Vehicle Brake Apparatus Abnormal Control for Smooth Pressure Transition
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Solution Overview
Problem
Existing brake apparatuses for vehicles face discomfort issues when switching from feedback control to feed forward control due to abrupt changes in brake fluid pressure, leading to an uncomfortable driving experience, especially when motor rotation number detection fails.
Innovation Solution
The brake apparatus includes a master cylinder, wheel brake devices, fluid pressure control valves, and an electric motor with feedback and feed forward control circuits, along with an abnormal control device that gradually increases brake fluid flow and control current to maintain consistent wheel cylinder pressure during control switching.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the control is switched from feedback control to feed forward control when motor rotation number cannot be detected, then the rotation control can continue, but the brake fluid pressure changes abruptly causing driver discomfort
Solution Approach 1:
The control device detects abnormalities in the rotation number detector and switches from feedback control to feed forward control in advance before the abnormality affects braking performance. By preparing the feed forward control parameters beforehand and switching proactively, the system maintains reliable rotation control while avoiding abrupt pressure changes that would cause driver discomfort.
Solution Approach 2:
The control device continuously monitors the motor rotation number and detects abnormalities in real-time. When an abnormality is detected, the feedback control is switched to feed forward control. The system uses feedback from the abnormality detection to trigger the control mode switch, ensuring reliable continuation of rotation control while maintaining driver comfort through proper transition management.
2Speed
If the electric motor is driven at high rotation number to increase discharge flow rate, then the responsiveness is improved, but the lifespan of the electric motor ends early
Solution Approach 1:
The control device dynamically adjusts the motor rotation number based on actual braking conditions and system state. Rather than maintaining a constantly high rotation number, the system optimizes the motor speed to match the required discharge flow rate, improving responsiveness when needed while extending motor lifespan through appropriate speed management during normal operation.
Solution Approach 2:
The control device changes the motor rotation number parameter according to braking requirements and system conditions. By adjusting this parameter dynamically rather than maintaining a fixed high value, the system achieves improved responsiveness when high flow rate is needed while reducing motor wear and extending lifespan during normal operating conditions.
Data Source
AI summary
A brake apparatus includes: a fluid pressure control valve; a fluid pressure pump; a feedback control circuit correcting a control power corresponding to a feedback control target rotation number of a motor and feed the corrected control power to a motor; a feed forward control circuit configured to feed, to the motor, a control power corresponding to a feed-forward control target rotation number of the motor; and an abnormal control fluid pressure generation control device, if a rotation number detector is abnormal, rotating the electric motor with the rotation number higher than the feedback control target rotation number by a margin rotation number, increases the brake fluid passing through the fluid pressure control valve, and changes the control current to be supplied to the fluid pressure control valve so that the wheel cylinder fluid pressure is not changed.