Brake Stroke Simulator Detection for Sudden Small Brake Inputs
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Solution Overview
Problem
The existing vehicle brake device has delayed responsiveness in detecting sudden brake operations, particularly small amount sudden operations, due to the performance of the stroke sensor, and the brake switch does not respond effectively to slight sudden operations, leading to inaccurate brake start determination.
Innovation Solution
A vehicle brake device incorporating a stroke simulator with a cylinder, piston, orifice, and pressure sensor that generates a reaction pressure, combined with a stroke sensor to determine the brake start by meeting threshold values for both reaction pressure and stroke, improving responsiveness and accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the stroke sensor is used to detect brake operation, then the detection responds similarly to usual gentle brake operation, but the responsiveness is delayed for sudden brake operation
Solution Approach 1:
The brake detection function is segmented into multiple independent detection paths: stroke sensor for gentle operations, brake switch for full-depression sudden operations, and reaction pressure sensor for small amount sudden operations. Each path handles specific detection scenarios, resolving the contradiction between reliability and speed by distributing detection responsibilities across multiple specialized sensors.
Solution Approach 2:
The reaction pressure sensor acts as an intermediary detection element that responds rapidly to sudden brake operations by detecting pressure changes in the brake liquid. This intermediary sensor bridges the gap between the slow-responding stroke sensor and the need for rapid detection, enabling timely brake start determination for small amount sudden operations.
2Speed
If the brake switch is used to detect sudden brake operation, then the responsiveness is improved for full depression, but it does not respond to small amount sudden operation
Solution Approach 1:
Different detection mechanisms are applied to different detection scenarios: the brake switch is optimized for full-depression sudden operations where high responsiveness is needed, while the reaction pressure sensor is used for small amount sudden operations where sensitivity to pressure changes is critical. This local quality approach ensures each sensor operates in its optimal detection range.
Solution Approach 2:
The reaction pressure sensor serves multiple detection functions: it detects both small amount sudden operations that the brake switch misses and provides supplementary detection for full depression operations. This multi-functionality expands the overall detection coverage of the brake detection system while maintaining high responsiveness.
3Measurement precision
If only stroke is used for brake start determination, then the accuracy is maintained, but the responsiveness is delayed for sudden operation
Solution Approach 1:
The reaction pressure sensor detects pressure changes that occur immediately upon brake operation initiation, providing preliminary detection before the stroke sensor can respond. This preliminary action enables early brake start determination for sudden operations, reducing determination delay while maintaining accuracy through subsequent confirmation by the stroke sensor.
Solution Approach 2:
The brake start determination unit integrates feedback from multiple sensors including the reaction pressure sensor and stroke sensor. The reaction pressure provides rapid initial feedback for sudden operations, while the stroke sensor provides continuous feedback for verification. This multi-source feedback mechanism resolves the contradiction by combining rapid detection with accurate verification.
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
Enhances the responsiveness of brake start determination for small amount sudden operations by utilizing reaction pressure and stroke as determination elements, ensuring accurate detection even when the brake switch does not respond, prioritizing responsiveness over accuracy.
Implementation Method 1
The orifice is formed in the fluid path. The pressure sensor is configured to detect a reaction pressure that is a liquid pressure of the brake liquid supplied to the liquid pressure chamber in a part on a supply-direction upstream side of the orifice in the fluid path.
Data Source
AI summary
A vehicle brake device includes a stroke simulator, a stroke sensor, and a brake start determination unit. The stroke simulator includes a cylinder, a piston, an orifice, and a pressure sensor. The cylinder defines a liquid pressure chamber to which a brake liquid is supplied via a fluid path. The piston slides in the cylinder by the brake liquid supplied to the liquid pressure chamber. The orifice is formed in the fluid path. The pressure sensor detects a reaction pressure. The stroke sensor is configured to detect the stroke. The brake start determination unit determines an operation of the brake operation member has been started in a case where the reaction pressure detected by the pressure sensor becomes equal to or greater than a first threshold value and the stroke detected by the stroke sensor becomes equal to or greater than a second threshold value.