Displacement machine based on the spiral principle

Description

[0001] The invention relates to a displacement machine based on the spiral principle, in particular a scroll compressor, according to the preamble of claim 1.

[0002] Positive displacement machines operating on the spiral principle, particularly scroll compressors, are well-known in practice. They are commonly used as compressors for air conditioning systems in vehicles. Generally, such scroll compressors are constructed such that a compression assembly, comprising an electric motor, an orbiting displacement spiral, a counter-spiral, and a bearing plate, is housed within a casing. The casing is designed to protect the internal components of the scroll compressor from corrosion.

[0003] The operating principle of the scroll compressor is based on the interlocking of the displacement spiral and the counter-spiral, creating variable compression chambers between them. A working fluid flows into these compression chambers and is compressed by the variable compression chambers. The orbiting displacement spiral is driven by an electric motor via a motor shaft connected to the displacement spiral. Displacement machines based on the spiral principle are known, for example, from JP H03 70888 A and US 2019 / 211820 A1.

[0004] Scroll compressors are generally very efficient and inherently quiet. However, with the increasing electrification of vehicles, the demands on quiet operation are rising considerably. In electrically powered vehicles, even small vibrations in individual components lead to noticeable noise. Such noise is masked in conventional vehicles with combustion engines by the vibrations of the combustion engine itself. In electrically powered vehicles, however, the reduction in moving parts significantly reduces vibrations emitted by the vehicle's drive system. Consequently, vibrations from other vehicle components become more prominent. Therefore, there is a strong focus on improving other moving components in a vehicle with regard to vibration and noise emissions. This particularly applies to air conditioning compressors in vehicles.

[0005] The object of the invention is therefore to provide a displacement machine based on the spiral principle, in particular a scroll compressor, which is improved with regard to vibrations and noise emissions.

[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, especially a scroll compressor, comprising an electric motor, an orbiting displacer spiral, and a counter-spiral, wherein the displacer spiral and the counter-spiral interlock in such a way that variable compression chambers are formed between the displacer spiral and the counter-spiral to receive and compress a working fluid flowing through a working fluid circuit. The electric motor is connected to the displacer spiral by means of a motor shaft. According to the invention, the motor shaft is supported by a single shaft bearing arranged between the electric motor and the displacer spiral.

[0008] 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, and it has been shown that a single shaft bearing is sufficient to provide stable support for the motor shaft. At the same time, contact with other components, especially stationary components, is reduced by eliminating the need for additional shaft bearings. This leads to an improvement in the noise emissions of the displacement machine. Specifically, the vibrations generated by the motor shaft are effectively dissipated via a single shaft bearing. This offers improved control options for reducing vibration transmission.

[0009] Preferably, the motor shaft is cantilevered on the side of the electric motor opposite the shaft bearing, and in particular, is unsupported. Specifically, the motor shaft is preferably spaced from the housing of the displacement machine, so that the transmission of vibrations via the motor shaft directly to the housing is prevented. Any connection between the motor shaft and the housing is only indirect, via the single shaft bearing. However, this connection can be vibration-isolated by damping and / or decoupling elements.

[0010] To effectively absorb axial forces acting on the motor shaft, a preferred embodiment of the invention provides that the shaft bearing is designed as a double-row angular contact ball bearing or as a pair of adjacent single-row angular contact ball bearings. The double-row angular contact ball bearing and / or the pair of single-row angular contact ball bearings can each have an O-arrangement. The O-arrangement ensures that axial forces can be absorbed in both axial directions.

[0011] According to the invention, the shaft bearing is mounted in a bearing plate located between the electric motor and the displacement spiral. The bearing plate thus forms a central component that supports both the drive section and the compression section of the displacement machine. Such a central connection not only offers manufacturing advantages but also provides opportunities to selectively dissipate or collect vibrations occurring during mechanical operation, thereby reducing or even eliminating them through simple measures at a central point. In any case, this ensures that vibrations occurring throughout the entire mechanical unit of the displacement machine can be dampened at a central point, thus reducing overall noise emissions from the displacement machine.

[0012] According to the invention, the bearing plate forms an inner housing in which the electric motor is arranged. The electric motor, the bearing plate, the displacer spiral, and the counter spiral can form a compression assembly, particularly a mechanically independent one, which is arranged in a housing. The compression assembly can be vibrationally decoupled from the housing. In particular, the bearing plate, which forms the inner housing, can be vibrationally decoupled from the housing by means of decoupling elements. It is particularly preferred if the compression assembly is fixed in the housing exclusively by means of decoupling elements. Vibrations occurring during operation of the compression assembly are thus not transmitted to the housing or are only transmitted with significant damping, thereby considerably reducing external noise emissions.

[0013] In a further preferred embodiment of the positive displacement machine according to the invention, the housing has a base to which an inverter housing can be connected. Alternatively, the base can form part of an inverter housing. The base can be spaced apart from the electric motor, in particular from a free end of the electric motor located opposite the shaft bearing. In conventional positive displacement machines, in which a second shaft bearing is arranged in the base, the inverter housing connected to the base forms a resonance chamber, which leads to an amplification of the noise emissions. By eliminating such an additional shaft bearing according to the invention and by maintaining the distance between the electric motor and the base, the inverter housing is vibrationally decoupled from the mechanically moving parts of the positive displacement machine, which leads to a further reduction in noise emissions.

[0014] In addition to reducing noise emissions, the invention offers further advantages. Firstly, the elimination of additional shaft bearings reduces the number of components, which has a positive impact on manufacturing costs. The displacement machine according to the invention thus has a particularly simple design. Furthermore, the displacement machine according to the invention is particularly compact, as the motor shaft can be made shorter by eliminating an additional shaft bearing. Overall, this results in a shorter overall length for the displacement machine. This improves the installation options for the displacement machine in vehicles.

[0015] The invention is explained in more detail below with reference to an exemplary embodiment and the accompanying schematic drawing. The single figure in the drawing shows a longitudinal sectional view through a displacement machine according to the invention.

[0016] The single figure shows a positive displacement machine based on the spiral principle, in particular a scroll compressor. The scroll compressor has a housing 100 that encloses a compression assembly 150. In the embodiment shown here, the housing 100 is formed from a main housing 110 and a housing cover 120. The main housing 110 is essentially pot-shaped and is closed at one axial end by the housing cover 120.

[0017] The compression assembly 150 comprises an electric motor 10 having a stator 13 and a rotor 11. The rotor 11 is non-rotatably connected to a motor shaft 12, which is supported in a shaft bearing 31. The shaft bearing 31 is preferably designed as a double-row angular contact ball bearing and forms the sole support for the motor shaft 12. Alternatively, the shaft bearing 31 can also be formed by a pair of adjacent single-row angular contact ball bearings. In any case, the shaft bearing 31 preferably has an O-arrangement so that it can absorb axial forces in both directions.

[0018] The shaft bearing 31 is preferably the only shaft bearing 31. Specifically, the motor shaft 12 is supported only by the single shaft bearing 31. In particular, on the side opposite the single shaft bearing 31, the motor shaft 12 is unsupported. The motor shaft 12 is thus cantilevered by the single shaft bearing 31. In this context, the motor shaft 12 is referred to as a cantilevered bearing arrangement.

[0019] The motor shaft 12 is further spaced from a housing base 101 of the housing 100. In particular, there is no direct contact between the motor shaft 12 and the housing base 101. This prevents vibrations from the rotational movement of the motor shaft 12 from being transmitted to the housing 100. An inverter housing can also be arranged on the housing base 101. The housing base 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 base 101 and thus from the inverter housing, such sound emissions are reduced.

[0020] 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 chamber. The electric motor 10 is located in the drive chamber. The compression chamber comprises a displacer spiral 21, which rests on the bearing plate 30 or on a sliding plate (not shown) arranged on the bearing plate 30. The displacer spiral 21 engages with a counter-spiral 22, which is also located in the compression chamber. The counter-spiral 22 is firmly connected to the bearing plate 30, in particular by bolting.

[0021] To ensure a good seal between the compression chambers formed between the displacer spiral 21 and the counter-spiral 22, the displacer spiral has a sealing groove 23. The sealing groove 23 preferably extends in an annular shape around the longitudinal axis of the motor shaft 12 through the base of the displacer spiral 21. A seal is accommodated in the sealing groove 23, which is not shown in the figure for the sake of clarity.

[0022] Radially within the sealing groove 23, an anti-rotation mechanism 40 is provided. The anti-rotation mechanism 40 comprises several distributed pins 41, which are fixedly mounted in the bearing plate 30. The pins 41 project beyond the bearing plate 30 and engage in bores 42 formed in the displacer spiral 21. The bores 42 have 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 referred to as a pin / ring mechanism, prevents the displacer spiral 21 from rotating about its central axis. Instead, it forces the displacer spiral into an orbiting motion. The displacer spiral 21 is driven by the motor shaft 12, which is in contact with the displacer spiral 21 via a compensating mechanism 14 and an eccentric bearing 15.The balancing mechanism 14 essentially comprises a counterweight that compensates for dynamic imbalances of the displacer spiral 21 and thus ensures that the compression chambers between the displacer spiral 21 and the counter spiral 22 are sealed.

[0023] As can be seen from the figure, the bearing plate 30 forms an inner housing 32 in which the electric motor 10 is arranged. The bearing plate 30 extends in a cylindrical shape and accommodates the stator 13 of the electric motor 10. The stator 13 is preferably rigidly connected to the inner housing 32.

[0024] The inner housing 32 has several grooves 33, which preferably extend in an annular shape around the longitudinal axis of the motor shaft 12. A total of four grooves are provided, with three grooves opening radially outwards, whereas one groove opens towards an axial end of the inner housing 32.

[0025] Decoupling elements 34 are arranged in all grooves 33 and are in contact with the housing 100. The decoupling elements 34 are preferably formed as O-rings made of plastic and / or rubber.

[0026] The inner housing 32 has a gap relative to the housing 100. Specifically, a gap is designed to exist 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. Thus, there is no metallic contact between the inner housing 32 and the housing 100, thereby achieving acoustic decoupling.

[0027] The counter-spiral 22 also has grooves 33, each of which accommodates a decoupling element 34. The counter-spiral 22, together with the inner housing 32 and the components arranged in the inner housing 32, forms the compression assembly 150, which is completely acoustically decoupled from the housing 100. This decoupling is achieved via the decoupling elements 34, which are arranged in the grooves 33.

[0028] The figure also shows that one of the grooves 33 in the counter spiral 22 is open towards 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., towards the free end of the main housing 110. This ensures that the compression assembly 150 is decoupled from the housing 100 not only radially but also axially on both sides. The second groove 33 in the counter spiral 22 is open radially outwards, i.e., towards the inner surface of the housing cover 120.

[0029] The figure also shows that the compression assembly 150 is mechanically independent in itself. All mechanical processes of the scroll compressor therefore take place within the compression assembly 150. The function of the housing 100 is solely to form the corresponding fluid chambers for guiding the working fluid to be compressed and to protect the compression assembly 150 from external environmental influences. Reference sign

[0030] 10 Electric motor 11 Rotor 12 Motor shaft 13 Stator 14 Compensating 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 100 Housing 101 Housing base 110 Main housing 120 Housing cover 150 Compression assembly

Claims

1. A displacement machine according to the spiral principle, in particular a scroll compressor, with an electric motor (10), an orbiting displacement spiral (21) and a counterspiral (22), wherein the displacement spiral (21) and the counterspiral (22) intermesh in such a way as to form variable compression chambers between the displacement spiral (21) and the counterspiral (22), so as to receive and compress a working medium flowing through a working medium circuit, and wherein the electric motor (10) is drive connected with the displacement spiral (21) by means of an engine shaft (12), wherein the engine shaft (12) is supported by a single shaft bearing (31) arranged between the electric motor (10) and the displacement spiral (21), characterized in that the bearing shaft (31) is fastened in a bearing plate (30) located between the electric motor (10) and the displacement spiral (21), and that the bearing plate (30) forms an inner housing (32) in which the electric motor (10) is arranged, wherein the bearing plate (30) cylindrically continues and receives a stator (13) of the electric motor (10).

2. The displacement machine according to claim 1, characterized in that the engine shaft (12) is cantilevered, in particular unsupported, on a side of the electric motor (10) lying opposite the bearing shaft (31).

3. The displacement machine according to claim 1 or 2, characterized in that the bearing shaft (31) is designed as a two-rowed angular contact ball bearing or as a pair of abutting one-rowed angular contact ball bearings in an O arrangement.

4. The displacement machine according to one of the preceding claims, characterized in that the electric motor (10), the bearing plate (30), the displacement spiral (21) and the counterspiral (22) form an in particular mechanically standalone compression assembly (150), which is arranged in a housing (100).

5. The displacement machine according to claim 4, characterized in that the compression assembly (150) is vibration-isolated from the housing (100).

6. The displacement machine according to claim 4 or 5, characterized in that the housing (100) has a housing floor (101), with which an inverter housing is connectable or which forms a part of an inverter housing, wherein the housing floor (101) is spaced apart from the electric motor (10), in particular from a free end of the electric motor (10) arranged opposite the bearing shaft (31).