FR2838093A1 - Intermediate fork shaft for automobile steering column comprises rod and fork connected by balls held between longitudinal grooves in rod and cage surrounding rod - Google Patents

Abstract

The shaft is composed of a rod (1) and a fork (2) connected to each other by balls (5) allowing the rod to telescope. The balls are held between longitudinal grooves (6) in the rod and longitudinal grooves (9) in a cage (10) surrounding the rod end. The cage is connected to a tubular part (3) of the fork by an elastic tubular element (11) located around the cage. This dampens any vibration whilst allowing a slight angular displacement of the rod relative to the fork. This angular displacement is limited by angular stop parts (15,17) located between the cage and the tubular part of the fork.

Description

3, [; ?,?., 6 p \ The present invention relates to a fork shaft

  constituting an intermediate shaft, in particular in a steering column of a

automobile car.

  The fork shift is a shaft for the movement of rotation which in the case of the steering column of a motor vehicle is an intermittent movement in both directions. This tree is composed of a metal rod assembled to a piece forming a fork, also metallic. The fork part o is provided with an axial hole, which may or may not be through, in which the

rod is force fitted.

  To facilitate assembly, but above all to improve driver safety in the event of a collision when the intermediate axis risks being pushed back in the direction of the passenger compartment and causing the steering wheel to move towards the driver at the same time as the latter is projected forward, we have proposed constructions allowing the telescoping of the rod inside the piece forming a fork. This telescoping must allow the piece forming a fork to move on the rod over a length of approximately 30 mm before transmitting this movement to this

C erNlere.

  A construction allowing this telescoping is known from EP 1

  167,785 which describes an intermediate shaft for a steering column.

  The connection in rotation between the rod and a tubular part of the fork-forming part is ensured by means of balls trapped between longitudinal grooves provided on the periphery of the end of the rod and longitudinal grooves provided on the inner face. of this tubular part of the piece forming a fork, and arranged opposite the first grooves. The balls are contiguous in the grooves and urged towards each other by a pair of pressure springs o arranged at a respective end of the facing grooves. These springs can be compressed to allow retraction of the rod in the

piece forming a fork.

  A similar construction is known from DE 198 24 477. In the example described in this document, there are no pressure springs at the ends of the grooves and the balls are arranged in aligned holes provided on a sleeve disposed at the inside the tubular part of the piece forming a fork. The second grooves are provided on a cage, itself force-fitted inside the tubular part of the piece forming a fork. Even if these constructions generally give satisfaction with regard to the possibility of obtaining the telescoping of the rod in the part forming a fork in the event of a collision, the connection between the rod and the part forming a fork in these constructions is completely rigid o and therefore likely to transmit any vibration, which can create problems from the point of view of sound insulation. This is especially the case for the intermediate shaft of a steering column of a motor car. In this environment, vibrations created by hydraulic pulsations in the steering box are transmitted under

  annoying noise in the passenger compartment.

  The invention aims to remedy this drawback by proposing a fork shaft capable of absorbing vibrations, also those caused by high frequencies, in order to dampen noise, while maintaining its ability to transmit the required torque. and o allowing the telescoping of the rod in the tubular part of the part

  forming a fork in the event of a collision.

  The object of the invention is a fork handle made up of a rod constituting the shaft proper, and of a piece forming a fork, the rod being mounted in an axial hole in a tutular part of said piece forming a fork, said rod being connected in rotation to said piece forming a fork by means of a plurality of spherical elements further allowing the telescoping of the rod inside said piece forming a fork during an axial stress on the latter, said spherical elements being trapped between so first longitudinal grooves made on the periphery of the rod and second longitudinal grooves arranged opposite the first performed in a cage surrounding said rod, characterized in that, in combination, said cage is connected to the slide part of the piece forming a fork by means of an elastic tutular element comprising nt nonlinear elastic disposed around said cage so as to dampen any vibration while allowing a slight relative angular displacement of said rod relative to said fork-forming part, this relative angular displacement being limited by angular abutment members disposed between said cage and the part

  s tubular part forming a fork.

  According to other characteristics of the invention: - said elastic tubular element is fixed to the inner face of the tubular part of the piece forming a fork; - Said elastic tubular element is fixed to the internal face of a sleeve inserted by force into the tubular part of the piece forming a fork; - The inside diameter of said sleeve is adapted to the outside diameter of said elastic tubular element so as to put the latter under prestressing; s - said cage is made of a material which is sufficiently deformable to absorb any radial clearance between said rod and said cage; - Said elastic guard element is forcibly mounted on said cage and comprises on its inner face first means of locking in rotation on said cage cooperating with second means of locking in rotation provided on the outside of said cage; said first rotation blocking means comprise longitudinal grooves and said second rotation blocking means comprise complementary ribs on the outer face of the cage; - Said complementary ribs on the outside of the cage correspond to said grooves made on the inside of said cage; - The rod, the tubular part of the piece forming a fork and said cage are cylindrical, and said angular stop means comprise at least one pin extending radially in the tubular part of the piece forming a fork so as to protrude therein. ci to be placed in a recess provided at one end of said cage and whose width delimits said relative displacement of the rod relative to

to the piece forming a fork.

  - Said recess has a width such that the maximum angular displacement corresponds to an angle of approximately 1.5 in a direction of

  either rotation of the rod.

  s - several pins are regularly distributed on the face

  interior of said tubular part of said piece forming a fork.

  Other characteristics and advantages of the invention will emerge from

  the following description of a non-limiting embodiment of

  the invention, with reference to the appended figures in which: o - Figure 1 is an exploded perspective view showing all the elements of an embodiment of a fork handle according to the invention, before assembly; - Figure 2 is a longitudinal sectional view showing the shaft according to the invention, after assembly; s - Figure 3 is a cross-sectional view along line A-A of Figure 2; - Figure 4 is a cross-sectional view along line B-B of Figure 2; - Figure 5 is a perspective view, partially in section, of a tree according to the invention; FIG. 6 is a perspective view, partially in section,

  of a tree according to the invention, seen in the other direction with respect to FIG. 5.

  In the figures, identical or equivalent elements will bear

the same signs of retention.

  Figure 1 shows the components of an embodiment of the fork handle according to the invention. The shaft has a cylindrical rod 1 connected to a part forming a fork 2 by a number of intermediate parts. Furthermore, the fork-forming part comprises a cylindrical tutular part 3 which at one of its ends o 4 carries the fork proper. Rod 1 is more precisely

  mounted in the axial hole defined by this tubular part 3.

  The tutular part can be force-fitted into the annular part or else be welded thereto. Both parties can

  also be made in one piece.

  The rotational movement of the rod 1 is in a manner known per se kansmis to the piece forming a fork 2 by means of a plurality of spherical elements in the form of steel balls 5 which are also intended to allow the telescoping of the rod inside

the piece forming a fork.

  These balls 5 are as is best shown in gures 2 and 5, housed in longitudinal grooves 6 provided on the periphery of the

  o rod 1 and extending from one of the ends thereof.

  The balls 5 are preferably kept at a distance from each other by being placed in aligned holes 7 made in a cylindrical sleeve 8 threaded on the rod 1. The balls are held captive between the grooves 6 in the rod 1 which are first grooves and second grooves 9 made in a cylindrical tubular cage 10 disposed around the hole sleeve 8. These grooves 9 may advantageously have an ogival shape which gives two lines

contact in each rainores.

  According to the invention, the cage 10 is connected to the tubular part 3 of the piece forming the fork 2 by means of a cylindrical elastic tubular element 11 with non-linear elastic behavior disposed around this cage. The tubular element 11 serves as a vibration damper, while its non-linear elastic behavior allows a certain relative angular displacement of the rod 1 relative to the part s forming a fork at the very start of a rotational movement of the rod without drive of the piece forming a fork. Of course, this is a normally very small relative angular displacement angle of

  the order of 1.0 in each direction of rotation.

  The support element 11 having a non-linearly elastic behavior is preferably made of rubber, but it could also be made of a hard plastic material such as Delrin @). The elastic guard element 11 is forcibly mounted on the cage 10 and comprises on its inner face first means for locking in rotation on the cage in the form of longitudinal grooves 12 cooperating with second means for locking in rotation in the form of complementary ribs 13 provided on the outer face of the cage 10. These complementary ribs 13 correspond to the grooves made on the inner face of the cage. This cage is preferably made of thin-walled steel so as to be deformable enough to absorb all the radial play between the rod 1 and the cage 10. As a variant, this

  cage can be made of a plastic material that can also be deformed.

  o In the example illustrated in the figures, the elastic tubular element 11 is placed inside a cylindrical sleeve 14, itself forcefully inserted into the tubular part of the piece forming a fork 2 in order to block it in rotation inside it. This sleeve is preferably metallic. s If the material used in the elastic tubular element 11 is rubber, the latter can advantageously be vulcanized directly inside the cylindrical sleeve 14. According to a variant not shown, the cylindrical sleeve has been eliminated and the rubber is vulcanized directly inside the tubular part 3 of the part

forming a fork 2.

  If the material used in the elastic tubular element 11 is a plastic material, this is preferably fixed by adhesion to the interior.

  of the cylindrical sleeve or inside the tubular part 3.

  Furthermore, the internal diameter of the sleeve 14 is preferably adapted to the external diameter of the elastic tubular element 11 of

  so as to put the latter under prestressing.

  To prevent deterioration of the elastic guard element ll over time due to abrupt rotational movements in one direction or the other, it is essential to provide angular or stop abutments arranged between the cage 10 and the tubular part of the fork piece. These angular abutment members comprise at least one pin 15 and preferably several pins regularly distributed on the inner face of the tubular part 3 of the part forming

fork 2.

  Each pin 15 extends radially inwardly through a through hole 16 in the wall of the tubular part 3 of the piece forming a fork 2. The pin extends towards the rod 1 passing through a recess 17 provided at the 'one of the ends of the cage 10. In the example illustrated, this recess has the form of a notch on the end reLord of the cage. This notch is laterally delimited by

  flanges extending parallel to the axis of the cage 10.

  When the rod 1 is not urged to turn in one direction or the other, the pin 15 is located substantially in the middle of the recess whose width thus defines the angular displacement

  maximum of the rod relative to the elastic tutular element.

  Figure 4 illustrates the mode of operation of these stop means. It can be seen there that each pin 15 is initially well centered in its respective notch. The angular distance between the free end s of the pin 15 and each of the lateral edges of the notch corresponds to a maximum angle a of approximately 1.5. When the rod 1 rotates slowly, the pin does not come into contact with either of the edges of the notch, but if the rod is suddenly turned, the elastic tubular element 11 is slightly deformed by the effect o d inertia and the pin abuts against the corresponding flange of

notch 17.

  The method of assembling the shaft according to the invention is as follows.

  First the cage 10 with the balls 5 and the sleeve with holes 8 is forcibly mounted on the end of the rod 1 by placing the grooves 6 thereof opposite the grooves 9 of the cage 10 and then, l elastic tubular element 11 with the second sleeve around 14 is forcibly mounted on the cage so as to obtain an assembly ready to be fitted

  in the tubular part 3 of the piece forming a fork 2.

  In the case where the elastic tubular element 11 is devoid of its outer sleeve, the cage 10 with the balls 5 and the sleeve with holes 8 is force-fitted on the end of the rod 1 by placing the grooves 6 thereof. here next to the grooves 9 of the cage 10 and then this set is

  fitted into the elastic tubular element 11 to form the arDre.

  Finally, the pins 15 are placed in the holes 16 provided on the tubular part 3 of the piece forming a fork 2 so as to constitute stop means limiting the relative movement

  of the rod 1 relative to the piece forming a fork 2.

  This gives a fork shaft that is easy to assemble and particularly easy to mount in a steering column because the length of the shaft can be adjusted without tools thanks to the function

of this tree.

  Of course, the invention is not limited to the example illustrated and described, but can be applied to fork arbors of different uses o, with constant or intermittent rotation, in one or both directions of rotation , and of any size from the moment one wishes to obtain a damping and telescoping effect between

  the components of the tree.

Claims (11)

  1. Fork order consisting of a rod (1) constituting the shaft proper, and a fork-shaped part (2), the rod being mounted in an axial hole in a tutular part (3) of said part forming fork, said rod being connected in rotation to said piece forming a fork by means of a plurality of spherical elements (5) further allowing the telescoping of the rod (l) inside said piece forming a fork (2) during an axial stress on the latter, said spherical elements (5) being trapped between first longitudinal grooves (6) made on the periphery of the rod and second longitudinal grooves es (9) arranged opposite the first (6) carried out in a tubular cage (10) surrounding said rod (1), characterized in that, in combination, said cage (10) is connected to the tubular part (3) of the piece forming a fork (2) via of n elastic tubular element (11) with non-linear elastic behavior disposed around said cage (10) so as to dampen any vibration while allowing a slight relative angular displacement of said rod (1) relative to said fork-forming part, this displacement relative angular being limited by o angular stop members disposed between said cage (10) and the part   tubular part of the fork (2).   2. Fork shaft according to claim 1, characterized in that said elastic tubular element (11) is fixed to the inner face   of the tubular part (3) of the piece forming a fork (2).   3. Fork shaft according to claim 1, characterized in that said elastic tutular element (11) is fixed to the inner face of a sleeve (14) inserted by force into the tubular part (3) of the part forming a fork (2).   4. Fork shaft according to claim 3, characterized in that the inside diameter of said sleeve (14) is adapted to the outside diameter of said elastic tubular element (11) so as to put this last under prestress.   5. Fork shaft according to any one of claims   above, characterized in that said cage (10) is made of a material which is sufficiently deformable to absorb any radial clearance between said rod (1) and said cage (10).   6. Fork order according to any one of claims   above, characterized in that said elastic tubular element (11) is force-fitted onto said cage (10) and comprises on its inner face first means for locking in rotation (12) on said cage (10) cooperating with second locking means (13) in   rotation provided on the outer face of said cage (10).   7. Fork shaft according to claim 6, characterized by the fact that said first rotation locking means comprise longitudinal grooves (12) and that said second rotation locking means comprise ribs (13) on the external face of the cage (10). 8. Fork shaft according to claim 7, characterized in that said complementary ribs (13) on the outer face of the cage (10) correspond to said grooves (9) made on the face interior of said cage.   9. Fork shaft according to any one of claims   previous in which the rod (1), the tubular part (3) of the part o forming a fork (2) and said cage (10) are cylindrical, characterized in that said angular stop means comprise at least one pin s' extending radially in the tubular part (3) of the piece forming a fork (2) so as to protrude therein to be placed in a recess (17) provided at one end of said cage (10) and whose the width defines said relative displacement of the rod   (1) relative to the piece forming a fork (2).   10. Fork adjuster according to claim 9, characterized in that the said recess (17) has a width such that the maximum angular displacement corresponds to an angle of approximately l, 5   o in one direction of rotation or the other of the rod (1).   11. Fork adjuster according to claim 9 or 10, characterized in that several pins (15) are regularly distributed on the inner face of said tubular part (3) of said piece forming