Planetary Transmission Shift Control With Pre-Charging Timing
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Solution Overview
Problem
The existing control systems for work vehicles with planetary transmission devices experience significant shift shock due to the time required to switch transmission gears while the vehicle is traveling, as the gear switching process takes longer than necessary.
Innovation Solution
A control system that includes a storage device storing data on the relationship between rotational speeds and switching points, and a controller that estimates the time required for the ratio to reach a switching point, allowing oil charging to start before the ratio reaches the switching point, thereby reducing the time needed for gear switching and minimizing shift shock.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the hydraulic clutch mechanism waits until the ratio reaches the switching point to start oil charging, then the gear switching occurs at the correct timing, but the switching time is prolonged causing significant shift shock
Solution Approach 1:
The controller starts oil charging to the hydraulic clutch mechanism before the transmission gear ratio reaches the switching point. By estimating the time required for oil charging and clutch engagement, the system initiates the oil supply in advance, ensuring the clutch is ready to engage exactly when the ratio reaches the switching point, thereby reducing shift shock and switching duration.
2Loss of time
If the oil charging is started earlier to reduce switching time, then the gear switching becomes faster, but the switching timing precision may be compromised
Solution Approach 1:
The controller continuously monitors the transmission gear ratio and compares it with the switching point. Based on this feedback, the controller estimates the time required for oil charging and dynamically adjusts the timing to start oil charging, ensuring both speed and precision in gear switching.
3Productivity
If the hydraulic clutch mechanism engages quickly, then the productivity increases, but the shift shock increases affecting user comfort
Solution Approach 1:
The system performs preliminary oil charging to the hydraulic clutch mechanism before the gear ratio reaches the switching point. This advance preparation ensures that the clutch is ready to engage smoothly and quickly when the switching point is reached, thereby increasing productivity while minimizing shift shock and improving user comfort.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution enables quick and smooth gear switching, reducing the time required to change ratios and minimizing the shift shock felt by the user, enhancing the operational efficiency and comfort of the work vehicle.
Implementation Method 1
a hydrostatic transmission device including a hydraulic pump to which rotation generated by an internal combustion engine is transmitted to thereby discharge oil in accordance with an angle of a swash plate, and a hydraulic motor to which the oil is supplied from the hydraulic pump to thereby generate rotation
Implementation Method 2
a hydraulic clutch mechanism to switch the transmission gear of the planetary transmission device
Data Source
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AI summary
A control system controls an operation of a power transmission device of a work vehicle. The control system includes: a storage device to store data indicating a relationship between a ratio between a rotational speed of a predetermined component on a power transmission path for transmitting the rotation of the planetary transmission device to wheels and a rotational speed of the internal combustion engine, and a plurality of switching points, which are points at which the transmission gear of the planetary transmission device is switched; and a controller to control the hydraulic clutch mechanism so as to perform switching of the transmission gear. Where the transmission gear is switched when the ratio changes to reach a first value corresponding to a first switching point or after the ratio reaches the first value, the controller controls the hydraulic clutch mechanism so as to start oil charging for performing switching of the transmission gear before the ratio reaches the first value.