Motor vehicles – Steering gear – With mechanical power assist
Reexamination Certificate
2001-06-22
2002-05-14
Boehler, Anne Marie (Department: 3618)
Motor vehicles
Steering gear
With mechanical power assist
C180S444000, C280S093510, C474S083000
Reexamination Certificate
active
06386313
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a gear ratio variable type steering device, and in particular to a gear ratio variable type steering device which is capable of varying a linear displacement of a rack bar based on the revolution of a steering wheel in accordance with the speed of a vehicle.
2. Description of the Background Art
Generally, a steering device of a vehicle is constructed in such a manner that a linear displacement of a rack bar is constantly generated when a driver rotates a steering wheel. The thusly generated linear displacement is expressed as 40 mm/rev. The gear ratio affects the characteristics of the steering operation of the vehicle.
FIG. 1
is a perspective view illustrating a conventional steering device. As shown therein, the conventional steering device includes a steering wheel
10
for generating a steering force based on a driver's operation, a column
20
connected with the lower potion of the same, a universal joint
30
connected to the lower portion of the column
20
, and a gear box
40
installed below the same.
FIG. 2
is a front view illustrating the gear box, and
FIG. 3
is a cross-sectional view of the same. As shown therein, a housing
41
which forms the outer construction of the gear box
40
is provided.
In addition, a hollow input shaft
42
is protrudely installed in the housing
41
for receiving a steering force generated by the steering force.
A pinion gear
43
is integrally provided at the lower portion of the input shaft
42
. A rack bar
44
having a rack gear
45
at one side of the same is installed at the lower portion of the housing
41
for a linear movement based on an engagement with the pinion gear
43
.
At this time, the rack bar
44
is displaced axially across the rack gear
45
, and a ball joint
50
connected with the steering member
60
is installed at both ends of the rack bar
44
.
In the thusly constructed conventional steering device, when a driver rotates the steering wheel
10
, the input shaft
42
is rotated, and the rack bar
44
is linearly operated based on the gear ratio which is determined when designing the vehicle and angular-operates the steering member
60
.
In the conventional steering device, since a certain gear ratio is constantly generated irrespective of a low speed or high speed operation, the distance of the movement of the rack bar becomes same based on the revolution of the input shaft.
Therefore, it is impossible to generate a large movement of the rack bar by rotating the steering wheel by a small amount at a low speed operation and generate a small movement of the rack bar by rotating the steering by a large amount at a high speed operation.
Namely, the conventional steering device is designed based on a constant gear ratio. Therefore, it is needed to rotate the steering wheel by a large amount in the case of the low speed operation and parking operation which need a large steering angle for thereby causing much inconvenience. In the case of the high speed operation which needs a small steering angle, the large steering angle is generated which is not proper to the high speed operation, so that it is impossible to obtain a certain steering stability.
SUMMARY OF THE INVENTION
Accordingly, it is an object of the present invention to provide a gear ratio variable type steering device which overcomes the problems encountered in the conventional art.
It is another object of the present invention to provide a gear ratio variable type steering device which includes a variable gear mechanism between a steering wheel and a gear box for varying a gear ratio based on the speed of a vehicle.
To achieve the above objects, there is provided a gear ratio variable steering device a gear ratio variable type steering device which comprises a variable gear mechanism which includes an input shaft for receiving a rotational force of the steering wheel, an output shaft for transferring a rotational force to the gear box, a variable pulley installed in the outer portions of the input shaft and the output shaft and moved in the axial direction, a belt for connecting the variable pulley, and a motor for varying a gear ratio by moving the variable pulley in the axial direction.
REFERENCES:
patent: 5267625 (1993-12-01), Shimizu
patent: 5284219 (1994-02-01), Shimizu et al.
patent: 5298000 (1994-03-01), Rattude et al.
patent: 5482130 (1996-01-01), Shimizu
patent: 5511629 (1996-04-01), Vogel
patent: 6041887 (2000-03-01), Kojo
patent: 6179083 (2001-01-01), Yamauchi
patent: 6302441 (2001-10-01), Kawamuro
Boehler Anne Marie
Coleman Henry
Mando Corporation
Sapone William
Sudol R. Neil
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