Land vehicles – Wheeled – Running gear
Reexamination Certificate
2002-01-08
2004-02-10
Dickson, Paul N. (Department: 3616)
Land vehicles
Wheeled
Running gear
C280S775000, C074S492000
Reexamination Certificate
active
06688644
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the invention
The present invention relates to a steering apparatus adapted to support a steering shaft so that a tilt can be adjusted and, more particularly, to a steering apparatus constituted to absorb energy of a secondary crash which is applied to the steering shaft at the time of a vehicle crash, utilizing a guiding portion for tilt adjustment.
2. Description of Related Art
A vehicle is steered by transmitting rotation caused by an operation of a steering wheel disposed in a driver's room to a steering mechanism disposed outside the driver's room for turning tire wheels for steering (the front wheels, in general). The steering wheel is mounted at an upper end portion of a steering shaft which is supported in the driver's room so as to be rotatable about an axis so that a driver can operate the steering wheel.
The steering shaft is rotatably supported in a cylindrical column housing. The steering shaft and the column housing are supported in a tilted orientation with the upper end portion, at which the steering wheel is mounted, leaning backwards. The steering shaft is extended to the exterior of the driver's room via an intermediate transmittance shaft such as a universal joint or the like, and is connected to the steering mechanism. The steering mechanism has a movement transforming unit, such as a rack-and-pinion, a ball thread or the like, allowing rotation of the steering wheel transmitted via the steering shaft and the intermediate transmittance shaft to the steering mechanism to be transformed into movement for turning the tire wheels via the movement transforming unit.
Some of such steering apparatuses of late years have a constitution with which a position of the steering wheel at an upper end of the steering shaft can be adjusted for realizing driver's comfortable steering operation. In general, a position of the steering wheel is adjusted with a combination of tilt adjustment for adjusting a tilt angle of the steering shaft along with the a column housing and telescopic adjustment for extending and contracting a middle portion of the steering shaft and the column housing.
Moreover, many of steering apparatuses of late years comprise an energy absorbing mechanism for absorbing energy of the crash, for reducing damage to the driver who has made a crash (a secondary crash) into the steering wheel by the action of inertia to the front at the time of the crash of the vehicle. In general, the energy absorbing mechanism is provided with an elastic portion at a middle portion of the steering shaft and the column housing, which portion is elastic in an axial direction under suitable resistance. Energy of the secondary crash is absorbed in virtue of sliding resistance which is generated while the elastic portion is contracted by action force caused by the secondary crash.
However, in a steering apparatus for a vehicle with a small space at the front portion of the driver's seat, such as a buss, a truck, a monospace car or the like, the steering shaft has to be supported with a large tilt angle with regard to a floor. In such a state, a direction of force, which is applied to the steering wheel at an upper end of the steering shaft at the time of the secondary crash, scarcely accords with an axial direction of the steering shaft. With a steering apparatus of this kind, the above energy absorption utilizing contraction of the steering shaft and the column housing is difficult to be realized. Consequently, for a conventional steering apparatus used in a vehicle of this kind, an energy absorbing mechanism is employed which absorbs energy of a secondary crash utilizing leaning of the steering shaft in a direction in which the tilt angle increases.
FIGS. 1A and 1B
are schematic representations showing a constitution of a steering apparatus comprising an energy absorbing mechanism utilizing an increase of a tilt angle. A steering shaft
1
is rotatably supported in a cylindrical column housing
2
, and is mounted to a tilting bracket
4
, which is fixed to and supported by a part of a driver's room, via a column bracket
3
fastened to a middle portion of said column housing
2
.
To an upper end portion of the steering shaft
1
which is projected from an upper portion of the column housing
2
, a steering wheel
10
is fixed. A lower end portion of the steering shaft
1
which is projected from a lower portion of the column housing
2
is connected via a universal joint
11
and an intermediate shaft
12
to a steering mechanism which is not shown in the figures. Rotation caused by an operation of the steering wheel
10
for steering is transmitted to the steering mechanism via the steering shaft
1
, the universal joint
11
and the intermediate shaft
12
. The intermediate shaft
12
, which is constructed by engaging an inner shaft
12
a
having a deformed cross section into an outer tube
12
b
of the same shape, is a telescopic shaft which can be extended and contracted in an axial direction by sliding the inner shaft
12
a
in and out of the outer tube
12
b
and can be rotated in one body at a suitable elastic position.
The column bracket
3
having a box-shaped cross section is integrally fastened to an exterior face of the column housing
2
. The column housing
2
comprises a pair of upper and lower telescoping apertures
30
and
31
which extend in an axial direction of the column housing
2
. The tilting bracket
4
has a cross section which is substantially in the shape of “U” with an open portion of both side walls placed downward. The column bracket
3
, which is fitted between both side walls of the tilting bracket
4
, is mounted with a locking bolt
20
and a guiding bolt
21
which respectively run through the telescoping apertures
30
and
31
.
At a side wall of the tilting bracket
4
a tilting aperture
40
is formed which is curved in an arc shape with a through portion of the guiding bolt
21
at a lower position as a center of the arc. The locking bolt
20
at an upper position runs through an intersecting portion where a tilting aperture
40
and a telescoping aperture
30
intersects, and is fastened to said position. At an upper portion of the tilting aperture
40
a guiding aperture
41
is formed to have a curved form in an extension to the tilting aperture
40
. At a boundary portion between the guiding aperture
41
and the tilting aperture
40
a stopper
5
is mounted. The stopper
5
which is configured as a tube with a diameter slightly larger than a width of the guiding aperture
41
is fitted at the boundary portion between the guiding aperture
41
and the tilting aperture
40
via a bush
50
made of resin, and is provided transversely between both side walls of the tilting bracket
4
.
In a steering apparatus constituted as above, the above tilt adjustment and the telescopic adjustment are performed in a state where the locking bolt
20
is unfastened. The column bracket
3
can move with regard to the tilting bracket
4
fixed to a carbody by sliding the locking bolt
20
and the guiding bolt
21
along the upper and lower telescoping apertures
30
and
31
. Telescopic adjustment for displacing the column housing
2
and the steering shaft
1
in an axial direction is caused by the movement of the column bracket
3
. This adjustment is achieved by extension and contraction of the intermediate shaft
12
constituted as a telescopic shaft.
Moreover, the column bracket
3
can be oscillated about an axis of the guiding bolt
21
with regard to the tilting bracket
4
fixed to a carbody, by sliding the locking bolt
20
along the tilting aperture
40
. Tilt adjustment for adjusting a tilt angle of the column housing
2
and the steering shaft
1
is achieved by the oscillation of the column bracket
3
. The steering shaft
1
and the column housing
2
thus can be oscillated about an axis of a connecting portion of the steering shaft
1
and the universal joint
11
, and extension and contraction of the intermediate shaft
12
change the tilted orientation.
FIG.
Kuromaru Yoshikazu
Minamoto Noboru
Tsunoda Yoshihiro
Darby & Darby
Dickson Paul N.
Koyo Seiko Co. Ltd.
Spisich George D.
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