Motor housing for an electric motor

Abstract

A motor housing for an electric motor comprises a basic housing made of aluminium, which is designed as a deep-drawn component, and a separately designed mounting flange arranged on the front face of the basic housing, which is firmly connected to the basic housing.

Description

The invention relates to a motor housing for an electric motor, in particular for a steering motor, wherein the motor housing has a base housing made of aluminium for receiving the stator and rotor. State of the art Electric steering motors are commonly found in vehicles, where they are coupled to a steering gear to provide steering assistance. The steering motors are powered by a control unit with power electronics located on the axial rear side of the motor housing. Heat from the electronics is transferred to the steering gear via the motor housing, a process facilitated by the high conductivity of the aluminum housing. Disclosure of the invention The motor housing according to the invention for electric motors can be used in particular for electric steering motors in vehicle steering systems where the steering motor is used for steering assistance. The steering motor is coupled to a steering gear, via which the steering motor feeds a supporting torque into the steering system. Such steering motors can also be used for autonomous steering maneuvers. In the following, the term "axial" refers to the longitudinal axis of the electric motor. Similarly, "radial" refers to a direction orthogonal to the longitudinal axis of the electric motor. The motor housing comprises an aluminum base housing for the stator and rotor, and a mounting flange that is separate from the base housing but permanently attached to it. The mounting flange connects the electric motor to another component, which in the case of a steering motor is the steering gear. The base housing, made of aluminum and therefore possessing high thermal conductivity, is a deep-drawn component. Such deep-drawn components are particularly cost-effective to manufacture. Due to the functional separation of the aluminum base housing and the separately designed mounting flange, standardized base housings for the stator and rotor can be used, along with individually adapted mounting flanges, which provide the specific interface for connection to the other component.At the same time, the advantage of the high thermal conductivity of the aluminum base housing is retained. The holding forces are absorbed via the mounting flange, which is firmly connected to the base housing, allowing the entire electric motor to be securely coupled to the other component. The aluminum base housing itself is not subject to direct fastening forces on the other component. A further advantage is that all sealing interfaces between the motor housing and the other components can be located exclusively on the aluminum base housing, whereas the mounting flange can be kept free of such sealing interfaces. The mounting flange is located on the outside of the aluminum base housing; a watertight connection between the base housing and the mounting flange is not required. In an advantageous embodiment, the mounting flange is annular. Several positions for the mounting flange on the base housing are possible. Firstly, it is advantageous to have an annular shoulder on one end face of the base housing, upon which the mounting flange rests. Secondly, it is also possible, regardless of whether an annular shoulder is present, to slide the mounting flange onto the cylindrical surface of the base housing. In both cases, the mounting is on the outside of the base housing. In the case of an annular shoulder, this provides support for the mounting flange in both the radial and axial directions. If the mounting flange is slid onto the cylindrical surface of the base housing, the base housing can be relatively short axially. According to yet another advantageous embodiment, the mounting flange has several radially outwardly projecting mounting eyes, via which attachment to the other component is possible. This embodiment has the advantage that the fastening elements, for example screws, are located at a radial distance from the outer surface of the cylindrical base housing and are easily accessible. According to yet another advantageous embodiment, an axially projecting, annular sealing carrier is integrally formed on the mounting flange. The annular sealing carrier projects axially beyond the base body of the mounting flange and allows for easy insertion of an annular sealing element, which is provided with a receiving groove into which the annular sealing carrier on the mounting flange projects when assembled. According to yet another advantageous embodiment, the mounting flange is designed as an extruded component. Alternatively, the mounting flange can also be designed as a cast component. According to a further advantageous embodiment, an aluminum alloy, in particular an aluminum-magnesium-lithium alloy such as EN AW6060, is suitable as the material for the mounting flange. According to yet another advantageous embodiment, the mounting flange has several boreholes distributed around its circumference, which serve to accommodate fastening screws for attachment to the other component. It may be advantageous to insert bushings, preferably made of steel, into these boreholes. The increased strength of the bushings allows for a shorter axial length of the mounting flange. If the mounting flange is inserted into an end-face annular shoulder on the base housing, the axial extent of the annular shoulder, and thus also the overall axial extent of the base housing, can be reduced accordingly. The connection between the mounting flange and the base housing can be made in various ways. It is particularly advantageous to create a friction-fit or material-fit connection with the base housing, for example by welding, especially laser welding, by bonding, or by thermal shrinking. The invention further relates to an electric motor with a motor housing as described above. The electric motor is, by way of example, a steering motor in a vehicle. The electric motor can have a control unit, including power electronics, on the end face axially opposite the mounting flange, which is attached to the base housing. The end face of the base housing with the control unit arranged thereon can be open, with the open side being closed by the mounting of the control unit. Further advantages and practical embodiments can be found in the further claims, the description of the figures, and the drawings. Figure 1 shows a perspective view of an electric motor with a cylindrical aluminum housing and a mounting flange on one end face. Figure 2 shows a longitudinal section through an electric motor with a housing and an end-face mounting flange, wherein a housing for a control unit is arranged on the opposite end face. Figure 3 shows a longitudinal section through the motor housing with the mounting flange in one embodiment. Figure 4 shows a perspective view of an electric motor with the mounting flange in another embodiment. Figure 5 shows a further perspective view of an electric motor with the mounting flange in yet another embodiment. Figure 6 shows a longitudinal section through an electric motor with the housing in one embodiment. In the figures, identical components are labelled with the same reference symbols. Figures 1 and 2 show a first embodiment of an electric motor 1, which is, for example, a steering motor for a steering system in a vehicle. Figure 1 shows the electric motor 1 with its motor housing, which comprises a cylindrical base housing 2 and a mounting flange 3 designed as an extruded or cast component. Figure 2 additionally shows a control unit housing 4 for accommodating a control unit including power electronics on one end face of the base housing 2. The electric motor 1 is, for example, designed as a permanent magnet, electrically commutated motor. The stator, which is located together with the rotor in the base housing 2, has windings distributed around its circumference. These windings are energized via terminals 5 from the power electronics in the control unit housing 4. The base housing 2 is made of aluminum and is designed as a deep-drawn component. The base housing 2 can be designed uniformly for a wide variety of applications, with individual adaptation for attaching the electric motor 1 to another component, such as a steering gear, via the mounting flange 3. The control unit with its control unit housing 4 can also be individually adapted, with a standardized connection for the control unit housings 4 to be connected being provided in the area of ​​interface 6 on the front face of the base housing 2. On the side axially opposite the control unit housing 4, the base housing 2 has a central opening for the rotor shaft, which is supported in a bearing adjacent to the end face. The protruding section of the rotor shaft can be used to drive, for example, a steering gear. On the outer end face of the base housing 2, adjacent to the central opening for the rotor shaft, there is a sealing element 7, which creates a flow-tight connection between the base housing and the other component or assembly to which the electric motor 1 is connected. Also on the end face with the opening for the rotor shaft, an annular shoulder 9 is formed on the base housing 2, on which the annular mounting flange 3 rests. The mounting flange 3 is firmly connected to the outside of the base housing 2, in particular by friction or material bonding, for example by welding or shrink-fitting. Distributed around its circumference, the mounting flange 3 has several axially extending bore holes 10, which serve for screwing it to the adjacent component. The dimensions of the mounting flange 3 are selected such that the annular shoulder 9 is completely filled by the mounting flange 3 in both the radial and axial directions, so that the radial outer diameter of the mounting flange 3 corresponds to the radial outer diameter of the base housing 2 and the axial extent of the mounting flange 3 corresponds to the axial extent of the annular shoulder 9. Figure 3 shows a variant embodiment of the mounting flange 3, which has an insert bushing 11 made of steel in the boreholes 10. The insert bushing 11 is capable of withstanding high forces and serves for bolting to the adjacent component. The insert bushing 11 is made of a harder and more resistant material than the mounting flange 3. The insert bushing 11 allows the mounting flange 3 to be designed with a smaller axial length, which in turn allows the annular shoulder 9 to also be designed with a smaller axial length. This results in a reduction of the overall axial length of the base housing 2 and the electric motor 1. In the embodiment shown in Fig. 4, the mounting flange 3 is inserted into an annular shoulder on the base housing 2, analogous to the first embodiment shown in Figs. 1 and 2. The mounting flange 3 has a total of three radially outwardly projecting mounting lugs 12 distributed around its circumference, each with a bore 10 for fastening to the adjacent component. The mounting lugs 12 project radially beyond the outer surface of the base housing 2 and are thus easily accessible from the outside for the insertion of fastening screws. Fig. 4 also shows a rotor shaft 13 that protrudes from the base housing. In the embodiment shown in Fig. 5, the mounting flange 3 is also inserted into an annular shoulder adjacent to the end face of the base housing 2. The mounting flange 3 has two diametrically opposed mounting lugs 12 extending radially outwards, each with a bore 10. Furthermore, the mounting flange 3 is provided with an axially projecting, annular sealing carrier 14, which serves to receive a seal for a flow-tight connection with an adjacent component to which the electric motor 1 is connected. In Fig. 6, the mounting flange 3 is designed analogously to the first embodiment according to Figs. 1 and 2 and sits on the outer surface of the base housing 2. In contrast to the first embodiment, the base housing 2 has an axial projection with a slightly reduced outer diameter, which allows for individual adaptation to design requirements, in particular to the adjacent component. Accordingly, in the embodiment according to Fig. 6, the base housing 2 is individually adapted, whereby the mounting flange 3 can also be selected according to the design requirements, if necessary.

Claims

Motor housing for an electric motor, in particular for a steering motor, with a base housing (2) made of aluminium for receiving the stator and rotor, characterized in that the base housing (2) is designed as a deep-drawn component and that a separately designed mounting flange (3) is arranged on an end face of the base housing (2), which is firmly connected to the base housing (2). Motor housing according to claim 1, characterized in that the mounting flange (3) is annular in shape. Motor housing according to claim 2, characterized in that the mounting flange (3) rests on an annular shoulder (9) on the end face of the base housing (2). Motor housing according to claim 2, characterized in that the mounting flange (3) is pushed onto the outer surface of the cylindrical base housing (2). Motor housing according to one of claims 1 to 4, characterized in that the mounting flange (3) has radially outwardly projecting mounting eyes (12). Motor housing according to one of claims 1 to 5, characterized in that an axially projecting, annular sealing carrier (14) is integrally formed on the mounting flange (3). Motor housing according to one of claims 1 to 6, characterized in that the mounting flange (3) is designed as an extruded component. Motor housing according to one of claims 1 to 7, characterized in that the mounting flange (3) is designed as a cast component. Motor housing according to one of claims 1 to 8, characterized in that the mounting flange (3) is made of an aluminum alloy, for example EN AW6060. Motor housing according to one of claims 1 to 9, characterized in that the mounting flange (3) has several boreholes (10) distributed around its circumference. Motor housing according to claim 10, characterized in that insert bushings (11) are inserted into the bore holes (10). Motor housing according to one of claims 1 to 11, characterized in that the mounting flange (3) is connected to the base housing (2) by friction or material bonding, in particular by welding, gluing or shrinking. Electric motor with a motor housing according to one of claims 1 to 12. Electric motor according to claim 13, characterized in that a control unit with power electronics is attached to the base housing at the end face axially opposite the mounting flange (3). Electric motor according to claim 12 or 13, characterized in that a sealing element (7) is arranged on the end face receiving the mounting flange (3), which is located at a distance from the mounting flange (3).

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