FR3045223A1 - ROTATING MACHINE FOR MOTOR VEHICLE AND ASSOCIATED ELECTRICAL CONTACT BROOM - Google Patents

Abstract

The present invention relates to a contact broom (1) for a rotating machine with a collector (7) of a motor vehicle comprising: a first part (21), called a wear part, comprising an active face (3) intended to be at least partially in contact with the collector (7) for feeding the winding of a rotor, in which the section of the first part (21) of the brush (1), in a plane parallel to the active face (3), so-called effective section, decreases according to the height of life (H) of the blade (1) away from the active face (3).

Description

ROTATING MACHINE FOR MOTOR VEHICLE AND BROOM

ELECTRICAL CONTACT

The present invention relates to the field of rotating machinery, in particular for motor vehicles and in particular commutating rotating machines such as starters, alternators and alternator-starters.

It is known in the state of the art to use one or more electric contact brushes associated with the stator and intended to come into contact with a collector associated with the rotor for supplying the rotor winding via the collector tracks. To allow contact between the electrical contact mop and the collector, springs are used to constrain the brushes against the collector.

Moreover, during the operation of the rotating machine with collector, the friction between the electrical contact mop and the collector causes wear of the contact broom whose life height, that is to say the dimension of the broom perpendicular to the active face which is in contact with the collector decreases so that the force exerted by the spring on the electric contact mop to hold it against the collector decreases.

This reduction in the force and therefore the pressure between the electric contact broom and the collector causes losses in the rotating machine.

It is therefore necessary to find a solution to obtain a substantially constant pressure between the electric contact broom and the collector. To this end, the subject of the present invention is a rotating machine broom with a collector of a motor vehicle comprising: a first part, called a wear part, comprising an active face intended to be at least partially in contact with the collector for feeding the winding of a rotor, in which the section of the first part of the blade, in a plane parallel to the active face, called the effective section, decreases, at least in steps, according to the height of life of the blade in s' away from the active face.

An active surface or contact surface is thus obtained which decreases during at least part of the life of the blade. The reduction, at least in steps, of the effective section on the wear portion of the blade reduces the surface of the active face over time during the wear of the blade so that the reduction of the active surface allows to compensate for the decrease of the force exerted by an elastic element such as a spring and thus to obtain a substantially constant pressure over time between the blade and the commutator during the wear of the blade.

The present invention may also be defined by a contact broom comprising: - an active face comprising a contact surface intended to come into contact with the collector, - a front face comprising a height of life and widths measured perpendicular to the height of life and in that the front face comprises a width smaller than a width of the front face measured closer to the active face, or by a contact broom of rotating machines collector of a motor vehicle comprising: - a first part, said wear portion, comprising an active face intended to be at least partially in contact with the collector for supplying the winding of a rotor, wherein the profile of the brush in a plane substantially normal to the active face, said wear profile, has a convergent shape away from the active face.

According to another aspect of the present invention, the blade also comprises a second portion, said holding portion, opposite to the active face of the first portion and configured to allow the maintenance of the blade.

The holding part makes it possible to keep a fixed section at the rear of the blade and thus allow cooperation with a standard brush holder.

According to an additional aspect of the present invention, the decrease is continuous over the life of the blade.

Continuous reduction of the cross-section over the life of the blade makes it possible to compensate for the decrease in the strength of the elastic element during the entire life of the blade.

According to an additional aspect of the present invention, the decrease is linear over the life of the blade.

A linear decrease makes it possible to better compensate for the linear decrease in the force applied by the elastic element.

According to a further aspect of the present invention, the ratio between the effective section of the blade at the end of the first portion opposite the active face and the effective section of the blade at the active face is equal to the ratio of the the force of the elastic element at the beginning of the blade on the force of the spring on the blade in the state of wear of the blade at the end of the first part so as to reduce a variation of the pressure of the blade on the collector during its lifetime.

According to another aspect of the present invention, the blade comprises a front face adjacent to the active face at a leading edge and a rear face adjacent to the active face at a trailing edge, the front face. and the rear face being connected by a first and a second lateral face, in which at least two of the following faces: the front face, the rear face, the first lateral face and the second lateral face extend perpendicularly. to the active face.

According to an additional aspect of the present invention, the at least two faces extending perpendicularly to the active face comprise the front face and the rear face. The use of a wiper comprising a front face and a rear face extending perpendicularly to the active face makes it possible to maintain the width, between the leading edge and the trailing edge, of the active face constant for the duration of life of the broom and thus ensure that the broom is in contact simultaneously with several tracks of the collector throughout its life.

The present invention also relates to a rotating machine with a collector of a motor vehicle comprising at least one blade according to any one of the preceding claims. Other features and advantages of the invention will appear in the description which will now be made, with reference to the accompanying drawings which show, by way of indication but not limitation, possible embodiments.

In these drawings: - Figure 1 shows schematically and partially a contact broom, a brush holder and a commutator of a rotating machine; - Figure 2a shows schematically and partially a contact broom and a collector of a rotating machine according to a first configuration; - Figure 2b shows schematically and partially a contact broom and a commutator of a rotating machine according to a second configuration; - Figure 3 shows schematically and partially a contact broom of a rotating machine according to a first embodiment; - Figure 4 shows schematically and partially a profile view along a first side face of the blade of Figure 3; - Figure 5 shows schematically and partially a profile view according to another embodiment; - Figure 6 shows schematically and partially a contact broom of a rotary machine according to a second embodiment; - Figure 7 shows schematically and partially a profile view according to another embodiment.

In these figures, the same reference numerals designate elements having an identical function.

The following achievements are examples. Although the description refers to one or more embodiments, this does not necessarily mean that each reference relates to the same embodiment, or that the features apply only to a single embodiment. Simple features of different embodiments may also be combined to provide other embodiments.

Figure 1 shows a diagram of an assembly comprising a contact broom 1 and a manifold 7 of a rotating machine, including a starter, an alternator or an alternator-starter, of a motor vehicle. The contact broom 1 is held by a brush holder 2 which partially surrounds the contact broom 1. The brush holder 2 also comprises an elastic means 4, for example a metal spring, to force the contact broom 1 against the collector 7 to allow powering the winding of a rotor of the rotating machine. The contact between the blade 1 and the manifold 7 is formed at a so-called active face 3 of the blade 1. Thus, during the rotation of the manifold 7 whose direction of rotation is represented by the arrow 12, the active face 3 of the blade 1 comes successively in contact with the different tracks 5 of the collector 7. The brush 1 is in each moment in contact with at least two tracks 5 of the collector 7.

The active face 3 comprises a first edge called leading edge 9 which is the edge by which the active face 3 comes into contact with a track 5 during the rotation of the collector 7 and a second edge said trailing edge 11 which is the edge by which the active face 3 loses contact with a track 5 of the collector 7 during the rotation of the collector 7.

In the case of a cylindrical collector 7 as shown in FIGS. 1 and 2a, the active face 3 is not flat but curved (or curves when the brush 1 is wearing) because of the cylindrical shape of the In the following description, however, it will be considered that the active face 5 forms a plane comprising the leading edge 9 and the trailing edge 11.

It should also be noted that the present invention also extends to the flat collectors 7 as shown in FIG. 2b for which the brush 1 comes into contact with a flat surface of the collector 7 comprising the tracks 5. In this case, the active surface 3 remains flat when the broom 1 is worn.

The direction of rotation of the manifold 7 is indicated by the arrows 12 in FIGS. 2a and 2b.

Figure 3 shows a perspective view of a contact broom 1 according to a first embodiment of the present invention. The blade 1 has a parallelepipedal general shape with a front face 13 adjacent to the active face 3 at the leading edge 9 and a rear face 15 adjacent to the active face 3 at the trailing edge IL. The blade 1 also comprises a first 17 and a second 19 side faces adjacent to the active face 3 and which connect the front face 13 and the rear face 15. The rear face 15, the first 17 and the second 19 side faces extend perpendicularly to the active face 3.

The contact broom 1 can be divided into two parts, a first part called wear portion 21 comprising the active face 3. The wear part 21 being intended to become the active face 3 during the life of the blade 1 Indeed, the friction of the blade 1 on the manifold 7 causes the wear of the blade 1 whose particles are deposited on the manifold 7 to form a patina on the surface of the tracks 5 of the manifold 7. Thus, the height of the blade in a direction perpendicular to the active face 3 called height of life H tends to decrease over time when using the rotating machine.

The contact broom 1 also comprises a second part called holding portion 23 opposite to the active face 3 and intended to hold the blade 1 by a brush holder 2. The brush holders 2 are generally standard, the dimensions (length L and width 1) of the holding portion 23 are imposed by the standard. The holding portion 23 comprises an electric wire 24, called a "shunt" in English, intended to provide an electric current to the blade 1 and may also include one or more recesses 26 formed on the face opposite the active face 3 in which come housing one end of the elastic elements 4, for example metal springs, which ensure the contact between the blade 1 and the collector 7.

The separation between the wear part 21 and the holding part 23 is indicated by a dashed line in FIG. 3. This separation is generally at the level of the limit of the electric wire 24.

The section of the wear portion 21 of the blade 1 is defined in a plane parallel to the active face 3, ie in a plane normal to the height of life H, as being the effective section and the contact broom. 1 is configured so that its effective cross section decreases away from the active face 3, at the wear portion 21. Thus, the surface of the active face 3 decreases during the life of the brush which allows to obtain a substantially constant pressure between the contact broom 3 and the collector 7 during the life of the blade 1. Indeed, the resilient means 4, such as the metal spring, applies a force which tends to decrease during the wear of the blade 1 due to the decrease in the height of life H. The reduction of the effective section during the wear of the blade 1 can counteract or compensate for the decrease in the force applied by the elastic element 4 and to obtain a substantially constant pressure between the broom 1 and the collector 7.

This reduction of the effective section of the blade 1 according to the height of life H away from the active face 3 is for example obtained by a front face 13 forming an acute angle with the active face 3 as shown in Figure 3. L the acute angle is, for example, determined so that the ratio of the effective section of the blade at the end of the first portion opposite the active face to the effective section of the blade at the active face is depending on the stiffness of the elastic member with respect to the state of wear of the blade so as to reduce the variation of the pressure of the blade on the collector.

This ratio is advantageously equal to the ratio of the force of the elastic element at the beginning on the blade to the force of the spring on the blade in the state of wear of the blade at the end of the first part 21. This allows constant pressure at the active side of the broom on the collector.

For example, if the spring pressure on a new broom is 26N, then when the broom is worn up to the end of the first part (eg after a stroke of 15mm) the spring pressure on the broom is now only 21N, so the spring supports only 80% of the 26N at the start, or the 20% lower broom presses at this end level than at the beginning of life, then the ratio of the cross-section of the broom at the end of the first part opposite the active face and the effective section of the broom at the active side is 80% between the effective section and the section of the broom at the end of life. Such ratio ensures a sufficient contact area between the brush 1 and the manifold 7 to allow the smooth operation of the rotating machine regardless of the wear of the blade 1.

FIG. 4 shows the profile of the contact broom 1 of FIG. 3 along a plane normal to the leading and trailing edges 9 and corresponding to a view in the direction of the second lateral face 19. In the case of FIG. , the section of the blade 1 is constant between the first 17 and second 19 side face, however, the present invention is not limited to a constant section between the first 17 and second 19 side face. The inclination of the front face 15 with respect to the active face 3 makes it possible to obtain a reduction of the section normal to the height of life H.

An acute angle can also be provided between the active face 3 and the rear face 15, the front face 13 then being substantially normal to the active face 3.

According to another embodiment shown in FIG. 5, the front face 13 and the rear face 15 have an acute angle with respect to the active face 3.

Moreover, the reduction of the effective section during wear can also be obtained by a blade 1 comprising an acute angle between the active face 3 and the first lateral face 17 or between the active face 3 and the second lateral face 19 as shown in FIG. 6. Alternatively, the first 17 and the second 19 lateral faces have an acute angle with respect to the active face 3. It is also possible to combine the various preceding embodiments with several faces presenting an acute angle by relative to the active face, for example the front face 13 and the first side face 17.

Furthermore, the reduction of the effective section of the blade 1 during its wear can also be carried out non-linearly or non-continuously. Indeed, instead of providing a face having an acute angle with respect to the active face 3, the face may have a convex or concave surface or any other shape having a divergent shape towards the active face 3 such as a staircase profile as shown in FIG. 7. The reduction of the cross section can also be obtained by one or more holes formed in the blade 1 and having a shape that converges towards the active face 3 of the contact broom 1.

Thus, the use of a contact broom 1 having an effective section which decreases away from the active face 3 reduces the surface of the active face 3, that is to say the surface in contact with the manifold 7 and thus obtain a pressure of the brush 1 on the collector 7 substantially constant over time during the life of the blade 1 despite the decrease in the force exerted by the elastic element 4, such as a metal spring, on the broom 1.

Claims (8)

1. contact broom (1) of a rotating machine with a collector (7) of a motor vehicle comprising: a first part (21), called a wear part, comprising an active face (3) intended to be at least partially in contact with the collector (7) for feeding the winding of a rotor, the first part comprising a height of life (H) which is a dimension perpendicular to the active face which is in contact with the collector, characterized in that a section of the first part (21) of the blade (1), in a plane parallel to the active face (3), said effective section, decreases, for example in steps, according to the height of life (H) of the blade (1) away from the active face (3). 2. Broom (1) according to claim 1 wherein the blade (1) also comprises: - a second portion (23), said holding portion, opposite to the active face (3) of the first portion (21) and configured to allow the maintenance of the broom (3). 3. Brush (1) according to claim 1 or 2 wherein the decrease is continuous over the height of life (H) of the blade (1). 4. Brush (1) according to claim 3 wherein the decrease is linear over the height of life (H) of the blade (1). 5. Broom (1) according to one of the preceding claims wherein the ratio between the effective section of the blade (1) at the end of the first portion (21) opposite the active face (3) and the section effective of the brush (1) at the active face (3) is a function of the ratio of the force of the elastic element at the beginning on the brush on the spring force on the brush in the state of wear of the brush at level of the end of the first portion (21) so as to reduce a variation of the pressure of the brush on the collector during its lifetime. 6. Broom (1) according to one of the preceding claims wherein the blade (1) comprises a front face (13) adjacent to the active face (3) at a leading edge (9) and a face rear (15) adjacent to the active face (3) at a trailing edge (11), the front face (13) and the rear face (15) being connected by a first (17) and a second (19). ) lateral faces, in which at least two of the following faces: - the front face (13), - the rear face (15), - the first lateral face (17) and - the second lateral face (19) extend perpendicular to the active face (3). 7. Broom according to claim 6 wherein the at least two faces (13, 15, 17, 19) extending perpendicularly to the active face (3) comprise the front face (13) and the rear face (15). 8. Turning machine collector of a motor vehicle comprising at least one blade (1) according to any one of the preceding claims.