Volumetric machines based on the spiral principle

Abstract

A positive displacement machine based on the spiral principle, in particular a scroll compressor, comprising a housing (100) and a compression structure (150) having an electric motor (10), a track-displacing spiral (21), a counter spiral (22) and a bearing plate (30), the displacing spiral (21) and the counter spiral (22) engaging with each other in and outwardly such that a variable compression chamber is formed between the displacing spiral (21) and the counter spiral (22) for receiving and compressing the working medium flowing through the working medium circuit, and the electric motor (10) is drivingly connected to the displacing spiral (21) by means of a motor shaft (12). The compression structure (150) is weakly vibrationally connected to the housing (100).

Description

[Technical field]

[0001] The present invention relates to a positive displacement machine based on the spiral principle, in particular a scroll compressor, as defined in the preamble of claim 1. [Background technology]

[0002] Positive displacement machines, specifically scroll compressors, operating on the spiral principle are known in practice. Positive displacement machines are usually used as compressors for air conditioning systems in vehicles. Generally, such scroll compressors are constructed in such a way that the compression structure, which comprises the electric motor, the orbital displacement spiral, the counter spiral and the bearing plate, is arranged in a housing. The housing is intended to protect the internal structural parts of the scroll compressor from corrosion.

[0003] The principle of operation of the scroll compressor is that a variable compression chamber is formed between the displacer spiral and the counter spiral, by the mutual engagement of the displacer spiral and the counter spiral, into which the working medium flows and is compressed by the variable compression chamber. The orbital displacement spiral is driven by a motor shaft via an electric motor, which is drivingly connected to the displacer spiral. Summary of the Invention [Problem to be solved by the invention]

[0004] Scroll compressors are generally very efficient and basically run smoothly. However, with the increasing electrification of vehicles, the requirements for smooth operation are significantly increased. In the case of electrically driven vehicles, small vibrations of individual components already result in noticeable noise emissions. In conventional vehicles with a combustion engine, such noise emissions are eliminated by the vibrations of the combustion engine itself. In the case of electrically driven vehicles, however, the vibrations emitted by the vehicle drive can be significantly reduced by reducing the number of parts in motion. As a result, the vibrations of other components in the vehicle become more noticeable. Therefore, great efforts are being made to improve other moving components in the vehicle in terms of vibration and sound radiation. This is particularly relevant for air conditioning compressors in vehicles.

[0005] It is therefore an object of the present invention to provide a positive displacement machine based on the scroll principle, in particular a scroll compressor, which is improved in terms of vibration and acoustic radiation. [Means for solving the problem]

[0006] According to the invention, this problem is solved by the subject matter of claim 1.

[0007] The invention is thus based on the idea of ​​providing a positive displacement machine based on the scroll principle, in particular a scroll compressor, with a housing and a compression structure, the compression structure having an electric motor, an orbital displacer spiral, a counter spiral and a bearing plate. The displacer spiral and the counter spiral engage with each other externally and internally in such a way that a variable compression chamber is formed between them for receiving and compressing the working medium flowing in the working medium circuit. The electric motor is drivingly connected to the displacer spiral by means of a motor shaft. According to the invention, the compression structure is weakly vibrationally coupled from the housing.

[0008] The invention is based on the idea that by grouping all the moving elements of the positive displacement machine in one compression structure and weakly coupling such compression structure to the housing of the positive displacement machine, vibrations generated by the operated parts of the compression structure are not directly introduced into the housing and are not directly transmitted from the housing into further components of the vehicle.

[0009] In this way, the smooth operation of the positive displacement machine is significantly improved. An additional advantageous effect of such an arrangement is that the weak coupling of the compression structure from the housing facilitates maintenance of the compression structure. In particular, the entire compression structure can be replaced relatively easily.

[0010] Advantageously, a non-metallic weak-coupling element is arranged between the compression structure and the housing. The weak-coupling element may in particular be designed as an O-ring. Advantageously, the O-ring is made of plastic and / or rubber. The weak-coupling element provides a vibration-weakened coupling between the compression structure and the housing in a particularly easy and inexpensive manner.

[0011] In general, the compression structure can function mechanically independently. The compression structure thus contains all moving parts of the displacement machine. This ensures that the mechanical structural elements which generate vibrations are well vibrationally coupled out of the housing. Vibrations generated in the compression structure thus cannot be transmitted directly to the housing. This improves smooth operation. In particular, the transmission of vibrations outwards, for example to other components of the vehicle, is avoided.

[0012] In a preferred embodiment of the displacement machine according to the invention, the bearing plate forms an inner housing in which the electric motor is arranged. The bearing plate is therefore not only formed as a flat plate but also has a housing form. The bearing plate preferably forms the inner housing. The inner housing is arranged inside the housing as part of the compression structure and is vibrationally weakly coupled from this housing. The inner housing brings together the parts of the compression structure that are to be operated, which form a structural unit that can be handled as a unit.

[0013] The bearing plate may be made of one piece or of several pieces. The one-piece construction of the bearing plate is advantageous during assembly, in particular because fewer individual parts have to be produced, which can reduce manufacturing costs. Making the bearing plate of several pieces allows for greater flexibility during maintenance or repair of the displacement machine.

[0014] The bearing plate, in particular the inner housing, can support the bearing of the motor shaft, which is thus supported in the bearing plate, so that the motor shaft is part of the compression structure and thus vibrationally weakly coupled from the housing.

[0015] The bearing plate immovably connects the electric motor, in particular the stator, the bearing and the counter spiral of the electric motor, to one another, and in this respect forms a central component of the compression structure, in particular the bearing plate can form a connection between the moving parts of the compression structure.

[0016] In an advantageous variant embodiment of the invention, the bearings are designed in such a way that the motor shaft is supported exclusively via a single bearing. In conventional scroll compressors, the motor shaft is in most cases supported on the one hand on the bearing plate via a first bearing and on the other hand on the bottom of the housing via a second bearing. However, in order to avoid metal contact between the compression structure and the housing, it is advantageous to dispense with the second bearing. There is thus no direct vibration-transmitting connection between the motor shaft and the housing. The transmission of structure-borne noise is thus further avoided.

[0017] In order to be able to absorb the forces occurring in the motor shaft even when supported on one side, it is advantageous if the bearing is designed as a double-row angular contact ball bearing or as a pair of abutting single-row angular contact ball bearings. The double-row angular contact ball bearing or the pair of abutting single-row angular contact ball bearings can each have a U-shaped arrangement. In this way, the axial forces acting on the motor shaft are also absorbed well by the bearing.

[0018] Furthermore, the compression structure, in particular the bearing plate, may have a different material than the housing. In particular, the bearing plate may be formed from a different material than the housing. This allows a functional separation to be achieved and even improved. The function of the housing is to protect the compression structure from external influences. For this purpose, the housing is preferably formed from a corrosion-resistant material, preferably from aluminum. The compression structure, in particular the bearing plate, forms the mechanical components required for the operation of the displacement machine to perform its basic functions. In this case, forces that have to be absorbed via the components of the compression structure are released. In particular, the bearing plate has to absorb large forces. In this connection, it is advantageous if the bearing plate is formed from a strong material, for example steel. It is particularly advantageous if the bearing plate and the bearing have materials with similar, in particular identical, coefficients of thermal expansion. This helps to avoid distortion of the bearing in the bearing plate and additionally to avoid vibrations.

[0019] The invention will now be described on the basis of an embodiment with reference to the accompanying drawings, in which: [Brief description of the drawings]

[0020] [Figure 1] The only figure shows a longitudinal section of a positive displacement machine according to the invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0021] The single figure shows a positive displacement machine based on the spiral principle, in particular a scroll compressor. The scroll compressor comprises a housing 100 which surrounds a compression structure 150. The housing 100 is formed in the embodiment shown here by a main housing 110 and a housing cover 120. The main housing 110 is formed substantially pot-shaped and is closed at its axial end by the housing cover 120.

[0022] The compression structure 150 comprises an electric motor 10. The electric motor 10 has a stator 13 and a rotor 11. The rotor 11 is connected to a motor shaft 12 so that it cannot rotate relative to the motor shaft 12. The motor shaft is supported in a bearing 31. The bearing 31 is preferably configured as a double-row angular contact ball bearing and forms the only support for the motor shaft 12. Alternatively, the bearing 31 can be formed by a pair of abutting single-row angular contact ball bearings. The bearing 31 preferably has an O-shaped arrangement in each case, so that the bearing 31 can absorb axial forces in both directions.

[0023] The bearing 31 is advantageously a single bearing 31. In particular, the motor shaft 12 is supported only by the single bearing 31. In particular, on the opposite side of the single bearing 31, the motor shaft 12 has no bearing or is not supported. The motor shaft 12 is in this respect supported in a cantilevered manner by the single bearing 31. In this connection, this is referred to as a floating support of the motor shaft 12.

[0024] The motor shaft 12 further has a certain distance from the housing bottom 101 of the housing 100. In particular, there is no direct contact between the motor shaft 12 and the housing bottom 101. This prevents vibrations from the rotational movement of the motor shaft 12 from being transmitted into the housing 100. An inverter housing may further be arranged on the housing bottom 101. The housing bottom 101 may also form a wall of the inverter housing. In both cases, the interior space of the inverter housing forms a resonant space or resonator that can increase acoustic radiation. Such acoustic radiation is reduced due to the weak coupling of the motor shaft 12 from the housing bottom 101 and thus from the inverter housing.

[0025] The bearing 31 is pressed into the bearing plate 30. The bearing plate 30 separates the drive space of the compression structure 150 from the compression space. In the drive space, the electric motor 10 is arranged. The compression space contains a displacement spiral 21. The displacement spiral 21 rests on the bearing plate 30 or on a slide plate (not shown) arranged on the bearing plate 30. The displacement spiral 21 engages into a counter spiral 22. The counter spiral 22 is also arranged in the compression space. The counter spiral 22 is fixedly connected to the bearing plate 30, in particular by a screw fastening.

[0026] In order to achieve a good seal between the displacement spiral 21 and the bearing plate 30, the displacement spiral has a sealing groove 23. The sealing groove 23 preferably runs annularly through the bottom of the displacement spiral 21 about the longitudinal axis of the motor shaft 12. A sealing element is received in the sealing groove 23. The sealing element is not shown for reasons of clarity.

[0027] An anti-rotation mechanism 40 is provided radially inside the sealing groove 23. The anti-rotation mechanism 40 comprises a number of distributed pins 41, which are immovably arranged in the bearing plate 30. The pins 41 protrude beyond the bearing plate 30 and engage in holes 42, which are formed in the displacement spiral 21. The holes 42 are clearly larger than the diameter of the pins, in particular several times larger. The anti-rotation mechanism 40, also called a pin / ring mechanism, prevents the displacement spiral 21 from rotating about its central axis. Instead, the displacement spiral is forced into an orbital movement. In this case, the displacement spiral 21 is driven by the motor shaft 12, which is in contact with the displacement spiral 21 via the compensation mechanism 14 and the eccentric bearing 15. The compensation mechanism 14 essentially comprises a counterweight, which serves to compensate for the dynamic imbalance of the displacement spiral 21 and to seal the compression chamber between the displacement spiral 21 and the counterspiral 22.

[0028] As can be seen from the drawing, the bearing plate 30 forms an inner housing 32 in which the electric motor 10 is arranged. In particular, the bearing plate 30 is cylindrically continuous and receives the stator 13 of the electric motor 10. The stator 13 is preferably fixedly connected to the inner housing 32. The inner housing 32 has a number of grooves 33 which preferably run in an annular manner around the longitudinal axis of the motor shaft 12. A total of four grooves 33 are provided. Three grooves 33 open radially outward, whereas one groove 33 opens towards the axial end of the inner housing 32. In all grooves 33, weak coupling elements 34 are arranged. These weak coupling elements are in contact with the housing 100. The weak coupling elements 34 are preferably formed as O-rings from plastic and / or rubber.

[0029] The inner housing 32 has play relative to the housing 100. Specifically, a gap exists between the inner housing 32 and the housing 100. The weak coupling element 34 bridges such gap and holds the inner housing 32 at a predetermined distance from the housing 100. As a result, there is no metallic contact between the inner housing 32 and the housing 100. As a result, an acoustic weak coupling is achieved.

[0030] The opposing spiral 22 also has grooves 33. Each of these grooves receives one weak-coupling element 34. The opposing spiral 22 together with the inner housing 32 and the components arranged therein form a compression structure 150. The compression structure is supported from the housing 100 in a completely acoustically weakly coupled manner. The support is provided via the weak-coupling elements 34 arranged in the grooves 33.

[0031] As can also be seen, one of the grooves 33 in the counter spiral 22 opens towards the free axial end of the housing cover 120. The axially open groove 33 of the inner housing 32 opens in the opposite direction, i.e. towards the free end of the main housing 110. In this way it is ensured that the compression structure 150 is not only radially but also axially on both sides weakly coupled from the housing 100. The second groove 33 opens in the counter spiral 22 radially outwards, i.e. towards the inner surface of the housing cover 120.

[0032] It can further be seen that the compression structure 150 is mechanically independent in itself: all mechanical processes of the scroll compressor take place, i.e., within the compression structure 150. The task of the housing 100 is only to form the corresponding fluid chambers for guiding the working medium to be compressed and to protect the compression structure 150 from external environmental influences. [Explanation of symbols]

[0033] 10 Electric motor 11 Rotor 12 Motor shaft 13 Stator 14 Compensation mechanism 15 Eccentric bearing 21 Displacement Spiral 22 Opposing Spiral 23 Seal groove 30 Bearing plate 31 Bearings 32 Inner housing 33 Groove 34 Weakly Linked Elements 40 Anti-rotation mechanism 41 pin 42 holes 100 Housing 101 Housing bottom 110 Main Housing 120 Housing cover 150 Compressed Structure

Claims

1. A positive displacement machine based on the spiral principle, in particular a scroll compressor, comprising a housing (100) and a compression structure (150) having an electric motor (10), a track-displacing spiral (21), a counter spiral (22) and a bearing plate (30), the displacing spiral (21) and the counter spiral (22) engaging with each other in such a way that a variable compression chamber is formed between them for receiving and compressing a working medium flowing through a working medium circuit, the electric motor (10) being drivingly connected to the displacing spiral (21) by means of a motor shaft (12), A positive displacement machine, characterized in that the compression structure (150) is vibrationally weakly coupled from the housing (100).

2. 2. The positive displacement machine according to claim 1, characterized in that a non-metallic weak coupling element (34), preferably made of plastic and / or rubber, in particular an O-ring, is arranged between the compression structure (150) and the housing (100).

3. 3. A displacement machine according to claim 1 or 2, characterized in that the bearing plate (30) forms an inner housing (32) in which the electric motor (10) is arranged.

4. 4. A displacement machine according to claim 1, wherein the bearing plate (30) is made in one part or in several parts.

5. 5. A displacement machine according to any one of claims 1 to 4, characterized in that the bearing plate (30), in particular the inner housing (32), supports a bearing (31) of the motor shaft (12).

6. 6. The positive displacement machine according to claim 5, characterized in that the bearing plate (30) immovably connects the electric motor (10), in particular the stator (13) of the electric motor, the bearing (31) and the opposing spiral (22) to one another.

7. 7. The displacement machine according to claim 1, wherein the bearing (31) is configured such that the motor shaft (12) is supported exclusively via the single bearing (31).

8. 8. The displacement machine according to claim 7, characterized in that the bearings (31) are formed as double row angular contact ball bearings or as a pair of single row angular contact ball bearings abutting each other in an O-shaped arrangement.

9. 9. A positive displacement machine according to any one of claims 1 to 8, characterized in that the compression structure (150), in particular the bearing plate (30), has or is made of a different material than the housing (100).

10. 10. A positive displacement machine according to any one of the preceding claims, characterized in that the housing (100) comprises or is made of a corrosion-resistant material, in particular aluminium.

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