Compressor coupling member for coupling drive shaft and movable screw in scroll compressor

Abstract

A compressor coupling component includes: a planar body having a first front side and a second rear side opposite the first side; a cylindrical coupling neck integrally formed on or fastened to or inserted into the planar body, in which a cylindrical axis of the cylindrical coupling neck extends perpendicular to a plane of the planar body, the cylindrical coupling neck protrudes from the planar body in the axial direction relative to the cylindrical axis of the coupling neck on the front side of the planar body. A counterweight which is at least partially formed in the shape of a hollow cylindrical section, has an arcuate outer contour, is integrally formed on the outer region of the planar body and protrudes beyond the planar body in the axial direction on the rear side of the planar body, the planar body having opposite outer edge regions, the outer edge region extends as far as the ends of the counterweight opposite each other in the arc direction of the counterweight and linearly extends in the form of gradually spaced V-legs.

Description

Technical Field

[0001] The invention relates to a compressor coupling component with an integrally formed counterweight, the compressor coupling component being used to couple a drive shaft and a movable spiral of a scroll compressor to transmit a driving torque to the movable spiral. The invention also relates to a scroll compressor for a gaseous fluid, such as a refrigerant, in which such a compressor coupling component is used. Background Art

[0002] The present invention can be used primarily in electric scroll refrigerant compressors for motor vehicles. A scroll compressor typically has a compressor housing and two staggered spirals located inside the compressor housing. One of the two staggered spirals is fixed, while the other spiral is able to move eccentrically on a circular trajectory, the movable spiral also being referred to as a moving spiral or scroll. Due to the movement of the spirals, the volume of the compression chamber formed between the spirals changes periodically, wherein a gaseous fluid, such as a refrigerant, is sucked in and compressed. The movable spiral is typically moved on a circular trajectory by means of an eccentric drive. The eccentric drive is formed by a drive shaft and a counterweight, which rotates around an axis of rotation, and the counterweight is connected to the drive shaft in a rotationally fixed manner and therefore rotates with the drive shaft.

[0003] In the prior art, a rotatable compressor coupling part with an integrally formed counterweight is used to transmit the drive torque from the drive shaft to the movable screw of the scroll compressor. This means that the eccentric drive comprises at least one drive shaft rotating about an axis of rotation and a compressor coupling part rotating with the drive shaft and having a counterweight, and that the movable screw is eccentrically connected to the drive shaft via the compressor coupling part, wherein the axis of the movable screw and the axis of the drive shaft are offset from each other.

[0004] The compressor coupling part comprises a planar body as an inner part, the axis of rotation about which the compressor coupling part can rotate extending vertically through the plane of the planar body. The planar body is also referred to as an axial extension of the drive shaft and can be connected to the drive shaft, for example, via a connecting neck. In addition, the compressor coupling part rotating with the drive shaft has a counterweight as an outer part, which has an arcuate outer contour and is at least partially in the form of a hollow cylindrical section. The counterweight is offset backwards relative to the planar body in the axial direction of the axis of rotation, and the lateral surface of the hollow cylindrical section therefore encloses a part of the circumference of the drive shaft in the end region of the shank of the drive shaft.

[0005] For connection to the compressor coupling part, the drive shaft can have an eccentrically offset connection neck which is integrally formed, inserted or fastened on the end face of the drive shaft and whose longitudinal axis is oriented offset parallel to the longitudinal axis of the drive shaft.

[0006] In particular, carbon steel is used as material for the compressor coupling components.This design was sufficient for the previous use range with a limited maximum rotational speed.

[0007] The range of use of compressor coupling components with integrally formed counterweights is limited in rotational speed by the loads occurring during operation due to the required shape. The present invention aims to allow the use of both cost-effective manufacturing processes and materials and to allow the range of use to be extended to higher rotational speeds.

[0008] The compressor coupling component with a counterweight is a connecting element that transmits the driving force from the drive shaft to the scroll compression unit. The compressor coupling component includes: a coupling neck having a hole receiving portion for the coupling neck of the drive shaft; and a counterweight block, which is used to partially balance the system-induced imbalance of the scroll compression unit.

[0009] The loads during operation generate local stresses at the connection of the sleeve and the counterweight body, which limits the operating range according to the material properties and geometry / proportions of the parts. This applies to an increase in the operating range of the compressor. The maximum speed should be 11,000 revolutions per minute, compared to the previous limit of approximately 9,000 revolutions per minute.

[0010] Cost is the driving parameter for competitiveness. In order to offer significant savings potential, the metal powder forming process was selected. Metal powder alloys have a lower mechanical load capacity due to the reduced elastic modulus and reduced yield stress. In the standard form of the compressor coupling components, the structural stresses that occur during operation limit the operating range of the components.

[0011] The loads during operation generate local stresses on the connection connecting the neck and the counterweight body, which limits the operating range according to the material properties and the geometry or proportions of the parts. As the mechanical parameters of the sintered alloy decrease and the range of operating conditions expands, the usual shapes of compressor coupling components in the prior art do not have the required robustness for operation.

[0012] The driving parameter for component loads and local stresses is the compressor speed, expressed as the rotor rotation speed in revolutions per minute. The maximum speed increases up to 11,000 revolutions per minute.

[0013] Under the given operating conditions, local stresses on the connection of the counterweight body and the planar body ensure that the designs known from the prior art are not suitable for use with metal sintered alloys. Summary of the invention

[0014] Technical issues

[0015] The object of the present invention is to design a compressor coupling component with an integrally formed counterweight which is cost-effective to produce, wherein the compressor coupling component should at the same time be suitable for operation at high rotor rotational speeds, ie up to at least 11,000 revolutions per minute.

[0016] Technical Solution

[0017] This object is achieved by a compressor coupling component, which is suitable for coupling a drive shaft and a movable spiral in a scroll compressor, such as a refrigerant compressor, having the features according to claim 1. Developments are described in the dependent claims.

[0018] The compressor coupling component comprises:

[0019] a planar body having a first front side and a second rear side opposite the first side,

[0020] a cylindrical coupling neck which is integrally formed on or fastened to or inserted into a planar body, wherein a cylinder axis of the cylindrical coupling neck extends perpendicularly to the plane of the planar body and the cylindrical coupling neck protrudes from the planar body in an axial direction relative to the cylinder axis of the coupling neck on a front side of the planar body,

[0021] A counterweight, which is at least partially formed in the shape of a hollow cylindrical section, has an arcuate outer contour, is integrally formed on an outer area of ​​the planar body and protrudes beyond the planar body in an axial direction on the rear side of the planar body, the outer area only partially enclosing a cylindrical connecting neck and a neck surrounding area, which extends coaxially with the cylinder axis and completely encloses the connecting neck.

[0022] According to the invention, the planar body has relative outer edge areas, which - starting from an arched base edge area of ​​the planar body that only partially encloses the neck surrounding area - extend as far as the ends of the counterweight element that are opposite to each other in the arc direction of the counterweight element, and extend linearly in the manner of gradually spaced V-shaped legs with respect to the outer contour of the planar body.

[0023] Therefore, the present invention proposes a new connection design of the body, the coupling neck and the counterweight. Compared with the prior art, by widening the planar body into a V-shape, the rigidity and robustness of the compressor coupling component are significantly increased.

[0024] Compared to the prior art, the present invention makes possible a more robust design with comparable installation space requirements. A compressor coupling component designed in this way can be produced by forming a powder metal alloy, for example using a steel powder pressing method, which allows material and cost savings compared to a forging process. It is estimated that the achievable cost savings are 40% to 60%. At the same time, the more robust design allows higher operating loads resulting from high rotor rotation speeds. Therefore, the compressor coupling component produced by the metal powder forming process will be suitable for working under given load conditions. This means that the compressor coupling component is suitable for operating at a rotor rotation speed of 11,000 revolutions per minute. Therefore, the compressor coupling component can replace components designed according to the prior art with the same functionality and much lower costs.

[0025] The connection design according to the invention significantly reduces the local maximum stress. This is achieved by the connection design of the planar body, the coupling neck and the counterweight according to the invention.

[0026] Compared to the compressor coupling part formed according to the prior art, due to the V-shaped widening, not only the rigidity and robustness of the compressor coupling part are significantly increased, but also the widened portion obtained can be used for the combination of an additional supporting element. Therefore, a supporting element or multiple supporting elements can be formed in the area of ​​the planar body adjacent to the outer edge area extending in the manner of the V-legs, so as to further strengthen the compressor coupling part. According to an advantageous embodiment, the supporting element is a reinforcing rib of a rib structure, which protrudes from the planar body in the axial direction on the rear side of the planar body. An embodiment in which the rib structure with reinforcing ribs extends from the planar body as far as the counterweight is particularly preferred. Preferably, the rib structure includes two reinforcing ribs as additional supporting elements, each of which is adjacent to one of the outer edge areas of the opposite outer edge areas and extends as far as one of the ends of the counterweight that are opposite to each other in the arc direction. Advantageously, the reinforcing rib as an additional supporting element protrudes in the axial direction relative to the cylinder axis on the rear side of the planar body just as far as the counterweight protrudes beyond the planar body on the rear side.

[0027] For connection to the drive shaft of the scroll compressor, the cylindrical coupling neck advantageously has a receiving bore which is oriented eccentrically with respect to the cylinder axis.

[0028] A further aspect of the invention therefore relates to a scroll compressor for gaseous fluids, in which the compressor coupling component according to the invention is used as part of an eccentric drive.

[0029] This scroll compressor includes:

[0030] A compressor housing and two staggered spirals located inside the compressor housing, wherein one spiral is fixed and the other spiral is able to move eccentrically on a circular trajectory, and the volume of the compression chamber formed between the spirals can be periodically changed by the movement of the spirals, and

[0031] An eccentric drive, by means of which a movable screw can be moved on a circular trajectory, and which comprises a rotatable drive shaft and a compressor coupling part according to the invention which can rotate together with the drive shaft, wherein the movable screw is eccentrically connected to the drive shaft via the compressor coupling part. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Further details, features and advantages of embodiments of the present invention can be found in the following description of exemplary embodiments with reference to the associated drawings. In the drawings:

[0033] Figure 1A : shows a compressor coupling component for coupling a drive shaft and a movable spiral member of a scroll compressor according to the prior art, the compressor coupling component having a planar body, a counterweight and a coupling neck,

[0034] Figure 1B : Schematic diagram showing the area of ​​local maximum stress in the compressor coupling component during operation,

[0035] Figure 2 : A comparison diagram showing a compressor coupling component formed according to the prior art and a compressor coupling component designed according to an exemplary embodiment of the present invention,

[0036] Figure 3 : A schematic diagram showing a comparison of a compressor coupling component formed according to the prior art and a compressor coupling component designed according to an exemplary embodiment of the present invention in terms of local maximum stress in the region of a planar body,

[0037] Figure 4 : shows a compressor coupling component with an indicated widening,

[0038] Figure 5A : shows a perspective view of a compressor coupling component looking toward the front side with a coupling neck,

[0039] Figure 5B : shows a perspective view of the compressor coupling component looking towards the rear side with the receiving space for the end of the drive shaft, and

[0040] Figure 6 A bar graph comparing the local maximum stresses of different compressor coupling components at different rotor rotational speeds is shown. DETAILED DESCRIPTION

[0041] Figure 1A A compressor coupling component 1* formed according to the prior art is shown, which is used to connect a drive shaft (not shown) and a movable spiral member of a scroll compressor (not shown). This compressor coupling component 1* includes a planar body 2*, on which a cylindrical coupling neck 3* is integrally formed or fastened to the planar body 2* or the cylindrical coupling neck 3* is inserted, wherein a barrel axis 4* of the cylindrical coupling neck 3* extends perpendicular to the plane of the planar body 2*, and the cylindrical coupling neck 3* protrudes from the planar body 2* in an axial direction relative to the longitudinal axis of the coupling neck 3* on a first front side 2a* of the planar body 2*. A receiving hole 5* is formed by the cylindrical coupling neck 3*, which is eccentrically oriented relative to the barrel axis 4* of the cylindrical coupling neck 3* and is designed to receive a drive shaft (also in Figure 1A The area of ​​the planar body 2* that is directly supported against the connection neck 3* and also extends coaxially with the cylinder axis 4* and completely encloses the entire circumference of the connection neck 3* and the area that is directly supported against the connection neck shall be referred to as the neck surrounding area 6* in the following.

[0042] In addition, a counterweight 8* having an arched outer contour is integrally formed on an outer region 7* of a partially enclosed neck enclosing region 6* of the planar body 2* and has the shape of a hollow cylindrical section, and a cylindrical axis 9* of the counterweight 8* extends parallel to the cylindrical axis 4* of the cylindrical connecting neck 3* and is at a certain distance from the cylindrical axis 4* of the cylindrical connecting neck 3*. Therefore, the outer region 7* connects the neck enclosing region 6* of the planar body 2*, which is supported against the connecting neck 3*, to the counterweight 8*. The counterweight 8* also protrudes in the axial direction beyond the planar body 2*, but mainly protrudes on the second rear side 2b* of the planar body 2* opposite to the front side 2a* having the cylindrical connecting neck 3*. Since the counterweight 8* is at least partially in the form of a hollow cylindrical section, the counterweight 8* partially encloses the body 2* on one side, more precisely the outer region 7* of the body 2*, and thereby provides a space for partially receiving the drive shaft (at the inner side of the hollow cylindrical section) at the inner side of the hollow cylindrical section. Figure 1A The receiving cavity 10* in the end area of ​​the shank (not shown).

[0043] The material for such a compressor coupling component 1* is in particular carbon steel, wherein the compressor coupling component 1* is usually produced by forging and post-machining of at least some of the component surfaces; this applies in particular to the surface area of ​​the planar body 2*, the surface area of ​​the coupling neck 3* and the surface area of ​​the receiving hole 5* extending through the body 2* and the coupling neck 3*. This design is sufficient for the previous range of use with a limited maximum rotational speed.

[0044] The loads during operation generate local stresses on the connection between the connection neck 3* and the body of the counterweight 8*, which limits the operating range according to the material properties and geometry / proportions of the compressor connection part 1*. With the reduction of the mechanical parameters of the sintered alloy and the expansion of the range of operating conditions, the usual shape of the compressor connection part 1* in the prior art does not have the required robustness for operation. The driving parameter for component loads and local stresses is the speed or rotation speed of the compressor, which can reach a maximum of 11,000 revolutions per minute. Under given operating conditions, the local stresses in the connection area of ​​the counterweight 8* and the planar body 2* ensure that the designs known from the prior art are not suitable for the use of metal sintered alloys. Figure 1B The various regions of different loading levels of the compressor coupling part 1* at a compressor rotational speed of 11,000 revolutions per minute are schematically indicated by means of different shadings, and also the regions of local maximum stress 11* occurring at the edges of the outer region 7* of the planar body 2* of the compressor coupling part 1*. As already mentioned, the outer region 7* is the region connecting the neck enclosing region 6* of the planar body 2* to the counterweight 8*, which neck enclosing region 6* bears against the coupling neck 3* and completely encloses the coupling neck 3*.

[0045] Figure 2Comparative schematic diagrams of compressor coupling parts 1*, 1** formed according to the prior art, i.e., one compressor coupling part 1* produced by a forging process and one compressor coupling part 1** produced by a sintering process with the same design, and a compressor coupling part 1 designed according to an exemplary embodiment of the present invention. In addition, for the compressor coupling part 1*, the reception of the shank end region of the drive shaft 12 in the receiving cavity 10* formed by the inner side of the counterweight 8* is shown by way of example, wherein the position of the rotation axis 13 of the drive shaft 12 is also indicated in the stereoscopic views of the other compressor coupling parts 1**, 1, in which the corresponding receiving spaces 10**, 10 for the shank end region of the drive shaft 12 partially enclosed in each case by the inner side of the counterweight 8**, 8 and the receiving holes 5**, 5 in each case in the coupling neck 3**, 3 for receiving the connecting neck (not shown), which starts from the shank of the drive shaft 12 and can be formed integrally, inserted or fastened on the end face of the drive shaft can be seen.

[0046] The compressor coupling part 1 formed according to an exemplary embodiment of the invention has a planar body 2 which is formed in such a way that the opposite outer edge regions 14, 15 - starting from an arched base edge region 16 of the planar body 2 which partially surrounds the neck surrounding region 6 - extend linearly in each case as far as one of the ends of the counterweight 8 which are opposite to each other in the arc direction in terms of the outer contour of the outer edge regions 14, 15 in the manner of gradually spaced-apart V-shaped legs. In this way, the area of ​​the planar body 2 is widened compared to the body 2*, 2** of the compressor coupling parts 1*, 1** formed according to the prior art, wherein this widening shall be referred to below as V-shaped widening of the planar body 2. Due to the V-shaped widening, the rigidity and robustness of the compressor coupling part 1 are significantly increased compared to the compressor coupling parts 1*, 1** from the prior art.

[0047] Figure 3 In the corresponding comparative schematic views of different compressor coupling parts 1*, 1** and 1, the regions of different degrees of operation-induced loads and the position and size of the regions 11*, 11**, 11 of local maximum stresses on the planar bodies 2*, 2** and 2 are indicated in each case by means of shading. The local maximum stresses in the compressor coupling part 1 formed according to the exemplary embodiment of the invention are much smaller than the local maximum stresses in the compressor coupling parts 1*, 1** from the prior art.

[0048] Figure 4A comparison diagram is included that combines a front view of a compressor coupling component 1* designed according to the prior art with a front view of a compressor coupling component 1 formed according to an exemplary embodiment of the present invention. The comparison diagram allows to see the first front side 2a*, 2a of the planar body 2*, 2, the end face of the cylindrical coupling neck 3*, 3, and the front end face 17*, 17 of the cylindrical segment-shaped counterweight 8*, 8 of the corresponding compressor coupling element 1*, 1, which protrudes from the front side 2a*, 2a of the planar body 2*, 2 and has a receiving hole 5*, 5 oriented eccentrically with respect to the cylinder axis 4 of the cylindrical coupling neck 3*, 3. In the combined diagram, compared with the planar body 2* designed according to the prior art, the widening 18, 19 of the planar body 2 caused by the V-shaped form of the outer edge area 14, 15 starting from the base edge area 16 is indicated.

[0049] Figure 5A and Figure 5B A compressor coupling component 1 formed according to an exemplary embodiment of the present invention is shown in a perspective view. Figure 5A In the figure is a compressor coupling part 1 viewed towards the front side with a coupling neck 3, and in ... Figure 5B In the figure, the compressor coupling part 1 is seen towards the rear side with a receiving space 10 for the end of a drive shaft (not shown), which receiving space 10 is partially enclosed by the inner side of the counterweight 8. Figure 5A The front end face of the coupling neck 3 is shown, on which the front opening of the receiving hole 5 is located, which is designed to receive the connecting neck of the drive shaft (not shown), and Figure 5B The rear end face of the coupling neck 3 is shown, which is provided with an opposite rear opening of the receiving hole 5, wherein the circumference of the coupling neck 3 on the rear end face of the coupling neck 3 is completely enclosed by the neck surrounding area 6 of the planar body 2. In the embodiment shown, the coupling neck 3 is inserted into the planar body 2.

[0050] The neck surrounding area 6 is the area of ​​the planar body 2. Figure 5A As can be seen in FIG. 4 , this region extends coaxially with the cylinder axis 4 of the cylindrical coupling neck 3 and encloses the entire circumference of the coupling neck 3 at the rear end of the coupling neck 3 .

[0051] The planar body 2 - starting from an arched base edge region 16 of the planar body 2 which partially surrounds the neck enclosing region 6 - has opposite outer edge regions 14, 15 which, in terms of their outer contour, extend in the manner of gradually spaced-apart V-legs as far as the counterweight 8. Due to the V-shaped widening, not only is the rigidity and robustness of the compressor coupling component 1 significantly increased compared to compressor coupling components formed according to the prior art, but the widening obtained can also be used for the incorporation of an additional supporting element 20, for example in the form of two combined rib structures, each of which protrudes in the axial direction relative to the cylinder axis 4 of the coupling neck 3 on the front side of the planar body 2 and at the same time extends from the widening 18, 19 of the planar body 2 as far as the counterweight 8, or extends or merges into the counterweight 8, the widening 18, 19 each being supported in the manner of V-legs against the edge regions 14, 15 oriented towards each other. Figure 5A and Figure 5B It can be seen that the reinforcing rib as additional supporting element 20 protrudes on the rear side 2b of the planar body 2 in the axial direction relative to the cylinder axis 4 just as far as the counterweight 8 protrudes beyond the planar body 2 on the rear side 2b.

[0052] exist Figure 6 In the bar diagram of FIG. 1 , the local maximum stresses of different compressor coupling parts 1*, 1**, 1 are compared at different rotor rotational speeds. The local maximum stresses are indicated on one side in an absolute sense in the unit [N / mm2], and on the other side, the diagram also allows a relative figure compared with the local maximum stress occurring at 8600 revolutions per minute in a forged compressor coupling part 1* formed according to the prior art as a reference value, which corresponds to 100% shown on the right axis of the diagram. As shown in the diagram, the connection design according to the invention reduces the local maximum stresses at all rotor rotational speeds to well below 100%, and therefore also to below the maximum permissible operation-induced load of the compressor coupling part 1.

Claims

1. A compressor coupling component (1) for coupling a drive shaft and a movable spiral member in a scroll compressor, comprising: a planar body (2), the planar body (2) having a first front side (2a) and a second rear side (2b) opposite to the first side, a cylindrical coupling neck (3) which is integrally formed on the planar body (2) or fastened to the planar body (2) or inserted into the planar body (2), wherein a cylindrical axis (4) of the cylindrical coupling neck (3) extends perpendicularly to the plane of the planar body (2), and the cylindrical coupling neck (3) protrudes from the planar body (2) in an axial direction relative to the cylindrical axis (4) of the cylindrical coupling neck (3) on the front side (2a) of the planar body (2), a counterweight (8) at least partially formed in the shape of a hollow cylindrical section, having an arcuate outer contour, integrally formed on an outer region (7) of the planar body (2) and protruding beyond the planar body (2) in the axial direction on the rear side (2b) of the planar body (2), the outer region (7) only partially enclosing the cylindrical coupling neck (3) and a neck surrounding region (6), the neck surrounding region (6) extending coaxially with the cylinder axis (4) and completely enclosing the cylindrical coupling neck (3), The planar body (2) has relative outer edge regions (14, 15), which extend from an arched base edge region (16) of the planar body (2) that partially encloses the neck surrounding region (6) to ends of the counterweight (8) that are opposite to each other in the arc direction of the counterweight (8), and extend linearly in the form of gradually spaced V-shaped legs in terms of the outer contour of the planar body (2).

2. The compressor coupling component (1) according to claim 1, characterized in that A support element (20) or a plurality of support elements (20) are additionally formed in the area of ​​the planar body (2) adjacent to the outer edge areas (14, 15) extending in the manner of V-legs in order to reinforce the compressor coupling component (1).

3. The compressor coupling component (1) according to claim 2, characterized in that The additional supporting element (20) is a reinforcing rib of a rib structure which protrudes from the planar body (2) in the axial direction on the rear side (2b) of the planar body (2).

4. The compressor coupling component (1) according to claim 3, characterized in that The rib structure with the reinforcing ribs as additional supporting elements (20) extends as far as the counterweight (8).

5. The compressor coupling component (1) according to claim 3 or 4, characterized in that The rib structure comprises two reinforcing ribs as additional supporting elements (20), each of which is adjacent to one of the opposite outer edge regions (14, 15).

6. The compressor coupling component (1) according to claim 5, characterized in that The two reinforcing ribs as additional supporting elements (20) each extend as far as one of the ends of the counterweight (8) that are opposite to each other in the arc direction.

7. Compressor coupling component (1) according to one of claims 3 to 6, characterized in that The reinforcing rib as an additional supporting element (20) protrudes on the rear side (2b) of the planar body (2) in the axial direction just as far as the counterweight (8) protrudes beyond the planar body (2) on the rear side (2b).

8. Compressor coupling component (1) according to one of claims 1 to 7, characterized in that The compressor coupling component (1) is produced by a metal powder forming process.

9. The compressor coupling component (1) according to claim 8, characterized in that The compressor coupling component (1) is produced by a steel powder pressing method.

10. Compressor coupling component (1) according to one of claims 1 to 9, characterized in that The cylindrical coupling neck (3) has a receiving hole (5) oriented eccentrically with respect to the cylindrical body axis (4).

11. A scroll compressor for gaseous fluid, comprising: A compressor housing and two staggered spirals located inside the compressor housing (2), wherein one spiral is fixed and the other spiral is eccentrically movable on a circular trajectory, and the volume of the compression chamber formed between the spirals can be periodically changed by the movement of the spirals, An eccentric drive, by means of which the movable screw can be moved on a circular trajectory, and the eccentric drive comprises a rotatable drive shaft (12) and a compressor coupling part (1) according to one of claims 1 to 10, the compressor coupling part being rotatable together with the drive shaft (12), wherein the movable screw is eccentrically connected to the drive shaft (12) via the compressor coupling part (1).

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