Solenoid Valve Current Signature Checking for Brake Fault Detection
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Solution Overview
Problem
Existing methods for checking the functionality of solenoid valves in brake systems, especially in highly automated driving systems, face challenges in detecting faults without causing hydraulic load and noise, vibration, and harshness issues, and require complex active tests.
Innovation Solution
A method that measures and analyzes the electric current during the actuation of a solenoid valve to assess its functionality directly, without activating the hydraulic pressure generator, by identifying specific characteristics in the current curve or its rate of variation, allowing for a passive test during normal driving conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If active tests with pressure generator activation are used to check valve functionality, then measurement precision is improved, but hydraulic load increases and NVH issues occur
Solution Approach 1:
The patent replaces the mechanical/hydraulic testing approach with an electrical measurement approach. Instead of activating the pressure generator and measuring hydraulic pressure responses, the system measures the electrical current through the coil during valve actuation. The current characteristics (magnitude, rise time, decay) directly reflect the armature movement and valve functionality, eliminating the need for hydraulic system activation and avoiding associated NVH and load issues.
Solution Approach 2:
The patent introduces electrical current measurement as an intermediary parameter to assess valve functionality. Rather than directly measuring hydraulic pressure or mechanical valve position, the system uses the electrical current through the coil as a proxy indicator. The current characteristics serve as an intermediary that reflects the magnetic field strength, armature movement, and ultimately valve operation, providing indirect but accurate functionality assessment without mechanical activation.
2Reliability
If active tests are performed to assess valve functionality, then reliability of fault detection is improved, but device complexity increases
Solution Approach 1:
The patent enables the valve system to self-diagnose its functionality by monitoring its own electrical current characteristics during normal operation. The control unit analyzes the current through the coil during actuation cycles, and the valve effectively tests itself without requiring external test equipment or complex active test sequences. This self-service approach maintains high reliability while minimizing system complexity.
Solution Approach 2:
The patent extracts the essential functionality assessment from the complex hydraulic test sequence and isolates it to a simple electrical current measurement. By taking out only the necessary measurement (current through the coil) and analyzing its characteristics, the system achieves reliable fault detection without requiring the full hydraulic system activation and complex pressure measurement infrastructure.
3Ease of operation
If indirect methods measuring hydraulic pressure build-up are used, then ease of operation is improved, but measurement precision deteriorates
Solution Approach 1:
The patent replaces indirect hydraulic pressure measurement with direct electrical current measurement. Instead of monitoring hydraulic pressure build-up as an indirect indicator of valve function, the system directly measures the electrical current through the coil during actuation. This electrical approach provides more precise and direct information about valve functionality while maintaining ease of operation through automated current analysis.
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 enables reliable fault detection in solenoid valves without increasing hydraulic load or causing NVH issues, simplifying the testing process and reducing costs by eliminating the need for active tests, while ensuring high confidence in valve functionality assessment.
Implementation Method 1
the armature, on actuation of the valve, being moved by a magnetic field of the coil
Implementation Method 2
the armature being moved by a magnetic field of the coil
Implementation Method 3
This reduction of the air gap gives rise to a variation of the magnetic susceptibility in the coil-armature circuit and produces a current curve
Data Source
AI summary
A method checks a functionality of a solenoid valve for a brake system in a motor vehicle. The solenoid valve includes an armature and a coil. The armature, on actuation of the solenoid valve, is moved by a magnetic field of the coil, reducing an air gap of the solenoid valve defined by a position of the armature. The method includes measuring an electric current during the actuation of the solenoid valve, analysing a characteristic of the electric current during the actuation of the solenoid valve, and assessing the functionality of the solenoid valve based on the analysis of the characteristic of the electric current.