MOTOR VEHICLE TRANSMISSION SYSTEM

Abstract

A transmission system (M) for a motor vehicle, comprising: - a speed reduction device (R) in which at least a first transmission shaft (10), provided with a first pinion (11) rotating about a first axis of rotation (X1), and a second transmission shaft (20), provided with an intermediate gear (21) rotating about a second axis of rotation (X2), mesh together and form a first reduction stage; - a transmission housing (40a) and a closing cover (40b) assembled so as to form a casing (40) defining a housing in which the speed reduction device is received at least in part; in which the first transmission shaft (10) and the second transmission shaft (20) are supported by a common support (70), said common support (70) being separate from the casing (40) and fixedly supported by the transmission housing (40a) and / or the closing cover (40b). (Abstract figure: 1)

Description

Title of the invention: TRANSMISSION SYSTEM FOR MOTORIZED VEHICLES TECHNICAL FIELD OF THE INVENTION

[0001] The invention relates to a transmission system for a motor vehicle. This transmission system includes, in particular, a series of gear trains for connecting an electric machine to the vehicle's wheels, with the aim of reducing the rotational speed between the input and output of the transmission system. The invention also relates to a powertrain comprising the transmission system and the electric machine. When the motor vehicle also includes an internal combustion engine coupled to the electric machine, the vehicle is said to be "hybrid" because the vehicle's propulsion can be achieved either purely electrically, purely thermally, or in a hybrid manner by using both types of energy simultaneously.

[0002] In the case of a purely electric motorized vehicle, i.e., one without an internal combustion engine, electricity can be supplied by means of a battery or a fuel cell using hydrogen as a reducing fuel. The electric motorized vehicle can be a passenger car or an industrial vehicle, such as a truck, bus, or tractor. PRIOR TECHNOLOGY

[0003] Installing a powertrain on a motor vehicle chassis requires consideration of numerous technical constraints, such as the vehicle's dimensions, wheelbase, battery location, and available ground clearance. The transmission system comprises an input shaft, generally combined with the rotation axis of the electric motor, and an output shaft, generally combined with the vehicle's wheel shafts. The positions of these input and output shafts constitute geometric mounting interfaces imposed by the vehicle manufacturer, as do the interfaces for attaching the transmission system to the vehicle chassis. Since each vehicle has a chassis with specific geometry and dimensions, these geometric mounting and attachment interfaces must be positioned at specific locations within the powertrain.The position of the input and output shafts of the transmission system is defined by a transmission center distance that varies for each application.

[0004] For example, such a powertrain is known from patent application FR3095410 AL. The powertrain according to this patent application comprises a plurality of housings, the plurality of housings each having an internal space intended to house one or more components of the powertrain, and the plurality of housings together forming a powertrain assembly housing having an internal space, the assembly of housings comprising:

[0005] - at least one mounting housing comprising at least one mounting portion designed to attach the powertrain to the vehicle chassis,

[0006] - at least one additional fixed housing on the mounting housing and devoid of mounting portions intended to be fixed to the vehicle chassis.

[0007] In this powertrain, the transmission gears are supported directly by the housings. A change in the transmission center distance will require modifications to all the mounting housings and auxiliary housings.

[0008] Adapting the structure of a powertrain to the specific characteristics of different vehicle chassis is therefore complicated and costly. Many parts, such as transmission housings, which are sometimes very large, generally need to be adapted for each new application, particularly to comply with the transmission bolt pattern specified by the manufacturer. The present invention aims to overcome this problem. Description of the invention

[0009] The invention aims to remedy the disadvantages of the prior art and to propose a transmission system with reduced manufacturing costs and the ability to easily adjust the center distance value of the transmission without having to completely redesign the components of said transmission system.

[0010] To this end, according to a first aspect of the invention, a transmission system for a motor vehicle is proposed, comprising:

[0011] - a speed reduction device in which at least one first shaft of transmission, provided with a first pinion rotating around a first axis of rotation XI, and a second transmission shaft, provided with an intermediate toothed wheel rotating around a second axis of rotation X2, mesh together and form a first reduction stage;

[0012] - a transmission housing and a closing cover assembled so as to form a housing defining a compartment in which the speed reduction device is received, at least in part.

[0013] The transmission system is remarkable in that the first transmission shaft and the second transmission shaft are supported by a common support, said common support being separate from the housing and fixedly supported by the transmission housing and / or the closing cover.

[0014] The common support serves to hold the transmission shafts in position within the transmission system and to support all the mechanical forces generated by the engine torque transmitted within the reduction stage. The common support is designed to absorb the mechanical forces of the speed reduction device and to minimize geometric deformations. This prevents excessive deformations from being transmitted to the housing, for which it is not designed. The housing's main function is to protect the speed reduction device from its external environment and, if the transmission system is equipped with lubricating oil, to contain it.

[0015] The common support is also complex in shape, while the transmission housing and the cover are simple in shape. This simplifies the manufacturing process for the transmission housing and the cover and reduces their manufacturing cost. The use of stamped steel sheet is possible, thus reducing the overall size of the transmission system.

[0016] Advantageously, the speed reduction device may include at least one third transmission shaft, provided with a torque output gear rotating about a third axis of rotation X3, which meshes with an intermediate pinion of the second transmission shaft and forms, with this second transmission shaft, a second reduction stage. The second and third transmission shafts are held in position by an additional support, said additional support being separate from the housing and fixedly supported by the transmission casing and / or the cover. In this way, it is possible to precisely define the center distance between the first and third transmission shafts.

[0017] Preferably, the second transmission shaft and the third transmission shaft can be supported by the additional support.

[0018] According to one embodiment of the invention, the speed reduction device can form a unit subassembly in which the common support, the additional support and the first, second and third transmission shafts are pre-assembled.

[0019] According to another embodiment of the invention, the common support and the additional support can be rigidly joined to each other, for example by screwing, riveting, or welding. The common support and the additional support are then attached before assembly in the housing.

[0020] According to another embodiment of the invention, the common support and the additional support can be articulated to each other about the second axis of rotation X2 and rigidly connected to the housing. Thanks to the articulation available between the two supports, It is possible to adjust the center distance between the first and third drive shafts to comply with the geometric interface constraints imposed by the vehicle manufacturer. Based on this articulation function, it is also possible to adapt the center distance between the first and third drive shafts for different types of manufacturer applications without necessarily having to redesign the speed reduction mechanism. This allows for easy adaptation of an existing transmission system to a different vehicle chassis.

[0021] Advantageously, the first and second transmission shafts are supported by the common support via guide bearings, the common support comprising semi-circular housings having parallel axes arranged to receive the guide bearings. In this way, the common support can absorb the mechanical forces of the speed reduction device and minimize the geometric deformations transmitted to the housing.

[0022] Preferably, four guide bearings can guide the first transmission shaft and the second transmission shaft in rotation, two attachment flanges can hold the four guide bearings on the common support, a first attachment flange is common to a guide bearing of the first transmission shaft and a guide bearing of the second transmission shaft, a second attachment flange is common to a guide bearing of the first transmission shaft and a guide bearing of the second transmission shaft.

[0023] Advantageously, the first attachment flange can be screwed onto the common support and comprise two semi-circular housings having parallel axes arranged to receive the guide bearings.

[0024] Advantageously, the second attachment flange can be screwed onto the common support and comprise two semi-circular housings having parallel axes arranged to receive the guide bearings.

[0025] Preferably, the first attachment flange and the second attachment flange can be axially spaced, the first pinion and the intermediate gear of the first and second transmission shafts being arranged axially between the two attachment flanges.

[0026] Advantageously, the common support and the additional support, before assembly in the housing, can be mobile in rotation relative to each other around the second axis of rotation X2.

[0027] According to one embodiment of the invention, the common support may include at least one cylindrical centering surface and the additional support may include at least one complementary centering surface, at least partially cylindrical, which rests on the cylindrical centering surface.

[0028] Advantageously, the common support may include first and second cylindrical centering surfaces and the additional support includes first and second complementary centering surfaces at least partially cylindrical, the first complementary centering surface bearing on the first cylindrical centering surface, the second complementary centering surface bearing on the second cylindrical centering surface.

[0029] Preferably, the common support may have a body and U-shaped support walls distributed in two groups, a first group of two support walls extending circumferentially around the first axis of rotation XI, and a second group of two support walls extending circumferentially around the second axis of rotation X2, each support wall having at its end a semi-circular housing arranged to receive a guide bearing.

[0030] The common support and the additional support can be made of steel. In this way, the coefficient of thermal expansion is identical between the transmission shafts, the guide bearings, and the supports. The axial preloading of the guide bearings is simplified because it is not necessary to take into account different coefficients of thermal expansion between the housing and the components of the speed reduction device when the supports are made of steel.

[0031] For example, the first transmission shaft, the second transmission shaft and the third transmission shaft are parallel to each other.

[0032] The common support according to the invention may have one or more of the characteristics described below, either combined or taken independently of each other:

[0033] - the semi-circular housings are machined on the ends of the support walls;

[0034] - the support walls are arranged at the four ends of the body;

[0035] - the body extends axially along the first transmission shaft;

[0036] - the body extends axially along the second transmission shaft;

[0037] - the body extends partially between the first transmission shaft and the second drive shaft;

[0038] - the body extends partially between the first transmission shaft and the third drive shaft;

[0039] - the body extends partially between the second transmission shaft and the third drive shaft;

[0040] - the common support includes mounting tabs equipped with holes for the fixing on the housing, the holes extending radially beyond the outer diameter of the gear on the first transmission shaft;

[0041] - the common support and the attachment flanges are rigidly fixed by the intermediary of screws, the screws being notably inserted into machined drilling-tapping holes in the support walls;

[0042] - the common support has a welded mechanical type structure;

[0043] - the common support is obtained by forging and then machining.

[0044] According to one embodiment of the invention, the additional support may comprise a main part and additional U-shaped support walls distributed at both ends of the main part, the two additional support walls extending circumferentially around the third axis of rotation X3, each additional support wall having at its end a semi-circular housing arranged to receive a guide bearing.

[0045] Advantageously, the main part of the additional support may have a recess arranged to receive the torque output gear of the third transmission shaft.

[0046] Preferably, the additional support may include at least one connecting arm supporting one of the complementary centering surfaces and which connects the main part to the common support.

[0047] Advantageously, the additional support may include mounting tabs equipped with holes for fixing to the housing, the holes extending radially beyond the outside diameter of the gear of the third transmission shaft.

[0048] Preferably, the fixing lugs can be connected to the main part.

[0049] Advantageously, the transmission housing and / or the closing cover can be made of stamped sheet metal, for example steel, stainless steel or aluminium.

[0050] Preferably, the transmission housing and / or the closing cover may include bearing surfaces having shapes adapted to receive fixing tabs of the common support and the additional support.

[0051] Advantageously, the transmission housing and / or the closing cover may include at least one through-hole for a wheel shaft of the motor vehicle.

[0052] Preferably, the transmission housing may include a passage for the rotor shaft of the electric machine of the motorized vehicle.

[0053] Advantageously, the transmission housing may include a mounting area for the electric machine of the motorized vehicle.

[0054] According to one embodiment of the invention, the transmission system may include a manifold for receiving and distributing lubricating fluid housed inside the casing, said manifold comprising at least a base, an outer rim, and a fluid supply line from the base or the rim Externally, said fluid supply line supplies lubricating fluid to one of the guide bearings.

[0055] According to one embodiment of the invention, the housing can be composed of a transmission casing and a closing cover that rests on the transmission casing, at the level of a joint plane to seal the internal volume of the casing.

[0056] In order to overcome the drawbacks of the prior art and to offer a transmission system with reduced manufacturing costs and the ability to easily adjust the transmission center distance without having to completely redesign the components of said transmission system, a transmission system for a motor vehicle is proposed according to a second aspect of the invention, comprising:

[0057] - a speed reduction device in which:

[0058] - a first transmission shaft, provided with a first pinion rotating around a first axis of rotation XI; and a second transmission shaft, equipped with an intermediate gear rotating around a second axis of rotation X2, mesh together and form a first reduction stage;

[0059] - a third transmission shaft, equipped with a torque output gear rotating around a third axis of rotation X3, which meshes with an intermediate pinion of the second transmission shaft and forms with this second transmission shaft a second reduction stage;

[0060] - a transmission housing and a closing cover assembled so as to form a housing defining a compartment in which the speed reduction device is received, at least in part;

[0061] in which the first transmission shaft, the second transmission shaft and the third transmission shaft are supported by a common support, said common support being separate from the housing and fixedly supported by the transmission housing and / or the closing cover.

[0062] According to this second aspect of the invention, the common support serves to maintain the various transmission shafts in position within the transmission system and to support all the mechanical forces generated by the engine torque transmitted within the reduction stages. The common support is designed to absorb the mechanical forces of the speed reduction device and to minimize geometric deformations. This prevents excessive deformations, for which the housing is not designed, from being transmitted back to the gearbox. The housing's main function is to protect the speed reduction device from its external environment and, if the transmission system is equipped with lubricating oil, to potentially contain it.

[0063] The common support is also complex in shape, while the transmission housing and the cover are simple in shape. This simplifies the manufacturing process of the transmission housing and the cover, thereby reducing their manufacturing cost. For example, the transmission housing and the cover can be produced by stamping.

[0064] Preferably, the speed reduction device can form a unit subassembly in which the common support and the first, second, and third drive shafts are pre-assembled. The transmission system then exhibits increased rigidity.

[0065] Advantageously, the common support may have a U-shaped body and support walls distributed in three groups, a first group of two support walls extending circumferentially around the first axis of rotation XI, a second group of two support walls extending circumferentially around the second axis of rotation X2, and a third group of two support walls extending circumferentially around the third axis of rotation X3.

[0066] Preferably, the support walls can be arranged at the different ends of the body and each support wall has at its end a semi-circular housing arranged to receive a guide bearing.

[0067] The common support according to the invention may have one or more of the characteristics described below, either combined or taken independently of each other:

[0068] - the semi-circular housings are machined on the ends of the support walls;

[0069] - the body extends axially along the first transmission shaft;

[0070] - the body extends axially along the second transmission shaft;

[0071] - the body extends partially between the first transmission shaft and the second drive shaft;

[0072] - the body extends partially between the first transmission shaft and the third drive shaft;

[0073] - the body extends partially between the second transmission shaft and the third drive shaft;

[0074] - the common support includes mounting tabs equipped with holes for the fixing on the housing, the holes extending radially beyond the outer diameter of the gear on the first transmission shaft;

[0075] - the common support has a welded mechanical type structure;

[0076] - the common support is obtained by forging and then machining.

[0077] According to another aspect of the invention, it relates to a powertrain comprising an electric machine and a transmission system incorporating all or part of the characteristics mentioned above, the first shaft of transmission constituting an output shaft of the electric machine or being rotationally fixed to a rotor of the electric machine.

[0078] Advantageously, a stator of the electric machine can be fixed to the transmission housing.

[0079] The invention is more particularly applicable to a speed reducer type transmission system, and in particular to a fixed ratio or two ratio speed reducer, to a parallel shaft reducer or to a coaxial type speed reducer comprising an epicyclic gear train, in which the axis of rotation of the electric machine is concentric with the output shaft of the epicyclic gear train. BRIEF DESCRIPTION OF THE FIGURES

[0080] Other features and advantages of the invention will become apparent from the following description, with reference to the attached figures.

[0081] [Fig.1] Fig.1 illustrates an exploded isometric view of the transmission system according to a first embodiment of the invention.

[0082] [Fig.2] Fig.2 illustrates a front view of the inside of the transmission system of Fig.1.

[0083] [Fig.3] The [Fig.3] illustrates a detailed view of the transmission system of the [Fig.1].

[0084] [Fig.4] Fig.4 illustrates another detailed view of the transmission system of the [Fig.l].

[0085] [Fig.5] The [Fig.5] illustrates a cross-sectional view of a powertrain according to the first embodiment of the invention of the [Fig.1].

[0086] [Fig.6] Fig.6 illustrates a front view of the inside of a transmission system according to a second embodiment of the invention.

[0087] For clarity, identical or similar elements are identified by identical reference symbols throughout the figures. DETAILED description of implementation methods

[0088] Figures 1 to 5 illustrate a powertrain 1, comprising an electric machine 60 and a transmission system M according to a first embodiment of the invention. The transmission system M includes a speed reduction device R transmitting the torque from the electric machine 60 to the wheels of the electric or hybrid vehicle.

[0089] As illustrated in [Fig. 5], the electric machine 60 can be, for example, an induction electric motor, comprising a rotor 62 and a stator 61, electrically powered by three-phase alternating current from storage batteries via a current converter (not shown). The electric machine can be of another type, for example, an axial flux machine.

[0090] The electric machine 60 is mounted on a housing 40. The housing generally consists of a transmission casing 40a supporting the electric machine 60 and a closing cover 40b bearing against the transmission casing 40a at a joint 48, to seal a cavity defined by the transmission casing 40a and the closing cover 40b. The transmission casing 40a includes a base 42 and a circumferential rim 43 defining an internal volume suitable for receiving a lubricating fluid. The housing 40 defines a recess in which the speed reduction device R is at least partially housed. In this case, the transmission casing 40a and the closing cover 40b are made of stamped sheet steel.

[0091] Alternatively, the transmission housing 40a and the closing cover 40b can be made of injected plastic material.

[0092] The electric machine 60 drives in rotation a first transmission shaft 10 which enters the transmission housing 40a. The first transmission shaft 10 constitutes an input shaft of the speed reduction device R, which also includes a second transmission shaft 20, and a third transmission shaft 30 which constitutes an output shaft of the speed reduction device.

[0093] As illustrated in [Fig. 5], the first drive shaft 10 is aligned with the motor shaft of the electric machine 60 relative to the transmission housing 40a, and carries at least one first pinion 1, which is rotationally connected to the first drive shaft. The transmission housing 40a includes a through hole 45 arranged to allow passage of the first drive shaft 10, or alternatively, the motor shaft of the electric machine 60.

[0094] The second transmission shaft 20, which forms an intermediate shaft of the speed reduction device R, is parallel to the first transmission shaft 10 and the third transmission shaft 30. At the output of the speed reduction device R, the third transmission shaft 30 is a differential used to transmit and distribute torque from the electric machine 60 (not shown) to two wheel shafts of an axle of a motor vehicle. The transmission housing 40a and the closing cover 40b each include an opening 46 arranged to allow the wheel shafts to pass through.

[0095] The first transmission shaft 10 and the second transmission shaft 20 are supported by a common support 70. The first transmission shaft 10, also called the input shaft, is guided in rotation by two guide bearings 100a, 100b so as to rotate about a first axis of rotation XI relative to the common support 70. The second transmission shaft 20 is guided in rotation by two guide bearings 200a, 200b so as to rotate about a second axis of rotation X2 relative to the common support 70.

[0096] The guide bearing 100a, which supports the first transmission shaft 10 relative to the common support 70, includes, in particular, rolling elements, in this case, rolling balls. The guide bearing 100a is inserted into a semi-circular housing 76a formed in the common support 70.

[0097] The second transmission shaft 20 and the third transmission shaft 30 are held in position by an additional support 80. The third transmission shaft 30, otherwise called the output shaft, is guided in rotation by two guide bearings 300a, 300b so as to rotate around a first axis of rotation X3 relative to the additional support 80. The first, second and third axes of rotation XI, X2, X3 are parallel to each other.

[0098] To lubricate the various components of the transmission system M, the housing 40 contains lubricating fluid, for example, oil. The guide bearings, for example ball bearings, the pinions, and the gears of the various transmission shafts are partially immersed in the oil. The movement of the transmission system then, by splashing, mixes the oil and projects it throughout the entire internal volume of the housing, ensuring the desired lubrication of the entire speed reduction device R, including the non-immersed parts.

[0099] The third transmission shaft 30, otherwise called the output shaft, includes a torque output gear 31. The output shaft 30 further includes a fixed rotational link with a planet carrier of a differential 3 2, or constitutes the planet carrier of the differential 3 2. The differential 3 2 can be open or limited slip, depending on the properties required.

[0100] The second transmission shaft 20, also called the intermediate shaft, supports an intermediate gear 21 and an intermediate pinion 22. The intermediate gear 21 and the intermediate pinion 22 are rotationally linked to the second transmission shaft 20. The intermediate gear 21 forms a first reduction stage with the first pinion 11 of the input shaft 10, and the intermediate pinion 22 forms a second reduction stage with the torque output gear 31 of the output shaft 30.

[0101] The first pinion 11 has a diameter and number of teeth smaller than the diameter and number of teeth of the intermediate gear 21 of the intermediate shaft 20 forming the first speed reduction stage. Similarly, the intermediate pinion 22 of the intermediate shaft 20 forming the second speed reduction stage has a diameter and number of teeth smaller than the diameter and number of teeth of the torque output gear 31 of the output shaft 30. The transmission system M is therefore a reduction gear with no gear change.

[0102] For the remainder of this description, a reference operational position of the transmission system M is defined as the three-dimensional orientation in which the transmission mechanism M is installed in a horizontal vehicle. In this reference operational position illustrated in [Fig. 2], the second axis of rotation X2 is located above the first axis of rotation XI and the third axis of rotation X3. In the remainder of this description, unless otherwise stated, the invention will be described in this reference operational position.

[0103] The transmission housing 40a and the closing cover 40b are assembled to form the housing 40 defining a housing in which the speed reduction device R is received. The first transmission shaft, the second transmission shaft and the third transmission shaft are supported by the common support 70 and the additional support 80. The common support 70 and the additional support 80 are separate from the housing and are fixedly supported by the transmission housing 40a.

[0104] The speed reduction device R forms a unit subassembly in which the common support 70, the additional support 80 and the first, second and third transmission shafts 10, 20, 30 are pre-assembled.

[0105] In this first embodiment of the invention, the common support 70 and the additional support 80 are articulated to each other around the second axis of rotation X2 and rigidly linked to the housing 40. From this articulation function, it is possible to position the first and third axes of rotation XI, X3 and to define a center distance value E between the first transmission shaft and the third transmission shaft.

[0106] To achieve this articulation function, the common support 70 comprises first and second cylindrical centering surfaces 74a, 74b, and the additional support 80 comprises first and second complementary centering surfaces 84b, 84b, which are at least partially cylindrical. The first complementary centering surface 84a bears against the first cylindrical centering surface 74a, and the second complementary centering surface 84a bears against the second cylindrical centering surface 74a.

[0107] The combination of the first complementary centering surface 84a and the first cylindrical centering surface 74a forms a first pivot joint about the second axis of rotation X2. The combination of the second complementary centering surface 84b and the second cylindrical centering surface 74b forms a second pivot joint about the second axis of rotation X2. The two pivot joints are axially spaced with respect to the second axis of rotation X2. In this way, the common support 70 and the additional support 80 are rotationally movable. one relative to the other around the second axis of rotation X2 before assembly in the 40 case.

[0108] As illustrated in [Fig.3], the first transmission shaft 10 and the second transmission shaft 20 are supported by the common support 70 via guide bearings 100a, 100b, 200a, 200b. The common support 70 includes semi-circular housings 76a having parallel axes arranged to receive the guide bearings.

[0109] More specifically, four guide bearings 100a, 100b, 200a, 200b guide the rotation of the first transmission shaft 10 and the second transmission shaft 20, and two retaining flanges 71, 72 hold the four guide bearings on the common support 70. A first retaining flange 71 is common to a guide bearing 100a of the first transmission shaft 10 and a guide bearing 200a of the second transmission shaft 20. A second retaining flange 72 is common to a guide bearing 100b of the first transmission shaft 10 and a guide bearing 200b of the second transmission shaft 20.

[0110] The first attachment flange 71 is screwed onto the common support 70 and includes two semi-circular housings 76a having parallel axes arranged to receive the guide bearings.

[0111] Also, the second attachment flange 7 2 is screwed onto the common support 70 and includes two semi-circular housings 76a having parallel axes arranged to receive the guide bearings.

[0112] In this example, the first and second attachment flanges are axially spaced, the first pinion 11 and the intermediate gear 21 of the first and second transmission shafts 10, 20 being arranged axially between the two attachment flanges 71, 72. The common support 70 and the attachment flanges 71, 72 are rigidly fixed by means of screws 90, the screws 90 being in particular inserted into machined holes in the support walls 76.

[0113] The common support 70 has a body 75 and U-shaped support walls 76 arranged in two groups: a first group of two support walls 76 extending circumferentially around the first axis of rotation XI, and a second group of two support walls 76 extending circumferentially around the second axis of rotation X2. The support walls 76 are located at the four ends of the body 75, and each support wall 76 has at its end a semicircular recess 76a arranged to receive the guide bearing. The semicircular recesses 76a are machined on the ends of the support walls 76.

[0114] As illustrated in [Fig. 4], the body 75 extends axially along the first transmission shaft 10 and extends partially between the first transmission shaft 10 and the third drive shaft 30. The body 75 uses the available space inside the housing 40 to support the first drive shaft 10 and the second drive shaft 20.

[0115] The common support 70 includes mounting tabs 73 equipped with holes 73a for fixing to the housing 40, the holes 73a extending radially beyond the outside diameter of the gear of the first transmission shaft 10. The mounting tabs 73 can be connected to the body 75 by welding.

[0116] The common support 70 made of steel may have a welded structure, or be obtained by forging and then machining.

[0117] The transmission housing 40a includes bearing surfaces 41 having shapes adapted to receive the fixing tabs 73a of the common support 70.

[0118] The unit subassembly formed by the speed reduction device R is fixed to the transmission housing 40a using fixing screws or rivets. Then the housing 40 is closed by applying the closing cover 40b to the transmission housing, and the housing is hermetically sealed by means of the closing screws 91 distributed at the level of the sealing surface 48.

[0119] As illustrated in [Fig. 3], the additional support 80 comprises a main portion 85 and U-shaped additional support walls 86 distributed at both ends of the main portion, the two additional support walls 86 extending circumferentially around the third axis of rotation X3. Each additional support wall 86 has at its end a semi-circular housing 86a arranged to receive a guide bearing. The second drive shaft 20 and the third drive shaft 30 are thus held in position by the additional support 80.

[0120] The main part 85 of the additional support 80 has a recess 87 arranged to receive a gear of the third transmission shaft and includes two connecting arms 81 supporting the complementary centering surfaces 84b, 84b. Each connecting arm 81 rigidly connects the main part 85 to the common support 70.

[0121] The two guide bearings 300a, 300b are held by additional attachment flanges 88 attached to the additional support walls 86.

[0122] For mounting on the housing 40, the additional support 80 may include mounting tabs 83 equipped with holes 83a. The holes 83a extend radially beyond the outer diameter of the gear of the third transmission shaft 30. The mounting tabs 83 may be connected to the main part 85 by welding.

[0123] We will now describe, with reference to [Fig.6], a second embodiment of the invention, which differs from the first embodiment by the use of a common support supporting all the transmission shafts of the speed reduction device.

[0124] To this end, the transmission system M includes a speed reduction device R in which:

[0125] - a first transmission shaft 10, provided with a first rotating pinion 11 around a first axis of rotation XI, and a second transmission shaft 20, provided with an intermediate toothed wheel 21 rotating around a second axis of rotation X2, mesh together and form a first stage of reduction;

[0126] - a third transmission shaft 30, provided with a torque output gear 31 rotating around a third axis of rotation X3, which meshes with an intermediate pinion 22 of the second transmission shaft 20 and forms with this second transmission shaft a second reduction stage;

[0127] - a transmission housing 40a and a closing cover 40b assembled from in order to form a housing 40 defining a housing in which the speed reduction device R is received;

[0128] in which the first transmission shaft 10, the second transmission shaft 20 and the third transmission shaft 30 are supported by a common support 70, said common support 70 being separate from the housing and fixedly supported by the transmission housing 40a.

[0129] The speed reduction device R forms a unit subassembly in which the common support 70 and the first, second and third transmission shafts 10, 20, 30 are pre-assembled.

[0130] The common support 70 has a body 75 and U-shaped support walls 76 arranged in three groups: a first group of two support walls 76 extending circumferentially around the first axis of rotation XI, a second group of two support walls 76 extending circumferentially around the second axis of rotation X2, and a third group of two support walls 76 extending circumferentially around the third axis of rotation X3. The support walls 76 are located at the different ends of the body 75, and each support wall 76 has at its end a semicircular recess 76a arranged to receive guide bearings. The semicircular recesses 76a are machined on the ends of the support walls 76.

[0131] More particularly, six guide bearings 100a, 100b, 200a, 200b, 300a, 300b guide in rotation the first transmission shaft 10, the second transmission shaft 20 and the third transmission shaft 30, and attachment flanges 71, 72, 88 hold the six guide bearings on the common support 70.

[0132] As illustrated in [Fig. 6], the body 75 extends axially along the first transmission shaft 10, along the second transmission shaft 20, and extends partially between the first transmission shaft 10 and the third transmission shaft 30. The body 75 uses the available space inside the housing 40 to support the first drive shaft 10, the second drive shaft 20 and the third drive shaft 30.

[0133] In this second embodiment of the invention, the common support 70 is rigidly linked to the housing 40. The position of the first and third axes of rotation XI, X 3 defines a center distance value E between the first transmission shaft and the third transmission shaft.

[0134] Naturally, the examples shown in the figures and discussed above are given by way of illustration only and are not intended to be limiting. It is explicitly intended that the different embodiments illustrated may be combined to propose others.

[0135] According to another embodiment of the invention, the common support 70 and the additional support 80 can be rigidly joined to each other, for example by screwing, riveting, or welding. In this example, the common support and the additional support are attached before assembly in the housing.

[0136] According to an unillustrated variant, the transmission system M may be of coaxial type comprising an epicyclic gear train, in which the axis of rotation of the electric machine is concentric with the output shaft of the epicyclic gear train.

[0137] The transmission system M described above is a constant speed ratio reduction mechanism with one intermediate shaft, but the invention is also intended to be applied to mechanisms with several intermediate shafts, or without an intermediate shaft, to mechanisms with several speed ratios.

Claims

Demands

1. Transmission system (M) for a motor vehicle, comprising: - a speed reduction device (R) in which at least a first transmission shaft (10), having a first pinion (11) rotating about a first axis of rotation (XI), and a second transmission shaft (20), having an intermediate toothed wheel (21) rotating about a second axis of rotation (X2), mesh together and form a first reduction stage; - a transmission housing (40a) and a closing cover (40b) assembled so as to form a housing (40) defining a recess in which the speed reduction device is received at least in part; characterized in that the first transmission shaft (10) and the second transmission shaft (20) are supported by a common support (70), said common support (70) being separate from the housing (40) and fixedly supported by the transmission housing (40a) and / or the closing cover (40b).

2. Transmission system (M) according to claim 1, wherein the speed reduction device (R) comprises at least one third transmission shaft (30), provided with a torque output gear (31) rotating about a third axis of rotation (X3), which meshes with an intermediate pinion (22) of the second transmission shaft (20) and forms with this second transmission shaft (20) a second reduction stage, the second transmission shaft (20) and the third transmission shaft (30) are held in position by an additional support (80), said additional support (80) being separate from the housing (40) and fixedly supported by the transmission housing (40a) and / or the closing cover (40b).

3. Transmission system (M) according to the preceding claim, wherein the common support (70) and the additional support (80) are articulated to each other around the second axis of rotation (X2) and rigidly linked to the housing (40).

4. A transmission system (M) according to any one of the preceding claims, wherein the first transmission shaft (10) and the second transmission shaft (20) are supported by the common support (70) via guide bearings (100a, 100b, 200a, 200b), the common support (70) comprising housings semi-circular (76a) having parallel axes arranged to receive the guide bearings.

5. Transmission system (M) according to the preceding claim, wherein four guide bearings (100a, 100b, 200a, 200b) guide the first transmission shaft (10) and the second transmission shaft (20) in rotation, two attachment flanges (71, 72) retain the four guide bearings on the common support, a first attachment flange (71) is common to a guide bearing (100a) of the first transmission shaft and a guide bearing (200a) of the second transmission shaft, a second attachment flange (72) is common to a guide bearing (100b) of the first transmission shaft and a guide bearing (200b) of the second transmission shaft.

6. Transmission system (M) according to claim 5, wherein the first attachment flange (71) is screwed onto the common support (70) and comprises two semi-circular housings (71a) having parallel axes arranged to receive the guide bearings.

7. Transmission system (M) according to claim 5 or 6, wherein the second attachment flange (72) is screwed onto the common support (70) and comprises two semi-circular housings (72a) having parallel axes arranged to receive the guide bearings.

8. Transmission system (M) according to any one of claims 5 to 7, wherein the first attachment flange (71) and the second attachment flange (72) are axially spaced, the first pinion and the intermediate gear (11,21) of the first and second transmission shafts (10, 20) being arranged axially between the two attachment flanges.

9. Transmission system (M) according to any one of claims 2 to 8, wherein the common support (70) comprises at least one cylindrical centering surface (74a, 74b) and the additional support (80) comprises at least one complementary centering surface (84a, 84b) at least partially cylindrical which bears against the cylindrical centering surface.

10. A transmission system (M) according to any one of the preceding claims, wherein the common support (70) has a body (75) and U-shaped support walls (76) arranged in two groups, a first group of two support walls (76) extending circumferentially around the first axis of rotation (XI), and a second group of two support walls (76) extending circumferentially around the second axis of rotation (X2), each support wall (76) has at its end a semi-circular housing (76a) arranged to receive a guide bearing (100a, 100b, 200a, 200b).

11. Transmission system (M) according to the preceding claim, wherein the body (75) of the common support (70) extends partially between the first transmission shaft (10) and the second transmission shaft (20).

12. Transmission system (M) according to any one of the preceding claims, wherein the common support (70) comprises mounting lugs (73) equipped with holes (73a) for attachment to the housing (40), the holes (73a) extending radially beyond the outside diameter of the gear (11) of the first transmission shaft (10).

13. Transmission system (M) according to any one of claims 2 to 12, wherein the additional support (80) comprises a main part (85) and U-shaped additional support walls (86) distributed at both ends of the main part, the two additional support walls (86) extending circumferentially around the third axis of rotation (X3), each additional support wall (86) having at its end a semi-circular housing (86a) arranged to receive a guide bearing (300a, 300b).

14. Transmission system (M) according to claim 13 taken in combination with claim 9, wherein the additional support (80) comprises at least one connecting arm (81) supporting one of the complementary centering surfaces (84a, 84b) and which connects the main part (85) to the common support (70).

15. Transmission system (M) according to any one of claims 2 to 14, wherein the transmission housing (40a) and / or the closing cover (40b) comprise bearing surfaces (41) having shapes adapted to receive fixing lugs (73, 83) of the common support (70) and the additional support (80).

16. Transmission system (M) for a motor vehicle, comprising: - a speed reduction device (R) in which a first transmission shaft (10), provided with a first pinion (11) rotating about a first axis of rotation (XI), and a second shaft transmission (20), provided with an intermediate gear (21) rotating around a second axis of rotation (X2), mesh together and form a first reduction stage; - a third transmission shaft (30), provided with a torque output gear (31) rotating around a third axis of rotation (X3), which meshes with an intermediate pinion (22) of the second transmission shaft (20) and forms with this second transmission shaft a second reduction stage; - a transmission casing (40a) and a closing cover (40b) assembled so as to form a housing (40) defining a housing in which the speed reduction device is received; characterized in that the first transmission shaft (10), the second transmission shaft (20) and the third transmission shaft (30) are supported by a common support (70), said common support (70) being separate from the casing and fixedly supported by the transmission casing (40a).

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