Lockup Clutch Control for Torque Shock Prevention
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Solution Overview
Problem
During coast running, unintentional depression of the accelerator pedal can cause discomfort due to changes in vehicle travel speed, as the lockup clutch does not disengage promptly, leading to torque shocks when fuel recovery occurs.
Innovation Solution
A vehicle driving device with an internal combustion engine, torque converter, and lockup clutch, equipped with an accelerator pedal depression sensor and programmable controller, which delays fuel recovery until the lockup clutch's engaging pressure decreases to a predetermined level, thereby preventing torque shocks and maintaining consistent vehicle speed.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the lockup clutch is engaged during coast running to improve fuel economy, then fuel consumption is reduced through fuel cut, but torque shocks occur when fuel recovery and clutch disengagement timing differ
Solution Approach 1:
The controller performs preliminary action by detecting accelerator pedal depression before fuel recovery occurs, and proactively suppresses fuel recovery until the lockup clutch disengages. This prevents the timing mismatch between fuel recovery and clutch disengagement that causes torque shocks, while maintaining fuel cut benefits during genuine coast running.
Solution Approach 2:
The system uses feedback from the accelerator pedal depression sensor to continuously monitor driver input during coast running. When minute depression is detected, the controller adjusts fuel supply timing based on the lockup clutch engagement state, creating a closed-loop control that prevents torque shocks while maintaining fuel efficiency.
2Loss of energy
If the lockup clutch remains engaged during minute accelerator pedal depression to maintain fuel cut benefits, then fuel economy is improved, but vehicle speed changes cause driver discomfort
Solution Approach 1:
The controller performs preliminary detection of accelerator pedal depression and suppresses fuel recovery in advance, before the engine speed increases significantly. This prevents the transmission of speed changes to the drive wheels during lockup clutch engagement, eliminating driver discomfort while preserving fuel cut benefits during genuine coast running.
Solution Approach 2:
The system applies preliminary anti-action by suppressing fuel recovery when minute accelerator pedal depression is detected during lockup clutch engagement. This counteracts the potential harmful effect of engine speed increases being transmitted to the drive wheels, preventing vehicle speed fluctuations that would cause driver discomfort.
3Speed
If fuel recovery is performed immediately when rotation speed decreases during coast running, then engine responsiveness is improved, but torque shocks occur due to timing difference with lockup clutch disengagement
Solution Approach 1:
The controller uses feedback from the lockup clutch engagement state and accelerator pedal position to intelligently control fuel recovery timing. During lockup clutch engagement, fuel recovery is suppressed until the clutch disengages or significant accelerator depression is detected, preventing torque shocks while maintaining engine responsiveness for genuine acceleration requests.
Solution Approach 2:
The system dynamically adjusts fuel recovery timing based on operating conditions. During lockup clutch engagement with minute accelerator depression, fuel recovery is suppressed. However, when significant accelerator depression is detected or the lockup clutch disengages, fuel recovery is permitted, maintaining engine responsiveness while preventing torque shocks.
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 alleviates the influence of minor accelerator pedal depression on vehicle speed, preventing discomfort by ensuring smooth fuel recovery and disengagement of the lockup clutch, thus maintaining consistent acceleration and reducing torque shocks.
Implementation Method 1
an internal combustion engine generating an output power by combustion of fuel supplied in response to a depression of an accelerator pedal
Implementation Method 2
a torque converter that transmits the output power of the internal combustion engine to a drive wheel of the vehicle
Implementation Method 3
a lockup clutch that is engaged, when the vehicle performs the coast running, to lock up the torque converter
Data Source
Figure 1
Figure 2
Figure 3A~3F
AI summary
An output power of the internal combustion engine (1) is transmitted to a drive wheel via a torque converter (2B) having a pump impeller and a turbine runner. A lockup clutch (2C) directly connects the pump impeller and the turbine runner during a coast running of a vehicle. When the accelerator pedal is slightly depressed during a coast running of a vehicle in a fuel cut-off state, the lockup clutch (2C) disengages. In addition, fuel recovery of the internal combustion engine (1) is suppressed until the engaging pressure of the lockup clutch (2C) decreases, thereby preventing a vehicle speed change caused by an output power increase of the internal combustion engine (1) before the lockup clutch (2C) substantially disengages.