RADIAL PISTON COMPRESSOR AND METHOD FOR THE ASSEMBLY OF A RADIAL PISTON COMPRESSOR

Abstract

A radial piston compressor comprises a compressor unit and a drive device for driving the compressor unit, wherein the compressor unit includes at least two piston-and-cylinder-bore assemblies, preferably a plurality of piston-and-cylinder-bore assemblies, which are arranged radially around an eccentric shaft, wherein the eccentric shaft is driven by the drive device, wherein each piston-and-cylinder-bore assembly includes a piston, wherein the radial piston compressor, in particular the compressor unit, includes a piston guide ring, wherein the pistons are in contact, in particular in positive engagement, with the piston guide ring, wherein the piston guide ring is elastic, in particular elastic in the radial direction, at least in parts, preferably completely.

Description

The present invention relates to a radial piston compressor according to the preamble of claim 1 and to a method for the assembly of a radial piston compressor according to the preamble of claim 18 or 19.

A radial piston compressor comprises essentially a compressor unit and a drive device, preferably an electric motor, for driving the compressor unit. The compressor unit comprises essentially a plurality of piston-and-cylinder-bore assemblies, which are arranged radially around an eccentric shaft. The eccentric shaft is driven by the drive device accordingly.

Furthermore, a radial piston compressor can comprise a piston guide ring which is operatively connected to the pistons of the piston-and-cylinder-bore assemblies, such that a return movement can be applied to the pistons, i.e. the movement with which the piston is moved from its top dead center to its bottom dead center of the piston movement.

A radial piston compressor having a piston guide ring has been known, for example, from DE 102020211680A1. In this way, the piston guide ring is generally in contact with the respective piston at a point (without loss of contact) and the piston is brought into contact with the eccentric. Additional contact changes between piston guide ring and piston and between piston and eccentric should thereby be avoided, which has dynamic advantages with respect to the kinematics of the movement sequence and advantages with respect to wear. Acoustic advantages are also achieved in this way, because no rattling noises or other disturbing noises are produced. The piston guide ring holds the pistons and the transmission elements in sliding contact with the eccentric or with a bearing outer ring of a rolling bearing arranged on the eccentric.

Also, DE 103 56 373 A1 has disclosed a reciprocating piston machine having annularly mutually adjacent, radially directed piston-and-cylinder units and having an eccentric shaft, which extends centrally through a housing body of a machine housing and the eccentric of which controls the outward stroke of the pistons, wherein the inward stroke of the pistons is controlled by a control ring which surrounds the eccentric shaft and the eccentric of said eccentric shaft with clearance and which engages in the pistons, so that the outward stroke of the pistons controls the inward stroke of diametrically opposite pistons.

The piston guide ring disclosed in the prior art and designed as a circular ring has low flexibility. The flexibility is low to nonexistent. If the radial distance of the contact points on the piston is not equal, due to production tolerances of the components, contact gaps between piston guide ring and piston result. Because of the low flexibility, the guide ring cannot compensate these tolerances or fluctuations in the radius or diameter in order to ensure constant contact of the pistons with the eccentric. Thus, the contact gaps are closed, for example at the reversal point of the piston from the top dead center position towards lower positions. This contact closure involves, for example, impacting of the piston guide ring, which in turn causes negative acoustic effects, i.e. noises. Greater radial distances of the contact points on the piston can also lead, for example, to tighter contact of piston or pivot segments with the eccentric due to the largely inflexible circular ring. The result here is, for example, increased friction and/or wear.

This is the starting point of the present invention, the object of which is to propose an improved radial piston compressor, in particular to propose a radial piston compressor with which the disadvantages outlined above can be overcome, or however at least reduced. In particular, one object of the present invention is to propose a radial piston compressor with a piston guide ring, the piston guide ring of said radial piston compressor is designed to constantly form/maintain the contact between piston and piston guide ring, i.e. to avoid contact gaps, in order to compensate tolerances and/or fluctuations in the diameter through 3 contact points of the pistons, in particular in order to ensure constant contact of the pistons with the eccentric.

According to the invention, this object is achieved by a radial piston compressor having the characterizing features of claim 1. Since the piston guide ring is configured to be at least in sections, preferably entirely, elastic, in particular elastic in the radial direction, the disadvantages outlined above can be overcome, or at least reduced.

A guide ring which is radially elastic allows, in particular, out-of-roundness or a desired deformability in its diameter or in its effective diameter, so that it comes into contact with and maintains contact with all the contact points of the pistons, which, as a result of tolerances, do not lie on a circular path. Thus, all the pistons are constantly in contact with the eccentric. In the region of the connection between the pistons and the guide ring, an elasticity of the guide ring, in, in particular, the radial direction, is obtained. Constant contact of the pistons or that with the eccentric is obtained. This results in little to no noise, which could be produced, for example, by a change between contact and loss of contact between piston and eccentric. Tolerances or deviations in the diameter which is effective for the piston guide ring can be compensated; even “relatively large” jumps, i.e. out-of-roundness or deviations from the circular form, between adjacent pistons are then possible.

Additional advantageous embodiments of the proposed invention result in particular from the features of the dependent claims. In principle, the subject matter or features of the various claims can be combined with one another in any way.

In an advantageous embodiment of the invention, it can be provided that the elasticity of the piston guide ring is set by means of the geometry of said piston guide ring and/or the modulus of elasticity of said piston guide ring.

In another advantageous embodiment of the invention, it can be provided that the piston guide ring has a radial stiffness between 100 N/mm and 1000 N/mm.

In another advantageous embodiment of the invention, it can be provided that high-strength and higher-strength steels are considered as material for the piston guide ring.

In another advantageous embodiment of the invention, it can be provided that the piston guide ring has an inside lateral surface. The inside lateral surface is used essentially to contact the pistons, in particular an active surface of the respective piston. The inside lateral surface preferably faces the eccentric.

In another advantageous embodiment of the invention, it can be provided that the pistons each have an active surface for the engagement of the piston guide ring. The active surface is used essentially as a contact surface to the piston guide ring.

In another advantageous embodiment of the invention, it can be provided that the piston guide ring comprises a guide ring and resilient elements. Here, it can be provided that the guide ring per se is not elastic and merely the resilient elements are elastic.

In another advantageous embodiment of the invention, it can be provided that the resilient elements extend radially from the inside of the guide ring. This corresponds to the preferred action direction, so that the resilient elements can be used in a targeted way.

In another advantageous embodiment of the invention, it can be provided that the piston guide ring is wider than is high. Such an embodiment makes possible a piston guide ring which is elastic simply due to its geometry. Such a piston guide ring is accordingly economical to produce.

In another advantageous embodiment of the invention, it can be provided that the extent of the piston guide ring in the mounted state is greater in the axial direction than in the radial direction. Such an embodiment can result in a guide ring which is resilient by virtue of its geometry. Such a piston guide ring is accordingly economical to produce.

In another advantageous embodiment of the invention, it can be provided that the piston guide ring has nearly two turns, wherein the ends of the turns face each other at a distance from one another on different planes, wherein the piston guide ring per se has an inside diameter. Such a guide ring is resilient. It is possible to widen the profile for elasticity.

In another advantageous embodiment of the invention, it can be provided that the piston guide ring is equipped with a means for fastening to one of the pistons. In this way, peripheral movement can be prevented.

In another advantageous embodiment of the invention, it can be provided that the piston guide ring is made of a wound material or has a wound material.

In another advantageous embodiment of the invention, it can be provided that the piston guide ring is surrounded or at least partially surrounded by a material, in particular a plastic. In this way it is possible, for example, to set other desired properties of the piston guide ring.

In another advantageous embodiment of the invention, it can be provided that the piston guide ring has a V-shaped cross section. Special geometries can accordingly be used.

In another advantageous embodiment of the invention, it can be provided that the piston guide ring is in the form of a non-closed ring, wherein the piston guide ring has a gap in which butt ends of the non-closed ring face one another, wherein the piston guide ring has an inside diameter and the butt ends have a distance. A piston guide ring designed in such a way can be mounted advantageously. During mounting, the gap can widen and the inside diameter can increase. After the mounting, the piston guide ring can assume a state with a corresponding preload.

In another advantageous embodiment of the invention, it can be provided that the piston guide ring is in the form of a closed ring. In contrast, it can also be provided that the piston guide ring is in the form of a non-closed ring.

Another object of the present invention is to propose an advantageous method for mounting a piston guide ring in a radial piston compressor according to the invention.

According to the invention, this object is achieved by the following method steps for a non-closed piston guide ring:

• • the piston guide ring is in a relaxed state, the piston guide ring has a first inside diameter and a first distance of the butt ends;
  • the piston guide ring is put into a mounting state, the inside diameter is increased to a second inside diameter, the distance of the butt ends is increased to a second distance;
  • the piston guide ring, in particular with the inside lateral surface thereof, is applied to the pistons, in particular the second active surface of the pistons;
  • the piston guide ring is put into a mounted state, the inside diameter is decreased to a third inside diameter, the distance of the butt ends is decreased to a third distance the piston guide ring, in particular the inside lateral surface, is brought into engagement,
  • in particular positive engagement, with the pistons, in particular with the contact surfaces of the pistons.

According to the invention, this object is also achieved by the following method steps for a closed piston guide ring:

• • the piston guide ring is in a relaxed state, the piston guide ring has a first inside diameter;
  • the piston guide ring is put into a mounting state, the inside diameter is increased to a second inside diameter;
  • the piston guide ring, in particular with the inside lateral surface thereof, is applied to the pistons, in particular the piston contact surfaces;
  • the piston guide ring is put into a mounted state, the inside diameter is decreased to a third inside diameter;
  • the piston guide ring, in particular the inside lateral surface, is brought into engagement, in particular positive engagement, with the pistons, in particular with the contact surfaces of the pistons.

Further features and advantages of the present invention become clear by the following description of preferred exemplary embodiments with reference to the accompanying drawings, in which:

FIGS. 1 to 4 show details of pistons for piston-and-cylinder-bore assemblies, piston-and-cylinder-bore assemblies for a radial piston compressor, and radial piston compressor in different views according to the prior art;

FIG. 5 shows a piston-and-cylinder-bore assembly for a radial piston compressor according to the invention with an elastic piston guide ring in a first embodiment and a second embodiment;

FIG. 5a shows an elastic piston guide ring for a piston-and-cylinder-bore assembly in a perspective view;

FIG. 5 b, c show a portion of an elastic piston guide ring for a radial piston compressor according to the invention in a cross-sectional view;

FIG. 5 d, e show an elastic piston guide ring for a radial piston compressor according to the invention in a cross-sectional view;

FIG. 6 shows a piston-and-cylinder-bore assembly for a radial piston compressor according to the invention with an elastic piston guide ring in a third embodiment and a fourth embodiment;

FIG. 6a shows an elastic piston guide ring for a radial piston compressor according to the invention in a cross-sectional view;

FIG. 6b shows an elastic piston guide ring for a radial piston compressor according to the invention in a cross-sectional view;

FIGS. 6c-f show an elastic piston guide ring for a radial piston compressor according to the invention in a cross-sectional view;

FIG. 7a shows an elastic piston guide ring for a radial piston compressor according to the invention in a perspective view;

FIG. 7b shows an elastic piston guide ring for a radial piston compressor according to the invention in a side view;

FIG. 7c shows an elastic piston guide ring for a radial piston compressor according to the invention in a side view;

FIG. 7d shows an elastic piston guide ring for a radial piston compressor according to the invention in a side view;

FIG. 8 shows an elastic piston guide ring for a radial piston compressor according to the invention in a plan view;

FIG. 9 shows a plurality of pistons of a compressor unit according to the invention with an elastic piston guide ring in another embodiment;

FIG. 9a shows an elastic piston guide ring for a radial piston compressor according to the invention in a plan view;

FIG. 9b shows an elastic piston guide ring for a radial piston compressor according to the invention in a plan view;

FIG. 9c shows an elastic piston guide ring for a radial piston compressor according to the invention in a plan view;

FIG. 10 shows an elastic piston guide ring for a radial piston compressor according to the invention in a perspective view;

FIG. 11 shows a piston-and-cylinder-bore assembly for a radial piston compressor according to the invention with elastic piston guide rings in a further embodiment;

FIGS. 11a-d show portions of elastic piston guide rings in further embodiments.

The following reference signs are used in the drawings:

• • 1 Piston
  • 2 Cylinder bore
  • 3 Center line of the cylinder bore
  • 4 Drive shaft/eccentric shaft
  • 5 Axis of rotation of the drive shaft
  • 6 Eccentric
  • 7 Center point of the eccentric
  • 8 Transmission element
  • 9 First support surface of the transmission element
  • 10 Cylindrical surface
  • 11 Action surface of the piston
  • 12 Second support surface of the transmission element
  • 13 Piston guide ring
  • 14 Inside lateral surface of the piston guide ring
  • 15 Contact surface of the piston
  • 16 First support surface radius
  • 17 Radius of the cylinder surface
  • 19 Second support surface radius
  • 20 Second action surface radius
  • 21 Center point
  • 22 First action surface radius
  • 23 Radius of the inside lateral surface of the piston guide ring
  • 24 Outside lateral surface
  • 25 Outer ring
  • 26 Rolling bearing
  • 27 Cylinder housing
  • 131 Guide ring
  • 132 Resilient element
  • 133 Means for fastening to one of the pistons
  • V Compressor unit
  • M Drive device
  • A (′, ″) Gap or distance of the butt ends
  • D (′, ″) Inside diameter
  • B Width
  • H Height
  • K Plastic shell

The terminology used herein serves only the purpose of describing certain embodiments and is not intended to limit the disclosure. As used herein, the singular forms “a/an” and “the” are intended to also include the plural forms, insofar as the context does not clearly indicate otherwise. It will also be clear that the expressions “has” and/or “having”, when used in this description, specify the presence of the mentioned features, integers, steps, operations, elements and/or components but do not preclude the presence or the addition of one or more other features, integers, steps, operations, elements, components and/or groups of the same.

As used herein, the expression “and/or” includes any and all combinations of one or more of the associated, listed elements.

First, reference is made to FIGS. 1 to 4.

Here, details of pistons for piston-and-cylinder-bore assemblies, piston-and-cylinder-bore assemblies for a radial piston compressor and according to the prior art are described in different views in order to explain the basic principle.

A radial piston compressor comprises essentially a compressor unit V and a drive device M for driving the compressor unit V. The compressor unit V comprises essentially a plurality of piston-and-cylinder-bore assemblies 1, 2, which are arranged radially around an eccentric shaft 4. The eccentric shaft 4 is driven by the drive device M accordingly.

A piston-and-cylinder-bore assembly comprises essentially a cylinder or cylinder bore 2 and a piston 1 translatably accommodated in the cylinder bore 2.

The radial piston compressor preferably also comprises a cylinder housing 27 with piston-and-cylinder-bore assemblies accommodated therein. The radial piston compressor also comprises the drive shaft 4 with an eccentric 6. The drive shaft 4 is set into rotation by a drive means 31, preferably an electric motor.

In contrast to an axial piston compressor, the pistons 1 and cylinders 2 and piston-and-cylinder-bore assemblies 1, 2 extend radially from the drive shaft 4 or eccentric 6. The pistons 1 and cylinders and piston-and-cylinder-bore assemblies are preferably arranged around the drive shaft 4 or eccentric 6 in a star shape. The radial piston compressor can also be referred to as a compressor according to the radial piston principle.

FIG. 1 shows pistons 1 of piston-and-cylinder-bore assemblies in radial half-section. In FIG. 1, only the axis of rotation 5 of the drive shaft 4 is identified. Pistons 1 are arranged in a manner distributed around the drive shaft 4 in the peripheral direction. The center lines 3 of the cylinder bores 2, which are not shown in FIG. 1 for reasons of better clarity, intersect at the axis of rotation 5 of the drive shaft 4. The cylindrical eccentric 6 is in the form of an integral part of the drive shaft 4 or in the form of a component joined to the drive shaft 4 for conjoint rotation. The center point 7 of the eccentric 6 is arranged in a manner offset from the axis of rotation 5 of the drive shaft 4 by a distance in order to produce the eccentricity. The eccentric 6 has, as a lateral surface, a cylinder surface 10 with a radius 17.

The piston-and-cylinder-bore assembly according to the invention preferably also comprises a cylindrical piston guide ring 13 which preferably has an inside lateral surface 14.

A transmission element 8 is preferably arranged between the eccentric 6 and the piston 1 of a piston-and-cylinder-bore assembly. By means of the transmission element 8, the stroke of the eccentric 6 is transmitted to the piston 1, so that said piston performs the compression movement towards top dead center OT. In the exemplary embodiment shown in FIG. 1, the transmission elements 8 are supported directly on the cylinder surface 10 of the eccentric 6 by means of a first support surface 9. In the exemplary embodiment shown in FIG. 1, the first support surface 9 is in the form of a cylinder lateral surface segment which is concavely curved and which has a first support surface radius 16. The first support surface radius 16 corresponds to the radius 17 of the cylinder surface 10. The first support surface 9 and the cylinder surface 10 are thus mutually complementary. In principle, the first support surface 9 could also have a concave shape deviating from the shape of a circular ring.

The transmission element 8 has a convex second support surface 12. In the exemplary embodiment shown in FIG. 1, the second support surface 12 is in the form of a cylinder lateral surface segment with a second support surface radius 19. In principle, the second support surface 12 could also have, instead of a shape of a cylinder lateral surface segment, a convex shape deviating from the shape of a cylinder. The piston 1 is supported on the second support surface 12 of the transmission element 8 by means of an action surface 11 formed on the piston 1. The action surface 11 of the piston 1 is concave. In the exemplary embodiment shown, the action surface 11 of the piston 1 is in the form of a concave cylinder lateral surface segment having an action surface radius 22 which corresponds to the second support surface radius 19. The action surface 11 of the piston 1 and the second support surface 12 of the transmission element 8 are thus mutually complementary. In principle, the action surface 11 of the piston 1 could also have a concave shape deviating from the shape of a cylinder.

A convex contact surface 15 is formed on the piston 1 or the pistons 1. In the exemplary embodiment shown, the contact surface 15 of the piston 1 is a cylinder lateral surface segment having a contact surface radius 20. The pistons 1 are in engagement with the piston guide ring 13, in particular in positive engagement with the pistons 13. The piston is in positive engagement with the piston guide ring 13, in particular with the inside lateral surface 14 of the piston guide ring 13, in particular by means of the contact surface 15. The engagement, in particular the positive engagement, is effective in the direction of the center line 3 of the cylinder bore 2. By means of the piston guide ring 13, the return movement is transmitted to the pistons 1, in particular to the contact surface 15 of the pistons 1, i.e. the movement with which the piston 1 is moved from the top dead center OT into the bottom dead center UT of the piston movement.

In the exemplary embodiment shown in FIG. 1, the second support surface radius 19 of the transmission element 8 and the second active surface radius 22 of the piston 1 have the same center point 21. The center point 21 corresponds to the point at which the center line 3 of the cylinder bore 2 crosses the cylinder surface 10 of the eccentric 6. This design measure preferably has the result that the sum of the radius 17 of the cylinder surface 10 and the second active surface radius 22 of the piston 1 corresponds to the radius 23 of the inside lateral surface 14 of the piston guide ring 13. This has the result that the piston guide ring 13 with the inside lateral surface 14 thereof generally does not lose contact with the contact surface 15 of the piston 1, i.e. at no angular position of the eccentric 6 or of the drive shaft 4. In this way, for example, the piston guide ring 13 is always in contact (without loss of contact) with the respective piston 1. Thus, additional contact changes and between piston guide ring 13 and piston 1 or between piston 1 and eccentric 6 or eccentric bearing 25 are avoided, which has dynamic advantages with respect to the kinematics of the movement sequence and advantages with respect to wear. Acoustic advantages are also achieved in this way, because no rattling noises or other disturbing noises are produced.

As can be seen in FIG. 3, the eccentric 6 can also be equipped with a rolling bearing 26. The rolling bearing 26 generally comprises a bearing outer ring 25 which, instead of the eccentric disk, forms the surface of the eccentric 6 facing the pistons 1.

The piston guide ring 13 guides the pistons 1 on the eccentric 6 (or on the bearing outer ring 25) and prevents the pistons 1 from “lifting off” of the cylinder surface 10 (or the outside lateral surface 24 of the outer ring 25 of the rolling bearing) during a downward movement/return movement of the pistons 1. The piston guide ring 13 slides on the second active surface 15 formed on the piston 1. The piston guide ring 13 keeps the pistons 1 and the transmission elements 8 in sliding contact with the eccentric 6 (or with a bearing outer ring 25 of a rolling bearing 26 arranged on the eccentric).

FIG. 2 shows pistons 1 of piston-and-cylinder-bore assemblies in an exploded view. The transmission elements 8 are supported on the outer ring 25 of the rolling bearing 26. The eccentric 6 is not shown in FIG. 2. Contact surface 15 of the piston 1 is also designed such that it interacts with the inside lateral surface 14 of the piston guide ring 13.

FIG. 3 schematically shows a radial piston compressor having piston-and-cylinder-bore assemblies according to the invention. In the exemplary embodiment shown, the piston-and-cylinder-bore assemblies are designed such that the transmission elements 8 have cylinder-segment-shaped concave first support surfaces 9 and the second support surfaces 12 of the transmission elements 8 are cylinder-segment-shaped and interact with cylinder-segment-shaped first action surfaces 11 of the pistons 1.

The cylinder bores 2 are arranged in a cylinder housing 27. The individual pistons 1 are driven by means of a single drive shaft 4 with an eccentric 6. To achieve better clarity, FIG. 3 has not shown all the details that a complete radial piston compressor has. For example, all valve arrangements and feed and discharge channels for the refrigerant are thus omitted. Because of the piston-and-cylinder-bore assemblies, the radial piston compressor according to FIG. 3 is compact in the radial direction and also in the axial direction, i.e. it requires little installation space in both mentioned directions.

The further relationships and mode of action are well known to a person skilled in the art. For further details, reference can be made in particular to DE 10 2020 211 680 A1.

According to the invention, it is provided that the piston guide ring is configured to be at least partially, and preferably completely, elastic, particularly in the radial direction.

The elasticity of the piston guide ring can be set by means of the geometry of said piston guide ring and/or the modulus of elasticity of said piston guide ring. It is preferably provided that the piston guide ring has a radial stiffness between 100 N/mm and 1000 N/mm. High-strength and higher-strength steels, for example, are considered as material for the piston guide ring.

The piston guide ring 13 has an elasticity in the radial direction, preferably so that it comes into contact with all contact points, which, as a result of tolerances, do not lie on a circular path—i.e. a desired deformability of the piston guide ring 13 is sought, with the goal of having no contact gap.

Various embodiments are conceivable for implementing or providing an elastic piston guide ring 13 and should be described below. The embodiments of an elastic piston guide ring which are presented here are not exhaustive. Other embodiments not shown here are conceivable.

Below, reference is made to FIGS. 5 to 11d.

FIG. 5 shows a piston-and-cylinder-bore assembly for a radial piston compressor according to the invention with two different embodiments of elastic piston guide ring. The piston guide ring 13 shown on the right side is shown in a perspective view in FIG. 5a. The piston guide ring 13 comprises essentially a guide ring 131 and resilient elements 132. The guide ring 131 per se has little elasticity in the radial direction. It is also clear in FIG. 5 that the resilient elements 132 extend radially from the inside of the guide ring 131.

FIGS. 5b to 5e show further examples for the design of the piston guide ring 13, in particular of the resilient elements 132. The orientations of the resilient elements 132 can be radial, axial or else as a mixed form of radial and axial orientations, in particular oblique orientations. For example, FIG. 5c shows an oblique orientation of the resilient element 132. FIG. 5b shows a rather axial orientation of the resilient element 132.

In FIGS. 5a, 5d and 5e, a diameter D is shown. It is preferably provided that the resilient elements 132 form the diameter D of the piston guide ring 13 which is effective for the pistons 1.

FIG. 5b and FIG. 5c show the guide rings according to FIG. 5 in cross section in a detail. Reference sign B for width, H for height, D for the diameter which is effective at the piston contact points.

The shown axis of rotation 5 of the drive shaft illustrates the relative position in the mounted state. However, it is also possible in principle that the guide ring 131 and the resilient elements 132 extend over the entire periphery of the piston guide ring 13, as indicated in FIGS. 5d and 5e. Such a piston guide ring 13 is easier to mount because exact assignment of the individual resilient elements 132 to the piston contact points is not required.

FIG. 6 shows a piston-and-cylinder-bore assembly for a radial piston compressor according to the invention with two different embodiments of elastic piston guide ring 13. The piston guide ring 13 shown on the right side is shown in part, in cross section, in FIG. 6a. The piston guide ring 13 shown on the left side is shown in part, in cross section, in FIG. 6b. The piston guide rings 13 shown here are resilient by virtue of their geometry, in particular due to a cross-sectional shape which is wider than is high. In other words, the extent of the piston guide ring 13 in the mounted state is greater in the axial direction than in the radial direction. The width of the piston guide ring 13 is denoted with reference sign B, and the height is denoted with reference sign H.

FIG. 6c andd show the piston guide rings 13 according to FIG. 6 in a relaxed state. The piston guide rings 13 have an inside diameter D. FIG. 6c and FIG. 6d show the guide rings 13 in cross section, wherein here as well the axis of rotation 5 of the drive shaft 4 is intended to illustrate the position when mounted.

FIG. 6e shows, by way of example, the piston guide ring 13 according to FIG. 6c in a state during mounting. The piston guide ring 13 has a second inside diameter D′. It is clear that the second inside diameter D′ is greater in a state during mounting than in a relaxed state (D, FIG. 6c). In the aforementioned state, the piston guide ring 13 is in particular slid over piston contact surfaces 15. This is in particular a state in which the piston guide ring 13 should be maximally elastically preloaded.

FIG. 6f shows the piston guide ring 13 in a state in which it is mounted on the pistons. The piston guide ring 13 has a third inside diameter D″. It can be seen that the third inside diameter D″ in a mounted state is less than in a state during mounting (D′, FIG. 9b). On the other hand, the third diameter D″ in a mounted state is greater than in a relaxed state (D, FIG. 9a).

In the mounted state, the piston guide ring 13 is thus elastically preloaded, so that it comes into contact with all contact points (which, due to tolerances, do not lie on a circular path), such that no contact gap can form at contact points of the pistons 1. The diameter D of the piston guide ring 13 will preferably always be smaller than the smallest diameter, placed through 3 contact points of the pistons.

However, the preload should be as small as possible, because a large preload increases friction, which is undesired. The preload must also be designed such that it does not exceed the material limits (with respect to Hertzian contact stress and fatigue strength under reverse bending stress) both for the piston guide ring 13 and for the piston contact 15 under long-term loading.

The mounting and the diameters D, D′, D″ which are set are described and shown here using the piston guide ring 13 with rectangular cross section (FIGS. 6a, 6c) by way of example. These statements also apply to the embodiments of the piston guide ring 13 which are shown in FIG. 6b, d and FIGS. 5, 5a, 5b-5e.

In FIGS. 7a to 7d, only elastic piston guide rings 13 are shown in various states and views. The piston guide ring 13 shown here has two turns or nearly two turns. The turns are arranged one on top of the other. The butt ends of the turns face each other at a distance A from one another on different planes. The piston guide ring 13 per se has an inside diameter D. Reference sign B denotes the material width of the piston guide ring 13. FIGS. 7a and 7b show the piston guide ring 13 in a relaxed state. Accordingly, the aforementioned reference signs D, A, B relate to the respective dimensions in the relaxed state. For better differentiation, a first inside diameter D and a first distance A should be referred to here.

FIG. 7c shows the piston guide ring 13 in a maximally elastically preloaded state. The reference signs used in this regard are accordingly D′ and A′. For better differentiation, a second inside diameter D′ and a second distance A′ should be referred to here. It can be seen that the second distance A′ between the butt ends and the second inside diameter D′ in a state during mounting are greater than in a relaxed state (A, D, FIGS. 7a, 7b).

FIG. 7d shows the piston guide ring 13 in a state in which it is elastically preloaded during operation. The reference signs used in this regard are accordingly D″ and A″. For better differentiation, a third inside diameter D″ and a third distance A″ should be referred to here. It can be seen that the third distance A″ between the butt ends and the third inside diameter D″ in a mounted state are less than in a state during mounting (A′, D′, FIG. 7c). On the other hand, the third distance A″ and the third diameter D″ in a mounted state are greater than in a relaxed state (A, D, FIGS. 7a, 7b).

FIG. 8 shows an embodiment of an elastic piston guide ring 13 in a plan view. Here, it is provided and can be seen that the piston guide ring 13 is in the form of a closed ring. In contrast, some of the embodiments of piston guide rings 13 described below are in the form of non-closed rings, i.e. have an interruption or gap.

The piston guide ring 13 is equipped with a means 133 for fastening to one of the pistons.

Accordingly, peripheral movement is not possible, because the piston guide ring is fastened to a piston.

FIG. 9 shows a plurality of pistons 1 of a radial piston compressor according to the invention with an elastic piston guide ring 13 in a further embodiment. FIGS. 9a to 9c show the piston guide ring 13 from FIG. 9 in various states, which should be discussed below.

The piston guide ring 13 is a non-closed piston guide ring. In other words, the piston guide ring 13 is not closed, but rather there is a gap at which two butt ends of the piston guide ring face each other. The butt ends have a distance A and the piston guide ring has an inside diameter D, or, as explained later, an inside diameter D′ and D″ and a distance A′ and A″. For better differentiation, a first inside diameter D, a second inside diameter D′ and a third inside diameter D″, and a first distance A, a second distance A′ and a third distance A″ should be referred to here.

In FIG. 9a, the piston guide ring 13 is shown in a relaxed state. The distance between the butt ends is denoted by the reference sign A. The piston guide ring has an inside diameter D.

In FIG. 9b, the piston guide ring 13 is shown in a state during mounting. The distance between the butt ends is denoted by the reference sign A′. The piston guide ring has a second inside diameter D′. It can be seen that the second distance A′ between the butt ends and the second inside diameter D′ in a state during mounting are greater than in a relaxed state (A, D, FIG. 9a). In the aforementioned state, the piston guide ring 13 is in particular slid over piston contact surfaces 15. This is in particular a state in which the piston guide ring 13 should be maximally elastically preloaded.

FIG. 9c shows the piston guide ring 13 in a state in which it is mounted on the piston. The distance between the butt ends is denoted by the reference sign A″. The piston guide ring 13 has a third inside diameter D″. It can be seen that the third distance A″ between the butt ends and the third inside diameter D″ in a mounted state are less than in a state during mounting (A′, D′, FIG. 9b). On the other hand, the third distance A″ and the third diameter D″ in a mounted state are greater than in a relaxed state (A, D, FIG. 9a). In the mounted state, the piston guide ring is elastically preloaded.

In summary, two methods for mounting a piston guide ring in a radial piston compressor can be described here, characterized by the following method steps in the case of a non-closed piston guide ring 13:

• • the piston guide ring 13 is in a relaxed state, the piston guide ring 13 has a first inside diameter D and a first distance A of the butt ends;
  • the piston guide ring 13 is put into a mounting state, the inside diameter is increased to a second inside diameter D′, the distance of the butt ends is increased to a second distance A′;
  • the piston guide ring 13, in particular with the inside lateral surface 14 thereof, is applied to the pistons 1, in particular the piston contact surfaces 15;
  • the piston guide ring 13 is put into a mounted state, the inside diameter is decreased to a third inside diameter D″, the distance of the butt ends is decreased to a third distance A″;
  • the piston guide ring 13, in particular the inside lateral surface 14, is brought into engagement, in particular positive engagement, with the pistons 1, in particular with the contact surfaces 15 of the pistons 1.

And in the case of a closed piston guide ring 13:

• • the piston guide ring 13 is in a relaxed state, the piston guide ring 13 has a first inside diameter D;
  • the piston guide ring 13 is put into a mounting state, the inside diameter is increased to a second inside diameter D′;
  • the piston guide ring 13, in particular with the inside lateral surface 14 thereof, is applied to the pistons 1, in particular the piston contact surfaces 15;
  • the piston guide ring 13 is put into a mounted state, the inside diameter is decreased to a third inside diameter D″;
  • the piston guide ring 13, in particular the inside lateral surface 14, is brought into engagement, in particular positive engagement, with the pistons 1, in particular with the contact surfaces 15 of the pistons 1.

FIG. 10 shows another embodiment of an elastic piston guide ring 13 for a radial piston compressor according to the invention in a perspective view. Here, the piston guide ring is a closed piston guide ring. The piston guide ring 13 shown here is made of or has a wound material, for example a continuous spring.

FIG. 11 shows a piston-and-cylinder-bore assembly for a radial piston compressor according to the invention with elastic piston guide rings 13 in a further embodiment. The piston guide rings 13 shown schematically here are in particular piston guide rings surrounded or at least partially surrounded by a material, in particular a plastic. The piston guide ring per se can be in the form of a closed or non-closed ring.

FIGS. 11a to 11d correspondingly show detail views of piston guide rings 13. The piston guide rings 13 of FIGS. 11a and 11b are an elastic piston guide ring made of a wound material which is at least partially surrounded by a material, in particular plastic K.

The piston guide rings 13 of FIGS. 11c and 11d are an elastic piston guide ring 13 made of a material having a V-shaped cross section, said material being at least partially surrounded by a material, in particular plastic K.

It is clear from the exemplary embodiments outlined above that the diameter D, i.e. the effective diameter of the piston guide ring, should always be smaller than the smallest outside diameter, placed through, for example, three contact points of the pistons, meaning that the ring is then installed with a preload. However, the magnitude of the preload should be as small as possible, because a large preload increases friction, which is undesired. The preload for the piston guide ring should also be designed such that it does not exceed the material limits (in particular with respect to Hertzian contact stress and fatigue strength under reverse bending stress) both for the piston guide ring and for the piston contact under long-term loading.

In summary, the following specifications should preferably be taken into account. The piston guide ring should have a required stiffness, so that each piston with its piston base is in contact with the eccentric and thus the stroke curve of the piston follows the stroke curve from the eccentric. This produces in particular a thermodynamic advantage. The piston guide ring should have a required flexibility, in particular deformability, so as to be able to ensure the tolerance compensation of the contact points in the radial direction of adjacent pistons. The diameter of the piston guide ring should have a required oversize with respect to the diameter of the contact points. Furthermore, there should be a required component strength with regard to contact stress and fatigue strength under reverse bending stress.

Claims

1-19. (canceled)

20. A radial piston compressor, comprising:

a compressor unit;

a drive device for driving the compressor unit; and

a piston guide ring;

wherein the compressor unit includes at least two piston-and-cylinder-bore assemblies arranged radially around an eccentric shaft;

wherein the eccentric shaft is driven by the drive device;

wherein each piston-and-cylinder-bore assembly includes a piston in contact with the piston guide ring;

wherein the piston guide ring is configured to be at least partially elastic.

21. The radial piston compressor as claimed in claim 20, wherein the compressor unit includes the piston guide ring, wherein the pistons are in positive engagement with the piston guide ring, and wherein the piston guide ring is configured to be completely elastic in the radial direction.

22. The radial piston compressor as claimed in claim 20, wherein the elasticity of the piston guide ring is set by the geometry of the piston guide ring and/or the modulus of elasticity of the piston guide ring.

23. The radial piston compressor as claimed in claim 20, wherein the piston guide ring has a radial stiffness between 100 N/mm and 1000 N/mm.

24. The radial piston compressor as claimed in claim 20, wherein high-strength and higher-strength steels are used as material for the piston guide ring.

25. The radial piston compressor as claimed in claim 20, wherein the piston guide ring has an inside lateral surface.

26. The radial piston compressor as claimed in claim 20, wherein the pistons each have a piston contact surface for the engagement of the piston guide ring.

27. The radial piston compressor as claimed in claim 20, wherein the piston guide ring includes a guide ring and resilient elements.

28. The radial piston compressor as claimed in claim 27, wherein the resilient elements extend radially, axially and/or obliquely from the inside of the guide ring.

29. The radial piston compressor as claimed in claim 20, wherein the piston guide ring is wider than it is high.

30. The radial piston compressor as claimed in claim 20, wherein the extent of the piston guide ring in the mounted state is greater in the axial direction than in the radial direction.

31. The radial piston compressor as claimed in claim 20, wherein the piston guide ring has two turns or nearly two turns, wherein ends of the turns face each other at a distance from one another on different planes, wherein the piston guide ring has an inside diameter.

32. The radial piston compressor as claimed in claim 20, wherein the piston guide ring has a means for fastening to one of the pistons.

33. The radial piston compressor as claimed in claim 20, wherein the piston guide ring is made of a wound material or has a wound material.

34. The radial piston compressor as claimed in claim 20, wherein the piston guide ring is surrounded or at least partially surrounded by a plastic material.

35. The radial piston compressor as claimed in claim 20, wherein the piston guide ring has a V-shaped cross section.

36. The radial piston compressor as claimed in claim 20, wherein the piston guide ring is in the form of a non-closed ring, wherein the piston guide ring has a gap in which butt ends of the non-closed ring face one another, wherein the piston guide ring has an inside diameter and the butt ends have a distance.

37. The radial piston compressor as claimed in claim 20, wherein the piston guide ring is in the form of a closed ring.

38. A method for mounting a piston guide ring in the radial piston compressor of claim 36, comprising:

putting the piston guide ring from a relaxed state into a mounting state, thereby increasing an inside diameter of the piston guide ring from a first inside diameter to a second inside diameter and increasing a distance of the butt ends from a first distance to a second distance;

applying the piston guide ring, with the inside lateral surface thereof, to the piston contact surfaces;

putting the piston guide ring into a mounted state, thereby decreasing the inside diameter to a third inside diameter and decreasing the distance of the butt ends to a third distance; and

bringing the inside lateral surface of the piston guide ring into positive engagement with the contact surfaces of the pistons.

39. A method for mounting a piston guide ring in the radial piston compressor of claim 37, comprising:

putting the piston guide ring from a relaxed state into a mounting state, thereby increasing an inside diameter of the piston guide ring from a first inside diameter to a second inside diameter;

applying the piston guide ring, with the inside lateral surface thereof, to the piston contact surfaces of the pistons;

putting the piston guide ring into a mounted state, thereby decreasing the inside diameter to a third inside diameter; and

bringing the inside lateral surface of the piston guide ring into positive engagement with the contact surfaces of the pistons.