FR2842488A1 - Steering column for motor vehicle has retrofit bearing mechanism mounted between two tooth elements and having eccentric on which first tooth element is mounted for rotation about first axis parallel to and spaced from eccentric axis - Google Patents

Abstract

The steering column (2) includes a steering shaft (7) that is connected to rotary movement of a steering wheel (3) by a transmission (9), having two tooth elements (20,22) engaged with each other. The steering column includes a retrofit bearing mechanism (34) between the two tooth elements. The bearing mechanism includes an eccentric (36) on which the first tooth element is rotatably mounted about a first rotation axis (A1), the eccentric being rotatable about an eccentric axis (AE) parallel to and spaced from the first axis. An independent claim is included for a steering assembly including the above steering column.

Description

The present invention relates to a steering column for a vehicle

  automobile, of the type comprising a steering shaft, a system for transmitting to the steering shaft a rotational movement of a steering wheel, the transmission system comprising at least two toothed members meshing with one other, the column further comprising a mechanism for adjusting the clearances between a first of the toothed members and a second of the

toothed organs.

  The invention applies in particular to a motor vehicle steering assembly comprising, mounted at the rear of the steering column, a steering wheel for rotating the steering shaft and a central cushion

  intended to remain fixed when the steering wheel turns.

  A steering column of the aforementioned type is known from document EP825 089. The transmission system comprises a toothed ring gear

with two gables.

  The crown is brought back radially against the pinions thanks to a play take-up mechanism which includes a rocker biased by a

  spring and fitted with a support roller on the crown.

  This radial retention mechanism does not make up for backlash

in a satisfying manner.

  Indeed, it would be advisable for that to eliminate the plays which a driver can feel when he turns the steering wheel, without the couple

  necessary to cause the steering wheel to rotate too high.

  Application FR-2 802 489 has provided a solution to this problem by also describing a steering column of the aforementioned type. The transmission system includes a pinion meshing with two toothed rings. The backlash mechanism uses ramp surfaces and a longitudinal spring. However, this backlash mechanism comprises many parts and therefore proves to be complex. In addition, the use of different ramp surfaces requires, in the mechanism itself, to maintain operating clearances so that all clearances between the

  toothed organs are not caught up.

  An object of the invention is to solve these problems by providing a steering column of the aforementioned type, the mechanism for catching up

  games be simpler and more effective.

  To this end, the subject of the invention is a steering column of the aforementioned type, characterized in that the clearance take-up mechanism comprises an eccentric on which the first toothed member is rotatably mounted around a first axis of rotation, l eccentric being rotatable about an eccentric axis

  substantially parallel to and spaced apart from the first axis of rotation.

  According to particular embodiments of the invention, the column may include one or more of the following characteristics, taken in isolation or in any technically possible combination: - the play catch mechanism includes elastic return means radial from the first toothed member to the second toothed member in a substantially radial direction; - The radial holding mechanism comprises elastic means for returning the first toothed member in a transverse direction substantially orthogonal to the radial direction; - The elastic lateral return means have a greater stiffness than the elastic radial return means; - The elastic lateral return means and the elastic radial return means consist of the same ring; - A bore is formed in the eccentric and the first toothed member is rotatably mounted in the bore around the first axis of rotation; - The first toothed member is mounted in the bore of the eccentric by means of the ring; the first toothed member comprises a pinion or an internally toothed sleeve and the second toothed member respectively comprises an internally toothed sleeve or a pinion and - the column comprises a fixed block for mounting a central cushion

  to keep it fixed in rotation when the steering wheel turns.

  The invention further relates to a steering assembly comprising a steering column and a steering wheel mounted on the steering column, characterized in that the steering column is a steering column as defined above, the transmission system

is connected to the steering wheel.

  Alternatively, the steering assembly includes a central cushion mounted on a fixed block of the steering column to be rotationally fixed when the steering wheel turns. The invention also relates to a motor vehicle, characterized

  in that it comprises a steering assembly as defined above.

  The invention will be better understood on reading the description which will

  follow, given only by way of example, and made with reference to the accompanying drawings, in which: - Figure 1 is a schematic view in longitudinal section, along a plane orthogonal to a vertical plane, of a steering assembly according the invention, - Figure 2 is a schematic exploded perspective view of the play-up mechanism of the steering column of the assembly of Figure 1, - Figure 3A is a schematic sectional view taken along line 111 -111 of Figure 1, - Figure 3B is a schematic, reduced and end view illustrating the relative position of the toothed members of the transmission system of the steering column, - Figures 4A and 4B are views similar to Figures 3A and 3B and illustrating a first step in adjusting the play take-up mechanism, and - FIGS. 5A and 5B are views similar to FIGS. 3A and 3B and

  illustrating a second step of adjusting the backlash mechanism.

  In all that follows, the orientations used are the usual orientations of a motor vehicle. Thus, the terms "front", "rear", "up" and "down" are understood in relation to the position of the driver and the

  direction of travel of the motor vehicle.

  FIG. 1 schematically illustrates a steering assembly 1 of a motor vehicle which essentially comprises a steering column 2, a steering wheel 3 mounted at the rear of the steering column 2 and a fixed central cushion 4 disposed substantially in the center of the steering wheel 3. The steering wheel 3 and the cushion 4 have

  have been shown in phantom and very schematically in FIG. 1.

  The steering column 2 essentially comprises: - a body 6 carried by the structure of the motor vehicle, - a steering shaft 7 rotatable around its longitudinal axis XX and the front end 8 of which is provided, for example, with a fork gimbal to be connected to the rest of the steering mechanism of the motor vehicle, and - a transmission system 9 to the steering shaft 7 of a

steering wheel rotation 3.

  The steering wheel 3 conventionally comprises a peripheral rim 11 and branches 12 which extend from the rim 11 radially

  towards the rear end of column 2.

  The steering wheel 3 is mounted at the rear end of the steering column 2 by means of a steering wheel carrier hub 14. The hub 14 is rotatably mounted

  on the rear end of the body 6 by means of a bearing 16.

  The hub 14 surrounds an inner fixed block 18 which is integral, for example

by coming of matter, of the body 6.

  The fixed block 18 extends towards the rear and the fixed central cushion 4 is mounted at the rear end of the block 18 to allow it to remain fixed when the

steering wheel 3 turns.

  Conventionally, the central cushion 4 includes one or more accessories, including an airbag, a horn control switch and other control devices

  different vehicle equipment.

  The transmission system 9 comprises a first front toothed member 20, in the form of a pinion, and a second rear toothed member 22, under

  shape of an internally toothed sleeve.

  The pinion 20 is extended by a front tail 23 which extends along

  of its central axis AI merged with the axis X-X.

  The toothed sleeve 22 has for example come integrally with the hub 14 and can pivot like it, thanks to the bearing 16, about a central axis A2

confused with that of the steering wheel 3.

  The pinion 20 is mounted by fitting its tail 23 into the rear end 24 of a tube 25. Splines not shown and provided on the tail 23 and in the rear end 24 in rotation secure the pinion 20 and the tube 25. A pin, not shown, secures in translation the tube 25 and the pinion 20. As a variant, the pinion 20 may have come integrally with the tube 25. The front end 26 of the tube 25 receives the rear end of the steering shaft 7. Unrepresented splines provided in the front end 26 of the tube 25 and on the rear end of the steering shaft 7

rotation the shaft 7 and the tube 25.

  Thus, the pinion 20 and the steering shaft 7 are integral in rotation

around the axis AI.

  An anti-theft sleeve 28 surrounds the rear end 24 of the tube 25.

  As illustrated in FIG. 3B, the pinion 20 and the toothed sleeve 22 mesh with each other to transmit a rotational movement of the flywheel 3, and therefore of the hub 14, to the tube 25 and therefore to the steering shaft 7. This meshing occurs outside the plane of Figure 1 which is orthogonal to the vertical plane. More specifically, this meshing takes place above the plane of

  FIG. 1, in the upper regions of the pinion 20 and the toothed sleeve 22.

  To ensure a take-up of the clearances between the pinion 20 and the toothed sleeve 22, the steering column 22 comprises a catch-up mechanism 34

games.

  As illustrated in FIGS. 1 to 3A, this mechanism 34 includes a

  eccentric 36 in the form of a part received in the body 6 and itself receiving the tube 25 for connecting the pinion 20 to the steering shaft 7.

  More specifically, the eccentric 36 is received in a bore

  circular 38 with axis AE offset from the axis of rotation AI of pinion 20.

  The eccentric 36 is received in the bore 38 in order to be able to rotate around this axis AE, for example under the action of a torque applied to the front end 40 of the eccentric 36 which has three notches

  drive 42 angularly spaced from each other.

  As seen in Figure 3B, the AE axis is slightly spaced

  laterally to the left and significantly spaced down the A2 axis.

  The eccentric 36 is hollow and internally has a stepped cylindrical bore 43 of axis AI. The tube 25, and therefore the steering shaft 7 are rotatably mounted inside this stepped bore 43 by virtue of a front bearing 44, disposed between the front end 26 of the tube 25 and the front end of the eccentric 36, and a rear bearing 44 disposed between the rear end 24

  of the tube 25 and the rear end 46 of the eccentric 36.

  An elastic ring 48 is interposed between the rear end 46 of

  the eccentric 36 and the rear bearing 44.

  As illustrated more specifically by FIG. 3, this ring 48 is formed of a bent and curved metal blade whose ends 49 are

  substantially join in the upper region of bore 43.

  The ring 48 has, projecting inwards, two lateral reliefs arranged at the ends of a horizontal diameter passing through the axis AI, a lower relief 52, and an upper relief 54 formed by the free ends 49. The lower reliefs 52 and higher 54 have different shapes from that of the lateral reliefs 50 so that the elastic ring 48 has a lesser stiffness in a substantially vertical radial direction and a more rigid

  important in a substantially horizontal lateral direction.

  This difference in stiffness is obtained by a range

  lower circumference of the reliefs 50 compared to the reliefs 52 and 54.

  To arrive at the position illustrated by FIGS. 3A and 3B, one can

  go successively through the steps illustrated in FIGS. 4A, 4B, 5A and 5B.

  It will be noted that during these stages the axes AE and A2 remain fixed. Moreover,

  the displacements of the axis AI have been exaggerated in FIGS. 3B, 4B and 5B.

  In FIGS. 4A and 4B, the eccentric 36 is in position such that the axis AI is arranged in the same vertical radial plane R of the pinion 20 as the axis AE, under the axis AE. The axis A2 is placed under the axis AI and offset laterally from the plane

R to the left.

  The axis AI is thus in an extreme lower position as is the pinion 20. The teeth of the pinion 20 and of the sleeve 22 then mesh with a

  significant clearance, as shown in Figure 4B.

  The eccentric 36 occupies a position which can be deduced from that of FIG. 3A by a rotation, for example of 450, in the counterclockwise direction. The

ring 48 is then at rest.

  Then, the eccentric 36 is made to rotate about 550 in a clockwise direction, for example using a tool whose projections come into engagement

  the notches 42 of the front end 40 of the eccentric 36.

  At the end of this step, and as illustrated by FIGS. 5A and 5B, the axis AI of the pinion 20 approaches vertically the axis AE which is fixed. The

  axes AE and A2 are then out of the plane R passing through the axis AI.

  The teeth of the pinion 20 and of the sleeve 22 are then firmly in abutment against each other along the radial direction contained in the plane R. By reaction, the pinion 20, by means of the rear bearing 44 is supported on the lower relief 52 of the elastic ring 48 by crushing it

  completely at the bottom of the bore 43 of the eccentric 36.

  In this position, it can be seen that the clearances between the pinion 20 and the sleeve 22 are harmful, but that a very large torque must be exerted to

  ability to rotate steering shaft 7 from flywheel 3.

  Then, the eccentric 36 is pivoted in the opposite direction, that is to say in the counterclockwise direction in FIGS. 5A and 5B, in order to lower the pinion relative to the sleeve 22, while controlling the necessary torque for

  ability to rotate rotation shaft 7 from flywheel 3.

  As soon as a satisfactory value of torque has been reached, for example a torque of 160 Nm, the rotation of the eccentric 36 is stopped and it is locked in position for example by means of a non-represented pressure screw which

crosses the body.

  The eccentric 36 is then in the position of FIGS. 3A and 3B. The axis A2 is then substantially contained in the plane R. The lower relief 52 of the elastic ring 48 is then slightly deformed downwards by the pinion 20, via the rear bearing 44. Thus, the ring 48 exerts a vertical radial force for holding the pinion 20 against the toothed sleeve 22. The radial clearances are therefore satisfactorily caught up in the transmission system 9, without this resulting in a significant torque for driving the steering shaft 7 in rotation. Furthermore, it has been found that the lateral reliefs 50 of the elastic ring 48 exert a transverse elastic return, in a plane T of the pinion 20 orthogonal to the plane R and passing through the axis AI, on the pinion 20. This elastic return makes it possible to limit the lateral displacements of the pinion 20 which

  could cause clicks.

  Catching up on games and driving pleasure of the vehicle

automobile are therefore increased.

  The lateral take-up of the games, although present in the preferred embodiments, may however be absent from certain embodiments. In addition, the elastic ring 48 can be produced in a different way from that described so far. It may thus be, for example, a rubber ring provided, if necessary, with metal inserts making it possible to

  give it different stiffness in different directions.

  Similarly, the above principles can be applied to transmission systems 9 of the steering column 2 o organs other than a pinion and a crown 22 mesh with each other. Thus, they can be applied to systems comprising two pinions meshing with the same

  crown, a central pinion meshing with two crowns ...

  Similarly, the holding force can be applied to one

  any of the toothed parts of the transmission system 9.

Claims (12)

  1. Steering column (2) for a motor vehicle, of the type comprising a steering shaft (7), a system (9) for transmitting to the steering shaft a rotational movement of a steering wheel (3 ), the transmission system comprising at least two toothed members (20, 22) meshing with each other, the column further comprising a mechanism (34) for adjusting the play between a first (20) of the toothed members and a second (22) of the toothed members, characterized in that the clearance take-up mechanism comprises an eccentric (36) on which the first toothed member (20) is rotatably mounted around a first axis of rotation (AI), l 'eccentric (36) being rotatable about an eccentric axis (AE) substantially parallel to the first axis of rotation and spaced from it.   2. Column according to claim 1, characterized in that the play take-up mechanism (34) comprises elastic means (48) for radial return from the first toothed member (20) to the second toothed member (22)   in a substantially radial direction (R).   3. Column according to claim 2, characterized in that the radial holding mechanism (34) comprises elastic means (48) for returning the first toothed member in a transverse direction (T)   substantially orthogonal to the radial direction.   4. Column according to claim 3, characterized in that the elastic lateral return means have a greater stiffness than the   elastic radial return means.   5. Column according to claim 4, characterized in that the elastic lateral return means and the elastic radial return means   consist of the same ring (48).   6. Column according to one of the preceding claims, characterized   in that a bore (43) is formed in the eccentric (36) and in that the first toothed member (20) is rotatably mounted in the bore (43) around the first axis of rotation (AI).   7. Column according to claims 5 and 6 taken together,   characterized in that the first toothed member (20) is mounted in the bore   (43) of the eccentric (36) via the ring (48).   8. Column according to any one of the preceding claims,   characterized in that the first toothed member comprises a pinion (20) or an internally toothed sleeve and the second toothed member comprises   respectively an internally toothed sleeve (22) or a pinion.   9. Column according to one of the preceding claims, characterized   in that it comprises a fixed block (18) for mounting a central cushion (4)   to keep it fixed in rotation when the steering wheel (3) turns.   10. Steering assembly (1) of the type comprising a steering column (2) and a steering wheel (3) mounted on the steering column, characterized in that the steering column is a steering column according to   any one of the preceding claims, the system of which   transmission (9) is connected to the steering wheel (3).   11. An assembly according to claim 10, characterized in that it comprises a central cushion (4) mounted on a fixed block (18) of the column of   steering to be fixed in rotation when the steering wheel (3) turns.   12. Motor vehicle characterized in that it comprises a   steering assembly according to claims 10 or 11.