Brake Pressure Control Using Simulator Stroke Feedback
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Solution Overview
Problem
The existing brake control apparatus fails to maintain excellent pedal feeling and sufficient braking force when the brake environment changes, leading to potential deterioration in pedal feeling or insufficient braking force.
Innovation Solution
The brake control apparatus adjusts hydraulic pressure to increase braking force application in response to brake pedal stroke and continues to increase hydraulic pressure even after the stroke simulator's operation reaction force is restricted, ensuring consistent pedal feeling and braking force across varying brake environments.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the stroke simulator's stroke is restricted to maintain pedal feeling, then pedal feeling is improved, but braking force becomes insufficient when brake environment changes
Solution Approach 1:
The control unit continuously monitors the actual stroke simulator stroke and compares it with the target stroke. Based on this feedback, the control unit adjusts the hydraulic pressure through the pump to ensure the actual stroke matches the target stroke, thereby maintaining both pedal feeling and sufficient braking force under varying brake environments
Solution Approach 2:
The system dynamically adjusts the hydraulic pressure parameter in response to changes in brake environment. When the brake environment changes (such as brake fluid temperature or pad wear), the control unit modifies the hydraulic pressure to compensate, ensuring the stroke simulator maintains the correct stroke characteristics while providing adequate braking force
2Reliability
If hydraulic pressure is increased to maintain braking force, then braking force is improved, but pedal feeling deteriorates due to overboosting
Solution Approach 1:
The control unit uses feedback from stroke sensors to monitor the stroke simulator's actual stroke and compares it with the target stroke. This feedback mechanism allows the system to adjust hydraulic pressure precisely, increasing pressure only when necessary to maintain braking force while preventing excessive pressure that would cause overboosting and degrade pedal feeling
Solution Approach 2:
The system dynamically adjusts the hydraulic pressure based on real-time conditions rather than using a fixed pressure increase. The control unit modulates the pump output to match the actual braking requirements, ensuring pressure is increased only to the extent necessary for maintaining braking force without degrading pedal feeling
3Device complexity
If the stroke simulator stroke is limited, then device complexity is reduced, but adaptability to brake environment changes is worsened
Solution Approach 1:
The system replaces a mechanically complex adjustable stroke simulator with a simpler fixed-stroke simulator controlled by hydraulic pressure. The control unit uses electronic control and hydraulic pressure adjustment to achieve the adaptability that would otherwise require complex mechanical adjustments, thereby reducing device complexity while maintaining or improving brake environment adaptability
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
This approach allows for both excellent pedal feeling and secure braking force regardless of changes in the brake environment, preventing overboosting and insufficiency in braking force.
Implementation Method 1
controls a hydraulic pressure source 21 so as to increase a brake hydraulic pressure to generate in a braking force application portion 2 according to an increase in a stroke of a brake pedal 3
Implementation Method 2
a stroke of a stroke simulator 7 configured to generate an operation reaction force of the brake pedal is restricted
Data Source
AI summary
A control unit determines a final target wheel cylinder hydraulic pressure of a wheel cylinder based on a stroke-target wheel cylinder hydraulic pressure if an acquired simulator stroke position is smaller than a stroke limit, and determines the final target wheel cylinder hydraulic pressure of the wheel cylinder based on the stroke-target wheel cylinder hydraulic pressure and a master cylinder hydraulic pressure-target wheel cylinder hydraulic pressure if the acquired simulator stroke position is equal to or greater than the stroke limit.