FR3039460A1 - NON-LINEAR SLIDING CINEMATIC CATCH AND VEHICLE THEREFOR - Google Patents

Abstract

A jack (2) comprises a tubular body (21), a piston (22) separating two chambers (211, 212) and sliding in the body, a rod (23) having an end (231) integral with the piston, partially included in one of the chambers (212) and slidably driven by the piston, and a guide piece (24) of the rod, connected to the body and comprising a sliding passage opening of the rod. The tubular body being configured along a guideline followed substantially by sliding by the piston, the latter is connected to the rod by a link (25) allowing at least one degree of freedom in rotation along an axis perpendicular to the guideline. A sliding with curvature (s) is thus made possible. Applications to suspension dampers, and vehicle, in particular automobile, provided with such a cylinder.

Description

NON-LINEAR SLIDING CINEMATIC CATCH

VEHICLE ASSOCIATED

The present invention relates to an improved kinematic sliding cylinder and diversified. It relates more particularly to a suspension damper, in particular for a vehicle, and more specifically for a motor vehicle.

Leg-type suspension systems are commonly used in the automotive industry. Such a strut generally includes a hydraulic damper interposed between a wheel of the vehicle and the frame and allowing, in combination with a spring, damping shocks. Document FR-2874858 (inventor: Kris Schuyten) proposes for example the combination of a suspension damper with a spring having a non-linear shape.

A hydraulic damper typically comprises a rod disposed in the axis of a tubular body filled with a fluid. The rod has an end secured to a piston sliding in this body, which separates a low compression chamber on a side opposite the rod, of a high expansion chamber through which the rod. Sealed guidance allows the rod to exit the expansion chamber. The body and the rod being respectively coupled to a ground engaging member such as a wheel pivot and to the frame, suspension deflections cause the piston to slide which moves the fluid from one chamber to the other via calibrated orifices made in the piston.

Suspension dampers are generally formed of linear jacks in translation, but circular rotary jacks are also known.

The cylinders used in particular in the automotive field, however, have the disadvantage of requiring spatial arrangements appropriate to their size. These geometric constraints are often rather restrictive, in particular for the architecture of vehicle trains. They may in particular have the disadvantageous effects of limiting the tire width, imposing a minimum value on the vehicle lane, or requiring the installation of relatively complex and expensive mechanisms to avoid interference with parts of the vehicle. vehicle such as power transmission elements.

In addition, the actuators used as suspension dampers induce train drawings whose possibilities are relatively limited, particularly in terms of camber dynamics in vertical wheel deflection.

The present invention is intended in particular to avoid the drawbacks of known systems, by proposing a jack likely to offer a significantly increased flexibility in the geometric design of the cylinder and kinematics sliding rod. In its preferred modes applied to the automobile, the object of the invention is in particular to make it possible with regard to known systems: an increased tire width, a reduced vehicle track, a simplified and economical train architecture in the event of interference with other parts of the vehicle and / or the adaptive creation of epure curves relating to wheel camber variations as a function of vertical deflections. The invention also extends to other fields than the automobile, and is potentially applicable to multiple fields of operation, including other types of vehicles but also, for example, construction, machine tools and mechanical control systems. For this purpose, the subject of the invention is a jack comprising: a tubular body, at least one piston forming a partition separating two chambers internal to the body, this piston (s) being adapted to slide in the body, and thus to modify the sizes of these chambers, - at least one rod having an end secured to this (s) piston (s), this or these rod (s) being partially included (s) in one of the chambers and adapted to be driven (s) sliding in this chamber by sliding of this (these) piston (s), and - at least one guide piece of this rod (s) in the body, this / these part (s) being linked to the body and comprising at least one sliding passage opening of the rod (s) through this / these part (s).

According to the invention, the tubular body being configured according to at least one guide line followed substantially in sliding by the piston (s), this (s) piston (s) is / are linked (s) to the rod (s) (S) by a link allowing at least one degree of freedom in rotation along an axis perpendicular to this guideline.

Thus, in contrast to the cylinders usually used, the connection between the piston and the rod integral with the piston is not rigid, but flexible, according to at least the specified rotational movement. This flexibility, combined with other features of the cylinder and in particular the guidance of the rod, offers multiple geometric and kinematic potentialities. The opening of the field of realization of the jacks which results in particular makes it possible to build the body of the cylinder with two-dimensional or three-dimensional curvatures in length, in addition to the curvature in width, traditionally circular, transverse with respect to the guideline. The geometrical configuration of these curvatures in length is expressed in particular via the guideline, and makes it possible to dispense with the conventional framework of cylindrical cylinders of pure translation and circular cylinders of pure rotation. In appropriate embodiments, it is thus possible to solve problems of size and penalizing proximity of parts, by introducing adequate topological adaptations.

The shaping flexibility also makes it possible to specifically develop kinematics for the sliding of the piston and / or of the rod, in particular when the body of the jack comprises the above-mentioned curvatures, but also when this body is conventionally cylindrical. In the latter case, curvatures are advantageously assigned to the rod. The combined use of judiciously chosen curvatures for both the body and the stem is also interesting. In appropriate embodiments, it is thus possible to develop slide kinematics adjusted in a desired manner, thanks to the presence of one or more additional degrees of movement compared to conventional cylinders.

Preferably, the body guideline extends in a plane, and the connection between the piston and the rod allows at least one degree of freedom in rotation along an axis perpendicular to the plane.

In particular embodiments, alone or in combination (s): - the connection between the piston and the rod is a ball joint; - The guide member allows relative to the body at least one degree of freedom in rotation of the rod along an axis perpendicular to the guideline; the piston and the body have between them a connection of the sliding pivot type; the rod and the guide piece have between them a connection of the sliding pivot type.

In advantageous implementations, the jack forms a vehicle suspension damper, the tubular body being adapted to be connected to at least one vehicle ground connection element and the rod having another end adapted to be connected to at least one a suspended element of the vehicle.

In a particular particular embodiment, the body of the jack being adapted to be connected to a wheel pivot on one side of the body, this body is then configured so as to form on this side at least one concavity of the guide line, this concavity being adapted to face a wheel mounted on the wheel pivot.

In other advantageous implementations for which the jack forms a vehicle suspension damper, which can in particular be combined with the previous embodiment, this jack comprises at least one lower helical spring seat fixed on the body and adapted to receive a spring helical surrounding a length of the body located above this lower seat. The body is then configured to form at least one curvature of the guideline and the lower spring seat is secured below at least a portion of the curvature, so that the spring at least partially surrounds curvature. The invention also relates to a vehicle, in particular a motor vehicle, comprising at least one jack according to any one of the above definitions.

In an advantageous embodiment of the vehicle for which this cylinder forms a suspension damper, the cylinder body being adapted to be connected to a wheel pin and the rod having another end adapted to be connected to at least one suspended element of the vehicle, this body has a straight main part and a curved lower part. In addition, a wheel mounted on the wheel pivot having a camber varying according to a displacement of the wheel, the body of the cylinder and the positioning of the jack in the vehicle are adapted so that the camber attack remains negative including in maximum travel of current operation. The invention will be better understood and other features and advantages will appear more clearly in the light of the following description of embodiments, given without limitation with reference to the accompanying drawings in which: - Figure 1 is a schematic diagram showing a particular embodiment of a cylinder according to the invention; - Figure 2 shows a simplified section of a cylinder corresponding to the block diagram of Figure 1, in the depressed position of the rod; - Figure 3 shows a simplified section of the cylinder of Figure 2, in the partially stretched position of the rod; FIG. 4 shows in transparency a vehicle suspension damper for a wheel pivot with a wheel mounted, according to a traditional version with a cylindrical damper body; - Figure 5 shows the representation of Figure 4, replacing the traditional damper by a schematic embodiment of suspension damper formed by a cylinder according to the invention; FIG. 6 illustrates a specific arrangement of the vehicle rear axle with hybrid electric motor, involving a proximity arrangement between a transmission shaft and a conventional suspension damper with a cylindrical body; - Figure 7 shows schematically the respective arrangement of the transmission shaft and the damper of Figure 6; - Figure 8 shows the representation of Figure 7, replacing the traditional damper by a schematic embodiment of a suspension damper formed by a cylinder according to the invention; FIG. 9 shows a vehicle suspension damper on a McPherson-type front train, formed of a jack according to the invention; FIG. 10 is a graph showing the wheel camber (horizontal axis) as a function of a vertical wheel displacement (vertical axis), both for the damper of FIG. 9 and for a corresponding traditional damper. (with cylindrical body).

A jack 1, as represented in the form of a block diagram in FIG. 1, comprises a tubular body 11 in which slides a piston 12 carrying a rod 13, as well as a sliding guide piece 14 of the rod 13 in the body 11.

The body 11, non-rectilinear, is provided with at least one curvature 110. Its walls substantially follow in length a guide line, the body 11 having in width a substantially constant cross section. The piston 12 and the rod 13 can thus be guided in sliding along a path along this guideline. In an alternative embodiment, which requires adaptations of the piston 12 making it suitable for joint flexibility to the internal body walls 11 (for example via an elastomer element), this cross section is slightly variable. The geometry of the body 11 is then given by several guidelines.

In addition, in the chosen mode, the body guideline 11 follows a planar variation (in the plane of the sheet). Advantageously, it is substantially circular, the body 11 then having a constant section, a toric shape. This embodiment allows a circular path of the piston 12 and the rod 13. According to variants, the guide line 11 is profiled in three dimensions, which leads to more sophisticated curvatures of the body 11.

The piston 12, preferably of cylindrical shape, serves as a partition delimiting inside the body 11 a lower chamber 111 and a high chamber 112 bounded in the upper part by the guide member 14. It is connected to the body 11 by a connection sliding pivot type 16 (which allows a rotation along a sliding axis along the body of the guideline 11).

The rod 13, straight in the representation of principle, is secured to the piston 12 at a lower end 131 by a ball joint 15 and is partially contained in the upper chamber 112. It is also partially external to the body 11 by crossing the piece of 14, and thus comprises two parts 133 and 134 respectively internal and external to the body 11, of varying sizes depending on the sliding level of the rod 13.

The guide piece 14 comprises a portion 142 for passage of the rod 13 through an opening 141, and a portion 143 for connection to the body 11. These parts 142 and 143 are secured by a ball joint connection 17. In an alternative embodiment, the guide piece 14 is directly secured to the body 11 by such a connection. The rod 13 is free to slide in the opening 141 via a connection of the sliding pivot type 18.

The jack 1 finds multiple applications in which the body cooperates in the lower part with a first object and the rod 13 cooperates via its upper end 132 with a second object.

The four links 15, 16, 17 and 18 allow a great flexibility of movement, allowing in particular the rod 13 to follow the movements corresponding to the guideline of the body 11, including three-dimensional version, and turn on itself. This last aspect is particularly useful especially in the case where the cylinder 1 is used as a suspension damper in the front or rear train of a vehicle exposed to steering wheel.

In variants however, only a part of the degrees of freedom of these four links 15,16,17 and 18 is allowed, the other degrees of freedom being blocked. At least, for a plane curvature of the guideline, the ball joint 15 is replaced by a connection with a single degree of freedom in rotation in the plane of curvature of this guideline, the links 16 and 18 are replaced by sliding links. simple, and all other degrees of freedom are frozen. The guide piece 14 is then adapted to allow small rotational movements of the rod 13 in its opening 141, for example by means of a rubber block admitting sufficient deformations.

In other variants, the rod 13 is provided with at least one curvature, the body 11 then being curved or straight.

The cylinder 11 finds particular applications to hydraulic cylinders, pneumatic, hydropneumatic, and various corresponding dampers, including front and rear trains of vehicles.

In an exemplary embodiment associated with a hydraulic suspension damper, represented in FIGS. 2 and 3, a jack 2 comprises a body 21 that is bent, a piston 22 slidable therein by a sliding pivot 26 and a rod 23 secured to the piston 22 at its end. The piston 22, provided with calibrated openings for fluid passages, separates a compression chamber 211 from an expansion chamber 212 in which the rod 23 slides. A guide bearing 24 comprises a portion 242. passage of the rod 23 via a sliding pivot 28 and a portion 243 for holding the body 21 (for example by embedding). The portion 242 forms a ball joint inside the portion 243. The seal is provided between the portion 242 and the rod 23, as well as between the two parts 242 and 243.

In this case, the body 21 is of toric shape and the piston 22 of cylindrical shape, which ensures good sliding and good guidance of the piston 22 in the body 21.

The jack 2 is respectively connected to external objects by a lower junction 201 secured to the body 21 and an upper junction 202 integral with the rod 23. In the compression position (FIG 2), the rod 23 has mainly a portion 233A internal to the body 21, only a minority portion 234A being external to the body 21, while in the partial expansion position (FIG 3), the rod 23 has only a minority portion 233B internal to the body 21, the major part 234B being external thereto.

Several applications of a suspension damper meeting the above cylinder description are set forth below. In a first application (FIGS. 4 and 5), an implantation on a motor vehicle train of the pseudo McPherson type involves a wheel pivot 51 on which is mounted a wheel 52 with a tire 53. The suspension damping is ensured in particular by means of a strut secured to the wheel pivot 51 by a fastener 301.

According to the state of the art (FIG 4), such a strut comprises a hydraulic damper 3 including a cylindrical body 31, in which slides a piston 32 carrying a rod 33, and a sliding guide piece 34 of the rod 33. In addition, a bearing cup 303 fixed to the body 31 is provided for receiving a helical spring (not shown) disposed around and above the damper 3. This traditional configuration thus defines a door-to-door false PO between an axis of the damper 3 and the pivot 51, and a clearance DO between the damper 3 and the tire 53.

The implementation of a cylinder according to the contributions of the present description (Figure 5) leads to replace the damper 3 by a damper 4 having a body 41 curved, configured so that it has a concavity 410 53. A piston 42 linked by a ball joint to a rod 43 (or by a connection with less freedom of rotation) slides in this body 41, and a guide piece 44 allows the rod to follow the sliding movement. corresponding to the curvature of the body 41.

This provision induces a cantilever P similar to that PO obtained for the traditional damper 3, but a clearance D significantly higher. For example, considering that the damper 4 has a length of 300 mm and that the body 41 has a radius of curvature of 1500 mm, the clearance gain (D - D0) at the tire is about 10 mm, all while maintaining the same anchoring position of the cylinder body on the pivot 51. It is thus possible to mount a wider tire, or reduce the vehicle lane by moving the tire 53 towards the inside of the vehicle.

It is interesting to note that to obtain the same clearance D with the traditional damper 3 as with the damper 4, the overhang PO should be significantly increased.

A second application (FIGS. 6, 7 and 8) relates to a problem of implantation on a vehicle rear axle, in the combination of a shock absorber-spring assembly and a power transmission system. More specifically in the example shown of a hybrid motor, a wheel pivot 55 receives a transmission shaft 56 driven by an electric motor 57 via a gearbox 58.

With a conventional straight body damper 6 attached to the pivot 55 in the lower part of the body 61 by a junction 601, a difficulty is posed by the relative spatial arrangement of the damper 6 and the shaft 56 (see FIG. 6 and 7). The damper 6, which comprises a rod 63 sliding rectilinearly through a guide ring 64, is in fact secured to the vehicle frame in the upper part of the rod 63, via a junction 602. Now the spatial configuration of the vehicle infrastructure leads to a close proximity between the drive shaft 56 and the body 61 of the damper 6, with a very low OJ game. This proximity is problematic because of the risk of interference.

It also causes an additional difficulty for mounting a spring 605 on the damper 6, able to constitute a strut operating reduction and shock absorption. Indeed, the spring 605 is mounted between a lower seat 603 fixed to the body 61 and an upper seat disposed above the body 61 near the junction 602. To avoid clashes between the spring 605 and the shaft 56, it It is necessary to position the lower seat 603 high enough on the body 61. The spring 605 is thus shortened accordingly, so stiffer. The comfort of users is penalized.

The replacement of the traditional damper 6 by a damper 7 made with a cylinder according to this description is performed as follows (Figure 8). The damper 7 comprises a body 71 provided with a curvature 710 and a rod 73 sliding in the body 71 through a guide ring 74. The body 71 is designed and arranged so that the curvature 710 defines a facing cavity. to the shaft 56, producing a clearance J substantially greater than J0. It is thus possible, not only to prevent interference between the damper 7 and the shaft 56, but also to have a spring 705 around the body 71 in parallel with the transmission, to a much lower level than with the shock absorber 6.

In this way, it eliminates the risk of friction potentially deleterious for the internal mechanisms, while improving the comfort of users. The lowering of the lower spring seat is applicable to other situations with a spring surrounding a curved jack body. In particular, in an embodiment derived from the first application shown in FIG. 5, the clearance D between the damper 4 and the tire 53 is sufficiently large to lower the support cup of a spring, so that spring surrounds an upper portion of the concavity 410 vis-à-vis the tire 53.

The third application (FIGS. 9 and 10) concerns actuator sliding kinematics on a McPherson-type nose gear. During a vertical wheel travel, the camber variation of the wheel depends on this kinematics. The latter is usually dependent on the spatial positioning of a conventional damper with cylindrical body.

On a conventional McPherson system with a single arm or a triangle in normal use, it is particularly usual for the camber to become positive in attack, for sufficiently high deflections. But a negative camber attack improves the behavior of tires in turns.

A suspension damper 8 made in accordance with the present description (FIG 9) comprises a body 81 and a piston 83 sliding inside the body 81. The latter is formed of a main right part 813 and a part curved bottom 814, having a concavity 810. Compared with a conventional damper, the suspension damper 8 is installed on the McPherson-type front axle more vertically and is secured to a wheel (not shown) on one side. of the body 81 opposite the concavity 810. The lower part 814 and the associated sliding of the rod 83 give the damper 8 thus positioned remarkable properties relating to the sliding kinematics.

The resulting camber sketch curve 94, shown in FIG. 10, makes it possible to display significant differences with respect to the curve 93 obtained with a conventional damper. The camber (axis 91, expressed in degrees) is returned according to the displacement (axis 92, expressed in mm), starting from a negative camber at rest of -1 °. It appears that in the leading portion 931 of the curve 93, the camber increases in relative value until becoming positive for a travel greater than about 65 mm. In contrast, the leading portion 941 of the curve 94 shows a camber which remains close to -1 ° even for clearance of the order of 70 mm, thus providing a systematic counter-camber attack.

For the relaxation portion 932 of the curve 93, less critical than the attacking part for the qualities of the vehicle, the camber remains negative and increases slowly with the absolute value of the deflection, remaining of the order of -0.5 ° for a travel of 100 mm. In comparison, the relaxation portion 942 of the curve 94 corresponds to a rather rapid growth of the camber, which becomes positive in the vicinity of 80 mm of travel.

Overall, the curve 94 expresses a significant potential improvement in the suspension behavior for the camber in attack, with the rectification or the accentuation of the curve of epure, without compromising the properties in relaxation. The qualities associated with the presence of the damper 8 are in fact close to those of a multi-arm train.

More generally, cylinders according to the present invention allow to add a kinematic degree of vertical deflection, which makes the camber partly controllable. There is thus an action lever on a train pattern curve according to the needs, in particular of camber variation, instead of this curve being imposed by the linear sliding of a conventional cylinder.

Claims (10)

1. Cylinder (1; 2; 4; 7; 8) comprising: - a tubular body (11; 21; 41; 71; 81), - at least one piston (12; 22; 42) forming a partition separating two chambers (111, 112; 211, 212) internal to said body, said piston being adapted to slide in said body, and thus to modify sizes of said chambers, - at least one rod (13; 23; 43; 73; end (131; 231) integral with said piston, said rod being partially included in one of said chambers (112; 212) and adapted to be slidably engaged in said chamber by sliding of said piston, and - at least one guide piece (14; 24; 44; 74) of said shank in said body, said workpiece being bonded to said body and including at least one sliding passage aperture (141) of said shank through said workpiece, characterized in that said tubular body being configured according to at least one guideline followed substantially loosely by ledi t piston, said piston is connected to said rod by a connection (15; 25) allowing at least one degree of freedom in rotation along an axis perpendicular to said guideline. 2. Cylinder (1; 2; 4; 7; 8) according to claim 1, characterized in that the guide line of said body extends in a plane and said connection (15; 25) between said piston and said rod allows the at least one degree of freedom in rotation along an axis perpendicular to said plane. 3. Cylinder (1; 2; 4; 7; 8) according to one of claims 1 or 2, characterized in that said connection (15; 25) between said piston and said rod is a ball joint. 4. Cylinder (1; 2; 4; 7; 8) according to any one of the preceding claims, characterized in that said guide piece (14; 24; 44; 74) authorizes with respect to said body at least one degree of freedom in rotation of said rod along an axis perpendicular to said guideline. 5. Cylinder (1; 2; 4; 7; 8) according to any one of the preceding claims, characterized in that at least one pair formed of said piston and said body on the one hand, and said rod and said a guide piece, on the other hand, has a connection (16, 18; 26, 28) of the sliding pivot type. 6. Cylinder (2; 4; 7; 8) according to any one of the preceding claims, characterized in that it forms a vehicle suspension damper, said tubular body (21; 41; 71; 81) being adapted to being connected to at least one ground connection element (51; 55) of said vehicle and said rod (23; 43; 73; 83) having another end adapted to be connected to at least one suspended element of said vehicle. 7. Cylinder (4) according to claim 6, characterized in that said body (41) being adapted to be connected to a wheel pin (51) on one side of said body, said body is configured to form said side at least one concavity (410) of said guideline, said concavity being adapted to face a wheel (52) mounted on said wheel pivot. 8. Cylinder (7) according to any one of the preceding claims, characterized in that it forms a vehicle suspension damper which comprises at least one lower helical spring seat fixed on said body (71) and adapted to receive a a coil spring (705) surrounding a length of said body above said lower seat, said body being configured to form at least one curvature (710) of said guide line and said lower seat spring being secured below at least a portion of said curvature, such that said spring (705) at least partially surrounds said curvature. 9. Vehicle, in particular a motor vehicle, characterized in that it comprises at least one jack (1; 2; 4; 7; 8) according to any one of claims 1 to 8. 10. Vehicle according to claim 9, characterized in that said cylinder (8) according to claim 6, said body (81) of said cylinder being adapted to be connected to a wheel pivot and having a main right part (813) and a curved lower portion (814), and in that a wheel mounted on said wheel pivot having a camber (91) varying according to a clearance (92) of said wheel, said body of said cylinder and said positioning of said cylinder in said vehicle are adapted so that said camber attack (941) remains negative including maximum travel of current operation.