Speed Change System for Work Vehicle
First Claim
1. A speed change system for a work vehicle having a continuously variable transmission device comprising:
- a pump swash plate operation mechanism configured to operate a swash plate of a variable capacity pump for the continuously variable transmission device;
a motor swash plate operation mechanism configured to operate a swash plate of a variable capacity motor for the continuously variable transmission device;
a swash plate angle control unit configured to non-stepwise adjust a swash plate angle of the variable capacity pump through the pump swash plate operation mechanism and stepwise adjust a swash plate angle of the variable capacity motor through the motor swash plate operation mechanism; and
an operation position detector configured to detect an operation position of a speed change operation tool;
whereinthe swash plate angle control unit sets the swash plate angle of the variable capacity pump and the swash plate angle of the variable capacity motor based on an output from the operation position detector, and controls the pump swash plate operation mechanism and the motor swash plate operation mechanism so that the swash plate angle of the variable capacity pump and the swash plate angle of the variable capacity motor become respective set swash plate angles, andwhen the swash plate angle of the variable capacity motor is changed based on the output from the operation position detector, the swash plate angle control unit controls the pump swash plate operation mechanism in such a manner that the swash plate angle of the variable capacity pump is changed with a control amount which is set so as to compensate an amount of change in a change gear ratio of the continuously variable transmission device caused along with the change of the swash plate angle of the variable capacity motor.
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Accused Products
Abstract
A speed change system for work vehicle having a continuously variable transmission device selects a first change gear ratio which is set larger than a smallest change gear ratio, when an engine rotational speed is a first set rotational speed which is set equal or close to an idling rotational speed of an engine; retains the change gear ratio of the continuously variable transmission device at the smallest change gear ratio, when the engine rotational speed is equal to or above a second set rotational speed set on a high-speed side relative to the first set rotational speed; and makes the change gear ratio of the continuously variable transmission device larger between the first change gear ratio and the smallest change gear ratio, as the engine rotational speed at that moment becomes lower, when the engine rotational speed is between the first and second set rotational speeds.
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Citations
22 Claims
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1. A speed change system for a work vehicle having a continuously variable transmission device comprising:
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a pump swash plate operation mechanism configured to operate a swash plate of a variable capacity pump for the continuously variable transmission device; a motor swash plate operation mechanism configured to operate a swash plate of a variable capacity motor for the continuously variable transmission device; a swash plate angle control unit configured to non-stepwise adjust a swash plate angle of the variable capacity pump through the pump swash plate operation mechanism and stepwise adjust a swash plate angle of the variable capacity motor through the motor swash plate operation mechanism; and an operation position detector configured to detect an operation position of a speed change operation tool; wherein the swash plate angle control unit sets the swash plate angle of the variable capacity pump and the swash plate angle of the variable capacity motor based on an output from the operation position detector, and controls the pump swash plate operation mechanism and the motor swash plate operation mechanism so that the swash plate angle of the variable capacity pump and the swash plate angle of the variable capacity motor become respective set swash plate angles, and when the swash plate angle of the variable capacity motor is changed based on the output from the operation position detector, the swash plate angle control unit controls the pump swash plate operation mechanism in such a manner that the swash plate angle of the variable capacity pump is changed with a control amount which is set so as to compensate an amount of change in a change gear ratio of the continuously variable transmission device caused along with the change of the swash plate angle of the variable capacity motor. - View Dependent Claims (2, 3, 4, 5)
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6. A speed change system for a work vehicle having a continuously variable transmission device comprising:
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an engine rotational speed detector configured to detect an engine rotational speed; and a vehicle speed control unit configured to control a change gear ratio of the continuously variable transmission device; wherein the vehicle speed control unit controls the change gear ratio with a process comprising; (a) when the engine rotational speed is a first set rotational speed which is set to a rotational speed equal or close to an idling rotational speed of an engine, selecting a first change gear ratio which is set to a change gear ratio larger than a smallest change gear ratio as the change gear ratio of the continuously variable transmission device; (b) when the engine rotational speed is a rotational speed which is equal to or above a second set rotational speed which is set on a high-speed side relative to the first set rotational speed, retaining the change gear ratio of the continuously variable transmission device at the smallest change gear ratio; and (c) when the engine rotational speed is a rotational speed between the first set rotational speed and the second set rotational speed, making the change gear ratio of the continuously variable transmission device larger between the first change gear ratio and the smallest change gear ratio, as the engine rotational speed at that moment becomes low. - View Dependent Claims (7, 8, 9, 10, 11)
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12. A speed change system for a work vehicle having a continuously variable transmission device comprising:
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an engine rotational speed detector configured to detect an engine rotational speed; a vehicle speed control unit configured to control a change gear ratio of the continuously variable transmission device; and a vehicle speed detector configured to detect a vehicle speed; wherein the vehicle speed control unit computes a control target vehicle speed based on the detected engine rotational speed and a change gear ratio which is set for the continuously variable transmission device, and controls the change gear ratio of the continuously variable transmission device so that the detected vehicle speed matches the control target vehicle speed. - View Dependent Claims (13, 14, 15)
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16. A speed change system for a work vehicle having a continuously variable transmission device comprising:
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a computing unit configured to compute a rated vehicle speed obtained when an engine rotational speed reaches a rated rotational speed of an engine, based on the rated rotational speed and a change gear ratio set for the continuously variable transmission device; a display device comprising;
a vehicle speed display part configured to display information regarding a vehicle speed; and
a speed change step display part for variable speed change configured to display with characters without unit the rated vehicle speed output by the computing unit as a speed change step of the continuously variable transmission device; anda display control unit configured to control the display device. - View Dependent Claims (17, 18, 19, 20, 21, 22)
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Specification