Automatic Transmission Shift Control Device Torque Reduction Delay
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Solution Overview
Problem
The existing shift control technique for automatic transmissions in power transmission systems causes repeated gear shifts and uncomfortable feelings due to immediate up-shifts followed by down-shifts when the target deceleration becomes smaller and an acceleration request is generated shortly after, leading to a reduction in shift quality.
Innovation Solution
A shift control device with a torque-reduction-response-shift-request determining unit and a torque-reduction-response-shift delaying unit is implemented, which determines up-shift requests based on motor torque reduction and delays the execution of these requests by a set time, preventing immediate up-shifts and subsequent down-shifts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the automatic transmission is shifted up immediately when the target deceleration becomes smaller, then the transmission responds quickly to changing conditions, but repeated gear shifts occur causing shift shocks and reduced shift quality
Solution Approach 1:
The control device determines an up-shift request in advance when the target deceleration becomes smaller, but delays the actual execution of the shift until a set time has elapsed. This preliminary determination followed by delayed execution prevents immediate shifting that would cause repeated gear changes, while still being prepared to shift when needed.
Solution Approach 2:
The system dynamically adjusts the timing of shift execution based on current operating conditions. By introducing a time delay mechanism, the system makes the shift execution flexible rather than immediate, allowing it to adapt to changing acceleration requests and avoid repeated shifts while maintaining responsiveness when conditions stabilize.
2Force
If the automatic transmission is shifted down in response to acceleration requests, then the transmission provides adequate driving force, but repeated up-shifts and down-shifts occur in short time causing multiple shift shocks
Solution Approach 1:
The control device applies preliminary anti-action by delaying the execution of up-shift requests. This delay prevents the immediate up-shift that would subsequently require a down-shift when acceleration is requested, thereby preemptively avoiding the repeated gear shifts and associated shift shocks that would harm shift quality.
3Use of energy by moving object
If the shift control follows the shift pattern strictly based on motor torque, then the transmission operates efficiently, but repeated gear shifts occur when torque changes rapidly causing uncomfortable feelings
Solution Approach 1:
The control device determines up-shift requests in advance based on torque reduction, but delays execution by a set time. This preliminary determination maintains energy efficiency by following the shift pattern, while the delayed execution prevents repeated shifts that would cause uncomfortable feelings, thus resolving the contradiction between efficiency and comfort.
Data Source
AI summary
A target shift stage comes to a high speed stage at t2, during reduction toward zero of a motor torque by an accelerator pedal releasing operation from t1, and an up-shift shift request along with the torque reduction is generated. The shift request is executed for the first time at t3, and the automatic transmission is shifted up to a high speed stage from a current low speed stage selecting state. Therefore, even in the case that a request for increasing a motor regenerative torque is issued by a braking operation just after (t2 to t3) an up-shift shift request moment t2 in response to the torque reduction, the gear shift in response thereto is not generated, and it is possible to avoid generation of repeated gear shift of low speed stage→high speed stage→low speed stage for a short time.