WO2006045709A1

WO2006045709A1 - Brush for an electric machine

Info

Publication number: WO2006045709A1
Application number: PCT/EP2005/055258
Authority: WO
Inventors: Achim Neubauer; Andrew Pierson; Pascal Chaumet
Original assignee: Robert Bosch Gmbh
Priority date: 2004-10-22
Filing date: 2005-10-14
Publication date: 2006-05-04
Also published as: DE102004051463A1

Abstract

The invention relates to a brush (30) for an electric machine (10), whereby the brush (30) comprises a shaft (42) having a transversal section (46) comprising an outer contour (44) and the outer contour (44, 44.1, 44.2, 44.3, 44.4, 44.5) is embodied in a stream-lined manner. Said brush has, for example, the advantages of an optimisation of the efficiency and the current consumption of the direct current electro small motors comprising flat commutators due to the improved carbon geometry.

Description

Brush for an electric machine

State of the art

The invention relates to a brush for an electric machine after the

The preamble of claim 1. Such a brush comprises a shaft having a cross-sectional area having an outer contour.

Small electric motors that are mechanically commutated and operated in liquids and / or are traversed by liquids are as electric fuel pumps, as

Water pumps or the like in the automotive industry, and known as feed pumps or the like outside the automotive sector. Mechanical commutation systems for such engines are often plan commutators for space reasons. Due to dwindling resources for fuels / fuels and rising prices for electric energy, the importance of a high level of energy is increasing

Efficiency also for operated in liquids / fuels small electric motors. This applies in particular to motor vehicle applications. The power consumption is determined by the efficiency of the power supply chain, the magnetic utilization of the electrical energy (low magnetic losses) and the hydraulic (fluid-related) or mechanical (for example, bearing friction or the like) losses.

Advantages of the invention

The erfϊndungsgemäße brush for an electric machine with the features of claim 1 has the advantage of optimizing the efficiency and the

Current consumption of DC Small electric motors with flat commutator due to improved carbon geometry. Such a brush is optimized in geometry for reducing fluid friction and aquaplaning effects on the surface of planar commutators. For this purpose, the one shaft comprises a cross-sectional area having an outer contour, the outer contour being streamlined.

This is also possible as an alternative or in addition to an electric machine with a planar face having a plan commutator and with a Brush holder which holds brushes spring-loaded in quills and which has openings in the quivers at a bottom side facing the flat commutator, from which the brushes emerge and contact the end face of the flat commutator, the springs being spring-loaded with hooks on hangers laterally are formed at the openings are mounted, wherein the hooking means are arranged in a plane which is parallel and spaced from the flat end face of the commutator.

An implementation of the streamlined outer contour is possible in that the shaft has a plurality of longitudinal sides and that at least between two adjacent longitudinal sides, which are preferably at right angles to each other, a slope is formed whose width is greater than the width of at least one of the two adjacent longitudinal sides. This can be improved in that at least a first and second longitudinal side parallel to a first distance to each other, wherein the width of the first longitudinal side is greater than the width of the second longitudinal side, that the first and second longitudinal side are arranged symmetrically to a plane extends perpendicularly through the first and second longitudinal side, that a third and fourth longitudinal side symmetrical to the plane and preferably parallel and at a second distance from each other and that between the first longitudinal side and the third longitudinal side of a first slope and between the first longitudinal side and fourth longitudinal side second slope is formed.

If the third and fourth longitudinal sides are the same size and shorter than the second longitudinal side, then a brush type for motors with different directions of rotation can be used. Characterized in that the first and second bevels are wider than the third and fourth longitudinal side, the streamline shape can be improved. When the first and second ramps include a first angle symmetrical to the plane, the use of a brush type for motors with different directions of rotation is increased. This is further optimized by forming a third slope between the second longitudinal side and the third longitudinal side and a fourth slope between the second longitudinal side and the fourth longitudinal side, and the third and fourth slopes are wider than the third and fourth longitudinal sides. A completely symmetrical structure results from the fact that the third and fourth slopes include a second angle arranged symmetrically to the plane. The flow characteristics can be further optimized by making the first angle formed by the first and second bevels smaller than the second angle formed by the third and fourth bevels.

As further possibilities of a streamlined outer contour, round, oval, diamond-shaped, triangular or kidney-shaped shapes are possible.

The brushes are best suited for flat commutators by having an end face designed as a flat contact surface. Preferably, the brush on the side remote from a contact surface end face a slope for a scroll spring. In a preferred embodiment, the slope with the plane includes an angle of less than 90 °.

The said positive effects can be increased by using the brush in a brush holder for an electrical machine comprising quivers for at least one brush with a streamlined outer contour.

Preferably, the brush holder has two quivers for a planar commutator, which are formed parallel to each other and point in the same direction and extending at their alignable to a Plankommutator openings two in a plane

Suspension means for hooks of rolling springs. This reduces the vibrations of the brush over the rotating commutator, reduces the hydraulic loss and the average contact resistance between brush and Plankommutatorsegment and thus the losses in the voltage transition from stationary to the rotating parts of the electric motor and thus overall the efficiency and the necessary

Current consumption of the electric motor. In addition, this simultaneously increases the life of the drive, since the brush or Kommutatorverschleiß is reduced mainly by the lower vibrations. Ideally, this can reduce the thickness of the copper / carbon disk of the commutator or the length of the carbon brush for the same life or just the life can be extended beyond the known extent. - A -

Preferably, the quivers are open on both sides. This has the advantage that they can build shorter than closed quiver, since no tree space for springs must be provided, which increases the overall length.

These effects also affect an electric machine with such brushes and / or such a brush holder.

The Kohlegeometrie is designed such that the degree of coverage reduces the vibration excitation by the segment jumps between the individual Plommommutatorsegmenten and at the same time as a ship's bow the

Liquid or the fuel / fuel has little displacement surface and the liquid flows past the side. The bevels optimize not only the displacement (lower displacement losses) but also the tendency for the brushes to float on the liquid or the fuel (aquaplaning). As a result, the average gap height between brush and Plankommutatorsegment is minimized, a minimum inclination of the coal surface relative to the Kommutatorfläche prevented and in turn minimizes the current transfer losses between brush and commutator.

A coverage factor of e.g. 1.3 causes the brush to always rest on at least two segments, and therefore not at every transition from segment to zone

Segment of the plan commutator on the entire brush surface must absorb the vibration excitation of the respective segment jump, since it can at least partially still be supported on a previous segment. This reduces the vibration excitation and thus macroscopically also improves the efficiency and reduces the power consumption of the electric motor in the

Liquid.

The scroll spring is disposed over the brush such that it introduces axial and tangential force components into the coal, the axial force component producing the optimum contact force on the plan commutator and the tangential force ensuring smooth guidance in the brush guide of the brush holder. The spring constant of the scroll spring is close to zero, so that regardless of the residual length of the carbon brush over the life almost the same spring force on the carbon brush and the Plankommutator is exercised and the higher damping constant of the scroll spring the vibration behavior of the at least one brush on the at least two segments of the planar commutator in always the same way over the life improved. This introduction of the spring force on the brush thus improves the calming of the brush and thus a source of vibration. Overall, this results in lower vibrations between the rotating plan commutator and the stationary ones

Brushing, at a lower average gap or microscopic to more frequent or closer contact and thus more numerous and less voltage-intensive current transitions (also called "pittings") between the brush and commutator and thus just lower losses in the voltage transition, since the losses with increasing length and decreasing number of flashes / pittings and with increasing amount of liquid in the

Voltage transition increase. Overall, the more uniform contact pressure of the coal on the commutator segments over the life and the lower tendency to vibration leads to more homogeneous wear and lower losses in the voltage transition and macroscopically to higher efficiency.

Further advantages and advantageous developments emerge from the subclaims and the description.

drawing

An embodiment is shown in the drawing and in the following

Description explained in more detail. Show it:

1 shows an electrical machine in a longitudinal section,

FIG. 2 shows a detailed longitudinal section according to the sectional lines II-II in FIG. 3, FIG. 3 shows a plan view of the brush holder according to FIG. 2,

FIG. 4 shows a perspective view of brushes, roller springs and a commutator,

Figure 5 is a plan view of the commutator of Figure 4 and

Figure 6a to 6e alternative cross-sectional areas of brushes.

Description of the embodiment

In the figure 1, a part of an electric machine 10 is shown simplified in a longitudinal section. In the present embodiment, it is a brush-type DC motor, also called commutator, and part of a Fuel pump of a motor vehicle is. However, other applications, for example, in a fan, windows, wiper drive, seat adjuster or other applications in a motor vehicle are conceivable. It can also be a generator. The electrical machine 10 preferably has only one direction of rotation, which is why it is particularly intended for the already mentioned fan drive. Also due to the low noise, the electric machine 10 is best suited for a fan output.

In the electric machine 10, a commutator is arranged on the armature shaft in the case of a brushed DC motor. in case of a

Generator this would be a slip ring.

The electric machine 10 comprises a housing, in particular a pole tube 12, and an armature 14 arranged therein. The armature 14 has an armature shaft 16 which is arranged in two end-side bearings 18, which in turn are fastened in two bearing caps 20. Finally, magnets 22 are arranged around the disk pack 18 on the inner circumference of the pole tube 12. The magnets 22 cooperate with a fixed to the armature shaft 14 plate pack 18 with an armature winding 24.

The armature winding 24 is connected to hooks 26 (FIG. 2) of a commutator 28. Of the

Commutator 28, which is preferably designed as a planar commutator, is acted upon by two brushes or brushes 30 indicated by dashed lines. The brushes 30 are arranged on a brush holder 32 produced as a plastic injection-molded part.

From the figures 2 and 3 it is apparent that the brush holder 32 quiver 34 for two

Brush 30 having a streamlined outer contour comprises. The brush holder 32 has two quivers 34 which are formed parallel to each other and face in the same direction. Laterally to the commutator 28 alignable openings of the quiver 34 two extending in a plane paragraphs 36 are formed for hooks 38 of 40 rolling springs. The paragraphs 36 may, for example, the lower or the commutator 28 facing

Be the edge of the quiver 34. Parallel to the shoulder 36 or approximately at the same height, a web 39 extending transversely through the shaft of the holder 34 is formed at the lower edge. The web 39 extends parallel to the shoulder 36 and the scroll spring 40. It extends only slightly into the shaft of the holder 34 into it. The hook 38 of the Roller spring 40 is felt during assembly between the web 39 and the shoulder 36 and then hooked on the shoulder 36. Both the paragraphs 36 and the webs 39, the assembly of the brush 30 and the scroll spring 40 is facilitated by the remote from the commutator 28 side or opening of the holder 34. By the web 39 also a shaft 42 and the outer contour 44 of the brush 30 is formed on all sides enclosing guide, which has a positive effect on the vibration behavior and thus, inter alia, the life.

The quivers 34 are open at both ends. Between the brush holder 32 and the end face of the commutator 28, a space 41 is formed, through which in the case of

Fuel pump fuel is conveyed. Here, the fuel is swirled. The following describes how these turbulences can be reduced.

As best seen in Figures 4 and 5, the brushes 30 comprise a

Shaft 42 having an outer contour 44 having a cross-sectional area 46. The outer contour 44 is characterized in that it is formed streamlined. The shaft 42 includes a plurality of longitudinal sides 48, 50, 52, 54, which are preferably at right angles to each other. Between each adjacent longitudinal sides 48, 50, 52, 54 are slopes 56, 58, 60, 62 are formed, whose width is greater than the width of at least one of the two adjacent longitudinal sides 48, 50 52, 54. This results in an at least hexagonal, preferably octagonal cross-sectional area 46.

A first longitudinal side 48 and a second longitudinal side 50 run parallel to each other at a first distance. The width of the first longitudinal side 48 is greater than the width of the second longitudinal side 50. The first and the second longitudinal side 48, 50 are arranged symmetrically to a dashed line 64, which extends perpendicularly through the first and second longitudinal side. A third longitudinal side 52 and a fourth longitudinal side 54 extend symmetrically to the plane 64 and preferably parallel to one another and with a second distance. The third and fourth longitudinal side 52, 54 are the same size and shorter than the second longitudinal side 50. Between the first longitudinal side 48 and the third longitudinal side 52, a first slope 56 and between the first longitudinal side 48 and fourth longitudinal side 54, a second slope 58 is formed. The first and second slopes 56, 58 are wider than the third and fourth longitudinal sides 52, 54. The first and second bevels 56, 58 include a first angle 66 arranged symmetrically with respect to the plane 64.

Between the second longitudinal side 50 and the third longitudinal side 52 in each case a third slope 60 and between the second longitudinal side 50 and the fourth longitudinal side 54, a fourth slope 62 is formed. The third and fourth slopes 60, 62 are wider than the third and fourth longitudinal sides 52, 54. The third and fourth slopes 60, 62 enclose a second angle symmetrical to the plane 64. The first angle 66 formed by the first and second bevels 60 is smaller than the second angle formed by the third and fourth slopes.

Furthermore, the brush 30 has a plane formed as a flat contact surface 68 for the commutator 28 end face. As can readily be seen from FIG. 4, a bevel 72 for the scroll spring 40 is formed on the end face 70 of the brush 30 facing away from the contact surface 68. The slope preferably closes with the plane 64

Angle of less than 90 °.

The angle 66, which can also be referred to as the cover angle, is greater by a factor of 1.3 ± 0.2 than the angle 74 of a coal segment 76 of the commutator 28. At least the factor should be greater than 1.

Finally, as can be seen from FIGS. 6a to 6e, the outer contour 44.1, 44.2, 44.3, 44.4, 44.5 can still be round (FIG. 6a), oval (FIG. 6b), diamond-shaped (FIG. 6c), triangular (FIG. 6d) or kidney-shaped (FIG. Figure 6e, indicated only by a ring segment).

Claims

claims

1. Brush (30) for an electrical machine (10), wherein the brush (30) comprises a shank (42) with an outer contour (44) having cross-sectional area (46), characterized in that the outer contour (44, 44.1, 44.2, 44.3, 44.4, 44.5) is streamlined.

2. Brush (30) according to claim 1, characterized in that the shaft (42) has a plurality of longitudinal sides (48, 50, 52, 54) and that at least between two adjacent longitudinal sides (48, 50, 52, 54), preferably At right angles to each other, a bevel (56, 58, 60, 62) is formed, whose width is greater than the width of at least one of the two adjacent longitudinal sides (48, 50, 52, 54).

The brush (30) according to claim 1 or 2, characterized in that at least a first and second longitudinal side (48, 50) extend parallel to each other at a first distance, wherein the width of the first longitudinal side (48) is greater than the width of the second The longitudinal side (50) is such that the first and second longitudinal sides (48, 50) are arranged symmetrically to a plane (64) that runs perpendicularly through the first and second longitudinal sides (48, 50) such that a third and fourth longitudinal side (52 , 54) symmetrically to the plane (64) and preferably parallel and at a second distance from each other and that between the first longitudinal side (48) and the third longitudinal side (52) has a first slope (56) and between the first longitudinal side (48) and the fourth longitudinal side (54) is formed a second slope (58).

4. brush (30) according to claim 3, characterized in that the third and fourth longitudinal side (52, 54) are equal to and shorter than the second longitudinal side (50).

5. Brush (30) according to claim 3 or 4, characterized in that the first and second bevels (56, 58) are wider than the third and fourth longitudinal sides (53, 54).

6. Brush (30) according to any one of claims 3 to 5, characterized in that the first and second bevels (56, 58) include a symmetrically to the plane (64) arranged first angle (66).

7. Brush (30) according to one of claims 3 to 6, characterized in that between the second longitudinal side (50) and the third longitudinal side (52) has a third slope (60) and between the second longitudinal side (50) and the fourth longitudinal side (54) a fourth slope (62) is formed and that the third and fourth slope

(60, 62) are wider than the third and fourth longitudinal sides (53, 54)

8. brush (30) according to claim 7, characterized in that the third and fourth bevel (60, 62) include a symmetrical to the plane (64) arranged second angle.

A brush (30) according to claim 8, characterized in that the first angle (66) formed by the first and second bevels (56, 58) is smaller than the second angle formed by the third and fourth slopes (60, 62) ,

10. Brush (30) according to claim 1, characterized in that the outer contour (44.1, 44.2, 44.3, 44.4, 44.5) is round, oval, diamond-shaped, triangular or kidney-shaped.

11. Brush (30) according to one of claims 1 to 10, characterized in that the

Brush (30) has a designed as a flat contact surface (68) for a flat commutator end face.

12. Brush (30) according to one of claims 1 to 11, characterized in that on the side facing away from a contact surface (68) end face (70) of the brush (30) a

Inclined (72) for a scroll spring (40) is formed.

A brush (30) according to any one of claims 3 to 11, characterized in that the slope (72) subtends an angle of less than 90 ° with the plane (64).

14. brush holder (32) for an electrical machine, characterized in that the brush holder (32) quiver (34) for at least one brush (30) with a streamlined outer contour (44, 44.1, 44.2, 44.3, 44.4, 44.5) after a of the preceding claims.

15. Brush holder (32) according to claim 14, characterized in that the

Brush holder (32) comprises two quivers (34) for a planar commutator, which are formed parallel to each other and in the same direction and at their alignable to a Plankommutator openings two in a plane extending

Hooking means (36) for hooks (38) of roller springs (40), wherein the hooking means (36) are arranged in a plane which is parallel and at a distance from a flat end face of the flat commutator.

16. Brush holder (32) according to claim 14 or 15, characterized in that the

Springs are spring-loaded springs (40) hooked to hooks (38) on hooking means (36) formed laterally on the quivers (34), and in that, in addition to the hooking means (36) across the shafts, the quiver (34) Webs (39) extend, so that the shafts (42) of the brushes (30) are guided on all sides.

17. Brush holder (32) according to any one of claims 14 to 16, characterized in that the quiver (34) are open on both sides.

18. Electrical machine (10), preferably for a fuel pump, with brushes (30) according to one of claims 1 to 13 and / or a brush holder (32) according to one of claims 14 to 17, characterized in that the brushes (30) Commutator segments (76) of a Plankommutators by a factor of greater than 1, preferably a factor of 1.3 overlap.