Downshift Input Shaft Speed Control for Smoother Acceleration
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Solution Overview
Problem
Conventional shift control systems experience shift shock during accelerator stepping-in downshift due to excessive correction of target input shaft rotation speed, leading to vehicle slowdown and clutch engagement overshooting.
Innovation Solution
A shift control method that determines the presence of accelerating intention during downshifts, adjusting the target input shaft rotation speed by either increasing or decreasing the basic target synchronization speed to prevent shift shock, using a criterion region defined by accelerator pedal operation and vehicle speed.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the target input shaft rotation speed is increasingly corrected during accelerator stepping-in downshift, then the vehicle acceleration is improved, but the input shaft rotation speed may exceed the final target value causing shift shock
Solution Approach 1:
The patent applies dynamics by making the correction amount adaptive rather than fixed. The correction amount is dynamically adjusted based on the relationship between the basic target synchronization speed and the actual input shaft rotation speed. When the basic target synchronization speed is lower than the actual rotation speed, the correction amount is reduced or set to zero, preventing overshooting. This dynamic adjustment resolves the contradiction between maintaining acceleration performance and preventing shift shock.
Solution Approach 2:
The patent implements feedback control by continuously monitoring the actual input shaft rotation speed and comparing it with the basic target synchronization speed. The correction amount is determined based on this feedback information. When the actual rotation speed exceeds the basic target synchronization speed, the feedback mechanism reduces the correction amount to prevent further overshooting, thereby suppressing shift shock while maintaining appropriate acceleration response.
2Productivity
If the basic target synchronization speed is increasingly corrected to assume vehicle acceleration, then the acceleration response is improved, but the input shaft rotation speed overshoots the final target value
Solution Approach 1:
The correction amount is dynamically adjusted based on real-time conditions rather than applying a fixed increasing correction. The system monitors whether the basic target synchronization speed is lower than the actual input shaft rotation speed and adjusts the correction amount accordingly. This dynamic approach maintains responsive acceleration while preventing rotation speed overshooting, resolving the contradiction between acceleration response and control precision.
Solution Approach 2:
The patent applies preliminary anti-action by anticipating potential overshooting before it occurs. When the basic target synchronization speed is determined to be lower than the actual input shaft rotation speed, the system preemptively reduces or eliminates the correction amount. This preliminary adjustment prevents the rotation speed from exceeding the final target value, thereby maintaining both acceleration response and control precision.
3Power
If correction is applied to the basic target synchronization speed, then the accelerating performance is improved, but the shift smoothness deteriorates due to overshooting
Solution Approach 1:
The patent resolves the contradiction between accelerating performance and shift smoothness by dynamically adjusting the correction amount based on actual operating conditions. The correction is applied only when appropriate, and reduced or eliminated when the basic target synchronization speed falls below the actual input shaft rotation speed. This prevents overshooting and shift shock while maintaining effective accelerating performance.
Solution Approach 2:
The feedback mechanism monitors the relationship between basic target synchronization speed and actual input shaft rotation speed to determine the appropriate correction amount. When feedback indicates that the basic target synchronization speed is lower than the actual rotation speed, the correction is reduced to prevent overshooting and shift shock. This feedback-controlled approach maintains accelerating performance while ensuring shift smoothness.
Data Source
AI summary
The present invention provides a shift control method include: setting a basic target synchronization rotation speed that is a basic target value of the input shaft rotation speed during the shift; determining whether or not an accelerating intention is present when the shift is a downshift with a driving force requirement to the vehicle; when the accelerating intention is present, setting a first target input shaft rotation speed as the target input shaft rotation speed, the first target input shaft rotation speed being obtained by increasingly correcting the basic target synchronization rotation speed; and when the accelerating intention is not present, setting a second target input shaft rotation speed as the target input shaft rotation speed, the second target input shaft rotation speed being obtained by maintaining or decreasingly correcting the basic target synchronization rotation speed.