Automatic Transmission Control for Smooth Reverse Engagement
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Solution Overview
Problem
Automatic transmissions with mechanical engaging mechanisms face challenges in smoothly switching to the reverse gear range due to potential noise and vibration when the two-way clutch is switched during rotation, leading to mechanical failure if not done correctly.
Innovation Solution
A control apparatus that includes a detection unit and a control unit to manage the engaging mechanisms, switching the mechanical engaging mechanism from a one-way to a two-way rotation restriction state only when the shift position is detected as reverse and after other engaging mechanisms are controlled, with pre-engagement control initiated in the lowest-speed forward range or non-running condition to ensure smooth transitions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the two-way clutch is switched to restrict rotation in both directions during rotation of the rotational element, then the reverse range can be engaged, but unusual noise or vibration occurs and the two-way clutch breaks
Solution Approach 1:
The control unit initiates pre-engagement control of at least one engaging mechanism before switching the mechanical engaging mechanism to the second state. This preliminary action prepares the transmission path in advance, allowing the rotational element to decelerate to a stop before the two-way clutch is switched, thereby preventing noise, vibration, and mechanical failure during engagement
2Loss of time
If switching of the two-way clutch is performed quickly to implement smooth start in reverse range, then response time is improved, but the risk of switching during rotation increases
Solution Approach 1:
The control unit starts pre-engagement control in advance when specific conditions are met (mechanical engaging mechanism in first state and automatic transmission in lowest-speed forward range or non-running range). This allows the system to prepare the engagement path beforehand, reducing the actual shift time while ensuring the rotational element is stopped before the two-way clutch switches, thus maintaining both speed and safety
Solution Approach 2:
The control unit monitors the state of the mechanical engaging mechanism and the operating condition of the automatic transmission to determine when to initiate pre-engagement control. This feedback-based control ensures that pre-engagement is started at the optimal moment, balancing quick response with safe engagement by confirming the rotational element is stationary before switching the two-way clutch
Data Source
AI summary
An automatic transmission of this invention includes a plurality of engaging mechanisms, and the plurality of engaging mechanisms include a mechanical engaging mechanism that functions as a brake. The mechanical engaging mechanism can switch a rotational element between a first state in which rotation is restricted only in one direction and a second state in which rotation is restricted in both directions. When switching from the first state to the second state, engagement control is started in advance for at least one of the plurality of engaging mechanisms to be set in an engaging state.