Electric motor

Abstract

The invention relates to an electric motor (10), having a shaft (20) that is arranged in a motor housing (12) and is mounted rotatably on an end-face end region by way of a bearing device (32), wherein the motor housing (12), on the side facing the bearing device (32), has a housing opening (14) that is closed off by way of a cover element (16), wherein the bearing device (32) is arranged in a bearing receptacle element (36) separate from the cover element (16), and wherein the bearing receptacle element (36) is attached, in radially and axially fixed fashion, in a housing receptacle (48) of the motor housing (12).

Description

[0001] Description

[0002] electric motor

[0003] Technical area

[0004] The invention relates to an electric motor, in particular designed as a drive motor for a motor vehicle, which is characterized by a particularly advantageous mounting of a shaft in its motor housing.

[0005] State of the art

[0006] Electric motors, including those used as drive motors in motor vehicles, are known in many different forms. Such electric motors have shafts that are rotatably mounted within a motor housing. For this purpose, the axial end regions of the shaft are typically each mounted in a bearing device, which in turn is accommodated in a housing part, for example in a housing cover. The housing cover is typically required to form a closable opening in the motor housing through which the shaft, which is for example a component of the rotor of a brushless electric motor, can be inserted into the motor housing. The housing cover therefore serves both to close the motor housing and to arrange and fasten the bearing device. This in turn means that the housing cover, which is for example designed as a die-cast part, is relatively solid ormust be mechanically stable and therefore has a relatively high weight. It is also mentioned that such a housing cover, designed as a cast part, is typically subjected to mechanical remachining to ensure compliance with diameter tolerances between the seat of the bearing device and the receptacle in the housing cover. In order to further position the shaft in a desired axial position in the housing, the prior art also usually provides for the use of a preload spring between the bearing device and the housing cover, which applies an axial force to the bearing device in the direction of the shaft.

[0007] Disclosure of the invention

[0008] The electric motor according to the invention with the features of claim 1 has the advantage of enabling a simplified mounting of the electric motor shaft in the housing. In particular, it eliminates the need for a relatively complex and expensive (considering the cost of a die-casting tool for a housing cover) and relatively heavy housing cover. Furthermore, the preload spring typically required in the prior art to generate the axial force applied to the shaft can be dispensed with.

[0009] The invention is based on the idea of ​​separating the function of the bearing receptacle, on the one hand, and the function of the housing closure, on the other, and implementing them using components that are each optimized for their own purposes. Therefore, an electric motor according to the invention with the features of claim 1 has a shaft arranged in a motor housing, which is rotatably mounted at a front end region by means of a bearing device. Furthermore, the motor housing has, on the side facing the bearing device, a housing opening arranged concentrically to the shaft, which is closed by means of a cover element. Finally, the bearing device is arranged in a bearing receptacle element that is separate from the cover element, and the bearing receptacle element is radially and axially fixed in a housing receptacle of the motor housing.

[0010] Advantageous developments of the electric motor according to the invention are listed in the subclaims.

[0011] It is particularly advantageous for exerting an axial preload force on the shaft if the bearing receiving element is designed to be elastic, at least in sections, when viewed in the direction of a longitudinal axis of the shaft. This allows the preload force to be generated on the shaft via the bearing receiving element in conjunction with the axially fixed receptacle of the bearing receiving element realized in the housing receptacle. In a particularly preferred structural embodiment of such a bearing receiving element, the bearing receiving element is designed in the form of a bearing star with a receptacle for the bearing device and several, preferably three, retaining arms projecting radially from the receptacle at equal angular intervals.

[0012] In order to eliminate the need for additional fastening elements for securing the bearing support element in the housing receptacle, it is preferably provided that the bearing support element is held in the housing receptacle by a press or clamp connection. Furthermore, this allows the (axial) desired position of the bearing support element in the housing to be achieved in a simple manner by axial pressing.

[0013] In order to realize, on the one hand, a simple assembly by simply pressing the bearing receiving element into the housing receptacle, and on the other hand to be able to generate the above-mentioned axial preload on the bearing device or the shaft, it is particularly preferably provided that a displacement path for the axial positioning of the bearing receiving element is formed between the housing receptacle and the bearing receiving element, viewed in the direction of the longitudinal axis of the shaft.

[0014] Such a bearing support element can be formed in a particularly simple and relatively inexpensive manner by designing it as a stamped / bent part made of sheet metal.

[0015] In order to limit the axial length of the motor housing with regard to the two separate elements of the housing cover and the bearing support element or to enable the electric motor to be as compact as possible, a further advantageous design embodiment of the electric motor provides that a base section of the support of the bearing support element facing the housing opening forms a common plane together with the holding arms in a direction perpendicular to the longitudinal axis of the shaft.

[0016] The bearing device can be secured particularly easily in the receptacle of the bearing support element if the bearing device is pressed into the receptacle. To keep the weight of the electric motor as low as possible, the cover element is also designed to be made of plastic or light metal.

[0017] The electric motor according to the invention described so far is preferably used as a drive motor in a motor vehicle.

[0018] Further advantages, features and details of the invention will become apparent from the following description of preferred embodiments of the invention and from the drawings.

[0019] Short description of the drawings

[0020] Fig. 1 shows a perspective view of an electric motor with a front end of a shaft in the area of ​​a housing opening,

[0021] Fig. 2 a section through the electric motor according to Fig. 1 with a mounted housing cover and

[0022] Fig. 3 shows a bearing receiving element as used in the electric motor according to Figs. 1 and 2, in a plan view.

[0023] Embodiments of the invention

[0024] Identical elements or elements with the same function are provided with the same reference numbers in the figures.

[0025] The figures show an axial end region of an electric motor 10, such as is used in the context of electromobility, in particular as a drive motor for a motor vehicle (not shown). However, the electric motor 10 and its use should not be limited to such an application within the scope of the invention. The electric motor 10 has a multi-part motor housing 12, which is designed, for example, as a die-cast aluminum part or similar. At an end region of the motor housing 12, the motor housing 12 has a housing opening 14, which can be closed by means of a cover element 16 (only shown in Fig. 2). The cover element 16 is designed, for example, as a deep-drawn part made of sheet metal or light metal or even of plastic, in particular with a view to keeping the weight as low as possible. In particular, the cover element 16 is also designed in such a way that the ingress of media orMoisture is prevented from entering the interior of the motor housing 12. For this purpose, a seal (not shown) can be arranged, for example, between the motor housing 12 or the housing opening 14 and the cover element 16. The detachable connection of the cover element 16 is made possible, for example, by screw connections.

[0026] A rotor 18 of the internal-rotor, brushless electric motor 10 is arranged within the motor housing 12. As is known per se, the rotor 18 has a rotatably mounted shaft 20. Magnetic elements are arranged on the shaft 20 in a known manner, interacting with a stator 22 having wire windings 24 that radially surrounds the rotor 18. To control or energize the wire windings 24, it is also necessary to detect the angular position of the rotor 18. For this purpose, magnetic elements 28 are arranged on the front end 26 of the rotor 18 or the shaft 20, which magnetic elements can be detected in a known manner using a sensor element (not shown).

[0027] In order to rotatably support the shaft 20 with its longitudinal axis 30 in the motor housing 12, the area of ​​the shaft end 26 is radially enclosed by a bearing device 32. The bearing device 32 is in turn radially received in a receptacle 34 of a bearing receiving element 36. For this purpose, the bearing receiving element 36 has an approximately cup-shaped receiving section 38 with a through opening or hole 40 in a base section 41. The bearing device 32 is held radially and axially fixed, in particular by being pressed into the receiving section 38 of the receptacle 34.

[0028] The bearing receiving element 36 is in the form of a bearing star 42 with three holding arms 44, 45 and 46 arranged at equal angular intervals around the longitudinal axis 30 of the shaft 20, which protrude radially from the receiving section 38. The approximately strip-shaped holding arms 44 to 46, each of which is identical in design, extend from the receiving section 38 into the region of a housing receptacle 48 of the motor housing 12. The housing receptacle 48 is designed, as can be seen in particular from Figs. 1 and 2, in the form of a housing wall section 50 which extends radially around the axis of rotation 30.

[0029] The bearing receiving element 36 is designed in particular as a stamped / bent part made of sheet metal, wherein the three holding arms 44 to 46 extend from a flange 52 arranged radially on the side facing away from the hole 40 of the receiving section 38 and radially surrounding the receiving section 38. As shown in Figs. 1 and 2, the holding arms 44 to 46 are each bent over a bent intermediate section 54 arranged approximately obliquely or at an angle to the axis of rotation 30 to form a holding section 55 running parallel to the base section 41 of the receptacle 38. The holding sections 55, together with the base section 41, form a common end plane 53 on the side facing the cover element 16 in a plane running perpendicular to the longitudinal axis 30.The holding sections 55, in turn, have two bent first end regions 56 with a second end region 59 arranged therebetween, which are separated from one another by slots 57, 58 extending radially relative to the longitudinal axis 30. As can be seen particularly clearly from Fig. 1, the (central) second end region 59 has a greater length, viewed in the direction of the longitudinal axis 30, than the two laterally arranged first end regions 56.

[0030] The dimensioning of the bearing receiving element 36 or the holding arms 44 to 46 in relation to the size of the housing receptacle 48 is such that when the bearing receiving element 36 is inserted into the housing receptacle 48, a press fit is formed between the end regions 56, 59 of the holding arms 44 to 46 and the housing receptacle 48, which enables radial and axial fixation of the bearing receiving element 36 in the housing receptacle 48 during operation of the electric motor 10. The (longer) second end regions 59 cause radial centering of the bearing receiving element 36 relative to the longitudinal axis 30, while the first end regions 56, due to their geometry, can claw into the housing receptacle 48 when a force is exerted on the bearing receiving element 36 opposite to the direction of a preload force F visible in Fig. 2. The first end regions 56 thus serve to axially fix the bearing support element 36 in the housing support 48.

[0031] In particular, it can be seen from Fig. 1 that the housing receptacle 48 has a displacement path 60 running parallel to the rotational axis 30 for axially positioning the holding arms 44 to 46 in a desired position. Furthermore, the bearing receiving element 36 is designed to be elastic due to the curved or obliquely arranged intermediate sections 54 such that the axial preload force F on the shaft 20 or the rotor 18 is enabled by pressing the bearing receiving element 36 sufficiently deep into the housing receptacle 48 from the bearing receiving element 36 via the bearing device 32.

[0032] Furthermore, it can be seen from Fig. 2 that the cover element 16 is adapted to the shape of the bearing receiving element 36 in such a way that an approximately constant size gap 64 is formed between the two mentioned elements, which enables the axial mobility of the bearing receiving element 36 relative to the cover element 16.

[0033] The electric motor 10 and the bearing support element 36 described so far can be modified in many different ways without deviating from the inventive concept.

Claims

Claims 1. Electric motor (10), with a shaft (20) arranged in a motor housing (12) which is rotatably mounted at a front end region by means of a bearing device (32), wherein the motor housing (12) has a housing opening (14) on the side facing the bearing device (32) which is closed by means of a cover element (16), wherein the bearing device (32) is arranged in a bearing receiving element (36) separate from the cover element (16), and wherein the bearing receiving element (36) is fastened radially and axially fixed in a housing receptacle (48) of the motor housing (12).

2. Electric motor according to claim 1, characterized in that the bearing receiving element (36) is designed to be elastic at least in sections when viewed in the direction of a longitudinal axis (30) of the shaft (20).

3. Electric motor according to claim 2, characterized in that the bearing receiving element (36) is designed in the form of a bearing star (42) with a receptacle (34) for the bearing device (32) and several, preferably three, holding arms (44 to 46) projecting radially from the receptacle (34) at equal angular intervals around the longitudinal axis (30).

4. Electric motor according to claim 2 or 3, characterized in that the bearing receiving element (36) is received in the housing receptacle (48) by a press or clamp connection.

5. Electric motor according to claim 4, characterized in that the bearing receiving element (36) for forming the press or clamp connection (36) has a plurality of first end regions (56) and second End regions (59) which have a different geometry, wherein the first end regions (56) are designed to form an axial fixation and the second end regions (59) are designed to form a radial centering of the bearing receiving element (36) in the housing receptacle (48).

6. Electric motor according to claim 4 or 5, characterized in that a displacement path (60) for axially positioning the bearing receiving element (36) in the direction of the longitudinal axis (30) of the shaft (20) is formed between the housing receptacle (48) and the bearing receiving element (36).

7. Electric motor according to one of claims 1 to 6, characterized in that the bearing receiving element (36) is designed as a stamped / bent part made of sheet metal.

8. Electric motor according to one of claims 3 to 7, characterized in that a bottom section (41) of the receptacle (34) of the bearing receiving element (36) facing the housing opening (14) forms a common plane (53) together with the holding arms (44 to 46) in a direction perpendicular to the longitudinal axis (30) of the shaft (20).

9. Electric motor according to one of claims 3 to 8, characterized in that the bearing device (32) is pressed into the receptacle (34) of the bearing receiving element (36).

10. Electric motor according to one of claims 1 to 9, characterized in that the cover element (16) is made of plastic or light metal.

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