Work Vehicle Transmission Control for Low-Shift-Shock Gear Switching
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Solution Overview
Problem
The existing systems for work vehicles with hydrostatic and planetary transmissions experience significant shift shock due to the time required to switch transmission gears while traveling, as hydraulic fluid charging for the next gear engagement occurs after reaching the switching point, prolonging the gear change process.
Innovation Solution
A control system that estimates the time required for the rotational speed ratio to reach a switching point and initiates hydraulic fluid charging before reaching that point, allowing for earlier engagement of the clutch for the next gear, thereby reducing the time needed for gear switching and minimizing shift shock.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If hydraulic fluid charging is performed after reaching the switching point, then the gear switching is completed accurately at the intended point, but the gear switching time is prolonged causing significant shift shock
Solution Approach 1:
The control unit starts hydraulic fluid charging to the clutch mechanism before the transmission gear reaches the switching point. By calculating the required charging time and initiating the action in advance, the gear switching is completed exactly at the switching point without delay, thereby reducing shift shock while maintaining switching accuracy.
2Loss of time
If hydraulic fluid charging is started earlier, then the gear switching time is reduced minimizing shift shock, but the gear switching may occur at the incorrect point
Solution Approach 1:
The control unit continuously monitors the transmission gear position and dynamically adjusts the timing of hydraulic fluid charging based on real-time feedback. By calculating the remaining distance to the switching point and the required charging time, the system initiates charging at the precise moment that ensures completion exactly at the switching point, maintaining both speed and accuracy.
3Stability of the object's composition
If the clutch engagement is delayed until reaching the switching point, then the gear ratio changes smoothly, but the overall transmission response time increases
Solution Approach 1:
The system prepares the clutch mechanism for engagement by charging hydraulic fluid in advance before the switching point is reached. This preliminary action reduces the actual engagement time when switching occurs, thereby improving transmission response speed while maintaining smooth gear ratio changes through controlled clutch engagement.
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
This approach enables quick and smooth gear transitions, reducing the perceived shift shock for the user by completing gear changes in a shorter time frame.
Implementation Method 1
a hydrostatic transmission (28) including a hydraulic pump (P) to which rotation generated by an internal combustion engine (102) is transmitted to discharge hydraulic fluid in accordance with an angle of a swash plate (49) and a hydraulic motor (M) to which the hydraulic fluid is supplied from the hydraulic pump (P) to generate rotation
Implementation Method 2
a hydraulic clutch mechanism (29) to switch a transmission gear of the planetary transmission (31)
Data Source
AI summary
A control system to control an operation of a power transmission of a work vehicle includes a storage to store data indicating a relationship between a ratio between a rotational speed of a predetermined component on a power transmission path to transmit the rotation of the planetary transmission to wheels and a rotational speed of the internal combustion engine, and switching points at which the transmission gear of the planetary transmission is switched, and a controller to control the hydraulic clutch mechanism 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 hydraulic fluid charging to perform switching of the transmission gear before the ratio reaches the first value.