Electronically commutated internal-rotor electric motor

Abstract

The invention relates to an electronically commutated internal-rotor electric motor (10; 10a; 10b), in particular as part of a wiper motor, the electric motor (10; 10a; 10b) comprising a motor housing (12; 12a; 12b) having an insertion opening (14) for inserting a stator (16; 16a; 16b) into an interior (18) of the motor housing (12; 12a; 12b), the stator (16; 16a; 16b) having a longitudinal axis (26), the stator (16; 16a; 16b) being accommodated in the interior (18) in such a manner that it is positioned in an axial direction and at a rotation angle in relation to its longitudinal axis (26) when in an end position.

Description

Electronically commutated internal-rotor electric motorTechnical Field

[0001] The invention relates to an electronically commutated internal-rotor electric motor, in particular as part of a wiper motor, which is characterized by a particularly advantageous and simple positioning of a stator in a motor housing.Background Art

[0002] An electronically commutated internal-rotor electric motor as part of a wiper motor with the features of the preamble of the independent claims is known from WO 2023 / 123527 A1. The known electric motor is characterized in that a press fit between the stator and its motor housing is formed for fixing the stator in the motor housing. For this purpose, the motor housing has an inner wall with three areas of different diameters, which has the effect that the desired press fit is gradually established as the stator is inserted into the motor housing. Producing such a motor housing for achieving the press fit is relatively complex, i.e. , it requires precise manufacture in order for the forces needed during insertion to not become too high or be too low.Disclosure of the Invention

[0003] The electronically commutated internal-rotor electric motor according to the invention, in particular as part of a wiper motor, with the features of the independent claims has the advantage that alternative methods of positioning and fixing the stator in the motor housing are offered, which are relatively easy to implement in terms of manufacture and allow precise positioning of the stator in the motor housing both in an axial end position and, optionally, in its desired angular rotation position in relation to the motor housing.

[0004] In light of the explanations above, a first electronically commutated internal-rotor electric motor according to the invention therefore comprises a motor housing having an insertion opening for inserting a stator into an interior of the motor housing. The stator has a longitudinal axis, and the stator is furthermore accommodated in the interior in such a manner that it is positioned in an axial direction and at a rotation angle in relation to its longitudinal axis when in an end position. According to the invention, the first embodiment provides for an annular gap to be formed between an outer contour of the stator and an inner wall limiting the interior toward the stator, the annular gap narrowing in the direction of the end position of the stator in the motor housing, for at least one protrusion protruding radially inward in relation to the longitudinal axis to be formed on the inner wall of the housing, the protrusion serving as a stop element for the stator in the axial direction, the stop element interacting with an end face of the stator when the stator is in the end position, and for means for positioning the stator at a defined rotation angle in relation to the motor housing to be provided.

[0005] In a preferred embodiment of the first electric motor according to the invention, the annular gap gradually narrows in the direction of the end position, preferably down to an annular gap of zero in the end position, the motor housing preferably having at least three different inner diameters.

[0006] According to a preferred embodiment of the latter proposal, a sliding fit is established between the stator and the inner wall in the end position. In other words, this means that the stator is accommodated in the motor housing without radial play when in its axial end position.

[0007] Preferably, the means for defined angular positioning between the motor housing and the stator are formed by at least one protrusion disposed on the stator and protruding radially outward in relation to thelongitudinal axis of the stator, the protrusion interacting with a complementary recess in the inner wall of the motor housing.

[0008] In an alternative, second configuration of the electric motor or the positioning of the stator in the motor housing as per the invention, means for correct angular positioning between the motor housing and the stator in relation to the longitudinal axis of the stator are provided between the stator and the housing, the means comprising at least one protrusion disposed on the stator and protruding radially outward in relation to the longitudinal axis of the stator, the protrusion interacting with a complementary recess in the inner wall of the motor housing, and a receiving slot for the protrusion is formed on the inner wall of the motor housing in the axial end position, the receiving slot extending from the recess in a circumferential direction of the inner wall and serving to receive the protrusion in such a manner that a bayonet coupling is formed when the stator is rotated about its longitudinal axis.

[0009] In the latter configuration of the electric motor, it is preferred for multiple protrusions to be present, which are disposed at irregular angular intervals about the longitudinal axis in the circumferential direction. In particular, the irregular angular intervals enable a distinct rotation angle of the stator in relation to the housing.

[0010] In yet another alternative, third configuration of the electric motor, an annular gap may be formed between an inner wall of the motor housing and an outer contour of the stator, a pin oriented parallel to the longitudinal axis of the stator being disposed in the annular gap, the pin positioning the stator at its rotation angle in relation to the longitudinal axis with respect to the motor housing and fixing the stator in relation to the motor housing by a clamping fit or press fit.

[0011] In an embodiment of the latter proposal, the cross section of the pin interacts with a longitudinal groove on the stator in a form-fitting manner.

[0012] Irrespective of the concrete constructive solution proposed, all approaches advantageously provide for the stator to be formed by a plurality of interconnected die-cut metal plates stacked on top of each other.

[0013] Furthermore, it is provided for the motor housing to be an injection- molded plastic part. This makes it possible for the intended geometrical features to be produced in a particularly simple and precise manner.

[0014] Other advantages, features, and details of the invention are apparent from the following description of preferred embodiments of the invention and from the drawings.Brief Description of the Drawings

[0015] Fig. 1 is a cross-section view of a first embodiment of the electric motor;

[0016] Fig. 2 is a partial longitudinal-section view in plane ll-ll of Fig. 1 ;

[0017] Fig. 3 is a cross-section view of a second embodiment of the electric motor, in which the stator is accommodated in the motor housing through a bayonet coupling;

[0018] Fig. 4 is a view of a section of the inner wall of the motor housing of Fig. 3 in the area of a bayonet coupling; and

[0019] Fig. 5 is a perspective view of a third embodiment of the electric motor, in which the stator is fixed in relation to the motor housing by a pin.Embodiments of the Invention

[0020] Similar elements or elements having a similar function are designated by similar reference signs in the figures.

[0021] Figs. 1 and 2 show part of a first electronically commutated internalrotor electric motor 10, which serves in particular as part of a wiper motor in a vehicle.

[0022] The electric motor 10 has a motor housing 12, which is made of plastic and produced by injection molding, the motor housing 12 having an insertion opening 14 for inserting a stator 16 into an interior 18 of the motor housing 12 on an end face. The stator 16 is inserted into the interior 18 in the direction of arrow 20 in Fig. 2. The stator 16 is composed of a plurality of stacked stator laminations 22, which are interconnected in a known manner and which are die-cut metal plates and which serve to dispose a plurality of stator windings 24 according to the illustration of Fig. 1 ; in the exemplary embodiment illustrated, there are nine stator windings 24.

[0023] The stator 16 has a longitudinal axis 26 which runs perpendicular to the drawing plane of Fig. 1 , a rotor carrying permanent-magnet elements (not shown) being disposed in alignment with the longitudinal axis 26, as is known from the prior art. The stator 16 or the stator laminations 22 have an at least essentially round outer cross section, with the exception of three protrusions 28, 30, 32, which are formed on the stator 16 at irregular angular intervals about the longitudinal axis 26 of the stator 16 and protrude radially outward. The protrusions 28, 30, 32 serve to position the stator 16 at the correct rotation angle in relation to its longitudinal axis 26 with respect to the motor housing 12, in particular for establishing electrical contact between the stator windings 24 and contact elements (not shown). To this end, the protrusions 28, 30, 32 interact with complementary longitudinal slots 36 formed on an inner wall 34 of the motor housing 12.

[0024] As can further be seen in Fig. 2, the inner wall 34 has areas having three different inner diameters d1 , d2 and d3 when viewed in the direction of the longitudinal axis 26 of the stator 16. When the stator 16 is in the axial end position in the interior 18 of the motor housing 12, a sliding fit is established between inner diameter d1 of the inner wall 34 and the outer diameter of the stator 16, whereas annular gaps 38 ofdifferent sizes are formed between the stator 16 and inner diameters d2 and d3. In particular, the inner diameters d1 to d3 narrow toward the axial end position of the stator 16 in the motor housing 12 when viewed in the direction of the longitudinal axis 26.

[0025] Finally, a stop 39, e.g., in the form of an annular protrusion, which is formed on the inner wall 34 of the motor housing 12 and extends radially in the direction toward the longitudinal axis 26 is visible in Fig. 2, the stop 39 serving as an axial stop for an end face 40 of the stator 16 or the stator laminations 22 during the insertion into the interior 18 when the stator 16 has reached its axial end position in the motor housing 12; the axial end position is shown in Fig. 2. For example, it may be intended for the motor housing 12 to be closed by means of a housing cover (not shown), which forms a stop for the stator 16, so as to secure the stator 16 in the motor housing 12 against the direction of the stop 39.

[0026] Figs. 3 and 4 show an electric motor 10a, which essentially differs from the electric motor 10 according to Figs. 1 and 2 in that the protrusions 28a, 30a, 32a of the stator 16a, which protrude radially outward, are only formed on the end face 40 of the stator 16a that faces the interior 18 on one or more stator laminations 22 and serve as part of a bayonet coupling 42 between the stator 16a and the motor housing 12a. To this end, receiving slots 48 extending about the longitudinal axis 26 in the circumferential direction may be formed on the inner wall 44a of the motor housing 12a in the axial end position of the stator 16a in the motor housing 12a, the receiving slots 48 extending about longitudinal axis 26 across merely a small rotation angle range. Once the stator 16a has reached the axial end position in the motor housing 12a, the stator 16a is turned clockwise according to rotation arrow 52, causing the stator laminations 22 provided with the protrusions 28a, 30a, 32a to interact with the receiving slots 48, whichfix the stator 16a in the axial direction in relation to the motor housing 12. In this regard, reference is made to the illustration of Fig. 4, in which the protrusions 28a are shown by dashed lines in the axial end position of the stator 12a prior to the rotation of the stator 16a about the longitudinal axis 36. From this position, the protrusions 28a move into their end positions in the direction of arrow 54.

[0027] Finally, Fig. 4 shows an electric motor 10b which has an annular gap 56 formed between the stator 16b and the inner wall 44 of the motor housing 12b. Moreover, as an example, the outer contour of the stator 16b has longitudinal grooves 58 disposed at regular angular intervals in relation to each other. A fixing pin 60 disposed parallel to the longitudinal axis 26 of the stator 16b is provided in the annular gap 56, the cross section of the fixing pin 60 interacting with the longitudinal groove 58 in a form-fitting manner. The fixing pin 60 serves to fix the stator 16b in relation to the motor housing 12b and simultaneously brings about the required or desired angular position of the stator 16 in relation to the motor housing 12. It will be connected to the motor housing 12b once the stator 12b has been installed.

[0028] The electric motor 10, 10a and 10b thus described can be altered or modified in various ways without departing from the spirit of the invention.Reference signs

[0029] 10, a, b electric motor

[0030] 12, a, b motor housing

[0031] 14 insertion opening

[0032] 16, a, b stator

[0033] 18 interior

[0034] 20 arrow

[0035] 22 stator lamination

[0036] 24 stator winding

[0037] 26 longitudinal axis

[0038] 28, a protrusion

[0039] 30, a protrusion

[0040] 32, a protrusion

[0041] 34 inner wall

[0042] 36 longitudinal slot

[0043] 38 annular gap

[0044] 39 stop

[0045] 40 end face

[0046] 42 bayonet coupling

[0047] 48 receiving slot

[0048] 52 rotation arrow

[0049] 54 arrow

[0050] 56 annular gap

[0051] 58 longitudinal groove

[0052] 60 fixing pin

[0053] d1 , d2, d3 inner diameter

Claims

Claims1 . An electronically commutated internal-rotor electric motor (10), in particular as part of a wiper motor, the electric motor (10) comprising a motor housing (12) having an insertion opening (14) for inserting a stator (16) into an interior (18) of the motor housing (12), the stator (16) having a longitudinal axis (26), the stator (16) being accommodated in the interior (18) in such a manner that it is positioned in an axial direction and at a rotation angle in relation to its longitudinal axis (26) when in an end position, characterized in that an annular gap (38) is formed between an outer contour of the stator (16) and an inner wall (34) limiting the interior (18) toward the stator (16), the annular gap (38) narrowing in the direction of the end position of the stator (16) in the motor housing (12); at least one protrusion (39) protruding radially inward is formed on an inner wall (34) of the housing (12), the protrusion (39) serving as a stop element for the stator (16) in the axial direction, the stop element interacting with an end face (40) of the stator (16) when the stator (16) is in the end position; and means for correct angular positioning of the stator (16) in relation to the motor housing (12) are provided between the stator (16) and the motor housing (12).

2. The electric motor according to claim 1 , characterized in that the annular gap (38) gradually narrows in the direction of the end position of the stator (16), preferably down to an annular gap (38) of zero in the end position, the motor housing (12) preferably having at least three different inner diameters (d1 , d2, d3).

3. The electric motor according to claim 2, characterized in thata sliding fit is established between the stator (16) and the inner wall (34) in the end position.

4. The electric motor according to any one of claims 1 to 3, characterized in that the means for correct angular positioning between the motor housing (12) and the stator (16) comprise at least one protrusion (28, 30, 32) protruding radially outward in relation to the longitudinal axis (26) of the stator (16), the protrusion (28, 30, 32) interacting with a complementary recess (36) in the inner wall (34) of the motor housing (12).

5. An electronically commutated internal-rotor electric motor (10a), in particular as part of a wiper motor, the electric motor (10a) comprising a motor housing (12a) having an insertion opening (14) for inserting a stator (16a) into an interior (18) of the motor housing (12a), the stator (16a) having a longitudinal axis (26), the stator (16a) being accommodated in the interior (18) in such a manner that it is positioned in an axial direction and at a rotation angle in relation to its longitudinal axis (26) when in an end position, characterized in that means for correct angular positioning between the motor housing (12a) and the stator (16a) are provided between the stator (16a) and the motor housing (12a), the means comprising at least one protrusion (28a, 30a, 32a) protruding radially outward in relation to the longitudinal axis (26) of the stator (16a), the protrusion (28a, 30a, 32a) interacting with a complementary recess (36) in an inner wall (34) of the motor housing (12a); and a receiving slot (48) for the protrusion (28a, 30a, 32a) is formed on the inner wall (34) of the motor housing (12a) in the end position of the stator (16a), the receiving slot (48) extending from the recess (36) in a circumferential direction about the longitudinal axis (26) and serving toreceive the protrusion (28a, 30a, 32a) in such a manner that a bayonet coupling (42) is formed when the stator (16a) is rotated about its longitudinal axis (26).

6. The electric motor according to claim 5, characterized in that multiple protrusions (28a, 30a, 32a) are present, which are disposed at irregular angular intervals about the longitudinal axis (26) in the circumferential direction.

7. An electronically commutated internal-rotor electric motor (10b), in particular as part of a wiper motor, the electric motor (10b) comprising a motor housing (12b) having an insertion opening (14) for inserting a stator (16b) into an interior (18) of the motor housing (12b), the stator (16b) having a longitudinal axis (26), the stator (16b) being accommodated in the interior (18) in such a manner that it is positioned in an axial direction and at a rotation angle in relation to its longitudinal axis (26) when in an end position, characterized in that an annular gap (56) is formed between an inner wall (34) of the motor housing (12b) and an outer contour of the stator (16b), a pin (60) disposed parallel to the longitudinal axis (26) being disposed in the annular gap (56), the pin (60) positioning the stator (16b) in its angular position in relation to the longitudinal axis (26) with respect to the motor housing (12b) and fixing the stator (16b) in relation to the motor housing (12b) by a clamping or pressing fit.

8. The electric motor according to claim 7, characterized in that the cross section of the pin (60) interacts with a longitudinal groove (58) on the stator (16b) in a form-fitting manner.

9. The electric motor according to any one of claims 1 to 8, characterized in that the stator (16; 16a; 16b) is formed by a plurality of interconnected stator laminations (22) disposed one above the other.

10. The electric motor according to any one of claims 1 to 9, characterized in that the motor housing (12; 12a; 12b) is an injection-molded plastic part.

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