Drum Transmission Parking Lock Release with Dual Arm Restraint
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Solution Overview
Problem
Conventional drum-type transmission devices face reliability issues with their parking lock mechanisms, particularly when the parking operation arm becomes sagged or burred, leading to unintended vehicle movement on slopes due to failure in releasing the locked state, and there is a risk of unexpected vehicle movement.
Innovation Solution
The drum-type transmission device incorporates a parking lock mechanism with a parking operation arm that is urged towards the unlock position by a spring and a transmission operation shaft with an arm restraining portion, ensuring reliable release of the parking state through dual lock release mechanisms without additional operation systems, and includes an electric actuator for enhanced locking reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a parking lock mechanism using only spring force is used, then the structure is simple, but the parking operation arm may remain engaged with the parking gear when the vehicle is on a slope or the arm is sagged/burred, leading to failure to release the locked state
Solution Approach 1:
The parking lock release function is segmented into two independent mechanisms: a spring-based release mechanism and a transmission operation shaft-based release mechanism. This segmentation ensures that if one mechanism fails (e.g., spring force insufficient due to slope or arm sag), the other mechanism can still reliably release the parking lock.
Solution Approach 2:
The transmission operation shaft with arm restraining portion provides a backup release mechanism that activates beforehand to prevent the parking operation arm from remaining engaged due to insufficient spring force. The arm restraining portion is designed to forcibly separate the parking operation arm from the parking gear, cushioning against the risk of failed release.
2Reliability
If an additional operation system is added to provide a backup release mechanism, then the parking lock release reliability is improved, but the device complexity increases
Solution Approach 1:
The transmission operation shaft serves multiple functions: it controls the drum member rotation for gear shifting and simultaneously provides the backup parking lock release function through the arm restraining portion. This multi-functionality avoids adding a separate operation system, thereby maintaining structural simplicity while improving reliability.
Solution Approach 2:
The parking lock release function is merged with the existing transmission operation shaft mechanism. The arm restraining portion is integrated into the transmission operation shaft, combining the gear shifting control and parking lock release functions into a single integrated system, thus avoiding additional complexity.
3Ease of operation
If the parking operation arm is designed to be displaceable between lock and unlock positions, then the parking lock functionality is achieved, but the arm may become sagged or burred during operation, leading to unintended vehicle movement
Solution Approach 1:
The arm restraining portion acts as an intermediary mechanism that ensures reliable disengagement of the parking operation arm from the parking gear. It mediates the displacement between the lock and unlock positions by providing a forced separation mechanism, preventing the arm from remaining engaged due to sagging or burring during operation.
Solution Approach 2:
The arm restraining portion applies preliminary anti-action by forcing the parking operation arm toward the unlock position before unintended vehicle movement can occur. This counteracts the harmful effects of arm sagging or burring that might otherwise cause the arm to remain engaged and lead to vehicle movement on slopes.
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
The solution enhances the reliability of the parking lock mechanism by ensuring consistent release of the parking state even under adverse conditions, such as vehicle sag or slope, and maintains locking functionality even when the electric actuator is not powered, thereby preventing unexpected vehicle movement.
Implementation Method 1
a parking release spring that urges the parking operation arm toward the unlock position
Implementation Method 2
an arm restraining portion provided on one end of the transmission operation shaft, and capable of urging the parking operation arm toward the unlock position when the drum member rotates from the parking position to the shift position or neutral position
Data Source
AI summary
A parking lock mechanism of the drum-type transmission device comprises a parking gear that is provided on the transmission shaft, a parking operation arm which is selectively operated between a lock position engaging with the parking gear and an unlock position away from the parking gear, a parking release spring for urging the operation arm toward the unlock position, and a parking pushing member which is positioned at a lock position by pushing the operation arm according to the rotation of the drum member from the shift position or the neutral position to the parking position. One end of the transmission operation shaft is located near the operation arm. At one end of the shift operation shaft, there is provided an arm restraining portion that can urge the operation arm toward the unlock position when the drum member is moved from the parking position to the shift position or the neutral position.