Prior art

The invention relates to a brushless electric motor according to the preamble of claim 1 . Moreover, the invention relates to a method for the assembly of an electric motor according to the invention. A brushless electric motor of this kind is already known in practice. It comprises a rotor which is rotationally mounted and carries magnetic elements, which interacts with a stator arranged stationary in a housing of the electric motor. The stator comprises several wire windings, which are actuated or energized depending on the rotation angle position of the rotor, in order to drive the rotor. Furthermore, such an electric motor typically has a gearing on one section of a shaft of the rotor, which meshes with a gear wheel in order to drive a driven element of the electric motor. This driven element serves, for example in a windscreen wiper motor, for the at least indirect moving of a windscreen wiper or a wiping rod. For the installing of the rotor in the housing of the electric motor it is provided that this is positioned or fixed in the housing in the axial direction, i.e., the direction of the rotary axis of the rotor. For this purpose, bow- shaped securing elements are known in the prior art, which can be inserted into a recess of the housing and at the same time interact with, for example, a bearing device of the rotor, so that the bearing device and hence also the rotor are axially positioned in the housing. Furthermore, it is also required to secure the stator in the housing during the assembly or to position it in an axial position. This is performed in the prior art by a separate assembly step from the positioning or securing of the rotor.

Disclosure of the invention The brushless electric motor with the features of claim 1 has the advantage that, by its design configuration, the axial securing and positioning of both the rotor and the stator is performed in a single common assembly step using one and the same securing element. For this, it is provided that the securing element, designed to position and secure the rotor, is configured to additionally position the stator axially in the housing in the direction of the rotary axis of the rotor. Advantageous modifications of the brushless electric motor according to the invention are set forth in the dependent claims. All combinations of at least two features disclosed in the claims, the description, and/or the figures fall within the scope of the invention. The interworking of the stator with the securing element for the axial positioning of the stator occurs preferably by a positioning portion, which interacts with the securing element. In particular, it is provided that the positioning portion cooperates with the securing element by means of a form-fit connection. Such a configuration also makes it possible, in particular, to dispense with additional elements or components to connect the securing element to the positioning portion.

Usually the arrangement of the securing element for the axial positioning or securing of the rotor is dictated by the design. In order to avoid having to make any change to the installing location of the securing element in this regard and also to avoid having to make any change to the disposition of the stator with respect to the rotor, it is furthermore provided in one preferred design embodiment that the positioning portion axially protrudes beyond a coil region of the stator in the direction of a longitudinal axis of the stator in the direction of the securing element, which coil region comprises wire windings. In another preferred design embodiment of the electric motor which is optimized in terms of the assembly process, it is proposed that the stator is arranged in a motor housing, that the motor housing can be connected to a second face side of a gear housing on a first face side, wherein the motor housing forms the housing of the electric motor together with the gear housing, that the gear housing comprises a cutout into which the positioning portion can be axially inserted in the direction of the rotary axis of the rotor, and that the cutout extends all the way into the region of a recess for receiving the securing element. Such a configuration makes it possible, when joining the components of the electric motor, to introduce the stator by its positioning portion into the cutout of the gear housing until the positioning portion comes to overlap axially with the securing element. An assembly of the securing element, which can be performed especially easily in particular manually, provides that the securing element can be inserted into the recess in a direction running perpendicular to the rotary axis of the rotor. Such a configuration furthermore has the advantage that, for example a cover spanning the gear housing in the area of the recess for the securing element holds or secures the cover of the securing element in its position, so that no additional fastening elements are required for the securing element in the form of separate components either. In a preferred design embodiment of the positioning portion and the securing element interacting with the positioning portion, it is provided that the positioning portion of the stator comprises a groove in which a protrusion of the securing element engages. In order to fulfil the dual function of the securing element in terms of the positioning and the fixation of both the rotor and the stator, in one geometrically advantageous configuration of the securing element it is provided that, in a plane running perpendicular to the rotary axis of the rotor, the securing element is of U-shaped design with a cut-out for receiving a shaft of the rotor and it comprises an arresting section for cooperating with the positioning portion.

The positioning portion is formed in particular on an extension of the stator, wherein the extension extends parallel to the longitudinal axis of the stator, and the securing element comprises a protrusion which carries the arresting section.

It is most especially preferred that the stator together with the extension forms a monolithic injection molding. This affords an especially economical way of fabricating both the stator and the extension not requiring additional assembly expense.

The securing element serves, as is known in the prior art, for the axial positioning of the rotor in the housing of the electric motor. With the aid of the securing element, an axial force is exerted on a bearing device of the rotor, which is firmly connected to the shaft of the rotor in the axial direction, which applies force to the bearing device and hence to the rotor in a defined direction of the housing. For the applying of such an axial or biasing force to the bearing element it is advantageous for the securing element to consist of a spring steel sheet and to be formed as a punched or bent part. On account of being formed as a spring metal sheet, its configuration can be curved, for example, so that owing to its shape and the introducing of the securing element into a seat of the housing, the securing element can act with an axial biasing force on the bearing device. As is known, the stator has wire windings which need to be energized in order to drive the rotor. Another preferred design embodiment with a view to the possible contacting of the wire windings provides that the extension comprises ports for electrically contacting electric coils (wire windings) located in the stator. Such an embodiment further makes it possible to situate the location of the electrical contacting of the coils or wire windings by way of the extension in a region which is distant from the actual stator or wire windings.

An electric motor so described according to the invention in one preferred application is part of a wiper motor, which drives at least indirectly a windscreen wiper.

Furthermore, the invention also involves a method for mounting an electric motor as described according to the invention. This mounting includes at least the following steps: first of all, mounting the stator and the rotor in the motor housing of the electric motor. Next, axially joining the motor housing and the gear housing, wherein a portion of the rotor and the positioning portion of the stator protrude into the gear housing. Lastly, mounting the securing element, wherein the rotor and the positioning portion are positioned axially relative to the motor housing and the gear housing.

Further advantages, features and details of the invention will emerge from the following description of preferred exemplary embodiments as well as with the aid of the drawing. There are shown:

Fig. 1 the major components of a brushless electric motor according to the invention in a partly sectioned exploded view, Fig. 2 a partly sectioned representation of the mounted electric motor of

Fig. 1 , a detail of Fig. 2 in the region of a securing element in top view,

Fig. 4 the region of Fig. 3 in a perspective representation,

Fig. 5 a perspective representation of the electric motor of Fig. 1 and 2 to explain the assembly process for a securing element,

Fig. 6 a partial cross section in the region of the securing element of the electric motor and

Fig. 7 a cross section through the electric motor in the region of the securing element with major components. The same elements or elements with the same function are given the same reference numbers in the figures.

The figures show a brushless electric motor 10, which serves as a wiper motor 100 for at least indirect moving or driving of at least one windscreen wiper in a vehicle, not shown in the figures. The electric motor 10 comprises a housing 12, which consists of a typically multiple-piece gear housing 14 made of plastic in particular and a motor housing 16 which can be flanged onto the gear housing 14, especially of cup shape, and shown in section view in the figures. The connection between the gear housing 14 and the motor housing 16 occurs in the area of two opposite face sides 17, 18 of the gear housing 14 and the motor housing 16 in the region of flangelike sections, for example by fastening elements such as fastening screws (not shown) or by a locking connection. Inside the gear housing 14 there is arranged a gear 20, being a single- stage gear in the exemplary embodiment, with a gear wheel 21 . The gear wheel 21 , rotationally mounted in one axle in the gear housing 14, acts on a driven element 22 (Fig. 7) in the form of a driven shaft, which for example interacts directly with a windscreen wiper or with a wiper rod. The gear wheel 21 has on its outer circumference a gearing 23 in the form of a helical gearing, which meshes with a worm gearing 26 formed on one section of a shaft 24 of a rotor 25.

The rotor 25 is rotationally mounted inside the housing 12 for example by means of two bearing devices 28, 30, the two bearing devices 28, 30 being arranged in a fixed position on the shaft 24 of the rotor 25 in the direction of the rotary axis 31 of the rotor 25. The rotor 25 furthermore, as is also known in the prior art, has first magnetic elements 32 (Fig. 5) on its outer circumference for interacting with a stator 40 and second magnetic elements 34 as part of a Hall sensor for detecting the rotary angle position of the rotor 25, the magnetic elements 32, 34 being arranged at an axial spacing from each other in regard to the rotary axis 31 of the rotor 25 or being adjacent to each other (Fig. 5).

The rotor 25 is enclosed by the stator 40, fixed in place in the housing 12, coaxially to the rotary axis 31 . The stator 40 has a carrier element 42 made of plastic in an injection molding process, being adapted to receiving several wire windings 44 to form coils in the circumferential direction about a longitudinal axis 43 of the carrier element 42, which is aligned with the rotary axis 31 . Furthermore, the carrier element 42 is enclosed in a central region by a back yoke ring 46 made of ferromagnetic material.

In the state of the stator 40 installed in the housing 12, the wire windings 44 interact with the first magnetic elements 32 of the rotor 25, the first magnetic elements 32 being arranged in particular centrally in regard to the axial extension of the wire windings 44 in the direction of the longitudinal axis 43. Furthermore, the carrier element 42 comprises an extension 48 protruding axially beyond the region of the wire windings 44 in the direction towards the gear housing 14, which is monolithically moulded on the carrier element 42. The extension 48 runs substantially parallel to the longitudinal axis 43 of the carrier element 42 and has, at the side facing towards the longitudinal axis 43, a positioning portion 50 with a groove 52 arranged perpendicular to the longitudinal axis 43 (Fig. 4). Furthermore, in the area of the extension 48, as is best seen from Fig. 3 and 4, there are arranged for example three electrical connectors in the form of contact elements 53 to 55 made of spring metal sheets, which are electrically connected to the wire windings 44. Owing to the contact elements 53 to 55, an energization or contacting of the wire windings 44 can occur by mating elements, not shown, for example in the form of plugs which interact with the contact elements 53 to 55. For example, it may be provided in this case that the contacting of the contact elements 53 to 55 occurs by an additional cover element of the gear housing 14, which carries the mating contacts and which, when connected to the gear housing 14, automatically comes into operative connection with the contact elements 53 to 55. As is best seen from Fig. 2, the extension 48 protrudes axially into the gear housing 14. For this, the gear housing 14 has a recess 58 (Fig. 6, 7), which surrounds the extension 48 with a clearance when an axial joint is produced between the stator 40 or the motor housing 16 containing the stator 40 and the gear housing 14. In the condition shown in Fig. 2 joined between the stator 40 and the gear housing 14, the extension 48 is arranged with the region of the groove 52 and the contact elements 53 to 55 in the region of an additional recess 60 of the gear housing 14.

The positioning portion 50 or the groove 52 interact with a securing element 62 made of spring sheet metal. The securing element 62, as is especially recognizable when viewing Fig. 1 together with Fig. 6, has a U- shaped cutout 64 for receiving the shaft 24. The securing element 62 interacts by one face side 65 with an end surface of the one bearing device 28 facing towards it, and by its other face side 66 with a wall 68, forming an axial end stop, formed in the region of the other recess 60 in the gear housing 14 (Fig. 3, 5). The securing element 62, which is fashioned as a punched or bent part, is preferably somewhat curved or bent, so that when the securing element 62 is introduced axially in the direction of the installation direction 70, running perpendicular to the rotary axis 31 of the rotor 25 (Fig. 6), the two face sides 65, 66 of the securing element 62 exert an axial force on the bearing device 28 and hence on the rotor 25 in the direction of the rotary axis 31 , which position the rotor 25 in an axial nominal position in relation to the housing 12. Furthermore, the securing element 62, as is especially visible with the aid of Fig. 6, has a protrusion 72 with an arresting section 74 in the direction of the extension 48. The arresting section 74 is adapted to produce a form fit connection 76 with the groove 52 on the positioning portion 50 at the same time when the securing element 62 is assembled on the rotor 25.

If the groove 52, as can be seen from Fig. 6, does not run along the entire extent of the extension 48, but instead has a shoulder 78, then when the arresting section 74 is placed against the shoulder 78 a first end stop 79 is formed, which together with a second end stop 80, which is formed between the extension 48 and a bottom region 82 of the other recess 60, as per the arrows 83, 84, brings about a locking of the extension 48 and hence the stator 40 not only in the direction of the rotary axis 31 , but also a fixed rotary angular arrangement of the stator 40 relative to the housing 12.

For the assembly of the electric motor 10, the stator 40 and the rotor 25 are mounted in the motor housing 16, with the stator 40 protruding at least by the region of its extension 48 and the rotor 25 for a portion from the motor housing 16. After this, an axial joining is performed for the motor housing 16 and the gear housing 14, so that the components of the stator 40 and the rotor 25 protruding from the motor housing 16 end up in the region of the gear housing 14. When the axial joining between the gear housing 14 and the motor housing 16 is completed, (optionally after a fastening of the motor housing 16 to the gear housing 14) the securing element 62 is introduced in the direction of the installation direction 70 into the region of the further recess 60, while at the same time both the rotor 25 and the stator 40 are positioned in the longitudinal direction, i.e., in the direction of the rotary axis 31 or the longitudinal axis 43 with respect to the housing 12. After this, further assembly steps are performed to finish or complete the electric motor 10 or the wiper motor 100.

The electric motor 10 thus described can be altered or modified in many ways without deviating from the idea of the invention.

List of reference numbers

10 Electric motor

12 Housing

14 Gear housing

16 Motor housing

17 Face side

18 Face side

20 Gear

21 Gear wheel

22 Driven element

23 Gearing

24 Shaft

25 Rotor

26 Worm gearing

28 Bearing device

30 Bearing device

31 Rotary axis

32 First magnetic element

34 Second magnetic element

40 Stator

42 Carrier element

43 Longitudinal axis

44 Wire winding

46 Back yoke ring

48 Extension

50 Positioning portion

52 Groove

53 Contact element

54 Contact element

55 Contact element Recess

Recess

Securing element

Cutout

Face side

Face side

Wall

Installation direction

Protrusion

Arresting section

Form fit connection

Shoulder

First end stop

Second end stop

Bottom region

Arrow

Arrow

Wiper motor