Compensation mechanisms for positive displacement machines

Abstract

The present invention relates to a compensation mechanism for a positive displacement machine, in particular a scroll compressor, according to the spiral principle, comprising a drive shaft (10) with a central axis S and a compensation device (20), the latter comprising a cylindrical hub element (30) rotatably supported about a rotation axis P on a first eccentric pin (11) of the drive shaft (10) and a compensation element (40) rotatably supported about a rotation axis J on the hub element (30) and having an eccentrically arranged slot (42) extending radially relative to the rotation axis J, the second eccentric pin (12) of the drive shaft (10) being guided in the slot (42) of the compensation element (40) such that a Scotch yoke mechanism is formed between the slot (42) and the rotation axis J of the compensation element (40).Furthermore, the present invention relates to a positive displacement machine equipped with such a compensation mechanism.

Description

[Technical field]

[0001] The present invention relates to a compensation mechanism for a spiral principle positive displacement machine, in particular a scroll compressor, and to a spiral principle positive displacement machine equipped with such a compensation mechanism. [Background technology]

[0002] Scroll compressors with a compensation mechanism are known from the prior art, for example from German patent application DE 10 2020121442 A1, which belongs to the present applicant. The compensation mechanism serves to compensate for manufacturing tolerances and ensure that the two nested displacement spirals are in good contact with one another. Furthermore, existing oscillations, vibrations and noise are reduced. Further scroll compressors with such a compensation mechanism are known, for example from US patent application US 4,824,346 A and German patent application DE 10 2019108 079 A1. Summary of the Invention [Problem to be solved by the invention]

[0003] The object of the present invention is to proceed from this prior art and to improve a compensation mechanism for a positive displacement machine according to the spiral principle, in particular a scroll compressor, in order to achieve an improved reduction in vibrations with low component complexity. Another object of the present invention is to provide a positive displacement machine according to the spiral principle, in particular a scroll compressor, with such a compensation mechanism. [Means for solving the problem]

[0004] Within the scope of the present invention, this problem is solved by the subject matter of patent claim 1 with regard to the compensation mechanism and by the subject matter of patent claim 15 with regard to the positive displacement machine.

[0005] The invention is therefore based on the idea of ​​providing a compensation mechanism for positive displacement machines according to the spiral principle, in particular scroll compressors, which comprises a drive shaft with a central axis S and a compensation device. The compensation device has a cylindrical hub element rotatably supported about a rotation axis P on a first eccentric pin of the drive shaft. The compensation device further comprises a compensation element rotatably supported about a rotation axis J on the hub element and having an eccentrically arranged slot extending radially relative to the rotation axis J. A second eccentric pin of the drive shaft is guided in the slot of the compensation element in such a way that a Scotch yoke mechanism is formed between the slot and the rotation axis J of the compensation element.

[0006] The invention preferably uses a single compensating element to achieve a reduction in vibrations and thus contribute to the smooth operation of the positive displacement machine. The slot of the compensating element serves to limit the movement of the compensating element in the radial direction relative to the central axis S of the drive shaft. The slot thus determines the direction of movement of the compensating element, which together with the second eccentric pin essentially forms a Scotch yoke mechanism. A movement is thus performed which essentially combines vibration and linear motion. It has been found that this form of movement of the Scotch yoke mechanism compensates manufacturing tolerances particularly well and guarantees a very effective seal between the two displacement spirals. The compensating mechanism according to the invention simultaneously reduces vibrations in the positive displacement machine.

[0007] In a preferred embodiment of the invention, the centre of gravity of the compensating element has a pendulum component in operation, which reciprocates about a connecting line JQ between the rotation axis J of the compensating element and the central axis Q of the slot. The centre of gravity of the compensating element can in particular be arranged radially outside the central axis Q of the slot relative to the central axis S of the drive shaft. In this position, the Scotch yoke mechanism of the compensating element serves to ensure that the centre of gravity of the compensating element has a pendulum component which can be efficiently utilized to compensate for the circumferential manufacturing tolerances of the drive shaft.

[0008] The center of gravity of the compensation element can furthermore have a linear component during operation, the center of gravity moving along the connecting line JQ, the linear component being greater than the pendulum component. The linear component is primarily specified by the slots, thus limiting the rotational or oscillating movement of the compensation element. The linear component of the movement of the center of gravity of the compensation element is preferably aligned radially with respect to the central axis of the drive shaft, which is particularly advantageous for the damping of vibrations and for the sealing between the displacement spirals.

[0009] The compensation element has a rotation axis J and the hub element has a central axis C. In a particularly preferred variant of the invention, the rotation axis J of the compensation element is arranged concentrically with the central axis C of the hub element. In other words, the rotation axis J of the compensation element and the central axis C of the hub element can perfectly coincide. This design reduces the complexity of the compensation mechanism and limits its freedom of movement to an extent suitable for vibration reduction.

[0010] The hub element may further have an eccentric hub hole in which the first eccentric pin of the drive shaft is arranged. Overall, the compensation mechanism has multiple eccentricities, which results in a movement sequence that allows for good sealing between the displacement spirals and reduced noise during operation of the positive displacement machine.

[0011] In another variant of the invention, the compensation element has a retaining hole, via which the compensation element is rotatably supported on the hub element, in such a way that a movement sequence advantageous for vibration reduction is transmitted from the drive shaft to the movable displacement spiral, the retaining hole forming one of a number of rotary joints for the movement sequence.

[0012] The compensation element itself can have a guide and a balance weight, which preferably extends in an arc around the guide. It has been shown that such a design of the compensation element results in a particularly good mass balance in all operating states of the compensation mechanism. In this way, vibration reduction is particularly well achieved.

[0013] The retaining holes and the slots are preferably arranged in a guide part, which connects the rotation axis of the compensating element with the balancing weight, which is arranged as far outwardly as possible from the rotation axis of the compensating element in the radial direction so that the leverage is designed to be as small as possible, and at the same time the distance between the rotation axis of the compensating element and the balancing weight is kept as small as possible so that the compensation mechanism can be integrated compactly in the volumetric machine.

[0014] In order to contribute to a compactness of the compensation mechanism, in a particularly preferred embodiment of the invention, the balance weight extends in the shape of a half ring around the axis of rotation J of the compensation element.

[0015] It is advantageous, particularly for reasons of stability, if the guide part and the balancing weight are formed in one piece, in particular monolithically. The balancing weight as a whole can be formed as a one-piece or monolithic component.

[0016] In another variant of the invention, the first eccentric pin of the drive shaft has a larger diameter than the second eccentric pin of the drive shaft. Alternatively or additionally, the first eccentric pin of the drive shaft can have a larger length than the second eccentric pin of the drive shaft. Furthermore, the hub element can project from the compensation element, in particular the balance weight, along its central axis C. The first and second eccentric pins of the drive shaft transmit different forces and are therefore preferably designed with different dimensions. This contributes to weight optimization. The hub element, on the other hand, preferably extends to the revolving displacement spiral and therefore projects beyond the compensation element so as to transmit a rotational movement to the first displacement spiral.

[0017] To ensure that the hub element rotates as smoothly as possible around the first eccentric pin, the hub element can be rotatably supported on the first eccentric pin of the drive shaft via a plain or needle bearing. Alternatively or additionally, the compensation element can be rotatably supported on the hub element via a plain or needle bearing. A second aspect of the invention relates to a positive displacement machine according to the spiral principle, in particular a scroll compressor, comprising the compensation mechanism described above. In the positive displacement machine according to the invention, the hub element carries a scroll bearing connected to a moving displacement spiral, in particular a displacement spiral that revolves during operation, and the moving displacement spiral can be engaged with a fixed displacement spiral.

[0018] The invention will now be explained in more detail with reference to the accompanying schematic drawings. [Brief description of the drawings]

[0019] [Figure 1] FIG. 1 shows a cross-section of a positive displacement machine according to the invention based on the spiral principle, with a compensation mechanism according to a preferred embodiment, in which a hub element is in contact with a moving displacement spiral via a plain bearing. [Diagram 2] FIG. 2 shows a cross-section of a positive displacement machine according to the invention according to the spiral principle, with a compensation mechanism according to another embodiment, in which the hub element is in contact with the moving displacement spiral via a ball bearing. [Diagram 3] FIG. 3 is an exploded perspective view of the compensation mechanism of the present invention in accordance with a preferred embodiment. [Figure 4] FIG. 4 is a perspective view of the compensation mechanism according to FIG. 3 in an assembled state. [Diagram 5] FIG. 5 is a plan view of the compensation mechanism according to FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0020] 1 and 2 respectively show positive displacement machines based on the spiral principle, which have approximately the same construction. The embodiments shown in Fig. 1 and Fig. 2 differ only in the type of scroll bearing 32 arranged between the hub element 30 and the moving displacement spiral 4. Whereas in the embodiment according to Fig. 1 a plain bearing 32a is provided as scroll bearing 32, the embodiment according to Fig. 2 includes a ball bearing 32b as scroll bearing 32.

[0021] Generally, the positive displacement machines shown in Figures 1 and 2 each have one compressor housing 1, to which an electronics housing 2 is connected. Inside the compressor housing 1, an electric motor 3 is arranged, which drives a drive shaft 10. The drive shaft 10 acts via an eccentric mechanism on a movable displacement spiral 4, which performs an orbital movement during operation. The movable displacement spiral 4 engages with a fixed displacement spiral 5, and this engagement and the orbital movement result in a variable compression chamber between the spiral walls of the displacement spirals 4 and 5.

[0022] The eccentric mechanism between the drive shaft 10 and the movable displacement spiral 4 is designed as part of a compensation mechanism which will be explained in more detail below with reference to FIGS.

[0023] The compensation mechanism comprises a drive shaft 10 and a compensation device 20. The compensation device 20 essentially connects the drive shaft 10 with the movable displacement spiral 4. The compensation device 20 is made up of several parts, in particular a hub element 30 and a compensation element 40. The hub element 30 is arranged rotatably on the first eccentric pin 11 of the drive shaft 10. For this purpose, the hub element 30 is provided with a hub bore 31 into which the first eccentric pin 11 fits. Between the first eccentric pin 11 and the hub bore 31 a plain bearing or a needle bearing can be formed.

[0024] Hub element 30 includes a retaining portion 34 and a scroll portion 35, with retaining portion 34 facing drive shaft 10, while scroll portion 35 faces movable displacement spiral 4 and preferably carries scroll bearing 32. Scroll portion 35 and retaining portion 34 each have a cylindrical outer contour, with retaining portion 34 having a smaller cross-sectional diameter than scroll portion 35.

[0025] The retaining part 34 retains the compensating element 40. In particular, the compensating element 40 has a retaining hole 41 through which the scroll part 35 passes. The scroll part 35 extends beyond the retaining hole 41 towards the drive shaft 10 and is provided in its projecting part with an annular groove for receiving the fixing ring 33. In this way, the compensating element 40 is fixed to the hub element 30 in the longitudinal direction.

[0026] In general, the compensating element 40 is rotatably supported on the hub element 30. To this end, the retaining part 34 can form a plain bearing for the retaining bore 41 of the compensating element 40. By rotatably arranging the compensating element 40 on the hub element 30, it is achieved that in the compensating device 20, the eccentric connection between the first eccentric pin 11 and the movable displacement spiral 4 is decoupled from the balance weight 44. This results in a particularly good seal between the displacement spirals 4 and 5. This ensures a good seal of the variable compression chamber. At the same time, a very smooth operation is achieved by decoupling the balance weight 44.

[0027] The compensation element 40 comprises a guide part 43 carrying the retaining hole 41. Furthermore, a balance weight 44 is provided which extends substantially in the shape of a half ring or in the shape of a circular arc around the guide part 43. In particular, the balance weight 44 can extend in the shape of a circular arc around the retaining hole 41. The balance weight 44 preferably has a greater depth than the guide part 43.

[0028] Furthermore, a slot 42 is arranged in the guide part 43, which extends through the guide part 43 and whose longer transverse axis is substantially radially aligned with respect to the rotation axis J of the compensation element. The slot 42 receives the second eccentric pin 12 of the drive shaft 10, and the width of the slot 42 along its shorter transverse axis is substantially equal to the diameter of the second eccentric pin 12. The length of the slot 42 measured along its longer transverse axis is correspondingly greater than the diameter of the second eccentric pin 12.

[0029] 4, the first eccentric pin 11 fits into the hub bore 31 and the second eccentric pin 12 fits into the slot 42. The first eccentric pin 11 extends beyond the compensating element 40 but terminates within the hub bore 31. The second eccentric pin 12 terminates within the slot 42 and therefore does not extend beyond it.

[0030] 5 shows, in a front view of the compensation device 20, the location of the different axes which are crucial for the movement of the compensation mechanism. The drive shaft 10 has a central axis S which substantially forms the axis of rotation of the drive shaft 10.

[0031] The hub element 30 has a central axis C that extends through the center of the hub element 30. The hub hole 31 of the hub element 30 is formed eccentrically within the hub element 30. The central axis of the hub hole 31 forms a rotational axis P of the hub element 30. Thus, the hub element 30 rotates about the rotational axis P that is defined by the central axis of the hub hole 31 or the central axis of the first eccentric pin 11.

[0032] The compensating element 40 rotates about a rotation axis J defined by the central axis of the retaining hole 41. In the present embodiment, the rotation axis J of the compensating element 40 coincides with the central axis C of the hub element 30. However, it is also possible that the retaining hole 41 is eccentrically aligned with respect to the central axis C of the hub element, so that the rotation axis J of the compensating element 40 is located outside the central axis C of the hub element 30. For example, the retaining portion 34 of the hub element 30 can be formed eccentrically.

[0033] The slot 42 has a central axis Q that extends in the direction of boring of the slot 42, i.e., parallel to the central axis S of the drive shaft 10. The location of the central axis Q of the slot 42 is defined by the intersection of the transverse axes of the slot 42.

[0034] The compensation element 40 further has a centre of gravity 45 located within the guide part 43. The centre of gravity 45 is preferably located radially outside the slot 42 or the central axis Q of the slot 42, where "radially outside" should be understood with reference to the axis of rotation J of the compensation element 40.

[0035] In operation, a Scotch yoke mechanism is formed between the rotation axis P of the hub element 30, the rotation axis J of the compensation element 40 and the central axis Q of the slot 42, so that, during operation of the compensation device 20, the center of gravity 45 executes a movement having, on the one hand, a linear component extending radially along the connecting line JQ between the rotation axis of the compensation element 40 and the central axis Q of the slot 42, and, on the other hand, a pendulum component aligned substantially circumferentially about the rotation axis J of the compensation element 40. The linear component of this movement of the center of gravity 45 is greater than the circumferential or pendulum component. This type of movement, especially the linear component, leads to a significant reduction of vibrations and a reduction in noise inside the positive displacement machine.

Claims

1. A compensation mechanism for a positive displacement machine, in particular a scroll compressor, according to the spiral principle, said compensation mechanism comprises a drive shaft (10) having a central axis S and a compensation device (20), the compensation device (20) being: a cylindrical hub element (30) rotatably supported on a first eccentric pin (11) of the drive shaft (10) about a rotation axis P; a compensation element (40) supported on said hub element (30) for rotation about a rotation axis J and having an eccentrically disposed slot (42) extending radially with respect to the rotation axis J, A compensation mechanism, wherein the second eccentric pin (12) of the drive shaft (10) is guided in the slot (42) of the compensation element (40) such that a Scotch yoke mechanism is formed between the slot (42) and the rotation axis J of the compensation element (40).

2. 2. The compensation mechanism according to claim 1, characterized in that the center of gravity (45) of the compensation element (40) has a pendulum component in operation, and the center of gravity (45) reciprocates about a connection line JQ between the rotation axis J of the compensation element (40) and a central axis Q of the slot (42).

3. 3. The compensation mechanism according to claim 2, characterized in that the center of gravity (45) of the compensation element (40) has a linear component in operation, the center of gravity (45) moving along a connecting line JQ, the linear component being greater than the pendulum component.

4. 4. A compensation mechanism according to claim 1, wherein the rotation axis J of the compensation element (40) is arranged concentrically with the central axis C of the hub element (30).

5. 5. A compensation mechanism according to claim 1, wherein the axis of rotation J of the compensation element (40) is arranged eccentrically with respect to the central axis C of the hub element (30).

6. The compensation mechanism according to any one of claims 1 to 5, characterized in that the hub element (30) has an eccentric hub hole (31) in which the first eccentric pin (11) of the drive shaft (10) is arranged.

7. The compensation mechanism according to any one of claims 1 to 6, characterized in that the compensation element (40) has a retaining hole (41) in which the compensation element (40) is rotatably supported on the hub element (30).

8. 8. The compensation mechanism according to claim 1, wherein the compensation element (40) has a guide portion (43) and a balance weight (44), the balance weight (44) extending in an arc around the guide portion (43).

9. A compensation mechanism according to claim 8, characterized in that said retaining hole (41) and said slot (42) are arranged in said guide part (43).

10. 10. A compensation mechanism according to claim 8 or 9, characterized in that the balance weight (44) extends in the shape of a half ring about the axis of rotation J of the compensation element (40).

11. 11. A compensation mechanism according to claim 8, wherein the guide part (43) and the balance weight (44) are formed integrally, in particular monolithically.

12. The compensation mechanism according to any one of claims 1 to 11, characterized in that the first eccentric pin (11) of the drive shaft (10) has a larger diameter and / or a larger length than the second eccentric pin (12) of the drive shaft (10).

13. A compensation mechanism according to any one of claims 1 to 12, characterized in that the hub element (30) projects from the compensation element (40), in particular a balance weight (44), along the central axis C.

14. 14. The compensation mechanism according to claim 1, characterized in that the hub element (30) is rotatably supported on the first eccentric pin (11) of the drive shaft (10) via a plain bearing or a needle bearing, and / or the compensation element (40) is rotatably supported on the hub element (30) via a plain bearing or a needle bearing.

15. 15. A positive displacement machine according to the spiral principle, in particular a scroll compressor, comprising a compensation mechanism according to any one of claims 1 to 14.

16. 16. A positive displacement machine according to claim 15, characterized in that the hub element (30) carries a scroll bearing connected to a moving displacement spiral, in particular a displacement spiral that revolves during operation, said moving displacement spiral engaging a fixed displacement spiral.

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