FR3142628A1 - Assembly for driving a splined shaft - Google Patents

Abstract

An assembly for driving a splined shaft comprises: a rotor support (20) of an electric machine (17), a sleeve (22) comprising a spline (23) for connecting to the shaft, the sleeve (22) being integral with the rotor support (20), and a guide bearing (34) of the sleeve (22) rotating around an axis of revolution of the assembly. The sleeve (22) constitutes at least one raceway for a row of rolling bodies (35) of the guide bearing (34). (Abstract figure: 1)

Description

Assembly for driving a splined shaft TECHNICAL FIELD OF THE INVENTION

The invention relates to an assembly for driving a splined shaft using an electric machine, particularly applicable to a hybrid or electric vehicle.

STATE OF THE PRIOR ART

Document FR 3 094 586 A1 describes a device for axially mounting a motor shaft of an electric machine on a transmission box input shaft, by fitting the motor shaft of the electric machine onto the transmission box input shaft. The part constituting the motor shaft also forms a support for the rotor of the electric machine, and is only guided in rotation indirectly, by a bearing which is an internal bearing in the transmission box, intended for guiding the transmission box input shaft. In this configuration, the rotor of the electric machine is axially at a distance from the guide bearing, in cantilever, which negatively affects the quality of the guidance. It is then difficult to control the air gap between the rotor and the stator of the electric machine. Furthermore, since the electric machine does not have its own guide bearing, it forms a subassembly without coherent mechanical cohesion before its assembly on the input shaft of the gearbox, which requires auxiliary parts, in particular a fusible centering ring, which are used before and during assembly.

To improve rotor guidance, document FR 2 809 880 A1 proposes positioning a guide bearing specific to the electric machine, positioned at least partially between the two axial ends of the rotor. The precision of the rotational guidance of the rotor relative to the stator of the electric machine is improved. However, the guide bearing is mounted on a splined sleeve connecting to the input shaft of the gearbox, axially at a distance from the splined connection. In operation, this splined sleeve is subject to torsional, shear and bending deformations, which tend to cause creep, i.e. progressive angular displacement, of the inner rings of the bearing relative to the sleeve. This creep causes premature wear, and therefore a loss of cohesion of the assembly, generating vibration, noise and deterioration.

The invention aims to remedy the drawbacks of the state of the art and to propose an assembly for driving a splined shaft using an electric machine, which offers good precision in guiding the rotation of the rotor of the electric machine without risk of creep or mechanical separation at the level of the guide.

To this end, according to a first aspect of the invention, an assembly is proposed for driving a splined shaft, the assembly comprising: an electric machine rotor support, a sleeve comprising a spline for connection to the shaft, the sleeve being integral with the rotor support, and a bearing for guiding the sleeve in rotation about an axis of revolution of the assembly, the sleeve constituting at least one raceway for a row of rolling bodies of the guide bearing. Since the raceway is formed directly on the sleeve and not on an attached ring, the risk of creep is eliminated.

The raceway formed by the sleeve may be an inner raceway, facing radially outward, or an outer raceway, facing radially inward. The spline of the sleeve may be facing radially outward to inward. Among these embodiments, the combination of a radially inward spline and a radially outward raceway is preferred for its compactness and its compatibility with transmission input shafts having a radially outward spline, which is the most common configuration.

• Préférentiellement, la bague de roulement rapportée sur le manchon peut être frettée sur une portée conique ou cylindrique du manchon.
• Pour favoriser un arrêt en translation de la bague rapportée à une de ses extrémités axiales, la bague rapportée peut être en butée contre un épaulement formé sur le manchon.
• Pour arrêter la bague rapportée en translation à son extrémité axiale opposée, le manchon peut comporter une collerette en appui contre une face annulaire plane d’extrémité de la bague de roulement rapportée sur le manchon. Alternativement le manchon peut comporter un filetage pour un écrou d’arrêt de la bague de roulement rapportée.

According to one embodiment, the guide bearing comprises a bearing ring attached to the sleeve to constitute an additional raceway for an additional row of rolling bodies of the guide bearing. In order to immobilize the ring in rotation relative to the sleeve and prevent creeping, one or more of the following embodiments may be provided:

• Preferably, the bearing ring attached to the sleeve can be shrunk onto a conical or cylindrical surface of the sleeve.
• To facilitate a translational stop of the attached ring at one of its axial ends, the attached ring may abut against a shoulder formed on the sleeve.
• To stop the added ring in translation at its opposite axial end, the sleeve may include a collar bearing against a flat annular end face of the bearing ring added to the sleeve. Alternatively, the sleeve may include a thread for a stop nut for the added bearing ring.

Alternatively, it is also conceivable, in order to obtain a guide bearing with two rows of rolling bodies, to form an additional raceway directly on the sleeve.

The assembly is preferably instrumented. In particular, at least one encoder may be provided to be read by at least one fixed sensor, the encoder being fixed relative to the sleeve. If necessary, several angularly offset sensors may be provided to redundantly read the encoder signals, or several encoders opposite several sensors. The sensor(s) may in particular constitute a resolver and be used to control the windings of the electrical machine.

• le porte-codeur peut être fretté au manchon.
• Pour favoriser un arrêt en translation du porte-codeur à l’une de ses extrémités axiales, le porte-codeur peut être arrêté axialement par une butée mécanique du manchon.
• Le porte-codeur peut être arrêté à son extrémité axiale opposée par un anneau élastique logé dans une gorge du manchon et assurant un maintenu axial.

According to one embodiment, the encoder is carried by an encoder holder fixed directly or indirectly to the sleeve. The encoder holder can then be shrunk to the bearing ring attached to the sleeve. Alternatively, the encoder holder can be fixed directly to the sleeve. According to various embodiments,

• the encoder holder can be shrunk to the sleeve.
• To facilitate a translational stop of the encoder holder at one of its axial ends, the encoder holder can be stopped axially by a mechanical stop of the sleeve.
• The encoder holder can be stopped at its opposite axial end by an elastic ring housed in a groove in the sleeve and ensuring axial support.

According to another embodiment, the encoder is carried directly by the sleeve.

According to one embodiment, the rotor support and the sleeve form a single part. The integration of functions is then maximum, at the cost of complexity of the resulting part, as well as its manufacture and assembly.

In an alternative embodiment, the rotor support is a part fixed to the sleeve. Preferably, the rotor support bears against a flange of the sleeve and is fixed to the sleeve by fasteners passing through holes in the rotor support and corresponding holes formed on the flange of the sleeve. Alternatively, the rotor support may be shrink-fitted to the sleeve.

In practice, the guide bearing comprises at least one fixed ring comprising at least one fixed raceway opposite the raceway formed on the sleeve, and at least one row of rolling bodies in rolling contact with the fixed raceway and the raceway formed on the sleeve. The rolling bodies may in particular be cylindrical rollers, tapered rollers or balls, and in this case, with radial or oblique contact.

Preferably, a protective casing is provided, the fixed ring being fixed to the protective casing. The outer ring may be shrunk into the protective casing. Alternatively, the fixed ring may comprise a flange for fixing to the protective casing, the fixing involving fixing elements such as, for example, screws or rivets.

According to one embodiment, the fixed ring is an outer bearing ring, which surrounds the raceway formed on the sleeve. Naturally, the reverse configuration is also possible.

In the case of a double-row angular contact bearing, it is advantageous to form on the fixed ring, for guiding the additional row of rolling bodies, an additional fixed raceway opposite an additional raceway formed on an additional bearing ring secured to the sleeve, or directly on the sleeve.

In order to lubricate the gearbox through the assembly, it may be provided that the housing comprises a hydraulic conduit and a connecting tube opening into the sleeve, the assembly comprising an annular seal between the connecting tube and the sleeve.

In practice, the assembly further comprises an electric machine stator, located at an air gap distance from the rotor and surrounding the rotor, and forming with the rotor an electric machine. The assembly thus constitutes an electric motorization subassembly having mechanical cohesion, intended to drive a transmission box input shaft. Preferably, to protect the electric machine, the casing surrounds the stator.

According to another aspect of the invention, it relates to an electric or hybrid propulsion assembly for a motor vehicle comprising a transmission box having at least one splined input shaft, as well as an assembly as described above, the sleeve being fitted onto the splined input shaft.

BRIEF DESCRIPTION OF THE FIGURES

Other characteristics and advantages of the invention will emerge from reading the description which follows, with reference to the attached figures.

There illustrates a section in an axial plane of an assembly for driving a splined shaft according to a first embodiment of the invention.

There illustrates a section in an axial plane of an assembly for driving a splined shaft according to a second embodiment of the invention.

There illustrates a section in an axial plane of an assembly for driving a splined shaft according to a third embodiment of the invention.

There illustrates a section in an axial plane of an assembly for driving a splined shaft according to a fourth embodiment of the invention.

There illustrates a section in an axial plane of an assembly for driving a splined shaft according to a fifth embodiment of the invention.

There illustrates a section in an axial plane of an assembly for driving a splined shaft according to a sixth embodiment of the invention.

There illustrates a section in an axial plane of an assembly for driving a splined shaft according to a seventh embodiment of the invention.

There illustrates a section in an axial plane of an assembly for driving a splined shaft according to an eighth embodiment of the invention.

For clarity, identical or similar elements are identified by identical reference signs throughout the figures.

DETAILED description of embodiments

On the illustrated is an electric or hybrid propulsion assembly 10 for a motor vehicle comprising a transmission box 12 having at least one splined input shaft 14 (illustrated schematically), and which further comprises an assembly for connecting the splined input shaft 14 to an electric machine 17 .

The electric machine 17 comprises a stator 16 , and a rotor 18 located at an air gap distance from the stator 16 and surrounded by the stator 16. The rotor 18 is mounted on a rotor support 20 shrunk onto a grooved sleeve 22 , and stopped axially by a shoulder formed on the grooved sleeve 22 .

The input shaft 14 is, after assembly, engaged in an internal groove 23 of the grooved sleeve 22 , thus connecting the input shaft 14 in rotation to a rotating assembly formed by the rotor 18 , the rotor support 20 and the grooved sleeve 22 .

The stator 16 is housed in a protective casing 24 closed at one axial end by a support plate 26 on the transmission box casing and at an opposite axial end by a cover 28. The protective casing 24 further comprises a support wall 30 forming a hooping or centering surface for an outer ring 32 of a guide bearing 34 of the grooved sleeve 22 .

The guide bearing34which, in this embodiment, has two rows of rolling bodies35and has an oblique contact “O” structure, binds the sleeve22to the protective casing24. The outer ring32thus comprises two outer raceways facing axially in opposite directions and radially towards two inner raceways, one formed directly on the sleeve22and the other on an inner ring36reported on the sleeve22. This inner bearing ring36reported is, at one axial end, in abutment against a shoulder formed on the sleeve22, and, at an opposite axial end, retained, and where appropriate preloaded, by a collar37 at the end of the sleeve22, formed by a process which may be, for example, cold punching. The guide bearing34allows rotation of the sleeve22and the moving equipment around an axis of revolution of the assembly and therefore the rotation of the input shaft14when driven by the electric machine17.

The sleeve 22 is extended axially, on one side of the support wall opposite the electric machine 17 , by an axial extension 38 which, in this embodiment, is attached to the sleeve 22 , and in this case hooped into a cylindrical cavity of the sleeve 22 , stopped axially by an internal shoulder of the sleeve 22 and optionally by an elastic ring (not shown) housed in an annular groove 39 of the sleeve 22 .

Attached to the cover 28 of the casing 24 are a hydraulic conduit 40 and a connecting tube 42 opening into the axial extension of the sleeve 22 , which is itself tubular. The connecting tube 42 and the axial extension 38 of the sleeve 22 allow the circulation of a lubricating fluid which is used to lubricate the transmission box. An annular seal 44 is located between the connecting tube 42 and the sleeve 22 to ensure the sealing of the connecting tube 42 .

The axial extension 38 of the sleeve 22 also serves, in this embodiment, as an encoder holder for a measuring device of the assembly 41 , which further comprises one or more sensors 46 , fixed to the cover 28 of the casing 24 and located radially at a reading distance from the encoder 48 to read information carried by the encoder 48. The measuring principle can be of any type without contact, and in particular electromagnetic or optical. The sensor 46 and its encoder 48 here form a resolver used to control the electric machine 17 .

The assembly illustrated on the differs from the previous one essentially by the method of fixing used between the rotor support 20 and the sleeve 22. The sleeve 22 , in this embodiment, comprises a flange 50 resting on the rotor support 20. Fastening elements such as screws, bolts or rivets (not shown), are inserted into holes 52 passing through the flange 50 of the sleeve 22 and into corresponding holes 53 passing through the rotor support 20 to fix the two parts.

The embodiment presented on the differs from the previous one essentially by the method of fixing the assembly measuring device 41 and by its nature. Here, an encoder holder 54 is fixed by shrink-fitting on the added ring 36 on the sleeve 22 and the encoder 48 is shrink-fitted to an axial end of the encoder holder 54. The sensor 46 is fixed on the cover 28 of the protective casing 24 at a reading distance from the encoder 48 for axial reading. Alternatively, it would also be possible to orient the encoder 48 and the sensor 46 for radial reading as in the other embodiments.

The fourth embodiment, illustrated in the , differs from the first essentially by the method of fixing used between the outer ring 32 of the guide bearing 34 and the support wall of the casing 30. The outer ring 32 of the guide bearing 34 in fact comprises a flange 56 bearing against the support wall of the casing 30 and which is fixed thereto by fixing elements inserted in holes 58 passing through the flange 56 and corresponding holes 59 passing through the support of the protective casing 30 .

The fourth embodiment also differs from the first by the nature of the inner raceways of the guide bearing 34. Indeed, the two inner raceways of the guide bearing 34 are formed on the sleeve 22 , which dispenses with an added inner ring. In this embodiment, the sleeve 22 has an insertion hole 60 for the rolling bodies, which opens between the inner raceways, and allows the mounting of the rolling bodies 35 .

The embodiment illustrated on the differs from the second essentially by the method of attachment between the sleeve 22 and the rotor support 20. The rotor support 20 is shrunk and possibly welded or glued to the grooved sleeve 22 and stopped axially by a shoulder of the sleeve 22 .

On the , the illustrated embodiment differs from the previous one essentially by the fact that the rotor support20and the sleeve22form a single piece62which, at one radial end, is shrunk to the rotor18and at an opposite radial end, is internally grooved23 and engaged with external splines of the input shaft14of the transmission box.

The embodiment illustrated on the differs from the fourth essentially by the method of fixing the outer ring of the guide bearing 32 to the wall of the support of the protective casing 30. The outer ring 32 is shrunk and possibly welded or glued into the support of the casing 30 , and has a shoulder which comes to bear on an outer face of the casing support 30 .

The embodiment illustrated on the differs from the previous ones in that the sleeve 22 and its axial extension 38 form a single part 64. This common part 64 is secured to the input shaft 14 at the splines 23 , shrunk to the rotor support 20. It also serves as an encoder holder for the assembly measuring device 41 , which is shrunk to it.

Naturally, the examples shown in the figures and discussed above are given for illustrative purposes only and are not limiting. The guide bearing 34 may have two rows of rolling bodies 35 with an “X” structure with oblique contact. It is explicitly provided that the different embodiments illustrated may be combined with each other to propose others.

Claims (16)

Assembly for driving a splined shaft, the assembly comprising:

• a rotor support (20) of an electric machine (17),
• a sleeve (22) comprising a groove (23) for connection to the shaft, the sleeve (22) being integral with the rotor support (20), and
• a guide bearing (34) for rotating the sleeve (22) around an axis of revolution of the assembly,

characterized in that the sleeve (22) constitutes at least one raceway for a row of rolling bodies (35) of the guide bearing (34). Assembly according to claim 1, characterized in that:

• the raceway formed by the sleeve (22) is an inner raceway, facing radially outwards, or the raceway formed by the sleeve (22) is an outer raceway, facing radially inwards; and
• The sleeve groove is either radially outwardly rotated or radially inwardly rotated.

Assembly according to any one of the preceding claims, characterized in that the guide bearing (34) comprises a bearing ring (36) attached to the sleeve (22) to constitute an additional raceway for an additional row of rolling bodies (35) of the guide bearing (34). Assembly according to claim 3, characterized in that:

• the rolling ring (36) attached to the sleeve (22) is shrunk onto a cylindrical or conical surface of the sleeve (22), and/or
• the attached ring (36) abuts against a shoulder formed on the sleeve (22), and/or
• the sleeve (22) comprises a collar (37) bearing against a flat annular end face of the bearing ring (36) attached to the sleeve (22) and/or
• the sleeve (22) has a thread for a stop nut of the attached bearing ring (36).

Assembly according to any one of the preceding claims, characterized in that it further comprises at least one encoder (48) intended to be read by at least one fixed sensor (46), the encoder (48) being fixed relative to the sleeve (22). Assembly according to claim 5, characterized in that the encoder (48) is carried by an encoder holder (38, 54) fixed directly or indirectly to the sleeve (22). Assembly according to claim 6 in combination with claim 3, characterized in that the encoder holder (54) is shrunk to the bearing ring (36) attached to the sleeve (22). Assembly according to claim 6, characterized in that the encoder holder (38) is fixed directly to the sleeve and in that, preferably:

• the encoder holder (38) is shrunk to the sleeve (22) and/or
• the encoder holder (38) is stopped axially by a mechanical stop of the sleeve (22) and/or
• the encoder holder (38) is held axially by an elastic ring housed in a groove (39) of the sleeve (22).

Assembly according to claim 5, characterized in that the encoder (48) is carried directly by the sleeve (22). Assembly according to any one of claims 1 to 9, characterized in that the rotor support (20) and the sleeve (22) form a single piece (62). Assembly according to any one of claims 1 to 9, characterized in that the rotor support (20) is a part fixed to the sleeve (22), and in that, preferably:

• the rotor support (20) bears against a flange (50) of the sleeve (22) and is fixed to the sleeve (22) by fixing elements passing through holes (53) in the rotor support (20) and corresponding holes (52) formed on the flange (50) of the sleeve (22); or

• the rotor support (20) is shrunk, welded or glued to the sleeve (22).

Assembly according to any one of the preceding claims, characterized in that the guide bearing (34) comprises at least one fixed ring (32) comprising at least one fixed raceway opposite the raceway formed on the sleeve (22), and at least one row of rolling bodies (35) in rolling contact with the fixed raceway and the raceway formed on the sleeve (22). Assembly according to claim 12, characterized in that it further comprises a protective casing (24), the fixed ring (32) being fixed to the protective casing (24). Assembly according to claim 13, characterized in that the casing (24) comprises a hydraulic conduit (40) and a connection tube (42) opening into the sleeve (22), the assembly comprising an annular seal (44) between the connection tube (42) and the sleeve (22). Assembly according to any one of the preceding claims, characterized in that it further comprises a stator (16) of an electric machine (17), located at an air gap distance from the rotor (18) and surrounding the rotor (18), and forming with the rotor (18) an electric machine (17). Electric or hybrid propulsion assembly (10) for a motor vehicle comprising a transmission box having at least one splined input shaft (14), characterized in that it further comprises an assembly according to any one of the preceding claims, the sleeve (22) being fitted onto the splined input shaft (14).