Speed ratio control device and method for working vehicle
First Claim
1. A speed ratio control device for a working vehicle that uses an output of an internal combustion engine as a working power and a traveling power, and comprises an accelerator pedal that increases a rotation speed of the internal combustion engine when depressed and a transmission that shifts a rotation of the internal combustion engine and applies the shifted rotation to the traveling power, comprising:
- a programmable controller programmed to;
calculate a first target vehicle speed according to the rotation speed of the internal combustion engine;
calculate a second target vehicle speed according to a depression amount of the accelerator pedal;
vary the speed ratio of the transmission to achieve the first target vehicle speed when the first target vehicle speed is lower than the second target vehicle speed; and
vary the speed ratio of the transmission to achieve the second target vehicle speed when the first target vehicle speed is not lower than the second target vehicle speed.
2 Assignments
0 Petitions
Accused Products
Abstract
A working vehicle that uses the output of an internal combustion engine (30) as a working power and a traveling power includes an accelerator pedal (1) that increases a rotation speed of the engine (30) when depressed and a transmission (40) that shifts a rotation of the engine (30) and applies the shifted rotation to the traveling power. A speed ratio control device of the transmission (40) calculates a first target vehicle speed (Wne) according to the rotation speed of the engine (30), calculates a second target vehicle speed (Wu) according to a depression amount of the accelerator pedal (1), and controls the speed ratio of the transmission (40) on the basis of the smaller of these target vehicle speeds. As a result, a vehicle speed according to the depression amount of the traveling accelerator pedal (1) is obtained even when the internal combustion engine (30) rotates at high speed.
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Citations
9 Claims
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1. A speed ratio control device for a working vehicle that uses an output of an internal combustion engine as a working power and a traveling power, and comprises an accelerator pedal that increases a rotation speed of the internal combustion engine when depressed and a transmission that shifts a rotation of the internal combustion engine and applies the shifted rotation to the traveling power, comprising:
a programmable controller programmed to; calculate a first target vehicle speed according to the rotation speed of the internal combustion engine; calculate a second target vehicle speed according to a depression amount of the accelerator pedal; vary the speed ratio of the transmission to achieve the first target vehicle speed when the first target vehicle speed is lower than the second target vehicle speed; and vary the speed ratio of the transmission to achieve the second target vehicle speed when the first target vehicle speed is not lower than the second target vehicle speed. - View Dependent Claims (2, 3, 6, 7, 8)
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4. A speed ratio control device for a working vehicle that uses an output of an internal combustion engine as a working power and a traveling power, and comprises an accelerator pedal that increases a rotation speed of the internal combustion engine when depressed, a transmission constituted by a hydrostatic transmission combining a variable capacity hydraulic pump and a variable capacity hydraulic motor to shift a rotation of the internal combustion engine and applies the shifted rotation to the traveling power, and an inching pedal that applies braking to the working vehicle when depressed beyond a fixed amount, the device comprising:
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a programmable controller programmed to; calculate a first target vehicle speed according to the rotation speed of the internal combustion engine; calculate a second target vehicle speed according to a depression amount of the accelerator pedal; vary the speed ratio of the transmission to achieve the first target vehicle speed when the first target vehicle speed is lower than the second target vehicle speed; and vary the speed ratio of the transmission to achieve the second target vehicle speed when the first target vehicle speed is not lower than the second target vehicle speed; wherein the controller is further programmed to; set the smaller of the first target vehicle speed and the second target vehicle speed as a vehicle speed command basic value; calculate a final vehicle speed command value by reducing the vehicle speed command basic value in accordance with a depression amount of the inching pedal; and vary the speed ratio of the transmission such that the final vehicle speed command value is realized. - View Dependent Claims (5)
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9. A speed ratio control method for a working vehicle that uses an output of an internal combustion engine as a working power and a traveling power, and comprises an accelerator pedal that increases a rotation speed of the internal combustion engine when operated and a transmission that shifts a rotation of the internal combustion engine and applies the shifted rotation to the traveling power, comprising:
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using a calculating and modifying device to calculate a first target vehicle speed according to the rotation speed of the internal combustion engine; using the calculating and modifying device to calculate a second target vehicle speed according to a depression amount of the accelerator pedal; varying a speed ratio of the transmission to achieve the first target vehicle speed when the first target vehicle speed is lower than the second target vehicle speed; and varying the speed ratio of the transmission to achieve the second target vehicle speed when the first target vehicle speed is not lower than the second target vehicle speed.
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Specification