BALANCING MECHANISM FOR SCROLL COMPRESSORS

Abstract

A balancing mechanism for a positive displacement machine, in particular a scroll compressor, wherein the balancing mechanism includes a drive shaft, a first balancing element and a second balancing element. The first balancing element includes a cylindrical hub section and a first force transmission section and is rotatably in contact with the drive shaft via a first axis of rotation. The second balancing element is rotatably in contact with the drive shaft via a second axis of rotation. A center axis S of the drive shaft and a center axis C of the cylindrical hub section are arranged on a first reference line CS, and a center of gravity J of the first balancing element and a center of gravity K of the second balancing element are arranged on a different side of the first reference line CS than a center axis P of the first axis of rotation.

Claims

1. Balancing mechanism for a positive displacement machine according to the scroll principle, in particular a scroll compressor, wherein the balancing mechanism comprises a drive shaft, a first balancing element and a second balancing element, wherein the first balancing element comprises a cylindrical hub section and a first force transmission section and is rotatably in contact with the drive shaft via a first axis of rotation, and the second balancing element is rotatably in contact with the drive shaft via a second axis of rotation, and wherein a center axis S of the drive shaft and a center axis C of the cylindrical hub section are arranged on a first reference line CS, and wherein a center of gravity J of the first balancing element and a center of gravity K of the second balancing element are arranged on another side of the first reference line CS than a center axis P of the first axis of rotation.

2. Balancing mechanism according to claim 1, that wherein the hub section comprises an eccentrically arranged fitting hole in which the first axis of rotation engages.

3. Balancing mechanism according to claim 1, wherein the second balancing element comprises an engagement hole in which the second axis of rotation engages.

4. Balancing mechanism according to claim 1, wherein the first axis of rotation is fixedly, in particular monolithically, and eccentrically connected to the hub section and is rotatably mounted in a first blind hole of the drive shaft.

5. Balancing mechanism according to claim 1, wherein the second axis of rotation is fixedly, in particular monolithically, connected to the second balancing element and is rotatably mounted in a second blind hole of the drive shaft.

6. Balancing mechanism according to claim 1, wherein the second balancing element is arranged between the first balancing element and a drive shaft bearing.

7. Balancing mechanism according to claim 1, wherein the first balancing element comprises a first force transmission section.

8. Balancing mechanism according to claim 1, wherein the second balancing element comprises a mass section and a second force transmission section arranged on the same side of a second reference line PQ connecting the center axis P of the first axis of rotation and a center axis Q of the second axis of rotation.

9. Balancing mechanism according to claim 8, wherein the second force transmission section of the second balancing element is in force-transmitting contact with the first force transmission section of the first balancing element.

10. Balancing mechanism according to claim 1, wherein the first balancing element and the second balancing element are each formed in one piece, in particular monolithically.

11. Balancing mechanism according to claim 1, wherein the drive shaft comprises a spacer element extending around the first axis of rotation and having a height greater than the thickness of the second balancing element in the region of the engagement hole.

12. Balancing mechanism according to claim 8, wherein the first balancing element comprises a web rising towards the drive shaft and forming a stop for the mass section of the second balancing element.

13. Positive displacement machine according to the scroll principle, in particular scroll compressor, with a balancing mechanism according to claim 1.

14. Positive displacement machine according to claim 13, wherein the hub section carries a scroll bearing which is connected to a movable displacement spiral, in particular a displacement spiral which orbits during operation, the movable displacement spiral engaging a stationary displacement spiral.

Description

[0025] The invention is explained in more detail below by means of an example of an embodiment with reference to schematic drawings. Therein show

[0026] FIG. 1 longitudinal section through a balancing mechanism according to the invention in the installed state within a positive displacement machine according to the scroll principle;

[0027] FIG. 2 perspective top view of the balancing mechanism according to FIG. 1 in the installed state;

[0028] FIG. 3 perspective side view of the balancing mechanism according to FIG. 1, additionally showing a scroll bearing of a movable displacement spiral of the positive displacement machine;

[0029] FIG. 4 perspective detail view of the balancing mechanism according to FIG. 1, wherein the first balancing element is hidden for improved visualization of the second balancing element;

[0030] FIG. 5 perspective view of the balancing mechanism according to FIG. 1 with both balancing elements;

[0031] FIG. 6 side view of the balancing mechanism according to FIG. 5; and

[0032] FIG. 7 geometric representation of the position of the center axes and centers of gravity of different components of the balancing mechanism according to FIG. 1, where forces that occur are also shown.

[0033] FIG. 1 shows a cross-sectional view of a balancing mechanism according to an embodiment according to the invention. The balancing mechanism comprises a drive shaft 10, which is mounted in a partition wall 42 of a compressor housing via a scroll-side drive shaft bearing 34. The drive shaft 10 is further supported at an opposite end also in a housing-side shaft bearing, which is not shown in FIG. 1 for clarity. The partition wall 42 is usually fixedly arranged in an outer housing of a positive displacement machine, preferably a positive displacement machine according to the scroll principle, in particular a scroll compressor. The partition wall 42 separates a compressor area from a drive area within the positive displacement machine. In the drive area, the majority of the drive shaft 10 is arranged, which is driven mechanically or, particularly preferably, electrically, in particular by an electric motor. The electric motor is preferably also arranged in the drive area.

[0034] In the drive area, the drive shaft 10 also comprises two counterweights 14, 15. Here, a first counterweight 14 is arranged at an end of the drive shaft 10 facing away from the compression area and is firmly connected to the drive shaft 10. A second counterweight 15 is arranged on a side of the drive shaft 10 facing the compaction area, in particular in the immediate vicinity of the partition wall 42. The second counterweight 15 is also firmly connected to the drive shaft 10. The counterweights 14, 15 thus rotate with the drive shaft 10 during operation and thus compensate for imbalances.

[0035] The drive shaft bearing 34 is held in the partition wall 42. In particular, the drive shaft bearing 34 can be press-fitted to the partition wall 42, which comprises a corresponding recess for this purpose. Furthermore, the drive shaft 10 may be press-fitted into the drive shaft bearing 34. The drive shaft bearing 34 is preferably designed as a ball bearing.

[0036] Two blind holes 16, 17 are provided at the end of the drive shaft 10 facing the compression area. A first blind hole 16 accommodates a first axis of rotation 11. A second blind hole 17 accommodates a second axis of rotation 12. The first blind hole 16 preferably comprises a larger cross-sectional diameter than the second blind hole 17. The axes of rotation 11, 12 are each pressed into their respective blind holes 16, 17. Thus, there is a non-positive, non-rotating connection between the respective axis of rotation 11, 12 and the associated blind hole 16, 17.

[0037] FIG. 1 also clearly shows that the blind holes 16, 17 or axes of rotation 11, 12 are arranged off-center with respect to a center axis of the drive shaft 10. Thus, the axes of rotation 11, 12 are not aligned coaxially with the drive shaft 10, but are offset substantially eccentrically with respect to the center axis of the drive shaft 10.

[0038] In addition, the drive shaft 10 comprises an extension in the region of the first axis of rotation 11, which forms a spacer element 13. The spacer element 13 is formed integrally with the drive shaft 10. In particular, the spacer element 13 may be formed as an annular projection. The blind hole 16 extends through the spacer element 13, preferably with a constant internal cross-sectional diameter along the entire length of the blind hole 16.

[0039] The second axis of rotation 12 projects beyond the longitudinal end of the drive shaft 10. However, the portion of the second axis of rotation 12 projecting beyond the second blind hole 17 includes a height that is preferably less than the height of the spacer element 13. The two axes of rotation 11, 12 each accommodate balancing elements 20, 30, which are described in more detail below.

[0040] A first balancing element 20 is arranged on the first axis of rotation 11. The first balancing element 20 is pivotally mounted on the first axis of rotation 11. Specifically, the first balancing element 20 comprises a hub section 21 that is substantially cylindrically shaped. The hub section 21 includes a fitting hole 23 in which the first axis of rotation 11 engages. A clearance exists between the first axis of rotation 11 and the fitting hole 23, such that the hub section 21 or the first balancing element 20 can generally rotate or pivot about the first axis of rotation 11. In this respect, there is substantially a sliding bearing between the fitting hole 23 and the first axis of rotation 11.

[0041] The hub section 21 extends into a scroll bearing 41. The hub section 21 is preferably press-fitted to the scroll bearing 41. The scroll bearing 41 is arranged in a scroll bearing seat of a movable displacement spiral 40. Preferably, the scroll bearing 41 is formed by a ball bearing. Preferably, the scroll bearing 41 is press-fitted to the movable displacement spiral 40.

[0042] The movable displacement spiral 40 is only partially shown in FIG. 1. In any case, it can be seen that the movable displacement spiral 40 comprises spiral walls 44, which are, however, only indicated in FIG. 1. Usually, the spiral walls 44 comprise a greater height than that shown schematically here. The spiral walls 44 engage in corresponding spiral walls of a fixed, in particular stationary, displacement spiral arranged opposite, which is also not shown in FIG. 1 for reasons of clarity.

[0043] The movable displacement spiral 40 is guided by guide pins 43 which are firmly connected to the housing of the compressor. The guide pins engage in corresponding guide spaces 45 of the movable displacement spiral 40 and prevent the movable displacement spiral 40 from rotating. Rather, the movable displacement spiral 40 is intended to orbit, i.e., to follow a predetermined, orbital path of motion.

[0044] FIG. 2 shows the balancing mechanism in a plan view. The direction of view in FIG. 2 is essentially from the compression chamber of the compressor toward the drive chamber of the compressor. In particular, the partition wall 42 into which the drive shaft bearing 34 is pressed can be seen. The balancing elements 20, 30 are arranged in a space in the partition wall 42 further above the drive shaft bearing 34. The first balancing element 20 comprises the hub section 21 in which the fitting hole 23 is formed. The fitting hole 23 is recognizably oriented off-center in the hub section 21. Thus, the center axis of the first axis of rotation 11 is not aligned with the center axis of the cylindrical hub section 21, but rather comprises a distance from the center axis of the hub section 21. Preferably, the hub section 21 comprises a height corresponding to the height of the portion of the first axis of rotation 11 projecting beyond the first blind hole 16.

[0045] The first balancing element 20 further comprises a first force transmission section 22 integrally connected to the hub section 21. The first force transmission section 22 comprises a first recess 22a. The first recess 22a has a substantially triangular shape, in particular a right-angled triangular shape. In this respect, the first recess 22a forms an area of reduced wall thickness of the first force transmission section 22, which serves to reduce the weight of the first force transmission section 22. The first force transmission section 22 comprises an overall substantially L-shape extending in the manner of a radially outwardly extending arm from the hub section 21. The first balancing element 20 is integrally formed as a whole.

[0046] A second force transmission section 32 is in contact with the first force transmission section 22 in the circumferential direction. The second force transmission section 32 is part of the second balancing element 30. The second balancing element 30 further comprises a mass section 31, which is spaced apart from the second force transmission section 32 in the circumferential direction of the drive shaft bearing 34. With respect to the second axis of rotation 12, the mass section 31 and the second force transmission section 32 are thus arranged at an obtuse angle to each other. The second balancing element 30 is also integrally formed as a whole.

[0047] It can also be seen in FIG. 2 that the second balancing element 30 is arranged in the longitudinal axial direction of the drive shaft 10 between the drive shaft bearing 34 and the first balancing element 20. However, at least in the force transmission sections 22, 32, there is an overlap in the longitudinal axial direction of the drive shaft 10, so that the force transmission sections 22, 32 of the two balancing elements 20, 30 can rest against each other. In this case, the force transmission sections 22, 32 abut one another in the circumferential direction or in the direction of rotation of the drive shaft 10. In the longitudinal axial direction of the drive shaft 10, there is preferably no contact between the balancing elements 20, 30. Rather, the balancing elements 20, 30 should be able to oscillate independently of one another about their respective axes of rotation 11, 12.

[0048] In FIG. 2, it can additionally be seen that the mass section 32 of the second balancing element 30 essentially forms a thickening that also overlaps the first balancing element 20 somewhat in the longitudinal axial direction. This enables space-saving installation of the second balancing element 20, while at the same time allowing the mass required for balancing imbalances to be used in the mass section 31.

[0049] The connecting arm to the second force transmission section 32 includes a second recess 32a, which also forms an area of reduced wall thickness of the second balancing element 30. In this way, material and thus mass is saved in the area of the second force transmission section 32, which provides for improved operation of the balancing mechanism.

[0050] FIG. 3 shows the balancing mechanism again in a perspective side view. In this, in particular, the design of the counterweights 14, 15 and their position and alignment on the drive shaft 10 can be clearly seen. The balancing elements 20, 30 are located at one longitudinal end of the drive shaft 10. Also shown is the scroll bearing 41, which adjoins the longitudinal end of the drive shaft 10 after the balancing elements 20, 30.

[0051] In the detail shown in FIG. 4, the design and position of the second balancing element 30 can be readily seen. The second balancing element 30 comprises an engagement hole 33, which is preferably formed as a through hole. The engagement hole 33 receives the second axis of rotation 12. Preferably, there is a clearance between the engagement hole 33 and the second axis of rotation 12 so that there is substantially a sliding bearing connection between the second axis of rotation 12 and the engagement hole 33. In this way, the second balancing element 30 can oscillate about the second axis of rotation 12.

[0052] A third recess 31a can also be seen in the region of the mass section 31. The third recess 31a reduces the material of the mass section 31 in areas, resulting in an improved mass distribution in the mass section 31. This mass distribution has been found to be particularly advantageous for reducing vibrations in a scroll compressor. In FIG. 4, it can also be seen that the spacer element 30 comprises a height that is greater than the thickness of the second balancing element 30 in the region of the extension of the drive shaft 10. This ensures that the first balancing element 20, which is seated on the first axis of rotation 11 and abuts the spacer element 13, maintains a distance from the second balancing element 30 in the longitudinal axial direction of the drive shaft 10.

[0053] In FIGS. 5 and 6, it can also be seen that the first balancing element 20 comprises a web 24 extending toward the drive shaft 10 in the longitudinal axial direction of the drive shaft 10. The web 24 is arranged on an outer side of the first balancing element 20 and extends substantially at a distance around the hub spacing 21 to the first force transmission section 22. The web 24 forms an abutment 25 in a region opposite the first force transmission section 22. The abutment 25 overlaps the mass section 31 of the second balancing element 30 in the longitudinally axial direction of the drive shaft 10, so that the mass section 31 can abut the abutment 25. Thus, relative vibration between the first balancing element 20 and the second balancing element 30 is limited. In essence, the second balancing element 30 can oscillate relative to the first balancing element 20 only in a range limited by the abutment 25 on the one hand and by the first force transmission section 22 on the other hand.

[0054] The position of the center axes and centers of gravity of different components of the balancing mechanism is of great importance for the smooth running of a positive displacement machine, in particular a scroll compressor, which is particularly advantageous in the invention. This particular arrangement of center axes or rotational axes and centers of gravity will be explained in more detail below on the basis of the geometric representation shown in FIG. 7.

[0055] In FIG. 7, the cross sections of the drive shaft 10, the first axis of rotation 11, the second axis of rotation 12 and the hub section 21 are shown by circles. Two further circles indicate the respective mass of the force transmission sections 22, 32.

[0056] The drive shaft 10 comprises a center axis S. The hub section 21 comprises a center axis C. It can be seen in FIG. 7 that the center axis C of the hub section 21 is arranged eccentrically to the center axis S of the drive shaft 10. The line connecting the center axes C, S of the drive shaft 10 and the hub section 21 is referred to as the first reference line CS.

[0057] The first axis of rotation 11 comprises a center axis P. The second axis of rotation 12 comprises a center axis Q. A second reference line PQ extends through the center axes P, Q of the axes of rotation 11, 12.

[0058] The first balancing element 20 comprises a center of gravity J, which is shown in FIG. 7. Also visible is the centrifugal force F.sub.CJ acting on the center of gravity J.

[0059] The second balancing element 30 comprises a center of gravity K, which is shown together with the centrifugal force F.sub.CK acting on it in FIG. 7. Looking at the first reference line CS, it can be seen that the center axis P of the first axis of rotation 11 is arranged on one side of the first reference line CS, whereas the centers of gravity J, K of the balancing elements 20, 30 are arranged on the other side of the first reference line CS. Thus, the arrangement differs substantially from the prior art according to DE 10 2019 108 079 A1, in which the center of gravity of a balancing element is arranged with its center axis of rotation on the same side of the first reference line, i.e., in the prior art, the center axis P and the center of gravity J are thus on the same side of the first reference line CS.

[0060] With reference to the second reference line PQ connecting the center axes of rotation 11, 12, it can be seen that the center of gravity K of the second balancing element 30 is arranged on one side of the second reference line PQ, whereas the center of gravity J of the first balancing element 20 is arranged on the other side of the second reference line PQ. However, the center axis of the hub section 21 of the first balancing element 20 is arranged on the same side as the center of gravity K of the second balancing element 30 with respect to the second reference line PQ. In contrast, the center axis S of the drive shaft 10 is located on the same side of the second reference line PQ as the center of gravity J of the first balancing element 20.

[0061] In other words, the center axes of the hub section 21 of the first balancing element 20 and the drive shaft 10 are located on different sides of the second reference line PQ. Similarly, the centers of gravity J, K of the balancing elements 20, 30 are on different sides of the second reference line PQ. The center axis S of the drive shaft 10 and the center of gravity J of the first balancing element 20 are located on one side of the second reference line PQ, whereas the center axis C of the hub section 21 and the center of gravity K of the second balancing element 30 are located on the other side of the second reference line PQ.

[0062] It can also be seen in FIG. 7 that the center of gravity K of the second balancing element 30 comprises a significantly greater distance from the second reference line PQ than the center of gravity J of the first balancing element 20. The same applies with respect to the first reference line CS. The center of gravity K of the second balancing element 30 comprises a greater distance to the first reference line CS than the center of gravity J of the first balancing element 20. This is preferably achieved by the mass section 31 and the force transmission section 32 of the second balancing element 30 being arranged on the same side of the second reference line PQ. Preferably, the mass section 31 and the second force transmission section 32 of the second balancing element 30 are aligned and arranged with respect to each other such that they are arranged entirely on one side of the second reference line PQ.

[0063] To illustrate that there is a mechanical interaction between the balancing elements 20, 30, FIG. 7 also shows the force FN that occurs when the force transmission sections 22, 32 are in contact. Thus, during operation of the balancing mechanism, the first force transmission section 22 transmits a force to the second force transmission section 32, which generates a corresponding counterforce. Preferably, the force transmission sections 22, 32 are formed such that the force and the counterforce balance each other out.

LIST OF REFERENCE SIGNS

[0064] 10 drive shaft [0065] 11 first axis of rotation [0066] 12 second axis of rotation [0067] 13 spacer element [0068] 14 first counterweight [0069] 15 second counterweight [0070] 16 first blind hole [0071] 17 second blind hole [0072] 20 first balancing element [0073] 21 hub section [0074] 22 first force transmission section [0075] 22a first recess [0076] 23 fitting hole [0077] 24 web [0078] 25 abutment [0079] 30 second balancing element [0080] 31 mass section [0081] 31a third recess [0082] 32 second force transmission section [0083] 32a second recess [0084] 33 engagement hole [0085] 34 drive shaft bearing [0086] 40 movable displacement spiral [0087] 41 scroll bearing [0088] 42 partition wall [0089] 43 guide pin [0090] 44 spiral wall [0091] 45 guide space