Brake Booster Negative Pressure Sensor Verification
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Solution Overview
Problem
The existing methods for verifying the normal operation of a brake booster's negative pressure sensor are inadequate, leading to potential unintended braking forces due to high dependency on a single sensor, which increases manufacturing costs and weight, and fails to ensure functional safety.
Innovation Solution
A method and system that monitor values directly detected by the booster negative pressure sensor with values detected indirectly using sensors within a vehicle, such as intake-manifold and atmospheric pressure sensors, to determine conditions like low stuck-at, high stuck-at, and offset error conditions, and switch the low vacuum brake assist to a non-control state when malfunctions are detected.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If only the booster negative pressure sensor is utilized when determining negative pressure of the booster, then the system is simple and cost-effective, but there is high dependency on the sensor and possibility of unintended braking force during malfunction
Solution Approach 1:
The patent uses existing vehicle sensors (intake manifold pressure sensor, atmospheric pressure sensor, accelerator pedal position sensor) as intermediaries to indirectly verify the booster negative pressure sensor readings. These sensors serve as mediators to cross-check the vacuum pressure data without requiring direct additional sensing in the booster chamber.
Solution Approach 2:
The system continuously monitors and compares the booster negative pressure sensor readings with indirectly calculated vacuum pressure from other sensors. When discrepancies exceed thresholds, the system provides feedback by switching LVBA to non-control state, creating a closed-loop verification mechanism.
2Reliability
If more booster negative pressure sensors are added to secure robustness of verification, then functional safety is improved, but manufacturing cost and overall weight increase
Solution Approach 1:
The patent makes existing multi-functional sensors serve an additional verification function. The intake manifold pressure sensor and atmospheric pressure sensor, originally used for engine management, are now also used to verify booster negative pressure, eliminating the need for dedicated redundant sensors.
Solution Approach 2:
Instead of physically duplicating the booster negative pressure sensor, the system creates a virtual copy by calculating expected vacuum pressure from other sensor readings and comparing it with the actual sensor output, achieving redundancy through data replication rather than hardware duplication.
3Reliability
If the specification of the booster negative pressure sensor is changed to secure robustness of malfunction prevention, then functional safety is improved, but cost and weight of the sensor increase
Solution Approach 1:
The system enables self-verification where the sensor system monitors itself using available vehicle sensors. The booster negative pressure sensor's own readings are cross-checked against independently derived vacuum pressure calculations, allowing the system to detect sensor malfunctions without requiring more expensive high-specification sensors.
4Reliability
If a digital type sensor including a redundancy circuit is applied, then malfunction prevention is improved, but manufacturing cost and overall weight increase
Solution Approach 1:
The patent uses existing vehicle sensors as intermediaries to provide redundant verification without requiring complex digital sensors with built-in redundancy circuits. The intake manifold pressure sensor, atmospheric pressure sensor, and accelerator pedal position sensor collectively serve as external redundancy sources.
Data Source
AI summary
A method and a system for verifying normal operation of a negative pressure sensor of a brake booster is provided. The method and system verify whether the negative pressure sensor of the brake booster is in normal operation and the normal operation of the booster negative pressure sensor is detected by mutually verifying values measured by the booster negative pressure sensor and values measured by sensors that indirectly sense the booster negative pressure.