CVT Pulley Pressure Control to Prevent Surge at Maximum Ratio
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Solution Overview
Problem
In belt-type continuously variable transmissions, surge pressure can occur when the stroke of the movable side driven pulley half body is stopped by abutment, leading to sudden changes in oil flow rates and potential system instability.
Innovation Solution
A control device that includes an oil pressure control system with a pressure regulating valve, a control valve, and a control part that detects actual oil pressure and adjusts the instructed oil pressure to prevent surge pressure by lowering it when conditions such as maximum gear ratio, low oil discharge amount, or high shift speed are met, ensuring the second port of the pressure regulating valve is not blocked.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the movable side driven pulley half body is abutted against the end before the movable side drive pulley half body, then the gear ratio can be changed to maximum, but the stroke of the movable side drive pulley half body is forcibly stopped at the abutting position causing surge pressure
Solution Approach 1:
The control device performs preliminary action by detecting when the driven pulley approaches its abutting position and preemptively controlling the drive pulley to prevent simultaneous abutment. The control part monitors the position of the movable side driven pulley half body and adjusts the oil pressure to the drive pulley accordingly, preventing the surge pressure condition before it occurs.
Solution Approach 2:
The system implements feedback control by continuously monitoring the actual oil pressure and comparing it with the instructed oil pressure. When a discrepancy is detected that indicates approaching abutment conditions, the control part adjusts the control valve to modify the oil pressure supplied to the drive pulley, creating a closed-loop control system that prevents surge pressure.
2Manufacturing precision
If the stroke of the movable side driven pulley half body is stopped by abutment, then the gear ratio reaches maximum, but sudden changes in oil flow rates occur causing surge pressure
Solution Approach 1:
The control device acts as an intermediary between the driven pulley position and the drive pulley oil pressure. When the driven pulley approaches its abutting position, the control part mediates by adjusting the oil pressure to the drive pulley, preventing the sudden flow rate changes that would otherwise occur when both pulleys abut simultaneously. This intermediary control smooths the transition and prevents surge pressure.
Solution Approach 2:
The system dynamically changes the oil pressure parameter supplied to the drive pulley based on the position of the driven pulley. By monitoring the driven pulley position and adjusting the drive pulley oil pressure accordingly, the system modifies the pressure parameter in real-time to prevent the conditions that lead to surge pressure while maintaining precise gear ratio control.
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
Effectively prevents surge pressure occurrences by adjusting oil pressure instructions based on gear ratio, oil discharge, and shift speed, maintaining system stability and ensuring sufficient starting performance.
Implementation Method 1
a pressure regulating valve (152b) that regulates an oil pressure of oil supplied from an oil supply source (120, 130) to a cylinder chamber (9) of the driven pulley (8)
Implementation Method 2
an oil pressure detection part (162) that detects an actual oil pressure of oil supplied from the pressure regulating valve (152b) to the cylinder chamber (9)
Data Source
AI summary
Provided is a control device for a continuously variable transmission, which is capable of effectively preventing occurrence of surge pressure due to a stroke of a driven pulley being stopped by abutment. The control device for the continuously variable transmission includes a pressure regulating valve regulating an oil pressure of oil supplied from an oil supply source to a cylinder chamber of the driven pulley, a control valve controlling the pressure regulating valve, and a control part controlling the control valve. If the control part determines that a gear ratio of the continuously variable transmission is maximum, as a first condition, when an instructed oil pressure of the control valve for the pressure regulating valve is larger than an oil pressure of oil supplied from the pressure regulating valve to the driven pulley, a control for lowering the instructed oil pressure is performed.