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Title:
CARBON ELEMENT FOR A COMMUTATION DEVICE OF A DC MOTOR
Document Type and Number:
WIPO Patent Application WO/2017/186904
Kind Code:
A1
Abstract:
The invention relates to a carbon element (10) for a commutation device of a DC motor, wherein the carbon element (10) has a first end surface (11) which is designed to lie against a collector of the DC motor. According to the invention, it is provided that the first end surface (11) has, with respect to a plane (25) running perpendicularly to a centre plane (23) of the carbon element (10), two flat partial surfaces (21, 22) which are arranged at an angle (a), and that the carbon element (10) has its greatest axial extent in the centre plane (23).

Inventors:
KAPITZA HARALD (DE)
SÜSSER KARL-HEINZ (DE)
Application Number:
PCT/EP2017/060181
Publication Date:
November 02, 2017
Filing Date:
April 28, 2017
Export Citation:
Click for automatic bibliography generation   Help
Assignee:
VALEO SYSTEMES DESSUYAGE (FR)
International Classes:
H01R39/26; H01R39/41; H02K13/10; H02K5/14
Foreign References:
DE102004018932A12005-11-17
JP2008199892A2008-08-28
US20060103259A12006-05-18
US5594290A1997-01-14
Other References:
None
Attorney, Agent or Firm:
CALLU-DANSEUX, Violaine (FR)
Download PDF:
Claims:
Claims

1 . Carbon element (10) for a commutation device of a DC motor, wherein the carbon element (10) has a first end surface (1 1 ) which is designed to lie against a collector of the DC motor, characterized in that the first end surface (1 1 ) has, with respect to a plane (25) running perpendicularly to a centre plane (23) of the carbon element (10), two flat partial surfaces (21 , 22) which are arranged at an angle (a), and in that the carbon element (10) has its greatest axial extent in the centre plane (23). 2. Carbon element according to Claim 1 ,

characterized in that

the two partial surfaces (21 , 22) end at the centre plane (23) in the form of an intersecting line (26). 3. Carbon element according to Claim 1 or 2,

characterized in that

the angle (a) of the two partial surfaces (21 , 22) is identical in size and is between 1 degree and 25 degrees. 4. Carbon element according to one of Claims 1 to 3,

characterized in that

the carbon element (10) has a flexible contact cable (30), and in that the contact cable (30) is connected to the carbon element (10) level with the centre plane (23) in the region of a side surface (13, 14) of the carbon element (10).

5. Carbon element according to Claim 4,

characterized in that the contact cable (30) is designed in the form of a strand.

6. Carbon element according to one of Claims 1 to 5,

characterized in that

the carbon element (10) on the side facing away from the first end surface (1 1 ) has a second end surface (12) which runs perpendicularly to the centre plane (23) of the carbon element (10).

7. Carbon element according to one of Claims 1 to 6,

characterized in that

the carbon element (10) has two side surfaces (13, 14) arranged parallel to each other, and also a lower side (15) and an upper side (16), wherein the lower side (15) and the upper side (16) are arranged parallel to each other, and wherein the side surfaces (13, 14), the lower side (15) and the upper side (16) are designed to serve for guiding the carbon element (10) in the direction of a longitudinal axis (48) in a carbon-receiving element (40).

8. Carbon element according Claim 7,

characterized in that

the edges between the side surfaces (13, 14) and the lower side (15) or the upper side (16) are of rounded design or are provided with a bevel (17). 9. Carbon element according to one of Claims 1 to 8,

characterized in that

the carbon element (10) has a rectangular, preferably a square cross- sectional area. 10. Commutation device (100) for a DC motor, with a carbon element (10) which is designed according to one of Claims 1 to 9 and with a carbon- receiving element (40) for the form-fitting receiving and guiding of the carbon element (10) in the direction of a longitudinal axis (48) of the carbon element (10), wherein the carbon element (10) projects with its first end side (1 1 ) out of an opening (43) in the end side of the carbon-receiving element (40). 11. Commutation device according to Claim 10,

characterized in that

the carbon-receiving element (40) has, level with the centre plane (23) of the carbon element (10), a respective slot (46) on mutually opposite sides for conducting a contact cable (30).

12. Commutation device according to Claim 11 ,

characterized in that

the slot (46) originates in each case from an opening (43) of the carbon-receiving element (40), said opening facing the first end surface (11) of the carbon element (10), and reaches approximately up to half of the axial extent of the carbon-receiving element (40).

13. Windscreen wiper motor with a commutation device (100) according to one of Claims 10 to 12.

Description:
Carbon element for a commutation device of a DC motor

Prior art The invention relates to a carbon element for a commutation device of a DC motor according to the precharacterizing clause of Claim 1 . Furthermore, the invention relates to a commutation device for a DC motor with a carbon element according to the invention, and also to a windscreen wiper motor with a commutation device of this type.

A carbon element for a commutation device of a DC motor according to the precharacterizing clause of Claim 1 is already known in practice. In particular, a carbon element of this type is accommodated within what is referred to as a carbon cartridge and is pressed against the collector of the electric motor by means of spring force. The (DC) electric motor here customarily has either two or else four carbon elements which each lie simultaneously against the collector. Furthermore, the carbon element makes contact with or is connected to a power supply by means of a connecting cable consisting, for example, of a copper strand.

It is furthermore known from the prior art to design or to shape that end surface of the carbon element which faces the collector in such a manner that said end surface is provided, for example, with a radius which corresponds to the radius of the collector. It is also known to provide the end surface with a slope which runs over the entire end surface of the carbon element. The correspondingly shaped end surfaces of the carbon element serve, for example, to accelerate the entry operation in such a manner that the carbon element lies as rapidly as possible or with a large area against the collector in order to reduce the electric contact resistance. Furthermore, it is significant that, in particular because of the connecting cable which is arranged on a side surface of the carbon element, it is not possible in practice to use one and the same carbon element at different positions or for different carbon cartridges. This means that at least two different carbon elements are required for an electric motor.

Disclosure of the invention Starting from the prior art which has been presented, the invention is based on the object of developing a carbon element for a commutation device of a DC motor according to the precharacterizing clause of Claim 1 in such a manner that said carbon element is suitable for being able to be used at different positions or for different carbon cartridges on a DC motor. In particular, the diversity of types of carbon elements are intended to be reduced as a result, wherein it is desirable at the same time for the entry behaviour of the carbon element to furthermore be advantageous.

This object is achieved in the case of a carbon element for a commutation device of a DC motor by the features of Claim 1 .

The invention is based on the concept of designing or shaping the end surface of the carbon element, which end surface faces the collector, in such a manner that the carbon element can be arranged in different installation positions, in particular in two installation positions offset from each other by 180°, without the electric properties of the carbon element thereby being changed, or an electric connection of the carbon element being made difficult. For this purpose, it is provided according to the invention that the relevant end surface of the carbon element, which end surface faces the collector, has, with respect to a plane running perpendicularly to a centre plane of the carbon element, two flat partial surfaces which are arranged at an angle, wherein the carbon element has its greatest axial extent in the centre plane. Advantageous developments of the carbon element according to the invention for a commutation device of a DC motor are cited in the dependent claims. All combinations of at least two of the features disclosed in the description, the claims and/or the figures fall within the scope of the invention.

In particular, it is of advantage if the two partial surfaces of the end surface end at the centre plane or meet in the centre plane. This results in uniform abrasion of carbon with respect to the end surfaces on both sides of the centre plane during entry, wherein the greatest surface pressure against the carbon element can be obtained by the pointed shape in the region of the centre plane at which the two obliquely arranged partial surfaces of the end surface meet. This also results in the same properties in both directions of rotation in use in an electric motor which is reversible in the direction of rotation. Preferred angles with respect to the oblique position of the two partial surfaces on the end surface have turned out to be angles of between 1 ° and 25°, wherein the angles of the two partial surfaces with respect to the centre plane or with respect to a plane running perpendicularly to the centre plane are intended to be identical in size.

In order to be able to use that end surface of the carbon element which faces away from the collector for contact for a compression spring which presses the carbon element against the collector, it is furthermore preferably provided that the carbon element has a flexible contact cable, wherein the contact cable is connected to the carbon element level with the centre plane in the region of an end surface of the carbon element. As the result of the fact that the contact cable is connected to the carbon element in the region of the centre plane thereof, the possibility is provided of likewise forming an opening used for the conduction of the contact cable or a slot in the region of the carbon cartridge in the region of the centre plane of the carbon element, wherein said slot has to have a particularly small width because of the central arrangement of the contact cable. In order, in conjunction with the discussed compression spring which presses the carbon element against the collector, to product a resulting force on the carbon element, which force runs exactly in the centre plane of the carbon element, it is furthermore of advantage if that end surface of the carbon element which faces away from the collector runs perpendicularly to the centre plane of the carbon element.

The invention also comprises a commutation device for a DC motor with a carbon element according to the invention and described to this extent. The commutation device furthermore has a carbon-receiving element (carbon cartridge) for the form-fitting receiving of the carbon element, wherein the carbon element projects with its end surface out of an opening in the end side of the carbon-receiving element. In a development of the commutation device, it is provided for guiding or conducting the contact cable out of the carbon-receiving element that the carbon-receiving element has, level with the centre plane of the carbon element, a respective slot on mutually opposite sides for guiding the contact cable.

Finally, the invention also comprises a windscreen wiper motor using a commutation device described to this extent or a carbon element according to the invention. Further advantages, features and details of the invention emerge from the description below of preferred exemplary embodiments and with reference to the drawing, in which:

Fig. 1 shows a perspective view of a commutation device for a DC motor with a carbon cartridge and a carbon element according to the invention arranged in the latter, in a first position of the carbon element, Fig. 2 shows the commutation device according to Fig. 1 in a position in which the carbon element is rotated by 180° in relation to the position in Fig. 1 ,

Fig. 3 shows a side view of a carbon element, and

Fig. 4

and

Fig. 5 each show, in a perspective view, the carbon element according to Fig. 3 in different positions.

Identical elements or elements with an identical function are provided with the same reference numbers in the figures. Figs. 1 and 2 illustrate a commutation device 100 as part of a DC motor which is otherwise not shown and is preferably reversible in direction of rotation, as used in particular in a windscreen wiper motor. The commutation device 100 comprises a carbon element 10 which is of substantially cuboidal or pin-shaped design with a rectangular or square cross section. In particular, the carbon element 10 according to the illustration of Figs. 3 to 5 has a first end surface 1 1 , a second end surface 12, two side surfaces 13, 14 arranged opposite and parallel to each other, a lower side 15 and an upper side 16. The lower side 15 and the upper side 16 also run parallel to each other. The edges between the side surfaces 13, 14 and the lower side 15 or the upper side 16 can furthermore be rounded or provided with a bevel 17.

The first end surface 1 1 of the carbon element 10, which end surface is designed to lie against a collector (not illustrated) of the DC motor, has two partial surfaces 21 , 22 which are each of flat design. As can be seen in particular with reference to the illustration of Fig. 3, the carbon element 10 furthermore has a centre plane 23 at which the two partial surfaces 21 , 22 meet. The two partial surfaces 21 , 22 each have an angle a of preferably between 1 ° and 25° with respect to a plane 25 running perpendicularly to the centre plane 23.

As can be seen in particular with reference to Figs. 4 and 5, the two partial surfaces 21 , 22 intersect in the region of an intersecting line 26 in the region of the centre plane 23, wherein the carbon element 10 lies against the collector in the region of the intersecting line 26.

At one of the two side surfaces 13, 14, at the side surface 13 in the exemplary embodiment illustrated, a flexible contact cable 30 is connected to the carbon element 10. The contact cable 30 serves for the electrical contact connection of the carbon element 10 and is designed, for example, in the form of a copper strand or the like which is optionally provided with insulation (not illustrated). It is essential that the contact cable 30 is connected in the region of the centre plane 23 to the carbon element 10, preferably in the direction of the side facing the second end surface 12.

The carbon element 10 described to this extent is accommodated in the region of the side surfaces 12, 13, the lower side 15 and the upper side 16 of the carbon element 10 in a carbon-receiving element 40 (illustrated in Figs. 1 and 2) of the commutation device 100 and is guided by the sides of the carbon element 10 in the longitudinal direction in the carbon-receiving element 40, wherein the carbon-receiving element 40 is also referred to as a carbon cartridge. The carbon-receiving element 40 is connected, for example, to a carbon holder plate of the DC motor in a manner known per se by means of two extensions 41 , 42 which are arranged on the lower side of the carbon- receiving element 40. The carbon-receiving element 40 has a likewise rectangular receiving cross section for receiving the carbon element 10 with only a little play, wherein the carbon element 10 projects on the side facing the collector (not illustrated) out of an opening 43 in the end side of the carbon- receiving element 40. On the side facing the second end surace 12, force is applied to the carbon element 10 by a spring element (not illustrated), in particular a leg spring, and therefore the carbon element 10 is pressed against the collector. It is furthermore essential that the carbon-receiving element 40 has, level with the centre plane 23 of the carbon element 10, a respective slot 46 on opposite sides 44, 45 of the carbon-receiving element 40 for receiving the contact cable 30. In the exemplary embodiment illustrated, the slot 46 emerges from the opening 43 and reaches approximately up to half of the axial extent of the carbon-receiving element 40.

As can be seen with reference to the illustration of Figs. 1 and 2, the carbon element 10 is insertable with respect to a longitudinal axis 48 into the carbon- receiving element 40 in two positions differing by 180° with respect to the longitudinal axis 48, wherein the contact cable 30 projects either through the slot 46 on the one side 44 or else through the slot 46 on the other side 45 of the carbon-receiving element 40. The carbon element 10 described to this extent can be modified in diverse ways without departing from the inventive concept.

Reference signs

10 carbon element

1 1 end surface

12 end surface

13 side surface

14 side surface

15 lower side

16 upper side

17 bevel

21 partial surface

22 partial surface

23 centre plane

25 plane

26 intersecting line

30 contact cable

40 carbon-receiving element

41 extension

42 extension

43 opening

44 side

45 side

46 slot

48 longitudinal axis

100 commutation device a angle