Electric motor with deep-drawn motor housing

Abstract

The invention relates to an electric motor having a deep-drawn motor housing with flanges (5) adjoining the openings (4), the cross section of the flanges (5) being substantially polygonal, each flange corner (6) being provided with a screw socket fixing point (8), each flange corner (6) having two projections (9, 10) in each case, which in each case form a curved edge (14) of the motor housing between the screw socket fixing point (8) and the opening (4).

Description

TECHNICAL FIELD

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

[0002] Electric motors, which are referred to as internal rotor motors, have a rotor which comprises a motor shaft and is rotatably mounted in a housing, a permanent magnet being arranged on the rotor, a stator being arranged around the motor, a core of the stator carrying a plurality of windings. When suitably controlled, the windings generate a magnetic field which drives the rotor in rotation, the windings usually being of three-phase design and three electrical connections being provided accordingly, by means of 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] Such electric motors usually have a deep-drawn motor housing, and when designing the interface between the motor housing and the motor internal components, it must be taken into account that internal forces acting on the entire system can additionally be superimposed with external forces, for example, this can occur as a result of a strong acceleration of the entire system. Therefore, it is important to achieve a good mechanical stiffness when connecting the system components, so that the torques and forces occurring during operation of the electric motor do not lead to a deformation or a displacement of the motor housing. SUMMARY

[0004] It is an object of the invention to propose an electric motor which has a motor housing with particularly good mechanical stiffness.

[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, the radial direction denotes the direction of the distance from the longitudinal axis, and the circumferential direction is defined as tangential to the radius arranged in the radial direction.

[0007] An electric motor having a deep-drawn motor housing with flanges adjoining the openings, the flanges being substantially polygonal, in particular square, in cross section, and each flange corner being provided with a socket-type fixing point, each flange corner having two protrusions which form a curved edge of the motor housing between the socket-type fixing point and the opening.

[0008] The protrusions move the curved edge from the opening towards the socket-type fixing point, so that the mechanical stability of the flange is greatly increased.

[0009] In a preferred embodiment, the protrusions form a bearing surface for a busbar unit of the electric motor. Thus, the position of the busbar unit is explicitly defined, and it is not necessary to create additional fastening options in the motor housing. Preferably, a bearing surface is provided at the bottom of each protrusion.

[0010] The motor housing is preferably a pot-like body having a substantially cylindrical outer surface, a closed, continuous base, and an opening opposite the base, so that the motor housing is open on only one side and surrounds the rotor and the stator, which is preferably completely enclosed by the motor housing in the axial direction.

[0011] Preferably, the cross section of each protrusion is substantially a right-angled triangle, with the side opposite the right angle being formed by the opening of the motor housing, and the other two sides extending parallel to the outer side of the flange. Preferably, the two protrusions of the flange corner are arranged at a distance from each other and are mirror-symmetrical with respect to a symmetry axis, which passes through the socket fixing point and the longitudinal axis of the motor housing.

[0012] Preferably, the rectangular envelope of the two protrusions of the flange corner encloses the respective socket fixing point, which is located in the radially outermost corner of the envelope.

[0013] Preferably, in the area of the socket fixing point, the outer side of the flange and the two sides of the protrusion close to the socket fixing point and their extension form an imaginary square, the socket fixing point being arranged in the center of the square. Preferably, the imaginary square defines a planar area whose dimensions are adapted to the diameter of the fastener used for the socket fixing point.

[0014] Preferably, the motor is an internal rotor motor, with a rotor provided with magnets and a stator arranged around the rotor, the core of the stator being provided with a plurality of windings, the ends of which are electrically contacted by means of the busbar unit. BRIEF DESCRIPTION OF DRAWINGS

[0015] A preferred embodiment of the application will be explained in more detail below with reference to the drawings. Like or similar components are denoted by the same reference signs in the figures, which show:

[0016] Figure 1 is a perspective view of the motor housing of the electric motor from below;

[0017] Figure 2 is Figure 1 is a schematic view of a corner of the motor housing from above to below;

[0018] Figure 3 is Figure 1 is a perspective view of the corner of the motor housing, with the busbar unit inserted into the motor housing; and

[0019] Figure 4 is Figure 1 is a perspective view of the corner area, with the busbar unit not shown. DETAILED DESCRIPTION

[0020] Figure 1A deep-drawn motor housing 1 of an electric motor is shown. The motor housing 1 is a pot-shaped body having a substantially cylindrical outer surface 2, a closed, continuous base 3, and an opening opposite the base 3, which is surrounded in the circumferential direction by a flange 5 having a substantially rectangular base with four flange corners 6, of which only three are shown in the figure, which are uniformly distributed in the circumferential direction, and each of which is provided with a through-hole 7 serving as a screw-in fixing point 8. In the region of the flange corners 6, the flange 5 also has two projections 9, 10 extending downward in the direction of the base 3, one for each flange corner 6, which are arranged mirror-symmetrically about a symmetry axis 100, which connects the central axis or longitudinal axis 200 of the motor housing and the central axis 300 of the corresponding screw-in fixing point, which is perpendicular to the symmetry axis 100, and which are arranged at a distance from one another in the circumferential direction.

[0021] As can be seen in detail from Figure 2 , the projections 9, 10 each have a cross section with two straight, limiting side edges 11, 12, which extend parallel to the outer side of the flange 5 and which are connected to the opening 4 in the radial direction. The cross section of each projection 9, 10 is substantially triangular, with the side opposite the right angle being formed by the opening 4 of the motor housing. The rectangular envelope of the two projections 9, 10 of the flange corner encloses the corresponding screw-in fixing point 8, which is located in the radially outermost corner of the envelope. In the region of the screw-in fixing point, the outer side of the flange and the two side edges of the projection near the screw-in fixing point and their extensions form an imaginary square 13, in the center of which the screw-in fixing point is located, other conventional cylindrical geometries being dispensed with at the screw-in fixing point. The imaginary square 13 defines a planar area, the size of which is adapted to the diameter of the screw head of the through-hole or of the grommet, so that this area can be connected directly to the opening of the motor housing as far as possible.

[0022] The direct connection 14 between the right angles of the projections of the flange corner is parallel to the tangent of the opening 4 at the symmetry axis 100 and is located radially between the screw-in fixing point 8 and the opening 4.

[0023] The projections 9, 10 reduce the bending stresses at the screw-in fixing point 8, enabling a high mechanical stiffness of the motor housing even with low material thicknesses or wall thicknesses in the critical region of the screw-in fixing point 8.

[0024] As can be seen from Figure 3 , the projections 9, 10 can be used as axial bearing surfaces for the busbar unit 15 of the electric motor, the bearing surfaces 16 being subsequently machined into the base of the projections 9, 10, in particular by means of a stamping process (seeFigure 4 ). The stamping process can include a final finishing process, depending on the depth of the bearing surfaces 16 in the projections 9, 10, it is possible to ensure the radial fixing of the busbar unit 15. The bearing surfaces 16 extend radially away from the opening and are substantially semicircular in shape, one for each projection 9, 10. From Figure 3 It can be seen that the busbar unit 15 has projections 18 which rest on every other bearing surface, however, it is also possible to consider selecting a different number of projections for bearing on the bearing surfaces.

Claims

1. An electric motor having a deep-drawn motor housing (1), the motor housing (1) having a flange (5) adjacent to an opening (4), characterized in that, The flange (5) has a roughly polygonal cross section. Each flange corner (6) is provided with a screw-type fixing point (8), and each flange corner (6) has two protrusions (9, 10). The protrusions form a curved edge (14) of the motor housing between the screw-type fixing point (8) and the opening (4). The protrusions (9, 10) form a support surface (16) for the busbar unit (15) of the motor.

2. The electric motor according to claim 1, characterized in that, The support surface (16) is located at the bottom of the corresponding protrusion.

3. The electric motor according to any one of the preceding claims, characterized in that, Each protrusion (9, 10) has a cross-section that is approximately a right triangle, wherein one 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).

4. The electric motor according to claim 3, characterized in that, The rectangular envelope of the two protrusions (9, 10) of the flange corner surrounds the corresponding screw-type fixing point (8), wherein the screw-type fixing point (8) is arranged at the outermost corner of the envelope along the radial direction.

5. The electric motor according to claim 3, characterized in that, In the area of ​​the threaded fixing point (8), the outer side of the flange and the two sides of the protrusion near the threaded fixing point and their extensions form an imaginary square (13), and the threaded fixing point (8) is located at the center of the square.

6. The electric motor according to claim 5, 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).

7. The electric motor according to claim 1, characterized in that, The support surfaces (16) are all formed by molding process.

8. The electric motor according to claim 7, characterized in that, The molding process includes a final finishing operation.

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