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 at least one, preferably a plurality of piston-working chamber combinations (13, 13a,... 13f) which are arranged radially about an eccentric shaft (11, 12), wherein each piston-working chamber combination (13) comprises a working chamber (131) with a piston (132) which is movably accommodated therein, wherein the piston (132) is driven by the eccentric shaft (11, 12), wherein the piston-working chamber combination (13) is provided with an inlet valve (19) and / or an outlet valve (18), wherein the working chamber (131) is provided with a cylinder head (15), wherein a cutout (20) is provided on the cylinder head (15) on the side of the working chamber (131), the piston (132) and / or the inlet valve (19).

Description

[0001] radial piston compressor

[0002] The present invention relates to a radial piston compressor according to the preamble of claim 1.

[0003] A radial piston compressor is a component of fluid power technology. In contrast to an axial piston compressor, in this type of compressor at least one piston-working chamber combination 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 caused by an eccentric. Therefore, the drive shaft can also be referred to as an eccentric shaft. A radial piston compressor typically comprises several piston-working chamber combinations radiating outwards from the drive shaft or eccentric shaft in a star-shaped pattern.

[0005] A piston-working chamber combination 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 the side facing the eccentric shaft. During the rotation of the eccentric shaft, the eccentric disk contacts or rests against this surface. 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 refrigerants in the air conditioning systems of motor vehicles, especially in electric vehicles. A refrigerant such as R744 (CO2) can be used as the medium to be compressed. However, other media and refrigerants are also conceivable.

[0007] Radial piston compressors, which operate on the piston principle, have inlet and / or outlet valves, usually designed as reed valves. An axial or radial arrangement of the valve channels or their valve openings relative to the piston is known, for example. DE 102020208699 A1, for instance, discloses a radial piston compressor in which the valve opening of the outlet valve is aligned axially, i.e., at 0° with respect to the longitudinal axis of the eccentric shaft. In other words, the valve opening of the outlet valve is aligned radially to the piston or the piston's longitudinal axis.

[0008] To keep the diameter of a radial piston compressor as small as possible, a radial arrangement of the exhaust valves is advantageous, in which the compressed gas is directed laterally away from the cylinder area.

[0009] However, this arrangement can lead to increases in velocity and pressure (squish flow) in the area of ​​the piston's top dead center, with negative effects on the efficiency and achievable mass flow of the radial piston compressor.

[0010] The present invention addresses this issue and aims to propose an improved radial piston compressor, in particular a radial piston compressor that overcomes, or at least reduces, the disadvantages outlined above. Specifically, the invention proposes a radial piston compressor that exhibits no or only minimal velocity and pressure increases (squish flow) in the region of the piston's top dead center and / or that avoids or at least minimizes negative effects on the efficiency and achievable mass flow rate of the radial piston compressor.

[0011] According to the invention, this problem is solved by a radial piston compressor with the characterizing features of claim 1. By providing a clearance on the cylinder head on the working chamber side and / or on the piston and / or the inlet valve, the disadvantages outlined above can be overcome, or at least mitigated.

[0012] The purpose of this relief is to increase the available flow cross-section in the region of top dead center (TDC). The advantage is that the resulting lower cylinder pressures during exhaust reduce the resulting exhaust losses. This can particularly improve the efficiency of the radial piston compressor.

[0013] If an overpressure remains in the cylinder chamber after top dead center (TDC) compared to the high-pressure area, the mass flow can also be affected by the squish flow. By clearing the flow path, the exhaust stroke can be completed more quickly at higher engine speeds, thus improving the volumetric efficiency at high speeds. The proposed measure according to the invention can also reduce the flow velocities and thus the noise emission into the compressed medium. Without the measure according to the invention, the flow path is highly dependent on the resulting head clearance and thus on the clearances and tolerances in the piston mechanism. The proposed measure according to the invention simplifies manufacturing.

[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 eccentric shaft may comprise a drive shaft and an eccentric disc. The drive shaft is driven by the drive unit. Upon rotation, the eccentric disc comes into contact, directly or indirectly, with the piston base and displaces the piston within the working chamber. The medium in the working chamber can then be compressed.

[0016] In a further advantageous embodiment of the invention, the exhaust valve may comprise a valve channel, wherein the valve channel has an inlet opening on the working chamber side in the wall of the working chamber. Accordingly, a lateral inlet opening for the valve channel can be implemented. In conjunction with a corresponding clearance, for example in the piston crown, only a slight increase in velocity and pressure (squish flow) in the region of the piston's top dead center can be achieved, or possibly even completely avoided.

[0017] In a further advantageous embodiment of the invention, the valve channel of the outlet valve can be aligned axially or parallel to the drive shaft. A valve channel provided laterally in the wall of the working chamber can advantageously be equipped at its end with the associated inlet opening in the working chamber. With appropriate alignment, flow losses can be further minimized.

[0018] In a further advantageous embodiment of the invention, the inlet valve may comprise a valve plate with a valve tongue, wherein the valve plate is mounted on the cylinder head or between the cylinder head and the working chamber. The valve plate itself may be provided with a relief, for example in the form of a recess in the valve plate. Manufacturing such a recess in the valve plate is technically simple and can be carried out during, for example, the stamping process of the valve plate.

[0019] In a further advantageous embodiment of the invention, the relief can be designed as a cutout in the valve plate. As already described above, the cutout in the valve plate is a possible embodiment of the relief that is easy to implement from a manufacturing perspective. It is even conceivable, in principle, to replace a conventional valve plate in an already operating radial piston compressor with a valve plate featuring a relief.

[0020] In a further advantageous embodiment of the invention, the relief can be designed as a recess in the piston crown of the piston. This is also an embodiment of the relief. The relief in the piston and the relief in the valve plate can, in principle, be combined.

[0021] In a further advantageous embodiment of the invention, it can be provided that the valve plate is not arranged in a plane with the outlet valve, in particular that it is arranged parallel to the outlet valve.

[0022] In a further advantageous embodiment of the invention, it can be provided that the valve plate is arranged orthogonally to the outlet valve.

[0023] 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

[0024] Fig. 1 shows a radial piston compressor according to the invention in a side-cut view;

[0025] Fig. 2 shows a radial piston compressor according to the invention in a cutaway view from the front;

[0026] Fig. 3 shows a detail of a radial piston compressor according to the invention, in particular the inlet and outlet valves;

[0027] Fig. 4 shows a valve plate of an inlet valve for a radial piston compressor according to the invention, in particular with an additional cutout on the valve plate, in a perspective view;

[0028] Fig. 5 shows a piston for a radial piston compressor according to the invention, in particular a piston with a recess in the piston roof, in a perspective view;

[0029] Fig. 6 shows a cylinder head for a radial piston compressor according to the invention in a perspective view;

[0030] Fig. 7 shows an exploded view of a detail of a radial piston compressor according to the invention;

[0031] Fig. 8 shows a detail of a radial piston compressor according to the invention.

[0032] The following reference symbols are used in the illustrations:

[0033] R axis of rotation

[0034] K Piston axis

[0035] 1 compressor unit

[0036] 2 Drive unit

[0037] 11 Drive shaft 2 Eccentric disc 3 Piston-working chamber combination 4 - free - 5 Cylinder head 6 Compressor housing 7 Compressor housing cover 8 Exhaust valve 9 Inlet valve 0.20' Relief, in particular cutout, recess 1 Drive housing

[0038] 121 eccentric bearings

[0039] 131 Workspace

[0040] 132 pistons

[0041] 133 Transmission element

[0042] 181 Valve channel

[0043] 182 Valve tongue

[0044] 1321 Piston roof

[0045] 1811 Entrance opening

[0046] 1812 Outlet opening

[0047] 191 Valve channel

[0048] 192 Valve tongue

[0049] 193 Valve plate

[0050] 1911 Outlet opening. 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 the disclosure regarding the individual aspects of the invention always refers to each other or can refer to each other. Furthermore, any method described according to the invention can be carried out with the device according to the invention.

[0051] 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" are intended to include the plural forms unless the context otherwise makes clear. It will 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.

[0052] First, reference is made to Figures 1 and 2.

[0053] 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 compressor housing 16, and a compressor housing cover 17. Other housing configurations are also conceivable.

[0054] 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 an axis of rotation D. The compressor unit comprises at least one piston-working chamber combination 13, preferably several piston-working chamber combinations 13, 13a, 13b... 13f, arranged radially around the drive shaft 11. The piston-working chamber combination 13 can also be described as having a star-shaped arrangement around the drive shaft 11. The piston-working chamber combination 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. The working chamber 131 is equipped with a cylinder head 15 at the head end.The working chambers 131 of the piston-working chamber combinations 13 can be formed at least partially from the compressor housing 16.

[0055] 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 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.

[0056] 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.

[0057] As mentioned above, the working chamber 131 is closed at the head end by a cylinder head 15. Furthermore, the working chamber 13 has a circumferential wall.

[0058] It can also be seen in Fig. 3 that the radial piston compressor is equipped with an outlet valve 18. The outlet valve 18 is preferably designed as a spring-loaded valve. The outlet valve essentially comprises a valve channel 181, which can be selectively closed or opened, in particular by a valve tongue 182. The valve channel has an inlet opening 1811 on the working chamber side in the wall of the working chamber 131 and an outlet opening 1812. Other valve types are also conceivable. It is further provided that the valve channel 181 is aligned axially, i.e., parallel to the drive shaft 11. With this arrangement, the compressed medium can be discharged laterally from the working chamber 131.

[0059] It can also be seen in Fig. 3 that the radial piston compressor is equipped with an inlet valve 19. The inlet valve 19 is preferably designed as a spring-loaded valve. The inlet valve 19 essentially comprises a valve channel 191, which can be selectively closed or opened by a valve tongue 192. The valve tongue 192 can be part of a valve plate 193, which is inserted, for example, between the cylinder head 15 and the working chamber 131. The valve channel 191 has an outlet opening 1911 on the working chamber side. It is further provided that the valve channel 191 is oriented radially to the drive shaft 11. Preferably, the inlet valve 19 is provided in the cylinder head 15. With this arrangement, the medium to be compressed can be introduced into the working chamber 131 from above.

[0060] Particular reference is made below to Figures 4 and 5.

[0061] According to the invention, a clearance 20 is provided in or on the cylinder head 15 on the side of the working chamber 131 and / or on the piston 132.

[0062] Figure 4 shows a valve plate 193 of an inlet valve 19 with an additional cutout 20 on the valve plate 193. The valve plate 193 forms, among other things, the valve tongue 192 of the inlet valve 19 and is attached to the cylinder head 15 or between the cylinder head 15 and the working chamber 131. Here, the cutout 20 on the cylinder head 15 is formed by the cutout in the valve plate 193. The cutout is preferably oriented with the exhaust valve port 181, analogous to a recess in a piston (see especially Figures 7 and 8). However, it is also conceivable that the cutout is provided directly on the valve plate 193.

[0063] Figure 5 shows a detail of a piston 132 with a recess 20. It can be seen that the recess in the piston is designed as a bowl 20' in the piston crown 1321 of the piston 132. The bowl 20 is approximately semicircular in shape.

[0064] Figure 7 shows in particular the arrangement of the inlet valve 19, the relief 20 in the valve plate, with a relief as a recess 20' in the piston crown 1321, wherein the recess 20' and the relief 20 of the valve plate are arranged in the direction of the valve channel 181 and the outlet opening 1812 of the outlet valve from the working chamber, respectively. This allows, in particular, a squish flow to be achieved when the compressed fluid / refrigerant is expelled.

[0065] Fig. 8 shows, in particular, the arrangement and position of the components and openings or cutouts relative to each other in a top view. The valve channel 191 and the working chamber-side opening 1911 are shown here with dashed lines. The working chamber 131, or the piston 132, is designed with a cutout as a recess 20'. A valve plate 193 of the inlet valve 19 with valve tongue 192 and the cutout 20 is also visible. The preferred orientation of the components, or the radial piston compressor components, relative to each other is also shown. The recess 20' and the cutout 20 are preferably aligned in the same direction, namely towards the inlet opening 1811 of the outlet channel 181 from the working chamber 131.

Claims

Claims 1. 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 at least one, preferably a plurality of piston-working chamber combinations (13, 13a, ... 13f) arranged radially around an eccentric shaft (11, 12), wherein each piston-working chamber combination (13) comprises a working chamber (131) with a piston (132) slidably received therein, wherein the piston (132) is driven by the eccentric shaft (11, 12), wherein the piston-working chamber combination (13) is equipped with an inlet valve (19) and / or an outlet valve (18), wherein the working chamber (131) is equipped with a cylinder head (15), characterized in that a clearance (20) on the cylinder head (15) is provided on the side of the working chamber (131) and / or on the piston (132) and / or the inlet valve (19).

2. Radial piston compressor according to claim 1, characterized in that the eccentric shaft comprises a drive shaft (11) and an eccentric disk (12).

3. Radial piston compressor according to at least one of the preceding claims, characterized in that the outlet valve comprises a valve channel (181), wherein the valve channel (181) has a working chamber-side inlet opening (1811) in the wall of the working chamber (131).

4. Radial piston compressor according to at least one of the preceding claims, characterized in that the valve channel (181) of the outlet valve (181) is aligned axially or parallel to the drive shaft (11).

5. Radial piston compressor according to at least one of the preceding claims, characterized in that the inlet valve (19) comprises a valve plate (193) with a valve tongue (192), wherein the valve plate (193) is attached to the cylinder head (15) or between the cylinder head (15) and the working chamber (131).

6. Radial piston compressor according to at least one of the preceding claims, characterized in that the release is designed as a cutout (20) in the valve plate (193).

7. Radial piston compressor according to at least one of the preceding claims, characterized in that the clearance (20) is designed as a recess in the piston roof (1321) of the piston (132).

8. Radial piston compressor according to at least one of the preceding claims, characterized in that the valve plate (193) is not arranged in a plane with the outlet valve (18), in particular is arranged parallel to the outlet valve (19).

9. Radial piston compressor according to at least one of the preceding claims, characterized in that the valve plate (193) is arranged orthogonally to the outlet valve (18).

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