Motor vehicle wheel assembly

Abstract

The invention relates to a motor vehicle wheel assembly comprising: a cradle (12) having two opposing cradle ends; two wheel supports respectively connected to said two cradle ends (46) and adapted to receive a wheel each; two struts respectively surmounting said two wheel supports; a torsion bar (42) having a straight central portion (44) and two angled opposing bar ends (46), said central portion (44) being movably rotatably along said cradle (12). Said cradle (12) further comprises an elastic return element (74) located between said two cradle ends; and said central portion (44) comprises a tab (70) adapted to cooperate with said elastic return element (74) to dampen the simultaneous movement of said wheel supports relative to said cradle (12). Figure to be published with the abbreviation: Fig. 3

Description

Title of the invention: Motor vehicle wheel assembly

[0001] The present invention relates to a front or rear wheel assembly of a motor vehicle.

[0002] One envisaged area of ​​application is, in particular, that of four-wheel drive motor vehicle trains. This type of vehicle is not only suitable for travel on roads, but also off-road, on more or less rugged terrain.

[0003] Also, vehicles of this type include a motorized front wheel assembly and a motorized rear wheel assembly.

[0004] Each wheel assembly comprises a subframe with two opposing ends and two wheel carriers connected to the two ends of the subframe by suspension arms. Each of the two wheel carriers is surmounted by two struts, on which the vehicle body rests. The struts are axially compressible and include a return spring and a damping system. Furthermore, the wheel assembly also includes a torsion bar connecting the opposing suspension arms or the two struts. Its purpose is, in particular, to limit vehicle roll when in motion. It is commonly referred to as an "anti-roll bar."

[0005] The struts also include a "shock absorber," which comprises an elastically deformable element that absorbs energy at the end of the strut's compression stroke. Thus, the "shock absorber" limits the strut's travel during impacts, for example, on a rough road where the vehicle's wheel hits a pothole, or conversely, when the vehicle goes over a speed bump.

[0006] Consequently, the "shock stops" limit the wheel travel, thereby protecting the suspension components. However, this limits the vehicle's axle articulation capabilities, hindering its ability to operate on rough terrain.

[0007] Also, a problem which arises and which the present invention aims to solve is to provide wheel assemblies whose suspension elements are preserved, but also whose axle crossing capabilities are sufficient for the vehicle to be able to move on difficult and rugged terrain.

[0008] In order to solve this problem, and according to a first object, a wheel assembly for a motor vehicle is proposed comprising: a cradle having two opposing cradle ends; two wheel supports respectively connected to said two cradle ends and adapted to receive a wheel each; two struts respectively surmounting said two wheel supports and adapted to be compressed when said wheel supports are driven into motion relative to said cradle; a torsion bar having a straight middle portion and two opposite bar ends bent and symmetrical to each other, said middle portion being installed movable in rotation along said cradle, while said two opposite bar ends are respectively connected to said struts.

[0009] Said cradle further includes an elastic return member located between said two ends of cradle; and said middle part of said torsion bar includes a lug adapted to cooperate with said elastic return member to dampen the simultaneous movement of said wheel supports relative to said cradle.

[0010] Thus, a feature of the invention lies in the implementation of an elastic return element on the subframe and a bracket attached to the torsion bar, which bracket cooperates with the elastic return element. In this way, the elastic return element acts as a "shock absorber" by limiting the rotation of the torsion bar. Consequently, the "shock absorbers" on the struts can be eliminated, resulting in greater wheel travel and, therefore, greater axle articulation capabilities.

[0011] It will be observed that when the vehicle is moving in rough terrain, and in particular in bridge crossing situations, one end of the torsion bar is driven upwards, while the other is driven downwards, and as a result, the area of ​​the middle part receiving the leg remains immobile.

[0012] Conversely, when the vehicle is traveling on a road and encounters, for example, a speed bump, both ends of the torsion bar are stressed in the same direction, and consequently, the bracket comes into contact with the elastic return element. This element then acts as a conventional "bump stop" type of vertical travel limiter.

[0013] Advantageously, and according to the invention, the struts are each additionally equipped with shorter "shock stops". These shorter "shock stops" limit the extreme wheel travel during an asymmetrical impact that only partially activates the elastic return element, without, however, compromising the maximum wheel travel.

[0014] According to a preferred embodiment of the invention, said elastic return element is located substantially equidistant from said two beam ends. Furthermore, the torsion bar's lug is located substantially equidistant from its two ends and thus bears against the elastic return element.

[0015] Advantageously, and according to the invention, said cradle is equipped with two bearings spaced apart to receive said middle portion of said torsion bar. Thus, the two bearings are installed coaxially on the cradle and the two ends the middle part of the torsion bar, which middle part is straight, are mounted to rotate respectively in the two bearings.

[0016] According to a particularly advantageous embodiment of the invention, said cradle is hollow to receive said elastic return element, and furthermore has an opening at the location of said elastic return element to allow passage of said tab. In this way, the elastic return element is installed within a dead volume of the cradle, and consequently, its installation does not result in any change in the position of the conventional wheel assembly components.

[0017] According to the invention, each of the two opposing bar ends has a first portion bent relative to the central portion and a second portion bent relative to the first portion, forming a crank. The second bent portion is connected to the corresponding strut by means of a connecting rod. Consequently, the movement of the strut is adapted to cause the movement of the second bent portion, which then imparts a rotational torque to the central portion of the torsion bar.

[0018] Furthermore, according to the invention, each of the first portions is curved in a plane substantially perpendicular to said central portion. In this way, the ends of the torsion bar are substantially longer and thus offer greater flexibility. In other words, their buckling capacity is increased.

[0019] Furthermore, according to the invention, said two wheel supports are respectively connected to said two ends of the cradle by suspension arms. The suspension arms are pivotally mounted both on the ends of the cradle and also on the wheel supports. In this way, the wheels can oscillate relative to the cradle while remaining vertical.

[0020] According to another object of the invention, a motor vehicle is proposed having a front part and a rear part, and each of said front and rear parts is equipped with a wheel assembly as described above.

[0021] Other features and advantages of the invention will become apparent from the following description of a particular embodiment of the invention, given by way of example but not limitation, with reference to the accompanying drawings in which:

[0022] [Fig.1] is a schematic front view of a wheel assembly at rest according to the invention;

[0023] [Fig.2] is a schematic top view of a wheel assembly according to the invention;

[0024] [Fig.3] is a schematic three-quarter rear perspective view of the wheel assembly cut along the median plane III - III illustrated in [Fig. 1]; and,

[0025] [Fig.4] is a schematic front view of the wheel assembly shown in [Fig.1] in a working position.

[0026] Fig. 1 shows, from the front, a front wheel assembly 10 of a motor vehicle. However, the invention is also suitable for a vehicle's rear wheel assembly.

[0027] The front wheel assembly 10 is in an orthogonal frame X, Y, Z, in which the X axis extends along a front-to-rear longitudinal direction of the motor vehicle, oriented towards the rear; the Y axis extends along a transverse direction of the vehicle, oriented from left to right when in a driving situation; and the Z axis extends along a vertical direction, oriented away from the ground.

[0028] The front wheel assembly 10 includes first of all a cradle 12 extending transversely in the Y direction. The cradle 12 is hollow and has a right end 14 opposite a left end 16. It also has an upper wall 15 opposite a lower wall 17.

[0029] Also, the wheel assembly 10 includes a right lower arm 18 mounted articulated on the right end 14, and a left lower arm 20 mounted articulated on the left end 16 of the cradle 12.

[0030] The end of the right lower arm 18 is mounted articulated on a right wheel support 21, and on the opposite side, the end of the left lower arm 20 is mounted articulated on a left wheel support 23.

[0031] Also, a right wheel 24 installed on the right wheel support 21 and a left wheel 26 installed on the left wheel support 23 have been shown in dashed line.

[0032] The wheel supports 21, 23 are then surmounted respectively by a right strut 28 and a left strut 30.

[0033] The different elements of the struts 28, 30 have the same references because they are identical and they have exactly the same functions.

[0034] Each strut comprises a cylinder 32 directly attached to the wheel supports 21, 23, in which at least one piston connected to a rod slides (these supports are not shown). The rod and the inlet of the cylinder 32 are protected by a bellows 34. The rod bears against an upper cup 36. According to one embodiment of the invention, thin elastomer pieces are interposed between the upper cup 36 and the end of the rod to form shorter "shock stops" than those used in struts according to the prior art.

[0035] Also, each cylinder 32 is provided with a lower cup 38 and a helical spring 40 engages between the lower cup 38 and the upper cup 36.

[0036] Thus, the body of the motor vehicle, not shown, rests on the upper struts 36. Consequently, when the vehicle is in motion, the two struts 28, 30 are adapted to compress axially and to extend along the vertical component Z, and to oscillate around their equilibrium position. The piston and the moving rod inside the cylinder 32 are precisely adapted to dampen these oscillations.

[0037] In addition, the wheel assembly 10 includes a torsion bar 42 extending transversely along the cradle 12. It is made of steel. Also, it has a substantially circular cross-section with a diameter between, for example, 4 cm and 6 cm in diameter.

[0038] Figure 2 shows the front wheel assembly 10 without its struts. The subframe 12 is also shown. It has a front wall 43 opposite a rear wall 45. Also, the torsion bar 42 is shown in more detail, which has a straight central portion 44 and a right-hand bar end 46 symmetrical to a left-hand bar end 48 with respect to the median plane III - III.

[0039] The middle part is mounted for rotation in two bearings 50, 52 spaced apart and mounted on the upper wall 15 of the cradle 12, so that the middle part 44 extends transversely in the direction Y.

[0040] In addition, the end of the straight bar 46 has a first straight portion 54 bent towards the front of the vehicle in the direction -X, and substantially at a right angle to the middle portion 44, and a second straight portion 56 extending the first portion 54 and bent back at a right angle to the first portion 54. The second portion 56 thus extends in a direction substantially parallel to the middle portion 44, forming a crank.

[0041] Similarly, on the opposite side, the left end of the bar 48 has a first left portion 58 bent towards the front of the vehicle substantially parallel to the first portion 54, and substantially at a right angle to the middle portion 44, and a second left portion 60 extending the first portion 58 and bent back at a right angle to the first portion 58. The second portion 60 extends in a direction substantially parallel to the middle portion 44, also forming a crank.

[0042] Also, the second right portion 56 of the right bar end 46 terminates with a free right end 62, while on the opposite side, the second left portion 60 of the left bar end 48 terminates with a free left end 64.

[0043] In [Fig. 1], it will be observed that the first right portion 54 of the right bar end 46 and the first left portion 58 of the left bar end 48 form substantially an arc of a circle. This arc of a circle defines a plane substantially perpendicular to the mid-section 44 of the torsion bar 42. Also, the concave portion of this arc of a circle is oriented towards the cradle 12.

[0044] We also find on [Fig.1], the two free ends, right 62, and left 64 of the second right portions 56 and left 60 of the respective ends 46, 48 of the torsion bar 42.

[0045] Also, the right free end 62 is connected to the cylinder 32 of the right strut 28 by means of a right connecting rod 66, while the left free end 64 is connected to the cylinder 32 of the left strut 30 by means of a left connecting rod 68. These two connecting rods 66, 68 extend along a vertical component Z.

[0046] In addition, in accordance with the invention, a leg 70 attached to the middle part 44 of the torsion bar 42 appears on [Fig.1]. The leg 70 is located substantially equidistant from the two ends 46, 48 of the torsion bar 42 and it penetrates through the upper wall 15 into the cradle 12 as will be explained below with reference to [Fig.3].

[0047] Thus, we find in cross-section on [Fig.3], the cradle 12 and the middle part 44 of the torsion bar 42, which middle part 44 is extended by the first straight portion 54 of the end of the straight bar 46.

[0048] We then find the leg 70 attached to the middle part 44 and extending along a vertical component through a light 72 made in the upper wall 15 of the cradle 12. Thus, the leg 70 extends between the front wall 43 and the rear wall 45 of the cradle 12, and closer to the rear wall 45.

[0049] Furthermore, inside the cradle 12, an elastic return element 74 is installed, interposed between the front wall 43 and the leg 70. In one embodiment, the elastic return element 74 is a helical spring. In another embodiment, the elastic return element 74 is made of an elastomeric polymer material, for example, polyurethane. A combination of a polymer material and a helical spring is also envisaged.

[0050] It is thus understood, in view of the elements described above with regard to [Fig.3], that the rotational movement of the torsion bar 42 in the clockwise direction H causes the pivoting of the leg 70 inside the cradle 12 towards the front wall 43. And consequently, this rotational movement of the torsion bar 42 causes the compression of the elastic return member 74. The latter thus tends to oppose this rotation as will be explained below with reference to [Fig.1].

[0051] Thus, when the right wheels 24 and left wheels 26 of the wheel assembly 10 simultaneously or almost simultaneously approach a speed bump for example, taking into account the inertia of the vehicle moving in a straight line parallel to the surface of the road on which it travels, these right wheels 24 and left wheels 26 are driven more or less abruptly according to a vertical component +Z, while the two corresponding struts 28, 30 are compressed axially.

[0052] As a result, the two connecting rods right 66 and left 68 exert two upward forces respectively on the two free ends, right 62, and left 64 of the second right portions 56 and left 60 of the respective ends 46, 48 of the torsion bar 42.

[0053] Accordingly, the middle part 44 of the torsion bar 42 is driven in rotation following the clockwise direction H as illustrated in [Fig.3] to which reference should be made again. Thus, the leg 70 is driven in pivot towards the front wall 43 of the cradle 12 and thereby compresses the elastic return member 74. The latter, by compressing itself, opposes the pivoting movement of the leg 70. Consequently, it absorbs the shock caused by the contact of the two wheels 24, 26 of the aforementioned hump.

[0054] Thus, it is possible to do away with the "shock stops" usually implemented in conventional wheel assemblies.

[0055] On the other hand, in situations such as those illustrated in [Fig.4], where the wheel assembly 10 of the vehicle is subjected to cross-level movement, the absence of usual "shock stops" allows for a greater range of wheel travel.

[0056] The wheel assembly 10, as described opposite [Fig. 1], is thus found in a situation where the right wheel 24 is driven vertically along the upward vertical component +Z, while conversely, the left wheel 26 is driven vertically along the downward component -Z. Such a situation occurs when, conversely, the rear wheel assembly, not shown, is inclined in the opposite direction; in other words, when the right rear wheel is lowered while the left rear wheel is raised. In other words, the two wheel assemblies are inclined in opposite directions; this situation is described as: "bridge crossing".

[0057] As a result, the right strut 28 not shown in [Fig.4] is compressed to the maximum, without being prevented by a "shock stop", and therefore, it drives, according to a maximum amplitude, the free right end 62 of the second right portion 56 of the right bar end 46 via the right connecting rod 66 along the upward vertical component +Z.

[0058] Conversely, the left wheel 26 is driven vertically along the downward vertical component -Z. As a result, the left strut 30 not shown in [Fig.4] is in maximum extension, and it drives, with maximum amplitude, the left free end 64 of the second left portion 60 of the left bar end 48 via the left connecting rod 68 along the downward vertical component -Z.

[0059] Consequently, the torsion bar 42 is precisely driven in torsion and performs its elastic return function. Conversely, the portion of the central part 44 to which the lug 70 is attached, which portion is located approximately equidistant from the two right 46 and left 48 ends of the torsion bar 42, is neutral. Therefore, it remains in a fixed position and the lug 70 is not driven in pivot.

[0060] In this way, the range of motion of the two wheels 24, 26 is greater than it is when the struts are equipped with conventional "shock stops".

Claims

Demands

1. Wheel assembly (10) of a motor vehicle comprising: - a cradle (12) having two opposite cradle ends (14, 16); - two wheel supports (21, 23) respectively connected to said two cradle ends (46, 48) and adapted to each receive a wheel (24, 26); - two struts (28, 30) respectively surmounting said two wheel supports (21, 23) and adapted to be compressed when said wheel supports are driven in motion relative to said cradle (12); - a torsion bar (42) having a straight middle portion (44) and two opposite bar ends (46, 48) bent and symmetrical to each other, said middle portion (44) being installed movable in rotation along said cradle (12), while said two opposite bar ends (46, 48) are respectively connected to said struts (28, 30);characterized in that said cradle (12) further comprises an elastic return member (74) located between said two ends of cradle (14, 16); and in that said middle part (44) of said torsion bar (42) comprises a lug (70) adapted to cooperate with said elastic return member (74) to dampen the simultaneous movement of said wheel supports (21, 23) relative to said cradle (12).

2. Wheel train according to claim 1, characterized in that said elastic return member (74) is located substantially equidistant from said two ends of cradle (14, 16).

3. Wheel assembly according to claim 1 or 2, characterized in that said cradle (12) is equipped with two bearings (50, 52) spaced apart to receive said middle part (44) of said torsion bar (42).

4. Wheel assembly according to any one of claims 1 to 3, characterized in that said cradle (12) is hollow to receive said elastic return member (74), and in that it further has an opening (72) at the right of said elastic return member (74) to allow passage of said lug (70).

5. Wheel assembly according to any one of claims 1 to 4, characterized in that each of said two opposite bar ends

6.

7.

8. (46, 48) has a first portion (54, 58) bent in relation to said middle portion (44) and a second portion (56, 60) bent in relation to said first portion (54, 58) forming a crank. Wheel train according to claim 5, characterized in that each of the first portions (54, 58) is curved in a plane substantially perpendicular to said middle part (44). Wheel assembly according to any one of claims 1 to 6, characterized in that said two wheel supports (21, 23) are respectively connected to said two ends of cradle (14, 16) by suspension arms (18, 20). Motor vehicle having a front part and a rear part, characterized in that each of said front and rear parts is equipped with a wheel assembly (10) according to any one of claims 1 to 7.

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