GB2288654A

GB2288654A - Tilt steering apparatus

Info

Publication number: GB2288654A
Application number: GB9505936A
Authority: GB
Inventors: Hidenori Katayama; Kenji Kuroda
Original assignee: Daihatsu Motor Co Ltd
Current assignee: Daihatsu Motor Co Ltd
Priority date: 1994-04-19
Filing date: 1995-03-23
Publication date: 1995-10-25
Anticipated expiration: 2015-03-23
Also published as: GB9505936D0; JPH07285445A; JP3244591B2; DE19512809C2; DE19512809A1; GB2288654B

Description

It 1

TITLE OF THE INVENTION

Tilt Steering Apparatus 2288654 BACKGROUND OF THE INVENTION Field of the Invention

The present invention relates to a tilt steering apparatus having a column tube which is mounted on a car body to be vertically tiltable around a bracket supporting its forward end portion. Description of the Background Art

In general, there is proposed a tilt steering apparatus having an elastic rubber member which Is mounted on a car body by means of a retainer and a plate for supporting a front end portion of a column tube (Japanese Utility Model Laying-Open Gazette No. 64-36283 (1989)).

In this case, the inner surface of the rubber member which ':L,s in contact with outer peripheral surface of the column tube is provided in the form of a trapezoidal projection for allowing tilting of the column tube.

In the aforementioned apparatus, however, it is necessary to hold the rubber member by the retainer and the plate under pressure, in order to bring the same into close contact with the column tube. Thus, this apparatus is complicated in structure, and requires complicated steps for assembling these 1 1 2 components.

In another conventional apparatus, a forward end portion of a column tube is swingably mounted on a bracket fixed to a car body through a spherical bush (Japanese Patent Publication No. 2-25833 (1990)). In this case, however, the structure of the apparatus is complicated and the cost thereof is increased. Further, the column tube tends to be affected by the vibration of the car body.

SUMMARY OF THE INVENTION

Accordingly, an object of the present invention is to provide a tilt steering apparatus which has a simple structure and requires simple assembling steps.

Another object of the present invention is to provide atilt steering apparatus which can suppress the rattling of a is column tube affected by the vibration of the car body.

Still another object of the present invention is to provide a tilt steering apparatus which can be effective as an energy absorbing steering upon secondary collision.

A tilt steering apparatus of the present invention comprises a column tube which is mounted on a car body to be vertically tiltable around a bracket supporting a front end portion of the column tube. The bracket is provided with a 3 through hole which can be passed through by the column tube with an annular clearance. Also, the apparatus of the present invention comprises a collar having a radial flexibility for allowing vertical tilting of the column tube. The collar is press-fitted in the annular clearance between the through hole and the column tube.

The column tube is elastically supported inside of the through hole of the bracket due to the radial flexibility of the collar, whereby it is possible to sufficiently absorb rattling of the column tube by the elasticity of the collar, as well as to readily allow tilting of the column tube. Further, since the front end portion of the column tube is elastically supported by means of the collar alone, the number of components is reduced and the structure can be simplified to provide the steering apparatus at a low cost.

When the through hole is a circular hole, and the column tube has a cylindrical outer surface whose diameter is smaller than that of the through hole, the collar may preferably comprise a substantially annular portion which has a non-circular section and a radial thickness of the annular portion may preferably be smaller than width of the annular clearance. In this way, the collar may have a sufficient bending flexibility in a radial direction.

When the collar comprises the annular portion having a 4 non-circular section, a diameter of an inscribed circle of the annular portion in a free state may preferably be smaller than the diameter of the column tube. In this case, the collar is slightly expanded when the same is engaged with the outer periphery of the column tube, thereby the collar comes into pressure contact with the column tube.

In order to support the column tube at a center of the through hole, the collar may preferably be in pressure contact with an inner surface of the through hole and an outer surface of the column tube at a plurality of points with substantially uniform intervals in a circumferential direction of the collar.

In order to locate the collar in the bracket in an axial direction, the collar may preferably comprise a first location is means fitted with a front side of the bracket and a second location means fitted with a rear side of the bracket.

Especially, the second location means may preferably comprise a plurality of latches which are readily breakable in order to absorb impact energy upon secondary collision.

In order to mount the collar on the column tube, it is preferable that the column tube comprises holes and the collar comprises projections which project inwardly and which engage with the holes of the column tube. Especially, the holes may preferably be formed at both sides of the column tube so that the column tube is vertically tiltable around the projections.

When the collar is made of resin, the latches, the elastic pawls and the projections can be formed integrally with the annular portion.

The foregoing and other objects, features, aspects and advantages of the present invention will become more apparent from the following detailed description of the present invention when taken in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

Fig. 1 is a side elevational view showing an embodiment of a tilt steering apparatus according to the present invention; Fig. 2 is an enlarged side elevational view showing a rear supporting mechanism for the column tube; Fig. 3 is an exploded perspective view showing the rear supporting mechanism for the column tube; Fig. 4 is an exploded perspective view showing a front supporting mechanism for the column tube; Fig. 5 is a perspective view showing a first embodiment of a collar according to the present invention; Fig. 6 is an enlarged sectional view taken along the line A - A in Fig. 1; Fig. 7 is an enlarged sectional view taken along the line 6 B - B in Fig. 6; Fig. 8 is an enlarged sectional view taken along the line C - C in Fig. 6; Fig. 9 is a cross sectional view showing a second embodiment of the collar according to the present invention; Fig. 10 is a longitudinal sectional view showing a third embodiment of the collar according to the present invention; and Fig. 11 is a longitudinal sectional View showing a fourth embodiment of the collar according to the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Figs. 1 - 8 show an embodiment of a tilt steering apparatus according to the present invention.

Referring to Fig. 1, a steering wheel 2 is fixed to a rear end portion of a steering shaft 1, whose front end portion is coupled to a steering mechanism (not shown) through a universal joint 3. The steering shaft 1 is rotatably supported in a cylindrical column tube 4 through bearings 5. A rear portion of the column tube 4 is supported by a rear bracket 6 to be axially movable with respect to a pedal bracket 7 which is fixed to a car body D, and to be swingable in a vertical direction. A front portion of the column tube 4 is supported by a front bracket 20 to be tiltable at a 7 prescribed angle.

As shown in Figs. 2 and 3, the rear bracket 6 comprises first and second brackets 8 and 9, which are fixed to each other by welding. The first bracket 8 is formed to have a hat-shaped section, and provided with flanges 8a on each end thereof for being attached to the pedal bracket 7. Each of the flanges 8a is provided with a notch 8b opening rearwardly for receiving a bolt 10. The bolt 10 received in this notch 8b is screwed to the pedal bracket 7 for attaching the first bracket 8 thereto. Since the notch 8b is opening rearwardly, the first bracket 8 can be forwardly displaced from the pedal bracket 7 upon secondary collision.

The second bracket 9 is formed to have an inverted U-shaped section, for holding the column tube 4. A hook 11 serving as a shock absorbing member is fixed to the upper surface of the second bracket 9 by welding or the like. The hook 11 is made of a band metal whose lower portion llb is formed in a U-shape opening rearwardly, and whose upper portion lla is formed in a V-shape opening forwardly. The upper portion lla of the hook 11 is engageable with the rear end portion 7a of the pedal bracket 7. Further, the lower portion llb of the hook 11, covered with the first bracket 8, is plastically deformable for absorbing impact energy upon secondary collision as shown by two-dot chain lines in Fig. 2.

1 1 8 The second bracket 9 is provided with a pair of slots 9a which are vertically formed at lower portions thereof. Also, a tilt angle control lever 13 is vertically swingably attached by means of a bolt 12 which is inserted through the slots 9a. Further, a third bracket 14 having a Ushaped section and having a pair of through holes 14a at both sides thereof is fixed to a lower portion of the column tube 4 by welding or the like. The bolt 12 is inserted into the through holes 14a as well as into the slots 9a. When the lever 13 is downwardly swung, tightening force of the bolt 12 is so reduced that it is possible to vertically swing the column tube 4 by the length of the slots 9a. When the column tube 4 reaches a desired tilt angle position, the lever is upwardly swung. The bolt 12 is tightened so that the column tube 4 can be fixed in this desired position.

As shown in Figs. 4 - 8, the front bracket 20 is provided on both ends thereof with flanges 21 to be fixed to the pedal bracket 7 by means of bolts 23 (see Fig. 1). The bracket 20 is also provided on its central portion with a through hole 22a and a cylindrical portion 22 which surrounds the through hole 22a. The through hole 22a is passed through by the front end portion of the column tube 4 with a radial clearance.

A collar 30 made of elastic resin such as polyacetal 9 resin is press-fitted in the clearance between the through hole 22a and the column tube 4. As shown in Figs. 4 and 5, the collar 30 comprises an annular portion 30a which is substantially formed in a shape of polygonal cylinder having a radial flexibility. The annular portion 30a is provided with a split 31 in an axial direction thereof for increasing the radial flexibility of the collar 30. Four readily breakable latches 32 extending radially are formed on a rear edge of the collar 30 to be in contact with a rear side of the bracket 20.

Also, a pair of legs 33 extending rearwardly are also formed on a rear edge of the collar 30, and projections 34 which engage with holes 4a (see Fig. 4) of the column tube 4 are formed on inner sides of the legs 33. On the other hand, a pair of elastic pawls 35 are formed on a front edge of the collar 30, to engage with a front edge of the cylindrical portion 22. Therefore, the collar 30 can be correctly located to the bracket 20 in the axial direction by means of the latches 32 and the pawls 35.

The diameter of an inscribed circle of the collar 30 in a free state is smaller than the outer diameter of the column tube 4 so that the collar 30 is slightly expanded when the same is engaged with the outer periphery of the column tube 4. The projections 34 of the collar 30 are engaged with the holes 4a provided at both sides of the column tube 4, for axially positioning the collar 30 with respect to the column tube 4. When the collar 30 is engaged with the outer periphery of the column tube 4, the diameter of a circumscribed circle of the collar 30 is slightly larger than the inner diameter of the cylindrical portion 22 of the bracket 20. When the column tube 4 having the collar 30 is inserted into the cylindrical portion 22 from the rear, the latches 32 are brought into contact with the rear side of the bracket 20 while the pawls 35 are fitted with the front edge thereof as shown in Fig. 8, whereby the collar 30 are axially fixed to the cylindrical portion 22 of the bracket 20.

The collar 30 is in pressure contact with the inner surface of the through hole 22a at four points and with the outer surface of the column tube 4 at other four points, as shown in Fig. 6. These points of contact are positioned with substantially uniform intervals in a circumferential direction of the collar 30 so that the column tube 4 is supported at a center of the through hole 22a. The collar 30 can be radially deflected due to clearances 6 1 between the collar 30 and the cylindrical portion 22 and 2 between the collar 30 and the column tube 4. Therefore the column tube 4 is vertically tilted by elastic deflection of the collar 30.

A tilt operation of the steering apparatus having the 11 aforementioned structure is now described.

First, the tilt angle control lever 13 is downwardly swung in order to reduce the tightening force of the bolt 12. Thus, the column tube 4 is vertically tiltable about the front bracket 20. Referring to Fig. 2, uppermost and lowermost positions of the steering shaft 1 are shown by solid lines and two-dot chain lines respectively. At this time, since the projections 34 of the collar 30 are pivotally engaged with the holes 4a of the column tube 4 and the collar 30 has a radial flexibility, the column tube 4 can be easily tilted with respect to the collar 30 and the bracket 20 about the projections 34. When the column tube 4 reaches a desired position, the lever 13 is swung upwardly to tighten the bolt 12 for fixing the column tube 4 to the rear bracket 6. At this time, the front end portion of the column tube 4 is elastically supported by the bracket 20 through the collar 30, whereby no rattling is caused.

An energy absorbing operation the steering apparatus upon secondary collision is now described.

When a vehicle having this steering apparatus comes into collision, the driver may secondarily collide with the steering wheel 2. At this time, the rear bracket 6 as well as the steering shaft 1 and the column tube 4 are forwardly moved 12 by the impact force. Thus, the hanging portion lla of the hook 11 fixed to the rear bracket 6 are engaged with the rear end portion 7a of the pedal bracket 7 fixed to the car body D, whereby the hook 11 is rearwardly pulled by the pedal bracket 7. Thus, the U-shaped portion llb of the hook 11 is plastically-deformed to absorb the impact energy.

When the column tube 4 is forwardly moved by the secondary collision, further, the collar 30 fitted on the front end portion of the tube 4 is also forwardly moved with respect to the front bracket 20 fixed to the car body D. Thus, the latches 32 which are in contact with the rear surface of the bracket 20 are broken to absorb the impact energy. It is possible to control the energy to be absorbed by presetting the breaking strength of the latches 32.

Thus, it is possible to effectively absorb the impact energy upon the secondary collision by means of the shock absorbing means (hook 11 and latches 32) provided in the front and rear end portions of the column tube 4, thereby reducing the impact to be applied to the driver.

The present invention is not restricted to the aforementioned embodiment, but various modifications are available, as a matter of course.

Though the above embodiment has been described with 13 reference to an energy absorbing steering apparatus, the present invention is also applicable to a simple tilt steering apparatus having no energy absorbing mechanism.

Although the collar is formed substantially in the shape of a polygonal cylinder in the aforementioned embodiment, a collar 40 may be formed in a shape of a petal as shown in Fig. 9. A collar 41 may also be formed in a shape of a Venturi tube as shown in Fig. 10. Further, it is also possible to provide a plurality of inwardly inclined leaf springs 43 on a collar 42 as shown in Fig. 11 for supporting the column tube 4 elastically.

The cylindrical portion 22 provided on the front bracket 20 is not restricted to the circular shape as described above, but may have any shape so far as the same can hold the column tube 4 through the collar.

The collar according to the present invention, which may have a radial elasticity, can be made of a metal in place of the resin.

While the steering shaft and the column tube are illustrated as single components respectively in the aforementioned embodiment, these shaft and tube may be replaced by well-known telescopic members in order to obtain axial expansibility.

Although the present invention has been described and 14 illustrated in detail, it is clearly understood that the same is by way of illustration and example only and is not to be taken by way of limitation, the spirit and scope of the present invention being limited only by the terms of the appended claims.

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Claims

WHAT IS CLAIMED IS:

1. A tilt steering apparatus having a column tube (4) mounted on a car body to be vertically tiltable around a bracket (20) supporting a front end portion of said column tube (4), said apparatus comprising:

a through hole (22a) provided on said bracket (20) to be passed through by said front end portion of said column tube (4) with an annular clearance; and a collar (30) press-fitted in said annular clearance between said through hole (22a) and said column tube (4), said collar (30) having a radial flexibility for allowing vertical tilting of said column tube (4).

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2. A tilt steering apparatus in accordance with claim 1, wherein said through hole (22a) is a circular hole, said column tube (4) has a cylindrical outer surface whose diameter is smaller than that of said through hole (22a), said collar (30) comprises a substantially annular portion (30a) which has a non-circular section, and wherein a radial thickness of said annular portion (30a) is smaller than width of said annular clearance so that said annular portion has a bending flexibility in a radial 16 direction.

3. A tilt steering apparatus in accordance with claim 2, wherein a diameter of an inscribed circle of said collar (30) in a free state is smaller than said diameter of said column tube (4) so that said collar (30) is slightly expanded when the same is engaged with said outer periphery of said column tube (4).

4. A tilt steering apparatus in accordance with any preceding claim, wherein said bracket (20) is provided with a cylindrical portion (22) surrounding said through hole (22a).

5. A tilt steering apparatus in accordance with any preceding claim, wherein said collar (30) is in pressure contact with an inner surface of said through hole (22a) and an outer surface of said column tube (4) at a plurality of points with substantially uniform intervals in a circumferential direction of said collar (30) so that said column tube is supported at a center of said through hole.

17

6. A tilt steering apparatus in accordance with claim 2, wherein said annular portion (30a) of said collar (30) is substantially formed in a shape of polygonal cylinder.

7. A tilt steering apparatus in accordance with any preceding claim, wherein a split (31) is formed in said collar (30) for increasing said radial flexibility.

8. A tilt steering apparatus in accordance with any preceding claim, wherein said collar (30) comprises a first location means fitted with a front side of said bracket (20) and a second location means fitted with a rear side of said bracket (20) for locating itself in said bracket (20) in an axial direction thereof.

9. A tilt steering apparatus in accordance with claim 8, wherein said first location means comprises a plurality of elast! pawls (35) formed in a front end of said collar (30).

10. A tilt steering apparatus in accordance with claim 8 18 or 9, wherein said second location means comprises a plurality of latches (32) which are readily breakable upon secondary collision and which are formed in a rear end of said collar (30).

11. A tilt steering apparatus in accordance with any preceding claim, wherein said column tube (4) is provided with holes (4a), and wherein said collar (30) is provided with projections (34) which project inwardly and which engage with said holes (4a) of said column tube (4).

12. A tilt steering apparatus in accordance with claims 11, wherein said holes (4a) are formed at both sides of said column tube (4), and wherein said projections (34) engage with said holes so that said column tube (4) is vertically tiltable around said projections (34).

13. A tilt steering apparatus in accordance with any preceding claim, wherein 19 said collar (30) is made of resin.

14. A tilt steering apparatus in accordance with any preceding claim, wherein said apparatus further comprising a rear bracket for supporting a rear end portion of said column tube (4) to be adjustable in a vertical direction, and a shock absorbing member provided in said rear bracket for absorbing impact energy to said column tube (4) in a forward direction caused by secondary collision.

15. A tilt steering apparatus substantially as herein described with reference to the accompanying drawings.