Electric motor with deep-drawn motor housing

Abstract

The invention relates to an electric motor having a deep-drawn motor housing with a base (3) and an opening (4) opposite the base, which opening is adjoined by a flange (5) having at least one partial shaping (9, 10) adjacent to the opening, which partial shaping (9, 10) is formed axially and has a bearing surface (16) for components of the electric motor, the axial position of which in the axial direction is calibrated with respect to a base surface (17) formed on the motor housing during deep-drawing, and the radial position of which in the radial direction is calibrated by means of the opening (4) as a reference surface.

Description

TECHNICAL FIELD

[0001] The present invention relates to an electric motor. BACKGROUND

[0002] Electric motors known as internal rotor motors have a rotor which contains the motor shaft and is rotatably mounted in a housing, on which a permanent magnet is arranged, and a stator is arranged around the motor, which carries a plurality of windings on an iron core. When suitably controlled, the windings generate a magnetic field which drives the rotor to rotate, the windings are usually designed in three phases and three electrical connections are provided accordingly, through which the windings can be connected to a control unit (ECU). The ends of the windings are contacted by busbars which can be encapsulated in a busbar unit.

[0003] In electric motors, the components (stator and rotor) must be axially aligned to achieve the required boundary parameters during operation. If the electric motor has a deep-drawn motor housing, the axial alignment is usually specified by a shoulder or a protrusion on the inner geometry of the motor housing to facilitate the assembly operation. Radial cutting and / or embossing operations or the formation of a circumferential shoulder for this purpose are not desirable because they have many disadvantages. With radial embossing, there are limitations in terms of the achievable flatness, which mainly depends on the wall thickness of the motor housing, the tightness of the motor housing and the influence on the geometry of the housing around the embossed points. Furthermore, due to the radial stamping process, the manufacturing tolerances are relatively high and the necessary reference plane usually does not come into play. When a circumferential shoulder is provided, it is disadvantageous to increase the installation space of the housing and to form an annular surface which exceeds the requirements. SUMMARY

[0004] The object of the present invention is to provide an electric motor with a motor housing which is easy to manufacture and enables precise axial alignment of the components.

[0005] This object is solved by an electric motor having the following features.

[0006] For the geometric description of the electric motor, with respect to the longitudinal axis of the motor housing, we mean by radial direction the direction of the distance from the longitudinal axis and by circumferential direction the tangential direction to the radius arranged in the radial direction, the direction of the longitudinal axis is also referred to as axial.

[0007] An electric motor having a deep-drawn motor housing with a base and an opening opposite the base, the opening being connected to a flange, the flange having at least one locally formed portion adjacent to the opening, the locally formed portion being formed in axial direction and having a bearing surface for a component of the electric motor, the axial position of the bearing surface being aligned with respect to a bottom surface of the motor housing formed during deep-drawing, the radial position of the bearing surface being aligned with respect to the opening as a reference surface. The position of the at least one bearing surface can be determined by simple manufacturing, so that the component of the electric motor placed on the bearing surface is aligned accordingly, which simplifies the assembly process of the electric motor. Thus, a severe radial deformation of the deep-drawn motor housing or the circumferential shoulder can be avoided.

[0008] Preferably, the at least one locally formed portion is formed by stamping the flange.

[0009] Preferably, the position of the bearing surface is aligned by means of an embossing process.

[0010] Preferably, the surface of the bottom of the motor housing is a bearing surface of a rotor bearing, which is functional.

[0011] In a preferred embodiment, the component of the electric motor is a busbar unit. Thus, the position of the busbar unit is defined unambiguously and additional fastening options on the motor housing do not have to be created.

[0012] Optionally, the flange has a substantially polygonal cross-section, each flange corner being provided with a screw socket fixing point, each flange corner having two locally formed portions, each locally formed portion forming a curved edge of the motor housing between the screw socket fixing point and the opening. The locally formed portions move the curved edge from the opening towards the screw socket fixing point, so that the flange is significantly improved in mechanical stability.

[0013] If there are multiple contact surfaces, preferably, the contact surfaces are flat, parallel and in the same plane.

[0014] Preferably, the cross section of each partial shaping is approximately a right-angled triangle, the side opposite the right angle is formed by the opening of the motor housing, the other two sides extend parallel to the outer side of the flange. Preferably, the two partial shapings of the flange corner are arranged spaced apart from each other and mirror-symmetrically with respect to a symmetry axis through the screw-in fixing point and the longitudinal axis of the motor housing. Preferably, the rectangular envelope of the two partial shapings of the flange corner encloses the respective screw-in fixing point, whereby the screw-in fixing point is located in the radially outermost corner of the envelope. Preferably, in the region of the screw-in fixing point, the outer side of the flange and the two sides of the partial shaping adjacent to the screw-in fixing point and their extension enclose an imaginary square, in the center of which the screw-in fixing point is arranged. Preferably, the imaginary square defines a planar area whose dimensions are adapted to the diameter of the fastening element for the screw-in fixing point.

[0015] Preferably, the bearing surface is formed approximately semicircular near the opening. The busbar unit can have a corresponding protrusion which abuts on the contact surface outside the cylindrical geometry.

[0016] Preferably, the motor is an internal rotor motor, the rotor of which has magnets, the stator being arranged around the rotor, the core of the stator having a plurality of windings, the ends of which are electrically contacted by the busbar unit.

[0017] Furthermore, a method for machining a deep-drawn motor housing of an electric motor is provided, the motor housing having a bottom and an opening opposite the bottom, the opening adjoining a flange. The method comprises the following steps:

[0018] a) deforming the flange in at least one region adjoining the opening in the axial direction to form at least one partial shaping,

[0019] b) forming a bearing surface in the region of the at least one partial shaping, wherein the axial position of the bearing surface with respect to the surface formed on the bottom of the motor housing during deep-drawing and the radial position of the bearing surface with respect to the opening are calibrated during the shaping.

[0020] The above-mentioned advantages are that, preferably, the shaping in step a) and the shaping in step b) are carried out by means of an embossing process, respectively. Depending on the degree of deformation, the bearing surface can be produced in one or more deformation steps. The shaping process comprises a final calibration process to ensure the appropriate accuracy of the reference surface in the embossing process.

[0021] The motor housing can be designed in detail according to the above-mentioned method, preferably it can be part of an internal rotor motor, preferably the calibration surface is a bearing surface of a rotor bearing, the bearing surface preferably serving to support a busbar unit. BRIEF DESCRIPTION OF DRAWINGS

[0022] The preferred embodiments of the present invention will now be explained in more detail with reference to the accompanying drawings. Similar or similarly functioning components are indicated by the same reference numerals in the drawings, which indicate:

[0023] Figure 1 This is a three-dimensional view of the motor casing from below;

[0024] Figure 2 yes Figure 1 A diagram showing one corner of the motor housing viewed from above;

[0025] Figure 3 yes Figure 1 A perspective view of the corner of the motor housing, in which the bus unit is inserted into the motor housing;

[0026] Figure 4 yes Figure 1 A perspective view of the central corner region, where the busbar units are not shown; and

[0027] Figure 5 It is half of the longitudinal section passing through the motor housing. Detailed Implementation

[0028] Figure 1 The diagram shows a deep-drawn motor housing 1. The motor housing 1 is pot-shaped, with a generally cylindrical outer surface 2, a base 3, and an opening opposite the base 3. The opening is surrounded circumferentially by a flange 5. The flange 5 has a generally rectangular base with four flange corners 6; only three of these corners 6 are shown in the diagram. These flange corners 6 are evenly distributed circumferentially, and each flange corner 6 has a through hole 7 serving as a threaded fixing point 8. In the region of the flange corner 6, the flange 5 also has protrusions 9 and 10 extending downwards along the direction of the base 3. In the illustrated case, each flange corner 6 corresponds to two partially formed portions 9 and 10, which are protrusions and arranged mirror-symmetrically about an axis of symmetry 100. This axis of symmetry 100 is connected to the central axis or longitudinal axis 200 of the motor housing, and to the central axis 300 of the corresponding threaded fixing point, which is perpendicular to the axis of symmetry 100. The two protrusions 9 and 10 of the flange corner are spaced apart circumferentially.

[0029] from Figure 2As can be seen in detail, the cross-sections of protrusions 9 and 10 each have two right-angled, restrictive sides 11 and 12, which extend parallel to the outer side of flange 5. Protrusions 9 and 10 connect radially inward to opening 4. The cross-section of each protrusion 9 and 10 is approximately triangular, with the side opposite the right angle formed by opening 4 of the motor housing. The rectangular envelope of the two protrusions 9 and 10 at the flange corner surrounds the corresponding threaded fixing point 8, which is located at the outermost corner of the envelope along the radial direction. In the region of the threaded fixing point, the outer side of the flange and the two sides of the protrusions near the threaded fixing point and their extensions form an imaginary square 13, with the threaded fixing point located at the center of the square. Other conventional cylindrical geometries are abandoned at the threaded fixing point. The imaginary square 13 defines a planar area whose size is adapted to the diameter of the through hole or the screw head that mates with the washer, so that this area can be connected as directly as possible to the opening in the motor housing.

[0030] The direct connection 14 between the right angles of the flange protrusions is parallel to the tangent of the opening 4 at the axis of symmetry 100, and is located radially between the screw-type fixing point 8 and the opening 4.

[0031] like Figure 3 As shown, protrusions 9 and 10 can serve as axial support surfaces for the busbar unit 15 of the electric motor, and support surface 16 is formed in protrusions 9 and 10 through an additional molding process (see...). Figure 4 Preferably, the forming process is a stamping process, the support surface 16 is flat and located in the same plane, and the support surface 16 can be formed in one or more deformation stages depending on the degree of deformation. The forming process includes a final calibration process to ensure the proper accuracy of the reference surface.

[0032] Through appropriate process design, the support surface 16 is calibrated together with another important functional surface; that is, the support surface 16 is re-stamped during the calibration process. Figure 5 It can be seen that the important functional surface is preferably the axial bearing support surface 17 for the bearing, which supports the rotor shaft of the motor at the end away from the opening. This type of bearing is also called a type B bearing. The axial bearing support surface 17 is arranged in the base 3 of the motor housing and is formed during deep drawing. Therefore, the axial position of the support surface 16 for the bus unit is defined by the distance a to the bearing support surface 17. In the radial direction, the reference surface is the opening 4 of the motor housing, also known as the flange hole.

[0033] The radial fixation of the busbar unit 15 can be ensured by the depth to which the support surface 16 is stamped into the protrusions 9 and 10. The contact surface 16 extends radially away from the opening and is approximately semi-circular in shape, see... Figure 4 Each protrusion 9 and 10 has a contact surface 16.

[0034] from Figure 3 As can be seen, the bus unit 15 has protrusions 18, which are placed only on every other support surface 16. However, it is also possible to select different numbers of protrusions for placement on the support surfaces.

[0035] The protrusion reduces the bending stress of the screw-type fixing point 8, and even with low material thickness or wall thickness, high mechanical rigidity of the motor housing can be achieved in the critical area of ​​the screw-type fixing point 8.

[0036] Parts of the motor housing are formed in the protruding area and deviate from the basic cylindrical shape. The protrusion can typically form one or more flat, parallel surfaces, thereby aligning the motor components axially and radially within the motor housing.

Claims

1. An electric motor having a deep-drawn motor housing (1) having a base (3) and an opening (4) opposite to the base (3), the opening (4) being adjacent to a flange (5) having at least one angle (6), characterized in that, The flange (5) has at least one partially formed portion (9, 10) adjacent to the opening, the partially formed portion (9, 10) being formed axially and having a support surface (16) for a component of the motor, the axial position of the support surface (16) being calibrated relative to the bottom surface (17) of the motor housing formed during deep drawing, and the radial position of the support surface (16) being calibrated by the opening (4) as a reference surface, and the support surface (16) being axially recessed into the at least one partially formed portion (9, 10), the support surface (16) supporting the component of the motor as it rests on the support surface (16), and the support surface (16) being offset circumferentially to one side of at least one corner (6) of the flange (5).

2. The electric motor according to claim 1, characterized in that, The at least one partially formed part (9, 10) is formed on the flange (5) by stamping.

3. The electric motor according to claim 1 or 2, characterized in that, The position of the support surface (16) is calibrated by an embossing process.

4. The electric motor according to claim 1 or 2, characterized in that, The bottom surface (17) of the motor housing is the bearing support surface of the rotor bearing.

5. The electric motor according to claim 1 or 2, characterized in that, The component of the electric motor is a bus unit (15).

6. The electric motor according to claim 1 or 2, characterized in that, The cross-section of the flange (5) is approximately polygonal. Each flange corner (6) is provided with a screw-type fixing point (8). Each flange corner (6) has two partial forming parts (9, 10). Each partial forming part has a support surface, and each partial forming part forms a curved edge of the motor housing (1) between the screw-type fixing point (8) and the opening (4).

7. The electric motor according to claim 6, characterized in that, Each of the local molding parts (9, 10) has a cross-section that is approximately a right triangle. The side opposite to the right angle is formed by the opening (4) of the motor housing, and the other two sides (11, 12) extend parallel to the outer side of the flange (5).

8. The electric motor according to claim 7, characterized in that, The rectangular envelope of the two partially formed portions (9, 10) of the flange corner surrounds the corresponding threaded fixing point (8), wherein the threaded fixing point (8) is arranged at the outermost corner of the envelope along the radial direction.

9. The electric motor according to claim 6, characterized in that, In the area of ​​the screw-type fixing point (8), the outer side of the flange and the two sides of the partially formed part near the screw-type fixing point and their extensions form an imaginary square (13), and the screw-type fixing point (8) is located at the center of the square.

10. The electric motor according to claim 9, characterized in that, The dimensions of the planar region defined by the imaginary square (13) are adapted to the diameter of the fastener used for the screw-type fixing point (8).

11. The electric motor according to claim 6, characterized in that, The support surface (16) is formed into an approximately semi-circular shape near the opening (4).

12. A method for processing a deep-drawn motor housing of an electric motor, the motor housing (1) having a bottom (3) and an opening (4) opposite to the bottom, the opening being adjacent to a flange (5), characterized in that, The method includes the following steps: a) Deform the flange (5) axially in at least one region adjacent to the opening (4) to form at least one partially shaped portion (9, 10). b) In the region of the at least one partially formed portion (9, 10), a support surface (16) is formed, wherein the axial position of the support surface (16) relative to the bottom surface (17) of the motor housing formed during deep drawing, and the radial position of the support surface (16) relative to the opening (4) are calibrated during forming. In step b), the axial and radial positions of the support surface (16) are calibrated by an embossing process.

13. The method according to claim 12, characterized in that, The molding in step a) and step b) are respectively carried out by an imprinting process.

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