Transmission Control for Shuttle Shifting Prevention
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Solution Overview
Problem
Undesirable shuttle shifting occurs in vehicles equipped with automatic transmissions and road speed limiters, leading to poor drivability and passenger comfort due to frequent gear changes when traveling at constant speed on varying terrain.
Innovation Solution
A method and system that determine when a vehicle is in a shuttle shifting range and control the transmission to prevent shifting under conditions where it would normally occur, by limiting the percentage engine torque signal sent to the transmission controller, maintaining the vehicle in a higher gear and preventing unnecessary gear changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the transmission controller uses predetermined shift schedules to control gear changes, then the transmission operates efficiently under normal conditions, but shuttle shifting occurs when the vehicle travels at RSL speed on varying terrain
Solution Approach 1:
The system dynamically adjusts transmission control based on detected shuttle shifting conditions. When shuttle shifting is detected (through monitoring gear change frequency and operating parameters), the controller activates a shuttle shift prevention mode that overrides the normal predetermined shift schedules. This dynamic adaptation allows the system to maintain stable operation under normal conditions while preventing harmful shuttle shifting when terrain variations cause the vehicle to operate near shift points at RSL speed.
Solution Approach 2:
The system implements feedback by continuously monitoring transmission operating parameters (gear position, engine torque, vehicle speed) and detecting patterns indicative of shuttle shifting. When the feedback indicates shuttle shifting conditions, the controller responds by modifying shift control logic to prevent further shifting. This closed-loop feedback mechanism enables the system to distinguish between normal shift operations and harmful shuttle shifting, resolving the contradiction between maintaining efficient predetermined shift schedules and preventing drivability issues.
2Adaptability or versatility
If the transmission shifts gears in response to torque changes on varying terrain, then the transmission adapts to load conditions, but frequent gear changes occur that reduce drivability
Solution Approach 1:
The system applies preliminary anti-action by detecting conditions that precede harmful shuttle shifting (operation at RSL speed near shift points on varying terrain) and preemptively preventing gear changes in response to torque variations. When shuttle shift prevention mode is activated, the controller suppresses shift commands that would otherwise be generated by torque changes, thereby counteracting the adaptive response before it can cause harmful frequent gear changes. This allows the transmission to maintain adaptability to load conditions while preventing the adverse effect of excessive gear changes.
3Use of energy by moving object
If the vehicle maintains constant speed at RSL on varying terrain, then fuel economy is improved, but torque variations cause unwanted gear shifts
Solution Approach 1:
The system dynamically modifies transmission control behavior when operating at RSL speed on varying terrain. By detecting the combination of constant RSL speed operation and terrain-induced torque variations, the controller activates a specialized control mode that prevents gear shifts under these specific conditions. This dynamic adjustment allows the vehicle to maintain fuel-efficient constant speed operation while preventing the transmission instability that would otherwise result from torque-driven gear changes.
Data Source
AI summary
A system for operating a vehicle equipped with an automatic transmission and a vehicle road speed limiter (RSL) which is programmable to limit the maximum vehicle speed for a given transmission gear includes at least on controller. The at least one controller is operable, when the speed limiter (RSL) is active, to determine if the vehicle is operating in a shuttle shifting range based on the current status of preselected operating parameters. When the vehicle is operating in a shuttle shifting range, the at least one controller is operable to control transmission operation to prevent shifting under conditions where shifting would otherwise normally occur.