Patent Description:
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.

<CIT> discloses an electric motor with a rotor secured coaxially to a rotating shaft, a cylindrical stator surrounding the rotor on the diametric interior thereof; and a bearing holding part provided coaxially with the stator and integrally on each of the end faces thereof, the bearing holding part holding a bearing of the rotation axis from either side.

The brushless electric motor with the features of claim <NUM> 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.

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, according to the invention, 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.

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 <NUM>, which serves as a wiper motor <NUM> for at least indirect moving or driving of at least one windscreen wiper in a vehicle, not shown in the figures. The electric motor <NUM> comprises a housing <NUM>, which consists of a typically multiple-piece gear housing <NUM> made of plastic in particular and a motor housing <NUM> which can be flanged onto the gear housing <NUM>, especially of cup shape, and shown in section view in the figures. The connection between the gear housing <NUM> and the motor housing <NUM> occurs in the area of two opposite face sides <NUM>, <NUM> of the gear housing <NUM> and the motor housing <NUM> 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 <NUM> there is arranged a gear <NUM>, being a single-stage gear in the exemplary embodiment, with a gear wheel <NUM>. The gear wheel <NUM>, rotationally mounted in one axle in the gear housing <NUM>, acts on a driven element <NUM> (<FIG>) in the form of a driven shaft, which for example interacts directly with a windscreen wiper or with a wiper rod. The gear wheel <NUM> has on its outer circumference a gearing <NUM> in the form of a helical gearing, which meshes with a worm gearing <NUM> formed on one section of a shaft <NUM> of a rotor <NUM>.

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

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

In the state of the stator <NUM> installed in the housing <NUM>, the wire windings <NUM> interact with the first magnetic elements <NUM> of the rotor <NUM>, the first magnetic elements <NUM> being arranged in particular centrally in regard to the axial extension of the wire windings <NUM> in the direction of the longitudinal axis <NUM>. Furthermore, the carrier element <NUM> comprises an extension <NUM> protruding axially beyond the region of the wire windings <NUM> in the direction towards the gear housing <NUM>, which is monolithically moulded on the carrier element <NUM>. The extension <NUM> runs substantially parallel to the longitudinal axis <NUM> of the carrier element <NUM> and has, at the side facing towards the longitudinal axis <NUM>, a positioning portion <NUM> with a groove <NUM> arranged perpendicular to the longitudinal axis <NUM> (<FIG>). Furthermore, in the area of the extension <NUM>, as is best seen from <FIG>, there are arranged for example three electrical connectors in the form of contact elements <NUM> to <NUM> made of spring metal sheets, which are electrically connected to the wire windings <NUM>. Owing to the contact elements <NUM> to <NUM>, an energization or contacting of the wire windings <NUM> can occur by mating elements, not shown, for example in the form of plugs which interact with the contact elements <NUM> to <NUM>. For example, it may be provided in this case that the contacting of the contact elements <NUM> to <NUM> occurs by an additional cover element of the gear housing <NUM>, which carries the mating contacts and which, when connected to the gear housing <NUM>, automatically comes into operative connection with the contact elements <NUM> to <NUM>.

As is best seen from <FIG>, the extension <NUM> protrudes axially into the gear housing <NUM>. For this, the gear housing <NUM> has a recess <NUM> (<FIG>), which surrounds the extension <NUM> with a clearance when an axial joint is produced between the stator <NUM> or the motor housing <NUM> containing the stator <NUM> and the gear housing <NUM>. In the condition shown in <FIG> joined between the stator <NUM> and the gear housing <NUM>, the extension <NUM> is arranged with the region of the groove <NUM> and the contact elements <NUM> to <NUM> in the region of an additional recess <NUM> of the gear housing <NUM>.

The positioning portion <NUM> or the groove <NUM> interact with a securing element <NUM> made of spring sheet metal. The securing element <NUM>, as is especially recognizable when viewing <FIG> together with <FIG>, has a U-shaped cutout <NUM> for receiving the shaft <NUM>. The securing element <NUM> interacts by one face side <NUM> with an end surface of the one bearing device <NUM> facing towards it, and by its other face side <NUM> with a wall <NUM>, forming an axial end stop, formed in the region of the other recess <NUM> in the gear housing <NUM> (<FIG>). The securing element <NUM>, which is fashioned as a punched or bent part, is preferably somewhat curved or bent, so that when the securing element <NUM> is introduced axially in the direction of the installation direction <NUM>, running perpendicular to the rotary axis <NUM> of the rotor <NUM> (<FIG>), the two face sides <NUM>, <NUM> of the securing element <NUM> exert an axial force on the bearing device <NUM> and hence on the rotor <NUM> in the direction of the rotary axis <NUM>, which position the rotor <NUM> in an axial nominal position in relation to the housing <NUM>. Furthermore, the securing element <NUM>, as is especially visible with the aid of <FIG>, has a protrusion <NUM> with an arresting section <NUM> in the direction of the extension <NUM>. The arresting section <NUM> is adapted to produce a form fit connection <NUM> with the groove <NUM> on the positioning portion <NUM> at the same time when the securing element <NUM> is assembled on the rotor <NUM>.

If the groove <NUM>, as can be seen from <FIG>, does not run along the entire extent of the extension <NUM>, but instead has a shoulder <NUM>, then when the arresting section <NUM> is placed against the shoulder <NUM> a first end stop <NUM> is formed, which together with a second end stop <NUM>, which is formed between the extension <NUM> and a bottom region <NUM> of the other recess <NUM>, as per the arrows <NUM>, <NUM>, brings about a locking of the extension <NUM> and hence the stator <NUM> not only in the direction of the rotary axis <NUM>, but also a fixed rotary angular arrangement of the stator <NUM> relative to the housing <NUM>.

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

Claim 1:
Brushless electric motor (<NUM>), having a housing (<NUM>) for receiving a rotor (<NUM>) rotatably supported in a rotary axis (<NUM>) by means of multiple bearing means (<NUM>, <NUM>), wherein magnetic elements (<NUM>) are arranged on the rotor (<NUM>), which interact with a stator (<NUM>) stationary arranged in the housing (<NUM>), and wherein the rotor (<NUM>) is positioned in the housing (<NUM>) axially in the direction of the rotary axis (<NUM>) by means of a securing element (<NUM>) connectable with the housing (<NUM>),
characterized in that
the stator (<NUM>) comprises a positioning portion (<NUM>) cooperating with the securing element (<NUM>) and the positioning portion (<NUM>) axially protrudes beyond a carrier element (<NUM>) of the stator (<NUM>) in the direction of the rotary axis (<NUM>),
which carrier element (<NUM>) carries coil windings (<NUM>),
the securing element (<NUM>) serving for the axial positioning of the rotor (<NUM>) in the housing (<NUM>), said securing element (<NUM>) exerting an axial force on the bearing means (<NUM>) of the rotor (<NUM>),
wherein the bearing means (<NUM>) is firmly connected to a shaft (<NUM>) of the rotor (<NUM>) in the axial direction, wherein the securing element (<NUM>) applies force to the bearing means (<NUM>) and hence to the rotor (<NUM>) in the direction of the rotary axis (<NUM>),
wherein the positioning portion (<NUM>) interacts with the securing element (<NUM>) so as to additionally position the stator (<NUM>) in the housing (<NUM>) axially in the direction of the rotary axis (<NUM>).