Positive 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 (10); an orbiting displacement spiral (21); and a counter spiral (22), the displacement spiral (21) and the counter spiral (22) engaging into one another in such a way that variable compression chambers are formed between the displacement spiral (21) and the counter spiral (22) in order to receive and compress a working medium flowing through a working medium circuit, and the electric motor (10) being drivingly connected to the displacement spiral (21) by means of a motor shaft (12). The invention is characterised in that the motor shaft (12) is supported via a single shaft bearing (31) which is located between the electric motor (10) and the displacement spiral (21).

Description

[0001] Displacement machine based on the spiral principle

[0002] Description

[0003] The invention relates to a positive displacement machine based on the spiral principle, in particular a scroll compressor, according to the preamble of patent claim 1.

[0004] Positive displacement machines operating according to the scroll principle, especially scroll compressors, are well known in practice. They are typically used as compressors for air conditioning systems in vehicles. Such scroll compressors are generally designed with a compression assembly comprising an electric motor, an orbiting displacement scroll, a counter scroll, and a bearing plate, arranged in a housing. The housing is designed to protect the internal components of the scroll compressor from corrosion.

[0005] The operating principle of the scroll compressor is that the displacement scroll and the counter scroll mesh, forming variable compression chambers between the displacement scroll and the counter scroll. A working fluid flows into these compression chambers and is compressed by the variable compression chambers. The orbiting displacement scroll is driven by the electric motor via a motor shaft that is connected to the displacement scroll.

[0006] Scroll compressors are generally very efficient and run smoothly. However, with the increasing electrification of vehicles, the requirements for smooth running are increasing significantly. In electrically powered vehicles, even small vibrations in individual components lead to noticeable noise development. In conventional vehicles with combustion engines, such noise development is drowned out by the vibrations of the combustion engine itself. In electrically powered vehicles, however, the reduction in moving parts results in a significant reduction in the vibrations emitted by the vehicle's drive system. Consequently, vibrations from other components in the vehicle become more prominent. There is therefore a strong desire to improve other moving components in a vehicle with regard to vibrations and noise emissions. This particularly applies to air conditioning compressors in vehicles.

[0007] The object of the invention is therefore to provide a positive displacement machine according to the spiral principle, in particular a scroll compressor, which is improved with regard to vibrations and noise emissions.

[0008] According to the invention, this object is achieved by the subject matter of patent claim 1.

[0009] In particular, the object is achieved by a positive displacement machine based on 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 mesh in such a way 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. The electric motor is drive-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 arranged between the electric motor and the displacement spiral.

[0010] The invention is based on the idea of ​​reducing the number of connections between the moving parts of the positive displacement machine and the 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 stably support the motor shaft. At the same time, contact with other components, especially stationary components, is reduced by eliminating additional shaft bearings. This leads to an improvement in the sound emissions of the positive displacement machine. Specifically, the vibrations generated by the motor shaft are specifically dissipated via a single shaft bearing. This offers improved control options for reducing vibration transmission.

[0011] Preferably, the motor shaft is mounted on a shaft bearing opposite

[0012] The electric motor is self-supporting, particularly unsupported, on the side of the motor. In particular, the motor shaft is preferably spaced apart from a housing of the positive displacement machine, thus preventing the transmission of vibrations via the motor shaft directly to the housing. The connection between the motor shaft and the housing is at most indirect via the single shaft bearing. However, the connection can be vibration-decoupled by damping and / or decoupling elements.

[0013] To effectively absorb axial forces acting on the motor shaft, a preferred embodiment of the invention provides for the shaft bearing to be 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.

[0014] It is preferred if 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 carries or supports both the drive section of the displacement machine and the compression section of the displacement machine. Such a central connection not only has manufacturing advantages but also offers opportunities to specifically divert or collect vibrations that occur during mechanical operation, reducing or even eliminating them centrally through simple measures.

[0015] In any case, this ensures that the vibrations occurring in the entire mechanical unit of the displacement machine can be dampened at a central point in order to reduce the overall noise emission of the displacement machine.

[0016] In this respect, it is particularly preferred if the bearing plate forms an inner 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 assembly, in particular a mechanically independent one, which is arranged 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 decoupling elements. It is particularly preferred if the compression assembly is fixed in the housing exclusively via decoupling elements. Vibrations occurring during operation of the compression assembly are thus not transmitted to the housing or are only transmitted in a strongly dampened manner, thereby significantly reducing noise emission to the outside.

[0017] In a further preferred embodiment of the positive displacement machine according to the invention, the housing has a housing base to which an inverter housing can be connected. Alternatively, the housing base can form part of an inverter housing. The housing base can be spaced apart from the electric motor, in particular from a free end of the electric motor arranged opposite the shaft bearing. In conventional positive displacement machines in which a second shaft bearing is arranged in the housing base, the inverter housing, which is connected to the housing base, forms a resonance chamber which leads to an amplification of the noise emissions. By omitting such a further shaft bearing according to the invention and by the distance between the electric motor and the housing 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.

[0018] In addition to reducing noise emissions, the invention offers further advantages. Firstly, by eliminating the need for additional shaft bearings, the variety of components is reduced, which has a positive impact on manufacturing costs. The positive displacement machine according to the invention thus has a particularly simple design. Furthermore, the positive displacement machine according to the invention is particularly compact, since the motor shaft can be kept short by eliminating the need for an additional shaft bearing. Overall, this results in a shorter overall length of the positive displacement machine. This improves the installation options for the positive displacement machine in vehicles.

[0019] The invention is explained in more detail below using an exemplary embodiment with reference to the accompanying schematic drawing. The sole figure shows a longitudinal sectional view through a displacement machine according to the invention.

[0020] The single figure shows a positive displacement machine based on the scroll principle, in particular a scroll compressor. The scroll compressor has a housing 100 enclosing 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.

[0021] The compression assembly 150 comprises an electric motor 10 having a stator 13 and a rotor 11. The rotor 11 is rotationally fixedly connected to a motor shaft 12, 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 sole bearing 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.

[0022] 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 a side opposite the single shaft bearing 31, the motor shaft 12 is free of bearings or bearingless. The motor shaft 12 is thus supported in a cantilevered manner by the single shaft bearing 31. In this context, the motor shaft 12 is referred to as a floating bearing.

[0023] The motor shaft 12 is also spaced apart 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 resonance body, which 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.

[0024] 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 arranged in the drive chamber. The compression chamber comprises a displacement spiral 21, which rests on the bearing plate 30 or a sliding plate (not shown) arranged on the bearing plate 30. The displacement spiral 21 engages a counter spiral 22, which is also arranged in the compression chamber. The counter spiral 22 is firmly connected, in particular screwed, to the bearing plate 30.

[0025] To ensure a good seal between the compression chambers formed between the displacement spiral 21 and the counter spiral 22, the displacement spiral has a sealing groove 23. The sealing groove 23 preferably extends annularly around the longitudinal axis of the motor shaft 12 through the bottom of the displacement spiral 21. A seal is accommodated in the sealing groove 23, which is not shown in the figure for reasons of clarity.

[0026] An anti-rotation mechanism 40 is provided radially within the sealing groove 23. The anti-rotation mechanism 40 comprises a plurality of distributed pins 41, which are fixedly arranged in the bearing plate 30. The pins 41 protrude beyond the bearing plate 30 and engage in bores 42 formed in the displacement spiral 21. The bores 42 have a cross-sectional diameter that is significantly larger, in particular several times larger, than the diameter of the pins. The anti-rotation mechanism 40, also referred to as a pin / ring mechanism, prevents the displacement spiral 21 from rotating about its central axis. Rather, it forces the displacement spiral 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 balancing mechanism 14 and an eccentric bearing 15.The balancing mechanism 14 essentially comprises a counterweight that compensates for dynamic imbalances of the displacer scroll 21 and thus causes the compression chambers between the displacer scroll 21 and the counter scroll 22 to be sealed.

[0027] As can be seen from the figure, the bearing plate 30 forms an inner housing 32 in which the electric motor 10 is arranged. 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 has a plurality of grooves 33, which preferably extend in a ring 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 is open towards an axial end of the inner housing 32. Decoupling elements 34, which are in contact with the housing 100, are arranged in all grooves 33. The decoupling elements 34 are preferably formed as O-rings made of plastic and / or rubber.

[0028] The inner housing 32 has a clearance relative to the housing 100. Specifically, a gap is provided 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 sound decoupling.

[0029] The counter-volute 22 also has grooves 33, each of which accommodates a decoupling element 34. The counter-volute 22, together with the inner housing 32 and the components arranged in the inner housing 32, forms the compression assembly 150, which is mounted completely acoustically decoupled from the housing 100. The mounting is achieved via the decoupling elements 34, which are arranged in the grooves 33.

[0030] The figure also shows that one of the grooves 33 in the counter-volute 22 is open toward 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., toward 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-volute 22 is open radially outward, i.e., toward the inner surface of the housing cover 120.

[0031] The figure also shows that the compression assembly 150 is mechanically independent. All mechanical processes of the scroll compressor therefore take place within the compression assembly 150. The sole function of the housing 100 is 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.

[0032] Reference symbol

[0033] 10 Electric motor

[0034] 11 Rotor

[0035] 12 Motor shaft

[0036] 13 Stator

[0037] 14 Compensation mechanism

[0038] 15 eccentric bearings

[0039] 21 Displacement spiral

[0040] 22 Counter spiral

[0041] 23 Sealing groove

[0042] 30 bearing plate

[0043] 31 shaft bearings

[0044] 32 inner casings

[0045] 33 grooves

[0046] 34 Decoupling element

[0047] 40 Anti-rotation mechanism

[0048] 41 pen

[0049] 42 bore

[0050] 100 housings

[0051] 101 Case back

[0052] 110 Main body

[0053] 120 housing cover

[0054] 150 compression assembly

Claims

Claims Displacement machine according to the spiral principle, in particular scroll compressor, with an electric motor (10), an orbiting displacer spiral (21) and a counter spiral (22), wherein the displacer spiral (21) and the counter spiral (22) interlock in such a way that variable compression chambers are formed between the displacer spiral (21) and the counter spiral (22) in order to receive and compress a working medium flowing through a working medium circuit, and wherein the electric motor (10) is connected to the displacer spiral (21) by means of a motor shaft (12) characterized by the fact that the motor shaft (12) is supported by a single shaft bearing (31) which is arranged between the electric motor (10) and the displacer spiral (21). Displacement machine according to claim 1 dad u rch kenn ncharakter net that the motor shaft (12) is free-supporting, in particular unsupported, on a side of the electric motor (10) opposite the shaft bearing (31).A displacement machine according to claim 1 or 2 is characterized by the fact that the shaft bearing (31) is formed as a double-row angular contact ball bearing or as a pair of adjacent single-row angular contact ball bearings in an O-arrangement. A displacement machine according to any of the preceding claims is characterized by the fact that the shaft bearing (31) is mounted in a bearing plate (30) located between the electric motor (10) and the displacement spiral (21). A displacement machine according to claim 4 is characterized by the fact that the bearing plate (30) forms an inner housing (32) in which the... An electric motor (10) is arranged. A positive displacement machine according to claim 4 or 5 is characterized by the fact that the electric motor (10), the bearing plate (30), the displacer spiral (21) and the counter spiral (22) form a compression assembly (150), in particular a mechanically independent one, which is arranged in a housing (100). A positive displacement machine according to claim 6 is characterized by the fact that the compression assembly (150) is vibrationally decoupled from the housing (100). Displacement machine according to claim 6 or 7 is characterized by the fact that the housing (100) has a housing base (101) with which an inverter housing can be connected or which forms part of an inverter housing, wherein the housing base (101) is spaced apart from the electric motor (10), in particular from a free end of the electric motor (10) arranged opposite the shaft bearing (31).

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