EP4051972A1

EP4051972A1 - Refrigeration appliance comprising a compartment that can be heated and cooled

Info

Publication number: EP4051972A1
Application number: EP20797692.9A
Authority: EP
Inventors: Andreas BABUCKE; Oliver Janda; Niels Liengaard; Clemens Mack; Matthias Mrzyglod; Vitali ULRICH; Carsten Weiss
Original assignee: BSH Hausgeraete GmbH
Current assignee: BSH Hausgeraete GmbH
Priority date: 2019-10-28
Filing date: 2020-10-19
Publication date: 2022-09-07
Also published as: CN114616432B; CN114616432A; WO2021083697A1; US20220364781A1; DE102019216582A1

Abstract

The invention relates to a refrigeration appliance, in particular a domestic refrigeration appliance, comprising at least a first, a second and a third storage chamber (2, 3, 4), and a refrigerant circuit on which the following are connected in series between a pressure connection and a suction connection of a compressor (14): a condenser (15), a first expansion valve (17), a first heat exchanger (5) of the first storage chamber (2), a second expansion valve (18), and a second heat exchanger (6) of the second storage chamber (3), a third heat exchanger (7) associated with the third storage chamber (4), and a control circuit (13) for controlling the operation of the compressor (14) and the expansion valves (17, 18). The third heat exchanger (7) is connected in series downstream of the second heat exchanger (6). The control circuit (13) is designed to maintain a higher storage temperature (T4s) in the third storage chamber (4) than in the second storage chamber (3).

Description

Refrigeration device with a compartment that can be heated and cooled

The present invention relates to a refrigeration device, in particular a household refrigeration device, with at least one storage compartment that can be optionally heated or cooled.

Such a refrigeration device is known from DE 102016032 986 A, for example. In this known refrigeration device, heat exchangers of the heatable and coolable compartment and a first cooled compartment, each with an upstream and a downstream expansion valve, are arranged in parallel line strands of the refrigerant circuit, and both strands open onto the evaporator of a second cooled compartment. Since the pressure in the latter evaporator is lower than in each of the heat exchangers, the second refrigerated compartment is inevitably the coldest, i.e. the first refrigerated compartment can be considered as a normal refrigerator compartment, the second as a freezer compartment. In order to implement three different temperature zones in the refrigeration device, four expansion valves are therefore required, which makes the known refrigeration device relatively expensive. In addition, its refrigerant circuit is sensitive to overflowing the heat exchangers, which makes a sensitive and correspondingly complex control necessary.

One object of the present invention is therefore to create a refrigeration device with a storage compartment that can be heated and cooled, which is more simply constructed and can accordingly be implemented cost-effectively. Another object is to create an operating method for such a refrigeration device.

The object is achieved on the one hand in that in a refrigeration device, in particular a household refrigeration device, with at least a first, a second and a third storage chamber, a refrigerant circuit, on which the following are connected in series between a pressure connection and a suction connection of a compressor: a condenser, a first expansion valve, a first heat exchanger of the first storage chamber, a second expansion valve, and a second heat exchanger of the second storage chamber; a third heat exchanger assigned to the third storage chamber and a Control circuit for controlling the operation of the compressor and the expansion valves, the control circuit is set up to maintain a higher storage temperature in the third storage chamber than in the second storage chamber.

In this design, two expansion valves are still required to set the mass flow through the first heat exchanger and the pressures in the first and second heat exchangers, but the temperature of the third storage chamber can be regulated without resorting to expansion valves by using only refrigerant vapor or steam and, as required liquid refrigerant can be let through in variable proportions from the second to the third heat exchanger. An overflow of the second heat exchanger does not lead to malfunctions and does not have to be suppressed by control technology, but is part of normal operation of the refrigeration device, as it enables the third heat exchanger to be supplied with liquid refrigerant.

The connection between the second and third heat exchanger does not require any further expansion valve; on the contrary, this connection should be as free as possible of throttle points which impede the passage of refrigerant to the third heat exchanger or promote a pressure difference between the second and third heat exchanger. The smallest free cross section of a refrigerant line connecting the heat exchangers is preferably essentially the same size, but in any case at least half as large as a mean free cross section of lines of the heat exchangers.

The speed of the compressor should be adjustable to a large number of values, preferably continuously, so that fluctuations in the temperature in the storage chambers over time and the additional consumption of electrical energy associated with these fluctuations can be minimized by uninterrupted operation of the compressor.

The control circuit is preferably set up to increase the speed of the compressor if the temperature of the second storage chamber is above a setpoint value and / or to reduce the speed of rotation if the temperature of the second storage chamber is below a setpoint value. By increasing the compressor speed, the pressure in a suction line leading to the compressor and via this also the pressure in the second and third heat exchanger can be lowered. Since the cooling effect of the third heat exchanger is largely not based on the evaporation of liquid refrigerant in it, but rather on the vapor flowing through it originating from the second heat exchanger, the change in speed influences the cooling effect of the third heat exchanger at most slightly; On the other hand, the pressure decrease has a direct effect on the evaporation of the refrigerant taking place in the second heat exchanger.

The above mentioned setpoints can be identical; but you can also define the limits of an interval within which the speed of the evaporator remains unchanged.

In order to regulate the temperature in the third storage chamber, the control circuit is preferably set up to increase the degree of opening of the first expansion valve when the temperature of the third storage chamber is above a target value, and / or to decrease the degree of opening of the first expansion valve when the temperature of the third storage chamber is below a target value. Although the first expansion valve and the third heat exchanger in the refrigerant circuit are separated in one direction by two heat exchangers and the second expansion valve and in the other by the compressor, an adjustment of the first expansion valve surprisingly affects the third heat exchanger in particular. Opening the first expansion valve initially causes a reduction in the throttling effect of the entire refrigerant circuit. The pressure in the second and third heat exchanger changes only slightly because of the fact that the throughput of the compressor increases as this pressure increases while the speed remains the same. As a result, the main consequence of opening the first expansion valve is an increased flow of liquid refrigerant through the second expansion valve and consequently, at the latest after the second heat exchanger is completely filled with liquid refrigerant, an increased supply of liquid refrigerant to the third heat exchanger and thus increased cooling the third storage room.

The control circuit can also be configured to increase the degree of opening of the second expansion valve when the temperature of the third storage chamber is above a setpoint value and / or to reduce the degree of opening of the second expansion valve when the temperature of the third storage chamber is below a setpoint value. A decision as to which of these two options is to be used is expediently made on the basis of a comparison of the setpoint temperature of the first storage chamber with the ambient temperature.

In order to control the temperature of the first storage chamber, the control circuit can be configured to increase the degree of opening of the second expansion valve when the temperature of the first storage chamber is above a target value, and / or to decrease the degree of opening of the second expansion valve when the temperature of the first Storage chamber is below a target value.

Alternatively, the control circuit can be configured to increase the degree of opening of the first expansion valve when the temperature of the first storage chamber is below a setpoint value and / or to reduce the degree of opening of the first expansion valve when the temperature of the first storage chamber is above a setpoint value.

Here, too, the choice between the alternatives can be made on the basis of a comparison of the setpoint temperature of the first storage chamber with the ambient temperature.

A third expansion valve, a fourth heat exchanger of a fourth storage chamber and a fourth expansion valve can be connected to one another in series and connected in parallel to the first expansion valve, the first heat exchanger and the second expansion valve. In this way, several compartments that can be optionally heated or cooled can be created in the refrigerator.

The temperatures in these compartments can be set independently of one another by adjusting the evaporation pressures using the upstream and downstream expansion valves.

In a refrigeration device with a fourth storage chamber as described above, the degree of opening of the third expansion valve can also be increased if the temperature of the third storage chamber is above a target value, and / or the degree of opening of the third expansion valve can be reduced if the temperature of the third storage chamber is below a target value lies. If desired, further storage chambers can be provided, each with an assigned heat exchanger and the expansion valves connected upstream and downstream of this in a branch of the refrigerant circuit.

A fan for driving the exchange of air between the heat exchanger and the storage chamber can be assigned to at least one of the heat exchangers. Such a fan is advantageous in order to intensify the heat exchange with the storage chamber and thus to achieve a high exchange rate with a compact heat exchanger. They are not absolutely necessary to control the cooling of the various storage chambers. In the simplest case, such a fan can therefore be operated at an unregulated or fixed speed.

In particular if a storage chamber is operated in a cooled manner, it can be useful to regulate the speed of the fan based on a predetermined temperature difference between the evaporator and the storage chamber in order to reduce the extent to which the air in the storage chamber is dried by condensation on the evaporator or the Adjust the moisture content of the air.

The object is also achieved by a method for operating a refrigeration device as described above with the steps:

Increasing the degree of opening of the second expansion valve when the temperature of the first storage chamber is above a target value, and / or reducing the degree of opening of the second expansion valve when the temperature of the first storage chamber is below a target value.

Increasing the speed of the compressor when the temperature of the second storage chamber is above a setpoint value and / or lowering the speed when the temperature of the second storage chamber is below a setpoint value;

Opening the first expansion valve when the temperature of the third storage chamber is above a setpoint value, and / or reducing the degree of opening of the first expansion valve when the temperature of the third storage chamber is below a setpoint value, as well as by a computer program product which includes instructions that, when executed enable a computer to act as a control circuit in one To work refrigeration device as described above or to carry out the above-mentioned method.

Further features and advantages of the invention emerge from the description of exemplary embodiments with reference to the accompanying figures. Show it:

1 shows a block diagram of a refrigeration device according to the invention; and

2 shows a flow diagram of an operating method of the refrigeration device.

Fig. 1 shows a block diagram of a refrigeration device according to the invention. At least three bearing chambers 2, 3, 4 are recessed in a heat-insulating housing 1. A heat exchanger 5, 6, 7 is assigned to each of these storage chambers 2, 3, 4. The assignment can consist in the fact that the heat exchanger is embedded in the manner of a cold wall evaporator between an inner container of the storage chamber and an insulating material layer surrounding the inner container, or that the heat exchanger 5, 6, 7 is embedded in the inner container 8 of the relevant storage chamber 2, 3 , 4 is mounted. In the latter case, a partition 9 can be provided in the inner container, which divides the volume of the inner container into the storage chamber 2, 3, 4 and a heat exchanger chamber 10 accommodating the heat exchanger 5, 6, 7. Regardless of how the heat exchanger 5, 6, 7 is assigned to the storage chamber 2, 3, 4, a fan 11 can be assigned to each heat exchanger 5, 6, 7 to prevent the heat transfer between the storage chamber 2, 3, 4 and its heat exchanger 5 , 6, 7 intensify. The speed or power of such a fan 11 can be predetermined or, as will be explained in more detail below, controllable.

Each storage chamber 2, 3, 4 is equipped with a temperature sensor 12. Measured values from the temperature sensors 12 are recorded by a control circuit 13.

Starting from a pressure connection of a compressor 14, a refrigerant circuit comprises, one after the other, a condenser 15, a pressure line 16, a first expansion valve 17, the heat exchanger 5, a second expansion valve 18, the second heat exchanger 6, the third heat exchanger 7 and a suction line 19 which leads to a suction connection of the compressor 14. The expansion valves 17, 18 are from Design known per se, not described here, and designed to maintain a pressure difference between inlet and outlet that is predetermined by a control signal. The source of the control signals is the control circuit 13. The pressure line 16 and the suction line 19 run in opposite directions over part of their length in close contact with one another in order to form an internal heat exchanger 22 in which the compressed refrigerant passes to the residual heat shortly before reaching the expansion valve 17 Vents in the suction line 19.

The pressure difference that can be set at the expansion valve 17 is variable within wide limits. On the one hand, the expansion valve 17 allows a pressure to be set in the heat exchanger 5 that differs only slightly, if at all, from the pressure at the pressure connection of the compressor 14, so that refrigerant condensation takes place in the heat exchanger 5 as in the condenser 15 and the storage chamber 2 at a set temperature can be operated above ambient temperature, and refrigerant condensed in the condenser 15 and heat exchanger 5 is fed to the heat exchangers 6 and 7 via the expansion valve 18. An upper limit of the temperature at which the storage chamber 2 can be operated should not be below + 18 ° C.

The requirements for the expansion valve 18 are less stringent: in order to enable the storage chamber 3 to be operated as a freezer compartment, a non-negligible pressure drop at the expansion valve 18 is necessary even if the storage chamber 2 is operated as a normal refrigeration compartment. The maximum pressure difference at the expansion valve 18 should be sufficient to enable freezer operation of the storage chamber 3 even when essentially the full output pressure of the compressor 14 is present at the inlet of the expansion valve 18.

There is no significant pressure drop between the heat exchangers 6 and 7. In particular, both heat exchangers 6, 7 and a line connecting them can be manufactured from the same type of tube with constant cross-sectional dimensions.

Setpoint temperatures for all three storage chambers 2, 3, 4 can be set on a user interface 20 of the control circuit 13. If one of the storage chambers 2, 3, 4 has a fan 11, the user interface 20 can also provide the option of selecting a humidity value for the relevant storage chamber. 2 shows a flow chart of a working method of the control circuit 13. In step S1, the temperatures T2, T3. T4 in storage chambers 2,

3, 4 measured. In step S2, the setpoint temperature T2s set by the user for the storage chamber 2 is compared with the ambient temperature T _env . If the former is lower, that is, if the storage chamber 2 is being cooled, the method goes to step S3.

In step S3, the temperature T2 is compared with the target temperature T2s. If both values T2, T2s agree within a predetermined tolerance interval, the method goes directly to step S4. If the measured temperature T2 is significantly lower than T2s, then the control circuit reduces the degree of opening of the expansion valve 18 (S5) in order to increase the pressure or the boiling temperature of the refrigerant in the heat exchanger 5 in this way. The reduction in the degree of opening can consist in an increase in the pressure difference to be maintained between the heat exchangers 5 and 6 by the expansion valve 18. Conversely, in step S6 the degree of opening is increased (or the pressure difference is reduced) if the temperature T2 is significantly higher than T2s.

The extent to which the pressure difference is changed in step S5 or S6 can be a constant, or it can take into account circumstances such as the amount of the difference between T2 and T2s or the period of time that the deviation between T2 and T2s already lasts, in order to minimize the time until correspondence between T2 and T2s is restored or control overshoots.

In step S4, the temperature T3 is compared with the setpoint temperature T3s set by the user for the storage chamber 3. The heat exchanger 6 of the storage chamber 3 always works as an evaporator; To this end, it is continuously supplied with liquid refrigerant during operation, which either condenses in the condenser 15 and only a small part evaporates in the heat exchanger 5, or because condensation has taken place in the heat exchanger 5 in addition to that of the condenser. The heat exchanger 6 is therefore the coldest of the heat exchangers 5, 6, 7, and T3, T3s are normally located in one for one, since it, like the heat exchanger 7, is essentially the suction pressure of the compressor 14 and it is well supplied with liquid refrigerant Freezer compartment typical range below -10 ° C, e.g. around -18 ° C. If both values T3, T3s match within a predetermined tolerance interval, the method goes directly to step S7. If the measured temperature T3 is significantly lower than T3s, then the control circuit 13 reduces the speed of the compressor 14 (S8) in order to increase the pressure or the boiling temperature of the refrigerant in the heat exchanger 6 in this way. Conversely, the speed is increased in step S9 if the temperature T3 is significantly higher than T3s.

The extent to which the speed is changed in step S8 or S9 can be a constant, or it can take into account circumstances such as the amount of the difference between T3 and T3s or the time span that the deviation between T3 and T3s has already lasted, in order to minimize the time until correspondence between T3 and T3s is restored or control overshoots.

In step S7, the temperature T4 is compared with the setpoint temperature T4s set by the user for the storage chamber 4. If the two values T4, T4s match within a predetermined tolerance interval, the method goes back to step S1 after a predetermined waiting time (S12). If the measured temperature T4 is significantly lower than T4s, the control circuit reduces the degree of opening of the expansion valve 17 (S10) in order to reduce the mass flow of the refrigerant and thus to reduce the amount of liquid refrigerant that reaches the heat exchanger 7 . Conversely, the degree of opening is increased in step S11 if the temperature T4 is significantly higher than T4s, so that more liquid refrigerant reaches the heat exchanger 7.

If, on the other hand, it is determined in step S2 that heating mode has been selected for the storage chamber 2, ie if T2s> T _env , then T2 is then also compared with T2s (S3 '), but if T2 is significantly below T2s, the Expansion valve 17 further open (S5 '), or if T2 is significantly above T2s, further closed (S6').

The steps S4, S8, S9 for temperature control in the storage chamber 3 are identical to those described above for the case of the cooling operation in the storage chamber 2. ok

The temperature T4 in the storage chamber 4 is then regulated via the expansion valve 18: if it is determined in step S7 'that this is lower than the target temperature T4s, then the degree of opening of the expansion valve 18 is reduced to reduce the amount of liquid refrigerant in the heat exchanger 7 to decrease (S10 '), in the opposite case (S1T) the degree of opening is increased.

If desired, a fan 21 can be arranged on the condenser 15 in order to blow ambient air over the condenser 15 and thus accelerate the heat dissipation via the condenser 15. The fan 21 can run at a fixed speed. It is also conceivable that the control circuit 13 varies its speed in the same direction as that of the compressor 14 or with the ambient temperature in order to take into account the increased heat accumulation at the condenser 15 with increased compressor output.

The speeds of the fans 11 are independent of the temperatures in the storage chambers 2, 3, 4 and the environment. They can be fixed; in particular in the case of the storage chamber 4 that can be used as a normal refrigeration compartment, it can be useful to give the user at the interface 20 the choice between different power levels or speeds of the fan 11 there. The higher the power of the fan 11, the smaller the temperature difference between the storage chamber 4 and the evaporator 7, which is sufficient to maintain the setpoint temperature T4s of the storage chamber 4. And the higher the temperature of the heat exchanger 7, the smaller the proportion of air humidity from the storage chamber 4 that condenses on the heat exchanger 7 and has to be conducted outside. A high fan output is therefore suitable for storing items that are sensitive to drying out. A lower fan output can be set for items to be cooled that tend to form mold or the like in high humidity.

The same considerations apply to the control of the fan 11 in the storage chamber 2 when this is used as a normal cooling compartment or in a temperature range adjacent thereto, for example as a fresh cooling compartment.

In order to be able to create ideal storage conditions for both items that are sensitive to drying out and items that are sensitive to moisture, it may be desirable to have more than the three storage chambers shown in FIG. 1 available in a refrigeration device to have. For cooling or heating such a further storage chamber, the refrigerant circuit can have a plurality of line strands, which each extend between connection points 23 of the pressure line 16 and 24 of a line connecting the expansion valve 18 to the heat exchanger 6, each of which, analogously to the components 17, 5, 18 has in series an upstream expansion valve, a heat exchanger for the further storage chamber and a downstream expansion valve.

REFERENCE MARK

1 housing

2 storage room

3 storage room

4 storage room

5 heat exchangers

6 heat exchangers

7 heat exchangers

8 inner containers

9 partition

10 heat exchanger chamber

11 fans

12 temperature sensors

13 Control circuit

14 compressors

15 condenser

16 pressure line

17 expansion valve

18 expansion valve

19 suction line

20 User Interface

21 fans

22 internal heat exchanger

23 Connection point

24 connection point

Claims

PATENT CLAIMS

1. Refrigeration device, in particular household refrigeration device, with at least a first, a second and a third storage chamber (2, 3, 4), a refrigerant circuit on which a condenser is connected in series between a pressure connection and a suction connection of a compressor (14) (15), a first expansion valve (17), a first heat exchanger (5) of the first storage chamber (2), a second expansion valve (18), and a second heat exchanger (6) of the second storage chamber (3), one of the third storage chambers ( 4) associated third heat exchanger (7) and a control circuit (13) for controlling the operation of the compressor (14) and the expansion valves (17, 18), characterized in that the third heat exchanger (7) is in series with the second heat exchanger (6) is connected downstream and that the control circuit (13) is set up to maintain a higher storage temperature (T4s) in the third storage chamber (4) than in the second storage chamber (3).

2. Refrigerating device according to claim 1, characterized in that the second and the third heat exchanger (6, 7) are connected to one another without an interposed throttle point.

3. Refrigerating device according to claim 1 or 2, characterized in that the speed of the compressor (14) can be set to a plurality of values, preferably continuously, and the control circuit (13) is set up to increase the speed when the temperature (T3 ) the second storage chamber is above a setpoint value (T3s) and / or to reduce the speed if the temperature (T3) of the second storage chamber is below a setpoint value (T3s).

4. Refrigeration device according to one of the preceding claims, characterized in that the control circuit (13) is set up to increase the degree of opening of the first expansion valve (17) when the temperature (T4) of the third Storage chamber (4) is above a target value (T4s), and / or to reduce the degree of opening of the first expansion valve (17) when the temperature (T4) of the third storage chamber (4) is below a target value (T4s).

5. Refrigerating device according to one of the preceding claims, characterized in that the control circuit (13) is set up to increase the degree of opening of the second expansion valve (18) when the temperature (T4) of the third storage chamber (4) is above a setpoint value (T4s) and / or to reduce the degree of opening of the second expansion valve (18) when the temperature (T4) of the third storage chamber (4) is below a target value (T4s).

6. Refrigerating device according to one of the preceding claims, characterized in that the control circuit (13) is set up to increase the degree of opening of the second expansion valve (18) when the temperature of the first storage chamber (2) is above a setpoint value (T2s), and / or to reduce the degree of opening of the second expansion valve (18) when the temperature (T2) of the first storage chamber (2) is below a target value (T2s).

7. Refrigerating device according to one of the preceding claims, characterized in that the control circuit (13) is set up to increase the degree of opening of the first expansion valve (17) when the temperature of the first storage chamber (2) is below a setpoint value (T2s), and / or to reduce the degree of opening of the first expansion valve (17) when the temperature (T2) of the first storage chamber (2) is above a setpoint value (T2s).

8. Refrigeration device according to one of the preceding claims, characterized in that the control circuit (13) is set up to select an expansion valve to be adjusted depending on whether the temperature (T4) of the third storage chamber (4) deviates from a target value (T4s) a target temperature (T2s) of the first storage chamber (2) is above or below an ambient temperature (T _env ).

9. Refrigeration device according to one of the preceding claims, characterized in that a third expansion valve, a fourth heat exchanger, a fourth Storage chamber and a fourth expansion valve connected in series and connected in parallel to the first expansion valve (17), the first heat exchanger (5) and the second expansion valve (18).

10. Refrigeration device according to one of the preceding claims, characterized in that at least one of the heat exchangers (5, 6, 7) has a fan (11) for driving the exchange of air between the heat exchanger (5, 6, 7) and the storage chamber (2, 3 , 4) is assigned.

11. Refrigerating device according to claim 10, characterized in that the control circuit (13) is set up to control the speed of at least one fan (11) on the basis of a predetermined temperature difference between the evaporator (5, 6, 7) and the associated storage chamber (2, 3, 4) to regulate.

12. A method for operating a refrigeration device according to claim 1 with the steps:

Increase (S6) the degree of opening of the second expansion valve (18) when (S3) the temperature (T2) of the first storage chamber (2) is above a target value (T2s), and / or decrease (S5) the degree of opening of the second expansion valve (18) ) if the temperature of the first storage chamber (2) is below a setpoint (T2s).

Increase (S9) the speed of the compressor (14) if (S4) the temperature (T3) of the second storage chamber (3) is above a setpoint value (T3s) and / or decrease (S8) the speed if the temperature (T3) the second storage chamber (3) is below a target value (T3s);

Increase (S11) the degree of opening of the first expansion valve (17) when the temperature (T4) of the third storage chamber (4) is above a target value (T4s), and / or decrease (S10) the degree of opening of the first expansion valve (17) when the temperature (T4) of the third storage chamber (4) is below a target value (T4s).

13. Computer program product which comprises instructions which, when executed on a computer, enable it to work as a control circuit in a refrigeration device according to one of claims 1 to 11 or to carry out the method according to claim 12.