FR3118342A1 - ELECTRIC MOTOR WITH SIMPLIFIED CONTROL AND MOTOR VEHICLE PARKING BRAKE IMPLEMENTING SUCH A MOTOR - Google Patents

Abstract

Electric motor comprising a stator (2 and a rotor (4), said rotor (4) surrounding the stator (2), the rotor (4) being configured to rotate around a longitudinal axis X, pairs of coils (12) being carried by the rotor (4) and the m pairs of poles being carried by the stator (2), electrical connection means intended to supply the motor with direct current, rotary commutator collector means of the n pairs of coils (12) distributed between the rotor and the stator.The means comprise two concentric circular electric conductive tracks (26, 28) of axis X carried by the bottom of the rotor (4), two first brushes (30, 32) electrically and mechanically connected to the two electrical tracks (26 28) and switching tracks (14) carried by the stator (2) and electrically insulated from each other, each switching track (14) being electrically connected to a coil (12), said first brushes ( 30, 32) being arranged diametrically opposite, so as to come into contact simultaneously with two switching tracks (14) diametrically opposed and sequentially with said switching tracks. Figure for abstract: 1

Description

ELECTRIC MOTOR WITH SIMPLIFIED CONTROL AND MOTOR VEHICLE PARKING BRAKE IMPLEMENTING SUCH A MOTOR

TECHNICAL AREA AND PRIOR ART

The present invention relates to an electric motor with simplified control and to a motor vehicle parking brake implementing such a motor.

In the automotive industry, the function of electromechanical parking braking is to immobilize the vehicle when stationary in order to prevent it from moving unexpectedly. It also meets the legal provision requiring a second braking system independent of the service braking system, usually hydraulic, in the vehicle and fulfills other comfort and safety functions, in particular through its ability to self-diagnose.

It is known from document FR3016015 to install within a drum brake, a mechanical actuator in addition to the hydraulic actuator or wheel cylinder initially planned.

The mechanical actuator provides parking and emergency braking by spreading the associated ends of the segments to ensure rapid and powerful locking of the vehicle wheels according to a so-called "duo-servo" operating mode, in particular when the wheel cylinder is inactive. . This actuator is driven by an electric motor.

The implementation of a motor, possibly associated with a reduction module, requires the availability of a large amount of space.

However, the space available at the level of the wheels is relatively small. In addition, this space is very variable in size and shape depending on the vehicle model. It is then desirable to have a reduced size geared motor facilitating its integration on different vehicle models.

BLDC (Brushless Direct Current) outrunner or revolving cage motors are brushless motors with an external rotor. The stator carrying the coils is located inside the rotor, and the magnets are arranged on the rotor and therefore over a large diameter. This arrangement of the magnets creates an important lever arm. These motors can then develop a high torque, which can make it possible not to have to resort to a reduction module or to a reduced reduction module.

A BDLC motor has an electronic commutator that sequentially energizes the stator coils, thereby generating a rotating electric field that “drives” the rotating rotor. To ensure efficient operation, care must be taken to ensure that the coils are energized at exactly the right time. For this Hall effect type sensors are used to know the position of the rotor.

It is desired to simplify the control of electric motors, in particular for reliability purposes.

It is therefore an object of the present invention to provide an electric motor with simplified control and offering reduced bulk.

The object stated above is achieved by an electric motor comprising a stator or a rotor carrying at least one pair of coils, the coils of each pair being diametrically opposed and a rotor or a stator respectively comprising at least one pair of magnetic poles, a connection to a direct current source, two circular electric conductor tracks carried by the rotor or the stator and comprising a first pair of brushes, each permanently electrically connected to a circular track, and arranged so as to come into contact simultaneously and sequentially with two diametrically opposed coils.

In other words, the rotation of the rotor ensures the power switching of the coils. The rotor forms a mechanical commutator, which by turning allows a sequential supply of the coils. Thus, no position sensors are required to precisely know the position of the rotor, nor a complex electronic system for supplying the coils.

In a preferred embodiment, the coils are carried by the stator and the magnets are carried by the rotor, and very advantageously the rotor surrounds the stator.

In an exemplary embodiment, the electrical connection is carried by the rotor, which is connected to the two circular tracks by a second pair of brushes.

In another exemplary embodiment, the electrical connection is carried by a cover covering at least part of the rotor, and is connected to the two circular tracks by a second pair of brushes, which advantageously makes it possible to use standard electrical connectors in particular in automobile industry.

For example, the output shaft is for example directly carried by the rotor.

As a variant, a reduction device is arranged between the rotor and the output shaft of the motor, integrated in the stator, thus forming a geared motor.

One of the subjects of the present application is an electric motor comprising a stator and a rotor, said rotor surrounding the stator, the rotor being configured to rotate around a longitudinal axis X, n pairs of coils, the coils of each pair being diametrically opposed, n being an integer > 0 and m pairs of magnetic poles, m being an integer >0, poles of opposite polarities being arranged in a diametrically opposite manner, the n pairs of coils being carried by the rotor or the stator and the m pairs of poles being carried by the stator or the rotor respectively, electrical connection means intended to supply the motor with direct current, characterized in that it comprises means for collecting rotary switches of the n pairs of coils distributed between the rotor and the stator, said rotary commutator collector means being connected simultaneously to the coils of a pair and sequentially to the m coils.

In an exemplary embodiment, the rotor comprises a bottom perpendicular to the longitudinal axis X and a side wall and at least a part of the rotary commutator collector means is arranged between the bottom of the rotor and the stator.

According to an additional feature, the n pairs of coils are carried by the stator and the n pairs of poles are carried by the side wall of the rotor, and the rotary commutator collector means of the coils comprise two concentric circular electrical conductive tracks of axis X carried via the bottom of the rotor, at least two first brushes, each being electrically and mechanically connected to the two electrical tracks and switching tracks carried by the stator and electrically insulated from each other, each switching track being electrically connected to a coil, said first brushes being arranged in a diametrically opposed manner and so as to come into contact simultaneously with two diametrically opposed switching tracks and sequentially with said switching tracks.

Advantageously, the first two brushes are arranged substantially on the same circle and the switching tracks include an arcuate portion with which the first brushes are sequentially in contact.

The electric motor may comprise two second brushes in permanent contact with the electric tracks and connecting the electric connection means intended to supply the motor with direct current and the electric tracks.

The second brushes are for example carried by contacts fixed to the stator, the electrical tracks and the first brushes being located inside the rotor.

For example, the motor comprises a cover covering at least in part the rotor on which the second brushes are fixed, the electrical tracks being located outside the rotor, and the electrical connection means intended to supply the motor with direct current are carried by the hood.

According to another additional characteristic, the motor comprises an output shaft and the stator comprises a central passage, said output shaft being fixed to the rotor and passing through the stator through the central passage.

Another object of the present application is a geared motor comprising an electric motor according to the invention, the stator comprising a central passage and a reduction device mounted in the central passage of the stator.

Another object of the present application is a brake for a motor vehicle comprising friction elements intended to come into contact with a part integral in rotation with a wheel in order to brake it, a mechanical actuator for moving the friction elements and a motor electric according to the invention or a geared motor according to the invention, connected to the mechanical actuator to actuate it. The actuator is advantageously configured to be activated to provide parking braking.

The present invention will be better understood on the basis of the following description and the appended drawings in which:

is a perspective view of a stator and a perspective view of the inside of a rotor of an electric motor according to a first embodiment.

is an exploded view of the electric motor of the , the rotor being represented in transparency.

is a detail view of the stator of the .

is an exploded view of the electric motor according to a second embodiment.

is the exploded view of the on which the cover and the rotor are represented in transparency.

are schematic representations of both sides of a drum brake plate equipped with an electric parking brake implementing an electric motor according to Figures 4 and 5.

DETAILED DISCUSSION OF PARTICULAR EMBODIMENTS

In figures 1 to 3, one can see a first example of an electric motor M1 comprising a stator 2 and a rotor 4 intended to rotate around an axis X.

Rotor 4 surrounds stator 2.

The stator comprises a metal frame 10 comprising notches, on which coils 12 are placed. The coils 12 are distributed in a circle around the axis X. The coils 12 are distributed in pairs. The stator includes at least one pair of coils. In the example shown, twelve coils 12 are implemented.

The coils of a pair are arranged diametrically opposite with respect to the X axis and are electrically connected.

The metal frame is for example made from a stack of metal sheets.

The frame 10 and the coils 12 are arranged on a plate 16 provided with a central crossing passage 15 of axis X.

The stator also comprises on the free face of the frame 10 switching tracks 14, each being electrically connected to a coil 12. In this example, a switching track 14 comprises an arcuate portion 14.1 centered on the axis X, a radial portion 14.2 extending outward and connecting to a coil 12.

The arcuate portion 14.1 extends radially between a radius R1 and a radius R2, R2>R1 and the arcuate portions 14.1 are arranged relative to each other to form a discontinuous ring of interior radius R1 and of outer radius R2.

The switching tracks are for example made of copper.

The switching tracks 14 are distributed around the X axis and are electrically isolated from each other. In the example shown, the ends of the circular arc portions 14.1 of two adjacent connection tracks are separated by an insulation distance 18.

On the , one can see an example of connection between the radial portion 14.2 of a switching track 14 and a coil. The radial portion 14.2 has a free end 20 in the form of a hook, to which the wire 22 of a reel is attached.

The rotor 4 comprises a cup-shaped body provided with a bottom 6 orthogonal to the axis X, and with a side wall 8.

The rotor 4 also comprises permanent magnets 24 fixed on the inner face of the side wall 8 so as to be at least partly facing the radially outer ends of the coils 12.

The rotor 4 comprises at least one pair of magnets fixed diametrically opposite and so that the north pole of one magnet of a pair is oriented inwards and the south pole of the other magnet of the pair is oriented inward.

In the example shown, six pairs of magnets are used.

As a variant, the magnets are replaced by a single crown comprising zones of opposite polarity distributed successively around the X axis.

The rotor 4 also comprises on the inner face of the bottom 6 two electric conductive tracks 26, 28 concentric and centered on the axis X. the rotor also comprises two first sliding connectors or first brushes 30, 32, each electrically connected to a conductive track 26, 28 respectively and fixed on the inside face of the bottom. The first brushes 30, 32 extend parallel to the axis X so that their free end is in contact with the stator 2, more particularly either in contact each with a switching track 14. The dimension of each brush 30, 32 along the direction X is therefore substantially equal to the distance between the free face of the stator 2 and the inner face of the bottom 6.

The brushes, commonly called brushes, are for example made of carbon or formed by a flexible metal blade,

In the example shown, the tracks 26, 28 are suspended from the bottom 6, allowing the brush 30 of the radially inner track 26 to be located outside the track 28, the connection portion between the track 26 and the brush 30 passing between the track 28 and the bottom 6. The brushes are such that the free end of the brush 30 and the free end of the brush 32 are remote from the axis X, so as to be at least partly between a circle of radius R1 and a circle of radius R2. The brushes 30, 32 are located on a circle having approximately the same average radius as the arcuate portions 14.1 of the switching tracks. “Average radius of a track” means the average value between the inner radius and the outer radius of a switching track, i.e. (R1 + R2)/2.

Thus, when the rotor is in place around the stator, the free ends of the brushes 30, 32 are in contact at least in part with the circular arc portions 14.1 of the commutation tracks.

In addition, the suspension mounting also allows to offer a certain freedom of mounting in the X direction, making it possible to compensate for manufacturing tolerances. In addition, the brushes offer a certain elasticity in the X direction to ensure good contact between the brushes and the commutation tracks. The first brushes 30, 32 are for example carried by arms which offer this elasticity in the direction X.

The electric motor M1 also comprises two contacts 34, 36 intended to be connected to a source of direct current and ensuring the electrical supply of the coils. The contacts 34, 36 are carried by the stator 2 and pass through the metal frame 10. The contacts 34 and 36 each have a first end (not visible) on the plate side intended for connection to the direct current source, and a second end 34.1, 36.1 projecting from the free face of the stator. Contacts 34, 36 are electrically isolated from frame 10.

The second end 34.1 of the contact 34 and the second end of the contact 36.1 form second brushes configured to come into permanent contact with the tracks 26, 28 respectively. For this purpose, contact 34 is located on a circle having approximately the same average radius as track 26 and contact 36 is located on a circle having the same average radius as track 28. track”, the average value between the inner radius and the outer radius of a track.

In the example shown, the output shaft 38 of the motor M1 is directly attached to the inner face of the bottom 6 and passes through the through passage 15 of the plate 16 of the stator and emerges on the side opposite the bottom of the rotor. In this example, the output shaft 38 is attached to the rotor 4. Alternatively, the output shaft is made in one piece with the rotor. As a variant, a reduction device, for example of the planetary gear type, is integrated in the through passage 15 of the stator, the input sun gear being fixed in the bottom of the rotor.

The motor can advantageously include a casing cover (not shown) covering the rotor and being fixed for example on the plate 16 of the stator 2.

When the rotor 4 is mounted around the stator 2, the second end 34.1, 36.1 of the contacts 34, 36 is in permanent contact with the track 26, 28 respectively. Due to the suspended mounting of the tracks 26, 28 on the rotor 4, the dimensional constraints are relaxed.

The brushes 30, 32 are each in contact with a switching track 14, more particularly with the circular arc portions 14.1. The two switching tracks 14 are diametrically opposed.

The track 26, brush 30 and commutation track 14 assembly and the track 28, brush 32 and commutation track 14 assembly form rotary commutator collectors, creating an electrical connection between the stator and the rotor, with a switching function during the rotation.

The operation of the motor M1 of FIGS. 1 and 2 will now be described.

The motor is supplied with direct current via the contacts 34, 36 which supply the tracks 26, 28 respectively which themselves supply the switching tracks 14 (the hatched tracks on the ), supplying two diametrically opposed coils 12 via the first brushes 30, 32. The coils 12 generate a magnetic field, on which tends to align the magnetic moment of the magnets 24, which causes a displacement of the rotor 4. Or the rotation of the rotor 4 causes a rotation of the brushes 30, 32 which will come into contact with the adjacent diametrically opposed switching tracks 14, then supplying the adjacent diametrically opposed coils 12, which modifies the orientation of the magnetic field, on which the magnetic moment will try again to line up. The rotation of the rotor generates a rotating magnetic field which attracts the rotor.

The motor does not require an electronic current control system ensuring the current commutation in the stator windings.

In figures 4 and 5, one can see a second embodiment of an electric motor M2.

The M2 motor differs from the M1 motor in that the supply of the coils is not done through the stator but through a cover.

The motor of FIGS. 4 and 5 comprises a stator 102, a rotor 104 mounted around the stator 102 and a casing forming a cowl 139 mounted on the rotor at least opposite the outer face of the bottom of the rotor.

Stator 102 is substantially identical to stator 2 of motor M1.

The rotor 104 has the shape of a cup comprising a bottom 106 and a side wall 108.

It also comprises concentric circular tracks 126, 128 centered on the X axis. The tracks 126, 128 are located on the outer face of the bottom 106 of the rotor opposite the cover 139. 104 and connected to the tracks 126, 128 through the bottom 106 of the rotor 104. As for the brushes 30 and 32, the first brushes 130, 132 are advantageously supported so as to present a certain elasticity along the axis X. In this example, the first brushes 130, 132 are located inside the track 126.

The cover 139 comprises electrical conductors 134, 136 intended to supply each of the tracks 126, 128.

The electrical conductors 134, 136 each have a first end 134.1, 136.1 intended to be connected to a direct current source and a second end 134.2, 136.2 provided with a second brush 140, 142. The second brushes 140, 142 are arranged so as to be in permanent contact with the tracks 126, 128 respectively.

Very advantageously, the part of the cover 139 housing the first ends 134.1, 136.1 is configured in the form of a connector 144 whose shape is that of the connectors usually used in the automotive field, facilitating the connection of the motor to the power supply. electric. The M2 motor is therefore easily integrated into an existing structure.

Similar to the M2 motor, the output shaft is attached directly to the bottom of the rotor and passes through the stator. As a variant, a reduction device, for example of the planetary gear type, is integrated in the through passage of the stator, the input sun gear being fixed in the bottom of the rotor.

When the motor M2 is assembled, i.e. the rotor 104 is mounted around the stator 102 and the cover 139 covers the rotor 104, the second brushes 140, 142 are in permanent contact with the tracks 126, 128 respectively, and the first brushes 130, 132 are in contact with two diametrically opposed switching tracks 114, more particularly with the circular arc portions 114.1. Due to the elasticity of the first brushes 130, 132, the dimensional constraints in the X direction are relaxed.

The track 126, first brush 130 and commutation track 114 assembly and the track 128, first brush 132 and commutation track 114 assembly form rotary commutator collectors, creating an electrical connection between the stator 102 and the rotor 104, with a switching function during rotation.

The operation of the motor of FIGS. 4 and 5 will now be described.

The motor is supplied with direct current via the electrical conductors 134, 136 connected to a source of direct current, which supply the tracks 126, 128 via the second brushes 140, 142 respectively. Tracks 126, 128 feed switching tracks 114 via first brushes 130, 132, feeding two diametrically opposed coils 112. The coils 112 generate a magnetic field, on which tends to align the magnetic moment of the magnets 124, which causes a displacement of the rotor 104. Now the rotation of the rotor 104 causes a rotation of the brushes 130, 132 which will come into contact with the neighboring diametrically opposed switching tracks 114, feeds the neighboring diametrically opposed coils 112, which modifies the orientation of the magnetic field, and on which the magnetic moment will again try to align itself. Rotation of rotor 104 generates a rotating magnetic field which attracts the rotor.

In the examples described, the coils are advantageously carried by the stator and the magnets are carried by the rotor, which simplifies the electrical supply of the coils. Nevertheless, an electric motor in which the coils are carried by the rotor and the magnets are carried by the stator does not depart from the scope of the present invention.

In the examples described, the first two brushes are at the same radial distance from the X axis, the switching tracks have a single arcuate portion. As a variant, the first two brushes are at different radial distances from the X axis, and the switching tracks comprise two arcuate portions, one having a radius corresponding to the radial distance of one of the first brushes and the other having a radius corresponding to the radial distance from the other of the first brushes. Other switching track shapes are possible, for example an angular portion shape.

In FIGS. 6A and 6B, a drum brake can be seen schematically equipped with a motor M2 according to the invention ensuring the actuation of the electric parking brake.

The drum brake comprises a plate 202 of revolution of axis AX equipped with a first and a second segment in an arc of a circle 203 and 204 movable radially to be able to be pressed against the cylindrical internal face of a drum not shown.

The segments 203 and 204 each comprise a core 203a, 204a of flat sheet metal in the shape of a portion of a circular crown which carries a brake lining 203b, 204b, and are mounted diametrically opposite with their ends bearing both on a wheel cylinder 206 hydraulic and on a mechanical actuator 207 carried by the plate 202. These segments 203 and 204 are also biased towards each other by two return springs 208 and 209, and pressed against the plate 202 each by a spring.

A wear take-up link 212 extends along the wheel cylinder 206 having a first end resting on the web 203a of the first segment 203 and a second end resting on the web 204a of the second segment 204.

The wheel cylinder 206 is intended to be actuated when using the drum brake according to a first so-called "simplex" mode of operation, which provides progressive braking particularly suitable for braking the vehicle in service. It comprises a hydraulic chamber closed at its ends by two pistons which move apart when the hydraulic pressure increases and pushes the associated ends of the segments 203 and 204.

The mechanical actuator 207 provides the parking and emergency braking by moving the associated ends of the segments apart to ensure rapid and powerful locking of the vehicle wheels according to a so-called "duo-servo" operating mode, in particular when the cylinder wheel 206 is inactive. This actuator is driven by the electric motor M2. The mechanical actuator 207 is for example of the screw-nut type, the nut being driven by the electric motor M2. The motor M2 is mounted on a face 202.2 of the plate 202 opposite to the face 202.1 carrying the actuator 207 and the mechanical connection is made through the plate. For example, the nut comprises a toothed crown meshed with one or more toothed wheels driven by the electric motor M2, either directly by the output shaft 138, or via a reduction device.

The relatively flat and thin shape of the electric motor is particularly advantageous for integration into a brake. In addition, it is capable of developing sufficient torque making it suitable for actuating an electric parking brake, for example between 0.2 Nm and 1 Nm.

The electric motor can be implemented in a brake in order to ensure both the service brake function and the parking brake function.

References

2, 102 stator

4, 104 rotor

6, 106 rotor bottom

8, 108 rotor side wall

10 metal frame

12, 112 coil

14, 114 switch track

14.1 portion of an arc

14.2, 14.3 radial portion

15 inside passage

16 stator plate

18 isolation distance

20 free end of the radial portion

22 wire

24, 124 permanent magnet

26, 126, 28, 128 electric track

30, 130, 32, 132 first broom

34, 36, 134, 136 electrical conductor

38, 138 output shaft

134.1, 136.1 first end

139 hood

140, 142 second broom

144 connector

202 drum brake plate

202.1, 202.2 face of the board

203 first segment

203a, 204a soul

203b, 204b brake lining

204 second segment

206 wheel cylinder

207 mechanical actuator

208, 209 return spring

212 wear compensator rod

M1, M2 engine

X motor axis

AX brake plate axle

Claims (11)

Electric motor comprising a stator (2, 102) and a rotor (4, 104), said rotor (4, 104) surrounding the stator (2, 102), the rotor (4, 104) being configured to rotate around a longitudinal axis X, n pairs of coils (12, 112), the coils of each pair being diametrically opposed, n being an integer > 0 and m pairs of magnetic poles, m being an integer >0, poles of opposite polarity being arranged diametrically opposed, the n pairs of coils (12, 112) being carried by the rotor (4, 104) or the stator and the m pairs of poles being carried by the stator (2, 102) or the rotor respectively, electrical connection means intended to supply the motor with direct current, characterized in that it comprises rotary commutator collector means of the n pairs of coils (12, 112) distributed between the rotor and the stator, said rotary commutator collector means being connected simultaneously to the coils (12, 112) of a pair and sequentially to the m bo bins. Electric motor according to Claim 1, in which the rotor (4, 104) comprises a bottom (6, 106) perpendicular to the longitudinal axis X and a side wall (8, 108) and in which at least part of the collector means rotary switches is arranged between the bottom (6, 106) of the rotor (4, 104) and the stator. Electric motor according to Claim 2, in which the n pairs of coils (12, 112) are carried by the stator (2, 102) and the n pairs of poles are carried by the side wall (8, 108) of the rotor (4 , 104), and in which the rotary commutator collector means of the coils comprise two concentric circular electrical conductor tracks (26, 28, 126, 128) of axis X carried by the bottom of the rotor (4, 104), at least two first brushes (30, 32), each being electrically and mechanically connected to the two electrical tracks (26 28, 126, 128) and switching tracks (14, 114) carried by the stator (2, 102) and electrically insulated from each other others, each switching track (14, 114) being electrically connected to a coil (12, 112), said first brushes (30, 32, 130, 132) being arranged in a diametrically opposite manner and so as to come into contact simultaneously with two switching tracks (14, 114) diametrically opposed and sequentially with said switching tracks. Electric motor according to Claim 3, in which the first two brushes (30, 32, 130, 132) are arranged substantially on the same circle and the commutation tracks (14, 114) comprise an arcuate portion (14.1, 114.1 ) with which the first brushes (30, 32, 130, 132) are sequentially in contact. Electric motor according to Claim 3 or 4, comprising two second brushes in permanent contact with the electrical tracks (26, 28, 126, 128) and connecting the electrical connection means intended to supply the motor with direct current and the electrical tracks (26 , 28, 126, 128). Electric motor according to Claim 5, in which the second brushes are carried by contacts (34, 36) fixed to the stator (2), the electric tracks (26, 28) and the first brushes (30, 32) being located at the inside the rotor (4). Electric motor according to Claim 5, comprising a cover (139) covering at least part of the rotor (104), in which the second brushes (140, 142) are fixed to the cover (139), the electrical tracks (126, 128) being located outside the rotor (104), and in which the electrical connection means intended to supply the motor with direct current are carried by the cover (139). Electric motor according to one of Claims 1 to 7, comprising an output shaft (38) and in which the stator (2) comprises a central passage (15), the said output shaft (38) being fixed to the rotor (4) and passing through the stator (2) through the central passage (15). Gearmotor comprising an electric motor according to one of the preceding claims, the stator comprising a central passage and a reduction device mounted in the central passage of the stator. Motor vehicle brake comprising friction elements intended to come into contact with a part fixed in rotation to a wheel in order to brake it, a mechanical actuator for moving the friction elements and an electric motor according to one of Claims 1 to 8 or a geared motor according to claim 9, connected to the mechanical actuator to actuate it. Brake according to the preceding claim, said actuator being configured to be activated to provide for parking braking.