DCT Line Pressure Estimation Without a Pressure Sensor
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Solution Overview
Problem
Existing double clutch transmission (DCT) systems require a line pressure detector to maintain appropriate line pressure, which increases costs and is prone to malfunction, necessitating a relief valve for protection against detector failure.
Innovation Solution
A line pressure control method using a linear regression model estimates line pressure based on state variables like clutch torque, solenoid positions, and pump operation, allowing the electric oil pump to be driven at appropriate times to maintain stable line pressure without a line pressure detector, thereby reducing system costs and eliminating the need for a relief valve.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a line pressure detector is installed to measure line pressure, then line pressure can be accurately measured and maintained, but system cost increases and the system becomes more complex
Solution Approach 1:
The patent replaces the mechanical line pressure detector with a mathematical estimation model (linear regression model) that calculates line pressure based on electrical current data from the oil pump motor. This substitution eliminates the need for physical pressure sensing components while maintaining the ability to monitor and control line pressure, thereby reducing system complexity and cost.
Solution Approach 2:
The patent introduces electrical current data as an intermediary parameter to indirectly represent line pressure conditions. Instead of directly measuring pressure, the system uses current consumption patterns of the oil pump motor as a proxy indicator, which correlates with line pressure levels. This intermediary approach allows pressure monitoring without requiring direct pressure sensing hardware.
2Reliability
If a line pressure detector is installed to maintain line pressure, then line pressure control is improved, but system cost increases due to additional components
Solution Approach 1:
The patent replaces the mechanical line pressure detector with a mathematical estimation model (linear regression model) that calculates line pressure based on electrical current data from the oil pump motor. This substitution eliminates the need for physical pressure sensing components while maintaining the ability to monitor and control line pressure, thereby reducing system complexity and cost.
Solution Approach 2:
The patent creates a virtual copy of the line pressure measurement function through software-based linear regression modeling. Instead of using a physical detector, the system replicates the pressure measurement capability through mathematical calculations based on readily available electrical current data, effectively copying the measurement function in a virtual rather than physical form.
3Reliability
If a relief valve is added to protect against detector failure, then system reliability improves, but device complexity and cost increase
Solution Approach 1:
The patent replaces the mechanical line pressure detector with a mathematical estimation model (linear regression model) that calculates line pressure based on electrical current data from the oil pump motor. This substitution eliminates the need for physical pressure sensing components while maintaining the ability to monitor and control line pressure, thereby reducing system complexity and cost.
Solution Approach 2:
The patent enables the hydraulic system to self-monitor and self-regulate line pressure using existing electrical current data from the oil pump motor. The control unit continuously estimates line pressure through the linear regression model and automatically adjusts pump operation accordingly, allowing the system to service itself without requiring additional protective components like relief valves for detector failure.
Data Source
AI summary
A line pressure control method for a double clutch transmission (DCT) includes estimating a line pressure, which decreases with stoppage of an electric oil pump, based on a linear regression model using state variables of the DCT that are related to a line pressure change, and driving the electric oil pump when the line pressure estimated based on the linear regression model reaches a predetermined lower limit.