Radial piston compressor

Abstract

A radial piston compressor comprises a compressor unit and a drive device for driving the compressor unit, wherein the compressor unit comprises at least one, preferably a plurality of piston / working space combinations which are arranged radially around an eccentric shaft, wherein each piston / working space combination comprises a working space having a piston which is displaceably received therein, wherein the piston is driven by the eccentric shaft, wherein the eccentric shaft is rotatably supported in the radial piston compressor by means of at least three bearings, preferably three bearings.

Description

[0001] The invention relates to a radial piston compressor according to the preamble of claim 1.

[0002] A radial piston compressor is an element of fluid technology. In this radial piston compressor, at least one piston / working space combination in contrast to an axial piston compressor is arranged radially and perpendicularly to the drive shaft. A radial piston compressor can also be referred to as a compressor in accordance with the radial piston principle.

[0003] The conveying or lifting movement of the piston is in most cases brought about by means of an eccentric. In this regard, the drive shaft may also be referred to as an eccentric shaft. Generally, the radial piston compressor comprises a plurality of piston / working space combinations which extend in a star-like and radial manner from the drive shaft or eccentric shaft.

[0004] A piston / working space combination substantially comprises a working space, also referred to as a cylinder, and a piston which is moved up and down in the working space. The piston has a centrally geometric piston axis which corresponds to the displacement direction of the piston. In a radial piston compressor with an eccentric shaft, the piston comprises at the side thereof facing the eccentric shaft a contact face against which the eccentric disk strikes or abuts during the rotation of the eccentric shaft. The eccentric shaft has a rotation axis about which the eccentric shaft is rotated. When the eccentric strikes the contact face, there is an upward piston movement and a compression of a medium located in the working space.

[0005] Radial piston compressors are used, for example, for compressing coolants in air-conditioning systems of motor vehicles, in particular also in electrically driven motor vehicles. A medium which is intended to be compressed may include, for example, a coolant such as CO2. However, other media or coolants are also conceivable.

[0006] During a rotation, the refrigerant is drawn in, compressed and discharged again. This periodic process has between the cylinders a uniform phase shift which is produced in accordance with the number of cylinders.

[0007] The pressure which is adjusted in the cylinder acts via the piston face on the eccentric pin and consequently represents an excitation on the eccentric shaft. The superimposition of the forces of all the cylinders involved in the compression process produces the resulting force on the eccentric shaft. The eccentric shaft in turn, together with the bearing and the surrounding housing, represents a system which can oscillate. Said system is excited to carry out bending oscillations as a result of the periodically acting compression pressures.

[0008] In the system described here, bending oscillations have a particularly disadvantageous effect on the acoustic behavior since in the region of resonances the static force equilibrium is no longer complied with. Resonances occur when the inherent frequency of the oscillating system corresponds to the excitation frequency.

[0009] The present invention takes this as a basis and has the objective of providing an improved radial piston compressor, in particular providing a radial piston compressor which has improved acoustic behavior.

[0010] This object is achieved according to the invention with a radial piston compressor having the characterizing features of claim 1 in that the eccentric shaft is rotatably supported in the radial piston compressor by means of at least three bearings, preferably three bearings. In other words, in order to improve the acoustic behavior of the radial piston compressor, it is advantageous as a result of a targeted selection of the number of bearings, bearing position and / or bearing rigidity, to influence the system in such a manner that resonances can develop less powerfully.

[0011] Other advantageous embodiments of the proposed invention will be appreciated in particular from the features of the independent claims. The aspects of subject-matter or features of the different claims may in principle be freely combined with each other.

[0012] In an advantageous embodiment of the invention, there may be provision for the radial piston compressor to comprise a drive housing, a compressor housing and a compressor housing cover. In principle, the housing of the radial piston compressor may have other components or in principle be configured also to be divided only in two. In the three-way division illustrated here, however, the positions of the individual bearings are advantageous for a preferred embodiment of the invention, in particular since they are readily accessible in the individual housing portions and can be readily assembled or disassembled, for example, for maintenance purposes.

[0013] In another advantageous embodiment of the invention, there may be provision for the first bearing to be received in the compressor housing cover, the second bearing in the compressor housing and the third bearing in the drive housing. In this instance, a preferred positioning of the bearings with respect to the available housing components is set out. As already set out above, the bearings can be easily assembled or disassembled on the individual housing components.

[0014] In another advantageous embodiment of the invention, there may be provision for the first bearing and the second bearing to be received in the compressor housing and the third bearing to be received in the drive housing. In this instance, a preferred positioning of the bearings with respect to the available housing components is set out. As already set out above, the bearings can be easily assembled or disassembled on the individual housing components.

[0015] In another advantageous embodiment of the invention, there may be provision for the shaft as a result of the three bearing locations and the arrangement thereof to have a vibration node, wherein this vibration node is arranged in the axial position thereof close to the location of a load introduction.

[0016] In another advantageous embodiment of the invention, there may be provision for the bearings to be in the form of plain bearings or roller bearings, in particular cylinder roller bearings or ball bearings. Such bearing types have an advantageous bearing rigidity.

[0017] In another advantageous embodiment of the invention, there may be provision for one of the bearings to be in the form of an axial bearing. Accordingly, via the axial bearing the eccentric shaft can be axially fixed.

[0018] In another advantageous embodiment of the invention, there may be provision for the bearings to be received in the housing by means of pressing. Such a fixing of the bearings can be readily used in an industrial series production.

[0019] In another advantageous embodiment of the invention, there may be provision for the eccentric shaft to be axially guided by means of a securing ring. This advantageously results in the bearings not having to absorb any axial forces.

[0020] Other features and advantages of the present invention will be clearly appreciated from the following description of preferred exemplary embodiments with reference to the appended drawings, in which:

[0021] FIG. 1 shows a first bending vibration form of a shaft with an external 2-fold bearing;

[0022] FIG. 2 shows a first bending vibration form of a shaft with a three-fold bearing and vibration nodes near the location of the excitation;

[0023] FIG. 3 shows an eccentric shaft of a radial piston compressor according to the invention as a sectioned side view;

[0024] FIG. 4 shows an embodiment of a radial piston compressor according to the invention as a sectioned side view;

[0025] FIG. 5 shows another embodiment of a radial piston compressor according to the invention as a sectioned side view;

[0026] FIG. 6 shows another embodiment of a radial piston compressor according to the invention as a sectioned side view;

[0027] FIG. 7 shows a sectioned plan view of a radial piston compressor according to the invention.

[0028] The following reference numerals are used in the drawings:

[0029] S Vibration node

[0030] O Location of the excitation, load introduction

[0031] G Vibration form

[0032] D Rotation axis

[0033] 1 Drive device

[0034] 2 Compressor unit

[0035] 3 First bearing

[0036] 4 Second bearing

[0037] 5 Third bearing

[0038] 11 Drive housing

[0039] 12 Rotor

[0040] 21 Working space

[0041] 22 Piston

[0042] 23 Drive shaft

[0043] 24 Eccentric disk

[0044] 25 Compressor housing, cylinder housing

[0045] 26 Compressor housing cover

[0046] 27 Eccentric bearing

[0047] 28 Transfer element

[0048] 29 Piston guiding ring

[0049] 30 Securing ring

[0050] 231 First portion

[0051] 232 Second portion

[0052] In this instance, features and details which are described in connection with a method and of course also in connection with the apparatus according to the invention and vice versa apply so that, with respect to the disclosure, reference is or can always be made mutually to the individual aspects of the invention. Furthermore, a method according to the invention which is where applicable described can be carried out using the apparatus according to the invention.

[0053] The terminology used herein is used only for the purposes of describing specific embodiments and should not limit the disclosure. As used herein, the singular forms “a / one” and “the” are also intended to include the plural forms as long as the context does not otherwise allow this to be clearly identified. It will additionally be clear that the terms “has” and / or “having” when used in this description specify the presence of the features mentioned, whole numbers, steps, operations, elements and / or components, but do not exclude the presence or the addition of one or more other features, whole numbers, steps, operations, elements components and / or groups thereof. As used herein, the term “and / or” includes any and all combinations of one or more of the associated listed elements.

[0054] Reference will first be made to FIG. 1.

[0055] FIG. 1 schematically illustrates a first bending vibration form G of an eccentric shaft 23 with an external 2-fold bearing. It should in particular be thereby made clear that with a conventional bearing system with two bearings 3, 4 at the beginning and at the end of the shaft 23, a first bending vibration form G of the shaft which exclusively has vibration nodes S on or outside the bearing locations 3, 4 is formed. As shown in FIG. 1, the arrangement illustrated in this instance has two vibration nodes S.

[0056] Vibration form and vibration node are terms from (mechanical) vibration teaching or machine dynamics. The vibration form or the vibration mode describes the form / configuration of an inherent frequency of a resilient structure. In addition to bending vibration forms, there are torsion vibration forms in which the shaft vibrates about the rotation axis, or hybrids.

[0057] When such a system is excited, a very dominant resonance which in turn leads to a poor NVH behavior of the overall system is formed. The NVH (Noise Vibration Harshness) generally summarizes the acoustic behavior.

[0058] In order to displace this Eigenmode significantly into non-critical excitation ranges, the shaft rigidity, bearing rigidity and housing rigidity would have to be significantly increased. As a result of the structural space restrictions and the periphery of the compressor, this is only possible to a limited degree.

[0059] As described above, the problem lies in the development of bending vibration resonances which significantly impair the acoustic behavior. How powerfully a resonance of a system can be excited may substantially depend on the factors excitation frequency, excitation amplitude, system damping, location of the excitation and / or the vibration form. As a result of the system, the first four factors can only be influenced with difficulty.

[0060] According to the invention, it is proposed that the eccentric shaft is supported in the radial piston compressor by means of at least three bearings, preferably three bearings. In other words, it is proposed by means of a targeted selection of the number of bearings, bearing position and / or bearing rigidity to influence the vibration form in such a manner that the vibration node is located as close as possible to the location of the excitation.

[0061] To this end, in FIG. 2, for example, a first bending vibration form G of a shaft 23 with a three-fold bearing and vibration node S close to the location of the excitation O is illustrated. In the theoretical case that the vibration node S and the location of the excitation O meet each other precisely, no resonance would develop. For practical reasons, such as, for example, the structural space and the arrangement, which is not thereby freely selectable, of the bearing locations or the cylinder arrangement or the stroke (height / deflection of the eccentric), a person skilled in the art attempts to configure the compressor in such a manner that the vibration node S is located as close as possible to the location of the excitation or the location of the introduction of force. As can be seen, the shaft 23 comprises in this instance a first bearing 3, a second bearing 4 and a third bearing 5. The location of the introduction of force O or the location of the excitation O is in this instance illustrated schematically as a dot and represents the forces acting on the shaft 23.

[0062] Reference will be made below to FIGS. 3 to 6 which relate to embodiments of radial piston compressors according to the invention. In particular, the configuration of the radial piston compressor has been adapted in such a manner that the 3rd bearing location, in particular with the associated adapted rigidities of the bearing shaft and housing portions, leads to the described effect.

[0063] FIG. 3 illustrates a cut-away eccentric shaft 23, 24 with a rotor 12 of a radial piston compressor according to the invention.

[0064] The eccentric shaft 23, 24 substantially comprises a drive shaft 23 and an eccentric disk 24. An eccentric bearing 27, such as, for example, a needle bearing, may be fitted to the eccentric disk 24.

[0065] It can further be seen that in each case a bearing 3, 4, 5, in particular a ball bearing, is fitted at three different axial positions of the eccentric shaft 23, 24, in particular a first bearing 3 in the region of one end of the eccentric shaft, a second bearing 4 approximately at the center of the eccentric shaft and a third bearing 5 at the other end of the eccentric shaft. It can in particular be seen that the second bearing 4 is arranged between the eccentric disk 24 and the rotor 12. Furthermore, it can be seen that from this a bearing arrangement of the shaft 23 is produced in which the eccentric disk 24 is arranged in an axial direction between two bearings, the bearings 3 and 4. The bending vibration form G (illustrated with broken lines) of the shaft 23 according to FIG. 3 has as a result of the three bearing locations 3, 4, 5 and the arrangement thereof a vibration node S. This vibration node S is in the axial position thereof, in particular on the rotation axis D of the shaft 23, arranged close to the location of the load introduction O.

[0066] In FIG. 4, one embodiment of a radial piston compressor according to the invention is illustrated as a sectioned side view.

[0067] A radial piston compressor substantially comprises, in addition to the eccentric shaft 23, 24, a drive device 1 and a compressor unit 2.

[0068] The drive device 1 substantially comprises a drive housing 11 and a rotor 12. A stator is not illustrated here for reasons of clarity. The drive device 1 is consequently preferably substantially in the form of an electric motor.

[0069] The compressor unit 2 substantially comprises at least one, preferably a plurality of piston / working space combinations 21, 22 which are arranged around the eccentric shaft 23, 24. Preferably, the piston / working space combinations 21, 22 extend radially from the eccentric shaft 23, 24. The piston / working space combinations 21, 22 are arranged in a compressor housing 25, also referred to as a cylinder housing, or there may be provision for the working space(s) 21 to be at least partially formed by the compressor housing 25. There is further provision for the compressor housing 25 to be provided at one side with a compressor housing cover 26. The compressor housing cover 26 may, for example, be removed for maintenance purposes and / or form part of the working space(s) 21. In an axial direction, the following sequence of the housing components is produced: compressor housing cover 26, compressor housing 25, drive housing 11, wherein in the configuration according to FIG. 4 the compressor housing 25 does not extend up to the outer face of the compressor. The housing components may be connected in a releasable manner by means of screws. The housing of the radial piston compressor may be formed by the working housing 11, the compressor housing 25 and the compressor housing cover 26.

[0070] The piston / working space combination per se comprises a working space 21 and a piston 22 which is displaceably received in the working space 21. As a result of the displacement of the piston 22 in the working space 21, the fluid contained in the working space 21, such as, for example, a refrigerant, in particular CO2, can be compressed.

[0071] The drive device 1 displaces the drive shaft 23 in rotation, whereby the eccentric disk 24 strikes the piston 22, in particular the piston base. The piston 22 is thereby displaced within the working space 21 away from the eccentric shaft. The piston(s) 22 is / are accordingly driven by the eccentric shaft. A piston guiding ring 29 which can come into contact with the piston(s) 22 and can push the piston 22 back again in the direction of the eccentric shaft 23, 24 may also be provided.

[0072] As already indicated above, the eccentric disk 24 may be provided with an eccentric bearing 27. The piston 22, in particular the piston base, may also be provided with a transmission element 28. The transmission element 28 may be produced from a different material, for example, from the piston 22, for example, from a plastics material or in particular metal alloy which is advantageously suitable for the frequently repeated occurrences of contact with the eccentric disk 24 or eccentric bearing 27.

[0073] Other components, such as, for example, valves, channels, etc., are not illustrated here in greater detail. The operating principle of a radial piston compressor is, however, sufficiently known to a person skilled in the art.

[0074] As already set out above, there is provision according to the invention for the eccentric shaft to be supported by at least three bearings, preferably three bearings 3, 4, 5, in the radial piston compressor.

[0075] FIG. 4 illustrates an embodiment of the radial piston compressor according to the invention, the eccentric shaft 23, 24 of which is supported by means of three bearings 3, 4, 5 in the radial piston compressor. There is provision in this instance for the first bearing 3 to be received in the compressor housing cover 26, the second bearing 4 in the compressor housing 25 and the third bearing 5 in the drive housing 11.

[0076] FIG. 5 illustrates an embodiment of the radial piston compressor according to the invention, the eccentric shaft 23, 24 of which is supported by means of three bearings 3, 4, 5 in the radial piston compressor. There is provision in this instance for the first bearing 3 and the second bearing 4 to be received in the compressor housing 25 or the cylinder housing 25 and the third bearing 5 to be received in the drive housing 11. The bearings 3 and 4 are consequently arranged axially along the shaft 23 at both sides of the piston 22 or at both sides of the working space 21. In this manner, the bearings 3 and 4 are arranged axially very close to the location of the load introduction O and can optimally support the shaft 23. The housing of the radial piston compressor may be formed by the drive housing 11, the compressor housing 25 and the compressor housing cover 26.

[0077] FIG. 6 illustrates an embodiment of the radial piston compressor according to the invention, the eccentric shaft 23, 24 of which is supported by means of three bearings 3, 4, 5 in the radial piston compressor. There is provision in this instance for the first bearing 3 and the second bearing 4 to be received in the compressor housing 25 and the third bearing 5 to be received in the drive housing 11. There is further provision for the eccentric shaft 23, 24 to be configured in several pieces in an axial direction. Substantially one first axial portion 231 and at least a second portion 232 may preferably only have a second portion 232. The eccentric shaft may in this regard also be referred to as an assembled eccentric shaft. The housing of the radial piston compressor may be formed by the drive housing 11, the compressor housing 25 and the compressor housing cover 26. As shown in FIG. 6, the compressor housing 25 extends in this embodiment of the radial piston compressor up to the outer face or outer covering face thereof. In FIG. 6, it can additionally be seen that the eccentric shaft is axially guided by means of a securing ring 30. This advantageously results in the bearings not having to absorb any axial forces.

[0078] In FIG. 7, a radial piston compressor according to the invention is illustrated as a sectioned plan view, in particular to explain the arrangement of a plurality of, in this case six, piston / working space combinations 21, 22. For reasons of clarity, only one piston / working space combination is provided with the reference numerals 21, 22.

[0079] The radial piston compressor according to the invention may further be characterized by the following features.

[0080] There may preferably be provision for the bearings 3, 4, 5 to be in the form of plain or roller bearings, in particular cylinder roller bearings or ball bearings.

[0081] There may preferably be provision for one of the bearings 3, 4, 5 to be in the form of axial bearings.

[0082] There may preferably be provision for the bearings 3, 4, 5 to be received in the housing 11, 25, 26 by means of pressing.

[0083] There may preferably be provision for the eccentric shaft to be able to be axially guided by means of a securing ring 30. The bearings 3, 4 and 5 consequently do not have to absorb any axial forces.

Claims

1-9. (canceled)10. A radial piston compressor, comprising:a compressor unit; anda drive device for driving the compressor unit;wherein the compressor unit includes at least one piston / working space combination arranged radially around an eccentric shaft;wherein each piston / working space combination includes a working space having a piston displaceably received therein, wherein the piston is driven by the eccentric shaft;wherein the eccentric shaft is rotatably supported in the radial piston compressor by at least three bearings.

11. The radial piston compressor as claimed in claim 10, wherein the compressor unit includes a plurality of piston / working space combinations arranged radially around the eccentric shaft and wherein the eccentric shaft is rotatably supported in the radial piston compressor by exactly three bearings.

12. The radial piston compressor as claimed in claim 10, wherein the radial piston compressor includes a drive housing, a compressor housing, and a compressor housing cover.

13. The radial piston compressor as claimed in claim 12, wherein a first bearing is received in the compressor housing cover, a second bearing is received in the compressor housing, and a third bearing is received in the drive housing.

14. The radial piston compressor as claimed in claim 12, wherein a first bearing and a second bearing are received in the compressor housing and a third bearing is received in the drive housing.

15. The radial piston compressor as claimed in claim 10, wherein the shaft as a result of the three bearing locations and the arrangement thereof has a vibration node, wherein this vibration node is arranged in the axial position thereof close to the location of a load introduction.

16. The radial piston compressor as claimed in claim 10, wherein the bearings are in the form of plain or roller bearings.

17. The radial piston compressor as claimed in claim 10, wherein the bearings are in the form of cylinder roller bearings or ball bearings.

18. The radial piston compressor as claimed in claim 10, wherein a single bearing is in the form of an axial bearing.

19. The radial piston compressor as claimed in claim 10, wherein the bearings are received in a housing by pressing.

20. The radial piston compressor as claimed in claim 10, wherein the eccentric shaft is axially guided by a securing ring.

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