FR3034585A1 - CONNECTION BETWEEN AN ELECTRIC MACHINE SHAFT AND A REDUCER - Google Patents

Abstract

Connection between a shaft (11) of an electric machine (10), in particular a motor, and a pinion (30) of a gearbox (20) coupled to the machine, characterized in that the pinion has a bore conical (31) engaged on the shaft and comprises a shank (33) engaged in a bearing (23) of the reducer.

Description

The present invention relates to electromechanical assemblies comprising an electric machine and a reducer coupled to the machine. The invention relates more particularly, but not exclusively, to electromechanical assemblies in which the electric machine is a motor, in particular for an automobile traction application. The connection between the motor and the gearbox is a source of vibration, which causes noise, which should be reduced to a minimum. In the prior art there are different modes of connection between a shaft and a pinion.

A first solution, illustrated in Figure 1, is not to bring coins, but to have a shaft 1 in which is cut the teeth of pinion 2, also called "pinion tree". This solution has two disadvantages. First, the material of the tree is generally a steel with high mechanical properties, expensive. Making the gear teeth monolithically with the shaft increases the cost of wear of the machining equipment. Then, the front bearing of the engine must provide an oil seal function. Therefore, the engine has a seal 3 which must, to allow the establishment of the shaft, have an inner diameter greater than the outer diameter of the pinion. However, it is problematic to ensure a seal on a large diameter, because the speed of contact increases with the radius, and it must not exceed a limit speed of operation under penalty of excessive heating of the seal. Another way of connection between pinion and shaft, illustrated in Figure 2, is to fret a pinion tail 4 in the shaft 1; this arrangement alleviates the problem of cost of material, allowing the use of two different materials for the pinion and the shaft. However, it does not solve the aforementioned high-speed sealing problem because the shaft and the pinion are assembled before assembly of the assembly in the rest of the electrical machine. In addition, to ensure sufficient torque transmission, it is necessary to have an adequate length of recovery between the tail of the pinion and the shaft, which tends to increase the overall size of the assembly.

Another solution, illustrated in Figure 3, is to use a hollow pinion 2, which is attached to the shaft 1 after mounting the seal 3 and the front bearing 5 of the machine. The torque resistance of the pinion on the shaft is then ensured by axial clamping of a screw 6 fixed at the end of the shaft.

A disadvantage of such a solution is that the torque resistance of the pinion on the shaft, ensured by the tightening of the screw, is relatively limited. There is therefore a need to further improve the connection between an electric machine and an associated reducer, in particular for the purpose of minimizing the vibrations generated during the operation of the electromechanical assembly 10 thus formed, while allowing operation to high rotational speeds, for example of the order of 10000 to 18000 rpm. The invention achieves this objective by virtue of a connection between a shaft of an electric machine, in particular a motor, and a gear of a gearbox coupled to the machine, which is characterized by the fact that the pinion has a conical bore engaged on the shaft and comprises a shank engaged in a bearing of the gearbox. The invention has many advantages. First, it allows to mount the pinion on the shaft already equipped with the front bearing and the seal, and allows a high torque transmission, the shaft of the machine does not remain in cantilever thanks to the gearbox bearing.

Thus, the inner diameter of the seal of the machine can be relatively small, which allows operation at high rotational speeds. In addition, the tapered bore ensures a high torque recovery. Finally, machining on the same part formed by the pinion both the conical bore and the surface engaged in the bearing reduces concentricity defects in the manufacture and makes it possible to minimize the eccentricity defects, sources of vibrations and noise. Preferably, the tail of the pinion defines the rolling surface for rolling the gearbox. Also preferably, the pinion is traversed axially by an axial element 30 useful for its attachment to the shaft. This axial element is for example a screw fixed at the end of the shaft, or alternatively a threaded part monobloc with the shaft, the fixing then being carried out with the aid of a nut screwed thereon. Thus, the pinion can be axially constrained on the shaft so as to obtain the desired torque transmission. The tail of the pinion can be traversed by a cylindrical bore, in which the aforementioned axial element extends.

The subject of the invention is also an electromechanical assembly comprising a machine coupled to a gearbox, the transmission of the torque between the gearbox and the machine being effected by means of a connection according to the invention, as defined above. . The invention also relates to a vehicle equipped with such an electromechanical assembly.

The invention also relates to a method of mounting a gearbox on an electric machine, to form a connection according to the invention, in which process the pinion is fixed on the shaft of the engine pre-equipped with a bearing. and a seal, then the shaft thus equipped is engaged in the reducer. The invention further relates to a method of manufacturing a connection according to the invention, wherein the conical bore and the part engaged in the bearing are machined on the same machine, so as to reduce the eccentricity defects. . The invention will be better understood on reading the detailed description which follows, and on examining the appended drawing, in which: FIGS. 1 to 3, previously described, illustrate the state of the art, FIG. 4 is a partial axial section of an example of an electromechanical assembly according to the invention, and FIG. 5 represents a detail of FIG. 4. FIGS. 5 and 6 show an electromechanical assembly 100 according to the invention. , comprising an electric machine 10 coupled to a gearbox 20.

In the example considered, the electric machine is an electric motor, capable of operating at a high rotational speed, in particular between 10,000 and 18,000 rpm. This electric motor is for example a traction motor of an electric or hybrid vehicle, being for example mounted centrally under the hood or directly at the hubs of the wheels. The motor 10 comprises a shaft 11 which passes through a front flange 12 carrying a bearing 13 and a seal 14.

The reducer 20 comprises a housing 21 which is fixed to a flange 15 of the front flange 12, for example by bolting. The housing 21 has an opening 28 in which the shaft 11 is engaged. The reducer 20 houses any reduction or reduction mechanism 5 suitable for the application concerned. This mechanism comprises a pinion 30, which is an input gear of the reducer in the example in question, and which meshes with other elements of the mechanism, not visible in FIGS. 5 and 6. This pinion 30 has an enlarged portion 31 on which is made the toothing 32, and a tail 33 defining a running surface 34 for a bearing 23 of the gear 20, for example a needle bearing as illustrated. The toothing 32 can be of any type, helical, straight or conical. The shaft 10 has at the end a conical bearing surface 16 and the enlarged portion 31 of the pinion has a conical bore 35 adapted to fit on the shaft end so as to allow the transmission of the torque between the shaft and the pinion, by axial clamping of the pinion 30 on the shaft 10 by means of a screw 26 screwed into the shaft and whose head 27 abuts axially on the end edge 37 of the pinion. The screw 26 passes through the pinion tail by means of a cylindrical axial bore 38 thereof. The end 17 of the shaft 10 does not bear against the shoulder 39 formed at the junction of the tapered bore 35 and the cylindrical bore 38, so as to allow an axial clamping of the pinion on the tree. The tapered bore is for example of the MORSE type allowing irreversible drive of the pinion. The force applied to the mounting permits the passage of torque, and operation in forward or reverse direction does not allow the pinion to be loosened. The taper is preferably between 5 and 10% (10% corresponds to a 1/2 angle at the top of 2 ° 5145 "), better still 10%, in order to minimize the axial positioning variation of the pinion 30 with respect to a pinion of an intermediate axis of the reducer with which it meshes and thus ensure good meshing conditions, low wear and noise at the gear.

During manufacture, the shaft 10 can be mounted through the front bearing 13 and the seal 14.

3034585 5 Then, the pinion 30 can be mounted on the shaft 10 and fixed on it by the screw 26. The shaft 10 thus provided with its pinion 30 can be engaged in the reducer 20 by the opening 28 thereof , and the fixing flange 15 of the motor flange assembled to the frame 21 of the gearbox.

The invention is not limited to the example just described. The expression "comprising one" shall be understood as being synonymous with "comprising at least one" unless the contrary is specified.

Claims (10)

REVENDICATIONS1. Connection between a shaft (11) of an electric machine (10), in particular a motor, and a pinion (30) of a gearbox (20) coupled to the machine, characterized in that the pinion has a bore conical (31) engaged on the shaft and comprises a shank (33) engaged in a bearing (23) of the reducer. 2. Link according to claim 1, the tail (33) of the pinion defining the running surface (23) for rolling gear reducer. 3. Connection according to claim 1 or 2, the pinion being traversed axially by an axial member (26) useful for its attachment to the shaft. 4. Link according to claim 3, the axial element being a screw (26) fixed at the end of the shaft. 5. Connection according to claim 3 or 4, the tail of the pinion being traversed by a cylindrical bore, wherein extends the axial element (26) above. 6. Connection according to any one of the preceding claims, the taper of the conical bore being 10%. 7. Connection according to any one of claims 1 to 6, the conical bore (31) having been machined on the same machine as a surface (23) of the tail of the pinion engaged in the bearing. 8. An electromechanical assembly comprising a machine coupled to a gearbox, the transmission of torque between the gearbox and the machine being effected by means of a connection according to the invention, as defined in any one of claims 1 to 7. . 9. Vehicle equipped with an electromechanical assembly according to claim 8. 10. A method of mounting a reducer on an electric machine, to form a connection as defined in any one of claims 1 to 7, wherein the pinion (30) is fixed on the shaft (11) of the motor pre-equipped with a bearing (13) and a seal (14), then the shaft thus equipped is engaged in the gearbox (20).