Volumetric machine according to spiral principle

Abstract

The invention relates to a positive displacement machine, in particular a scroll compressor, according to the spiral principle, comprising an electric motor (10), an orbiting positive displacement spiral (21) and a counter-spiral (22), the positive displacement spiral (21) and the counter-spiral (22) being engaged with each other such that a variable compression chamber is formed between the positive displacement spiral (21) and the counter-spiral (22), the positive displacement screw (21) has a working medium circuit for receiving and compressing the working medium flowing through the working medium circuit, and wherein the electric motor (10) is drivingly connected to the positive displacement screw (21) by means of a motor shaft (12). The invention is characterized in that the motor shaft (12) is supported by a single bearing (31) which is arranged between the electric motor (10) and the positive displacement screw (21).

Description

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

[0002] Positive displacement machines, in particular scroll compressors, which work according to the screw principle are known in practice. Positive displacement machines are often used as compressors for air conditioning systems in vehicles. Typically, such scroll compressors are configured such that a compression assembly is arranged in a housing, the compression assembly having an electric motor, an orbiting positive displacement spiral, a counter-spiral and a support plate. The housing is intended to protect the internal components of the scroll compressor from corrosion.

[0003] The working principle of the scroll compressor is that a positive displacement spiral and a counter-spiral are engaged with each other, thereby forming a variable compression chamber between the positive displacement spiral and the counter-spiral. The working medium flows into these compression chambers and is compressed by the variable compression chambers. The electric motor drives the orbiting positive displacement spiral by means of a motor shaft, which is drivingly connected to the positive displacement spiral.

[0004] Normally, scroll compressors are very efficient and run largely smoothly. However, with the increasing electrification of vehicles, the requirements for smooth operation are increasing significantly. In electrically driven vehicles, even small vibrations of individual components can lead to noticeable noise generation. In conventional vehicles with internal combustion engines, this noise generation is not noticeable due to the vibrations of the internal combustion engine itself. However, in electrically driven vehicles, the vibrations emanating from the vehicle drive are significantly reduced due to the reduction in moving parts. As a result, vibrations of other components in the vehicle become more prominent. Therefore, there is a strong desire to improve the vibration and sound emissions of other moving parts in the vehicle. This also applies in particular to air conditioning compressors in vehicles.

[0005] The object of the present invention is therefore to specify a positive displacement machine according to the screw principle, in particular a scroll compressor, which is improved with regard to vibration and sound emissions.

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

[0007] In particular, the object is solved by a positive displacement machine according to the screw principle, in particular a scroll compressor, comprising an electric motor, an orbiting positive displacement spiral and a counter-spiral, wherein the positive displacement spiral and the counter-spiral are engaged with each other so that a variable compression chamber is formed between the positive displacement spiral and the counter-spiral to accommodate a working medium flowing through a working medium circuit and compress the working medium. The electric motor is drivingly connected to the positive displacement spiral by means of a motor shaft. According to the invention, the motor shaft is supported by a single bearing, which is arranged between the electric motor and the positive displacement spiral.

[0008] The idea underlying the invention is to reduce the number of connections between the moving and immovable parts of a positive displacement machine. As a moving part, the motor shaft requires support, wherein it has been shown that a single bearing is sufficient to stably support the motor shaft. At the same time, by omitting further bearings, the contact with other components, in particular immovable components, is reduced. This results in an improvement in the sound emission of the positive displacement machine. In particular, the vibrations generated by the motor shaft are dissipated in a targeted manner by means of a single bearing. This provides an improved control concept for reducing the transmission of vibrations.

[0009] The motor shaft is preferably unsupported, in particular bearingless, on the side of the electric motor opposite the bearing. In particular, the motor shaft is preferably at a distance from the housing of the positive displacement machine, so that a direct transmission of vibrations via the motor shaft to the housing is avoided. The connection between the motor shaft and the housing is at most indirect via a single bearing. However, the connection can also be decoupled from vibrations by means of damping elements and / or decoupling elements.

[0010] In order to absorb the axial forces acting on the motor shaft well, it is provided in a preferred embodiment of the present invention that the bearing is configured as a double-row angular contact ball bearing (Schrägkugellager) or a pair of single-row angular contact ball bearings adjacent to each other. The double-row angular contact ball bearing and / or the pair of single-row angular contact ball bearings can each have an O-shaped arrangement. The O-shaped arrangement ensures that the axial forces can be absorbed in two axial directions.

[0011] Preferably, the bearing is fastened in a support plate, which is located between the electric motor and the positive displacement screw. The support plate thus constitutes a central component that carries or supports the drive part of the positive displacement machine and the compression part of the positive displacement machine. This central connection not only has advantages in terms of production technology, but also provides the possibility of targeted dissipation or collection of vibrations occurring in mechanical operation in order to reduce or even eliminate them in a central location by simple measures. In any case, it can be ensured in this way that vibrations occurring in the entire mechanical unit of the positive displacement machine can be damped in a central location, so that the sound emissions of the positive displacement machine as a whole are reduced.

[0012] In this respect, it is particularly preferred that the support plate constitutes an inner housing in which the motor is arranged. The motor, the support plate, the volumetric spiral and the counter-spiral can constitute a compression assembly arranged in the housing, which is particularly mechanically independent. The compression assembly can be decoupled from the housing vibration. In particular, the support plate constituting the inner housing can be decoupled from the housing vibration by a decoupling element. It is particularly preferred that the compression assembly is fixed in the housing only by the decoupling element. The vibrations that occur during the operation of the compression assembly are not transmitted to the housing or are only transmitted to the housing in a highly attenuated manner, thereby significantly reducing the transmission of noise to the outside.

[0013] In another preferred embodiment of the volumetric machine according to the invention, the housing has a housing bottom to which the inverter housing can be connected. Alternatively, the housing bottom can constitute 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 opposite the bearing. In conventional volumetric machines, in which the second bearing is arranged in the housing bottom, the inverter housing connected to the housing bottom forms a resonance cavity, which amplifies the sound emission. According to the invention, by omitting such an additional bearing and the distance between the electric motor and the housing bottom, the inverter housing is vibration-decoupled from the mechanical moving parts of the volumetric machine, which leads to a further reduction in sound emissions.

[0014] In addition to the reduction of sound emissions, the invention has further advantages. On the one hand, by eliminating additional bearings, the variety of components is reduced, which has a positive effect on the manufacturing costs. The positive displacement machine according to the invention thus has a particularly simple structure. In addition, the positive displacement machine according to the invention is particularly compact, since by eliminating additional bearings, the motor shaft can be designed to be shorter. Overall, this leads to a shortened structural length of the positive displacement machine. This improves the installation possibilities of the positive displacement machine in a vehicle.

[0015] The invention will be explained in more detail below based on an embodiment and with reference to the attached schematic drawings, in which the single figure shows a longitudinal section through a positive displacement machine according to the invention.

[0016] The single figure shows a positive displacement machine according to the screw principle, in particular a scroll compressor. The scroll compressor has a housing 100 which surrounds a compression assembly 150. In the embodiment shown here, the housing 100 consists of a main housing 110 and a housing cover 120. The main housing 110 is essentially pot-shaped and is closed at the axial ends 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 connected in a rotationally fixed manner to a motor shaft 12, which is mounted in a bearing 31. The bearing 31 is preferably designed as a double-row angular contact ball bearing and constitutes the only support for the motor shaft 12. Alternatively, the bearing 31 can also be composed of a pair of single-row angular contact ball bearings adjacent to each other. In any case, the bearing 31 preferably has an O-shaped arrangement so that the bearing 31 can receive axial forces in two directions.

[0018] The bearing 31 is preferably a single bearing 31. In particular, the motor shaft 12 is supported only by the single bearing 31. In particular, on the side opposite to the single bearing 31, the motor shaft 12 is bearingless or unsupported. In this respect, the motor shaft 12 is mounted here without support by the single bearing 31. In this case, the motor shaft 12 is referred to as cantilevered (fliegend) mounted.

[0019] The motor shaft 12 is also at 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 the vibrations generated by the rotational movement of the motor shaft 12 from being transmitted to the housing 100. The inverter housing can also be arranged on the housing bottom 101. The housing bottom 101 can also constitute the wall of the inverter housing. In both cases, the interior space of the inverter housing forms a resonance chamber or a resonance body that can amplify sound emissions. By decoupling the motor shaft 12 from the housing bottom 101 and thereby from the inverter housing, such sound emissions are reduced.

[0020] The bearing 31 is pressed into the support plate 30. The support plate 30 separates the drive chamber of the compression assembly 150 from the compression chamber. The motor 10 is arranged in the drive chamber. The compression chamber comprises a positive displacement spiral 21, which is located on the support plate 30 or on a sliding plate (not shown) arranged on the support plate 30. The positive displacement spiral 21 engages in a counter spiral 22, which is also arranged in the compression chamber. The counter spiral 22 is firmly connected to the support plate 30, in particular firmly threaded.

[0021] In order to achieve a good seal of the compression chamber formed between the positive displacement spiral 21 and the counter spiral 22, the positive displacement spiral has a sealing groove 23. Preferably, the sealing groove 23 extends annularly through the bottom of the positive displacement spiral 21 around the longitudinal axis of the motor shaft 12. The seal is accommodated in the sealing groove 23, and for the sake of clarity, the seal is not shown in the drawings.

[0022] An anti-rotation mechanism 40 is radially arranged in the sealing groove 23. The anti-rotation mechanism 40 includes a plurality of distributed pins 41, which are fixedly arranged in the support plate 30. The pins 41 protrude beyond the support plate 30 and engage in holes 42, which are formed in the volumetric spiral 21. The cross-sectional diameter of the hole 42 is significantly larger than the diameter of the pin, in particular many times larger. The anti-rotation mechanism 40 (also referred to as the pin / ring mechanism) prevents the volumetric spiral 21 from rotating around its central axis. More specifically, it is achieved that the volumetric spiral is forced to perform an orbital motion. Here, the volumetric spiral 21 is driven by a motor shaft 12, which contacts the volumetric spiral 21 through a compensation mechanism 14 and an eccentric bearing 15. The compensation mechanism 14 mainly includes a counterweight, which compensates for the dynamic imbalance of the volumetric spiral 21, thereby causing the compression chamber between the volumetric spiral 21 and the counter-spiral 22 to be sealed.

[0023] As can be seen from the figure, the support plate 30 constitutes an inner housing 32, in which the electric motor 10 is arranged. In particular, the support plate 30 extends in a cylindrical shape and accommodates the stator 13 of the electric motor 10. Preferably, the stator 13 is firmly connected to the inner housing 32. The inner housing 32 has a plurality of grooves 33, which preferably extend annularly around the longitudinal axis of the motor shaft 12. A total of four grooves are provided, of which three grooves are radially open to the outside and one groove is open in the direction of the axial end of the inner housing 32. Decoupling elements 34 in contact with the housing 100 are arranged in all grooves 33. The decoupling elements 34 are preferably configured as O-rings made of plastic and / or rubber.

[0024] There is a gap between the inner housing 32 and the housing 100. Specifically, it is provided that there is a gap between the inner housing 32 and the housing 100. The decoupling element 34 spans the gap and keeps the inner housing 32 at a certain distance from the housing 100. There is no metal contact between the inner housing 32 and the housing 100, thereby achieving sound decoupling.

[0025] The reverse spiral 22 also has grooves 33, each of which accommodates a decoupling element 34. The reverse spiral 22, together with the inner housing 32 and the components arranged in the inner housing 32, forms a compression assembly 150 which is mounted in a manner completely acoustically decoupled from the housing 100. The support is provided by the decoupling elements 34 arranged in the grooves 33.

[0026] It can also be seen from the figure that one of the grooves 33 in the reverse spiral 22 is open in the direction of the open 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 open end of the main housing 110. In this way, it is ensured that the compression assembly 150 is decoupled from the housing 100 not only radially, but also axially on both sides. The second groove 33 is open radially outward in the reverse spiral 22, i.e. in the direction of the inner surface of the housing cover 120.

[0027] It can also be seen from the figure that the compression assembly 150 itself is mechanically independent. All mechanical processes of the scroll compressor also occur in the compression assembly 150. The task of the housing 100 is only to form a corresponding fluid chamber to guide the working medium to be compressed and to protect the compression assembly 150 from the external environment. Reference Mark List

[0028] 10. Electric Motor 11 Rotor 12 Motor shaft 13. Stator 14 Compensation Agency 15 Eccentric bearing 21 Volumetric Screw 22 Anti-Spiral Pieces 23 Sealing groove 30 Support plate 31 Bearing 32 Inner shell 33 slots 34 Decoupling element 40 Anti-rotation mechanism 41 Pins 42 holes 100 Shell 101 Shell bottom 110 Main housing 120 Housing cover 150 Compression components.

Claims

1. A positive displacement machine according to the screw principle, in particular a scroll compressor, comprising an electric motor (10), an orbiting positive displacement screw (21) and a counter-screw (22), wherein: The volumetric screw (21) and the counter-screw (22) are engaged with each other so that a variable compression chamber is formed between the volumetric screw (21) and the counter-screw (22) to accommodate the working medium flowing through the working medium circuit and compress the working medium, and wherein the electric motor (10) is drivingly connected to the volumetric screw (21) by means of a motor shaft (12), It is characterized in that The motor shaft (12) is supported by a single bearing (31), which is arranged between the electric motor (10) and the positive displacement screw (21).

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

3. A volumetric machine according to claim 1 or 2, characterized in that The bearing (31) is configured as a double-row angular contact ball bearing arranged in an O shape or as a pair of single-row angular contact ball bearings adjacent to each other.

4. A volumetric machine according to any one of the preceding claims, characterised in that The bearing (31) is fastened in a support plate (30), and the support plate (30) is located between the motor (10) and the positive displacement screw (21).

5. The positive displacement machine according to claim 4, characterized in that The support plate (30) forms an inner housing (32), and the electric motor (10) is arranged in the inner housing (32).

6. A volumetric machine according to claim 4 or 5, characterized in that The motor (10), the support plate (30), the positive displacement spiral (21) and the reverse spiral (22) constitute a compression assembly (150). The compression assembly (150) is arranged in a housing (100). The compression assembly (150) is particularly a mechanically independent compression assembly (150).

7. The positive displacement machine according to claim 6, characterized in that The compression assembly (150) is vibrationally decoupled from the housing (100).

8. A positive displacement machine according to claim 6 or 7, characterised in that The housing (100) has a housing bottom (101), to which a converter housing can be connected, or which forms a part of the converter housing, wherein the housing bottom (101) is spaced apart 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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