WO2008014736A1

WO2008014736A1 - Device for coupling a piston to an annular disc

Info

Publication number: WO2008014736A1
Application number: PCT/DE2007/001077
Authority: WO
Inventors: Marc Hohmann
Original assignee: Ixetic Mac Gmbh
Priority date: 2006-07-29
Filing date: 2007-06-19
Publication date: 2008-02-07
Also published as: EP2049796B1; DE112007001657A5; ATE460586T1; DE502007003098D1; EP2049796A1

Abstract

A device for coupling a piston to an annular disc (1), in particular to a captive C-washer/swash plate or to a pivot ring of the working unit of a reciprocating-piston machine, preferably of a compressor of the air-conditioning system of a motor vehicle, having a piston bridge (2) which is assigned to the piston and sliding shoes (3) which act between the annular disc (1) and the piston bridge (2), wherein the piston bridge (2) engages at least partially around or over the annular disc (1) and is in sliding engagement with the annular disc (1) by means of the sliding shoes (3), is characterized in that the sliding shoes (3) form, on the side facing towards the annular disc (1), around their actual sliding face (4) and towards the annular disc (1), an outer gap (5) which encircles the sliding face (4) and which serves to receive and store lubricant.

Description

Device for coupling a piston to an annular disc

The invention relates to a device for coupling a piston to an annular disc, in particular to a swivel / swash plate or to a swivel ring of the working unit of a reciprocating engine, preferably a compressor of the air conditioning system of a motor vehicle, with a piston associated with the piston bridge and between the annular disc and the piston bridge acting sliding blocks, wherein the piston bridge at least partially encompasses or overlaps the annular disc and is in sliding engagement with the annular disc via the sliding shoes.

The generic device is commonly used in reciprocating engines, which are known for many years in a variety of designs and for various uses. Such a reciprocating engine can be, for example, a compressor, for example a compressor for the air conditioning system of a motor vehicle. Such compressors are also commonly referred to as air conditioning compressors and include a housing which includes an externally driven compressor unit. The compressor unit designed, for example, as an axial piston machine, in turn, comprises a plurality of pistons, which can be moved back and forth in a cylinder block. Upon rotation of a swash plate usually formed as an annular disc or when pivoting a corresponding swash plate, the pistons are moved back and forth. The housing is usually closed.

Schwenkscheibenkompressoren or swing ring compressors are well known in a variety of designs. For example only, reference is made to DE 4 441 721 A1 and to DE 100 10 142 C 2.

With regard to further constructive details, reference is made to DE 197 49 727 C2.

In the known from DE 197 49 727 C2 reciprocating a circular, ring-like swash plate, also called swivel ring, is provided, which is adjustable in its inclination to the machine shaft. The swashplate is driven for rotation by the machine shaft. This is done via a slide body guided axially on the machine shaft and via a driving pin arranged at a distance from the machine shaft. The pistons have joint arrangements with which the swash plate is in sliding engagement. Specifically, the known reciprocating engine comprises a working unit with a plurality of correspondingly driven pistons, wherein the pistons are guided in cylinder bores and follow through special coupling elements of the pivoting / tumbling motion of the annular disc and thus perform their stroke.

The generic device used in the known reciprocating engine usually includes sliding blocks, which are problematic especially in the use of C0 ₂ compressors, due to the high pressures and pressure differences occurring there. So most sliding shoes tend to seize on the ring disc or on its sliding surface. In addition, the shoe is insufficiently supplied with lubricant, so that increased wear takes place. In addition, a lack of lubricant leads to increased operating noise.

The present invention is therefore based on the object, a device for coupling a piston to an annular disc, in particular to a swivel / swash plate or to a swivel ring of a working unit of a reciprocating engine, preferably a compressor of the air conditioning of a motor vehicle, namely a device of the gattunsbil- denden Art to design and further develop that the problems of lubrication occurring in the prior art are largely eliminated. Furthermore, a shoe for a corresponding device should be specified. Finally, a reciprocating engine to be specified with a corresponding device in which the aforementioned problems are also eliminated.

The above object is solved by the features of claim 1. Thereafter, the generic device is characterized in that the sliding blocks on the side facing the annular disc around its actual sliding surface, towards the annular disc out, form an outer, the sliding surface circumferential gap, which serves for receiving or storing lubricant.

Furthermore, the above object is achieved by the features of the independent claims 26 and 27, using a device according to the invention. According to the invention, it has been recognized that it is advantageous for the sliding property of the sliding shoe when a special measure for receiving or storing lubricant is provided there.

Specifically, on the side facing the annular disc of the sliding block, around the actual sliding surface, an outer gap is provided which surrounds or revolves the sliding surface. This gap is made sufficiently flat relative to the surface of the annular disk, so that due to the resulting capillary effect, a lubricant reservoir is formed, in which the lubricant can collect due to capillary forces.

It should be noted at this point that the term "sliding surface" does not necessarily mean a self-contained surface which comes to rest on the surface of the annular disc. Rather, the sliding surface is defined by regions of the sliding shoe, wherein intermediate spaces can be filled with lubricant ,

Advantageously, the shoe is at least slightly resilient. Due to the resilient property of the sliding block, it can be stronger under load or pressed against the surface of the annular disc, thereby increasing the contact area. When springing back lubricant may first flow into the circumferential gap, wherein the volume formed in the gap increases at least slightly.

The sliding block may be made of metal, preferably of steel and / or of aluminum. It is also conceivable that the sliding shoe is surface-coated, preferably by means of plastic.

In a particularly advantageous manner, the shoe is made of plastic, possibly with additives or inclusions in the sense of a composite material, in an ideal manner by means of injection molding. A sliding shoe made of plastic has the great advantage that - per se - it has a lower mass than a sliding block made of metal, in particular of steel. Thus, a plastic shoe already considered by itself reduces the noise generated during operation due to the low mass. The injection molding production of a sliding shoe made of plastic has the further advantage that no machining is required for its production. On the contrary, the shoe can be manufactured by injection molding to final dimensions. It is possible to increase the margin of tolerance for the game between shoe, swivel ring and piston, namely by using a termoplastischen material.

In terms of design, it is advantageous if the sliding surface of the circumferential gap is designed as an annular gap. Thus, a rotationally symmetrical design would be created on the one hand of the annular gap and on the other hand, the sliding surface.

The gap surrounding the sliding surface-annular gap-can be formed by a shoulder protruding from the sliding shoe or from the sliding surface or by a corresponding elevation, wherein this shoulder or the elevation can likewise be annular. Thus, the annular gap is predetermined on the one hand by the outer contour of the shoe and on the other hand by the paragraph.

In particular, with respect to the sliding property and the supply of the sliding surface with lubricant, it is advantageous if the sliding surface has an at least slightly inwardly directed recess, a recess or the like, wherein the sliding surface may be concave thereto. Of particular advantage in this respect is an inwardly directed curvature, which forms an inner depot for lubricants.

With a purposeful concavity of the sliding surface of the shoe can deflect under load. This creates a larger effective contact surface with the annular disc. When springing back, a volume is formed - almost in the sliding surface - into which a sufficient amount of lubricant can flow. A kind of inner capillary effect thus promotes the transport of lubricant in the region of the sliding surface, so that a perfect run and thus a noise reduction and wear reduction is realized.

It should be emphasized at this point that the inner concavity after spring-back generates a hydrodynamic lubricant film structure, due to the oblique surface defining the concavity. The concavity, that is, the inward chamfer, can range from 0.01 mm to 0.05 mm. This ensures that sufficient lubricant is collected or stored in the region of the annular gap using the outer capillary effect. In particular, in a relief of the shoe an inner capillary effect acts with a concavity in the range of preferably 0.01 mm to 0.05 mm, so that springs back in the suction phase of the shoe and increases the inner volume in the sliding surface. Lubricant is sucked in from the outer annular gap and passes directly into the area of the sliding surface.

It is also conceivable that instead of a concave an at least slightly convex design of the sliding surface is provided, that is, an outward curvature. Again, sufficient lubricant from the annular gap in the area of the sliding surface succeeded, whereby the lubricant is displaced under load.

Regardless of a concave or convex configuration of the sliding surface, it is further advantageous if lubrication grooves are formed in the sliding surface, which extend inwards from the outer annular gap and are at least partially open in the sliding surface. The provision of the lubrication grooves also avoids seizing the sliding surface on the surface of the sliding ring. In addition, a sufficient amount of lubricant is transported through the lubrication grooves in the inner region of the sliding surface. The lubrication grooves can be partially open or closed. An overall open design of the lubrication grooves is particularly advantageous with regard to a simple construction / production, so that the lubrication grooves open overall in the sliding surface or are designed to be open from the outset.

The lubrication grooves may extend radially inwardly from the annular gap, it being conceivable that they end at a distance from the center, so that they do not influence one another. It is also conceivable that the lubrication grooves have an H-shaped arrangement in the sliding surface. Any other embodiments are possible, it being ensured that sufficient lubricant passes through the Schmiemuten in the region of the sliding surface of the shoe.

The lubrication grooves may have an approximately rectangular cross section with a substantially flat groove bottom. It is also conceivable that the lubrication grooves about V-shaped cross-section have tapered groove bottom. A part-circle or part-type core-like cross section with a curved or arcuate groove bottom is also conceivable.

Furthermore, it is advantageous if a continuous bore is formed in the sliding shoe, which produces a flow connection between the sliding surface and the piston bridge or the pan facing surface of the sliding shoe. Such a continuous bore, if possible arranged centrally, effectively avoids a fixed eye of the shoe on the surface of the annular disc, in particular during spring back of the shoe. Thus, the through hole communicates with both sides of the shoe, which also in this respect a transport of lubricant is possible.

On the side facing the piston bridge, the sliding shoe is equipped in a further advantageous manner with a spherical segment surface for engagement in a pan associated with the piston bridge with correspondingly adapted geometry. There, too, lubricant is used, and it is of far-reaching advantage if the radius of the spherical segment surface deviates at least slightly from the radius of the inner wall of the cup. Specifically, the radius of the spherical segment surface may be at least slightly smaller or slightly larger than the radius of the pan, resulting in different systems and power relationships between the shoe and the piston bridge or the pan. A firm eye between the two components is effectively avoided due to the different radii.

With the independent claim 26, a shoe according to the above statements is claimed, which is for use in a device for coupling a piston to an annular disc, in particular to a swivel / swash plate or to a swivel ring of the working unit of a reciprocating engine, is used.

With the further independent claim 27, a reciprocating engine is claimed, comprising a device according to the invention and thus also a sliding shoe according to the invention. In the drawing show

1 in a schematic side view, cut, a first embodiment of a device according to the invention,

2 shows a schematic side view, cut away, of a second embodiment of a device according to the invention,

Fig. 3 is a schematic view, from below, an embodiment of a shoe and

Fig. 4 in a schematic view, from below, another embodiment of a shoe.

1 and 2 show two different embodiments of a device for coupling a piston, not shown in the figures, to an annular disc 1, which is merely indicated in FIGS. 1 and 2. In concrete terms, the annular disc 1 is a swivel / swash plate or a swivel ring of the working unit of a reciprocating piston engine, as is known, for example, from DE 197 49 727 C2. With regard to details relating to this, reference is expressly made to DE 19749 727 C2.

The device comprises a piston bridge 2 assigned to the piston, and sliding shoes 3 acting between the annular disc 1 and the piston bridges 2, wherein for the sake of simplicity only a part of the piston bridge 2 and a single sliding block 3 are shown. It should be noted in addition that the piston bridge 2, the annular disc 1 partially engages over and that the piston is not shown on the sliding blocks 3 in sliding engagement with the annular disc 1.

According to the invention form the sliding blocks 3 on the side facing the annular discs 1, to the actual sliding surface 4 around, to the annular disc 1 out, an outer, the sliding surface 4 circumferential gap 5, which serves for receiving or storing lubricant. The shoe 3 is made of plastic in the embodiments chosen here and has resilient properties. Specifically, the shoe 4 is produced by injection molding.

1 and 2 further show that the sliding surface 4 circumferential gap 5 is designed as an annular gap. FIGS. 3 and 4 show this particularly clearly.

In the embodiment shown in Fig. 1 of the sliding surface circumferential gap 5 has a projecting from the shoe 3 and the sliding surface 4 paragraph 6, wherein the paragraph 6 also has annular configuration. Thus, the annular gap 5 is defined or limited by the outer contour of the sliding block 3 and by the annular shoulder 6.

The embodiment shown in Fig. 1 can further recognize that the sliding surface 4 has a concave configuration, that is, an inwardly directed curvature. This curvature also serves as a lubricant reservoir, wherein the inner space 7 thus formed during the unloading of the shoe 3, that is, the spring back of the shoe 3, fully sucks with lubricant, which is sucked from the region of the annular gap 5 in the inner space 7. The concavity is for example in the range between 0.01 mm to 0.05 mm.

In the exemplary embodiment shown in FIG. 2, the sliding surface 4 is convex, thus enclosing an outward curvature. Regardless, the sliding surface 4 is surrounded even in the embodiment shown in FIG. 2 by an annular gap 5 from which lubricant can flow into the area below the sliding surface 4 or laterally of the sliding surface 4, namely in particular when the sliding block 3 relieves is and the gap increases laterally or under the sliding surface 4 during the return spring of the shoe 3.

FIGS. 3 and 4 show exemplary embodiments of a sliding shoe 3, namely in a view from below, that is to say seen from the annular disk 1. From the annular gap 5, lubrication grooves 8 extend into the region of the sliding surface 4, so that a sufficiently good supply of lubricant is ensured. In addition, the lubricating grooves 8 ensure that a firm eye of the shoe 3 is effectively avoided. While in the embodiment shown in Fig. 3, the lubrication grooves 8 extend radially toward the center, the lubrication grooves 8 shown in Fig. 4 are arranged in an H-shape. Any other arrangements are conceivable, with always a flow connection to the annular gap 5 is provided. The lubrication grooves 8 may have a different cross section, for example rectangular cross sections, rounded walls, V-shaped cross sections, etc.

Again, reference is made to Figs. 1 and 2, this time on the annular disc 1 opposite side of the shoe 3, namely in relation to the interaction between shoe 3 and piston bridge. 2

Thus, the sliding block 3 comprises, on the side facing the piston bridge 2, a spherical segment surface 9 for engagement in a cup 10 assigned to the piston bridge 2 with a correspondingly adapted geometry.

In the embodiment shown in Fig. 1, the radius of the spherical segment surface 9 is slightly smaller than the radius of the pan 10, so that a small gap 11 is in the unloaded state.

In the embodiment shown in Fig. 2, the spherical segment surface 9 has a slightly larger radius than the pan 10, so that a clearance between the piston bridge 2 and the shoe 3 is made, also in the unloaded state. A spring back of the shoe 3 in relief of the shoe 3 avoids a mutual suction of the components, so that even in so far the sliding property is favored quite considerably.

With regard to features which can not be inferred from the figures, reference is made to avoid repetition to the general part of the description. Finally, it should be noted that the embodiments discussed above are for the purposes of discussion of the claimed teaching, but not for the purpose of limiting the embodiments. LIST OF REFERENCE NUMBERS

Ring disc Piston bridge Sliding shoe Sliding surface (of the sliding shoe) Slit, annular gap Paragraph Inner space Lubrication groove Ball segment surface Cup Gap (between piston bridge and sliding shoe) Convex design of the sliding surface 4

Claims

claims

1. A device for coupling a piston to an annular disc (1), in particular to a swivel / swash plate or to a swivel ring of the working unit of a reciprocating engine, preferably a compressor of the air conditioning system of a motor vehicle, with a piston associated with the piston bridge (2) and between the Ring disc (1) and the piston bridge (2) acting sliding shoes (3), wherein the piston bridge (2) the annular disc (1) at least partially encompasses or overlaps and on the sliding blocks (3) in sliding engagement with the annular disc (1) , characterized in that the sliding shoes (3) on the side facing the annular disc (1) around its actual sliding surface (4), towards the annular disc (1), form an outer, circumferential, the sliding surface (4), the gap for receiving or Storage of lubricant is used.

2. Apparatus according to claim 1, characterized in that the sliding block (3) is at least slightly resilient.

3. Device according to claim 1 or 2, characterized in that the sliding shoe (3) made of metal, preferably made of steel and / or aluminum.

4. Device according to one of claims 1 to 3, characterized in that the sliding shoe (3), preferably by means of plastic, total or partial, is surface-coated.

5. Apparatus according to claim 1 or 2, characterized in that the sliding shoe (3) made of plastic, preferably by injection molding, is made.

6. Device according to one of claims 1 to 5, characterized in that the sliding surface (4) circumferential gap (5) is designed as an annular gap (5).

7. Device according to one of claims 1 to 6, characterized in that the sliding surface (4) encircling gap (5) by a sliding shoe (3) or from the sliding surface (4) projecting shoulder (6) is formed.

8. Apparatus according to claim 7, characterized in that the shoulder (6) is annular.

9. Device according to one of claims 1 to 8, characterized in that the sliding surface (4) has an at least slight inwardly directed recess, a recess or the like ..

10. Device according to one of claims 1 to 9, characterized in that the sliding surface (4) has an at least slight concave formation, i. an inward curvature (7), has.

11. The device according to claim 10, characterized in that the concavity is 0.01 to 0.05 mm.

12. Device according to one of claims 1 to 9, characterized in that the inwardly extending from the annular gap (5) sliding surface (4) has an at least slight convexity (12), i. an outward curvature, has.

13. Device according to one of claims 1 to 12, characterized in that the sliding surface (4) with respect to the annular gap (5) protrudes by about 0.05 to 0.5 mm.

14. Device according to one of claims 1 to 13, characterized in that in the sliding surface (4), lubrication grooves (8) are formed which extend from the outer annular gap (5) inwardly and in the sliding surface (4) are at least partially open ,

15. Device according to one of Ansprüchel to 13, characterized in that in the sliding surface (4) Schmiemuten (8) are formed, which extend from the outer annular gap (5) inwardly and in the sliding surface (4) are open.

16. The device according to claim 15 or! 6, characterized in that the lubrication grooves (8) extend radially inwardly from the outer annular gap (5).

17. The apparatus according to claim 16, characterized in that the lubrication grooves (8) at a distance from the center of the sliding surface (4) end.

18. The apparatus according to claim 14 or 15, characterized in that the lubrication grooves (8) have an H-shaped arrangement in the sliding surface (4).

19. Device according to one of claims 14 to 18, characterized in that the lubrication grooves (8) have an approximately rectangular cross section with a substantially flat groove bottom.

20. Device according to one of claims 14 to 18, characterized in that the lubrication grooves (8) have an approximately V-shaped cross-section with tapered groove bottom.

21. Device according to one of claims 14 to 18, characterized in that the lubrication grooves (8) have a part-circular or partially elliptical cross-section with a curved or arcuate groove bottom.

22. Device according to one of claims 1 to 21, characterized in that in the sliding shoe (3) has a through hole is formed, which faces a flow connection between the sliding surface (4) and the piston bridge (2) or the pan (10) Surface of the shoe (3) produces.

23. Device according to one of claims 1 to 22, characterized in that the sliding shoe (3) on the piston bridge (2) side facing a spherical segment surface (9) for engaging in a piston bridge (2) associated with pan (10) with corresponding has adapted geometry.

24. The device according to claim 23, characterized in that the radius of the spherical segment surface (9) of the radius of the pan (10) at least slightly different.

25. The apparatus of claim 23 or 24, characterized in that the radius of the spherical segment surface (9) is at least slightly smaller than the radius of the pan (10).

26. The apparatus of claim 23 or 24, characterized in that the radius of the spherical segment surface (9) is at least slightly larger than the radius of the pan (10).

27. Sliding shoe (3) for a device for coupling a piston to an annular disc (1), in particular to a swivel / swash plate or to a swivel ring of the working unit of a reciprocating piston engine, preferably a compressor of the air conditioning a motor vehicle, with a piston associated with the piston bridge (2) and between the annular disc (1) and the piston bridge (2) sliding shoes (3), wherein the piston bridge (2) the annular disc (1) at least partially um- or ü - is aligned and on the sliding blocks (3) in sliding engagement with the annular disc (1), characterized by the features according to one of the claims 1 to 26.

28. A reciprocating piston machine having a device for coupling a piston to an annular disc (1), in particular to a swivel or swash plate or to a swivel ring of the working unit of the reciprocating piston engine, preferably a compressor of the air conditioning system of a motor vehicle, having a piston bridge associated with the piston (2). and between the annular disc (1) and the piston bridge (2) acting sliding shoes (3), wherein the piston bridge (2) at least partially surrounds the annular disc (1) and over the sliding shoes (3) in sliding engagement with the annular disc ( 1), characterized by the features according to one of the claims 1 to 26.