DE102008040455B4 - axial piston - Google Patents

Abstract

Axial piston compressor based on the swash plate principle, in which several pistons (3) are arranged around a central axis of symmetry (7) and can be moved parallel to this axis of symmetry in corresponding cylinder bores (2), the pistons (3) fixed to support structures (12, 12) ', 12' ') which limit rotation of the pistons (3) about their respective central axis (11) by supporting them on an adjacent component, characterized in that the support structures (12, 12', 12 '') are designed in this way are that the main component of the resulting support force acts with respect to the central axis of symmetry (7) in each case in the radial direction and the extent of the support structures (12, 12 ', 12' ') in the tangential direction is so great that the support structures (12, 12 ', 12' ') of adjacent pistons (3) at least partially overlap or support structures (12, 12', 12 '') of a piston (3) each extend into the area of an adjacent piston.

Description

The invention relates to an axial piston compressor whose construction requires a smooth and quiet operation.

STATE OF THE ART

Axial piston compressors are used as particularly compact and powerful compression elements in a wide variety of applications, where effective and largely constant pressurization of fluids is required. This is especially true for use in various compression circuits of air conditioners in motor vehicles.

In this case, a noise is sought, which does not noticeably exceed at least other operating noise of the vehicle. From an energetic point of view, moreover, a minimization of the noise is always sought, as this would otherwise convert the mechanical energy supplied to the air conditioner in an unusable and unacceptable extent in sound energy and dissipate. Furthermore, in principle, frictional effects are to be avoided or minimized, which would reduce the service lives of the assemblies concerned by way of wear associated therewith, or would be associated with increased expenditure for the regular replacement of various wearing parts.

The operating principle of axial piston compressors is based in many cases on the use of so-called swashplates, swashplates or rings or swash plates or rings, hereinafter referred to as swashplates, which are movably associated with pistons, often as part of rotationally symmetrical multi-piston arrangements. The pistons are guided guided in cylinder bores, which run parallel to the axis of symmetry. The movement of the piston leads to the desired compression effect of the arrangement. The movement of the pistons occurs when, during a proper relative movement of the swash plate, for example by rotation of the swash plate about the axis of symmetry of the piston assembly, the distance of the connecting portion between the swash plate and the respective piston to the cylinder bores having housing part varies, resulting in a hub-shaped forced movement of the Piston in the cylinder bores leads. The type of relative movement between the swash plate and the piston causes the occurrence of torques on the movable piston, which can not be used.

For structural reasons, the connecting region between the swash plate and the individual pistons is preferably designed in the form of a piston calotte, which receives corresponding bearing devices, for example in the form of pivotable piston shoes, in order to realize a movable and partially positive connection between the swash plate and the pistons. The piston calotte surrounds the edge of the swash plate in the shape of a claw (for example in the form of a so-called piston bridge).

One of the impressed torques acts around the longitudinal axis of the piston. Without compensation of this torque, there would be a rotation of the piston about its longitudinal axis until the piston bridge would come into contact with the swash plate, which would destroy the arrangement in the worst case, but would in any case severely impair the operation by a very unfavorable friction behavior. In the case of the use of piston bridges, it is therefore imperative to compensate for this impressed torque. In order not to impair the movement of the piston in the cylinder or not to subject the cylinder wall to excessive wear, the functionally required torque support is usually in the range of the piston calotte or piston bridge.

Piston calipers and piston bridges are therefore designed so that they can not be rotated arbitrarily about the longitudinal axis of the piston, which contributes to the prevention of unwanted contacts between relatively movable parts. The required compensation of the impressed torque nevertheless takes place via the contact with modules, which performs a relative movement with respect to the respective piston bridge, but in contact points or contact areas designed in a constructive manner.

Since the torque to be compensated is impressed in a friction-mediated manner, it depends primarily on the force with which the piston is pressed against components whose relative movement with respect to the axis of symmetry of the piston has a rotational component. These components can be found in the storage devices in the field of piston shoes. The contact force, which allows the impression of the torque to be compensated, results from the resistance that the piston opposes the lifting movement. This resistance results from the gas pressure applied to the piston, from frictional forces that occur between the piston and the cylinder wall, and from inertial forces that occur during the acceleration of the piston in the course of a stroke. It follows that the torque to be compensated significantly with the operating pressure of increased compressing fluid. This aspect is gaining in importance, in particular in the field of vehicle air conditioning systems, since carbon dioxide-based refrigerants are used to a greater extent there, which is associated with significantly higher operating pressures than conventional air conditioning systems.

Various ways are known of reducing the torque impression by optimizing the frictional properties of the components used in the connecting area between the piston and the swash plate ( DE 199 55 103 A1 . DE 10 2006 008 437 A1 ). However, these measures do not replace compensation of impressed torques, since their occurrence basically, in the described dependence on the respective contact force, remains.

Requirements in terms of weight savings require in the compressor area a frequent use of housings or housing parts made of aluminum. The choice of material for the pistons may require steel materials due to the operating loads that occur. In a direct support of the piston to such housing parts made of aluminum, which is a common solution for the compensation of the impressed torque, sliding zones form out, in which steel slides on aluminum, which protects the steel piston components, in contrast, in the contact area between the piston and housing results in a partial considerable abrasion of aluminum particles. As a result, grooves or other changes in shape may occur in the housing, which may affect the sliding behavior of the piston and due to a progression of the abrasive phenomena may cause a deterioration of the torque compensation. Remedy can provide in these cases, only a time-consuming periodic replacement of the worn housing parts.

Another disadvantage of increased aluminum abrasion is due to the property of aluminum to form on its surface in oxidative environment very quickly a thin and very solid oxide layer. Due to the sometimes very high pressures and / or temperatures occurring in the event of wear, particularly hard crystalline phases can also arise. As a result, the abrasion particles originating from the housing wall are immediately coated with a layer of aluminum oxide and thus become a very aggressive abrasive, which leads to an increase in wear on all moving parts of the compressor. Furthermore, generates the friction between the piston and housing, in addition to the aforementioned wear effects, vibrations of the compressor housing, which are emitted as airborne sound and audible as an unwanted Verdichterferziehungsweise compressor noise. The noise is a frequently criticized disadvantage of known axial piston compressors according to the prior art.

It is known to realize a rotation of the piston over relatively large contact surfaces. In this case, a suitably shaped piston bridge is largely surrounded by a complementary groove, in which it moves in a sliding manner ( DE 102 61 884 A1 ). Any such design requires clearance to allow for the necessary sliding action, ultimately leading to uneven loading of the contact surfaces with all the disadvantages associated therewith.

It is known to mitigate the problems presented by the required for the compensation of the impressed torque support in contact areas, which provide a favorable leverage, whereby the force required for torque compensation contact pressure is relatively low. For this purpose, for example, T-shaped rotation boundaries are known whose beam length determines the lever ratio ( DE 197 46 896 A1 ). This approach is set constructive limits in conventional compressor arrangements, since support elements of corresponding extent can reach as far as possible to the support elements of the adjacent piston. The described problem persists in a weakened form.

Axial piston machines with piston bridge solutions are known in which adjacent piston bridges have contact surfaces which are provided for mutual support in the tangential direction. This eliminates the need for support at corresponding sliding zones of the housing. A disadvantage of such arrangements, however, is that the support to some extent takes place against "fleeing" surfaces, which, taking into account a required minimum clearance between the individual piston bridges and associated deflections can lead to clamping effects, which would affect the ease of the compressor assembly. Such solutions are therefore at best suitable for symmetrical double-piston arrangements ( DE 196 42 021 A1 . DE 195 27 645 A1 ).

The object of the invention is to provide an axial piston, which is distinguished from the prior art by a low wear, low noise and low running resistance, and requires no increased effort to its production.

DISCLOSURE OF THE INVENTION

The essence of the invention is to provide the pistons of an axial piston compressor with support structures that extends into the region of the respective support structure of the respectively adjacent piston and overlaps them. The overlap overcomes the structural limitation of previous solutions, according to which support elements can extend as far as possible to the support elements of the adjacent piston in their extension. Is carried out by so designed and overlapping arranged support structures a support on the housing wall of a suitably designed compressor, so can at least the length of effective for compensating the impressed torque lever arm over the prior art significantly increase, resulting in a reduction of friction and abrasion and associated with this results in a reduction of the noise.

The invention consists in particular in an axial piston compressor according to the swash plate principle, in which a plurality of pistons are arranged about a central axis of symmetry, which can be moved parallel to this axis of symmetry in corresponding cylinder bores, wherein the pistons are fixedly connected to support structures which rotate the pistons about their respective central axis by support on an adjacent component limit, wherein the support structures are designed so that the main component of the resulting upon rotation of the piston supporting force with respect to the central axis of symmetry acts in the radial direction and the extension of the support structures in the tangential direction is so large that the support structures of adjacent pistons at least partially overlap or support structures of a piston each extend into the region of an adjacent piston. The main component of the resulting support force is to be understood as the largest force component in terms of magnitude that results when the support force is divided into a radial and a tangential component.

The overlap is advantageously realized in that in a radially symmetrical arrangement, the support structures in the vicinity of the housing surrounding the piston assembly and are at least partially arranged at different distances with respect to their distance from the central axis of symmetry of the arrangement or have a distance gradation.

EMBODIMENTS OF THE INVENTION

In embodiments, the invention is explained in more detail below. Show it:

1 a schematic representation of a piston in an axial piston compressor;

2 a schematic plan view of an exemplary piston bridge in section;

3 a schematic sectional view through a seven-cylinder axial piston compressor;

4 a schematic sectional view through a seven-cylinder axial piston with inventively designed support structures;

5 a schematic partial processing of the piston assembly;

6 a schematic sectional view through a seven-cylinder axial piston compressor with particularly advantageous designed support structures;

7 a schematic sectional view through a seven-cylinder axial piston compressor with a further variant of particularly advantageous designed support structures;

8th a perspective view of a piston assembly with support structures according to 4 ;

9 a partial plan view of a piston assembly according to 8th ;

10 a perspective view of a piston assembly with support structures according to 6 ;

11 a partial plan view of a piston assembly according to 10 ;

12 a perspective view of a piston assembly with support structures according to 7 and

13 a partial plan view of a piston assembly according to 12 ,

1 shows a schematic representation of a piston in an axial piston compressor to illustrate the relevant positional relationships. In a cylinder block 1 are cylinder bores 2 arranged in which pistons 3 can perform a linear oscillating movement (in the direction of the double arrow). The free end of the piston 3 is fixed with a piston bridge 4 connected, the inclusion of piston shoes 5 serves. Between the piston shoes 5 slides a rotating swash plate 6 , The rotation axis 7 , which simultaneously forms the central axis of symmetry of the overall arrangement, runs parallel to the cylinder bore 2 , However not parallel to the normal of the plane of the swash plate 6 Therefore, their rotation is associated with a tumbling motion, resulting in a constant variation of the inclination angle of the swash plate 6 opposite the piston bridge 4 leads. This wobbling force enforces the desired and functional oscillation movement of the piston 3 ,

About the contact surfaces 8th between the swash plate 6 and the piston shoes 5 is due to the rotational component of the tumbling motion and corresponding pressure forces a torque in the piston 3 imprinted, whose main component is parallel to the cylinder or piston axis. Because the piston 3 in the area of the cylinder bore 2 has no anti-rotation, it comes through the impressed torque to a rotation of the piston bridge 4 around the cylinder axis until, as a result of this rotation, there is formation of a supporting contact with adjacent assemblies and, associated therewith, inhibition of further rotation. The supporting contact is in the thereby forming contact area 9 inevitably associated with abrasive effects. In the present case, the contact area required for supporting or compensating for the impressed torque is formed 9 between the piston bridge 4 and the housing 10 out of the compressor.

This example illustrates the general problem of compensating torque. In such axial piston compressors with swash plate or ring or swash plate and pistons axially guided pistons act on the piston both mass and gas forces (parallel to the cylinder axis). One of the torques impressed thereby acts around the longitudinal axis of the piston. If it were not compensated, the piston bridge, which encloses the swash ring or the swash plate, would be rotated and pressed against it. This could lead to the destruction of the mechanism. To compensate for the impressed torque is a structurally geometrically defined contact point or contact area, in which the associated with the sliding support effects are less harmful.

In any case, a contact pressure is generated between the mutually axially oscillating contact surfaces, which generates abrasion mainly on the softer of the two sliding surfaces. When supported on the housing, the majority of wear and tear on the housing occurs when it is made of aluminum and the complementary support structure is made of a harder material, such as steel.

This abrasion volume is greater, the higher the operating pressures and thus the torque to be absorbed.

For alternative environmentally friendly refrigerants, such. As CO ₂ , the effect is enhanced because its gas properties cause much higher operating pressures.

Furthermore, the friction between piston and housing generates vibrations of the compressor housing, which are emitted as airborne sound and audible as unwanted compressor or compressor noise and also increase with increasing contact pressure. The problem of such a claimed contact area is in 2 further clarified.

2 shows a schematic plan view of an exemplary piston bridge 4 in section. The cutting plane is perpendicular to the axis of rotation and symmetry 7 the overall arrangement. The torque caused by the friction between the rotating swash plate 6 , the piston shoes (not shown) and the piston calotte or piston bridge 4 , in which the piston shoe is pivotally mounted, acts on the piston, is a function of the axial piston force, which in turn, as already mentioned, by the acting gas and inertial forces is determined.

This impressed torque around the piston axis 11 is via a support or contact force F _a between the piston bridge 4 and the housing 10 compensated, resulting in a surface pressure between the axially oscillating piston and the affected contact surface in the contact area to the housing 10 results. A play-related slight rotation of the piston leads to an uneven expression of the surface pressure, which is idealized by the assumption of a contact point 9 (actually a contact line) can be described. To one with respect to the axis of rotation 7 To use the swash plate radially acting support force F _a for effective compensation of the impressed torque, it comes on a tangential disengagement of this contact point 9 from the plane of the rotary axes 7 . 11 from swash plate 6 and pistons on. The distance to this plane causes a lever to be effective, the length of which can be considered inversely proportional to the amount of support force (except at very low disengagement). Low radial support forces can thus be realized only if the operationally forming contact area 9 , hereinafter referred to as contact point, as far away as possible from the plane through which the axes of rotation 7 . 11 from swash plate 6 and pistons run. Structurally, according to the prior art, in particular with a support on the housing and potentially changing direction of rotation of the swash plate, this distance or the effective lever length limits, which are explained below.

The 3 to 7 serve in particular the explanation of mechanical principles of the invention, without being limited to a specific design variant. Contact areas and support structures are illustrated idealized with respect to their geometric effect.

3 shows a schematic sectional view through a seven-cylinder axial piston compressor with a support principle according to the prior art. Each piston, represented by the contour of the piston bridge 4 , has extended finger-shaped support structures 12 for support against the housing 10 , which extend in the tangential direction as far as possible to the left and right, bounded in each case by the identically designed adjacent piston or its finger-shaped support structure 12 ,

This leads to the greatest possible reduction of abrasion by utilizing conventional positional relationships.

This operating principle is, for example, as shown at the beginning in FIG DE 197 46 896 A1 comparable.

4 shows a schematic sectional view through a seven-cylinder axial piston compressor according to the invention designed support structures. Each piston in turn has extended finger-shaped support structures 12 for support against the housing, which extend as far as possible to the left and right in the tangential direction. The illustrated structural design of the support structures 12 However, overcomes the previous geometric limitation of the "finger length" by a diameter grading or distance gradation with respect to the central axis of symmetry 7 and thus allows an overlap of the support structures 12 adjacent piston. In the illustrated variant and the assumed direction of the impressed torques, a support on the housing 10 , but with a comparison with the prior art significantly lower support force F ₂ (compared to F ₁ , the support force with support at the edge of the piston bridge 4 ).

The overlap according to the invention is associated with further advantages. If, in the illustrated arrangement, the shaft rotation direction, that is to say the impressed torque, is reversed, the piston-bridge main torque is introduced into a piston-to-piston contact in the region of the finger-shaped support structures 12 , This piston-to-piston contact also results from a radial support, which does not take place against "fleeing surfaces", so it is associated with a low tendency to clamp.

The illustrated embodiment is particularly suitable for axial piston compressors, which are operated in a pronounced preferred direction or exclusively in one operating direction and an associated impressed main torque. Ideally, there is no contact between the piston or its support structures 12 and the housing 10 with compensation of the main torque. For example, an Al-steel contact can be avoided in this way, which has particularly wear-intensive side effects. By securing a steel-to-steel contact, the longevity of such compressors can be significantly improved even using lightweight housings.

In a change of direction of the impressed moment, although there is a contact between the piston bridge 4 or the associated with this support structures 12 and the housing 10 However, this contact leads due to the extended effective lever to minimized contact forces, which also contributes to the avoidance of wear.

5 shows a schematic partial development of the piston assembly of an inventively designed seven-cylinder axial piston compressor. Shown are three of the seven pistons 3 , The entire arrangement can be characterized by a stroke length HUB, which is determined by the position of the two dead centers OT, UT. However, the maximum stroke difference .DELTA.HUB _max between two adjacent pistons is significantly lower, since the individual pistons perform oscillating movements, between which there is a phase shift in arrangements with more than two pistons, which is significantly less than 180 °. Thus, if the compensation of the impressed torque via a support on the adjacent piston, so the abrasive relevant average speed difference between the claimed sliding surfaces against a support on the housing is significantly reduced. In addition to avoiding abrasive interaction on sliding surface pairs of differently resistant material, this also contributes to the reduction in wear. The extension of the support structures 12 in the axial direction is chosen so that is provided even during the occurrence of the maximum stroke difference between two adjacent piston for the mechanically required minimum coverage, which is required for receiving the supporting forces occurring.

6 shows a schematic sectional view through a seven-cylinder axial piston compressor with particularly advantageous designed support structures 12 , Each piston has an extended finger-shaped support structure 12 , Which extends to the middle of the following piston back, so that each piston is supported at the next piston in the plane of the piston central axis against the torque introduced via the piston shoes. In this area, the surfaces used for the support, even in the case of a slight rotation of the piston perform any lifting movement in the radial direction. The support point on each piston is quasi stationary in the cutting plane. This eliminates the influence of the contact angle.

This embodiment is also particularly suitable for axial piston compressors, which are operated in a pronounced preferred direction or exclusively in one operating direction and an associated impressed main torque. Against the main moment direction, contact with the housing is possible, but minimized by the further improved lever ratio.

7 shows a schematic sectional view through a seven-cylinder axial piston compressor with a further variant of particularly advantageous designed support structures 12 , The overlap of the support structures according to the invention 12 is realized so that in each case a pair of corresponding engagement elements for a movable, but positive connection of the support structures 12 provide adjacent piston.

In the example shown, each piston has left and right for this purpose a finger-shaped support structure 12 which extends near the housing approximately to the middle of the intermediate region between two adjacent pistons. On a "finger" is a fork 13 , on the other a pin 14 so that two adjacent pistons have their supporting structures connected to them 12 engage each other and support each other against rotation by the impressed torque.

Such an arrangement of the support structures 12 is particularly suitable for axial piston compressor, which are regularly used with different operating directions, since the impressed torques are always compensated regardless of their effective direction in the same constructive manner, so it does not come to directional wear. Although due to the phase shift of the linear acceleration on the individual pistons never on all pistons simultaneously the respective impressed torque has the same amount, resulting from the two-sided leadership of the support structures 12 an almost complete compensation of the introduced torques, without requiring deflections, resulting in contact between individual support structures 12 and the housing surrounding the assembly 10 would lead.

This principle can be used particularly advantageously if the axial piston compressor has an uneven number of pistons arranged symmetrically about a central axis of rotation and / or axis of symmetry. Due to the odd number of pistons, the pistons hold each other aligned with respect to the angular position of the piston bridges. A support against the housing is no longer required in both operating directions. A wear-related contact with the housing, due to the impressed torques, does not come about at all.

Between the embodiments according to 6 and 7 Practically every combination is conceivable.

It becomes clear from the exemplary embodiments illustrated that the overlapping of the support structures according to the invention on the pistons of an axial-piston compressor permits the use of a plurality of constructive principles for compensating the impressed torque, which can advantageously be combined with one another. When supported on the housing, at least the lever lengths effective during the compensation of the torque can be increased and the occurring supporting and frictional forces can be reduced.

In all other illustrated embodiments, the pistons in axial piston compressors at least partially mutually guide with respect to their alignment about their longitudinal axis to compensate for the impressed torque. At the same time, any remaining support forces / contact pressures are reduced in these cases in such a way that abrasive inlet and operating conditions in the contact surfaces between the oscillating pistons and the housing are minimized, thereby avoiding noise.

Another useful design principle is the displacement of the contact area between the individual support structures immediately behind the respectively adjacent pistons. As a result, the position of the contact region becomes largely independent of the orientation of the pistons, since the respective bearing surface into which the support force is introduced is not moved in the radial direction, even in the case of a piston rotated about its main axis.

The third advantageous design principle using an overlap of support structures results in the direction of rotation independent guidance or support of the piston with each other, for example, by the use of corresponding engagement structures according to 7 ,

The three mentioned design principles simultaneously determine the minimum requirements for an overlap to be maintained within the meaning of the invention. Thereafter, by overlapping the support structures of adjacent pistons in the tangential direction, inter alia, any extension of these support structures in the tangential direction to understand, which is sufficient for a positive interaction between the support structures and allows the initiation of a supporting force in the radial direction.

Solutions that use a piston-to-housing contact for support optionally limit the variation of the contact distance via a corresponding contour and tolerance selection. As a result of the overlapping of the support structures according to the invention, the influence of the required clearance between the parts is reduced or eliminated. This tolerances for the components used, in particular for the contact surfaces, can be increased to limit the rotational game. Lower tolerance requirements reduce manufacturing costs. The higher uniformity of support associated with the invention, particularly when the support is independent of housing and component tolerances, also contributes to the reduction of external compressor noise.

In the following 8th to 13 Concretely configured embodiments of the piston arrangements of axial piston compressors according to the invention are shown, in which the already three abstract advantageous design principles are implemented individually. The illustrated axial piston compressors are designed as a variant with a steel piston arrangement in an aluminum housing (not shown).

The 8th and 9 show a representation of a piston assembly with support structures according to the in 4 illustrated design principle. A swash plate inclined with respect to a central axis of symmetry of the arrangement 6 is in its edge area of the piston bridges 4 or piston calottes of the individual pistons 3 embrace. The contact between pistons 3 and swash plate 6 is about piston shoes 5 taught. To the swash plate 6 facing ends of the pistons 3 , in the present case in the area of the piston bridges 4 , are tangentially extending in both directions away from the piston support structures 12 arranged in the form of flattened fingers, each partially with the support structures 12 overlap each adjacent piston. The overlap is achieved by spacing the support structures 12 in terms of their distance to the central axis of symmetry 7 the arrangement and thus at the same time the distance to the inner surface of the (not shown) housing allows. The overlap is designed so that in one operating direction of the compressor, a support of all pistons 3 relative to the housing takes place and in the reverse operating direction, a support of all pistons 3 against the corresponding support structure 12 an adjacent piston takes place.

This maximized contact distance concept results in an increase in the effective lever arm beyond the limit actually given by the adjacent piston, thus reducing the support force. The limitation of the extension of the support structures in this embodiment is no longer due to the position of the support structures of the adjacent piston, but by the position of the piston bridge of the respective adjacent piston.

The 10 and 11 show a representation of a piston assembly with support structures according to the in 6 illustrated design principle. One with respect to a central axis of symmetry 7 the arrangement inclined swash plate 6 is also in its edge area of the piston bridges 4 or piston calottes of the individual pistons 3 embrace. The contact between pistons 3 and swash plate 6 is about piston shoes 5 taught. To the swash plate 6 facing ends of the pistons 3 , in the present case in the area of the piston bridges 4 , are tangential in one direction from the piston 3 away extending support structures 12 arranged in the form of flattened fingers, each extending into the region of the adjacent piston 3 extend. The outside of the piston bridge 4 every piston 3 is for this purpose with a recess 15 provided in which the end of the support structure 12 of the adjacent piston 3 slidably finds a bearing surface. The piston bridges 4 are thus incorporated into the system of support structures themselves and allow in the region of the recess 15 existing pitch with respect to the central axis of symmetry 7 the functionally necessary overlap in the context of the invention. The extended finger-shaped support structures 12 all pistons, which are up to the outside contact points on the adjacent piston 3 range, allow a compensation of the impressed torque in the radial section line of a tangential plane of contact with the plane through which the central axis of symmetry 7 , ie the axis of rotation of the swash plate 6 , And the respective piston axis run. The compensation of the impressed torque thus takes place without generating a counter-torque. In addition, in this embodiment, the advantages of an extended effective lever to compensate for impressed torques can be used particularly effectively.

The 12 and 13 show a representation of a piston assembly with support structures according to the in 7 illustrated design principle. One with respect to a central axis of symmetry 7 the arrangement inclined swash plate 6 In turn, in its edge area of the piston bridges 4 or piston calottes of the individual pistons 3 embrace. The contact between pistons 3 and palette 6 is also about piston shoes 5 taught. To the swash plate 6 facing ends of the pistons 3 , in the present case in the area of the piston bridges 4 , are tangentially extending in both directions away from the piston support structures 12 ' . 12 '' arranged in the form of a flattened finger. The extension in the tangential direction is chosen so that it is sufficient for a tight overlap. To realize this tight overlap, each has a support structure 12 ' a groove-shaped end 16 on, and the other support structure 12 '' has a tapered end area 17 which is in the groove-shaped end 16 fits. In this way, the desired overlap can be realized by corresponding engagement structures for forming the contact areas required for the support, which cooperate in the form of a tongue-and-groove connection, wherein parallel to the piston axis, a sliding displacement of the respective adjacent support structures 12 ' . 12 '' is possible. Thus, each two adjacent support structures engage each other as a piston arm and allow mutual support when occurring impressed torques. As a result, on the one hand a particularly uniform compensation occurs, on the other hand it is ensured that the support is always independent of the operating direction relative to other pistons, but not against fixed components, in particular in the region of the housing.

A particularly high degree of uniformity and resistance to twisting results in this embodiment, if it is an odd number of pistons, which are arranged radially symmetrically. These lead each other during their axial oscillation in the predetermined position to the housing and the swash plate. Due to the compensation of impressed torques, which is very well balanced in this case, there is no contact between the pistons and the housing for this two-way deflectable arrangement, instead always for a piston-piston contact.

In order to exclude clamping effects in the region of the support structures in the event of slight rotations of the pistons occurring about their main axis, the tapered region engaging in the groove has 17 at its extremity a bead-shaped thickening 18 in whose area it comes to the initiation of functional support forces.

In all variants of a support against adjacent pistons or their support structures is reduced by the not independently taking place relative movements between the adjacent piston, the length of the abrasive relevant Gleitwegs. The total length of the glide path after x revolutions is reduced by a factor sin (Π / n _K ) compared to a support on the compressor housing, where n _{K is} the number of rotationally symmetrically arranged pistons. Consequently, for n _K = 2 there is no reduction of the glide path. In contrast, the sliding path is reduced in a arrangement with 7 pistons by the factor sin (Π / 7) or with 5 pistons by the factor sin (Π / 5). This reduction relates in each case to a comparison arrangement with support in relation to a fixed guide element, for example the housing.

In all the illustrated embodiments, compared to the prior art, there is a reduction of wear effects and associated contamination of lubricants and / or refrigerants. The possibility of using components of larger tolerances is associated with a favorable reduction of manufacturing costs. In the case of avoiding housing contact of the pistons, an effective noise reduction results. In general, the lower support forces cause reduced friction losses and associated noise developments. An ecological advantage of the invention is therefore obvious: longer oil change intervals with a simultaneously longer product life reduce resource consumption and also help to save costs.

LIST OF REFERENCE NUMBERS

1

cylinder block

2

cylinder bores

3

piston

4

piston bridge

5

piston shoes

6

swash plate

7

Rotation or symmetry axis

8th

contact area

9

Contact point or area

10

casing

11

Piston or central axis

12

Stutz structure

12 '

support structure

12 ''

support structure

13

fork

14

Pin code

15

recess

16

The End

17

end

18

thickening

Claims (15)

Axial piston compressor according to the swash plate principle, in which about a central axis of symmetry ( 7 ) several pistons ( 3 ) are arranged parallel to this axis of symmetry in corresponding cylinder bores ( 2 ), the pistons ( 3 ) fixed with support structures ( 12 . 12 ' . 12 '' ), which causes a rotation of the pistons ( 3 ) about their respective central axis ( 11 ) by supporting on an adjacent component, characterized in that the support structures ( 12 . 12 ' . 12 '' ) are designed so that the main component of the resulting support force with respect to the central axis of symmetry ( 7 ) acts respectively in the radial direction and the extension of the support structures ( 12 . 12 ' . 12 '' ) is so large in the tangential direction that the support structures ( 12 . 12 ' . 12 '' ) of adjacent pistons ( 3 ) at least partially overlap or support structures ( 12 . 12 ' . 12 '' ) of a piston ( 3 ) each extend into the area of an adjacent piston. Axial piston compressor according to claim 1, characterized in that support structures ( 12 . 12 ' . 12 '' ) of each piston ( 3 ) in a tangential direction on both sides of the piston ( 3 ). Axial piston compressor according to claim 1 or 2, characterized in that the support structures ( 12 . 12 ' . 12 '' ) are designed so that at least in one operating direction of the axial piston compressor, the support against a housing surrounding the piston assembly ( 10 ) he follows. Axial piston compressor according to one of claims 1 to 3, characterized in that the support structures ( 12 . 12 ' . 12 '' ) are designed so that at least in one operating direction of the axial piston compressor, the support against a support structure ( 12 . 12 ' . 12 '' ) of a respective adjacent piston ( 3 ) he follows. Axial piston compressor according to one of claims 1 to 4, characterized in that the support structures ( 12 . 12 ' . 12 '' ) are designed so that in both operating directions of the axial piston compressor, the support against a support structure ( 12 . 12 ' . 12 '' ) of a respective adjacent piston ( 3 ) he follows. Axial piston compressor according to one of claims 1 to 5, characterized in that the support structures ( 12 . 12 ' . 12 '' ) as finger-shaped extensions of the piston bridges ( 4 ) are executed. Axial piston compressor according to one of claims 1 to 6, characterized in that the support structures ( 12 . 12 ' . 12 '' ) in the respective overlapping areas have sliding surfaces for forming the contact areas required for the support. Axial piston compressor according to one of claims 1 to 6, characterized in that the support structures ( 12 . 12 ' . 12 '' ) each adjacent piston ( 3 ) in the respective overlapping areas corresponding intervention structures ( 16 . 17 . 18 ) to form the required contact areas for support. Axial piston compressor according to one of claims 1 to 8, characterized in that the support structures ( 12 . 12 ' . 12 '' ) are designed so that, at least in one operating direction of the axial piston compressor, the support takes place against a support structure of a respective adjacent piston in a contact region which intersects the plane through which the central axis of symmetry ( 7 ) of the arrangement and the main axis ( 11 ) of the adjacent piston. Axial piston compressor according to claim 9, characterized in that the support of the support structure ( 12 . 12 ' . 12 '' ) of a piston ( 3 ) each against the outside of the piston bridge ( 4 ) of an adjacent piston takes place. Axial piston compressor according to one of claims 1 to 10, characterized in that the support structures ( 12 . 12 ' . 12 '' ) consist of steel. Axial piston compressor according to one of claims 1 to 11, characterized in that the housing ( 10 ) consists of aluminum. Axial piston compressor according to one of claims 1 to 12, characterized in that an odd number of pistons ( 3 ) is included. Axial piston compressor according to one of claims 1 to 13, characterized in that at least five pistons ( 3 ) are included. Axial piston compressor according to one of claims 1 to 13, characterized in that at least seven pistons ( 3 ) are included.

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