Radial piston pump, and process for manufacturing a radial piston pump

Abstract

The invention relates to a radial piston pump comprising a drive shaft (1) with an eccentric (11), and comprising at least one piston-working chamber combination (2), the piston-working chamber combination (2) comprising a working chamber (21) and a piston (22). The radial piston pump comprises at least two piston-working chamber combinations (2, 2a, 2b,…) which extend radially from the drive shaft (1), each working chamber (21) being closed by a cover, the radial piston pump being equipped with at least one retaining ring for fastening all of the covers of the radial piston pump. The invention also relates to a process for manufacturing a radial piston pump.

Description

[0001] The present invention relates to a radial piston pump, in particular a radial piston compressor, according to the preamble of claim 1, and to a method for producing a radial piston pump according to the preamble of claim 18, 19, 20 and / or 21.

[0002] A radial piston pump is a component of fluid technology. In this pump, also referred to as a pump based on the radial piston principle, the piston-working chamber combinations are arranged radially and perpendicular to the drive shaft, unlike an axial piston compressor. The delivery or reciprocating movement of each individual working piston is caused by an eccentric located on the drive shaft. Typically, the radial piston pump comprises several piston-working chamber combinations that extend radially from the drive shaft in a star-shaped pattern. The radial piston pump pumps a fluid from a low-pressure chamber to a high-pressure chamber.

[0003] Radial piston pumps are used, for example, as compressors for coolant in motor vehicle air conditioning systems, especially in electrically powered vehicles. A radial piston pump can also be referred to as a radial piston compressor or refrigerant compressor based on the radial piston principle.

[0004] The present invention relates to the improvement of a radial piston pump, in particular a refrigerant compressor based on the radial piston principle, whose stroke function is transmitted to the pistons by means of a circular eccentric. The valves for the gas exchange process in such a radial piston pump are preferably arranged as follows. The inlet valves are arranged radially with respect to the axis of rotation of the eccentric shaft, i.e., near the head side of the respective piston. The outlet valves, on the other hand, are preferably arranged axially, which offers advantages in terms of installation space and increases the design freedom for the inlet valves, in particular larger valve diameters, greater bending lengths, possibly multiple inlet valves, etc.

[0005] A radial piston pump further comprises a cover. The cover is designed, for example, as a pre-assembled subassembly and comprises, in addition to the cover, a seal, an inlet valve plate with a reed valve, and two fastening pins that hold the subassembly together. The inlet valve, in particular a valve plate with a reed valve, preferably lies in the base of a cylindrical recess above the working chamber on the pump body. The cover, preferably with a seal, presses from the outside onto the valve plate against the collar of the cylindrical recess. When the piston moves from the upper end position to the lower end position, a vacuum is created in the working chamber between the piston head and the cover, and the inlet valve opens into the working chamber, drawing in fresh gas.After the piston reaches bottom dead center (BDC), the piston moves upwards again, the inlet valve closes, and the fluid, particularly gas, in the working chamber is compressed. In CO2 compressors, for example, the pressure in the working chamber rises to up to 140 bar. Above the cover is the low-pressure area, whose pressure level is approximately 35 bar. This means that the cover, especially including the inlet valve, is pushed radially outward across the surface of the cover with a pressure differential of 140 - 35 bar.

[0006] The resulting compressive force must be absorbed by a suitable cover fastening. State-of-the-art technology, for example, secures the cover with screws, meaning one cover screw connection is provided for each cylinder unit. This screw connection requires additional radial space and incurs additional costs for parts and assembly.

[0007] A radial piston pump comprising a drive shaft with an eccentric, and at least one piston-working chamber combination, wherein the piston-working chamber combination comprises a working chamber and a piston, wherein the radial piston pump comprises at least two piston-working chamber combinations which extend radially from the drive shaft, wherein the radial piston pump is equipped with a housing which is designed to at least partially accommodate the piston-working chamber combinations, wherein each working chamber is closed with a cover, wherein the radial piston pump is equipped with at least one retaining ring for fixing all covers of the radial piston pump, is already known from CN 102 439 312 A.

[0008] Although a usable radial piston pump is already proposed here, there is still room for improvement.

[0009] This is where the present invention comes in and sets itself the task of providing an improved radial piston pump, in particular a radial piston pump is to be provided that can be assembled more easily and / or more quickly.

[0010] According to the invention, this object is achieved by a radial piston pump having the characterizing features of claim 1. This is achieved by equipping the radial piston pump with at least one retaining ring for securing all covers of the radial piston pump. The resulting advantages lie in particular in the fact that only one component is required to assume the holding force of the covers. This results in a reduction in the number of components and / or in a simplification of the components. A further possible advantage lies in the elimination of cost-intensive machining such as drilling and threading, as well as additional assembly steps such as screwing for each cylinder. This results in a reduction in manufacturing costs.

[0011] Further advantageous embodiments of the proposed invention emerge in particular from the features of the subclaims. The subject matter and features of the various claims can, in principle, be combined with one another in any desired way.

[0012] In an advantageous embodiment of the invention, the radial piston pump can comprise at least three, preferably six, piston-working chamber combinations arranged in a star configuration around the drive shaft. Accordingly, several piston-working chamber combinations can be driven by one drive shaft, in particular an eccentric shaft.

[0013] In a further advantageous embodiment of the invention, the piston-working chamber combinations can be accommodated in a pump base body. This allows a correspondingly compact design of the radial piston pump to be realized.

[0014] In a further advantageous embodiment of the invention, the cover can be provided with a contact surface for the retaining ring. A defined contact surface can be adapted to the inner surface of the retaining ring, in particular with regard to a suitable curvature and a corresponding adaptation to the diameter of the retaining ring, so that, for example, an advantageous positive connection or a sufficient interference fit can be achieved.

[0015] In a further advantageous embodiment of the invention, it can be provided that the cover and / or the pump body has a contact collar for the retaining ring, wherein the contact collar in particular has a radially extending surface as a stop for the retaining ring. The contact collar can serve as a stop for the retaining ring, for example, as a corresponding stop during assembly of the retaining ring. Furthermore, it can be ensured, for example, when the retaining ring is fully seated against the contact collar, that the cover(s) have the correct angular position.

[0016] In a further advantageous embodiment of the invention, the radial piston pump can be provided with at least two retaining rings for securing all covers of the radial piston pump, wherein the retaining rings are arranged axially one behind the other. In principle, it is preferred that the covers be secured by a single retaining ring. However, there may be a need for a larger number of inlets or inlet valves or for a special arrangement of an inlet or inlet valve, so that it may be advantageous to arrange the retaining rings around the inlet valve openings.

[0017] In a further advantageous embodiment of the invention, it can be provided that a press fit is provided between the retaining ring and the cover.

[0018] In a further advantageous embodiment of the invention, it can be provided that the inner diameter of the retaining ring has an inner diameter according to tolerance class IT 7 or IT 8.

[0019] It is intended that the radial piston pump is equipped with a housing which is designed to accommodate at least some of the piston-working chamber combinations.

[0020] According to the invention, it is provided that the retaining ring is integrated into the housing or at least one housing component, wherein the housing of the radial piston pump is formed from at least two housing components, namely a high-pressure housing and a stator housing for receiving a rotor and a stator of an electric motor.

[0021] In a further advantageous embodiment of the invention, it can be provided that the housing components are screwed together, in particular that the housing components are screwed together by means of a screw.

[0022] In a further advantageous embodiment of the invention, it can be provided that the pump base body has a flange which serves for screwing to the housing and / or the other housing components.

[0023] In a further advantageous embodiment of the invention, it can be provided that the housing components form fluid channels of the radial piston pump, or at least partial areas thereof.

[0024] In a further advantageous embodiment of the invention, it can be provided that the housing component has plane-parallel axial sealing surfaces.

[0025] In a further advantageous embodiment of the invention, it can be provided that the surfaces of the sealing surfaces of the housing component are provided with concentric grooves, in particular with a waviness in the radial direction.

[0026] In a further advantageous embodiment of the invention, it can be provided that seals are arranged additionally or solely between the sealing surfaces.

[0027] In a further advantageous embodiment of the invention, it can be provided that the surfaces of the sealing surfaces have one or more geometric shapes that deviate from a flat or approximately flat surface.

[0028] In a further advantageous embodiment of the invention, it can be provided that fluctuations in the distance between the housing components can be compensated by the elasticity.

[0029] A further object of the present invention is to propose advantageous methods for producing a radial piston pump according to the invention.

[0030] According to the invention, this object is achieved by a method according to claim 20, 21, 22 and / or 23.

[0031] Further features and advantages of the present invention will become clear from the following description of preferred embodiments with reference to the accompanying drawings. Fig. 1a radial piston pump without retaining ring in a sectional view; Fig. 1a an enlarged view of a portion of a radial piston pump according to Fig. 1; Fig. 1b: a plan view of a cover of a radial piston pump to illustrate its surface; Fig. 2: a schematic diagram of a piston-working chamber combination of a radial piston pump to illustrate its mode of operation; Fig. 2a: exemplary arrangements of inlet valve(s) and outlet valve(s) of a piston-working chamber combination of a radial piston pump; Fig. 2b: exemplary arrangements of inlet valve(s) and outlet valve(s) of a piston-working chamber combination of a radial piston pump; Fig. 3: a radial piston pump according to the invention in a sectional view; Fig. 4: a radial piston pump according to the invention in a perspective view; Fig. 5: an enlarged view of a partial area of ​​a radial piston pump according to the invention; Fig. 6: a further enlarged view of a partial area according to Fig. 5; Fig. 7-9 an enlarged representation of a partial area of ​​a radial piston pump according to the invention to illustrate assembly steps; Fig. 10 a schematic representation of the fluid flow in a partial area of ​​a radial piston pump; Fig. 11-13 a schematic representation of an assembly variant; Fig. 14-15 a schematic representation of an assembly variant; Fig. 16-18 a schematic representation of an assembly variant; Fig. 19 a retaining ring in a possible assembly position; Fig. 20 a schematic representation of a possible assembly position of two retaining rings; Fig. 21 a schematic representation of a possible assembly position of a retaining ring.

[0032] The following reference symbols are used in the figures: LLongitudinal axis FFluid WTool WHZHeatable tool SSwelding tool 1Drive shaft 2 (a - e)Piston-working chamber combination 3Pump body 4 (a)Retaining ring 5Support collar 6Housing 7High-pressure housing 8Stator housing 11Eccentric 21Working chamber 22Piston 23(a - e)Cover 24Inlet valve 25Exhaust valve 26Seal 27Flange 28Screw 41Slot 251Fluid outlet 252High pressure channel 241Fluid inlet 232Contact surface

[0033] Features and details described in connection with a method naturally also apply in connection with the device according to the invention, and vice versa, so that with regard to the disclosure of the individual aspects of the invention, reference is always made to each other. Furthermore, a method according to the invention that may be described can be carried out with the device according to the invention.

[0034] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the disclosure. As used herein, the singular forms "a" and "an" are intended to include the plural forms unless the context clearly indicates otherwise. It will also be understood that the terms "comprises" and / or "comprising," when used in this specification, specify the presence of the recited features, integers, steps, operations, elements, and / or components, but do not preclude the presence or addition of one or more other features, integers, 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.

[0035] First, Fig. 1 or 1a.

[0036] A radial piston pump essentially comprises a drive shaft 1 with an eccentric 11, as well as at least one piston-working chamber combination 2, which is accommodated in a pump body 3. To define the axial direction, a longitudinal axis L of the drive shaft 1 is in the Fig. 1 The piston-working chamber combination 2 essentially comprises a working chamber 21 and a piston 22. The working chamber 21 is closed on the piston head side with a cover 23.

[0037] Typically, the radial piston pump comprises at least two piston-working chamber combinations 2, 2a, 2b, ..., which extend radially from the drive shaft 1. Preferably, the radial piston pump comprises at least three, preferably six, piston-working chamber combinations 2, 2a, 2b, ..., which extend in a corresponding star shape from the drive shaft 1. Accordingly, each piston-working chamber combination 2, 2a, 2b, ... is provided with a cover 23, 23a, .... The piston-working chamber combinations 2, 2a, 2b, ... can be accommodated in a housing 6.

[0038] Furthermore, a fluid inlet 241 is provided in the cover 23 or at the head end of the working chamber 21. A fluid outlet 251 is also provided in the working chamber 21, preferably in the wall of the working chamber 21. The fluid inlet 241 is equipped with an inlet valve 24, which can selectively close or open the fluid inlet 241. The fluid outlet 251 is equipped with an outlet valve 25, which can selectively close or open the fluid outlet 251.

[0039] For example, in Fig. 10 As shown, the fluid F to be compressed flows via the fluid inlet 241 or the inlet valve 24 into the working chamber 21, is compressed there by the stroke movement of the piston 22 and leaves the working chamber 21 through the outlet valve 25 or the fluid outlet 251. The design of the valves, for example as a spring plate valve, is sufficiently known to the person skilled in the art and requires no further explanation here.

[0040] The Fig. 1aillustrates the acting system pressures and the pressure surfaces involved in the cover 23 arranged radially to the drive shaft 1. The cover 23 further comprises a seal 26. The inlet valve 24, in particular comprising a valve plate with a reed valve, rests in the base of a cylindrical recess above the working chamber on the pump base body 3. The cover 23 presses from the outside on the valve plate against the collar of the cylindrical recess. When the piston moves from the upper end position to the lower end position, a vacuum is created in the working chamber between the piston head and cover 23, and the inlet valve 24 opens into the working chamber, and fresh gas is drawn in. After the piston reaches bottom dead center (BDC), the piston 22 moves upward again, the inlet valve closes, and the gas in the working chamber is compressed. The compressed gas leaves the working chamber 21 accordingly through the fluid outlet 251 or outlet valve 25.

[0041] The Fig. 2 shows a schematic diagram of a piston-working chamber combination of a radial piston pump to illustrate its mode of operation, in particular the fluid flow from the fluid inlet 241 via the working chamber 21 into the fluid outlet 251 is shown here.

[0042] Fig. 2a shows a variant of a piston-working chamber combination 2 with two fluid inlets 251 or two inlet valves 24 and one fluid outlet 241 or outlet valve 25 and Fig. 2b shows a variant of a piston-working chamber combination 2 with fluid inlet 241 or one inlet valve and one fluid outlet 251 or one outlet valve 25.

[0043] The design of the other components and the functioning of a radial piston pump, such as the valves, which can be designed as spring plate valves, for example, is sufficiently known to the person skilled in the art and requires no further explanation here.

[0044] According to the invention, the radial piston pump is provided with at least one, preferably one, retaining ring 4 for securing all covers 23, 23a to 23e of the radial piston pump. In other words, it is particularly provided that the covers 23 (ae) of all piston-working chamber combinations 2 (ae) are secured simultaneously by means of only one common retaining ring 4. In particular, in the Fig. 3 and 4 This is shown using the example of a 6-cylinder radial piston compressor. Thus, the retaining ring 4 generates the necessary holding force to keep all covers 23 in position relative to the working chamber 21 or the pump body 3 under operating conditions.

[0045] It can further preferably be provided that the cover 23 and / or the pump body 3 has a contact collar 5 for the retaining ring 4. Such a contact collar 5 is, for example, in Fig. 6clearly visible and is designed, in particular, as a radially aligned surface. The contact collar 5 can be used to ensure the axial position of the retaining ring 4 on the pump base body 3 and / or cover 23. The contact collar 5 on the cover 23 preferably simultaneously fixes the angular position of the cover 23 relative to the pump base body 3 when the retaining ring 4 is mounted.

[0046] Furthermore, the cover 23 can be equipped with a contact surface 232 for the retaining ring 4. The retaining ring 4 can rest positively on such a contact surface 232. In particular, the combination of the contact collar 5 and the contact surface 232 can guide or ensure the position of the retaining ring 4 relative to the cover 23 as well as its angular position or concentricity to the pump's longitudinal axis, for example, in the joined state or even during assembly.

[0047] In order for the retaining ring 4 to counteract any possible cover movement, particularly due to pressure conditions, from the pump base body 3 outwards, the pairing of all covers 23 to the retaining ring 4 should have a press fit. This means that the outer diameter of all contact points of the contact surfaces 232 should be larger than the inner diameter of the retaining ring 4 at the same temperature. This press fit results in the retaining ring 4 - similar to a preloaded spring - fixing the cover 23 to the pump base body 3 with a defined holding force, preferably through a defined press fit of the retaining ring inner diameter to the cover contact surfaces, which ensures sufficient holding force of the cover 23 to the pump base body 3 at all operating points.

[0048] The Fig. 5 shows an enlarged view of a portion of a radial piston pump according to the invention.

[0049] As in the Figure 5As shown, it is provided that the radial piston pump is equipped with a housing 6, which is designed to at least partially accommodate the piston-working chamber combinations 2, 2a, 2b, .... Further preferably, it can be provided that the housing 6 of the radial piston pump is formed from at least two housing components, in particular a high-pressure housing 7, and / or a stator housing 8, in particular for receiving a rotor and a stator of an electric motor. According to the invention, it is provided that the retaining ring 4 is integrated into the housing 6 or at least one housing component 7, 8. In principle, it is provided that the housing component with integrated retaining ring and the other housing components form the housing of the radial piston pump. As further shown, it can be provided that the housing components are screwed together to form the pump housing.Preferably, the housing components are screwed together using a screw 28. For this purpose, the pump base body 3 may have a flange 27 or the like, which serves for screwing the other housing components.

[0050] Preferably, fluid channels of the radial piston pump, or at least portions thereof, can be formed by means of the housing parts screwed together. One such combined channel is, for example, the high-pressure channel 252.

[0051] The housing components can delimit or seal different pressure zones within the radial piston pump or to the outside. In a further advantageous embodiment of the invention, the housing component can be provided with plane-parallel axial sealing surfaces. Sealing surfaces designed in this way can provide a tight connection to the adjacent housing component, such as the high-pressure housing 7 or the stator housing 8.

[0052] In a further advantageous embodiment of the invention, the surfaces of the sealing faces of the housing component can be provided with concentric grooves, in particular with a waviness in the radial direction. The concentric groove(s) can further improve the sealing effect.

[0053] Furthermore, it can be provided that seals are arranged additionally or solely between the sealing surfaces.

[0054] In a further advantageous embodiment of the invention, the surfaces of the sealing surfaces can have one or more geometric shapes that deviate from a flat or approximately flat surface. For example, the sealing surfaces can have a concave or convex shape for the targeted formation of contact surfaces or linear contacts.

[0055] For example, a flat sealing surface of one housing component can be brought into contact with the convex surface of another housing component, thus forming a sealing surface. By bringing a flat and a convex surface into contact, a defined linear contact is advantageously formed between the two surfaces. Such linear contact can preferably fully or at least partially replicate the function of a seal between corresponding components. Advantageously, one of the surfaces can exhibit elastic behavior, so that fluctuations in the distance between the components can be compensated for by the elasticity.

[0056] The Fig. 6 shows a further enlarged view of a section according to Fig. 5 .

[0057] Furthermore, it is preferable for the retaining ring 4 to have a precisely machined inner diameter. The inner diameter of the retaining ring 4 should preferably be within tolerance class IT 7...8.

[0058] Furthermore, small tolerances should be maintained for the height of the cover 23, in particular with regard to the contact surface of the cover to the pump body and / or the contact surface 232 of the cover 23 to the retaining ring 4.

[0059] Preferably, sufficient compressive strength should be selected for the materials on which the contact pressure is generated, especially at the most critical contact point between the cover and the retaining ring.

[0060] Further details of the invention will become apparent in particular from a description of the assembly of a radial piston pump according to the invention, particularly with regard to the assembly of the retaining ring 4. It is understood that only a few selected assembly steps are shown here, as they are helpful for understanding the method according to the invention. The manufacture of the radial piston pump may include further steps or intermediate steps known to those skilled in the art.

[0061] The retaining ring 4 can be fixed, for example, by a thermal cross-press fit between the covers 23 and the retaining ring 4.

[0062] The retaining ring 4 is heated using a heat source or a heatable tool (WHZ) prior to assembly. The thermal expansion of the retaining ring 4 eliminates any overlap between the retaining ring 4 and the cover 23, enabling force-free joining. In the heated state, a radial clearance forms between the contact surface of the retaining ring 4 and the contact surfaces 232 of the cover 23, allowing the retaining ring 4 to be joined with virtually no force. After assembly, the retaining ring 4 cools down, and the overlap is restored, or due to the shrinkage of the diameter, a joint pressure is generated on all covers 23. The minimum joint pressure that occurs, particularly at each cover / retaining ring contact, should be large enough that the cover 23 does not lift off the pump body 3 at the maximum pressure difference between high and low pressure. Such a process is described in the Fig. 11 to 13shown schematically. During assembly of the retaining ring 4, the retaining ring 4 can be brought into contact or abutment against the contact collar 5.

[0063] The retaining ring 4 can be secured, for example, by a longitudinal press fit between the covers 23 and the retaining ring 4. The retaining ring 4 is pushed onto the cover 23 with an overlap. The retaining ring 4 stretches elastically. The overlap generates a force. Such a method is described in the Figs. 14 and 15 shown schematically. When sliding the retaining ring 4 onto the cover 23, the retaining ring 4 can also be brought into contact or abutment against the contact collar 5.

[0064] The retaining ring 4 can also be secured, for example, by a welded connection. The retaining ring 4 is preferably provided with a slot 41 or is designed as an open ring and is fitted over the covers 23, then clamped or compressed using a tool W, so that the retaining ring rests against all contact surfaces of the covers 23. In this state, the gap between the ring ends is approximately 2 mm. The welding process then takes place using a welding device S, which closes the slotted retaining ring (approx. 2 mm gap) by adding filler metal, in particular liquid metal. After the welding process, the filler material cools down, shrinks accordingly, and thus creates tensile stress in the retaining ring 4. The accuracy requirements for the retaining ring 4 or the covers 23 can be lower with this variant. Such a process is described in the Fig. 16 to 18shown schematically. During assembly of the retaining ring 4, the retaining ring 4 can be brought into contact or abutment against the contact collar 5.

[0065] In principle (not shown), however, it is also conceivable that the covers are elastically (radially) pressed "inward" using a device / tool ​​W before joining the retaining ring, thus providing a joining gap for the retaining ring for the duration of the joining process. If no gap is created, at least the overlap during assembly can be somewhat reduced. The advantage of this is that the thermal transverse interference fit could be eliminated (costs, temperature effect in the retaining ring, or impact on its structure). In addition, the sliding / joining force can be reduced compared to the "normal" or "longitudinal interference fit" described above. The procedure in principle:

[0066] This requires that the cover can elastically spring / deform (dashed line) to form a joint gap (at least in the area of ​​contact surface 232). This can be achieved geometrically by the cover 23 or its geometric design.

[0067] The figure shows (schematically): a tool W elastically presses or deforms the cover 23; in particular, the contact surface 232 elastically retreats / radially inward, so that a gap is formed or the overlap between the retaining ring and the cover 23 is reduced. After the tool is removed, the cover 23 or the contact surface 232 elastically springs back, so that an overlap is formed. To ensure that the tool does not get in the way when joining the retaining ring 4 and that the contact surface 232 can still reliably deform elastically, different geometric designs for the cover than those shown above are preferably selected.

[0068] In principle (not shown), the elastic behavior can also be achieved by an element arranged between the cover and the pump housing / cylinder housing. This must ensure tightness and thus prevent the cover from lifting off.

[0069] In the Fig. 19 to 21 Advantageous positions of the valves 24, 25 or inlet / outlet 251, 241 relative to the cover 23 are shown. For example, the fluid inlet 251 or the inlet valve 24 can be arranged off-center of the cover 23 to create space for the retaining ring 4. A reed valve, possibly with a stop, can be used as the valve 24, 25, for example.

[0070] Advantageous adjustments can be made, in particular, to the ring width or height, the ring material (pipe material, welded, drawn...), and the cover material (sintered material, forged material...). One or more retaining rings 4 can be used per radial piston pump, as in, for example, Fig. 20 Retaining rings 4 and 4a are shown. In this case, the retaining rings are preferably arranged axially one behind the other. Preferably, the retaining ring 4 can have a mounting bevel on the inside to simplify installation.

[0071] The radial piston pump proposed here can preferably be used as an air conditioning compressor, preferably driven by an electric motor. Accordingly, the fluid is preferably a refrigerant.

Claims

1. Radial piston pump, in particular a radial piston compressor, comprising - a drive shaft (1) with an eccentric (11), and piston-working-space combinations (2), each piston-working-space combination (2) comprising a working space (21) and a piston (22), - the radial piston pump comprising at least two piston-working-space combinations (2, 2a, 2b, ...) which extend radially from the drive shaft (1), the radial piston pump being provided with a housing (6) which is designed for at least partial accommodation of the piston-working-space combinations (2, 2a, 2b, ...), - each working space (21) being closed by a cover (23 (a-e)), wherein the radial piston pump is equipped with at least one retaining ring (4) for fixing all the covers (23 (a-e)) of the radial piston pump, characterised in that the retaining ring (4) is integrated into the housing (6), or the housing (6) of the radial piston pump is composed of at least two housing components, namely a high-pressure housing (7) and a stator housing (8) for receiving a rotor and a stator of an electric motor, and the retaining ring (4) is integrated into at least one housing component (7, 8).

2. Radial piston pump according to claim 1, characterised in that the radial piston pump comprises at least three piston-working-space combinations (2, 2a, 2b, ...) that are arranged star-shaped around the drive shaft (1).

3. Radial piston pump according to any one of the preceding claims, characterised in that the piston-working-space combinations (2, 2a, 2b, ...) are accommodated in a pump basic body (3).

4. Radial piston pump according to any one of the preceding claims, characterised in that the cover (23) has a contact surface (232) for the retaining ring (4).

5. Radial piston pump according to claim 3, characterised in that the cover (23) and / or the pump basic body (3) has an abutment collar (5) for the retaining ring (4), the abutment collar (5) having a radially extending surface acting as a stop for the retaining ring (4).

6. Radial piston pump according to any one of the preceding claims, characterised in that the radial piston pump has at least two retaining rings (4, 4a) for fixing all the covers (23 (a-e)) of the radial piston pump, the retaining rings (4, 4a) being arranged axially one behind the other.

7. Radial piston pump according to any one of the preceding claims, characterised in that an interference fit is provided between the retaining ring (4) and the cover (23).

8. Radial piston pump according to any one of the preceding claims, characterised in that the inside diameter of the retaining ring (4) corresponds to tolerance class IT 7 or IT 8.

9. Radial piston pump according to claim 3, characterised in that the housing (6) is configured for at least partial accommodation of the pump basic body (3).

10. Radial piston pump according to any one of the preceding claims, characterised in that the housing components (7, 8) are screwed to one another.

11. Radial piston pump according to claim 3, characterised in that the pump basic body (3) has a flange (27) that serves for screwing to the housing (6) and / or the further housing components (7, 8).

12. Radial piston pump according to any one of the preceding claims, characterised in that the housing components (7, 8) form fluid channels of the radial piston pump, or at least portions thereof.

13. Radial piston pump according to any one of the preceding claims, characterised in that the housing component (7, 8) has plane-parallel axial sealing surfaces.

14. Radial piston pump according to claim 13, characterised in that the surfaces of the sealing surfaces of the housing component are provided with concentric grooves.

15. Radial piston pump according to claim 13 or 14, characterised in that additionally or exclusively seals are arranged between the sealing surfaces.

16. Radial piston pump according to any one of the preceding claims, characterised in that the surfaces of the sealing surfaces have one or more geometrical forms deviating from a plane or approximately plane surface.

17. Radial piston pump according to any one of the preceding claims, characterised in that variations in the spacing of the housing components relative to one another can be compensated by elasticity.

18. Method for producing a radial piston pump according to any one of the preceding claims, characterised in that fixing of the retaining ring (4) is carried out by a thermal transverse shrink fit between the covers (23 (a-e)) and the retaining ring (4), comprising the following steps: - heating the retaining ring (4) before assembly, - placing the retaining ring (4) onto the covers (23 (a-e)), - cooling the retaining ring (4).

19. Method for producing a radial piston pump according to any one of the preceding claims, characterised in that fixing of the retaining ring (4) is carried out by a longitudinal interference fit between the covers (23 (a-e)) and the retaining ring (4), comprising the following steps: - pushing the retaining ring (4) with overlap onto the covers (23 (a-e)), - elastically expanding the retaining ring (4).

20. Method for producing a radial piston pump according to any one of the preceding claims, characterised in that fixing of the retaining ring (4) is carried out by a welded joint, comprising the following steps: - slitting the retaining ring (4) to create a slot, - placing the retaining ring (4) onto the covers (23 (a-e)), - tensioning the retaining ring (4), preferably by means of a tool (W), - closing the slot.

21. Method for producing a radial piston pump according to any one of the preceding claims, wherein the cover is designed to elastically flex and / or yield in order to form an assembly gap, at least in the region of the contact surface 232, characterised in that - before fitting the retaining ring, the covers are pressed elastically, radially inward by means of a device / tool (W) in order to provide an assembly gap for the retaining ring during fitting.

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