Transmission Neutral Holding Phase for Stationary Vehicle Safety
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Solution Overview
Problem
Existing automatic and automated motor vehicle transmissions lack a method to engage the neutral position and parking lock efficiently while ensuring maximum drivability and safety, particularly when the vehicle is stationary and the ignition is off, without relying on additional measures.
Innovation Solution
A method that activates a holding phase in the transmission, allowing it to be in a neutral position free from friction force locking when the vehicle is stationary and the ignition is off, using a separate operating device, which can only be activated when the vehicle is at rest, the ignition is interrupted, and the shift position is set to neutral, with additional criteria such as vehicle horizontal position and ignition key presence being optional conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the parking lock is automatically engaged when the ignition is off and vehicle speed is low, then the vehicle can be kept stationary safely, but the drivability and ability to move are reduced
Solution Approach 1:
The system dynamically switches between two operational modes: a locked mode where the parking lock is engaged to prevent vehicle movement, and an unlocked mode where the parking lock is disengaged to allow drivability. The control unit automatically transitions between these modes based on real-time monitoring of ignition status and vehicle speed parameters, ensuring the vehicle remains stationary when safe but becomes drivable when conditions permit
Solution Approach 2:
The system changes the operational state of the parking lock based on parameter changes in ignition status and vehicle speed. When the ignition is turned off and vehicle speed drops below a threshold, the parking lock is automatically engaged. When the ignition is turned on or speed exceeds the threshold, the parking lock is disengaged, allowing the vehicle to move freely
2Reliability
If additional measures are taken to engage the neutral position and parking lock, then safety and controlled movement are improved, but the complexity of the system increases
Solution Approach 1:
The existing transmission control unit is made multi-functional by adding the capability to automatically control the parking lock engagement. Instead of adding a separate dedicated control system, the control unit already responsible for transmission management is enhanced to also manage parking lock actuation based on ignition and speed parameters, thereby improving safety without proportionally increasing system complexity
Solution Approach 2:
The system uses its own existing sensors and control mechanisms to automatically manage the parking lock engagement. The control unit monitors its own operational parameters (ignition status, vehicle speed) and autonomously decides when to engage or disengage the parking lock without requiring external intervention or additional complex control systems
Data Source
AI summary
A method for shifting an automatic or an automated transmission of a motor vehicle to a “neutral” position such that the shift position of the transmission and a parking lock, provided for keeping the motor vehicle stationary, are engaged as a function of a shift position selected with a driver operated selector device and as a function of other operating parameters of the motor vehicle. A holding phase, in which the transmission is in the neutral position, free from friction force locking, can be activated by a separate operating device which is provided, in addition to the selector device, but only when the motor vehicle is simultaneously at least approximately stationary, an ignition current circuit that acts on a drive engine of the motor vehicle is electrically interrupted, and the “neutral” (N) shift position is specified by a selector device.