FR2783369A1 - Electric motor with brush carrier plate, for use as motor vehicle windscreen wiper drive motor - Google Patents

Abstract

The brush-carrier plate (6) also carries a number of auxiliary circuits for interference suppression and overload protection. Each of these circuits has its own connector to the vehicle ground potential, provided by a tongue (41,42) that accepts a slide-on connector. One tongue is between the first an second brush holders, and the other between the second and third brush holder.

Description

The invention relates to the field of electric motors with pads

  brush holders, also called brush holder pads. For example, it may be wiper motor reducers for a motor vehicle.

  Document FR 2 582 872 already discloses a holder plate

  brushes for such motors comprising two tracks, formed of two annular zones, approximately concentric, each zone being connected, on the one hand to an electrical supply circuit and on the other hand to brush holders. Electronic components, such as capacitors are mounted on the brush holder plate. One of the terminals

  of the component is connected to one of the tracks, while the other terminal of it

  this is connected to the other track. The two tracks are linked to a common mass recovery. This requires the above configuration with the tracks

  forming concentric circles on the whole of the holder plate

  broom. However, this arrangement is unfavorable for the installation of a large number of components and a maximum of functions on the brush holder plate, these functions being for example: - interference suppression, - protection against overheating , - power supply (terminal support), - ground insulation, etc. In addition, such a configuration of the tracks generates effects

antenna.

  An object of the present invention is to optimize the place of the tracks

  while minimizing antenna effects.

  This object is achieved according to the invention, thanks to an electric motor comprising a brush holder plate having at least two electrical circuits and a ground connection, characterized in that the two circuits

  have respective mass recoveries dissociated from each other.

  Indeed, the separation of the masses, in accordance with the present invention, makes it possible to close the various circuits on the ground, for example near each component, without having recourse to a track connected to

  a common ground recovery terminal.

  The present invention thus makes it possible to minimize the length of the tracks, and consequently to attenuate the antenna effects, as well as to optimize their arrangement to allow the implementation of numerous functions.

  Other preferred but non-limiting aspects of the carrier plate

  brushes according to the invention are as follows: - advantageously the plate comprises an electrical supply circuit and a suppressor circuit; - advantageously, one of the mass recovery is located on the periphery of the brush holder plate, between a first and a third brush holder, and the other mass recovery is located on the periphery of the brush holder plate, between a second and a third brush holder; advantageously, at least one of the earth connections comprises a tongue coming into contact with a conductive base, by pressing the tongue in an appropriate housing of the conductive base, the or each housing having the shape of a channel having a shape of U in cross section; - advantageously, a capacitor is adjacent to the tongue; - Advantageously, the or each tongue has a curved end capable of being pressed against the walls of said housing; advantageously, at least one of the earth connections, is crimped or screwed onto a conductive base; - Advantageously, the ground recoveries are associated with a respective suppressor circuit of the wafer, the brush holder wafer comprising a third ground recovery for the electrical supply circuit, these three earth recoveries all being dissociated from each other other; advantageously, the wafer comprises an insulating support on which tracks are stapled, by means of fingers inserted into openings of the insulating support and folded over one face of the insulating support,

  opposite to another face on which the tracks are stuck.

  Still other aspects, aims and advantages of the invention will appear

  on reading the detailed description which follows, of a preferred mode of

  realization of the invention. The invention will also be better understood with reference to the drawings in which: - Figure 1 is an exploded perspective representation of a motor vehicle windshield wiper gear motor fitted with an electric motor incorporating a door plate -broom according to the present invention; - Figure 2 is a schematic top view of the brush holder plate of Figure 1; - Figure 3 is a bottom view of the brush holder plate of Figure 2; - Figure 4 is a schematic representation of an example of an electrical circuit produced on the brush holder plate of Figure 2; Figure 5 is a perspective view of the base on which is fixed the brush holder plate of Figure 2; - Figure 6 is an elevational view of the base on which is mounted the brush holder plate of Figure 2; - Figure 7 is a schematic section of a ground connection for the supply circuit, of the brush holder plate of the motor of Figure 1; and - Figure 8 is a schematic section of a ground recovery for the suppressor circuit of the brush holder plate of the motor of FIG. 1. A nonlimiting example of an electric motor 1 which can be equipped with a brush holder plate 6 in accordance with the present invention is

shown in figure 1.

  More specifically, this electric motor 1 is for example a moto-

  windshield wiper reducers for motor vehicles. The motor comprises an inductor 2, an armature 3, a collector 4, a base 5 and a plate

  brush holder 6. The inductor 2, the armature 3, the collector 4 and the holder plate

  brushes 6 generally have a symmetry of revolution about an axis of symmetry 0-0. The armature 3 is housed in the inductor 2. The collector 4 projects

  on one of the faces of the armature 3 perpendicular to its axis of symmetry 0-0.

  The brush holder plate 6 is inserted parallel to this face, between the armature 3 and the base 5. On the axis of symmetry 0-0 of the assembly consisting of the inductor 2, the armature 3, the manifold 4 and the brush holder plate 6, there is a drive shaft 7, integral with the manifold 4 and the armature 3. This drive shaft 7 transmits the driving force of the electric motor 1

  to a motion reduction mechanism.

  The base 5 is conductive and allows the return to ground of the circuits

  the brush holder plate 6.

  The base 5 comprises a first part 50 intended to receive the brush holder plate 6 and a second part 52 intended to receive

  transmission and reduction parts of the gearmotor movement 1.

  In particular, these parts include a drive shaft 53

  perpendicular to the drive shaft 7.

  The second part 52 is closed by a closure plate 54 perpendicular to the drive shaft 53. The first part 50 will be

  described in more detail later.

  An example of a brush holder plate 6, in accordance with the present invention, forming part of the electric motor 1 shown in the

  Figure 1 is shown in more detail in Figures 2 and 3.

  The plate 6 comprises an insulating support 22 having the overall shape of a disc with a central orifice 8 intended for the passage of the collector 4. The insulating support 22 of the brush holder plate 6 is for example

  synthetic resin known as "bakelite" (Trademark).

  This support 22 comprises a first 13 and a second 15 main faces. The first face 13 is shown seen from above in the figure

  2. The second face 15 is shown seen from above in FIG. 3.

  The various electrical and electronic components of the electrical circuits of the brush holder plate 6 are arranged on the first face 13. Conductive tracks 19, 20, 21 ensuring the electrical connection of these various components are arranged on the second face 15. These

  tracks are for example cut from a thin brass plate.

  On the first face 13 are mounted capacitors 14 and

  inductors 16, to constitute interference suppression circuits.

  A terminal support 9, or connector, is placed on the periphery of the

  insulating support 22. A first 10, a second 11 and a third 12 holder

  brushes are arranged radially on the first face 13 and fixed around the central orifice 8, so as to allow contact of the respective brushes of the brush holders 10, 11, 12 on the collector 4. The first 10 and second 11 holders brushes are arranged on either side of an imaginary line connecting the orifice 8 to the terminal support 9. The third brush holder is

  generally diametrically opposite the first brush holder 10.

  The insulating support 22 is pierced with openings 26. These openings 26 are used for the passage of screws 36 ensuring the fixing of this insulating support 22 on the base 5, for the passage of the legs of the components of the first face 13 towards the second face 15 and when passing from one face to the other, fingers 25 folded over the brush holders 10, 11, 12, to staple the tracks 19, 20, 21 and the brush holders 10, 11, 12, on the insulating support 22. The fingers 25 of the tracks 19, 20, 21 are thus folded over the first face 13 of the insulating support 22, opposite that 15 on which the tracks 19, 20, 21 are pressed. These tracks 19, 20, 21 include tabs 18 intended to form

  ground repeats 41, 42 for the interference suppression circuits (FIG. 3).

  A first ground connection 41, for one of the interference suppression circuits, is located at the periphery of the brush holder plate 6, between the first 10 and the third 12 brush holder. A second ground connection 42, for another of the interference suppression circuits, is located on the periphery of the brush holder plate 6, between the second 12 and the third

brush holder 13.

  The electric circuit thus produced can schematically be represented as in FIG. 4. This circuit comprises two capacitors 14, two inductors 16 and an electric motor 1, it is a 2L 2C circuit. One of the conductive tracks 19, 20, 21 makes it possible to connect the first 1 1 and the second 12 brush holder, each to a separate terminal 29 or 30 of the terminal support 9, with interposition between each brush 10 or 11

  and each terminal, respectively 29 or 30, of an inductor 16 in series.

  One 29 of these terminals 29, 30 is for example that which corresponds to the operation of the gear motor 1 at low speed (PV). The other 30 of these terminals 29, 30 is for example the one which corresponds to the operation of the high-speed gearmotor I (GV) Upstream, by reference to the direction of current flow, of each of these inductors 16, the tracks 19, 20, 21 make it possible to connect the capacitors 14 each connected respectively to the first 41 and to the second 42 ground connection of the interference suppression circuits, different from a third ground connection 43 provided for the electrical supply circuit. These tracks 19, 20, 21 also make it possible to connect the third brush holder 12 to the third mass recovery 43, the first 41, second 42 and third 43 mass recovery being

  all dissociated from each other.

  An example of a conductive base 5 is shown in FIGS. 5 and 6. The first part 50 has a central cavity 37 in which is housed the free end of the drive shaft 7, a threaded rod 32 and a threaded cavity 33 intended for fixing the brush holder plate 6 on this base 5, as well as two housings 35 intended to receive the tongues 18 serving to make a contact at the earth connections 41, 42 of the interference suppression circuits. This first part 50 also includes notched structures 36 opposite the position occupied by the support to

  terminals 9, when the brush holder plate 6 is fixed on the base 5.

  Examples of these earth recovery structures 41, 42, 43 for the electrical supply circuit and for those of interference suppression, are

  schematically shown in Figures 7 and 8.

  The example of mass recovery for electrical supply 43, shown in FIG. 7, is produced by screwing a screw 36 into a threaded cavity 33 of the base 5. The head 38 of the screw 36 makes it possible to tighten a conductive track 21 on the base 5. To make this ground contact more reliable with respect to vibration stresses and thermal shocks, an opening 39 is made in the insulating support 22 (see also FIG. 2). Head 38 is like this

  in contact with the corresponding conductive track 21.

  As shown in FIG. 8, the first 41 and second 42 ground connections include tongues 18 which come into contact with the conductive base 5 and which are pressed into the housings 35. These housings 35 are made up of two ribs 45, 46 defining a channel which has a U shape in a cross section to its axis

longitudinal (see also figure 6).

  The tongue 18 then advantageously has a curved end

  able to be pressed against the walls of said housings 35.

  Each capacitor 14 is located near a tongue 18

separate (see also Figure 2).

  The brush holder plate 6 according to the present invention can

present many variations.

  So, for example, the first 41 and second 42 covers of

  ground, can be crimped onto the conductive base 5.

  According to yet another variant, the first 41 and second 42

  earth connections can be screwed onto the conductive base 5.

  According to yet another variant, the tracks 19, 20, 21, instead of being in the form of a cut brass sheet, can be produced directly on the insulating support 22 thanks to the techniques

  known to make printed circuits.

Claims (10)

  1. Electric motor comprising a brush holder plate (6) having at least two electrical circuits and a ground recovery, characterized in that the two circuits have respective ground recovery (41, 42) dissociated from each other.   2. Electric motor according to claim 1, characterized in that the plate (6) comprises an electrical supply circuit and a circuit suppression.   3. Electric motor according to claim 1 or 2, characterized in that one of the earth connections (41) is located on the periphery of the   brush holder plate (6), between a first (10) and a third (12) holder   brushes, and that the other ground connection (42) is located on the periphery of the   brush holder plate (6), between a second (4) and a third (12) holder broom.   4. Electric motor according to one of claims 1 to 3, characterized   by the fact that at least one of the earth connections comprises a tongue (18) coming into contact with a conductive base (5), by pressing the tongue (18) in a suitable housing (35) of the conductive base (5 ), the or each housing (35) having the shape of a channel having a shape of U in cross section.   5. Electric motor according to claim 4, characterized in that   that a capacitor (14) is adjacent to the tongue (18).   6. Electric motor according to one of claims 4 or 5,   characterized in that the or each tongue (18) has one end   curved capable of being pressed against walls of said housing (35).   7. Electric motor according to one of claims 1 to 6, characterized   by the fact that at least one of the earth connections is set on a base conductor (5).   8. Electric motor according to one of claims 1 to 7, characterized   by the fact that at least one of the mass recoveries is screwed onto a base conductor (5).   9. Electric motor according to one of claims 1 to 8, characterized   by the fact that each ground recovery is associated with a respective interference suppression circuit of the wafer, the brush holder wafer (6), comprising a third ground recovery (43) for the electrical supply circuit (43), these three mass recoveries (41, 42, 43) being   all dissociated from each other.   10. Brush holder plate for electric motor according to one of the   previous claims, characterized in that it comprises a   insulating support (22) on which tracks are stapled (19, 20, 21), by means of fingers (25) introduced into openings (26) of the insulating support (22) and folded over one face of the insulating support (22) , opposite to another face on   which are plated tracks (19, 20, 21).