RECIPROCATING PISTON COMPRESSOR FOR REFRIGERANT

In order to increase the efficiency, in respect of the quantity of refrigerant to be compressed, of a reciprocating piston compressor for refrigerant, comprising a compressor housing having at least one compressor stage that has at least one cylinder unit, wherein a piston is movably arranged in the cylinder unit, a cylinder drive that is arranged in the compressor housing, for the at least one piston, a valve plate that closes off a cylinder chamber and is provided with at least one suction valve which, for its part, has a suction opening, arranged in the valve plate and closable by a suction vane, and has at least one outlet valve with an outlet opening, wherein the at least one suction valve and the at least one outlet valve are associated with the respective cylinder chamber, and a cylinder head that is arranged on an opposite side of the valve plate to the cylinder chamber, it is proposed that the valve plate should have, on its side facing the cylinder chamber, a recess, which is arranged inside an external contour of an abutment face of the suction vane that is associated with the suction opening and which extends from the suction opening and is open toward this abutment face.

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Description
CROSS-REFERENCE TO RELATED PATENT APPLICATION

This patent application claims the benefit of German application No. 10 2022 109 938.5, filed Apr. 25, 2022, the teachings and disclosure of which are hereby incorporated in their entirety by reference thereto.

BACKGROUND OF THE INVENTION

The invention relates to a reciprocating piston compressor for refrigerant, comprising a compressor housing having at least one compressor stage that has at least one cylinder unit, which itself comprises at least one cylinder chamber, wherein a piston is movably arranged in the cylinder unit, a cylinder drive that is arranged in the compressor housing, for the at least one piston, a valve plate that closes off the cylinder chamber and is provided with at least one suction valve which, for its part, has a suction opening, arranged in the valve plate and closable by a suction vane, and has at least one outlet valve with an outlet opening, wherein the at least one suction valve and the at least one outlet valve are associated with the respective cylinder chamber, and a cylinder head that is arranged on an opposite side of the valve plate to the cylinder chamber.

Reciprocating piston compressors of this kind are known from the prior art.

There is a need for the efficiency of these to be increased in respect of the quantity of refrigerant to be compressed.

SUMMARY OF THE INVENTION

According to the invention, this object is achieved in the case of a reciprocating piston compressor of the type mentioned in the introduction in that the valve plate has, on its side facing the cylinder chamber, a recess, which is arranged inside an external contour of an abutment face of the suction vane that is associated with the suction opening and which extends from the suction opening and is open toward this abutment face.

The advantage of the solution according to the invention can be seen in the fact that the recess, which adjoins the suction opening and is open toward the abutment face, provides the possibility of enlarging the surface area over which the refrigerant to be drawn in by suction acts on the suction vane immediately before the suction vane is opened, and in so doing provides the possibility of achieving reliable and quicker opening of the suction vane even at low pressures, and hence better filling of the cylinder chamber.

Here, it is particularly favorable if the recess has a recess base that is set back in relation to the abutment face of the suction vane and thus makes it possible for the refrigerant that is to be drawn in by suction to be able to flow through the suction opening and into the recess before opening and to be able to act on the suction vane, in order to open it, in the region of the recess as well, such that a larger surface area of action on the suction vane is available.

Here, favorably the recess base extends into the suction opening, such that when the suction vane closes the suction opening the recess can sufficiently quickly fill with refrigerant that is to be drawn in by suction, and, for the purpose of opening the suction vane, this refrigerant can act on the suction vane in addition to the refrigerant that is in the suction opening.

Furthermore, detailed statements have not yet been made as regards the depth of the recess.

For example, an advantageous solution provides for the recess, starting from the abutment face of the suction vane, to have a depth that is greater than a thickness of a lubricant film that is formed between the suction vane and the abutment face when the suction opening is sealed off.

This solution has the advantage that it makes it possible to prevent the recess from filling with lubricant when the suction vane closes the suction opening, so that the possibility that refrigerant flows into the recess before the suction vane opens is impeded.

It is particularly favorable if, starting from the abutment face of the suction vane, the depth of the recess is at least 0.2 mm, in particular at least 0.3 mm.

For example, the depth of the recess is at most 40%, in particular at most 50%, of the thickness of the valve plate.

A particularly favorable solution provides for the recess to run at a spacing from the external contour of the abutment face of the suction vane and thus, when the suction opening is closed, for the suction vane also to sealingly close the recess toward the cylinder chamber.

Moreover, it is preferably provided for the recess and the suction opening to be surrounded by a contact face for the suction vane that runs peripherally all the way around them, such that when the suction opening is closed the recess is sealingly closed with the required reliability in order to avoid dead space and to make available a sufficiently large contact surface area for the suction vane.

It is particularly favorable in the context of the solution according to the invention if, on its side facing the suction vane and open toward the abutment face of the suction vane, the recess has a surface area that is at least 10%, preferably at least 20%, even more preferably at least 50% of the cross-sectional surface area of the suction opening.

More detailed statements have not yet been made as regards the course of the recess.

In principle, the recess could run around the suction opening, but this would be unfavorable from the point of view of the space available.

For this reason, it is preferably provided for the recess to extend from the suction opening in the direction of a suction vane foot.

Another advantageous solution provides for the recess to extend from the suction opening in the direction of a suction vane end.

In order to have enough space for the extent of the recess, it is preferably provided for the recess to extend from the suction opening over a region of the valve plate that, on the side with the cylinder head, abuts against a foot region of the cylinder head. As a result, the recess can extend over broad regions of the valve plate even though there is, on the opposite side to the recess, a foot region of the cylinder head that prevents the suction opening itself from being enlarged.

It is even more advantageous if the recess extends from the suction opening over a region of the valve plate that delimits an outlet chamber on the side with the cylinder head.

In order to optimize the supply of refrigerant to the suction opening, it is preferably provided for the cylinder head to be provided with a connector for refrigerant that is to be drawn in.

Preferably here, it is provided for a suction duct to run through the cylinder head from the connector for the refrigerant that is to be compressed as far as the suction opening, and for the duct cross section thereof to correspond to at most twice, even more preferably at most 1.5 times, a cross-sectional surface area of the suction opening in order to guide the refrigerant that is to be drawn in through the cylinder head as quickly as possible and with as little turbulence as possible and hence to achieve quick, reliable opening of the suction vane even at low pressures.

Further, it is preferably provided for a suction duct that leads to a plurality of suction openings to have a cross-sectional surface area that corresponds to at most twice, even more preferably at most 1.5 times, the sum of the cross-sectional surface areas of the plurality of suction openings.

In one embodiment, the suction duct that runs in the cylinder head is shaped within the cylinder head.

A further embodiment provides for the suction duct to be formed in an insert that is inserted into the cylinder head.

Moreover, the invention relates to a valve plate for a reciprocating piston compressor comprising a compressor housing having at least one compressor stage that has at least one cylinder unit, which itself comprises at least one cylinder chamber, wherein the valve plate closes off the cylinder chamber and carries a cylinder head and is provided with at least one suction valve which, for its part, has a suction opening, arranged in the valve plate and closable by a suction vane, and is provided with at least one outlet valve with an outlet opening, wherein the at least one suction valve and the at least one outlet valve are associated with the respective cylinder chamber.

Preferably, the valve plate takes a form such that it has one or more of the features described above.

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

1. A reciprocating piston compressor (54) for refrigerant, comprising a compressor housing (130) having at least one compressor stage (112, 142) that has at least one cylinder unit (114, 144), which itself comprises at least one cylinder chamber (228), wherein a piston (226) is movably arranged in the cylinder unit (114, 144), a cylinder drive (115, 145) that is arranged in the compressor housing (130), for the at least one piston (226), a valve plate (232) that closes off the cylinder chamber (228) and is provided with at least one suction valve (240) which, for its part, has a suction opening (242), arranged in the valve plate (232) and closable by a suction vane (246), and has at least one outlet valve (243) with an outlet opening (244), wherein the at least one suction valve (240) and the at least one outlet valve (243) are associated with the respective cylinder chamber (228), and a cylinder head (192, 194) that is arranged on an opposite side of the valve plate (232) to the cylinder chamber (228), wherein the valve plate (232) has, on its side facing the cylinder chamber (228), a recess (282), which is arranged inside an external contour (262) of an abutment face (256) of the suction vane (246) that is associated with the suction opening (242) and which extends from the suction opening (242) and is open toward this abutment face (256).

2. The reciprocating piston compressor according to embodiment 1, wherein the recess (282) has a recess base (284) that is set back in relation to the abutment face (256) of the suction vane (246).

3. The reciprocating piston compressor according to embodiment 2, wherein the recess base (284) extends into the suction opening (242).

4. The reciprocating piston compressor according to one of the preceding embodiments, wherein the recess (282), starting from the abutment face (256) of the suction vane (246), has a depth that is greater than a thickness of a lubricant film that is formed between the suction vane (246) and the abutment face (256) when the suction opening (242) is sealed off.

5. The reciprocating piston compressor according to one of the preceding embodiments, wherein, starting from the abutment face (256) of the suction vane (246), the depth of the recess (282) is at least 0.2 mm, in particular at least 0.3 mm.

6. The reciprocating piston compressor according to one of the preceding embodiments, wherein, starting from the abutment face (256) of the suction vane (246), the depth of the recess (282) is at most 40%, in particular at most 50%, of the thickness of the valve plate.

7. The reciprocating piston compressor according to one of the preceding embodiments, wherein the recess (282) runs at a spacing from the external contour (262) of the abutment face (256) of the suction vane (246).

8. The reciprocating piston compressor according to one of the preceding embodiments, wherein the recess (282) and the suction opening (242) are surrounded by a contact face (288) for the suction vane (246) that runs peripherally all the way around them.

9. The reciprocating piston compressor according to one of the preceding embodiments, wherein, on its side facing the suction vane (246) and open toward the abutment face of the suction vane (246), the recess (282) has a surface area that is at least 10%, preferably at least 20%, even more preferably at least 50% of a cross-sectional surface area of the suction opening (242).

10. The reciprocating piston compressor according to one of the preceding embodiments, wherein the recess (282) extends from the suction opening (242) in the direction of a suction vane foot (252).

11. The reciprocating piston compressor according to one of the preceding embodiments, wherein the recess (282) extends from the suction opening (242) in the direction of a suction vane end (254).

12. The reciprocating piston compressor according to one of the preceding embodiments, wherein the recess (282) extends from the suction opening (242) over a region of the valve plate that, on the side with the cylinder head (192, 194), abuts against a foot region (272, 274) of the cylinder head (192, 194).

13. The reciprocating piston compressor according to one of the preceding embodiments, wherein the recess (282) extends from the suction opening (242) over a region of the valve plate (292) that delimits an outlet chamber on the side with the cylinder head (192, 194).

14. The reciprocating piston compressor according to one of the preceding embodiments, wherein the cylinder head (192, 194) is provided with a connector (304) for refrigerant that is to be drawn in.

15. The reciprocating piston compressor according to embodiment 14, wherein a suction duct (302, 312, 314) extends through the cylinder head (192, 194) from the connector (304) for the refrigerant that is to be compressed as far as the suction opening (242).

16. The reciprocating piston compressor according to embodiment 15, wherein the suction duct (302, 312, 314) has a duct cross section that corresponds to at most twice, even more preferably at most 1.5 times, a cross-sectional surface area of flow of the suction opening (242).

17. The reciprocating piston compressor according to embodiment 14 to 16, wherein a suction duct (312, 314) that leads to a plurality of suction openings (242) has a cross-sectional surface area of flow that corresponds to at most twice, even more preferably at most 1.5 times, the sum of the cross-sectional surface areas of flow of the suction ducts (312, 314).

18. The reciprocating piston compressor according to one of embodiments 15 to 17, wherein the suction duct (302, 312, 314) is shaped within the cylinder head (192′).

19. The reciprocating piston compressor according to one of embodiments 15 to 17, wherein the suction duct (302, 312, 314) is formed substantially in an insert (316) that is inserted into the cylinder head (192″).

20. A valve plate for a reciprocating piston compressor (54) comprising a compressor housing (130) having at least one compressor stage (112, 142) that has at least one cylinder unit (114, 144), which itself comprises at least one cylinder chamber (228), wherein the valve plate (232) closes off the cylinder chamber (228) and carries a cylinder head (192, 194) and is provided with at least one suction valve (240) which, for its part, has a suction opening (242), arranged in the valve plate (232) and closable by a suction vane (246), and is provided with at least one outlet valve with an outlet opening, wherein the at least one suction valve (240) and the at least one outlet valve (243) are associated with the respective cylinder chamber (228), wherein the valve plate (232) has, on its side facing the cylinder chamber (228), a recess (282), which is arranged inside an external contour (262) of an abutment face (256) of the suction vane (246) that is associated with the suction opening (242) and which extends from the suction opening (242) and is open toward this abutment face (256).

21. The valve plate according to embodiment 20, wherein the valve plate (232) has one or more of the features of embodiments 2 to 13.

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 schematic illustration of a refrigeration unit, in particular taking the form of a transport refrigeration unit, having a refrigeration plant according to the invention;

FIG. 2 shows a schematic illustration of a first exemplary embodiment of a refrigeration circuit according to the invention, having a piston compressor according to the invention;

FIG. 3 shows a cross section in the region of a cylinder chamber of a cylinder of a piston compressor according to the invention, provided with a valve plate and suction valve and a cylinder head;

FIG. 4 shows a plan view, as seen in the direction of the arrow A in FIG. 3, of the valve plate with the suction vanes of the suction valve;

FIG. 5 shows a plan view, corresponding to FIG. 4, of the valve plate without suction vanes;

FIG. 6 shows a plan view similar to FIG. 5, in the case of a second exemplary embodiment of the valve plate;

FIG. 7 shows a plan view similar to FIG. 5, in the case of a third exemplary embodiment of the valve plate;

FIG. 8 shows a cross section through a second exemplary embodiment of a cylinder head of a piston compressor according to the invention; and

FIG. 9 shows a cross section through a third exemplary embodiment of a cylinder head of a piston compressor according to the invention.

 DETAILED DESCRIPTION OF THE INVENTION

A refrigeration unit that is designated 10 as a whole comprises a thermally insulated housing 12 that encloses an interior 14 in which temperature-sensitive goods 16 or temperature-sensitive freight 16 can be stored, wherein the temperature-sensitive goods 16 or temperature-sensitive freight 16 is surrounded by a gaseous medium 18, in particular air, which is kept at a defined temperature level in order to keep the temperature-sensitive freight 16 or temperature-sensitive goods 16 within a particular temperature range.

The refrigeration unit 10 preferably takes the form of a transportable refrigeration unit, for example as a superstructure for a truck or a freight car or as a conventional transport container for transporting temperature-sensitive freight 16, either by truck or by rail or sea.

So that a defined or predetermined temperature range for the freight 16 can be maintained, a circulation stream 22 of the gaseous medium 18 runs within the interior 14, wherein, starting from a temperature-control unit 24, an incoming stream 26 enters the interior 14, flows through this and enters the temperature-control unit 24 again as an outgoing stream 28.

In this context, the circulation stream 22 is generated by a fan unit 32 that is arranged in the temperature-control unit 24 and is kept at the desired temperature by an internal heat exchanger 34 arranged in the temperature-control unit 24.

Preferably here, the incoming stream 26 exits from the temperature-control unit 24 in a region close to a top wall 36 of the insulated housing 12, and the circulation stream 22 is preferably returned to the temperature-control unit 24 close to a bottom wall 38 of the insulated housing 12 and in so doing forms the outgoing stream 28 that flows back to the temperature-control unit 24.

In particular, the temperature-control unit 24 is arranged close to the top wall 36 of the insulated housing 12, and for example close to a front wall 48 or close to a back wall 48 thereof.

An assembly unit 52 comprising a refrigerant compressor unit 54 with a refrigerant compressor 56 and an electric drive motor 58 is arranged on the thermally insulated housing 12, preferably close to the temperature-control unit 24, wherein the assembly unit 52 preferably additionally comprises a first external heat exchanger 62 and an external fan unit 64 that generates for example an air stream 66 from ambient air, which passes through the first external heat exchanger 62.

As illustrated in FIG. 2, the refrigerant compressor unit 54, the internal heat exchanger 34 and the first external heat exchanger 62 are arranged in a refrigeration circuit, designated 70 as a whole, of a refrigeration plant 60 that is integrated into the refrigeration unit.

The refrigeration circuit 70 is connected to a high-pressure connector 72 of the refrigerant compressor unit 54, in particular taking the form of a reciprocating piston compressor, from which a supply conduit 74 leads to the first external heat exchanger 62, which cools an overall mass flow G of refrigerant, in the present case in particular CO2, that has been compressed to high pressure PH by the refrigerant compressor 54, wherein in the case of CO2 the refrigerant is in a transcritical state.

Here, in the first external heat exchanger unit 62 on the high-pressure side, the refrigerant may be cooled either by ambient air or indeed also by contact with a heat-absorbing medium of any kind, for example also cooling water.

Downstream of the external heat exchanger 62, the overall mass flow G that is supplied at the high-pressure connector 72 of the refrigerant compressor unit 54 in the refrigeration circuit 70 flows, in the case of CO2 in a transcritical state, through an expansion member 76 that is arranged in the refrigeration circuit 70 is expanded by this to an intermediate pressure PZ and then enters an intermediate-pressure collector 82 in which the overall mass flow G, cooled as a result of expansion, is divided into a main mass flow H comprising liquid refrigerant, which is deposited in the intermediate-pressure collector 82 as a liquid refrigerant bath 84, and an additional mass flow Z, which forms a gas bubble 86 above the liquid bath 84.

The main mass flow H comprising liquid refrigerant is supplied from the intermediate-pressure collector 82 to a cooling stage 92, which has a cooling expansion member 94 that cools the main mass flow H as a result of expansion to low pressure PN, and from which the main mass flow H enters the internal heat exchanger 34 on the low-pressure side, in which it is able to take heat from the circulation stream 22 in the interior 18 of the refrigeration unit 10 as a result of making refrigeration capacity available.

The main mass flow H that is heated in the heat exchanger 34 then enters the refrigerant compressor unit 54 at low pressure PN, by way of a low-pressure connector 102.

As illustrated in FIG. 2, the refrigerant compressor 56 of the refrigerant compressor unit 54 takes the form of a reciprocating piston compressor, and preferably comprises a first compressor stage 112, formed by two cylinder units 114a and 114b which are respectively driven by a cylinder drive 115a, 115b, in particular an eccentric drive, and of which each draws in the refrigerant of the main mass flow H by suction from a suction chamber 116a, 116b and discharges it for example to a common outlet chamber 118. During this, the first compressor stage 112 compresses the refrigerant from the main mass flow H that is supplied thereto at low pressure, for example at values of from 0.1 bar to 60 bar, to a medium pressure PM, of which for example the values lie in the range of from 20 bar to 120 bar.

Then, the main mass flow H that has been compressed to medium pressure PM is supplied from a medium-pressure outlet 122 of the common outlet chamber 118 to a second external heat exchanger 124 on the medium-pressure side, which is for example likewise arranged in the assembly unit 52 and through which for example the external air stream 66 likewise flows.

As a result of the second external heat exchanger 124 on the medium-pressure side, it is possible to cool the refrigerant of the main mass flow H that has been compressed to medium pressure PM back to a temperature close to ambient temperature, and to take from it again a substantial proportion of the heat supplied during compression.

From the second external heat exchanger 124 on the medium-pressure side, the refrigerant of the main mass flow H that has been cooled and compressed to medium pressure PM is supplied by way of a medium-pressure supply conduit 126 to a medium-pressure inlet 128 of an overall housing 130 of the refrigerant compressor unit 54, wherein the medium-pressure inlet 128 is arranged in particular in a motor housing 132 of the overall housing 130 of the refrigerant compressor unit 54.

Moreover, the medium-pressure supply conduit 126 is also connected to the gas bubble 86 of the intermediate-pressure collector 82, with the result that the additional mass flow Z is likewise supplied to the medium-pressure connector 128 of the refrigerant compressor unit 54 from the intermediate-pressure collector 82 by way of the medium-pressure supply conduit 126, and the medium pressure PM is for example set to correspond to the intermediate pressure PZ.

The medium-pressure inlet 128 is preferably arranged in the motor housing 132 such that the incoming refrigerant enters a motor compartment 134, passes through the motor compartment 134 in a manner cooling the electric drive motor 58, in particular cooling a rotor 136 and a stator 138 thereof, and then, guided through the overall housing 130, enters a second compressor stage 142 of the refrigerant compressor unit 54.

The second compressor stage 142 likewise comprises two cylinder units 144a and 144b which are respectively driven by a cylinder drive 145a, 145b, in particular an eccentric drive, wherein the refrigerant that has been compressed to medium pressure PM and supplied to the second compressor stage 142 enters the cylinder units 144a and 144b for example by way of inlet chambers 146a and 146b, is compressed in these cylinder units 144a and 144b and then exits to an outlet chamber 148 that is connected to the high-pressure connector 72.

In the first exemplary embodiment of the reciprocating piston compressor 54 according to the invention, the cylinder units 114a and 114b of the first compressor stage 112 and the cylinder units 144a and 144b of the second compressor stage 142 are driven by way of a common drive shaft 152, in particular an eccentric shaft, which acts on the respective cylinder drives 115a, 115b and 145a, 145b and is preferably connected coaxially and in particular in one piece with a rotor shaft 154 of the rotor 136, and forms an overall drive shaft 188 therewith.

Further, in the first exemplary embodiment of the refrigerant compressor unit 54, the cylinder drive compartment 156, which receives the drive shaft 152 and the cylinder drives 115a, 115b, 145a, 145b and adjoins each of the cylinder units 114a and 114b or 144a and 144b, is connected within the overall housing 130 to the motor compartment 134 or merges into this, with the result that the cylinder drive compartment 156 is at medium pressure.

This has the advantage that as a result, in particular in the case of the second compressor stage 142, only pressure differences between medium pressure and high pressure occur in the cylinder units 144a and 144b, and thus the load on the cylinder drives 145a and 145b for the cylinder units 144a, 144b is smaller than if there were low pressure in the cylinder drive compartment 156.

Similarly, the load on the cylinder units 144a and 144b themselves, in particular the pistons thereof, is also smaller than if there were low pressure in the cylinder drive compartment 156.

As illustrated in FIG. 2, in the first exemplary embodiment of the refrigerant compressor unit 54 according to the invention, it takes the form of a semi-hermetic compressor, in which the refrigerant compressor 56 and the electric drive motor 58 are arranged in the overall housing 130, which comprises a housing sleeve 162, bearing covers 164 and 166 that are arranged on either side of the housing sleeve 162, and bearing receptacles 174 and 176 that are integrally formed on the bearing covers 164 and 166 and are made for example from aluminum, wherein arranged in the bearing receptacles 174 and 176 are roller bearings 184 and 186, which in this case form the mounting for an overall drive shaft 188 comprising the drive shaft 152 and the rotor shaft 154.

Further, respectively arranged on the housing sleeve 162 are cylinder heads 192 and 194, which are likewise made for example from aluminum, wherein the cylinder head 192 is associated with the cylinder units 114a and 114b and has the low-pressure connector 102 that is connected to the inlet chambers 116a and 116b, and has the outlet chamber 118 that is connected to the medium-pressure outlet 122.

The cylinder head 194 is associated with the cylinder units 144a and 144b, wherein the inlet chambers 146a and 146b are connected to the motor compartment 134 and/or the cylinder drive compartment 156, and the outlet chamber 148 is connected to the high-pressure connector 72.

For the purpose of controlling the electric drive motor 58, there is provided in particular a converter 212, which is preferably likewise arranged in the assembly unit 52.

With this converter, the electric drive motor 58 is operable with speed control, and thus the refrigeration capacity of the refrigerant compressor unit 54 is also continuously variably controllable within a provided capacity range.

As illustrated in FIG. 3, each of the cylinder units 114 has a cylinder 224, which is provided in a cylinder block 222, for example formed by the overall housing 130, and in which a piston 226 is movable, wherein the piston delimits a cylinder chamber 228 lying between the piston 226 and a valve plate 232 that closes off the respective cylinder 224, wherein the valve plate is sealed off in relation to the cylinder block 222, for example by way of a gasket 234.

For the purpose of drawing the refrigerant in by suction, the valve plate 232 is provided with a suction valve 240 that a suction opening 242a having a suction vane 246a associated therewith and moreover an outlet valve 243 with an outlet opening 244 and an outlet vane (not illustrated).

In this case, the suction opening 242 is configured to be sealed off by the suction vane 246, which is arranged on the valve plate 232 on a side facing the cylinder chamber 228 and, in the region of a suction vane foot 252, is fixedly connected to the valve plate 232 and then extends from the suction vane foot 252 beyond the suction opening 242 as far as a suction vane end 254a, and in so doing, in its position that closes the suction opening 242 and is illustrated in FIG. 3, extends beyond the suction opening 242 and abuts against an abutment face 256a of the valve plate 232 for the purpose of sealing off the suction opening 242.

In the simplest case, the abutment face 256 here is formed by a subregion of the side 258 of the valve plate that faces the cylinder chamber 228 and engages over the cylinder chamber 228.

In this case, the abutment face 256 is delimited on the side 258 of the valve plate 232 by an external contour of the respective suction vane 246, and by the suction opening 242.

In the exemplary embodiment illustrated in FIG. 4, two suction vanes 246a and 246b are provided, which serve to close two suction openings 242a and 242b that lead into the cylinder chamber 228, wherein for example the two suction vane feet 252a and 252b are additionally connected to one another, while the suction vane ends 254a and 254b are movable in relation to one another.

Moreover, for each of the suction vanes 254a and 254b, the suction vane end 254a, b, as illustrated for example in FIG. 3 in the context of the suction vane end 254a, is arranged in a recess 264 that forms an abutment face 266 in order to limit movement of the respective suction vane, in this case the suction vane 246a, as it uncovers the respective suction opening, for example the suction opening 242a.

As illustrated in FIG. 4, two suction openings 242a and 242b are provided for the respective cylinder 224 in order to make available the largest possible inflow cross section.

Moreover, for example three outlet openings 244 are provided in order also to make available an optimal outlet cross section for the pressurized refrigerant.

As illustrated in FIG. 4, moreover the spatial conditions for providing a sufficient cross section for the suction openings 242 and the outlet openings 244, all of which have to lie inside the external contour of the respective cylinder chamber 228, are limited.

Furthermore, as is also clear from FIG. 4, the spatial possibilities for making the suction openings 242 larger are also limited by the fact that there is provided in the respective cylinder head, for example the cylinder head 192, a separating wall 272 for separating for example the suction chamber 116a from the outlet chamber 118, and this separating wall 272 necessarily extends as far as the valve plate 232 and is sealed in relation to the valve plate 232 by a gasket 274 for sealing off the entire cylinder head 192.

In order to increase the efficiency of the reciprocating piston compressor, in particular by opening the respective suction vane 246 as quickly as possible as the drawing in of refrigerant by suction through the respective suction opening 242 begins, in a first embodiment there is provided a recess 282, for example the recess 282a or the recess 282b in FIG. 4, adjoining the respective suction opening 242, and these lie inside the respective external contour 262 of the corresponding suction vane 246a, b and extend from the respective abutment face 256a and 256b of the respective suction vane 246a and 246b as far as a recess base 284 that runs opposite the corresponding abutment face 256a and 256b in the valve plate 232, at a depth that is greater than the thickness of a lubricant film that is formed by the lubricant in the reciprocating piston compressor, such that when the suction vane 246a, b is closed the respective recess 282a, b cannot be closed, entirely or in part, by a lubricant film, but rather when the suction vane 246a, b is closed the lubricant under suction pressure flows into the recess 282 from the respective suction opening 242, and thus, at the negative pressure prevailing in the cylinder chamber 228, the respective suction vane 246a, b is acted on by suction pressure over a larger surface area than would be the case if the suction vane 246a, b were only acted on in the region of the suction opening 242.

Preferably in this case, in the abutment face 256a, b of the respective suction vane 246a, b the recess 282a, b has an external contour 286 that surrounds at least 20% of a cross-sectional surface area of the suction opening 242a, b, such that as a result the force on the respective suction vane 246a, b is significantly increased as it is lifted away from the respective abutment face 256a, b, and thus opening of the suction vane 246a, b can be performed more quickly during the procedure of drawing in by suction.

In order to achieve secure sealing between the respective suction vane 246a, 246b and the abutment face 256a, 256b, it is preferably provided for the respective suction opening 242a, 242b and the associated recess 282a, 282b to be together surrounded by a contact face 288a and 288b that runs peripherally all the way around them and is part of the abutment face 256a, 256b, and thus, when the suction opening 242a or 242b is closed by the respective suction vane 246a and 246b respectively, ensures proper and reliable sealing between the respective suction vane 246a and 246b and the corresponding abutment face 256a and 256b, and moreover also ensures that the respective suction vane 246a or 246b has a sufficiently large flat contact surface area 256a and 256b to avoid damage to the respective suction vane 246a or 246b.

In the exemplary embodiment of the valve plate 232 that is illustrated in FIGS. 4 and 5, the respective recess 282a and 282b extends in the direction of the respective suction vane foot 252a, b, in particular—as described—over the region of the side 258 of the valve plate 232 facing the cylinder chamber 228, against the opposite side of which the separating wall 272 of the cylinder head 192 is supported.

As an alternative to the form taken by the recesses 282a, 282b in the first exemplary embodiment, in a second exemplary embodiment, which is illustrated in FIG. 6, there is the possibility of providing recesses 292a and 294a and 292b and 294b, wherein the recesses 292a and 292b extend, in the same manner as the recesses 282a and 282b, in the direction of the respective suction vane foot 252a and 252b, while the recesses 294a and 294b extend from the respective suction opening 242a and 242b in the direction of the respective suction vane end 254a and 254b.

Thus, an enlargement of the surface area by means of which the refrigerant that is to be drawn in by suction acts on the respective suction vane 246a and 246b to move it away from the corresponding abutment face 256a, 256b is is achievable on either side of the respective suction opening 242a and 242b.

In a third exemplary embodiment, illustrated in FIG. 7, starting from the suction openings 242a and 242b there are provided recesses 296a and 296b that extend from the respective suction opening 242a and 242b over a distance in the direction of the respective suction vane foot 252a and 252b that is greater than a diameter of the respective suction opening 242a and 242b, for example even having an extent in the direction of the respective suction vane foot 252a and 252b that is greater than twice a diameter of the suction opening, wherein the recesses 296a and 296b each lie within the abutment face 256 and are moreover likewise surrounded by a respective contact face 288a and 288b that runs peripherally all the way around them in order to achieve a sufficiently large sealing surface area to seal off the suction opening 242a and 242b and the recess 296a and 296b in relation to the cylinder chamber 228.

In particular, in this solution the recesses 296a and 296b extend into a region of the side 258 of the valve plate 232 facing the cylinder chamber 228, on the opposite side of which lies the outlet chamber 118 in the cylinder head 196.

In a modification of the cylinder head of the first exemplary embodiment, illustrated in FIG. 8, the cylinder head 192′ is modified such that instead of the inlet chambers 116a and 116b there is provided a suction duct 302, which extends from an outer suction end 304 provided on the cylinder head 192 to the suction opening 242 as directly as possible, with the result that a low-turbulence, if not turbulence-free flow guidance that promotes advantageous low-turbulence, preferably turbulence-free flow of the refrigerant from the outer connector 304 to the suction opening 242 is produced for the refrigerant that is to be drawn in by suction from the outer suction connector 304 to the respective suction opening 242, and heating thereof in the cylinder head 192 is reduced.

In this exemplary embodiment, the suction duct 302 is for example shaped within the cylinder head 192′.

Preferably, the inlet duct 302 has a cross-sectional surface area of flow that corresponds at least to a cross-sectional surface area of flow of the respective suction opening 242 and is at most twice, even more preferably 1.5 times, the cross-sectional surface area of flow of the suction opening 242.

In a third exemplary embodiment of a refrigerant compressor according to the invention, illustrated in FIG. 9, there is provided on the cylinder head 192″ an outer connector 306 from which two suction ducts 312 and 314 branch off, each of which leads to a suction opening 242 for different cylinders 224.

In this exemplary embodiment, the suction ducts 312 and 314 are for example at least substantially shaped within an insert 316 that is inserted into the cylinder head 192″.

Here, it is preferably provided for a cross-sectional surface area of flow of the outer connector 306 to correspond at least to the cross-sectional surface area of flow into the suction ducts 312 and 314, in order to achieve flow through the cylinder head 192″ that is as low in turbulence as possible, preferably being turbulence-free, with as little heating as possible of the refrigerant that is drawn in by suction.

Preferably, the cross-sectional surface area of flow of the outer connector 306 is at most twice, even more preferably at most 1.5 times, the sum of the cross-sectional surface areas of flow of the suction ducts 312, 314.

All the features that are described in conjunction with the cylinder head 192 and the valve plate 232 cooperating therewith are likewise applicable in the cylinder head 194 and the valve plate 232 connected thereto.

Claims

1. A reciprocating piston compressor for refrigerant, comprising a compressor housing having at least one compressor stage that has at least one cylinder unit, which itself comprises at least one cylinder chamber, wherein a piston is movably arranged in the cylinder unit, a cylinder drive that is arranged in the compressor housing, for the at least one piston, a valve plate that closes off the cylinder chamber and is provided with at least one suction valve which, for its part, has a suction opening, arranged in the valve plate and closable by a suction vane, and has at least one outlet valve with an outlet opening, wherein the at least one suction valve and the at least one outlet valve are associated with the respective cylinder chamber, and a cylinder head that is arranged on an opposite side of the valve plate to the cylinder chamber, the valve plate has, on its side facing the cylinder chamber, a recess, which is arranged inside an external contour (262) of an abutment face (256) of the suction vane (246) that is associated with the suction opening (242) and which extends from the suction opening (242) and is open toward this abutment face (256).

2. The reciprocating piston compressor as claimed in claim 1, wherein the recess has a recess base that is set back in relation to the abutment face of the suction vane.

3. The reciprocating piston compressor as claimed in claim 2, wherein the recess base extends into the suction opening.

4. The reciprocating piston compressor as claimed in claim 1, wherein the recess, starting from the abutment face of the suction vane, has a depth that is greater than a thickness of a lubricant film that is formed between the suction vane and the abutment face when the suction opening is sealed off.

5. The reciprocating piston compressor as claimed in claim 1, wherein, starting from the abutment face of the suction vane, the depth of the recess is at least 0.2 mm, in particular at least 0.3 mm.

6. The reciprocating piston compressor as claimed in claim 1, wherein, starting from the abutment face of the suction vane, the depth of the recess is at most 40%, in particular at most 50%, of the thickness of the valve plate.

7. The reciprocating piston compressor as claimed in claim 1, wherein the recess runs at a spacing from the external contour of the abutment face of the suction vane.

8. The reciprocating piston compressor as claimed in claim 1, wherein the recess and the suction opening are surrounded by a contact face for the suction vane that runs peripherally all the way around them.

9. The reciprocating piston compressor as claimed in claim 1, wherein, on its side facing the suction vane and open toward the abutment face of the suction vane, the recess has a surface area that is at least 10%, preferably at least 20%, even more preferably at least 50% of a cross-sectional surface area of the suction opening.

10. The reciprocating piston compressor as claimed in claim 1, wherein the recess extends from the suction opening in the direction of a suction vane foot.

11. The reciprocating piston compressor as claimed in claim 1, wherein the recess extends from the suction opening in the direction of a suction vane end.

12. The reciprocating piston compressor as claimed in claim 1, wherein the recess extends from the suction opening over a region of the valve plate that, on the side with the cylinder head, abuts against a foot region of the cylinder head.

13. The reciprocating piston compressor as claimed in claim 1, wherein the recess extends from the suction opening over a region of the valve plate that delimits an outlet chamber on the side with the cylinder head.

14. The reciprocating piston compressor as claimed in claim 1, wherein the cylinder head is provided with a connector for refrigerant that is to be drawn in.

15. The reciprocating piston compressor as claimed in claim 14, wherein a suction duct extends through the cylinder head from the connector for the refrigerant that is to be compressed as far as the suction opening.

16. The reciprocating piston compressor as claimed in claim 15, wherein the suction duct has a duct cross section that corresponds to at most twice, even more preferably at most 1.5 times, a cross-sectional surface area of flow of the suction opening.

17. The reciprocating piston compressor as claimed in claim 14, wherein a suction duct that leads to a plurality of suction openings has a cross-sectional surface area of flow that corresponds to at most twice, even more preferably at most 1.5 times, the sum of the cross-sectional surface areas of flow of the suction ducts.

18. The reciprocating piston compressor as claimed in claim 15, wherein the suction duct is shaped within the cylinder head.

19. The reciprocating piston compressor as claimed in claim 15, wherein the suction duct is formed substantially in an insert that is inserted into the cylinder head.

20. A valve plate for a reciprocating piston compressor comprising a compressor housing having at least one compressor stage that has at least one cylinder unit, which itself comprises at least one cylinder chamber, wherein the valve plate closes off the cylinder chamber and carries a cylinder head and is provided with at least one suction valve which, for its part, has a suction opening, arranged in the valve plate and closable by a suction vane, and is provided with at least one outlet valve with an outlet opening, wherein the at least one suction valve and the at least one outlet valve are associated with the respective cylinder chamber, the valve plate has, on its side facing the cylinder chamber, a recess, which is arranged inside an external contour of an abutment face of the suction vane that is associated with the suction opening and which extends from the suction opening and is open toward this abutment face.

21. The valve plate as claimed in claim 20, wherein the recess has a recess base that is set back in relation to the abutment face of the suction vane.

22. The valve plate as claimed in claim 21, wherein the recess base extends into the suction opening.

23. The valve plate as claimed in claim 20, wherein the recess, starting from the abutment face of the suction vane, has a depth that is greater than a thickness of a lubricant film that is formed between the suction vane and the abutment face when the suction opening is sealed off.

24. The valve plate as claimed in claim 20, wherein, starting from the abutment face of the suction vane, the depth of the recess is at least 0.2 mm, in particular at least 0.3 mm.

25. The valve plate as claimed in claim 20, wherein, starting from the abutment face of the suction vane, the depth of the recess is at most 40%, in particular at most 50%, of the thickness of the valve plate.

26. The valve plate as claimed in claim 20, wherein the recess runs at a spacing from the external contour of the abutment face of the suction vane.

27. The valve plate as claimed in claim 20, wherein the recess and the suction opening are surrounded by a contact face for the suction vane that runs peripherally all the way around them.

28. The valve plate as claimed in claim 20, wherein, on its side facing the suction vane and open toward the abutment face of the suction vane, the recess has a surface area that is at least 10%, preferably at least 20%, even more preferably at least 50% of a cross-sectional surface area of the suction opening.

29. The valve plate as claimed in claim 20, wherein the recess extends from the suction opening in the direction of a suction vane foot.

30. The valve plate as claimed in claim 20, wherein the recess extends from the suction opening in the direction of a suction vane end.

31. The valve plate as claimed in claim 20, wherein the recess extends from the suction opening over a region of the valve plate that, on the side with the cylinder head, abuts against a foot region of the cylinder head.

32. The valve plate as claimed in claim 20, wherein the recess extends from the suction opening over a region of the valve plate that delimits an outlet chamber on the side with the cylinder head.

Patent History
Publication number: 20230341156
Type: Application
Filed: Apr 21, 2023
Publication Date: Oct 26, 2023
Applicant: BITZER Kuehlmaschinenbau GmbH (Sindelfingen)
Inventor: Andreas Becker (Halle)
Application Number: 18/304,419
Classifications
International Classification: F25B 31/02 (20060101); F04B 39/10 (20060101);