Positive-displacement machine according to the spiral principle

Abstract

The invention relates to a positive-displacement machine according to the spiral principle, in particular a scroll compressor, said displacement machine comprising a housing (100) which has a compressor housing (20) and a drive housing (10), an orbiting displacement spiral (21) and a counter spiral (25) being located in the compressor housing (20) and engaging into one another in such a way that variable compression chambers (23) are formed between the displacement spiral (21) and the counter spiral (25) in order to receive and compress a working medium flowing through a working medium circuit, a drive shaft (12) being located in the drive housing (10) and being drivingly connected to the displacement spiral (21), a bearing plate (30) being located between the drive housing (10) and the compressor housing (20) and carrying a bearing (32) for the drive shaft (12), and an anti-rotation mechanism being provided between the bearing plate (30) and the orbiting displacement spiral (21). The bearing plate (30) is located completely inside the housing (100), the bearing plate (30) and the bearing (32) being made of materials having coefficients of thermal expansion which differ from one another by at most 20%, in particular by at most 10%, in particular by at most 5%.

Description

[0001] Displacement machine based on the spiral principle

[0002] Description

[0003] The invention relates to a displacement machine according to the spiral principle with the features of the preamble of patent claim 1. Such a displacement machine is known, for example, from DE 10 2016 118 525 B4.

[0004] The aforementioned DE 10 2016 118 525 B4 describes a positive displacement machine based on the scroll principle, in particular a scroll compressor, with a housing made of aluminum for corrosion protection. The housing forms a wall that separates a drive chamber of the scroll compressor from a compression chamber. The wall supports a drive bearing that supports a drive shaft. The drive shaft engages eccentrically with an orbiting displacement spiral, which in turn is in spiral engagement with a counter-spiral. The orbiting movement of the displacement spiral, initiated by the eccentric connection with the drive shaft, creates variable compression chambers between the displacement spiral and the counter-spiral, through which a working fluid can be compressed.

[0005] The known scroll compressor also features an anti-rotation mechanism. The anti-rotation mechanism comprises a pin that engages an opening in the bottom of the displacer scroll, thus preventing the displacer scroll from rotating. This forces the displacer scroll into the desired orbiting motion.

[0006] DE 10 2016 118 525 B4 has recognized that it is advantageous if the pins of the anti-rotation mechanism are not inserted directly into the aluminum wall, but rather a steel sliding plate is formed between the aluminum wall and the displacement spiral. The pins of the anti-rotation mechanism are inserted into this sliding plate and engage in openings in the displacement spiral. For reasons of durability, the pins are also made of steel.

[0007] The wall supporting the sliding plate also serves as a bearing plate that supports the drive shaft bearing. To ensure durability, drive shaft bearings are typically made of steel.

[0008] Due to the different materials between the bearing plate and the bearing, thermal expansion varies during operation of the positive displacement machine. This must be taken into account when pressing the bearing into the bearing plate and can lead to very small bearing clearance during partial load operation of the positive displacement machine or to the bearing becoming preloaded during operation. Both of these negatively impact the bearing's service life.

[0009] The object of the invention is to provide a displacement machine based on the spiral principle which has an improved service life.

[0010] In particular, the drive shaft bearing is intended to have an increased service life thanks to the invention.

[0011] This object is achieved according to the invention by the subject matter of patent claim 1.

[0012] Specifically, the invention is based on the idea of ​​providing a positive displacement machine based on the spiral principle, in particular a scroll compressor, with a housing comprising a compressor housing and a drive housing. An orbiting displacement spiral and a counter spiral are arranged in the compressor housing, which interlock such that variable compression chambers are formed between the displacement spiral and the counter spiral to accommodate and compress a working fluid flowing through a working fluid circuit. A drive shaft is arranged in the drive housing and is drivingly connected to the displacement spiral. A bearing plate, which supports a bearing for the drive shaft, is arranged between the drive housing and the compressor housing. An anti-rotation mechanism is provided between the bearing plate and the orbiting displacement spiral.According to the invention, the bearing plate is arranged completely within the housing, wherein the bearing plate and the bearing are formed from materials whose thermal expansion coefficient differs from each other by at most 20%, in particular at most 10%, in particular at most 5%.

[0013] The invention essentially utilizes two effects. Firstly, the material selection for the bearing plate and bearing ensures that the bearing does not become strained during operation, thus increasing the service life of the bearing. Secondly, the bearing plate is located entirely within the housing. This means that a different material can be selected for the bearing plate than for the housing. For example, the housing can be made of aluminum, offering appropriate corrosion protection. The bearing plate, on the other hand, can be made of steel, offering sufficient strength to hold the bearing. In this respect, the invention is also based on the idea of ​​a functional separation between the housing and the bearing plate.While in the prior art the housing and the bearing plate are often formed as one piece, the invention uses a two-part design so that each component can be optimally configured for its assigned function.

[0014] By making the bearing plate and the bearing from materials that have a similar coefficient of thermal expansion, the interference fit between the bearing plate and the bearing can be well dimensioned, which has a positive effect on the service life of the bearing.

[0015] The bearing plate can be connected to the housing by force. In particular, the bearing plate can be connected to the housing by a press fit, a screw connection, rivets, or a pin connection.

[0016] In one embodiment, it is particularly provided that the bearing plate is fastened in a housing ring which is arranged between the drive housing and the compressor housing. In this variant, ease of maintenance is a priority. The housing itself comprises the drive housing, the housing ring and the compressor housing. The housing ring is preferably non-positively connected to the bearing plate. The material of the housing ring preferably corresponds to the materials of the drive housing and the compressor housing. The bearing plate is preferably made of a different material, in particular steel. Specifically, in a preferred embodiment, it is provided that the housing ring comprises a different material than the bearing plate and / or the compressor housing. The material of the housing ring is preferably corrosion-resistant, in particular aluminum.

[0017] Alternatively, the bearing plate can be mounted in the drive housing. This eliminates the need for a separate housing ring. This reduces the number of components, which has a positive effect on manufacturing costs.

[0018] In a further preferred embodiment, it is provided that the bearing plate is fastened in the compressor housing.

[0019] Another alternative variant of the invention provides for the bearing plate to be firmly connected, in particular by force-locking, to the counter-spiral. The aforementioned force-locking connections can be used for all variants.

[0020] In a further preferred embodiment of the invention, the orbiting displacement spiral has a displacement spiral base in which a sealing element is mounted. The sealing element seals the orbiting displacement spiral to the bearing plate and thus to the drive housing. This increases the efficiency of the displacement machine.

[0021] A sliding plate can also be arranged between the bearing plate and the orbiting displacement spiral, in particular the displacement spiral base. The sliding plate is preferably arranged entirely within the housing. It is particularly preferred if the sealing element seals against the sliding plate.

[0022] The sliding plate is preferably made of a material with good sliding and sealing properties. This reduces friction within the positive displacement machine and increases its efficiency. At the same time, vibrations and noise emissions are reduced, which is important for electromobility applications.

[0023] The invention is explained in more detail below using an exemplary embodiment with reference to the accompanying drawing. The single figure shows a partial cross-sectional view of a displacement machine according to the invention according to a preferred exemplary embodiment.

[0024] Fig. 1 specifically shows a section of a positive displacement machine, in particular a scroll compressor, with a housing 100. The housing 100 is divided into a drive housing 10 and a compressor housing 20. In the embodiment shown here, a housing ring 31 is arranged between the drive housing 10 and the compressor housing 20. The housing ring 31 is firmly connected to the drive housing 10 and the compressor housing 20. Preferably, the drive housing 10, the compressor housing 20, and the housing ring 31 are formed from an aluminum alloy.

[0025] A drive shaft 12 is also arranged in the drive housing 10. Drive housing 10 may also include an electric motor (not shown here) that directly drives the drive shaft 12.

[0026] The drive shaft 12 passes through a bearing plate 30 and is mounted in a bearing 32 within the bearing plate 30. The bearing 32 is preferably fixed in the bearing plate 30 with a press fit. A shaft seal 11 is located in front of the bearing 32, which surrounds the drive shaft 12 and thus tightly seals the drive housing 10 against the bearing plate 30.

[0027] The drive shaft 12 engages an eccentric bearing 14 via a compensating mechanism 13. The eccentric bearing 14 engages with an orbiting displacement spiral 21, so that drive energy can be transmitted to the orbiting displacement spiral 21 via the drive shaft 12 and the eccentric bearing 14.

[0028] The positive displacement machine shown in the figure further includes an anti-rotation mechanism 40. The anti-rotation mechanism 40 comprises a pin 41 that is firmly attached to the bearing plate 30. The pin 41 engages with play in a ring 42 that is arranged in an opening of the displacement spiral 21. The play between the ring 42 and the pin 41 forces the displacement spiral 21 into an orbiting motion by the eccentric on the drive shaft 12. Simple rotation of the displacement spiral is thus prevented. To ensure a good seal between the orbiting displacement spiral 21 and the bearing plate 30, the bearing plate 30 further carries a sliding plate 33. The orbiting displacement spiral 21 further comprises a sealing element 24 that is pressed against the sliding plate 33, thus ensuring good sealing. The sealing element 24 can be a circumferential O-ring.

[0029] As can also be clearly seen in the figure, the bearing plate 30 is arranged entirely within the housing. The bearing plate 30 is firmly connected to the counter spiral 25. The connection can be made, in particular, by force-locking. For example, press-fitted fastening pins can hold the bearing plate 30 to the counter spiral 25. Alternatively, screwing, riveting, or a tolerance ring design are also possible.

[0030] The bearing plate 30 can be made of steel or a cast material. Preferably, a material is used that is also used for the manufacture of the shaft bearing 32. In any case, the bearing plate 30 and the shaft bearing 32 should be made of materials that have the same or at least similar thermal expansion coefficients. During operation of the positive displacement machine, the shaft bearing 32 and the bearing plate 30 expand evenly. The interference fit between the shaft bearing 32 and the bearing plate 30 can thus be dimensioned well and precisely, which has a positive effect on the service life of the shaft bearing 32.

[0031] Reference symbol

[0032] 10 drive housing

[0033] 11 Shaft seal

[0034] 12 Drive shaft

[0035] 13 Compensation mechanism

[0036] 14 eccentric bearings

[0037] 20 compressor housing

[0038] 21 orbiting displacement spiral

[0039] 22 Displacement spiral bottom

[0040] 23 Compression chamber

[0041] 24 Sealing element

[0042] 25 Counter spiral

[0043] 30 bearing plate

[0044] 31 Case ring

[0045] 32 warehouses

[0046] 33 Sliding plate

[0047] 40 Anti-rotation mechanism

[0048] 41 pen

[0049] 42 rings

[0050] 100 housings

Claims

Claims: A positive displacement machine based on the spiral principle, in particular a scroll compressor, with a housing (100) comprising a compressor housing (20) and a drive housing (10), wherein an orbiting displacer spiral (21) and a counter-spiral (25) are arranged in the compressor housing (20) in such a way that variable compression chambers (23) are formed between the displacer spiral (21) and the counter-spiral (25) to receive and compress a working fluid flowing through a working fluid circuit, wherein a drive shaft (12) is arranged in the drive housing (10) which is drive-connected to the displacer spiral (21), wherein a bearing plate (30) is arranged between the drive housing (10) and the compressor housing (20) which carries a bearing (32) for the drive shaft (12), and wherein between the bearing plate (30) and the orbiting displacer spiral (21) an antirotation mechanism (40) is provided, that is indicated by a sign,that the bearing plate (30) is arranged completely within the housing (100), wherein the bearing plate (30) and the bearing (31) are made of materials whose coefficient of thermal expansion differs from each other by at most 20%, in particular by at most 10%, in particular by at most 5%. A positive displacement machine according to claim 1 is characterized by the fact that the bearing plate (30) is force-fitted to the housing (100). A positive displacement machine according to claim 1 or 2 is characterized by the fact that the bearing plate (30) is fastened in a housing ring (31) which is arranged between the drive housing (10) and the compressor housing (20). A positive displacement machine according to claim 3 is characterized by the fact that the housing ring (31) is made of a different material than the bearing plate (30), in particular the same material as the drive housing (10) and / or, the compressor housing (20). Positive displacement machine according to claim 1 or 2 is characterized by the fact that the bearing plate (30) is fastened in the drive housing (10). Positive displacement machine according to claim 1 or 2 is characterized by the fact that the bearing plate (30) is fastened in the compressor housing (20). Positive displacement machine according to any of the preceding claims is characterized by the fact that the bearing plate (30) is firmly, in particular force-fit, connected to the counter-spiral (25). Positive displacement machine according to any of the preceding claims is characterized by the fact that the orbiting displacer spiral (21) has a displacer spiral base (22) in which a sealing element (24) is fastened. Displacement machine according to one of the preceding claims is characterized by the fact that a sliding plate (33) is arranged between the bearing plate (30) and the orbiting displacement spiral (21), in particular the displacement spiral base (22).A positive displacement machine according to claim 9 is characterized by the fact that the sliding plate (33) is arranged completely within the housing (100). A positive displacement machine according to claim 9 or 10 is characterized by the fact that the sealing element (24) seals against the sliding plate (40).

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