Hydraulic Circuit Fault Detection via Pump Torque Monitoring
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Solution Overview
Problem
Direct drive transmissions in battery electric vehicles face issues with fluid leakage and blockage in hydraulic circuits, leading to inadequate cooling and lubrication of transmission components, which can result in damage if not detected promptly, and existing monitoring methods like fluid level sensors and pressure sensors increase costs and packaging constraints.
Innovation Solution
A method using an electric pump to monitor actual and desired pump torque, calculating a confidence factor, and comparing it to a threshold to detect fault conditions in the hydraulic circuit, allowing for early detection of fluid level issues and blockages without the need for additional costly sensors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If fluid level sensors and pressure sensors are used to monitor hydraulic circuit conditions, then detection accuracy is improved, but system cost and packaging complexity increase
Solution Approach 1:
The pump serves dual functions: it not only circulates hydraulic fluid for cooling and lubrication but also acts as its own monitoring device. By measuring the pump's actual power consumption and comparing it to expected values, the system self-diagnoses fluid level and blockage conditions without requiring separate sensors.
Solution Approach 2:
The patent replaces mechanical/electrical sensors with an electrical measurement approach. Instead of using physical sensors to detect fluid levels and pressure, the system uses electrical power measurements from the pump motor to infer hydraulic circuit conditions, substituting a complex sensing system with a simpler electrical measurement system.
2Device complexity
If no monitoring system is used to reduce cost and complexity, then device complexity is reduced, but transmission components may suffer damage from undetected fluid leakage and blockage
Solution Approach 1:
The system continuously monitors the pump's actual power consumption and compares it to expected values based on operating conditions. When deviations exceed thresholds, the system provides feedback to trigger fault detection and alert the operator, enabling continuous protection without complex additional hardware.
Solution Approach 2:
The patent monitors changes in electrical parameters (power consumption, current) of the pump to detect hydraulic faults. By tracking parameter variations over time and comparing them to expected ranges, the system reliably detects fluid level and blockage conditions while maintaining simple system architecture.
Data Source
AI summary
Method for detecting a fault condition in a vehicular hydraulic circuit during a drive cycle using an electric pump includes monitoring an actual pump torque and monitoring a desired pump torque. A current confidence factor is determined based on the actual pump torque and the desired pump torque. An average confidence factor is iteratively calculated based on the current confidence factor and previously determined confidence factors. The average confidence factor is compared to a fault condition threshold. An absence of the fault condition in the hydraulic circuit is detected when the average confidence factor is at least the fault condition threshold, and a presence of the fault condition in the hydraulic circuit is detected when the average confidence factor is less than the fault condition threshold.