Motor vehicles – Having at least one wheel both driven and steerable
Reexamination Certificate
2000-08-08
2002-11-19
Boehler, Anne Marie (Department: 3611)
Motor vehicles
Having at least one wheel both driven and steerable
C180S253000
Reexamination Certificate
active
06481524
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 Background 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 (4WS) have been known as prior art four-wheel vehicles which can improve the turning radius. The 4WS 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 4WS 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 since 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, since 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 that it has only limited operation states in which the vehicle can be turned with stability.
Conventional vehicles also have a problem that drivers encounter difficulties in performing a turning operation with a good operability.
SUMMARY OF THE INVENTION
It is therefore an object of the present invention to provide a four-wheel vehicle which is capable of stably turning the vehicle body with a relatively small turning radius. It is another object of the present invention to provide a four-wheel vehicle which is capable of permitting a driver to perform a turning operation with a good operability.
A four-wheel vehicle equipped with a turning mechanism according to the present invention comprises a rotatably supporting device 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; an instructing device for generating a turn mode instruction in response to a manipulation; a determining device for determining whether a vehicle operating state satisfies predetermined conditions when the turn mode instruction is generated; a rotation driving device, when the determining device 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, with 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 device for applying a rotating torque to the one pair of left and right wheels at the angular positions along the tangential directions to turn the 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 four-wheel vehicle of the present invention described above, since one of 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 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, since the one pair of left and right wheels will not be rotated from the straight traveling positions taken when the vehicle is running to the respective angular positions along the tangential directions for a turning operation unless the vehicle operating state satisfies the predetermined conditions suitable for a turn when a turn mode instruction is generated, the turning operation can be performed while the vehicle is in a stable state. Further, since the one pair of left and right wheels are applied with a rotating torque at angular positions along tangential directions to turn the 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, the turning radius is extremely small.
The four-wheel vehicle includes a left turn instructing device for generating a left turn instruction in response to a manipulation, and a right turn instructing device for generating a right turn instruction in response to a manipulation, wherein the turn driving device turns the vehicle body counterclockwise in response to the left turn instruction, and turns the vehicle body clockwise in response to the right turn instruction. According to this configuration, the vehicle body can be turned either in the clockwise or counterclockwise direction with a simple manipulation.
The left turn instructing device and the right turn instructing device are arranged integral with a steering wheel. According to this configuration, the driver can readily perform a left turn or a right turn operation while holding the steering wheel.
The four-wheel vehicle comprises a transmission formed with a left turn shift position and a right turn shift position in addition to shift positions for transmission, wherein the left turn instructing device generates the left turn instruction when a shift lever of the transmission is moved to the left turn shift position, and the right turn instructing device generates the right turn instruction when the shift lever of the transmission is moved to the right turn shift position. According to this configuration, the driver can readily perform a left turn or a right turn operation by manipulating the shift lever of the transmission.
The instructing device generates a turn mode stop instruction in response to a manipulation, and the rotation driving device rotates the one pair of left and right wheels from the angular position along the tangential directions to the straight traveling positions in response to the turn mode stop instruction. According to this configuration, after the vehicle body is turned, the one pair of left and right wheels can be rotated to the original straight traveling positions by a manipulation of the driver.
The predetermined conditions include at least the following conditions:
(a) the vehicle stops running; and
(b) the steering angle of front wheels is substantially zero degrees. By thus defining the predetermined conditions, it is possible to confirm whether vehicle is in a state from which the vehicle can transition without any problem to a vehicle body turning operation for which the one pair of left and right wheels are driven to rotate.
The condition defining that the vehicle stops running is detected from a shif
Hanaoka Tadashi
Ishida Yoshimitsu
Armstrong Westerman & Hattori, LLP.
Boehler Anne Marie
Honda Giken Kogyo Kabushiki Kaisha
Winner Tony
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