Arrangement for a geared motor including an element stiffening the rotor shaft of such a geared motor.

Abstract

Arrangement for a geared motor comprising an element stiffening the rotor shaft of such a geared motor. The invention relates to an arrangement (2) for a geared motor, comprising a housing (4), a shaft (10) arranged at least partially within the housing (4), a bearing (5) arranged between the housing (4) and the shaft (10), the bearing (5) supporting at least partially the rotating shaft (10), a rotor (6) of such a geared motor, the rotor (6) being fixed on the shaft (10) and extending within the housing (4), a space (E) extending around the shaft (10) between the bearing (5) and the rotor (6), the arrangement (2) comprising an element (20) fixed on the shaft (10) within the space (E) so as to stiffen the shaft (10), particularly in terms of bending. Figure for the summary: Figure 3

Description

Title of the invention: Arrangement for a geared motor comprising an element stiffening the rotor shaft of such a geared motor. Technical field of the invention

[0001] The invention relates to an arrangement for a geared motor comprising an element that stiffens the shaft supporting the rotor of the geared motor. The invention further relates to a geared motor comprising such an arrangement. The invention also relates to a vehicle, in particular a motor vehicle, comprising such a geared motor or such an arrangement. Prior art

[0002] A hybrid or electric vehicle generally includes a geared motor generating torque for traction and / or propulsion. Such a geared motor generally includes a shaft supporting a rotor. This shaft includes an output pinion for transmitting this torque. This pinion is generally arranged at the end of the shaft, the shaft being held in rotation by two bearings relative to a housing. This output pinion generally has helical teeth.

[0003] Only such helical teeth generate a force that causes such a shaft to flex, particularly between the two bearings. This shaft flex affects the quality of the meshing with the output pinion. The result is premature wear of the helical teeth. Furthermore, this wear reduces the transmission's efficiency and / or generates noise, which is unacceptable for an electric or hybrid vehicle.

[0004] Such a situation is not acceptable. Presentation of the invention

[0005] The object of the invention is to provide an arrangement for a geared motor that remedies the above disadvantages.

[0006] More specifically, an object of the invention is to provide a geared motor offering excellent efficiency and a long service life, while being quiet. Summary of the invention

[0007] To achieve this objective, the invention relates to an arrangement for a geared motor, in particular a geared motor for towing and / or propelling a vehicle, comprising: - a housing, - a shaft arranged at least partially within the casing, - a bearing arranged between the housing and the shaft, the bearing supporting at least partially the rotating shaft, - a rotor of such a geared motor, the rotor being fixed to the shaft and extending within the housing, - a space extending around the shaft between the bearing and the rotor, the arrangement including an element fixed to the shaft within the space so as to stiffen the shaft, particularly in terms of bending.

[0008] The element may be cylindrical or substantially cylindrical.

[0009] The element may include a first bore arranged next to the bearing and the shaft may include a first portion, the first bore of the element being able to come into contact with the first portion of the shaft.

[0010] The first bore of the element can be shrink-fitted onto the first portion of the shaft.

[0011] The first bore of the element may include internal splines and the The first portion of the tree may include external grooves, with internal grooves cooperating with the external grooves.

[0012] The element may include a second bore arranged next to the rotor, the second bore being able to be of a larger diameter than the first bore, and the shaft may include a second portion for mounting the rotor, in particular a second portion comprising external grooves parallel to the axis of the shaft, the second bore being able to be shrink-fitted at least over a portion of the axial length of the second portion.

[0013] The second portion of the shaft may include a frustoconical portion so as to facilitate the mounting of the rotor.

[0014] The element may include radial extensions.

[0015] The invention further relates to a geared motor, in particular intended to tow and / or propel a vehicle, comprising an arrangement as defined above.

[0016] The invention further relates to a vehicle, in particular a motor vehicle, comprising an arrangement as defined above, or a geared motor as defined above. Presentation of the figures

[0017] These objects, features and advantages of the present invention will be described in detail in the following description of a particular embodiment, given by way of non-limiting example, with reference to the accompanying figures, among which:

[0018] Fig. 1 is a schematic profile view of a motor vehicle according to an embodiment of the invention.

[0019] Fig. 2 is a partial cross-sectional view of a geared motor according to an embodiment of the invention, the cutting plane passing through the axis of the shaft of the geared motor.

[0020] Fig. 3 is a detailed cross-sectional view of the geared motor comprising a stiffening element for the shaft of the geared motor according to a first embodiment of the invention, the cutting plane passing through the axis of the shaft of the geared motor.

[0021] Fig. 4 is a detailed cross-sectional view of the geared motor comprising a stiffening element for the shaft of the geared motor according to a second embodiment of the invention, the cutting plane passing through the axis of the shaft of the geared motor.

[0022] Fig. 5 is a perspective view of the stiffening element of the geared motor shaft according to an embodiment of the invention.

[0023] Fig. 6 is a partial perspective view of the geared motor according to the embodiment of the invention, without a shaft stiffening element.

[0024] Figure 7 is another partial perspective view of the geared motor according to the embodiment of the invention, with the shaft stiffening element. Detailed description

[0025] Figure 1 schematically illustrates a vehicle 1, preferably a motor vehicle. Vehicle 1 may be a passenger car or a commercial vehicle. Alternatively, it could be a truck, a bus, a lifting machine, an agricultural machine, or even any other type of land vehicle, such as a two-wheeler. Vehicle 1 is advantageously hybrid or electric. Vehicle 1 includes a geared motor 3. A geared motor is understood to be, in particular, an electrical machine powered by an electric current and capable of providing torque to move vehicle 1. The torque output from the geared motor 3 is preferably intended to drive at least one front wheel (traction) and / or at least one rear wheel (propulsion).

[0026] The vehicle 1, or the geared motor 3, comprises at least one arrangement 2.

[0027] As illustrated in [Fig. 2], the arrangement 2 comprises a housing or casing 4. The arrangement 2 further comprises a shaft 10 arranged at least partially within the housing 4. Preferably, the shaft 10 passes through the housing 4, protruding on either side of the housing 4, as illustrated in [Fig. 2]. The arrangement 2 further comprises a bearing 5 arranged between the housing 4 and the shaft 10. The bearing 5 supports the shaft 10 in rotation, at least partially. Advantageously, the housing 4 comprises another bearing 7 so as to connect the shaft 10 to the housing 4 via a pivot joint, supported by the two bearings 5 ​​and 7. Preferably, the two bearings 5 ​​and 7 are arranged near the two ends of the shaft 10.

[0028] The arrangement 2 further includes a rotor 6 for the geared motor 3. The rotor 6 is fixed on the shaft 10 and extends within the housing 4 between the two bearings 5, 7. Advantageously, the rotor 6 includes stacks and the method of fixing the rotor 6 to the shaft 10 is shrink fitting.

[0029] For example, at least one bearing, or even both bearings 5,7, are ball bearings, or roller bearings, or needle bearings so as to limit the friction related to the rotation of the shaft 10.

[0030] The arrangement 2 further includes a space E extending around the shaft 10. More precisely, the space E extends along the axial direction of the shaft 10 between the bearing 5 and the rotor 6, as illustrated in Figures 2, 3 and 4.

[0031] The arrangement 2 further includes a stiffening element 20 fixed to the shaft 10 and extending into space E. Advantageously, the sole function of mounting the element 20 on the shaft 10 is to stiffen the shaft 10, to increase the shaft's rigidity, and in particular to limit the deflections of the shaft 10 due to the meshing of a drive pinion 8, preferably helical, arranged at the end of the shaft. Preferably, particularly for balancing purposes, the element 20 is cylindrical or substantially cylindrical.

[0032] According to a first embodiment, as illustrated in [Fig. 3], the element 20 comprises a first bore 21 arranged so as to be located next to, near, the bearing 5 after assembly. The shaft 10 comprises a first cylindrical or substantially cylindrical portion 11. The first bore 21 of the element 20 comes into contact with the first portion 11 of the shaft 10. Preferably, the first bore 21 of the element 20 is press-fitted onto the first portion 11 of the shaft 10.

[0033] Advantageously, as illustrated in Figures 3 and 5, the first bore 21 of the element 20 includes internal splines 25. The first portion 11 of the shaft 10 then includes external splines 15. Thus, the internal splines 25 formed in the first bore 21 of the element 20 cooperate with the external splines 15 formed in the first cylindrical portion 11 of the shaft 10. Advantageously, the splines 15, 25 combine with the shrink fit, complement the shrink fit, to ensure reliable and durable retention of the element 20 on the shaft 10.

[0034] The element 20 comprises a second bore 22 arranged so as to be located next to, or near, the rotor 6 of the geared motor 3 after assembly. The second bore 22 preferably has a larger diameter than the diameter of the first bore 21. The shaft 10 comprises a second cylindrical portion 12 for mounting the rotor 6. Advantageously, as illustrated in Figures 6 and 7, the second portion 12 comprises external grooves 13 parallel to the axis A of the shaft 10. The second bore 22 is shrink-fitted onto at least a portion L12 of the axial length of the second cylindrical or substantially cylindrical portion 12. Advantageously, the portion having an axial length L12 of the shaft 10 extends outside an internal volume V of the rotor 6, as illustrated in [Fig. 3].

[0035] Optionally, the second portion 12 includes a frustoconical portion 17, in particular extending over the axial length L12 of the shaft 10. This facilitates the passage of the rotor onto the beginning of this second portion 12 before shrink-fitting the rotor 6 further along the shaft 10. Thus, the rotor is first inserted around the first portion 11 of the shaft 10 before being translated onto the frustoconical portion 17, if necessary, and then onto the remainder of the second portion 12. In this case, the small diameter of the frustoconical portion 17 is on the bearing side 5 and the large diameter of the frustoconical portion 17 is on the rotor side 6. Preferably, the large diameter of the frustoconical portion 17 is equal to, or substantially equal to, the diameter of a receiving portion 16 of the rotor. As illustrated in [Fig.3], the rotor 6 is fixed, preferably by shrink fitting, onto the receiving part 16 of the shaft 10.

[0036] Note that the shaft 10 includes a shoulder 14 at the point of the difference in diameters between the first portion 11 and the second portion 12, as illustrated in figures 3 and 6.

[0037] According to a second embodiment illustrated in [Fig. 4], the element 20 also includes the first bore 21 arranged so as to be located next to, near, the bearing 5 after assembly. The first bore 21 of the element 20 comes into contact with the first portion 11 of the shaft 10. Preferably, the first bore 21 of the element 20 is shrink-fitted, that is, press-fitted, onto the first portion 11 of the shaft 10.

[0038] Advantageously, as illustrated in Figures 4 and 5, the first bore 21 of the element 20 includes the internal splines 25. The first portion 11 of the shaft 10 includes the external splines 15. Thus, the internal splines 25 formed in the first bore 21 of the element 20 cooperate with the external splines 15 formed in the first cylindrical portion 11 of the shaft 10. Advantageously, the splines 15, 25 combine with the shrink fit, complementing the shrink fit, to ensure reliable and durable retention of the element 20 on the shaft 10.

[0039] Element 20 of the second embodiment also includes the second bore 22 arranged so as to be located next to, or near, the rotor 6 of the geared motor 3 after assembly. The second bore 22 preferably has a larger diameter than the diameter of the first bore 21. The second bore 22 is shrink-fitted onto at least the portion L12 of the axial length of the second cylindrical or substantially cylindrical portion 12. Advantageously, the portion having an axial length L12 of the shaft 10 extends outside the internal volume V of the rotor 6, as illustrated in [Fig. 4].

[0040] In particular, according to the second embodiment of element 20, illustrated in [Fig. 4], element 20 comprises a third bore 26, of the counterbore, recess, or groove type, between the first and second bores 21, 22. The third bore 26 is preferably of a larger diameter than each of the first and second bores. 21, 22. In particular, the third bore 26 facilitates the manufacture of the reinforcing element 20 by allowing tool clearances, useful, for example, for obtaining the internal splines 25. The axial lengths L21 and L22, respectively of the first bore 21 and the second bore 22, present at each end of the element 20 or retainer, enable the function of the element 20, namely preventing bending of the shaft 10. These lengths L21, L22, locally reduced compared to the first embodiment without the counterbore 26, also allow for limiting the insertion force without reducing the target shaft stiffness. For example, the length L21 of the first bore 21, advantageously splined, is between 5 mm and 15 mm, or even between 8 mm and 12 mm. This length is sufficient, even if there is a need to transmit torque through 23 teeth.

[0041] Indeed, possibly, as illustrated in figures 3 and 4, the element 20 includes external teeth or radial extensions 23, for example at the level of the first bore along the axial direction.

[0042] The solution makes it possible to increase the rigidity, the stiffness of the shaft 10 of the geared motor without modification of the bearings 5, 7 and the housing 4.

[0043] Indeed, the reinforcing element 20 limits the deflection of the shaft 10, particularly in the case of a powertrain comprising the geared motor 3 equipped with the output pinion 8 at the end of the shaft 10. This deflection is specifically reduced or even eliminated between the two bearings 5 ​​and 7. In the case of a helical pinion 8 generating significant forces at the end of the shaft, the stiffening element 20 prevents the bending, also known as "skew," resulting from such forces. It should be noted that these forces are, for example, simultaneously radial and axial. The solution does not generate any additional friction, so the efficiency of the geared motor is not affected.

[0044] By avoiding such deflections of the shaft 10, any degradation of the pinion 8 and / or the gear cooperating with this pinion 8 is prevented, along with any resulting noise. In other words, the teeth of this gear are preserved over time, which extends its service life and / or reduces the maintenance required.

[0045] The solution does not affect the rotor, the housing, or the bearings. Regarding the shaft, only splines 15, if applicable, and / or diameter differences between portion 11 and portion 12, are required in terms of modifications. Therefore, standard components are compatible with the solution, making it very economical.

[0046] Preferably, the material used for the stiffening element 20 is steel in order to provide maximum stiffness and to be compatible with shrink fitting.

[0047] For example, the thickness E20 of the element 20, along the radial direction, illustrated in Figures 3 and 4, is between 1 mm and 5 mm, or even between 2 mm and 4 mm, preferably on the order of 3 mm in order to provide substantial stiffness without, however, requiring excessive stress for shrink fitting. Although the thickness E20 is As illustrated at the second bore 22, this thickness E20 can also be substantially valid at the first bore 21. Indeed, the diameter difference between the first and second bores can be small. This resulting increase in shaft thickness allows the desired deflection limit to be achieved. The length L20, along the axial direction, of the sleeve 20 is, for example, between 20 mm and 80 mm, for example, on the order of 50 mm. Advantageously, the length of the sleeve 20 is maximized relative to the available space E between the bearing 5 and the rotor 6.

[0048] The stiffening element 20 of the shaft 10, in particular its thickness E20 in the radial direction, therefore contributes to the stiffness of the part of the shaft 10 supporting the rotor 6. Note that the shaft 10 is cantilevered between the bearing 5 and the active parts of the rotor 6.

[0049] As a reminder, in order for the element 20 to contribute to the maximum increase in the stiffness of the shaft 10, the second bore 22 is shrink-fitted onto the drive shaft 10.

[0050] As previously seen, the rotor shaft 10 has external grooves 13 extending parallel to the axis A of the shaft, for example, four of them. These grooves 13 allow for the shrink-fitting and press-fitting of the active parts of the rotor 6, preferably stacked-type active parts. The solution is compatible with these grooves 13, which preferably extend beyond the axial length L17 of the frustoconical portion 17 intended to facilitate the press-fitting of the rotor 6. More precisely, these grooves extend at least partially within the volume V of the rotor 6.

[0051] In particular, to allow torque to pass through any radial projections 23 of the sleeve 20, a bearing surface is provided at the first bore 21 to press-fit onto the external diameter of the outer splines 15 of the shaft. In other words, the teeth of the splines allow the torque to pass, and the crests of the spline teeth are pressed into the sleeve 20 to increase the stiffness of the shaft. For example, the press-fitting is performed with a relatively low clamping force so as to eliminate any risk of damage to the shaft 10 and / or the active parts of the rotor 6 and / or the element 20, while still allowing the sleeve 20 to absorb the primarily bending forces of the rotor shaft 10 at the two bores 21, 22.For example, the difference in diameter between the shrink-fit diameter and the shaft diameter at the shrink-fit point(s) is between 5 and 60 microns, or even between 10 and 54 microns for a smooth shaft, and between 5 and 85 microns, or even between 10 and 80 microns for splined or grooved shafts. These values ​​are given for a shaft approximately 50 mm in diameter and should be adjusted for shafts of smaller or larger diameters.

[0052] Thus, the shrink fittings do not require significant effort, which facilitates assembly in terms of the assembly process of the arrangement.

[0053] In terms of the assembly method, the components are simply fitted axially, one behind the other, along the length of the rotor shaft 10. As mentioned, the element 20 is shrink-fitted on one part on the side of the bearing 5, at the level of its splines 25 while being guided by these teeth cooperating with the splines 15, and on the other part on the side of the rotor 6, at the level of its second bore 22 over the length L12. During assembly, the insertion of element 20 onto shaft 10 continues until contact is made between an internal shoulder 24 of the sleeve 20 and a shoulder 14 formed on shaft 10. More precisely, the shoulder 24 of the stiffening ring 20 results from the difference between the second bore 22 and the first bore 21, the second bore being larger in diameter than the first bore. The shoulder 14 of shaft 10 is preferably located at the junction between the first portion 11 and the frustoconical portion 17.

[0054] Advantageously, the bearing housing 5 comprises a bearing, for example a ball bearing, whose inner ring 51 is press-fitted onto a bearing surface 18 of the shaft. For example, the inner ring 51 of the bearing bears axially against the element 20. Alternatively, the inner ring 51 of the bearing bears axially against a shoulder extending between the bearing surface 18 and the first portion 11 of the shaft 10. The output pinion 8 is advantageously mounted on splines 30, for example by being centered or substantially centered. For example, axial retention of the pinion 8 is ensured against the inner ring 51 of the bearing 5 via a shoulder 53 formed on the pinion ([Fig. 2]). Preferably, an axial locking means 9, for example of the split elastic clip type, or stop ring, cooperating with a groove formed on the shaft 10, is mounted at the end of the shaft on the side of the output pinion 8. This locking means 9 ensures an axial stop of the stack on the shaft 10.This locking means 9 and / or the groove into which it is inserted are preferably fitted to the stack on the shaft 10 comprising the inserted and press-fitted element 20, the bearing whose inner ring 51 is preferably press-fitted, and the pinion 8. In practice, after this assembly, an axial measurement is taken of the stack obtained from these three components 20, 51, 8, and from this, for example, the thickness along the axial direction of the locking means 9 is deduced in order to adjust it, possibly with a desired level of clamping force. In other words, the axial thickness of the locking means 9 acts as a shim for adjusting the stack obtained. Optionally, an axial hole communicating with a radial lubrication hole is made at the end of the shaft to lubricate the contact of the teeth of the splines 30 of the pinion 8.

[0055] The solution is particularly compact, and offers a gain in mass and consequently in cost with regard to the raw material of the shaft 10 of the geared motor.

[0056] In summary, despite the stresses exerted on the pinion 8, preferably helical (motor torque output) at the end of the shaft of the geared motor supporting the rotor 6, the shaft 10 does not It doesn't bend or flex. This solution prevents damage to the helical gear teeth and avoids the creation of an imbalance due to shaft deflection. The result is an increased service life for bearings 5 ​​and 7 in the assembly.

[0057] The solution makes it possible to increase the shaft's stiffness without increasing the shaft's material volume, in particular without increasing its diameter. The rotor's internal diameter remains unchanged, and consequently, the entire rotor undergoes no modification. The part furthest from the rotor's axis of rotation, which experiences a very high tangential velocity, is therefore unaffected.

[0058] Optionally, although the sleeve 20 has been described only on the output pinion side, it could be arranged between the rotor 6 and the bearing 7, i.e., on the other side of the rotor. Alternatively, a second sleeve could be arranged between the rotor 6 and the bearing 7, in addition to the sleeve 20 arranged between the rotor 6 and the bearing 5.

[0059] The invention is particularly suited to a vehicle, especially a motor vehicle, and can be used for a truck, bus, coach, agricultural machinery, lifting equipment, and any other motorized vehicle such as a motorcycle, for example. Furthermore, it can be adapted to any engine comprising a space between a rotor and at least one of its bearings.

Claims

Demands

1. An arrangement (2) for a geared motor (3), in particular a geared motor (3) for towing and / or propelling a vehicle (1), comprising: - a housing (4), - a shaft (10) arranged at least partially within the housing (4), - a bearing (5) arranged between the housing (4) and the shaft (10), the bearing (5) at least partially supporting the rotating shaft (10), - a rotor (6) of such a geared motor (3), the rotor (6) being fixed to the shaft (10) and extending within the housing (4), - a space (E) extending around the shaft (10) between the bearing (5) and the rotor (6), characterized in that the arrangement (2) comprises an element (20) fixed to the shaft (10) within the space (E) so as to stiffen the shaft (10), in particular in terms of bending, the element (20) comprising a first bore (21) arranged next to the bearing (5) and the shaft (10) comprising a first portion (11), the first bore (21) of the element (20) coming into contact with the first portion (11) of the shaft (10),the first bore (21) of the element (20) being shrunk onto the first portion (11) of the shaft (10), the first bore (21) of the element (20) comprising internal splines (25) and the first portion (11) of the shaft (10) comprising external splines (15), the internal splines (25) cooperating with the external splines (15).

2. Arrangement (2) according to the preceding claim, characterized in that the element (20) is cylindrical or substantially cylindrical.

3. Arrangement (2) according to any one of the preceding claims, characterized in that the element (20) comprises a second bore (22) arranged next to the rotor (6), the second bore (22) being of a larger diameter than the first bore (21), and in that the shaft (10) comprises a second portion (12) for mounting the rotor (6), in particular a second portion (12) comprising external grooves (13) parallel to the axis of the shaft (10), the second bore (22) being shrink-fitted at least over a portion (L12) of the axial length of the second portion (12).

4. Arrangement (2) according to the preceding claim, characterized in that the second portion (12) of the shaft (10) comprises a frustoconical portion (17) so as to facilitate the mounting of the rotor (6).

5. Arrangement (2) according to any one of the preceding claims, characterized in that the element (20) comprises radial extensions (23).

6. Geared motor (3), in particular intended to tow and / or propel a vehicle, characterized in that it comprises an arrangement (2) according to one of the preceding claims.

7. Vehicle, in particular motor vehicle (1), characterized in that it comprises an arrangement (2) according to any one of claims 1 to 5, or a geared motor (3) according to claim 6.

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