Automatic Transmission Gearshift Control for One-Way Clutch Shock
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Solution Overview
Problem
The existing warm-up promotion control for automatic transmissions using gear-shift maps offset towards higher vehicle speeds leads to neutral feeling and engagement shock due to abrupt one-way clutch engagement when the accelerator is released and then depressed again, causing a mismatch between engine and output shaft rotation speeds.
Innovation Solution
A control apparatus that adjusts the gear-shift lines by adding coast correction lines to project the small accelerator opening angle area towards a lower vehicle speed side, preventing the one-way clutch from idling and ensuring smooth engagement during accelerator re-depression by maintaining the up-shift stage and avoiding one-way clutch engagement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If gear-shift lines are offset toward higher vehicle speed side for warm-up promotion, then engine rotation speed increases, but one-way clutch engagement shock occurs during accelerator re-depression
Solution Approach 1:
The control device performs preliminary detection of accelerator operation patterns (foot separation followed by re-depression). When such a pattern is detected, the system proactively suppresses down-shift control before the one-way clutch engagement shock can occur, preventing the harmful effect while maintaining warm-up promotion benefits
Solution Approach 2:
The control device introduces an intermediate control mechanism that detects accelerator operation patterns and mediates between the warm-up promotion gear-shift map and the one-way clutch engagement. By identifying the specific operating condition (accelerator re-depression after foot separation), the system selectively applies or suppresses down-shift control to prevent engagement shock
2Productivity
If gear-shift lines are offset toward higher vehicle speed side, then low speed stage selection increases, but drive feeling deteriorates due to neutral feeling from one-way clutch idle run
Solution Approach 1:
The system performs preliminary detection of accelerator operation patterns to identify when the driving point will traverse the gear-shift lines. By detecting the accelerator foot separation and re-depression sequence in advance, the system proactively suppresses down-shift control to prevent the one-way clutch from running idle, thereby maintaining smooth drive feeling while preserving warm-up promotion
Solution Approach 2:
The control device continuously monitors accelerator operation status and provides feedback control. When accelerator re-depression is detected after foot separation, the system responds by suppressing down-shift control, creating a closed-loop control that adapts to driver operations and maintains optimal drive feeling
Data Source
AI summary
In a control apparatus for an automatic transmission, in a drive train, a driving source and the automatic transmission having a plurality of gear-shift stages including the gear-shift stages at each of which a one way clutch is engaged during a drive are equipped, a gear-shift line correction by such coast correction lines as to provide such gear-shift line shapes projecting toward a lower vehicle speed side in a small accelerator opening area is added to up-shift lines of the gear-shift stages at each of which the one way clutch participates from among the gear-shift lines after the correction by vehicle speed correction lines.