FR2739988A1 - Brush holder assembly for DC motor used in motor vehicle heating, ventilating and air conditioning system - Google Patents

Abstract

The brush holder assembly includes two brush holder assemblies (9a-9c) which are fixed in place on a conducting body (2), on which a brush holder plate (7) is also mounted. Assembly of the brushes on each side is carried out by two electrical connection pieces (8,20). The connection piece (20) includes a part (21) for fixing on the brush holder plate (7), a part (12) for electric connection with the exterior and the extension piece (13) which extends from the fixing part to an adjacent region at the periphery of the brush holder plate (7). The extension piece (13) which when assembled comes into contact with the body area (14) and so earths the brush on one side.

Description

 The present invention relates generally to direct current machines, and in particular to a direct current motor with brushes usable for example for a fan or blower of a heating and / or air conditioning equipment of the passenger compartment of a motor vehicle.

 It is still common to use DC brushed motors for this kind of application. However, the most recent international standards for electromagnetic compatibility (EMC) lead designers to adapt their specifications to comply with them.

 Motors of this type have long been equipped with a device limiting the electromagnetic disturbances generated by the operation of the motor and transmitted to the environment, by radiation or by conduction.

 This device generally consists of a combination of two inductors and a capacitor, the values and wiring of which are chosen appropriately.

Conventionally, the inductors are connected in series on the brush supply lines, while the capacitor is connected in parallel on the brush / collector circuit.

 However, recent standards in terms of electromagnetic radiation have led to the design of an improvement, consisting in electrically connecting the power supply of the brush on the negative side to the metal frame of the motor (grounded), in order to ensure an electromagnetic shielding effect. by the fact that the motor casing is at the same electrical potential as the negative pole of the motor.

 This grounding is carried out in a known manner by various arrangements of the brush holder plate, but whatever the solution chosen, it always requires an additional component and / or an additional assembly operation.

Documents FR-A-2 544 927, FR-A-2 672 445 and
DE-U-91 05 301 illustrate in particular this state of the art.

 In addition, when the brush holder plate is fitted with shock absorbers, it is difficult to ensure grounding without compromising the effectiveness of the desired vibration decoupling with the shock absorbers.

 The present invention aims to overcome the drawbacks of being technical, and to provide a grounding of the negative brush of a DC motor which does not require any additional component and / or assembly operation , and if necessary which does not compromise the vibration decoupling provided by shock absorbers.

 To this end, the invention provides a brush holder assembly for a DC machine, in particular for a motor for the ventilation, heating or air conditioning apparatus of a motor vehicle cabin, of the type comprising a brush holder plate intended for be mounted by crimping on a conductive carcass of the machine, two sets of brushes mounted on the plate, two pieces of electrical connection of the brushes with the outside, also mounted on the plate, and connecting means for electrically connecting one brushes to said carcass, characterized in that said connecting means are constituted by an extension of one of said connection pieces, capable of coming into contact with a crimping tab coming from the carcass during the crimping operation .

Preferred, but not limiting, aspects of the brush holder assembly according to the invention are as follows:
- Said connection piece comprises a fixing part on the plate, an electric connection part with the outside and a tongue extending from the fixing part in the direction of an adjacent region of the periphery of the plate.

 - Said connecting piece is made by cutting and bending metal.

 - The tongue comprises a connecting part and a terminal pad.

 - Said tab ends at an elastically deformable part of the plate.

 - Said elastically deformable part is constituted either by a damper attached to the plate, or by a rib formed on the plate.

 The invention also provides a direct current machine, in particular a motor for the ventilation, heating or air conditioning apparatus of the passenger compartment of a motor vehicle, characterized in that it comprises an electrically conductive carcass and a brush holder assembly such as defined above, retained by crimping in the carcass.

Other aspects, aims and advantages of the present invention will appear better on reading the following detailed description of preferred embodiments thereof, given by way of non-limiting example and made with reference to the accompanying drawings, in which
FIG. 1 is an end view of a brush-bearing plate with dampers, according to a first embodiment of the invention,
FIG. 2 is a sectional view along the line II-II of FIG. 1,
FIG. 3 is an end view of a brush-holding plate without dampers, according to a second embodiment of the invention,
FIG. 4 is a sectional view along the line IV-IV of FIG. 3,
FIG. 5 is a view partially in elevation and partially in section, along the line VV in FIG. 6, of the plate of FIG. 3 mounted in a part of the carcass of the associated motor, before crimping,
FIG. 6 is a sectional view along line VI-VI of FIG. 5,
FIG. 7 is a view similar to FIG. 5, but on the line VII-VII of FIG. 8, after crimping,
Figure 8 is a sectional view along the line
VIII-VIII of figure 7,
FIG. 9 is a perspective view on an enlarged scale of a region of the carcass part receiving the plate according to the invention,
FIG. 10 is a perspective view of a conductive part of the plate according to the invention, and
Figures 11 and 12 are detailed sectional views, respectively before and after crimping.

 Referring firstly to Figures 1 and 2, there is shown a brush holder assembly, generally designated by the reference 1, which is intended to be mounted in a part of the motor casing, for example a metal bearing support 2 shown in Figures 5 to 9. This assembly comprises a support plate 7 carrying the various elements as will be seen in detail below.

 In the embodiment of FIGS. 1 and 2, the plate 7 comprises two damping parts 3, 3 ′, made of elastomeric material, held on the plate by embedding and by means of which the plate is mounted in the support 2, in order to decouple vibrations. These parts have a rounded outer face in which a notch is formed, to ensure mounting in the support 2 by complementarity of shapes.

The plate 7 carries the various usual elements of a brush holder assembly, namely
- two lugs or pins 8, 12, in this case male lugs, for electrical connection with the motor supply voltage either by soldering or using additional connectors;
- two coals 9a mounted in guides 9b and urged by springs 9c;
- two inductors 10, 10 'and a capacitor 11.

 The variant embodiment of FIGS. 3 and 4 differs from the embodiment of FIGS. 1 and 2 essentially in that the damping parts 3, 3 'are omitted and replaced by rigid parts 6, 6' added or made of a integral with the plastic (thermoplastic or thermosetting) of the plate 7.

 The description which follows of the general principle of the present invention applies equally to the embodiment of FIGS. 1 and 2 and to its variant of FIGS. 3 and 4.

 Now with reference to FIGS. 5 to 12, it is observed in particular in FIG. 10 that the negative terminal 12 for supplying the negative brush is part of a bent metal part 20 comprising, in addition to the terminal 12 itself, a barrel 21 from which the terminal extends substantially radially, and intended to be engaged in an orifice formed in the plate 7 to be fixed therein, and a tongue 13 extending in a generally transverse plane and comprising a slightly raised connecting branch 13a , and a terminal pad 13b.

 This tongue, when the part 20 is put in place, is shaped so that the terminal stud 13b is positioned substantially against one face of the damping part 3 or of the adjacent extension 6, at the place where, as we go see in detail below, a crimping lug from the bearing support 2 is folded by permanent deformation against said face of the part 3 or of the extension 6.

 FIG. 9 illustrates in detail the shape of a foot 4 of the bearing support 2, having a curved profile and comprising a central rib 25 so as to ensure cooperation of shapes with the outer edge of the respective part 3 or 6. The foot 4 comprises, along its two lateral edges, two crimping lugs 14, 14 intended to be folded about 90 inwards, after the assembly 1 has been placed in the support 2, to ensure their mutual fixing.

 Figures 11 and 12 show in detail the realization of the grounding of the negative terminal (part 20). In FIG. 11, the lug 14 has not yet been folded down, and the terminal stud 13b of the part 20 rests against the upper surface of the part 6. In FIG. 12, the crimping has been carried out, and the lug 14 compresses the stud 13b between it and the upper surface of the part 6, thereby ensuring, by contacting said stud with said tab 14, grounding. FIG. 7 also illustrates the tab 14 applied against the stud 13b.

 It will be observed that the tab 14 of the opposite lateral edge of the foot 4 is applied directly against the part 6.

 In addition, FIGS. 11 and 12 also illustrate an alternative embodiment of the invention, according to which the part 6 is provided, at the place where the stud 13b is positioned, with a thin deformable rib 15, intended to avoid any break in contact between the stud and the lug 14 under the effect for example of a slight elastic return of the lug 14 after crimping.

 More specifically, the rib 15, by the play of its elastic return after compression, permanently urges the stud 13b against the tab 14, to ensure the grounding contact reliably.

 It will be observed here that, when the assembly 1 comprises damping parts 3, 3 ′ having a high degree of elasticity, the rib 15 is superfluous insofar as the part 3 itself, after the compression resulting from the crimping , reminds the stud 13b in the direction of the crimping lug 14.

 This produces, in an extremely simple and economical manner, the grounding of the negative side of the brush assembly. More specifically, no additional part is required, insofar as the tongue 13 comes from the part 20 forming a terminal or connection terminal, while the fitting, in the usual way, of the part 20, followed by the crimping, also in the usual way, of the assembly 1 in the support 2, is sufficient to ensure grounding.

 Of course, the present invention is not limited to the embodiments described and shown, but those skilled in the art will be able to make any variant or modification in accordance with his spirit.

Claims (8)

 1. Brush holder assembly for a DC machine, in particular for a motor for the ventilation, heating or air conditioning apparatus of a motor vehicle cabin, of the type comprising a brush holder plate (7) intended to be mounted by crimping on a conductive carcass (2) of the machine, two sets of brushes (9a-9c) mounted on the plate, two pieces (8, 20) of electrical connection of the brushes with the outside, also mounted on the plate, and connecting means for electrically connecting one of the brushes to said carcass, characterized in that said connecting means are constituted by an extension (13) of one (20) of said connection pieces, capable of coming into contact with 'a crimping tab (14) from the carcass (2) during the crimping operation.  2. brush holder assembly according to claim 1, characterized in that said connection piece (20) comprises a part (21) for fixing on the plate, a part (12) for electrical connection with the outside and a tongue ( 13) extending from the fixing part towards an adjacent region (3, 6) of the periphery of the plate.  3. Assembly according to claim 2, characterized in that said connection piece (20) is produced by cutting and bending of metal.  4. Assembly according to one of claims 2 and 3, characterized in that in that the tongue (13) comprises a connecting part (13a) and a terminal stud (13b).  5. Assembly according to one of claims 2 to 4, characterized in that said tongue ends at an elastically deformable part (15; 3) of the plate.  6. An assembly according to claim 5, characterized in that said elastically deformable part is constituted by a damper (3) attached to the plate (7).  7. An assembly according to claim 5, characterized in that said elastically deformable part is constituted by a rib (15) formed on the plate (6, 7).  8. DC machine, in particular motor of ventilation, heating or air conditioning unit of motor vehicle cabin, characterized in that it comprises an electrically conductive carcass (2) and a brush holder assembly (1) according to one of the preceding claims retained by crimping in the carcass.