Automatic Engine Restart for Transmission Fluid Pressurization
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Solution Overview
Problem
When a vehicle's engine is automatically stopped while the transmission is engaged in park, it takes longer to restart the engine and transfer torque to the wheels due to the need for increased transmission fluid pressure, delaying vehicle launch.
Innovation Solution
Automatically starting the engine in response to the brake pedal application before shifting from park to drive, allowing the transmission fluid pump to increase pressure and reduce the time needed to engage gear clutches.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the engine is automatically stopped while the transmission is engaged in park, then fuel is conserved during idle time, but significantly more transmission fluid must be delivered to the gear clutches after engine restart, delaying vehicle launch
Solution Approach 1:
The system detects brake pedal application as a preliminary action indicating the driver's intent to launch the vehicle. In response, the controller automatically restarts the engine before the transmission is shifted out of park, allowing the transmission fluid pump to begin pressurizing fluid in advance. This preliminary engine restart and fluid pressurization reduces the delay when torque is needed, resolving the contradiction between fuel conservation during idle and quick launch response.
2Speed
If the engine is automatically restarted after stopping, then the vehicle can quickly respond to driver input, but significantly more transmission fluid must be supplied to engage gear clutches, delaying torque transfer to wheels
Solution Approach 1:
The system uses feedback from the brake pedal position sensor to detect driver intent. When the brake pedal is applied, the controller receives this feedback signal and automatically restarts the engine, which in turn activates the transmission fluid pump. This feedback-based control ensures the transmission fluid is pressurized in advance, reducing the delay between engine restart and torque transfer to the wheels, thus resolving the contradiction between quick engine restart response and torque transfer timing.
3Ease of operation
If the transmission is engaged in park, then all gear clutches must be released to allow vehicle movement, but this requires significantly more transmission fluid to be supplied, delaying engine torque availability to wheels
Solution Approach 1:
The system performs preliminary action by detecting brake pedal application and automatically restarting the engine before the driver shifts the transmission out of park. This causes the transmission fluid pump to begin pressurizing fluid in advance, so that when the transmission is shifted and gear clutches need to engage, the fluid is already available under pressure. This resolves the contradiction between the ease of transmission engagement and the time required to pressurize sufficient fluid for 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 reduces the time between shifting into drive and the availability of engine torque at the wheels, improving vehicle launch efficiency by pre-pressurizing the transmission fluid before gear engagement.
Implementation Method 1
significantly more transmission fluid may have to be delivered to the gear clutches before engine torque may be transferred to the vehicle's wheels
Data Source
AI summary
Systems and methods for operating an engine that may be automatically stopped and started responsive to vehicle operating conditions are disclosed. In one example, the engine may be automatically started after it has been automatically stopped in response to a driver applying a brake pedal while the vehicle's transmission is engaged in park. The engine may be started to increase transmission pump pressure prior to engaging a gear to reduce vehicle launch time.