Front or rear axle for a vehicle equipped with an epicyclic gear train coaxial with the differential

Abstract

The invention relates to a front or rear axle (18) for a vehicle with front or rear-wheel drive, said axle (18) comprising a housing (40) at least partially enclosing: - an input shaft (42), - two output shafts (52) for driving the vehicle's wheels, - a differential (54), - a bevel gear (44) meshing with the input shaft (42) and capable of transmitting a rotational motion from the input shaft (42) to the differential (54), characterized in that the axle (18) comprises, housed within the housing (40), an epicyclic gear train (58) coaxial with the output shafts (52) for driving the wheels, this epicyclic gear train (58) being interposed between the bevel gear (44) and the differential (54) to transmit a rotational motion from the bevel gear (44) to the differential (54) for the rotational drive of one or both of the output trees (52). Figure for the abbreviation: Figure 3

Description

Title of the invention: Front or rear axle for a vehicle equipped with an epicyclic gear train coaxial with the differential. Technical field

[0001] The present invention relates to a front or rear axle of a vehicle. In particular, the present invention relates to a front or rear axle comprising a differential allowing the wheels to rotate at the same or different speeds. Technological background

[0002] A front or rear axle of a motor vehicle transmits the rotational motion and torque supplied by the engine to the wheels via a differential. The rotational speed supplied to each wheel of the same axle by the differential is identical or different depending on the requirements, particularly when turning, where the inside wheel does not travel the same distance as the outside wheel.

[0003] The axle is a critical component on a motor vehicle because the power developed by the engine is transmitted to it, which can lead to problems with mechanical strength and / or lifespan. These difficulties are exacerbated for vehicles with high engine power. This is particularly true for motor vehicles used in rally raids.

[0004] It is known to transmit power from the gearbox (rotational motion and torque) located between the axle and the engine via a bevel gear. This power transmission can be direct or indirect, notably via a reduction stage between the gearbox and the axle (also called a "transfer case"). This bevel gear can mesh directly with the differential housing to transmit the engine's rotational motion to the differential.

[0005] Such a known configuration is shown in [Fig. 2]. The input rotational motion is transmitted to an input shaft 30, which can transmit this rotational motion directly or via a meshing stage 32 to a bevel gear 34. This bevel gear 34 comprises a drive bevel gear 35 that meshes directly with the differential housing 36 of the differential 38. Thus, the differential housing 36 of the differential 38 carries a transmission bevel gear 37 that is rotationally fixed to the differential housing 36 of the differential 38. The output shafts 39 of the differential 38 allow the transmission of this rotational motion to the wheels.

[0006] It has been observed that in cases of use with high stress (e.g. vehicle in rally raid) that the bevel gear had a very limited lifespan, despite resizing or adjustments of the parts involved.

[0007] Another identified drawback of existing front or rear axle solutions is their lack of compactness, which constrains the overall vehicle layout by manufacturers. Indeed, greater axle compactness facilitates their integration into the vehicle, lowers the vehicle's center of gravity, and minimizes the angles of the lateral wheel shafts.

[0008] Finally, it is desirable to increase the torque transmission capacity of the bridge without increasing its overall size, which is difficult to achieve with existing solutions that are already showing their limitations. Indeed, a solution consisting of increasing the dimensions of the bridge to increase its torque transmission capacity is not feasible because its environment is restricted.

[0009] There is therefore a need for a front or rear vehicle axle that does not have the aforementioned disadvantages. Summary of the invention

[0010] The invention provides for this purpose a front axle, or respectively a rear axle, for a vehicle with front or respectively rear-wheel drive, said axle comprising a housing containing at least partially: - an input shaft capable of engaging with a gearbox output shaft to transmit rotational motion to the input shaft, - two output shafts for driving the vehicle's wheels, - a differential comprising a differential housing, the differential being disposed between the output shafts and configured to allow the rotation of each output shaft at the same or different speeds, - a bevel gear meshing with the input shaft and capable of transmitting a rotational movement from the input shaft to the differential, characterized in that the bridge comprises housed inside the casing an epicyclic gear train coaxial with the wheel drive output shafts, this epicyclic gear train being interposed between the bevel gear and the differential to transmit a rotational movement from the bevel gear to the differential for the rotational drive of one or both of the output shafts.

[0011] Adding an epicyclic gear train between the differential and the bevel gear allows for an additional torque reduction stage. This increases the torque transmitted to the differential while reducing the torque experienced by the bevel gear. Reducing the torque experienced by the bevel gear also increases its lifespan and, consequently, the overall lifespan of the axle.

[0012] The implantation of an epicyclic train coaxial with the differential makes it possible to improve the compactness of the bridge while benefiting from the increase in the torque transmitted to the differential.

[0013] The axle can be a front-wheel drive axle and / or a rear-wheel drive axle. The axle is therefore suitable for a four-wheel drive vehicle.

[0014] The differential housing is guided in rotation relative to the casing by means of guide elements. The epicyclic gear train transmits to the differential housing the rotational movement from the bevel gear so as to transmit a rotational movement to the output shafts, at the same or different speed.

[0015] The input shaft is preferably oriented towards the gearbox. The input shaft extends, for example, along the longitudinal axis of the vehicle. The input shaft may extend along a direction that has an angular offset from a horizontal plane for reasons of component arrangement.

[0016] The epicyclic gear train may comprise a first transmission gear, at least one planet gear, a planet carrier, and a second transmission gear. Said at least one planet gear is mounted for rotation on the planet carrier and configured to mesh with the first and second transmission gears, the rotational motion of the first transmission gear being transmitted to said at least one planet gear, which then transmits it to the second transmission gear.

[0017] The first transmission gear may have internal or external teeth. Similarly, the second transmission gear may have internal or external teeth.

[0018] The satellite may have one or more gears. Thus, the satellite may comprise a plurality of, for example, two gears mounted on a satellite body that is rotatably mounted on the satellite carrier. The satellite's gears may have a different number of teeth.

[0019] According to one embodiment, the first transmission gear is an external toothed ring, and the second transmission gear is a planetary gear, the planetary gear being meshed with the satellite itself being meshed with the external toothed ring.

[0020] The term "external toothed ring" refers to an internal toothed surface adapted to mesh with a gear arranged within that internal toothed surface. The planetary gears are therefore arranged inside the external toothed ring. An external toothed ring is an external gear.

[0021] The term "planetary" means an internal toothed ring, i.e., an external toothed surface capable of meshing with a toothed wheel disposed outside this external surface. toothed. The satellites are therefore arranged around the planetary gear. The inner toothed ring or planetary gear is an internal toothed wheel.

[0022] The term "coaxial with the output shafts" means that the main axis of rotation of the planetary gears around the planetary gear coincides with the axis of rotation of the output shafts. The main axis of rotation of the planetary gears is distinct from the secondary axis of rotation of the planetary gears about themselves.

[0023] The bevel gear may include a drive bevel gear and a transmission bevel gear.

[0024] Said bridge may further include an interface piece disposed between the bevel gear and the epicyclic gear train.

[0025] The interface piece is preferably coaxial with the differential housing

[0026] The interface piece is preferably configured to move in rotation around The differential housing is driven by the bevel gear and this rotation is transmitted to the epicyclic gear train. This interface piece connects the bevel gear to the epicyclic gear train.

[0027] The interface piece can form an internal cavity configured to receive all or part of the differential housing. In other words, the interface piece can be hollow to receive all or part of the differential housing. The interface piece can therefore extend around the differential housing. The arrangement of the interface piece around the differential housing allows for a more compact design while still enabling the transmission of rotational motion and torque from the bevel gear.

[0028] The interface piece preferably comprises a cylindrical hollow body extending around an axis of revolution coaxial with the wheel drive output shafts when the interface piece is in the operating position.

[0029] The interface piece can further carry one of the external toothed ring, the planet carrier and the planetary gear of the epicyclic train.

[0030] The interface piece may comprise a cylindrical body and an interface toothed ring, said interface toothed ring being either the transmission bevel gear in direct contact with the drive bevel gear, or an external toothed wheel in contact with a straight toothed wheel rotationally fixed to the transmission bevel gear.

[0031] The outer toothed ring can be fixed in rotation relative to the housing, the planet carrier being rotationally fixed to the differential housing, the planetary gear being rotationally fixed to the interface piece.

[0032] The interface piece can be rotationally fixed to the external toothed ring.

[0033] The planet carrier can be rotationally fixed to the differential housing, the planetary gear being fixed relative to the housing.

[0034] Alternatively, the planet carrier can be fixed relative to the housing, the planetary gear being in rotation of the differential housing.

[0035] The outer toothed ring can be rotationally fixed to the differential housing, the planet carrier being fixed relative to the housing, the planet being rotationally fixed to the interface piece.

[0036] The outer toothed ring can be fixed relative to the housing, the planetary gear being rotationally fixed to the differential housing, the planet carrier being rotationally fixed to the interface piece.

[0037] The outer toothed ring can be rotationally fixed to the differential housing, the planetary gear being fixed relative to the housing, the planet carrier being rotationally fixed to the interface piece.

[0038] The differential may be of the self-locking or limited-slip type. The differential may also be of the free-spinning type.

[0039] The differential may include two clutches arranged in the differential housing.

[0040] When a part A is "rotationally fixed" to a part B, it is understood that the rotational speeds of parts A and B are identical. Thus, parts A and B may be one and the same part. Alternatively, parts A and B may be separate and cooperate to transmit this rotational motion. This cooperation may be a fixed assembly of part A with part B or a rigid coupling. Brief description of the figures

[0041] The following description, with reference to the accompanying drawings, given by way of non-limiting examples, will clearly explain what the invention consists of and how it can be implemented. In the accompanying figures:

[0042] [Fig-1] Fig. 1 represents a schematic perspective view of a system of motorization and transmission of a vehicle comprising an engine, a gearbox, a front axle and a rear axle, each arranged between a pair of wheels of the vehicle;

[0043] [Fig.2] Fig.2 represents a diagram of a known vehicle bridge;

[0044] [Fig.3] The [Fig.3] a diagram of a first embodiment of a vehicle bridge;

[0045] [Fig.4] Fig.4 represents a diagram of a first embodiment of a vehicle bridge, comprising a cascade shaft between a gearbox output shaft and a bridge input shaft;

[0046] [Fig.5] [Fig.5] A partial exploded view of the bridge of [Fig.3], the exploded view representing a portion of the casing, the bevel gear for transmitting the gear conical, epicyclic gear train, differential and wheel drive output shafts;

[0047] [Fig.6] Figure [Fig.6] shows a diagram of a second embodiment of a vehicle bridge;

[0048] [Fig.7] Figure [Fig.7] shows a diagram of a third embodiment of a bridge for vehicle;

[0049] [Fig.8] Figure [Fig.8] represents a diagram of a fourth embodiment of a vehicle bridge;

[0050] [Fig.9] Figure [Fig.9] represents a diagram of a fifth embodiment of a vehicle bridge;

[0051] [Fig. 10] Figure 10 represents a diagram of a sixth embodiment of a vehicle bridge. Description of method(s) of implementation

[0052] For the sake of clarity, the same references designating the same elements according to the state of the art and according to the invention are used for all figures.

[0053] The concept of the invention is described more fully below with reference to the accompanying drawings, in which embodiments of the concept of the invention are shown. In the drawings, the size and relative sizes of the elements may be exaggerated for clarity. Similar numbers refer to similar elements in all the drawings. However, this concept of the invention can be implemented in many different forms and should not be construed as being limited to the embodiments set forth herein. Rather, these embodiments are offered so as to make this description complete and to communicate the scope of the concept of the invention to those skilled in the art.

[0054] A reference throughout the specification to "an embodiment" means that a particular feature, structure, or characteristic described in relation to an embodiment is included in at least one embodiment of the present invention. Thus, the appearance of the phrase "in an embodiment" in various places throughout the specification does not necessarily refer to the same embodiment. Furthermore, the particular features, structures, or characteristics may be combined in any suitable manner in one or more embodiments. Moreover, the term "including" does not exclude other elements or steps.

[0055] With reference to [Fig. 1], a powertrain and transmission system 10 of a vehicle 12 comprises an engine 14 coupled to a gearbox 16. The gearbox 16 may include an additional reduction ratio called a "transfer case". This transfer case may be integrated into the gearbox housing 16 as shown in [Fig. 1] or separated into a separate housing.

[0056] The motorization and transmission system 10 includes two axles 18 for transmitting the rotational movement of the gearbox to the wheels 19. In particular, a front axle 20 is arranged between the front wheels 21 of the vehicle 12 and a rear axle 22 is arranged between the rear wheels 23. The vehicle 12 here includes four-wheel drive.

[0057] The vehicle 12 defines a longitudinal axis of vehicle A extending between the front wheels 21 and the rear wheels 23 of the vehicle 12.

[0058] The axle 18 according to the present invention is indifferently a rear axle or a front axle of a vehicle. This distinction will not be made in the remainder of the description, which will refer only to an axle 18.

[0059] With reference to [Fig.3], the bridge 18 includes a housing 40 forming an outer casing allowing the fixing and mounting of the bridge 18 in a vehicle 12. The housing 40 is mounted so as to be fixed relative to the chassis of the vehicle.

[0060] The bridge 18 includes an input shaft 42 driven in rotation with an output shaft of the gearbox so as to transmit a rotational movement to this input shaft 42.

[0061] This input shaft 42 can be directly or indirectly rotationally fixed to the gearbox. Indeed, with reference to [Fig. 4], a cascade shaft 45 can be added between the gearbox and the input shaft 42. The cascade shaft 45 includes a toothed wheel allowing for the addition of a gear stage.

[0062] The input shaft 42 is guided in rotation relative to the housing 40 by means of a plurality of guide elements 43.

[0063] The input shaft 42 is oriented towards the gearbox. The input shaft 42 extends, for example, along the longitudinal axis of vehicle A. The input shaft can extend along a direction that has an angular offset from a horizontal plane.

[0064] The bridge 18 also includes two output shafts 52 for driving wheels 19 of the vehicle 12.

[0065] The bridge 18 further includes a differential 54 comprising a differential housing 56. The differential 54 is disposed between the output shafts 52.

[0066] The differential 56 is configured to allow the rotation of each output shaft 52 at the same or different speeds. The output shafts extend along an output axis B. The output axis B preferably coincides with the axis of the differential 54.

[0067] The bridge 18 also includes an epicyclic gear train 58 arranged coaxially with the output shafts 52. The epicyclic gear train 58 is mounted on the differential housing 56 so as to transmit a rotational motion from the input shaft 42 to differential 54 for the rotational drive of one or both of the output shafts 52.

[0068] The bridge 18 also includes a bevel gear 44. The bevel gear 44 is disposed or interposed between the input shaft 42 and the epicyclic gear train 58. Put another way, the epicyclic gear train 58 is interposed between the bevel gear 44 and the differential 54.

[0069] The bevel gear 44 comprises a drive bevel gear 46 and a transmission bevel gear 48. The drive bevel gear 46 extends, for example, perpendicularly to the transmission bevel gear 48. More generally, the axes of rotation of the drive bevel gear 46 and transmission bevel gear 48 have an angle other than 0° between them.

[0070] The bevel drive wheel 46 is carried by the input shaft 42. The bevel drive wheel 46 therefore extends around the input shaft 42.

[0071] The conical transmission wheel 48 is supported by an interface piece 50.

[0072] The interface piece 50 is disposed between the bevel gear 44 and the train epicyclic gear 58. The interface piece 50 is coaxial with the differential housing 56. More specifically, the interface piece 50 is configured to rotate around the differential housing 56 under the action of the bevel drive wheel 46 and transmit this rotation to the epicyclic gear train 58. This interface piece 50 provides the connection between the bevel gear 44 and the epicyclic gear train 58.

[0073] According to a possible alternative, the interface piece 50 can carry teeth configured to mesh with teeth carried by an intermediate shaft interposed between the input shaft 42 and the interface piece 50. In this case, the intermediate shaft carries the transmission bevel gear 48.

[0074] The interface piece 50 comprises a hollow cylindrical body 60 extending around an axis of revolution coaxial with the output shafts 52. The conical transmission wheel 48 is attached and fixed to the body 60.

[0075] The interface piece 50 is guided in rotation relative to the housing by means of guide elements.

[0076] The epicyclic gear train 58 comprises an outer toothed ring 64, at least one planet gear 62, a planet carrier 66, and a sun gear 68. The rotational movement resulting from the bevel gear 44 is transmitted to the sun gear 68, which meshes with the planet gears 62, themselves meshed with the outer toothed ring 64. According to the configurations described below with reference to the embodiments, the outer toothed ring 64, the planet carrier 66, and the sun gear 68 can each be mounted and secured to the interface piece 50, the housing 40, or the differential housing 56.

[0077] A first embodiment is shown in figures 3 and 4. The planetary gear 68 is carried by and fixed in rotation to the interface piece 50.

[0078] The planet carrier 66 is rotationally fixed to the differential housing 56. The external toothed ring 64 is fixed relative to the housing 40.

[0079] An exploded view of a portion of the housing 40 containing the differential 54, the output shafts 52, the epicyclic gear train 58 and the interface piece 50 is visible in [Fig.5].

[0080] The interface piece 50 is here in two parts. A first part 70 comprises a first body 71 on which the bevel gear 48 is mounted. A second part 72 comprises a second body 73 on which the planetary gear 68 is formed or mounted. The first 70 and second 72 parts are configured to be rotationally fixed to each other.

[0081] The planet carrier 66 has several cavities in which the planets are mounted to rotate freely about themselves. The planet carrier 66 extends coaxially to the output shafts 52, and preferably around the differential 54 and / or one of the output shafts 52.

[0082] A second embodiment is shown in [Fig.6]. The planetary gear 68 is here rotationally fixed to the differential housing 56. The planet carrier 66 is rotationally fixed to the interface piece 50 and the outer toothed ring 64 is fixed relative to the housing 40.

[0083] In a third embodiment visible in [Fig.7], the planet carrier 66 is also rotationally fixed to the interface piece 50. However, the planet 68 is fixed relative to the housing 40 and the outer toothed ring 64 is rotationally fixed to the differential housing 56.

[0084] In a fourth embodiment shown in [Fig.8], the outer toothed ring 64 is rotationally fixed to the interface piece 50. The planet carrier 66 is rotationally fixed to the differential housing 56. The planet gear 68 is fixed relative to the housing 40.

[0085] In a fifth embodiment shown in [Fig.9], the outer toothed ring 64 is rotationally fixed to the differential housing 56. The planet carrier 66 is fixed relative to the housing 40. The planet gear 68 is rotationally fixed to the interface piece 50.

[0086] In a sixth embodiment shown in [Fig. 10], the outer toothed ring 64 is rotationally fixed to the interface piece 50. The planet carrier 66 is fixed relative to the housing 40. The planet gear 68 is rotationally fixed to the differential housing 56.

[0087] In each of the first, second, third, fourth, fifth and sixth embodiments, a cascade shaft 45 illustrated in [Fig.4] can be arranged between the input shaft 42 and the output shaft of the gearbox.

Claims

Demands

1. Front axle (18), or respectively rear axle, for a vehicle (12) with front or respectively rear driven wheels, said axle (18) comprising a housing (40) housing at least partially: - an input shaft (42) adapted to mesh with an output shaft of a gearbox (16) to transmit a rotational motion to the input shaft (42), - two output shafts (52) for driving wheels (19) of the vehicle (12), - a differential (54) comprising a differential housing (56), the differential (54) being disposed between the output shafts (52) and configured to allow the rotational drive of each output shaft (52) at the same or different speeds, - a bevel gear (44) meshing with the input shaft (42) and adapted to transmit a rotational motion from the input shaft (42) to the differential (54),characterized in that the bridge (18) comprises, housed inside the casing (40), an epicyclic gear train (58) coaxial with the output shafts (52) for wheel drive, this epicyclic gear train (58) being interposed between the bevel gear (44) and the differential (54) to transmit a rotational movement from the bevel gear (44) to the differential (54) for the rotational drive of one or both of the output shafts (52).

2. Bridge according to claim 1, wherein the epicyclic gear train (58) comprises a first transmission gear, at least one planet (62), a planet carrier (66) and a second transmission gear, said at least one planet (62) being mounted in rotation on the planet carrier and configured to be in mesh with the first and second transmission gears, the rotational motion of the first transmission gear being transmitted to said at least one planet (62) which then transmits it to the second transmission gear.

3. A bridge (18) according to claim 2, wherein the first transmission gear is an external ring gear (64), and the second transmission gear is a planetary gear (68), the planetary gear (68) being meshed with the planetary gear (62) itself engaged by meshing with the outer toothed ring (64).

4. Bridge (18) according to claim 2 or 3, wherein the bevel gear (44) comprises a bevel drive wheel (46) and a bevel transmission wheel (48), said bridge (18) further comprising an interface piece (50) disposed between the bevel gear (44) and the epicyclic gear train (58).

5. Bridge (18) according to claim 4, wherein the interface piece (50) is coaxial with the differential housing (56) and configured to move in rotation around the differential housing (56) under the action of the bevel drive wheel (46) and transmit this rotation to the epicyclic gear train (58).

6. Bridge (18) according to claim 4 or 5, wherein the interface piece (50) forms an internal cavity configured to receive all or part of the differential housing (56).

7. Bridge (18) according to any one of claims 4 to 6 in combination with claim 3, wherein the interface piece (50) further carries one of the outer toothed ring (64) and the planetary (68) of the epicyclic gear train (58).

8. Bridge (18) according to claim 7, wherein the outer toothed ring (64) is fixed in rotation relative to the housing (40), the planet carrier (66) being rotationally fixed to the differential housing (56), the planet (68) being rotationally fixed to the interface piece (50).

9. Bridge (18) according to claim 7, wherein the interface piece (50) is rotationally fixed to the outer toothed ring (64), the planet carrier s (66) being rotationally fixed to the differential housing (56) and the planetary gear (68) being rotationally fixed relative to the housing (40).

10. Bridge (18) according to claim 7, wherein the outer toothed ring (64) is rotationally fixed to the differential housing (56), the planet carrier (66) being rotationally fixed relative to the housing (40), the planet (68) being rotationally fixed to the interface piece (50).

11. Bridge (18) according to any one of the preceding claims in combination with claim 4, wherein the interface piece (50) comprises a cylindrical body and an interface toothed ring, said interface toothed ring being either 12 the conical transmission wheel (48) in direct contact with the conical drive wheel (46), i.e. an external toothed wheel in contact with a toothed wheel fixed in rotation to the conical transmission wheel (48).

12. Axle (18) according to any one of the preceding claims, wherein the differential (54) comprises two clutches disposed in the differential housing (56), the differential (54) being of the self-locking or limited-slip type.

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