CN1864113A - Electronic thermal-protector for electric water boilers - Google Patents

Abstract

It is described a control device (R) which can perform heat regulation and thermal protection procedures in electric water boilers. During regular operating conditions, the beat regulation procedure is in progress and the power supply to the electrical resistances (2) is enabled or cut off by means (3) capable of preventing the passage of current inside the electrical circuit (1). In the event of anomalous operating conditions, the thermal protection procedure is activated; it shuts the circuit (1) by opening the two relays (4). As per the invention, a single electronic device (7, 8, 9, 10) receives information from one or more temperature sensors l: (6), manages said heat regulation and thermal protection procedures and decides whether the heat regulation procedure is to be maintained or whether the thermal protection procedure is to be activated by opening both relays (4). A hardware logic circuit (8) performing the function pf watch-dog (8) supervising the correctness of the operations is featured. The invention also features the possibility for the user to reset the heat regulation procedure manually once the anomaly no longer subsists and up to a maximum number of reset attempts.

Description

Electronic thermal protector for electric boiling water boiler

manual

The invention relates to an adjustment and safety control device for an electric boiling water boiler. The electric boiling water boiler has two devices that control the temperature of the water contained in the container.

One is the regulating thermostat (hereinafter also referred to as the thermostat). Its task is to regulate the temperature by keeping the temperature of the boiling water boiler at the t.r value set by the manufacturer and/or the user; of course, any adjustment the user can make is to prevent dangerous temperatures from being reached.

Another device is a thermal protection thermostat (hereinafter referred to as a thermal protector). Its task is to provide thermal protection by cutting off the power supply to the resistor if the monitored temperature reaches an intermediate cut-off value t.i between the value attainable during normal operation and the maximum value of t.s specified by safety regulations. Generally, this only happens if the regulating thermostat malfunctions; for example, if the setting is incorrect or if the electrical contacts are welded and can no longer be disconnected. However, abnormal conditions such as lack of water in the container can cause a sudden increase in temperature, so that it is possible to activate the thermal protector even when the regulating thermostat is in good condition.

It is very important to adjust the accuracy of the thermostat, not for comfort but to limit consumption; it has been proved by experiments that in a given period, assuming that the average temperature in the boiling water boiler is the same, the actual temperature change due to its inaccurate control is greater. The sharper, the greater the heat loss. From this point of view, it is a fact that the most accurate electro-mechanical thermostats are those using bubble sensors, followed by rod sensors, and thirdly those whose sensors consist of bistable bimetallic foils. Electronic thermostats are the best, which usually use NTC as the sensor, which not only provides accurate regulation that electro-mechanical thermostats cannot, but also offers many other advantages, such as the ease of controlling them with a microprocessor, Run time, temperature, and other functions are programmable through the microprocessor. Electro-mechanical thermostats cut off the power supplied to the resistor by physically breaking the electrical contact, while electronic thermostats act by cutting off the current flowing through a semiconductor device (TRIAC) or by commanding the opening of a relay, where if the required amperage Low enough, the semiconductor device can be directly arranged in series in the circuit of the resistor, and the relay breaks the circuit of the resistor. However, safety adjustments do not require the adjustment thermostat to physically disconnect the individual phases of the circuit.

The physical disconnection of the two poles across the resistive circuit is commanded by the thermal protection thermostat; on the other hand, the activation temperature does not require specific precision, since the allowable residual value of a less sensitive sensor like a bistable bimetallic foil can vary at a distance. Activated at a cut-off temperature t.i above the regulation temperature t.r but well below the maximum allowable temperature t.s. Heat protection thermostats in boiling water boilers have hitherto been of the electro-mechanical type with a very simple mechanism; in general it is of the type that incorporates the well-known bistable bimetal disc as a sensor/actuator device. The thermal protection thermostat irreversibly disconnects two (or three) power phases when the set temperature is reached; when overheating is not caused by a fault affecting the regulating thermostat, resetting the contact to restart the boiler is in most models It is possible, but resetting the device can only be checked by a service technician, which creates the inconvenience that the resetting of the boiling water boiler always requires the intervention of the technical service, even if the cause of the failure is entirely accidental.

For compactness and ease of assembly, electro-mechanical thermostats and thermal protection thermostats are often housed in the same housing, but this does not mean that they are not two separate devices, each with its own sensor, its own The mechanism used to break the electrical contact and its own electrical contact. In conclusion, safety requires that each of the two thermostats must have its own "electro-mechanical logic".

In the case of electronically adjustable thermostats, their use has hitherto been limited to higher-grade products, taking into account the impossibility of saving the cost of electro-mechanical thermal protectors, which are usually extremely difficult to accommodate in the same housing as the electronic thermostat. Although the most common type of thermal protector is the one with a bimetallic foil, it must be placed as close as possible to the area whose temperature must be monitored, that is, the area in which the operating temperature Can be high enough to damage electronic devices.

The main purpose of the present invention is to specify a means by which a single control device can be obtained which can be used at least as a thermostat and a thermal protector in an electric boiling water boiler.

Another object of the invention is to specify a means by which said single control device is allowed to use a single operating logic, ie a single hardware device and a single software device, for controlling at least the functions of the thermal regulator and the thermal protector.

Yet another object of the present invention is to enable the user to reset the normal operation of the boiler when it is blocked by the thermal protector for reasons that are accidental and not part of a detectable fault.

Yet another object of the present invention is to give said single control device additional information, programming and control functions not related to thermal regulation or thermal protection.

According to the invention, these and other objects are achieved by a control device acting in a suitable way, comprising a combination of suitable electronic and electro-mechanical means.

The invention is illustrated with some preferred but not exclusive variants in the following description together with the drawings and appended claims, which form an integral part of the description of the invention.

Some preferred variants of the present invention are described below.

FIG. 1 , the sole figure of the present description, schematically shows an electronic and electro-mechanical control device R according to the invention.

Referring to the accompanying drawings, R represents a control device, which has the functions of a thermal regulator and a thermal protector as a whole; 1 is a power supply circuit that supplies power to the resistance 2 of heating water through the connection terminal 2.1; 3 represents a regulating relay, whose disconnection Open and close control power supply to resistor 2 to keep the water at set temperature during normal operation; 4 indicates two safety relays (or a single relay with double microswitches) if the control R detects anything related to the safety regulation Incompatible operational failure, the control means R opens the relay; 5 designates two (possible) fuses which are connected in series with said relay 4 and which protect the contacts of relay 4 from overcurrents which would cause them to stick.

The control means R comprises one or two temperature sensors 6, preferably of the NTC type, or any other type, suitable for delivering a temperature signal that can be interpreted by electronics; of the two sensors 6, one is dedicated to controlling the set regulated temperature t.r, the other dedicated to the control of the cut-off temperature t.i; however, consistent with the relevant regulation requirements, and in line with the point where the regulation temperature t.r and the cut-off temperature t.i can be detected, a single sensor 6 can be used simultaneously with thermal regulation and thermal protection Relevant information; at least one second sensor 6 can be used for auxiliary functions not related to thermal regulation and thermal protection functions, for example, to estimate the average temperature and energy content in a boiler for boiling water according to known methods, if the water temperature in two different selection zones are known, these two values are easy to derive.

The control device R also includes a microprocessor 7 equipped with special software to perform at least the following tasks:

- receive and interpret signals from sensors 6;

- if there is no operational fault, then through the command cable 3.1 command the relay 3 to modulate the thermal power supplied to the water through the resistor 2 so that the temperature is kept around the set regulated temperature value t.r;

- If there is an operating fault, force the relay 4 to open via the command cable 4.1 to cut off the two power phases of the resistor 2.

Furthermore, the operating faults that the microprocessor 7 can recognize include not only the overheating temperature signaled by the detection sensor 6, but also the resistance value of the detection sensor 6 due to infinite, zero or unreasonable values (i.e. values outside the possible range of the sensor 6). ) faults due to open or short circuit of a signaled resistor.

The control device R also includes a hardware circuit 8 which acts as a monitor (commonly and well known as a system "watchdog") which monitors the normal operation of the microprocessor 7 and, if used with the microprocessor 7 or Other main or auxiliary devices (including the controller device R) detect abnormal actions, then disconnect the relay 4 through the instruction circuit 4.2. Said watchdog 8 acting according to known techniques and methods will not be described in the following, since it can be implicitly deduced that it can monitor the control of any function within the range provided by the state of the art.

It is reminded that current manufacturing techniques of electronic equipment, providing possible redundancy of logic circuits, and monitoring methods by means of hardware circuits used as watchdogs, at least for the proper performance of the main functions, make obtaining approval by the relevant regulatory authority and Acceptable, very reliable equipment with safety functions is possible.

If one of the relays 4 opens due to a detected fault, the automatic closing of the control means does not take place once the fault has been eliminated, only the manually operated reset means 9 can command them to close. However, said reset command can only be accepted by the safety system if the microprocessor 7 determines that the fault that caused the relay 4 to open no longer exists. In other words, if for example an unexpected increase in temperature occurs, the reset command and subsequent closure of relay 4 is accepted only after the temperature has returned to normal; conversely, if (as an example) the fault is an irreversible damage to the sensor, a return to normal is not possible state, so the reset instruction continues to be rejected by the microprocessor 7. It is known that electro-mechanical thermal protectors are also equipped with a reset command that resets the thermostat once the fault has been eliminated; it consists of a push button that, once pressed, acts directly on it by closing the electrical contacts; however, even if the fault persists, pressing A push button can also force the contacts closed. To this end, the button is placed out of reach of the user and protected by a cover that can be opened with a special tool so that it can only be opened by authorized repair personnel. On the contrary, as mentioned above, according to the invention, since the reset command is rejected and has no effect if the fault still exists, but the user still has access to the instruction, the advantage is that when there is no damage but only a temporary and reversible fault , there is no need to ask the technical service department to reset the boiler.

However, the control device R can also be designed to take into account and remember the number of times it has accepted a reset command, and limit the maximum possible number of resets to a set value beyond which it rejects any command. Therefore, even a temporary and reversible failure, if it occurs too frequently, may require the intervention of technical services, thereby indicating a recurring problem that needs to be identified and resolved.

For this purpose, the control device R may include a non-volatile memory 10 such as EEPROM, that is, a memory that will not be deleted when power is turned off, and that stores all detected abnormalities and/or the number of resets accepted with appropriate codes; The memory 10 can also hold data not related to thermal regulation and thermal protection but useful in performing the auxiliary functions mentioned above.

Finally, a display 11 may also be provided, which provides the user with information on the status of the boiler with respect to the thermal regulation and thermal protection functions as well as with respect to auxiliary functions.

Another difference concerning not only the device but also the method and even the logic of operation compared with existing electro-mechanical thermal regulation and thermal protection devices is that, There are also always two independent devices within a single case; in other words, they each follow their own mechanical logic. On the contrary, even if the control device R is redundant for safety reasons and comprises software and hardware components including watchdog 8, it has only a single "electronic logic". The "electronic logic" is not composed of dedicated components dedicated to thermal regulation, thermal protection, and auxiliary functions. Regardless of whether there is more than one temperature sensor 6, in order to comply with regulating or measuring the temperature of several points, their signals are received by a single unit performing various functions depending on the situation (as long as the temperature range is normal), the control device R The "electronic logic" controls the operation of the regulating relay 3 or, in other words, it executes the thermal regulating process; as soon as the cut-off temperature ti is exceeded or if there is another fault, the same control device R opens the two safety relays 4, i.e. it cuts off the water by blocking boiler to start the thermal protection process; at the same time, the "electronic logic" of the control device R can also perform other auxiliary messages and programming functions, etc.

The advantage is obvious that the control device R provides at negligible additional cost through the development of non-essential functions useful for programming and other purposes.

Other embodiments of the control means R are possible, some non-exhaustive examples are provided below.

The safety relay 4 can be of normally closed or normally open type, and they can be safely disconnected or kept disconnected by the control device R under abnormal conditions.

The cut-off device 3, like current electronically adjustable thermostats, could have a TRIAC instead of a relay.

Since it is equipped to perform a greater number of cycles than expected during the boiler's service life (e.g. 300,000 cycles at the state of the art), the regulating relay 3 can be eliminated and its function assigned to one of the safety relays 4 one or two. In this case, the safety provided by the control device R may be further enhanced by adding one or more of the following functions or devices:

- may include fuse 5 as mentioned above;

- In thermal regulation mode, it is possible and sufficient to alternately command one of the two relays 4 to open, so that their contacts wear evenly, and a possibility of 2 x 300,000 opening and closing cycles of the resistance 2 for thermal regulation purposes sex is ensured.

- As soon as the number of cycles reaches a predetermined maximum value, the control device R can be blocked by finally opening the relay 4 .

- the contact of one of the relays 4 which cannot be opened can be detected by the control device R by electrical or thermal signals in various ways (for example, by detecting that there is a voltage drop across the resistor 2, or by detecting that despite the opening The command temperature still continues to rise), and then another relay 4 is disconnected immediately without reset.

For relay 4, they may be replaced by TRIACs as long as the relevant regulation permits.

Finally, it should be pointed out that, mutatis mutandis, the foregoing refers to two-phase currents and can therefore also be used for three-phase systems with resistors connected in delta or star.

Claims (24)

1, a kind of thermal conditioning of electric water boilers and control device R of heat protection function of being used for comprises:

-at least one sensor (6) is used for the temperature of measuring vessel water,

-power circuit (1) to resistance (2) power supply, is used for the water of heating container by link (2.1),

-heat regulating device is used for making the water temperature of container to remain on to set and regulates near the temperature (t.r), and described heat regulating device comprises device (3), in order to the electric current of blocking circuit (1) at least one end of the link (2.1) of described resistance (2),

-thermel protection device is used for preventing that water with container is heated to surpasses by temperature (t.i), describedly is lower than maximum by temperature and can allows safe temperature (t.s); Described thermel protection device comprises device (4), is used for described two described links (2.1) of disconnecting circuit (1), it is characterized in that:

The device of carrying out thermal conditioning and heat protection function comprises:

-single electronic logic (7,8,9,10) can pass through the electric power that described device (3,4) be cut to one or two link (2.1),

-described electronic logic (7,8.9,10) depends on the temperature value that receives by built-in command and any other signal that can drive following process by described sensor (6):

-thermal conditioning process, during this period, described control device (R) periodically activates/stops using the power supply of resistance (2), so that remaining on, the temperature of drinking water boiler regulates about temperature (t.r),

-or hot protection process; during this period; described control device (R) force two links (2.1) to the circuit (1) of resistance (2) power supply by and make them keep this state up to carrying out any hand-reset operation to prevent further water to be heated to the temperature of setting by more than the temperature (t.i); and wherein prevent the described device (3) that has electric current to pass through in the circuit (1), and be used for to activate by control device (R) at the described device (4) of link (2.1) two ends disconnecting circuits (1).

2, control device as claimed in claim 1 (R) is characterized in that, described electronic logic (7,8,9,10) is partly expressed with the software instruction that is kept in the microprocessor (7), and partly uses hardware logic electric circuit (8) to express.

3, the described control device of claim (R) as described above is characterized in that, the function that described hardware logic electric circuit (8) can execution monitoring dog (8) because it can:

-according to state-of-the art, detect one or more abnormal behaviors of described microprocessor (7) and other system units,

-under failure condition, realize described hot protection process.

As the described control device of the arbitrary claim in front (R), it is characterized in that 4, the described device (3) that is used for the electric current of blocking circuit (1) comprises relay (3), wherein single microswitch is connected with resistance (2).

5, as the described control device of the arbitrary claim in front (R), it is characterized in that, be used for comprising at the device (4) of two links (2.1) disconnecting circuits (1) of resistance (2):

-the two poles of the earth relay (4)

-or two relays (4) with single microswitch.

6, as the described control device of the arbitrary claim in front (R), it is characterized in that, the nonvolatile memory such as EEPROM (10) is provided, wherein can write down the information of relevant operating troubles at least.

7, as the described control device of the arbitrary claim in front (R), it is characterized in that, display device (11) is provided, to the information of user by relevant drinking water boiler state.

8, as the described control device of the arbitrary claim in front (R), it is characterized in that, comprise manual reseting device (9), be used at least:

Thermal conditioning process in the-repositioning control device (R),

-be closed in the described device (4) that is forced to open in the hot protection process.

9, as the described control device of front claim (R), it is characterized in that,

-described resetting means (9) can be by user capture,

-described electronic logic is only just accepted reset request after the fault that triggers hot protection process finishes.

10, as the described control device of front claim (R), it is characterized in that,

-described nonvolatile memory (10) is considered described electronic logic request and is received the number of times that resets.

If-the number of times that accepts request surpasses set-point, then described electronic logic is no longer accepted described reset request.

11, control device as claimed in claim 5 (5) is characterized in that, described relay (4) belongs to often opens type.

12, control device as claimed in claim 5 (5) is characterized in that, described relay (4) belongs to normally closed type.

13, as the described control device of the arbitrary claim in front (R), it is characterized in that, two fuses (5) that are arranged to connect with each described relay (4), being made the excess current of contact adhesion with the contact that prevents described relay (4) is feature.

14, as the described control device of the arbitrary claim in front (R); it is characterized in that; at least the function that goes up electric current in the cut off circuit (1) at one of link (2.1) of resistance (2) is to be carried out by one of two relays (4) that the heat protection is provided, because be responsible for that heat is protected and the relay (4) of thermal conditioning is that the periodicity that can carry out equals the type at the desired periodicity of drinking water boiler length of life at least.

15, as the arbitrary claim described control device (R) of front except that right requirement 14; it is characterized in that; at least the function that goes up electric current in the cut off circuit (1) at one of link (2.1) of resistance (2) is only by the alternately execution of one of two relays (4) that the heat protection is provided, and equals type in half of the desired periodicity of drinking water boiler length of life at least because described relay (4) is the periodicity that can carry out.

16, as claim 14 or 15 described control device (R), it is characterized in that, described unified control device (R) can be by being recorded in periodicity in the described nonvolatile memory (10) to come periodicity is counted, and be programmed to disconnect described two relays (4), thereby in case reached setting cycle and count them and just can not be resetted by the user.

17, accessory rights requires the described control device of arbitrary front claim (R) of 14 beginnings, it is characterized in that, described control device (R) can detect fault and disconnect one of described relay (4) that is disconnected by order, and is programmed to another relay (4) that order is right after subsequently and can not disconnects with resetting.

18, a kind of control device (R) that is used for electric water boilers thermal conditioning and heat protection function is characterized by:

The thermal conditioning of water in the-container is regulated about temperature (t.r) so that its temperature remains on to set,

-Re protection prevents from the water in the container is heated to above the temperature that is lower than maximum safety temperature (t.s) by temperature (t.i),

It is characterized in that:

-when detecting fault,, activate the shutoff action of drinking water boiler heating function no matter whether reached dangerous temperature.

19, as the described control device of front claim (R), it is characterized in that having only when not having further to cause the situation of shutoff, user's operating conditions in the thermal conditioning pattern that can reset.

As the described control device of front claim (R), it is characterized in that 20, the user only is allowed to carry out reset operation predetermined time.

As the arbitrary claim described control method of front since 16, it is characterized in that 21, the abnormal operation situation is regarded as comprising and is higher than the temperature value reading of setting by temperature (t.i) in the drinking water boiler.

22, as the arbitrary claim described control method of front since 16, it is characterized in that, the abnormal operation situation be regarded as comprising in the drinking water boiler obvious Yin Wendu read with telltale in the temperature value reading that causes of fault.

23, as the arbitrary claim described control method of front since 16, it is characterized in that the proper operation and the function of control system are monitored, and if described operation be considered to incorrect, then drinking water boiler is turned off.

24, as the described control device of the one or more claims in front (R), it is characterized in that:

-power supply is a three-phase supply,

-the some resistance that are connected into △ shape or star (2) are provided,

The sufficient amount device that-blocking-up electric current (3) passes through is a feature to prevent that in the thermal conditioning process electric current from passing through all described resistance (2),

-at hot guard period, be feature with the circuit (1) of all links (2.1) of being used to disconnect all described resistance (2).

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