Prior art

The present invention relates to a brushless electric motor, in particular for a windshield wiper motor, having the features of the preamble of claim 1.

Such a brushless electric motor, known from practice, is characterized by two features which are essential in the context of explaining the invention: on the one hand, a rotor of the electric motor, which is rotatably mounted by means of a plurality of bearings, is received in the housing of the windshield wiper motor without axial clearance by an axial-clearance compensating device in the longitudinal direction of the shaft of the rotor. In practice, the axial-clearance compensating device is, for example, configured in the form of a stamped bending part comprising a U-shaped receiving opening for the shaft, which stamped bending part is inserted in a direction extending perpendicular to the longitudinal direction of the shaft into a receiving gap between a bearing of the rotor and the housing, thereby forming a clamping connection. On the other hand, the brushless electric motor is characterized by a stator comprising wire coils, wherein the wire coils can be electrically contacted via a connecting body formed as a component of the stator and connected to this. The connecting body is configured in the manner of an appendix, which is disposed at a front side of the stator and runs parallel to the longitudinal axis of the stator at a distance. In turn, electrical connecting elements connected to the wire coils are disposed in the connecting body, which can be contacted by means of further connecting elements for energizing the electric motor. These further connecting elements are, for example, connected to a housing cover, which is joined to a gearbox cover of the windshield wiper motor in a direction extending perpendicular to the longitudinal axis of the stator, wherein the further connecting elements come into contact with the connecting elements in the connecting body by force. The problem is that the appendix consisting of plastic on the connecting body has a certain level of flexibility in a direction extending perpendicular to the longitudinal axis of the stator so that, when joining the housing cover, the danger exists that the appendix along with its electrical connecting elements deviates from its intended position and the contacting is not reliably ensured by the connecting elements on the housing cover. In order to avoid this, it is known to support the appendix of the connecting body by means of a corresponding embodiment of the (gearbox) housing so that this cannot deviate from its target position during the contacting process.

Disclosure of the invention

The brushless electric motor according to the invention, in particular for a windshield wiper motor, with the features of claim 1 has the advantage that, on the one hand, a support of the appendix on the connecting body for reliable electric contacting is made possible without a modification of the (gearbox) housing and that, on the other hand, a fixed and defined positioning of the axial-clearance compensating device for securing the shaft of the rotor is simultaneously ensured by force. For this purpose, the teaching of the invention proposes to configure the axial-clearance compensating device in such a way that this is disposed so as to be in abutting contact with the stator, in particular with the appendix of the connecting body or the stator, thereby being supported in the direction of the longitudinal axis in a direction extending perpendicular to the longitudinal axis of the stator. Furthermore, by means of the abutting contact of the axial-clearance compensating device with the stator, securing of the axial-clearance compensating device to prevent loss is ensured to the extent that this, in turn, is prevented from moving against its mounting direction by the stator.

Advantageous further embodiments of the brushless electric motor according to the invention, especially for a windshield wiper motor, are specified in the subclaims.

In a specific further embodiment of the brushless electric motor, it is provided that the stator has a stator body carrying wire coils and a connecting body at least indirectly connected to the stator body for forming an electrical contact with the wire coils, the connecting body being disposed at a front side of the stator body, the connecting body having an appendix disposed on the side that faces away from the stator body and running parallel to the longitudinal axis of the stator, and the appendix being disposed so as to be in abutting contact with the axial-clearance compensating device.

In an embodiment of the connecting body that is preferred on a technical manufacturing level, this is made of plastic and produced using an injection-molding method. In the context of the invention, forming out of plastic in connection with the geometric design of the appendix of the connecting body results in the elasticity of the appendix extending in the direction of the longitudinal axis of the stator, which is compensated by the axial-clearance compensating device without negative effects for the electrical contacting of the appendix.

With reference to the formation of the axial-clearance compensating device, there are different constructive variants. A particularly preferable embodiment with regard to manufacturing costs provides that the axial- clearance compensating device is realized in the form of an elastically deformable element, in particular made of a metal plate, which has a U- shaped opening for accommodating the shaft of the rotor and can be mounted into a seat of the housing in a direction perpendicular to the axis of rotation of the shaft in such a manner that a clamping lock connection is formed between the axial-clearance compensating device and the shaft, the axial-clearance compensating device subjecting the shaft to an axial force in the direction of a bearing.

In order to ensure that the axial-clearance compensating device is secure in the installation state contrary to the original mounting direction, it is provided in a further embodiment of the axial-clearance compensating device just described that the abutting contact is formed at a side of the axial-clearance compensating device that faces away from the opening of the axial-clearance compensating device. With regard to the assembly for receiving the axial-clearance compensating device in the seat of the housing, it is furthermore advantageous if the abutting contact between the axial-clearance compensating device and the appendix of the connecting body is formed on the axial-clearance compensating device in an area of the opening of the axial-clearance compensating device spaced-apart with respect to the direction of the axis of rotation of the shaft.

Thereby, the abutting contact preferably takes place on a portion of the axial-clearance compensating device that runs parallel to the axis of rotation of the shaft of the rotor.

In order to ensure the functionality of the axial-clearance compensating device, this must be disposed at a required target position in relation to a direction extending perpendicular to the axis of rotation of the rotor. This target position can, for example, be defined by a corresponding design of the U-shaped seat, wherein it must be avoided however that the base of the seat abuts the shaft of the rotor. Another embodiment that is preferred on a constructive level for securing the final mounting position of the axial- clearance compensating device therefore provides that the axial-clearance compensating device has an abutment portion for forming a stop in a mounting direction of the axial-clearance compensating device, said mounting direction extending perpendicular to the axis of rotation of the shaft of the rotor.

Thereby, preferably, it is provided that the abutment portion is disposed in operative connection with an outer circumference of a bearing. Since the outer circumference of the bearing is disposed in a stationary manner with respect to the housing, therefore, also no relative movement takes place between the abutment portion of the axial-clearance compensating device and the corresponding bearing.

Another functionality of the invention relates to positioning the stator in the motor housing of the electric motor in a direction extending parallel to the longitudinal axis of the stator. Here, the prior art usually provides that the stator is disposed in a seat of a motor housing, wherein the motor housing, for example, has a step on an inner housing wall radially running around the longitudinal axis of the stator and forms an axial stop when making contact with the stator. However, this requires a corresponding embodiment of the motor housing with corresponding tolerances of the components. In order to avoid this, it can be provided that the stator is fixed in the housing in a direction parallel to its longitudinal axis and that said fixing is brought about by the axial-clearance compensating device abutting against the appendix of the stator.

For this purpose, in particular, it can be provided that the axial-clearance compensating device has a portion extending perpendicular to the axis of rotation of the shaft and abutting against the appendix at the side that faces away from the stator.

It can also be provided that the appendix has a stop that extends in the direction of the axis of rotation of the shaft and that the stop abuts against the axial-clearance compensating device with a section extending in parallel to the axis of rotation of the shaft. With regard to the formation of the appendix or of the connecting body as an injection-molded plastic part, this section can be produced on or integrated onto the appendix in a very simple and inexpensive manner.

Another aspect of the invention relates to the possibility of additionally fixing and positioning the stator in the circumferential direction with respect to its longitudinal axis. For this purpose, it is provided that the axial- clearance compensating device is additionally configured to prevent the stator from rotating about its longitudinal axis, especially by at least one further abutting contact between the axial-clearance compensating device and the stator. Further advantages, features and details of the invention result from the following description of the preferred exemplary embodiments as well as based on the drawing.

In the drawing:

Fig. 1 shows a longitudinal portion through a windshield wiper motor in the case of a first embodiment of an axial- clearance compensating device, Fig. 2

and

Fig. 3 each show partial longitudinal portions through the windshield wiper motor in accordance with Fig. 1 in the case of modified axial-clearance compensating devices,

Fig. 4 shows a cross section through a windshield wiper motor in the case of an axial-clearance compensating device which has been modified once again, and

Fig. 5 shows a perspective illustration of a partial section of the windshield wiper motor in accordance with Fig. 4 in the connecting section between the axial-clearance compensating device and an appendix of a connecting body.

Identical elements and elements that are identical in function are indicated with the same reference numbers in the figures. The windshield wiper motor 100 shown in Fig. 1 is used to at least indirectly move a wiper arm (not shown) with a wiper blade of a windshield wiper system of a vehicle. For this purpose, the windshield wiper motor 100 comprises an output shaft 12, which is coupled to a wiper arm or else a wiper rod via a toothing 14 to drive at least one wiper arm.

The windshield wiper motor 100 comprises a brushless electric motor 10. The electric motor 10 comprises an annular stator 16 with a longitudinal axis 18. The stator 16 furthermore comprises a multitude of stator plates 20 stacked on top of one another and connected to each other, which form a stator body 24 and which serve to attach or receive wire coils 22, which can only be recognized in Fig. 1 , as this is known from prior art. On a front side, the stator body 24 is connected to a connecting body 26 that is also essentially annular. The connecting body 26 used for the electrical contacting of the wire coils 22 is made of plastic and is designed as an injection-molded part.

On the side facing away from the stator plates 20, an appendix 28 extending in parallel and at a distance from the longitudinal axis 18 protrudes from the connecting body 26. First electrical connecting elements 30 designed, in turn, as clamping elements or the like are provided in the tub-shaped appendix 28 on the end portion of the appendix 28 facing away from the stator plates 20, said connecting elements 30 being connected to the wire coils 22 on the one hand and being contactable via second electrical connecting elements 32 on the other in order to drive the windshield wiper motor 100 or the electric motor 10. For this purpose, the second connecting elements 32 are, for example, arranged in a housing cover 34 in an integrated manner, which makes a forced contacting possible between the first and the second connecting elements 30, 32 by joining in a mounting direction 36 extending perpendicular to the longitudinal axis 18. The contacting between the connecting elements 30, 32 takes place outside of the section of a housing 46, in which the stator 16 with the stator body 24 and the wire coils 22 are arranged.

In the exemplary embodiment shown, the appendix 28 is rectangular in the outer cross section and has a constant outer cross section in the longitudinal direction.

The stator 16 interacts with a rotor 38 that is arranged concentrically to the longitudinal axis 18. In a way which is also known, the rotor 38 comprises a shaft 40, which is rotatably mounted in a housing 46 of the electric motor which are axially spaced apart from one another. The axis of rotation 48 of the rotor 38 is aligned with the longitudinal axis 18 of the stator 16. In the overlapping section with the wire coils 22, in a way that is known and not shown, the rotor 38 furthermore comprises a plurality of permanent magnetic elements, which cause a rotation of the rotor 38 around the axis of rotation 48 in the case of a temporally offset energizing of the stator coils 22. For detecting the angle-of-rotation position of the rotor 38 for the prompt control or energizing of the wire coils 22, furthermore, a magnetic ring 50 with magnetic elements 52 is arranged on the circumference of the rotor 38, which is, for example, an integral part of a Hall sensor device in order to be able to deduce the angle-of-rotation position of the rotor 38 or the shaft 40.

In a section between the two bearings 42, 44, the shaft 40 furthermore comprises a worm gearing 54, which combs along the outer circumference of a spur wheel 58 with a counter-toothing 56, which, in turn, is at least indirectly coupled to the output shaft 12.

The multi-part housing 46 of the windshield wiper motor 100 comprises a housing cover 60 on the front side to seal a pot-shaped seat 62 for the stator 16. The seat 62 comprises a radially circumferential geometry running around the longitudinal axis 18 with a step 64, at which the stator 16, for example, along with the stator plates 20 abuts a side in an axial manner so that the step 64 forms an axial stop for axially positioning the stator 16 in the housing 46.

In order to avoid noise in the case of changing the direction of rotation of the electric motor 10 in particular, as well as to compensate for possible assembly clearances, the electric motor 10 furthermore comprises an axial-clearance compensating device 66. The axial-clearance compensating device 66 is configured in the form of a component consisting of a metal plate. The component is elastically deformable at least in portions and manufactured by means of a stamping/bending process. Furthermore, it comprises a U-shaped opening or seat 68, which is designed to comprise the shaft 40 on its outer circumference in portions. The axial-clearance compensating device 66 is received in a seat 70 of the housing 46, thereby forming a clamping lock connection in such a way that the one end face of the axial-clearance compensating device 66 is supported on a housing wall 72 and the other front side or end face is supported on the first bearing 42. In order to mount the axial-clearance compensating device 66, this can be inserted into the seat 70 in a direction running perpendicular to the axis of rotation 48 or in a mounting direction 36. By means of this, the shaft 40 connected to the first bearing 42 in a torque-proof manner is subjected to an axial force, for example, in the direction of the second bearing 44.

The axial-clearance compensating device 66 comprises a first portion 73 protruding away from the stator 16 in a slanted manner on the side facing away from the shaft 40, where a second portion 74 extending parallel to the axis of rotation 48 joins. The second portion 74 abuts the underside 75 of the appendix 28 with its topside, thereby forming an axial stop for the appendix 28 in the direction of the shaft 40 or in the mounting direction 36. Furthermore, the axial-clearance compensating device 66 comprises an abutment portion 76 that is parallel to the axis of rotation 48, which abuts the outer circumference of the first bearing 42, thereby limiting the movement of the axial-clearance compensating device 66 when mounting in the seat 68 in the mounting direction 36.

When mounting the second connecting elements 32, due to the abutting contact between the axial-clearance compensating device 66 and the appendix 28, it is ensured that the appendix 28 cannot deviate in the direction of the shaft 40. Furthermore, by means of this, the positioning of the stator 16 in the seat of the housing 46 in a direction extending perpendicular to the axis of rotation 48 or the longitudinal axis 18 is ensured so that the stator 16 in the housing 46 is also prevented from making a tilting movement.

The axial-clearance compensating device 66a shown in Fig. 2 differs from the axial-clearance compensating device 66 in accordance with Fig. 1 in that the abutting contact between the axial-clearance compensating device 66a and the underside 75 of the appendix 28 is provided in the section of a portion 78 extending parallel to the axis of rotation 48, which is longer than the second portion 74 in the case of the axial-clearance compensating device 66. Furthermore, an abutment portion 80 arranged perpendicular to the axis of rotation 48 protrudes from the portion 78 in such a way that the front side 82 of the appendix 28 facing away from the stator plates 20 axially abuts the portion 80. The axial-clearance compensating device 66a thereby limits the mobility of the stator 16 in the direction of the longitudinal axis 18. In turn, this has the result that the housing 46a can be designed in a simplified manner to the extent that, for example, no step 64 or no axial stop for the stator surface 20 must be provided.

The axial-clearance compensating device 66 shown in Fig. 3 is identical to the axial-clearance compensating device 66 in Fig. 1. Flowever, an appendix 28a is provided, which is complemented by an additional stop element 84, which is preferably monolithically formed on the appendix 28a. The stop element 84 acts as an axial stop for the axial-clearance compensating device 66 so that, in this case, a movement of the stator 16 in the direction of the arrow 86, in other words from the step 64 in the housing 46, is prevented. Lastly, another embodiment of an appendix 28b is shown in Fig. 4 and 5. This comprises two depressions 92, 94, which the limbs 88, 90 of the axial-clearance compensating device 66b abut, on the side facing the two limbs 88, 90 of the axial-clearance compensating device 66b, which limit the seat 68. By means of this, at least two abutting contacts 96, 98 are formed between the axial-clearance compensating device 66b and the appendix 28b in the circumferential direction of a semicircular diameter around the longitudinal axis 18 of the stator 16, which are arranged at a horizontal distance from one another. In particular, such an embodiment has the effect that a rotation of the stator 16, which is not shown in Fig. 4 and 5, about its longitudinal axis 18 is prevented since the depressions 92,

94 come to rest on a side face of the respective limb 88, 90 at the abutting contacts 96, 98 depending on the direction of rotation of the stator 16 around the longitudinal axis 18.

The electric motor 10 and windshield wiper motor 100 described up until this point can be varied and modified in a multitude of ways without departing from the concept of the present invention.

List of reference numbers

10 electric motor

12 output shaft

14 toothing

16 stator

18 longitudinal axis

20 stator plate

22 wire coil

24 stator body

26 connecting body

28, 28a, 28b appendix

30 first connecting element

32 second connecting element

34 housing cover

36 mounting direction

38 rotor

40 shaft

42, 44 bearing

46, 46a housing

48 axis of rotation

50 magnetic ring

52 magnetic element

54 worm gearing

56 counter-toothing

58 spur wheel

60 housing cover

62 seat

64 step

66, 66a, 66b axial-clearance compensating device 68 seat 70 seat

72 housing wall

73 first portion

74 second portion

75 underside

76 abutment portion

78 portion

80 abutment portion

82 front side

84 stop element

86 arrow

88, 90 limb

92, 94 depression

96, 98 abutting contact

100 windshield wiper motor