Parking Lock Release Control Using Main Motor Load Relief
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Solution Overview
Problem
Existing vehicle control devices face challenges in appropriately releasing the parking lock due to variability in operating environments, leading to poor responsiveness and potential misjudgment of actuator torque, especially when the parking range release determination time is not optimized.
Innovation Solution
The vehicle control device includes an actuator drive control section, a main motor drive control section, and a range determination section that performs meshing surface pressure reduction control by varying the parking range release determination time based on the operating environment, including tilt angle, vehicle weight, and actuator temperature, to ensure proper release of the parking lock.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a fixed parking range release determination time is used, then the control logic is simple, but the responsiveness is poor and misjudgment occurs in variable operating environments
Solution Approach 1:
The patent applies dynamics by making the parking range release determination time variable rather than fixed. The control device adjusts the determination time based on operating environment parameters including tilt angle, vehicle weight, and actuator temperature. This dynamic adjustment ensures reliable parking lock release across different operating conditions while maintaining appropriate responsiveness.
Solution Approach 2:
The patent implements parameter changes by modifying the determination time parameter according to multiple operating environment parameters. Specifically, the determination time is adjusted based on tilt angle (affecting gravitational load on the parking lock), vehicle weight (affecting the force required to release the lock), and actuator temperature (affecting actuator performance). This parameter-based adaptation resolves the contradiction between reliability and complexity.
2Reliability
If the actuator torque is increased to ensure reliable parking lock release, then the release reliability improves, but the actuator size increases and heat generation rises
Solution Approach 1:
The patent applies preliminary action by performing meshing surface pressure reduction control before attempting to release the parking lock. The main motor is activated in advance to reduce the meshing surface pressure between the parking gear and parking lever, creating more favorable conditions for actuator operation. This preliminary action reduces the torque requirement for the actuator while ensuring reliable lock release.
Solution Approach 2:
The patent introduces the main motor as an intermediary between the control system and the parking lock mechanism. The main motor provides meshing surface pressure reduction control that facilitates the actuator's work in releasing the parking lock. This intermediary action reduces the direct torque burden on the actuator, allowing for a smaller actuator design with reduced heat generation while maintaining release reliability.
3Power
If the meshing surface pressure is reduced by main motor control, then the actuator torque requirement decreases, but the control system complexity increases
Solution Approach 1:
The patent merges the control functions by integrating the meshing surface pressure reduction control with the existing parking range release control logic. The main motor drive control section coordinates with the actuator drive control section to provide combined control, reducing the need for separate complex control systems. This merging approach reduces actuator torque requirements while managing control system complexity through integrated design.
Data Source
AI summary
A vehicle control device controls a vehicle drive system including a main motor as a drive source of a vehicle, a parking lock mechanism, and an actuator. The vehicle control device includes an actuator drive control section that controls a drive of the actuator, a main motor drive control section that controls a drive of the main motor, and a range determination unit that determines whether or not a shift range is a parking range. When releasing the parking lock, if the parking range is not released within a parking range release determination time that is variable according to an operating environment, the main motor drive control section performs a meshing surface pressure reduction control for driving the main motor so as to reduce a meshing surface pressure between a parking gear and a parking lever.