CVT Line Pressure Control for Hydraulic Pulsation
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Solution Overview
Problem
Conventional control systems for continuously variable transmissions fail to effectively suppress vehicle behavior variations and unnatural driver feelings due to hydraulic pressure pulsation, leading to increased slippage and instability.
Innovation Solution
A control device for continuously variable transmissions that includes a line pressure generating means, a pilot valve to regulate pilot pressure, a control unit to manage solenoid valves, an oil vibration sensing mechanism, and a line pressure increase mechanism to stabilize hydraulic pressure by increasing line pressure when oil vibration is detected, thereby preventing excessive hydraulic pressure and reducing driver discomfort.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the target supply hydraulic pressure of the clamping pressure is increased to prevent belt slippage, then belt slippage is prevented, but hydraulic pressure pulsation cannot be decreased and vehicle behavior variation is not suppressed
Solution Approach 1:
The control device performs preliminary action by increasing the line pressure before the hydraulic pressure pulsation can cause significant vehicle behavior variation. The oil vibration sensing means detects early signs of pulsation, and the line pressure increase means preemptively raises the pressure to stabilize the system before harmful effects manifest
Solution Approach 2:
The control device implements feedback by continuously monitoring hydraulic pressure through the oil vibration sensing means and automatically adjusting the line pressure through the line pressure increase means. This closed-loop feedback system detects pulsation and responds by stabilizing pressure, preventing excessive vehicle behavior variation while maintaining reliable belt clamping
2Stability of the object's composition
If the line pressure is increased to suppress oil vibration, then hydraulic pressure stability is improved, but the pilot valve may exclude excessive hydraulic pressure causing unstable pilot pressure
Solution Approach 1:
The control device applies dynamics by making the line pressure adjustable rather than fixed. The line pressure increase means dynamically modifies the pressure based on real-time oil vibration detection, allowing the system to adapt to varying conditions and maintain stability without causing excessive pressure that would trigger the pilot valve to exclude pressure
Solution Approach 2:
The control device changes the pressure parameter dynamically. Instead of maintaining a constant high pressure, the line pressure increase means adjusts the pressure level based on detected oil vibration characteristics, changing the parameter to match system needs and prevent pilot valve activation while maintaining hydraulic stability
3Loss of energy
If the clamping force is decreased due to hydraulic pressure pulsation, then fuel efficiency is improved, but belt slippage occurs and vehicle behavior becomes unstable
Solution Approach 1:
The control device uses feedback to monitor hydraulic pressure stability and automatically adjust line pressure to compensate for pulsation. This allows the system to maintain stable clamping force despite attempts to reduce it, preventing belt slippage and vehicle behavior variation while allowing some flexibility for fuel efficiency optimization
Solution Approach 2:
The control device performs preliminary action by stabilizing line pressure before hydraulic pressure pulsation can cause belt slippage. This preemptive pressure stabilization ensures reliable power transmission even when clamping force is reduced, allowing fuel efficiency improvement without sacrificing vehicle behavior stability
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
The solution stabilizes hydraulic pressure and reduces variations, preventing mutual increases in hydraulic pressure and thus minimizing unnatural feelings for the driver by ensuring stable pilot pressure and controlling solenoid valves based on sensed oil vibration, thereby enhancing vehicle stability and reducing resonance with natural frequencies.
Implementation Method 1
a pilot valve configured to supply a pilot pressure regulated so as not to exceed a first predetermined pressure when the line pressure exceeds the first predetermined pressure
Implementation Method 2
an oil vibration sensing means configured to sense an oil vibration
Implementation Method 3
a line pressure increase means configured to increase the line pressure to be greater than the first predetermined pressure when the oil vibration sensing means senses the oil vibration
Data Source
AI summary
A control device for a continuously variable transmission includes: a line pressure generating means configured to generate a line pressure; a pilot valve configured to supply a pilot pressure regulated so as not to exceed a first predetermined pressure when the line pressure exceeds the first predetermined pressure; a control means configured to control solenoid valves by the pilot pressure, and thereby to generate belt clamping forces; an oil vibration sensing means configured to sense an oil vibration; and a line pressure increase means configured to increase the line pressure to be greater than the first predetermined pressure when the oil vibration sensing means senses the oil vibration.