Compressor for a motor vehicle

Abstract

The invention relates to a compressor (2) for a motor vehicle, the compressor comprising: a compressor housing (14) having a low-pressure-side inlet (50) and a high-pressure-side outlet (52); an electric-motor drive (4); and a compressor head (6) coupled to the electric-motor drive via a drive shaft (30), wherein the compressor head (6) comprises a compression chamber (40) for compressing an oil-fluid mixture, a high-pressure chamber (56) coupled thereto for pulsation damping, and a reservoir chamber (58) that is coupled to the drive shaft (30) and forms a high-pressure oil reservoir, wherein the high-pressure chamber (56) and the reservoir chamber (58) are separated from one another by a partition wall (62), wherein an oil separator (68) for separating the oil-fluid mixture is arranged in the partition wall (62), wherein an inlet (74) of the oil separator (68) is coupled to the high-pressure chamber (56), wherein a fluid outlet (76) of the oil separator (68) is coupled to the outlet (52), and wherein an oil outlet (80) of the oil separator (68) is coupled to the reservoir chamber (58).

Description

[0001] Page 1

[0002] 2023 291 WO

[0003] Description

[0004] Compressor for a motor vehicle

[0005] The invention relates to a positive displacement machine or a rotary compressor, in particular in the form of a scroll or rotary piston compressor for a motor vehicle, which is used in particular for the compression of refrigerant in a vehicle air conditioning system.

[0006] Motor vehicles are regularly equipped with air conditioning systems that use a refrigerant circuit to regulate the vehicle interior (passenger compartment), i.e., to cool and heat it. In electrically powered or plug-in hybrid vehicles, the air conditioning system can also be used to condition the vehicle battery (traction battery). These systems generally consist of a closed loop containing a refrigerant. The refrigerant, for example, R-744 (carbon dioxide, CO2), is heated at an evaporator and compressed by a refrigerant compressor. The refrigerant then releases the absorbed heat via a heat exchanger before being returned to the evaporator through an expansion valve.

[0007] In electrically or electromechanically driven refrigerant compressors, the compressor mechanism, the electric motor, and the motor electronics (control unit, ECU) are typically housed together in a single compressor casing. Part of the compressor casing is thus exposed to suction pressure (low-pressure side) and another part to discharge pressure (high-pressure side). The suction gas is also used to cool the electric motor and the electronics. Page 2

[0008] Refrigerant compressors in vehicle air conditioning systems are typically scroll compressors, used to compress a refrigerant-oil mixture. The resulting gas-oil mixture is separated, with the separated gas being introduced into the air conditioning circuit, while the separated oil is usually circulated within the scroll compressor to lubricate moving parts.

[0009] So-called rolling piston compressors are generally not used for automotive applications, but only for stationary applications, such as cooling systems and heat pumps.

[0010] In rotary piston compressors, a cylindrical or piston-like compressor rotor rotates completely around an eccentric axis; therefore, rotary piston compressors are also called rotary or circulating compressors. A spring-loaded separating or shut-off valve (vane) is pressed radially against the outer circumference of the compressor rotor, dividing the compressor chamber into two separate chambers (suction and pressure chambers). When a gaseous refrigerant enters the compressor on the suction side (suction gas), it is forced against the separating valve by the compressor rotor, which rolls along the inner wall of the compressor chamber. The rotational movement reduces the volume of the pressure chamber, thus compressing the refrigerant. The separating valve, which moves back and forth with the rotation of the rotor, seals the suction side from the pressure side, eliminating the need for additional inlet valves (suction valves) for the compressor chamber.Rotary piston compressors thus achieve a high coefficient of performance and exhibit particularly low noise levels.

[0011] Rotary piston compressors in stationary applications typically feature a vertical hollow shaft with radial bores, one open end of which is immersed in an oil sump (oil pan) serving as the oil reservoir. The oil is drawn upwards through the hollow shaft and, with the aid of an internal oil slinger plate, continuously supplies the shaft bearings with oil. Another feature of such compressors (see page 3)

[0012] The key feature of a rotary piston compressor is that the compressor housing, particularly the oil sump, is under a uniform gas pressure. In other words, the compressor housing is under either high or medium pressure. Due to this uniform gas pressure inside the compressor housing, the end faces of the hollow shaft are at the same pressure level, so no pressure-induced axial force acts on the hollow shaft.

[0013] In contrast, refrigerant compressors in vehicle air conditioning systems have a horizontally oriented shaft when installed. Furthermore, these refrigerant compressors do not have a traditional oil pan. Because the electric motor and electronics are cooled by the suction gas, the compressor housings of refrigerant compressors in motor vehicles also do not have a uniform gas pressure inside the housing.

[0014] Due to the limited space between the compressor housing and the electric motor rotor, an oil reservoir on the low-pressure side of the rotary piston compressor is generally not feasible. Furthermore, a low-pressure oil reservoir presents the additional challenge of how to deliver the oil from the reservoir, through the hollow shaft, to the sliding bearing lubrication system.

[0015] The compressor mechanism of the rotary piston compressor generates a pulsating flow of the compressed gas-oil mixture. Due to the associated (flow) turbulence, it is not possible to provide a stable oil reservoir free of dissolved refrigerant gas bubbles on the high-pressure side without additional components.

[0016] The invention is based on the objective of providing a particularly suitable compressor for a motor vehicle. In particular, a rotary piston compressor with a minimally volatile oil reservoir for supplying the hollow shaft or the plain bearings with oil as a lubricant is to be provided. Page 4

[0017] The problem is solved according to the invention with the features of claim 1. Advantageous embodiments and further developments are the subject of the dependent claims.

[0018] The compressor according to the invention is intended for, and suitable and configured for, a motor vehicle, in particular for a vehicle air conditioning system. The compressor has a compressor housing with a low-pressure or suction-side inlet and a high-pressure or discharge-side outlet. An electric motor drive is arranged in the compressor housing, which drives a (rotary piston) compressor mechanism. During operation, the compressor pumps or compresses a refrigerant, in particular a chemical or natural refrigerant, preferably carbon dioxide (R744).

[0019] The drive comprises an electric motor, in particular a brushless electric motor, which can be powered by motor or control electronics. The electric motor has a stator fixed to the housing and a rotor mounted to rotate or rotate relative to the stator. The stator is wound with a rotating field or stator winding, and the rotor is, for example, equipped with permanent magnet rotor magnets. The rotor is rigidly connected to a motor or drive shaft. The drive shaft is mounted to rotate or rotate in the compressor housing by means of shaft bearings. Preferably, the drive shaft is mounted by means of plain bearings.

[0020] The motor electronics are housed in a fluid- and pressure-tight separate electronics compartment within the compressor housing. Preferably, the inlet is oriented such that the incoming refrigerant flows along a housing wall of the electronics compartment, thus cooling it. The refrigerant also flows around the electric motor, so that in particular the energized or energizable rotating field or stator winding is cooled.

[0021] The drive shaft is coupled to a compressor head. The compressor head contains the compressor mechanism, which draws in the refrigerant from side 5 of the low-pressure side, compresses it, and delivers it via a high-pressure side through the outlet of the compressor housing.

[0022] The compressor head has a compressor chamber for compressing an oil-fluid mixture and a high-pressure chamber coupled to it for pulsation damping, as well as a reservoir chamber as a high-pressure oil reservoir.

[0023] The compressor mechanism, which includes at least one compressor rotor driven eccentrically by the drive shaft, is located within the compressor chamber. A spring-loaded separator is also located within the compressor chamber to divide it into a suction chamber and a pressure chamber. This separator is pressed radially against the compressor rotor by means of a spring element, in particular a compression or helical spring. The compressed medium is pulsated into the high-pressure chamber via an outlet. To reduce the resulting pulsations (pressure waves in the flowing medium or varying flow velocity), the high-pressure chamber is preferably designed as a pulsation volume (so-called muffler).

[0024] The robustness and service life of the rotary piston compressor depend crucially on the tribological conditions during operation. These can be significantly improved by adequate and continuous lubrication. The rotary piston compressor is primarily oil-lubricated and features an integrated oil circuit for a (lubricating) oil. The term "oil" here is not limited to mineral oils. Fully synthetic or semi-synthetic oils, silicone oils, or other lubricants can also be used.

[0025] In particular, a mixture of refrigerant (gas) and special oils (e.g., PAG or POE) is used. The oil then distributes itself through the flow conditions within the system and within the compressor. Redistribution of the oil into the system components of a connected refrigerant circuit is undesirable and leads to poorer heat transfer and consequently to lower system efficiencies (COP). The actual purpose of the oil is described on page 6.

[0026] Compressor chamber and the lubrication or friction reduction between stressed compressor components such as the shaft bearing and the separating slide.

[0027] During operation of the refrigerant drive, or compressor, a fluid in the form of gaseous refrigerant is introduced into the compressor housing through the inlet. This area of ​​the compressor housing forms the suction or low-pressure side of the rotary compressor. Inside the compressor housing, the refrigerant is mixed with oil to form a fluid-oil mixture, and is drawn along the rotor and stator through an opening to the compressor head. The compressor mechanism compresses the refrigerant-oil mixture, with the oil lubricating the at least one compressor rotor, thus reducing friction and consequently increasing efficiency. The oil also acts as a seal to prevent uncontrolled escape of the refrigerant from the pressure chamber to the suction chamber.

[0028] Oil separation systems are used to separate the oil (which is usually present in droplet form within the flowing refrigerant) and retain it within the compressor. For this purpose, the high-pressure side has an oil reservoir to collect and stabilize the separated oil; this reservoir is formed by a reservoir chamber. The reservoir chamber and the high-pressure chamber are spatially separated by a partition wall, in which an oil separator, such as a cyclone separator, is arranged or integrated. The collected oil can then be cooled in the reservoir chamber via housing surfaces and returned to relevant friction points of the compressor via an oil recirculation system, particularly one driven by pressure.

[0029] The oil separator has an inlet for the fluid-oil mixture or refrigerant-oil mixture, as well as a fluid outlet (refrigerant outlet) and an oil outlet. The inlet of the oil separator is coupled to the high-pressure chamber, so that a pulsation-reduced flow enters the oil separator (page 7). The separated fluid or refrigerant is directed via the fluid outlet towards the compressor housing outlet, with the oil being separated into the reservoir chamber via the oil outlet.

[0030] The compressed refrigerant-oil mixture is fed into a high-pressure chamber within the compressor housing, forming the high-pressure side. Within the oil separator located in the partition wall, the refrigerant-oil mixture is set into rotation. Due to its increased inertia and mass, the heavier oil is forced by centrifugal force towards the walls of the oil separator and collected, for example, under the influence of gravity (g), in the reservoir chamber, which serves as the oil collection area. Meanwhile, the refrigerant is discharged upwards or laterally through the outlet. The oil is then returned to the electric motor via an oil recirculation system.

[0031] The partition wall with its integrated oil separator creates a particularly suitable compressor in which the high-pressure chamber acts as a pulsation damping chamber, while the reservoir chamber serves as a high-pressure oil reservoir. The pulsation damping in the high-pressure chamber thus introduces a fluid-oil mixture with reduced pulsation and turbulence into the oil separator. Consequently, the separated oil contains fewer dissolved gas bubbles (refrigerant bubbles), resulting in a more stable oil reservoir for the integrated oil circuit of the rotary piston compressor. This significantly improves the lubrication and sealing—and therefore the efficiency—of the compressor, as well as its service life.

[0032] In this and the following, "axial" or an "axial direction" refers specifically to a direction parallel (coaxial) to the axis of rotation of the electric motor, i.e., along a longitudinal direction of the drive shaft. Similarly, in this and the following, "radial" or a "radial direction" refers specifically to a direction oriented perpendicular (transverse) to the axis of rotation of the electric motor, along a radius of the drive shaft or the electric motor itself. (See page 8.)

[0033] "Tangential" or "tangential direction" is understood here and in the following to mean in particular a direction along the circumference of the hollow shaft or the electric motor (circumferential direction, azimuthal direction), i.e. a direction perpendicular to the axial direction and to the radial direction.

[0034] The compressor is designed, for example, as a scroll compressor or a rotary piston compressor. In the following, the compressor will be specifically referred to as a rotary piston compressor, without limiting the generality of the term.

[0035] In the installed state, the drive shaft, which is preferably arranged horizontally or lying down, is designed as a hollow shaft in the rotary piston compressor and will be referred to as such below. The hollow shaft is open axially at both ends, meaning that it has an axial bore which opens into a high-pressure inlet and a low-pressure outlet at its end face. The hollow shaft also has a number of radial bores connected to the axial bore. These radial bores are preferably located at the level of the shaft bearings. The oil contained in the hollow shaft exits through the radial bores due to centrifugal force, thus lubricating the shaft or sliding bearings of the hollow shaft. The hollow shaft is part of the oil return system, with the oil being returned from the reservoir chamber via the hollow shaft under pressure.

[0036] The compressor housing has an outlet chamber volume located between the compressor chamber and the outlet, which is divided into the high-pressure chamber and the reservoir chamber by the partition. In an advantageous embodiment, the partition and the oil separator are designed as a pre-assembled unit, which is installed in the compressor housing to form the high-pressure chamber and the reservoir chamber. In other words, the gas volume on the high-pressure side is divided into two partial volumes by the partition or the assembly. The partition is preferably inserted axially into the compressor housing to separate the outlet chamber volume. Advantageously, the partition has a circumferential sealing element (see page 9) for radially sealing the high-pressure chamber and the reservoir chamber against the inner wall of the compressor housing.This makes the compressor housing or the outlet chamber volume particularly easy to design, thus simplifying the assembly and manufacturing of the rotary piston compressor.

[0037] Since the partition is located on the high-pressure side of the rotary piston compressor, it possesses sufficient mechanical stability to prevent deformation during compressor operation. In a suitable embodiment, the partition is manufactured as a die-cast part, particularly an aluminum die-cast part, or as a plastic part, particularly an injection-molded part.

[0038] An additional aspect of the invention provides that a riser pipe is arranged between the oil outlet of the oil separator and the reservoir chamber. The riser pipe opens into the reservoir chamber. The riser pipe ensures the highest possible fill level of the reservoir chamber with oil. In other words, it ensures that the high-pressure side oil reservoir is filled as completely as possible, so that sufficient oil is always available for oil return via the hollow shaft.

[0039] In a preferred embodiment, the riser pipe is integrated into the partition. Preferably, the riser pipe is integral with the partition, i.e., formed in one piece or monolithically, or molded onto or into it. This achieves a particularly advantageous functional integration of the partition. In particular, the partition thus essentially performs three functions: separation of the oil reservoir (reservoir chamber) and pulsation damping (high-pressure chamber), oil separation, and ensuring a desired fill level in the oil reservoir.

[0040] The orientation or angle of the riser pipe to the oil separator or to a direction of gravity depends on the position of the compressor housing outlet. Preferably, the riser pipe is oriented as vertically as possible to ensure the highest possible fill level in the oil reservoir. In a suitable orientation, the riser pipe is essentially vertical, i.e., parallel to the direction of gravity. Alternatively, the riser pipe has an angle of less than 45°, for example, 0° to 45°, particularly approximately 30°, relative to the direction of gravity. For example, the riser pipe can have an inclination within a range of ± 45°.

[0041] In a further advantageous embodiment, the partition wall has a cylindrical channel in which the oil separator is either seated or inserted. Preferably, the channel is open axially towards the outlet of the compressor housing, with the fluid outlet of the oil separator oriented towards this end face. The channel and the oil separator seated therein provide a fluid and pressure connection between the high-pressure chamber and the reservoir chamber.

[0042] For this purpose, the channel has a first inlet from the high-pressure chamber into the channel, with the inlet of the oil separator being located at this first inlet. The channel also has a second inlet from the reservoir chamber into the channel. Preferably, fluid or refrigerant that was dissolved in the separated oil is returned from the oil reservoir to the channel, particularly to the inlet of the oil separator. The channel further has an outlet from the channel volume to the reservoir chamber or the riser pipe, which is located in the area of ​​the oil outlet of the oil separator.

[0043] In an advantageous embodiment, the second channel inlet from the reservoir chamber and the channel outlet into the reservoir chamber or into the riser pipe are arranged offset from each other in the direction of gravity, with the second channel inlet being arranged in the direction of gravity, in particular above the channel outlet.

[0044] Preferably, the separated oil is routed via the channel outlet into the riser pipe. Through the riser pipe, the oil is filled into the reservoir chamber against the direction of gravity "from the top" (page 11), allowing it to settle and defoam. In particular, this causes (fluid or refrigerant) bubbles to rise from the fluid or oil sump to the surface and be guided back to the oil separator inlet via the second channel inlet located above. This ensures that, as far as possible, only fluid or oil is returned via the hollow shaft.

[0045] Exemplary embodiments of the invention are explained in more detail below with reference to a drawing. The drawing shows:

[0046] Fig. 1 shows a schematic representation of a rotary piston compressor,

[0047] Fig. 2 shows a partial perspective sectional view of the outlet chamber volume of the rotary piston compressor, which is divided into a high-pressure chamber and a reservoir chamber by a partition assembly.

[0048] Fig. 3 shows a partial perspective sectional view of the outlet chamber volume, where the partition assembly has an integrated riser pipe.

[0049] Fig. 4 shows a perspective view of the partition assembly looking towards one side of a high-pressure chamber.

[0050] Fig. 5 shows a perspective view of the partition assembly looking towards one side of a reservoir chamber.

[0051] Fig. 6 shows a perspective view of a partition wall assembly in a partially disassembled state, and

[0052] Fig. 7 shows the partition wall assembly in a perspective sectional view.

[0053] Corresponding parts and sizes are always marked with the same reference symbols in all figures.

[0054] Figure 1 shows a schematic and highly simplified representation of a compressor 2 according to the invention, which is installed, for example, as a refrigerant compressor in a refrigerant circuit (not shown) of an air conditioning system in a motor vehicle. The refrigerant used is, for example, R744. (See page 12.)

[0055] Compressor 2, for example, is designed as a rotary piston compressor, and will be referred to as such below.

[0056] The modularly constructed electric refrigerant or rotary piston compressor 2 has an electric (electromotive) drive (drive module) 4 and a compressor head (compressor module) 6 coupled to it. A bearing plate (center plate) 8 is provided between the drive 4 and the compressor head 6 as a mechanical interface, by means of which the compressor head 6 is connected to the drive 4.

[0057] The bearing shield 8 forms an intermediate wall between a drive housing 10 and a compressor head housing 12. The bearing shield 8, the drive housing 10, and the compressor head housing 12 form a compressor housing 14 of the rotary piston compressor 2. The compressor head 6 is connected to the drive 4, for example, by means of circumferentially distributed flange connections extending in an axial direction A of the rotary piston compressor 2 (joined, bolted).

[0058] A compressor-side housing section of the drive housing 10 is designed as a motor housing or motor compartment 16 for accommodating an electric motor 18 and is closed on one side by an integrated housing partition 20 to an electronics compartment (electronics housing) 24, which is provided with a housing cover 22 and contains motor electronics (electronics) that control the electric motor 18 (not shown in detail), and on the other side by the bearing shield 8. The drive housing 10 has a connection section (not shown in detail) in the area of ​​the electronics housing 16 for electrically connecting the electronics 18 to the vehicle's electrical system.

[0059] The electric motor 18, which is designed to be brushless, has a housing-mounted or stationary stator 26 equipped with a rotating field winding. The rotating field winding is connected to the electronics via vias through the (housing) partition 20. The electric motor 18 also has a rotor 28, which is shaft-mounted to a drive or side 13

[0060] Motor shaft 30 is attached. The drive shaft 30 is designed as a hollow shaft and will subsequently be referred to as such.

[0061] In this and the following, "axial" or "axial direction A" refers in particular to a direction parallel (coaxial) to the axis of rotation of the electric motor 18, i.e., along the longitudinal direction of the rotary piston compressor 2. Similarly, in this and the following, "radial" or "radial direction" refers in particular to a direction oriented perpendicular (transverse) to the axis of rotation of the electric motor 18 along a radius of the electric motor 18. In this and the following, "tangential" or "tangential direction" refers in particular to a direction along the circumference of the electric motor (circumferential direction, azimuthal direction), i.e., a direction perpendicular to both the axial and radial directions. In the figures, the direction of gravity (gravitational direction) is denoted by g and shown as an example.

[0062] The hollow shaft 30 has a central axial bore 32, which opens at the shaft end or face into a compressor head-side (hollow shaft) inlet 34 and an electric motor-side (hollow shaft) outlet 36. The hollow shaft 30 also has a number of axially distributed radial bores (not shown). These bores extend radially through the hollow shaft 30 from the bore 32 and are open towards the outer circumference of the hollow shaft 30.

[0063] The compressor head 6 has a (rotary piston) compressor mechanism. In the exemplary embodiment, the compressor mechanism is particularly designed as a two-stage unit, wherein two compressor rotors 38a, 38b are eccentrically connected to the hollow shaft 30. The compressor rotors 38a, 38b are arranged in a compressor chamber 40. A housing-mounted valve plate 42 is arranged between the compressor rotors 38a, 38b, which divides the compressor chamber 40 into a first sub-chamber 40a – facing a low-pressure side 44 – and a second sub-chamber 40b – facing a high-pressure side 46. Page 14

[0064] In each of the sub-chambers 40a, 40b, one of the compressor rotors 38a, 38b and a spring-loaded separating slide (not shown) for separating the sub-chambers 40a, 40b into a suction chamber and a pressure chamber are arranged. The separating slides are pressed radially against the respective compressor rotor 38a, 38b by means of a spring element, in particular a compression or helical spring. Sub-chamber 40a is fluidly connected to the motor compartment 16, which forms the low-pressure side 44 of the compressor housing 14, and to sub-chamber 40b. Sub-chamber 40b is fluidly connected to sub-chamber 46a and to an outlet chamber volume 48, which forms the high-pressure side 46 of the compressor housing 14.

[0065] The rotary piston compressor 2 has a (refrigerant) inlet or (refrigerant) supply 50 for connection to the refrigerant circuit and a (refrigerant) outlet 52. The inlet 50 is formed in a region of the drive housing 10 facing the electronics compartment 24. The outlet 52 is formed on the base of a compressor head housing 12 in the region of the outlet chamber volume 48. When connected, the inlet 50 connected to the motor compartment 18 forms the low-pressure or suction side 44 (suction gas side), and the one connected to the outlet 52 forms the high-pressure or pump side (pump side) of the rotary piston compressor 2.

[0066] The hollow shaft 30, which in the installed state is arranged particularly horizontally or lying down, is rotatably or perpendicularly mounted in the compressor housing 14 by means of three shaft bearings. The shaft bearings, which are not shown in detail, are preferably designed as plain bearings. One shaft bearing is arranged in a bearing seat connected to the motor compartment 16, which is integrally formed on the housing base or on the intermediate wall 20 of the drive housing 10. The second shaft bearing is received in the bearing shield 8 that delimits the sub-chamber 38a, and the third shaft bearing is arranged in a bearing shield 53 that delimits the sub-chamber 40b from the outlet chamber volume 48. Page 15

[0067] As shown in more detail in Fig. 2, for example, a partition assembly 54 is inserted into the compressor head housing 14, which divides the outlet chamber volume 48, or the high-pressure side 46, into a high-pressure chamber 56 and a reservoir chamber 58. An axial bore 60 of the compressor head housing 14, which runs laterally past the high-pressure chamber 56, opens into the reservoir chamber 58.

[0068] The partition assembly 54 has a disc- or plate-shaped partition (separating disc) 62. A sealing element 64 is provided on the outer circumference of the partition 60, which seals the partition 62 – and thus the high-pressure chamber 56 and the reservoir chamber 58 – radially against the inner walls of the compressor head housing 12.

[0069] A cylindrical channel 66 is incorporated or molded into the partition wall 62, which is primarily a die-cast part, and an oil separator 68 is arranged within it. The high-pressure chamber 56 is coupled to the outlet of the compressor chamber 40 and to the channel 66. The channel 66 is coupled to the high-pressure chamber 56, to the outlet 52, and to the reservoir chamber 58.

[0070] Channel 66 is connected to the high-pressure chamber 56 via a channel inlet (not shown in detail). Channel 66 opens axially at its end face towards the outlet 52 of the compressor head housing 12 with respect to a longitudinal channel axis, with the oil separator 68 extending at least partially into the compressor head housing 12 or into the outlet 52 when installed (see, for example, Fig. 2). Channel 66 also has two fluid connections to the reservoir chamber 58 in the form of a channel outlet 70 and a channel inlet 72.

[0071] The compressed oil-refrigerant mixture is introduced from the compressor chamber 40 into the high-pressure chamber 56 as a pulsation-damping volume. From there, the pulsation-damped oil-refrigerant mixture flows through the channel inlet into the channel 66, and is then directed radially and / or tangentially into an inlet 74 of the oil separator 68. The oil separator 68 is, for example, designed as a cyclone separator and separates the flowing oil-refrigerant mixture into a page 16

[0072] Refrigerant gas stream, which is discharged via a fluid outlet 76 to the outlet 52, and into droplet-shaped oil 78, which is separated via an oil outlet 80 into the channel 66.

[0073] The separated oil 78 collects by gravity at the bottom of the channel 66 opposite the outlet 52. A bore oriented radially to the channel 66 and parallel to the axial direction A is provided in this bottom region as a channel outlet 70, through which the oil 78 flows into the reservoir chamber 58. The oil 78 is collected and settled in the reservoir chamber 58, which is designed as a (high-pressure) oil reservoir. Gaseous refrigerant dissolved in the separated oil 78 escapes from the oil 78 as bubbles (defoaming) and is returned to the inlet 74 of the oil separator 68 via the channel inlet 72. For this purpose, the channel inlet 72 is arranged above the channel outlet 70 in the direction of gravity g when installed. Preferably, the channel inlet 72 is aligned with the inlet 74 with respect to the direction of gravity g.The separated and recirculated refrigerant is expelled through the fluid outlet 76 and via the outlet 52 from the compressor housing 14.

[0074] During compressor operation, the refrigerant is drawn into the motor compartment 16 through the inlet 50. The refrigerant flows along the partition 20, allowing the motor electronics to be cooled through this partition. Furthermore, the refrigerant flows around and cools the rotating field winding of the stator 26.

[0075] To lubricate the shaft bearings, a lubricant or oil (e.g., PAG or POE) is added to the refrigerant within the motor compartment 16 or on the low-pressure side 44 of the compressor housing 14. The fluid flow delivered by the rotary piston compressor 2 is therefore a mixture of the gaseous refrigerant and the liquid, droplet-shaped oil.

[0076] The refrigerant-oil mixture is drawn into the suction chamber of subchamber 40a through corresponding openings in the bearing shield 8 and compressed by the first compressor rotor. The compressed refrigerant-oil mixture is discharged into the [page 17]

[0077] The oil is introduced into the suction chamber of sub-chamber 40a and further compressed there by means of the second compressor rotor. The oil also serves to lubricate the two separating slides, thus reducing friction and consequently increasing efficiency. The oil also acts as a seal between the suction and pressure chambers, which are separated by the separating slides, to prevent uncontrolled escape through the slides. After this two-stage compression, the compressed refrigerant-oil mixture is introduced into the high-pressure chamber 56, or rather into the high-pressure side 46 of the compressor housing 14.

[0078] The pulsations of the compressed refrigerant-oil mixture are dampened by the volume of the high-pressure chamber 56, and the refrigerant-oil mixture is introduced into the channel 66. The oil is separated from the refrigerant by the oil separator 68. The refrigerant is expelled via the outlet 52, with the oil 78 being collected in the reservoir chamber 58 and returned to the low-pressure side 44 via oil recirculation for the lubrication of the shaft bearings.

[0079] In the operating state shown in Fig. 2, the reservoir chamber 58 is at least partially filled with the separated oil 78. Due to the pressure difference between the high-pressure side 46 and the low-pressure side 44, the oil 78 flows through the bore 60. The bore 60 is located at the bottom of the reservoir chamber 58 with respect to the direction of gravity g.

[0080] For example, a throttling element (not shown) can be arranged in bore 60, which reduces the (static) high pressure of the oil 78 to the low pressure level of the low-pressure side 44. The oil 78, now at low pressure, is then guided via a radial bore 82 into a receptacle 84 located between the compressor chamber 40 and the high-pressure chamber 56, and enters the hollow shaft inlet 34 there. The reservoir chamber 58 is thus coupled or connected to the hollow shaft inlet 34 of the hollow shaft 30 via bores 60, 82 and the receptacle 84.

[0081] The oil 78 flows axially through the bore 32 to the hollow shaft outlet 36. The radial bores are arranged at the level of the shaft bearings, so that the oil (page 18)

[0082] The oil 78 is flung out of bore 32 through the radial bores by centrifugal force, thus lubricating the shaft bearings. The excess oil 78 exits at the hollow shaft outlet 36 into the engine compartment 16 or the low-pressure side 46, and is mixed again with the refrigerant.

[0083] A second embodiment of the partition assembly 54 is explained in more detail below with reference to Figures 3 to 7.

[0084] In this embodiment, the partition wall 62 of the partition wall assembly 54 has an additional riser pipe 86 which connects the channel outlet 70 to the reservoir chamber 58.

[0085] The partition wall 62 shown individually in Fig. 4 and Fig. 5 is in particular designed as a die-cast part, for example as an aluminium die-cast part, wherein the channel 66 and the riser pipe 86 are integrally formed, i.e. in one piece or monolithically, on the partition wall 62.

[0086] The riser pipe 86 ensures the highest possible fill level of the reservoir chamber 58 with oil 78 (Fig. 3). In other words, it ensures that the high-pressure side oil reservoir is filled as completely as possible, so that sufficient oil 78 is always available for oil return via the hollow shaft 30.

[0087] As can be seen particularly in Fig. 5, the riser pipe 86 is oriented at an angle W to a longitudinal direction of the channel. In this embodiment, the channel 66 is arranged substantially parallel to the direction of gravity g in the installed state, so that the riser pipe 86 is oriented obliquely or inclined to the direction of gravity g. In this embodiment, the riser pipe 86 has an angle W of approximately 30°.

[0088] The separated oil 78 is directed via the channel outlet 70 into the riser pipe 86. Through the riser pipe 86, the oil 78 is filled "from above" against the direction of gravity g into the reservoir chamber 58, thus enabling improved settling and defoaming. Page 19

[0089] The claimed invention is not limited to the embodiments described above. Rather, other variants of the invention can also be derived by a person skilled in the art within the scope of the disclosed claims without departing from the subject matter of the claimed invention. In particular, all individual features described in connection with the various embodiments can also be combined in other ways within the scope of the disclosed claims without departing from the subject matter of the claimed invention.

[0090] For example, the compressor 2 can also be designed as a scroll compressor with corresponding nested scroll elements, whereby the design of the partition 62 is analogous. A key difference in a scroll compressor is the design of the oil return from the reservoir chamber 58 to the low-pressure side 44, since no hollow shaft extending through the compressor mechanism is provided. In a scroll compressor, the oil return is integrated, in particular, into the compressor housing 14, specifically into the compressor head housing 12 or into the housing walls.

[0091] Page 20

[0092] Reference symbol list

[0093] 2 compressors / rotary piston compressors

[0094] 4 Drive

[0095] 6 compressor head

[0096] 8 Storage sign

[0097] 10 drive housings

[0098] 12 compressor head housings

[0099] 14 compressor housings

[0100] 16 Engine compartment

[0101] 18 Electric motor

[0102] 20 Housing partition

[0103] 22 Case covers

[0104] 24 Electronic compartment

[0105] 26 Stator

[0106] 28 Rotor

[0107] 30 Drive shaft / hollow shaft

[0108] 32 bore

[0109] 34 Hollow shaft intake

[0110] 36 Hollow shaft outlet

[0111] 38a, 38b Compressor rotor

[0112] 40 compressor chamber

[0113] 40a, 40b Subchapter

[0114] 42 Valve plate

[0115] 44 Low-pressure side

[0116] 46 High-pressure side

[0117] 48 outlet chamber volume

[0118] 50 admission

[0119] 52 Outlet

[0120] 53 Storage sign

[0121] 54 Partition wall assembly

[0122] 56 High-pressure chamber

[0123] 58 Reservoir chamber Page 21

[0124] 60 bore

[0125] 62 Partition wall

[0126] 64 Sealing element

[0127] Channel 66

[0128] 68 oil separators

[0129] 70 Channel Inlet

[0130] 72 Channel outlet

[0131] 74 Admission

[0132] 76 Fluid outlet

[0133] 78 Oil

[0134] 80 Oil outlet

[0135] 82 radial bore

[0136] 84 recording

[0137] 86 Riser pipe

[0138] A Axial direction g Gravity direction

[0139] W angle

Claims

Page 22 Claims 1. Compressor (2) for a motor vehicle, comprising a compressor housing (14) with a low-pressure inlet (50) and a high-pressure outlet (52) as well as with an electric motor drive (4) and with a compressor head (6) coupled thereto via a drive shaft (30), - wherein the compressor head (6) has a compressor chamber (40) for compressing an oil-fluid mixture and a high-pressure chamber (56) coupled thereto for pulsation damping, as well as a reservoir chamber (58) coupled to the drive shaft (30) as a high-pressure oil reservoir, - wherein the high-pressure chamber (56) and the reservoir chamber (58) are separated from each other by a partition (62), - wherein an oil separator (68) is arranged in the partition (62) for separating the oil-fluid mixture, - wherein an inlet (74) of the oil separator (68) is coupled to the high-pressure chamber (56), - wherein a fluid outlet (76) of the oil separator (68) is coupled to the outlet (52), and - wherein an oil outlet (80) of the oil separator (68) is coupled to the reservoir chamber (58).

2. Compressor (2) according to claim 1 , characterized in that the partition (62) and the oil separator (68) are a pre-assembled assembly (54) which is arranged in the compressor housing (14) to form the high pressure chamber (56) and the reservoir chamber (58).

3. Compressor (2) according to claim 1 or 2, characterized in that the partition (62) is designed as a die-cast part.

4. Compressor (2) according to one of claims 1 to 3, characterized in that, Page 23 shows that a riser pipe (86) is arranged between the oil outlet (80) of the oil separator (68) and the reservoir chamber (58).

5. Compressor (2) according to claim 4, characterized in that the riser pipe (86) is integrated into the partition wall (62).

6. Compressor (2) according to claim 4 or 5, characterized in that the riser pipe (86) is oriented parallel to a direction of gravity (g).

7. Compressor (2) according to one of claims 1 to 6, characterized in that the partition (62) has a cylindrical channel (66) in which the oil separator (68) is seated.

8. Compressor (2) according to claim 7, characterized in that the channel (66) is opened axially at the end face to the outlet (52), wherein a first channel inlet opens from the high pressure chamber (56) into the channel (66), wherein a second channel inlet (72) opens from the reservoir chamber (58) into the channel (66), and wherein a channel outlet (70) couples the channel (66) with the reservoir chamber (58).

9. Compressor (2) according to claim 8, characterized in that the second channel inlet (72) and the channel outlet (70) are arranged offset from each other in the direction of gravity (g).

10. Compressor (2) according to claim 9, characterized in that the second channel inlet (72) is arranged in the direction of gravity (g) above the channel outlet (70).

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