DE102005022435A1 - Carbon brush design for electric machine, has rear face spring for supporting the brush - Google Patents

Abstract

A carbon brush (1) is mainly a bar-shaped body in which the front face of the brush rests on a commutator, a spring on a rear face of the brush supports the brush which is movably carried in a brush holder. The brush (1) has at least two shaped molded zones (7,8) for guiding the brush in the brush holder.

Description

The Invention relates to a carbon brush, essentially rod-shaped trained, for an electric machine, wherein a front end face of the carbon brush on a commutator rests, a spring on a rear face of the carbon brush this supports and the carbon brush in a carbon brush holder movably guided is. This creates a sliding contact between carbon brush and commutator. Occurring signs of wear the front end of the carbon brush are by means of the prestressed Balanced spring.

Carbon brushes are important functional parts for power transmission in electrical Machinery. They find particular application in DC machines with mechanical commutation. With the help of carbon brushes and a commutator is a DC voltage in a motor Transformed AC voltage.

Usual constructions for one Carbon brush and a carbon brush holder are based on a rectangular cross-section of the two parts the one you want Game for the mobile leadership of the Carbon brush. It is one as possible low-backlash leadership the carbon brush important to achieve the electrical characteristics of the machine and to hold. From the identical cross sections of the carbon brush and the carbon brush holder As well as the small game shows that the vast majority of the outer surfaces of carbon brush on the inner surfaces of the Carbon brush holder is in contact or in contact. Is the electric machine in use, so it is often the case especially in open design machines Case that foreign matter, such as dust, between carbon brush and carbon brush holder store. As with the usual Constructions the outer surfaces of the carbon brush and the inner surfaces the carbon brush holder can lie against each other the aforementioned foreign matter deposits a binding or a clamping of the carbon brush in the carbon brush holder for Episode. This requires the carbon brush with increased force pressed to the commutator become. Should the frictional resistance due to the foreign material deposits even bigger than the pressure force of the spring leads this to the carbon brush no longer tracked can be and thus an interruption of the current flow, d. H. a failure of the electric machine, takes place. Such operational failures are not wanted in practice.

From the EP 0 719 465 B1 a carbon brush for an electric motor is known, which is rod-shaped and has different cross-sections perpendicular to the longitudinal axis. A cross section perpendicular to the longitudinal axis of the carbon brush near the front end surface and the front end surface itself are trapezoidal and a cross section near the rear end surface is formed rectangular or square. These different cross sections of the carbon brush should produce as little noise as possible when used in an electric motor.

It is therefore the object of the present invention, a carbon brush such to develop that on the one hand a low-backlash leadership in the carbon brush holder allows and on the other machine failures due to foreign deposits between carbon brush and Carbon brush holder be prevented.

According to the invention Task solved with the features of claim 1. advantageous Further developments can be found in the dependent claims.

The carbon brush is essentially rod-shaped formed, wherein a section perpendicular to its longitudinal axis is substantially rectangular. The rectangular area faces four pages on, with two opposite sides the same Have length and are arranged in parallel. At least two to the longitudinal axis parallel opposite Sides of the carbon brush have profile areas. The profile areas protrude over the original rectangular area of the section to the longitudinal axis the carbon brush out. With the profile areas, the carbon brush becomes in the carbon brush holder guided, being the lead with the least possible Game takes place.

The other two to the longitudinal axis parallel opposite Pages have no profile areas. Rather, these pages become with a big game in the carbon brush holder guided. This creates a distance between carbon brush and at several areas Carbon brush holder. This distance leads to that in these areas the carbon brush and the carbon brush holder do not touch each other. Foreign substances may be exposed in these Although still storing areas, but have by the predominant big game or the distance only a small frictional resistance result. This low frictional resistance has only a minor effect on the compressive force of the Spring off, d. H. wear on the front end of the carbon brush can easily from the spring be balanced, but do not relate to disability the functionality the carbon brush represents.

Also between the profile area, which serves to guide the carbon brush in the carbon brush holder, and carbon brush may foreign substances to store. This can briefly lead to a frictional resistance and thus a reduction in the pressure force of the spring. Since the electrical machine generates mechanical energy in the operating state, the machine, and thus also the carbon brush itself, undergoes mechanical movements. As a result of these movements, the stored foreign substances migrate between the profile regions of the carbon brush and the carbon brush holder into the adjacent, exposed regions and thus do not constitute a hindrance to the carbon brush.

advantageously, is the carbon brush designed such that the profile areas in relation to the total outer contour the carbon brush occupy only a small area, so that the carbon brush predominantly not on the carbon brush holder.

Preferably points the carbon brush in the direction of its longitudinal axis four profile areas for guidance in the carbon brush holder on. Each side has a parallel to the longitudinal axis of the carbon brush Profile area on. Four profile areas have opposite two Profile areas the advantage that the carbon brush safer and more accurate in the carbon brush holder guided can be.

With particular advantage, the carbon brush holder on two side surfaces of Carbon brush holder protuberances on. By means of the protuberances will be an additional Distance between the carbon brush and the carbon brush holder produced. This ensures that that the carbon brush Mostly not on the carbon brush holder or in contact.

Preferably is the carbon brush arranged in small electric motors open design. electrical Small engines become predominant Used in the automotive sector. In automobiles, it is inevitable that foreign substances from the environment are stored in the small engines, wherein especially in this area operating failures of small engines are undesirable.

The Carbon brush holder is made of metal, preferably brass.

In The following description describes further features and details the invention in conjunction with the accompanying drawings with reference to embodiments explained in more detail. there are features and relationships described in individual variants basically to all Embodiments transferable. In the drawings show:

1 a perspective view of a first embodiment of the carbon brush according to the invention;

2 a front view of a first embodiment of the carbon brush according to the invention in the carbon brush holder;

3 a perspective view of a second embodiment of the carbon brush according to the invention; and

4 a front view of a second embodiment of the carbon brush according to the invention in the carbon brush holder.

In 1 is a perspective view of a first embodiment of the carbon brush according to the invention 1 shown. The carbon brush 1 is formed substantially rod-shaped, wherein a section perpendicular to its longitudinal axis is substantially rectangular. The rectangular area 2 has four pages 3 . 4 . 5 . 6 on, wherein two opposite sides have the same length and are arranged in parallel. At least two opposite sides parallel to the longitudinal axis 3 . 4 the carbon brush 1 have profile areas 7 . 8th on. The profile areas 7 . 8th protrude over the original rectangular area 2 of the section to the longitudinal axis of the carbon brush 1 out. With the profile areas 7 . 8th becomes the carbon brush 1 performed in a carbon brush holder, not shown with minimal play. The other two opposite sides parallel to the longitudinal axis 5 . 6 have no profile areas.

In 2 is a front view of a first embodiment of the carbon brush according to the invention 1 in a carbon brush holder 15 shown. As in 2 can be seen, serve the profile areas 7 . 8th for guiding the carbon brush 1 in the carbon brush holder 15 , There is a distance between carbon brush 1 and carbon brush holder 15 at the areas 13 and 14 that have no profile. This distance causes foreign matter in the areas 13 and 14 Although still can store, by the predominantly large game or the distance but only a small frictional resistance result. Also at the profile areas 7 . 8th , there is a possibility that foreign matter between profile area 7 . 8th and carbon brush holder 15 store. Since an electric machine, not shown, generates mechanical energy in the operating state, the machine, not shown, and thus also the carbon brush are subject 1 itself, mechanical movements. These movements can be used to store any foreign substances between the profile areas 7 . 8th the carbon brush 1 and the carbon brush holder 15 into the neighboring, exposed areas 13 and 14 hike.

In 3 is a perspective view of a second embodiment of the carbon brush according to the invention 1 shown. The rectangular area 2 has four pages 3 . 4 . 5 . 6 on. Each of the four sides 3 . 4 . 5 . 6 has a profile area 7 . 8th . 9 . 10 on. The profile areas protrude over the original rectangular area 2 of the section to the longitudinal axis of the carbon brush 1 out. With the profile areas 7 . 8th . 9 . 10 becomes the carbon brush 1 in the carbon brush holder 15 guided with minimal play. Furthermore, in 3 an electrical connection element 16 for the electrical connection of the carbon brush 1 to see.

4 shows a front view of a second embodiment of the carbon brush according to the invention 1 in the carbon brush holder 15 , The carbon brush 1 is with the profile areas 7 . 8th . 9 . 10 fitted. The profileless areas 11 . 12 . 13 . 14 do not lie on the carbon brush holder 15 at. The carbon brush holder 15 preferably has two protuberances 17 and 18 on. By means of the protuberances 17 and 18 there will be an extra space between carbon brushes 1 and carbon brush holder 15 at the profile areas 9 and 10 produced. This ensures that the carbon brush 1 mostly not on the carbon brush holder 15 is applied. Furthermore, in 4 an electrical connection element 16 for the electrical connection of the carbon brush 1 to see.

1

carbon brush

2

cut to the longitudinal axis

3-6

Sides of the cut 2

7-10

Profile areas of the pages 3 - 6

11-14

Unprofiled areas of the sides 3 - 6

15

Carbon brush holder

16

electrical connecting element

17-18

protuberances

Claims (8)

Carbon brush ( 1 ), formed substantially rod-shaped, for an electric machine, wherein a front end face of the carbon brush ( 1 ) abuts a commutator, a spring on a rear end face of the carbon brush ( 1 ) this supports and the carbon brush ( 1 ) in a carbon brush holder ( 15 ) is movably guided, characterized in that the carbon brush ( 1 ) on at least two opposite sides ( 3 . 4 ) parallel to the longitudinal axis with profile areas ( 7 . 8th ) for guiding the carbon brush ( 1 ) in the carbon brush holder ( 15 ) Is provided. Carbon brush ( 1 ) according to claim 1, characterized in that between the profile areas ( 7 . 8th ) and the carbon brush holder ( 15 ) lowest possible game exists. Carbon brush ( 1 ) according to claim 1 or 2, characterized in that the sides ( 3 . 4 ) profileless areas ( 13 . 14 ) having. Carbon brush ( 1 ) according to one or more of the preceding claims, characterized in that the carbon brush ( 1 ) on two opposite sides ( 5 . 6 ) parallel to the longitudinal axis with non-profiled areas ( 11 . 12 ) Is provided. Carbon brush ( 1 ) according to one or more of the preceding claims, characterized in that between the non-profiled areas ( 13 . 14 ) and the carbon brush holder ( 15 ) is as large a game as possible such that a distance between the non-profiled areas ( 13 . 14 ) of the carbon brush ( 1 ) and the carbon brush holder ( 15 ) is available. Carbon brush ( 1 ) according to one or more of the preceding claims, characterized in that the profile areas ( 7 . 8th . 9 . 10 ) in relation to the entire outer contour of the carbon brush ( 1 ) take only a small area, so that the carbon brush ( 1 ) mostly not on the carbon brush holder ( 15 ) is present. Carbon brush ( 1 ) according to one or more of the preceding claims, characterized in that the carbon brush ( 1 ) is arranged in small electric motors open design. Carbon brush ( 1 ) according to one or more of the preceding claims, characterized in that the carbon brush holder ( 15 ) made of metal, in particular brass.