Patent Application
20170010025
The invention relates to a compressor for a refrigeration circuit of a domestic refrigerator and a method for operating a compressor of a domestic refrigerator of the type specified in the preamble of the independent claims. Furthermore, the invention relates to a domestic refrigerator having a compressor of this type.
WO 2008 055810 A1 shows a linear compressor for a domestic appliance, having a piston which can move between an upper and lower dead center position in the longitudinal direction of a cylinder, the outer surface of the piston of which can be supported in a contactless manner with respect to a corresponding inner surface of the cylinder by forming a gas pressure bearing in the radial direction of the cylinder. The linear compressor shown there can be used in a refrigeration circuit of a domestic refrigerator.
During a downtime of a compressor of this type with a gas storage, said gas storage may result in an undesirable backflow of gaseous refrigerant from a high pressure outlet to a low pressure inlet of the compressor. The result is that a corresponding pressure difference between the high pressure outlet and the low pressure inlet during the downtime of a compressor of this type cannot be maintained, which has a negative effect on the operation of a refrigeration circuit of a domestic refrigerator. When a compressor of this type is restarted, the pressure difference between the high pressure outlet and the low pressure inlet of the compressor must first be re-established.
It is therefore the object of the present invention to be able to maintain a pressure difference between a low pressure inlet and a high pressure outlet of a compressor even during the downtime of the compressor.
This object is achieved by a compressor for a refrigeration circuit of a domestic refrigerator and by a method for operating a compressor of a refrigeration circuit of a domestic refrigerator with the features of the independent claims and furthermore by a domestic refrigerator with a compressor of this type.
The inventive compressor for a refrigeration circuit of a domestic refrigerator comprises a piston which can be moved within a compression chamber of a cylinder in order to compress a refrigerant, wherein in its radial direction relative to the cylinder the piston can be supported in a contactless manner by means of a gas pressure bearing which can be formed from the refrigerant. Moreover, the compressor comprises an inlet valve for regulating a volume flow of uncompressed refrigerant from a low pressure inlet of the compressor into the compression chamber. The compressor also comprises an outlet valve for regulating a volume flow of compressed refrigerant from the compression chamber to a high pressure outlet of the compressor. In order to be able to maintain a pressure difference between the low pressure inlet and the high pressure outlet of the compressor which was established during operation of the compressor even during the downtime of the compressor, provision is inventively made for the compressor to comprise a stop valve arranged between the low pressure inlet and the high pressure inlet, which is designed to prevent a backflow of refrigerant from the high pressure outlet to the low pressure inlet when the compressor is deactivated.
Provision is therefore made in accordance with the invention, in addition to the inlet valve and the outlet valve, which serve to regulate the volume flows of refrigerant through the compressor, to provide a further stop valve within the compressor between the low pressure inlet and the high pressure outlet, by means of which it is possible to prevent refrigerant from flowing through the compressor when the compressor is deactivated. During operation of the compressor, a pressure difference is established between the low pressure inlet and the high pressure outlet, which, during deactivation of the compressor by a backflow of refrigerant through the compressor would result in an undesirable pressure compensation. The inventively provided stop valve now enables this undesirable pressure compensation between the low pressure inlet and the high pressure outlet of the compressor to be prevented by the stop valve being closed once the compressor is deactivated. Even during the downtime of the compressor the inventive solution enables a previously established pressure difference between the low pressure inlet and the high pressure outlet of the compressor to be maintained, which allows a significant increase in efficiency of a refrigeration circuit of a domestic refrigerator to be achieved, in which the inventive compressor is used. When the compressor is restarted, it is namely no longer necessary by means of the inventive solution to firstly establish a pressure difference between the low pressure inlet and the high pressure inlet, since the pressure difference established previously during operation of the compressor by the closable stop valve can also be reliably maintained during the downtime of the compressor.
Provision is made in an advantageous embodiment for the stop valve to be arranged in a gas bearing supply pipe of the compressor, through which the refrigerant can be fed in order to form the gas pressure bearing. In other words the stop valve can be arranged directly in the gas bearing supply pipe of the compressor which serves as a pressure pipe, as a result of which when the compressor is disconnected a pressure compensation can be prevented by a backflow of refrigerant through the gas bearing supply pipe.
Provision is made in a further advantageous embodiment of the invention for the stop valve to be arranged in a refrigerant pipe of the compressor, through which refrigerant pipe the compressed refrigerant flows in the direction of the high pressure outlet when the compressor is activated. The accessibility of a refrigerant pipe of this type may be better in some instances than with the gas bearing supply pipe, so that a potentially defective stop valve can be exchanged particularly easily. With the arrangement of the stop valve in the refrigerant pipe, which leads to the high pressure outlet of the compressor, an undesirable pressure compensation between the high pressure outlet and the low pressure inlet of the compressor can likewise be effectively prevented when the compressor is deactivated.
According to a further advantageous embodiment of the invention, provision is made for the stop valve to be embodied as a non-return valve. For instance, the stop valve can be embodied as a lamellar valve, spring valve or suchlike, which can be actuated solely by the pressure difference between the low pressure inlet and the high pressure outlet of the compressor. A stop valve of this type is typically of a relatively simple design and can therefore be manufactured and provided in a particularly cost-effective manner.
Provision is made in a further advantageous embodiment of the invention for the stop valve to be actuateable in an electromotive or electromagnetic manner In other words, provision can be made for the stop valve to be an active element, with which the valve position can be influenced by applying an electrical current for instance. The advantage of an embodiment of this type is that the stop valve can be actively actuated, as a result of which its actuation can be freely selected essentially independently of the pressure ratios prevailing within the compressor.
A further advantageous embodiment of the invention provides that the compressor is embodied as a linear compressor. Linear compressors are typically piston compressors, in which the pistons are driven by linear drives, for instance roller thread gears, independently of a crankshaft. Compared with conventional piston compressors with a rotary drive, for instance by way of a connecting rod driven by a rotation motor, linear compressors have the advantage that the piston stroke can be changed. This enables the compression ratio within the compressor to be adjusted particularly easily to suit requirements.
Provision is made in a further advantageous embodiment of the invention for the cylinder to comprise a socket, within which the piston is arranged. If the gas pressure bearing is not able to be formed on account of a defect for instance, the piston only achieves contact with the socket, within which it is guided, so that in a case of this type only the socket is damaged and has to be replaced.
A further advantageous embodiment of the invention provides that the socket comprises a number of openings, through which the refrigerant can be supplied in the direction of the piston in order to form the gas pressure bearing. These openings are preferably provided evenly distributed on the socket, so that the gas pressure bearing can be set up particularly quickly and evenly.
The domestic refrigerator according to the invention comprises the inventive compressor or an advantageous embodiment of the inventive compressor.
According to an advantageous embodiment of the domestic refrigerator, provision is made for the compressor to be arranged downstream of an evaporator and upstream of a condenser in the flow direction of a refrigeration circuit of the domestic refrigerator, wherein a further stop valve is arranged downstream of the condenser and upstream of the evaporator in the flow direction. Here the flow direction is understood to mean the flow direction of the refrigerant within the refrigeration circuit, in which the refrigerant flows through the refrigeration circuit when the compressor is activated. As a result of a further stop valve being arranged downstream of the condenser and upstream of the evaporator, an undesirable pressure compensation between the condenser and the evaporator can be prevented when the compressor is deactivated, since the condenser represents a high-pressure side and the evaporator a low-pressure side of the refrigeration circuit. This likewise contributes to increased efficiency of the refrigeration circuit of the domestic refrigerator, because a pressure compensation between the condenser and the evaporator can be prevented by closing the further stop valve.
With the inventive method for operating a compressor of a refrigeration circuit of a domestic refrigerator, a refrigerant is compressed by means of a piston that can be moved within a compression chamber of a cylinder, which, in its radial direction with respect to the cylinder, is supported in a contactless manner by means of a gas pressure bearing formed from the refrigerant. Here an inlet valve of the compressor is actuated in order to regulate a volume flow of uncompressed refrigerant from a low pressure inlet of the compressor into the compression chamber. Furthermore, an outlet valve of the compressor is actuated in order to regulate a volume flow of compressed refrigerant from the compression chamber to a high pressure outlet of the compressor. The inventive method is characterized here in that a stop valve arranged between the low pressure inlet and the high pressure outlet is closed as soon as the compressor is deactivated, wherein a backflow of refrigerant from the high pressure outlet to the low pressure inlet is prevented when the compressor is deactivated. Advantageous embodiments of the inventive compressor are to be considered here as advantageous embodiments of the inventive method for operating a compressor of this type.
Provision is made in a further advantageous embodiment of the method for the stop valve to be opened with a predetermined timeline before the deactivated compressor is activated again in order to compress the refrigerant. The timeline before activating the compressor is preferably selected to be so great that the gas pressure bearing between the piston and the cylinder is fully formed by means of the refrigerant flowing into the compressor from the high pressure outlet. In other words, the stop valve is opened with respect to a prevailing drop in pressure when the compressor is deactivated so that on account of the prevailing drop in pressure between the high pressure outlet and the low pressure inlet of the compressor, the refrigerant flows into the compressor and the gas pressure bearing is formed between the piston and the cylinder, even before the compressor is activated again. As a result, the piston can already be supported in a contactless manner in respect of the cylinder before the compressor is activated. As a result, the wear on the piston-cylinder pairing can be significantly reduced.
Further advantages, features and details of the invention result from the description of preferred exemplary embodiments which follows and with the aid of the drawing. The features and feature combinations mentioned above in the description and the features and feature combinations mentioned below in the description of the figures and/or simply shown in the figures can be used not only in the combination specified in each instance but also in other combinations or alone without departing from the scope of the invention.
The drawings show in:
Similar or functionally similar elements are provided with the same reference characters in the figures.
A domestic refrigerator 10 is shown in
The domestic refrigerator 10 comprises a refrigeration circuit 14, which has a compressor 16 embodied as a linear compressor. The compressor 16 is preferably arranged in a machine space 18, which is disposed in the lower and rear region of the domestic refrigerator 10.
The compressor 16 is therefore arranged downstream of the evaporator 24 and upstream of the condenser 20 in the flow direction 30 of the refrigeration circuit 14, wherein the further stop valve 28 is arranged downstream of the condenser and upstream of the evaporator 24 in the flow direction 30, in the present case still upstream of the throttle 22.
Moreover, the compressor 16 comprises an inlet valve 42 which serves to regulate a volume flow of uncompressed refrigerant from a low pressure inlet 44 of the compressor 16 into the compression chamber 32. The low pressure inlet 44 is arranged on a housing 35 of the compressor 16 and is connected within the refrigeration circuit 14 to the evaporator 24, so that when the compressor 16 is activated, the refrigerant is fed from the evaporator 24 via the low pressure inlet 44 to the compressor 16.
The compressor 16 further comprises an outlet valve 46 for regulating a volume flow of compressed refrigerant from the compression chamber 32 to a high pressure outlet 48 of the compressor 16, which is likewise arranged on the housing 35. The high pressure outlet 48 is connected within the refrigeration circuit 14 to the condenser 20. The compressed refrigerant is therefore routed via the high pressure outlet 48 to the condenser 20.
The compressor 16 comprises a stop valve 50 arranged between the low pressure inlet 44 and the high pressure outlet 48, which is designed to prevent a backflow of refrigerant from the high pressure outlet 48 to the low pressure inlet 44 when the compressor 16 is deactivated. In other words, the stop valve 50 can be closed when the compressor 16 is deactivated, so that a pressure difference established between the high pressure outlet 48 and the low pressure inlet 44 during operation of the compressor 16 can be maintained.
In this case the stop valve 50 is arranged in a gas bearing supply pipe 52 of the compressor 16, through which the refrigerant for forming the gas pressure bearing can be fed. The gas bearing supply pipe 52 leads from a high-pressure side of the compressor 16 into a reservoir 41, from where the refrigerant can be fed through the openings 40 of the socket 38 in the direction of the piston 36, in order to form the gas pressure bearing between the piston 36 and the socket 38.
The stop valve 50 can be embodied as a simple non-return valve, for instance as a lamellar valve, spring valve or suchlike. In this case, the stop valve 50 is independently closed by a pressure difference between the high pressure outlet 48 and the low pressure inlet 44 of the compressor 16. It is alternatively also possible for the stop valve 50 to be embodied as an active element and to be actuateable in an electromotive or electromagnetic manner for instance.
A method for operating the compressor 16 is explained below. When the compressor 16 is activated, the refrigerant is compressed by means of the piston 36 moved within the compression chamber 32 within the cylinder 34, wherein, in its radial direction with respect to the cylinder 34, the piston 36 is supported in a contactless manner by means of the gas pressure bearing formed from the refrigerant. In this way refrigerant is continuously conveyed into the gas reservoir 41 via the gas bearing supply pipe 52 and fed through the openings 40 in the direction of the piston 36, as a result of which the gas pressure bearing, which is formed from the refrigerant, is supplied with an adequate pressure.
Provided the compressor 16 is in operation, the inlet valve 42 and the outlet valve 46 are actuated cyclically and alternately, in order to regulate the volume flow of refrigerant from the low pressure inlet 44 through the compression chamber 32 via the high pressure outlet 48.
As soon as the compressor 16 is deactivated, the stop valve 50 arranged between the low pressure inlet 44 and the high pressure outlet 48 is closed, as a result of which a backflow of refrigerant from the high pressure outlet 48 to the low pressure inlet 44 is prevented when the compressor 16 is deactivated. At the same time the further stop valve 28, which, as shown in
The stop valve 50 arranged within the compressor 16 is opened with a predetermined timeline, before the deactivated compressor 16 is activated again in order to compress the refrigerant. Here the timeline before activating the compressor 16 is selected to be so great that the gas pressure bearing between the piston 36 and the cylinder 34 is fully formed by means of the refrigerant flowing into the compressor 16 from the high pressure outlet 48, before the compressor 16 is activated again. This ensures that the gas pressure bearing between the piston 36 and cylinder 34 is fully formed before the compressor 16 is activated again and the piston 36 moves within the cylinder 34 in order to compress the refrigerant.
| Number | Date | Country | Kind |
|---|---|---|---|
| 10 2014 200 981.2 | Jan 2014 | DE | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/EP2015/050150 | 1/7/2015 | WO | 00 |
