Compressor head for a rolling-piston compressor

Abstract

The invention relates to a compressor head (6) for a rolling-piston compressor (2), comprising a compressor-head housing (12) having a compression chamber (40) and a high-pressure chamber (56), wherein the compression chamber (40) is delimited at its ends by a low-pressure-side bearing plate (8) and by a high-pressure-side bearing plate (54), wherein the compression chamber (40) comprises at least two sub-chambers (40a, 40b) which are arranged axially one above the other and each have a partition wall (42) arranged therebetween, wherein an eccentrically driven compressor rotor (38a, 38b) and a spring-loaded separating slide (47) are arranged in each sub-chamber (40a, 40b), wherein the separating slides (47) are pressed radially against the associated compressor rotor (38a, 38b) in order to divide each sub-chamber (40a, 40b) into a suction chamber and a pressure chamber, wherein at least one axial through-opening (88, 94) is introduced into the compressor rotors (38a, 38b) and into the at least one partition wall (42) and forms an inlet channel (92) or an outlet channel (95), wherein an inlet channel (92) couples an inlet opening (88a) of the low-pressure-side bearing plate (8) to the suction chambers of the at least two sub-chambers (40a, 40b), and wherein an outlet channel (95) couples the pressure chamber of the low-pressure-side sub-chamber (40a) to the high-pressure chamber (56).

Description

[0001] Page 1

[0002] 2023 226 WO

[0003] Description

[0004] Compressor head for a rotary piston compressor

[0005] The invention lies in the field of positive displacement machines or rotary compressors and relates to a compressor head for a rotary piston compressor. The invention further relates to a rotary piston compressor for a motor vehicle, which is used in particular for compressing refrigerant in a vehicle air conditioning system.

[0006] Motor vehicles are regularly equipped with air conditioning systems that use a refrigerant circuit to cool and heat the vehicle interior (passenger compartment). In electrically powered or regenerative vehicles, such as electric or 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] In vehicle air conditioning systems, so-called scroll compressors are typically used to compress a refrigerant-oil mixture. The resulting gas-oil mixture is separated, with the separated gas or refrigerant 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 (rotational piston compressors, English: Rolling Piston Compressor) are generally not used for motor vehicle applications, but only for stationary applications, such as cooling systems and heat pumps.

[0010] In rotary compressors, a cylindrical or piston-like compressor rotor rotates completely around an eccentric axis; therefore, rotary 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 (page 3), continuously supplies the shaft bearings with oil. Another characteristic of such rotary piston compressors is that the compressor housing, particularly the oil sump, is under a uniform gas pressure. In other words, the compressor housing is either under high pressure or medium pressure.

[0012] 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 sump. Because the electric motor and electronics are cooled by the suction gas, the compressor housings of refrigerant compressors in motor vehicles do not have a uniform gas pressure inside the housing, but are internally divided into a low-pressure side (inlet side) and a high-pressure side (outlet side).

[0013] In a single-stage compression system with multiple compressor rotors, the compressor chamber is divided into several sub-chambers, each containing a compressor rotor and a separating slide valve. Typically, the sub-chambers are arranged axially one above the other, allowing the valve rotors to be driven by a common drive shaft (hollow shaft).

[0014] In stationary applications, each sub-chamber has an inlet for the refrigerant to be compressed. In other words, an external inlet line is directly connected to the sub-chambers, allowing the refrigerant to flow into the compressor via the sub-chambers. Each sub-chamber also has an outlet opening into the interior of the housing, so that the compressed refrigerant is introduced directly from the sub-chambers into the housing interior, ensuring a uniform gas pressure. The compressed refrigerant from the individual sub-chambers thus mixes within the compressor housing before flowing out of the compressor housing outlet.

[0015] Since the compressor housing of a rotary piston compressor for automotive applications is divided into a high-pressure side and a low-pressure side, single-stage compression using several axially stacked compressor rotors is generally not possible, as the sub-chambers face different directions (page 4).

[0016] They are oriented towards pressure levels. This means that, on the one hand, the simultaneous coupling of the suction chambers of the several sub-chambers to the low-pressure level and, on the other hand, the coupling of the pressure chambers to the high-pressure level is not conventionally possible.

[0017] The invention is based on the objective of providing a particularly suitable compressor head for a rotary piston compressor. In particular, a structurally simple, single-stage compression system with several axially stacked compressor rotors is to be provided. The invention is further based on the objective of providing a particularly suitable rotary piston compressor for a motor vehicle.

[0018] With regard to the compressor head, the problem is solved according to the invention by the features of claim 1, and with regard to the rotary piston compressor by the features of claim 8. Advantageous embodiments and further developments are the subject of the dependent claims. The advantages and embodiments mentioned with regard to the compressor head are also transferable analogously to the rotary piston compressor and vice versa.

[0019] The compressor head according to the invention is designed, suitable, and configured for a rotary piston compressor, in particular for a rotary piston compressor which is internally divided into a high-pressure side and a low-pressure side. The rotary piston compressor is preferably designed for a motor vehicle, i.e., for automotive applications.

[0020] The rotary compressor has a compressor housing with a low-pressure or suction-side inlet and a high-pressure or discharge-side outlet. An electric motor is arranged in the compressor housing, which drives a (rotary piston) compressor mechanism in the compressor head via a drive shaft. During operation, the rotary compressor pumps or compresses a gaseous fluid or medium, for example, a refrigerant, in particular R744. Page 5

[0021] In this and the following, "axial" or "axial direction" refers specifically to a direction parallel (coaxial) to the axis of rotation of the drive, i.e., parallel to the drive shaft. Similarly, in this and the following, "radial" or "radial direction" refers specifically to a direction oriented perpendicular (transverse) to the axis of rotation of the drive, along a radius of the stator or electric motor. In this and the following, "tangential" or "tangential direction" refers specifically to a direction along the circumference of the stator or electric motor (circumferential direction, azimuthal direction), i.e., a direction perpendicular to both the axial and radial directions.

[0022] The compressor head has a compressor head housing, which, when installed, is part of the rotary compressor housing. The compressor head, or rotary compressor, is designed modularly, allowing different compressor heads (compressor modules) to be coupled with different drives (drive modules). However, the compressor head can also be an integral part of the rotary compressor; in particular, the compressor head housing can be a single, monolithic section of the compressor housing.

[0023] The compressor head housing comprises a compressor chamber containing the compressor mechanism for compressing the fluid. The compressor housing also includes a high-pressure chamber. During compressor operation, this high-pressure chamber forms the high-pressure side of the rotary piston compressor. In other words, during compressor operation, the compressed fluid is conveyed from the compressor chamber to the high-pressure chamber. Preferably, the outlet of the rotary piston compressor is integrally formed with the compressor head housing and coupled to the high-pressure chamber.

[0024] The compressor chamber is bounded at its end face by a low-pressure end shield, which, in the installed state, faces the low-pressure side of the compressor housing containing the drive, and by a high-pressure end shield, which is located adjacent to the high-pressure chamber. In other words, the low-pressure end shield forms an interface to the drive (page 6) or motor compartment of the compressor housing, while the high-pressure end shield forms a partition to the high-pressure chamber. The end shields preferably each have a shaft bearing for rotatable or rotating support of the drive shaft. The shaft bearings are, for example, designed as plain bearings. The end shields are fixed to or within the compressor head housing.

[0025] The compressor chamber has at least two axially arranged sub-chambers, with a plate-shaped or disc-shaped partition between each pair of adjacent sub-chambers. The partition is fixed to the compressor head housing. Each sub-chamber performs one (compressor) stroke during the compression of the fluid to be compressed.

[0026] The end-faced sub-chambers are each bounded by a bearing plate and a partition, with sub-chambers located between the end faces being flanked by two partitions. Hereinafter, the sub-chamber facing the low-pressure-side bearing plate is also referred to as the low-pressure-side sub-chamber, the sub-chamber facing the high-pressure-side bearing plate is also referred to as the high-pressure-side sub-chamber, and the sub-chambers arranged in between are also referred to as intermediate chambers.

[0027] The following is a simplified description—without limiting generality—of a compressor chamber with exactly two sub-chambers: a low-pressure sub-chamber and a high-pressure sub-chamber, separated by a common partition. However, the following explanations can also be applied analogously to compressor chambers with any number of intermediate chambers. In a compressor chamber with three or more sub-chambers or strokes, each sub-chamber or stroke has its own discharge valve, valve strainer, and small discharge chamber, which are, for example, integrated into the respective partition. Page 7

[0028] The compressor mechanism is arranged in the compressor chamber, with each sub-chamber containing an eccentrically driven or driveable compressor rotor. The compressor rotors are axially aligned with each other and, in the installed state, are preferably driven together by the drive shaft (motor shaft) of the drive unit. For this purpose, the compressor rotors are joined to the drive shaft, for example, by means of a loose fit. The drive or motor shaft is, in particular, designed as a hollow shaft.

[0029] In each sub-chamber, a spring-loaded separating slide is arranged to separate the respective sub-chamber into a suction chamber and a pressure chamber, which is pressed radially against the respective compressor rotor by means of a spring element, in particular by means of a compression or helical spring.

[0030] The compressed medium is expelled through a respective (axial) (chamber) outlet of the pressure chamber. The outlet may include an outlet valve, for example a spring-loaded valve (flutter valve), which opens automatically when a sufficiently high pressure is present in the respective pressure chamber.

[0031] The compressor head according to the invention is designed for single-stage compression of the fluid or refrigerant. For this purpose, according to the invention, at least one axial through-opening is provided in each compressor rotor and in each partition, serving as an inlet channel and / or an outlet channel. In other words, the at least one axial through-opening extends through the axially stacked compressor rotors and partitions, serving as either an inlet channel or an outlet channel. The through-opening is, for example, configured as axially aligned bores in the compressor rotors and partitions.

[0032] An inlet channel connects an axial inlet opening of the low-pressure side bearing shield to the suction chambers of at least two sub-chambers. The compressor chamber, or the low-pressure side bearing shield, thus has only one inlet opening as a suction port, through which uncompressed fluid flows via the inlet channel into each of the sub-chambers (see page 8).

[0033] The suction gas flows into the suction chambers. This allows all sub-chambers (internally) to be supplied with suction gas simultaneously.

[0034] An outlet channel connects the pressure chamber of the low-pressure subchamber to the high-pressure chamber. This allows the compressed fluid in the compressor housing to be directed from the pressure chamber of the low-pressure subchamber to the high-pressure chamber. This ensures that the compressed fluid from each subchamber is either directed into or expelled from the high-pressure chamber.

[0035] Since the compressor rotors are connected to the drive shaft and the baffles are fixed within the compressor housing, the compressor rotors move or rotate relative to the baffles during compressor operation. The axial through-opening, or inlet or outlet channel, is therefore only formed or opened for specific rotation angles (or ranges) of the drive shaft during the compression cycle. This ensures that there is no permanent connection to the low-pressure or high-pressure side, and that the separation between the low-pressure and high-pressure sides is maintained during compressor operation.

[0036] The inlet or outlet channel enables a particularly suitable compressor head for single-stage compression with multiple compressor rotors, especially for applications with rotary piston compressors featuring an internal high-pressure / low-pressure separation. Since the connection between the suction chambers and the low-pressure side, or vice versa, is achieved via a channel integrated into the compressor mechanism, a structurally simple, component-reduced, and space-saving design of the compressor head is possible.

[0037] In a preferred embodiment, two axial through-openings are provided in each compressor rotor and in each partition, one through-opening being configured as an inlet channel and the other as an outlet channel. This results in a compressor head particularly suitable for single-stage compression (page 9), in which the suction chambers of the compressor chamber can be supplied with suction gas jointly via the inlet channel, and in which the compressed fluid is expelled internally from the housing or compressor chamber to the high-pressure chamber.

[0038] In an advantageous further development, a first (axial) outlet opening is incorporated into the high-pressure-side bearing shield as an outflow opening for the pressure chamber of the high-pressure-side sub-chamber. In other words, the pressure chamber outlet of the high-pressure-side sub-chamber is directly coupled to the high-pressure chamber via an (axial) outlet opening in the high-pressure-side bearing shield. The compressed fluid is conveyed directly from the pressure chamber of the high-pressure-side sub-chamber into the high-pressure chamber, while the compressed fluid from the pressure chamber of the low-pressure-side sub-chamber is conveyed into the high-pressure chamber via the outlet channel.

[0039] An additional aspect of the invention provides that the low-pressure side bearing shield has an outlet chamber which is coupled to the pressure chamber of the low-pressure side subchamber. In other words, an (axial) pressure chamber outlet of the low-pressure side subchamber opens into the outlet chamber of the low-pressure side bearing shield. The low-pressure side bearing shield thus has a receiving volume for the fluid compressed in the low-pressure side subchamber. This means that the inlet (suction port) and the outlet of the low-pressure side subchamber are arranged on the same side of the chamber and are both incorporated into the low-pressure side bearing shield.

[0040] In a particularly compact design, the outlet chamber is formed as a recess in the low-pressure side, i.e., in a flat surface facing away from the compressor chamber, of the low-pressure end shield. The recess is sealed by a cover plate, ensuring a fluid- and pressure-tight seal. The recess and the cover plate together constitute the outlet chamber volume. The low-pressure end shield is, for example, a die-cast part, allowing for particularly simple manufacturing of the outlet chamber thanks to the recess and the cover plate. A steel or cast steel material is used for the low-pressure end shield, which is typically manufactured using a casting process.

[0041] In a preferred embodiment, the outlet chamber is coupled to the high-pressure chamber of the compressor housing via the outlet channel. In a suitable design, the outlet chamber and the high-pressure side bearing shield each have an (axial) outlet opening which is coupled to the outlet channel during compressor operation. This means that the outlet chamber has a (second) outlet opening for coupling to the outlet channel, and that the high-pressure side bearing shield, in addition to the (first) outlet opening of the high-pressure side pressure chamber, has a further (third) outlet opening as an outflow opening for the outlet channel.

[0042] The compressed fluid is thus expelled directly from the high-pressure chamber into the high-pressure chamber via the first outlet opening. The low-pressure chamber expels the compressed fluid into the outlet chamber, from where it is introduced into the high-pressure chamber via the second and third outlet openings and the outlet channel located between them.

[0043] The rotary piston 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 rotary piston 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 compressor head as described above. During operation, the rotary piston compressor conveys or compresses a refrigerant, in particular R744. This results in a particularly suitable rotary piston compressor.

[0044] The drive preferably 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 rotatably or rotatably relative to it (page 11). 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 motor shaft is rotatably or rotatably mounted in the compressor housing, in particular in the bearing shields of the compressor head, by means of shaft bearings. Preferably, the motor shaft is supported by plain bearings.

[0045] 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.

[0046] The motor shaft is driven by the compressor head, which, during compressor operation, draws in the refrigerant from the low-pressure side, compresses it, and conveys it via a high-pressure side through the outlet of the compressor housing.

[0047] The motor shaft, which in its installed state is arranged particularly horizontally or lying down, is designed as a hollow shaft and will hereinafter also be referred to as such. The hollow shaft is open axially at both ends, meaning that the hollow shaft 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 arranged at the level of the shaft bearings.

[0048] The compressor head comprises a compressor chamber for compressing an oil-fluid mixture and a coupled high-pressure chamber for pulsation damping, as well as preferably a reservoir chamber coupled to the hollow shaft as a high-pressure oil reservoir. The compressed medium is pulsated from the compressor chamber into the high-pressure chamber. 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).

[0049] 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, which also serves to reduce leakage in the compressor chamber. 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.

[0050] In particular, a mixture of refrigerant (gas) and special oils (e.g., PAG or POE) is used. The oil is then distributed throughout the system and within the compressor by the flow conditions. 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 oil's primary purpose is to lubricate the compressor chamber and reduce friction between stressed compressor components, such as the shaft bearing and the separator.

[0051] During operation of the refrigerant drive, or rotary piston 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 piston 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 the inlet opening of the low-pressure side end shield to the compressor head. The compressor mechanism compresses the refrigerant-oil mixture, with the oil providing lubrication for at least one of the components. (Page 13)

[0052] The oil serves to reduce friction in the compressor rotor and consequently increase efficiency. It also acts as a seal to prevent uncontrolled leakage of refrigerant from the pressure chambers into the suction chamber.

[0053] So-called 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 under pressure through the hollow shaft to relevant friction points of the rotary piston compressor.

[0054] Exemplary embodiments of the invention are explained in more detail below with reference to a drawing. The drawing shows:

[0055] Fig. 1 shows a schematic representation of a rotary piston compressor, Fig. 2 shows a perspective view of the rotary piston compressor, Fig. 3 shows a sectional view of the rotary piston compressor with a compressor head, Fig. 4 shows a partial sectional view of the rotary piston compressor with an inlet channel.

[0056] Fig. 5 shows a top view of a low-pressure side bearing shield of the rotary piston compressor.

[0057] Fig. 6 shows a section of the rotary piston compressor with an outlet port, and

[0058] Fig. 7 shows a top view of a high-pressure side bearing shield of the rotary piston compressor.

[0059] Corresponding parts and sizes are always marked with the same reference symbols in all figures. Page 14

[0060] Figure 1 shows a schematic and highly simplified representation of a rotary piston compressor 2 according to the invention, which is installed, for example, as a refrigerant compressor in a refrigerant circuit (not shown in detail) of an air conditioning system in a motor vehicle. The refrigerant used is, for example, R744.

[0061] 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 low-pressure side 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.

[0062] 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 together form a compressor housing 14 of the rotary piston compressor 2. The compressor head 6 is connected (bolted) to the drive 4, for example, by means of circumferentially distributed flange connections 15 (Fig. 2) extending in an axial direction A of the rotary piston compressor 2. The flange connections 15 or fastening bolts extend through the bearing shield 8.

[0063] 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. Page 15

[0064] The electric motor 18, which is primarily 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 rigidly connected to a drive or motor shaft 30. The motor shaft 30 is designed as a hollow shaft and will be referred to as such below.

[0065] 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 is shown as an example.

[0066] 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 37 (Fig. 4), not shown in detail. These bores 37 extend radially through the hollow shaft 30 from the bore 32 and are open towards the outer circumference of the hollow shaft 30.

[0067] The compressor head 6 has a (rotary piston) compressor mechanism. The compressor mechanism is designed for single-stage compression with several compressor rotors 38a, 38b, wherein, in the illustrated embodiment, 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. Page 16

[0068] A housing-fixed partition 42 is arranged between the compressor rotors 38a, 38b, which divides the compressor chamber 40 into a first (low-pressure side) sub-chamber 40a facing a low-pressure side 44 and a second (high-pressure side) sub-chamber 40b facing a high-pressure side 46.

[0069] In each of the sub-chambers 40a, 40b, one of the compressor rotors 38a, 38b and a spring-loaded separating slide 47 (Fig. 3) are arranged to separate the sub-chambers 40a, 40b into a suction chamber and a pressure chamber. The separating slides 47 are pressed radially against the respective compressor rotor 38a, 38b by means of a spring element 48 (Fig. 3), in particular by means of a compression or helical spring.

[0070] The rotary piston compressor 2 has a (refrigerant) inlet or (cold medium) supply 50 for connection to the refrigerant circuit and a (refrigerant) outlet 52. The inlet 50 is formed in an area of ​​the drive housing 10 facing the electronics compartment 24. The outlet 52 is formed on the base of a compressor head housing 12. 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.

[0071] 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 53a, 53b, 53c (Fig. 3). The shaft bearings 53a, 53b, 53c are each preferably designed as plain bearings. The shaft bearing 53a 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 shaft bearing 53b is received in the bearing shield 8 that delimits the partial chamber 38a, with the shaft bearing 53c being arranged in a bearing shield 54 that separates the partial chamber 40b from an outlet chamber volume. Page 17

[0072] As shown in more detail in Fig. 3, for example, a partition 55 is inserted into the compressor head housing 12, which divides the outlet chamber volume, or the high-pressure side 46, of the compressor head housing 12 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. The bore 60 is located at the bottom of the reservoir chamber 58 with respect to the direction of gravity g.

[0073] A sealing element 62 is provided on the outer circumference of the partition wall 55, which seals the partition wall 55 - and thus the high pressure chamber 56 and the reservoir chamber 58 - radially against the inner walls of the compressor head housing 12.

[0074] A channel 64 is incorporated or molded into the partition wall 55, which is primarily a die-cast part, and an oil separator 66 is arranged within it. The high-pressure chamber 56 is connected to the outlet of the compressor chamber 40 and to the channel 64. The channel 64 is connected to the high-pressure chamber 56, to the outlet 52, and to the reservoir chamber 58.

[0075] 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 into the channel 64 and is introduced, for example, radially and / or tangentially into the oil separator 66. The oil separator 66 is designed, in particular, as a cyclone separator and separates the flowing oil-refrigerant mixture into a refrigerant gas stream, which is discharged to the outlet 52, and into droplet-shaped oil, which is separated into the channel 64.

[0076] The separated oil collects by gravity at the bottom of channel 64. A borehole is drilled in this bottom area, through which the oil flows into reservoir chamber 58. The oil is collected and settled in reservoir chamber 58, which is designed as a (high-pressure) oil reservoir, with gaseous components being removed. (Page 18)

[0077] Refrigerant dissolved in the separated oil escapes from the oil as bubbles (defoaming).

[0078] For example, a throttling element 68 can be arranged in the bore 60, which reduces the (static) high pressure of the oil to the low pressure level of the low pressure side 44.

[0079] A cover plate 70 is mounted on the high-pressure side bearing shield 54, separating the high-shaft inlet 34 from the high-pressure chamber 56. A radial bore 72 and a receptacle 74 are provided in the cover plate 70, which are coupled to the bore 60 and the throttle element 68, respectively.

[0080] The rotary piston compressor 2 is shown in more detail in Figures 2 to 7, with the construction of the compressor head 6 being explained in more detail below.

[0081] The compressor chamber 40 is axially bounded within the compressor housing 12 by the bearing shields 8 and 54. Bearing shield 8 is hereinafter also referred to as the low-pressure side bearing shield 8, since the flat surface facing away from the compressor chamber 40 faces the low-pressure side 44 or the motor compartment 16. Similarly, bearing shield 54 is hereinafter also referred to as the high-pressure side bearing shield 54, since the flat surface facing away from the compressor chamber 40 faces the high-pressure side 56 or the high-pressure chamber 56.

[0082] The cover plate 70 is screwed to the high-pressure end face of the bearing shield 54 by means of six axial fastening screws 76 (Fig. 7). A cover plate 78 is screwed to the low-pressure end face of the bearing shield 8 by means of six axial fastening screws 80 (Fig. 5).

[0083] The cover plate 78 is sealed axially against the end face of the bearing shield 8 by means of a first sealing element 82 and radially against a collar of the bearing shield 8 forming the shaft bearing 53b by means of a second sealing element 84. Page 19

[0084] In this embodiment, the shaft-fixed rotor 28 is axially flanked on both sides by a counterweight 86, which reduces the imbalance of the eccentrically driven compressor rotors 38a, 38b on the hollow shaft 30.

[0085] As can be seen, for example, in Fig. 4, the compressor head 6 has an axial through-opening 88. This through-opening 88 is formed by an axial through-opening 88a in the cover plate 78, an axial through-opening 88b in the bearing shield 8, an axial through-opening 88c in the compressor rotor 38a, an axial through-opening 88d in the partition 42, and an axial through-opening 88e in the compressor rotor 38b. Extending from the through-openings 88c and 88e of the compressor rotors 38a and 38b are two radial through-openings 90a and 90b, which open into the suction chamber of the respective sub-chamber 40a and 40b. The through-openings 88a to 88e, 90a, and 90b are, for example, designed as bores.

[0086] In the rotational position of the hollow shaft 30 shown in Fig. 4, the through-openings 88a to 88e are arranged axially aligned with each other and form the continuous through-opening 88, which together with the radial through-openings 90a, 90b forms an inlet channel 92 of the compressor chamber 40.

[0087] As can be seen particularly in Fig. 6, the compressor head 6 has a further axial through-opening 94. The through-opening 94 is formed by an axial through-opening 94a of the bearing shield 8, an axial through-opening 94b of the compressor rotor 38a, an axial through-opening 94c of the partition 42, an axial through-opening 94d of the compressor rotor 38b, an axial through-opening 94e of the bearing shield 54, and an axial through-opening 94f of the cover plate 70. The through-openings 94a to 94f are, for example, designed as bores.

[0088] In the rotational position of the hollow shaft 30 shown in Fig. 6, the through-openings 94a to 94f are arranged axially aligned with each other and form the through-opening 94, which connects an outlet chamber 96 of the bearing shield 8 with the high-pressure chamber 56. In particular, the through-opening 94a of the bearing shield 8 opens into the outlet chamber 96, so that the through-opening 94a forms an axial outlet opening of the outlet chamber 96 into the outlet channel 95. Correspondingly, the through-opening 94e of the bearing shield 54 or the through-opening 94f of the cover plate 70 forms an axial outlet opening of the outlet channel 95 into the high-pressure chamber 56.

[0089] The outlet chamber 96 is formed by a recess on the low-pressure side face of the bearing shield 8 and by the cover plate 78 covering or closing it.

[0090] Subchamber 40a, in particular its pressure chamber, has an axial outlet opening as an outlet to outlet chamber 96. Subchamber 40b, in particular its pressure chamber, has an axial outlet opening 98 as an outlet to high-pressure chamber 56.

[0091] 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.

[0092] 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.

[0093] The refrigerant-oil mixture is compressed in a single stage in the compressor chamber 40, and the compressed refrigerant-oil mixture is introduced into the high-pressure chamber 56 or into the high-pressure side 46 of the compressor housing 14. Page 21

[0094] For this purpose, the refrigerant-oil mixture is drawn into the suction chambers of the two sub-chambers 40a and 40b through the through-opening 88a and the inlet channel 92 in the shaft position shown in Fig. 4. In other words, the inlet channel 92 couples the low-pressure side 44 with the suction chambers of the sub-chambers 40a and 40b, which are distributed axially along the hollow shaft 30. The compressor chamber 40, or rather the low-pressure side bearing shield 8, thus has only one inlet opening (through-opening 88a) as a suction port, through which the uncompressed refrigerant-oil mixture flows into each of the sub-chambers 40a and 40b, or suction chambers. As a result, during compressor operation in this rotational position of the hollow shaft 30, all sub-chambers 40a and 40b are simultaneously supplied (internally) with suction gas.

[0095] With a further rotation of the hollow shaft 30, the compressor rotors 38a, 38b – and thus the through-openings 88c and 88e – are moved relative to the housing-fixed bearing shields 8, 54 and the partition 42 – and thus the through-openings 88a, 88b, 88d – so that the through-opening 88 or the inlet channel 92 is closed or blocked. This separates the suction chambers of the sub-chambers 40a, 40b from the low-pressure side 44 and seals them off from the pressure chambers.

[0096] As the hollow shaft 30 rotates further, the refrigerant-oil mixture enclosed in the sub-chambers 40a and 40b is successively compressed by means of the separating slides 47 until the shaft position shown in Fig. 6 is reached. The oil in the refrigerant-oil mixture also serves to lubricate the two separating slides 47, thus reducing friction and consequently increasing efficiency. The oil also seals the suction and pressure chambers separated by the separating slides 47, preventing uncontrolled escape through the separating slides 47.

[0097] In the wave configuration shown in Fig. 6, the compressed refrigerant-oil mixture is expelled from the pressure chambers. The refrigerant-oil mixture from subchamber 40b is expelled directly into the high-pressure chamber 56 via the outlet opening 98. The refrigerant-oil mixture from subchamber 40a is expelled axially into the outlet chamber 96 via the outlet opening (not shown in detail on page 22), with the expelled refrigerant-oil mixture flowing into the high-pressure chamber 56 via the outlet chamber 96 and the outlet channel 95. In other words, the refrigerant-oil mixture from subchamber 40b is conveyed directly into the high-pressure chamber 56, while the refrigerant-oil mixture from subchamber 40a is first conveyed into the outlet chamber 96 and from there via the outlet channel 95 into the high-pressure chamber 56.

[0098] This causes the refrigerant-oil mixture to be compressed in a single stage using both sub-chambers 40a and 40b and introduced into the high-pressure chamber 56. 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 64. The oil is separated from the refrigerant by the oil separator 66. The refrigerant is discharged via the outlet 52, with the oil 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.

[0099] During compressor operation, the reservoir chamber 58 is at least partially filled with the separated oil. Due to the pressure difference between the high-pressure side 46 and the low-pressure side 44, the oil flows through the bore 60 and is expanded to the pressure level of the low-pressure side 44 by means of the throttling element 68.

[0100] The oil, operating at low pressure, is directed from bore 60 or throttle element 68 via radial bore 72 into the receptacle 74 located between compressor chamber 40 and 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, 72, and receptacle 74. The cover plate 70 or receptacle 74 is radially sealed from the outside against an axial collar of the bearing shield 54, which forms the shaft bearing 53c, by means of a sealing element 71. Page 23

[0101] The oil flows axially through bore 32 to the hollow shaft outlet 36. The radial bores are located at the level of the shaft bearings 53b and 53c, so that centrifugal force forces the oil out of bore 32 through the radial bores 37, thus lubricating the shaft bearings 53b and 53c. Excess oil exits at the hollow shaft outlet 36 in the area of ​​shaft bearing 53a into the engine compartment 16 or the low-pressure side 46, and is mixed with the refrigerant again.

[0102] 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.

[0103] Page 24

[0104] Reference symbol list

[0105] Rotary piston compressor

[0106] 4 Drive

[0107] 6 compressor head

[0108] 8 Storage sign

[0109] 10 drive housings

[0110] 12 compressor head housings

[0111] 14 compressor housings

[0112] 15 Flange connection

[0113] 16 Engine compartment

[0114] 18 Electric motor

[0115] 20 Housing partition

[0116] 22 Case covers

[0117] 24 Electronic compartment

[0118] 26 Stator

[0119] 28 Rotor

[0120] 30 Motor shaft / hollow shaft

[0121] 32 bore

[0122] 34 Hollow shaft intake

[0123] 36 Hollow shaft outlet

[0124] 37 bore

[0125] 38a, 38b Compressor rotor

[0126] 40 compressor chamber

[0127] 40a, 40b Subchapter

[0128] 42 Partition wall

[0129] 44 Low-pressure side

[0130] 46 High-pressure side

[0131] 47 separating slides

[0132] 48 spring element

[0133] 50 admission

[0134] 52 Outlet

[0135] 53a, 53b, 53c Shaft bearings Page 25

[0136] 54 Storage sign

[0137] 55 Partition wall

[0138] High-pressure chamber

[0139] 58 Reservoir chamber

[0140] 60 bore

[0141] 62 Sealing element

[0142] 64-channel

[0143] 66 oil separators

[0144] 68 Throttle element

[0145] 70 Cover plate

[0146] 72 radial bore

[0147] 74 recording

[0148] 76 Mounting screw

[0149] 78 Cover plate

[0150] 80 fastening screw

[0151] 82 Sealing element

[0152] 84 Sealing element

[0153] 86 Counterweight

[0154] 88, 88a...88e Through opening

[0155] 90a, 90b Through opening

[0156] 92 Inlet channel

[0157] 94, 94a...94f Through opening

[0158] 95 Outlet channel

[0159] 96 Outlet chamber

[0160] 98 Outlet opening

[0161] A Axial direction g Gravity direction

Claims

Page 26 Claims 1. Compressor head (6) for a rotary piston compressor (2), comprising a compressor head housing (12) with a compressor chamber (40) and with a high-pressure chamber (56), - wherein the compressor chamber (40) is bounded at the front by a low-pressure side bearing shield (8) and by a high-pressure side bearing shield (54), - wherein the compressor chamber (40) has at least two axially arranged sub-chambers (40a, 40b) with a partition wall (42) arranged between them, - wherein an eccentrically driven compressor rotor (38a, 38b) and a spring-loaded separating slide (47) are arranged in each sub-chamber (40a, 40b), - wherein the separating slides (47) are pressed radially against the respective compressor rotor (38a, 38b) to separate the sub-chambers (40a, 40b) into a suction chamber and a pressure chamber, - wherein at least one axial through-opening (88, 94) is provided in the compressor rotors (38a, 38b) and in the at least one partition (42) as an inlet channel (92) or as an outlet channel (95), - wherein an inlet channel (92) couples an inlet opening (88a) of the low-pressure side bearing shield (8) with the suction chambers of the at least two sub-chambers (40a, 40b), and - wherein an outlet channel (95) couples the pressure chamber of the low-pressure side sub-chamber (40a) with the high-pressure chamber (56).

2. Compressor head (6) according to claim 1 , characterized in that two axial through-openings (88, 94) are provided in the compressor rotors (38a, 38b) and in the at least one partition (42), one being designed as an inlet channel (92) and the other as an outlet channel (95). Page 27 3. Compressor head (6) according to claim 1 or 2, characterized in that a first outlet opening (98) is provided in the high-pressure side bearing shield (54), which couples the pressure chamber of the high-pressure side sub-chamber (40b) with a high-pressure chamber (56) of the compressor head housing (12).

4. Compressor head (6) according to one of claims 1 to 3, characterized in that the low-pressure side bearing shield (8) has an outlet chamber (96) which is coupled to the pressure chamber of the low-pressure side sub-chamber (40a).

5. Compressor head (6) according to claim 4, characterized in that the outlet chamber (96) is provided as a recess in the low-pressure side of the bearing shield (8) and is closed by means of a cover plate (78).

6. Compressor head (6) according to claim 4 or 5, characterized in that the outlet chamber (96) is coupled to the high pressure chamber (56) of the compressor housing (12) via the outlet channel (95).

7. Compressor head (6) according to claim 6, characterized in that, - that the outlet chamber (96) has a second outlet opening (94a) for coupling with the outlet channel (95), and - that the high-pressure side bearing shield (54) has a third outlet opening (94e) as an outflow opening from the outlet channel (95) into the high-pressure chamber (56). Page 28 8. Rotary piston compressor (2) for a motor vehicle, comprising a compressor head (6) according to one of claims 1 to 7.

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