KR20010013819A - Suspension structure in particular for motor vehicle - Google Patents

Abstract

The present invention relates in particular to a vehicle elastic suspension structure for a motor vehicle. The suspension structure is symmetrical with respect to the vertical plane receiving the longitudinal axis of the vehicle and is mainly flexible in the vertical direction and to a lesser extent in the horizontal direction with respect to the vertical plane receiving the longitudinal axis of the vehicle. The suspension structure includes at least three flexible arms that merge and join at one end. The vertically extruded surface area of the structure is inscribed in the polygonal joint of the free ends of the adjacent arms, each end of which is directly or indirectly connected to the wheel support. Each arm is connected to the passenger compartment of the vehicle by a flexible connection with anisotropic stiffness between the end connected to the other arms and the end connected to the wheel support, the flexible connection being connected to the respective arm for each arm. Provides degrees of freedom of rotational movement about an axis adjacent to the horizontal plane perpendicular to the arm in position and lower degrees of freedom of movement for rotations about orthogonal axes and linear movements along each of the other five axes, in particular the seam axis. Providing.

Description

Suspension Structure for Vehicles {SUSPENSION STRUCTURE IN PARTICULAR FOR MOTOR VEHICLE}

Techniques well known in the art use separate means to provide guidance and stiffness: such techniques induce the movement of each wheel relative to the portion of the vehicle in which the function is floating in the air. Parts (tripods, trail arms, etc.) and elastic members (coil springs, torsion bars, etc.) that make up springs whose function is to store and restore energy.

A drawback of this technique is the use of multiple component parts, which means expensive assembly costs.

To achieve a good level of comfort for the occupant of the vehicle, rolls (particularly for multi-purpose vehicles (MPVs) with high roll inertia) are obtained to obtain a minimum roll angle for a given transverse acceleration rather than hunting associated with the natural frequency of human walking. Stiffness in the wheel is indispensable.

The conventional solution was to add an anti-roll bar to each axle.

In addition to increasing the number of components, this method increases stiffness in wheels that are loaded alone to cross road obstacles.

The force transmitted to the structure of the vehicle doubles and the change in acceleration applied to the occupant is consequently higher, resulting in less comfort.

In addition, this additional stiffness does not work at a pitch that would be beneficial to limit the brake angle for a given deceleration.

Thus, the prior art solution is not satisfactory.

Achieving a good level of comfort for the occupant of the vehicle with limited suspension movements requires variable stiffness: low when in static equilibrium and high stiffness in compression and expansion when out of this state.

In this way, small variations in the wheel's position relative to the static equilibrium position lead to small variations in acceleration, which contributes to comfort.

On the other hand, high stiffness is required for large road obstacles in order to allow the resulting working force to sufficiently regulate the movement trajectory of the vehicle, thereby creating a condition for satisfactorily crossing the road obstacle.

Patent FR 2 563 301 (button) proposes a device made of a transverse elastic leaf spring between two ends and which does not respond to roll motion. However, this doubles the stiffness in the wheels on which the load is applied alone, compared to the case in hunting, increasing the strength of the "bumps", which degrades comfort.

One way to limit this malignant effect is to reduce the stiffness of the device in hunting and to compensate for the high static deflection resulting from prestressing the leaf spring.

In order not to provide this prestressing treatment which would increase the assembly time on a vehicle assembly line, patent FR 2 600 016 (button) describes the installation of a prestressed leaf spring in a subframe and subsequent assembly into the vehicle. However, this solution has the drawback of having multiple components.

Patent FR 2 624 446 (button), based on the use of a leaf spring with a rigid end, describes a method of reducing the number of components and using the law of progressive stiffness to eliminate the malicious effects described above. However, this solution is counteracted by the need for delicate cross-arranged mounting at each end of the leaf spring.

In addition, in addition to the above, the solution of using a laid-up leaf spring has the drawback that it interferes with the mounting of the engine between the wheels of the axle on which the engine is driven. This method of construction requires the engine to be mounted or moved to the passenger compartment in a cantilevered manner, which will cause an increase in moment of inertia in the pitch that impairs comfort, which also reduces the internal space of the available vehicle and reduces frontal impact. City is very dangerous.

When the wheels move relative to the vehicle, conventional suspension structures cause high forces in the front and rear that require high structural stiffness in torsion and bending.

This limits the possibility of reducing the mass of these parts and therefore disadvantages dynamic behavior, safety and power consumption.

Simplification of the front and rear ends of the vehicle is appropriate because it is possible to partly believe in collision safety against the use of deformable lightweight materials, as is well known in the art, which is advantageous for weight reduction of the vehicle.

This also results in an overall reduction in the size of the vehicle, which also results in a mass reduction.

Prior art anti-roll devices (such as anti-roll bars) induce stiffness against the torsion of quadrilaterals where the points in contact with the road surface partition, thereby hindering road surface maintenance performance.

Patent FR 2 640 205 (Reno) provides an isostatic suspension in which the quadrilateral torsion in which the points of contact with the road are partitioned for the purpose of limiting the torsional and bending stresses on the structure of the vehicle is independent of the road surface load. have.

However, apart from the fact that the leaf springs on the axis of the axle interfere with the positioning of the engine, this solution requires a number of components and connections.

In addition, as noted more clearly in the proposed solution, the movement trajectory of the vehicle is not controlled by any movement of the wheel with respect to the floating part of the vehicle. Thus, this relative movement can easily reach the maximum value allowed by the geometry of the suspension, resulting in bumping.

Such bumping will adversely affect comfort and will severely stress the structure of the vehicle, which is not suitable for its intended purpose.

Finally, the suspension is also required to be longitudinally resilient in order to limit the extreme forces arising from crossing very steep road obstacles (eg sidewalks) at a given speed.

Conventional elastic supports and pivots may only impose limited bending possibilities for structures of known art in order to maintain acceptable geometric shapes.

The Pionet suspension structure described in FR-A-2 552 718 connects four wheels by means of a flexible frame comprising two longitudinal leaf springs and two transverse leaf springs. And that's why it's effective.

However, these structures have the drawback that they interfere with positioning the engine between the wheels of the axle and have lower stiffness on the roll than in hunting.

Finally, the suspension should eliminate as much vibration as possible from tires rolling on the road.

Prior art structures connect the suspension to the vehicle structure by two stages of flexible connections through the subframe, which does not contribute to anisotropy for stiffness of the final assembly.

The present invention relates in particular to suspensions for motor vehicles, and more particularly for, but not limited to, four wheel vehicles.

1 is a cross-sectional view of a suspension structure according to the invention taken with respect to the contour of the vehicle along line B2-B2 of FIG. 2;

2 is a plan view taken along line A1-A1 of FIG. 1;

3 is an illustration of a suspension structure according to the invention when the wheel crosses a road obstruction;

4 is a plan view of the same situation;

5 is a cross-sectional view of the elastic suspension structure according to the invention taken along line B6-B6 of FIG. 6 when the wheel passes the sidewalk at a given speed;

6 is a plan view of the same situation;

7A is a front view of one arm of the suspension structure according to the present invention cut away in the position where one arm merges into the other arms;

7B is a plan view of the same arm in the position where one arm is merged into the other arms;

8 is a cross-sectional view of the suspension structure according to the invention taken with respect to the contour of the vehicle along the lines B9-B9 of FIG. 9;

9 is a plan sectional view of the suspension structure according to the invention taken with respect to the contour of the vehicle along line A8-A8 in FIG. 8;

10 is a detailed view of the transverse cross section.

It is an object of the present invention to propose a simple structure for optimizing the dynamic behavior of a vehicle to achieve a good level of comfort for passengers.

FIELD OF THE INVENTION The present invention relates to an elastic suspension structure for a vehicle, more particularly for a motor vehicle, which structure is symmetrical about a vertical plane that receives the longitudinal axis of the vehicle and which accommodates the longitudinal axis of the vehicle. A vertically extruded surface of the structure, comprising at least three flexible arms which are primarily vertically flexible with respect to the vertical plane, to a lesser extent in the horizontal direction, and joined and merged together at one end; The region is inscribed in the polygon connecting the free ends of adjacent arms, each end connected directly or indirectly to the wheel support.

Each arm is an elastomeric structure according to the invention connected to the passenger compartment of the vehicle between its end connected with the other arms and its end connected with the wheel support.

Most typically, the arms are connected by flexible connections with anisotropic stiffness, providing degrees of freedom of rotational movement about an axis adjacent to the horizontal plane perpendicular to the arm at the location of the connection and each of the other five arms It provides less degrees of freedom of movement, especially with respect to the linear and orthogonal axes along its seam axis.

This connection can be in the form of a flexible pivot, an elliptical support, a pair of elastic supports or any elastomeric device with anisotropic stiffness.

The width-to-thickness ratio of the major portion of each arm advantageously has at least one minimum near the position of the arm connection to the passenger compartment and at least one maximum near the position at which the arms merge. In the presence of strong vertical loads the horizontal extrusion onto the vertical plane for each arm's profile can be straight from its end connected to the wheel support to the end connected to the passenger compartment of the vehicle.

In a strong vertical load, the horizontal direction acting on the end of the arm engaged with the wheel support, in the part of the arm between the portion of the connection where the end of the arm is joined by the wheel support and the part that is connected to the passenger compartment of the vehicle. The torsion caused by the force is canceled out.

To increase the energy storage capacity, each arm may have one or more transverse ribs at the center between the end connected with the other arms and the connection to the vehicle's passenger compartment.

The additional stiffness portion provided by a spring or a contact made of rubber composite, preferably receiving a cavity filled with pressurized gas adapted to the speed and / or load of the vehicle, for example, is provided in the center of the suspension structure and in the vehicle's boarding. It can be installed between the cabins and this stiffness part is limited by the connection to the passenger compartment of the vehicle.

Particularly in a four-wheeled vehicle, the suspension structure is rigid in a subframe that is rigid in the horizontal plane, symmetrical with respect to the vertical plane that accommodates the longitudinal axis of the vehicle, flexible against torsion and rigid against loads other than torsional loads. Can be connected to the passenger compartment of the vehicle, the subframe being advantageously reduced towards the junction point supporting the connection to the suspension structure, the main part of which is curved on the side and the main part between the subframes joined to the vehicle by four connections. Open in a manner such that the two connections are termed "lengthwise" because they are located in the longitudinal symmetry plane of the subframe and the two connections are on the transverse axis crossing the symmetry plane at a suitable selected point at the same distance from the longitudinal connection. Named as "crosswise" because do.

The connection is a flexible connection with isotropic stiffness as a whole and provides a degree of freedom of movement in rotation about each longitudinal or transverse axis, in particular each with respect to rotation about a straight and orthogonal axis along the seam axis. With respect to the axis it provides a lower degree of freedom of movement.

Each of these connections may be in the form of a flexible pivot, an elliptical support, a pair of elastic supports or any elastomeric device with anisotropic stiffness.

This provides a desirable treatment for torsional motion and the resulting flexibility reduces the stiffness of the suspension against torsion, which optimizes dynamic behavior and especially comfort.

The suspension structure and the subframe according to the invention can be made of any material having a high rate of bending to fatigue resistance, preferably a synthetic material consisting of fibers oriented and inserted in at least two directions in the resin, for example glass- It may be made of an epoxy resin.

Features of the present invention are described with reference to FIGS. 1 to 10 together with embodiments for a four-wheeled vehicle.

Claims (8)

7. The contact as claimed in claim 2, provided by a spring or a contact made of a rubber composite, preferably containing a cavity filled with pressurized gas, eg adapted to the speed and / or load of the vehicle. The additional stiffness part 7 can be installed between the central part 199 of the suspension structure and the passenger compartment of the vehicle 3, which stiffness part is limited by the connection to the passenger compartment of the vehicle 3. Suspension structure (1). 10. Suspension structure according to any one of the preceding claims, characterized in that it comprises four arms (11, 12, 13, 14) each corresponding to a wheel 2 or 2 'of the vehicle. One). 9. The subframe (5) according to claim 8, wherein the suspension structure (1) is subframe (5) which is symmetrical with respect to the vertical plane which receives the longitudinal axis of the vehicle, is rigid in its plane, flexible against torsion and more rigid against other loads. Is connected to the passenger compartment of the vehicle 3, the subframe may be a rectangular frame with curved sides, the main part of which is a suspension structure in which the subframe is between the parts joined to the vehicle by four connections. It is open in an advantageously diminishing manner towards the junctions supporting the furnace connections 6, and the two connections 41 are called "lengthwise" because they are located in the longitudinal symmetry plane of the subframe, and the two connections 42 is on the transverse axis intersecting the plane of symmetry at a suitably selected point that is the same distance from the longitudinal connection. Suspension structure, characterized in that it is named "cross direction". 10. Each of the " lengthwise " 41 or " crosswise " 42 subframe connections is a flexible connection with isotropic stiffness and has a degree of freedom of rotational movement about each longitudinal or transverse axis. Suspension structure (1), characterized in that it provides a lower degree of freedom of movement for each of the other five axes, in particular for linear movements along the seam axis and rotation about orthogonal axes. Suspension structure (1) according to any one of the preceding claims, characterized in that it is made of a material made of fibres inserted in a synthetic resin oriented in at least two directions. Wheel suspension, characterized in that it comprises at least one arm which is part of the suspension structure (1) of any one of the preceding claims. Suspension, in particular for motor vehicles, characterized in that it comprises an elastic structure (1) according to one of the preceding claims. An automobile comprising a suspension according to claim 13.