DE102019202649A1 - Refrigeration device - Google Patents

Abstract

In a refrigeration device, in particular a domestic refrigeration device, with a condenser (4), at least one first evaporator (7) cooling a first storage compartment (23), a throttle point (6) that connects an outlet of the condenser (4) with an inlet of the first evaporator (7) connects, a collecting container (8, 30) for liquid refrigerant overflowing from the first evaporator (7), which is connected to an outlet of the first evaporator (7) and is in a warmer environment than the environment of the first evaporator (7) is arranged, a temperature sensor (20) is assigned to the collecting container (8, 30), and the throttle point (6) comprises a controllable expansion valve (14) which is controlled on the basis of the temperature detected by the temperature sensor (20).

Description

The present invention relates to a refrigeration device, in particular a household refrigeration device such as a refrigerator or freezer or a combination device with a plurality of storage compartments kept at different operating temperatures.

In addition to energy efficiency, low or unobtrusive operating noise is an essential quality feature of household refrigerators. A major cause of operating noises is the circulation of the refrigerant in such a device. It is true that the compressor and, if present, the fans of a refrigeration device do not work silently either, but they can be operated in a controlled manner at a constant speed, so that the noise they generate is only slightly perceived due to its uniformity.

For reasons of cost, household refrigeration devices usually use a capillary as a throttle point to relax the refrigerant. The capillary cannot be actively regulated; their mass flow is high as long as liquid refrigerant with high density is present at the inlet of the capillary. If this has flowed off via the capillary, refrigerant vapor penetrates into the capillary. Due to the low density of the steam, this leads to a reduction in the mass flow, so that the refrigerant condenses in front of the capillary; on the other hand, the steam flows through the capillary at a higher speed than the liquid refrigerant, and the resulting fluctuations in speed lead to clearly perceptible fluctuations in the operating noise .

In commercial refrigeration systems, thermostatic expansion valves are used which allow active control of the mass flow. These are usually arranged downstream of a collector which is large enough to enable a clean separation of vapor and liquid and to supply the expansion valve exclusively with liquid refrigerant, as long as the collector contains a sufficient amount thereof. To ensure this, the mass flow through the expansion valve is controlled with the aid of a pressure sensor. By keeping gaseous refrigerant away from the expansion valve, losses in efficiency can be avoided that would result if, on the one hand, steam is compressed using energy and, on the other hand, is allowed to expand again in the expansion valve without the energy used being able to be used.

Attaching a pressure sensor is complex, since the pressure sensor must communicate directly with the refrigerant to be measured and must be suitably sealed. This, the cost of the known controllable expansion valves and the fact that hardly usable expansion valves were available for the small mass flows to be controlled in household refrigeration devices have long prevented their use in household refrigeration devices. Household refrigerators that use controllable expansion valves have only been developed for a few years.

Out DE 10 2015 215 491 A1 a household refrigerator is known in which a controllable expansion valve is connected in series between two evaporators in order to be able to vary a pressure difference between the evaporators and in this way to be able to variably set the operating temperatures of the storage compartments cooled by the evaporators. Since refrigerant that has evaporated in the upstream evaporator can only flow out via the expansion valve, liquid and vaporous refrigerant must alternate in the expansion valve, and quiet operation is not possible.

The object of the present invention is to create a highly efficient and yet inexpensive to manufacture refrigeration device, in particular a domestic refrigeration device.

The object is achieved in that, in a refrigeration device, in particular a household refrigerator, with a condenser, at least one first evaporator cooling a first storage compartment, a throttle point that connects an outlet of the condenser to an inlet of the first evaporator, a collecting container for overflow from the first evaporator liquid refrigerant, which is connected to an outlet of the first evaporator and is arranged in a warmer environment than the environment of the first evaporator, a temperature sensor is assigned to the collecting container and the throttle point comprises a controllable expansion valve which is controlled based on the temperature detected by the temperature sensor .

The collecting container creates a buffer, the degree of filling of which with liquid refrigerant can be estimated based on the measured temperature. By using this temperature to control the mass flow through the expansion valve, it can be ensured that when the compressor is running, there is always enough liquid refrigerant available upstream of the throttle point to be able to keep vapor away from the expansion valve. At the same time, it is possible to completely flood the first evaporator with liquid refrigerant and thus provide a high cooling capacity, which is required, for example, for the rapid cooling of freshly loaded refrigerated goods. By placing the collecting container in a warmer environment than the first evaporator, it can be ensured that the liquid refrigerant flowing from the first evaporator into the Collection container overflows, does not accumulate there, but evaporates immediately.

In order to ensure different ambient temperatures for the first evaporator and the collecting container, the collecting container can be separated from the first storage compartment by a thermal insulation layer.

In order to enable precise control of small mass flows through the expansion valve, it can be helpful to connect the expansion valve in series with a capillary, so that part of the pressure difference between the condenser and the first evaporator falls on the capillary and the rest on the expansion valve.

In order to avoid that already in the capillary shortly before its downstream end evaporation begins and that noises are produced by the fact that vapor and liquid refrigerant alternate at the exit of the capillary, the capillary should be arranged upstream of the expansion valve and the pressure difference falling across it should be small enough, to prevent refrigerant from evaporating before it reaches the expansion valve.

Typically, the capillary should be sized to have a smaller pressure drop than the controllable expansion valve.

A steam separator can be connected upstream of the controllable expansion valve (and possibly the capillary).

The vapor separator not only separates refrigerant vapor from the liquid refrigerant, but also non-condensable residual gas that remained in its cavities when the refrigerant circuit was assembled. By making the vapor separator spacious enough, it is also possible to neutralize a larger amount of residual gas than is currently usually left behind when the refrigerant circuit is evacuated. The additional expense associated with installing the vapor separator can therefore be at least partially offset by shortening the evacuation.

In the simplest case, the vapor separator is an expansion or chamber, the cross-section of which is large enough that the flow of the refrigerant can slow down enough to allow vapor bubbles to rise from the liquid refrigerant. Such a separation chamber preferably has a maximum horizontal cross-sectional dimension of at least 8 mm or a maximum horizontal cross-sectional area of at least 0.5 cm ² between an upper inlet and a lower outlet. The separation chamber can contain built-in components that impede the formation of vortices in the liquid refrigerant, such as partition walls or a bed of particles. The effect of the vapor separator can also be based on a large volume and a correspondingly long retention time of the refrigerant, which gives the phases time to separate from one another. This capacity should preferably be sufficient to accommodate at least half of the total refrigerant present in the refrigeration device in the liquid state. In order to be able to guarantee bubble-free drainage of the refrigerant even with increased compressor performance, for example during rapid cooling operation, the capacity of the vapor separator can be dimensioned for up to 90% of the amount of refrigerant in the liquid state. Vapor separator and first evaporator can be dimensioned together in order to offer space for the entire refrigerant in the liquid state.

The outlet of the condenser should be connected to the throttle point without the interposition of a further evaporator.

According to a particularly preferred embodiment, the collecting container is a second evaporator. This can be of the same design as the first evaporator, e.g. a Rollbond, ToS or lamellar evaporator.

The second evaporator is expediently used to cool a second storage compartment.

Since the second evaporator only receives liquid refrigerant when the first overflows, the operating temperature of the second storage compartment should be higher than that of the first.

The evaporators can be arranged in direct thermal contact with the storage compartments they are cooling, i. the above-mentioned surroundings of the first evaporator and the collecting container or second evaporator can be these storage compartments themselves.

A compartment temperature sensor of the second storage compartment can then serve as the above-mentioned temperature sensor controlling the expansion valve. This avoids the costs associated with adding an additional sensor.

In order not to unnecessarily restrict the space available for accommodating the evaporator or evaporators, the controllable expansion valve can be accommodated in a partition between the storage compartments. In particular, a rear wall of the storage compartments remains completely available in order to attach one of the evaporators to it.

The above-mentioned thermal insulation layer can be part of the partition wall. In this case, since the expansion valve cools down during operation a recess in the thermal insulation layer, which accommodates the expansion valve, should be open at least towards the colder, ie generally towards the first storage compartment.

In order to reliably prevent the collecting container or second evaporator from overflowing, its capacity should be dimensioned to provide space for at least half of the refrigerant in the liquid state. The space does not need to be sufficient for the entire refrigerant, since liquid refrigerant generally only reaches the collecting container when the first evaporator is full.

A control circuit should be set up in order to set a high mass flow rate through the controllable expansion valve at a high sensed temperature and a low mass flow rate at a low sensed temperature.

• 1 ein Blockdiagramm eines Kältegeräts gemäß einer ersten Ausgestaltung;
• 2 einen schematischen Schnitt durch das Kältegerät aus 1;
• 3 ein Blockdiagramm eines Kältegeräts gemäß einer zweiten Ausgestaltung der Erfindung; und
• 4 einen schematischen Schnitt durch das Kältegerät aus 3.

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

• 1 a block diagram of a refrigeration device according to a first embodiment;
• 2 a schematic section through the refrigerator 1 ;
• 3 a block diagram of a refrigeration device according to a second embodiment of the invention; and
• 4th a schematic section through the refrigerator 3 .

1 illustrates the principle of the invention on the basis of a block diagram which essentially shows components of a refrigerant circuit of a domestic refrigeration appliance. The refrigerant circuit comprises a compressor in a manner known per se 1 , from its pressure connection 2 a pressure line 3 a condenser 4th and a collector 5 or dryer to a throttle point 6th extends. In one to the throttle point 6th The low-pressure part of the refrigerant circuit is followed by an evaporator 7th and an evaporator 8th each other, one from the evaporator 8th outgoing suction pipe 9 leads the refrigerant back to a suction connection 10 of the compressor 1 .

At the collector 5 is the pressure line 3 locally to a chamber that acts as a vapor separator 11 with an inlet 12 at the top and one outlet 13 widened at the lower end. About the inlet 12 a mixture of liquid refrigerant and vapor comes out of the condenser 4th in the collector 5 . Because the free cross section of the collector 5 is greater than that of the pressure line 3 upstream and downstream, the flow velocity of the refrigerant in the receiver is reduced, and both phases of the refrigerant have the opportunity to separate from one another. So that this can take place without being hindered by capillary effects, the free cross section of the collector should at least locally 5 reach an area of at least 0.5 cm ² or the diameter a value of at least 8 mm. A sufficient retention time of the refrigerant for the phase separation is achieved by a large volume of the chamber; this is preferably dimensioned in order to offer at least half of the total refrigerant present in the device in the liquid state, ie with a refrigerant charge of 50 or 100 g and a density of 0.5 g / cm ³ , the capacity of the chamber should be at least 50 or 100 cm ³ . To prevent the refrigerant from flowing out through the outlet 13 the liquid refrigerant in the collector starts to swirl, causing vapor bubbles to reach the outlet 13 In addition, a bed of granules, in particular of a dryer material that binds residual water in the refrigerant, can arrive in an area of the collector near the outlet 5 be housed.

The throttle point 6th comprises at least one controllable expansion valve 14th . In the in 1 case shown is between the collector 5 and the expansion valve 14th also a capillary 15th intended. The capillary 15th is sized to cover only the minor part of the pressure drop between the condenser 4th and the evaporator 7th to generate, the greater part is created at the controllable expansion valve 14th . In particular, the nitrogen flow through the capillary can be 500-800 l / h with a pressure drop of 6 bar. The series connection with the capillary 15th allows the expansion valve 14th to precisely control smaller mass flows at a given pressure difference than if the expansion valve were exposed to the pressure of the refrigerant alone. Since the capillary 15th upstream of the expansion valve 14th is arranged, the pressure is in the capillary 15th along their entire length high enough to prevent refrigerant from evaporating in the capillary 15th to prevent. Since the capillary is not cooled by internal evaporation, residual heat of the liquid refrigerant can be stored in an internal heat exchanger 16 in which the capillary 15th in close contact with the suction tube 9 runs efficiently to the compressor in the latter 1 returning steam are transferred.

The evaporator 8th is to the evaporator 7th connected in such a way that liquid refrigerant only then enters the evaporator 8th when the evaporator 7th is full. For this purpose, for example, the evaporator 7th with a refrigerant pipe 17th be equipped by an inlet 18th to an outlet 19th of the evaporator 7th continuously increases so that in the evaporator 7th resulting steam in the direction of the outlet 19th flows away, but liquid refrigerant on steam rising past towards the inlet 18th can flow.

A temperature sensor 20th can on the evaporator 8th to be appropriate; it is preferably not in direct contact with the evaporator 8th in one of this refrigerated storage compartment 21st (see 2 ), typically attached to a normal cooling compartment of the refrigeration device to keep the temperature of the storage compartment 21st capture. This shows the amount of liquid refrigerant in the evaporator with a delay and averaged over time 8th got.

A control circuit 22nd is with the temperature sensor 20th and the expansion valve 14th connected to the latter based on readings from the temperature sensor 20th to control. You can also use the compressor 1 be connected to its speed based on these measured values and possibly one in one of the evaporator 7th refrigerated storage compartment 23 (see 2 ) to control measured temperature.

Exceeds when the compressor is running 1 from the temperature sensor 20th sensed temperature has a setpoint, so the expansion valve 14th further open. This happens gradually, ie as long as the setpoint is exceeded, the control circuit increases 22nd the degree of opening of the expansion valve 14th continuously or in regular small steps to ensure that increasing the degree of opening does not temporarily dry out the collector 5 and for the entry of steam into the throttle point 6th leads. The likelihood of this happening is further reduced by the large volume of the collector 5 and the fact that if the setpoint is exceeded, it can be expected that the evaporator 8th Contains little or no liquid refrigerant and accordingly a lot in the collector 5 must be stocked. The increasing supply of liquid refrigerant to the evaporator due to the increase in the degree of opening 7th finally lets this overflow, and into the evaporator 8th penetrating refrigerant leads to a decrease in the temperature from the temperature sensor 20th detected temperature, so that the setpoint is reached or undercut and the control circuit 22nd the degree of opening of the expansion valve 14th no longer increased.

It is reversed as long as the compressor is running 1 from the temperature sensor 20th detected temperature is below a second setpoint, which can be identical to or lower than the above-mentioned setpoint, the degree of opening of the expansion valve 14th gradually decreased. This reduces the amount of liquid refrigerant that reaches the evaporator 8th and that from the temperature sensor 20th recorded temperature of the storage compartment 21st gradually increases. The one on the vaporizer 7th The available cooling capacity does not change as long as there is still liquid refrigerant up to the evaporator 8th got. Only when this no longer happens and the evaporator 7th is only incompletely filled with liquid refrigerant, its cooling capacity also decreases.

In order to adapt the latter to the respective requirements, it can be provided that the control circuit 22nd also the speed of the evaporator 1 based on the cooling needs of the storage compartment 23 controls. If the measured temperature exceeds a setpoint in the latter, the speed of the compressor becomes 1 gradually booted up. This leads, if not at the same time, to the degree of opening of the expansion valve 14th is changed, to an increased evaporation in the evaporator 8th and a corresponding increase in the amount of liquid refrigerant in the receiver 5 . The increased evaporation leaves the temperature in the storage compartment 23 decrease, which, according to the principles explained in the previous paragraph, leads to the opening degree of the expansion valve 14th is turned down, less liquid refrigerant enters the evaporator 8th achieved and the additional cooling capacity is essentially due to the evaporator 7th stays focused. Conversely, the speed can be reduced if the target value is not reached.

2 shows a schematic cross section through a body 24 of the refrigerator the 1 . The colder storage compartment 23 is arranged under the warmer 21 and separated from the latter by a partition 25th Cut. Like the rest of the body 24 also is the partition 25th as a hollow body with outer walls 26th formed, the interior of which with an insulating material 27 is foamed. The suction pipe 9 runs in a rear wall of the body 24 on both storage bins 23 , 21st along downwards; the capillary runs along part of its length 15th inside or in contact with its outer wall, around the internal heat exchanger 16 to build.

A recess 28 in the layer of insulation material 27 is provided to the expansion valve 14th record. Since the latter cools down during operation, the recess 28 to the storage compartment 23 open to allow heat to flow from there to the expansion valve 14th to enable. The recess can be through a little heat-insulating cover 29 be closed, which can be removed to allow repairs to the expansion valve 14th to enable.

3 shows a second embodiment of the refrigeration device in a to 1 analog representation. Components of the refrigerant circuit that are the same as those already described above are given the same reference numerals and are not described again. The second evaporator 8th is here through a collecting container 30th which does not necessarily cool a storage compartment. Instead, the collection container 30th in an evaporator chamber 31 of a no-frost refrigeration device based on the Direction of circulation between the evaporator chamber 31 and storage compartment 21st or 23 circulating air flow upstream of the evaporator 7th be arranged, as exemplified in 4th shown.

The 4th shows a section through an intermediate wall 32 of a no-frost refrigeration device. The evaporator chamber 31 is from the cold storage compartment below 23 through a thin partition 33 and from the warmer storage compartment above 21st by one with insulating material 27 filled wall separated. A fan 34 is in a known manner downstream of the evaporator designed as a lamellar evaporator 7th arranged to air out one of the compartments 21st , 23 each via an inlet 35 suck in. Which compartment the air is sucked in from is determined by the position of a flap 36 set. No matter in which position the flap is 36 the air that is drawn in is upstream of the evaporator 7th always warmer than downstream. By the collection container 30th in the evaporation chamber 31 upstream of the evaporator 7th mounted, it is in a warmer environment than the latter, and refrigerant that is from the evaporator 7th into the collecting container 30th overflows, can still evaporate in this. By using the common capacity of evaporator 7th and collecting container 30th is sufficiently dimensioned to absorb all of the refrigerant present in the refrigerant circuit in the liquid state, the collecting container may overflow 30th into the suction pipe 9 be excluded.

List of reference symbols

1

compressor

2

Pressure connection

3

Pressure line

4th

Condenser

5

Collector

6th

Throttling point

7th

Evaporator

8th

Evaporator

9

Suction pipe

10

Suction connection

11

chamber

12

inlet

13

Outlet

14th

Expansion valve

15th

capillary

16

Heat exchanger

17th

Refrigerant pipe

18th

inlet

19th

Outlet

20th

Temperature sensor

21st

Storage compartment

22nd

Control circuit

23

Storage compartment

24

Body

25th

Partition

26th

Outer wall

27

Insulation material

28

Recess

29

cover

30th

Collecting container

31

Evaporation chamber

32

Partition

33

partition wall

34

fan

35

inlet

36

flap

QUOTES INCLUDED IN THE DESCRIPTION

This list of the documents listed by the applicant was generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Patent literature cited

• DE 102015215491 A1 [0006]

Claims (15)

Refrigeration device, in particular household refrigeration device, with a condenser (4), at least one first evaporator (7) cooling a first storage compartment (23), a throttle point (6) which connects an outlet of the condenser (4) to an inlet of the first evaporator (7) connects, a collecting container (8, 30) for liquid refrigerant overflowing from the first evaporator (7), which is connected to an outlet of the first evaporator (7) and is arranged in a warmer environment than the environment of the first evaporator (7), characterized in that a temperature sensor (20) is assigned to the collecting container (8, 30) and the throttle point (6) comprises a controllable expansion valve (14) which is controlled using the temperature detected by the temperature sensor (20). Appliance after Claim 1 , characterized in that the collecting container (8) is separated from the first storage compartment (23) by a layer of insulating material (27). Appliance after Claim 1 or 2 , characterized in that a capillary (15) is connected upstream of the controllable expansion valve (14). Appliance after Claim 3 , characterized in that the capillary (15) is sized to have a smaller pressure drop than the controllable expansion valve (14). Refrigerating device according to one of the preceding claims, characterized in that a vapor separator (5) is connected upstream of the controllable expansion valve (14). Appliance after Claim 5 , characterized in that the vapor separator (5) has a separation chamber (11) with an upper inlet (12), a lower outlet (13) and a horizontal cross-sectional dimension which at least locally exceeds 8 mm between inlet and outlet (12, 13), and / or a horizontal cross-sectional area which between inlet and outlet (12, 13) at least locally exceeds 0.5 cm ² , and / or a capacity that is sufficient to accommodate at least half, preferably 90%, of the refrigerant in the liquid state has to offer. Refrigerating device according to one of the preceding claims, characterized in that the outlet of the condenser (4) is connected to the throttle point (6) without the interposition of a further evaporator. Refrigerating device according to one of the preceding claims, characterized in that the collecting container (8) is a second evaporator (8). Appliance after Claim 8 , characterized by a second storage compartment (21) cooled by the second evaporator (8). Appliance after Claim 9 , characterized in that the operating temperature of the second storage compartment is higher (21) than that of the first storage compartment (23). Appliance after Claim 9 or 10 , characterized in that the temperature sensor (20) is a compartment temperature sensor of the second storage compartment (21). Appliance after Claim 9 , 10 or 11 , characterized in that the controllable expansion valve (14) is accommodated in an intermediate wall (25) between the storage compartments (21, 23). Appliance after Claim 12 , characterized in that the partition (25) contains a thermal insulation layer (27) and the expansion valve (14) is accommodated in a recess (28) in the thermal insulation layer (27) which is open to the first storage compartment (23). Refrigerating device according to one of the preceding claims, characterized in that the capacity of the collecting container (8, 30) is dimensioned to provide space for at least half of the refrigerant in the liquid state. Refrigerating device according to one of the preceding claims, characterized in that a control circuit (22) is set up to set a high mass flow rate through the controllable expansion valve (14) at a high sensed temperature and a low mass flow rate at a low sensed temperature.

Images