Automatic Transmission Parking to Reverse Transition Control
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Solution Overview
Problem
The existing automatic transmissions take a long time to transition from a parking range to a reverse range, resulting in unfavorable responsiveness for reverse movement.
Innovation Solution
The automatic transmission includes a switching mechanism, such as a two-way clutch, that is controlled to switch from a reverse rotation prevention state to a fixed state during parking release control, allowing simultaneous parking release and reverse side preparation, ensuring sufficient hydraulic pressure and preventing differential rotation, which damages the clutch.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If parking release control is performed sequentially followed by reverse side preparation mode, then the parking state is properly released, but the transition time to reverse normal mode is long and responsiveness is poor
Solution Approach 1:
The switching mechanism is activated in advance during parking release control to prepare the element for reverse rotation, so that when reverse side preparation mode begins, the mechanism is already positioned to enable immediate reverse movement, thereby reducing transition time
Solution Approach 2:
Parking release control and reverse side preparation mode are merged into a simultaneous operation by activating the switching mechanism during parking release, so both functions occur in parallel rather than sequentially, reducing overall transition time
2Loss of time
If the switching mechanism is activated during simultaneous parking release and reverse side preparation, then responsiveness is improved, but hydraulic pressure may become insufficient causing differential rotation and clutch damage
Solution Approach 1:
Hydraulic pressure is built up in advance during parking release control before the switching mechanism is activated, ensuring sufficient pressure is available when simultaneous operation begins, preventing differential rotation and clutch damage
Solution Approach 2:
The system prepares sufficient hydraulic pressure beforehand during parking release to cushion against potential pressure deficiencies when the switching mechanism activates, preventing harmful differential rotation of the clutch
Data Source
AI summary
An automatic transmission for improving responsiveness until reverse movement is possible. When the range is switched from a parking range to a reverse range, P lock release control for releasing a parking state starts. When a two-way clutch is in a reverse rotation prevention state, hydraulic pressure is supplied to a first clutch, a third clutch, and a third brake, and a process in a reverse side preparation mode starts. When the first clutch is in a connected state and a rotational speed of an input shaft is a predetermined rotational speed, whether a parking piston of a parking lock mechanism is at an unlock position is determined. When it is at the unlock position, a driving source is requested to restrict an output torque. Then, hydraulic pressure is supplied to the two-way clutch, and the two-way clutch is switched from a reverse rotation prevention state to a fixed state.