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Patent Searching and Data


Title:
BRUSHLESS ELECTRIC MOTOR
Document Type and Number:
WIPO Patent Application WO/2019/052835
Kind Code:
A1
Abstract:
The invention relates to a brushless electric motor (10), having a rotor (25) rotatably supported in a rotary axis (26), which comprises a magnetic element carrier (35) for fastening first magnetic elements (48), wherein the magnetic element carrier (35) is fixed in a non-rotatable manner with a shaft (22) of the rotor (25). According to the invention, it is provided that the magnetic element carrier (35) comprises a carrier element (36) consisting of plastic material.

Inventors:
SCHAEUBLE, Michael (Valeo Wischersysteme Gmbh, Valeostrasse 1, Bietigheim-Bissingen, 74321, DE)
Application Number:
EP2018/073440
Publication Date:
March 21, 2019
Filing Date:
August 31, 2018
Export Citation:
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Assignee:
VALEO SYSTEMES D'ESSUYAGE (CS 90581, ZA L' Agiot8 Rue Louis Lorman, LA VERRIERE LE MESNIL SAINT DENIS, 78322, FR)
International Classes:
H02K1/27; H02K29/08; H02K7/04
Foreign References:
US20030168925A12003-09-11
EP2852031A12015-03-25
US4259603A1981-03-31
Other References:
None
Attorney, Agent or Firm:
CALLU-DANSEUX, Violaine (ZA L' Agiot, 8 Rue Louis LormandCS 90581 LA VERRIERE, LE MESNIL SAINT DENIS, 78322, FR)
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Claims:
Claims

1 . Brushless electric motor (10), having a rotor (25) rotatably supported in a rotary axis (26), which comprises a magnetic element carrier (35) for fastening first magnetic elements (48), wherein the magnetic element carrier (35) is fixed in a non-rotatable manner with a shaft (22) of the rotor (25), characterized in that the magnetic element carrier (35) comprises a carrier element (36) consisting of plastic material.

2. Electric motor according to claim 1 ,

characterized in that

on the side radially facing the shaft (22), the carrier element (36) is connected to a sleeve-type spacer (50) consisting of metal, which is fixed in a non-rotatable manner with the shaft (22).

3. Electric motor according to claim 1 or 2,

characterized in that

the carrier element (36) is enclosed on a circumferential face (39) by a magnetic sleeve (46), and in that the first magnetic elements (48) are connected to the magnetic sleeve (46) on the side of the magnetic sleeve (46) facing away from the carrier element (36).

4. Electric motor according to claim 2 or 3,

characterized in that

the material of the carrier element (36) is injection-molded onto the spacer (50) and/or the magnetic sleeve (46).

5. Electric motor according to one of claims 1 to 4, characterized in that

the carrier element (36) comprises flanges (43, 44) extending radially around the rotary axis (26), between which are received the first magnetic elements (48) in the longitudinal direction.

6. Electric motor according to one of claims 1 to 5,

characterized in that

a carrier portion (58) radially extending around the rotary axis (26) for fastening second magnetic elements (60) of a sensor is molded onto the carrier element (36).

7. Electric motor according to claim 6,

characterized in that

the carrier portion (58) is connected to the carrier element (36) in the direction of the rotary axis (22) via an intermediate portion (56) reduced in diameter with respect to the carrier portion (58).

8. Electric motor according to one of claims 1 to 7,

characterized in that

the carrier element (36) comprises at least one cavity (52) for weight reduction.

9. Electric motor according to one of Claims 2 to 8,

characterized in that

the rotor (25) is rotatably supported by means of two bearing means (64, 66), and in that the two bearing means (64, 66) are fixed in a non- rotatable manner with the shaft (22), wherein the two opposite end faces (61 , 62) of the spacer (50) each form an axial stop for a bearing means (64, 66).

10. Electric motor according to one of claims 1 to 9,

characterized in that the carrier element (36) comprises multiple recesses (54) for receiving balancing weights (55) and preferably arranged at angular intervals equal in size with respect to the rotary axis (22).

1 1 . Electric motor according to claim 10,

characterized in that

the balancing weights (55) are received in the recesses (54), forming a press-fit connection.

12. Electric motor according to one of claims 9 to 1 1 ,

characterized in that

the bearing means (64, 66) are connected to the shaft (22) on the side facing away from the magnetic element carrier (35) by means of a cohesive connection, a force-fit connection or by means of an additional securing element.

13. Electric motor according to one of claims 1 to 12,

characterized in that

the electric motor (10) is formed as part of a wiper motor (100).

14. Electric motor according to one of claims 1 to 13,

characterized in that

the carrier element (36) is of drum-shaped design.

15. Electric motor according to one of claims 1 to 14,

characterized in that

the carrier element (36) is formed as an injection-moulding.

Description:
Brushless electric motor

Prior art

The invention relates to a brushless electric motor according to the preamble of claim 1 .

An electric motor of this kind is known to the applicant from practice. The known electric motor serves as a windscreen wiper drive for at least indirect moving of at least one windscreen wiper of a windscreen wiping unit in a motor vehicle. The known electric motor comprises for this purpose, as is known per se, a stator arranged stationary in a housing of the electric motor with several wire windings which interact with a rotatably supported rotor. The rotor serves as a magnetic element carrier for the fastening of first magnetic elements, which are arranged on the circumference of the magnetic element carrier, the magnetic element carrier being fixed in a non-rotatable manner to a shaft of the rotor. In the known electric motor, the magnetic element carrier is designed as a deep- drawn metal part. Due to the design as a deep-drawn part, the magnetic element carrier has a relatively large weight. Furthermore, second magnetic elements serving to detect the rotary angle position of the rotor need to be arranged on a special (annular) element on the rotor shaft, separate from the magnetic element carrier.

Disclosure of the invention

The brushless electric motor according to the invention with the features of claim 1 has the advantage that its magnetic element carrier has an especially low weight and can be produced especially economically. This is made possible, according to the invention, by a design of the magnetic element carrier in which it comprises a carrier element made of plastic. This carrier element according to the invention is designed to accommodate or carry the first magnetic elements on its outer circumference. Since the magnetic element carrier consists of plastic in the region of its carrier element, it can be made in economically advantageous manner in particular in an injection moulding process, so that especially low production costs may be achieved. Furthermore, the relatively low weight of the carrier element makes possible an especially high dynamics of the electric motor when the stator windings are energized.

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.

In order to fix the carrier element to the rotor shaft in a non-rotatable manner, it is provided in an advantageous design embodiment that, on the side radially facing the shaft, the carrier element is connected to a sleeve- type spacer consisting of metal, which is fixed in a non-rotatable manner to the shaft. The connection between this spacer and the shaft may be done, for example, by a glue connection, by cohesive connections such as welding or soldering, or by a force-fit connection such as caulking or the like.

In contrast with the aforementioned prior art, in order not to impair the magnetic flux properties of the magnetic element carrier despite the use of plastic for the carrier element, it is furthermore advantageous for the carrier element to be enclosed on a circumferential face by a magnetic sleeve consisting of ferromagnetic material, and for the first magnetic elements to be connected to the magnetic sleeve on the side facing away from the carrier element. The connection between the magnetic sleeve and the first magnetic elements is typically done by glue connections. A most especially preferred method of manufacture provides that the material of the carrier element is injection-moulded onto the spacer and/or the magnetic sleeve. Such a configuration or production of a structural unit consisting of the carrier element, the spacer and/or the magnetic sleeve has the advantage that the connection between the individual elements is accomplished solely by the injection moulding of the plastic material of the carrier element and therefore no other fastening elements or glue or the like are required.

In order to arrange the first magnetic elements at a defined place, looking in the longitudinal direction or the direction of the rotary axis of the rotor, and also to make possible an especially easy assembly process, it is furthermore advantageous for the carrier element to comprise flanges extending radially around the rotary axis, between which are received the first magnetic elements in the longitudinal direction. Such flanges in one embodiment of the carrier element may be very easily realized as an injection-moulding.

A most especially preferred embodiment of the carrier element furthermore provides that a radially encircling carrier portion for fastening second magnetic elements of a sensor is moulded onto the carrier element. These second magnetic elements, as already mentioned above, serve for the detecting of the rotary angle position or the position of the rotor and thus for the actuating or energizing of the stator windings. Since the second magnetic elements can be arranged directly on the carrier element by way of the radially encircling carrier portion, it is possible to design the carrier element, together with the spacer and the magnetic sleeve as well as the first and second magnetic elements, as a premounted assembly, which is subsequently connected to the rotor shaft. Such a design thus makes possible an especially economical assembly process, which is especially advantageous from the standpoint of production.

Both for cost reasons and in particular for reasons of the lowest possible weight of the carrier element it is provided that the carrier element has at least one cavity for weight savings.

In order to mount the rotor inside the electric motor, it is provided that the rotor is rotatably supported by means of two bearing means, while the two bearing means are fixed in a non-rotatable manner with the rotor shaft, wherein the two opposite end sides of the (sleeve-shaped) spacer of the magnetic element carrier each form an axial stop for one of the bearing means. Thus, an axial positioning of the bearing means relative to the magnetic element carrier is made possible in especially simple manner with no additional components or no additional assembly step, such as a press fitting of the bearing means on the shaft.

Another especially preferred embodiment of the carrier element provides that it comprises multiple recesses for receiving balancing weights and preferably arranged at angular intervals equal in size with respect to the rotary axis. Such a design of the carrier element has the advantage that no additional components or glue needs to be used for the fastening of balancing weights.

Especially in connection with the recesses it is provided that the balancing weights are received in the recesses, forming a press-fit connection. These press-fit connections enable a secure fastening of the balancing weights in the recesses.

In order to fix the bearing means serving for the mounting of the rotor in the electric motor in their axial position, it is provided that the bearing means are connected to the shaft on the side facing away from the magnetic element carrier by means of a cohesive connection, a force-fit connection or by means of an additional securing element.

A brushless electric motor as described is preferably formed as part of a wiper motor. Furthermore, its carrier element is of drum-shaped design and formed as an injection-moulding for the realization of its different segments or geometrical shapes.

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 a partly sectioned view of a brushless electric motor,

Fig. 2 the components of a magnetic element carrier used in the electric motor of Fig. 1 in exploded view,

Fig. 3 the magnetic element carrier of Fig. 2 in the mounted state in a side view,

Fig. 4 a carrier element with magnetic elements fastened to it in perspective representation, and

Fig. 5 a rotor of the electric motor with the magnetic element carrier of

Fig. 2 and 3 in a side view.

The same elements or elements with the same function are given the same reference numbers in the figures. Fig. 1 shows in partly sectioned representation a brushless electric motor 10, serving as part of a wiper motor 100. The wiper motor 100 has a multiple-piece housing 12, in which a transmission gear 14 is rotatably supported. The transmission gear 14 in the exemplary embodiment shown is part of a single-stage transmission, but it may also be part of a multistaged transmission. The transmission gear 14 acts on a driven shaft 16, arranged perpendicular to the plane of the drawing in Fig. 1 , which is coupled at least indirectly to a windscreen wiper to be moved or a wiper rod of a windscreen wiping unit.

The transmission gear 14 comprises on its outer circumference a (helical) gearing 18, which meshes with a gearing of a shaft 22, especially one configured as a worm gear 20. The shaft 22 is part of a rotor 25 of the electric motor 10 and is rotatably supported about a rotary axis 26 (Fig. 5). The rotor 25 interacts with windings 28 of a stator 30 arranged in the region of the housing 12. The stator 30 is arranged stationary in the housing 12 and the windings 28 are actuated in proper time and phase by a control unit, not shown, for the driving of the rotor 25, as is familiar in itself from the prior art. The housing 12 is enclosed by a housing cover 32 in the region of the stator 30, as shown in Fig. 1 .

The shaft 22 of the rotor 25 is connected in a non-rotatable manner to a magnetic element carrier 35, shown by itself in Fig. 2 and 3. The magnetic element carrier 35 has a drum-shaped carrier element 36 made of plastic, especially one produced in an injection moulding process. The carrier element 36 has a cylindrically shaped segment 38 with a round circumferential face 39 in cross section. The segment 38 is bounded by two radially encircling flanges 43, 44 in the direction of a longitudinal axis 41 , which in the mounted state of the magnetic element carrier 35 is aligned with the shaft 22 with the rotary axis 26, which protrude radially beyond the circumferential face 39. Between the two flanges 43, 44, a magnetic sleeve 46 consisting of a ferromagnetic material such as steel is directly arranged on the circumferential face 39 or fastened to it. On the side of the magnetic sleeve 46 facing away from the circumferential face 39 there are furthermore fastened first magnetic elements 48 with alternating polarity in the circumferential direction between the flanges 43, 44, which are connected to the magnetic sleeve 46 in particular by glue connections. The first magnetic elements 48 extend, as is especially well seen from Fig. 3 and 5, in the longitudinal direction right up to the flanges 43, 44. As is furthermore seen in particular from Fig. 4, the carrier element 46 has a centrally arranged through opening 49, which is designed to enclose radially a sleeve-shaped spacer 50, especially one made of metal, as is especially well seen in Fig. 2. The spacer 50 is connected in a non- rotatable manner to the carrier element 36.

In order to produce the fastening between the carrier element 36 and the spacer 50 as well as the magnetic sleeve 46, the spacer 50 and the magnetic sleeve 46 are preferably inserted into an injection moulding die for the making of the carrier element 36 and then the molten material of the carrier element 36 (consisting in particular of a thermoplastic material) is injection-moulded onto the outer circumference of the spacer 50 and the inner circumference of the magnetic sleeve 46, wherein the carrier element 36 is given its special shape by an appropriate configuration of the injection moulding die.

As can be seen furthermore from Fig. 4, several cavities 52 extending in the longitudinal direction and serving for weight reduction are formed in a radial intermediate region between the through opening 49 and the circumferential face 39. Furthermore, recesses 54 having a round circular cross section in the exemplary embodiment are formed radially outside the cavities 52, preferably at equal angular intervals about the longitudinal axis 41 , in order to receive balancing weights 55. The balancing weights 55 here preferably have a slightly larger cross-sectional area than the recesses 54, so that the balancing weights 55 are held firmly in the recesses 54 by axial press fitting of the balancing weights 55 into the recesses 54, even without additional glue or the like.

At an axial distance from the one flange 44, a carrier portion 58 is formed monolithically with the carrier element 36 across an intermediate portion 56. The intermediate portion 56 here has a smaller diameter than the carrier portion 58 (likewise circular in shape). On the outer circumference of the carrier portion 58 are arranged or fastened several second magnetic elements 60 with alternating polarity in the circumferential direction of the carrier portion 58, for example by glue connections. The second magnetic elements 60 are part of a sensor, not shown in the figures, for detecting the rotary angle position of the rotor 25.

The spacer 50 extends, looking in the longitudinal direction, beyond the two flanges 43, 44, as is especially well seen in Fig. 3 and 5. On the side facing away from the flanges 43, 44, the spacer 50 by its respective end face 61 , 62 forms an axial stop for a respective bearing means 64, 66, recognizable in Fig. 5, for the rotatable mounting of the rotor 25 in the housing 12 of the wiper motor 100. At the side facing away from the spacer 50, the bearing means 64, 66 is fastened to the shaft 22 by a cohesive or force-fit connection or by a separate connection element, not shown.

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 Transmission gear

16 Driven shaft

18 Gearing

20 Worm gear

22 Shaft

25 Rotor

26 Rotary axis

28 Winding

30 Stator

32 Housing cover

35 Magnetic element carrier

36 Carrier element

38 Segment

39 Circumferential face

41 Longitudinal axis

43 Flange

44 Flange

46 Magnetic sleeve

48 First magnetic element

49 Through opening

50 Spacer

52 Cavity

54 Recess

55 Balancing weight

56 Intermediate portion

58 Carrier portion

60 Second magnetic element

61 End face End face Bearing means Bearing means Wiper motor