Hydraulic vehicle shock absorber with spring preload adjustment

Abstract

The invention relates to a hydraulic shock absorber (1) for a vehicle, comprising: - a hydraulic braking chamber (2); - a sliding piston (3); - a first head (5) having a first bearing surface (51); - a second head (6) integral with the piston and having a second bearing surface (61); - a first stop (7) pivotally mounted about a longitudinal axis and sliding; - a second stop (8) retained by the second head (6); - a spring (4) compressed in the longitudinal direction between the stops (7, 8); - the first head (5) having a first projecting lug (52), formed in one piece with the bearing surface (51) of the first head, the first stop (7) having a cam (71) having a series of contact faces offset from each other (711, 712, 713), one of the contact faces (711) being in contact with the first lug (52). Figure to be published with the abbreviation: Fig. 1

Description

Title of the invention: Hydraulic vehicle shock absorber with spring preload adjustment

[0001] The invention relates to vehicle spring-shock absorber assemblies, and in particular to telescopic spring-shock absorber assemblies, for which the spring preload is adjustable.

[0002] The use of a suspension is imposed by the irregularities of the surface on which the vehicle moves. The suspension reduces the impact on the machine, avoiding breakages and excessive wear, improving driving comfort and maintaining contact between the wheels and the ground despite its irregularities. Maintaining contact is an essential condition for road holding and traction. The suspension of a vehicle usually comprises a spring element and a shock absorber to connect a wheel to the chassis of the vehicle. The spring element aims to suspend the weight of the vehicle. The shock absorber serves to control the speed of the suspension movements by absorbing the energy transmitted to the wheel and the chassis, so as to control the speed and limit of its oscillations. When transferring kinetic energy into potential energy in the suspension, the shock absorber achieves this dissipation of energy.

[0003] Most shock absorbers used in vehicles are telescopic hydraulic shock absorbers. Such shock absorbers utilize the pressure losses of oil flowing in a chamber. A piston is slidably mounted in the chamber containing oil. When the piston moves as required by the wheel or chassis movements, the piston forces the fluid through calibrated perforations, separate deformable valves, or a pressure relief system, provided for the flow of oil in its compression and expansion movements.

[0004] In order to have minimal bulk and weight, it is common to combine the shock absorber and suspension spring functions in the same device. Particularly in the field of motorcycles, it is common to use telescopic spring-shock absorber assemblies for the rear suspension. Similarly, off-road vehicles most often have telescopic spring / shock absorber assemblies at the rear wheels.

[0005] To manage possible variations in vehicle load or more or less uneven ground relief, it is recommended to adjust the preload of the spring of the combination, in particular to define the amplitude of the dead travel of the vehicle. According to a known structure, a combination is used, equipped with a fixing head secured to the hydraulic damping chamber and comprising a bearing surface for a first point of attachment to the vehicle. This combination comprises a pivoting and sliding cam by relative to the chamber and serving as a movable stop for one end of a coil spring. The cam has several contact faces offset along the longitudinal axis of the assembly. A finger is welded to the fixing head and comes into contact with one contact face of the cam. Thus, by pivoting the cam around the chamber, another contact face of the cam is placed against the finger. The movable stop is then moved along the longitudinal axis of the assembly, which makes it possible to adjust the compression preload of the spring.

[0006] Such a configuration turns out to be relatively unattractive. Furthermore, it turns out that the manufacturing and assembly process of a handset is relatively complex and impacts its selling price.

[0007] The invention aims to solve one or more of these drawbacks. The invention thus relates to a hydraulic vehicle shock absorber, comprising: - a hydraulic braking chamber; - a piston mounted to slide in a longitudinal direction in the hydraulic damping chamber; - a first fixing head secured to the hydraulic damping chamber and comprising a first attachment surface to a vehicle; - a second fixing head secured to the piston and comprising a second surface for fixing to a vehicle; - a first stop, pivotally mounted around the longitudinal axis and sliding along the longitudinal axis relative to the hydraulic braking chamber; - a second stop retained by the second fixing head; - a helical spring positioned to be compressed in the longitudinal direction between the first and second stops; -the first fixing head comprising a first protruding lug along the longitudinal axis, the first lug being formed in one piece with the bearing surface of the first fixing head, the first stop comprising a cam having a series of contact faces offset from each other along the longitudinal axis and around the longitudinal axis, one of the contact faces being in contact with the first lug; or -the first stop comprising a first protruding lug along the longitudinal axis, the first fixing head comprising a cam having several contact faces offset along the longitudinal axis and around the longitudinal axis, one of the contact faces being in contact with the first lug, the cam being formed in one piece with the bearing surface of the first fixing head.

[0008] The invention also relates to the following variants. Those skilled in the art will understand that each of the features of the following variants can be independently combined with the above features, without constituting an intermediate generalization.

[0009] According to a variant, the hydraulic damping chamber is in particular delimited by a tube screwed into a bore of a crown of the first fixing head, the first lug being formed by a finger extending in one piece from the crown to the outside of the tube.

[0010] According to another variant, the shock absorber further comprises an adjustable pressure limiter, interfering in a fluid flow circuit provided in the first fixing head.

[0011] According to another variant, the shock absorber comprises a second lug formed in one piece with the bearing surface of the first fixing head and angularly offset around the longitudinal axis relative to the first lug, the cam comprising another series of contact faces offset relative to each other along the longitudinal axis and around the longitudinal axis, one of the contact faces of this other series being in contact with the second lug.

[0012] According to yet another variant, the contact faces of said series form recesses separated by ridges.

[0013] The invention also relates to a method of manufacturing a hydraulic vehicle shock absorber, comprising the steps of: -machining of a first fixing head comprising a surface for fixing to a vehicle, and comprising a first lug or a cam in one piece, - the placement, where appropriate, of a cam of a first stop in contact with the first lug of the first fixing head or of a first lug of a first stop in contact with the cam of the first fixing head; - securing a hydraulic braking chamber to the first fixing head; - mounting a sliding piston relative to the hydraulic braking chamber; - compression of a helical spring between the first stop and a second stop retained by a second fixing head.

[0014] Other characteristics and advantages of the invention will emerge clearly from the description given below, for information purposes only and in no way limiting, with reference to the appended drawings, in which:

[0015] [Fig-1] is a perspective view of an exemplary embodiment of a hydraulic shock absorber according to an exemplary implementation of the invention;

[0016] [Fig.2] is a partial sectional view of the hydraulic damper of [Fig. 1]

[0017] [Fig.3] is a flattened view of a portion of an exemplary cam profile.

[0018] [Fig.l] illustrates a perspective view of an exemplary embodiment of a hydraulic shock absorber according to an exemplary implementation of the invention. [Fig.2] illustrates a partial sectional view of the hydraulic shock absorber of [Fig.l]. The hydraulic shock absorber 1 is intended to be mounted on a vehicle, for example a motorcycle or an off-road vehicle. The hydraulic shock absorber 1 comprises a hydraulic braking chamber 2 and a piston 3 slidably mounted in the hydraulic damping chamber 2 in the longitudinal direction (X). The hydraulic braking chamber 2 is at least partially filled with a liquid which the piston forces to pass through hydraulic restrictions in order to achieve, in a manner known per se, hydraulic damping to brake a movement of expansion or compression of the piston 3. The chamber 2 thus comprises an enclosure 23 receiving the head 31 of the piston 3 and a hydraulic fluid.

[0019] The shock absorber 1 comprises a first fixing head 5 secured to the hydraulic damping chamber 2. This fixing head 5 comprises a first attachment surface 51 for attachment to a vehicle. This attachment surface 51 can, for example, receive a ball joint, a silent block or a connecting pin to an element of the vehicle, for example the chassis. The surface 51 can be of the single or double type (in the form of a stirrup). The chamber 2 is here delimited both by a tube 21 (here of circular section), a plug 22 and the fixing head 5. A rod 32 of the piston is mounted to slide in a sealed manner relative to the plug 22.

[0020] The shock absorber 1 also comprises a second fixing head 6 secured to the piston and comprising a second fixing surface 61 for fixing to the vehicle. This fixing surface 61 can for example receive a ball joint, a silent block or a connecting pin to an element of the vehicle, for example a suspension arm or a swing arm. The surface 61 can be of the single or double type (in the form of a caliper).

[0021] The shock absorber 1 also comprises a first stop 7 pivotally mounted around the longitudinal axis X and sliding along the longitudinal axis relative to the hydraulic braking chamber 2.

[0022] The shock absorber 1 also comprises a second stop 8 retained by the second fixing head 6. Thus, a face 82 of the stop 8 interferes with the fixing head 6. It could also be envisaged to fix the stop 8 to the fixing head 6. Thus, the second stop 8 is held between the chamber 2 and the second fixing head 6.

[0023] The shock absorber 1 is intended to receive the helical spring 4 (not illustrated in [Fig.2]) to form a spring / shock absorber combination. The spring 4 is positioned to be compressed in the longitudinal direction between the first and second stops 7 and 8. More precisely, the spring 4 is compressed between a bearing face 72 of the stop 7 and a bearing face 81 of the stop 8.

[0024] In the illustrated embodiment, the first fixing head 5 comprises at least one lug 52 projecting along the longitudinal axis X. This lug 52 is formed in one piece with the bearing surface 51 of the first fixing head 5, typically by machining. The first stop 7 comprises a cam 71. The cam 71 has a series of contact faces, the faces 711 to 713 of which are referenced. The contact faces of the cam 71 are offset from each other along the longitudinal axis and around the axis longitudinal. One of the contact faces is in contact with the first lug 52. Thus, depending on the contact face placed in contact with the lug 52, the distance between the bearing faces 72 and 81 is fixed. This distance corresponds to the precompression of the spring 4, i.e. its load when no force is applied to the fixing heads 5 and 6. The contact face placed against the lug 52 is defined by rotation of the stop 7 around the longitudinal axis X. Each contact face thus defines a notch corresponding to a preload value of the spring 4.

[0025] When the bearing faces 72 and 81 are brought together, the spring 4 is compressed, which exerts an opposite elastic return force. The movement of the piston 3 is also damped by means of hydraulic braking of the hydraulic fluid displaced in the chamber 2. The movement is thus damped during the compression stroke of the shock absorber 1.

[0026] At the end of the compression stroke, the spring 4 separates the bearing faces 72 and 81. The movement of the piston 3 is also damped by means of hydraulic braking of the hydraulic fluid displaced in the chamber 2. The movement is thus damped during the expansion stroke of the shock absorber 1. In the example illustrated, the head 5 comprises a fluid flow circuit 55. The head 5 further comprises a bore 54, intended to receive an adjustable pressure limiter, not illustrated. Such a pressure limiter is intended to be mounted in the bore, so as to interfere with the fluid flow circuit 55. Such a pressure limiter can thus be provided to brake a fluid flow of the expansion stroke and / or the compression stroke.

[0027] In the example illustrated, the tube 21 of the chamber is screwed into a bore of a crown 53 of the first fixing head 5. The lug 52 is here formed by a finger extending in one piece along the longitudinal axis and from the crown 53, outside the tube 21.

[0028] [Fig. 3] illustrates a flattened example of a cam profile. To ensure the stability of the different preload positions of the spring 4, these contact faces form recesses separated by ridges. The recesses advantageously have a shape complementary to that of a contact face of the lug 52.

[0029] In order to distribute the forces on the stop 7, for example to keep it as much as possible with an axis coaxial with the chamber 2, another lug is advantageously formed in one piece with the bearing surface 51 of the first fixing head 5 and offset angularly around the longitudinal axis X relative to the first lug 52. The cam 7 comprises another series of contact faces offset relative to each other along the longitudinal axis and around the longitudinal axis, one of the contact faces of this other series of contact faces being in contact with the other lug. Advantageously, the other lug is symmetrical to the lug 52 relative to the longitudinal axis X. It is also possible to provide three lugs distributed around the longitudinal axis X to distribute the forces. forces imposed by the spring around the axis.

[0030] In the example illustrated, the first stop 7 comprises the cam 71 and the fixing head 51 comprises the lug 52. It is also possible to envisage that the stop 7 comprises a first lug projecting along the longitudinal axis, the first fixing head 5 comprising a cam having several contact faces offset along the longitudinal axis and around the longitudinal axis, the cam being formed in one piece with the bearing surface 51. As in the example detailed previously, one of the contact faces of the cam of the head 5 is then in contact with the lug of the first stop.

[0031] Typically, the method of manufacturing such a hydraulic vehicle shock absorber 1, comprising the steps of:

[0032] -machining the first fixing head 5 comprising the fixing surface 51 to a vehicle, and comprising a first lug 52 or a cam in one piece;

[0033] -the placement, where appropriate, of a cam of a first stop 7 in contact with the first lug 52 of the first fixing head, or of a first lug of a first stop in contact with the cam of the first fixing head;

[0034] - the securing of the hydraulic braking chamber 2 to the first fixing head;

[0035] - the mounting of a piston 3 sliding relative to the hydraulic braking chamber 2;

[0036] - the compression of a helical spring 4 between the first stop 7 and a second stop 8 retained by the second fixing head 6.

Claims

Claims

1. Hydraulic shock absorber (1) for a vehicle, characterized in that it comprises: - a hydraulic braking chamber (2); - a piston (3) mounted to slide in a longitudinal direction (X) in the hydraulic damping chamber (2); - a first fixing head (5) secured to the hydraulic damping chamber (2) and comprising a first fixing surface (51) for fixing to a vehicle; - a second fixing head (6) secured to the piston and comprising a second fixing surface (61) for fixing to a vehicle; - a first stop (7), pivotally mounted about the longitudinal axis and sliding along the longitudinal axis relative to the hydraulic braking chamber (2); - a second stop (8) retained by the second fixing head (6); - a helical spring (4) positioned to be compressed in the longitudinal direction between the first and second stops (7, 8);-the first fixing head (5) comprising a first lug (52) projecting along the longitudinal axis, the first lug (52) being formed in one piece with the bearing surface (51) of the first fixing head, the first stop (7) comprising a cam (71) having a series of contact faces offset from each other (711, 712, 713) along the longitudinal axis and around the longitudinal axis, one of the contact faces (711) being in contact with the first lug (52); or -the first stop (7) comprising a first lug projecting along the longitudinal axis, the first fixing head (5) comprising a cam having several contact faces offset along the longitudinal axis and around the longitudinal axis, one of the contact faces being in contact with the first lug, the cam being formed in one piece with the bearing surface of the first fixing head (5).;

2. Hydraulic vehicle shock absorber (1) according to claim 1, the hydraulic damping chamber (2) being in particular delimited by a tube (21) screwed into a bore of a crown (53) of the first fixing head (5), the first lug (52) being formed by a finger extending in one piece from the crown (53) to the outside of the tube (21).

3. Hydraulic vehicle shock absorber (1) according to claim 1 or 2, further comprising an adjustable pressure limiter, interfering in a fluid flow circuit (55) provided in the first fixing head (5).

4. Hydraulic vehicle shock absorber (1) according to any one of the preceding claims, comprising a second lug formed in one piece with the bearing surface (51) of the first fixing head (5) and angularly offset around the longitudinal axis relative to the first lug (52), the cam (7) comprising another series of contact faces offset relative to each other along the longitudinal axis and around the longitudinal axis, one of the contact faces of this other series being in contact with the second lug.

5. A hydraulic vehicle shock absorber (1) according to any preceding claim, wherein the contact faces of said series form recesses separated by ridges.

6. Method for manufacturing a hydraulic shock absorber (1) for a vehicle, comprising the steps of: -machining a first fixing head (5) comprising a surface (51) for fixing to a vehicle, and comprising a first lug (52) or a cam in one piece, -placing, where appropriate, a cam of a first stop (7) in contact with the first lug (52) of the first fixing head or a first lug of a first stop in contact with the cam of the first fixing head; -securing a hydraulic braking chamber (2) to the first fixing head; -mounting a piston (3) sliding relative to the hydraulic braking chamber (2); -compressing a helical spring (4) between the first stop (7) and a second stop (8) retained by a second fixing head (6).

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