Automatic Transmission Shift Control via Torque-Based Strategy
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Solution Overview
Problem
Existing automatic transmission systems face challenges in preventing shock while maintaining shift response, particularly when shifting gears under high drive force conditions, leading to reduced drivability.
Innovation Solution
A control apparatus and method that selectively execute clutch-to-clutch shift or rotation synchronization shift based on output shaft torque, with the region for rotation synchronization shift being lower in torque than clutch-to-clutch shift, allowing emphasis on shock or shift speed based on torque conditions, and adjusting thresholds based on vehicle speed, accelerator depression, and gear to optimize shift control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the hydraulic pressure of the engagement device is reduced quickly to improve shift response, then shift speed is improved, but output shaft torque is reduced and drivability deteriorates
Solution Approach 1:
The system dynamically adjusts the shift control strategy based on real-time driving conditions. When accelerator depression rate is high, the system selects clutch-to-clutch shift with gentle pressure reduction to maintain torque. When accelerator depression rate is low, the system selects rotation synchronization shift with quick pressure reduction for fast response. This dynamic adaptation resolves the contradiction between shift speed and output shaft torque.
Solution Approach 2:
The system changes the control parameters (hydraulic pressure reduction rate, shift type selection) based on the accelerator depression rate and driving conditions. By adjusting these parameters dynamically, the system achieves fast shift response when appropriate while preventing excessive torque reduction, thus resolving the contradiction between shift speed and power output.
2Speed
If the hydraulic pressure of the engagement device is reduced quickly to improve shift response, then shift response is improved, but shock increases and drivability deteriorates
Solution Approach 1:
The system dynamically selects between two shift control strategies based on real-time conditions. High accelerator depression rate triggers clutch-to-clutch shift with gradual pressure reduction to minimize shock. Low accelerator depression rate allows rotation synchronization shift with quick pressure reduction for fast response. This dynamic selection resolves the contradiction between shift response and shift shock.
Solution Approach 2:
The system applies preliminary anti-action by selecting the appropriate shift control strategy before the shift occurs. When high accelerator depression is detected, the system prepares for clutch-to-clutch shift with gentle pressure control to prevent shock. This advance preparation based on driver intent resolves the contradiction between fast response and shock prevention.
3Ease of operation
If the depression speed of the accelerator pedal is used to determine shift control, then shift feeling in response to driver will is achieved, but output shaft torque is reduced under high drive force conditions
Solution Approach 1:
The system dynamically adjusts shift control based on accelerator depression rate. When depression rate is high (indicating driver demand for speed), the system selects clutch-to-clutch shift with gentle pressure reduction to maintain output shaft torque. When depression rate is low (indicating comfort-oriented driving), the system selects rotation synchronization shift for fast response. This dynamic adjustment maintains both shift feeling and torque output.
Data Source
AI summary
In a downshift of an automatic transmission in a state where an accelerator pedal is depressed, one of a clutch-to-clutch shift in which the shift is carried out by gradually reducing an engagement pressure of a clutch or a brake to be disengaged in the shift and a rotation synchronization shift in which the shift is carried out by reducing the engagement pressure of the clutch or the brake more quickly than in the clutch-to-clutch shift is selected based on an output shaft torque of the automatic transmission, a region where the rotation synchronization shift is selected is lower in output shaft torque than a region where the clutch-to-clutch shift is selected, and hence it is possible to appropriately selectively execute a shift placing emphasis on a shock and a shift placing emphasis on a shift speed in accordance with the output shaft torque.