The present invention is related to a tilt-type steering apparatus having a steering column which rotatably supports a steering shaft to which a steering shaft is attached, and a tilt bracket which tiltably supports the steering column.
Conventionally, there has been known an electric position adjusting type steering column apparatus as an example of tilt-type steering apparatuses, in which a rectangular supporting portion is formed around a steering column, abutting plates (slide plates) are interposed between the supporting portion and opposing flat plate portions of a vehicle body side bracket, and a plurality of fastening screws are fastened to press the abutting plates from right and left against the rectangular supporting portion of the steering column, thereby providing sliding resistance between the supporting portion and the opposing flat plate portions of the steering vehicle body side bracket. The sliding resistance is set to be greater than an external input from a steering wheel (a steering force from a driver) but smaller than tilt driving force. Patent Document 1: JP 2005-199760 A (page 1, FIG. 3)
However, in the conventional example disclosed in Patent Document 1 in which the sliding resistance is provided between the rectangular supporting portion of the steering column and the opposing flat plate portions of the vehicle body side bracket sandwiching the rectangular supporting portion of the steering column, if there is an misalignment in a parallelism between the steering column and the opposing flat plate portions of the vehicle body side bracket, assembling is carried out such that the steering column is dented due to a partial contact against the opposing flat plate portions of the vehicle body side bracket (not a uniform contact of the entire contact surface by a local contact). When adjusting a position of the steering column under such a condition that the steering column is partially contacting against the opposing flat plate portions of the vehicle body side bracket, there have been some unsolved problems such as an occurrence of abnormal noise and an increase of a drive current of an electric actuator, resulting from scratching on the sliding surface and running out of lubricant oil on the sliding surface.
In order to solve such unsolved problems, a method for improving a dimensional accuracy of the vehicle body side bracket and the vehicle body to improve the parallelism between the steering column and the opposing flat plate portions of the vehicle body side bracket may be conceived. In such a case, however, it is necessary to improve dimensional accuracy of each of the components, which would then result in another problem of increase of manufacturing cost.
The present invention has been made in view of the unsolved problems of the conventional example described above, and it is an object thereof to provide a tilt-type steering apparatus in which a damage of a sliding surface and an occurrence of an abnormal noise upon position adjustment can be prevented even under the condition of partial contact between a steering column and a vehicle body side bracket, without need of improving dimensional accuracy of each of the components.
In order to achieve the object described above, a tilt-type steering apparatus according to a first aspect of the present invention includes a steering column swingably supported by a tilt pivot shaft and rotatably supporting a steering shaft to which a steering wheel is attached; and a tilt bracket fixed to a vehicle body member and tiltably holding the steering column,
wherein a stress cushioning member is disposed between the steering column and the tilt bracket.
According to the tilt-type steering apparatus of a second aspect, in the first aspect of the invention, the stress cushioning member is made of a synthetic resin.
Further, according to the tilt-type steering apparatus of a third aspect, in the first aspect of the invention, the stress cushioning member is fixed on either one of the steering column and the tilt bracket.
Further, according to the tilt-type steering apparatus of a fourth aspect, in the first aspect of the invention, a fitting recess is formed on either one of the steering column and the tilt bracket; and the stress cushioning member is fixedly fitted into the fitting recess.
Still further, according to the tilt-type steering apparatus of a fifth aspect, in the first aspect of the invention, a fitting recess is formed on either one of the steering column and the tilt bracket; and a fitting protrusion formed on the stress cushioning member is fitted into the fitting recess.
Still further, according to the tilt-type steering apparatus of a sixth aspect, in the first aspect of the invention, a fitting protrusion is formed on either one of the steering column and the tilt bracket, and a fitting recess formed on the stress cushioning member is fitted into the fitting protrusion.
Still further, according to the tilt-type steering apparatus of a seventh aspect, in the first aspect of the invention, the tilt-type steering apparatus further includes an electric actuator which tilts the steering column with respect to the tilt bracket.
According to the present invention, the stress cushioning member is disposed between the steering column and the tilt bracket. Therefore, even if the dimension accuracy as to the steering column, the tilt bracket, and the vehicle body member is low so that a partial contact is created between the steering column and the stress cushioning member or between the stress cushioning member and the tilt bracket, the stress cushioning member conforms to a sliding surface contacting thereto over time so that an area of the sliding surface increase, whereby surface pressure on the sliding surface is reduced. The reduction of the surface pressure on the sliding surface is advantageous in that damages and running out of lubricating oil of the sliding surface can be prevented, and also, abnormal noise generation and an increase of drive current in a case where a electric actuator is provided can be prevented. Moreover, it is also advantageous in that the manufacturing cost can be reduced because it is not required to improve the dimensional accuracy of respective components.
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
In
When a driver steers the steering wheel 13, a rotation force thereof is transmitted to the steering gear 17 via the steering shaft 11, the universal joint 14, the intermediate shaft 15 and the universal joint 16, and a rotational movement is converted into a linear movement along a vehicle width direction through the rack-and-pinion mechanism, whereby the steered wheel 19 is turned via the tie rod 18.
Peripheral components P is arranged on a rear portion of the steering column 12. The peripheral components P includes such as a control switch and a combination switch for driving an electric tilting mechanism 30 and an electric telescopic mechanism 50 which will be described later, and a column cover.
As shown in
The steering column 12 includes an outer column 12a, and an inner column 12b which is slidably held by the outer column 12a. The steering shaft 11 is rotatably supported by rolling bearings (not shown) which are arranged on inner circumferential surfaces of front and rear end portions of the inner column 12b respectively.
As shown in
As shown in
The outer column 12a is inserted through a guide space 24f which is surrounded by the attaching plate portion 24b, the guide plate portions 24c, 24d, and the bottom plate portion 24e of the tilt bracket 24.
As shown in
The stress cushioning members 25a, 25b are formed of synthetic resin having high abrasion resistance, such as POM (polyacetal) resin, PA (polyamide) resin, PEEK (polyetheretherketone) resin, PPS (polyphenylene sulfide) resin, PAI (polyamide-imide) resin, PTFE (4-ethylene fluoride) or the like. The stress cushioning members 25a, 25b are fixed on the projected portions 12c, 12d by adhesive bonding, welding or the like. In order to further improve slidability (durability) of the stress cushioning members 25a, 25b, for example, oil impregnated resin such as oil impregnated POM resin may be used.
One of the stress cushioning members 25a is slidably contacted to a clearance filling plate 24g which is arranged on an inner side surface of the guide plate portion 24c of the tilt bracket 24 to prevent a play of the steering column 12, while the other of stress cushioning members 25b is slidably contacted to an inner side surface of the guide plate portion 24d of the tilt bracket 24.
As shown in
The steering column 12 is held by the electric tilting mechanism 30, which is arranged on a vehicle-front side (the left side in
A worm wheel 36 is attached to the screw shaft 35 at a position near the rolling bearing 33 inside the gear housing 31, and a worm 37 is meshed with the worm wheel 36. As shown in
A cylindrical covering member 41 is arranged on an inner side of a through hole 31a, through which the screw shaft 35 is inserted, of the gear housing 31 to cover the screw shaft 35, and a damper 42 is arranged on a tip portion of the cylindrical covering member 41. The damper 42 is made of synthetic resin having high elasticity such as polyurethane, and is slidably contacted to an outer circumferential surface of the screw shaft 35. Similarly, another damper 43 is arranged on a lower end face of the rolling bearing 34, and is slidably contacted to the outer circumferential surface of the screw shaft 35.
A nut 45 is screwed onto the screw shaft 35 between the dampers 42, 43, and is held by a nut holder 44 having a rectangular section. The nut holder 44 is engaged within a guide groove 46, which is formed in the guide plate portion 24c of the tilt bracket 24 and extending along the up-and-down directions. An engaging pin 47, which is protrudingly formed from the nut holder 44, is engaged with a slot 12m, which is formed to extend along an axial direction in the protrusion 12c integrally formed with the outer column 12a. Accordingly, a rotation of the nut holder 44 around a center axis of the screw shaft 35 is restricted, whereby the nut holder 44 moves along the up-and-down directions in accordance with a rotation of the screw shaft 35 in forward and reverse directions.
Therefore, when the electric motor 40 drives the worm 37 in forward and reverse directions, the screw shaft 35 is driven in the forward and reverse directions so that the nut holder 44 is moved along the up-and-down directions and the outer column 12a is swung in the up-and-down directions around the tilt pivot shaft 23, whereby a tilting function can be exercised. An electric actuator 48 includes the electric motor 40, the worm 37, the worm wheel 36, the screw shaft 35 and the nut 45.
An electric telescopic mechanism 50 is provided between the outer column 12a and the inner column 12b of the steering column 12.
This electric telescopic mechanism 50 has a coupling plate portion 57 and a coupling rod 58. The coupling plate portion 57 is attached to the inner column 12b on a side of the steering wheel (a right end side in
Next, operations of the above-described embodiment will be explained.
Now, when a driver carries out a tilt adjustment of the steering column 12 of the steering column apparatus 10, a control switch provided in the peripheral components P, which is arranged on the rear side of the steering column 12 as shown in
In response thereto, the screw shaft 35 is driven in the reverse direction (or in the forward direction) via the worm 37 and the worm wheel 36 so that the nut 45 is moved upwardly (or downwardly) as viewed in
Reduction of the surface pressure of the slidably contacting surface reliably prevents damages and running out of lubricating oil with respect to the slidably contacting surfaces, and also prevents an abnormal noise and an increase of drive current for driving the electric motor 40 of the electric tilting mechanism 30 at the time of sliding contact. In addition, because the dimensional accuracy is no longer required to be improved, it is possible to reduce the manufacturing cost.
Moreover, because the stress cushioning members 25a, 25b are attached to the projected portions 12c, 12d of the outer column 12a, lengths of the respective stress cushioning members 25a, 25b along the sliding direction can be made to be the same as the lengths of the projected portions 12c, 12d. Accordingly, the lengths of the stress cushioning members 25a, 25b can be designed to be necessary minimum lengths.
When the driver carries out a telescopic adjustment of the steering column 12 of the steering column apparatus 10, a control switch provided in the peripheral component P, which is arranged on the rear side of the steering column 12 as shown in
In the first embodiment described above, the description has been made of a case in which the stress cushioning members 25a, 25b are adhered or welded to the projected portions 12c, 12d of the outer column 12a. However, the present invention is not limited thereto. The stress cushioning members 25a, 25b may be fixed by other fixing means such as screws.
Further, in the first embodiment, the description is made of a case in which the stress cushioning members 25a, 25b are attached to the flat end surfaces of the projected portions 12c, 12d of the outer column 12a. However, the present invention is not limited thereto. As shown in
Further, as shown in
Next, a second embodiment of the present invention will be explained with reference to
In this second embodiment, the stress cushioning members 25a, 25b are fixed to the tilt bracket 24.
That is, as shown in
In this case, lengths of the stress cushioning members 25a, 25b along the up-and-down directions are set to correspond to a tilt adjusting range of the steering column 12.
According to the second embodiment, the stress cushioning members 25a, 25b are fixed to the clearance filling plate 24g and the guide plate portion 24d, and the flat end surfaces of the projected portions 12c, 12d of the outer column 12a are slidably contacted to the stress cushioning members 25a, 25b. Therefore, similar advantageous effects similar as the first embodiment can be contained.
While the description has been made of a case in which the stress cushioning members 25a, 25b are fixed onto the flat inner side surface of the clearance filling plate 24g and the flat inner side surface of the guide plate portion 24d of the tilt bracket 24 in the second embodiment, the present invention is not restricted thereto. As shown in
Further, as shown in
Furthermore, while the first and second embodiments have been explained that both of the stress cushioning members 25a, 25b are fixed on the outer column 12a or on the clearance filling plate 24g and the guide plate portion 24d, the present invention is not restricted thereto. Alternatively, the stress cushioning member 25a may be fixed on the clearance filling plate 24g and the other stress cushioning member 25b may be fixed on the projected portion 12d of the outer column 12a. Conversely, the stress cushioning member 25a may be fixed on the projected portion 12c of the outer column 12a and the other stress cushioning member 25b may be fixed on the guide plate portion 24d. Moreover, one of the right and left stress cushioning members 25a, 25b may be omitted.
It should also be noted that, while the first and second embodiments have been explained that the present invention is applied to the steering apparatus having the electric tilting mechanism 30, the present invention is not restricted thereto, and may also be applied to a steering apparatus having a general manual tilt mechanism without the electric tilting mechanism 30.
The present application is based on Japanese Patent Application No. 2007-050133 filed on Feb. 28, 2007, the content of which is incorporated herein by reference.
Number | Date | Country | Kind |
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2007-050133 | Feb 2007 | JP | national |
Filing Document | Filing Date | Country | Kind | 371c Date |
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PCT/JP2008/050712 | 1/21/2008 | WO | 00 | 9/9/2008 |