Electrical machine arrangement

Abstract

An electrical machine arrangement (1) comprising two electrical machines (2, 3), each with a housing (4, 5), wherein each housing (4, 5) has a machine compartment (12, 13) with a rotor-stator arrangement (6, 7) and a resolver compartment section (18, 19) forming part of a resolver compartment (20) located between the machine compartments (12, 13) and sealed towards the machine compartments, wherein the housings (4, 5) with their resolver compartment sections (18, 19) are adjoining one another and are connected to each other to form the resolver compartment (20), wherein several pressure equalization elements (21, 22, 25, 26) are provided for the machine compartments (12, 13) and the resolver compartment (20), wherein a pressure equalization element (25, 26) is arranged so that pressure equalization takes place between the resolver room (20) and the coupled machine room (12, 13).

Description

[0001] The invention relates to an electric machine arrangement comprising two electric machines, each with a housing.

[0002] Such an electric motor assembly is used, for example, as a rear axle drive in an electric motor vehicle. The assembly comprises two separate electric motors, one driving the right axle section and thus the right rear wheel, and the other driving the left axle section and thus the left rear wheel. Each electric motor has a housing, usually made of cast metal, in which a rotor-stator assembly is accommodated in a pot-shaped recess forming a machine chamber. A coolant can flow through this chamber to cool the electric motor and its working components. To create a uniform, closed coolant chamber for the entire assembly, the housings are joined together with their open end faces, thus both enclosing and connecting the two machine chambers.Typically, the two rotor-stator arrangements are connected to each other via a common rotor shaft through which a coolant can flow.

[0003] To allow pressure equalization between the interior of the housings and the environment, several pressure equalization elements are provided. Each machine compartment can be vented to the environment via at least one pressure equalization element, and the resolver compartment can also be vented to the environment via at least one pressure equalization element.

[0004] The pressure equalization elements are located on the outer surface of each housing. The pressure equalization element(s) assigned to the resolver chamber are situated at the interface of the two housings, resulting from the fact that the two housings are geometrically identical but positioned at 180° to each other. Each pressure equalization element therefore represents an interface to the environment.

[0005] German patent application DE 20 2009 014 189 U1 discloses a motor vehicle with an electric axle in which two electric machine arrangements, each comprising a housing, a stator, and a rotor, are arranged in a mirror image of each other. One machine arrangement is specified as having a housing with a first bearing cap and a second bearing cap, between which a cylindrical section extends. A second shaft section extends from the housing through an opening or axial recess in the bearing cap, and a sensor arrangement is provided on the second section to enable the detection of the shaft's rotational position. An incremental encoder is provided as the sensor arrangement.The second machine arrangement is analogous and mirror-image to the first machine arrangement, with the two first bearing covers of the two machine arrangements being connected to each other and the axial recesses of these bearing covers forming a sensor space.

[0006] JP 2006-298 314 A discloses a drive unit for a motor vehicle comprising two electric motors. One electric motor serves to start an internal combustion engine and subsequently generate electrical energy. The other electric motor is powered by a high-voltage battery and serves to drive the motor vehicle. A resolver is also provided, which is attached to a partition separating the housing of one electric motor from that of the other electric motor and a gearbox. A passage in the partition allows pressure exchange between these two housings. Valves are also provided to connect the housings to the environment.

[0007] The invention is based on the problem of providing an improved electrical machine arrangement in comparison.

[0008] To solve this problem, an electric machine arrangement is provided, comprising two electric machines, each with a housing, wherein each housing has a machine room with a rotor-stator arrangement and a resolver room section forming part of a resolver room formed between the machine rooms and sealed towards the machine rooms, wherein the housings with their resolver room sections are adjoining each other and are connected to each other to form the resolver room, wherein several pressure equalization elements are provided for the machine rooms and the resolver room, wherein a pressure equalization element is arranged between the resolver room and at least one of the adjacent machine rooms, so that pressure equalization takes place between the resolver room and the coupled machine room.

[0009] Unlike before, pressure equalization no longer occurs between the resolver chamber and the environment, but rather between the resolver chamber and at least one of the adjacent machine compartments. This means that the pressure equalization element is positioned within a partition wall that separates the resolver chamber from the adjacent machine compartment. This reduces the number of interfaces to the environment, as the pressure in the resolver chamber is essentially equalized internally. Any overpressure in the resolver chamber is thus equalized towards the machine compartment, with any resulting overpressure being released to the environment via the pressure equalization element on the machine compartment side. By reducing the number of external interfaces, the risk of moisture ingress into the interior of the assembly through such a pressure equalization element is also reduced.

[0010] Preferably, the resolver room is coupled to both machine rooms via a pressure equalization element, so that possible venting to both machine rooms is possible.

[0011] According to a particularly advantageous embodiment of the invention, the pressure equalization element(s) that couple the resolver chamber with the engine room(s) are arranged above a collection section for leakage water provided in the resolver chamber. The resolver chamber is designed with a collection section located at the bottom of the resolver chamber, in which any leakage fluid, typically a coolant, which may penetrate, for example, via bearing points where the rotor shafts are mounted on the partition wall separating the resolver chamber from the adjacent engine room, can collect.If, according to the invention, the pressure equalization element(s) are arranged above this collecting section, then, despite internal venting of the resolver chamber to the machine chamber(s), it is prevented that any leakage fluid from the resolver chamber or the collecting section can enter the respective machine chamber, i.e., the active chamber with the rotor-stator arrangement. This means that leakage from the resolver chamber to the machine or active chamber(s) is prevented.

[0012] As described, each engine compartment can be vented to the environment via at least one pressure equalization element. Positionally, it is advantageous for the pressure equalization elements to be located above a wading line, i.e., a line up to which the vessel can be submerged without impairing its function. Since, as explained, the two engine housings are identical, only mirrored, the position of the respective receptacles in which the pressure equalization elements are positioned must be selected accordingly during the housing design, so that the pressure equalization elements are positioned sufficiently high in the assembled state.

[0013] It is advantageous for the pressure equalization elements, through which the machine compartments can be vented, to be arranged on the opposing end faces of the housings. The end faces of the housings are closed by corresponding housing covers. These housing covers, which—like the two housings themselves at the central interface—are sealed with appropriate sealants or sealing elements, can be easily fitted with the necessary receptacles for one or, if necessary, several pressure equalization elements per machine half, so that the appropriate positioning of the pressure equalization elements at the appropriate housing height can be readily achieved.

[0014] In addition to the electric machine arrangement itself, the invention further relates to a motor vehicle comprising such an electric machine arrangement, in particular as a rear axle drive.

[0015] Further advantages and features of the invention will become apparent from the exemplary embodiment described below and from the drawing. The drawing shows: Fig. 1 a schematic representation of an electrical machine arrangement according to the invention of a first embodiment, and Fig. 2 a schematic representation of an electrical machine arrangement according to the invention of a second embodiment.

[0016] Fig. Figure 1 shows a schematic representation of an electrical machine arrangement 1 according to the invention, comprising a first electrical machine 2 and a second electrical machine 3. Each electrical machine 2, 3 has a housing 4, 5 in which a corresponding rotor-stator arrangement 6, 7 comprising a stator 8, 9 and a rotor 10, 11 is accommodated.

[0017] Each housing 4, 5 is designed in a pot-like shape and is open on one side, so that each housing 4, 5 has a machine chamber 12, 13 in which the respective rotor-stator assembly 6, 7 is accommodated. The rotor 10, 11 is, of course, arranged in a known manner on a corresponding output shaft in order to drive the respective wheel coupled to the output shaft. It rotates within the respective stator 8, 9, as indicated by the double arrows P.

[0018] At their respective end faces, each housing 4, 5 has a closing cover 14, 15. The two housings 4, 5 abut each other at their end faces 16, 17. In this area, the two housings 4, 5 are configured such that each housing has a resolver chamber section 18, 19, the two resolver chamber sections 18, 19 combining to form a resolver chamber 20 located centrally between the two machine chambers 12, 13. A device for resolving the position of the respective rotor 10, 11 relative to the stator 8, 9 is accommodated in this resolver chamber in a manner known per se.

[0019] The basic structure and function of such an electrical machine arrangement is well known. Fig. Figure 1 is a purely schematic representation to explain the essential components.

[0020] Two pressure equalization elements 21, 22 are shown, each assigned to one of the two machine compartments 12, 13. One pressure equalization element 21, 22 is shown for each housing 4, 5; naturally, several such pressure equalization elements, each assigned to one of the machine compartments 12, 13, can be provided on the respective housings 4, 5. The pressure equalization elements 21, 22 are arranged in the circumferential wall sections of the housings 4, 5, i.e., on the lower and upper sides. Corresponding receptacles are formed in the housings 4, 5, into which the respective pressure equalization elements 21, 22 are inserted. It should be noted that the two housings 4, 5 are identical in design but arranged as mirror images of each other. This means that only one type of housing is required to form the electric machine arrangement 1; the housings 4, 5 simply need to be arranged with their end faces 16, 17 reversed relative to each other.Any overpressure within the engine rooms 12, 13 can be discharged to the environment via the pressure equalization elements 21, 22, thus allowing venting.

[0021] Any overpressure in resolver chamber 20 can also be equalized, but not to the environment as before, but rather into one of the two machine chambers 12, 13. For this purpose, at least one pressure equalization element 25, 26 is arranged in the respective partition 23, 24, which separates resolver chamber 20 from machine chamber 12 or 13, respectively. Any overpressure in resolver chamber 20 can be discharged via the pressure equalization elements 25, 26 either into machine chamber 12 or machine chamber 13, and any overpressure in the respective machine chamber 12, 13 can then be discharged to the environment via the pressure equalization elements 21, 22. This means that resolver chamber 20 is vented internally; unlike before, an interface to the environment is no longer provided.The pressure equalization elements 25, 26 are also opposite each other, resulting from the fact that the two housings 4, 5 are identical but arranged in a mirror image of each other.

[0022] Furthermore, resolver chamber 20 contains a collection section 27 for any leakage water that may enter the resolver chamber from the cooling circuit implemented within the electric machine assembly 1. Machine chambers 12 and 13 are interconnected in such a way that any coolant channels or the machine chambers themselves complement or communicate with each other, allowing coolant to flow through the coolant channels or the machine chambers themselves to cool the respective rotor-stator assembly 6 and 7. The coolant can only circulate within the housings 4 and 5, meaning that they essentially have a common, closed coolant circuit. However, it is also conceivable to supply the coolant, for example, at housing 4 and discharge it at housing 5, feeding it to a cooling device from which it is then returned to housing 4.This means that in this case, the electric machine assembly 1 would be integrated into an external coolant circuit. Through this coolant circuit, whether internal or external, it is possible for coolant to penetrate the otherwise sealed resolver chamber 20, for example, via bearing points where the rotor shafts are supported against the housing walls 23 or 24. This coolant collects in the area of ​​the collection section 27. Since the lower pressure equalization element 26 is located above this collection section 27, its positioning advantageously prevents any leakage fluid from the collection section 27 from entering the adjacent machine chambers 12 and 13 via a pressure equalization element.

[0023] Fig. Figure 2 shows an embodiment of an electrical machine arrangement 1 according to the invention, which is derived from Fig. 1 corresponds. The only difference is that in the design according to Fig. 2. The two pressure equalization elements 21, 22 are not arranged on the respective cylindrical wall section of the housings 4, 5, but on the housing cover 14, 15, i.e., on the end face. Thus, compared to the arrangement shown in Fig. 1, somewhat higher (in the case of the pressure equalization element 21) or lower (in the case of the pressure equalization element 22), compared with the design according to Fig. 1. The lower pressure equalization element 21 is located in a position above a wading line 28. This wading line is the height to which the electrical machine assembly can be submerged without any loss of function. Because the pressure equalization element 21 is positioned above this wading line 28, it prevents water from entering the respective associated machine compartment via the pressure equalization element 21 should the electrical machine assembly 1 become submerged.

Claims

[1] Electric machine arrangement (1) comprising two electric machines (2, 3) each with a housing (4, 5), wherein each housing (4, 5) has a machine compartment (12, 13) with a rotor-stator arrangement (6, 7) and a resolver compartment section (18, 19) forming part of a resolver compartment (20) located between the machine compartments (12, 13) and sealed towards the machine compartments, wherein the housings (4, 5) with their resolver compartment sections (18, 19) are adjoining one another and are connected to each other to form the resolver compartment (20), wherein several pressure equalization elements (21, 22, 25, 26) are provided for the machine compartments (12, 13) and the resolver compartment (20), wherein a pressure equalization element is located between the resolver compartment (20) and at least one of the adjacent machine compartments (12, 13). (25, 26) is arranged so that pressure equalization takes place between the resolver room (20) and the coupled machine room (12, 13). [2] Electric machine arrangement (1) according to claim 1, characterized by , that the resolver room (20) is coupled to both machine rooms (12, 13) via a pressure equalization element (25, 26) in each case. [3] Electric machine arrangement (1) according to claim 1 or 2, characterized by that the or both pressure equalization elements (25, 26) are arranged above a collection section (27) for leakage water provided in the resolver room (20). [4] Electric machine arrangement (1) according to one of the preceding claims, characterized by , that the two pressure equalization elements (21, 22), via which the machine rooms (12, 13) can be vented, are arranged above a wading line (28) when viewed in the upward direction of the electrical machine arrangement (1). [5] Electric machine arrangement (1) according to one of the preceding claims, characterized by, that the pressure equalization elements (21, 22), via which the machine rooms (12, 13) can be vented, are arranged on the opposite end faces of the housings (4, 5). [6] Motor vehicle comprising an electric machine arrangement (1) according to any one of the preceding claims.

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