FR2812242A1 - Automobile deformable axle comprises pair of longitudinal suspension arms connected by torsion deformable crosspiece, one end of each arm connected to bodywork by elastic articulation and one end to wheel hub - Google Patents

Abstract

The axle comprises a pair of longitudinal suspension arms (1), which support the vehicle bodywork, connected by a torsion deformable crosspiece (2). One of the ends of each arm carries a wheel hub whilst the other end is connected to the bodywork by means of an elastic articulation (4) with a transverse horizontal axis (Y-Y'). The articulation has a torsion stiffener with an angular displacement amplitude sufficient to ensure the bodywork suspension with recourse to additional springs. It also has a weak stiffener in the longitudinal direction (X-X') allowing translation displacement of the arm relative to the bodywork over a specified path.

Description

The present invention relates to a deformable axle with suspension

  integrated for motor vehicle.

  By the expression "motor vehicle" is meant herein

  description and related claims, not only vehicles

  automobiles proper, but also trailers and caravans, and others

  towed rolling machines, also capable of being fitted with this kind of axle.

  More specifically, the object of the invention is a deformable axle of the type comprising a pair of longitudinal suspension arms which support the vehicle body, and are connected to each other by a torsionally deformable cross member, the one end of each arm (directed towards the rear of the vehicle) carrying a wheel hub, while its other end (directed towards the front) is connected to the body of the vehicle by means of an elastic articulation device , of horizontal transverse, or approximately transverse, axis, comprising members

in elastomeric material.

  This type of axle is generally used on modern motor vehicles with front-wheel drive, to ensure the connection of the body with the

rear wheels, not driving.

  Traditionally, each of the arms supports the vehicle body,

  by means of a shock absorber associated with a helical metal spring.

  The function of the spring is to support the load of the vehicle, corresponding approximately to a quarter of the total mass of the body,

  keep the attitude horizontal and ensure the flexibility of the suspension.

  The function of the elastic articulation device is to ensure filtering between the stresses coming from the road and the body, and to provide a guiding function by giving the axle a comprising understeer ensuring a

good cornering trajectory.

  The cross which connects the two arms, has a stiffness in bending

  very high, but can work at torsion, playing an anti-roll role.

  On these known devices, the suspension springs are

  relatively expensive heavy and bulky.

  An objective of the invention is to eliminate these springs, as well as the support cups with which they are generally associated, by making each aforementioned elastic articulation device play, not only only the role of filtering the vibrations occurring between the body and the road but also the function

suspension.

  FR-A-2 778 605 already knows a vehicle axle

  equipped with an elastic articulation device ensuring the suspension function.

  To this end, this articulation consists of a bearing made of elastomeric material pierced by two cells, which give the articulation the desired stiffness,

  while giving it sufficient angular movement.

  However, this known axle does not, or practically does not,

  of elasticity between the body and the axle arms in the longitudinal direction.

  This results in jolts in the transmission between the body and the

  wheels, especially as a result of vehicle acceleration and braking.

  This is why another objective of the invention is to propose a

  articulation device of the aforementioned kind which makes it possible to best absorb these

  blows (shocks), allowing a gentle transmission of forces between the body and the wheels, and vice versa, and correspondingly offering great comfort and safety

  optimal driving for the user.

  These objectives are achieved, in accordance with the invention, thanks to the fact that the elastic articulation device, on the one hand, has a torsional stiffness, and has an amplitude of angular movement, which are sufficient to ensure the function of suspension of the body, without the need for additional springs which would be interposed between the body and said arms and, on the other hand, has a low stiffness in the longitudinal direction, allowing movement in translation, over a determined stroke, ( in a horizontal plane or

  close to a horizontal plane) of the arm relative to the body in this direction.

  Furthermore, according to a certain number of additional advantageous, but not limiting, characteristics of the invention: - the torsional stiffness of the elastic joint is between and 100 mN /, and is preferably of the order of 80 mN /; - The amplitude of angular movement of the elastic joint is between +20 and + 35, and is preferably of the order of + 30; - The stiffness in translation, in the longitudinal direction, of the elastic joint is between 100 and 600 N / mm, and is preferably of the order of 200 N / mm; the displacement travel in translation, in the longitudinal direction, of the elastic joint, is between 0.1 and 5 mm, and is

preferably of the order of I mm.

  - Said elastic articulation comprises three tubular metallic reinforcements fitted coaxially one inside the other, and consisting of a central core receiving the articulation axis; - an intermediate hollow body; - an external box; and the intermediate hollow body is connected both to the outer casing and to the central core, by interfaces of adhered elastomeric material, one of which

  works in torsion, and the other works in longitudinal translation.

  - at least one of the two interfaces is laminated, comprising a rigid insert embedded in the mass of elastomeric material; - The interface which works in torsion consists of a tubular sleeve, the internal and external walls of which have a polygonal section; - the interface which works in longitudinal translation comprises loaves of elastomeric material whose deformation results from shear forces - the interface which works in longitudinal translation comprises at least one pair of loaves of elastomeric material, located one at- above, and the other below, the axis of the joint; - The interface which works in longitudinal translation comprises two pairs of loaves of elastomeric material, one located in front, and the other behind, of the joint; the interface which works in longitudinal translation comprises two compression stops made of elastomeric material, intended, one, to absorb the acceleration forces and, the other, the braking forces of the vehicle, these stops being located respectively at before and behind the axis of the joint; - The interface which works in torsion is interposed between the central core and the intermediate hollow body, while the interface which works in longitudinal translation is interposed between the intermediate hollow body and the external housing; - The interface which works in longitudinal translation is interposed between the central core and the intermediate hollow body, while the interface which works in torsion is interposed between the intermediate hollow body and the external housing; - Said central core is secured to the vehicle body, while said outer box is secured to the arm; said central core is secured to the arm, while said outer box is secured to the vehicle body - the vehicle body is linked to each of said arms by

through a shock absorber.

  The present also relates to an elastic articulation device which is intended to equip a deformable axle having the characteristics mentioned above. Other characteristics and advantages of the invention will become apparent from the

  description which will now be made of it, with reference to the appended drawings, on

  which: - Figure I is a schematic perspective view of a traditional deformable axle; - Figure 2 is a view similar to Figure 1, showing a deformable axle with integrated suspension according to the invention; - Figure 3 is a perspective view of a first mode of elastic articulation device, equipping the deformable axle illustrated in Figure 2; - Figure 4 is a front view of the device of Figure 3; - Figure 5 is a side and sectional view of the device of Figures 3 and 4, the section plane being designated V-V in Figure 4; - Figures 6 and 7 are half-views similar to the view of Figure 2, which show different mounting methods of the articulation device at the end of one of the two arms of the axle; - Figure 8 shows a second possible embodiment of the articulation device; - Figure 9 shows the device of Figure 8 cut by a plane perpendicular to the hinge axis; - Figure I0 is a detail view, in perspective, showing the central part of this device; - Figure 11 is a perspective view similar to that of Figure 2, showing a deformable axle provided with the articulation device of the figures

8 and 9.

  In the drawings, the direction X-X 'has designated the direction

  longitudinal of the vehicle, and by the reference Y-Y ', its transverse direction.

  These two axes are located in a horizontal plane.

  The front arrow corresponds to the front of the vehicle.

  FIG. 1 shows a traditional deformable axle,

  intended to support the two rear wheels, not driving, of a motor vehicle.

  This axle is composed of two parallel longitudinal arms 1,

  approximately horizontal, connected by a cross 2.

  This cross member is generally a profile open at the bottom, of

  "U" or inverted "V" section, which acts as a torsion bar.

  The axle has a symmetrical configuration with respect to a vertical plane

longitudinal median.

  This applies to the description of the axle structure located on one

  on the sides of the vehicle, also applies to the other side, as well for the condition of the

  Figure 1 technique for the subject of the invention.

  At its front end, each arm 1 is integral, for example by

  welding, of a metallic tubular sleeve 3, for example of cylindrical shape.

  This coaxially surrounds a central core 30, also metallic. Elements 3 and 30 are connected by a ring of elastic material,

  rubber or elastomeric material, referenced 31.

  The core 30 is crossed by a central opening, which makes it possible to

  make it integral with the vehicle body, for example by means of a screw.

  This link - not shown - ensures complete immobilization

  of the core 30 relative to the body, both in translation and in rotation.

  In the example illustrated, the axis of the core 30 corresponds to the direction

transverse Y-Y '.

  However, provision may be made for the axis W-W 'of this core to form an angle a with respect to the transverse direction, this angle being thus oriented so that the

  two W-W 'axes form a very open "V", the point of which is directed forward.

  Such angulation allows the axle to move relative to the

  body according to a desired kinematic law.

  At its rear end, each arm I is integral with a wheel fixing hub 10, carrying a spindle with an axis 100, on which the wheel is centered,

this in a well known manner.

  The rockets 100 are of course directed towards the outside of the vehicle. On the inner side, each arm carries a stirrup 11, to which is fixed a

  shock absorber 12 directed green the top.

  This supports a helical spring 9 which, by means of a support cup 90 made of elastomeric material, supports the body of the vehicle (not shown). The axis Z-Z 'of the shock absorber system 12 / spring 9 is vertical, or

substantially vertical.

  In FIG. 2, the same references have been kept as in FIG. 1,

  to designate the elements common to the two figures.

  It can be seen that the springs 9 and the associated cups 90 have been

  deleted. The body is linked to the shock absorber rods 12.

  The front end of each arm 1 is secured to a device

  elastic articulation according to the invention, and which will be described in detail below.

  In the embodiment illustrated in FIG. 2, the device 4 comprises an outer casing 5, at the rear of which is welded a tubular flange, the cross section of which (apart from the interlocking clearance) corresponds to that of the portion

forearm 1.

  This portion of the arm I is fitted into the flange 40, and is there

fixed with screws 400.

  It goes without saying that the end of arm I could be welded directly

on the rear face of the housing 5.

  Furthermore, as will be seen with reference to FIGS. 6 and 7,

  other mounting methods can be envisaged.

  In the examples illustrated below, the axis of articulation of the

  4 devices is strictly transverse, corresponding to the direction YY '.

  However, the invention also covers, of course, configurations in which an angulation oc, as mentioned above, is provided. With particular reference to Figures 3 to 5, we will

  now describe the structure of the articulation device 4.

  This comprises an outer casing 5. of tubular shape

generally square.

  As an indication, the housing 5 has a height of 70 mm, a width of

  mm and a length (dimension along Y-Y ') of approximately 100 mm.

  More specifically, as can be seen in the figures, the front 51 and rear 53 faces of this box 5 are flat, while its upper 50 and inner 52 faces are curved in their central part, in the form of a cylinder portion, the convexity is directed outward (upward and downward, respectively). Inside the housing 5 is housed a hollow body 6, called "intermediate", whose outer wall has a similar profile, but smaller

dimensions, to that of the housing 5.

  Thus, a peripheral free space 55 is created, of approximately constant width, between the interior walls of the housing 5 and the exterior of the

body 6.

  Inside the body 6 is a core 7.

  It is a tubular part, having a central cylindrical opening 70, and an outer wall in the form of a regular prism, in this case at

base in the shape of a regular octagon.

  The core 7 can be fixed to the vehicle body by any known means, so as to ensure its immobilization both in rotation (around

the axis Y-Y ') only in rotation.

  This fixing can be achieved for example by means of a screw passing through the bore 70 and screwed fully into a tapped hole formed in the body, so as to ensure (by the screw head) sufficient tightening to block the core

against the cash register.

  The opening 70 could also be grooved, allowing immobilization in rotation by fitting on a complementary grooved shaft

carried by the body.

  Tubular parts 5, 6 and 7 are metallic, for example steel

  or aluminum, of great resistance.

  These four parts are arranged coaxially, centered on the axis Y-

  Y '. As seen in Figures 3 and 4, the part 7 has a slightly larger axial dimension than that of the parts 5 and 6 which, themselves, have the same

  axial dimension, so that it projects on each side of the housing.

  In the example illustrated, the part 6 has an inner wall of polygonal section, similar to that of the outer wall of FIG. 7, but offset

  angularly of the value of a half-face, compared to the latter.

  Between these two parts is interposed a mass 8 of elastomeric material, which is adhered as well as on the external wall of the part 7 that

  on the internal wall of part 6.

  In the example illustrated, we are dealing with a so-called "laminated" elastomer, composed of two masses, one interior 81, the other exterior 80, between which

  is interposed a tubular frame 82, preferably also made of metal.

  In the example illustrated, the tubular frame 82 has an inner wall of octagonal profile, similar to that of the outer wall of the core 7, and a cylindrical outer wall. The elastomeric masses 81, 80 are also adhered to

these walls.

  Other forms of reinforcement can, of course, be envisaged. A laminated structure of this type, as is well known, makes it possible to appreciably increase the torsional stiffness of the mass of elastomeric material 8, practically without affecting the amplitude of angular displacement.

(around the axis Y-Y ').

  The intermediate body 6 is secured to the housing 5 via

  of four loaves of elastomeric material 62.

  Two loaves referenced 62a, are provided on the top of the part 6,

  one at the front and one at the back.

  Similarly, two loaves 62b are provided on the underside of the part 6,

  one at the front and one at the back.

  They are in the form of strips of low height

  extending in the direction Y-Y 'over the entire length of the element 4.

  According to the direction X-X 'they have a substantially greater width

than their height.

  These breads 62 also have a laminated structure, and are composed

  of two parts separated by a rigid strip 620, for example made of metal.

  They are adhered both to the outer wall of the body 6 and to the

inner wall of the housing 5.

  On the front and rear faces of the body 6 are fixed, also by adhesion, curved pads 60, respectively 61, the convexity of which is directed

outwards.

  These pads are also made of elastomeric material; in the illustrated embodiment, the pads 60, 61 are supported by their most forward generator or,

  respectively the rearmost, against the walls 51, respectively 53 of the housing 5.

  However, it would be possible to provide some initial play between these elements. Reverse mounting is of course possible, according to which the pads 60, 61 are adhered against the internal faces of the walls 51, 53 of the housing 5 and serve

body stops 6.

  In the event of wheel travel, the arm 1 is - correlatively - the

  housing 5 of which it is integral, is subjected to a torque around the axis Y-

  Yt. This torque is transmitted directly to the body 6, without - or practically without - relative movement between these two parts; indeed the structure

  laminated pads 62 gives them a very high stiffness in compression.

  It is therefore the mass of elastomer 8 which takes up the torque, and there is an angular movement, around Y-Y '- in one direction or the other -,

  of the assembly 5/6 relative to the core 7, integral with the body.

  In case of acceleration of the vehicle, there is a decline in the housing 5

according to X-X '.

  This decline is possible, thanks to the low stiffness of the elastomeric bars 62 in the longitudinal direction; these work in shearing in a horizontal plane allowing a displacement in relative translation of the housing 5 relative to

all 6/7.

  However, during this movement, the shoe 60 crashes, forming a

  elastic stop, which limits said travel, smoothly and gradually.

  Likewise, always in a gentle and progressive manner, the whole

  resumes its initial configuration when acceleration stops.

  In the event of braking, the same phenomenon is observed, but in direction

  reverse, with crushing of the rear stop 61.

  Figures 6 and 7 show other possible mounting methods

  of the device 4 at the front end of the arm 1.

  In FIG. 6, the housing 5 is mounted on the upper face of the arm 1, the fixing being ensured by a bracket 41 in the form of an inverted "UJ", enclosing the housing 5, and having lower edges folded at right angles by which he is

  fixed by means of screws 410 to arm 1.

  In FIG. 7, it is the housing 5 which is secured to the body, this by means of a "U" bracket 42, adapted to be fixed by its folded edges

  420, by means of screws, against the body.

  The end of the arm I carries a yoke 15 which is crossed by a fixing member such as a bolt 150, ensuring the joining of the central core

  7, with the yoke 15, and therefore with the arm 1.

  It is therefore a kinematically reversed assembly compared to

precedents.

  On the embodiment of the articulation device shown in FIGS. 8 to 11, the same reference numbers have been kept as in the first embodiment for designating the similar elements, but by

affecting the "prime" index.

  The fundamental difference between the two variants is that, in the second embodiment, the torsional deformation (angular movement of the arm) takes place between the outer casing 5 ′ and the intermediate hollow body 6 ′, while the displacements in the longitudinal direction between the 7 'core and the body

intermediate 6 '.

  In this embodiment, as can be seen in particular in FIG. 10, the core 7 ′ has the shape of a cylinder cut by two parallel horizontal planes, constituting an upper flat which carries a bread 62 ′ a and a flat

lower carrying a bread 62'b.

  The semi-cylindrical front and rear parts of the core 7 'are

  coated with a layer of elastomeric material 60 ′, respectively 61 ′.

  The inner wall of the body 6 ′ is similar to that of the core 7 ′, and there is an annular space between these two parts, which allows the desired longitudinal movement, the flexible linings 60 ′, 61 ′, acting as stops,

  respectively acceleration and braking, as previously described.

  The outer box 5 'has a cylindrical outer wall, and a wall

polygonal interior.

  The body 6 ′ also has a similar polygonal outer wall, the parts 6 ′ and 5 ′ being connected by a mass of elastomeric material 8 ′, similar to the

  mass 8 of the first embodiment.

  It is this mass that works at torsion, in the event of travel

angle of the arm.

  As shown in Figure 11, the front end of the arms 1 can

  simply be welded to a 5 'box.

  The core 7 'is fixed to the body by suitable means of known type, not shown, It

Claims (17)

  1. Deformable axle for a motor vehicle, which comprises a pair of longitudinal suspension arms (1) intended to support the body of the vehicle and connected to one another by a cross member (2) deformable in torsion, one of the ends of each arm (1) carrying a wheel hub, while its other end is connected to the vehicle body by means of an elastic articulation device (4), of horizontal axis (Y- Y ') , or approximately transverse, comprising members of elastomeric material, characterized in that said elastic articulation device (4), on the one hand, has a stiffness in torsion and has an amplitude of angular movement which are sufficient to ensure the body suspension function, without the need for additional springs which would be interposed between the body and said arms (1) and, on the other hand, has a low stiffness in the longitudinal direction (X- X '), authorizing a displacement in translation, over a determined stroke, of the arm (1) by   report to the body following this direction (X-X ').   2. Axle according to claim 1, characterized in that the torsional stiffness of the elastic joint (4) is between 30 and 100 mN /,   and is preferably of the order of 80 mN /.   3. Axle according to claim 1 or 2, characterized in that the amplitude of angular movement of the elastic joint (4) is included   between + 20 and + 35, and is preferably of the order of + 30.   4. Axle according to one of claims I to 3, characterized in that   that the stiffness in translation, in the longitudinal direction, of the elastic joint (4) is between 100 and 600 N / mm, and is preferably of the order of N / mm.   5. Axle according to one of claims 1 to 4, characterized in that   that the displacement travel in translation, in the longitudinal direction, of the elastic joint (4) is between 0.1 and 5 mm, and is preferably of the order of I mm.   6. Axle according to one of the preceding claims, characterized by   the fact that said elastic articulation (4) comprises three tubular metallic reinforcements (7, 6, 5) fitted coaxially one inside the other, and consisting of - a central core (7) receiving the articulation axis; - an intermediate hollow body (6); - an outer box (5); and that the intermediate hollow body (6) is connected both to the outer casing (5) and to the central core (4), by interfaces of adhered elastomeric material, one of which (8)   works in torsion, and the other (60-61, 62) works in longitudinal translation.   7. Axle according to claim 6, characterized in that at least one of the two interfaces is laminated, comprising a rigid insert (82, 620)   embedded in the mass of elastomeric material (8, 62).   8. Axle according to claim 6 or 7, characterized in that the interface (8) which works in torsion consists of a tubular sleeve, the   internal and external walls have a polygonal section.   9. Axle according to one of claims 6 to 8, characterized in that   that the interface which works in longitudinal translation has loaves in   elastomeric material (62) whose deformation results from shear forces.   10. Axle according to claim 9, characterized in that the interface which works in longitudinal translation comprises at least one pair of loaves of elastomeric material (62a, 62b), located one above, and the other below , of the axis (Y-Y ') of the joint.   ilo Axle according to claim 10, characterized in that the interface which works in longitudinal translation comprises two pairs of loaves of elastomeric material (62a, 62b), one located in front, and the other in rear, of the axis (Y-Y ') of the joint.   12. Axle according to claim 9 or 10, characterized in that the interface which works in longitudinal translation comprises two compression stops made of elastomeric material (60, 61), determined, one, to absorb the acceleration forces and, the other, the braking forces of the vehicle, these stops being located   respectively in front and behind the axis (Y-Y ') of the joint.   13. Axle according to one of claims 6 to 12, characterized by the   fact that the interface (8) which works in torsion is interposed between the central core (7) and the intermediate hollow body (6), while the interface (60-61, 62) which works in longitudinal translation is interposed between the intermediate hollow body (6) and the outer case (5).   14. Axle according to one of claims 6 to 12, characterized by the   means that the interface (60'-61 ', 62') which works in longitudinal translation is interposed between the central core (7 ') and the intermediate hollow body (6'), while the interface (8 ') which works in torsion is interposed between the hollow body   intermediate (6 ') and the outer box (5').   15. Axle according to one of claims 6 to 14, characterized by the   that said central core (7) is integral with the body of the vehicle, while said   outer casing (5) is integral with the arm (1).   16. Axle according to one of claims 6 to 14, characterized by the   that said central core (7) is integral with the arm (1), while said housing   exterior (5) is integral with the vehicle body.   17. Axle according to one of claims 1 to 16, characterized by the   fact that the vehicle body is linked to each of said arms (1) via a shock absorber (12).   18. Elastic articulation device (4) intended to equip an axle   deformable according to at least one of the preceding claims.