Note: Descriptions are shown in the official language in which they were submitted.
CA 02357463 2001-09-19
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TITLE: POWER STEERING SYSTEM
FIELD OF THE INVENTION
The present invention relates to a power
steering system.
BACKGROUND OF THE INVENTION
Hitherto, as a power steering system of this
kind, there has been known one having the structure shown
in Fig. 3.
The power steering system shown in the figure
comprises a power assist cylinder 3 provided between a
steering shaft 1 and a vehicle body frame 2, a control
valve 4 operated by the steering shaft 1 to control the
power assist cylinder 3, an oil pump 5 for pressurizing a
working oil supplied to the power assist cylinder 3, and
an oil tank 6 for reserving the working oil, the oil tank
6 being of an open-to-atmosphere type and being fitted to
the vehicle body frame 2.
The oil pump 5, the oil tank 6 and the control
valve 4 are communicated with each other by three oil
pipings 7.
An input shaft 8 is fixed to a lower end portion
of the steering shaft 1 by welding, and a spool lever 9
for operating the control valve 4 is fastened and fixed
to the steering shaft 1 through a clamp member 9b.
An output shaft 9a to which the power assist
cylinder 3 is connected is connected to the input shaft
8.
In the prior art as above-mentioned, the input
shaft 8 is fixed to a lower end portion of the steering
shaft 1 by welding and the output shaft 9a to which the
power assist cylinder 3 is connected is connected to the
input shaft 8, so that a power assist portion including
the power assist cylinder 3 and the control valve 4 and a
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steering shaft portion including the output shaft must be
separately assembled onto a vehicle body, and there is
the problem that much time is required for assembly.
In addition, since the spool lever 9 for
operating the control valve 4 is fastened and fixed to
the steering shaft 1 through a clamp member 9b, the
condition of fastening has an influence on assembly
accuracy.
The present invention has been made in
consideration of the above-mentioned problems in the
prior art, and it is an object of the present invention
to provide a power steering system with which it is
possible to simplify the assembly onto a vehicle body and
to enhance assembly accuracy.
SUMMARY OF THE INVENTION
In order to attain the above obj ect, the power
steering system according to the present invention
resides in a power steering system comprising a steering
shaft turnably fitted to a vehicle body frame, a power
assist cylinder provided between the steering shaft and
the vehicle body frame, a control valve operated by the
steering shaft to control the power assist cylinder, and
a spool lever fitted to the steering shaft for operating
the control valve. The power steering system is
characterized in that the steering shaft is divided into
two portions in the axial direction to set the lower
portion to be an input shaft, a connecting cylinder to
which the input shaft is serration-fitted is integrally
provided at a lower portion of the steering shaft, a side
wall of the connecting cylinder is provided with a groove
in the axial direction, a fastening means is provided for
reducing the diameter of the connecting cylinder so as to
reduce the width of the groove, and the spool lever is
integrally fitted to the input shaft.
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BRIEF DESCRIPTION OF THE DRAWINGS
Preferred embodiments of the invention are shown
in the drawings, wherein:
Fig. 1 is a side view of a vehicle for running on
a rough ground to which one embodiment of the present
invention has been applied.
Fig. 2A and 2B illustrate a system constitution
diagram of one embodiment of the present invention.
Fig. 3 is a system constitution diagram of a prior
art example.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
Now, an embodiment of the present invention will be
described in detail below based on the drawings.
Fig. 1 shows a saddle ride type vehicle as a vehicle
to which the present embodiment has been applied. Tree
vehicle comprises a pair of front wheel 12 and rear wheel 1.3
supported in the front-rear and left-right directions of a
vehicle body frame 11 with an engine 10 mounted on a centr2.1
portion thereof, a steering shaft 14 turnably fitted to a
front portion of the vehicle body frame 2, a steering arm 1.5
connecting the front wheel 12 as a steered wheel and the
steering shaft 14, a steering handle 16 fitted to an upper
portion of the steering shaft 14, and a seat 17 fitted t.o
the vehicle body frame 11 at a position on the rear side of
the steering handle 16. Further a power steering system 1.8
according to the present embodiment is provided between the
vicinity of a lower portion of the steering shaft 14 and the
vehicle body frame 11.
A connecting cylinder 19 provided with a serration
19a on the inside thereof is integrally fitted to a lower
end portion of the steering shaft 14, a side wall of the
connecting cylinder 19 is provided with a groove 19b
reaching to the lower end edge of the side wall, flanges 20
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are projected on both sides of the groove 19b, a fastening
bolt 21 is provided penetrating through the flanges 20, and
the spacing between the flanges 20 is reduced by the
fastening bolt 21 and a nut 22 mated with the fastening bolt
21, whereby the inside diameter of the connecting cylinder
19 can be reduced.
An input shaft 23 is inserted into the connecting
cylinder 19 from the lower end portion, is meshed with the
serration 19a so that relative rotation around an axis is
inhibited, and is integrated with the connecting cylinder 19
by a reduction in the diameter of the connecting cylinder
19.
In addition, a spool lever 25 for operating a
control valve 24 constituting the power steering system 18
described later is integrally fitted to the input shaft 23
at a position on the lower side of the connecting cylinder
19 by welding.
Further, as shown in Fig. 2A and 2B, the power
steering system 18 comprises an output shaft 26 provided
axially adjacent to a lower portion of the input shaft 23, a
center arm 27 provided so as to project in the radial
direction of the output shaft 26, a power assist cylinder 28
intermediately disposed between the center arm 27 and the
vehicle body frame 11, the control valve 24 fitted to the
power assist cylinder 28 to control the power assist
cylinder 28, an oil pump 29 fitted to the engine 10 for
supplying by pressurizing a working oil to the control valve
24, and an oil tank 30 reserving the working oil.
The oil pump 29 and the control valve 24 are
communicated with each other by a working oil supply pipe 3:1
for supplying the working oil pressurized by the oil pump 29
to the control valve 24, and a working oil return
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pipe 32 for returning the working oil from the control
valve 24 to the oil pump 29 through the oil tank 30.
In the power steering system 18 according to the
present embodiment constituted as above, when the
steering handle 16 is operated to the left or right, the
spool lever 25 fitted to the steering handle 16 is
oscillated, the control valve 24 is operated, the working
oil supplied from the oil pump 29 is supplied to the
power assist cylinder 28, and a turning force in the
operating direction of the steering handle 16 is given to
the output shaft 26 through the center arm 27.
By this, the operating force on the steering
handle 16 is alleviated.
In the present embodiment, the input shaft 23 is
fastened and fixed to the steering shaft 14 through the
connecting cylinder 19 in the condition where relative
turning is inhibited by the serration 19a, and the spool
lever 25 is integrally fitted to the input shaft 23;
therefore, at the time of assembly onto the vehicle body,
the power assist portion including the input shaft 23,
the power assist cylinder 28 and the control valve 24 as
well as the input shaft 23 and the output shaft 26 are
preliminarily assembled, and then the connecting cylinder
19 is fitted and then fastened and fixed to the input
shaft 23, whereby the steering shaft 14 with the steering
handle 16 fitted thereto can be connected to the input
shaft 23.
Thus, in the present embodiment, the power
steering system 18 can be assembled onto the vehicle body
through an easy work.
In addition, with the spool lever 25 integrally
fixed to the input shaft 23, there is no possibility that
the fitting position of the spool lever 25 may be
staggered, and, therefore, an enhanced fitting accuracy
can be contrived.
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Incidentally, the shape, size and the like of
each component member shown in the above embodiment are
only presented as examples, and various modifications can
be made based on design requirement and the like.
According to the power steering system of the
present invention, the input shaft is fastened and fixed
to the steering shaft through the connecting cylinder in
the condition where relative turning is inhibited by the
serration, and the spool lever is integrally fitted to
the input shaft; therefore, at the time of assembly onto
the vehicle body, the power assist portion including the
input shaft, the power assist cylinder and the control
valve as well as the input shaft and the output shaft are
preliminarily assembled, and then the connecting cylinder
is fitted and then fastened and fixed to the input shaft,
whereby the steering shaft with the steering handle
fitted thereto can be connected to the input shaft. By
this, the power steering system can be assembled onto the
vehicle body through an easy work.
In addition, with the spool lever integrally
fixed to the input shaft, there is no possibility that
the fitting position of the spool lever is staggered,
and, therefore, enhanced fitting accuracy can be
contrived.
Although various preferred embodiments of the
present invention have been described herein in detail,
it will be appreciated by those skilled in the art, that
variations may be made thereto without departing from the
spirit of the invention or the scope of the appended
claims.
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