Electric Motor Brake Control for Rapid Torque Reduction
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Solution Overview
Problem
In vehicles equipped with electric/mechanical braking systems, the inertia of the electric motor makes it difficult to immediately reduce braking torque in response to decompression instructions, leading to excessive wheel slip and compromised stability, especially for the rear wheel.
Innovation Solution
A vehicle brake control device that includes electric braking means for the rear wheel, wheel speed acquisition, slip state calculation, and control means to adjust the target energization amount of the electric motor based on the slip state of the rear and front wheels, implementing sudden-stop control to rapidly decelerate the electric motor and reduce braking torque, thereby suppressing excessive slip.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If electric motor is used for braking, then braking force can be generated, but the inertia of the electric motor makes it difficult to immediately reduce braking torque in response to decompression instructions
Solution Approach 1:
The control device predicts future wheel slip states based on current vehicle state and driver input, and proactively adjusts the target energization amount before excessive slip occurs. This preliminary action compensates for the electric motor's inertia, enabling the braking torque to be reduced more quickly in response to decompression instructions.
Solution Approach 2:
The control device dynamically adjusts the target energization amount based on predicted wheel slip states, transitioning from static braking control to dynamic adaptive control. This allows the system to optimize the balance between generating sufficient braking torque and enabling rapid torque reduction when needed.
2Ease of operation
If decompression instruction is issued to reduce braking torque, then wheel slip should be reduced, but the electric motor keeps moving at high speed causing delay in braking torque reduction
Solution Approach 1:
The control device performs preliminary adjustment of the target energization amount based on predicted wheel slip states before the actual slip occurs. This anticipatory control reduces the time delay in braking torque reduction by preparing the motor for upcoming decompression needs.
Solution Approach 2:
The control device uses feedback from wheel speed sensors and vehicle state data to continuously monitor and adjust the target energization amount. This closed-loop feedback mechanism ensures that braking torque is reduced timely in response to actual wheel slip conditions.
3Reliability
If the target energization amount is adjusted based on rear wheel slip state, then rear wheel slip can be suppressed, but the front wheel slip may increase due to braking force distribution
Solution Approach 1:
The control device applies different control strategies to different wheels based on their individual slip states. The target energization amount for the rear wheel is adjusted according to rear wheel slip predictions, while front wheel braking force is independently managed, allowing localized optimization of slip suppression while maintaining overall vehicle stability.
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 solution allows for immediate and effective reduction of braking torque on the rear wheel, preventing excessive slip and maintaining vehicle stability by decelerating the electric motor rapidly in response to driver input, even when the slip suppression control is initiated.
Implementation Method 1
electric braking means (BRK) for generating a braking torque of a rear wheel (WH[r*]) of a vehicle through intermediation of an electric motor (MTR)
Implementation Method 2
wheel speed acquisition means (VWA) for acquiring speeds (Vwa[**]) of four wheels (WH[**]) of the vehicle
Data Source
AI summary
A vehicle brake control device generates rear wheel braking torque by an electric motor by pressing a friction member against a rotating member rotating together with the rear wheel, reduces rear wheel braking torque by controlling the electric motor based on a target energization amount calculated from a slip state quantity of the rear wheel, and rapidly stops electric motor rotation motion based on an adjusted target energization amount calculated from the target energization amount and a slip state quantity of a front wheel.