Dual-Clutch Transmission Lubrication Pump Speed Control
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Solution Overview
Problem
Dual-clutch transmission (DCT) lubrication pumps are often operated at higher speeds than necessary, leading to energy waste, and existing solutions like electrically driven pumps increase weight, cost, and introduce durability and reliability issues.
Innovation Solution
An electronic control unit is used to register the operational state of the clutches and lubrication pump, allowing the pump to be driven by partly engaging the inactive clutch unit, enabling variable or intermittent operation to match lubrication requirements, reducing pump speed and energy consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the lubrication pump is mechanically driven by the engaged clutch at prime mover speed, then the pump receives sufficient lubrication pressure, but the pump operates at higher speed than necessary causing energy waste
Solution Approach 1:
The clutch is controlled to dynamically adjust its engagement state, transitioning from fully engaged (for power transmission) to partially engaged (for pump drive only). This dynamic control allows the pump to receive mechanical drive at reduced speed when power transmission is not needed, reducing energy waste while maintaining lubrication reliability through electronic monitoring of pump operation.
2Speed
If an electrically driven lubrication pump is used, then the pump speed can be controlled independently of prime mover speed, but additional weight and cost are introduced along with durability and reliability issues
Solution Approach 1:
Instead of replacing the mechanical pump drive system with an electrical motor (which would improve speed control but add weight and reliability concerns), the invention substitutes electrical control of the existing mechanical clutch system. The ECU electronically controls the clutch actuator to achieve partial engagement, providing variable speed control to the mechanically driven pump without introducing additional motors or complex electrical drive systems.
3Reliability
If the first clutch unit is fully engaged to drive the lubrication pump, then the pump operates at sufficient speed for lubrication, but power transmission to the driving wheels is interrupted
Solution Approach 1:
The clutch is engaged only partially (rather than fully) to drive the lubrication pump. This partial engagement provides sufficient mechanical torque to rotate the pump at adequate speed for lubrication, while maintaining enough engagement force to continue transmitting power to the driving wheels. The ECU controls the actuator to achieve this optimal partial engagement state, balancing lubrication adequacy with power transmission continuity.
Data Source
Figure 1
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Figure 4
AI summary
The invention relates to a vehicle transmission in a vehicle which comprises at least one prime mover, e.g., an internal combustion engine and/or an electric motor. The transmission comprises a first transmission mechanism arranged to transmit mechanical driving power from an output shaft (20; 30; 40) of the prime mover to a first input shaft (25; 31; 41) and to put any one of a first set of gears in an engaged state to drivingly connect the first input shaft (25; 31; 41) to the driving wheels; and a second transmission mechanism arranged to transmit mechanical driving power from the output shaft (20; 30; 40) of the prime mover to a second input shaft (26; 32; 42) and to put any one of a second set of gears in an engaged state to drivingly connect the second input shaft (26; 32; 42) to the driving wheels. Controllable first and second clutch unit (22; C2)s are arranged to bring the output shaft (20; 30; 40) of the prime mover and the first and the input shaft, respectively, into engagement with each other. A lubrication pump (36; 46) is drivingly connected to the first input shaft (25; 31; 41) to lubricate the transmission and an electronic control unit (15) is arranged to determine a lubricated state of the transmission and the operational state of the lubrication pump (36; 46). When the first clutch unit (21; C1) is engaged to connect the output shaft (20; 30; 40) of the prime mover to the first input shaft (25; 31; 41), the lubrication pump (36; 46) is driven by the first input shaft (25; 31; 41). When the second clutch unit (22; C2) is engaged to connect the output shaft (20; 30; 40) of the prime mover to the second input shaft (26; 32; 42), the lubrication pump (36; 46) is arranged to be driven by the first input shaft (25; 31; 41) by at least partly engaging the first clutch unit (21; C1).