Park Lock Carrier Assembly for Power-Loss Engagement Control
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Solution Overview
Problem
Modern vehicles with automatic transmissions face unpredictable behavior when the supply of electricity to the park lock system is lost, leading to potential wheel locking or failure to immobilize the vehicle, highlighting a need for improved park lock systems.
Innovation Solution
A park lock system comprising a movable primary carrier, secondary carrier, rod, biasing member, and actuator, which configures to lock or unlock the transmission based on available supply voltages and wheel speed, ensuring reliable operation even during power failures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the park lock system is electronically controlled without backup power supply, then the device complexity is reduced, but the reliability deteriorates when electricity supply is lost
Solution Approach 1:
The spring mechanism is pre-loaded and positioned to automatically engage the parking pawl with the park lock wheel teeth when power is lost. The secondary carrier and rod assembly are pre-configured to mechanically force the pawl into the locked position, ensuring the vehicle is immobilized before any dangerous movement can occur.
Solution Approach 2:
The spring-loaded mechanism uses the loss of electrical power itself as the triggering condition for engagement. When the electric actuator fails to maintain the unlocked position due to power loss, the spring automatically pushes the secondary carrier and rod to engage the parking pawl, making the system self-actuating in response to the power failure condition.
2Reliability
If the parking pawl is automatically engaged on power loss, then the reliability is improved, but the ease of operation deteriorates due to unintended locking
Solution Approach 1:
The control unit continuously monitors wheel speed through sensors and uses this feedback to determine whether to allow the spring mechanism to engage the parking pawl. When wheel speed exceeds the threshold, the control unit activates the electric actuator to counteract the spring force and prevent engagement, creating a closed-loop control system that prevents unintended locking.
Solution Approach 2:
The system dynamically adjusts the engagement state of the parking pawl based on real-time wheel speed conditions. The spring mechanism remains in a state of potential engagement, but the electric actuator dynamically counteracts the spring force when motion is detected, allowing the system to transition between locked and unlocked states based on operational conditions.
3Reliability
If a spring mechanism is added to ensure locking on power loss, then the reliability is improved, but the device complexity increases
Solution Approach 1:
The secondary carrier is positioned within the primary carrier, and the rod assembly is nested within the secondary carrier. This nested arrangement allows multiple functional components to be compactly integrated without significantly increasing the overall spatial footprint of the park lock system, reducing the complexity penalty of adding the spring mechanism.
Solution Approach 2:
The spring mechanism, secondary carrier, and rod assembly are combined into a single integrated mechanical unit that works together to transfer the spring force to the parking pawl. This merging of components reduces the number of separate assemblies and simplifies the overall structure compared to having independent locking and spring mechanisms.
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 system maintains transmission control and ensures safe immobilization of the vehicle by monitoring supply voltages and wheel speed, preventing unintended wheel locking and ensuring reliable operation during electrical failures.
Implementation Method 1
a biasing member configured to bias the secondary carrier to maintain the secondary carrier in the normal position relative to the primary carrier
Data Source
AI summary
A park lock system for a vehicle transmission, includes a movable primary carrier, a secondary carrier, a rod, a first biasing member, an engagement carrier, and a first actuator. The movable primary carrier defines a primary internal space. The secondary carrier is located within the primary internal space and is movable relative to the primary carrier. The rod fixedly extends from the secondary carrier and includes a rod portion located outside of the primary internal space. The first biasing member is located within the primary internal space between the secondary carrier and the primary carrier. The engagement carrier is configured to receive the rod portion and includes a terminal portion operably connected to a pawl and a park lock wheel arrangement to lock and unlock the vehicle transmission. The first actuator is configurable in a first state or a second state.