Data processing: vehicles – navigation – and relative location – Vehicle control – guidance – operation – or indication – Vehicle subsystem or accessory control
Reexamination Certificate
2000-04-07
2002-05-14
Cuchlinski, Jr., William A. (Department: 3661)
Data processing: vehicles, navigation, and relative location
Vehicle control, guidance, operation, or indication
Vehicle subsystem or accessory control
C701S043000, C701S062000, C180S193000, C180S443000, C475S286000, C475S225000, C318S432000, C318S434000
Reexamination Certificate
active
06389342
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a steering apparatus for a vehicle in which a steering mechanism for changing a direction of tire wheels is not mechanically connected to a steering wheel, a steering torque applied to the steering wheel is obtained and an electric motor included in the steering mechanism is driven and controlled in accordance with the calculated steering torque, thereby increasing or decreasing a steering angle.
A steering operation of a vehicle is performed by operating a steering device arranged within passengers' room, for example, by transmitting a rotation of the steering wheel to the steering mechanism which is arranged outside the passengers' room for directing tire wheels (generally front tire wheels).
In recent years, there has been widely spread a steering apparatus (a power steering apparatus) for vehicle structured such as to arrange an actuator for steering assistance such as a hydraulic cylinder, an electric motor or the like in the middle of the steering mechanism, drives the actuator based on a detected result of operating force applied to the steering wheel to assist an operation of the steering mechanism in accordance with the rotation of the steering wheel, thereby reducing labor and load of a driver for steering.
However, in the conventional steering apparatus mentioned above, a mechanical connection (linkage) between the steering wheel corresponding to the steering device and steering mechanism is required, so that there is a problem that an arranging position of the steering wheel within the passengers' room is limited to a position at which the connection with the steering mechanism outside of the passengers' room can be achieved, and further, even in the case that the steering wheel is arranged at connectable position, a complex connecting structure is required for realizing the connection, so that this becomes a reason of interrupting the vehicle from being reduced in weight and its assembling process from being simplified.
For example, in Japanese Utility Model Publication No. 2-29017, there is disclosed a steering apparatus such as a linkless (drive-by-wire) power steering apparatus which is aimed to solve the problem mentioned above. In this steering apparatus, the steering wheel is mechanically separated from the steering mechanism and an electric motor such as an actuator for steering is arranged in the middle of the steering mechanism in the same manner as that of the actuator for steering assistance in the conventional steering apparatus. The structure is made such that the steering operation is performed in accordance with the operation of the steering wheel by driving the electric motor based on a detected result of operating direction and operating amount of the steering wheel.
The linkless steering apparatus structured in the manner mentioned above has advantages for automobile technology development future such as realizing a new steering device such as a lever (a joy stick), a pedal in place of the steering wheel, realizing an autopilot system in accordance with a route information obtained by detecting guide signs on a road surface and by receiving a satellite information, in addition to the scopes mentioned above such as increasing freedom of arrangement of the steering wheel and reducing weight of the vehicle.
In the above-mentioned steering apparatus, a torque sensor using a torsion bar is considered as its conventional detecting system of the steering torque, however, the system has problems that the torque sensor using the torsion bar is high in cost and that a freedom of design is limited because of size and placing position thereof are limited.
BRIEF SUMMARY OF THE INVENTION
The present invention is made by solving the problems mentioned above, and an object of the present invention is to provide a linkless steering apparatus for a vehicle which does not require a torque sensor for detecting a steering torque which occupies a large space and is high in cost.
In accordance with a first aspect of the present invention, there is provided a steering apparatus, in which a steering mechanism for changing a direction (a steering angle) of a tire wheel is not mechanically connected to a steering wheel, a steering torque applied to the steering wheel is obtained and an actuator included in the steering mechanism is driven and controlled in accordance with the obtained steering torque, thereby increasing or decreasing steering angle, characterized by comprising: an electric motor connected to a rotational shaft of the steering wheel; a steering angle detector for detecting a steering angle of the steering wheel; and a calculator for calculating the steering torque based on the steering angle detected by the steering angle detector, a moment of inertia of the steering wheel, and a moment of inertia of the electric motor.
In this invention, the steering mechanism for changing a direction of the tire wheel is not mechanically connected to the steering wheel, the steering torque applied to the steering wheel is obtained, and the actuator included in the steering mechanism is driven and controlled in accordance with the obtained steering torque, whereby the steering angle is controlled so as to be increased or decreased. The electric motor is connected to the rotational shaft of the steering wheel and the steering angle detector detects the steering angle of the steering wheel. The calculator calculates the steering torque based on the steering angle detected by the steering angle detector, the moment of inertia of the steering wheel, and the moment of inertia of the electric motor.
Therefore, it is possible to realize a linkless steering apparatus which does not need a torque sensor that occupies large space and is high-cost.
In accordance with a modification of the first aspect, there is provided a steering apparatus, further comprising a current detector for detecting an electric current flowing through the electric motor, wherein the calculator calculates the steering torque based on the electric current detected by the current detector, the steering angle of the steering wheel, the moment of inertia of the steering wheel, and the moment of inertia of the electric motor.
In this invention, the current detector detects the current which flows through the electric motor. The calculator calculates the steering torque based on the electric current detected by the current detector, the steering angle detected by the steering angle detector, the moment of inertia of the steering wheel, and the moment of inertia of the electric motor. That is, for example, even when the electric motor is operated as a reaction-force motor in the invention mentioned above, the calculator determines a reaction force which the electric motor actually generates based on the electric current detected by the current detector and calculates the steering angle by considering the reaction force.
Therefore, it is possible to realize a linkless steering apparatus which does not need a torque sensor that occupies large space and is high-cost, even in the case that the electric motor generates the reaction force.
More particularly, in the calculation of the steering torque in the former invention, the calculator calculates a steering angular acceleration based on the steering angle, adds the moment of inertia of the steering wheel and the moment of inertia of the electric motor, multiplies by the steering angular acceleration by the added result, and calculates the steering torque based on the multiplied result.
Further, in the calculation of the steering torque in the latter invention, the electric current flowing through the electric motor is detected by the current detector, and the calculator calculates the steering angular acceleration based on the steering angle, adds the moment of inertia of the steering wheel and the moment of inertia of the electric motor, multiplies the steering angular acceleration by the added result, further, adds the multiplied result and the value based on the electric current and c
Cuchlinski Jr. William A.
Koyo Seiko Co. Ltd.
To Tuan C
LandOfFree
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