Motor vehicles – Having four wheels driven – With means for steering all driven wheels
Reexamination Certificate
2000-07-13
2003-02-25
Boehler, Anne Marie (Department: 3611)
Motor vehicles
Having four wheels driven
With means for steering all driven wheels
C180S242000, C180S253000, C180S411000
Reexamination Certificate
active
06523632
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a vehicle which can turn with a smaller turning radius.
2. Description of the Related Art
For four-wheel vehicles, a parameter called the “turning radius” is known for indicating the performance of each four-wheel vehicle. A vehicle having a smaller turning radius can make a smaller turn at a corner during a turning operation such as U-turn.
Vehicles employing four-wheel steering (
4
WS) have been known as prior art four-wheel vehicles which can improve the turning radius. The
4
WS refers to a system which controls the steering angle (rudder angle) of not only front wheels but also rear wheels in association with a manipulation through a steering wheel. The
4
WS system can reduce the turning radius due to the controllable steering angle provided to the rear wheels .
A fifth wheel system is also known as an improvement in the turning radius. The fifth wheel system additionally has a fifth wheel stored below the floor, in addition to four wheels, such that the fifth wheel is slightly protruded relative to the other wheels during a turn to lift up the vehicle body, and the fifth wheel is driven to have the vehicle make a turn.
However, the 4WS, while it is effective in reducing the turning radius, suffers from limitations to the reduction in the turning radius because the steering angle is limited in order to suppress an inherent shake-out phenomenon to a practically ignorable extent. The fifth wheel system in turn is expected to provide significant effects, but implies a problem that the vehicle becomes unstable due to a three-wheel state during a turning operation.
Moreover, because a vehicle turning operation which reduces the turning radius requires actuation of a turning mechanism which cannot be used during a normal running operation such as straight traveling and backward traveling, the vehicle presents another problem in that it has only limited operation states in which the vehicle can be turned with stability.
In addition, a vehicle, when equipped with such a turning mechanism, has been desired to provide improved operability during a turning operation.
SUMMARY OF THE INVENTION
It is therefore an object of the present invention to provide a vehicle which is capable of turning a vehicle body with a relatively small turning radius and a good operability during a turning operation.
A vehicle equipped with a turning mechanism according to the present invention comprises rotatably supporting means for supporting one of front and rear pairs of left and right wheels, to which a running torque produced by a driving source is not transmitted, for rotation concerning respective axes perpendicular to the ground; rotating position fixing means for fixing the one pair of left and right wheels at respective angular positions along tangential directions of an arc passing the respective axes perpendicular to the ground of the one pair of left and right wheels, and having the center located near a center point of a rotating axle for running the vehicle of the other of the front and rear pairs of left and right wheels; and turn driving means for applying a rotating torque to the one pair of left and right wheels at the angular positions fixed by the rotating position fixing means to turn a vehicle body on a neighborhood of the center point of the rotating axle for running the vehicle of the other pair of left and right wheels.
According to the vehicle of the present invention described above, because one of the front and rear pairs of left and right wheels, to which a running torque produced by the driving source is not transmitted, are supported for rotation concerning respective axes perpendicular to the ground, and the one pair of left and right wheels are fixed at the respective angular positions along the tangential directions of the arc passing the respective axes perpendicular to the ground of the one pair of left and right wheels, with the center of the arc located near the center point of the rotating axle for running the vehicle of the other of the front and rear pairs of left and right wheels, it is possible to provide a relatively simple and small turning mechanism. In addition, because the radius of the arc passing the axes of the one pair of left and right wheels perpendicular to the ground and having the center near the center point of the rotating axle of the other pair of left and right wheels is the turning radius when the vehicle is turned, the turning radius is extremely small.
Another vehicle equipped with a turning mechanism according to the present invention comprises steering means rotatably arranged for steering the vehicle; detecting means for detecting a manipulating state of the steering means; mode selecting means for selecting one of a normal mode for running the vehicle and a turn mode for turning a vehicle body while the vehicle stops running; steering control means for changing a steering angle of a steering wheel of the vehicle in accordance with a result of detection by the detecting means when the mode selecting means selects the normal mode; and turning means for turning the vehicle body on a neighborhood of the center point of an axle extending between a front or rear pair of left and right wheels of the vehicle in response to a result of detection by the detecting means, without allowing the steering control means to change the steering angle of the steering wheel in accordance with a result of detection by the detecting means when the mode selecting means selects the turn mode.
According to the vehicle of the present invention described above, the vehicle body is turned on a point near the center point of the rotating axle of the front or rear left and right wheels of the vehicle, thereby making it possible to turn the vehicle body with a relatively small turning radius. In addition, the steering means such as the steering wheel for use in the normal mode for running the vehicle is also used in the turn mode to perform the turning operation, the operability can be improved during the turning operation. Furthermore, the utilization of the steering means for the turning operation can reduce the cost as compared with a manipulating device such as a switch which would be newly provided for the turning operation.
The turning means includes rotatably supporting means for supporting one of front and rear pairs of left and right wheels, to which a running torque produced by a driving source is not transmitted, for rotation concerning respective axes perpendicular to the ground; determining means for determining whether a vehicle operating state satisfies predetermined conditions when the turn mode is selected; and rotation driving means, when the determining means determines that the predetermined conditions are satisfied, for rotating the one pair of left and right wheels from straight traveling positions taken when the vehicle is running to respective angular positions along tangential directions of an arc passing the respective axes perpendicular to the ground of the one pair of left and right wheels, the arc having the center located near a center point of a rotating axle of the other of the front and rear pairs of left and right wheels.
According to the vehicle described above, because one of the front and rear pairs of left and right wheels, to which a running torque produced by a driving source is not transmitted, are supported for rotation concerning the respective axes perpendicular to the ground, and the one pair of left and right wheels are rotated from the straight traveling positions taken when the vehicle is running to the respective angular positions along the tangential direction of the arc passing the respective axes perpendicular to the ground of the one pair of left and right wheels, with the center of the arc located near the center point of the rotating axle of the other of the front and rear pairs of left and right wheels, it is possible to provide a relatively simple and small turning mechanism. In addition, since he one pair of left and right w
Hamasaki Yoshito
Hanaoka Tadashi
Ishida Yoshimitsu
Katayama Masaru
Shigematsu Yasuto
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