Piston compressor, in particular radial piston compressor or axial piston compressor

Abstract

The invention relates to a piston compressor, in particular a radial piston compressor, comprising a compressor unit (2) and a drive device (1), wherein the compressor unit (2) is provided with at least one piston-working chamber combination (21), wherein the at least one piston-working chamber combination (21) comprises a working chamber (211) and a piston (212) which is movably accommodated in the working chamber (211) and is driven by the drive device (1), wherein the at least one piston-working chamber combination (21) is provided with at least one valve device (8, 9), wherein the valve device (8, 9) comprises a valve plate (81) with a valve tongue (812), wherein the valve tongue (812) is arranged with at least one bridge element (811) on the valve plate (81), wherein the valve plate (81) is arranged on a support surface (83), wherein the valve device (8, 9) further comprises a valve channel (82) with a valve channel opening (821) in the support surface (83), wherein the valve tongue (812) is optionally designed to open or close the valve channel opening (821), wherein the support surface (83) is provided with at least one recess (831) which is at least partially covered, preferably fully covered, by the at least one bridge element (811).

Description

[0001] Piston compressors, in particular radial piston compressors or axial piston compressors

[0002] The present invention relates to a piston compressor, in particular a radial piston compressor or an axial piston compressor, with an inlet valve and / or an outlet valve according to the preamble of claim 1.

[0003] A piston compressor is an element of fluid technology and is used to compress compressible media, such as refrigerants.

[0004] A special type of piston compressor is the so-called radial piston compressor. The piston compressor can also be referred to as a reciprocating piston compressor.

[0005] A radial piston compressor essentially comprises a compressor unit and a drive unit. The compressor unit includes at least one piston-working chamber combination, preferably several piston-working chamber combinations. The piston-working chamber combination includes a working chamber, also called a cylinder, with a piston that is movable within the working chamber.

[0006] The drive unit, for example, drives a drive shaft with an eccentric, the eccentric being able to contact the piston to move the piston within the working chamber and compress the medium in the working chamber. Preferably, the radial piston compressor is equipped with several piston-working chamber combinations extending radially, in particular in a star shape, from the axis of rotation of the drive shaft.

[0007] 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.

[0008] 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.

[0009] The piston compressor, in particular the at least one piston-working chamber combination, is further equipped with at least one valve assembly in the form of an inlet valve and / or outlet valve, which controls the charge exchange of the medium to be compressed. The valve assembly generally comprises a valve channel with a valve channel opening in a support surface and a valve plate arranged on the support surface with a valve tongue. The valve tongue is configured to selectively close or open the valve channel opening. The valve tongue is connected to the valve plate via at least one valve bridge, preferably two valve bridges. Ultimately, the valve bridges act like leaf springs and press the valve tongue into a closed valve position, in which the valve bridges are flush with the support surface and the valve tongue is positioned above the valve channel opening. To open the valve channel opening, the valve tongue lifts away from the valve channel opening.In this case, the valve stems bend slightly and lift off the contact surface.

[0010] Such valve devices are generally actuated by the applied pressure differentials. Prior art has shown that a portion of oil is always present in the compressor along with the circulating refrigerant. This oil film collects between the valve stems and the contact surface, is compressed when the valve closes, and generates adhesive forces (the "stick effect") that cause the valve to open with a delay. This delayed opening negatively impacts the pressure profile, volumetric efficiency, and noise level of the compressor.

[0011] The invention is therefore based on the objective of proposing an improved piston compressor, in particular a radial piston compressor, and in particular a piston compressor in whose valve arrangement the sticking effect outlined above is minimized and thereby a spontaneous or earlier valve opening at low pressure ratios can be enabled.

[0012] According to the invention, this problem is solved by a piston compressor with the characterizing features of claim 1. By providing the bearing surface with at least one recess that is at least partially, preferably completely, overlaid by the at least one valve stem, the wetted contact area can be significantly reduced, so that less lubricating oil accumulates during closing, the sticking effect is reduced, and the valve reed opens at a lower pressure differential. This improves the volumetric efficiency of the piston compressor. Furthermore, noise that may be indirectly attributable to the opening or closing of the valve assembly can be reduced. In particular, the noise reduction can result from an optimized force profile within the compressor unit. This effect can arise especially from the altered pressure profile when the valve opens with a reduced pressure differential.This significantly reduces the excitation of the mechanical components, leading to an effective reduction in operating noise.

[0013] 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.

[0014] In an advantageous embodiment of the invention, the valve tongue can be connected to the valve plate via two valve bridges, and a single recess is jointly projected by both valve bridges. This results in a symmetrical spring characteristic with minimal machining effort, which improves the uniformity of the valve stroke and the component stiffness.

[0015] In a further advantageous embodiment of the invention, two separate recesses may be provided, each of which is overlaid by a valve bridge. This allows the contact surface for each valve bridge to be individually adjusted, thus compensating for manufacturing tolerances and further reducing local adhesive forces.

[0016] In a further advantageous embodiment of the invention, the recess(s) can be produced by removing material from the bearing surface to create a relief. This enables cost-effective manufacturing with high dimensional accuracy without the need for additional components or joining processes.

[0017] In a further advantageous embodiment of the invention, the valve assembly can optionally serve as an inlet valve and / or an outlet valve. This results in a unified valve concept that reduces the number of parts and simplifies assembly.

[0018] In a further advantageous embodiment of the invention, the valve assembly, designed as an inlet valve, can be arranged in the cylinder head. This results in a particularly short flow path from the inlet channel to the working chamber, thereby reducing pressure losses and improving cylinder filling.

[0019] In a further advantageous embodiment of the invention, the recess and valve plate can be arranged on the side of the cylinder cover facing away from the working chamber. This shields the valve components from the hot or high-flowing medium, thus increasing their service life and operational reliability.

[0020] In a further advantageous embodiment of the invention, the valve channel can be provided to completely penetrate the cylinder head and connect the working chamber directly to the valve channel opening. This reduces flow resistance while minimizing dead volume and thermal losses.

[0021] In a further advantageous embodiment of the invention, the recess can be dimensioned such that the adhering oil film between the valve stem and the contact surface is effectively reduced during closing. This avoids opening delays, which increases the efficiency of the compressor, particularly at high operating frequencies.

[0022] In a further advantageous embodiment of the invention, the recess can have a different depth along its length. This allows the contact surface along the valve stem to be selectively modulated, so that spring stiffness and damping can be optimally adjusted.

[0023] In a further advantageous embodiment of the invention, the shape and / or arrangement of the recess can be adapted to the geometry of the associated valve stem. This ensures a uniform load distribution on the valve stem, which reduces material fatigue and stabilizes the switching characteristics.

[0024] In a further advantageous embodiment of the invention, it can be provided that, to further reduce the adhesion effect, at least one of the parameters oil viscosity, surface roughness of the contact surface, or gap geometry between the valve bridge and the contact surface is specifically adjusted. This allows the remaining adhesive film to be minimized even further, thereby improving the valve dynamics and reducing the energy consumption of the compressor.

[0025] In a further advantageous embodiment of the invention, the recess in the section projecting beyond the valve stem can be wider than the valve stem itself. This design reliably prevents the valve stem from bearing directly on the support surface in this area. In this way, the wetted contact area between the valve stem and the support surface is significantly reduced, resulting in less lubricating oil accumulating in the closed state and effectively preventing the formation of adhesive forces. This allows the valve to open at lower pressure differentials, thereby improving valve dynamics, increasing volumetric efficiency, and simultaneously reducing noise.Furthermore, the reduced alternating stress on the valve stems leads to a longer service life of the valve assembly and thus contributes to increased efficiency and operational reliability of the piston compressor. Further features and advantages of the present invention will become clear with reference to the following description of preferred embodiments and the accompanying figures. The elements or features of the various embodiments can, in principle, be combined with one another as desired. These show:

[0026] Fig. 1 shows a piston compressor according to the invention, in particular a radial piston compressor, in a cutaway side view;

[0027] Fig. 2 shows a piston compressor according to the invention, in particular a radial piston compressor, in a cutaway perspective detail view;

[0028] Fig. 3 shows an embodiment of a valve device, in particular an inlet valve, for a radial piston compressor according to the invention in a top view;

[0029] Fig. 4 shows an embodiment of a valve device according to Fig. 3, but without the valve plate for illustrative purposes;

[0030] Fig. 5 shows a further embodiment of a valve device, in particular an inlet valve, for a radial piston compressor according to the invention in a top view;

[0031] Fig. 6 shows an embodiment of a valve device according to Fig. 5, but without a valve plate for illustrative purposes.

[0032] Fig. 7 shows a piston compressor according to the invention, in particular an axial piston compressor, in a cutaway side view;

[0033] Fig. 8 shows an embodiment of a valve device according to Fig. 9, but without the valve plate for illustrative purposes;

[0034] Fig. 9 shows a further embodiment of a valve device, in particular an inlet valve, for an axial piston compressor according to the invention in a top view;

[0035] Fig. 10 shows an embodiment of a valve device according to Fig. 11, but without the valve plate for illustrative purposes;

[0036] Fig. 11 shows a further embodiment of a valve device, in particular an inlet valve, for an axial piston compressor according to the invention in a top view;

[0037] Fig. 12 shows another embodiment of a valve cover for a radial piston compressor according to the invention in a top view.

[0038] The following reference symbols are used in the illustrations:

[0039] 1 Drive unit

[0040] 2 compressor units

[0041] 3 Drive shaft 4 Eccentric

[0042] 5 Piston guide ring

[0043] 6 transmission element

[0044] 7 cylinder heads

[0045] 8 Valve assembly / Inlet valve

[0046] 9 Valve assembly / Exhaust valve

[0047] 10 troughs

[0048] 11 Rotor

[0049] 12 Stator

[0050] 13 Drive housings

[0051] 21 piston-working chamber combination

[0052] 22 compressor housings

[0053] 40 Swashplate

[0054] 41 Cover plate

[0055] 81 Valve plate

[0056] 82 Valve channel

[0057] 83 contact area

[0058] 211 Workspace

[0059] 212 pistons

[0060] 811 Valve bridge

[0061] 812 Valve tongue

[0062] 821 Valve channel opening

[0063] 831 Exclusion

[0064] 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.

[0065] 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.

[0066] First, particular reference is made to Fig. 1 and Fig. 2.

[0067] Figures 1 and 2 show a radial piston compressor in a side sectional view and a sectional top view, respectively. A radial piston compressor essentially comprises a drive unit 1 and a compressor unit 2. In the exemplary embodiment presented here, the compressor unit 2 has at least one piston-working chamber combination 21. The piston-working chamber combination 21 comprises a working chamber 211, which can also be referred to as a cylinder, and a piston 212 slidably mounted in the working chamber 211, which moves up and down within the working chamber 211. The working chamber 211 is generally closed at the top end by a cylinder cover 7.

[0068] The drive unit 1 is preferably designed as an electric motor and comprises a stator 12 and a rotor 11. The rotor 11 drives a drive shaft 3 with an eccentric 4, which can accordingly also be referred to as an eccentric shaft. The piston 212 has a contact surface on its side facing the eccentric shaft, against which the eccentric 4 strikes or rests during the rotation of the drive shaft 3. The impact of the eccentric 4 on the contact surface causes an upward movement of the piston 212 and thus the compression of a medium located in the working chamber 211.

[0069] The piston 212 can also be equipped with a transmission element 6, preferably made of plastic, which can be arranged between the eccentric 4 and the piston 212. This transmission element 6 transmits the stroke of the eccentric 4 to the piston 212. The return movement of the piston 212 can be effected by a piston guide ring 5, so that the piston 212 returns to bottom dead center (BDC) until the eccentric 4 again contacts the piston crown or the transmission element 6, and the piston 212 moves towards its top dead center (TDC).

[0070] The radial piston compressor preferably comprises more than one piston-working chamber combination 21, in particular six piston-working chamber combinations 21, extending radially, especially in a star-shaped pattern, from the axis of rotation of the drive shaft 3. Radial piston compressors are used, for example, for compressing refrigerants in air conditioning systems of motor vehicles, especially also in electrically powered motor vehicles. CO2 is suitable, for example, as a medium to be compressed; other media are also conceivable. The design and operation of a radial piston compressor are known to those skilled in the art and are therefore not explained in detail. A piston compressor, in particular 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.

[0071] The radial piston compressor, in particular the piston-working chamber combination 21, is equipped with an inlet valve 8 and an outlet valve 9. The valves 8 and 9 regulate the exchange of the medium to be compressed in the working chamber 211. The inlet valve 8 can, for example, be located in the cylinder head 7. The outlet valve 9 can, for example, be located in the wall of the working chamber 211. However, other arrangements are also conceivable. A valve assembly, as described in more detail below, is suitable for both the inlet valve 8 and the outlet valve 9.

[0072] A valve assembly essentially comprises a valve plate 81, a valve channel 82, and a bearing surface 83. The valve plate 81 is preferably made of a metallic sheet. However, other materials, such as plastics, are also conceivable.

[0073] The valve channel 82 is in fluidic communication with the working chamber 211. The valve channel 82 opens at one end with its valve channel opening 821 into the support surface 83, and at the other end into the associated working chamber 211. The valve plate 81 comprises a valve tongue 812, which is connected to the valve plate 81 via at least one valve web 811, preferably two valve webs 811. The valve tongue 812 is arranged upstream of the valve channel opening 821. The valve webs 811, acting like leaf springs, press the valve tongue 812 against the valve channel opening 821. If there is a sufficient pressure difference between the working chamber 211 and the surroundings of the valve assembly, the valve tongue 812 can be lifted from the valve channel opening 821, thus releasing the valve channel opening 821 and allowing the medium to flow through the valve channel 82. The valve stems 811 are deformed by spring elasticity when the valve assembly is opened.When the valve assembly is closed, they can rest on and / or against the support surface 83 and are elastically deformed when the valve assembly opens, i.e., when the valve tongue lifts from the valve channel. The valve tongue 812 comprises a wider and a narrower section, so that one can speak of a kind of waisting and / or constriction.

[0074] According to the invention, the contact surface 83 is provided with at least one recess 831 which is overlooked at least partially, preferably completely, by the at least one valve web 811.

[0075] Preferably, the recess 831 is wider than the valve stem 811, so that contact between the valve stem 811 and the bearing surface 83 is avoided in this area. Preferably, the recess 831 also extends along the valve stem 811 (see especially Fig. 5).

[0076] Figures 3 and 4 show an embodiment with a recess 831 and two valve ribs 811. It can be seen how the two valve ribs 811 overlap the recess 831. No, or at least extremely minimal, adhesive forces can act on the valve ribs 811 that would otherwise result from an accumulation of lubricant between the valve rib 811 and the bearing surface 83 when the valve ribs 811 lift off. Therefore, the valve can open even at small pressure differentials, which significantly reduces charge exchange losses, dead volume increases, and noise emissions.

[0077] Figures 5 and 6 show a further embodiment with two recesses 831 and two valve bridges 811. Ultimately, each valve bridge 811 is assigned a separate recess 831.

[0078] The exemplary embodiments shown here are valve assemblies used as inlet valves 8 of the radial piston compressor. In this example, the inlet valve 8 is located in the cylinder head 7 of the respective piston-working chamber combination 21. The valve channel 82 is located in the cylinder head 7. In this embodiment of the valve assembly, the bearing surface 83 is located on the cylinder head 7. The bearing surface 83, and thus also the valve plate 81, is located on the side of the cylinder head 7 facing the working chamber 211. The recess 831 is located in the cylinder head 7 in this embodiment of the valve assembly. The valve assembly sketched above can also be used as an outlet valve 9. Figures 7 to 11 show some details of this, using an axial piston compressor as an example.

[0079] Essentially, the axial piston compressor comprises a swashplate 40, which performs the function of the eccentric 4 in the radial piston compressor sketched above. The swashplate 40 is mounted on the drive shaft 3 and is rotated by the piston 212. This actuates the pistons 212 of the piston-working chamber assemblies 21. The working chambers 211 of the piston-working chamber assemblies 21 are covered by a common cover plate 41, in which the inlet valves 8 and the outlet valves 9, or rather their port openings, are located. The valve assemblies sketched above are configured here as inlet valves 8.

[0080] In this embodiment of the valve assembly, the contact surface 83 is located on the cover plate 41. The contact surface 83, and thus also the valve plate 81, is located on the side of the cover plate 41 facing the working chamber 211. The recess 831 is located in the cover plate 41 in this embodiment of the valve assembly.

[0081] In principle, the invention is not limited to the embodiments outlined above. Rather, variations are conceivable without deviating from the inventive idea, in particular with regard to the number and arrangement of the valve webs 811, the shape, depth, width or direction of the recess 831, the geometry of the valve tongue 812, the material or thickness of the valve plate 81, possible coatings of the bearing surface 83, the position of the valve channel 82 and its valve channel opening 821, the design of the transmission element 6, and the installation positions of the valve assemblies 8, 9 within the cylinder cover 7 or the compressor housing 22. Likewise, several recesses 831 of different contours can be provided, or the valve plate 81 and bearing surface 83 can be designed as separate, interchangeable inserts, without departing from the scope of protection of the invention.The inlet valve 8 and / or outlet valve 9 of the compressor according to the invention, in particular radial piston compressors or axial piston compressors, can also be equipped as a valve assembly with the at least one recess 831 as sketched above, which is at least partially, preferably completely, overlaid by the at least one valve web 811. It should also be noted that the effective contact area under the valve web is preferably reduced so that the respective valve preferably opens automatically even at a nearly pressureless state (Ap ~ 0); this minimizes charge exchange losses and improves the noise characteristics of the compressor.To fine-tune this opening characteristic, in addition to the geometry and depth of the recess, the viscosity of the circulating lubricating oil, the surface roughness of the contact area, and the remaining gap geometry can be specifically varied to further reduce the remaining adhesive forces. The combination of these measures noticeably increases the volumetric efficiency and is equally applicable to compressors with valves, especially piston, radial, and axial piston compressors, as well as to inlet and outlet valves.

[0082] It may be provided that the recess 831 is produced by removing material from the bearing surface 83, in particular in the form of a cutout.

[0083] Particular reference is made below to Fig. 12.

[0084] In addition to the recess(s) 831, a recess 10 may also be provided in the inlet valve cover 7. The recess 10 may perform different functions than the recess(s) 831, for example, to clear the cylinder cover 7 in the area of ​​an exhaust port.

Claims

Claims 1. Piston compressor, in particular radial piston compressor or axial piston compressor, comprising a compressor unit (2) and a drive unit (1), wherein the compressor unit (2) is equipped with at least one piston-working chamber combination (21), wherein the at least one piston-working chamber combination (21) comprises a working chamber (211) and a piston (212) movably mounted in the working chamber (211), which is driven by the drive unit (1), wherein the at least one piston-working chamber combination (21) is equipped with at least one valve assembly (8, 9), wherein the valve assembly (8, 9) comprises a valve plate (81) with a valve tongue (812), wherein the valve tongue (812) is arranged on the valve plate (81) with at least one valve web (811), wherein the valve plate (81) is arranged on a support surface (83), wherein the valve assembly (8,9) further comprising a valve channel (82) with a valve channel opening (821) in the support surface (83), wherein the valve tongue (812) is optionally configured to open or close the valve channel opening (821), characterized in that the support surface (83) is provided with at least one recess (831) which is projected at least partially, preferably completely, by the at least one valve web (811).

2. Piston compressor according to claim 1, characterized in that the valve tongue (812) is connected to the valve plate (81) via two valve bridges (811), wherein the bearing surface (83) has a single recess (831) which is jointly, at least partially, projected over by both valve bridges (811).

3. Piston compressor according to claim 1, characterized in that the valve tongue (812) is connected to the valve plate (81) via two valve bridges (811), wherein the bearing surface (83) has two spaced-apart recesses (831), each recess (831) being overlaid, at least partially, by one of the valve bridges (811).

4. Piston compressor according to one of the preceding claims, characterized in that the recess (831) or recesses (831) is produced by removing material from the bearing surface (83), in particular in the form of a clearance.

5. Piston compressor according to one of the preceding claims, characterized in that the valve assembly (8, 9) forms the inlet valve (8) and / or the outlet valve (9).

6. Piston compressor according to claim 5, characterized in that the valve assembly designed as an inlet valve (8) is arranged in a cylinder cover (7) of the piston-working chamber combination (21).

7. Piston compressor according to one of the preceding claims characterized in that the recess (831) or recesses (831) and the valve plate (81) are arranged on the side of the cylinder cover (7) facing away from the working chamber (211).

8. Piston compressor according to one of the preceding claims, characterized in that the valve channel (82) passes through the cylinder cover (7) and connects the working chamber (211) directly to the valve channel opening (821).

9. Piston compressor according to one of the preceding claims, characterized in that the at least one recess (831) is dimensioned and arranged such that when the valve assembly (8, 9) is closed, the adhering oil film between the valve bridge (811) and the contact surface (83) is effectively reduced.

10. Piston compressor according to one of the preceding claims, characterized in that the at least one recess (831) has a different depth over its extent.

11. Piston compressor according to one of the preceding claims, characterized in that the shape and / or arrangement of the at least one recess (831) are varied to be adapted to the geometry of the associated valve bridge (811).

12. Piston compressor according to one of the preceding claims, characterized in that at least one of the following parameters is specifically adjusted to further reduce the adhesion effect: • Oil viscosity of the lubricating oil circulating in the compressor, • Surface roughness of the bearing surface (83) or • Gap geometry between valve stem (811) and contact surface (83).

13. Piston compressor according to one of the preceding claims, characterized in that the recess (831) in its section projecting over the valve bridge (811) is wider than the valve bridge (811) in its width.

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