Machine element or mechanism – Control lever and linkage systems – Hand operated
Reexamination Certificate
1999-05-05
2001-03-20
Herrmann, Allan D. (Department: 3682)
Machine element or mechanism
Control lever and linkage systems
Hand operated
C074S545000, C180S006300, C180S332000, C297S411360, C297S411370
Reexamination Certificate
active
06202501
ABSTRACT:
TECHNICAL FIELD
The present invention relates to a steering apparatus for a construction vehicle.
BACKGROUND ART
Conventionally, a steering wheel method and a joystick lever method have been known as steering methods of construction vehicles. In the steering wheel method, an operator turns a steering wheel provided at a driver's seat, thereby obtaining a steering angle almost proportional to the turning angle, and the maximum turning angle is, for example, two or three turns respectively to the right and left. According to the steering wheel method, a steering angle corresponding to a turning angle is obtained, therefore enabling a fine steering operation. In addition, a construction vehicle can be driven with the same feeling as in driving a car, which makes it easy to travel.
Meanwhile, in the joystick lever method, an operator tilts a joystick lever provided at a driver's seat, thereby obtaining a steering speed (changing speed of a steering angle) which is almost proportional to the tilting angle. The maximum tilting angle is the maximum angle of turning the wrist respectively to the right and left, thereby enabling an operation with one hand. Consequently, it is easy to travel while operating a working machine.
The conventional steering methods as described above, however, have the following disadvantages. In the steering wheel method, a larger turning angle is required in order to obtain a larger steering angle, which becomes one of the reasons for causing fatigue of the operator in a construction vehicle requiring frequent switching of the steering. When traveling during an operation, it is necessary to operate a steering wheel with one hand, which causes the disadvantage of the steering operation being very difficult.
In the joystick method, a steering speed almost proportional to the tilting angle of a joystick lever is obtained, and therefore in a situation in which a lever is tilted, the steering is turned too much. For this reason, each time when a steering angle reaches a target steering angle in one steering operation, it is necessary to return the joystick lever to a neutral position so that the steering speed recovers to 0 (zero). In addition, when the steering angle is further returned to the straight-ahead position, it is necessary to carry out the same operation as above in the reverse direction. Accordingly, the number of operations increases, thereby increasing the workload on the operator. Further, in order to operate the steering at a minute steering angle, it is necessary to continuously operate the lever in a minute tilting angle range in the reverse directions in a short time, therefore making the operation extremely difficult, and the steering tends to be unstable.
SUMMARY OF THE INVENTION
Paying attention to the aforesaid disadvantages, the present invention is made, and its object is to provide a steering apparatus with excellent operability, which is especially excellent in a minute steering operation
A steering apparatus according to the present invention is a steering apparatus for a construction vehicle, and is characterized by including
a steering operation shaft rotating almost horizontally, and
a lever which is coupled to the steering operation shaft, separated by a predetermined horizontal distance from the steering operation shaft, and which turns almost horizontally to rotate the steering operation shaft.
According to the above configuration, the steering operation shaft is rotated by means of the lever which is horizontally separated by a predetermined distance from the steering operation shaft, therefore it is easy for an operator to feel the degree of the horizontal rotational angle as a quantity of the steering operation. Accordingly, a fine-tuning of the operating quantity is enabled by slightly moving the lever.
Further, the steering operation shaft may be positioned almost beneath the wrist of the operator when the operator grips the lever. According to the configuration, the steering operation shaft is positioned almost beneath the wrist when the operator grips the lever, and therefore the lever is turned around the wrist. Thereby, the operability of the steering, especially the operability in a minute operation is improved.
Furthermore, an arm rest, on which the operator fixes his or her elbow or arm when the operator grips the lever, may be included. According to the configuration, a steering operation can be performed in a stabilized state with his or her elbow or arm being fixed on the arm rest, therefore the operability in steering is improved.
Further, the positions of the lever and the arm rest may be adjustable at least either in an almost horizontal direction or in a vertical direction, relative to an operator seat in which the operator sits. According to the configuration, the positions of the lever and the arm rest are adjustable in an almost horizontal direction and/or a vertical direction, relative to the operator seat in which the operator sits, therefore the lever and the arm rest can be adjusted corresponding to the physical constitution of the operator. Accordingly, the operator can steer in a natural posture, therefore improving the operability of the steering.
In addition, it is suitable to further include a pilot valve which is disposed almost beneath the steering operation shaft, with an input shaft and a feedback shaft being provided on a concentric axis, and which outputs pilot hydraulic pressure almost proportional to the deviation angle of the rotational angle of the input shaft and the rotational angle of the feedback shaft to control the steering angle of the construction vehicle, and coupling means for coupling the steering operation shaft and the input shaft so that the steering operation shaft is movable horizontally and vertically relative to the input shaft.
According to the above configuration, the steering operation shaft and the rotating shaft of the pilot valve are coupled by the coupling means so that the steering operation shaft is movable horizontally and vertically relative to the rotating shaft of the pilot valve. Accordingly, even if the lever and the steering operation shaft are moved correspondingly to the physical constitution of the operator, or the like, the rotational angle of the steering operation shaft can be transmitted to the rotating shaft of the pilot valve by the coupling means. Thereby, the operator seat and the steering operation shaft can be moved to a position at which the operator comfortably carries out the operation, therefore improving the steering operability.
Furthermore, the input shaft and a rotational axis of the steering operation shaft may be disposed almost in parallel. According to the configuration, the rotating shaft of the pilot valve and the rotational axis of the steering operation shaft are almost in parallel, therefore enabling to simplify the configuration of the coupling means for transmitting the rotation of the steering operation shaft to the pilot valve, and to effectively transmit the rotation of the steering operation shaft.
Further, the steering angle may be almost proportional to the rotational angle of the steering operation shaft. According to the configuration, the steering angle is controlled to be almost proportional to the rotational angle of the steering operation shaft (namely, the operating angle of the lever), therefore eliminating a need to return the lever to the central position when the steering angle reaches a target steering angle. Thereby, the number of operations is reduced, therefore reducing the fatigue of the operator. In addition, the steering speed does not change relative to the operating angle of the lever, therefore enabling a stable steering operation. Further, the rotational angle and the rotational direction of the steering operation shaft can easily correspond to the steering angle and the steering turning direction. Thereby, the operator has immediate and clear feeling of the steering operation, therefore facilitating the steering operation.
Furthermore, the changing speed of the steering angle may cha
Armstrong Westerman Hattori McLeland & Naughton LLP
Herrmann Allan D.
Komatsu Ltd.
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