Volumetric machines based on the spiral principle

Abstract

The invention relates to a positive displacement machine based on the spiral principle, in particular a scroll compressor, with an electric motor (10), an orbital displacement spiral (21) and a counter spiral (22) which are in mutual engagement with each other 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, and the electric motor (10) is drivingly connected to the displacement spiral (21) by means of a motor shaft (12). The invention is characterized in that the motor shaft (12) is supported via a single bearing (31), which is arranged between the electric motor (10) and the displacement spiral (21).

Description

[Technical field]

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

[0002] Positive displacement machines, specifically scroll compressors, working on the spiral principle are known in practice. Positive displacement machines are usually used as compressors for air conditioning systems in vehicles. Typically, such scroll compressors are constructed in such a way that the compression structure with 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 displacement spiral and the counter spiral by the mutual engagement of the displacement 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 displacement 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] In particular, the problem is solved by a positive displacement machine based on the spiral principle, in particular a scroll compressor, with an electric motor, an orbital displacer spiral and a counter spiral, which are engaged with each other in such a way that a variable compression chamber is formed between the displacer spiral and the counter spiral for receiving and compressing the working medium flowing through the working medium circuit. The electric motor is drivingly connected to the displacer spiral by a motor shaft. According to the invention, the motor shaft is supported via only one bearing, which is arranged between the electric motor and the displacer spiral.

[0008] The invention is based on the idea of ​​reducing the number of connections between the moved and non-moved parts of a positive displacement machine. The motor shaft as the moved part requires a support. It has been found that only one bearing is sufficient to stably support the motor shaft. At the same time, by omitting further bearings, the contacts with other components, in particular with non-moving components, are reduced. This leads to an improvement with regard to the acoustic radiation of the positive displacement machine. In particular, the vibrations generated by the motor shaft are purposefully guided through only one bearing. This provides improved control possibilities for reducing the vibration transmission.

[0009] Advantageously, the motor shaft is free-supporting, in particular unsupported, on the side of the electric motor opposite the bearing. In particular, the motor shaft is preferably spaced apart from the housing of the displacement machine, so that a direct transmission of vibrations to the housing via the motor shaft is avoided. At most, the connection between the motor shaft and the housing is only indirect, via a single bearing. However, this connection may be vibrationally weakly coupled by means of damping elements and / or weak-coupling elements.

[0010] In order to be able to absorb axial forces acting on the motor shaft well, in an advantageous embodiment of the invention the bearing is configured as a double-row angular contact ball bearing or as a pair of single-row angular contact ball bearings abutting against one another. The double-row angular contact ball bearings and / or the single-row angular contact ball bearing pairs can each have an O-shaped arrangement. The O-shaped arrangement allows axial forces to be absorbed in both axial directions.

[0011] It is advantageous if the bearing is fixed in a bearing plate, which is located between the electric motor and the displacement spiral. The bearing plate thereby forms a central component that carries or supports both the drive part of the positive displacement machine and the compression part of the positive displacement machine. Such a central connection not only offers manufacturing advantages, but also the possibility of reducing or even eliminating the vibrations occurring during mechanical operation centrally by targeted diverting or collecting these vibrations. In any case, this ensures that the acoustic radiation of the positive displacement machine can be reduced overall by centrally damping the vibrations occurring in all mechanical units of the positive displacement machine.

[0012] In this connection, it is particularly advantageous if the bearing plate forms an internal housing, in which the electric motor is arranged. The electric motor, the bearing plate, the displacement spiral and the counter spiral can form a compression structure, in particular mechanically independent, which is arranged in the housing. The compression structure can be vibrationally decoupled from the housing. In particular, the bearing plate forming the internal housing can be vibrationally decoupled from the housing by decoupling elements. It is particularly advantageous if the compression structure is fixed in the housing exclusively via decoupling elements. Vibrations occurring during operation of the compression structure are thus not emitted at all or only in a strongly damped manner into the housing, whereby noise generation is significantly reduced outwards.

[0013] In a further advantageous embodiment of the displacement machine according to the invention, the housing has a housing bottom, which can be connected to the inverter housing. Alternatively, the housing bottom can form part of the inverter housing. The housing bottom can be spaced apart from the electric motor, in particular from the free end of the electric motor arranged opposite the bearing. In the case of conventional displacement machines in which a second bearing is arranged in the housing bottom, the inverter housing arranged next to the housing bottom forms a resonance space, which leads to an increase in acoustic radiation. By omitting such an additional bearing according to the invention and by providing a distance between the electric motor and the housing bottom, the inverter housing is weakly vibrationally coupled from the mechanically operated parts of the displacement machine. This leads to a further reduction in acoustic radiation.

[0014] In addition to the reduction in acoustic radiation, the invention has further advantages. On the one hand, the number of components is reduced by eliminating further bearings. This is favorably reflected in the production costs. The displacement machine according to the invention thus has a particularly simple construction. Furthermore, the displacement machine according to the invention is particularly compact, since the motor shaft can be made short by eliminating further bearings. Overall, this results in a reduced construction length of the displacement machine. The installation possibilities of the displacement machine in a vehicle are thereby improved.

[0015] The invention will now be described in more detail on the basis of one embodiment with reference to the accompanying schematic drawing. [Brief description of the drawings]

[0016] [Figure 1] The only figure shows a longitudinal section of a positive displacement machine according to the invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0017] 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.

[0018] 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 such that it cannot rotate relative to the motor shaft. 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.

[0019] 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 this 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.

[0020] 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 onto 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 motor shaft 12 being weakly coupled from the housing bottom 101 and thus from the inverter housing.

[0021] 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.

[0022] In order to achieve a good sealing of the compression chamber formed between the displacement spiral 21 and the counter spiral 22, the latter has a sealing groove 23. The sealing groove 23 advantageously 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.

[0023] 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 ensure that the compression chamber between the displacement spiral 21 and the counterspiral 22 is sealed.

[0024] As can be seen, 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 annularly around the longitudinal axis of the motor shaft 12. A total of four grooves are provided. Three grooves open radially outward, whereas one groove 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.

[0025] 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.

[0026] 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.

[0027] 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.

[0028] 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]

[0029] 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 an electric motor (10), an orbital displacement spiral (21) and a counter spiral (22), the latter engaging with each other in such a way that a variable compression chamber is formed between the former and the counter spiral (22) for receiving and compressing a working medium flowing through a working medium circuit, the electric motor (10) being drivingly connected to the latter by a motor shaft (12), A positive displacement machine, characterized in that the motor shaft (12) is supported via a single bearing (31), the bearing being disposed between the electric motor (10) and the displacement spiral (21).

2. 2. A positive displacement machine according to claim 1, characterized in that the motor shaft (12) is self-supporting and not specifically supported on the side of the electric motor (10) opposite the bearing (31).

3. 3. A displacement machine according to claim 1 or 2, 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.

4. 4. A displacement machine according to claim 1, wherein the bearing (31) is fixed in a bearing plate (30), the bearing plate being located between the electric motor (10) and the displacement spiral (21).

5. 5. A positive displacement machine according to claim 4, characterized in that said bearing plate (30) forms an inner housing (32) in which said electric motor (10) is arranged.

6. 6. A displacement machine according to claim 4 or 5, wherein the electric motor (10), the bearing plate (30), the displacement spiral (21) and the counter spiral (22) form in particular a mechanically independent compression structure (150), the compression structure being arranged in a housing (100).

7. 7. A positive displacement machine according to claim 6, characterized in that the compression structure (150) is vibrationally weakly coupled from the housing (100).

8. 8. The displacement machine according to claim 6 or 7, characterized in that the housing (100) has a housing bottom (101), which can be coupled to an inverter housing or which forms part of the inverter housing, and the housing bottom (101) is isolated from the electric motor (10), in particular from a free end of the electric motor (10) arranged opposite the bearing (31).

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