FR3111489A1 - MOTOR GEAR AND PARKING BRAKE OF A MOTOR VEHICLE IMPLEMENTING SUCH A GEAR MOTOR - Google Patents

Abstract

Electric gear motor comprising a brushless 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 ), coils (12) being carried by the stator (2) and poles being carried by the rotor (4), electrical connection means intended to supply the motor with direct current, means for sequentially supplying the coils, a reduction device (DR) and an output shaft (22) characterized in that the stator (2) has a through passage (14), in that the reduction device (DR) is housed at least partly in the through passage (14) of the stator (2) and in that the output shaft (22) protrudes from the stator (2). Figure for abstract: 2

Description

GEAR MOTOR AND MOTOR VEHICLE PARKING BRAKE IMPLEMENTING SUCH A GEAR MOTOR

TECHNICAL AREA AND PRIOR ART

The present invention relates to a compact electric gear motor and to a motor vehicle parking brake implementing such a gear 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 into different vehicle models.

BLDC type motors (Brushless Direct Current in English terminology) are brushless motors, which offer an increased lifespan since there is no longer any problem of brush wear.

It is therefore an object of the present invention to provide a geared motor offering great compactness.

The object stated above is achieved by an electric gear motor comprising a stator carrying coils, and a rotor carrying magnetic poles, the rotor being mounted around the stator and the output shaft of the gear motor passing through the stator, the reduction device being disposed at least partly inside the stator.

The geared motor then has great compactness, since the gear is included at least in part in the casing of the electric motor.

In the external rotor geared motor, the magnets are arranged over a large diameter, which creates a very interesting lever arm. The motor then advantageously offers a high motor torque.

The geared motor according to the invention is particularly suitable for producing at least partially electrically controlled brakes, for example with a brake having an electric parking brake function.

In other words, the geared motor comprises a brushless motor with an external rotor housing at least partly the reduction gear.

One of the objects of the present application is an electric geared motor comprising a brushless electric motor comprising a stator and a rotor, said rotor surrounding the stator, the rotor being configured to rotate around a longitudinal axis, coils being carried by the stator and the poles being carried by the rotor, electrical connection means intended to supply the motor with direct current, means for sequentially supplying the coils, a reduction device and an output shaft. The stator has a through passage, the reduction device is housed at least partially in the through passage of the stator and the output shaft protrudes from the stator.

Preferably, the rotor comprises a bottom perpendicular to the longitudinal axis and a side wall, the poles being permanent magnets carried by the side wall.

The axis of the through passage of the stator is advantageously the longitudinal axis.

For example, the reduction device is an epicyclic gear train comprising a sun gear integral in rotation with the bottom of the rotor, satellites, at least one ring gear and at least one planet carrier, the output shaft being integral in rotation with at least a satellite carrier.

According to an additional characteristic, the sun gear is attached to the rotor.

Preferably, the reduction device is contained entirely within the through 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 fixed in rotation to a wheel in order to brake it, a mechanical actuator for moving the friction elements and a geared motor according to the present application, 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 side view of an example of a gearmotor,

is an exploded view of the geared motor of figure 1,

is a perspective view of the inside of the rotor of the geared motor of Figures 1 and 2,

are schematic representations of both sides of a drum brake plate equipped with an electric parking brake implementing an electric motor according to Figures 1 and 2.

DETAILED DISCUSSION OF PARTICULAR EMBODIMENTS

In figures 1 and 2, one can see a first example of an electric gear motor M 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 stator comprises at least one pair of coils. In the example shown, twelve coils 12 are implemented. The metal frame 10 is carried by a plate 5.

In one example, the coils 12 are distributed in pairs and are arranged diametrically opposite with respect to the X axis and are electrically connected.

In another example, the coils are in groups of three, and are arranged at 120° from each other.

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

The metal frame 10 is for example made from a stack of metal sheets.

The frame 10 and the coils 12 are arranged on a plate 5 provided with a central crossing passage 14 of axis X.

The stator has a through passage 14 formed in the metal frame 10 between the coils 12 and passing through the plate 5.

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 9 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 (FIG. 3).

The rotor 4 comprises at least one pair of permanent 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 geared motor also comprises means 13 for connection to a direct current source, in order to supply the coils.

In this example, the control of the geared motor is carried out by an electronic switch (not shown) configured to sequentially supply the coils of the stator, thus generating a rotating electric field which “drives” the rotor in rotation. Advantageously one or more Hall effect type sensors (not shown) is or are used to know the position of the rotor and to make it possible to synchronize the supply of the coils and the position of the rotor. The switch and the sensor or sensors are for example carried by an electronic card. The electronic switch and the sensor(s) are for example carried by an electronic card.

The gearmotor can be single-phase, two-phase, the coils are in pairs, or three-phase, the coils are in threes. The operation of such an engine is well known to those skilled in the art.

The geared motor also comprises a reduction device DR mounted in the through passage 14 of the stator 2. In this example the reduction device DR is a single-stage planetary gear train comprising a sun gear 17 (FIG. 3) integral in rotation with the rotor. The sun gear is fixed on the inner face of the bottom 6 of the rotor.

The reduction device also comprises satellites 16 meshed by the sun gear and meshing with a planetary crown 20. The satellites are supported by a planet carrier 18 and.

The geared motor also comprises output shaft 22 integral with the planet carrier. The output shaft 22 protrudes from the plate 5 of the stator. The output shaft 22 is advantageously aligned with the sun gear 17 along their common axis X.

In the example shown, the sun gear 17 is attached to the bottom 6 of the rotor. Sun gear 17 is mounted through the bottom of the rotor. It is secured to the bottom 6 for example by welding. Alternatively, the sun gear is in one piece with the bottom 6.

All or part of the elements of the reduction device are advantageously made of plastic material, making it possible to reduce the mass of the geared motor.

This example is particularly advantageous because the reduction device is entirely contained in the stator, the size due to the integration of the reduction gear is not increased.

The motor can advantageously comprise a casing cover (not shown) covering the rotor and being fixed for example on the plate 5 of the stator 2.

In the example shown, the bottom 6 of the rotor is flat. As a variant, the bottom 6 has an outward boss allowing part of the reduction device to be housed.

The operation of the geared motor will now be described.

The switch provides a sequential power supply to the coils, with the coils creating a magnetic field that rotates at the same frequency as the supply voltages. The permanent magnets of the rotor seek to orient themselves in the direction of the magnetic field, but the latter moves and moves away continuously while rotating. The rotor continues its course to join the magnetic field, which induces the rotation. The reduction device makes it possible to reduce the speed of rotation of the output shaft 22 in relation to that of the rotor and to increase its torque. The sun gear 17 is driven in rotation around the X axis, driving the planet gears which also mesh with the planet gear 20. The planet gear carrier is then driven in rotation as well as the output shaft 22, which rotates at a reduced speed by compared to the satellite but with an increased torque.

Figures 4A and 4B show schematically a drum brake equipped with a geared motor M according to the invention ensuring actuation of the electric parking brake.

The drum brake comprises a plate 202 of revolution of axis AX equipped with a first segment 203 and a second segment 204 in an arc of a circle that are radially movable so as 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 which carries a brake lining 203b, 204b, and are mounted diametrically opposite with their ends resting both on a hydraulic wheel cylinder 206 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 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 ensures, for its part, the parking and emergency braking by spreading the associated ends of the segments to ensure rapid and powerful locking of the wheels of the vehicle according to a so-called "duo-servo" operating mode, in particular when wheel cylinder 206 is inactive. This actuator is driven by the electric gear motor M. The mechanical actuator 207 is for example of the screw-nut type, the nut being driven by the gear motor M. The gear motor M 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 meshing with one or more toothed wheels driven by the geared motor M, either directly by the output shaft 22, 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 gear motor can be implemented in a brake in order to ensure both the service brake function and the parking brake function.

It is understood that a disc brake comprising a geared motor according to the invention does not depart from the scope of the present invention.

References

2 stator

4 rotor

5 stator plate

6 rotor bottom

8 rotor side wall

9 permanent magnet

10 metal frame

12 coil

13 connection ways

14 through passage

16 satellites

17 planetary

18 planet carriers

20 planetary crown

22 output shaft

202 drum brake plate

202.1, 202.2 face of the board

203 first segment

204 second segment

203a, 204a soul

203b, 204b brake lining

206 wheel cylinder

207 mechanical actuator

208, 209 return spring

212 wear compensator rod

DR reduction device

M gear motor

X axis of the gear motor

AX brake plate axle

Claims (8)

Electric gear motor comprising a brushless 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 ), coils (12) being carried by the stator (2) and poles being carried by the rotor (4), electrical connection means intended to supply the motor with direct current, means for sequentially supplying the coils, a reduction device and an output shaft (22) characterized in that the stator has a through passage (14), in that the reduction device (DR) is housed at least partly in the through passage (14) of the stator (2) and in that the output shaft (22) protrudes from the stator (2). Electric geared motor according to Claim 1, in which the rotor (4) comprises a bottom (6) perpendicular to the longitudinal axis (X) and a side wall (8), the poles being permanent magnets (7) carried by the wall side (8). Electric gear motor according to Claim 2, in which the axis of the through passage (14) of the stator (2) is the longitudinal axis (X). Electric geared motor according to Claim 3, in which the reduction device (DR) is an epicyclic gear train comprising a sun gear (17) integral in rotation with the bottom (6) of the rotor (4), satellites (16), at least one gear (20) and at least one planet carrier (18), the output shaft (22) being integral in rotation with the at least one planet carrier (18). Electric geared motor according to Claim 4, in which the sun gear (17) is attached to the rotor (4). Electric geared motor according to one of Claims 1 to 5, in which the reduction device (DR) is contained entirely in the through passage (14) of the stator (2). Brake for a motor vehicle 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 a geared motor according to one of Claims 1 to 6 , connected to the mechanical actuator to operate it. Brake according to the preceding claim, said actuator being configured to be activated to provide parking braking.