EP4247657A1

EP4247657A1 - Electric drive device for a vehicle axle

Info

Publication number: EP4247657A1
Application number: EP21815511.7A
Authority: EP
Inventors: Fabien LEBEAU
Original assignee: Valeo Embrayages SAS
Current assignee: Valeo Embrayages SAS
Priority date: 2020-11-20
Filing date: 2021-11-22
Publication date: 2023-09-27
Also published as: CN116745156A; FR3116578A1; FR3116578B1; WO2022106681A1

Abstract

The invention relates to an electric drive device (1) for a vehicle axle, comprising - a rotor (2) of an electric machine (3) with an input shaft (4), - a driveshaft of the vehicle, - a transmission gear mechanism (5) disposed between the input shaft and the drive shaft, the gear mechanism comprising at least one gear element, and - a parking brake device (9) with a blocking wheel (10), the blocking wheel being capable of interacting with one among the driveshaft, the input shaft or the gear element, wherein the drive device comprises a torque limiter (17) disposed between the input shaft and the driveshaft, the torque limiter interacting with the blocking wheel.

Description

Title of the invention: Electric drive device for a vehicle axle

The present invention relates to an electric drive device for a vehicle axle. The invention finds applications in the field of transmissions for electric vehicles.

[002] There is known an electric drive device for a vehicle axle comprising a rotor of an electric machine with an input shaft, a drive shaft of the vehicle, a transmission gear mechanism arranged between the input shaft and the drive shaft. In one example, the gear mechanism is driven directly from the input shaft. The speed of the electric machine, i.e. the rotor speed, is reduced by the transmission gear mechanism compared to the rotational speed of the vehicle drive shaft. The drive shaft can be two axes which are in functional connection with each other, in particular by means of a differential gear. In one example, the transmission gear mechanism includes two gear stages. A pinion tooth may be provided on a periphery of the input shaft, which meshes with a gear of the first stage transmission.

[003] Such an electric drive device is also equipped with a parking brake or handbrake. The purpose of the parking brake is to prevent the vehicle from rolling when the engine is off. In general it is activated by a lever.

[004] In particular, the parking brake is a mechanical locking of a rotating shaft relative to a support which is static. For example, the rotating shaft is the input shaft and the support is a housing of the gear mechanism. The parking brake essentially comprises a locking wheel having teeth on its circumference and is connected in a fixed manner in rotation to the rotor shaft of the electric machine. When the parking brake is activated, a locking mechanism is engaged. For example, a pawl is actuated to engage in the toothing of the locking wheel, then causing the forced stop in rotation of the input shaft, and therefore the stopping of the vehicle. The pawl is mounted fixed in rotation on a static support, such as the housing of the gear mechanism.

[005] During the intervention of the locking mechanism, all the inertia of the vehicle can take over the inertia of the rotor of the electric machine. All the inertia formed by the electrical machine is also transmitted through the gears and their bearings. Overtorques can be generated and damage these gears and the associated bearings. [006] To avoid these drawbacks, it is known to increase the dimensions of the gears and the associated bearings. However, such an increase in dimensions leads to an increase in the volume occupied by the gear mechanism.

[007] The object of the invention is to improve the electrical drive devices of a vehicle axle of the prior art by proposing a device whose energy from the overtorques caused by the use of the parking brake is dissipated without increasing of the volume occupied by the gear mechanism.

[008] The invention aims to solve this problem and to this end, the invention relates to an electric drive device for a vehicle axle, comprising

- a rotor of an electric machine with an input shaft,

- a vehicle drive shaft,

- a transmission gear mechanism disposed between the input shaft and the drive shaft, the gear mechanism comprising at least one meshing element, and

- a parking brake device with a locking wheel, the locking wheel being capable of cooperating with one of the drive shaft, the input shaft or the meshing element, in which the drive device comprises a torque limiter disposed between the input shaft and the drive shaft, the torque limiter cooperating with the locking wheel.

[009] Thus, thanks to the invention, the forces generated by the inertia of the electric motor, among other things, will be largely dissipated by the friction generated by the torque limiter. The torque limiter allows the rotation of the input shaft to be progressively stopped, allowing the forces generated by the inertia of the electric motor to be absorbed over time.

[010] Preferably, the torque limiter is a separate mechanical device from the electrical machine.

[011] Preferably, the copy limiter is arranged kinematically between the input shaft and the drive shaft.

[012] In a preferred example, the locking wheel cooperates with the input shaft and the torque limiter is arranged between the locking wheel and the input shaft.

[013] In a preferred example, the gear mechanism may be a speed reducer associated or not with a differential.

[014] Alternatively, the locking wheel could cooperate with a differential housing and the torque limiter.

[015] Preferably, the torque limiter is a friction limiter.

[016] In one embodiment of the invention, the torque limiter comprises a friction disc and an elastic member, the friction disc being mounted bearing against the wheel blocking while being integral in rotation with one of the input shaft, the drive shaft and the meshing element, and the elastic member being mounted in abutment, on the one hand, against one among respectively the input shaft, the drive shaft and the meshing element, and against the friction disc, on the other hand. Preferably, the locking wheel is integral in rotation with the input shaft and the elastic member is mounted bearing against the input shaft and the friction disc. More specifically, the locking wheel is fixed in rotation to the input shaft via the torque limiter below the triggering torque of the torque limiter, and the elastic member is mounted bearing against the shaft inlet and the friction disc. Thus the elastic member presses the friction disc against the locking wheel.

[017] In one embodiment of the invention, the locking wheel is adapted to cooperate with one of the drive shaft, the input shaft or the frictional meshing element. In one example, the locking wheel could cooperate with a shaft of a second reduction stage or intermediate shaft.

[018] In one embodiment of the invention, the locking wheel comprises a first friction surface and one of the drive shaft, the input shaft or the meshing element comprises a second friction surface, the first surface and the second surface each forming a frustoconical surface. In particular, the first surface and the second surface are each part of a frustoconical cylindrical.

[019] In one embodiment of the invention, the elastic member is formed by a Belleville washer or by a helical spring.

[020] In one embodiment of the invention, the friction disc is mounted fixed in rotation around the input shaft and bearing against the locking wheel, the elastic member being mounted bearing against the disc friction and against a stop formed by the input shaft. In particular, the friction disc comprises at least a first fixing means and the input shaft comprises at least a second fixing means, the friction disc and the input shaft being fixed in rotation with one the other by joint cooperation of the first fixing means and the second fixing means with each other. In one example, the first fixing means forms a protuberance and the second fixing means forms a recess, the recess possibly having a shape complementary to that of the protuberance.

[021] In one embodiment of the invention, the abutment is formed by a circlip mounted tightly around the input shaft.

[022] In one embodiment of the invention, the friction disc is mounted around the meshing element and bears against the locking wheel, the elastic member being mounted bears against the friction disc and against an abutment formed by the element gearing. In one example, the gear mechanism includes a speed reducer comprising two reduction stages and a differential. The meshing element can be a toothed wheel of the gear reducer or else a differential case.

[023] In another of its aspects, the invention also relates to an electric drive device for a vehicle axle, comprising

[024] - a rotor of an electric machine with an input shaft,

[025] - a vehicle drive shaft,

[026] - a transmission gear mechanism disposed between the input shaft and the drive shaft, the gear mechanism comprising at least one meshing element, and

[027] - a parking brake device with a locking wheel, in which

[028] - the locking wheel being connected in rotation with one of the drive shaft, the input shaft or the meshing element, in which the locking wheel and one of the the drive shaft, the input shaft and the meshing element cooperate with each other by gearing, and in which

[029] - the drive device also comprises at least one elastic element interposed between the locking wheel and one of the drive shaft, the input shaft and the meshing element, the elastic element being positioned and configured in such a way as to generate an elastic rotational torque when the parking brake is actuated.

[030] In one embodiment of the invention, a hub is interposed between the locking wheel and the input shaft, the hub being connected in rotation to the locking wheel and to the input shaft, the elastic element being positioned between the locking wheel and the hub or between the hub and the input shaft.

[031] In one embodiment of the invention, the locking wheel and the hub cooperating with each other by axial connecting means, the elastic element being interposed between these axial connecting means

[032] In one embodiment of the invention, the elastic element forms a cylinder extending axially along an axis of rotation of the input shaft.

[033] In one embodiment of the invention, the axial connecting means are formed by protrusions and housings, the locking wheel and the hub cooperating with each other by axial insertion of the protrusions into the corresponding housings .

[034] In one embodiment of the invention, the protuberances are formed by the locking wheel or by the hub and the housings are formed respectively by the hub or by the locking wheel.

[035] In one embodiment of the invention, the protrusions extend axially from a ring and over at least a portion of a periphery of the ring. In a example, the locking wheel forms a ring and protrusions are formed from this ring, the protrusions extending axially along the axis of rotation of the input shaft from a face of the ring .

[036] In one embodiment of the invention, the housings are formed radially in the direction of the axis of rotation of the input shaft and from a hollow cylinder over at least part of a periphery. of the cylinder. In a preferred example, the hub forms a hollow cylinder and the housings are hollowed radially towards the axis of rotation of the input shaft and from a face of the cylinder which fits into the contour of the cylinder.

[037] In one embodiment of the invention, the hub forms at least a portion comprising two side edges and the locking wheel forms at least one protrusion comprising two side faces, the locking wheel and the hub cooperating with one the other by inserting the protuberance into the associated housing, the elastic element being wedged between a lateral face of the protuberance and a lateral edge of the portion of the hub.

[038] In a preferred example, the elastic element forms an elastic bead.

[039] The elastic element has a circumferential action and acts as a torsional shock absorber.

[040] The invention will be better understood on reading the following description and on examining the accompanying figures. These figures are given only by way of illustration but in no way limit the invention.

[041] [Figure 1] shows a cross section of an electric drive device for an axle of a vehicle, according to a first embodiment of the invention;

[042] The [Figure 2] illustrates an exploded part of the drive device, according to [Figure 1];

[043] [Figure 3] illustrates an electric drive device for an axle of a vehicle, according to a second embodiment of the invention;

[044] [Figure 4a] illustrates a longitudinal section of part of an electric drive device for an axle of a vehicle, according to another aspect of the invention;

[045] [Figure 4b] illustrates a cross section of the drive device of the device of Figure 4a according to an A-A section, and

[046] [Figure 4c] illustrates an exploded view of the drive device of [figure 4a],

[047] For reasons of simplification, similar elements have the same references from one figure to another.

[048] The [Figure 1] and [Figure 2] show an electric drive device 1 of a vehicle axle, comprising a rotor 2 of an electric machine 3 with an input shaft 4. The device drive 1 also includes a drive shaft of the vehicle (not shown), a gear reducer 5 arranged between the input shaft 4 and the drive shaft. The drive shaft can connect the gear reducer 5 to the wheels (not shown) of the vehicle. The input shaft 4 is connected in rotation to the rotor by one end and cooperates by gear by another opposite end with the speed reducer 5.

[049] The drive device 1 also comprises a parking brake device 9 housed in a housing 23 of the speed reducer 5. The parking brake device 9 comprises a locking wheel 10 which is capable of cooperating with the shaft input 4 for a rotating connection.

[050] In particular, this locking wheel 10 is arranged around the input shaft 4. The locking wheel 10 forms a ring whose inner periphery has a first friction surface 11 of frustoconical shape. The input shaft 3 comprises in correspondence on an outer periphery a second friction surface 12 of shape complementary to that of the first friction surface 11 . In particular, the second friction surface 12 is also of frustoconical shape. The locking wheel 10 and the input shaft 4 are connected in rotation with each other by cooperation of the first friction surface 11 with the second friction surface 12.

[051] The locking wheel 10 has on an outer periphery grooves such as 13. These grooves 13 are made parallel to an axis of rotation X of the input shaft 4. In this example, the grooves 13 are arranged at equidistant from each other. These grooves 13 are adapted to receive a pawl (not shown in Figure 1 and Figure 2 but shown in Figure 3 at 14) of a locking mechanism (not shown in Figure 1 and Figure 2 but shown in Figure 3 at 15) of the lock 10. In this example, the axis of rotation X of the input shaft 4 is coaxial with an axis of rotation of the electric machine 3.

[052] According to a preferred embodiment of the invention, the drive device 1 comprises a torque limiter 17. In this example, the torque limiter 17 is arranged around the input shaft 4. The torque limiter 17 is configured to cooperate with the locking wheel 10. In particular, the torque limiter 17 comprises a friction disc 18 mounted to bear against the locking wheel 10 while being integral in rotation with the input shaft 4. Indeed, the friction disc 18 comprises a protrusion 19 capable of coming to be positioned by form complementarity opposite a recess 20 formed by the input shaft 4. The torque limiter 17 also comprises a Belleville washer 21 positioned around the input shaft 4 while being mounted bearing against the locking wheel 10 on one side and against a stop 22 formed by the input shaft 4 on the other side. The stop 22 may be a circlip mounted inside a circumferential groove 25 formed by the input shaft 4 around the axis of rotation X Or in another example not illustrated, the stop 22 could be formed by another circlip mounted tight around the input shaft

4.

[053] The speed reducer 5 comprises a first reduction stage 6 and a second reduction stage 7. In this example, the input shaft 4 cooperates with the first reduction stage 6. The speed reducer 5 can be associated with a differential (not shown in Figures 1 and 2 but shown at 8 in Figure 3).

[054] A first bearing and a second bearing such as 24 are arranged around the input shaft 4 while being connected to the input shaft 4 and to the housing 23 of the gear device 5. Between these two bearings 24 are arranged the locking wheel 10 as well as the torque limiter 17.

[055] In operation, as long as the electric motor 3 is running, the locking wheel 10 is permanently driven in rotation by the input shaft 4. When the parking brake device 9 is put in place, the locking wheel 10 is locked in rotation, which causes a stop in rotation of the input shaft 4. Via the torque limiter 17, this stop in rotation of the input shaft 4 is achieved gradually . Indeed, the friction disc 18 positioned in abutment against the locking wheel 10 while being connected in rotation to the input shaft 4, will allow the input shaft 4 to stop more progressively. stop in rotation of the locking wheel 10. This progressive stop will be carried out by disengaging the locking wheel 10 with respect to the input shaft 4, the time to evacuate the overtorque generated by this stop in rotation.

[056] Figure 3 also illustrates a drive device 100 according to a second embodiment of the invention. In this figure, one can observe the presence of a locking mechanism 15 which comprises a pivot axis 16 mounted fixed in rotation on the casing 23 of the speed reducer 5. On this pivot 16 is mounted a pawl 14 which is capable of rotating around this same pivot 16 in order to fit into one of the grooves 13 under the action of a locking control (not shown). By fitting into one of the grooves 13, the pawl 14 causes the locking wheel 10 to stop rotating relative to the casing 23 and relative to the input shaft 4.

[057] In this figure, one can also observe a first gear stage 6 and a second gear stage 7 as well as the presence of an axle differential 8. The differential 8 comprises a housing 26 which is driven by an output pinion of the second gear stage 7. Each of the gear stages comprises at least one pinion and one toothed wheel, the pinion and the toothed wheel cooperating with each other to transmit a torque.

[058] In a variant not shown, the locking wheel 10 could be mounted around the housing 26 of the differential 8. [059] Figure 4a, Figure 4b and Figure 4c illustrate a training device 200 according to another aspect of the invention. According to this other aspect, the drive device also comprises at least one elastic bead 27 interposed between the locking wheel 10 and the input shaft 4. In this example, the elastic bead 27 is shown in an elongated cylindrical shape with a circular. But the elastic bead 27 could be of any other spherical or cube shape. The elastic bead 27 is positioned and configured in such a way as to generate an elastic rotational torque when the parking brake represented in FIG. 4a, FIG. 4b and FIG. 4c is actuated by the locking wheel 10.

[060] A hub 28 is interposed between the locking wheel 10 and the input shaft 4. The hub 28 is connected in rotation to the locking wheel 10 and to the input shaft 4 by gearing of the with each other. The elastic bead 27 is positioned between the locking wheel 10 and the hub 28.

[061] The locking wheel 10 includes protrusions 29 (visible in FIG. 4b and FIG. 4c) which extend axially from a ring 30 and over at least part of a periphery of the ring 30. The protrusions 29 extend axially along the axis of rotation X of the input shaft 4.

[062] The hub 28 forms housings 31 in correspondence of the protrusions 29. Each of the housings 31 is formed radially in the direction of the axis of rotation X of the input shaft 4 and from a hollow cylinder on the least part of a periphery of the cylinder. The housings 31 are hollowed out radially towards the axis of rotation X and from a face of the cylinder which fits into the contour of the cylinder.

[063] Each of the housings 31 of the hub 28 forms two side edges such as 32 and the protrusion 29 of the locking wheel 10 forms two side faces such as 33. The hub 28 and the locking wheel 10 cooperate with one another. another by inserting the protuberance 29 into the associated housing 31, the elastic bead 27 being wedged between an edge 32 of the portion of the hub 28 and a side face 33 of the protuberance 29.

[064] The hub 28 has an axial cylindrical portion 35 intended to be positioned radially between the locking wheel 10 which includes the grooves 13 and the input shaft 4. The housings 31 are made on another cylindrical portion 36 of the hub 28 which is partially covered by the protuberances 29 of the locking wheel 10.

[065] To retain the locking wheel 10 axially on the input shaft 4, a circlip 34 is provided and which is housed on the input shaft 4.

Claims

[Claim 1] Electric drive device (1) of a vehicle axle, comprising

- a rotor (2) of an electric machine (3) with an input shaft (4),

- a vehicle drive shaft,

- a transmission gear mechanism (5) arranged between the input shaft and the drive shaft, the gear mechanism comprising at least one meshing element, and

- a parking brake device (9) with a locking wheel (10), the locking wheel being capable of cooperating with one of the drive shaft, the input shaft or the damper element meshing, in which the drive device comprises a torque limiter (17) disposed between the input shaft and the drive shaft, the torque limiter cooperating with the locking wheel.

[Claim 2] Device according to Claim 1, in which the torque limiter comprises a friction disc (18) and an elastic member (21), the friction disc being mounted in abutment against the locking wheel while being integral in rotation of one of the input shaft, the drive shaft and the meshing element, and the elastic member being mounted in abutment, on the one hand, against one of respectively the shaft input, the drive shaft and the meshing element, and against the friction disc, on the other hand.

[Claim 3] Device according to claim 1 or 2, in which the locking wheel is adapted to cooperate with one of the drive shaft, the input shaft or the frictional meshing element.

[Claim 4] Device according to claim 3, in which the locking wheel comprises a first friction surface (11) and one of the drive shaft, the input shaft or the meshing element has a second friction surface (12), the first surface and the second surface each forming a frustoconical surface.

[Claim 5] Device according to one of Claims 2 to 4, in which the elastic member is formed by a Belleville washer or by a helical spring.

[Claim 6] Device according to one of Claims 2 to 5, in which the friction disc is mounted fixed in rotation around the input shaft and bears against the locking wheel, the elastic member being mounted in bearing against the friction disc and against a stop (22) formed by the input shaft.

[Claim 7] Device according to claim 6, in which the abutment is formed by a circlip tightly mounted around the input shaft.

[Claim 8] Device according to one of Claims 2 to 7, in which the friction disc comprises at least one first fixing means and the input shaft comprises at least one second fixing means, the friction disc and the input shaft being fbés in rotation with each other by joint cooperation of the first fixing means and the second fixing means with each other.

[Claim 9] Device according to claim 8, in which the first fixing means forms a protuberance and the second fixing means forms a recess.

[Claim 10] Device according to one of Claims 2 to 5, in which the friction disc is mounted around the meshing element and bears against the locking wheel, the elastic member being mounted bears against the friction disc and against a stop formed by the meshing element.

[Claim 11] Device according to one of the preceding claims, in which the torque limiter is a separate mechanical device from the electrical machine.