In-Vehicle Control Device Shock Reduction Torque Management
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Solution Overview
Problem
When releasing the shift lock in a vehicle with an electric parking brake, a shock can occur due to the sudden release of torsional torque from the drive shaft, and further shocks may arise from the damping torque output by the motor during this process.
Innovation Solution
The in-vehicle control device implements shock reduction control by outputting torque based on the vehicle's tilt angle from the electric motor when releasing the shift lock, determining whether to perform this control based on the activation and release states of the shift lock and foot brake.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If damping torque is output from the motor when releasing the shift lock, then the shock from releasing torsional torque is reduced, but a shock may occur due to the damping torque itself
Solution Approach 1:
The control device changes the torque output parameter dynamically based on the vehicle tilt angle. When the vehicle is on a slope, the motor outputs torque proportional to the tilt angle to counteract gravitational effects on the drive shaft. This parameter adjustment ensures that the damping torque matches the torsional torque conditions, preventing both excessive shock from torque release and shock from inappropriate damping torque application.
2Object-affected harmful factors
If shock reduction control is always performed when releasing shift lock, then shocks from torsional torque are reduced, but shocks from unnecessary control actions increase
Solution Approach 1:
The control device performs preliminary assessment of the shift lock activation state before executing shock reduction control. It checks whether the shift lock was activated with the foot brake applied and whether the electric parking brake was activated subsequently. Based on this preliminary evaluation, the control device determines whether shock reduction control is necessary, avoiding unnecessary control actions that could generate shocks.
3Object-affected harmful factors
If the control device checks multiple states to determine whether to perform shock reduction control, then unnecessary shocks are reduced, but the control complexity increases
Solution Approach 1:
The control logic is segmented into distinct evaluation stages: first checking if the shift lock was activated with foot brake applied, then checking if electric parking brake was activated, and finally determining whether shock reduction control is needed. This segmentation of the control process into discrete decision points simplifies the overall complexity while maintaining comprehensive shock reduction capability.
Data Source
AI summary
The in-vehicle control device is mounted on a motor vehicle including a shift mechanism having a parking position for performing a shift lock on an axle, an electric parking brake for applying a braking force to a wheel connected to the axle, and an electric motor capable of inputting and outputting power to and from the axle. The vehicle control device performs shock reduction control for suppressing a shock generated in the vehicle by outputting torque corresponding to the inclination angle of the vehicle from the electric motor when releasing the shift lock, and determines whether to perform the shock reduction control when releasing the shift lock according to a state when activating the shift lock and a state after activating the shift lock.