Vehicle Control Device Torque Limiting Park Lock Release
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Solution Overview
Problem
In automatic transmissions with park-by-wire systems, the unlocking of the park lock mechanism is delayed during high meshing loads, such as when parking on a hill or towing, leading to difficulties in timing the engagement of the engaging element and park lock release, which increases the load on the park lock mechanism and may result in sudden vehicle starts.
Innovation Solution
A control device and method that limit the torque of the drive source until the park lock mechanism is released and the engaging element is engaged, ensuring that the load on the park lock mechanism is suppressed and preventing sudden starts by gradually increasing engine torque after the park lock is released.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the engaging element is engaged earlier to enable start running, then the productivity is improved, but the load on the park lock mechanism becomes even larger
Solution Approach 1:
The park lock mechanism is activated in advance before the engaging element is engaged. The control unit outputs a signal to the actuator to operate the park lock mechanism before the engaging element engagement is completed, ensuring the park lock is ready to take over the load immediately when the engaging element engages, thereby preventing excessive load on the park lock mechanism during the transition.
2Ease of operation
If the park lock mechanism is operated by actuator with mechanical linkage, then the ease of operation is improved, but the device complexity increases
Solution Approach 1:
The patent replaces the traditional mechanical linkage between the shifter and the park lock mechanism with an electrical signal-based control system. The control unit receives signals from the shifter position sensor and controls the actuator accordingly, eliminating the need for complex mechanical linkages while maintaining ease of operation.
3Reliability
If the unlocking of park lock mechanism is delayed during high meshing load, then the reliability is improved, but the loss of time increases
Solution Approach 1:
The park lock mechanism is activated in advance before the engaging element engagement is completed. By outputting the signal to the actuator beforehand, the system ensures that the park lock mechanism is ready to engage immediately when the engaging element is fully engaged, reducing the actual unlocking time while maintaining reliability under high load conditions.
Data Source
AI summary
A control device is provided for a vehicle including a drive source and an automatic transmission having a park lock mechanism for locking an output shaft and an engaging element to be engaged at the start of running. Output rotation of the drive source is input to the automatic transmission. The control device includes a control unit to limit a torque of the drive source until the release of locking by the park lock mechanism is completed in response to an instruction being given to change from a parking range to a travel range. The control unit is configured to limit the torque of the drive source from after the instruction is given to change from the parking range to the travel range until the release of locking by the park lock mechanism is completed.