Electric compressor for compressing a gas, especially for a motor vehicle

Abstract

Electric compressor (1) for compressing a gas, in particular for a motor vehicle, comprising - a control unit (2) with several capacitors (22), - an electric motor (3) with a substantially ring-shaped stator (9), wherein the electric motor (3) can be controlled by means of the control unit (2) and wherein the stator (9) has several axially extending recesses (11) spaced evenly apart along its outer circumference (10), - a compressor wheel (4), wherein the compressor wheel (4) can be driven by means of the electric motor (3), and - a housing (6), wherein the housing (6) at least partially encloses the electric motor (3), wherein the housing (6) is manufactured by means of a potting process such that a cooling structure (7) with several cooling channels, namely cooling channels (8) corresponding to the number of recesses (11), is formed integrally with the housing (6), in particular within the housing (6), wherein the cooling structure (7) is formed at least partially around the outer circumference (10) of the stator (9), so that the electric motor (3) and the control unit (2) are cooled, wherein the cooling channels (8) extend axially along the recesses (11) of the stator (9), wherein the stator (9) has, in each case in the area between the recesses (11), on a side facing away from the control unit (2), radially extending lugs (26) over a partial region of the outer circumference (10), which are designed such thatthat each capacitor (22) of the control unit (2) can extend axially along the stator (9) in the area between two recesses (11) up to the lugs (26).

Description

Field of the invention

[0001] The present invention relates to an electric compressor for compressing a gas, in particular for a motor vehicle State of the art

[0002] In general, compressors in the automotive sector are particularly important in connection with the desire to increase the performance and efficiency of a motor vehicle's internal combustion engine.

[0003] One of the most well-known forms of a compressor is the exhaust gas turbocharger. The exhaust gas turbocharger serves to ensure a sufficient amount of combustion air in the cylinders of the internal combustion engine by compressing ambient air or an ambient air / exhaust gas mixture and thus supplying the cylinders with this combustion air at excess pressure.

[0004] Typically, an exhaust gas turbocharger consists of an exhaust turbine and a compressor wheel, with the two wheels mounted on a common shaft. The exhaust turbine converts the heat and kinetic energy of the internal combustion engine's exhaust gas into rotational energy. This rotational energy is transferred to the compressor wheel via the common shaft. Ambient air or a mixture of ambient air and exhaust gas is drawn in and compressed via the compressor wheel. This allows a higher working pressure to be achieved at the same temperature in the internal combustion engine's cylinder.

[0005] As long as sufficient exhaust gas flows from the internal combustion engine to drive the exhaust turbine, the engine speed is sufficient to create excess pressure on the intake side. However, when accelerating, for example, the turbo may react with a delay (even) at higher engine speeds – this condition is commonly known as "turbo lag."

[0006] There are many approaches to counteracting the development of turbo lag. For example, the inertia of the exhaust turbine can be reduced by making it smaller. While this reduces the turbo's efficiency, it allows the exhaust turbine to be driven by a weak exhaust flow.

[0007] Another approach in this context is the use of an (additional) electrically driven compressor (electric compressor), which operates independently of the exhaust gas flow from the internal combustion engine. An electrically driven compressor typically also has a compressor wheel, but can be driven by an electric motor.

[0008] Publication WO 99 / 10654 A1, for example, describes an electrically driven compressor in which the compressor and the electric drive motor are arranged coaxially on a shaft and housed in a common housing. The primary objective is to provide a compressor that is as compact as possible.

[0009] When planning an electric compressor, the main focus is on a component-optimized and compact design of the entire compressor.

[0010] In high-speed motor components, such as an electric compressor, high speeds result in large induced electrical voltages. These high voltages and the applied currents generate heat during operation, which must be dissipated by external cooling to ensure continuous operation at specified power levels.

[0011] The publication DE 10 2008 003 784 A1, for example, describes a device and a method for the full encapsulation of stators of electric motors with internal rotors. In the described method, the stator is set in rotation during and / or after the introduction of flowable encapsulating compound, whereby the encapsulating compound is introduced radially from the inside to the outside, so that the encapsulating compound is filled with the cavity and distributed evenly during the rotation process. Due to the centrifugal forces that the rotation exerts on the encapsulating compound, it is forced into all cavities and winding phases of the stator. The stator is thereby fully encapsulated. By fully encapsulating the stator and in particular the stator windings, the electric motor can be made very compact and, depending on the full encapsulation material used, the heat transfer from the stator or the windings can be improved.Stator winding to the housing can be positively influenced - the housing represents the temperature sink.

[0012] Document DE 10 2008 022 516 A1 describes a stator assembly for use in a fluid-cooled engine. The stator assembly comprises a main body portion arranged around a rotor assembly coupled to a driven element, such as a compressor impeller. A cooling jacket is arranged around the main body portion of the stator. The cooling jacket includes at least one conduit suitable for receiving coolant.

[0013] The document DE 10 2006 029 803 A1 discloses a method for producing an electrical machine and an electrical machine produced according to this method. Summary of the invention

[0014] One object of the invention is to provide an electric compressor which can be operated with high performance while having a compact design. The object is achieved by an electric compressor for compressing a gas, in particular for a motor vehicle, comprising a control unit with a plurality of capacitors, an electric motor with a substantially annular stator, wherein the electric motor is controllable by means of the control unit and wherein the stator has a plurality of axially extending recesses evenly spaced along its outer circumference, a compressor wheel, wherein the compressor wheel is drivable by means of the electric motor, and a housing (6), wherein the housing at least partially encloses the electric motor, wherein the housing is manufactured by means of a casting process such that a cooling structure with a plurality of cooling channels, namely a number of cooling channels corresponding to the number of recesses, is formed in one piece with the housing, in particular in the housing, wherein the cooling structure is formed at least partially around the outer circumference of the stator,so that cooling of the electric motor and the control unit takes place, wherein the cooling channels extend axially along the recesses of the stator, wherein the stator has, in the region between the recesses on a side facing away from the control unit, lugs extending radially over a partial region of the outer circumference, which are designed such that a capacitor of the control unit can extend axially along the stator in the region between two recesses up to the lugs.

[0015] The electric compressor according to the invention comprises a control unit with several capacitors, an electric motor with a stator, a compressor wheel and a housing.

[0016] According to the invention, the electric motor can be controlled by means of the control unit and serves to selectively drive the compressor wheel.

[0017] The control unit represents the power and signal electronics for the electric motor and preferably comprises a circuit board on which various electronic components, such as capacitors, semiconductor chips, etc., can be arranged.

[0018] However, the control unit can also be understood as a plug, in which case the circuit board including the various electronic components arranged on it are designed as an external control module.

[0019] The compressor wheel and the electric motor are preferably arranged coaxially on a common shaft, wherein the shaft is formed along a central axis of rotation of the electric motor.

[0020] The electric motor has a rotor and a stator with at least one stator winding, but usually several stator windings.

[0021] The control unit is preferably arranged coaxially to the electric motor along the central axis of rotation of the electric motor and is electrically connected to the electric motor, more precisely to the stator windings of the stator of the electric motor, via at least one connecting element.

[0022] According to the present invention, the electric motor serves to drive the compressor wheel.

[0023] The rotor of the electric motor is preferably arranged on the shaft in a rotationally fixed manner and / or is formed in one piece with the shaft.

[0024] The compressor wheel is preferably arranged on the shaft in a rotationally fixed manner and / or is formed in one piece with the shaft.

[0025] The rotational energy generated by the electric motor is transferred to the compressor wheel via the common shaft.

[0026] The housing of the electric compressor according to the invention serves to accommodate at least partially the electric motor, in particular the stator of the electric motor.

[0027] According to the invention, the cooling structure has several cooling channels. This allows for simple, demand-based cooling of the electric motor and the control unit.

[0028] Furthermore, according to the invention, the cooling structure is formed at least partially around the outer circumference of the stator of the electric motor. The stator has at least one stator winding, preferably several stator windings. By at least partially forming the cooling structure around the outer circumference of the stator, the electrically loaded stator winding, in particular, can be efficiently cooled.

[0029] According to the present invention, the stator is substantially annular and has a plurality of axially extending recesses, evenly spaced along its outer circumference.

[0030] The direction “axial” refers to a direction along the central axis of rotation of the electric motor.

[0031] It is advantageous if the cooling structure has a number of cooling channels corresponding to the number of recesses in the stator. However, more or fewer cooling channels can also be installed around the stator.

[0032] According to the invention, the cooling channels extend axially along the recesses of the stator. The design of the stator recesses and the arrangement of a cooling channel of the cooling structure in each recess result in an extremely compact design with efficient cooling, particularly of the stator.

[0033] According to the present invention, the stator has, in the region between the recesses on a side facing away from the control unit, lugs extending radially over a partial region of the outer circumference, which are designed such that a capacitor of the control unit can extend axially along the stator up to the lugs in the region between two recesses.

[0034] The direction “radial” refers to a direction normal to the central axis of rotation of the electric motor.

[0035] Preferably, the housing of the electric compressor according to the invention serves at least partially to accommodate the control unit.

[0036] According to the invention, the housing is produced by a casting process, wherein a cooling structure is formed integrally with the housing, in particular in the housing.

[0037] The casting process is preferably an injection molding process or a die casting process.

[0038] Polymeric materials, such as thermosetting plastics, thermoplastics, etc., are used as casting compounds. These materials are usually filled with inorganic materials to improve certain material properties, such as thermal conductivity.

[0039] The inventive design of the electric compressor enables efficient cooling, particularly of the electric motor and the control unit. Thus, with a suitable choice of the potting compound used in the potting process, higher electric motor performance can be easily achieved with a compact and simple design. Furthermore, reliable, service-optimized operation of the electric compressor can be ensured, particularly through efficient cooling of the control unit.

[0040] The housing at least partially protects the electric motor from external negative influences, such as contamination, and also performs the cooling function of the electric motor.

[0041] A method for producing an electric compressor as described above comprises producing the housing by means of a potting process, wherein the potting process is carried out in such a way that the cooling structure is formed integrally with the housing, in particular in the housing.

[0042] By producing a housing with an integrated cooling structure for efficient cooling of the electric motor and the control unit of the electric compressor according to the invention, additional components in this area can be dispensed with.

[0043] Furthermore, the production of the electric compressor also allows other components to be optimized and / or eliminated, for example in the area of ​​the shaft bearings.

[0044] The manufacturing process is simple to carry out and the cooling structure in the housing can be individually designed depending on the cooling requirements and structural design of the electric motor and the control unit.

[0045] In a further advantageous embodiment of the present invention, the cooling structure is formed at least partially on the rear side of the control unit. This makes it possible to easily ensure the cooling of other highly stressed electronic components.

[0046] The housing is preferably made of a thermally conductive, electrically insulating material.

[0047] The cooling structure can be produced by means of internal pressure injection molding and / or by introducing at least one molded body.

[0048] In addition, at least one opening can be produced by means of internal pressure injection molding and / or by inserting at least one opening mold. By forming, for example, a central opening along the central axis of rotation of the electric motor within the stator of the electric motor, a space for the shaft and rotor can be easily created.

[0049] The molded body and the opening molded body are arranged, for example, with the part of the electric compressor according to the invention to be cast, at least partially the electric motor of the electric compressor according to the invention, in a suitable casting device and cast with casting compound.

[0050] The molded body and the opening molded body are preferably removed mechanically and / or volatilized by chemical reaction and / or thermal reaction after the casting process, ie after curing of the casting compound.

[0051] When forming the cooling structure and / or the opening using internal pressure injection molding, a filler, such as water or an inert gas such as nitrogen, is injected into a gas-tight device partially filled with flowable, uncured potting compound. The filler acts as an internal mold within the device, displacing the potting compound radially outward from the inside toward the inner walls of the device. This creates a cavity within the potting compound. After the potting compound has cured, the filler can escape from the device, and the resulting cavity forms the cooling structure. Brief description of the drawings

[0052] The invention is described below by way of example with reference to the drawings. Fig. 1 shows a longitudinal section of an electric compressor according to the invention. Fig. 2 shows a perspective view of a control unit and a stator of an electric motor of an electric compressor according to the invention. Fig. 3 shows a perspective detail view from Fig. 3. Fig. 4 shows a perspective view of a housing including a control unit and a stator of an electric motor of an electric compressor according to the invention. Fig. 5 shows Fig. 4 in a longitudinal section. Fig. 6 shows Fig. 4 in a cross section. Fig. 7 shows Fig. 4 in another cross-section at the electric motor / control unit interface. Fig. 8 shows a top view of the control unit according to Fig. 4. Fig. 9 shows Fig. 4 in a further longitudinal section including arranged molded parts. Fig. 10 shows a perspective view of the electric compressor according to the invention. Detailed description of the invention

[0053] The Fig. The electric compressor shown in Figure 1 comprises a control unit 2, an electric motor 3, a compressor wheel 4 and a housing 6 ( Fig. 4) appears.

[0054] The electric motor 3 can be controlled by means of the control unit 2 and serves to optionally drive the compressor wheel 4.

[0055] The compressor wheel 4 and the electric motor 3 are arranged coaxially on a common shaft 5, wherein the shaft 5 is formed along a central axis of rotation 13 of the electric motor 3.

[0056] The compressor wheel 4 is arranged in a compressor wheel housing 17.

[0057] The compressor wheel housing 17 is formed by the combination of a first compressor wheel housing part 18 and a second compressor wheel housing part 19.

[0058] The electric motor 3 is designed as an internal rotor electric motor and has a rotor 14 with permanent magnets and a stator 9 with six stator windings 15.

[0059] The electric motor 3 drives the compressor wheel 4.

[0060] The rotor 14 of the electric motor 3 is arranged on the shaft 5 in a rotationally fixed manner.

[0061] The compressor wheel 4 is arranged on the shaft 5 in a rotationally fixed manner.

[0062] The rotational energy generated by the electric motor 3 is transferred to the compressor wheel 4 via the common shaft 5.

[0063] The control unit 2 is arranged coaxially to the electric motor 3 along the central axis of rotation 13 of the electric motor 3 and is electrically connected to the electric motor 3, more precisely to the stator windings 15 of the stator 9 of the electric motor 3, via at least one connecting element 16.

[0064] Fig. 2 shows a perspective view of a control unit 2 and a stator 9 of an electric motor 3 of an electric compressor 1 according to the invention.

[0065] The control unit 2 represents the power and signal electronics for the electric motor 3 and comprises a printed circuit board 20 on which various electronic components 21, including capacitors 22, are arranged, as well as two connection plugs 23.

[0066] The two connection plugs 23 are one power plug and the other signal plug.

[0067] The stator 9 of the electric motor 3 comprises six individual stator segments 24, six stator windings 15 arranged on the stator segments 24 and a stator carrier 25.

[0068] The stator carrier 25 is ring-shaped and encloses the stator segments 24 and the stator windings 15.

[0069] The stator carrier outer circumference thus forms the outer circumference 10 of the stator 9 of the electric motor 3.

[0070] The stator carrier 25 has a plurality of axially extending recesses 11 evenly spaced on the outer circumference 10.

[0071] The direction “axial” refers to a direction along the central axis of rotation 13 of the electric motor 3.

[0072] In the area between the recesses 11, the stator carrier 25 has lugs 26 in the area of ​​a side facing away from the control unit 2.

[0073] The lugs 26 extend radially over a partial area of ​​the outer circumference 10 of the stator carrier 25 in the area between two recesses 11.

[0074] The direction “radial” refers to a direction normal to the central axis of rotation 13 of the electric motor 3.

[0075] The lugs 26 are designed such that the capacitors 22 of the control unit 2 can extend axially along the stator 9 up to the lugs 26 in the area between two recesses 11.

[0076] In this way, a compact and robust arrangement of the electric motor 3 and the control unit 2 is achieved.

[0077] In Fig. 3 is the one based on Fig. 2 already described perspective view of the control unit 2 and the stator 9 of an electric motor 3 without the stator carrier.

[0078] The six stator windings 15 of the stator 9 can be seen here.

[0079] In the area of ​​the central opening 27 of the stator 9, the rotor 14 arranged on the shaft 5 is arranged (not shown; Fig. 1).

[0080] Fig. 4 shows the Fig. 2 and Fig. 3 already described perspective view of the control unit 2 and the stator 9 of an electric motor 3 with the housing 6 of the electric compressor 1 according to the invention. Fig. 5 shows a longitudinal section through the perspective view in Fig. 4.

[0081] The stator 9 of the electric motor 3 and the control unit 2 are arranged in the housing 6 of the electric compressor 1 according to the invention.

[0082] The housing 6 is manufactured using a casting process, wherein a cooling structure 7 is formed integrally with the housing 6, in the housing 6.

[0083] The cooling structure 7 has a plurality of cooling channels 8, wherein the cooling channels 8 are formed around the outer circumference 10 of the stator of the electric motor 3, in particular the cooling channels 8 extend axially along the recesses 11 of the stator 9 (the stator carrier 25).

[0084] The cooling structure 7 of the present exemplary electric compressor 1 has a number of cooling channels 8 corresponding to the number of recesses 11 of the stator 9, ie six cooling channels 8.

[0085] The cooling channels 8 each extend radially from the recess 11 on the outer circumference 10 of the stator 9 into the area of ​​the capacitors 22 of the control unit 2, which extend axially along the outer circumference 10 of the stator 9 between two recesses 11. Here, the radial extension of the lugs 26 is shorter than the radial extension of the cooling channels 8.

[0086] The cooling channels 8 serve not only to cool the electric motor 3, but are also used to cool the capacitors 22. The rear side 34 of the control unit 2, namely the side of the control unit 2 facing away from the electric motor 3, is also cooled via the cooling channel feedthroughs 28.

[0087] In Fig. 6 is a first cross-section through the Fig. 4 shows a perspective view of the control unit 2 and the stator 9 of an electric motor 3 with the housing 6 of the electric compressor 1 according to the invention.

[0088] Here, in particular, the distribution of the noses 26, the capacitors 22 and the cooling channels 8 along the outer circumference 10 of the stator carrier 25 can be seen.

[0089] Fig. 7 shows a further cross section through the Fig. 4 shows a perspective view of the control unit with the housing 6 of the electric compressor 1 according to the invention at the interface between the electric motor 3 and the control unit 2.

[0090] Here, too, the distribution of the capacitors 22 and the cooling channels 8 along the outer circumference 10 of the stator carrier 25 can be seen.

[0091] In addition, one of three connecting elements 16 is shown by means of which the electric motor 3 is electrically connected to the control unit 2.

[0092] The connecting elements 16 represent the electrical interface between the electric motor 3, more precisely the stator windings 15, and the control unit 2.

[0093] In Fig. Figure 8 is a plan view of control unit 2 as shown in Fig. 4 is shown.

[0094] The cooling structure 7 of the electric compressor 1 according to the invention has two cooling channel passages 28 in the area of ​​the control unit 2, which serve to cool the rear side 34 of the control unit 2, namely the side of the control unit 2 facing away from the electric motor 3, wherein in particular the cooling of further highly loaded electronic components 21 of the control unit 2 takes place in this way.

[0095] The cooling structure 7 is supplied with cooling fluid via a cooling fluid inlet 32 ​​and a cooling fluid outlet 33.

[0096] The method according to the invention for producing the described electric compressor 1 comprises the production of the housing 6 by means of a casting process, wherein the casting process is carried out in such a way that the cooling structure 7, ie here the cooling channels 8, is formed in one piece with the housing 6, in the housing 6.

[0097] The cooling structure 7 is produced by inserting molded bodies 12.

[0098] Fig. 9 shows a longitudinal section through the Fig. 4 shows a perspective view with inserted mold bodies 12 and an opening mold body 29.

[0099] The mold bodies 12 and the opening mold bodies 29 are removed mechanically after the casting process.

[0100] The molded bodies 12 serve, as in Fig. 9, the formation of the cooling channels 8 of the cooling structure 7 and, according to the present embodiment, have a trapezoidal cross-section, so that the trapezoidal cooling channels 8 are formed in the housing. However, the molded bodies 12 and thus the cooling channels 8 can be formed in any desired shape.

[0101] The opening shaped body 29 serves to form the central opening 27 and has a substantially circular cross-section, so that a circular central opening 27 is obtained for the arrangement of the shaft 5 and the rotor 14.

[0102] In this embodiment, the stator 9 and the control unit 2 are completely encapsulated by means of the casting process, only the locations at which the molded bodies 12 and the opening molded body are inserted remain free, so that the cooling structure 7 and also the central opening 27 are formed.

[0103] Fig. 10 shows the Fig.1 shows an exemplary electric compressor 1 according to the invention, shown in a longitudinal section, in a perspective view, wherein a compressor gas inlet 30 and a compressor gas outlet 31 are formed on the compressor wheel housing 17.

[0104] In addition, the assembly of the compressor wheel housing 17 and the housing 6 of the electric compressor 1 is visible.

[0105] According to the present invention, the compressor wheel housing 17 can also be formed in one piece with the housing 6 of the electric compressor 1. List of reference symbols 1 Electric compressor 2 control unit 3 electric motor 4 Compressor wheel 5 Wave 6 housings 7 Cooling structure 8 cooling channel 9 Stator 10 Outer circumference (of the stator / stator carrier) 11 Recess 12 molded bodies 13 Central axis of rotation 14 Rotor 15 Stator winding 16 Connecting element 17 Compressor wheel housing 18 First compressor wheel housing part 19 Second compressor wheel housing part 20 circuit board 21 Electronic components 22 capacitors 23 connector plugs 24 stator segments 25 stator carriers 26 Nose 27 Opening 28 Cooling channel feedthrough 29 opening moldings 30 Compressor gas inlet 31 Compressor gas outlet 32 Cooling fluid inlet 33 Cooling fluid outlet 34 Back (of the control unit)

Claims

[1] Electric compressor (1) for compressing a gas, in particular for a motor vehicle, comprising - a control unit (2) with several capacitors (22), - an electric motor (3) with a substantially ring-shaped stator (9), wherein the electric motor (3) is controllable by means of the control unit (2) and wherein the stator (9) has a plurality of axially extending recesses (11) evenly spaced along its outer circumference (10), - a compressor wheel (4), wherein the compressor wheel (4) can be driven by means of the electric motor (3), and - a housing (6), wherein the housing (6) at least partially encloses the electric motor (3), wherein the housing (6) is manufactured by means of a casting process such that a cooling structure (7) with a plurality of cooling channels, namely a number of cooling channels (8) corresponding to the number of recesses (11), is formed in one piece with the housing (6), in particular in the housing (6), wherein the cooling structure (7) is formed at least partially around the outer circumference (10) of the stator (9), so that cooling of the electric motor (3) and the control unit (2) takes place, wherein the cooling channels (8) extend axially along the recesses (11) of the stator (9), wherein the stator (9) has, in the region between the recesses (11), on a side facing away from the control unit (2), lugs (26) extending radially over a partial region of the outer circumference (10), which are designed such thatthat a capacitor (22) of the control unit (2) can extend in the area between two recesses (11) axially along the stator (9) up to the lugs (26). [2] Electric compressor (1) according to claim 1, characterized by that the compressor wheel (4) and the electric motor (3) are arranged coaxially on a shaft (5). [3] Electric compressor according to claim 1 or 2, characterized by that the housing (6) at least partially encloses the control unit (2). [4] Electric compressor (1) according to one of the preceding claims, characterized by that the cooling structure (7) is formed at least partially on a rear side (34) of the control unit (2). [5] Electric compressor (1) according to one of the preceding claims, characterized by that the housing (6) is made of a thermally highly conductive material.

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