Transmission Hydraulic Fault Diagnosis Using a Shared Clutch Pressure Sensor
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Solution Overview
Problem
Existing hydraulic systems for dual clutch transmissions rely on expensive sensors to diagnose pressure accumulator faults, which is inefficient and costly.
Innovation Solution
A diagnosis module within the electronic control unit that uses a pressure sensor in a fault-free clutch path to diagnose gear selector and pressure accumulator faults by analyzing pressure gradients and comparing them to reference values, reducing the need for additional sensors and enhancing measurement accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a pressure sensor is installed in each gear selector path to diagnose leakage, then measurement precision is improved, but device complexity and cost increase
Solution Approach 1:
The pressure sensor in the clutch path is designed to serve multiple functions: it diagnoses both clutch path leakage and gear selector path leakage. By using the same sensor for different diagnostic purposes through sequential operating modes, the system avoids installing separate sensors for each function, thereby reducing device complexity while maintaining measurement precision.
Solution Approach 2:
The system uses its own existing pressure sensor and hydraulic components to perform self-diagnosis of the gear selector path. By activating the gear selector valve and observing pressure changes through the existing sensor, the system enables itself to detect leaks without requiring additional diagnostic equipment.
2Reliability
If multiple pressure sensors are installed to monitor all paths, then reliability is improved, but manufacturing cost increases
Solution Approach 1:
The single pressure sensor performs multiple diagnostic functions by operating in different modes. First, it monitors clutch path pressure for clutch leakage detection. Then, by activating the gear selector valve, it monitors gear selector path pressure for leakage detection. This multi-functional approach ensures reliable monitoring of both paths without the need for multiple sensors, thereby reducing manufacturing costs while maintaining operating security.
Solution Approach 2:
The control unit acts as an intermediary that coordinates the diagnostic process. It activates the gear selector valve sequentially and processes the pressure signals from the existing sensor to determine the leakage status of the gear selector path, enabling reliable diagnosis without additional hardware investment.
3Device complexity
If a pressure sensor in a clutch path is used to diagnose gear selector leakage, then device complexity is reduced, but measurement precision may deteriorate
Solution Approach 1:
The diagnostic system uses periodic action by sequentially switching between different diagnostic modes. The gear selector valve is activated only during the diagnostic phase, allowing the pressure sensor to measure pressure changes in the gear selector path temporarily. This periodic activation ensures that the existing sensor can accurately capture pressure variations for leakage detection without requiring continuous monitoring hardware in all paths.
Solution Approach 2:
Before diagnosing gear selector leakage, the system performs preliminary diagnostics to identify a fault-free clutch path. This preliminary action ensures that the pressure sensor is positioned in a reliable location, thereby maintaining measurement precision even though the sensor is shared across different paths.
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 allows for reliable and cost-effective diagnosis of hydraulic system faults, ensuring operational security with reduced sensor technology expenses and improved measurement accuracy.
Implementation Method 1
a pressure sensor arranged in the at least one clutch path, by which a hydraulic pressure applied at the clutch hydraulic cylinder can be detected
Implementation Method 2
a charging hydraulic pump, which delivers hydraulic fluid to the hydraulic system in a charging process in order to boost the accumulator pressure
Implementation Method 3
a third evaluating unit can detect a pressure gradient of the accumulator pressure curve via the pressure sensor and compare it to a reference pressure gradient
Data Source
AI summary
A hydraulic system for an automatic transmission of a motor vehicle, with which hydraulic cylinders of at least one clutch and of gear selectors can be actuated, which hydraulic system has a pressure accumulator for providing an accumulator pressure in the hydraulic system, wherein a clutch valve that can be actuated by the control unit is arranged in a clutch path leading from the pressure accumulator to the clutch hydraulic cylinder.