Leaf spring vehicle suspension system

Abstract

A vehicle axle suspension system comprising a leaf spring; each end of the leaf spring being fixed to one of the mounting brackets (26) by means of a pivot joint via a pivot pin (38), and at least one of the mounting brackets (26) having at least one extended opening (28) such that it permits movement of the pivot pin (38) passing through it, so that said pivot pin (38) can slide between a rest position (72) and a movement position (74). Figure to be published with the abbreviation: Figure 4

Description

Title of the invention: Leaf spring vehicle suspension system

[0001] The invention relates to a vehicle axle suspension system. More specifically, the invention relates to a leaf spring suspension system for a rear vehicle axle. The invention also relates to a vehicle comprising such a suspension system.

[0002] Some vehicles are equipped with suspension systems that include leaf springs to ensure their contact with the ground. A vehicle suspension with leaf springs is a type of suspension system commonly used in heavy vehicles such as trucks and trailers, but not exclusively; this type of suspension can also be used in light motor vehicles.

[0003] A leaf spring consists of several overlapping metal sheets, curved in an arc shape and fixed together. The sheets (or blades) can be of different lengths, the longest being called the "master leaf". They are arranged so that the blades extend along the longitudinal direction of the vehicle.

[0004] The leaf springs of such suspension systems absorb and distribute loads and shocks. They support the weight of the vehicle and maintain the chassis height in terms of ground clearance. For this purpose, they are connected to both the vehicle chassis and the axle (whether the axle is rigid or swing axle). The leaf springs are connected at their central section to the vehicle axle by means of a bracket-type mounting device.

[0005] The leaf spring is attached to the chassis at its ends, generally at the ends of the longer leaf. Leaf springs are attached to the vehicle chassis at the front and rear. The front is often rigidly attached to its support by a simple pivot joint, while the rear is attached by a hinge involving a double pivot joint, allowing the spring to extend and retract in response to suspension movements. It is also possible for both ends of the leaf spring to be attached to the chassis by means of mounting brackets allowing a double pivot joint.

[0006] An example of a suspension unit comprising a leaf spring is described in document EP3698998.

[0007] Suspension systems incorporating leaf springs are simple and easy to maintain. Unfortunately, by design, while the leaf spring exhibits high stiffness enabling it to support heavy loads, it does not provide much travel. Consequently, it is not very satisfactory in terms of comfort. This makes it rarely used for light motor vehicles. A solution therefore needs to be found to improve this situation.

[0008] The invention aims to address at least one of the problems or drawbacks encountered in the prior art. In particular, the invention aims to provide a leaf spring suspension system offering improved driving comfort compared to known systems.

[0009] To this end and according to a first aspect, the invention proposes a vehicle axle suspension system, comprising a leaf spring with a front end and a rear end, the suspension system further comprising two mounting supports distributed into a front mounting support and a rear mounting support and intended to be fixed to a vehicle chassis, each of the front and rear ends of the leaf spring being fixed to one of the two mounting supports by a pivot joint by means of a pivot axis, notable in that at least one of the two mounting supports shows at least one orifice extended in that it allows a movement of the pivot axis passing through it, so that said pivot axis can slide between a rest position and a movement position.

[0010] As will be understood from the definition just given, the invention is remarkable in that it offers a mounting bracket allowing for additional suspension travel compared to that provided by the leaf spring alone. This additional travel, combined with the flexibility of the flat spring, results in improved driving comfort. The perceived quality of the vehicle is enhanced.

[0011] Document FR3055878 B1 describes a half-axle comprising a shock absorber and a spring, the ends of the shock absorber being articulated respectively to the vehicle chassis and the lower control arm. This solution applies to a trailing arm type suspension and not to a leaf spring suspension.

[0012] According to one embodiment, the fixing support showing at least one extended orifice further includes an elastic means configured to return the pivot axis to the rest position.

[0013] According to one embodiment, the extended orifice(s) are configured so that the movement takes place in a vertical direction.

[0014] According to one embodiment, the movement takes place between a low position and a high position, and the rest position is the low position.

[0015] According to one embodiment, the mounting bracket showing at least one extended hole is the rear mounting bracket.

[0016] According to one embodiment, the pivot axis passing through the extended orifice(s) is part of a double pivot joint showing a parallel upper pivot axis and a parallel lower pivot axis, such that the upper pivot axis passes through the or the extended orifices and the lower pivot axis be connected to one end of the leaf spring; preferably, to the rear end of the leaf spring.

[0017] According to one embodiment, the elastic means is chosen from a compression spring or a tension spring; preferably, the elastic means is a compression spring.

[0018] According to one embodiment, the elastic means is chosen from a helical spring or a flat spring; preferably, the elastic means is a flat spring.

[0019] Preferably, the elastic means is a flat spring configured to bend when a sufficient force is applied to its center, and the mounting support showing at least one extended orifice includes two retaining edges configured to form a guide receiving the flat spring and capable of guiding it in its bending movement.

[0020] Preferably, the elastic means is a flat spring configured to bend when a sufficient force is applied at its center, and the mounting support showing at least one extended orifice includes at least one slide configured to guide the flat spring in its bending movement, said flat spring including at least one guide rib configured to fit into the or at least one of the slides.

[0021] According to one embodiment, the mounting bracket showing at least one extended orifice comprises a retaining sleeve through which the pivot axis passes, said retaining sleeve passing through the extended orifice(s) and being able to slide within said extended orifice. Preferably, the retaining sleeve comprises two lateral flanges configured to guide the retaining sleeve in its sliding movement.

[0022] According to one embodiment, the extended orifice(s) show an oblong shape or a T-shaped shape.

[0023] According to one embodiment, a clearance height is between 2 and 30 mm, preferably between 5 and 20 mm.

[0024] According to one embodiment, the suspension system includes a shock absorber with a strut.

[0025] According to a second aspect, the invention proposes a vehicle, remarkable in that it includes at least one suspension system according to the first aspect.

[0026] Preferably, the or at least one of said suspension systems is associated with a rear axle.

[0027] Preferably, the or at least one of said suspension systems is associated with a rigid axle or an oscillating axle.

[0028] Each feature introduced by the expression "preferably" given in relation to one of the aspects of the invention applies to all other aspects of the invention.

[0029] The invention will be well understood and other aspects and advantages will become clear upon reading the following description, given with reference to the attached figures listed below.

[0030] Fig. 1 is a side view of a vehicle according to the invention.

[0031] Fig. 2 shows a suspension system according to the invention.

[0032] Figure 3 represents a vehicle suspension system mounting bracket according to the invention.

[0033] Fig. 4 presents two lateral views of a mounting support according to the invention, in rest position and in travel position.

[0034] Fig. 5 is a cross-sectional view of a vehicle suspension system mounting bracket according to the invention.

[0035] In the following description, the term "include" is synonymous with "include" and is not limiting in that it permits the presence of other elements in the vehicle to which it relates. It is understood that the term "include" includes the terms "consist of". The terms "external" and "internal" shall respectively designate what is oriented towards the outside of the vehicle and towards the inside of the vehicle.

[0036] In this description, the terms "longitudinal," "longitudinally," "transverse," and "transversely" are used with respect to the vehicle's frame of reference in the mounting configuration. The term "longitudinal" refers to the principal direction of travel of the vehicle. The term "transverse" refers to a direction perpendicular to the principal direction of travel of the vehicle. The term "front" refers to the principal direction of travel of the vehicle. The term "rear" refers to the opposite of the front of the vehicle.

[0037] The X-axis represents the longitudinal direction, the Y-axis represents the transverse direction, and the Z-axis represents the vertical direction of the motor vehicle. These three axes define a right-handed trihedron whose orientation is preserved throughout the figures.

[0038] In this description, the ranges of values ​​include the bounds that delimit them.

[0039] In this description, the terms "vertical" and "horizontal" are not to be understood in their strict sense. Indeed, they allow an inclination of at most 20°, preferably at most 10°, more preferably at most 5°, and even more preferably at most 2°; with respect to the strict meaning of these terms.

[0040] In this description, the technical characteristics are defined in the system mounting configuration, unless otherwise explicitly stated.

[0041] Throughout the description, the various figures use the same reference numerals to designate identical or similar entities. The suspension system 20 according to the invention and the vehicle 10 exhibiting such a suspension system 20 will be described jointly.

[0042] Reference will first be made to [Fig. 1] showing a vehicle 10 according to the invention. In the illustrated example, the vehicle 10 is a light motor vehicle, but the invention also applies to heavy vehicles, commercial vehicles, and trailers. The suspension system 20 is shown here associated with the rear axle, but it can also be applied to a front axle. The suspension system 20 is associated with an axle 18, which can be a rigid axle or a swing axle. The suspension system 20 connects the axle 18 to a chassis 14.

[0043] Turning to [Fig. 2], it can be seen that according to the invention, the suspension system 20 comprises a leaf spring 22. The use of leaf springs 22 in a suspension system is known. Leaf springs 22 comprise one or more arc-shaped curved leaves, generally made of metal or composite material. When they comprise several leaves, these are of different lengths, overlapping, and fixed together. The leaf spring 22 is arranged so that the leaves extend along the longitudinal direction of the vehicle. The leaf spring 22 comprises, at its longest leaf, a longitudinally opposed front end 50 and a longitudinally opposed rear end 24. The axle is connected to the central part of the leaf spring 22 by means of a bracket-type fastening device.The suspension system 20 may include a strut shock absorber 54, positioned substantially in the centre of the leaf spring 22 and connected to the chassis 14 of the vehicle 10.

[0044] The suspension system 20 includes two mounting brackets (26, 52), namely a front mounting bracket 52 and a rear mounting bracket 26, intended to be fixed to the chassis 14 of the vehicle.

[0045] Each of the front 50 and rear 24 ends of the leaf spring 22 is fixed to one of the mounting brackets (26, 52) by means of a pivot joint via a pivot axis (38, 58). The pivot joints may be single or double. In the context of the invention, a double pivot joint is a double pivot joint. Preferably, the suspension system includes at least one double pivot joint. For example, the suspension system 20 includes a single pivot joint 56 (with a pivot axis 58) and a double pivot joint 30 (with two pivot axes (38, 40)). Each pivot joint is carried by one of the mounting brackets (26, 52). For this purpose, each of the mounting brackets (26, 52) has an opening in its wall which is traversed by the axis of rotation and which supports it. Preferably, each of the fixing supports (26, 52) shows a double wall, each wall mounting an orifice so that the orifices are aligned, and so that the pivot axis (38, 58) passes through the two orifices.

[0046] The leaf springs 22 operate in flexure by bending under the action of a force applied by the axle at their center. The fixing of the leaf spring 22 by its ends (24, 50) must allow this flexure movement on the one hand by a change in curvature of the leaf(s), and therefore of orientation (i.e. angle) with respect to the chassis 14 (hence the use of pivot joints) and a modification of the spacing between the two ends (24, 50) of said leaf spring 22 (hence the use of at least one double pivot joint).

[0047] In the illustrated embodiment, the front end 50 is fixed by a simple pivot joint 56 and the rear end is fixed by a double pivot joint 30. However, the reverse can be considered by a person skilled in the art.

[0048] The invention is remarkable in that at least one of the mounting supports (26, 52) has at least one extended orifice 28 allowing movement of the pivot axis (38, 58) passing through it, so that said pivot axis (38, 58) can slide between a rest position 72 and a movement position 74 (visible in [Fig. 4]). Usually, the orifice(s) offer only one degree of freedom to the pivot axis passing through them, namely rotation about the axis. According to the invention, the fixing support(s) (26, 52) showing at least one extended orifice 28, offer two degrees of freedom to the pivot axis passing through them, namely a rotational movement around the axis and a translational movement along the edges of the extended orifice(s) 28. Thus, the extended orifice(s) 28 will advantageously show an elongated, oblong or T-shaped form.When the extended orifice(s) 28 show a T-shape, the pivot axis will slide along the stem of the T.

[0049] With reference to [Fig. 4], it will be understood that the suspension system according to the invention will create an additional travel height H at at least one end of the leaf spring, partially compensating for the rigidity of the leaf spring. Advantageously, the travel height H is between 2 and 30 mm; preferably, between 5 and 20 mm.

[0050] The edges of the extended orifice(s) 28 will therefore serve as guides in the translational movement of the axis of rotation. In order to maximize the compensating effect, those skilled in the art would benefit from configuring the extended orifice(s) 28 so that the movement occurs in a vertical direction. However, other orientations are possible, for example, an orientation in a direction showing an angle of 10 to 60 degrees with respect to the vertical.

[0051] The mounting bracket (26, 52) showing at least one extended hole 28 can be associated with a simple pivot joint or with a double pivot joint. Preferably, and as illustrated [Fig. 2], the rear mounting bracket 26 showing at least one extended hole 28 is associated with a double pivot joint 30.

[0052] The rear end 24 of the leaf spring 22 is connected to the rear mounting bracket 26 by the double pivot joint 30. The double pivot joint 30 comprises an upper pivot joint and a lower pivot joint. The rear mounting bracket 26 is connected to two parallel fasteners 36 by an upper pivot pin 38, forming the upper pivot joint. The two parallel fasteners 36 are connected to the rear end 24 by a lower pivot pin 40 joining the two parallel fasteners 36 by passing through the rear end 24, to form the lower pivot joint. For example, at the rear end 24, the upper leaf of the leaf spring 22 is folded forward to form a sleeve through which the lower pivot pin 40 passes. The parallel fasteners 36 may be splices.

[0053] The upper pivot joint and the lower pivot joint are parallel. The upper pivot axis 38 and the lower pivot axis 40 are parallel. The upper pivot axis 38 and the lower pivot axis 40 are transverse axes.

[0054] The upper pivot joint allows the parallel fasteners 36 to rotate around the upper pivot axis 38; said rotation causes the parallel fasteners 36 to move. The lower pivot joint allows the leaf spring 22 to rotate around its rear end 24. The lower pivot joint allows the leaf spring 22 to rotate around the lower pivot axis 40; said rotation causes the leaf spring 22 to move.

[0055] The double pivot joint 30 is a joint allowing the leaf spring 22 to lengthen and shorten in response to the movements of the axle, under the effect of the asperities of the road.

[0056] Thus, according to a preferred embodiment of the invention, the pivot axis 38 passing through the extended orifice(s) 28 is part of a double pivot joint 30 showing a parallel upper pivot axis 38 and lower pivot axis 40, so that the upper pivot axis 38 passes through the extended orifice(s) and the lower pivot axis 40 is connected to one end of the leaf spring, preferably to the rear end 24 of the leaf spring 22.

[0057] Advantageously, and as illustrated in Figures 3 to 5, the rear mounting bracket 26, showing at least one extended opening 28, further comprises an elastic means 66 configured to return the pivot axis 38 to its rest position 72. The elastic means 66 can be selected from a compression spring and a tension spring; preferably, as illustrated, the elastic means 66 is a compression spring. The elastic means 66 can be selected from a helical spring or a flat spring; preferably, as illustrated, the elastic means 66 is a flat spring. Flat springs operate on the same principle as leaf springs and work in bending.

[0058] As illustrated in [Fig. 3], in embodiments in which the elastic means 66 is a flat spring configured to bend when sufficient force is applied to its center, the rear mounting bracket 26 showing at least one extended opening 28 advantageously comprises two retaining edges 42 configured to guide the flat spring in its bending movement. As illustrated in [Fig. 5], it may also comprise at least one slide 44 configured to guide the flat spring in its bending movement, and said flat spring then comprises at least one guide rib 46 configured to fit into the slide or at least one of the slides 44.

[0059] Advantageously the pivot axis 38 is inserted into a retaining sleeve 48. The retaining sleeve 48 will therefore pass through the extended orifice(s) 28 and slide there with the pivot axis 38; preferably, the retaining sleeve 48 comprises two lateral rims 86 configured to guide the retaining sleeve 48 in its sliding movement and to hold it in position in the extended orifice(s) 28.

[0060] The rear mounting support 26 showing at least one extended orifice 28 advantageously includes a bearing surface 68 for the elastic means 66. The bearing surface 68 can materialize an upper limit of the extended orifice(s) 28. For example, the bearing surface 68 closes the upper part thereof.

Claims

Demands

1. Suspension system (20) for a vehicle axle (18) (10), comprising a leaf spring (22) with a front end (50) and a rear end (24), the suspension system (20) further comprising two mounting brackets (26, 52) divided into a front mounting bracket (52) and a rear mounting bracket (26) and intended to be fixed to a vehicle chassis (14) (10), each of the front (50) and rear (24) ends of the leaf spring (22) being fixed to one of the two mounting brackets (26, 52) by a pivot joint by means of a pivot pin (38, 58), characterized in that at least one of the two mounting brackets (26, 52) has at least one extended opening (28) such that it allows movement of the pivot pin (38, 58) passing through it, so that said pin pivot (38, 58) can slide between a rest position (72) and a travel position (74).

2. Suspension system (20) according to claim 1, characterized in that the fixing support (26, 52) showing at least one extended orifice (28) further comprises an elastic means (66) configured to return the pivot axis (38, 58) to the rest position (72).

3. Suspension system (20) according to claim 1 or 2, characterized in that the mounting support showing at least one extended orifice (28) is the rear mounting support (26); and / or in that the extended orifice(s) (28) are configured so that the movement occurs in a vertical direction.

4. Suspension system (20) according to any one of claims 1 to 3, characterized in that the pivot axis (38) passing through the extended orifice(s) (28) is part of a double pivot joint (30) showing a parallel upper pivot axis (38) and lower pivot axis (40), such that the upper pivot axis (38) passes through the extended orifice(s) and the lower pivot axis (40) is connected to one end of the leaf spring; preferably, to the rear end (24) of the leaf spring (22).

5. Suspension system (20) according to any one of claims 2 to 4, characterized in that the elastic means (66) is selected from a compression spring or a tension spring; and / or in that the elastic means (66) is selected from a helical spring or a flat spring; preferably, the elastic means (66) is a flat spring.

6. Suspension system (20) according to claim 5, characterized in that the elastic means (66) is a flat spring configured to flex when a sufficient force is applied to its center, and in that the fixing support (26, 52) showing at least one extended orifice (28) comprises two retaining edges (42) configured to form a guide receiving the flat spring and capable of guiding it in its flexing movement.

7. Suspension system (20) according to any one of claims 5 or 6, characterized in that the elastic means (66) is a flat spring configured to flex when a sufficient force is applied at its center, and in that the mounting support (26, 52) showing at least one extended orifice (28) comprises at least one slide (44) configured to guide the flat spring in its flexing movement, said flat spring comprising at least one guide rib (46) configured to fit into the or at least one of the slides (44).

8. Suspension system (20) according to any one of claims 1 to 7, characterized in that the mounting support (26, 52) showing at least one extended orifice (28) comprises a retaining sleeve (48) through which the pivot axis (38) passes, said retaining sleeve (48) passing through the extended orifice(s) (28) and being able to slide in said extended orifice (28); preferably, the retaining sleeve (48) comprises two lateral flanges (86) configured to guide the retaining sleeve (48) in its sliding movement.

9. Suspension system (20) according to any one of claims 1 to 8, characterized in that the extended orifice(s) (28) show an oblong shape or a T-shape; and / or in that a travel height is between 2 and 30 mm, preferably between 5 and 20 mm.

10. Vehicle (10) characterized in that it comprises at least one suspension system (20) according to any one of claims 1 to 9, preferably, the or at least one of said suspension systems (20) is associated with a rear axle (18) and / or the or at least one of said suspension systems (20) is associated with a rigid axle or an oscillating axle.