End shield for an electric motor, electric motor, and production method

Abstract

The present invention relates to an end shield for an electric motor, in particular for or in an electric power steering system, having: a bearing portion designed for supporting a motor shaft; and a sealing portion designed for a sealing connection with respect to a motor housing, wherein the sealing portion has a peripheral seal which is oriented axially with respect to the bearing portion and is designed to receive a peripheral seal and to receive an axial edge portion of the motor housing in a manner squeezing the seal. The present invention also relates to an electric motor for an electric power steering system having such an end shield, and to a method for producing same.

Description

[0001]End shield for an electric motor, electric motor and method for manufacturing it FIELD OF THE INVENTION The present invention relates to an end shield for an electric motor, in particular for or in an electric power steering system, an electric motor for an electric power steering system and a method for manufacturing an electric motor, in particular an electric motor for an electric power steering system. TECHNICAL BACKGROUND Although the present invention and the problem underlying it are described in more detail below using an electric motor for an electric power steering system, the invention is not limited to this, but can be applied to a wide variety of electric motors requiring a tight connection between the end shield and the motor housing. Electric power steering systems, also known as electro-mechanical steering or EPS (Electric Power Steering) orMDPS (Motor Driven Power Steering) systems offer a host of advantages over traditional hydraulic power steering systems, including reduced fuel consumption, significant space savings, and lower integration costs. Furthermore, they enable the implementation of software-controlled improvements to the driving experience, as well as assistance systems and even automated driving. Naturally, this is applicable to all types of vehicles with electric power steering, for example, in addition to motor vehicles, also trucks, work machines, racing cars, and the like. CN217087639U describes an electric power steering system in which a housing is coupled to a bearing plate by a flange connection and sealed by a circumferential O-ring seal arranged in the fold of the flange connection.The O-ring seal is arranged on an outer side in the flange area of ​​the bearing shield and on an inner side in the flange area of ​​the housing. One axial end of the housing thus protrudes beyond the seal in the direction of the bearing shield and terminates after the seal on the bearing shield. To ensure the sealing effect during assembly, a circumferential chamfer is provided on the flange-side end of the inner wall of the housing, into which the O-ring fits during assembly. SUMMARY OF THE INVENTION Against this background, the present invention is based on the object of specifying an improved sealing connection between the bearing shield and the motor housing.According to the invention, this object is achieved by a bearing plate for an electric motor having the features of patent claim 1 and / or by an electric motor for an electric power steering system having the features of patent claim 6 and / or by a method for producing an electric motor having the features of patent claim 9. Accordingly, the following is provided: - A bearing plate for an electric motor, in particular for or in an electric power steering system, having: a bearing section designed to support a motor shaft; and a sealing section designed for a sealing connection to a motor housing, wherein the sealing section has a circumferential sealing groove which is axially aligned with the bearing section and is designed to receive a circumferential seal and to receive an axial edge section of the motor housing in a way that squeezes the seal.- An electric motor for an electric power steering system, with a bearing shield according to the invention. - A method for producing an electric motor, in particular an electric motor according to the invention, comprising the steps of: inserting a circumferential seal into an axially aligned sealing groove of a bearing shield; inserting an axial edge of a motor housing into the sealing groove such that the seal is squeezed; and fastening the motor housing to the bearing shield. The finding underlying the present invention is that a housing section projecting beyond the seal on the bearing shield requires additional installation space and thus increases the overall axial size of an electric motor. The idea underlying the present invention is to have the motor housing resting with its axial end on the seal or to have the seal end squeezing in the axial direction.For this purpose, a sealing groove is provided in the sealing section of the bearing shield, which accommodates the seal and fixes it in all other translational degrees of freedom. In this way, the motor housing advantageously does not need to protrude beyond the seal, but ends directly on the seal. This advantageously saves the protruding length of the motor housing, and the motor housing and the entire motor can be designed with a correspondingly shorter axial length. For example, the motor housing can be materially connected to the bearing shield in the position that squeezes the seal. This ensures continued simple assembly while fully fulfilling the sealing requirements. According to the invention, a structural reinforcement of the motor housing is also provided by the fact that the motor housing is circumferentially accommodated in the sealing groove of the bearing shield.In this way, the motor housing can advantageously withstand higher loads according to the invention and / or be designed to be optimized with regard to the use of materials and its weight. Overall, the power density of the electric motor is thus improved according to the invention, both in relation to the total weight and in relation to the required installation space. Advantageous embodiments and further developments emerge from the further subclaims and from the description with reference to the figures of the drawing. According to one embodiment, the bearing section is formed on a radially inner side of the sealing section and a flange region is provided on a radially outer side, so that the sealing groove is arranged between the bearing section and the flange region. The seal is therefore advantageously separated from the flange region orits mounting points are arranged independently and the tightness of the electric motor is thus ensured regardless of its assembly by means of the flange area. According to one embodiment, the sealing groove is arranged on a shoulder of the sealing section. In this way, a structurally stable circumferential receptacle for the edge section of the motor housing is provided. The shoulder can advantageously be used simultaneously to connect the motor housing to the bearing plate, for example for a materially integral connection. According to one development, the shoulder has a preparation for connecting the motor housing to the bearing plate. For example, this can be a weld seam preparation. According to one development, the preparation is formed on an outer edge of the shoulder.In particular, the preparation as a chamfer is intended to optimize a material-to-material connection, for example to accommodate the volume of filler material during welding. According to one embodiment of an electric motor, a motor shaft, a motor housing receiving the motor shaft, and a circumferential seal are provided. The seal is designed to seal the motor housing against the bearing plate supporting the motor shaft and is received in the sealing groove of the bearing plate. An axial edge of the motor housing is inserted into the sealing groove, and the motor housing is fastened to the bearing plate in such a way that the axial edge squeezes the seal. In this way, the motor housing advantageously does not need to protrude beyond the seal, but ends with its front edge directly on the seal.This eliminates the length of the motor housing that protrudes beyond the seal, and the motor housing and the entire motor can be designed with a shorter axial length. The fact that the motor housing is accommodated all the way around in the sealing groove of the bearing plate also provides structural reinforcement of the motor housing. In this way, the motor housing can advantageously withstand greater stresses and / or be optimized in terms of material usage and weight compared to a design with conventional sealing. According to a further development, the motor housing also has a radial shoulder that is materially connected to the shoulder of the sealing section. The radial shoulder projects radially outwards beyond the motor housing. The motor housing can therefore be easily materially connected to the bearing plate.The radial shoulder of the motor housing can also advantageously function as a stop, in particular against the shoulder of the bearing shield, in order to apply a predetermined crush force to the seal without the risk of destroying it. According to a further development, the radial shoulder has a preparation for connecting the motor housing to the bearing shield. In particular, both the shoulder of the bearing shield and the radial shoulder of the motor housing have corresponding preparations. For example, this can be a weld seam preparation. According to a further development, the preparation is formed on an outer edge of the shoulder(s). In particular, the preparation is provided as a chamfer to optimize a material-to-material connection, for example to absorb the volume of filler material during welding.According to one embodiment of the manufacturing method, the axially aligned sealing groove is formed in a shoulder of a sealing section of the bearing shield, wherein the motor housing has a radial shoulder and the fastening of the motor housing to the bearing shield comprises a materially bonded connection of the shoulder of the motor housing to the shoulder of the bearing shield. The shoulder of the bearing shield can thus advantageously be used not only to form the sealing groove, but also simultaneously to connect the motor housing to the bearing shield. The radial shoulder of the motor housing projects radially outwards beyond the motor housing and preferably ends flush with the shoulder of the bearing shield. The radial shoulder of the motor housing can also advantageously function as a stop, in particular against the shoulder of the bearing shield, in order to apply a predetermined pinch to the seal without any risk of destroying it.Furthermore, this provides an easily accessible joint for a material-to-material connection, for example by welding. The above embodiments and further developments can be combined with one another as desired, where appropriate. Further possible embodiments, further developments, and implementations of the invention also include combinations of features of the invention described previously or below with regard to the exemplary embodiments that are not explicitly mentioned. In particular, the person skilled in the art will also add individual aspects as improvements or additions to the respective basic form of the present invention. TABLE OF CONTENTS OF THE DRAWING The present invention is explained in more detail below with reference to the exemplary embodiments shown in the schematic figures of the drawing. They show: Fig. 1 a cross-sectional view of a bearing plate; Fig. 2 a cross-sectional view of an electric motor; Fig.3 shows a detailed view of a sealing section of the electric motor according to Fig. 2; Fig. 4 shows a flow diagram of a method for manufacturing an electric motor; and Fig. 5 shows an illustration of the method according to Fig. 4. The accompanying drawing figures are intended to provide a further understanding of the embodiments of the invention. They illustrate embodiments and, in conjunction with the description, serve to explain principles and concepts of the invention. Other embodiments and many of the aforementioned advantages will become apparent with reference to the drawings. The elements of the drawings are not necessarily shown to scale. In the drawing figures, identical, functionally identical, and acting identical elements, features, and components are provided with the same reference numerals, unless otherwise stated. DESCRIPTION OF EMBODIMENTS Fig. 1 shows a cross-sectional view of an end shield 1.The bearing shield 1 is designed for an electric motor 10 (see Fig. 2). In particular, it is a bearing shield for an electric power steering system or in an electric power steering system of a motor vehicle. The bearing shield 1 is designed as a circumferential support structure and serves to transfer loads acting on a motor shaft. A bearing section 2 of the bearing shield is designed to support the motor shaft 11 (see Fig. 2). For this purpose, it forms a radially inner part of the bearing shield 1 and has a bearing seat 3 which is designed to receive a suitable shaft bearing 19 (see Fig. 2), for example a rolling bearing. A flange region 7 is provided on a radially outer side of the bearing shield 1. This is provided here purely by way of example with a bore 7A and is designed for attachment to a vehicle structure.Instead of a bore, in further embodiments, a variety of differently designed fastening means can of course be provided on the flange area 7, either optionally or additionally. A sealing section 4 of the bearing plate 1 is provided radially between the flange area 7 and the bearing section 2. The sealing section 4 is designed for a sealing connection to a motor housing 12 (see Fig. 2), i.e., a connection sealed against the motor housing 12. According to the embodiment shown here, the sealing section 4 is designed to receive a circumferential seal 5, for example an O-ring seal. For this purpose, the sealing section 4 has a circumferential sealing groove 6 which is axially aligned with the bearing section 2 and into which the circumferential seal 5 can be received. Although a seal 5 is shown here for better illustration, it does not constitute part of the bearing plate 1.Rather, the seal 5 is only inserted into the sealing groove 6 when the bearing plate 1 is assembled with a motor housing 12 of an electric motor (see Fig. 5). The sealing groove 6 is arranged on a shoulder 8 of the sealing section 4. The shoulder 8 is designed for the structural connection of the bearing plate to the motor housing and accordingly protrudes in the axial direction relative to the flange area 7. The sealing groove 6 is designed to receive an axial edge section 13 of the motor housing 12. This means that an edge at the open end of the motor housing 12 can be inserted into the sealing groove 6. To ensure optimal sealing, the edge section 13 can be inserted into the sealing groove 6 far enough that a seal 5 arranged therein is squeezed or can be squeezed in a sealing manner. For this purpose, the sealing groove 6 has a depth which exceeds the thickness or height of the seal 5. Fig. 2 shows a cross-sectional view of an electric motor 10.This is an electric motor 10 for an electric power steering system with the bearing shield 1 according to Fig. 1. A motor shaft 11 of the electric motor 10 is accommodated in a motor housing 12. A bearing for the motor shaft 11 with suitable shaft bearings 19, here purely exemplary designed with rolling bearings, is provided at a closed end 15 of the motor housing 12 on the one hand and in the bearing section 2 of the bearing shield 1 on the other. A rotor 16 is fastened to the motor shaft 11 and a stator 17 is fastened to the motor housing 12. The bearing shield 1 is arranged at an open end 18 of the motor housing 12. A circumferential seal 5 is accommodated in the sealing groove 6 of the bearing shield 1. The seal 5 is designed to seal the motor housing 12 against the bearing shield 1. An axial edge section 13 of the motor housing 12 is inserted into the sealing groove 6 and thus squeezes the seal 5.The motor housing 12 has an outwardly projecting radial shoulder 14 at the edge region, which is designed here, for example, as a circumferential projection. The radial shoulder 14 functions, on the one hand, as a stop interacting with the shoulder 8 and, on the other hand, is integrally connected to the shoulder 8 of the sealing section 4. The radial shoulder 14 of the motor housing 12 is optional. In further embodiments, therefore, alternatively or additionally, other fastening means for fastening the motor housing 12 to the bearing plate 1 and / or other stop means for providing a predetermined pinch of the seal 5 can also be provided. Fig. 3 shows a detailed view of a sealing section 4 of the electric motor 10 according to Fig. 2.The two shoulders 8 and 14 can be seen in detail here; they act as stops against each other, so that a predetermined distance is set between the end of the edge section 13 and a groove base of the sealing groove 6 for a predetermined pinching of the seal 5. Shown is a correspondingly pinched state in a predetermined manner or a predetermined deformation of the seal 5, which leads to complete contact with the side surfaces and the base of the sealing groove 6 without damaging the seal 5 and thus provides a high level of tightness. Furthermore, it can be seen that the edge section 13 of the motor housing 12 is slightly chamfered, i.e., has a relatively flat bevel 20 on the outer edge, which facilitates insertion into the sealing groove 6.In the embodiment shown, a material-to-material connection (not explicitly shown here) is also provided between the bearing plate 1 and the motor housing 12, which is formed between the shoulder 8 of the bearing plate 1 and the radial shoulder 14 of the motor housing 12. For this purpose, the shoulder 8 has a formed preparation 9 on an outer edge for the material-to-material connection of the motor housing 12 to the bearing plate 1. By way of example, the embodiment shown here is a chamfer for seam preparation of a welded joint. Fig. 4 shows a flow diagram of a method for producing an electric motor. The method for producing an electric motor 10 is, in particular, a method for producing an electric motor for an electric power steering system, as shown in Figures 2 and 3.A first step S1 of the method includes inserting a circumferential seal 5 into an axially aligned sealing groove 6 of a bearing plate 1. A further step S2 includes inserting an axial edge section 13 of a motor housing 12 into the sealing groove 6 such that the seal 5 is squeezed. A third step S3 includes fastening the motor housing 12 to the bearing plate 1. Fastening the motor housing 12 to the bearing plate 1 can comprise a materially bonded connection of the motor housing to the shoulder 8 of the bearing plate 1. For this purpose, the axially aligned sealing groove 6 is formed in a shoulder 8 of a sealing section 4 of the bearing plate 1, wherein the motor housing 12 has a radial shoulder 14 and the shoulder 8 of the bearing plate 1 is connected to the radial shoulder 14, for example by welding.If the radial shoulder 14 is provided, the insertion S2 of an axial edge section 13 can be limited to a predetermined dimension for pinching the seal 5 by a stop of the radial shoulder 14 with the axially projecting shoulder 8 of the bearing plate 1. Fig. 5 additionally shows an illustration of the method according to Fig. 4. The insertion S1 of the seal 5 into the sealing groove 6 and the insertion S2 of the edge section 13 into the sealing groove 6 are each symbolized by arrows in an exploded view of the components. Although the present invention has been fully described above using preferred exemplary embodiments, it is not limited thereto, but can be modified in many different ways. For example, instead of an O-ring seal, a wide variety of other types of circumferential seals can be inserted into the sealing groove for assembly or provided in the electric motor.In particular, it may also be a seal that is not solid at the time the circumferential seal is inserted, such as a sealing paste or the like that hardens later, which is inserted circumferentially into the sealing groove. For example, it would be conceivable for a non-solid seal to be activated and / or hardened by the heat introduced for the material-to-material connection, in particular welding. In the preceding exemplary embodiment, the bearing plate 1 is shown purely by way of example as a cast part with comparatively large radii, wherein at least the sealing groove 6, the shoulder 8 and the bearing seat 3 are machined surfaces. In further embodiments, however, the bearing plate 1 may of course also be manufactured in a different way, for example a milled part, an additively manufactured part, a pressed part, or the like.List of reference symbols 1 bearing shield 2 bearing section 3 bearing seat 4 sealing section 5 seal 6 sealing groove 7 flange area 7A bore 8 shoulder 9 preparation, chamfer 10 electric motor 11 motor shaft 12 motor housing 13 edge section 14 radial shoulder 15 closed end 16 rotor 17 stator 18 open end 19 shaft bearing 20 chamfer.

Claims

PATENT CLAIMS 1. A bearing plate (1) for an electric motor (10), in particular for or in an electric power steering system, comprising: a bearing section (2) designed to support a motor shaft (11); and a sealing section (4) designed for a sealing connection to a motor housing (12), wherein the sealing section (4) has a circumferential sealing groove (6) axially aligned with the bearing section (2), which is designed to receive a circumferential seal (5) and to receive an axial edge section (13) of the motor housing (12) in a manner that squeezes the seal (5).

2. A bearing plate according to claim 1, characterized in that the bearing section (2) is formed on a radially inner side of the sealing section (4), and a flange region (7) is provided on a radially outer side, so that the sealing groove (6) is arranged between the bearing section (2) and the flange region. 3.End shield according to one of the preceding claims, characterized in that the sealing groove (6) is arranged on a shoulder (8) of the sealing section (4).

4. End shield according to claim 3, characterized in that. that the shoulder (8) has a preparation (9) for connecting the motor housing to the bearing plate.

5. Bearing plate according to claim 3, characterized in that the preparation (9) is formed on an outer edge of the shoulder (8), in particular as a chamfer for a material-to-material connection.

6. Electric motor (10) for an electric power steering system, with a bearing plate (1) according to one of the preceding claims. 7.Electric motor according to claim 6, characterized in that a motor shaft (11), a motor housing (12) receiving the motor shaft, and a circumferential seal (5) are also provided, wherein the seal (5) is designed to seal the motor housing (12) against the bearing plate (1) supporting the motor shaft (11) and is received in the sealing groove (6) of the bearing plate (1), wherein an axial edge section (13) of the motor housing (12) is inserted into the sealing groove (6) and the motor housing (12) is fastened to the bearing plate (1) in such a way that the axial edge section (13) squeezes the seal.

8. Electric motor according to claim 6 or 7, characterized in that the bearing plate (1) is designed according to one of claims 3 to 5 and the motor housing (12) has a radial shoulder (14) which is materially connected to the shoulder (8) of the sealing section (4).

9. A method for producing an electric motor (10), in particular an electric motor for an electric power steering system according to one of claims 6 or 7, comprising the steps of: inserting (S1) a circumferential seal (5) into an axially aligned sealing groove (6) of a bearing plate (1); inserting (S2) an axial edge section (13) of a motor housing (12) into the sealing groove (6) such that the seal (5) is squeezed; and fastening (S3) the motor housing (12) to the bearing plate (1).

10. The method according to claim 9, characterized in that the axially aligned sealing groove (6) is formed in a shoulder (8) of a sealing section (2) of the bearing plate (1), wherein the motor housing (12) has a radial shoulder (14) and the fastening (S3) of the motor housing (12) to the bearing plate (1) comprises a materially bonded connection of the shoulder (14) of the motor housing to the shoulder (8) of the bearing plate (1).

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