FR2629186A1 - SYSTEM AND METHOD FOR CONTROLLING THE POWER APPLIED TO AN AIR COOLING APPARATUS - Google Patents

Abstract

The invention relates to the control of air cooling devices. A control system for regulating the electric power which is applied to the refrigeration means 6, 26, 28 or to the defrosting means 13 of an appliance such as a domestic refrigerator, uses at least one piezoceramic relay 12. The power electrical is applied to the relay in dependence on control signals and the control circuit 19 is directly and ohmically connected to the power source. In one embodiment, a single piezoceramic relay switches the input electrical power between the refrigeration means and the defrost means. Application to refrigerators.

Description

The present invention relates to a communication circuit

  power station using at least one piezoelectric relay

  more particularly on the order

  by such means of a particular type of apparatus.

  We know that piezoelectric relays provide

  a means of establishing or interrupting the circulation of a

  to a device consisting of a load. A relay

  known piezoceramic type used for this purpose is de-

  written in U.S. patents Nos. 4,670,682 and 4,689,517, which were assigned to the applicant. The relay comprises a bending piezoceramic device which is formed by at least two pre-polarized plane piezoceramic plates, which are fixed in parallel and opposite orientations on

  opposite faces of at least one central conductive surface

  the, and which have external conductive surfaces that are

  isolated from each other and from the over-

  central conductive surface by the thicknesses of the piezoelectric blades

  respective intercalated ceramics. A movable contact associated with the bending device, which is movable, interacts with fixed contacts disposed proximate, so as to establish or interrupt an electrical circuit which circulates a current from a power source to the device consisting of a charge. A representative form of this type of relay, which is

  described in the above-mentioned prior patents, uses a

  piezoceramic positive flexion which is pre-polarized selectively

  veminent and which comprises locking means fixed on unpolarized parts, in position adjacent to the device

  bending which is pre-biased selectively, and suppor-

  mechanically this device cantilevered for action-

  pairs of electrical contacts working together

  the unpolarized parts being electrically

  very much and not subject to any mechanical effort. The provision

  bending system is designed to work from

  of a central position which it normally takes when

  that it is not excited, to thus allow different modes of operation. In an operating mode, the relay

  can simply perform the function of a

  stopping, in which a pair of switch contacts

  Valiant jointly closes or opens the electrical circuit for the device that constitutes the load. However, in a different mode of operation, the contacts of the pair

  switch contacts working together are

  on both sides of the bending device to enable selective charging of multiple loads. With the "bimorph" type bend switching devices of the prior art, the two modes of operation are implemented in a similar manner, in which the continuous excitation potenie = i used to cause the flexion

  bending device has the same polarity as the

  pre-biasing current that is used to pre-bias the pre-polarized piezoceramic blade. The fact of using

  relay in this way avoids depolarization, which

  a dipole enhancement for relatively long-term operation with loads that operate with load voltages up to 5000 volts and

  corresponding currents amounting to hundreds of

fathers.

  In the two operating modes defined above

  above, it has been recognized that such piezoceramic relays pro-

  have important operating and structural benefits.

  relative to electromagnetic (EM) relays or semiconductor devices, when used

  in power switching applications. These advantages

  These are indicated in US Pat. No. 4,658,154,

  has been transferred to the plaintiff, which also describes

  Piezoceramic relay switching bakes for controlling single or double loads. EM relays which are still widely used for this purpose provide a

  interface between, for example, an electronic control circuit

  and a load circuit, in a configuration in the-

  the control circuit produces the low power control signals to selectively energize the relay coil to appropriately position the relay contacts that interact with the power circuit to

  switch relatively higher power levels.

  When such relay contacts are closed, a current of

  load is delivered, virtually without any loss, and

  that these contacts are separated, the charging current is in-

  with the certainty that only an air space can

  curer. Improvements in the EM relays that were introduced

  over the years have led to improved yield and reduced physical size. Such relays can be actuated with relatively high energy control signals.

  low, to switch between reasonable load current levels and

  sonnely high. There are for example EM relays that can be operated with a control signal of one watt for

  switch several kilowatts of power to an alternating voltage

  native of 115 or 230 volts. As a result, EM relays can be operated with signals produced by semiconductor control circuits. On the other hand, the disadvantages associated with EM relays used to control the flow of a current in load circuits, under

  the dependence of control signals, nevertheless remain important.

  tives. Although the current EM relays have been miniaturized compared to earlier relays, their requirements for excitation power are still very high.

  for example in comparison with

  modern semiconductor power transfer. Current EM relays are still relatively complex and difficult

  to manufacture; for example, their coils require

  feature a large number of turns of very fine wire. The resistance of the coil consumes a certain power which must be supplied by a reasonably robust power supply. For example, when EM relays are used in appliances control devices, the power supply of the relays must be obtained from the network

  115 or 230 V AC power. The necessary power supply

  particularly when an EM relay is associated

  to a semiconductor control circuit, requires

  transformer, electrolytic capacitors,

  gulators and protection, to provide a reliable source of current actuating relays. Such power supplies

  are expensive and constitute an important source of dissi-

  energy. In addition, in some applications in

  high ambient magnetic fields are pre-

  such as in engine starting applications, EM must be specially shielded to

  untimely operation. The disadvantages which are associated

  use of EM relays in communication circuits.

  This has led to a trend towards the use of semiconductor switching elements, such as triacs, thyristors, MOS field effect transistors, isolated control electrode transistors.

  (IGT), etc., for the output device ensuring the switching

  power generation. Although such semiconductor switching elements have become relatively economical and although they may have a smaller physical size than

  that of EM relays of comparable characteristics, they

  actually feel a noticeable resistance to the conductive

  which results in considerable power dissipation

  ble at high current levels. The elements of comnfuta-

  semiconductor power supplies that are used in high-current applications must therefore be

  radiator suitable for protection against

  of thermal origin, and under these conditions, with their radiators, these devices may occupy more

  space than the equivalent EM relays. In addition, the

  semiconductor power switching

  be protected against possible damage by a

  abnormal reaction due to transients, discharges

  electrostatic and electromagnetic disturbances. always

  these protective measures represent an additional cost

  silent. Insofar as such semiconductor power switching elements do not impose an air gap to prevent the flow of current in their off state, and because of their mode of failure in the conductive state,

  certification body Underwriters.Laboratory has

  their use in many household appliances.

  This prohibition could only be partially overcome with a combination of semiconductor switching elements

  series-connected relays in certain home appliances

  ticks, so as to establish the required air space.

  All the previous major disadvantages that we

  encounter in the use of EM relays or commu-

  As a power switching output device, there has been renewed interest in piezoelectric relays, including piezoceramic relays. Recent improvements made to

  piezoceramic materials have improved their electrical efficiency.

  mechanical for these relay applications. We can manufacture

  piezoceramic training elements from a cer-

  a number of different polycrystalline ceramic materials such as barium titanate, lead zirconate-titanate, lead metaniobate, etc., which are pre-molded and fired

  with a desired shape, such as for example ceramic blades

  rectangular shape. The piezoceramic relays required

  very weak actuating currents, they dissipate

  a minimum power to maintain an action-state

  born, and they do not absorb any current when they are in their

  state of rest or state not excited. The electrical characteristics

  of the piezoceramic training elements are

  damental capacitive nature, and these elements are therefore virtually insensitive to ambient electromagnetic fields. Such piezoceramic relays can be made with

  a smaller physical size than that of EM relays of

  comparable characteristics. Such piezoceramic relays use switch contacts, and the separation of the contacts introduces into the charging circuit the air gap that is required for approval by the U.L. in the case of household appliances applications. The

  closing of these relay contacts establishes a path of

  of negligible resistance, which means that there is no

  There is no loss in the charging circuit, unlike in the case of power switching

  semiconductor. Other advantages of structure and function

  Such improved piezoceramic relays are disclosed in U.S. patents. Nos. 4,670,682 and 4,689

517 above.

  There are of course other factors to be considered with respect to the possibility of using such piezoceramic relays for controlling traffic.

  current to a particular device. It is necessary at the same time

  maintain the desired functional characteristics in the application

  the same and take into account the environmental conditions that are

  encountered. For example, a major

  cooling of domestic air, namely refrigeration

  household, uses refrigeration equipment to

  to keep the contents of a storage compartment,

  - while de-icing means are usually incor-

  pores to eliminate the accumulation of frost that forms on

  the refrigeration evaporator surfaces. It is desirable

  to control the operation of this appliance,

  as well as other similar air coolers

  res, so that they work directly from the

  mains voltage available, with a minimum of

  in the control circuit, and further reducing the sensitivity of the control circuit to electromagnetic disturbances and transients in the sector. The use of at least one piezoceramic relay in the control circuit could theoretically allow

  switch current flow between the means of

  management and defrosting in such a cooling apparatus

  air, with excellent performance and immunity from

  to ambient electromagnetic fields. The re-

  piezoceramic lais are also particularly suitable for

  for use in combination with

  electronic circuits with low consumption, intended to

  the control signals to operate the piezoelectric device

  zoceramic bending, and to allow opening or

  closing the relay contacts. It would furthermore be desirable

  to replace the separate control means which are

  Currently available in a representative type of air cooling apparatus, for individually controlling the refrigerating and defrosting means, by a single control unit employing at least one piezoceramic relay. Such a simplification would be particularly advantageous for the household refrigerating appliance envisaged above, because of the fact that

  that it allows for more space for conserva-

  of food and makes it easier to house the whole

  control means inside the apparatus, for

look more aesthetic.

  The aptitude of a piezoceramic relay and its cir-

  control cookware associated with operating properly in a relatively high humidity and temperature environment

  relatively low that is associated with a cooling device

  of air, is obviously another consideration

  important. Relay contacts must open and close

  sea reliably in this operating environment,

2629186 '

  the relatively long life that is required for most refrigeration appliances. Although it has been found that piezoceramic relays are capable of reliable long-term operation, it must be recognized that there are still significant contact problems, and that these have not been mitigated so far. than by the use of additional circuits. Specifically, arcs are formed between the contacts for various reasons at the time of opening and closing of the relay contacts, and this has required the use of additional circuits to reduce wear and disintegration at the surface of the contacts. contact. The problem of armoring an arc at the moment of opening of the contacts is attributed to a rise in the direct potential which is reapplied between the contacts at the moment of their opening, and this potential can be reduced by means of circuits dampers, as

  proposed in the two patents Nos. 4,658,154 and 4,670,682

  your. The problem of priming an arc at the moment of * closing

  Such contact is caused by a mechanical rebound of the contacts upon closing, and this problem is addressed in another U.S. Patent No. 4,626,698, which was also assigned to the Applicant. The latter patent proposes to use with a piezoceramic relay new circuits comprising

  circuit elements intended to initially apply a voltage

  relatively low excitation voltage to the piezocera-

  flexion, to slow down its movement and reduce

  jumping of contacts after their initial closure. This patent also proposes to operate such circuits so as to cut off the flow of current through the contacts.

  at the moment of their opening, to help mitigate

  arc priming problem initially mentioned. We can appreciate

  the severity of the two arc ignition problems by

  an additional recommendation in the patent

  above, which advocates the use of special contact metals

  to support the formation of an arc whenever

Relay contacts are separated.

  Recent legislation in many states now requires performance standards to be met

  energy saving for household appliances. For an appa-

  domestic air cooling system, which includes the

  refrigerators, air conditioners, heat pumps, etc., such a requirement obviously imposes a good use of

  the electrical power both in the refrigeration

  only in the de-icing means. A major problem

  in this respect is the result of the way in which

  de-icing means in a large number of

  domestic air cooling lines that are used at present. For example, a household refrigerator

  feature controls the operation of the drive motor

  pressure in the refrigeration means using a heat

  mostat, depending on the temperature that is detected. The associated de-icing means are controlled by the energizing of a defrost heating element which operates at

  periodic intervals dependent on a temporisa-

  tor. Because the temporal characteristics of the cycle of

  defrosting are set by the manufacturer at the time of

  brication, nothing is planned to vary the cycle of

  icing as a function of changes in the operating environment. Therefore, the interval during which the deicing means is turned on remains constant

  despite significant fluctuations in the humidity of the environ-

  when a user operates the device. It thus becomes possible for the deicing means to heat

  excessively the surfaces of the evaporator in a

  low humidity, and this has led to the incorporation of

  additional thermostat for the interruption of the

  deicing key, as a precaution. In addition, the trend

  the current situation of housing inside the device the

  Apparently the control system for a household refrigerator and other air-cooling appliances for domestic use, for aesthetic purposes as well as to reduce wiring costs, has additional disadvantages. Engine

  the defrost timer is now subject to

  ambient conditions corresponding to very high humidity and very low temperatures, and this motor also produces heat which must be absorbed by the cooling means.

  gération. This last disadvantage obviously reduces the

  overall thermal performance of the particular device, which makes

  much more difficult to meet the minimum standards

  concerning the energy efficiency of domestic appliances

  c. When you consider these energy efficiency standards,

  it is also obvious that an appropriate order

  of an air-cooling apparatus comprising both refrigeration and de-icing means

  prohibit any simultaneous operation of the respective means.

  As indicated in the patent No. 4,658,154

  above mentioned, it is possible to operate a piezo relay

  ceramic with minimal power consumption,

  to regulate the power that is applied to a pair of

  resistive loads, in a way that prevents any functioning

  simultaneously the respective charges. This patent indicates that such a control of the operation of the relay uses

  high-voltage integrated circuits which are directly

  from a conventional source of electrical energy, such as

  the alternative sources available at 115 volts or 230 volts. For such a relay control circuit to regulate reliably and with good efficiency the power that is applied to an air cooling apparatus comprising

  either means of refrigeration alone or means of

  refrigeration functionally associated with means of

  icing, however, it is necessary to satisfy various

  very important criteria. With regard to essential criteria

  applicable to the regulation of the input power which is applied to the refrigeration means or the means of

  defrosting, we can obviously mention the need for

  efficiency of the power consumed, reliable operation

  In the long run, selected power switching devices and relatively low costs associated with the hardware realization of selected power switching means in a particular apparatus. Such criteria can be further illustrated in relation to

  are currently used in refrigeration equipment.

  typical household type. The means of refrigeration

  conventional temperature control in one or more

  food storage compartments, using a thermo-

  mostat which drives the compressor motor according to the

  temperature that is detected. Conventional de-icing means

  control the operation of the heating element

  defrosting with a timer motor, so that a

  defrost key is triggered when a time interval

  fixed refrigeration equipment has been

  the. Since the cycle of the defrost timer is generally

  usually fixed to provide proper defrosting in a

  environment with high humidity and with intensive use

  the de-icing capacity is excessive when the

  the same works in a low humidity environment. he

  As a result, the use of energy is often

  than the optimum in the conventional power control system, and that a control algorithm using less

  of energy would be advantageous. We would obtain additional benefits

  by replacing the separate electrical control means which currently operate the refrigeration and defrosting means in the conventional apparatus, by

* a single control unit employing a piezoceramic relay.

  It would thus be possible to reduce wiring costs in the appliance while increasing the reliability of operation, because of simple electrical interconnections. The appearance of reliable and economical microprocessor control circuits

  as shown by their wide use in many

  current domestic standards, offers the possibility of

  automatically plotting to a piezoceramic relay actuating signals that satisfy the control algorithm defined above, for a characteristic type air cooling apparatus. By doing so, we could program a

  integrated circuit available commercially, so as to

  the logic and timing commands required to execute a selected control algorithm, with control signals developed in a way that allows

  operate additional integrated circuits that

  the piezoceramic relay. The resulting control circuit could then be connected directly and ohmically to a

  appropriate source of energy and at the piezo relay relay terminal.

  in order to minimize the operating power requirements, the relay then automatically react

  deforming in a first direction to establish a

  electric cooking between the energy source and the means of

  refrigeration, or deforming in a second direction to establish an electrical circuit between the power source and

  the deicing means; all in a relatively

  vorable from the point of view of security in case of default.

  A more detailed understanding of the classical control algorithm is necessary to design simpler and more reliable control means, and also having a

  better energy efficiency, for the regulation of

  electrical system for refrigeration or de-icing means

  which are employed in a typical air-cooling apparatus. In the typical household refrigerator considered above, the control algorithm currently being used establishes a fixed daily time interval for defrosting, instead of performing the

  defrost when necessary. More specifically, the system

  This refrigeration control system consists of two

  power control units. 'The first corre-

  to the conventional cold control which consists of a heat

  hydraulic bulb, which controls the compressor motor.

  depending on the detected temperature. The algorithm of

  conventional cold control, which differs from a true asser-

  temperature control, exerts temperature control on the frozen food and fresh food compartments in mutual connection in the refrigerator, with a single temperature set point. Because conventional refrigeration systems reach their maximum efficiency only if

  the compressor is left running for a sufficient time

  particularly long, such as fifteen to forty five minutes, to reach steady-state conditions, the

  present cold control is a design compromise between tight control of the setpoint temperature and a

  proper operation of the refrigeration system itself. During this minimum period of operation of the

  compressor, the temperature in one or other of the two

  The units may go beyond the desired temperature, but an attempt to minimize the overrun will reduce the energy efficiency of the refrigerator. It is also obvious that every time a warm thermal load

  is introduced into one or other of the food compartments

  ments, a thermal transient occurs. An appropriate cold control is achieved by controlling the temperature in

  the fresh food compartment. In the means of refrigeration

  conventional control, the temperature of the air leaving the evaporator is controlled by using a long time constant thermostat, so that short disturbances of

  the outlet temperature do not operate the control

  of temperature. The air coming out of the evaporator section

  is cold compared to the air coming from the compartment

  fresh food because it is a mixture of

  air circulation in the fresh food compartment and

  part of frozen foods. The cold control present therefore requires a significant hysteresis, such as 5.5-7.2 C

  for stable operation. This hysteresis also guarantees

  the minimum running and stopping times for

  pressure, because of the time constant of the evaporator and

  of the thermostat. The minimum duration of operation is neces-

  to ensure that the operation is carried out with a good

  while the minimum stopping time is necessary for

  the refrigerant gas pressure is equalized, so that the

  compressor does not attempt to start with a counter-

  high pressure. By using the temperature of the air

  of the evaporator, a parameter is introduced to the extent that depends both on the fresh food compartment and the frozen food compartment, since the air coming from the

  both compartments mix in the evaporator. The utili-

  Moreover, the temperature of the outlet air allows a certain degree of thermal anticipation to be introduced into the air.

  temperature control system, which has the effect of

  nimise the levels of temperature

  feast in the fresh food compartment, and thus limit the damage that is caused to loads having a low thermal mass, such as lettuce. The means of

  conventional refrigeration systems also include

  by the user, to adjust the temperatures of the

  compartments, in a configuration that otherwise corresponds to

  their to a closed loop temperature control. The Your-

  conventional cold control means depends in

  in addition to the altitude at which the device operates. Contrary

  to the means of temperature control for the

  operation of conventional refrigeration equipment, the se-

  Average defrost control conds in the conventional apparatus initiate a defrost cycle with a timer that controls the defrost heater, so that it operates for a fixed time interval. A 500-watt heating element is typically used to periodically melt the frost that has accumulated on the

  evaporator surface, in order to maintain the energy efficiency

  geometry of the refrigeration apparatus. Current defrost timers typically initiate a defrost cycle each time the compressor in the refrigeration means has been operating for a fixed number of hours. We

  do this by plugging the defrost timer into

  Raises on the compressor motor. The cycle of temporisa-

  current de-icer is also being adapted

  special types of refrigerators, in which the defrost cycle is currently

  times for each period of eight to sixteen hours of

  compressor, depending on the structure of the sample.

  heat of the particular refrigerator. The heating element

  classic defrosting is thus energized during

  a maximum of half an hour, followed by a short

  stopping the compressor for pressure equalization

  and the temperature of the gas in the refrigeration means.

  Current defrosting means of fixed duration have a poor performance when operating the refrigerator in a

  low humidity environment, or when it is

  with a low-intensity use, in which a very small amount of frost accumulates on the surfaces of the evaporator, so that the evaporator is brought to very high temperatures when the 500-watt heating element is set energized for the duration of thirty minutes

  which is only necessary for a strong accumulation of frost.

  Due to such an overheating possibility, the conventional control system generally further includes a defrost stop thermostat system that cuts the power applied to the defrost heater each

  the evaporator reaches a temperature set at

  this. It is understood that incorporating this control system

  in the energy compartment.

  parts of the device subjects all components to an environ-

  high humidity and low temperature, and requires

  The refrigeration means absorb additional thermal loads which are generated by the control system itself. The need for a control algorithm

  having a better energy efficiency appears in a

  core more obvious when considering important work

  currently being carried out with the aim of developing

  per frost detection means to replace the means

  Conventional fixed time defrosting devices.

  The main purpose of the invention is to provide a system

  energy-efficient system for regulating

  tion of the electrical power applied to the means

  refrigeration and defrosting systems that are used in a

like air cooling.

  Another important object of the invention is to provide

  control means employing at least one piezoelectric relay

  ceramic, to regulate the electrical power that is applied

  to an air cooling device, in a manner

  providing better security in the event of a fault.

  An additional important object of the invention is to provide control means for regulating the

  electrical power that is applied to a

  air cooling, which do not use an electromechanical timer.

  Another important object of the invention is to provide

  sophisticated electronic control

  automatic regulation of the electrical power which is

  plicated to an air cooling device.

  Another important object of the invention is to provide

  perform an original process for regulating the electrical power applied to an air cooling unit.

  Another important object of the invention is to provide

  To provide a method for operating a piezoceramic relay so as to better regulate the electrical power that is applied to an air cooling apparatus.

  Another important object of the invention is to provide

  a process with better efficiency to regulate self-

  the electrical power applied to an application

like air cooling.

  Another important object of the invention is to provide

  an air cooler having a better

  performance, which uses new control

  gulate the electrical power that is applied to the means of

refrigeration and defrosting.

  Another important object of the invention is to provide

  an air cooling unit that uses simpler control means to regulate the

  electrically applied, using piezoceramic relay

c.

  Another important object of the invention is to provide

  an air cooling device employing

  electronic control systems to automatically regulate

  the electric power that is applied to the means

  refrigeration and defrosting.

  Another important object of the invention is to provide

  a domestic air cooling device using

  new control means to regulate the electrical power

  which is applied to the means of refrigeration and

icing.

  Another important object of the invention is to provide

  a household refrigerator employing new control means to automatically regulate electrical power,

  between the refrigeration and defrosting means.

  These and other objects of the invention are

  draw from the detailed description of the invention which is

below.

  New control means have been discovered for regulating the electrical power which is applied to refrigeration means or de-icing means employed in an air cooling apparatus, which make it possible to obtain

  all the desirable improvements mentioned above.

  According to one aspect of the invention, an improved control algorithm operates de-icing means in response to control signals which are determined by the operating time interval of cooling means, but the operation of the means Defrost is

  now more responsive to actual deicing needs.

  Although these advanced de-icing means work

  during a fixed time interval, the defrost cycle de-

  hangs in the time that the triggering of the defrosting cycle depends on the operation of the refrigeration means,

  that is to say, it takes place either at the end of a period of

  a predetermined value, ie when an interval value of

  predetermined operating time of the refrigeration means

  is exceeded. An additional feature of

  time dependence in such an improved control algorithm allows the operation of the de-icing means in dependence on the control signals, whereby the

  defrost cycle can be triggered as a result of

  period of time after the function

  preceding of these means. The following explanation further illustrates an appropriate way to implement such a

  an advanced control algorithm for a metal refrigerator

  swim of characteristic type. A control circuit controls the operating time of the compressor in the means of

  refrigeration, to establish a function interval value

  tion, and this operating interval value is

  defined as the difference between the duration during the

  which compressor is running and how long

  the compressor has been stopped. Therefore, if refrigeration

  for four hours with the compressor in

  operation for three hours and stopped for a

  re, the operating interval value at this time is two hours. If during the same four-hour period the compressor ran for two hours and was then

  stopped for two hours, the interval value of

  This is equal to zero because the operating time interval of the compressor does not exceed the timeout interval. Similarly, if the compressor has been running for one hour and stopped for three hours in a four-hour period, the operating interval value is always zero, because in the order present, this value

  is defined as a positive number. A cycle of

  is triggered each time the operation interval value exceeds a predetermined value, or each

  time that the compressor's operating time

  a long time, such as forty-eight hours,

  elapsed since the last defrost cycle.

  According to a different aspect of the invention,

  a single control unit to regulate the power between the compressor motor of the refrigeration means and

  the defrost heating element in the deicing means.

  A single piezoceramic relay performs power switching with low power consumption, in a representative embodiment, and the control circuit which

  operates the relay also functions in a comparable manner.

  corn. In this embodiment, the bending device of the piezo ceramic relay is actuated to move from one

  side or other of a central position that takes normal-

  this device in a non-excited condition, and the cir-

  control is directly and ohmically connected to an available alternative energy source, as well as

  piezoceramic relay terminal, so as to react to

  control devices by operating the piezo-ceramic bending device, whereby the bending device deforms a bending motion in a first direction to establish a circuit between the alternative energy source and the terminal

  means of refrigeration, or it is deformed by a movement

  bending in a second direction to establish a circuit between the AC power source and the dice terminal

  deicing means. In such a mode of operation,

  frant a relatively good security in case of default, it is

  obvious that such a control unit can never trigger

  simultaneously cooling and heating, and virtually no electrical power is required to maintain the electrical contacts of the relay in a closed operating state. A preferred piezoceramic relay allows

  so much to implement such a mode of operation

  federation uses the aforementioned "bimorph" structure in the

  wherein the bending piezoceramic device is formed by at least two planar and pre-polarized piezoceramic plates, which are fixed in parallel and opposite orientations on opposite sides of at least one central conductive surface, and which have outer conductive surfaces which are insulated from each other and with respect to the central conductive surface by the thicknesses of the respective interposed piezoceramic blades. The mobile electrical contact means that are functionally associated with the

  piezo-ceramic bending device, movable, can be

  placed on the same side or on opposite sides of the device to

  bending, and they can also be placed in positions

  lateral arrangements, or even positioned on elements

  extend from the bending device and which are mechanically

  nally coupled thereto, all of which are described in more detail below and in the aforementioned patents. A further preferred form of the piezo-ceramic bending device having the "bimorph" structure is pre-biased selectively, and locking means are secured in unpolarized portions, which are adjacent to the baffle device.

  pre-polarized flexion selectively and mechanically support

  the latter in a cantilevered position to operate one or more

  sieur pairs of electrical contacts working together

  the unpolarized parts are not subject to any

  mechanical stress and being electrically neutral.

  The control circuit that operates the piezo ceramic relay with low power consumption is connected in

  circuit with respective ones of the piezoceramic blades

  pre-polarized, to apply a continuous potential for ex-

  citation causing the selective deformation of the bending device, in response to control signals that are developed during the operation of associated refrigerating or defrosting means. The continuous potential of excitement

  is preferably applied with the same polarity as the

  Pre-polarization wave which is used to polarize the piezoceramic slides, so as not to depolarize the relay during operation. The relay can be operated under

  the effect of the control signals by means of an electronic circuit

  associated partner that consumes a weak power. More precise-

  ment, an appropriate relay driver for the refrigeration

  householdgenerator.considered above, may include simple-

  a diode-capacitor array for producing the high-voltage DC excitation potential for operating the piezoceramic relay, in combination with voltage drop resistors for the control logic and active semiconductor devices, for to selectively apply the high excitation voltage to

  piezo ceramic bending device. In such a circuit of

  a series-connected isolation resistor can be provided to limit the current that is absorbed-from a

  alternative energy source, while a resistance of

  can also be planned to direct the potential of ex-

  quote to the piezo-ceramic bending device. Such driving circuit embodiments may also include additional resistance for discharging the first piezoceramic blade when its excitation has ceased, and a second resistor for discharging the second piezoceramic blade when its excitation has ceased. Automatic switching of the relay contacts can be performed at

  means of a functionally associated electronic circuit,

  for example, reading various available integrated circuits. By way of example, a CMOS control circuit can be programmed in a known manner so as to introduce into the latter all the temperature and time values making it possible to regulate in this manner an air cooling apparatus which is controlled. . Such a representative type digital integrated circuit is simply programmed in the known manner, by establishing maximum temperature and minimum temperature set points for the temperature control of the refrigeration means, so that the compressor is

  actuated at a predetermined temperature and that its function

  stopping at a second temperature, of lower value than

  re. It is possible to develop time control signals

  additional costs for the automatic operation of the refrigeration equipment, if the software used for

  In addition, programming responds to user input

  setting desired temperature levels in one or more food storage compartments. he

  It is thus possible to adapt specifically to the application

  A semiconductor chip device is provided for generating control signals for operating the de-icing means according to a plurality of predetermined time sequences. The initiation of the defrost cycle can simply be determined by means of time signals which

  are established by counting cycles of alternating voltage

  sector at 50 or 60 Hz available. With such a representative control unit, the associated integrated circuit

  performs all the functions of definition of characteris-

  time, temperature sensing, and relay drive measurements that are required for the control algorithm, requiring only a minimal number of components

  external circuitry in the overall control circuit.

  The use of such built-in or built-in temperature sensing eliminates the need for separate boot and component connection

  sensor and polarization that would otherwise be required.

  sary. Other integrated circuits can therefore be used.

  similar grids in the overall control circuit present to directly attack the piezo-ceramic relay from

  of an integrated circuit, such as a circuit made with

* high voltage MOS nology, which is already manufactured

  LEMENT. As a further illustration, it should be noted that such an integrated circuit marketed at present supports a voltage of 500 volts and uses low current consumption driving transistors (10-20 milliamps) for active devices which can be placed further down the

  integrated circuit chip. In a similar way, we can pro-

  grammer other integrated circuits known to fulfill all the functions of definition of temporal characteristics,

  of temperature measurement and relay attack that are ne-

  in the control circuit present. As an example

  ple, it would also be possible to use an integrated circuit

  simple option, based on microprocessor control in

  CMOS technology, able to perform on the

  analog-to-digital version, allowing the conversion of

  User setpoint and temperature feedback signals, within this control circuit, with a minimum of external components. We also see that it is possible to use various types of semiconductor elements other than transistors, for active devices, in

  the overall control circuit envisaged above. We are

  There are many technologies for the manufacture of high-voltage and low-current devices which are

  applicable to the control circuit present, as

  CMOS, DMOS, PHMOS, NMOS, etc. High voltage and low current are understood to mean voltages in the range of 300 to

  600 volts and currents of the order of a few milliamperes.

  Usable circuits include the monolithic FET DMOS networks offered by Supertex Inc. (2NT001), the Siliconix 2N9001-type MOS-FETs, and the ET012PC-based GTO transistors offered by Hitachi. Hereinafter will be described in more detail, in connection with the following preferred embodiments, a flowchart for

  a typical software which allows a functioning

  fully automated in a type of cooling device

  of air using refrigeration and de-icing means.

  vrage. The use of the regulation embodiments

  described above makes it possible to save

  considerable energy costs. Such a representative type of control unit contributes in three main ways to

  energy savings. As will be explained in more detail

  cut in connection with a household refrigerator type

  feature, the first reduction in consumption results

  lower power dissipation in the

  food preservation, because of the replacement of the

  electromechanical timer by means of a control circuit

  summoning less power. We consider that we obtain

  similarly a second reduction in consumption because of

  number of defrost cycles that can be achieved

  hold by the use of a perfect control algorithm

  tioned. A third reduction in consumption can be obtained.

  by operating the compressor with a minimum number of starts and stops, which should increase the thermal efficiency of the refrigeration means. Because the conventional timer engine consumes approximately 3.9 kilowatt hours per year during operation, while

  the additional energy that the compressor must

  for this heat is about 9.8 kilowatt hours per year, the conventional control system currently consumes a total of 13.7 kilowatt hours per year. The replacement of the conventional control structure with a CMOS electronic control circuit having a consumption of the order of 1.5 kilowatt-hours per year should provide an annual energy saving of 12.2 kilowatt-hours. More importantly, however, is the energy consumed by the conventional refrigerator to operate the defrost heater for up to half an hour for each 8-16 hours of compressor operation. There can be 650 defrost cycles per year, which in the conventional device

  leads to an energy consumption of around 164 kilowatts

  hours that is due only to defrost cycles. The UTI

  implementation of the improved control algorithm envisaged

  above should reduce the annual number of degassing cycles

  only 182 cycles in the same environment, saving 116 kilowatt hours per year, assuming the conventional defrost

10. 500 watt power.

  According to still other different aspects of the invention,

  in connection with an air cooling device

  comprising refrigeration means functionally

  together with de-icing means, the present control unit can be modified so as to allow the regulation of the power which is applied to the refrigeration means and to the

  de-icing means with an individual piezoceramic relay.

  Thus, the regulation of the power that is applied to

  representative type of refrigeration equipment uses a first

  first relay of this type which is connected in a circuit to allow the connection to the refrigeration means, the piezoceramic relay comprising a terminal provided for connection to the energy source, and a movable and pre-biased piezoceramic device for bending, which has movable electrical contact means which work in association

  with stationary electrical contact means placed near

  the fixed electrical contact means being connected to

  a terminal of the refrigeration means, and the piezoelectric device

  bending ceramic now the means of electrical contact

  movable spacers with respect to the stationary electrical contact means when in a non-energized condition, and a control circuit which is connected directly and

  ohmic to the power source and to the piezo relay relay

  ramique, and which operates under control signals to actuate the movable piezo-ceramic bending device, and which causes the bending device to

  distorts a bending movement and establishes a circuit

  be the source of energy and the terminal of the refrigeration

  tion. Control signals for actuation of this piezoceramic relay can be provided by means of a temperature control, as indicated above, so that the actuation occurs at a predetermined temperature and

  ceases at a lower predetermined temperature. The regulation

  tion of the power applied to means of

  type. representative in the cooling apparatus

  The air supply shown here uses a second relay relay.

  zoceramic which is connected in a circuit to allow connection to the deicing means, the piezoceramic relay comprising a terminal provided for the connection to the power source and a piezo-ceramic device for bending, moving and

  pre-polarized circuit, comprising means of electrical contact mod-

  who work in association with means of

  fixed electrical contacts placed nearby, the means of

  fixed electrical contacts being connected to a terminal means

  defrosting device, and the piezo-ceramic device

  holding the moving electrical contact means spaced apart from the stationary electrical contact means when in a non-energized position, and a control circuit which is directly and ohmically connected to the power source

  and a terminal of the piezo-ceramic relay, which reacts to

  control gears by operating the movable bending piezoceramic device and causing the bending device to deform a bending motion and establish a circuit between the power source and the terminal of the deicing means. As indicated above, the control signals for actuation of the second piezoceramic relay can

  be developed in accordance with the perfected control algorithm

  As previously indicated, the time interval during which the deicing means is actuated is determined by the operating time interval of the functionally associated refrigeration means. It is also possible to incorporate in such an embodiment with several relays structure and / or circuit elements

  known, preventing simultaneous operation of the relays.

  The use of a piezoceramic relay in the way

  described in any one of the preceding embodiments

  has a number of important advantages in terms of

  the power regulation for a cooling device

  air supply. For this purpose a number of electromagnetic relays are used in the conventional apparatus, and these

  relays are placed in different positions in the device.

  The power consumed by these relays further requires using for the associated control circuit wiring sufficiently robust to withstand high power. The requirements of

  reduced power and the simple structure of the piezoelectric relay

  ramique now allow to place in a central position, in a minimal space, the whole of the control unit for

  the device, which significantly reduces cable costs.

  ge. It is now possible, in connection with others

  aspects of the invention, to make the control unit per-

  made in the form of a single plug-in module, allowing replacement or repair in a very

  more convenient. The conventional apparatus also uses a heat

  mostat for the temperature control of refrigeration

  as de-icing means, for the purpose of producing control signals having a power level sufficient for. operate the functionally associated electromagnetic relays. A disadvantage that we encounter at present

  with the electromechanical temperature control means

  canic, consists in the absence of control outside the controlled temperature band of the thermostat. Possibility

  to operate a piezoceramic relay with an electronic circuit

  operating at a lower power level, now allows the use of temperature control means

  electronic devices, such as a semiconductor device

  both in a thermistor. The temperature detection means

  electronic devices produce a continuous feedback signal over a much larger temperature range than is required in an air cooling apparatus, and can therefore be used to produce

  control based on temperature conditions that appear

  inside and outside the temperature band

  controlled. A particularly important point in this respect is

  side in the elimination of current practice in an appa-

  conventional air cooling system, which consists of

  put the operation for long durations when the

  temperature in the device is outside the ban-

  of controlled temperature that is selected by a user

  sateur. Such operation may cause excessive heating of the compressor motor, so that it becomes desirable to mitigate such excessive operating condition, by means of a continuous temperature feedback control signal, whenever the compressor motor is overheated. device is put under

  voltage. Obtaining a more precise temperature control

  the device, by such means, still presents from

  benefits, including the avoidance of a freeze cycle in items that are refrigerated. In addition, we can now make sure that a refrigerator

  household responds much more sensitively to a variety of

  the thermal loads to which the apparatus is subjected by the use of the user, such as the opening of doors with seals, or the introduction of lukewarm articles into the food storage compartments. There is no

  no difficulty in applying such control signals.

  improved temperature to a piezoceramic relay regulating the power that is applied to a cooling device

  air. The aforementioned electronic control circuit

  demister, which is functionally associated with the relay, may simply comprise a thermistor semiconductor element, connected in an already known circuit configuration, with temperature set points for its

  operation, and with a time set point

  set by the user in the case of refrigerated

household.

  Still other aspects of the invention

  to further improve-the operation of the means of de-icing

  in an air cooling unit. The elements

  radiant energy heaters that are used on a

  in conventional appliances have poor energy efficiency since they use much more electricity than is necessary to

  melt the accumulation of frost, especially when

  also amazes all the additional thermal energy that

  must be removed by the associated refrigeration means.

  It has now been found that it is possible to replace

  conventional defrosting means by an electric heating element

  positive temperature coefficient (PTC), with the

  possibility of considerable energy savings.

  Such PTC heating means include electrical cables.

  already widely used, often wrapped around water pipes to protect them from freezing, or used to de-ice roof gutters, and the electrical resistance of the cable increases rapidly so that The device produces very little heat at around 60 C. A commercially available cable of this type is currently sold by Raychem Corporation, as well as by Ensign-Bickford and other suppliers. A

  Characteristic type cable structure comprises two

  parallel copper conductors surrounded by a heating element

  polyethylene with a carbon charge, which is electrically

  triply isolated by a polyethylene sheath. To improve defrost efficiency in a cooling device

  of air, the heating cable can simply be

  the fins normally used in the evaporator section of conventional refrigeration equipment, or

  it can be placed in close physical proximity to the fins.

  In this environment, cable has a significant increase

  electrical resistance above 50 C, which limits the power that is dissipated and the final temperature that is reached. In particular, if there is no frost at a location in the evaporator, the cable becomes warmer,

  which increases its electrical impedance and therefore decreases the power

  it consumes. In this way, the cable regulates

  and with good efficiency the heat that is applied

  to the entire surface of the evaporator which is

  defrosting, and it behaves basically like a continuously distributed length of integrated heaters, in parallel. Obviously, this type of deicing means reduces both the cost of operation and the quality of food preservation. Certain other materials, including barium titanate, vanadium compounds and other charge-containing and electrically conductive polymers, exhibit

  similar nonlinear resistance in the presence of a

  temperature, and therefore may also be useful for these improved deicing means. We are considering

  therefore, in addition to using such de-icing means perfected

  in combination with the means of regulating

  of the invention. We can find a presentation even more

  the various de-icing techniques that have been

  bent in air coolers, and their modes of operation, in a technical publication entitled "Refrigeration Control Systems" AIEE Paper 60CPA5026,

presented on May 16-17, 1960.

  The rest of the description refers to the drawings

  nexes which represent respectively:

  Figure 1: a front view in perspective of a

  household refrigerator of a typical type, comprising a

  form of the improved control unit considered here.

  Figure 2: an electrical circuit diagram of a control unit of a representative type that can be used

in the apparatus of Figure 1.

  Figure 3 is a more detailed representation of the structure of a typical type control module which includes the relay and the circuit shown in Figure 2. Figures 4A, 4B and 4C: side views in the direction

  of three different forms of a piezoelectric relay

  ramic type bimorph operable in the present control unit.

  Figure 5: a graphical representation of

  operating procedures of a relay shown on the

Figures 4A-4C.

  Figure 6: a circuit diagram of control means

  representative type of electronics, in accordance with the invention.

tion.

  Figure 7: A typical organization chart for the

  automated power control which is performed in

bending the circuit of Figure 6.

  Now considering the drawings more specifically, it is noted that the preferred embodiments of

  the invention are illustrated in connection with an apparatus for re-

  air cooling in the form of a household refrigerator,

  of the type more fully described in U.S.

  No. 4,543,799. This patent has been assigned to the applicant and the reader will be able to refer to it for more details. We see in Figure 1 a refrigerator cabinet including

  an exterior body 1, in which there is a

  frozen food preservation part 2, in the upper position, and a fresh food storage compartment 3, in the lower position. The two storage compartments are surrounded by an insulating material 4, and they further include access openings which are closed

  doors fitted with gaskets (not shown).

  FOA). Refrigeration for both compartments is ensured

  by an evaporator 5 which is placed between the two compartments.

  timings and means of refrigeration further include

  compressor 6 driven by an electric motor, and a condenser

  7. A fan 8 is placed in a conduit which connects the storage compartments, to provide a means for circulating air from the two compartments, thereby

  it passes on the evaporator 5 and returns to the

  compartments. A thermostat 9 is provided to automatically control

  The operation of the compressor 6 in order to maintain the temperature in the storage compartments in a controlled temperature range by means of a functionally associated relay control unit 10 which is housed in the fresh food storage compartment. . The evaporator 5 operates at lower temperatures. At the freezing point of the water

  and, in order to periodically eliminate the hoarfrost that accumulates

  mule on the surface of the evaporator, the apparatus comprises a defrost heating element 13 which is also operated periodically by the relay control unit

present.

  The operation of the control unit 10 of a type

  representative representative will emerge more clearly from the examination of

  circuit diagram of this unit, which is representative of

  Figure 2. More precisely, a single module of com-

  Mande 11 is incorporated in the fresh food compartment, and this module comprises a piezoceramic relay 12, for the purpose of regulating the electrical input power between the means

  refrigeration equipment and de-icing means in the refrigeration

  described above. For this purpose, the piezoceramic relay 12 is connected in a circuit configuration which allows the individual connection of the alternative energy source.

  domestic means of refrigeration or means of

  tion, and the piezoceramic relay includes a terminal 14 pre-

  view for connection to the alternative energy source, and a movable bending piezoceramic device, 15, which comprises

  a pair of movable electrical contact means 16 which

  in association with a pair of stationary electrical contact means 17 and 18 placed in proximity, and the pair of stationary electrical contact means are separately connected to terminals of the refrigerating and defrosting means, while the flexing device is controlled so as to deform on one side or the other of a central position that the device takes when it is at rest, that is to say in

  a position not excited, as shown in the drawing. A cir-

  fired 19, which is also housed in the control module 11, actuates the piezoceramic relay under the control signals, to ensure

  that the piezo-ceramic device with flexion, mobile and pre-

  15, is deformed by a bending movement in a first direction to establish a circuit between the alternative energy source and the terminal of the refrigeration means, or deforms and establishes an electrical circuit between the

  alternative source of energy and the terminal of the means of

  vrage. To operate the refrigerator in this control mode which prevents the simultaneous operation of the means of

  refrigeration and de-icing equipment, the engines of

  condenser and evaporator condensers, 26 and 28, are connected in parallel with a supply conductor 20,

  via the control module 11, and the drive motor

  presser 6 and the evaporator fan motors, 26, and the condenser fan, 28, have connections

  respective electrical return devices to the power supply

  remaining 22. A corresponding order is made

  defrosting means with a configuration in which the

  defrost heating element 13 is also connected in

  in the control circuit 19, via the control module 11, and an additional thermostat 32 is

  also connected in series with the heating element

  vrage. In the present controlled operating mode, the

  the time during which the de-icing means are

  controlled by the control signals, is de-

  terminated by the time interval of operation of the refrigeration means. Control signals for actuating

  in this way the de-icing means are fully

  in the control module that is shown, and these

  signals can also trigger the defrost cycle each

  that a predetermined operating time interval of the cooling means has elapsed. The module

  control can further develop control signals

  to initiate a defrost cycle following the lapse of a predetermined time interval after a previous defrost cycle. The control module exerts a similar control of the refrigeration means in the refrigerator embodiment that is shown. The thermostat 9 is thus used to provide control signals to the

  control module, to operate the compressor at a temperature of

  predetermined level, and to stop the operation

  compressor at a second temperature, lower value.

  This mode of operation can be implemented in a

  automatically in the control module, and for this purpose the

  dule develops first control signals that represent

  the difference between the detected temperature and the second time

  predetermined lower temperature, while the compressor

  until the temperature difference detects

  reaches zero, and at this point the electrical contacts of the

  piezoceramic relay controlling the operation of the compres-

  open. This temperature control band is

  depending on the altitude, and can be given as low a value as desired to avoid a continuous freeze and thaw of the foods that are kept. We can also

* introduce other modifications in the refrigeration means.

  ration which are shown, for the automated operation under the control module. It is thus possible to place frost detection means (not shown) adjacent to the surfaces of the evaporator, and it is possible to use in the control embodiment present

  command that are developed from these detection means.

  It is also possible to introduce thermal protection means

  refrigeration means, so that the control module automatically interrupts the

  compressor operation, if necessary.

  Figure 3 shows a more detailed representation of the structure of the control unit described in the mode of

  immediately preceding realization. As shown more by

  particularly in FIG. 2, the control module 11 physically contains all the control means which are necessary to regulate the input power which is applied to the refrigeration and defrosting means which are employed in

  the apparatus shown. Therefore, the piezoceramic relay

  12 and its control circuit 19 functionally associated are housed inside a box 21, and the terminals for the electrical connection to the refrigeration means

  and de-icing respective. The box comprises an isolating base

  27 which can conveniently be attached within the

  refrigerator, and it further includes a hood 29 to protect against the build-up of frost components

  that are inside. The piezo relay

  12 and its control circuit 19 are fixed on the insulating base 27, as are the power source connections 20 and 22 and the two connection terminals 23 and 25 which are associated with the refrigeration and defrosting means

  orders. As can also be seen in the drawing

  electrical connections start from a supply conductor 20 towards the control circuit 19, and

  are also associated with the mobile contacts 16A in the

  The remaining power conductor 22 is simply connected in series with the control circuit 19.

  and it is also connected outside of the communication module

  11 (this is not shown) to the refrigeration

  and the de-icing means, which makes it possible to establish power supply circuits to these means. Under these conditions the actuation of the mobile device, bending,

  under the control signals, causes the deformation

  bending device and establishing contact with one of the associated fixed electrical contacts 17 and 18 which

  are placed adjacent to the movable contact means

  the. When the bending device 15 is not excited, because no control signal is applied to it by the

  associated control circuit 19, the movable contacts 16A

  tent spaced relative to the two associated fixed electrical contacts. 17 and 18, which means that no electric power can be applied to the refrigeration

  de-icing means that are ordered.

  Figures 4A, 4B and 4C show side views,

  in a longitudinal orientation, three different structures

  rents for a bimorph type piezoceramic relay which can be used in the present control unit. The relay of FIG. 4A allows long-term reliable operation, as previously described in connection with FIGS. 1-3, in a configuration in which power is switched with a single relay between the refrigeration means and the means. defrosting. The relay shown in Figure 4B

  represents a different form of structure that makes it possible

  applying power to the refrigeration means or to the deicing means under the effect of the deformation, in the same direction, of elements with separate bending. The relay of FIG. 4C also represents another different structure which comprises remotely arranged movable contact means which are functionally associated with a single bending element and a remote terminal for the connection to the energy source. This last type of relay is also suitable for providing power to either the refrigeration means or the de-icing means, but it requires a pair of

  relay to provide power to both types of means.

  All relay embodiments that are shown

  However, they are operated in a similar way with the cir-

  present order, provided that a mo-

  bending bile is controlled so as to deform with a movement

  bending under the action of control signals, and to establish a circuit between the power source and terminals which

  are connected separately to the respective means in the

  ordered. For this reason, the same literal and numerical identifications on the present drawing are used to designate common structural elements in

  respective relays, as well as con-

  common connections, as far as possible.

  In FIG. 4A, the switching device 34 consisting of a bending piezoceramic device comprises at least two plane piezoceramic blades, namely a blade

  upper 36 and a lower blade 37, in the representation

  tion that is made on the drawing. Piezoceramic slides

  36 and 37 are set out in parallel and oppo-

  on opposite sides of at least one conductive surface

  39, and they have extruded conductive surfaces

  respectively 40 and 41 which are insulated one by one.

  port to the other and in relation to the central conducting surface

  on the 39th, by the thicknesses of the piezoceramic

  respective ones. The piezoceramic slides 36 and 37 may be of lead zirconate titanate, lead metaniobate, barium titanate or other known piezoceramic materials. Conductive surfaces 39, 40 and 41 may be

  nickel, silver or other similar conductive

  The flexion-type piezoceramic switching device further comprises a set of associated fixed electrical contacts, 42 and 43, which are mounted on relatively rigid support means. , and which may be sufficiently flexible to absorb shocks and close under the effect of the deformation of a portion of bending device, movable and

  pre-polarized, which is constituted by the piezoceramic blades 36A and 37A of the flexion-type switching device.

  Contacts 42 and 43 respectively work in partnership

2629186-

  with electrically isolated contacts 44 and 45 which are formed on the movable end of the bending device 36, 37 when the latter is actuated by control signals

  which are produced by the present control unit. By the-

  Bending mobile device members 36, 37 of the piezo ceramic switching device 34 are mechanically supported.

  cantilevered by blocking means represented at 46, -

  which serve both to mechanically maintain and clamp together the piezoceramic blades 36 and 37, with the central conductive surface 39 interposed between them. The locking means 46 are arranged on parts 36B and 37B

  piezoceramic slides 36 and 37 which have not been prepolarized

  and, therefore, unpolarized and electrically neutral, as opposed to the pre-polarized, active and movable bending device portions 36A and 37A, blades on which the contacts 44 and 45 are located. The locking means 46 are preferably placed on the ends of

  unpolarized portions 36B and 37B which are immediately ad-

  embedded, and physically integrated, at the ends of the pre-polarized, active and movable bending device portion,

  which consists of the blades 36A and 37A which have been

  polarized. It has also been found that by mounting the piezoelectric blades in this way, the number of failures due to the breaking of the ceramic material at the blade support points was considerably reduced. Terminals T3, T4 and

  a common terminal Tc provide the means by which a potential

  continuous tiel of excitation is selectively and respectively

  applied to the pre-bending device blade parts

  larized, active and mobile, 36A and 37A, under the effect

  control signals that are provided by the present control circuit 19 (not shown). This excitation potential, which is also applied by the control circuit, is

  so that the moving parts of the bending device

  selectively form and close their contacts 44 and 45 on one or the other of the respective associated fixed contacts, 42 and

2 629186

  43. Under the effect of the closure of an associated contact pair

  an electrical circuit is established between terminals L1 which are connected to the power source, and either

  additional terminals T1 and T2 which are connected separately

  in the cooling and defrosting means of the apparatus which is controlled. Therefore, a

  upward deflection of the bending device establishes a

  electrical cooking between the energy source and terminal T1, tan-

  say that a downward deflection of the bending device

  blit a similar circuit to terminal T2. At the moment of the suppression of the continuous potential of excitation which is applied to one or the other of the terminals T3, T4, the active mobile part of the bending device returns to its central neutral position, not excited, which has for effect of opening the game of

  associated contacts 42, 44 or 43, 45 which was closed.

  The piezo-ceramic bending type switching device 47 shown in FIG. 4B has a general structure similar to that of the relay embodiment described above, and therefore the same literal and numerical identifications have been retained to designate

  common structural elements in the relay present. This re-

  it differs in that it comprises a pair of bending device movable portions forming two branches, 36A, 37A and 36A ', 37A', which are separately actuated to establish electrical circuits to terminals T1 and T2. For this purpose, the movable contacts 44 and 45 are fixed on the same face of the individual movable bending device parts, respectively bearing the references 36A, 37A and 36A ', 37A', to allow the desired independent operation of the deicing means and refrigeration. Separate terminals are also established in association with the moving parts

  flexion devices, thanks to which a potential

  The continuous excitation circuit can be applied individually to the ceramic plates of each moving part of the bending device, and separate terminals are provided to establish the individual circuits between the power source and one of the

  controlled means. Thus, terminals T3, T4 and a common terminal

  T does not provide the means by which a continuous potential c of excitation is applied selectively and respectively to pre-polarized, active and movable bending device parts 36A and 37A, depending on the control signals, while than terminals T3, Tj and the common terminal

  You provide corresponding means for the parties to the

  c my bending device mobiles 36A 'and 37A'. Under the effect of the closure of the pair of associated contacts 42, 44, a

  electrical circuit is established between the terminal L1, which is con-

  connected to the energy source, and the terminal T1 which is connected to a terminal in the refrigeration means or in the deicing means. In a similar way, the closure of

  the pair of associated contacts 43, 45 establishes an electrical circuit

  between the L; terminal, which is also connected to the power source, and the T2 terminal which is connected to the others.

  means among the refrigeration and defrosting means.

  As can be seen from the drawing, the two cir-

  electric cookers are established by deforming the moving parts of the bending device with two branches, and the moving parts of the bending device

  maintain the means of associated contacts mutually es-

  paced when in a non-excited condition. Right here

  control signals such as the excitation potential

  allowing the separate actuation of the moving parts

  flexural devices are produced by the cir-

  cooked control 19 present (not shown).

  The switching device consisting of a

  piezo-ceramic bending positive, 48, shown in FIG. 4C, also has a general structure similar to that of the embodiment of FIG. 4A, so that here again

  the same literal and numerical identifications have been preserved.

  in the present drawing to designate the common structural elements. However, as can be seen in the present drawing, the use of a single pair of associated contact means in this relay embodiment allows

  to apply power to only one type of

  congestion or defrost). Thus, the piezoceramic slides 36 and 37 are fixed in parallel and opposite orientations

  on opposite sides of at least one central conductive surface

  and they have external conductive surfaces

  respective ones 40 and 41 which are insulated from each other and from the central conductive surface 39,

  by the thicknesses of the respective interspersed blades. The disc

  positive type of flexural type switching further comprises a pair of associated contact means 43, 45, which close

  under the effect of a downward deformation of a pre-

  polarized and movable bending device constituted by

  the piezoceramic slides 36A and 37A of the switching device

  bending. However, it can be noted in this respect that the

  movable contact 45 is arranged on a spring element

  electrically conductive 45A, and that the mobile part of

  positive to bending and the spring element are gathered together

  by an insulating block 46A, so as to have a common movement.

  By establishing an electrical connection between the spring element 45A and the power source, as shown in the present drawing, it becomes unnecessary to connect the movable contact to a conducting wire or "flying conductor", as was the case. in the previous embodiments. The movable flexure device parts 36, 37 of the device

  piezoceramic switching circuit 48, as well as the element with

  45A, are mechanically supported at their opposite ends

  placed, cantilevered, by the blocking means which are represented at 46, and which, again, have the functions of both mechanically holding and clamping together the piezoceramic plates 36 and 37, with the conductive surface central 39 interposed between elies. Locking means

  46 are placed on parts 36B and 37B piezocene blades

  ramiques 36 and 37 which are not prepolarized, and which are therefore unpolarized and electrically neutral, as opposed to the prepolarized, active and movable flexion devices, 36A and 37A, blades. Here again, the terminals T3 'T4 and the common terminal Tc provide the means necessary to apply a potential of continuous excitation to the parts of

  pre-polarized, active and mobile blades of

  xion, 36A and 37A, depending on the control signals, and these as the excitation potential are provided by the control circuit 19 present (not shown). We can note here again that at the time of the closure of the pair

  associated contacts 43, 45, under the effect of the

  an electrical circuit is established between the power source

  which is connected to the spring element 45A, through the terminal it, and one of the controlled means (refrigeration or defrost) which is connected to the terminal T1. It is also seen in this embodiment that the suppression of the DC excitation potential which is applied to the terminal T3 or T4 acts on the part

  active mobile device flexion so as to open the pa-

  re of associated contacts, and these remain spaced apart while the device is in a non-excited condition. It will also be apparent to those skilled in the art that it is possible to achieve a similar individual regulation of

  the power which is applied to second means (refrigeration

  ration or defrost) in the air cooling unit,

  by employing a second switching device of. pedestrian type

  zoceramic bending having the same structure, and connected in series with the second means in the apparatus, in a manner

  similar to that shown here.

  For the embodiments of piezoelectric relays

  ramics described above work properly for a long time in a particular air cooling apparatus, it is obviously necessary that the bending device

  itself continues to present the functional characteristics-

  the necessary ones. As an illustration, it is considered that the relay contacts working in the refrigeration means

  and defrosting in a typical household refrigerator

  The equipment will be operated to perform approximately 500,000 cycles during the twenty years of operation planned for the device. Such long-term operation of a piezo-ceramic bending device requires appropriate force and displacement characteristics, while avoiding relay failure during operation.

  under the effect of problems related to the priming of arcs. We explain

  so in more detail how can we satisfy

  these critical requirements for a device piezo

  Zoceramic type characteristic bending is suitable for use in the embodiment of the apparatus defined above. Figure 5 shows a graphical representation of

  characteristics of deviation and force of a piezo material

  commercially available bimorph type ceramic, which has

  supplied by Piezoelectric Products Inc. The values shown are

  were obtained with the cantilevered bending device configuration described above in connection with FIG. 4A, and the results of curve A relate to a device whose stiffness has not been increased. , while the results of curve B, more favorable, were obtained in

  increasing the stiffness of the free or moving end of the

  bending. More precisely, we know that the device

  bimorph does not bend only in the longitudinal direction

  dinal, and that the free end also becomes concave in the direction perpendicular to the direction of curvature, because of additional forces exerted on the corners of the bimorph device. If a contact is attached to the party

  the free end of the bimorph device, it does not

  not fully read the force produced and the displacement

  available from the entire bimorph device. We therefore determined

  that it was possible to optimize the amount of force

  unit of material by applying a stiffening element to the ex-

  free end of the bimorph device. A stiffening element

  representative type consisted of a piece of plastic material

  that Ultem carrying a load of glass, which was split for

  can be slid on the free end of the bimo-

  phe. The force-displacement curve that is presented makes it possible to see that the hysteresis of the operating characteristic of the bimorph devices considered is of the order of 10%. In other words, the free deformation from rest to a locking position under the effect of a force, and the return to rest show a hysteresis of about 10% in the deformation which occurs at the end of free deformation of the curve. This characteristic must be taken into account

  known hysteresis to properly design the re-

  piezoceramic lais. It can be further noted from the results

  indicated in the bending device which has been

  the stiffness, the average blocking force increases by 1.16

  N at 1.23 N, while the mean free deformation has been increased

  similarly about 0.495 minutes to 533 mm. This leads to a 14% increase in the force-displacement product, and therefore to the work of a given flexor bimorph device

  can perform. Such an increase in the force-displacement

  cement attributable to the stiffening of the free end of the bimorph device, also allows a significant reduction in the amount of piezoceramic material that would otherwise be required for a given relay operation. For the long-term operation of this piezoceramic relay and other similar relays, such as those described above in

  relationship with FIGS. 4B and 4C, it has been found that a function

  stable policy also required that the continued potential for ex-

  quote is applied in a direction identical to the direc-

  polarization, to avoid dimensional change

  in the piezoceramic material. When the operating voltage

  is applied in the opposite direction, there is a progressive depolarization in the piezoceramic material. Over time, a given displacement or force will be reduced

  gradually to zero under the action of such a depolla-

  the applied voltage. The speed of this depolarization

  sation depends on the original bias conditions and the voltage applied. For a high applied voltage, the depolarization can take place in 1 to 2 minutes, while lower voltages can make the force disappear only over a period of several years.

  born. For this reason, it is desirable to

  the piezoceramic relay with voltages applied to the bimorph laminae in the polarization direction, and

  exciting only one ceramic blade at a time in the

  positive bimorph. Therefore, to bend the device

  bimorph upwards, the ceramic blade can be excited

  with 300 volts, while 1-a lower blade is electri-

  triply in short circuit. To bend the bimor

  ohe down, you can short-circuit the upper blade and

  excite the lower blade with the 300 volts.

  On the basis of the above explanation, we can

  the pre-polarization of the ceramic slats in a

  flexor bimorph positive forms dipoles in crystals

  of individual ceramics. The subsequent application of a

  continuous excitation of a pre-polarized ceramic blade

  produces a dipole alignment in the ceramics crystals

  as individuals, and this is accompanied by a significant change in

  in the blade that is excited.Under the effect of this

  strong tension induced, the excited ceramic blade becomes thicker in the direction corresponding to the polarity of

  the applied voltage, and it also becomes shorter.

  The application of such a potential of continuous excitation to a

  unblocked bending device produces such a di-

  but this one does not accompany a deviation of the bimorph device. However, as indicated above, the

  blocking at one end a bimorph device

  Pre-polarized xion produces a deflection of the opposite end of the bending mobile device when the ceramic blades

  are so excited. The application of the continuous potential of

  quote to an individual pre-polarized ceramic blade, with

  a polarity identical to that of the pre-polarization potential

  tion, reinforces the desired alignment of dipoles, and changes them

  dimensional dimensions that occur in the dimensions

  the blade remains stable over time. Such reinforcement of the dipoles thus produces a force response or

  stabilized deviation, as long as

  the prepolarized bimorph piezoceramic relay with

  bidirectional continuous potential applied in the same direction

  than the pre-polarization potential.

  Additional considerations are involved in mitigating training problems

  arcs for the long-term operation of the mode of

  relays described above. For the appropriate size for use in this type of application, there are two

  main modes of unwanted welding of contacts. Meadow-

  first mode is due to a low contact force during

  current conduction cycles by the pair of contacts

  ciated. The constriction resistance of a pair of closed contacts is proportional to the inverse of the square root of the contact pressure. As a result, insufficient contact force leads to high constriction resistance, which results in elevated localized temperatures at the point of mechanical closure of the contacts. These high temperatures lead to localized micro-welding of the pairs of contacts that the restoring force of the bimorph device would not be able to break. The second mode of contact welding appears in control configurations in which there is an appreciable rebound of the contacts

  at closing. If the pair of contacts bounce back to the ou- state.

  after the charging current has been established, an arc

  this and it is maintained by the voltage of the power line and the impedance of the load. This arc locally heats the contact pairs at the point of closure. Every rebound

  successively restores the arc and increases the temperature of the

  tacts. In an extreme case, with high currents and multiple twists, this localized heating can lead to liquefaction of the contact material at the point of arc formation, which causes micro-welding of

  pairs of contacts at the time of final closures. This sou-

  hard may be strong enough for the force of

  recall of the relay can not break it, when

  lais is de-energized. For piezoceramic relays, the opening force is limited to a value approximately equal to the closing force of the contacts. To help mitigate the two contact welding modes described above, it has been found that forming the contacts with a low-melting metal alloy, such as silver cadmium oxide,

  is likely to maintain a working condition

  the pairs of associated contacts of the present piezoceramic electrode. We can proceed in a different way to reduce the welding of the contacts which is attributable to the rebound

  the moment of closure of the contact pairs as-

  sociées. By operating the relay circuit in the present control pattern so that the capacity of the bimorph device is charged more slowly, we obtain

* a lower closing speed of the contacts, which re-

  considerably reduces the undesirable condition of rebound-

  is lying. Such a modification of the circuit of

  by adding a resistance in series with the alternative energy source, while allowing the potential

  which is applied to piezoceramic slides individually.

  to increase them up to the operating level of 300 volts

indicated previously.

  FIG. 6 shows an electrical circuit diagram for a characteristic type of control unit, according to an aspect of the invention, making it possible to carry out a command

  fully automated. More precisely, this figure represents

  the overall power control circuit 49 which would be used for a single control module 11, for the purpose of automatically regulating the input power between the refrigeration means and the deicing means, in the household refrigerator described above. . Therefore, for ease of understanding, the same reference numerals in Fig. 6 are retained to identify the circuit components previously identified in the previous refrigeration control circuit (Fig. 3). As we

  can be noted in the present drawing, the piezocera-

  Bending system 15 is connected in a circuit configuration.

  baked such that its central conductive surface 14 is connected

  to a power supply conductor 20, and the moving end

  16 of the piezo-ceramic bending device remains in a positive

  when the relay is not energized. of the

  fixed electrical contacts 17 and 18 are connected in the cir-

  cooked to allow an electrical connection to be made with

  means of refrigeration and de-icing, all of this being

  form to the description made previously. We can also

  that the relay interconnection provides a secure

  such as the control unit can never trigger simultaneously cooling and heating, while the relay requires only a very low holding power,

  about 10 microwatts, during its operation. The exam-

  full circuit that is shown to apply.

  Continuous excitation at the piezoceramic relay consists simply of

  diode-capacitor network which includes a capacitor

  pump 50, a storage capacitor 51 and doubling diodes 52 and 53, for the purpose of effectively doubling the AC voltage to 115 volts, in a known manner. Current limiting resistors 54 and 55 are incorporated in the control circuit to reduce the sensitivity of the circuit to sector-induced transients. The relay driver part in the circuit that is represented is completed by a pair of active devices 56 and 57, which

  are represented in the form of output transistors dis-

  Decrees. Control signals for the automatic actuation

  The control of the piezoceramic relay in the circuit can be provided by an integrated circuit 60 specially adapted for this circuit, and the control signals are elaborated in the general manner which has also been previously explained. However, to further explain a typical example of developing temperature control signals for the refrigeration means shown therein, there is shown

  used in the circuit considered a low configuration

  to intervene a feedback signal, in which one.

  thermistor 62 is connected to a series-connected limiting resistor 64 for bridge measurement, with the user set-point potentiometer 66 and two calibration resistors 68 and 70 which define

  minimum temperature and temperature setpoints

  maximum ture. The supply for the logic circuits in the control circuit 60 is obtained by means of a voltage drop resistor 72 and a power storage capacitor 76. This power supply for the logic circuits is further regulated by a shunt regulator incorporated on the chip, which is part of the control circuit shown. The excitation of the piezoceramic relay with a single single-transistor driver in the circuit shown is used in

  in addition to passive resistors 78 and 80, connected to the potential

  positive feed, to unload the piezocene blades.

  ramic whenever the selective excitation is complete.

  At the moment of initial excitation, the electronic control circuit produces a voltage of about 3 volts, so

  that the active drive transistor 56 and the resistor 81, con-

  connected in series, function as a source to

  ordered. As a result of the initial closure of

  relays that are connected, the voltage that is applied

  to the gate of the active device 56 is immediately

  up to the full voltage of the power bus line

  logic circuits, which is provided by the communication circuit

  electronic control and can be up to 10 volts. This then causes the active device 56 to become fully conductive, and the piezoceramic relay blade which is thus actuated is then charged quickly, which increases the contact force exerted on the relay contacts and prevents

  welding at the time of a subsequent closure of the contacts. The electronic control circuit operates in a similar way

  active device 57 remaining and its resistor 82 connected in series. Additional current limiting resistors 84 and 86, which are respectively connected in series with the active devices 56 and 57, prevent the flow of excessive current in the active devices that become conductive, and they also contribute to the limitation of the maximum closing speed of the piezoceramic relay contacts. Although the relay is powered by

  the control circuit which is represented, the main cou-

  The power supply must be supplied by the shunt resistors 78 and 80. This operating mode limits the maximum voltage applied to the relay, since the impedance

  high source that provides the diode-capacitor network pre-

  is charged by the shunt resistors. This mode of operation

  This minimizes the erosion of the relay contacts because, under these conditions, the contact separation speed of the relay is relatively slow. The remaining capacitors 88 and 90 which are represented in the circuit in question are essentially intended to attenuate the noise. Frost detection means 92, which are optional, and compressor protection means 94, already known, have also been incorporated in the control circuit shown, to show

  other useful control functions that can easily be

  grammer in the integrated circuit part of the communication circuit

  using the classic technology.

  The automated overall operation of the control circuit described above deviates in a first direction the piezo-ceramic bending device, under the effect of control signals which are produced by the associated integrated circuit, to establish a circuit between the power source alternative and the terminal which is connected to the refrigeration means, while it deflects the bending piezo-ceramic device in

  a second direction, under the effect of second signals of com-

  which are produced by the integrated circuit, so as to establish a circuit between the alternative energy source and the deicing means. In such an automated operating method, it is possible to operate the deicing means

  for a predetermined period of time, under the

  this second control signals, and the operation of the deicing means is triggered each time an interval

  predetermined operating time of the cooling means

  ration is exceeded, in accordance with a preprogrammed sequence that has been introduced into the integrated circuit. As explained

  previously, the de-icing means can also function

  depending on the second control signals, to enable the initiation of a defrost cycle following the lapse of a predetermined time interval

  after their previous operation. When the means of

  Frost detection is incorporated in the control circuit, it also becomes possible to operate the deicing means under the control of second control signals that are produced under the action of frost detection means. In a similar manner, the integrated circuit that is shown may further provide thermal protection for the refrigeration means, with the incorporation of additional temperature sensing means for the compressor motor. Representative control steps that are

  implemented in accordance with a method of operation

  of the circuit shown, comprise a triggering operation of the refrigeration means at a predetermined temperature, with the application of the alternative energy

  when the electrical contacts of the miniature piezoceramic relay

  bile are moved to a first operating position

  detection of the temperatures that are reached in the particular air cooling apparatus, during the operation of the refrigeration means, to develop first control signals representing the difference between

  the detected temperature and a second predetermined temperature

  the first control signals allowing the application to the piezoceramic relay of a potential

  continuous excitation of predetermined polarity, corresponding to

  at high voltage, the application of the potential

  high voltage excitation circuit at the piezoceramic relay, until the detected temperature difference reaches zero, then removing the high voltage DC potential, which causes the piezoceramic relay electrical contacts to open, the elaboration of seconds

  control signals, by which the time interval

  the de-icing means are actuated is deter-

  the second control signals enabling the application to the piezoceramic relay of a high potential of excitation of high voltage and of opposite polarity, and the application to the piezoceramic relay of high potential of excitation of high voltage and of opposite polarity, which causes the displacement of the electrical contacts of the piezoceramic relay to a second operating position,

  in which the alternative energy is applied for triggering

  the operation of the de-icing means. As mentioned

  As previously described, the operation of adapting a typical high-voltage integrated circuit to accomplish these control steps uses conventional technology. The

  usual microprocessor which is incorporated in the internal circuit

  tegree performs the control functions that are illustrated <in accordance with instructions that are introduced in the

  ROM that is functionally associated with the micropro-

  cessor. A programmer can therefore prepare a set of instructions to permanently record in the microprocessor ROM, these instructions

  allowing the microprocessor to execute without difficulty

  cultured the order program. The control algorithm allows

  made according to one aspect of the invention is therefore simple-

  introduced in these programming instructions.

  A representative embodiment for the refrigeration apparatus described above, which employs such an electronic control circuit to regulate the application of the AC power between the refrigeration means and the deicing means, in order to avoid operation simultaneous means may include: (a) at least one relay

  piezoceramic having a first terminal intended to be

  connected to an alternative energy source, a second terminal for establishing an electrical connection between the alternative energy source and the refrigeration means in an operating position, and a third terminal for establishing an electrical connection between the energy source

  alternative and the de-icing means in a second position.

  operating mode, the relay further comprising a

  piezoceramic positive bending positive, which is formed by at least two plane and pre-polarized piezoceramic blades, which are fixed in parallel and opposite orientations on opposite sides of at least one central conductive surface, and which comprise outer conductive surfaces which are insulated from each other and from the central surface by the thicknesses of the respective interposed piezoceramic blades, the bending device further comprising a pair of movable electrical contacts which are placed on opposite sides of the device to bending, to work in association with a pair of fixed electrical contacts

  placed nearby, the fixed electrical contacts being

  separately connected, from one side to a terminal in the refrigeration means, and from the remaining side to a terminal in the de-icing means, and the bending device being designed to deform on one side or the other a central position

  that this device takes rest, in a position not exci-

  (b) a relay switching circuit that is connected to

  respective ones of the piezoceramic slides

  polarized, so as to apply a continuous potential for exci-

  a method of selective deformation of the bending device under the effect of control signals which are developed during operation of the refrigerating and defrosting means, and (c) the relay switching circuit being directly and ohmically connected to the alternative energy source and a terminal of the piezoceramic relay, so the latter is deformed in a first direction to establish a circuit between the alternative energy source and the

  refrigeration means, or is deformed in a se-

  conde direction for establishing a circuit between the alternative energy source and the terminal of the deicing means,

  dependent on the control exercised by a cir-

  baked integrated interconnected to the switching circuit. A re-

  The appropriate piezoceramic lip which operates in this manner, according to FIG. 4A, described above, is preferably pre-polarized selectively, and it comprises locking means which are fixed on non-polarized parts and which

  adjacent to the selective pre-polarized bending device

  ment, and support the latter cantilever, to actuate the pairs of associated electrical contacts, the unpolarized portions being electrically neutral and not subject to

  no mechanical stress. A switching circuit of

  characterized in that it comprises a diode-capacitor array for producing the DC potential of excitation corresponding to a high voltage, and further comprises series-connected isolation resistors, for limiting the current which is absorbed to

  from the alternative energy source. The circuit of com

  Relay mutation of a representative type also includes a load resistor that is connected to apply the excitation potential to the piezoelectric relay, as well as a first resistor that is provided to discharge the first piezoceramic blade when its excitation has ceased. ,

  and a second resistance that is intended to unload the se-

  piezoceramic blade when its excitation ceased. A mode of operation of the deicing means according to

  the advanced control algorithm described above, de-

  triggers a defrost cycle dependent on control signals that are provided by the interconnected integrated circuit, for a predetermined value of 9.5 hours, in accordance with the previously defined operating interval value, - or

  every 48 hours have elapsed since the last

   deny defrost cycle. It is obvious that doing

  function in this way the domestic appliance which is de-

  crit now allows to use a more control unit

  simple, that it is possible to install more easily

  inside the device, and with wiring costs

  reduced, and that in addition the operation of the apparatus

ra cheaper to a user.

  The flowchart shown in Figure 7 represents a

  sequence of pre-programmed instructions of a type

  to allow the integrated circuit considered above to

  operate in a fully automated way the

  the same is ordered. The flowchart consists of a sequence

  this of programs that the microprocessor runs continuously

  cyclically, when the control circuit is conti-

  natively fueled by the fact that the apparatus ordered is

  connected to a power source. The control sequence of

  seems to be logically divided into several

  mande. In the first program bearing the designation "T / Tu", which controls the operation of the refrigeration means, the temperature detected in the food storage compartments is compared with the maximum temperature set. If the detected temperature exceeds the maximum temperature set,

  a sub-program relating to the state of operation of the com-

  presser is called. In this subroutine, the compressor is operated unless it was already running, and the

  Electronic defrost timer is triggered automatically.

  o the compressor is in operation. If the

  presser is found in operation, a second sub-pro-

  gramma with the designation "TD / TD or TE / TE" is called

D DS E / TES

  to determine whether the value of the defrost timer de-

  pass the start time value of the defrost, or if a

  elapsed time value exceeds a predetermined maximum value.

  born of time elapsed. If any of these exceedances are found in this routine, the sequence returns to the initial starting point. However, if no overshoot is found in the latter subprogram, the sequence passes

  then to the operations of triggering the

  the defrost heating element and the defrost heater timer. As can be further noted in the drawing, the control sequence involves additional subroutines at the time of the

  triggering the deicing means. The first subpro-

  gram, labeled TH / THF or TS / TcHAUD, compares the defrost heater timer value with

  a set point corresponding to a maximum value

  determined for the heating element, and it compares further the

  operating temperature of the heating element of

  with the set point corresponding to a manual value

  maximum for the defrost heating element. This sub-product

  gram continues to run cyclically as long as

  time that no value corresponding to an overshoot is detected. However, if either overflow is detected in the subprogram, the defrost cycle is stopped and the defrost timer, elapsed time timer, and heater timer are restored to that time.

  moment. The defrost timer is also retriggered

  in the next subroutine, so that its restart instant value can be compared with a value

  predetermined delay time in the subroutine

  before, bearing the designation TH / THS. This final subroutine in the defrost control sequence allows a delay time to be introduced before the compressor mechanism is actuated so that the gas-refrigerant pressure can be applied.

  equalize, in order to avoid starting the engine of the com-

  presser with high back pressure. When all the subprograms associated with the operation of the de-icing means are completed, the command sequence returns to its

  starting point. In the continuous fulfillment of cycles

  the operation of the refrigeration equipment, the se-

  the control program proceeds to a subsequent scan program, labeled TL / T / TU, in which the temperatures detected in the food storage compartment are

  compared with the setpoints corresponding to the temperatures

  eratures upper and lower. This polling program continues to run as long as the temperatures

  detected remain within the set point

  blis, and during this check, a subroutine is executed

  to maintain the compressor in its operating mode.

  This routine brings the sequence back to the subprogram

  was executed in the previous polling program, in relation to the operation of the refrigeration means, if the compressor is still off, or it passes the sequence to a polling program which will be executed at the

  continued if the compressor is found at a standstill. When the

  gram relating to the operation of refrigeration equipment -

  finds that the operating temperature in the compartment

  maintenance is not included between the lower and upper set points that have been established,

  a subsequent scanning program is executed. In this

  In the scan program, a subroutine determines the operating condition of the compressor, which is stopped at this time, and this subprogram also reverses the defrost timer. If the compressor is found stopped at this time, the control sequence goes to a polling program

  final. In this final scanning program, carrying the

  TE / Ts, the value of the time measuring timer

  elapsed time is compared with the maximum value of elapsed time.

  When the value of the elapsed time measurement timer exceeds the maximum time elapsed value, the control sequence proceeds to the subprograms that trigger a defrost cycle. If the maximum value of elapsed time exceeds

  timer value of elapsed time in this program

  gram, the sequence simply returns to the starting point.

  The examination of the organization chart clearly shows that

  thus provides actuating means for the automatic regulation of

  refrigeration and de-icing equipment, a

  which avoids the simultaneous operation of the means

  tive. It is also obvious that this regulation

  automated delivery of the input power between the respective refrigeration and defrosting means is accomplished

  with a better return, which reduces the

  defrosting means in the controlled apparatus.

  The foregoing description shows that the invention

  proposes a power control system having wide uses that makes it possible to operate an apparatus for

  air cooling with better performance. We also see

  that it is possible to make changes to

  processes, to the control means and to the specially controlled apparatus

  which are described here, without departing from the scope of the

  vention. It is noted, for example, that it is possible to easily program in the integrated circuit used here additional control functions other than those described above specifically for controlling more extensively the

  refrigeration and defrosting means. It is also possible

  sible to make various modifications to the means of refrigeration.

  specific de-icing means described above.

  while retaining the control principles that have been

have been exposed for the invention.

Claims (10)

  1. System for regulating electric power   which comprises, in combination: (a) a piezoceramic relay (12) connected in a circuit configuration which allows   connection of a source of energy to the refrigeration means   tion (6, 26, 28), the piezoceramic relay (12) comprising a terminal (14) provided for connection to the power source, and   a movable, bending piezoceramic device (15) comprising   both mobile electrical contact means (16) which   valiant in association with electrical contact   (17) placed nearby, the electrical contact means   fixed terminals (17) being connected to a terminal of the means for   frigating (6, 26, 28), and the bending piezoceramic device (15) maintaining the movable contact means (16) spaced from the stationary electrical contact means (17) when in a non-energized condition; and (b) a control circuit (19) connected directly and ohmically   to the power source and to the terminal (14) of the piezoelectric relay   (12), which responds to control signals in action.   piezoceramic mobile device with bending, and which   the bending device deforms and   blisse a circuit between the energy source and the terminal of refrigeration means.   2. Power regulation system according to the   claim 1, characterized in that the control circuit (19) further comprises a diode-capacitor network (50, 52,   53) for producing a continuous potential for corona excitation.   responding to a high voltage to operate the relay Zoceramic (12).   3. Electric power regulation system   which is applied to an air cooling device com-   carrying de-icing means, characterized in that it comprises   takes, in combination: (a) a piezoceramic relay (12)   nected in a circuit configuration that allows connectivity   xion of a power source to the deicing means (13), the piezoceramic relay (12) comprising a terminal (14) provided   for the connection to the energy source and a piezoelectric device   movable, bending zoceramic (15) having movable contact means (16) which work in association with stationary electrical contact means (18) which are placed in proximity, the fixed electrical contact means (18) being connected to a terminal of the de-icing means (13), and the bending piezo-ceramic device (12) maintaining the means   movable contacts (16) spaced from the con-   fixed electrical contact (18) when in a non-excited condition; and (b) a control circuit (19) directly and ohmically connected to the power source and the piezo-ceramic relay (12) terminal (14), which responds to control signals by actuating the moving piezoceramic device bending, and which causes the bending device (15) to deform and establish a circuit between the source   of energy and the terminal of the deicing means (13).   4. System for controlling the electrical input power between the refrigerating means (6, 26, 28) and the deicing means (13) in a cooling apparatus   of air, which avoids the simultaneous operation of the   which comprises: (a) at least one   piezoceramic relay (12) which is connected in a configuration   circuit arrangement for individual connection of the energy source to the refrigeration means (6, 26, 28) or the deicing means (13), the relay (12) comprising a terminal (14) which is functionally associated with a mobile, bending piezoceramic device, (15) ', comprising means   associated contacts (16, 17, 18) for the individual connection   to terminals which are incorporated in the   refrigeration and defrosting lenses; and (b) a control circuit (19) directly and ohmically connected to the power source and the piezo-ceramic relay (12) terminal (14), which responds to control signals by actuating the moving piezoceramic device at bending, (15), which causes the bending device to deform and establish a circuit between the power source and the terminal of the refrigeration means (6, 26, 28), or deforms and establishes a circuit between the energy source and the terminal means of defrosting (13).   An air cooling apparatus comprising, in combination, a cabinet having at least one storage compartment (2, 3), refrigeration means (6, 26, 28) and an electrical control unit (10, 11). which is intended to allow the connection of a power source to the refrigeration means, characterized in that the electrical control unit (10, 11) comprises: (a) a piezoceramic relay (12) which is connected in a circuit configuration that   allows the connection of the energy source to the means of re-   frigration (6, 26, 28), the relay (12) including a terminal   (14) provided for the connection to the power source and a dis-   piezoceramic moving, bending positive, (15) which comprises movable electrical contact means (16) working in association with fixed electrical contact means (17) placed in the vicinity, the fixed electrical contact means (17) being connected to a terminal of the refrigeration means   (6, 26, 28), and the piezo-ceramic device with bending   holding the moving electrical contact means (16) spaced from the fixed electrical contact means (17)   when he is in a non-excited condition; and (b) a cir-   cooked control (19), connected directly and ohmically   to the energy source and to the terminal (14) of the piezocera-   mie (12), which responds to control signals by operating the bending, movable, piezoceramic device (15) and causes the piezoceramic device to deform and establish a circuit between the power source and the terminal of the   refrigeration means (6, 26, 28).   6. Air cooling apparatus according to the   5, characterized in that the control circuit (19) comprises a diode-capacitor network (50, 52, 53) which is   intended to produce a continuous excitation potential corresponding to   high voltage, to operate the piezo relay ceramic (12).   7. Air cooling apparatus according to the   5, characterized in that the operation of the refrigeration means (6, 26, 28) in dependence on the control signals is also controlled by means of temperature detection.   8. A method of regulating the power which is applied to an air cooling apparatus comprising refrigeration means (6, 26, 28), characterized in that it comprises the following operations: (a) selecting   a piezoceramic relay (12) having a terminal (14)   connected to the energy source and a piezoceramic device   bending, (15) with electrical contact means   mobiles (16) working in association with.   fixed electrical contact means (17) placed in the vicinity, the fixed electrical contact means (6) being connected to a terminal of the refrigeration means (6, 26, 28); (b) deforming the bending device (15) in a first direction with control signals provided by an associated control circuit (19) so that   the associated contact means (16, 17) close in order to   blurring a circuit between the power source and the terminal of the refrigeration means (6, 26, 28); and (c) producing with the associated control circuit (19) second control signals under which the bending device (15) deforms in the opposite direction, to open the means associated contact points (16, 17).   9. Method for regulating the input power which   is applied to an air cooling device with   both defrosting means (13), characterized in that   includes the following operations: (a) selecting a   piezoceramic lais (12) having a terminal connected to the power source and a movable bending piezoceramic device (15) with movable electrical contact means   (16) working in association with means of   fixed electrical contacts (18) placed in proximity, the fixed electrical contact means (18) being connected to a terminal of the deicing means (13); (b) deforming the bending device (15) in one direction, with first control signals being provided by an associated control circuit (19), so that the associated contact means (16, 18) close to establish a circuit between the energy source and the terminal of the deicing means (13); and (c) producing with the associated control circuit (19)   second control signals under the effect of which the   bending wire (15) is deformed in the opposite direction, for   opening the associated contact means (16, 18).   A method for controlling the input electrical power between the refrigerating means (6, 26, 28) and the deicing means (13) in an air cooling apparatus, employing as a switching means a piezoceramic relay mobile and pre-biased (12), to prevent simultaneous operation of the respective means, characterized   in that it comprises the following operations:   a piezoceramic relay (12) comprising a movable and pre-biased piezoceramic bending device (15) which operates on either side of a central position which the bending device takes to rest, in a non-excited condition, the piezoceramic relay (12) further comprising a first terminal (14) for connection to the power source, a second terminal for connecting the power source to the refrigeration means (6, 26, 28) in a first operating position, and a third terminal for connecting the power source to the   de-icing means (13) in a second operating position   tioning; (b) deforming the bending device (15) in a first direction, with first   control signals that are provided by a communication circuit   associated command (19), to establish a circuit between the source   of energy and the terminal which is connected to the means of   management (6, 26, 28); and (c) deforming the bending device (15) in a second direction, with   second control signals which are provided by the circuit   associated control cookware (19), to establish a circuit between   the energy source and the deicing means (13).