Automatic Parking Lock Engagement Logic for Gearbox Safety
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Solution Overview
Problem
Existing methods for automatically engaging a parking lock in automatic or automated gearboxes often fail to balance vehicle safety and drivability, particularly in vehicles with keyless ignition systems, where determining the driver's intent to leave the vehicle is unreliable, and may lead to unintended start-ups or rolling.
Innovation Solution
A method using Boolean logical operators to automatically engage the parking lock based on vehicle speed and selected drive positions, without relying on the ignition key removal signal, ensuring high safety and drivability by considering the driver's intended actions through specific functional connections and monitoring.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If automatic parking lock engagement is implemented based on ignition circuit interruption and vehicle speed, then vehicle safety against unintended rolling is improved, but vehicle drivability and availability deteriorate due to unexpected gearbox state changes
Solution Approach 1:
Instead of automatically engaging the parking lock when ignition is interrupted (conventional approach), the invention inverts the logic by automatically engaging the neutral position when ignition is interrupted. This prevents rolling while maintaining drivability, as neutral is a safer default state that doesn't lock the vehicle unnecessarily.
Solution Approach 2:
The system performs preliminary action by pre-positioning the gearbox in neutral before the driver potentially needs to move the vehicle. This anticipatory positioning ensures safety is established in advance while allowing the driver to easily transition to drive mode when ready, maintaining both safety and drivability.
2Reliability
If the parking lock is automatically engaged when ignition is interrupted, then protection against unintended start-up is improved, but vehicle availability deteriorates due to loss of drivability
Solution Approach 1:
The invention inverts the conventional approach by not engaging parking lock automatically, but rather ensuring the gearbox is in neutral. This provides protection against unintended start-up while maintaining vehicle availability, as the vehicle can be quickly put into drive mode without being locked in parking position.
3Extent of automation
If reliance is placed on ignition key removal signal for automatic parking lock engagement, then automation is improved, but reliability deteriorates in keyless ignition systems due to unreliable driver intent detection
Solution Approach 1:
The invention extracts the problematic ignition key removal signal from the control logic and replaces it with more reliable signals: ignition circuit interruption status and vehicle speed. This maintains automation while significantly improving reliability, as these signals directly indicate the vehicle state without requiring interpretation of driver intent.
Data Source
AI summary
A method of automatically engaging a parking lock or an automatic or automated gearbox of a motor vehicle, which can be engaged depending on a drive position selected by the driver of the motor vehicle, by way of a selector device and depending on other operating parameters. In order to achieve as little restriction of the drivability of the motor vehicle as possible, without neglecting the safety of the driver and surroundings, two different complex embodiments of an Auto_P function for automatically engaging the parking lock are proposed, if the motor vehicle is at least approximately stopped and, at the same time, an ignition circuit acting on the drive motor of the motor vehicle is electrically interrupted.