US20150219084A1

US20150219084A1 - Compressor

Info

Publication number: US20150219084A1
Application number: US14/422,085
Authority: US
Inventors: Markus Besemer; Christian Etter; Martin Schaich
Original assignee: GEA Bock GmbH
Current assignee: Bock GmbH
Priority date: 2012-08-17
Filing date: 2013-08-17
Publication date: 2015-08-06
Also published as: CN104903577A; WO2014026769A1; DE102012016265A1; WO2014026769A9; EP2885540A1

Abstract

A compressor for compressing a refrigerant comprising a cylinder block, a cylinder cover (12) and a valve plate (10) which is interposed between the cylinder block and the cylinder cover (12), said valve plate (10) being connected to the cylinder cover (12) and/or to the cylinder block without redundancy in the sealing plane.

Description

The present invention relates to a compressor, in particular a compressor for compressing refrigerant according to the preamble of claim 1.
Refrigeration technology is an increasingly strong industrial sector not least because of the increasing global application of technology. Due to rising energy costs, increasing attention is being focused on the most efficient use of the energy that corresponding refrigerating machines, compressors, air conditioning systems, etc. consume.
For example, with cooling in supermarkets, industrial and marine applications, or even in the mobile air-conditioning and refrigeration, reciprocating piston compressors play an important role. Reciprocating piston compressors in refrigeration technology usually have intrinsic medium activated valves, which are arranged on a valve plate. The valve plate itself is arranged between a cylinder block and a cylinder cover, and separates the compression volumes, (cylinder chambers, cylinder bores) which are interposed in the cylinder block, from a suction gas volume and a pressure gas volume, which are both disposed in the cylinder cover. Here, the valve plate is usually pressed together with the cylinder cover with pretension against the cylinder block, using fastening screws. The leak tightness is produced here using flat seals on both existing sealing planes.
To connect the suction volume and the pressure volume to the compression volumes, in order to allow an inlet, or respectively a suction, of refrigerant under low pressure, and a discharge of refrigerant under high pressure, the valve plate has, as suggested by the name, appropriate valves, which in each case allow a suction and a discharge of refrigerant at the desired time. In addition to reed valves, ring valves can also be used.
Due to high mechanical loads and also high pressure loads that act on the valve plate, the size of the valve openings, and thus the thickness of webs or the like which are arranged between the respective openings, is determined by the prevailing forces and pressures, i.e. the loads acting on the valve plate. Since the loads in extreme operating conditions are relatively high, and in practice, the medium to be compressed, in addition to the gaseous state, can in rare cases take on the liquid state, the openings are separated by solid supports, which is disadvantageous from an energy viewpoint, since the flow resistance is greater.
Based on prior art discussed above, the object of the present invention is therefore to specify a compressor, in particular a compressor for compressing refrigerant, which in comparison to the compressors of the prior art, enables an energetically favorable and therefore efficient operation.
This object is solved according to the invention by a compressor according to claim 1.
According to the invention an appropriate compressor for compressing refrigerant has a cylinder block, a cylinder cover and a valve plate which is interposed between the cylinder block and the cylinder cover. The valve plate is connected in the compressor to the cylinder cover and/or to the cylinder block. The construction thereby obtains suitable stability, which allows an enlarged valve opening in comparison to the prior art. The larger the valve opening, or valve openings, of a compressor can be designed, the greater the refrigerant flow rate of the unit can be realized or selected.
In one possible embodiment, outside of the cylinder bore, the valve plate is pressed together with the cylinder cover against the cylinder block using fastening elements, for example fastening screws. In addition, the valve plate—for example, in the central region of the cylinder bores—is pressed to the cylinder cover by fastening elements, which again can be present in the form of fastening screws. The seal in this region, with this connection, lies on, or respectively in, the same plane as the seal in the region outside of the valve nests (central region of the cylinder bores). The seal can thus be made using the same flat seal in both regions.
Preferably, the connection is made by means of a screw and a thread corresponding thereto, which is arranged in the valve plate. This represents a reliable solution.
In a preferred embodiment, the connection is effected in the region of the pressure unit, or respectively the so-called pressure nest, i.e. the pressure nest (or respectively the pressure unit) is connected to the cylinder cover. The pressure unit, or respectively the pressure nest, extends here over the region of the valve plate between the intersection of the extended central axis of a cylinder bore (central axis of the bore in the direction of extension thereof, the central axis in the axial direction of each bore) with the valve plate to the openings in the valve plate, which are provided for discharging the compressed refrigerant. Optionally for this purpose, a support element, in particular a somewhat column-like support element, which extends from an outer wall of the cylinder cover in the direction of the valve plate, is arranged in the suction volume or in the pressure volume. This support element can have a recess for the guiding through the connection element, for example the screw, by means of which the connection occurs, preferably in the center in the direction of extension thereof from an outer wall of the cylinder cover up to the valve plate. Alternatively, it is also conceivable to provide the support element itself as a connecting element, and to fasten it to the valve plate, for example by means of a bonding, soldering or welding process.
Further features of the invention are specified in the dependent claims.
The invention is explained in the following with reference to the accompanying drawings based on example embodiments of the invention. The drawings show in:
FIG. 1 a valve plate of a compressor according to the prior art for general explanation;
FIG. 2 a perspective sectional view of a cylinder cover and a valve plate of a compressor according to the invention;
FIG. 3 a section from FIG. 2 in a top view of the sectional plane;
FIG. 4 the valve plate according to FIG. 3;
FIG. 5 a valve plate of a compressor according to the invention including the seal in a top view (the side facing the cylinder block);
FIG. 6 the valve plate of the compressor according to the invention according to FIG. 5 including the seal in a top view (the side facing the cylinder cover);
FIG. 7 the valve plate according to FIG. 6, but without the seal.
FIG. 1 shows a valve plate 110 of a compressor according to the prior art, for general explanation. A region A corresponds approximately to a diameter of a cylinder (not shown), which is covered by the corresponding part of the valve plate 110 and is delimited by a cylinder cover (not shown). First surfaces 112 represent the pressure cross-sections, whereas second surfaces 114 represent the suction cross-sections. The figures clearly show that the theoretically possible maximum cross-sections are sharply reduced by webs 116, 118, which are essential for the stability of the valve plate 110.
In contrast to this, the FIGS. 2 to 7 show parts of a compressor according to the invention. The FIGS. 2 to 4 are each sectional representations of a valve plate 10 shown in the FIGS. 2 and 3 together with a cylinder cover 12 of a compressor according to the invention, whereas the FIGS. 5 to 7 each show top views of valve plates 10 of a compressor according to the invention. The cylinder cover has recesses in which screws 14 are arranged, with which the cylinder cover 12 is fastened to a cylinder block (not shown) of the compressor.
The cylinder cover 12 has, for each provided cylinder, a suction volume, or respectively a suction chamber 16 (recess in the cylinder cover 12), from which the refrigerant is suctioned into the cylinder of the compressor, and a pressure volume 18 (also a recess in the cylinder cover 12), wherein the respective suction volume 16 is arranged in a ring-shape around the corresponding pressure volume 18.
The valve plate 10 has a suction disk or suction lamella 20, respectively and a pressure disk or pressure lamella 22, respectively, which close or release a respective suction opening 24 and a pressure opening 26 in the valve plate, for the gas exchange between the cylinder and the respective suction volume 16 and the respective pressure volume 18.
The suction disk 20, which in a closed state, i.e. in a state in which it lies on the valve plate 10, separates the suction volume 16 and the corresponding cylinder chamber (compression volume) from each other, releases the respective suction opening 24 by an appropriate lifting-off from the valve plate 10, and allows an inflow of the medium to be compressed (suction gas, here in the form of refrigerant) into the compression volume. The lifting-off of the suction disk 20 from the valve plate 10 is caused by a low pressure predominating in the compression volume in the suction cycle. In doing so, the suction disk 20 moves away from the valve plate 10 in the direction of the compression volume. The suction disk 20 is formed circularly and has a suction disk outer diameter d1 and a suction disk inner diameter d2.
The pressure disk 22, which in a closed state, i.e. in a state in which it lies on the valve plate 10, separates the pressure volume 18 and the corresponding cylinder chamber (compression volume) from each other, releases the respective pressure opening 26 by an appropriate lifting-off from the valve plate 10, and allows an outflow of the compressed, medium under high pressure (compressed gas) into the pressure volume 18. The lifting-off of the pressure disk 22 from the valve plate 10 is caused by a high pressure in the compression volume generated during compression. In doing so, the pressure disk 22 moves away from the valve plate 10 in the direction of the cylinder cover. The pressure disk 22, like the suction disk 20, is formed circularly, and has a pressure disk outer diameter d3 and a pressure disk inner diameter d4. In the present embodiment: d4<d3<d2<d1.
The pressure disk 22 is pressed against the pressure opening 26 due to the effect of an elastic element in the form of a sine spring 28, and the lifting-off of the pressure disk 22 is limited by a lift catch 30. The lift catch 30 is annular in shape, and is arranged on the valve plate 10 secured against rotation by means of a lock against rotation in the form of a pin 32. The lift catch is approximately circular in shape, or respectively circularly ring-shaped, and an outer diameter of the lift catch 30 corresponds approximately to the outer diameter d3 of the pressure disk 22.
The suction disk 20 (for this, particularly see FIG. 5) comprises at two locations of the circular ring suction disk extensions 34, 36 directed outwardly, approximately rectangular in shape, that are formed at an angle of 180°, or respectively opposite to each other, on the suction disk 20. As the suction disk 20 itself, the suction disk extensions 34, 36 are also formed plate-shaped corresponding to the plate-shaped formation of the suction disk 20. The suction disk extensions 34, 36 are formed integrally with the suction disk 20 and of a single material. Alternatively, the suction disk extensions can also be produced from another material and/or can be attached on the suction disk 20 by means of a suitable fastening method (for example bonding, soldering or welding). The suction disk extensions 34, 36 each have recesses in the shape of elongated holes 38, 40 (guides), in which a guide pin 42, 44, arranged in the valve plate, engages. When the suction disk 20 during suctioning of the suction gas is drawn into the compression volume and thus lifted-off from the suction opening 24, the suction disk extensions 34, 36 move guided by the guide pins 42, 44 in the direction of the pressure disks (or simply: they move inwards) and limit the lifting-off of the suction disk 20, when the guide pins lie at the outer ends (outer diameter) of the elongated holes 38, 40.
It can be seen particularly in FIGS. 2 to 4 that in the cylinder cover 12, not only screws 14 are provided for connection to the cylinder block, but also that for each cylinder a connection element in the form of a screw 46 is provided for connecting to the valve plate 10. The screws 46 each engage in each case in corresponding threads 48 formed in the valve plate 10, and provide a connection of the cylinder cover 12 with the valve plate 10. In an alternative embodiment, it can be conceivable that the valve plate 10 is connected alternatively or additionally for this purpose to the cylinder block, preferably again by screwing. Alternatives to a screwing as a connection, or respectively a screw as a connecting element, could be other connection methods, for example soldering, bonding or welding.
For optimizing the connection and support properties, an approximately column-shaped support element 50, which extends from an outer wall 52 of the cylinder cover 12 in the direction of the valve plate 10, is arranged in the pressure volume 18. The support element 50 is formed column-shaped with a recess 54 in the center along the center axis or is formed as a hollow cylinder, wherein the outer diameter of the support element 50 in the region of the outer wall 52 of the cylinder cover 12 is slightly larger (by approximately 2% to 7%) than in the region of the valve plate 10. The recess 54 extends from the outer wall of the cylinder cover 12 in the direction of the valve plate 10, and is provided for accommodating the connecting element (screw 46).
The connection between the cylinder cover 12 and the valve plate 10 using the screw 46 and the support element 50, is effected for each cylinder of the compressor in the described embodiment preferably in the region of the pressure unit, or respectively the so-called pressure nest 56, i.e. the pressure unit, or respectively the pressure nest 56, is connected to the cylinder cover 12. The pressure nest, or respectively the pressure unit 56 of the valve plate 10, extends over the region of the valve plate 10 between the intersection of the (extended) center axis of a cylinder bore (center axis of the bore in the extension direction thereof, center axis in the axial direction of the respective bore) with the valve plate and the pressure openings 26, which are provided for discharging the compressed refrigerant.
The lift catch 30, which determines the lifting height and radial position of the pressure disk 22, is recessed axially in comparison to fitting at the valve plate 10. The arising gap is necessary in order not to generate any redundancy, and to ensure that the tensile force of the screw 46 is transferred via valve plate 10 to the support element 50 in the cylinder cover 12, and in order not to generate any stresses in the sealing plane. In other words, a slight gap remains between the lift catch 30 and the cylinder cover 12, such that the sealing plane between the valve plate 10 and the cylinder cover 12 is not redundant. Thus, a gap is arranged between the lift catch 30 and the cylinder cover 12, which prevents a redundancy of the sealing surface between the valve plate 10 and the cylinder cover 12. In order not to unnecessarily limit the axial play for manufacturing, a seal 58 (cylinder cover seal), which is arranged between the valve plate 10 and the cylinder cover 12 can compensate this axial play. Further, a seal (second seal 59) is also arranged between the valve plate 10 and the cylinder block.
The valve plate of the compressor according to the invention is shown in FIGS. 5, 6 and 7, wherein FIG. 5 shows the side facing toward the cylinders, and FIGS. 6 and 7 show the side facing toward the cylinder cover 12. FIG. 6 also shows the seal 58 (cylinder cover seal). As is seen particularly in FIG. 7, due to the connection of the cylinder cover 12 and the valve plate 10 in the region of the lift catch 30, only three small webs 60 are still required that interrupt the pressure opening 26. In comparison to the webs 116 according to the prior art (compare FIG. 1, here six webs 116 are required) the webs 60 are present in a reduced number and are significantly narrower.
This contributes to the performance optimization of a compressor because among other reasons, the filling factor (volumetric efficiency) of the compressor, i.e. the fastest possible gas exchange with the lowest loss (pressure loss, etc) per work cycle is critical for this. Large suction and pressure cross-sections relative to the cylinder displacement can be realized in order to reduce pressure losses and to allow a rapid gas exchange. The largest cross-sections can be achieved by means of the annular disks that are used. For optimum utilization of the cylinder cross-sectional area, the suction and pressure annular disks are arranged concentrically to each other. The center of the annular disks is located in the cylinder axis.
The construction leads to several positive effects:
1. Reduction of the tension in the most highly stressed region of the valve plate 10.
2. Reduction of the bending in the most highly stressed region of the valve plate 10.
3. Reduction of the number of webs and/or the web width
4. Enlargement of the grate cross-section (outflow cross-section)
5. The lift catch 30 is usually fixed axially by means of screws (prior art). In the present case, the lift catch is fixed axially using the support integrated into the cylinder cover. Thus, this valve plate 10 is particularly robust and less sensitive to pressure peaks and slugging or liquid hammers, respectively.
6. The tensile force of the screw 46 balances a certain portion of the compressive force on the high pressure side.
Although the invention is described based on an embodiment with fixed combination of features, the invention however also comprises conceivable further advantageous combinations, as they are specified, although not exhaustively, by the dependent claims. All features disclosed in the application documents are claimed as essential to the invention, insofar as they individually or in combination are novel with respect to the prior art.

LIST OF REFERENCE SIGNS

10 valve plate
12 cylinder cover
14 screws
16 suction volume
18 pressure volume
20 suction disk or suction lamella, resp.
22 pressure disk or pressure lamella, resp.
24 suction opening
26 pressure opening
28 sine spring
30 lift catch
32 pin
34 suction disk extension
36 suction disk extension
38 elongated hole
40 elongated hole
42 guide pin
44 guide pin
46 screw
48 thread
50 support element
52 outer wall of the cylinder cover 12
54 recess
56 pressure unit, or pressure nest, resp.
58 seal
59 second seal
60 web
110 valve plate
112 first surface
114 second surface
116 web
118 web

Claims

1. A compressor for compressing refrigerant comprising a cylinder block, a cylinder cover and a valve plate, said valve plate being interposed between the cylinder block and the cylinder cover, wherein

the valve plate is connected to the cylinder cover and/or is connected to the cylinder block, or respectively fastened thereto.

2. The compressor according to claim 1, wherein

the valve plate is connected to the cylinder cover and/or to the cylinder block by means of a connecting element, in particular a screw, or respectively is fastened thereto.

3. The compressor according to claim 1, wherein

the valve plate comprises a thread.

4. The compressor according to claim 1, wherein

the cylinder cover has a suction volume and a pressure volume, wherein a support element, in particular approximately column-shaped, is arranged in the suction volume or in the pressure volume, the support element extending from an outer wall of the cylinder cover towards the valve plate.

5. The compressor according to claim 4, wherein

the support element has a recess, which extends from the outer wall of the cylinder cover in the direction of the valve plate, the recess being provided for receiving the connecting element.

6. The compressor according to claim 1, wherein

the valve plate has one or more suction disks and/or one or more pressure disks, which are formed in a ring valve design.

7. The compressor according to claim 1, wherein

the connection of the valve plate to the cylinder cover and/or to the cylinder block is effected in the region of a pressure nest, or respectively a pressure unit, of the valve plate.

8. The compressor according to claim 1, wherein

the valve plate has a lift catch, which limits the lift of a pressure disk away from the valve plate.

9. The compressor according to claim 8, wherein

a gap is arranged between the lift catch and the cylinder cover.

10. The compressor according to claim 1, wherein

the valve plate is pressed together with the cylinder cover against the cylinder block by fastening elements, in particular fastening screws in regions, in which it does not cover any cylinder bores arranged in the cylinder block.