DISPLACEMENT MACHINE ACCORDING TO THE SPIRAL PRINCIPLE

Abstract

The invention relates to a displacement machine according to the spiral principle, in particular a scroll compressor, said machine comprising: an electric motor; an orbiting displacement spiral; and a counter spiral, the displacement spiral and the counter spiral engaging into one another in such a way that variable compression chambers are formed between the displacement spiral and the counter spiral in order to receive and compress a working medium flowing through a working medium circuit, and the electric motor being drivingly connected to the displacement spiral by means of a motor shaft. The invention is characterized in that the motor shaft is supported via a single shaft bearing which is located between the electric motor and the displacement spiral.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a National Stage Application of International Application No. PCT/EP2023/061482, filed on May 2, 2023, which claims benefit of priority to German Patent Application No. 102022111379.5, filed on May 6, 2022 which applications are incorporated herein by reference in their entirety. To the extent appropriate, a claim of priority is made to each of the above disclosed applications.

TECHNICAL FIELD

The invention relates to a displacement machine according to the spiral principle, in particular, a scroll compressor.

Displacement machines that work according to the spiral principle, in particular, scroll compressors, are known from practice. They are commonly used as compressors for air conditioning systems in vehicles. In general, such scroll compressors are designed in such a way that a compression assembly comprising an electric motor, an orbiting displacement spiral, a counter spiral and a bearing plate is located in a housing. The housing is intended to protect the inner components of the scroll compressor from corrosion.

The operating principle of the scroll compressor is that the displacement spiral and the counter spiral engage into one another so that variable compression chambers are formed between the displacement spiral and the counter spiral. A working medium flows into these compression chambers and is compacted by the variable compression chambers. The orbiting displacement spiral is driven by the electric motor by means of a motor shaft that is connected to the displacement spiral.

Scroll compressors are generally very efficient and generally smooth running. However, with the increasing electrification of vehicles, the requirements for smooth running are increasing considerably. In electrically powered vehicles, even small vibrations in individual components lead to noticeable noise development. Such noise development has disappeared in conventional vehicles with combustion engines due to the vibrations of the combustion engine itself. In the case of electrically powered vehicles, however, the vibrations emitted from the vehicle drive are significantly reduced by reducing moving parts. As a result, emphasis is given to vibrations from other components in the vehicle. For this reason, there is a high level of effort to improve other moving components in a vehicle with regard to vibrations and noise emissions. This also applies, in particular, to air conditioning compressors in vehicles.

The object of the invention is thus to provide a displacement machine according to the spiral principle, in particular a scroll compressor, which is improved in terms of vibration and noise emissions.

In particular, the problem is solved by means of a displacement machine according to the spiral principle, in particular, a scroll compressor, with an electric motor, an orbiting displacement spiral and a counter spiral, the displacement spiral and the counter spiral engaging into one another in such a way that variable compression chambers are formed between the displacement spiral and the counter spiral in order to receive and compress a working medium flowing through a working medium circuit. The electric motor is connected to the displacement spiral by means of a motor shaft. According to the invention, the motor shaft is supported by a single shaft bearing, which is located between the electric motor and the displacement spiral.

The invention is based on the idea of reducing the number of connections between moving parts of the displacement machine and stationary parts. The motor shaft as a moving part requires a bearing, wherein it has been shown that a single shaft bearing is sufficient to support the motor shaft stably. Simultaneously, contact with other components, particularly immovable components, are reduced by dispensing with additional shaft bearings. This leads to an improvement in terms of noise emissions from the displacement machine. Specifically, the vibrations generated by the motor shaft are dissipated in a targeted manner via a single shaft bearing. This offers improved control options for reducing vibration transmission.

Preferably, the motor shaft on one side of the electric motor opposite the shaft bearing is self-supporting, particularly unsupported. In particular, the motor shaft preferably comprises a distance to a housing of the displacement machine so that a transmission of vibrations via the motor shaft directly to the housing is avoided. A connection between the motor shaft and the housing exists at best indirectly via the single shaft bearing. However, the connection can be vibration-decoupled by damping and/or decoupling elements.

In order to be able to absorb axial forces acting on the motor shaft well, it is provided in a preferred embodiment of the invention that the shaft bearing is formed as a double-row angular contact ball bearing or as a pair of single-row angular contact ball bearings adjacent to one another. The double-row angular contact ball bearing and/or the pair of single-row angular contact ball bearings can each comprise an O-arrangement. The O-arrangement ensures that axial forces can be absorbed in both axial directions.

It is preferable if the shaft bearing is fixed in a bearing plate that is located between the electric motor and the displacement spiral. The bearing plate thus forms a central component that supports both the drive part of the displacement machine as well as the compression part of the displacement machine. Such a central connection not only has advantages in terms of production technology but also offers possibilities for dissipating or collecting vibrations that occur in mechanical operation in order to reduce or even eliminate them at a central location through simple measures. In any case, this ensures that the vibrations that occur throughout the mechanical unit of the displacement machine can be dampened at a central point in order to reduce overall noise emission from the displacement machine.

In this respect, it is particularly preferable if the bearing plate forms an inner housing in which the electric motor is located. The electric motor, the bearing plate, the displacement spiral and the counter spiral can form a compression assembly, particularly mechanically independent, which is located in a housing. The compression assembly can be vibration-decoupled from the housing. In particular, the bearing plate forming the inner housing can be vibration-decoupled from the housing by means of decoupling elements. It is particularly preferable if the compression assembly is fixed exclusively in the housing by means of decoupling elements. Vibrations occurring during operation of the compression assembly are thus not emitted to the housing or are only highly dampened, which significantly reduces the noise development to the outside.

In another preferred embodiment of the displacement machine according to the invention, the housing comprises a housing floor to which an inverter housing can be connected. Alternatively, the housing floor can form part of an inverter housing. The housing floor may be spaced from the electric motor, in particular from a free end of the electric motor located opposite the shaft bearing. In conventional displacement machines, where a second shaft bearing is located in the housing floor, the inverter housing connected to the housing floor forms a resonance chamber that leads to an amplification of the sound emissions. By dispensing with such an additional shaft bearing according to the invention and the distance between the electric motor and the housing floor, the inverter housing is vibrationally decoupled from the mechanically moving parts of the displacement machine, which leads to a further reduction in noise emissions.

In addition to the reduction of noise emissions, the invention has other advantages. On the one hand, the absence of additional shaft bearings reduces the variety of components, which has a positive effect on manufacturing costs. The displacement machine according to the invention therefore comprises a particularly simple structure. In addition, the displacement machine according to the invention is particularly compact, since the motor shaft can be formed for a short time by dispensing with an additional shaft bearing. Overall, this leads to a shortened overall length of the displacement machine. This will improve the installation options of the displacement machine in vehicles.

The invention is explained in more detail below by means of an exemplary embodiment with reference to the attached schematic drawing. The only FIGURE therein shows a longitudinal sectional view through a displacement machine according to the invention.

The only FIGURE shows a displacement machine according to the spiral principle, in particular, a scroll compressor. The scroll compressor comprises a housing 100 that encloses a compression assembly 150. In the exemplary embodiment shown here, the housing 100 is formed from a main housing 110 and a housing cover 120. The main housing 110 is essentially shaped like a pot and sealed by the housing cover 120 at one axial end.

The compression assembly 150 comprises an electric motor 10, which comprises a stator 13 and a rotor 11. The rotor 11 is connected to a motor shaft 12 in a torque-proof manner, which is mounted in a shaft bearing 31. The shaft bearing 31 is preferably designed as a double-row angular contact ball bearing and forms the only bearing for the motor shaft 12. Alternatively, the shaft bearing 31 can also be formed by a pair of single-row angular contact ball bearings adjacent to one another. In any case, the shaft bearing 31 preferably comprises an O-arrangement so that it can absorb axial forces in both directions.

The shaft bearing 31 is preferably the only shaft bearing 31. Specifically, the motor shaft 12 is only supported by the single shaft bearing 31. In particular, on one side opposite the single shaft bearing 31, the motor shaft 12 is bearing-free or not supported by anything. In this respect, the motor shaft 12 is cantilevered by the single shaft bearing 31. In this context, there is talk of a flying bearing of the motor shaft 12.

The motor shaft 12 also comprises a distance to a housing floor 101 of the housing 100. In particular, there is no direct contact between the motor shaft 12 and the housing floor 101. This prevents vibrations from the rotational movement of the motor shaft 12 from being transmitted to the housing 100. An inverter housing may also be located at the housing floor 101. The housing floor 101 can also form a wall of the inverter housing. In both cases, the interior of the inverter housing forms a resonance chamber or resonating body that can amplify sound emissions. By decoupling the motor shaft 12 from the housing floor 101 and thus from the inverter housing, such noise emissions are reduced. The shaft bearing 31 is pressed into a bearing plate 30. The bearing plate 30 separates a drive chamber of the compression assembly 150 from a compression space. The electric motor 10 is located in the drive compartment. The compression chamber comprises a displacement spiral 21 that rests on the bearing plate 30 or a sliding plate located on the bearing plate 30 (not shown). The displacement spiral 21 engages with a counter spiral 22, which is also located in the compression space. The counter spiral 22 is firmly connected to the bearing plate 30, in particular, being screwed.

In order to achieve a good seal of the compression chambers formed between the displacement spiral 21 and the counter spiral 22, the displacement spiral comprises a sealing groove 23. The sealing groove 23 extends preferably in a ring around the longitudinal axis of the motor shaft 12 through the floor of the displacement spiral 21. A seal is included in the sealing groove 23, which is not shown in the figure for reasons of clarity.

Radially within the sealing groove 23, an anti-rotation mechanism 40 is provided. The anti-rotation mechanism 40 comprises a plurality of distributed pins 41 that are firmly placed in the bearing plate 30. The pins 41 project over the bearing plate 30 and engage with bore holes 42, which are formed in the displacement spiral 21. The bore holes 42 comprise a cross-sectional diameter that is significantly larger, in particular, many times larger, than the diameter of the pins. The anti-rotation mechanism 40, also known as the pin/ring mechanism, prevents the displacement spiral 21 from rotating around its central axis. Rather, it is achieved that the displacement spiral is pushed into an orbiting motion. The displacement spiral 21 is driven by the motor shaft 12, which is in contact with the displacement spiral 21 via a compensating mechanism 14 and an eccentric bearing 15. The compensatory mechanism 14 essentially comprises a counterweight that compensates for dynamic imbalances of the displacement spiral 21 and thus causes the compression chambers between the displacement spiral 21 and the counter spiral 22 to be sealed.

As can be seen from the figure, the bearing plate 30 forms an inner housing 32, in which the electric motor 10 is located. In particular, the bearing plate 30 continues in a cylindrical shape and accommodates the stator 13 of the electric motor 10. The stator 13 is preferably firmly connected to the inner housing 32.

The inner housing 32 comprises a plurality of grooves 33, which extend preferably in a ring around the longitudinal axis of the motor shaft 12. A total of four grooves are provided, three of which are radially open outwards, while, in contrast, one groove is open towards an axial end of the inner housing 32. Decoupling elements 34 are located in all grooves 33, which are in contact with the housing 100. The decoupling elements 34 are preferably formed as O-rings made of plastic and/or rubber.

The inner housing 32 comprises play with relation to the housing 100. Specifically, it is provided that there will be a gap between the inner housing 32 and the housing 100. The decoupling elements 34 bridge this gap and keep the inner housing 32 at a distance from the housing 100. There is no metallic contact between the inner housing 32 and the housing 100, which results in sound decoupling.

The counter spiral 22 also comprises grooves 33, each of which accommodates a decoupling element 34. The counter spiral 22 forms the compression module 150 with the inner housing 32 and the components located in the inner housing 32, which is completely sound-decoupled from the housing 100. The support is carried out via the decoupling elements 34, which are located in the grooves 33.

It can also be seen in the figure that one of the grooves 33 in the counter spiral 22 is open in the direction of a free axial end of the housing cover 120. The axially open groove 33 of the inner housing 32 is open in the opposite direction, i.e., in the direction of the free end of the main housing 110. This ensures that the compression assembly 150 is not only radially but also axially decoupled from the housing 100 on both sides. The second groove 33 is radially open outwards in the counter spiral 22, i.e., in the direction of the inner surface of the housing cover 120.

The FIGURE also shows that the compression assembly 150 is mechanically independent on its own. All mechanical processes of the scroll compressor are therefore carried out in the compression module 150. The only task of the housing 100 is to form the appropriate fluid chambers for guiding the working medium to be compacted and to protect the compression module 150 from external environmental influences.

REFERENCE LIST

• • 10 electric motor
  • 11 rotor
  • 12 motor shaft
  • 13 stator
  • 14 balancing mechanism
  • 15 eccentric bearing
  • 21 displacement spiral
  • 22 counter spiral
  • 23 sealing groove
  • 30 bearing plate
  • 31 shaft bearing
  • 32 inner housing
  • 33 groove
  • 34 decoupling element
  • 40 anti-rotation mechanism
  • 41 pin
  • 42 bore hole
  • 100 housing
  • 101 housing floor
  • 110 main housing
  • 120 housing cover
  • 150 compression assembly

Claims

1. A displacement machine according to the spiral principle, in particular, a scroll compressor, comprising an electric motor, an orbiting displacement spiral and a counter spiral, the displacement spiral and the counter spiral engaging into one another in such a way that variable compression chambers are formed between the displacement spiral and the counter spiral in order to receive and compress a working medium flowing through a working medium circuit, and wherein the electric motor is connected to the displacement spiral by means of a motor shaft, and the motor shaft is supported by a single shaft bearing which is located between the electric motor and the displacement spiral.

2. The displacement machine according to claim 1, wherein the motor shaft on one side of the electric motor opposite the shaft bearing is self-supporting, in particular, not supported by anything.

3. The displacement machine according to claim 1, wherein the shaft bearing is formed as a two-row angular contact ball bearing or as a pair of interconnected single-row angular contact ball bearings in an O-arrangement.

4. The displacement machine according to claim 1, wherein the shaft bearing is fixed in a bearing plate which is located between the electric motor and the displacement spiral.

5. The displacement machine according to claim 4, wherein the bearing plate forms an inner housing in which the electric motor is located.

6. The displacement machine according to claim 4, wherein the electric motor, the bearing plate, the displacement spiral and the counter spiral form a compression assembly, in particular, a mechanically independent one, which is located in a housing.

7. The displacement machine according to claim 6 wherein the compression assembly is vibration-decoupled from the housing.

8. The displacement machine according to claim 6, wherein the housing comprises a housing floor to which an inverter housing can be connected or which forms part of an inverter housing, the housing floor being spaced away from the electric motor, in particular, being spaced away from a free end of the electric motor located opposite the shaft bearing.