Electric Motor Parking Torque Control for Sprag Alignment
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Solution Overview
Problem
During the parking process, vehicles equipped with electric motors face issues of impact and potential damage due to external forces, such as slopes, when shifting to the parking stage, as the parking sprag may not be properly combined with the parking gear, leading to gear alignment problems and potential injury to passengers.
Innovation Solution
A parking control method that calculates external forces applied to the wheels and determines whether the drive shaft fixing means is combined, using an electric motor to apply a torque in the opposite direction to external forces, either less than or greater than the external force depending on the sprag's state, to prevent impact and ensure smooth gear alignment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the brake pedal is released after shifting to P stage, then the parking sprag should mechanically fix the rotation shaft, but external force may cause the parking sprag to be not combined with the parking gear leading to impact and vibration
Solution Approach 1:
The controller calculates external force and determines the combination state of the drive shaft fixing means before the brake pedal is released. Based on this preliminary determination, the controller proactively controls the electric motor to apply torque in the opposite direction to external force, preventing the parking sprag from being not combined with the parking gear before the harmful effect can occur.
Solution Approach 2:
The controller applies torque from the electric motor in the opposite direction to external force before the brake pedal is released. This preliminary anti-action counteracts external force (such as gravity on slopes) that would otherwise cause the parking sprag to fail to combine properly with the parking gear, preventing impact and vibration.
2Reliability
If the electric motor applies torque greater than external force, then the parking sprag can be combined with the parking gear, but the wheel may rotate excessively causing impact when the sprag hits the sawtooth
Solution Approach 1:
The controller dynamically adjusts the torque parameter of the electric motor based on the combination state of the drive shaft fixing means. When the parking sprag is not combined, the controller increases motor torque above external force to ensure combination. When combined, the controller reduces motor torque to be less than external force to prevent excessive wheel rotation and impact on the parking sprag.
Solution Approach 2:
The system transitions from a static torque application to a dynamic torque control strategy. The controller continuously monitors the combination state and adjusts motor torque in real-time, changing from high torque (greater than external force) to ensure combination to low torque (less than external force) to maintain combination without causing impact.
3Ease of operation
If the brake pedal is released while a fellow passenger is alighting, then the passenger can exit the vehicle, but the wheel may rotate due to external force causing injury to the passenger
Solution Approach 1:
The controller determines the combination state of the drive shaft fixing means and calculates external force before the brake pedal is released. Based on this preliminary assessment, the controller proactively applies motor torque to ensure the parking sprag is combined with the parking gear, preventing wheel rotation that could injure passengers alighting or boarding.
Solution Approach 2:
The system provides beforehand protection by controlling the electric motor to apply torque in the opposite direction to external force before the brake pedal is released. This prior cushioning ensures the parking sprag is firmly combined with the parking gear, cushioning against external forces that would otherwise cause wheel rotation and potential passenger injury.
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
Effectively prevents impact and damage by controlling motor torque to align the parking sprag with the parking gear, enhancing safety during parking and reducing the risk of accidents, especially when passengers are boarding or alighting.
Implementation Method 1
controlling the electric motor such that a torque having a magnitude less than the external force is applied to the wheels in a direction opposite to the external force
Data Source
AI summary
A method of parking control for a vehicle equipped with an electric motor independent from a transmission includes calculating external force applied to wheels when predetermined conditions including shifting to a parking (P) stage are satisfied, determining whether a drive shaft fixing apparatus activated according to shifting to the P stage is combined, and controlling the electric motor such that a torque having a magnitude less than the external force is applied to the wheels in a direction opposite to the external force when the drive shaft fixing apparatus is determined to be combined.