Automatic Transmission Controller Surge Pressure Control
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Solution Overview
Problem
Automatic transmissions face challenges in smoothly performing multiple shifts that transitionally establish an intermediate speed position, leading to extended shift times and deteriorated drivability due to incomplete engagement of frictional elements during power-on downshifts.
Innovation Solution
A controller for automatic transmissions is designed with a surge hydraulic pressure control unit that adjusts hydraulic pressure to prevent complete engagement of frictional elements during intermediate speed position transitions, ensuring smoother shifts by setting lower surge hydraulic pressure for intermediate speed position engagements and higher pressure for required speed position engagements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If surge hydraulic pressure control is applied with equivalent pressure for intermediate speed position engaging element as for required speed position engaging element, then the intermediate speed position engaging element can be completely engaged, but the state where the intermediate speed position is established is temporarily held and the rate of change in input shaft rotation speed reduces, causing shift operation stagnation
Solution Approach 1:
The patent applies parameter changes by setting different surge hydraulic pressure values for intermediate speed position engaging elements compared to required speed position engaging elements. Specifically, the surge hydraulic pressure for intermediate speed position engaging elements is set to a value that prevents complete engagement, thereby avoiding shift operation stagnation while still achieving the desired speed position transitions efficiently.
2Speed
If surge hydraulic pressure is increased to improve response of engaging frictional engagement element, then response time is reduced, but complete engagement of intermediate speed position engaging element causes shift operation stagnation
Solution Approach 1:
The patent resolves this contradiction by changing the surge hydraulic pressure parameter based on the type of engaging element. For intermediate speed position engaging elements, a lower surge hydraulic pressure is applied to achieve partial engagement and maintain response speed without causing complete engagement stagnation. For required speed position engaging elements, higher surge hydraulic pressure is applied to ensure complete engagement and fast response.
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
This configuration enables smooth performance of multiple shifts, prevents reduction in input shaft rotation speed, and suppresses drivability issues by ensuring timely and complete engagement of frictional elements during downshifts.
Implementation Method 1
control a surge hydraulic pressure that is supplied to each engaging frictional engagement element in order to increase response of the engaging frictional engagement element
Data Source
AI summary
When there is a request for a skip downshift that transitionally establishes an intermediate speed position, a surge hydraulic pressure at the start of a torque phase during shift control toward the intermediate speed position is set so as to be lower than a surge hydraulic pressure at the start of a torque phase during shift control toward a required speed position.