EP2794320A1

EP2794320A1 - Motor-driven hub for electrically driving an axle of a hybrid-drive motor vehicle

Info

Publication number: EP2794320A1
Application number: EP12798324.5A
Authority: EP
Inventors: Daniel Walser; Gérard BAUMGARTNER
Original assignee: Michelin Recherche et Technique SA Switzerland; Compagnie Generale des Etablissements Michelin SCA; Michelin Recherche et Technique SA France
Current assignee: Michelin Recherche et Technique SA Switzerland; Compagnie Generale des Etablissements Michelin SCA; Michelin Recherche et Technique SA France
Priority date: 2011-12-20
Filing date: 2012-12-11
Publication date: 2014-10-29
Also published as: FR2984243A1; WO2013092301A1; FR2984243B1

Abstract

The invention relates to a motor-driven hub for electrically driving an axle of a hybrid-drive motor vehicle, said motor-driven hub including a hub (1) rotatably mounted, with respect to a hub holder (2), about a hub axis (A), the motor-driven hub including an electric drive machine (4) including an external stator connected to the hub holder (2) and an internal rotor, the rotational axis (R) of which is spaced apart from the hub axis (A), the motor-driven hub including a reduction means and a coupling/uncoupling means capable of assuming a coupling position, in which the rotation of the electric machine (4) is coupled with the rotation of the hub (1), and an uncoupling position, the coupling/decoupling means including a mechanism (10) having a sliding gear, said mechanism including rolling bodies (11) which are arranged in a track (12) of the sliding gear (10), said track being arranged, by a movement of the sliding gear (10) in the coupling position, so as to rotatably link the hub (1) and the reduction means via said rolling bodies.

Description

Motorized hub for the electric drive of an axle of a hybrid traction motor vehicle

The invention relates to a motorized hub for the electric drive of an axle of a hybrid traction motor vehicle, a motorized wheel comprising such a hub and a motor vehicle comprising at least two motorized wheels.

In particular, the invention applies to motor vehicles having electrically powered wheels that can be decoupled from their electric machine when the vehicle is moved through another source of traction.

In the field of the ground connection of electric traction motor vehicles, in particular their motorized wheels, a certain number of proposals are known, including that of document WO-201 1/073320 which describes a motorized hub comprising reduction means acting between the rotor of the electric machine and the hub as well as coupling / decoupling means adapted to adopt a coupling position in which the rotation of the electric machine is coupled to the rotation of the hub and a decoupling position in which the rotation of the electric machine is decoupled from the rotation of the hub.

In the present application, the term "motorized hub" is used to designate the mechanical assembly comprising the hub, the hub-carrier, the guiding of the hub relative to the hub-carrier, the electric motor and the braking means of the hub. . The motorized hub is therefore intended on the one hand to receive a wheel equipped for example with a tire and to carry on the other hand a vehicle, generally by means of suspension means. In the present application, the term "motorized wheel" is also used to designate the mechanical assembly comprising the motorized hub defined above and the corresponding wheel. One of the difficulties in adopting such motorized hubs on production vehicles is the compatibility with the solutions already adopted and validated by manufacturers for certain elements such as suspension systems and wheels. Another difficulty is to obtain a compact system, simple and as light as possible to make the cost acceptable for this industry.

In particular, the integration of electric motors inside the wheels is particularly desirable because the adoption of electric traction often requires the need to ship batteries to store electrical energy which, even with the most powerful technologies known to date, requires to devote a sufficient volume to the batteries in the vehicle, except to greatly reduce the autonomy of an electric vehicle. Similar reasoning can be used for fuel cell or parallel hybrid vehicles.

Moreover, if we want to develop sufficient traction torque, it is necessary to install reduction means because we can not, with a sufficiently compact electric motor, develop adequate torque to ensure traction directly. of a passenger vehicle.

In addition, parallel hybrid vehicles whose thermal engine generally allows to drive at relatively high speed (for example 50 km / h) represent a particular difficulty in choosing the reduction ratio of electric traction.

Finally, it is generally necessary to integrate in the wheel, not only the electric motor, the associated necessary reduction means, but also a mechanical braking device (disk brake or friction drum).

To solve all these problems, the document WO-201 1/073320 proposes coupling / decoupling means comprising a mechanism for dog and walkman, said walker being coaxial with the hub being constantly rotatably integral reduction means.

In particular, when the electric traction is decoupled, the reduction means are not rotated by the rotation of the hub when the vehicle is moved through another source of traction, to limit noise and torque induced drag.

For this configuration, the document WO-201 1/073320 proposes a coupling via cylindrical splines, respectively internal on the player and external on a ring gear of the reduction means and on the hub.

However, these grooves are difficult to machine, especially in that they are not open on the hub and on the toothed wheel, and require a large travel distance of the player around the hub to ensure the transmission of the traction torque, which goes against the compactness sought for the motorized hub. The invention aims to improve the prior art by providing a compact motorized hub, easy to achieve and in which noise and induced drag torque can be limited when electric traction is not used.

For this purpose, according to a first aspect, the invention proposes a motorized hub for the electric drive of an axle of a hybrid traction motor vehicle, said motorized hub comprising a hub for receiving a wheel, said hub being rotatably mounted. relative to a hub carrier according to a hub axis, the motorized hub comprising an electric traction machine, the electric machine comprising an outer stator connected to the hub carrier and an inner rotor whose axis of rotation is distant from the hub axis, the motorized hub comprising reduction means acting between the rotor of the electric machine and the hub, the motorized hub comprising coupling / decoupling means adapted to adopt a coupling position in which the rotation of the electrical machine is coupled to the rotation of the hub and a decoupling position in which the rotation of the electric machine is decoupled from the rotation of the hub, the coupling / decoupling means comprising a walkman mechanism, said mechanism comprising bodies rollers which are arranged in a track of the player, said track being arranged, by moving the player in the coupling position, to link in rotation the hub and the reduction means via said rolling bodies. According to a second aspect, the invention proposes a motorized wheel comprising such a motorized hub.

According to a third aspect, the invention proposes a motor vehicle comprising at least two motorized wheels.

Other objects and advantages of the invention will appear in the description which follows, made with reference to the appended figures, in which:

- Figure 1 is an overall perspective view of a motorized hub according to one embodiment of the invention;

- Figure 2 is a partial longitudinal sectional view of a motorized hub according to the invention.

- Figure 3 is a detailed view of a preferred embodiment of the motorized hub according to the invention. In connection with these figures, an embodiment of a motorized hub is described below which is intended to guide and control the rotation of a wheel, in particular for the electric motorization of an axle of a traction motor vehicle. hybrid. The motorized hub comprises a hub 1 intended to receive a wheel, said hub being rotatably mounted relative to a hub carrier 2 according to a hub axis A. In particular, the hub carrier 2 is a rocket around which the hub rotates 1 through a hub bearing 3. The hub axis A is a constant reference in the present application, it is with respect to this axis that we refer to qualify an orientation of "radial" or "axial". As a reminder and according to the customary use in the field of the tire or the wheel, an axial orientation is an orientation parallel to the hub axis A and a radial orientation is an orientation perpendicular to the hub axis A.

The motorized hub comprises an electric traction machine 4, the electric machine 4 comprising an external stator connected to the hub carrier 2 and an inner rotor whose axis of rotation R is distant from the hub axis A. In particular, the electric machine 4 has an inner rotor whose axis of rotation R is distant from the hub axis A and parallel to said hub axis, that is to say non-coaxial.

The electric machine 4 assures the motorization and possibly the braking of the hub 1 by means of reduction means acting between the rotor of the electric machine 4 and the hub 1. The reduction means comprise a driving pinion 5 intended to be connected to the rotor of the electric machine 4 and a ring gear 6 intended to be connected to the hub 1.

The reduction means preferably comprise two reduction stages. In FIG. 2, a first reduction stage comprises the gear of the driving pinion 5 and of a gearwheel 7 connected to an intermediate shaft 8 parallel to the hub axle A, a second reduction stage comprising the gearwheel a reduction gear 9 connected to the intermediate shaft 8 and the ring gear 6 intended to be connected to the hub 1. The overall reduction ratio is preferably greater than 15. The motorized hub comprises coupling / decoupling means able to adopt a coupling position (FIG. 2) in which the rotation of the electric machine 4 is coupled to the rotation of the hub 1. and a decoupling position in which the rotation of the electric machine 4 is decoupled the rotation of the hub 1, so as respectively to establish and interrupt the transmission of torque between the reduction means and the hub 1.

The coupling / decoupling means comprise a walkman mechanism 10. In the embodiment shown, the player 10 is coaxial with the hub 1 while being constantly rotatably integral with the reduction means. In this way, when the vehicle is traveling in decoupled mode and the electric machine 4 is stopped, the hub 1 is the only moving part while the reduction means and the player 10 are immobile in order to limit the noise as well as the torque induced drag.

In the embodiment shown, the player 10 is mounted in translation along the hub axis A around the ring gear 6 between a coupling position and a decoupling position. In known manner, a fork can be used to control the axial position of the player 10, said fork can be controlled by a screw actuator and nut comprising a small electric gear motor or an electromagnet.

The walkman mechanism comprises rolling bodies 1 1, for example balls, which are arranged in a track 12 of the player 10, said track being arranged, by displacement of the player 10 in the coupling position, to link in rotation the hub 1 and the reduction means via said rolling bodies. In relation with FIG. 2, the track 12 has an axial slope which is arranged for, in the coupling position, that the rolling bodies 1 1 are pushed radially to be engaged respectively in an impression 13 integral with the hub 1 and, in the position of decoupling, said rolling bodies are released from said indentations. In particular, the indentations 13 may be substantially hemispherical and be distributed angularly to ensure good torque transmission. In particular, a row of balls may be disposed in the track 12 (in Figure 2, the section does not go through the center of the bottom ball shown). In the embodiment shown, the ring gear 6 comprises an axial annular bearing surface 6a in which passages 14 are formed, the rolling bodies 1 1 being arranged in said passages to be rotated by said ring gear. The annular bearing surface 6a is arranged around an axial annular bearing surface 1a of the hub 1, the cavities 13 being formed in said bearing surface to ensure the rotational connection when a rolling body January 1 is disposed in a recess 13 and a passage 14 arranged radially opposite.

The player 10 may be equipped with a means for retaining the rolling bodies 1 1 in the free position of the cavities 13. For example, this means may be formed of a magnet 15 exerting a radial magnetic attraction on a rolling body 1 1 disposed in open position. The player 10 can also be equipped with a means of elastic stress of the rolling bodies 1 1 in the engaged position in the indentations 13, to ensure that all the rolling bodies January 1 carry at the same time despite the multiplicity of contacts and therefore the hyperstatism of the connection. An example of resilient biasing means is given in Figure 3 where we see that a resilient tongue 20 pushes the rolling body January 1 in its engaged position.

The entire transmission, ie all of the reduction means and the coupling / decoupling means, is contained in a sealed casing 16 containing a suitable quantity of a lubricant in order to lubricate the assembly by bubbling. .

The stator of the electrical machine 4 is rotatably connected to the hub carrier 2. This connection, necessary for the transmission of the torque, can be rigid and direct but it can preferably be indirect in order to allow a relative rotational movement at the same time. opportunity of suspension travel. This relative movement is of course limited and aims to allow a certain independence between the transmitted torque and the dynamic rigidities (vertical and horizontal) of the suspension device. In particular, the stator of the electric machine 4 is carried by the housing 16 while said housing is rotatably mounted relative to the hub carrier 2 according to the hub axis A. The rotation of the housing 16 relative to the hub carrier 2 can be controlled by a connecting rod acting between the housing 16 and the vehicle body.

In addition, the motorized hub comprises a disc brake whose disc 17 is placed outside the housing 16 relative to the vehicle. Although this is a preferred embodiment, it is known to those skilled in the art that in some situations it may be preferable to use a drum brake instead of the disc brake.

An advantageous way of constructing a hybrid vehicle is to combine a conventional thermal engine of the front axle and an electric motorization of the wheels of the rear axle according to the invention. In particular, the hub carriers 2 of the wheels can each be secured to an arm pulled from the rear axle, for example torsion, of the hybrid vehicle. The source of electrical energy may be a set of batteries or supercapacitors, a fuel cell, an urban network in the manner of trolley buses or any other available electrical source.

FIG. 1 shows a single electric machine 4. Naturally, it is possible according to the invention to implement two or more machines 4 for each hub 1, the machines 4 each meshing by means of a driving pinion 5 clean on common means of reduction. Thanks to a multiple motorization, it is possible to increase the available torque and / or to reduce the axial and radial dimensions of the electrical machines 4.

Whatever the embodiment of the invention, the reduction means are preferably reversible to allow the use of the electric machine 4 in braking mode. The electrical energy recovered by the electric machine 4 in braking mode can be stored or dissipated in a manner known per se. A motorized hub according to the invention thus allows coupling / uncoupling the electric motor at any time, including during the movement of the vehicle. To allow decoupling smoothly, it is preferable to control the electric machine 4 so that it transmits a zero or very low torque when the player 10 is moving.

Although the present description focuses on a specific embodiment, those skilled in the art can consider other combinations of the various means described herein or other combinations of some of these means with other means not described here but known. of the state of the art.

Claims

1. Motorized hub for the electric motorization of an axle of a hybrid traction motor vehicle, said motorized hub comprising a hub (1) intended to receive a wheel, said hub being rotatably mounted with respect to a hub carrier (2) according to a hub axle (A), the motorized hub comprising an electric traction machine (4), the electric machine (4) comprising an outer stator connected to the hub-carrier (2) and an inner rotor whose axis of rotation ( R) is remote from the hub axle (A), the motorized hub comprises reduction means acting between the rotor of the electric machine (4) and the hub (1), the motorized hub comprising coupling / decoupling means adapted to adopt a coupling position in which the rotation of the electric machine (4) is coupled to the rotation of the hub (1) and a decoupling position in which the rotation of the electric machine (4) is decoupled from the rotation of the hub (1), coupling means e / decoupling comprising a walkman mechanism (10), said motorized hub being characterized in that said mechanism comprises rolling bodies (1 1) which are arranged in a track (12) of the player (10), said track being arranged, by moving the slider (10) in the coupling position, for rotatably connecting the hub (1) and the reduction means via said rolling bodies.

2. Motorized hub according to claim 1, characterized in that the slider (10) is coaxial with the hub (1) being constantly rotatably integral reduction means.

3. Motorized hub according to claim 2, characterized in that the track (12) has an axial slope which is arranged for, in the coupling position, that the rolling bodies (1 1) are pushed radially to be engaged respectively in a footprint. (13) integral with the hub (1) and, in the decoupling position, said rolling bodies are released from said indentations.

4. Motorized hub according to claim 3, characterized in that the walkman (10) is equipped with a means (15) for retaining the rolling bodies (1 1) in the released position of the cavities (13).

5. Motorized hub according to claim 3 or 4, characterized in that the player (10) is equipped with a means of elastic stress of the rolling bodies (1 1) in the engaged position in the footprints (13).

6. Motorized hub according to any one of claims 2 to 5, characterized in that the reduction means comprise a ring gear (6) intended to be connected to the hub (1), the player (10) being mounted in translation next the hub axle (A) around the ring gear (6) between a coupling position and a decoupling position.

7. Motorized hub according to claim 6 when dependent on claim 3, characterized in that the indentations (13) are formed on the hub (1).

Motorized hub according to claim 6 or 7, characterized in that the reduction means comprise two reduction stages.

Motorized hub according to claim 8, characterized in that a first reduction stage comprises the gear of a motor gear (5) intended to be connected to the rotor of the electric machine (4) and a gear wheel. (7) connected to an intermediate shaft (8), a second reduction stage comprising the gear of a reduction gear (9) connected to the intermediate shaft (8) and the ring gear (6) to be connected at the hub (1).

10. Motorized hub according to any one of claims 1 to 9, characterized in that it comprises a casing (16) sealed containing the reduction means and the coupling / decoupling means and carrying the electric machine (4), said housing containing a lubricant.

1 1. Motorized wheel comprising a motorized hub according to any one of claims 1 to 10.

12. Motor vehicle comprising at least two motorized wheels according to claim 1 1.

13. Motor vehicle according to claim 12, characterized in that two motorized wheels are disposed on the rear axle of said vehicle, the hub carriers (2) of said wheels each being integral with an arm drawn from the rear axle.