WO2013160111A1 - Single-circuit refrigerator and operating method therefor - Google Patents

Description

 Single-circuit refrigeration unit and operating method for this

The present invention relates to a refrigerator, in particular a domestic refrigerator, with a first and a second storage compartment, which are cooled by connected in series with a compressor evaporator, and an operating method for such

The refrigerator.

In a refrigerator with evaporators connected in series, also referred to as a single-circuit refrigeration device, the refrigerant can circulate either only by both evaporators simultaneously when the compressor is operating, or by neither of the two evaporators when the compressor is not in operation. If such a refrigeration device conventionally has a temperature sensor on one of the storage compartments and a control unit switches the compressor on and off based on the temperature detected by this temperature sensor, there is the problem that when warm goods to be refrigerated are loaded into the storage compartment not monitored by the temperature sensor and is to be cooled therein, the control unit is unable to take this into account. The cooling of the newly loaded refrigerated goods can therefore take a very long time, and the durability of existing refrigerated goods can be affected by this is heated by the newly loaded refrigerated goods. This problem is especially disturbing when the temperature sensorless

Storage compartment is a freezer compartment and it is to be frozen in the newly loaded refrigerated goods, as this the refrigerated goods a large amount of heat must be withdrawn.

A known technique for accelerating the freezing operation in a single-circuit refrigerator is known as "super-operation." While in a normal refrigeration mode of the refrigeration appliance, the control unit compares the compressor with a comparison of the

When the temperature sensor detects and turns off the detected temperature at a user-adjustable setpoint temperature, it does so in the superb mode by comparing it with a fixed set temperature, which is generally much lower than the user-set temperature. If the storage compartment on which the temperature sensor is located is a standard cooling compartment, then the setpoint temperature is in Super cooling mode generally just above freezing, so that freezing of refrigerated goods in the normal tray is just avoided.

The super cooling mode affects the energy efficiency of such a device, as inevitably both storage compartments are cooled down, even if only in the freezer compartment, a higher cooling capacity than normal is needed. In addition, the need to avoid undercooling and, in particular, freezing in the normal refrigeration compartment, necessitates regular interruptions of compressor operation, thus extending the time required to freeze newly refrigerated goods in the freezer compartment. The object of the invention is to provide a refrigeration device and an operating method for this, which is a fast and energy-efficient cooling of newly loaded refrigerated goods

enable.

The object is achieved on the one hand by a refrigeration device, in particular a household refrigerator, with a compressor, an upstream and a

downstream evaporators connected in series with the compressor, a first storage compartment cooled by the upstream evaporator, and a second storage compartment cooled by the downstream evaporator and a control unit configured to operate in a normal cooling mode the compressor based on a comparison of the temperature measured by a temperature sensor in one of the storage compartments temperature with a first setpoint to control and from the

Normal cooling mode by a user in an intensive cooling mode is switchable, the intensive cooling mode at least one phase of long compressor operating times, in which the control unit controls the operation of the compressor based on a comparison of the measured temperature with a second setpoint, which is lower than the first setpoint, and a phase short Compressor operating times, in which the circulated by the compressor between a switch on and the subsequent shutdown

Refrigerant is smaller than the capacity of the two evaporators for liquid refrigerant.

Since the amount of liquid refrigerant that enters the evaporators in the phase of short operating times, in each case between a switch-on and a switch-off, ie in an operating phase of the compressor, although sufficient to the upstream To fill evaporator, but not for the downstream, eliminates in this phase, a relatively large proportion of the cooling capacity of the compressor to the first storage compartment cooled by the upstream evaporator. The first storage compartment or newly stored refrigerated goods can therefore be cooled faster than by a conventional

Super operation, in which such a preference of the first storage compartment is not possible.

In order to selectively supply only the upstream evaporator with liquid refrigerant in a phase of short compressor run times, the amount of refrigerant circulated in the phase of short compressor operating times in each compressor operating time should correspond as closely as possible to the capacity for liquid refrigerant of the upstream evaporator. The amount of refrigerant circulated should therefore in any case be between 0.5 and 1.5 times the capacity of the

amount upstream evaporator.

If the volumetric capacity of the evaporator and the throughput of the compressor are known, the control unit can monitor the elapsed time since the last time the compressor was switched on and then switch the compressor off again when the desired amount of refrigerant has been established. Alternatively, it may be considered to use a temperature sensor located on one of the evaporators to monitor the advance of liquid refrigerant in the evaporators and to turn the compressor off again when cooling at the location of the temperature sensor indicates that the desired amount of refrigerant is circulating. Such a

Temperature sensor is conveniently located in the vicinity of a refrigerant outlet of the upstream evaporator or a refrigerant inlet of the downstream evaporator.

Preferably, the control unit is configured to switch when in the

Intense cooling mode first to control a phase of long operating times and then a phase of short operating times. Since in the phase of long operating times both

Storage compartments are cooled, the phase of short compressor run times, in which essentially only the first storage compartment is cooled, then a long time

be maintained, without causing excessive heating of the second storage compartment. The temperature sensor should expediently be arranged on the second storage compartment.

This makes it possible in particular, the control unit a phase short

Start compressor operating times when the temperature at the second storage compartment falls below a limit.

Alternatively, a phase of short compressor operating times may also be started in each case after a predetermined duration of a phase of long compressor operating times.

Conveniently, the control unit should be set up to switch on the compressor at a predetermined time interval after switching to the intensive cooling mode. Thus, if a user knows in advance when to load the new refrigerated goods, by timely switching to the intensive refrigeration mode, if the new goods to be refrigerated are actually loaded, the compressor will start up at the same time as cooling power to freeze the new goods thus immediately available.

A particularly rapid cooling of the new chilled goods can be achieved if, simultaneously with the switching on of the compressor, a phase of long compressor operating times also begins.

In practice, it is generally difficult to predict to the minute exactly when new refrigerated goods to be loaded will be ready. This can be accommodated by, if the refrigerator has a door and a door sensor for detecting an actuation of the door, the control unit does not turn on the compressor immediately after switching to the intensive cooling mode at the predetermined time interval, but initially only one time window opens, and the Compressor then turns on when an operation of the door is detected in the time window. So the switching on of the compressor with the

Invite the goods to be synchronized exactly, even if the time of the invitation is not exactly predictable.

The specified time interval should be several hours to ensure sufficient cooling before loading the new chilled goods. It is expedient if the predetermined time interval is an integer multiple of 24 hours; Deviations of up to +6 or - 6 hours from this value are also possible.

The invention also provides a method for controlling a compressor in a refrigerator, in which the compressor is connected in series with an upstream and a downstream evaporator, which cool a first or a second storage compartment, with the steps:

a) in a normal cooling mode, controlling the operation of the compressor based on a comparison of the temperature measured by a temperature sensor in one of the storage compartments with a first set value;

b) upon detection of a user input, switching to an intensive cooling mode, the at least one phase of long compressor operating times in which the operation of the compressor is controlled based on a comparison of the measured temperature with a second setpoint lower than the first setpoint and a phase shorter

Compressor operating times in which the volume of refrigerant circulated from the compressor between a switch on and the subsequent shutdown is smaller than the capacity of the two evaporators for liquid refrigerant.

Further features and advantages of the invention will become apparent from the following description of embodiments with reference to the accompanying figures. From this description and the figures are also features of the

 Embodiments, which are not mentioned in the claims. Such features may also occur in combinations other than those specifically disclosed herein. Therefore, the fact that several such features are mentioned in the same sentence or in a different type of textual context does not justify the conclusion that they can occur only in the specific combination disclosed;

instead, it must be assumed that, of several such characteristics, it is also possible to omit or modify individual ones, provided that this is the case

Functionality of the invention is not in question. FIG. 1 is a schematic representation of a device according to the invention. FIG

Refrigeration unit; 2 shows the change of Verdichterbetriebs- and -nichtbetriebszeiten in a first embodiment of the refrigeration device.

3 shows a flowchart of a method of operation of a control circuit of the refrigeration device.

Fig. 1 shows schematically a single-circuit household refrigerator with a heat-insulating housing 1, the interior of which is divided into two storage compartments, here a freezer compartment 2 and a normal refrigeration compartment 3. The subdivision here is a wall 4, which, like the compartments 2, 3 surrounding walls of the housing 1 is filled with insulating material; but the two compartments 2, 3 could also be formed in a contiguous interior of the housing 1 or only by a the air exchange between them obstructing

Be separated wall.

Both compartments 2, 3 are each assigned an evaporator 5 and 6, respectively. The evaporators 5, 6 are shown here as a coldwall evaporator, but there are others

 Evaporator types into consideration. The evaporators 5, 6 can on separate boards or on a single, the wall 4 bridging over both compartments 2, 3rd

be formed extending board. The evaporators 5, 6 are part of a refrigerant circuit, which further comprises, in a manner known per se, a compressor 7, a condenser 8, for example, attached to a rear wall of the housing 1, a dryer 9 and a capillary 10. Refrigerant, which has been compressed and heated in the compressor 7, gives off its heat at the condenser 8 and condenses. The liquid refrigerant relaxes when passing through the capillary 10 and reaches from there first the evaporator 5 of the freezer, where it can evaporate under low pressure. The evaporator 6 connects downstream to the evaporator 5, and its output is connected to a suction port of the compressor 7. A control circuit 1 1 is used to turn on and off the compressor based on temperature readings that are supplied by an evaporator temperature sensor 12 and an air temperature sensor 13. The evaporator temperature sensor 12 is in tight thermal contact with the evaporator 6, preferably on the board of the

Evaporator 6, mounted.

The evaporator temperature sensor 12 should be disposed on the evaporator 6 adjacent to an upstream portion of the refrigerant line running on the evaporator 6 to react quickly when fresh refrigerant is lower

Temperature from the evaporator 5 penetrates into the evaporator 6. It is also expedient to attach the evaporator temperature sensor 12 in the lower region of the evaporator 6, so that the temperature sensor 12 during a defrosting reliable

Provide information about the residues inventory that collects during defrosting at the bottom of the evaporator 6. The structure shown in Fig. 1 satisfies these two

Requirements at the same time by the refrigerant line runs on the evaporator 6 from a refrigerant inlet 14 at the top of first directly down to the lower corner of the evaporator 6, in which the evaporator temperature sensor 12 is mounted, and then in meandering over the surface of the evaporator 6 spreads.

The measured value of the air temperature sensor 13 should reproduce the air temperature in the normal cooling compartment 3 as exactly as possible. For this purpose, the air temperature sensor 13 is arranged in a wall of the housing 1 between the insulating material filling and a normal cooling compartment 3 limiting inner container removed from the evaporator 6.

The compartments 2, 3 each have an interior light, not shown here, which is turned on and off by a switch actuated in a conventional manner by the door of the compartment. Of these two switches, FIG. 1 shows only the switch designated by 16 of the freezer compartment 2.

A user interface of the refrigerator comprises an operating mode selector switch 17 connected to the control circuit 11. The operating mode selector switch 17 serves at least for switching from a normal refrigeration mode to an intensive refrigeration mode. Switching back from intensive to normal cooling mode can be repeated

Operation of the operating mode selector switch 17 or time-controlled, after expiry of a maximum permissible duration of the intensive cooling mode. FIG. 2 shows by way of example the operating state, switched on or off, of the compressor 7 over time in the normal cooling mode and in the intensive cooling mode. At time t0, the refrigeration device is in the normal cooling mode. A setpoint temperature of

Normal cooling compartment 3 is in a conventional manner to a controller of

User interface adjustable by the user. The control circuit 1 1 always turns on the compressor 7 when the temperature Tnk detected by the temperature sensor 13 in the normal cooling compartment 3 exceeds a switch-on threshold Tein, which is the

Setpoint temperature plus a small tolerance value corresponds, and switches it off again, as soon as a lying by a predetermined amount below the setpoint temperature

Switch-off threshold Taus is undercut. This results in switch-on phases At1 of medium duration, which alternate with relatively long switch-off phases AtO.

When the user switches to the intensive cooling mode at time t1 by operating the operation mode selection switch 17, the result is that the

Control circuit 1 1 no longer used by the user set on the controller setpoint temperature on and off thresholds Tein, Taus used, but on and off thresholds Tein ', Taus', in a corresponding manner from a specified by the manufacturer of the device, significantly lower temperature are derived. In practice, in particular a switch-off threshold Taus' is used, which is only so far above 0 ° C, as is necessary to avoid a local underrun of the freezing point in the normal cooling compartment 3. That the closer to the evaporator 6 of the normal cooling compartment 3 the temperature sensor 13 is arranged, the closer to the freezing point Taus' can be selected.

By lowering the switch-on and switch-off thresholds result - especially shortly after switching to the intensive cooling mode, when the normal refrigeration compartment 3 is still significantly warmer than the deep switch-off threshold Taus', compared to

Normal operation mode significantly longer switch-on phases At1 'and shorter

Off phases AtO ', and both compartments 2, 3 are rapidly cooled. This effect slows down when the local mean of the temperature of the

Normal cooling compartment 3 of the deep switch-off threshold Taus' approaches. The reason for this is that the normal cooling compartment 3 cools homogeneously over time. While in one

Initial phase of the intensive cooling mode as seen from the evaporator 6 from beyond Temperature sensor 13 lying region of the normal refrigeration compartment is still substantially at the set by the user set temperature and in a downtime of the compressor heat from this area quickly to the temperature sensor 13 and in the lying between the temperature sensor 13 and the evaporator 6 range of

Normal cooling compartment 3 propagates decreases gradually over the course of several compressor operating times of the temperature gradient in the normal cooling compartment 3, so that the downtime of the compressor is longer and the operating times are shorter. This in turn prevents intensive cooling of the freezer compartment 2.

In order nevertheless to be able to provide sufficient cooling capacity in the freezer compartment 2 for quickly freezing newly loaded refrigerated goods, the control circuit 1 1, in the context of the intensive cooling mode, moves into a phase shorter at a time t 2

Compressor operating hours. For this purpose, the compressor 7 is first turned off at the time t2 for a time AtO "whose length is such that it is sufficient to evaporate the liquid refrigerant present in the evaporator 5 of the freezer compartment 2.

Thereafter, the compressor 7 operates for a period of time At1 ", the length of which may be timed or controlled by the temperature sensor 12. In the case of timing, the compressor 7 is operated as long as it is aware of the flow rate of the compressor 7 and the capacity of the evaporator 5 required to displace the refrigerant vapor from the evaporator 5 into the evaporator 6 and to fill up the evaporator 5 with fresh, liquid refrigerant In the case of a control by means of the temperature sensor 12, the compressor 7 is operated until a

Temperature drop at the temperature sensor 12 indicates that liquid refrigerant has penetrated through the evaporator 5 to the temperature sensor 12. In one case as in the other case, practically only the evaporator 5 of the freezer compartment 2 is supplied with liquid refrigerant, whereas in the evaporator 6 only refrigerant vapor arrives. In this way, the freezer compartment 2 is further cooled with high performance, while on the normal cooling compartment 3 as good as no more cooling capacity. The resulting over time heating of the normal cooling compartment 3 can be accepted, since this is colder anyway, as the set by the user set temperature corresponds; heating of the normal refrigeration compartment 3 is even desirable since, after a few hours, at a time point t3, when the temperature in the normal refrigeration compartment 3 has returned to near the user-set target temperature, Return to the control of the compressor based on the specified low thresholds Taus ', Tein' allows.

FIG. 3 shows a flowchart of a working method of the control circuit 11 according to a further developed embodiment of the invention. At the beginning of the method, the method is in the normal cooling mode: In step S1, it is checked whether the temperature Tnk of the temperature sensor 13 is above the switch-on threshold Tein, and if so, the compressor 7 is turned on in step S2. If not, it is checked in step S3 whether the temperature Tnk is below the turn-off threshold Toff, and if so, the compressor 7 is turned off in step S4. Step S5 checks if a user input,

in particular, an operation of the mode selector switch 17, is present. If this is not the case, the method returns to the output. Thus, steps S1-S5 are repeated in an endless loop as long as the normal cooling mode continues.

The user of the refrigerator is stopped, if he wants to re-store and freeze a larger amount of fresh refrigerated goods, in good time before, at a time interval D from the intended time of storage, to activate the intensive cooling mode. The time interval D can be in particular 24 h or an integer multiple thereof.

If the intensive cooling mode has been activated at time t1, the

Control circuit in step S6 a timer in motion. This is followed by a comparison S7 of the temperature Tnk with a predetermined low switch-on threshold Tein 'and, at

Exceeding this switch-on threshold, switching on S8 of the compressor. In step S9, it is checked whether a predetermined low switch-off threshold Taus' is exceeded, and if so, in step S10, the compressor 7 is switched off again. In step S1 1 it is checked whether a predetermined period of time d has elapsed since the start S6 of the timer. The period of time d is D - n (At0 "+ At1") - At0 ", where n is a natural number and n (At0" + At1 ") should be several hours, and if this time has not yet elapsed, the method returns Otherwise, the compressor 7 (if not already turned off at the time of the inspection S1 1) is turned off in step S12, the lapse of one

Off time AtO "is awaited (S13), the compressor is turned on in step S14, and the lapse of the on time At1" is awaited (S15). Steps S12 to S15 is cyclically repeated until it is determined in step S17 that the predetermined time period D has elapsed since the start of the timer in step S6. Due to the above definition of the period of time, the end of the period D always coincides with the end of a turn-off time. When the period of time D has elapsed, the process returns to step S7 to store refrigerated goods which are assumed to be in that at that time

Freezer 2 has been charged to freeze quickly.

If, since the start of the timer, a time which is likely to be sufficient for freezing the chilled goods, e.g. 48 hours elapsed, then this is detected in step S16 and causes the process to return to normal operation S8.

According to a variant, it can be provided that, after the time period D has elapsed, step S17 does not unconditionally return to step S7, but that a time window is opened whose duration is preferably not greater than At0 "+ At1", and in that time window Control circuit 1 1 waits for a signal of the switch 16, which indicates an access of a user to the freezer compartment 2. If this signal arrives, it can be concluded that actually new refrigerated goods have been stored, and the control circuit 1 1 responds by now jumping to step S7. Thus, the start of the compressor and the invitation of the item to be chilled are exactly synchronized. If the time window lapses without the switch 16 indicating a door actuation, then the method also returns to step S7 to keep the compartments of the refrigerator cold in the event that, albeit later than intended, new refrigerated goods are still being loaded.

If the late loading occurs while the control circuit repeats the steps S12 to S15 in a loop, it may be provided that the door operation triggers a jump to step S7.

Claims

Refrigerating appliance, in particular household refrigerating appliance, with a compressor (7), an upstream and a downstream evaporator (5, 6) connected in series with the compressor (7), a first storage compartment (2) which is filled by the upstream evaporator (5 ), and a second storage compartment (3) which is cooled by the downstream evaporator (6), and a Control unit (1 1), which is arranged in a normal cooling mode (S1 -S5), the operation of the compressor (7) based on a comparison of a Temperature sensor (13) in one of the storage compartments (3) measured temperature (Tnk) with a first setpoint to control and can be switched from the normal cooling mode by a user in an intensive cooling mode, characterized characterized in that the intensive cooling mode at least one phase of long compressor operating times ([t1, t2]; S6-S1 1), in which the control unit (1 1) the operation of the compressor (7) based on a comparison of the measured temperature (Tnk) with a second Setpoint controls that is lower than the first setpoint, and a phase of short compressor operating times ([t2, t3]; S12-S17) in which the amount of refrigerant circulated by the compressor (7) between a switch on and the subsequent shutdown is smaller than Capacity of the two evaporators (5, 6) for liquid refrigerant. Refrigerating appliance according to claim 1, characterized in that the quantity of refrigerant circulated in the phase of short compressor operating times ([t2, t3], S12-S17) between a switching on and the subsequent switching off from the compressor (7) is between 0.5 times and which is 1.5 times the liquid refrigerant capacity of the upstream evaporator (5). Refrigerating appliance according to claim 1 or 2, characterized in that the Control unit (1 1) is arranged, when switching to the intensive cooling mode first to control a phase of long compressor operating times ([t1, t2]; S6-S1 1) and then a phase of short compressor operating times ([t2, t3]; S12-S17). Refrigerating appliance according to one of the preceding claims, characterized in that the temperature sensor (13) is arranged on the second storage compartment (3). Refrigerating appliance according to claim 4, characterized in that the control unit (1 1) is adapted to start a phase of short compressor operating times when the temperature at the second storage compartment falls below a threshold value. Refrigerating appliance according to claim 3 or 4, characterized in that the Control unit is set, after a predetermined duration of a phase of long compressor operating times ([t1, t2]; S6-S1 1) a phase short Compressor operating times ([t2, t3]; S12-S17) to begin. Refrigerating appliance according to one of the preceding claims, characterized in that the control unit (1 1) is arranged to switch on the compressor (1 1) at a predetermined time interval from the switching (t 2; S 6) into the intensive cooling mode. Refrigerating appliance according to one of claims 1 to 6, characterized in that it comprises a door and a door sensor (16) for detecting an actuation of the door and the control unit (1 1) is arranged at a predetermined time interval from the switching (t2, S6 ) in the intensive cooling mode to define a time window and to turn on the compressor (7) when in the time window, an operation of the door is detected. Refrigerating appliance according to claim 7 or 8, characterized in that the Control unit (1 1) is arranged to start at the predetermined time interval from the switching over a phase of long compressor operating times ([t3, ...]; S6-S1 1). Refrigerating appliance according to claim 7, 8 or 9, characterized in that the predetermined time interval deviates by a maximum of + 6h or -6h from an integer multiple of 24 h. Method for controlling a compressor in a refrigeration appliance, in which the  Compressor with an upstream and a downstream evaporator (5, 6) is connected in series, the first and a second storage compartment (2, 3) cool, comprising the steps: a) in a normal cooling mode (S1 -S5) controlling the operation of the compressor (7) based on a comparison of the measured by a temperature sensor (13) in one of the storage compartments (3) temperature (Tnk) with a first setpoint value; b) upon detection of a user input (S5), switching to a Intensive cooling mode (S6-S1) comprising at least one phase ([t1, t2]; S6-S1 1) of long compressor operating times (At1 ') in which the operation of the compressor (7) is compared with a comparison of the measured temperature (Tnk) second setpoint lower than the first setpoint, and a phase ([t2, t3]; S12-S17) of short compressor operating times (Δί1 ") in which the compressor (7) between a turn-on and the subsequent turn-off circulated amount of refrigerant is smaller than the capacity of the two evaporators (5, 6) for liquid refrigerant.