Refrigerant Compressor

Abstract

In order to operate as energy-efficiently as possible a refrigerant compressor, comprising a reciprocating piston compressor and an electric motor, an overall housing having a motor housing portion for the electric motor and a compressor housing portion for the reciprocating piston compressor, a suction connector connected to a low-pressure side of the reciprocating piston compressor, a pressure connector connected to a high-pressure side of the reciprocating piston compressor, wherein provided in the compressor housing portion is at least one cylinder of the reciprocating piston compressor, which has a piston that is movable in a cylinder bore formed in the compressor housing portion, a valve plate closing the cylinder bore, and a cylinder head that spans the valve plate and forms part of the compressor housing portion, it is proposed that a mechanical performance control unit should be provided by which the low-pressure side and the high-pressure side are connectable to one another for the purpose of reducing performance, and that there should be provided in the region of the cylinder head a nonreturn valve that is held against the cylinder head and that allows a refrigerant stream exiting therefrom on the high-pressure side and blocks a refrigerant stream counter to this refrigerant stream.

Description

The present disclosure relates to the subject matter disclosed in German application number 10 2023 128 426.6 of 17 Oct. 2023, which is incorporated herein by reference in its entirety and for all purposes.

BACKGROUND OF THE INVENTION

The invention relates to a refrigerant compressor, comprising a reciprocating piston compressor and an electric motor, an overall housing having a motor housing portion for the electric motor and a compressor housing portion for the reciprocating piston compressor, a suction connector connected to a low-pressure side of the reciprocating piston compressor, a pressure connector connected to a high-pressure side of the reciprocating piston compressor, wherein provided in the compressor housing portion is at least one cylinder of the reciprocating piston compressor, which has a piston that is movable in a cylinder bore formed in the compressor housing portion, a valve plate closing the cylinder bore, and a cylinder head that spans the valve plate and forms part of the compressor housing portion.

Refrigerant compressors of this kind are known from the prior art.

In these refrigerant compressors there arises the problem of operating them as energy-efficiently as possible with as simple a construction as possible.

SUMMARY OF THE INVENTION

In accordance with an embodiment of the invention, in the case of a refrigerant compressor of the type mentioned in the introduction, a mechanical performance control unit is provided by which the low-pressure side and the high-pressure side are connectable to one another for the purpose of reducing performance, and provided in the region of the cylinder head is a nonreturn valve that is held against the cylinder head and that allows a refrigerant stream exiting therefrom and blocks a refrigerant stream counter to this refrigerant stream.

An externally controlled performance control unit of this kind provides the possibility of using the mechanical performance control unit, which is inexpensive and efficient, to control the compressor conveying performance of the semi-hermetic refrigerant compressor without a frequency converter for the electric motor, and it also in particular opens up the possibility of reducing mechanical loads on the reciprocating piston compressor.

In particular here, for the purpose of reducing performance, it is provided for the mechanical performance control unit to connect the outlet refrigerant path on the high-pressure side to the inlet refrigerant path on the low-pressure side in at least one cylinder.

This provides the possibility of operating the at least one cylinder such that it does not contribute to the compressor conveying performance.

This solution has the advantage that, as a result, when there is a performance reduction the mechanical load on the components of the reciprocating piston compressor is small, since the refrigerant is at a pressure level close to that of the inlet side and flows back from the high-pressure side to the low-pressure side, and during this there are no major fluctuations in pressure or even peaks in pressure and temperature in the reciprocating piston compressor, which in particular also reduce efficiency during performance reduction.

The advantage of this solution can further be seen in the fact that, as a result of the nonreturn valve in the region of the cylinder head, there is a possibility of ensuring that a drop in pressure at the pressure connector can be avoided without complex structural measures, in particular changes to the compressor housing portion.

It is particularly advantageous if the nonreturn valve is arranged downstream of the outlet chamber and prevents backflow of refrigerant downstream of the nonreturn valve into the outlet chamber, and thus limits the volume that is relevant to functioning of the mechanical performance control unit to the volume of the outlet chamber.

It is particularly favorable for the spatial arrangement of the nonreturn valve if it is arranged on the cylinder head at a spacing from the valve plate.

It is particularly favorable here if the nonreturn valve is arranged at a region of the cylinder head remote from the valve plate, since in this case there is a possibility of arranging the receptacle for the nonreturn valve such that it is possible to mount the nonreturn valve simply.

Preferably in this case, the nonreturn valve is arranged in the region of a transition from the outlet chamber into an outlet refrigerant path, wherein with this solution the outlet refrigerant path may either lead directly away from the cylinder head or still run in part within the cylinder head.

Further, it is advantageously provided for the nonreturn valve to be arranged and fixed in a receptacle that is provided on the cylinder head.

The provision of a receptacle of this kind in particular provides the possibility of mounting a nonreturn valve of this kind simply. In this case, the receptacle may be mounted on or in the cylinder head as a separate part.

Another advantageous solution provides for the receptacle to be integrally formed on the cylinder head.

Moreover, it is preferably provided for the nonreturn valve to be arranged sealed tight to the receptacle.

More detailed statements have not been made in the context of the above explanation of the solution according to the invention as regards the form taken by the nonreturn valve itself.

For example, in theory it would be conceivable to form the nonreturn valve as a valve tongue, similar to the inlet and outlet valves.

A further advantageous solution provides for the nonreturn valve to have a valve body with at least one through opening in it, and for the through opening to be closable by a reed valve that is movable in relation to the valve body.

Because in this case the nonreturn valve has a valve body where the through opening is sited, the nonreturn valve as a whole is mountable in the receptacle in a simple manner.

Further, it is preferably provided for the reed valve to be resiliently urged in the direction of a flow-blocking position in abutment against a sealing face of the valve body.

In particular here, the reed valve is urged by a separate spring element, with the result that the reed valve itself need not provide the resilient action.

Further, it is advantageous for the realization of permanent reliable functioning of the reed valve if the reed valve is guided such that it is movable in relation to the valve body.

In order to achieve as large as possible an opening cross section in the cleared-for-flow position, it is preferably provided for the reed valve as a whole to be at a spacing from the valve body in a cleared-for-flow position, with the result that overall the reed valve has the same travel during transfer from the flow-blocking position to the cleared-for-flow position, and can thus also make available as large as possible an opening cross section in the cleared-for-flow position.

Moreover, advantageously, it is provided for the nonreturn valve to have a capturing body for the reed valve, which positions the reed valve in its cleared-for-flow position such that as a result the position of the reed valve in the cleared-for-flow position is likewise exactly predeterminable.

Preferably in this case, the capturing body likewise takes a form such that the spring element that urges the reed valve is supported against the capturing body.

More detailed statements have not yet been made as regards the form further taken by the valve body of the nonreturn valve.

For example, an advantageous solution provides for the valve body to take the form of an annular body which consequently has an advantageous external contour for mounting it in the receptacle in a sealed manner.

In this arrangement, the annular body could itself be screwed into the receptacle.

However, it is also conceivable for the annular body to be inserted into the receptacle with a tolerance and to be fixed in the receptacle by separate fixing elements such as one or more retaining rings.

If the valve body takes the form of an annular ring, it is further advantageously provided for the valve body to have at least one through opening which is arranged in an annular region around a center axis.

Preferably, it is provided for the valve body to have a plurality of through openings arranged in the annular region around the center axis.

As an adaptation to the valve body taking the form of an annular body, the reed valve could take the form of a disk that can close the at least one through opening.

It is particularly favorable if the reed valve takes the form of an annular body in order, in the cleared-for-flow position, to make as large as possible a flow cross section available, based on possible flow through the opening within the annular body.

In particular, it is provided for the reed valve to take the form of an annular body which is arranged in the cleared-for-flow position such that refrigerant flows both over a radially outer external edge of the annular body and also a radially inner internal edge of the annular body, and thus flow conditions that are as favorable as possible are created in the cleared-for-flow position.

No further statements have been made in the context of the above explanation of the solutions according to the invention as regards the arrangement of the mechanical performance control unit.

For example, an advantageous solution provides for the mechanical performance control unit to be arranged on the at least one cylinder head, which creates the advantage that the mechanical performance control unit can thus cooperate with at least one cylinder in a simple manner.

It is particularly favorable if the mechanical performance control unit is at least partly integrated into the at least one cylinder head.

So that it is possible to cooperate with at least one cylinder as optimally as possible, it is preferably provided, for the purpose of reducing performance, for the mechanical performance control unit to connect an outlet chamber in the cylinder head to an inlet chamber in the cylinder head by way of a controllable connection channel.

Thus, direct cooperation of the performance control unit with the at least one cylinder that is associated with the cylinder head is possible, with the result that a compact construction of the refrigerant compressor is realizable when there is a performance control unit constructed in this way.

It is particularly favorable if the connection channel is arranged integrated into the cylinder head, with the result that the space needed for the performance control unit to cooperate with the inlet chamber and the outlet chamber can likewise be optimized.

In particular, it is provided for an outlet chamber in the cylinder head to be arranged directly adjoining at least one outlet opening for the respective cylinder in the valve plate and thus in particular the outlet chamber also directly adjoins the valve plate and the outlet opening, in particular with the outlet valve.

Further, it is preferably provided for an inlet chamber in the cylinder head to be arranged directly adjoining an inlet opening for the respective cylinder in the valve plate, such that the inlet chamber also directly adjoins the valve plate and the inlet opening.

The most diverse possibilities are conceivable as regards the way in which the mechanical performance control unit opens or closes the connection channel between the outlet chamber and the inlet chamber.

For example, it would be conceivable to use a conventional slide valve constructions.

A particularly advantageous solution provides for the mechanical performance control unit to have a closing piston for the purpose of closing the connection channel.

A closing piston of this kind provides the possibility of opening or closing the connection channel in particular with the shortest possible reaction time.

For the purpose of reliable sealing, the closing piston is guided, preferably sealed by a piston ring, in a guide bore, in particular in the cylinder head.

In particular, it is provided, for the purpose of closing the connection channel, for the closing piston to be settable on a sealing seat that runs in a manner surrounding the connection channel, with the result that when the closing piston is set on the sealing seat the connection channel is interrupted, whereas when the closing piston is lifted away from the sealing seat the connection channel is opened again.

In order to achieve reliable closing in the long term, it is preferably provided for a sealing region of the closing piston that is settable on the sealing seat to be made from a metal with lower hardness than a metal from which the sealing seat is made, or vice versa.

In this context, the sealing seat may be arranged in the most diverse ways.

A particularly advantageous and compact solution provides for the sealing seat to be arranged in a wall portion of the cylinder head that separates the inlet chamber from the outlet chamber.

Here, the sealing seat may either be formed as part of the wall portion, or the sealing seat is formed by a component inserted into the wall portion of the cylinder head.

Preferably here, the sealing seat is arranged such that it is arranged in a wall portion running above the valve plate and above the inlet chamber, and consequently in particular the sealing seat is at the same time an intake opening, opposite the valve plate, for the inlet chamber.

Further, it is also preferably provided for the sealing seat to be at the same time an outlet opening for the outlet chamber, such that the sealing seat creates a direct transition point from the outlet chamber into the inlet chamber.

For a spatially compact arrangement, it has proved particularly favorable if the sealing seat is arranged on an opposite side of the inlet chamber to the valve plate.

Preferably, it is possible for the closing piston to be switched rapidly between the closed position and the open position if, starting from the sealing seat, the stroke of the closing piston lies within the range of a quarter to a half of an average diameter of the connection channel.

More detailed statements have not been made in the context of the above explanation of the individual embodiments as regards the association of the mechanical performance control unit with individual cylinders.

For example, one solution provides for the mechanical performance control unit to be associated with a cylinder and, in cases where there is a plurality of cylinders, for a plurality of mechanical performance control units to be provided, wherein it is not absolutely necessary for a mechanical performance control unit to be associated with each cylinder.

A favorable solution provides for a cylinder head to have an inlet chamber and an outlet chamber for a cylinder bank that comprises at least two cylinders.

In this case, a plurality of cylinders is thus grouped together to form a cylinder bank.

Advantageously, with a solution of this kind it is provided for the respective mechanical performance control unit to be associated with a cylinder bank, in particular having at least two cylinders.

In the case of a refrigerant compressor having a plurality of cylinder banks, for example N cylinder banks, it is preferably provided for a mechanical performance control unit to be associated with at least N−1 cylinder banks.

However, so that the performance of the refrigerant compressor can be reduced optimally, it is preferably provided for a mechanical performance control unit to be associated with each cylinder bank.

More detailed statements have not been made in the context of the above explanation of the individual exemplary embodiments as regards actuation of the closing piston.

For example, an advantageous solution provides for the closing piston to be urged by a pressure spring in the direction of the position in which it cooperates with the sealing seat, such that the pressure spring ensures that the closing piston closes the connection channel for example in the non-operative condition of the refrigerant compressor, as a result of the action of the pressure spring.

Further, it is preferably provided for the closing piston to be actuable by a pressure chamber which, depending on the external control of the performance control unit, is configured to be acted upon either by negative pressure or by high pressure, wherein when the pressure chamber is acted upon by negative pressure the closing piston moves over into its open position, and when the pressure chamber is acted upon by high pressure the closing piston is urged in the direction of its closed position, in addition to the action of the pressure spring.

In particular, a volume of the pressure chamber is so small that in the open position of the closing piston it is smaller than a third, preferably smaller than a quarter, more preferably smaller than a fifth, advantageously smaller than a sixth and particularly advantageously smaller than a seventh and even more advantageously smaller than an eighth of the maximum volume of the pressure chamber in the closed position of the closing piston.

This dimensioning of the pressure chamber makes it possible to switch rapidly between the closed position and the open position, since the pressure only has to be changed between negative pressure and high pressure in a small volume.

Preferably, for the purpose of acting upon the pressure chamber respectively with high pressure or negative pressure, a control unit comprised within the performance control unit is provided, by which the action of pressure upon the closing piston is controllable.

For the purpose of carrying out performance control of the refrigerant compressor, a performance controller that controls the at least one performance control unit in accordance with a demanded compressor conveying performance is preferably provided.

Here, the performance controller is connected in particular to a higher-level plant controller, and receives information on the demanded compressor conveying performance from the plant controller.

In accordance with this information on the demanded compressor conveying performance, the performance controller then controls the at least one or plurality of performance control units such that the refrigerant compressor delivers the demanded compressor conveying performance but does not deliver an unnecessarily high compressor conveying performance.

For this purpose, the refrigerant compressor is configured such that its maximum compressor conveying performance is sufficient for the maximum compressor conveying performance demanded by the plant controller, and smaller levels of compressor conveying performance are achieved by reducing the performance using the at least one performance control unit.

More detailed statements have not been made in the context of the explanation of the solution according to the invention as regards the operating modes of the reciprocating piston compressor.

Fundamentally, the reciprocating piston compressor according to the invention can operate with any refrigerant that is conventional for semi-hermetic refrigerant compressors.

However, the solution according to the invention gives particular advantages for operation of the reciprocating piston compressor, in particular damage-free operation of the reciprocating piston compressor, if the reciprocating piston compressor operates with a negative pressure in the range of from 10 bar to 50 bar.

Further, as regards the mechanical load on the reciprocating piston compressor the solution according to the invention is likewise particularly advantageous if the reciprocating piston compressor operates with a high pressure in the range of from 40 bar to 160 bar.

In particular, the refrigerant compressor according to the invention is usable particularly advantageously if the reciprocating piston compressor operates with carbon dioxide as the refrigerant and is configured in particular for operation with carbon dioxide as the refrigerant.

As an alternative or in addition, in accordance with an embodiment of the invention, in the case of a semi-hermetic refrigerant compressor of the type mentioned in the introduction, provision is made that the electric motor takes the form of a synchronous motor, in the rotor of which are arranged permanent magnets for synchronous operation of the electric motor, and a squirrel cage for starting up the electric motor in asynchronous operation.

The advantage of the solution according to the invention can be seen in the fact that an electric motor of this kind, for driving a semi-hermetic refrigerant compressor, has higher energy efficiency, in particular under full load and also under partial load. Further, the advantage of an electric motor of this kind can be seen in the fact that synchronous operation allows the conveying volume to be constant even in the high-load range.

Fundamentally, the electric motor may be cooled in the most diverse ways.

An advantageous solution provides for the refrigerant path on the low-pressure side to pass through the motor housing for the purpose of cooling the electric motor.

Further, a cylinder head for a refrigerant compressor is provided, in particular a reciprocating piston compressor, for mounting on a valve plate that closes at least one cylinder bore and spans it with an open side, such that the cylinder head delimits an inlet chamber, arranged between the valve plate and the cylinder head, and an outlet chamber, wherein a mechanical performance control unit is provided by which an inlet chamber and an outlet chamber are connectable to one another for the purpose of reducing performance, and wherein provided in the region of the cylinder head is a nonreturn valve that is held against the cylinder head and that allows a refrigerant stream exiting therefrom and blocks a refrigerant stream counter to this exiting refrigerant stream.

Further embodiments of the cylinder head become apparent from the features that are described above in the context of the refrigerant compressor.

Thus, the above description of solutions according to the invention comprises in particular the different combinations of features that are defined by the consecutively numbered embodiments below:

• • 1. A refrigerant compressor, comprising a reciprocating piston compressor (12) and an electric motor (14), an overall housing (10) having a motor housing portion (24) for the electric motor (14) and a compressor housing portion (22) for the reciprocating piston compressor (12), a suction connector (272) connected to a low-pressure side of the reciprocating piston compressor (12), and a pressure connector (216, 260′, 260″, 260″′) connected to a high-pressure side of the reciprocating piston compressor (12), wherein provided in the compressor housing portion (22) is at least one cylinder (82, 84) of the reciprocating piston compressor (12), which has a piston (66, 68) that is movable in a cylinder bore (72, 74) formed in the compressor housing portion (22), and a valve plate (88) closing the cylinder bore (72, 74), and a cylinder head (92) that spans the valve plate (88) and forms part of the compressor housing portion (22), wherein a mechanical performance control unit (142) is provided by which the low-pressure side and the high-pressure side are connectable to one another for the purpose of reducing performance, and in that provided in the region of the cylinder head (92) is a nonreturn valve (220) that is held against the cylinder head (92) and that allows a refrigerant stream exiting therefrom on the high-pressure side and blocks a refrigerant stream counter to this exiting refrigerant stream.
  • 2. The refrigerant compressor according to embodiment 1, wherein the nonreturn valve (220) is arranged downstream of the outlet chamber (96) and prevents backflow of refrigerant downstream of the nonreturn valve (22) on the high-pressure side into the outlet chamber (96).
  • 3. The refrigerant compressor according to embodiment 1 or 2, wherein the nonreturn valve (220) is arranged on the cylinder head (92) at a spacing from the valve plate (88).
  • 4. The refrigerant compressor according to one of the preceding embodiments, wherein the nonreturn valve (220) is arranged at a region of the cylinder head (92) remote from the valve plate (88).
  • 5. The refrigerant compressor according to one of the preceding embodiments, wherein the nonreturn valve (220) is arranged in the region of a transition from the outlet chamber (96) into an outlet refrigerant path (210).
  • 6. The refrigerant compressor according to one of the preceding embodiments, wherein the nonreturn valve (220) is arranged and fixed in a receptacle (258) that is arranged on the cylinder head (92).
  • 7. The refrigerant compressor according to one of the preceding embodiments, wherein the receptacle (258) is integrally formed on the cylinder head (92).
  • 8. The refrigerant compressor according to one of the preceding embodiments, wherein the nonreturn valve (220) is arranged sealed tight to the receptacle (258).
  • 9. The refrigerant compressor according to one of the preceding embodiments, wherein the nonreturn valve (220) has a valve body (222) with at least one through opening (226) in it, and in that the through opening (226) is closable by a reed valve (234) that is movable in relation to the valve body (222).
  • 10. The refrigerant compressor according to embodiment 9, wherein the reed valve (234) is resiliently urged in the direction of a flow-blocking position in which the reed valve (234) abuts against a sealing face (232) of the valve body (222).
  • 11. The refrigerant compressor according to embodiment 9 or 10, wherein the reed valve (234) is guided such that it is movable in relation to the valve body (222).
  • 12. The refrigerant compressor according to embodiment 11, wherein the reed valve (234) as a whole is at a spacing from the valve body (222) in a cleared-for-flow position.
  • 13. The refrigerant compressor according to one of embodiments 9 to 12, wherein the nonreturn valve (220) has a capturing body (242) for the reed valve (234), which positions the reed valve (234) in its cleared-for-flow position.
  • 14. The refrigerant compressor according to one of embodiments 9 to 13, wherein the valve body (222) takes the form of an annular body.
  • 15. The refrigerant compressor according to embodiment 14, wherein the valve body (222) has at least one through opening (226) which is arranged in an annular region around a center axis (224).
  • 16. The refrigerant compressor according to embodiment 15, wherein the reed valve (234) takes the form of an annular body.
  • 17. The refrigerant compressor according to embodiment 16, wherein, in the cleared-for-flow position of the reed valve (234), refrigerant flowing through the through openings (226) flows around the reed valve (234) both in the region of its internal edge (252) and also in the region of its external edge (254).
  • 18. The refrigerant compressor according to one of the preceding embodiments, wherein the mechanical performance control unit (142) is arranged on the at least one cylinder head (92).
  • 19. The refrigerant compressor according to embodiment 18, wherein the mechanical performance control unit (142) is at least partly integrated into the at least one cylinder head (92).
  • 20. The refrigerant compressor according to one of the preceding embodiments, wherein, for the purpose of reducing performance, the mechanical performance control unit (142) connects an outlet chamber (96) in the cylinder head (92) to an inlet chamber (94) in the cylinder head (92) by way of a controllable connection channel (144).
  • 21. The refrigerant compressor according to embodiment 20, wherein the connection channel (144) is arranged integrated into the cylinder head (92).
  • 22. The refrigerant compressor according to one of the preceding embodiments, wherein an outlet chamber (96) in the cylinder head (92) is arranged directly adjoining at least one outlet opening (112, 114, 116, 118) for the respective cylinder (82, 84) in the valve plate (88).
  • 23. The refrigerant compressor according to one of the preceding embodiments, wherein an inlet chamber (94) in the cylinder head is arranged directly adjoining an inlet opening (102, 104, 106, 108) for the respective cylinder (82, 84) of the valve plate (88).
  • 24. The refrigerant compressor according to one of the preceding embodiments, wherein the mechanical performance control unit (142) has a closing piston (152) for the purpose of closing the connection channel (144).
  • 25. The refrigerant compressor according to embodiment 24, wherein, for the purpose of closing the connection channel (144), the closing piston (152) is settable on a sealing seat (148) that runs in a manner surrounding the connection channel (144).
  • 26. The refrigerant compressor according to embodiment 24 or 25, wherein a sealing region (154) of the closing piston (152) is made from a metal with lower hardness than a metal from which the sealing seat (148) is made, or vice versa.
  • 27. The refrigerant compressor according to embodiment 25 or 26, wherein the sealing seat (148) is arranged in a wall portion (124) of the cylinder head (92) that separates the inlet chamber (94) from the outlet chamber (96).
  • 28. The refrigerant compressor according to one of embodiments 25 to 27, wherein the sealing seat (148) is arranged in a wall portion (124) running above the valve plate (88) and above the inlet chamber (94).
  • 29. The refrigerant compressor according to one of embodiments 25 to 28, wherein the sealing seat (148) is arranged on an opposite side of the inlet chamber (94) to the valve plate (88).
  • 30. The refrigerant compressor according to one of embodiments 25 to 29, wherein, starting from the sealing seat (148), a stroke of the closing piston (152) lies within the range of a quarter to a half of an average diameter of the connection channel (144).
  • 31. The refrigerant compressor according to one of the preceding embodiments, wherein a cylinder head (92) has an inlet chamber (94) and an outlet chamber (96) for a cylinder bank (86) that comprises at least two cylinders (82, 84).
  • 32. The refrigerant compressor according to one of the preceding embodiments, wherein the respective mechanical performance control unit (142) is associated with a cylinder bank (86).
  • 33. The refrigerant compressor according to one of the preceding embodiments, wherein, in the case of the refrigerant compressor having N cylinder banks (86), a mechanical performance control unit (142) is associated with at least N−1 cylinder banks (86).
  • 34. The refrigerant compressor according to one of embodiments 31 to 33, wherein a mechanical performance control unit (142) is associated with each cylinder bank (86).
  • 35. The refrigerant compressor according to one of embodiments 24 to 34, wherein the closing piston (152) is urged by a pressure spring (166) in the direction of the position in which it cooperates with the sealing seat (148).
  • 36. The refrigerant compressor according to one of embodiments 24 to 35, wherein the closing piston (152) is actuable by a pressure chamber (162) which, depending on the external control of the performance control unit (142), is configured to be acted upon either by negative pressure or by high pressure.
  • 37. The refrigerant compressor according to embodiment 36, wherein, in the open position of the closing piston (152), the pressure chamber (162) has a volume that is smaller than a third, preferably smaller than a quarter, of the maximum volume of the pressure chamber (162) in the closed position.
  • 38. The refrigerant compressor according to one of the preceding embodiments, wherein a control unit (182) comprised within the performance control unit (142) is provided, by which the action of pressure upon the closing piston (152) is controllable.
  • 39. The refrigerant compressor according to one of the preceding embodiments, wherein there is provided a performance controller (138) that controls the at least one performance control unit (142) in accordance with a demanded compressor conveying performance.
  • 40. A cylinder head (92) for a refrigerant compressor, in particular a reciprocating piston compressor, for mounting on a valve plate (88) that closes at least one cylinder bore (72, 74) and spans it with an open side (93), such that the cylinder head (92) delimits an inlet chamber (94), arranged between the valve plate (88) and the cylinder head (92), and an outlet chamber (96), wherein a mechanical performance control unit (142) is provided by which an inlet chamber (94) and an outlet chamber (96) are connectable to one another for the purpose of reducing performance, and in that provided in the region of the cylinder head (92) is a nonreturn valve (220) that is held against the cylinder head (92) and that allows a refrigerant stream exiting therefrom and blocks a refrigerant stream counter to this exiting refrigerant stream.
  • 41. The cylinder head according to embodiment 40, wherein the nonreturn valve (220) is arranged downstream of the outlet chamber (96) and prevents backflow of refrigerant downstream of the nonreturn valve (22) into the outlet chamber (96).
  • 42. The cylinder head according to embodiment 40 or 41, wherein the nonreturn valve (220) is arranged on the cylinder head (92) at a spacing from the open side (93).
  • 43. The cylinder head according one of embodiments 40 to 42, wherein the nonreturn valve (220) is arranged at a region of the cylinder head (92) remote from the open side (93).
  • 44. The cylinder head according to one of embodiments 40 to 43, wherein the nonreturn valve (220) is arranged in the region of a transition from the outlet chamber (96) into an outlet refrigerant path (210).
  • 45. The cylinder head according to one of embodiments 40 to 44, wherein the nonreturn valve (220) is arranged and fixed in a receptacle (258) that is arranged on the cylinder head (92).
  • 46. The cylinder head according to one of embodiments 40 to 45, wherein the receptacle (258) is integrally formed on the cylinder head (92).
  • 47. The cylinder head according to one of embodiments 40 to 46, wherein the nonreturn valve (220) is arranged sealed tight to the receptacle (258).
  • 48. The cylinder head according to one of embodiments 40 to 47, wherein the nonreturn valve (220) has a valve body (222) with at least one through opening (226) in it, and in that the through opening (226) is closable by a reed valve (234) that is movable in relation to the valve body (222).
  • 49. The cylinder head according to embodiment 48, wherein the reed valve (234) is resiliently urged in the direction of a flow-blocking position in which the reed valve (234) abuts against a sealing face (232) of the valve body (222).
  • 50. The cylinder head according to embodiment 48 or 49, wherein the reed valve (234) is guided such that it is movable in relation to the valve body (222).
  • 51. The cylinder head according to embodiment 50, wherein the reed valve (234) as a whole is at a spacing from the valve body (222) in a cleared-for-flow position.
  • 52. The cylinder head according to one of embodiments 48 to 51, wherein the nonreturn valve (220) has a capturing body (242) for the reed valve (234), which positions the reed valve (234) in its cleared-for-flow position.
  • 53. The cylinder head according to one of embodiments 48 to 52, wherein the valve body (222) takes the form of an annular body.
  • 54. The cylinder head according to embodiment 53, wherein the valve body (222) has at least one through opening (226) which is arranged in an annular region around a center axis (224).
  • 55. The cylinder head according to embodiment 54, wherein the reed valve (234) takes the form of an annular body.
  • 56. The cylinder head according to embodiment 55, wherein, in the cleared-for-flow position of the reed valve (234), refrigerant flowing through the through openings (226) flows around the reed valve (234) both in the region of its internal edge (252) and also in the region of its external edge (254).
  • 57. The cylinder head according to one of embodiments 40 to 56, wherein the mechanical performance control unit (142) is arranged on the cylinder head (92), in particular in that the mechanical performance control unit (142) is at least partly integrated into the at least one cylinder head (92).
  • 58. The cylinder head according to one of embodiments 40 to 57, wherein, for the purpose of reducing performance, the mechanical performance control unit (142) connects the outlet chamber (96) in the cylinder head (92) to the inlet chamber (94) in the cylinder head (92) by way of a controllable connection channel (144), in particular in that the connection channel (144) is arranged integrated into the cylinder head (92).
  • 59. The cylinder head according to one of embodiments 40 to 58, wherein the mechanical performance control unit (142) has a closing piston (152) for the purpose of closing the connection channel (144), in particular in that, for the purpose of closing the connection channel (144), the closing piston (152) is settable on a sealing seat (148) that runs in a manner surrounding the connection channel (144), in particular in that a sealing region (154) of the closing piston (152) is made from a metal with lower hardness than a metal from which the sealing seat (148) is made, or vice versa, in particular in that the sealing seat (148) is arranged in a wall portion (124) of the cylinder head (92) that separates the inlet chamber (94) from the outlet chamber (96), in particular in that the sealing seat (148) is arranged in a wall portion (124) running above the valve plate (88) and above the inlet chamber (94), in particular in that the sealing seat (148) is arranged on an opposite side of the inlet chamber (94) to the valve plate (88).
  • 60. The cylinder head according to one of embodiments 40 to 59, wherein a control unit (182) comprised within the performance control unit (142) is provided, by which the action of pressure upon the closing piston (152) is controllable.
  • 61. The cylinder head according to one of embodiments 40 to 60, wherein there is provided a performance controller (138) that controls the at least one mechanical performance control unit (142) in accordance with a demanded compressor conveying performance.

Further features and advantages of the invention form the subject matter of the description below and the illustration in the drawing of some exemplary embodiments.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a side view of an exemplary embodiment of a refrigerant compressor according to the invention;

FIG. 2 shows a plan view, in the direction of the arrow A in FIG. 1, of the refrigerant compressor according to the invention;

FIG. 3 shows a front view of the exemplary embodiment of the refrigerant compressor according to the invention;

FIG. 4 shows a section along the line 4-4 in FIG. 2, with one half offset;

FIG. 5 shows a longitudinal section, along the line 5-5 in FIG. 2, through the refrigerant compressor according to the invention;

FIG. 6 shows a section along the line 6-6 in FIG. 7;

FIG. 7 shows a section through a first exemplary embodiment of a cylinder head according to the invention, along the line 7-7 in FIG. 6;

FIG. 8 shows an enlarged illustration of a nonreturn valve according to the invention in the closed position;

FIG. 9 shows an illustration similar to FIG. 8, of the nonreturn valve according to the invention in the open position;

FIG. 10 shows an illustration similar to FIG. 7, of a second exemplary embodiment of a cylinder head according to the invention;

FIG. 11 shows an illustration similar to FIG. 7, of a third exemplary embodiment of a cylinder head according to the invention; and

FIG. 12 shows an illustration similar to FIG. 7, of a fourth exemplary embodiment of a cylinder head according to the invention.

DETAILED DESCRIPTION OF THE INVENTION

One exemplary embodiment of a refrigerant compressor according to the invention, illustrated in FIGS. 1 to 5, comprises an overall housing 10 in which there are arranged a reciprocating piston compressor 12, in particular a compressor with pistons that are movable by a shaft axis, and an electric motor 14.

Preferably, the overall housing 10 comprises a compressor housing portion 22, which is an external housing of the reciprocating piston compressor 12, and a motor housing portion 24, which is an external housing of the electric motor 14.

The overall housing 10 is preferably formed by a one-piece housing body 26 which extends in a direction parallel to a center axis 28, explained in detail below, and is closed at the end on the compressor housing portion 22 side by a bearing cap 32 and is closed at the end in the region of the motor portion 24 by an end cover 34.

A compressor shaft, designated 42 as a whole, extends in the compressor housing portion 22, coaxially relative to the center axis 28, between a first shaft bearing 44 arranged on the bearing cap 32 and a second shaft bearing 46 that is arranged between the reciprocating piston compressor 12 and the electric motor 14, wherein the second shaft bearing 46 is held against a center wall 48, which is made in the housing body 26 and delimits a drive compartment 52, wherein the drive compartment 52 is located between the bearing cap 32 and the center wall 48, the compressor shaft 42 extends through it, and eccentrics 54 and 56 of the compressor shaft 42 are arranged therein, wherein arranged on each of the eccentrics 54 and 56 are respectively a connecting rod 62₁ and 62₂ each having a connecting rod arm, and two connecting rods 64₁ and 64₂ each having a connecting rod arm, wherein the connecting rod arms of the connecting rods 62₁ and 64₁ drive the pistons 66₁ and 68₁, and the connecting rod arms of the connecting rods 62₂ and 64₂ drive the pistons 66₂ and 68₂.

The pistons 66 and 68, which in particular in the case of the compressor are driven and movable radially relative to the compressor shaft 42, are guided in cylinder bores 72 and 74 that are formed by cylinder housings 76, 78 that are made in the compressor housing portion 22 and are in particular made in one piece therewith.

Each cylinder housing 76, 78, together with the cylinder bore 72, 74 and the piston 66, 68 guided therein, forms a respective cylinder 82, 84.

The two first cylinders 82₁ and 84₁ that are made in the compressor housing portion 22 form a first cylinder bank 86₁, while the two cylinders 82₂ and 84₂ that are formed in the compressor housing portion 22 form a second cylinder bank 86₂.

In each of the cylinder banks 86₁ and 86₂, the respective cylinder bores 72₁ and 74₁, and 72₂ and 74₂, are closed by a common valve plate 88₁ and 88₂, which with the aid of a gasket 89 lies on the respective cylinder housings 76₁ and 78₁, and 76₂ and 78₂, such that it is sealed tight, and thus delimit compression chambers that are surrounded by the respective valve plate 88₁ and 88₂ respectively and the respective piston 66₁ and 68₁, or 66₂ and 68₂, and the cylinder bores 72₁ and 74₁ or 72₂ and 74₂.

For their part, the valve plates 88₁ and 88₂ are then in turn covered by cylinder heads 92₁ and 92₂ respectively, wherein the open sides 93₁, 93₂ of the respective cylinder heads 92₁ and 92₂ face the valve plates 88₁ and 88₂ and lie on the valve plates 88₁ and 88₂ such that they are sealed tight.

As illustrated in FIGS. 6 and 7, in each of the cylinder heads 92₁ and 92₂ there is arranged respectively an inlet chamber 94, comprised within a low-pressure side of the reciprocating piston compressor 12, and an outlet chamber 96, comprised within a high-pressure side of the reciprocating piston compressor 12, and these are associated with the two cylinders 82 and 84 of the respective cylinder bank 86.

In particular, the inlet chamber 94 lies above inlet openings 102 and 104 of the cylinder 82, which are made in the respective valve plate 88, and inlet openings 106 and 108 of the cylinder 84 of the respective cylinder bank 86, for example the cylinder bank 86₂, and directly adjoins the valve plate 88.

Further, the outlet chamber 96 lies above outlet openings 112 and 114 of the cylinder 82, which are made in the respective valve plate 88, and outlet openings 116 and 118 of the cylinder 84, which are provided with outlet valves 113, 115, 117, 119 seated on the valve plate 88, and directly adjoins the valve plate 88.

As illustrated in FIGS. 6 and 7, each cylinder head 92 comprises an external body 122 which is supported on the respective valve plate 88 by way of a sealing layer 123 and spans this and surrounds the inlet chamber 94 and the outlet chamber 96, which for their part are in turn separated from one another by a separating body 124 that runs within the external body 122 and is connected thereto, wherein the external body 122 and the separating body 124 extend upward from the respective valve plate 88 and extend over and span the inlet chamber 94 and the outlet chamber 96.

Thus, the outlet chamber 96 lies laterally next to the inlet chamber 94 in the region of the valve plate 88, and extends between the external body 122 and the separating body 124, at least in certain regions also above the inlet chamber 94.

For the purpose of controlling performance, that is to say controlling the compressor conveying performance, of the refrigerant compressor, associated with each cylinder head 92 there may be a mechanical performance control unit 142 that is actively controlled by a performance controller 138 and by which a connection channel 144 between the outlet chamber 96 and the inlet chamber 94 may be closed or opened, wherein when the connection channel 144 is closed (FIG. 7) the respective cylinders 82, 84 associated with the cylinder head 92 compress refrigerant at full performance, and when the connection channel 144 is open they do not compress refrigerant, since the refrigerant flows back from the outlet chamber 96 and into the inlet chamber 94 through the connection channel 144.

Here, a portion 144a of the connection channel 144 runs through an insert part 146 which is inserted into the separating body 124, which forms a sealing seat 148 facing the outlet chamber 96, and which adjoins a part of the outlet chamber 96 that surrounds the sealing seat 148 and adjoins it.

Further, the sealing seat 148 faces a closing piston 152 which is configured to be set on the sealing seat 148, for example by a sealing region 154 made of metal, in order to close the connection channel 144 in a manner that seals tight, and which is configured to be raised away from the sealing seat 148 far enough for the sealing region 154 to be at a spacing from the sealing seat 148 and thus for refrigerant to be able to flow over from the outlet chamber 96 through the portion 144b and into the inlet chamber 94 through the portion 144a.

Preferably in this case, the closing piston 152 is guided coaxially relative to the insert part 146 having the sealing seat 148 and, sealed by a piston ring 153, in a guide bore 156 that is formed by a guiding bushing body 158 of the cylinder head 92 which is integrally formed on the external body 122.

Preferably, the closing piston 152 itself or at least the sealing region 154 is made from a metal, for example a non-ferrous metal, of lower hardness than the metal of the sealing seat 148, which is made for example from steel, in particular hardened steel.

In order to enable rapid movement of the closing piston 152, in particular a stroke of the closing piston 152 between a closed position (FIG. 7) and an open position, indicated in dashed lines in FIG. 7, is in the range between a quarter and a half of an average diameter of the connecting channel 144.

Here, the closing piston 152 delimits a pressure chamber 162, which is arranged on a side of the closing piston 152 remote from the sealing region 154 and is closed by a terminating body 164 on an opposite side to the closing piston 152.

The volume of the pressure chamber 162 is in particular so small that in the open position of the closing piston it is smaller than a third, preferably smaller than a quarter, more preferably smaller than a fifth, advantageously smaller than a sixth and even more advantageously smaller than an eighth of the maximum volume of the pressure chamber 162 in the closed position of the closing piston 152.

Further, arranged in the pressure chamber 162 is a pressure spring 166 that on one side is supported against the terminating body 164 and on the other urges the closing piston 152 in the direction of its closed position seated on the sealing seat 148.

Depending on the pressurized urging of the pressure chamber 162, the closing piston 152 is movable into its open position, illustrated in dashed lines in FIG. 7, or into its closed position, illustrated in FIG. 7.

For this purpose, a throttle channel 172 passes through the closing piston 152 and extends from the pressure chamber 162 through the closing piston 152 to an outlet opening 157 that is arranged radially outside the sealing region 154 on a side facing the sealing seat 148, but, because it lies radially outside the sealing element 154, in the closed position of the closing piston 152 it allows entry to refrigerant that is under pressure in the outlet chamber 96 and that flows around the sealing seat, and supplies it to the pressure chamber 162 in a throttled arrangement.

Moreover, a relief channel 176 leads into the pressure chamber 162, for example through the terminating body 164, and is configured to be connected by a solenoid valve, designated 182 as a whole, to a pressure relief channel 184 connected to the inlet chamber 94.

For example, the solenoid valve 182 takes a form such that it has a valve body 186 by which the connection between the pressure relief channel 184 and the relief channel 176 can be made or broken.

If the connection between the relief channel 176 and the pressure relief channel 184 is made, negative pressure dominates in the pressure chamber 162, while the closing piston 152 is acted upon by the pressure in the outlet chamber 96 on its side facing the outlet chamber 96 and is thus moved into its open position.

However, if the connection between the pressure relief channel 184 and the relief channel 176 is broken by the valve body 186, the pressure spring 166 presses the closing piston 152 onto the sealing seat 148, and in addition high pressure flows into the pressure chamber 162 through the throttle channel 172, with the result that in the pressure chamber 162 high pressure builds up and, in addition to the action of the pressure spring 166, presses the closing piston 152 onto the sealing seat 148 with the sealing element 154.

In particular, the closing piston 152 takes a form such that it extends radially beyond the sealing seat 148, such that even when the closing piston 152 is in the closed position the piston face that is radially outside the sealing seat 148 and is acted upon by high pressure results in the closing piston 152 being moved in opposition to the force of the pressure spring 166 and into the open position, illustrated in dashed lines in FIG. 7, provided the valve body 186 of the solenoid valve 182 makes the connection between the relief channel 176 and the pressure relief channel 184, which has the result that a negative pressure is established in the pressure chamber 162.

Refrigerant under negative pressure is supplied by way of a supply channel 202 (FIG. 5) that is made in the compressor housing portion 22, is comprised within the low-pressure side of the reciprocating piston compressor 12, and leads to an inlet opening 204 (FIG. 7) leading to the valve plate 88, wherein refrigerant under negative pressure flows through the inlet opening 204 to a passage opening 206 in the valve plate 88 and passes through this into the inlet chamber 94.

Moreover, as illustrated in FIG. 7, an outlet channel 210 that is made in the cylinder head 92 and comprised within the high-pressure side of the reciprocating piston compressor 12 leads from the outlet chamber 96 to an outlet opening 212 in the valve plate 88, through which the pressurized refrigerant in the outlet chamber 96 passes into an outlet channel 214 provided in the compressor housing portion 22 and can flow to a pressure connector 216.

Provided at the transition from the outlet chamber 96 to the outlet channel 210 is a nonreturn valve, designated 220 as a whole, which, as illustrated on a larger scale in FIGS. 8 and 9, has a valve body 222 which takes the form for example of an annular body and has through openings 226 that are arranged successively in an annular region around a center axis 224 and pass through the valve body 222 from an inflow side 228 to an outflow side 232.

A reed valve 234, likewise taking the form of an annular body, is provided such that it is movable in relation to the valve body 222 and, for the purpose of closing the through openings 226, is configured to abut against the outflow side 232 of the valve body 222 in a manner that seals tight and, for the purpose of clearing the through openings 226, is configured to move as a whole away from the outflow side 232 and to be positioned at a spacing therefrom.

This position of the reed valve 234, blocking flow 226 through the nonreturn valve 220 from the outflow side 232 in the direction of the inflow side 228, is brought about by a spring element 236 which likewise takes the form of an annular body and is supported on the one hand on an opposite side of the reed valve 234 to the outflow side 232 and on the other hand against a capturing body 242 of the nonreturn valve 220, wherein the capturing body 242 is held at a spacing from the outflow side 232, for example at a center region 244 of the valve body 222 that lies between the through openings 226 and the center axis 224, this center region 244 running around the center axis 224 and on the inside of the through openings 226.

Preferably, anchored in the center region 244 is a holding pin 246 which passes through central openings in both the reed valve 234 and also the spring element 236 and extends as far as the capturing body 242 and is firmly connected thereto, with the result that the holding pin 246 fixes the capturing body 242 such that it is undisplaceable in the direction of the center axis 224 in relation to the valve body 222, to prevent movements in the direction of the center axis 224.

In the position illustrated in FIG. 9, which is open to the maximum, the reed valve 234, which has been moved as a whole away from the outflow side 232, enables flow through each of the respective through openings 226 from the inflow side 228 in the direction of the outflow side 232, wherein the flow then exits on the outflow side 232, from the respective through opening 226, and in relation to the center axis 224 flows radially outward and radially inward in the direction of the holding pin 246, in order to flow past both an internal edge 252 and an external edge 254 of the reed valve 234, and past an outer side of the spring element 236 and the capturing body 242 and through openings 248 made in the capturing body 242 around the holding pin 246.

Preferably, the valve body 222 takes the form of an annular body—that is to say is rotationally symmetrical in relation to the center axis 224—and has a circle-cylindrical outer face 255 by which it is inserted in a receptacle 258 formed at the transition from the outlet chamber 96 to the outlet channel 210, and is fixed for example on the one side thereof by a flange 256 that is provided and on the other by a securing ring 257, and in so doing terminates at the receptacle 258 and tight therewith.

As an alternative thereto, the outer face 255 may be provided with a thread and be screwed into a thread in the receptacle 258.

When a pressure lower than high pressure prevails in the outlet chamber 96, for example when there is a drop in pressure brought about by the performance controller 138 using the performance control unit 142, the reed valve 234 closes the through openings 226 as a result of the action of the spring element 236, with the result that pressure is maintained in the outlet channel 210, and a pressure equalization between the outlet chamber 96 and the inlet chamber 94 as a result of the action of the mechanical performance control unit 142 does not have an effect on the pressure in the outlet channel 210.

Thus, as a result of arranging the nonreturn valve 220 in the respective cylinder head 92, it is possible, in a simple manner, to convert a conventional compressor—for example one without performance control—into a cylinder head 92 with controllable performance by substituting the cylinder head 92 with the performance control unit 142 and the nonreturn valve 220, without the need for any changes in the construction of the respective valve plate 88 and the respective cylinder bank 86.

In a second exemplary embodiment of a refrigerant compressor according to the invention with a second exemplary embodiment of a cylinder head 92′ according to the invention, the elements that are identical to those of the first exemplary embodiment are provided with the same reference numerals, so reference can be made to the statements regarding the first exemplary embodiment in their entirety.

Unlike the first exemplary embodiment, the outlet channel 210′ in the cylinder head 92′ takes a form such that it leads directly to a pressure connector 260′ that is provided on the cylinder head 92′ and that is guided, for example from an opposite side to the valve plate 88, to the external body 122 and is directly connected thereto, with the result that the outlet channel 210′ merges directly into a pressure conduit of the pressure connector 260′.

In this case, the receptacle 258′ for the valve body 222 is provided in the cylinder head 92′ in a receiving body 262 that projects into the outlet chamber 96 from an opposite side to the valve plate 88, wherein the receiving body 262 is preferably likewise integrally formed in one piece with the external body 122 of the cylinder head 92′.

In a third exemplary embodiment of a refrigerant compressor according to the invention with a third exemplary embodiment of a cylinder head 92″, illustrated in FIG. 11, the nonreturn valve 220 is arranged such that the valve body 222 is seated in a receptacle 258″ that is formed directly in an outer wall of the external body 122 of the cylinder head 92″, with the result that there is absolutely no need for any additional measures for receiving the nonreturn valve 220 in the cylinder head 92″, but all that needs to be done is to provide a passage in the outer wall of the external body 122, which forms the receptacle 258″ for the valve body 222, wherein for example the valve body 222 is screwed into an internal thread of the receptacle 258″ by an external thread.

In this case, the pressure connector 260″ can be mounted on the external body 122 in a simple manner, with the result that the refrigerant passing through the nonreturn valve 220 can directly enter the pressure conduit of the pressure connector 260″.

Otherwise, in the third exemplary embodiment, the elements that are identical to the above exemplary embodiments are provided with the same reference numerals, so for a description thereof reference can be made to the statements regarding the above exemplary embodiments in their entirety.

In a fourth exemplary embodiment of a refrigerant compressor according to the invention with a fourth exemplary embodiment of a cylinder head 92″′, the elements that are identical to those of the above exemplary embodiments are provided with the same reference numerals, so for a description thereof reference can be made to the statements regarding the above exemplary embodiments in their entirety.

Unlike the above exemplary embodiments, in the fourth exemplary embodiment it is provided for there to be made in the external body 122 of the cylinder head 92″′ a passage 264 from which refrigerant can directly enter the pressure connector 260″′, wherein the nonreturn valve 220 is inserted into a receptacle 258″′ that is arranged on the inlet side of the pressure connector 260″′, with the result that the pressure connector 260″′ itself forms the receptacle 258″′ for the valve body 222.

Here, for example the pressure connector 260″′ may be part of a blocking valve 266 mounted on the cylinder head 92″′.

Thus, in the fourth exemplary embodiment of the refrigerant compressor according to the invention, the nonreturn valve 220 is not received in the cylinder head 92″′ but held on the cylinder head 92″′ indirectly by way of the high-pressure connector 260.

The exemplary embodiments of the refrigerant compressors according to the invention take the form for example of semi-hermetic compressors, such that refrigerant under negative pressure is supplied to a motor compartment 274 by an inlet connector element 272 that is arranged on the end cover 34, and flows through the electric motor 14 in the direction of the center wall 48 and passes out of the motor compartment 274 through into the supply channel 202, with the result that the supplied refrigerant on the low-pressure side brings about cooling of the electric motor 14 in the motor compartment 274.

For its part, the electric motor 14 comprises a stator 282 that is held fixed in the motor housing portion 24 and has a stator winding 284.

The stator 282 further has a rotor 286, which comprises for example permanent magnets and is operable as a synchronous motor, and in addition a squirrel cage, so that it may start up as an asynchronous motor.

Claims

1. A refrigerant compressor, comprising a reciprocating piston compressor and an electric motor, an overall housing having a motor housing portion for the electric motor and a compressor housing portion for the reciprocating piston compressor, a suction connector connected to a low-pressure side of the reciprocating piston compressor, and a pressure connector connected to a high-pressure side of the reciprocating piston compressor, wherein provided in the compressor housing portion is at least one cylinder of the reciprocating piston compressor, which has a piston that is movable in a cylinder bore formed in the compressor housing portion, and a valve plate closing the cylinder bore, and a cylinder head that spans the valve plate and forms part of the compressor housing portion, wherein a mechanical performance control unit is provided by which the low-pressure side and the high-pressure side are connectable to one another for the purpose of reducing performance, and wherein provided in the region of the cylinder head is a nonreturn valve that is held against the cylinder head and that allows a refrigerant stream exiting therefrom and blocks a refrigerant stream counter to this exiting refrigerant stream.

2. The refrigerant compressor as claimed in claim 1, wherein the nonreturn valve is arranged downstream of the outlet chamber and prevents backflow of refrigerant downstream of the nonreturn valve into the outlet chamber.

3. The refrigerant compressor as claimed in claim 1, wherein the nonreturn valve is arranged on the cylinder head at a spacing from the valve plate.

4. The refrigerant compressor as claimed in claim 1, wherein the nonreturn valve is arranged at a region of the cylinder head remote from the valve plate.

5. The refrigerant compressor as claimed in claim 1, wherein the nonreturn valve is arranged in the region of a transition from the outlet chamber into an outlet refrigerant path.

6. The refrigerant compressor as claimed in claim 1, wherein the nonreturn valve is arranged and fixed in a receptacle that is arranged on the cylinder head.

7. The refrigerant compressor as claimed in claim 1, wherein the receptacle is integrally formed on the cylinder head.

8. The refrigerant compressor as claimed in claim 1, wherein the nonreturn valve is arranged sealed tight to the receptacle.

9. The refrigerant compressor as claimed in claim 1, wherein the nonreturn valve has a valve body with at least one through opening in it, and wherein the through opening is closable by a reed valve that is movable in relation to the valve body.

10. The refrigerant compressor as claimed in claim 9, wherein the reed valve is resiliently urged in the direction of a flow-blocking position in which the reed valve abuts against a sealing face of the valve body.

11. The refrigerant compressor as claimed in claim 9, wherein the reed valve is guided such that it is movable in relation to the valve body.

12. The refrigerant compressor as claimed in claim 11, wherein the reed valve as a whole is at a spacing from the valve body in a cleared-for-flow position.

13. The refrigerant compressor as claimed in claim 9, wherein the nonreturn valve has a capturing body for the reed valve, which positions the reed valve in its cleared-for-flow position.

14. The refrigerant compressor as claimed in claim 9, wherein the valve body takes the form of an annular body.

15. The refrigerant compressor as claimed in claim 14, wherein the valve body has at least one through opening which is arranged in an annular region around a center axis.

16. The refrigerant compressor as claimed in claim 15, wherein the reed valve takes the form of an annular body.

17. The refrigerant compressor as claimed in claim 16, wherein, in the cleared-for-flow position of the reed valve, refrigerant flowing through the through openings flows around the reed valve both in the region of its internal edge and also in the region of its external edge.

18. The refrigerant compressor as claimed in claim 1, wherein the mechanical performance control unit is arranged on the at least one cylinder head, in particular wherein the mechanical performance control unit is at least partly integrated into the at least one cylinder head.

19. The refrigerant compressor as claimed in claim 1, wherein, for the purpose of reducing performance, the mechanical performance control unit connects an outlet chamber in the cylinder head to an inlet chamber in the cylinder head by way of a controllable connection channel, in particular wherein the connection channel is arranged integrated into the cylinder head.

20. The refrigerant compressor as claimed in claim 1, wherein an outlet chamber in the cylinder head is arranged directly adjoining at least one outlet opening for the respective cylinder in the valve plate.

21. The refrigerant compressor as claimed in claim 1, wherein an inlet chamber in the cylinder head is arranged directly adjoining an inlet opening for the respective cylinder of the valve plate.

22. The refrigerant compressor as claimed in claim 1, wherein the mechanical performance control unit has a closing piston for the purpose of closing the connection channel, in particular wherein, for the purpose of closing the connection channel, the closing piston is settable on a sealing seat that runs in a manner surrounding the connection channel, in particular wherein a sealing region of the closing piston is made from a metal with lower hardness than a metal from which the sealing seat is made, or vice versa, in particular wherein the sealing seat is arranged in a wall portion of the cylinder head that separates the inlet chamber from the outlet chamber, in particular wherein the sealing seat is arranged in a wall portion running above the valve plate and above the inlet chamber, in particular wherein the sealing seat is arranged on an opposite side of the inlet chamber to the valve plate.

23. The refrigerant compressor as claimed in claim 1, wherein a cylinder head has an inlet chamber and an outlet chamber for a cylinder bank that comprises at least two cylinders.

24. The refrigerant compressor as claimed in claim 1, wherein the respective mechanical performance control unit is associated with a cylinder bank.

25. The refrigerant compressor as claimed in claim 1, wherein, in the case of the refrigerant compressor having N cylinder banks, a mechanical performance control unit is associated with at least N−1 cylinder banks.

26. The refrigerant compressor as claimed in claim 23, wherein a mechanical performance control unit is associated with each cylinder bank.

27. The refrigerant compressor as claimed in claim 22, wherein the closing piston is urged by a pressure spring in the direction of the position in which it cooperates with the sealing seat.

28. The refrigerant compressor as claimed in claim 22, wherein the closing piston is actuable by a pressure chamber which, depending on the external control of the performance control unit, is configured to be acted upon either by negative pressure or by high pressure.

29. The refrigerant compressor as claimed in claim 1, wherein a control unit comprised within the performance control unit is provided, by which the action of pressure upon the closing piston is controllable.

30. The refrigerant compressor as claimed in claim 1, wherein there is provided a performance controller that controls the at least one performance control unit in accordance with a demanded compressor conveying performance.