DE102014200977A1 - Refrigeration circuit for a household refrigerating appliance, household refrigerating appliance with a refrigeration cycle and method for operating a refrigeration cycle of a household refrigerating appliance - Google Patents

Abstract

The invention relates to a refrigeration circuit (14) for a household refrigerating appliance (10), comprising: a compressor (16) for compressing a refrigerant comprising a piston (24) movable within a compressor chamber (20) of a cylinder (22) for compressing the refrigerant wherein the piston (24) in the radial direction relative to the cylinder (22) can be stored without contact by means of a gas pressure bearing 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; wherein between the compressor (16) and the condenser (42) a shut-off valve (48) in the refrigeration circuit (14) is arranged, which is designed to deactivate the compressor (16) a flow of the refrigerant against the flow direction (46) of the condenser (42) through the compressor (16) to the evaporator (44) to prevent. Furthermore, the invention relates to a domestic refrigeration appliance (10) with a refrigeration cycle (14) and to a method for operating a refrigeration cycle (14) of a domestic refrigeration appliance (10).

Description

The invention relates to a refrigeration cycle for a domestic refrigeration appliance and a method for operating a refrigeration cycle of a domestic 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.

The WO 2008 055810 A1 shows a linear compressor for a household appliance, with a longitudinal direction of a cylinder between an upper and lower dead center movable piston whose 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 domestic 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, as a result 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 disposed shut-off valve is closed as soon as the compressor is deactivated, whereby the compressor is deactivated, a volume flow of the refrigerant from the condenser through the compressor to the evaporator against the Flow direction is prevented. 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, the 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 arranged in the flow direction after the condenser and before the evaporator shut-off valve is closed as soon as the compressor is deactivated, whereby at a deactivated compressor, a flow of the refrigerant in the flow direction of the Condenser is suppressed to the evaporator. 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 rebuilt first 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 the features and feature combinations mentioned below in the description of the figures and / or in the figures alone can be used not only in the respectively specified combination but also in other combinations or in isolation, without the scope of To leave invention.

The drawing shows in:

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

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

3 a schematic representation of a refrigeration cycle of the household refrigerator, in which the compressor is arranged.

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

A household refrigerator 10 is a schematic longitudinal sectional view in 1 shown. In the household refrigerator 10 it may be, for example, a refrigerator, a freezer or a combination refrigerator-freezer. The household refrigerator 10 includes an interior 12 which is trained to take food. This interior 12 may be a refrigerated compartment, a freezer or a no-frost compartment, or at least two of these compartments.

The household refrigerator 10 includes a refrigeration cycle 14 , which is a compressor designed as a linear compressor 16 includes. The compressor 16 is preferably in a machine room 18 Standing in the lower and rear of the household refrigerator 10 is located.

In 2 is the compressor 16 shown in a schematic side sectional view. The compressor 16 includes one within a compressor room 20 a cylinder 22 movable piston 24 for compressing an unspecified refrigerant, wherein the piston 24 in its radial direction relative to the cylinder 24 Can be stored without contact by means of a formable from the refrigerant unspecified gas pressure bearing. The cylinder 22 includes a socket 26 , inside which the piston 24 is arranged. The socket 26 has a plurality of openings 28 on, through which the refrigerant to form the gas pressure bearing in the direction of the piston 24 can be fed. In addition, the cylinder points 22 a gas storage supply line 29 through which the refrigerant for forming the gas pressure bearing a reservoir 30 can be supplied from where the refrigerant through the openings 28 in the direction of the piston 24 can be fed. The cylinder 22 is of a housing 32 surround.

The compressor 16 has an inlet valve 34 for regulating a volume flow of the uncompressed refrigerant from one to the housing 32 arranged low-pressure inlet 36 of the compressor 16 in the compressor room 20 on. Furthermore, the compressor includes 16 another outlet valve 38 for regulating a volume flow of the compressed refrigerant from the compressor room 20 to one also on the housing 32 arranged high-pressure outlet 40 of the compressor 16 ,

In 3 is the refrigeration cycle 14 of the household refrigerator 10 shown schematically. Next to the compressor 16 includes the refrigeration cycle 14 a liquefier 42 for liquefying by means of the compressor 16 compressed refrigerant and an evaporator 44 to evaporate by means of the condenser 42 liquefied refrigerant, the compressor 16 in one with the arrow 46 characterized flow direction of the refrigeration cycle 14 downstream of the evaporator 44 and upstream of the condenser 42 is arranged. With the flow direction 46 is the flow direction designated, in which the refrigerant through the refrigeration cycle 14 flows as long as the compressor 16 is activated and thus compresses the refrigerant and in the flow direction 46 through the refrigeration cycle 14 inflated.

Between the compressor 16 and the liquefier 42 is a shut-off valve 48 in the refrigeration cycle 14 arranged, which is designed with the compressor off 16 a flow of the refrigerant against the flow direction 46 from the liquefier 42 through the compressor 16 to the evaporator 44 to prevent. Because in the refrigeration cycle 14 forms the condenser 42 a high pressure side and the evaporator 44 forms a low pressure side. As soon as the compressor 16 is deactivated, the refrigerant would have due to the Pressure gradient between the condenser 42 and the evaporator 44 namely the tendency, contrary to the direction of flow 46 for pressure equalization of the condenser 42 through the compressor 16 to the evaporator 44 to flow.

The shut-off valve 48 For example, it may be formed as a check valve in the form of a louvered valve, spring valve or the like, so that this alone by the pressure difference between the condenser 42 and the evaporator 44 automatically closed 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, an electric motor or electromagnetically actuated, so that the opening and closing of the shut-off valve 48 is arbitrarily controllable.

Another shut-off valve 50 is in the flow direction 46 after the liquefier 42 and in front of the evaporator 44 arranged. In the example shown here is between the condenser 42 and the evaporator 44 another throttle 52 arranged, which may also be an expansion valve. In the present case, therefore, the other shut-off valve 50 between the liquefier 42 and the throttle 52 arranged. The further shut-off valve 50 is designed with the compressor off 16 a volume flow of the refrigerant in the flow direction 46 from the liquefier 42 to the evaporator 44 to prevent. This will equalize the pressure when the compressor is off 16 between the liquefier 42 and the evaporator 44 prevented.

The following is a method for operating the refrigeration cycle 14 explained in more detail. With compressor activated 16 is the refrigerant by means of the compressor 16 compressed, wherein the refrigerant by means of within the compressor room 20 of the cylinder 22 moving piston 24 is compressed, which is opposite to the cylinder 22 is stored 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 as it flows through the condenser 42 is liquefied. The liquefied refrigerant then flows through in the flow direction 46 through the throttle 52 in the evaporator 44 in which the refrigerant is evaporated. As soon as the compressor 16 is deactivated, the shut-off valve 48 closed, resulting in disabled compressor 16 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.

Simultaneously with the deactivation of the compressor 16 becomes the further shut-off valve 50 also closed, resulting in disabled compressor 16 a volume flow of the refrigerant in the flow direction 46 from the liquefier 42 through the throttle 52 to the evaporator 44 is prevented. By closing the shut-off valves 48 . 50 So is 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. So even if the deactivated compressor 16 would allow a flow of refrigerant through this, is by closing the shut-off valves 48 . 50 a volume flow of the refrigerant through the refrigeration cycle 14 when the compressor is switched off 16 prevented.

Before the deactivated compressor 16 is reactivated again, at least the shut-off valve 48 opened with a predetermined time lead. The time delay before activating the compressor 16 is chosen so large that by means of the high-pressure outlet 40 in the compressor 16 inflowing refrigerant the gas pressure bearing between the piston 24 and the cylinder 22 is fully formed before the compressor 16 is restarted. In other words, so by opening the shut-off valve 48 an inflow of the refrigerant from the condenser 42 in the compressor 16 , more precisely by its high-pressure outlet 40 , allows, so that the gas pressure bearing for non-contact bearing of the piston 24 opposite the cylinder 22 is possible even before the compressor 16 is activated again. This will cause wear on the piston 24 or at the socket 26 when starting the compressor 16 prevents the gas pressure bearing already at the time of activation of the compressor 16 is completely formed, causing the piston 24 contactless with respect to the socket 26 is stored.

LIST OF REFERENCE NUMBERS

10

 Household refrigerator

12

 inner space

14

 Refrigeration circuit

16

 compressor

18

 engine room

20

 compressor room

22

 cylinder

24

 piston

26

 Rifle

28

 opening

29

 Gas bearing supply line

30

 reservoir

32

 casing

34

 intake valve

36

 Low pressure input

38

 outlet valve

40

 High pressure outlet

42

 condenser

44

 Evaporator

46

 flow direction

48

 shut-off valve

50

 shut-off valve

52

 throttle

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been 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.

Cited patent literature

• WO 2008055810 A1 [0002]

Claims (12)

Refrigeration cycle ( 14 ) for a domestic refrigeration appliance ( 10 ), with - a compressor ( 16 ) for compressing a refrigerant, which within a compressor room ( 20 ) of a cylinder ( 22 ) movable piston ( 24 ) for compressing the refrigerant, wherein the piston ( 24 ) in its radial direction relative to the cylinder ( 22 ) Can be stored without contact by means of a formable from the refrigerant gas pressure bearing; A condenser ( 42 ) for liquefying the compressed refrigerant and an evaporator ( 44 ) for vaporizing the liquefied refrigerant, wherein the compressor ( 16 ) in the flow direction ( 46 ) of the refrigeration cycle ( 14 ) downstream of the evaporator ( 44 ) and upstream of the condenser ( 42 ) is arranged; characterized in that between the compressor ( 16 ) and the liquefier ( 42 ) a shut-off valve ( 48 ) in the refrigeration cycle ( 14 ) is arranged, which is designed, with deactivated compressor ( 16 ) a flow of the refrigerant against the flow direction ( 46 ) from the liquefier ( 42 ) through the compressor ( 16 ) to the evaporator ( 44 ) to prevent. Refrigeration cycle ( 14 ) according to claim 1, characterized in that the shut-off valve ( 48 ) is designed as a check valve. Refrigeration cycle ( 14 ) according to claim 1, characterized in that the shut-off valve ( 48 ) is electromotive or electromagnetically actuated. Refrigeration cycle ( 14 ) according to one of the preceding claims, characterized in that a further shut-off valve ( 50 ) in the flow direction ( 46 ) after the liquefier ( 42 ) and in front of the evaporator ( 44 ) is arranged, which is designed, with deactivated compressor ( 16 ) a volume flow of the refrigerant in the flow direction ( 46 ) from the liquefier ( 42 ) to the evaporator ( 44 ) to prevent. Refrigeration cycle ( 14 ) according to one of the preceding claims, characterized in that the compressor ( 16 ) is designed as a linear compressor. Refrigeration cycle ( 14 ) according to one of the preceding claims, characterized in that the cylinder ( 22 ) a socket ( 26 ), within which the piston ( 24 ) is arranged. Refrigeration cycle ( 14 ) according to claim 6, characterized in that the bushing ( 26 ) several openings ( 28 ), through which the refrigerant for forming the gas pressure bearing in the direction of the piston ( 24 ) can be fed. Domestic refrigeration appliance ( 10 ) with a refrigeration cycle ( 14 ) according to any one of the preceding claims. 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 by means of a within a compressor room ( 20 ) of a cylinder ( 22 ) moving piston ( 24 ), which is opposite the cylinder ( 22 ) Is mounted without contact by means of a formed from the refrigerant gas pressure bearing; - liquefying the compressed refrigerant by means of a flow direction ( 46 ) of the refrigeration cycle ( 14 ) downstream of the compressor ( 16 ) and connected to this condenser ( 42 ); Vaporizing the liquefied refrigerant by means of a flow direction ( 46 ) downstream of the condenser ( 42 ) arranged evaporator ( 44 ); characterized in that a flow direction ( 46 ) downstream of the compressor ( 16 ) and upstream of the condenser ( 42 ) arranged shut-off valve ( 48 ) is closed as soon as the compressor ( 16 ) is deactivated, whereby when the compressor is deactivated ( 16 ) 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. A method according to claim 10, characterized in that the time advance before activating the compressor ( 16 ) so large that by means of a high-pressure outlet ( 40 ) in the compressor ( 16 ) inflowing refrigerant the gas pressure bearing between the piston ( 24 ) and the cylinder ( 22 ) is formed. Method according to one of claims 9 to 11, characterized in that another in the flow direction ( 46 ) after the liquefier ( 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 is deactivated ( 16 ) a volume flow of the refrigerant in the flow direction ( 46 ) from the liquefier ( 42 ) to the evaporator ( 44 ) is prevented.

Images