CVT Pulley Pressure Control for Hydraulic Oscillation Mitigation
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Solution Overview
Problem
Current continuously variable transmission (CVT) systems face hydraulic pressure instability issues during oscillating conditions, leading to potential hardware damage and drivability concerns due to uncontrolled pressure oscillations in pulley systems.
Innovation Solution
A CVT control system that includes a pulley pressure control system capable of recognizing and mitigating pressure oscillations by measuring pulley pressures, calculating a pressure oscillation energy value, applying filtering to reject specific frequencies, and switching between closed-loop and open-loop control based on predetermined thresholds and time durations to manage pulley pressures effectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If closed-loop control is used to control pulley pressure for precise ratio control, then manufacturing precision is improved, but pressure oscillations occur causing stability deterioration
Solution Approach 1:
The control system dynamically switches between closed-loop and open-loop control modes based on detected pressure oscillation conditions. When oscillations are detected, the system transitions from closed-loop to open-loop control to eliminate the oscillations, then returns to closed-loop control when stable, allowing the system to adapt its control strategy in real-time
Solution Approach 2:
The system uses feedback from pressure sensors to detect oscillations and triggers a control mode transition. The feedback mechanism monitors pressure conditions continuously and initiates the switch from closed-loop to open-loop control when oscillation thresholds are exceeded, preventing stability issues while maintaining precision during normal operation
2Stability of the object's composition
If pressure oscillations are mitigated by switching to open-loop control, then pressure stability is improved, but system responsiveness deteriorates
Solution Approach 1:
The control mode is dynamically adjusted based on real-time pressure conditions. The system remains in responsive closed-loop control during normal operation and only switches to open-loop when oscillations are detected, minimizing the time spent in less responsive mode while maintaining stability when needed
Solution Approach 2:
The system periodically monitors pressure conditions and switches control modes based on detected oscillation patterns. This periodic checking ensures rapid detection of oscillation conditions and quick transition to open-loop control, minimizing disruption to system responsiveness
3Stability of the object's composition
If pressure oscillation detection and control mode switching is implemented, then pressure stability is improved, but device complexity increases
Solution Approach 1:
The control system automatically detects pressure oscillations and self-manages the transition between control modes without external intervention. The system monitors its own pressure conditions and autonomously switches between closed-loop and open-loop control, reducing the need for additional complex external control mechanisms
Data Source
AI summary
A continuously variable transmission control system includes a continuously variable transmission (CVT) including a primary variator pulley and a secondary variator pulley each including a set of pulley members defining a variable-width gap, and a flexible member positioned within the variable-width gap and movable to define a CVT ratio. The transmission control system also includes a primary pulley valve controlling a primary pulley pressure of a fluid to the primary variator pulley, a secondary pulley valve controlling a secondary pulley pressure of the fluid to the secondary variator pulley; and a pulley pressure control system configured to recognize and mitigate pressure oscillations occurring in the primary pulley pressure or in the secondary pulley pressure.