Vacuum Sensor Signal Monitoring via Self-Diagnosis
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Solution Overview
Problem
Modern vehicle designs face issues where the required minimum braking effect is not achieved when the vacuum supply or vacuum brake booster fails, necessitating the activation of a hydraulic brake booster function, which requires continuous monitoring of the vacuum sensor signal without incurring significant structural effort or using redundant vacuum measurements.
Innovation Solution
Monitoring the operating states of the vacuum generator and brake booster to calculate an upper error limit based on a simplified physical model, detecting errors if the vacuum sensor signal exceeds this limit, and providing a driver warning when necessary, without requiring additional structural work or redundant measurements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a redundant vacuum sensor or additional vacuum signal processing is used to monitor the vacuum sensor signal, then the reliability of the hydraulic brake booster function is improved, but the device complexity and structural effort increase
Solution Approach 1:
The system uses existing sensors (vacuum sensor, accelerator pedal sensor, brake sensor) and available data (operating states of vacuum generator and brake booster) to perform self-diagnosis. The control unit calculates an expected vacuum signal based on the physical state of the system and compares it with the actual sensor signal, enabling the system to monitor itself without additional hardware
Solution Approach 2:
The control unit performs multiple functions: it controls the ESC system, monitors the vacuum sensor signal, calculates the expected vacuum signal based on operating states, and generates driver warnings. By making the control unit multi-functional, the patent avoids adding separate monitoring hardware while maintaining reliability
2Reliability
If the vacuum sensor signal is continuously monitored using existing methods, then the reliability of the hydraulic brake booster function is improved, but the manufacturing cost and structural complexity increase due to additional sensors or signal processing requirements
Solution Approach 1:
The monitoring system uses existing components and data sources already present in the vehicle (vacuum sensor, accelerator pedal sensor, brake sensor, control unit). The system performs self-diagnosis by comparing actual sensor readings with expected values calculated from the physical state of the vacuum system, eliminating the need for additional manufacturing costs
Solution Approach 2:
The control unit continuously compares the actual vacuum sensor signal with an expected vacuum signal calculated from the operating states of the vacuum generator and brake booster. This feedback mechanism enables continuous monitoring without additional hardware, as the system uses existing data streams to validate sensor functionality
Data Source
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Figure 3
AI summary
Disclosed is a method for monitoring the signal value of a vacuum sensor in a vacuum system of a vehicle. In said method: - a vacuum generator and a brake booster are provided in the vacuum system; - an upper error threshold (-p_vac_fehlerschranke) is calculated as a function of the operating states of the vacuum generator and the brake booster; and - an error is identified when the signal value of the vacuum sensor exceeds the current value of the error threshold.