Dual-Clutch Transmission Line Pressure Control Using Model-Based Estimation
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Solution Overview
Problem
Dual-clutch transmissions (DCTs) face challenges in minimizing energy consumption and reducing costs associated with hydraulic pressure generation, while ensuring stable hydraulic pressure supply to clutches, often requiring unnecessary hydraulic pressure sensors.
Innovation Solution
A line pressure control method that uses an electric oil pump controlled by a controller, which estimates line pressure decreases using a pressure accumulator model, learns parameters, and adjusts pump operation to maintain optimal pressure within predetermined limits, eliminating the need for a hydraulic pressure sensor and minimizing energy consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a hydraulic pressure sensor is used to monitor line pressure, then measurement precision is improved, but device complexity and cost increase
Solution Approach 1:
The patent replaces the mechanical hydraulic pressure sensor with a model-based estimation system. The controller estimates line pressure by calculating the force balance between the pressure accumulator spring and the hydraulic pressure acting on the piston, substituting physical sensing with computational modeling.
Solution Approach 2:
The pressure accumulator serves as an intermediary element that enables pressure estimation without direct sensing. By modeling the relationship between accumulator spring force and hydraulic pressure through the piston area, the system indirectly determines line pressure without requiring a sensor.
2Stability of the object's composition
If the electric oil pump operates continuously to maintain hydraulic pressure, then stability of hydraulic pressure supply is improved, but energy consumption increases
Solution Approach 1:
The patent implements periodic pump operation by controlling the electric oil pump to operate only when the estimated line pressure falls below a predetermined threshold. The pump is activated to increase pressure, then shut off when the upper threshold is reached, creating a periodic on-off control cycle that reduces energy consumption while maintaining pressure stability.
Solution Approach 2:
The system uses feedback control by continuously estimating line pressure and comparing it against predetermined thresholds. The controller adjusts pump operation based on this feedback, activating the pump only when pressure drops below the lower threshold and deactivating it when pressure reaches the upper threshold.
3Productivity
If the electric oil pump is driven at high power to quickly increase line pressure, then productivity is improved, but energy consumption increases
Solution Approach 1:
The patent applies partial action by driving the electric oil pump only to the extent necessary to reach the upper pressure threshold, rather than continuously operating at maximum power. The pump operates intermittently and at variable power levels, providing just enough pressure increase to maintain system requirements while minimizing energy waste.
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 reduces energy consumption, improves fuel efficiency, and ensures stable hydraulic pressure supply to clutches, thereby increasing vehicle travel distance while minimizing costs by eliminating the need for hydraulic pressure sensors.
Implementation Method 1
a pressure accumulator (7) mounted in the hydraulic pressure line
Implementation Method 2
an electric oil pump
Data Source
AI summary
A line pressure control method for a dual-clutch transmission (DCT), may include a hydraulic-pressure-decreasing operation of interrupting, by a controller, the supply of current to an electric oil pump and estimating a decrease in a line pressure using a line pressure model based on a pressure accumulator mounted in a hydraulic pressure line, a pump-driving operation of, when the estimated line pressure is equal to or less than a predetermined lower-limit value, driving, by the controller, the electric oil pump, and a hydraulic-pressure-increasing operation of determining, by the controller, the line pressure based on the current supplied to the electric oil pump and to determine whether the determined line pressure is equal to or greater than a predetermined upper-limit value.