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Patent Searching and Data


Title:
AUTOMOTIVE ELECTRIC MOTOR
Document Type and Number:
WIPO Patent Application WO/2018/006953
Kind Code:
A1
Abstract:
The automotive electric motor (10) with mechanical commutation comprises a stiff coil wire (58) with a welding portion (66) and an end portion (70) adjacent to the welding portion (66), and a flexible braid wire (54) with a wire end (62), the wire end (62) being electrically and mechanically connected to the coil wire (58) at the welding portion (66) by welding. The end portion (70) of the coil wire (58) is bended in relation to the welding portion (66) and is thereby bended away from the braid wire (54) so that an end surface (78) of the end portion (70) of the coil wire (58) is not facing the braid wire (54).

Inventors:
HENKE TONI (DE)
LINDNER ENRICO (DE)
ZILL MATHIAS (DE)
Application Number:
PCT/EP2016/065983
Publication Date:
January 11, 2018
Filing Date:
July 06, 2016
Export Citation:
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Assignee:
PIERBURG PUMP TECHNOLOGY GMBH (DE)
International Classes:
H02K11/026; H01R39/36
Foreign References:
US20120291277A12012-11-22
US20020105246A12002-08-08
US20150028705A12015-01-29
JPH06311708A1994-11-04
Attorney, Agent or Firm:
PATENTANWÄLTE TER SMITTEN EBERLEIN RÜTTEN (DE)
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Claims:
Pierburg Pump Technology GmbH

C L A I M S

1. Automotive electric motor ( 10) with mechanical commutation, comprising :

a stiff coil wire (58) with a welding portion (66) and an end portion (70) adjacent to the welding portion (66), and

a flexible braid wire (54) with a wire end (62), the wire end (62) being electrically and mechanically connected to the coil wire (58) at the welding portion (66) by welding, whereby the end portion (70) is bended in relation to the welding portion (66) and is thereby bended away from the braid wire (54) so that an end surface (78) of the end portion (70) of the coil wire (58) is not facing the braid wire (54) .

2. The automotive electric motor (10) according to claim 1, characterized in that a bending angle (a) between the welding portion (66) and the end portion (70) of the coil wire (58) is in the range of 60°- 120°.

3. The automotive electric motor (10) according to claim 1 or 2, characterized] in that a welding area (82) is facing to a direction, which is substantially orthogonal to a longitudinal direction (86) of the end portion (70) of the coll wire (58).

4. The automotive electric motor (10) according to one of the preceding claims, characterized in that the coil wire end surface (78) is inserted into a pocket (90).

5. The automotive electric motor (10) according to one of claims 1 to 3, characterized in that the wire end surface (78) is fixed in a pocket (90).

6. The automotive electric motor (10) according to one of the preceding claims, characterized in that the end portion (70) of the coil wire (58) is provided with a sharp edge (74),

7. The automotive electric motor (10) according to one of the preceding claims, characterized in that the coil wire (58) defines a choke coil (50).

8. The automotive electric motor (10) according to one of the preceding claims, characterized in that the flexible braid wire (54) defines a brush wire of a mechanical commutator arrangement (26).

Description:
Automotive electric motor

The present invention refers to an automotive electric motor with mechanical commutation.

In particular, the present Invention refers to an automotive electric motor for driving components or devices of the automobile. Such components or devices could be e.g. auxiliary units, actuators or pumps. Accordingly, the automotive electric motor according to the present invention is not an engine of the automobile for driving the vehicle. The automotive electric motor is mechanically commutated so that commutator brushes are necessary, which are in permanent contact with a commutator ring. The automotive electric motor comprises a coil wire for electrically connecting the commutator brushes with a power source. A common automotive electric motor for driving auxiliary units, actuators or pumps has an electric performance of up to approximately 500W, so that an electric current of 10 of up to 40A with an on-board voltage of 12 or 24V is required. As a consequence, in order to reduce the electric resistance of the coil wire the wire has a diameter of at least a couple of millimeters. The coll wire, which can define, for example, a choke coil, therefore has high stiffness, so that it cannot be directly mechanically connected to the commutator brushes. A flexible braid wire is provided between the commutator brushes and the stiff coil wire, to allow movements of the brushes and vibrations of the coil wire. The braid wire is provided with a wire end, which is electrically and mechanically connected to the coil wire by welding. The flexible braid wire can be a brush wire electrically connecting the coil wire with the commutator brush. In practice, the stiff coil wire end Is defined by machine cutting so that a burr and/or a sharp edge can result at the cutted end surface. During the lifetime of the automotive electric motor the burr or sharp edge can damage the braid wire, which is connected to the coll wire. The braid wire is defined by a multiple number of thin wires, each of which is sensitive to be cut by the burr or sharp edge of the coil wire. A failure of the electric motor can occur in case the braid wire is substantially severed. A failure also could occur, If merely a majority of the thin wires are cut. In this case the remaining thin wires are fused due to the high electric current. As a consequence lifetime and reliability of the automotive electric motor is limited. In order to prevent such damages additional complex manufacturing steps are necessary in order to remove the burr and sharp edges. Thereby, the manufacturing costs are increased.

The object of the present invention is to provide a reliable automotive electric motor with mechanical commutation, with reduced manufacturing costs.

This object is solved with an automotive electric motor having the features of claim 1.

According to the present Invention the stiff coil wire Is provided with a welding portion and an end portion adjacent to the welding portion. The wire end portion is bended in relation to the wire welding portion and is thereby bended away from the braid wire so that a wire end surface of the wire end portion of the coil wire is not facing the braid wire. The term "welding" according to the invention is not limited to the welding process as such, but may also be a soldering process. The welding portion according to the present invention Is an axial section of the coil wire, where the braid wire is allowed and Intended to be welded to the coil wire. In this axial section the braid wire can be connected to the coll wire by spot-weiding or by welding over a defined longitudinal section. Between the welding portion and the end portion, which is provided adjacent to the welding portion, the coil wire is bended and thereby changes the axial direction. The end portion therefore is bended in relation to the welding portion. The end surface according to the invention is the surface of the coil wire, which is generated by the cutting process.

According to the invention the end surface does not face the braid wire, if a projected longitudinal axis of the wire end axis does not cross the braid wire. By bending the end portion according to the present invention a sharp edge of the wire end surface will always be provided in a distance to the braid wire so that abrasion, kinking and breaking of the braid wire can be excluded. Damages of the braid wire during the mounting process or during operation due to vibrations will not occur anymore. Thereby the lifetime and reliability of the automotive electric motor will be increased.

Further, the complex manufacturing step of deburring the sharp edges of the wire end surface can be omitted, so that the manufacturing costs can be decreased.

In a preferred embodiment of the present Invention a bending angle between the wire welding portion and the wire end portion of the coil wire is in the range of 60°-120°. The axial direction of the wire welding portion and the axial direction of the end portion enclose and define the bending angle. The specified bending angle has the effect that the end surface of the wire end portion is not facing the braid wire so that damages of the braid wire are securely prevented.

In a further preferred embodiment a welding area is facing to a direction, which Is substantially orthogonal to a longitudinal direction of the wire end portion of the coil wire. The welding area according to the present invention is the area where the coil wire is materially bonded to the braid wire. The welding area, which is at least a part of an outer circumferential surface of the coil wire, which is facing to a lateral direction, is substantially orthogonal to the direction of the welding portion of the coil wire. The welding area therefore is facing to a direction, which is substantially orthogonal to the plane, which is defined by the longitudinal axis of the wire end portion of the coil wire and by the longitudinal axis of the welding portion of the coil wire. The specified arrangement has the effect that the mounting space in the axis of the wire end portion can be kept small.

Preferably, the coil wire end surface Is inserted into a pocket. According to the invention the pocket can be formed like a hopper or a concave portion. The pocket can be defined by e.g. a part of the motor housing or frame or by a part supporting the coil wire, for example a brush card. The pocket restricts the freedom of movement of the coll wire end portion. As the movement of the coil wire is restricted, the dynamic load on the welding connection between the braid wire and the coil wire is reduced so that the lifetime of the welding connection is increased.

The coil wire end portion can be inserted loose into the pocket. Alternatively, the wire end surface is fixed in the pocket. According to the Invention, the term "fixed" means that the wire end surface is tightly provided and fixed in the pocket. Mechanical load acting on the welding between braid wire and coil wire generated by e.g. vibrations is thereby significantly reduced. Accordingly, the lifetime and reliability of the electric motor thereby will be increased.

According to a preferred embodiment, the end portion of the coil wire is provided with a sharp edge. The sharp edge like e.g. a burr, resulting from the cutting process of the coil wire, need not to be removed. Accordingly, the manufacturing step of removing the sharp edge is omitted. Thereby, the automotive electric motor can be manufactured more economically. The coil wire preferably defines a choke coil. With the choke coil electromagnetic interferences generated by the brush sparking can be minimized. As a consequence electromagnetic emissions, disturbing other electronic devices in the automobile are significantly reduced. Preferably, the flexible braid wire defines a brush wire of a mechanical commutator arrangement. The braid wire has a high flexibility so that relative movements of the brushes in relation to the coil wire can be compensated without a fatigue break of the braid wire.

The following is a detailed description of an embodiment of the invention with reference to the drawings, wherein:

Figure 1 shows a schematic drawing of an automotive electric motor according to the present invention, and

Figure 2 shows an enlarged section of figure 1 of the connection between the braid wire and the coil wire of the commutator of the electric motor. Figure 1 shows a schematic drawing of an automotive electric motor 10 with mechanical commutation. The electric motor 10 comprises a motor housing 14, housing a motor stator 18, a motor rotor 22 and a commutator arrangement 26. The motor rotor 22 is arranged on a rotor shaft 30, which is rotatably supported at the motor housing 14 via a first and a second bearing 34, 38. The motor stator 18 is arranged inside the motor housing 14 surrounding the motor rotor 22. The commutator arrangement 26 comprises a commutator ring 40, which is arranged on the rotor shaft 30. The commutator ring 40 is electrically connected by electrical connections 42 to rotor windings of the motor rotor 22. The commutator arrangement 26 further comprises two commutator brushes 46. The commutator brushes 46 are provided in radial electrical contact with the commutator ring 40 and are arranged on radial opposing sides of the commutator ring 40. Each commutator brush 46 is electrically connected to a respective choke coll 50 in order to minimize electromagnetic interference generated by the brush sparking of the commutator brushes 46.

Figure 2 shows an enlarged view of the electrical connection between the commutator brush 46 and the choke coil 50 of figure 1. The commutator brush 46 is electrically connected to the coil wire by a flexible braid wire 54. The flexible braid wire 54 comprises multiple thin filament wires, which are braided to define a ribbon-shaped braid wire 54. The braid wire 54 is electrically and mechanically connected to a stiff coil wire 58, which has a diameter of a couple of millimeters, by welding a wire end 62 of the braid wire 54 to a welding portion 66 of the coil wire 58. The welding portion 66 Is an axial section of the coil wire 58, where the braid wire 54 Is intended to be welded to the coil wire 58.

The coil wire 58 comprises a wire end portion 70, which is arranged adjacent to the welding portion 66 of the coil wire 58. Due to the cutting process of the stiff coil wire 58, the wire end portion 70 is provided with a sharp edge 74 like e.g. a burr. The wire end portion 70 Is bended in relation to the welding portion 66 and is thereby bended away from the braid wire 54, so that a wire end surface 78 of the wire end portion 70 Is not facing the braid wire 54. A welding area 82, where the coil wire 58 is materially bonded to the braid wire 54, is facing to a direction, which is substantially orthogonal to a longitudinal direction 86 of the wire end portion 70 of the coil wire 58. An angle between the welding portion 66 and the wire end portion 70 of the coil wire 58 is 90°. Thereby it is prevented that the sharp edge 74 of the coil wire 58 comes into contact with the braid wire 54. Thus, the braid wire 54 cannot be damaged by the sharp edge 74 of the coil wire 58.

The wire end surface 78 Is inserted into a pocket 90, which has a concave shape. The pocket 90 is defined by a frame 94 of the motor housing 14. The pocket 90 restricts the lateral freedom of movement of the end portion 70 so that vibrations of the coil wire 58 are reduced. As a consequence, also the dynamic load on the welding connection is decreased.

From the above it should be clear that the automotive electric motor with mechanical commutation Is not limited to the above described embodiment. In particular other designs of the pocket can be used. Aiso other bending angles and other designs of the welding area are conceivable.

Reference signs

10 automotive electric motor

14 motor housing

5 18 motor stator

22 motor rotor

26 commutator arrangement

30 rotor shaft

34 first bearing

10 38 second bearing

40 commutator ring

42 electrical connection

46 commutator brush

50 choke coil

15 54 flexible braid wire

58 stiff coil wire

62 wire end

66 welding portion

70 end portion

20 74 sharp edge

78 end surface

82 welding area

86 longitudinal direction of the end portion

90 pocket

25 94 frame

a angle