WO2015110285A1

WO2015110285A1 - Coolant circuit for a domestic refrigerator, domestic refrigerator with a coolant circuit, and method for operating a coolant circuit of a domestic refrigerator

Info

Publication number: WO2015110285A1
Application number: PCT/EP2015/050156
Authority: WO
Inventors: Christian Mayershofer
Original assignee: BSH Hausgeräte GmbH
Priority date: 2014-01-21
Filing date: 2015-01-07
Publication date: 2015-07-30
Also published as: DE102014200977A1

Abstract

The invention relates to a coolant circuit (14) for a domestic refrigerator (10), comprising: a compressor (16) for compressing a coolant, said compressor comprising a piston (24) which can be moved within a compressor area (20) of a cylinder (22) in order to compress the coolant, wherein the piston (24) can be supported in a contactless manner in the radial direction of the piston relative to the cylinder (22) by means of a gas thrust bearing which can be formed from the coolant; a liquefier (42) for liquefying the compressed coolant; and an evaporator (44) for evaporating the liquefied coolant. The compressor (16) is arranged downstream of the evaporator (44) and upstream of the liquefier (42) in the flow direction (46) of the coolant circuit (14); a blocking valve (48) is arranged in the coolant circuit (14) between the compressor (16) and the liquefier (42), said blocking valve being designed to prevent a volumetric flow rate of the coolant against the flow direction (46) from the liquefier (42) through the compressor (16) to the evaporator (44) when the compressor (16) is deactivated. The invention further relates to a domestic refrigerator (10) with a coolant circuit (14) and to a method for operating a coolant circuit (14) of a domestic refrigerator (10).

Description

COOLING CIRCUIT FOR A BUDGET COOLING DEVICE, HOUSEHOLD COOLING DEVICE WITH A COOLING CIRCUIT UNO METHOD FOR OPERATING A COOLING CIRCUIT OF A HOUSEHOLD COOLING DEVICE

The invention relates to a refrigeration cycle for a domestic refrigeration appliance and a method for operating a refrigeration cycle of a household refrigerating appliance of the type specified in the preambles of the independent claims. Furthermore, the invention relates to a household refrigeration appliance with such a refrigeration cycle. WO 2008 055810 A1 shows a linear compressor for a household appliance, with a movable in the longitudinal direction of a cylinder between an upper and lower dead center piston, the piston outer surface is to form a gas pressure bearing in the radial direction of the cylinder without contact against a corresponding cylinder inner surface storable. The linear compressor shown there can be used in a refrigeration cycle of a household refrigerator.

During a standstill time of such a compressor with a gas bearing, it may be due to the gas storage to an undesirable backflow of a gaseous refrigerant from a high pressure side to a low pressure side of the compressor. The result is that a corresponding pressure difference between the high pressure side and the low pressure side during the downtime of such a compressor can not be maintained, which has a negative effect on the operation of a refrigeration cycle of a domestic refrigerator. Because in a restart of such a compressor, first, the pressure difference between the high pressure side and the low pressure side of the compressor must be rebuilt.

It is the object of the present invention to ensure the maintenance of a pressure difference between a high-pressure side and a low-pressure side of a compressor during the downtime of a compressor of a refrigeration cycle of a household refrigerator. This object is achieved by a refrigeration cycle for a household refrigeration appliance and by a method for operating a refrigeration cycle of a household refrigerating appliance with the features of the independent claims and by a household refrigeration appliance with such a refrigeration cycle. The refrigeration cycle according to the invention for a household refrigerating appliance comprises a compressor for compressing a refrigerant, which comprises a piston movable within a compressor chamber of a cylinder for compressing the refrigerant, wherein the piston can be stored in the radial direction relative to the cylinder without contact by means of a gas pressure bearing which can be formed from the refrigerant. Furthermore, the refrigeration cycle according to the invention comprises a condenser for liquefying the compressed refrigerant and an evaporator for evaporating the liquefied refrigerant, wherein the compressor is arranged in the flow direction of the refrigeration circuit downstream of the evaporator and upstream of the condenser. In order to ensure the maintenance of a pressure difference between a low-pressure and a high-pressure side of the compressor during a standstill of the compressor, it is provided according to the invention that between the compressor and the condenser, a shut-off valve is arranged in the refrigeration cycle, which is designed with a deactivated compressor Volume flow of the refrigerant against the flow direction from the condenser through the compressor to the evaporator to prevent. In this case, the flow direction of the refrigerant within the refrigeration cycle is designated by the flow direction, in which the refrigerant flows through the refrigeration cycle when the compressor is activated.

In other words, it is thus provided according to the invention to provide upstream of the compressor within the refrigeration circuit a shut-off valve, by means of which a return flow of the refrigerant can be suppressed with deactivated compressor according to the prevailing pressure gradient from the condenser through the compressor to the evaporator. This makes it possible, despite the use of a compressor with a gas bearing the pressure difference established during operation of the compressor between a suction and pressure side of the compressor to maintain because a flow through the compressor with the compressor off with the refrigerant by means of the invention arranged in the shut-off valve Refrigeration circuit can be prevented. This contributes to a considerable increase in the efficiency of the refrigeration cycle, because of the shut-off valve, a pressure drop within the refrigeration cycle above the compressor can be prevented while the compressor is deactivated.

In an advantageous embodiment of the invention, it is provided that the shut-off valve is designed as a check valve. For example, the shut-off valve may be formed as a louvered valve, spring valve or the like, which is automatically closed solely by the pressure difference between the condenser and the evaporator. Check valves are usually relatively simple and therefore can be provided inexpensively. In a further advantageous embodiment of the invention, it is provided that the shut-off valve is electromotive or electromagnetically actuated. In other words, it is also possible that the shut-off valve is designed as an active element whose valve position can be influenced, for example, by applying an electrical current. As a result, the switching times of the shut-off valve can be adjusted particularly easily as needed.

In a further advantageous embodiment of the invention, it is provided that a further shut-off valve is arranged downstream of the condenser and upstream of the evaporator, which is designed to prevent a volume flow of the refrigerant in the flow direction from the condenser to the evaporator when the compressor is deactivated. As a result, a pressure drop when the compressor is deactivated within the refrigeration cycle from the condenser to the evaporator is prevented, which also contributes to the increase in efficiency in the operation of the refrigeration cycle. Due to the fact that the pressure from the condenser to the evaporator can not fall when the compressor is deactivated, this pressure difference does not first have to be rebuilt after the compressor has been switched on.

A further advantageous embodiment of the invention provides that the compressor is designed as a linear compressor. Linear compressors are usually reciprocating compressors in which the pistons are driven by linear drives, for example roller screw drives or the like, independently of a crankshaft. Compared with reciprocating compressors with a rotary drive, for example via a connecting rod driven by a rotary motor, linear compressors have the Advantage that the piston stroke can be changed. This makes it possible to adjust the degree of compression of the compressor in a particularly simple way as needed.

In a further advantageous embodiment of the invention, it is provided that the cylinder comprises a socket, within which the piston is arranged. For example, if due to a defect, the gas pressure bearing can not be formed, the piston only comes into contact with the socket, within which it is guided, so that in such a case, only the socket is damaged and it must be replaced.

A further advantageous embodiment of the invention provides that the bushing comprises a plurality of openings through which the refrigerant for supplying the gas pressure bearing in the direction of the piston can be fed. Preferably, these openings are provided evenly distributed on the socket, so that the gas pressure bearing can be constructed very quickly and evenly.

The domestic refrigeration appliance according to the invention comprises the refrigeration cycle according to the invention or an advantageous embodiment of the refrigeration cycle according to the invention.

In the method according to the invention for operating a refrigeration cycle of a household refrigerating appliance, a refrigerant is compressed by means of a compressor, the refrigerant being compressed by means of a piston moved within a compressor chamber of a cylinder, which is mounted without contact relative to the cylinder by means of a gas pressure bearing formed from the refrigerant. The compressed refrigerant is liquefied by means of a downstream of the compressor arranged in the flow direction of the refrigerant circuit and connected to this condenser. The liquefied refrigerant is then vaporized by means of an evaporator arranged downstream of the condenser. The inventive method is characterized in that a downstream downstream of the compressor and upstream of the condenser arranged shut-off valve is closed as soon as the compressor is deactivated, whereby, with the compressor deactivated, a volume flow of the refrigerant from the condenser through the compressor is suppressed to the evaporator against the flow direction. Advantageous embodiments of the refrigeration cycle according to the invention are to be regarded as advantageous embodiments of the method according to the invention.

In an advantageous embodiment of the method according to the invention, it is provided that the shut-off valve is opened with a predetermined time advance before the deactivated compressor for compressing the refrigerant is activated again. Preferably, the time advance before the activation of the compressor is chosen to be so large that the gas pressure bearing between the piston and the cylinder is formed by means of the refrigerant flowing from a high-pressure outlet into the compressor. In other words, the shut-off valve is opened against a prevailing pressure gradient when the compressor is deactivated, so that due to the prevailing pressure gradient between the high-pressure outlet and the low-pressure inlet of the compressor, the refrigerant flows into the compressor and the gas pressure bearing between the piston and the cylinder is formed, even before the Compressor is reactivated. As a result, the piston can already be mounted without contact relative to the cylinder before the compressor is activated. As a result, wear on the piston-cylinder mating can be significantly reduced.

Finally, it is provided according to a further advantageous embodiment of the method according to the invention that another in the flow direction after the condenser and upstream of the evaporator shut-off valve is closed as soon as the compressor is deactivated, whereby the compressor is deactivated, a volume flow of the refrigerant in the flow direction of the condenser Evaporator is suppressed. In other words, it is prevented by the closing of the further shut-off valve that a pressure equalization between the condenser and the evaporator can be performed when the compressor is deactivated, which also contributes to increasing the efficiency of the refrigeration cycle, since this pressure difference does not have to be first rebuilt when switching on the compressor. Further advantages, features and details of the invention will become apparent from the following description of preferred embodiments and from the drawing. The features and feature combinations mentioned above in the description as well as those mentioned below in the description of the figures and / or features and combinations of features shown alone in the figures can be used not only in the particular combination specified, but also in other combinations or in isolation, without departing from the scope of the invention. The drawing shows in:

Fig. 1 is a schematic longitudinal sectional view of a household refrigerator with a compressor;

Fig. 2 is a schematic side sectional view of the compressor; and in

Fig. 3 is a schematic representation of a refrigeration cycle of

Household refrigerating appliance, in which the compressor is arranged.

In the figures, identical or functionally identical elements are provided with the same reference numerals.

A domestic refrigeration appliance 10 is shown in a schematic longitudinal section in FIG. 1. The household refrigerating appliance 10 may be, for example, a refrigerator, a freezer or a refrigerated combined freezer. The domestic refrigeration appliance 10 comprises an interior space 12 which is designed to receive food. This interior space 12 may be a refrigerated compartment, a freezer compartment or a no-frost compartment or at least two of these compartments.

The domestic refrigeration appliance 10 comprises a refrigeration cycle 14, which comprises a compressor 16 designed as a linear compressor. The compressor 16 is preferably arranged in a machine room 18, which is located in the lower and rear area of the domestic refrigerator 10.

2, the compressor 16 is shown in a schematic side sectional view. The compressor 16 comprises a piston 24, which is movable within a compressor chamber 20 of a cylinder 22, for compressing a refrigerant which is not described in greater detail, wherein the piston 24 can be mounted in the radial direction relative to the cylinder 24 without contact by means of a gas pressure bearing which can be formed from the refrigerant. The cylinder 22 includes a socket 26 within which the piston 24 is arranged. The bush 26 has a plurality of openings 28, through which the refrigerant for forming the gas pressure bearing in the direction of the piston 24 can be fed. In addition, the cylinder 22 has a gas bearing supply line 29, through which the refrigerant for forming the gas pressure bearing can be fed to a reservoir 30, from where the refrigerant can be supplied through the openings 28 in the direction of the piston 24. The cylinder 22 is surrounded by a housing 32.

The compressor 16 has an inlet valve 34 for regulating a volume flow of the uncompressed refrigerant from a low-pressure inlet 36 of the compressor 16 arranged in the housing 32 into the compressor chamber 20. Furthermore, the compressor 16 also comprises an outlet valve 38 for regulating a volume flow of the compressed refrigerant from the compressor chamber 20 to a high pressure outlet 40 of the compressor 16 also arranged on the housing 32. FIG. 3 schematically shows the refrigeration cycle 14 of the household refrigerating appliance 10. In addition to the compressor 16, the refrigeration cycle 14 comprises a condenser 42 for liquefying the refrigerant compressed by the compressor 16 and an evaporator 44 for vaporizing the refrigerant liquefied by the condenser 42, the compressor 16 downstream in a flow direction of the refrigeration cycle 14 indicated by the arrow 46 from the evaporator 44 and upstream of the condenser 42 is arranged. With the flow direction 46 that flow direction is designated, in which the refrigerant flows through the refrigeration circuit 14, as long as the compressor 16 is activated and thus compresses the refrigerant and in the flow direction 46 through the refrigerant circuit 14 pumps.

Between the compressor 16 and the condenser 42, a shut-off valve 48 is arranged in the refrigeration circuit 14, which is designed to prevent a volume flow of the refrigerant against the flow direction 46 of the condenser 42 through the compressor 16 to the evaporator 44 with deactivated compressor 16. Because in the refrigeration cycle 14, the condenser 42 forms a high pressure side and the evaporator 44 forms a low pressure side. As soon as the compressor 16 is deactivated, because of the pressure gradient between the condenser 42 and the evaporator 44, the refrigerant would tend to move counter to the flow direction 46 Pressure equalization from the condenser 42 through the compressor 16 to the evaporator 44 to flow.

The check valve 48 may be formed, for example, as a check valve in the form of a louvered valve, spring valve or the like, so that it is automatically closed by the pressure difference between the condenser 42 and the evaporator 44, as soon as the compressor 16 is deactivated. Alternatively, it is also possible that the shut-off valve 48 is formed as an active element, and, for example, by an electric motor or electromagnetically actuated, so that the opening and closing of the shut-off valve 48 is arbitrarily controlled.

Another shut-off valve 50 is arranged in the flow direction 46 after the condenser 42 and before the evaporator 44. In the example shown here, a throttle 52 is still disposed between the condenser 42 and the evaporator 44, which may also be an expansion valve. In the present case, therefore, the further shut-off valve 50 is arranged between the condenser 42 and the throttle 52. The further shut-off valve 50 is designed to prevent a volume flow of the refrigerant in the flow direction 46 from the condenser 42 to the evaporator 44 when the compressor 16 is deactivated. As a result, pressure compensation is prevented when the compressor 16 is switched off between the condenser 42 and the evaporator 44.

Hereinafter, a method for operating the refrigeration cycle 14 will be explained in more detail. When the compressor 16 is activated, the refrigerant is compressed by means of the compressor 16, wherein the refrigerant is compressed by means of the piston 24 moved within the compressor chamber 20 of the cylinder 24, which is mounted relative to the cylinder 22 without contact by means of the formed from the refrigerant gas pressure bearing. The compressed refrigerant flows in the flow direction 46 from the high-pressure outlet 40 in the direction of the condenser 42, wherein the compressed refrigerant is liquefied when flowing through the condenser 42. The liquefied refrigerant then flows in the flow direction 46 through the throttle 52 into the evaporator 44, in which the refrigerant is evaporated. Once the compressor 16 is deactivated, the shut-off valve 48 is closed, whereby a volume flow of the refrigerant is suppressed by the condenser 42 through the compressor 16 to the evaporator 44 against the flow direction 46 when the compressor 16 is deactivated. Simultaneously with the deactivation of the compressor 16, the further shut-off valve 50 is also closed, whereby when the compressor 16 is deactivated, a volume flow of the refrigerant in the flow direction 46 from the condenser 42 through the throttle 52 to the evaporator 44 is prevented. By closing the shut-off valves 48, 50 is thus a pressure equalization between the high pressure side of the refrigeration circuit, in which the condenser 42 is arranged, and the low pressure side, in which the evaporator 44 is arranged, prevented. Thus, even if the deactivated compressor 16 would allow a volume flow of the refrigerant through this, by closing the shut-off valves 48, 50, a volume flow of the refrigerant through the refrigeration circuit 14 is stopped when the compressor 16 is turned off.

Before the deactivated compressor 16 is again activated, at least the shut-off valve 48 is opened with a predetermined time advance. The time advance before activating the compressor 16 is chosen to be so large that the gas pressure bearing between the piston 24 and the cylinder 22 is completely formed by means of the refrigerant flowing from the high pressure port 40 into the compressor 16 before the compressor 16 is restarted. In other words, therefore, by opening the shut-off valve 48, an inflow of the refrigerant from the condenser 42 into the compressor 16, more precisely through its high-pressure outlet 40, allows, so that the gas pressure bearing for non-contact storage of the piston 24 relative to the cylinder 22 is made possible before the Compressor 16 is reactivated. This prevents wear on the piston 24 or on the sleeve 26 when starting the compressor 16, since the gas pressure bearing is fully formed already at the time of activation of the compressor 16, whereby the piston 24 is mounted without contact relative to the sleeve 26. 5 list of reference numerals

10 household refrigerators

12 interior

14 refrigeration cycle

16 compressors

18 engine room

20 compressor room

22 cylinders

24 pistons

26 socket

28 opening

29 gas storage supply line

30 reservoir

32 housing

34 inlet valve

36 low pressure input

38 exhaust valve

40 high pressure outlet

42 liquefier

44 evaporator

46 flow direction

48 shut-off valve

50 shut-off valve

52 throttle

30

Claims

claims

Refrigeration circuit (14) for a household refrigerator (10), with

a compressor (16) for compressing a refrigerant, which comprises a piston (24) movable within a compressor chamber (20) of a cylinder (22) for compressing the refrigerant, the piston (24) in its radial direction relative to the cylinder (22) can be stored without contact by means of a gas pressure bearing which can be formed from the refrigerant;

a condenser (42) for liquefying the compressed refrigerant and an evaporator (44) for evaporating the liquefied refrigerant, wherein the compressor (16) in the flow direction (46) of the refrigeration circuit (14) downstream of the evaporator (44) and upstream of the condenser ( 42) is arranged;

characterized in that

between the compressor (16) and the condenser (42) a shut-off valve (48) in the refrigeration circuit (14) is arranged, which is designed, when the compressor (16) is deactivated, a volume flow of the refrigerant against the

Direction of flow (46) from the condenser (42) through the compressor (16) to the evaporator (44) to prevent.

Refrigeration circuit (14) according to claim 1,

characterized in that

the shut-off valve (48) is designed as a check valve.

Refrigeration circuit (14) according to claim 1,

characterized in that

the shut-off valve (48) can be actuated by an electric motor or electromagnetically.

Refrigeration circuit (14) according to one of the preceding claims,

characterized in that

a further shut-off valve (50) in the flow direction (46) after the condenser (42) and in front of the evaporator (44) is arranged, which is designed to, at deactivated compressor (16) a volume flow of the refrigerant in

Direction of flow (46) from the condenser (42) to the evaporator (44) to prevent.

5. Refrigeration circuit (14) according to one of the preceding claims,

characterized in that

the compressor (16) is designed as a linear compressor.

6. refrigeration circuit (14) according to one of the preceding claims,

characterized in that

the cylinder (22) comprises a bushing (26) within which the piston (24) is arranged.

7. refrigeration circuit (14) according to claim 6,

characterized in that

the bush (26) comprises a plurality of openings (28) through which the refrigerant for forming the gas pressure bearing in the direction of the piston (24) can be fed.

8. domestic refrigeration appliance (10) with a refrigeration circuit (14) according to one of

previous claims.

9. A method for operating a refrigeration cycle (14) of a household refrigerating appliance (10), comprising the steps of:

Compressing a refrigerant by means of a compressor (16), wherein the refrigerant is compressed by means of a piston (24) moving within a compressor chamber (20) of a cylinder (22), which is mounted without contact relative to the cylinder (22) by means of a gas pressure bearing formed from the refrigerant becomes;

Liquefying the compressed refrigerant by means of a in the flow direction (46) of the refrigeration circuit (14) downstream of the compressor (16) arranged and connected thereto condenser (42);

Vaporizing the liquefied refrigerant by means of an evaporator (44) arranged downstream of the condenser (42) in the flow direction (46); characterized in that a shut-off valve (48) arranged downstream of the compressor (16) downstream of the condenser (42) is closed as soon as the compressor (16) is deactivated, whereby with the compressor (16) deactivated a volume flow of the refrigerant from the

Condenser (42) through the compressor (16) to the evaporator (44) against the flow direction (46) is prevented.

Method according to claim 9,

characterized in that

the shut-off valve (48) is opened with a predetermined time delay before the deactivated compressor (16) is reactivated to compress the refrigerant.

Method according to claim 10,

characterized in that

the time advance before activating the compressor (16) is chosen to be so large that the gas pressure bearing between the piston (24) and the cylinder (22) is formed by means of the refrigerant flowing from a high-pressure outlet (40) into the compressor (16).

Method according to one of claims 9 to 11,

characterized in that

another in the flow direction (46) after the condenser (42) and in front of the evaporator (44) arranged shut-off valve (50) is closed as soon as the compressor (16) is deactivated, whereby when the compressor (16) is deactivated, a volume flow of the refrigerant in the flow direction (46) from the condenser (42) to the evaporator (44) is prevented.