Powertrain Control Apparatus Torque Phase Lag Reduction
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Solution Overview
Problem
Existing control methods for powertrain transmissions during shifts can generate shift shock due to torque fluctuations, particularly when friction apply elements wear out, leading to increased hydraulic pressure and delayed engine torque increase, which worsens torque phase lag and output torque fluctuations.
Innovation Solution
A control apparatus and method that adjusts hydraulic pressure to a preset standby pressure, corrected based on transmission state, to synchronize the timing and gradient of output torque increase during shifts, reducing torque phase lag and shift shock.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If hydraulic pressure is increased to compensate for worn friction apply elements, then the apply force is sufficient, but the torque phase starts earlier causing lag between torque phase start and engine torque increase
Solution Approach 1:
The control apparatus increases engine torque in advance before the torque phase actually starts. By detecting the start of the torque phase through hydraulic pressure changes and predicting the timing, the system pre-adjusts engine torque to match the upcoming torque phase, eliminating the lag between torque phase start and engine torque increase.
Solution Approach 2:
The system monitors hydraulic pressure changes to detect when the torque phase starts. This feedback information is used to adjust engine torque timing dynamically, ensuring that engine torque increases are synchronized with the actual torque phase timing rather than relying on fixed predetermined timings.
2Stability of the object's composition
If engine torque is increased during the torque phase, then output torque fluctuation is reduced, but shift shock occurs due to torque increase during the inertia phase
Solution Approach 1:
The control apparatus dynamically adjusts engine torque based on the current phase of the shift (torque phase or inertia phase). By continuously monitoring hydraulic pressure to determine phase timing, the system applies torque increase only during the torque phase and suppresses torque increase during the inertia phase, optimizing both stability and shock reduction.
Solution Approach 2:
The system changes the engine torque parameter selectively based on phase detection. During the torque phase, engine torque is increased to stabilize output torque. During the inertia phase, engine torque increase is suppressed to prevent shift shock. This parameter change is triggered by hydraulic pressure-based phase detection.
3Ease of operation
If predetermined timing for engine torque increase is used, then control is simple, but it cannot adapt to early torque phase start caused by increased hydraulic pressure
Solution Approach 1:
The system uses hydraulic pressure feedback to detect torque phase start timing and adjusts engine torque increase timing accordingly. This feedback mechanism allows the control system to adapt to varying conditions (such as worn friction elements requiring higher pressure) while maintaining relatively simple control logic based on pressure threshold detection.
Data Source
AI summary
Hydraulic pressure supplied to a first brake and a second brake in a transmission is controlled during an upshift such that the second brake releases from an applied state, and the first brake applies from a released state. The hydraulic pressure supplied to the first brake is increased to a standby pressure. When a period of time has passed after the upshift starts, the output torque of a powertrain is increased. The standby pressure is corrected according to a decrease rate of an input shaft rotation speed of the transmission during an inertia phase of the upshift. An ECU executes a program that includes the step of setting the period of time from the start of the upshift until the output torque of the powertrain starts to increase, according to the standby pressure.