Hydraulic Clutch Pre-fill for Engine Torque Delay
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Solution Overview
Problem
In vehicles with internal combustion engines and stop/start capability, there is a delay in transmitting engine torque to the drive wheels due to the time required for the hydraulically-actuated clutch and damper to fill with fluid, which affects the responsiveness of the powertrain when restarting the engine.
Innovation Solution
A method and system that anticipates an imminent engine start by determining the likelihood of torque demand and pre-fills the hydraulically-actuated clutch and damper with fluid, reducing the time needed to commence torque transmission by using a controller to assess torque input and output data and compare it against predetermined threshold values.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the engine is shut off to reduce emissions and improve fuel efficiency, then emissions and fuel consumption are reduced, but the time required to commence torque transmission increases when the engine is restarted
Solution Approach 1:
The clutch is pre-filled with hydraulic fluid before the engine restart is initiated. The controller detects the engine stop condition and pre-fills the clutch actuator with hydraulic fluid, so that when the engine restarts and torque demand occurs, the clutch is already ready to engage immediately without waiting for fluid pressure buildup.
2Speed
If the clutch is pre-filled with fluid to reduce torque transmission delay, then responsiveness is improved, but the system complexity increases due to additional control mechanisms
Solution Approach 1:
The controller continuously monitors engine operating conditions, including stop/start status and torque demand signals from the accelerator pedal. Based on this feedback, the controller intelligently activates the pre-fill function only when appropriate (during engine stop conditions with anticipated restart), thereby reducing torque transmission delay without requiring constant pre-filling that would oversimplify the system.
Solution Approach 2:
The system performs preliminary action by pre-filling the clutch with hydraulic fluid during engine stop conditions before restart is needed. This preliminary preparation eliminates the delay in torque transmission when the engine restarts, improving responsiveness without requiring permanent modification to the clutch structure.
3Speed
If the pre-fill function is always active to ensure immediate torque transmission, then responsiveness is maximized, but energy waste increases due to unnecessary fluid pumping
Solution Approach 1:
Instead of continuous operation, the pre-fill function operates periodically or intermittently based on engine stop/start conditions. The controller activates the pre-fill pump only during engine stop conditions when a restart is anticipated, and deactivates it when the engine is running or no restart is expected, thereby reducing energy consumption while maintaining responsiveness when needed.
Solution Approach 2:
The controller uses feedback from engine operating conditions (stop/start status, torque demand) to intelligently control the pre-fill function. This feedback mechanism ensures the pre-fill operation occurs only when necessary, avoiding unnecessary energy consumption from continuous or inappropriate pre-filling while still achieving rapid torque transmission when the engine restarts.
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 required to transmit engine torque to the transmission, enhancing the responsiveness and efficiency of the powertrain by minimizing delays between the request for vehicle drive and actual torque application at the wheels.
Implementation Method 1
pre-filling with fluid a hydraulically-actuated clutch that is configured to connect the engine to the transmission
Implementation Method 2
pre-filling a hydraulically-actuated damper with fluid. The damper may be operatively connected to each of the engine and the transmission, and configured to preclude at least some vibrations of the engine from being transmitted to the transmission
Data Source
AI summary
A method controls an amount of time required to commence transmitting torque of an internal combustion engine equipped with a stop/start feature to a transmission configured to transmit the torque of the engine to drive-wheels in a vehicle. The method includes determining whether a start of the engine is likely. The method also includes pre-filling with fluid a hydraulically-actuated clutch that is configured to connect the engine to the transmission when the start of the engine is likely. Accordingly, the amount of time required to commence transmitting torque of the engine to the transmission is reduced. A system employs the method for controlling an amount of time required to commence transmitting torque of the engine.