Automatic Transmission Park Lock With Manual Emergency Release
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing parking lock systems for automatic transmissions lack an effective emergency release mechanism that allows manual disengagement without compromising the compact design and operational efficiency, especially when the hydraulic and electrical systems fail.
Innovation Solution
A parking lock system with a bi-stable locking device and an emergency release mechanism that includes two pistons and an electromagnetically actuatable locking device, allowing axial movement of the second piston to disengage the parking lock manually, while the first piston remains locked in its engaged state, ensuring secure engagement and disengagement without relying on functional hydraulic and electrical supplies.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a hydraulic system with electromagnetically actuatable locks is used to secure the parking lock piston, then the parking lock is protected against unintentional disengagement, but the system cannot be released in emergency situations when electrical control fails
Solution Approach 1:
A mechanically actuated cam disk is introduced as an intermediary device that can directly rotate the detent disk to disengage the parking lock in emergency situations, bypassing the failed electrical control system while remaining invisible during normal operation
2Ease of operation
If a cam disk is added for emergency release, then manual disengagement is possible, but the device complexity increases
Solution Approach 1:
The cam disk is designed with dual functionality: during normal operation it remains stationary and is part of the regular mechanism, but during emergency operation it becomes an active tool for rotating the detent disk, thus one component serves multiple purposes without requiring separate dedicated emergency release mechanisms
Solution Approach 2:
The emergency release function is segmented from the normal operation system, allowing the cam disk to be independently actuated through the emergency release device without interfering with the hydraulic and electrical control systems used during normal parking lock operation
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 reliable manual disengagement of the parking lock in emergency situations without affecting the compact design or operational efficiency, ensuring the parking lock remains secure and functional even when the hydraulic and electrical systems fail.
Implementation Method 1
a torsion spring for disengaging the parking lock and by the force of the insert spring for engaging the parking lock is axially displaceable
Implementation Method 2
the cylinder chamber of the parking lock cylinder is pressurized and pushes the parking lock piston and thus the dial against the spring force of the torsion spring into the P_off position (parking lock disengaged)
Implementation Method 3
a solenoid valve is usually provided, which is electrically energized in this position of the parking lock cylinder and thereby actuates a latching mechanism acting on the parking lock piston
Data Source
Figure 1
Figure 2
Figure 3
AI summary
The invention relates to a park lock comprising a pawl (2), which engages in or disengages from a park lock gear (1), and a locking element (6), which is arranged on a connecting rod (5) to a selector lever (4) and which, in the locked state, prevents the pawl (2) from being pressed out of a tooth space (1a) of the park lock gear (1). The end of the connecting rod (5) remote from the locking element (6) is articulated to the selector lever (4). When the park lock is engaged, the selector lever (4) is rotated by an engagement spring (9). A hydraulically actuatable actuator (10) having two pistons (11, 12) is provided for disengaging the park lock. In order to disengage the park lock, pressure is applied to the first piston (11), and the first piston then axially slides the second piston (12) against the spring force of the engagement spring (9). The axial motion of the second piston (12) causes a rotation of the selector lever (4) and vice versa. A locking device (13) of the actuator (10), which locking device can be actuated by an electromagnet (13a), locks the first piston (11) in a piston position corresponding to the engaged or the disengaged state (P_ein, P_aus) of the park lock when the electromagnet (13a) is not energized. In order to manually disengage the park lock, an emergency release device (15) can be brought into operative connection with the selector lever (4) such that the second piston (12) can be axially slid by the selector lever (4) in the event of emergency release, without the first piston (11) leaving the piston position thereof corresponding to the engaged state (P_ein) of the park lock.