Parking Lock Emergency Release Mechanism
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Solution Overview
Problem
The existing parking lock systems for automatic transmissions, particularly those with hydraulically actuatable bistable interlocks, fail to provide an effective emergency release mechanism when the hydraulic and electrical control systems fail, rendering the parking lock inoperable.
Innovation Solution
A parking lock system that includes a locking pawl, a connecting rod, a spring, a hydraulically actuatable actuator, and a manually actuatable emergency release device. The system features two disks mechanically connected to transmit the spring force for engagement and disengagement, allowing the parking lock to be manually disengaged even when the actuator is not operable, and includes a detent device fixed by an electromagnet to secure the piston in either engaged or disengaged positions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a hydraulically actuatable parking lock system with electromagnet-controlled detent mechanism is used, then the parking lock can be securely locked and automatically disengaged, but the system becomes inoperable when hydraulic pressure supply fails
Solution Approach 1:
The parking lock system is segmented into two independent control paths: a normal operational path using hydraulic actuation with electromagnet-controlled detent, and an emergency path using manual mechanical actuation. This segmentation allows the system to maintain functionality through the emergency mechanical path when the hydraulic system fails.
Solution Approach 2:
A manually actuatable emergency release device is introduced as an intermediary mechanism that directly acts on the piston rod or connecting rod to disengage the parking lock. This intermediary provides an alternative control method that bypasses the failed hydraulic system, enabling emergency release when normal operation fails.
2Reliability
If the parking lock piston is mechanically interlocked in both engaged and disengaged positions, then unintentional disengagement is prevented, but emergency release becomes impossible when electrical control fails
Solution Approach 1:
The system employs dynamic characteristics by making the mechanical interlocking conditional rather than fixed. The electromagnet provides dynamic control to release the interlocking when needed, while the manual emergency release provides a static mechanical override that can always disengage the interlocking, ensuring both security during normal operation and accessibility during emergencies.
Solution Approach 2:
The manual emergency release device serves as an intermediary that can override the mechanical interlocking system. By directly acting on the piston rod or connecting rod, it bypasses the electromagnet-controlled detent mechanism, providing access to emergency release even when electrical control fails.
3Adaptability or versatility
If a cam disk operatively connected to the detent disk is used for emergency release, then mechanical disengagement is enabled, but the system complexity increases
Solution Approach 1:
The emergency release function is extracted from the complex cam disk and detent disk linkage system and implemented through a simplified manual actuation mechanism that directly acts on the piston rod or connecting rod. This extraction reduces mechanical linkage complexity while maintaining emergency release functionality.
Solution Approach 2:
Instead of using a complex cam disk mechanism that operates during normal operation, the emergency release is inverted to use a simple manual lever or actuator that operates only during emergencies. This inversion simplifies the system by eliminating unnecessary complex linkages while preserving the essential emergency release function.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Enables the parking lock to be disengaged manually during emergencies, ensuring the vehicle can be safely released from the locked state even if the hydraulic and electrical control systems fail, thus maintaining operational safety.
Implementation Method 1
The interlocking element is spring-mounted on the connecting rod via a spring element. The engagement of the parking lock usually takes place mechanically via the spring force of an spring.
Implementation Method 2
a hydraulically actuatable parking lock piston, which is arranged in a parking lock cylinder and is axially displaceable against the force of the spring, which is usually a leg spring, for disengaging the parking lock and is axially displaceable by the force of the spring for engaging the parking lock.
Implementation Method 3
a solenoid valve is mostly provided, which is electrically energized in this position of the parking lock cylinder and, as a result, actuates a detent mechanism acting on the parking lock piston.
Data Source
AI summary
A parking lock having a locking pawl engageable into a parking interlock gear, a connecting rod with an interlocking element to prevent the parking lock from disengaging when in the locked condition, a spring for engaging the parking lock, a hydraulically actuatable actuator for disengaging the parking lock, and an emergency release device for emergency disengagement of the parking lock. The piston is articulatedly connected to a first disk rotatably mounted on a selector shaft, a second disk connected to the selector shaft in a torsion-proof manner is articulatedly connected to the connecting rod, the spring is tensioned between the transmission housing and the second disk, and the emergency release device is connected to the selector shaft in a torsion-proof manner. The first disk is operatively connected to the second disk such that rotation of the second disk by the emergency release device does not rotate the first disk.