Torque Converter Pressure Control During Lock-Up Clutch Engagement
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Solution Overview
Problem
The internal pressure of a torque converter increases when the lock-up clutch is engaged, leading to increased loss of horsepower in the hydraulic pump due to the need to maintain high discharge pressure.
Innovation Solution
A power transmission device comprising a torque converter device, hydraulic pumps, oil channels, pressure control valves, and a controller that adjusts the pressure control valves to manage the internal pressure of the torque converter, reducing it when the lock-up clutch is engaged and maintaining it at a constant pressure when disengaged, thereby minimizing horsepower loss.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the lock-up clutch is engaged to transmit power directly, then power transmission efficiency is improved, but the internal pressure of the torque converter increases causing horsepower loss in the hydraulic pump
Solution Approach 1:
The pressure control valve dynamically adjusts the internal pressure of the torque converter based on the engagement state of the lock-up clutch. When the lock-up clutch is engaged, the valve opens to reduce pressure; when disengaged, it closes to maintain pressure. This dynamic adjustment resolves the contradiction by adapting the pressure level to the current operational mode, eliminating unnecessary horsepower loss during direct power transmission while maintaining proper pressure during torque converter operation.
Solution Approach 2:
The system changes the pressure parameter of the torque converter based on the lock-up clutch state. By controlling the pressure control valve to open when the lock-up clutch is engaged, the internal pressure is reduced from a high constant level to a lower level, directly addressing the horsepower loss issue while maintaining the benefits of lock-up clutch engagement.
2Reliability
If the discharge pressure of the hydraulic pump is maintained at a high level, then the torque converter internal pressure is sufficient, but horsepower loss in the hydraulic pump increases
Solution Approach 1:
The pressure control valve provides dynamic pressure regulation within the torque converter, allowing the system to maintain sufficient pressure for reliable operation only when needed (when lock-up clutch is disengaged). When the lock-up clutch is engaged, the valve opens to reduce pressure, eliminating the continuous high-pressure maintenance that causes horsepower loss while ensuring reliability is maintained during torque converter operation.
Solution Approach 2:
The pressure control valve extracts the excess pressure from the torque converter when the lock-up clutch is engaged, separating the pressure maintenance function from the power transmission mode. This allows the hydraulic pump to operate at lower pressure during lock-up clutch engagement, reducing horsepower loss while maintaining adequate pressure during torque converter operation through the valve's selective pressure regulation.
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 effectively suppresses horsepower loss in the hydraulic pump by regulating the internal pressure of the torque converter, ensuring efficient power transmission while maintaining optimal lubrication and pressure levels.
Implementation Method 1
The controller causes the pressure control valve to open and close. The controller sets the pressure control valve to an open state when the lock-up clutch is in an engaged state.
Implementation Method 2
The first oil channel supplies hydraulic fluid from the first hydraulic pump to the torque converter. The second oil channel drains hydraulic fluid from the torque converter.
Implementation Method 3
The torque converter device includes a torque converter and a lock-up clutch and transmits power from the power source to the travel device.
Data Source
AI summary
A power transmission device includes a torque converter device, a first hydraulic pump, a first oil channel, a second oil channel, a third oil channel, a second pressure control valve, and a controller. The torque converter device has a torque converter and a lock-up clutch. The first oil channel supplies hydraulic fluid from the first hydraulic pump to the torque converter. The second oil channel drains hydraulic fluid from the torque converter. The third oil channel communicates with the first oil channel and the second oil channel. The second pressure control valve is disposed in the third oil channel. The controller sets the second pressure control valve to an open state when the lock-up clutch is in an engaged state.