Simulator-Equipped Hydraulic Brake Mode Transition Control
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Solution Overview
Problem
The existing simulator-equipped hydraulic brake systems experience a sudden 'sinking' or 'slumping' of the brake actuating element/brake pedal when transitioning from fallback mode to simulator mode, leading to uncomfortable braking experiences for drivers, often necessitating operation in simulator mode from the start to avoid this issue.
Innovation Solution
A control device that compares the current displacement path and master brake cylinder pressure with specified boundaries, implementing an intermediate mode to gradually transition the system from fallback to simulator mode, minimizing the compensating movement of the brake pedal by controlling the simulator and brake circuit isolating valves based on predefined characteristic curves and target opening times.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the brake system transitions directly from fallback mode to simulator mode by opening the simulator isolating valve and closing the brake circuit isolating valve, then the system can switch operating modes, but the brake actuating element experiences sudden sinking or slumping causing driver discomfort
Solution Approach 1:
The transition process is segmented into multiple phases: an intermediate mode with phased valve switching, where the simulator isolating valve opens gradually and the brake circuit isolating valve closes in stages, rather than simultaneous abrupt switching. This segmentation prevents sudden brake fluid volume changes that cause pedal sinking.
Solution Approach 2:
An intermediate operating mode is introduced as a mediator between fallback mode and simulator mode. During this intermediate phase, both isolating valves are temporarily in transitional states, allowing brake fluid to redistribute gradually through alternative pathways, thus preventing the direct volume displacement that causes pedal slumping.
2Ease of operation
If the system operates in simulator mode from the beginning to avoid pedal sinking, then braking comfort is improved, but operational flexibility is reduced when initial conditions do not meet simulator mode requirements
Solution Approach 1:
The system dynamically adapts its operating mode based on real-time conditions. The control device monitors brake fluid pressure, temperature, and flow conditions, and automatically transitions between fallback mode, intermediate mode, and simulator mode to maintain optimal braking performance and pedal stability under varying operational conditions.
Solution Approach 2:
The system changes operational parameters (valve positions, brake fluid flow paths, pressure distribution) to transition between different operating modes. By adjusting these parameters gradually through the intermediate mode, the system maintains pedal stability while adapting to different initial conditions and operational requirements.
3Adaptability or versatility
If the brake circuit isolating valve is closed during fallback mode to decouple wheel brake cylinders, then the system operates in fallback mode, but brake fluid volume already pressed out is lost causing displacement path changes
Solution Approach 1:
Before closing the brake circuit isolating valve to enter fallback mode, the control device预先 opens the simulator isolating valve partially or maintains alternative fluid pathways, so that brake fluid volume is not completely trapped or lost. This preliminary action ensures that when transitioning back to simulator mode, the brake pedal displacement can be recovered smoothly without sudden sinking.
Data Source
AI summary
A control device operates a vehicle hydraulic brake system (a) in a fallback mode during which a simulator isolating valve is closed and a brake circuit isolating valve is open, (b) in a simulator mode during which the simulator isolating valve is open and the brake circuit isolating valve is closed, and (c) to transition from the fallback mode to the simulator mode using an intermediate mode in which, at least once, the simulator isolating valve and the at least one brake circuit isolating valve are simultaneously closed for a first time interval, the simulator isolating valve and the at least one brake circuit isolating valve are simultaneously open for a second time interval, and the simulator isolating valve is closed for a third time interval, while the at least one brake circuit isolating valve is open at least part of the time during the third time interval.