Brake Fluid Level Sensor Functional Testing via Pump Actuation
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Solution Overview
Problem
Existing electromechanical filling level monitoring devices in motor vehicles can fail to detect a low brake fluid level if the float is mechanically blocked or the sensor contacts stick, leading to potential hydraulic circuit contamination and brake pressure buildup without warning, especially in power brake systems.
Innovation Solution
A method is introduced to test the functionality of the filling level monitoring device by intentionally lowering the fluid level in a pressure medium chamber and observing the signal response, using a pressure medium delivery device to simulate a decrease in fluid level and assess the device's functionality through signal changes, allowing for timely detection of malfunctions and prevention of undetected failures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the float is mechanically blocked or sensor contacts stick, then the device structure remains simple, but the reliability of level detection deteriorates
Solution Approach 1:
The patent implements preliminary functional testing of the level monitoring device by using the pressure medium delivery device to intentionally lower the fluid level before normal operation begins. This proactive approach detects potential float blocking or contact sticking issues before they cause detection failures, thereby improving reliability without requiring complex additional testing equipment.
Solution Approach 2:
The pressure medium delivery device, which is already part of the brake system, is given an additional function: serving as a level monitoring test device. By controlling this existing device to deliver pressure medium and lower the fluid level, the system achieves functional testing capability without adding separate dedicated testing equipment, thus improving reliability while minimizing increased device complexity.
2Object-affected harmful factors
If the filling level monitoring device is not tested, then the device complexity remains low, but the harmful factors such as hydraulic circuit contamination increase
Solution Approach 1:
The system performs self-diagnosis by using its own pressure medium delivery device to test the level monitoring functionality. The control unit automatically controls the delivery device to lower the fluid level and monitors the sensor response, enabling the system to detect potential failures that could lead to hydraulic circuit contamination without requiring external testing equipment or complex additional systems.
Solution Approach 2:
The control unit monitors the signal from the filling level monitoring device during the testing process. When the fluid level is lowered by the pressure medium delivery device, the control unit expects a specific sensor response. If the sensor fails to respond appropriately, the system generates a warning signal, providing feedback that detects potential contamination risks before they materialize.
3Measurement precision
If the fluid level is not intentionally lowered for testing, then the operation time is shorter, but the detection precision of device malfunctions deteriorates
Solution Approach 1:
The patent implements periodic functional testing of the level monitoring device at predetermined intervals after vehicle start-up. The control unit automatically initiates the testing sequence by controlling the pressure medium delivery device to lower the fluid level and monitor sensor response. This periodic approach ensures high malfunction detection precision while limiting the time loss to specific intervals rather than continuous testing.
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 method ensures that functional failures of the filling level monitoring device are promptly detected, preventing potential hydraulic circuit contamination and enabling timely warnings to the driver, thus ensuring the safety of the brake system by differentiating between proper and malfunctioning device responses.
Implementation Method 1
a pressure medium delivery device, which is usually present in a hydraulic circuit anyway. In particular, brake circuits of electronically slip-controllable vehicle brake systems are equipped with pressure generators or pressure medium delivery devices
Implementation Method 2
a float which is arranged in the brake fluid reservoir and carries a magnet. Depending on the filling level of the brake fluid reservoir, this float moves along a sensor element equipped with a switching contact, for example a reed contact. As soon as the fill level drops below a minimum mark, the magnet in the sensor element triggers a switching process
Implementation Method 3
The pumped pressure medium can flow back into the first pressure chamber automatically, i.e. without pump support, via the compensating opening
Data Source
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AI summary
The invention relates to a method for the functional testing of an electromechanical level-monitoring device (222). The aim of the invention is to test the plausability of the signal emitted by a level-monitoring device (222) of a first pressure-medium chamber (214). To this end, said level-monitoring device (222) is force-actuated from time to time. According to the invention, said force actuation is carried out as a result of a pressure-medium-conveying unit (234) being controlled in a pressure-medium circuit (232) comprising the first pressure-medium chamber (214), over a pre-defined period of time. This supplies a pressure medium via a pressure-medium connection (232) from the first pressure-medium chamber (214) fitted with the level-detection device (222) into a second pressure-medium chamber (216). On the basis of the signal course emitted by the level-monitoring device (222), the operational reliability of the level-monitoring device (222) is defined in the electronic control appliance (230).