Transmission Hydraulic Circuit Diagnostics Using Clutch Pressure Sensing
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Solution Overview
Problem
Existing hydraulic systems for dual-clutch transmissions require complex sensor systems to detect malfunctions in the accumulator charging valve, which can be prone to errors due to issues like spring failures or soil deposits, leading to inaccurate pressure threshold switching.
Innovation Solution
Incorporating a diagnostic module with a pressure sensor in the clutch path that can detect accumulator pressure during switchover times and an analysis unit to estimate proper switchover times, along with a valve spread diagnosis to determine actual valve spread, allowing for fault detection and diagnosis of accumulator pressure and leakage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If complex sensor systems are used to detect accumulator charging valve malfunction, then detection capability is improved, but device complexity increases
Solution Approach 1:
The existing pressure sensor in the clutch path is made multi-functional by using it both for its original function (monitoring clutch hydraulic pressure) and for the new function (detecting accumulator pressure during switchover times). This eliminates the need for separate dedicated sensors while maintaining fault detection capability.
Solution Approach 2:
The existing pressure sensor serves itself by being reused for multiple purposes. Instead of requiring additional components, the system leverages the already-present sensor to perform both clutch pressure monitoring and accumulator pressure detection, making the system self-sufficient.
2Measurement precision
If dedicated pressure sensors are added for accumulator monitoring, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The pressure sensor is designed to serve multiple functions: monitoring clutch hydraulic pressure during normal operation and detecting accumulator pressure during switchover times. This multi-functionality maintains measurement precision without adding dedicated sensors.
Solution Approach 2:
The control unit acts as an intermediary by processing pressure readings from the existing sensor and determining switchover times. It correlates the pressure data with expected switchover timing to infer accumulator pressure conditions without requiring direct accumulator pressure measurement hardware.
3Measurement precision
If multiple dedicated sensors are used for valve spread diagnosis, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The existing pressure sensor is used for multiple diagnostic purposes including clutch pressure monitoring, accumulator pressure detection during switchover, and valve spread diagnosis. This single sensor performs what would traditionally require multiple dedicated sensors.
Solution Approach 2:
The system uses feedback from the pressure sensor readings combined with timing information from switchover events to calculate valve spread. The control unit continuously monitors pressure changes during switchover and compares them against expected values to diagnose valve condition.
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 solution simplifies fault detection by using existing sensors for accumulator pressure monitoring, reducing the need for complex systems and improving accuracy in diagnosing valve and accumulator issues, thereby enhancing the reliability of the hydraulic system.
Implementation Method 1
the electronic control unit can be assigned a pressure sensor, with which the hydraulic pressure applied to the clutch hydraulic cylinder can be detected
Implementation Method 2
Torque is transmitted via one of two clutches, which connects the two sub-transmissions to the drive. The clutches and the gear selectors for engaging the gears are actuated via hydraulic cylinders, which are controlled hydraulically via a hydraulic system.
Implementation Method 3
a pressure accumulator for supplying an accumulator pressure in the hydraulic system
Data Source
AI summary
A hydraulic system for an automatic transmission of a motor vehicle, including a high pressure circuit in which a pressure accumulator, at least one clutch and a gear selector are connected, and comprising a low pressure circuit for cooling the clutch, wherein the high pressure circuit and the low pressure circuit have at least one hydraulic pump that can be driven by an electric motor, and including a control unit that actuates the electric motor of the hydraulic pump when a pressure accumulator charging requirement is detected, wherein the high and low pressure circuits are connected via a bypass line to an integrated accumulator charging valve.