Radial piston compressor

Abstract

The invention relates to a radial piston compressor, comprising a compressor unit (1) and a drive device (2) for driving the compressor unit (1), wherein the compressor unit (1) comprises a plurality of piston-working-chamber assemblies (13), which are arranged radially around an eccentric shaft (11, 12), the eccentric shaft being driven by the drive device (2); each piston-cylinder-bore assembly (13) comprises a piston (132) which can be moved in a working chamber (131); and the compressor unit (1) comprises a cylinder housing (16) and the drive device (2) comprises a drive housing (21), the cylinder housing (16) and the drive housing (21) being connected together via a centering device, which comprises a sequence of individual centering elements (71) and free positions (72) arranged in the circumferential direction. The invention likewise relates to a method for producing the corresponding radial piston compressor.

Description

[0001] radial piston compressor

[0002] The present invention relates to a radial piston compressor according to the preamble of claim 1, and to a method for manufacturing a radial piston compressor, in particular a cylinder housing of a radial piston compressor, according to the preamble of claim 4.

[0003] A radial piston compressor is a fluid power component. In contrast to an axial piston compressor, in this type of compressor at least one piston-working chamber assembly is arranged radially and perpendicular to the drive shaft. A radial piston compressor can also be referred to as a compressor based on the radial piston principle.

[0004] The piston's conveying or reciprocating motion is usually generated by an eccentric. Therefore, the drive shaft with the eccentric can also be referred to as an eccentric shaft. Typically, a radial piston compressor comprises several piston-working chamber assemblies that extend radially from the eccentric shaft in a star-shaped pattern.

[0005] A piston-work chamber assembly essentially comprises a working chamber, also called a cylinder, and a piston that moves up and down within the working chamber. The piston has a central geometric axis that coincides with the piston's direction of movement. In a radial piston compressor with an eccentric shaft, the piston has a contact surface on its side facing the eccentric shaft. The eccentric disk contacts this surface during the rotation of the eccentric shaft. The eccentric shaft has an axis of rotation around which it rotates. When the eccentric disk contacts the contact surface, the piston moves upward, compressing the medium in the working chamber.

[0006] Radial piston compressors are used, for example, to compress refrigerant in the air conditioning systems of motor vehicles, especially in electric vehicles. A refrigerant such as CO2 can be used as the medium to be compressed. However, other media and refrigerants are also conceivable.

[0007] A radial piston compressor of the aforementioned type is known, for example, from DE 10 2020 211 680 Al or DE 10 2022 133 723 Al. A radial piston compressor of the aforementioned type is also known from DE 10 2021 204 713 Al. This describes a radial piston compressor whose working chambers are each equipped with an inlet valve cover at the head end. It is also provided that all inlet valve covers of the radial piston compressor are secured by a common retaining ring.

[0008] The retaining ring may be centered by the intake valve covers distributed around the circumference. Axially, the retaining ring can connect to the cylinder housing via a gasket, and oppositely, to the drive housing via another gasket. Since the intermediate retaining ring typically only has axial contact surfaces, a centering element is usually integrated to ensure the cylinder housing and drive housing are aligned. This is achieved, for example, by a shoulder in the cylinder housing that centers itself internally within the drive housing. If the centering element is circumferential, the fluid flow between the drive housing chamber and the intake valve or intake valve cover is blocked. No gas can be drawn in through the intake valve, and the radial piston compressor is inoperable.

[0009] It is also known that the radial piston compressor is equipped with a cylinder housing, essentially for accommodating or forming the piston-working chamber assemblies, and a drive housing, essentially for accommodating or forming an electric motor as a drive device.

[0010] The design stipulates that the two housing halves are centered relative to each other using suitable means to minimize misalignment in the bearing bore and in the position between the rotor and stator. However, this centering can impede the fluid flow between the inlet valve and the low-pressure side of the compressor.

[0011] Known solutions connect the two suction paths using bores, which, in the case of a radial piston compressor, would have to be machined at an angle. Manufacturing angled bores that penetrate a surface at an angle is disadvantageous for the machining process. Due to the limited installation space, the bores do not reach the desired position on the inlet valve cover or fluid inlet channel. Suction gas losses are to be expected in the intervening path, which negatively impact the compressor's performance. Furthermore, feed channels and bores are constrictions, resulting in cross-sectional changes and deflections that restrict the suction gas flow and thus cause further flow losses.The present invention addresses this issue and aims to propose an improved radial piston compressor. In particular, a radial piston compressor with a retaining ring for securing the inlet valve covers is proposed, which avoids, or at least mitigates, the problems outlined above. To ensure optimal fluid flow, technical solutions are to be developed that are as space-efficient as possible, without impairing fluid flow or resulting in excessive intake losses.

[0012] According to the invention, this problem is solved by a radial piston compressor with the characterizing features of claim 1. By connecting the cylinder housing and the drive housing to each other via a centering device, wherein the centering device comprises a circumferentially arranged sequence of individual centering elements and clearances, it can be ensured that the flow cross-section between the low-pressure area and the inlet ports of the piston-working chamber assemblies is not excessively restricted, and in particular is always maximized. Preferably, the resulting intake losses are reduced, and preferably avoided. At the same time, the centering of both housing halves is ensured.

[0013] The fluid can flow freely laterally through the cutouts to the fluid inlet channel or the respective inlet valve. The resulting cross-section is always large enough to prevent any or only minimal constriction or drastic deflections. The centering of both components is nevertheless ensured by the remaining individual centering elements.

[0014] Further advantageous embodiments of the proposed invention arise in particular from the features of the dependent claims. The subject matter or features of the various claims can, in principle, be combined with one another in any way.

[0015] In an advantageous embodiment of the invention, the centering device may comprise one clearance for each piston-working chamber assembly. Accordingly, each fluid inlet channel may be assigned a clearance through which fluid can flow. In a further advantageous embodiment of the invention, the centering device may comprise one individual centering element for each piston-working chamber assembly. This allows for the provision of maximum support for the drive housing.

[0016] In a further advantageous embodiment of the invention, it can be provided that the radial piston compressor comprises a low-pressure area, wherein each piston-cylinder bore assembly is equipped with an inlet channel, wherein the flow cross-section between the low-pressure area and the respective inlet channel of the piston-working chamber assembly is maximal in the area of ​​the centering device.

[0017] The invention further relates to an advantageous method for manufacturing a radial piston compressor according to the invention, in particular a cylinder housing of a radial piston compressor according to the invention, according to the preamble of claim 4.

[0018] According to the invention, this problem is solved by a method for manufacturing a radial piston compressor according to the invention, in particular a cylinder housing of a radial piston compressor according to the invention, in which the cylinder housing is manufactured as a casting, wherein the recesses are provided in the casting. Accordingly, the recesses do not need to be subsequently created, for example by milling.

[0019] Further features and advantages of the present invention will become clear from the following description of preferred embodiments with reference to the accompanying figures. These show

[0020] Fig. 1 shows a radial piston compressor in a side-cut view;

[0021] Fig. 2 shows a radial piston compressor in a cutaway view from the front;

[0022] Fig. 3 shows a radial piston compressor in a cutaway view from the front;

[0023] Fig. 4 shows an enlarged view of a section of a radial piston compressor according to

[0024] Fig. 3;

[0025] Fig. 5 shows a cylinder housing of a radial piston compressor in a perspective view;

[0026] Fig. 6 shows an exploded view of a receiver, an inlet valve and an inlet valve cover of a radial piston compressor;

[0027] Fig. 7 shows a cylinder housing of a radial piston compressor in a perspective view;

[0028] Fig. 8 shows a detail of a radial piston compressor in a sectional view;

[0029] Fig. 9 shows a detail of a radial piston compressor in a sectional view;

[0030] Fig. 10 shows a detail of a radial piston compressor in a partially transparent view;

[0031] Fig. 11 shows a detail of a radial piston compressor in a partially transparent view;

[0032] Fig. 12 shows a cylinder housing of a radial piston compressor according to the invention in a perspective view;

[0033] Fig. 13 shows a detail of a radial piston compressor according to the invention in a sectional view;

[0034] Fig. 14 shows a detail of a radial piston compressor according to the invention in a sectional view;

[0035] Fig. 15 shows a detail of a radial piston compressor according to the invention in a sectional view.

[0036] The following reference symbols are used in the illustrations:

[0037] R axis of rotation

[0038] K Piston axis

[0039] B bore h opening height

[0040] L bending length

[0041] 1 compressor unit

[0042] 2 Drive unit

[0043] 3 retaining rings

[0044] 4 High-pressure collector channel

[0045] 5 Low-pressure gas side (LP) / Low-pressure area

[0046] 6 -free-

[0047] 7 -free-

[0048] 8 Shoulder

[0049] 11 Drive shaft

[0050] 12 eccentric discs

[0051] 13 Piston working chamber assembly or indices a, b, c, ...

[0052] 14 - free -

[0053] 15 Intake valve covers or indices a, b, c, ...

[0054] 16 cylinder housings

[0055] 17 high-pressure lids

[0056] 18 Recess for intake valve cover

[0057] 21 Drive housings

[0058] 22 Rotor

[0059] 24 Inlet valve

[0060] 25 Exhaust valve

[0061] 71 Single centering element

[0062] 72 Release 121 Eccentric bearing

[0063] 131 Workspace

[0064] 132 pistons

[0065] 133 Transmission element

[0066] 151 Seal

[0067] 211 Contact surface (drive housing side)

[0068] 241 Fluid inlet channel

[0069] 242 Valve plate

[0070] 251 Fluid outlet channel

[0071] 2421 Valve tongue

[0072] Features and details described in connection with a method naturally also apply to the device according to the invention, and vice versa, so that the disclosure regarding the individual aspects of the invention always makes or can make reciprocal reference. Furthermore, any described method according to the invention can be carried out with the device according to the invention.

[0073] The terminology used herein serves only to describe certain embodiments and is not intended to limit the disclosure. As used herein, the singular forms "a" and "the" shall also include the plural forms unless the context otherwise makes clear. It shall also be clear that the expressions "indicates" and / or "indicating," when used in this description, specify the presence of the aforementioned features, integers, steps, operations, elements, and / or components, but do not exclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or groups thereof. As used herein, the expression "and / or" includes any and all combinations of one or more of the associated, listed elements. Reference is made in particular to Figures 1 and 2.

[0074] A radial piston compressor essentially comprises a compressor unit 1 and a drive unit 2. The radial piston compressor includes a housing, which can be composed of individual housing components, such as, for example, in the present embodiment, a drive housing 21, a cylinder housing 16, and a high-pressure cover 17. Other housing configurations are also conceivable.

[0075] The compressor unit 1 comprises a drive shaft 11 with an eccentric disc 12. The combination of drive shaft 11 and eccentric disc 12 can also be referred to as an eccentric shaft. The drive shaft 11 has a pivot axis D. The compressor unit 1 comprises at least one piston-working chamber assembly 13, preferably several piston-working chamber assemblies 13, 13a, 13b... 13f, which are arranged radially around the drive shaft 11. The indices a, b, c, ... accordingly represent further piston-working chamber assemblies. The piston-working chamber assemblies 13 (ae) around the drive shaft 11 can also be described as having a star-shaped arrangement. The piston-working chamber assembly 13 comprises a working chamber 131 with a piston 132 slidably arranged therein. The piston 132 has a piston axis K. The direction of displacement of the piston 132 corresponds to the piston axis K. The working chamber 131 can also be referred to as a cylinder or cylinder bore.The working chamber 131 is equipped with an inlet valve cover 15 at the cylinder head. The indices a, b, c, ... represent further inlet valve covers accordingly. It can be seen that each piston-working chamber assembly 13 is equipped with an inlet valve cover 15. The working chambers 131 of the piston-working chamber assemblies 13 can be formed at least partially, preferably completely, from the cylinder housing 16.

[0076] The drive shaft 11, in turn, can be set in rotation by the drive unit 2, which can, for example, be designed as an electric motor. As the drive shaft 11 rotates, the eccentric disk 12 engages the piston 132 and moves it within the working chamber 131, thereby compressing the medium in the working chamber, for example, a refrigerant. The return movement of the piston 132 can be effected, for example, by a piston guide ring (not shown) in contact with the piston 132. In this way, the piston 132 can be moved back to bottom dead center (BDC) until the eccentric disk 12 again engages the piston crown. The piston 132, in particular the piston crown, can also be equipped with a transmission element 133, or a transmission element 133 can be arranged between the eccentric disk 12 and the piston 132.The transmission element 133 transfers the stroke of the eccentric disc 12 to the piston 132, enabling the piston to perform the compression movement towards top dead center (TDC). The transmission element 133 can be made of a different material than the piston 132 and eccentric disc 12, particularly plastic. This can, for example, reduce wear or provide some damping when the eccentric disc 12 impacts the piston. The eccentric disc 12 can also be equipped with an eccentric bearing 121, particularly a needle bearing.

[0077] The further details and operation of a radial piston compressor are sufficiently known to those skilled in the art. For further details, reference can be made, for example, to DE 10 2020 211 680 A1.

[0078] Particular reference is made below to Figures 3 to 5.

[0079] The intake valve cover 15 is received in a receptacle 18 above the respective working chamber 131. The receptacle 18 is designed as a recess in the cylinder housing 16 and includes a shoulder as a bearing surface 181 for supporting a valve plate 242 or the intake valve cover 15.

[0080] The shape of the receptacle 18 or recess ultimately depends on the shape of the intake valve cover 15, such that the intake valve cover 15, possibly with a circumferential seal 151, and the valve plate 242 can be received in the receptacle 18. A circular cylindrical recess 18 and a flat circular cylindrical intake valve cover 15 are shown here. The circular cylindrical recess 18 can also be referred to as a cover bore.

[0081] The inlet valve cover 15 comprises an inlet valve 24. The inlet valve 24 includes a fluid inlet channel 241 and the valve plate 242. It is preferably provided that the radial piston compressor comprises a low-pressure section 5, with each piston-cylinder bore assembly 13 being equipped with an inlet channel 241, wherein the flow cross-section between the low-pressure section 5 and the respective inlet channel 241 of the piston-working chamber assembly 13 is maximized in the area of ​​the centering device. The valve plate 242, in turn, comprises a valve tongue 2421. The inlet valve 24, in particular the valve tongue 2421, is configured to selectively close or open the fluid inlet channel 241.

[0082] The fluid to be compressed flows into the working chamber 131 via the fluid inlet channel 241, is compressed there by the stroke movement of the piston 132 and leaves the working chamber 131 through a fluid outlet valve 25 or fluid outlet channel 251.

[0083] The design of the valves, for example as a spring-loaded sheet valve, is sufficiently known to those skilled in the art and requires no further explanation here.

[0084] It is specifically provided that the fluid inlet channel 241 is aligned radially to the axis of rotation R of the drive shaft 1 of the radial piston compressor. It is specifically provided that the fluid outlet channel 251 is aligned axially to the axis of rotation R of the drive shaft 1 of the radial piston compressor. The fluid outlet channel 251 opens into a high-pressure collecting channel 4.

[0085] In particular, Fig. 4 illustrates the system pressures acting on the system and the pressure surfaces involved in the intake valve cover 15, which is arranged radially to the drive shaft 1. The valve plate 242 rests on the support surface 181 of the receptacle 18 at its edge and is pressed onto the support surface 181 by the intake valve cover 15.

[0086] When the piston 132 moves from its upper end position to its lower end position, a vacuum is created in the working chamber 131 between the piston head and the intake valve cover 15. The intake valve 24 opens into the working chamber 131, and fresh gas is drawn in through the fluid intake port 241. Specifically, the valve reed 2421 is lifted from the intake valve cover 15 against its bending force, thus opening the fluid intake port 241. After reaching bottom dead center (BDC), the piston 132 moves upwards again, the intake valve 242 closes, and the gas in the working chamber 131 is compressed. Specifically, the valve reed 2421 springs back, closing the fluid intake port 241. The compressed gas then exits the working chamber 131 through the exhaust valve 25, specifically the fluid outlet 251.

[0087] Particular reference is made below to Fig. 6. Fig. 6 shows the intake valve cover 15 with intake valve 24 in a general sectional view.

[0088] The valve tongue 2421 is spring-loaded and connected to the valve plate 242.

[0089] Fig. 6 shows the inlet valve 24 in the open state with an opening height (h) and a bending length (I). To ensure that the material stresses in this open state are permanently tolerable, the bending length (I) (distance from the clamping point to the center of the valve reed) should be as large as possible.

[0090] Reference is made below to Figures 7 to 11.

[0091] Figure 7 shows a perspective view of a cylinder housing 16 of a radial piston compressor. A rotor 22 of the drive unit 2, designed as an electric motor, is also visible.

[0092] Advantageously, a centering device is provided for the positional orientation and alignment of the cylinder housing 16 to the drive housing 21, especially in the case that the intermediate retaining ring 3 only has axial connection surfaces.

[0093] The centering device here comprises a continuous circumferential shoulder 8. The drive housing 21 has a corresponding support surface 211 which can rest on the shoulder 8.

[0094] In Fig. 8, the low-pressure side or low-pressure area of ​​the radial piston compressor is marked with reference numeral 5.

[0095] Furthermore, the inlet valve 24, or the valve plate 242, the inlet valve cover 15, the retaining ring 3, the cylinder housing 16 and the drive housing 21 are recognizable.

[0096] The position of the inlet valve 24 is assigned to the low-pressure (LP) side 5. The valve plate 242 is held by the inlet valve cover 15, and the inlet valve cover 15 is held in position by the retaining ring 3. The valve plate 242 and the inlet valve cover 15 are located in the cylinder housing 16. The retaining ring 3 is centered by the inlet valve covers 15, 15a, 15b, etc., distributed around the circumference. Axially, the retaining ring 3 connects to the cylinder housing 16 via a seal and, on the opposite side, to the drive housing 21 via another seal. Since the intermediate retaining ring 3 typically only has axial contact surfaces, a centering device should be integrated to ensure the positional orientation and alignment of the cylinder housing 16 with the drive housing 21. This is achieved by the shoulder 8 in the cylinder housing 16, which centers itself internally within the drive housing 21.

[0097] If the centering device includes a circumferential shoulder 8, the fluid flow between the drive housing chamber 21 and the inlet valve 24 may be blocked. No fluid, especially gas, can be drawn in by the inlet valve 24, and the compressor would be inoperative. A non-inventive solution would be to introduce bores B towards the low-pressure gas side 5. These would have to extend from the retaining ring chamber to the low-pressure gas side, their position is limited by the numerous surrounding functional surfaces, and they would have to be drilled at an angle. Furthermore, the bores B would open at a location unfavorable from a flow perspective and not directly at the fluid inlet channel 241 of the inlet valve 24 or valve cover 15.

[0098] Figure 9 shows the centering device of the drive housing 21 and the cylinder housing 16 in detail and in a perspective view. The inlet valve plate 242, the inlet valve cover 15, the retaining ring 3, and the cylinder housing 16 are particularly visible. The drive housing 21 is partially supported on the circumferential shoulder 8 by a contact surface 211 associated with the centering.

[0099] Figure 10 shows a bore B extending from the space below the retaining ring 3 to the low-pressure gas side 5. The space below the retaining ring 3 is fluidically connected to the inlet valves 24. This is the solution already described above, but rather disadvantageous, for overcoming the blockage or at least the negative influence on the fluid flow between the low-pressure side 5 and the inlet valve 24 while simultaneously using a circumferential shoulder 8. Figure 11 shows this bore B again from a different perspective. It can be seen that the bore B extends from the low-pressure area 5 into a space below the retaining ring 3. Reference is then made to Figures 12 to 15. These show a radial piston compressor according to the invention, or details of a radial piston compressor according to the invention.

[0100] According to the invention, the centering device is segmented. In other words, the centering device comprises a circumferentially arranged sequence of individual centering elements 71 and clearances 72.

[0101] Between the individual centering elements 71, corresponding cutouts 72 are provided. In the circumferential direction, this results in a sequence of individual centering elements 71 and cutouts 72. The centering is therefore no longer formed by a continuous shoulder, but by interrupted individual surfaces.

[0102] A key aspect of the invention is therefore to interrupt the centering seat between the drive housing and the cylinder housing in such a way that the flow path is not unduly restricted, and in particular is always maximally restricted. Preferably, the resulting intake losses should be reduced, and preferably eliminated. At the same time, however, the centering of both housing halves should be ensured.

[0103] The fluid can flow freely laterally through the clearances 72 to the fluid inlet channel 241 or to the inlet valve 24. The resulting cross-section is always large enough to prevent any or only minimal constriction or drastic deflections. Centering of both components is nevertheless ensured by the remaining individual centering elements 71. The clearances 72 can be incorporated into the casting.

[0104] Figure 12 shows a perspective view of the cylinder housing 16 of a radial piston compressor according to the invention. It can be seen how the individual centering elements 71 alternate with the clearances 72 in the circumferential direction. Nevertheless, the individual centering elements 71 together form a sufficient centering device that can adequately fulfill both tasks – centering and fluid flow. The individual centering sections 71 are preferably arranged or configured axially along the drive shaft 11.

[0105] In summary, the proposed invention offers the following advantages in particular. The centering of the two housing halves 16, 21 is ensured by the individual centering elements 71. Due to their large cross-sections, the intervening clearances 72 do not impede the flow of fluid, and no or only minimal suction losses occur along the path between the low-pressure gas side 5 in the drive housing 21 and the fluid inlet channel in the inlet valve cover 15. The performance of the radial piston compressor is not adversely affected by the centering. Therefore, the complex manufacturing of angled feed channels and / or bores with constrictions, cross-sectional changes, and deflections that restrict the suction gas flow is unnecessary. The required clearances 72 can be incorporated directly into the casting and are cost-neutral.Accordingly, the manufacturing process for the radial piston compressor, in particular for the cylinder housing 16, provides that the cylinder housing 16 is manufactured as a casting, with the recesses 72 already present in the casting. Therefore, they do not need to be added subsequently, for example by milling.

[0106] The individual centering elements 71 and the clearances 72 can be designed differently in their type, number and size, especially as long as sufficient cross-section is released that does not impede the suction gas flow.

[0107] Preferably, the centering device includes one clearance 72 per piston-working chamber assembly. Accordingly, each fluid inlet channel 242 can be assigned a clearance through which fluid can flow.

[0108] Accordingly, it is also preferably provided that the centering device comprises a single centering element 71 per piston working chamber assembly.

[0109] For example, Fig. 15 also shows with arrows how the fluid / refrigerant can pass through the release 72, past the single centering element 71 to the inlet valve cover 15 and consequently into the working chamber 131.

Claims

Claims 1. Radial piston compressor, comprising - a compressor unit (1) and a drive unit (2) for driving the compressor unit (1), wherein - the compressor unit (1) comprises a plurality of piston working chamber assemblies (13) arranged radially around an eccentric shaft (11, 12), wherein - the eccentric shaft is driven by the drive device (2), wherein - each piston-cylinder bore assembly (13) comprises a piston (132) that is movable in a working space (131), wherein - the compressor unit (1) comprises a cylinder housing (16) and the drive unit (2) comprises a drive housing (21), characterized in that the cylinder housing (16) and the drive housing (21) are connected to each other via a centering device, wherein the centering device comprises a circumferentially arranged sequence of individual centering elements (71) and clearances (72).

2. Radial piston compressor according to claim 1, characterized in that the centering device comprises a clearance (72) per piston working chamber assembly (13, 13a, 13b, ...).

3. Radial piston compressor according to at least one of the preceding claims, characterized in that the centering device comprises a single centering element (71) per piston working chamber assembly (13, 13a, 13b, ...).

4. Radial piston compressor according to at least one of the preceding claims, characterized in that the radial piston compressor comprises a low-pressure area (5), wherein each piston-cylinder bore assembly (13) is equipped with an inlet channel (241), wherein the flow cross-section between the low-pressure area (5) and the respective inlet channel (241) of the piston working chamber assembly (13) is maximal in the area of ​​the centering device.

5. Method for manufacturing a radial piston compressor, in particular a cylinder housing (16), according to at least one of the preceding claims, characterized in that the cylinder housing (16) is manufactured as a casting, wherein the reliefs (72) are provided in the casting.

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