Bypass Valve for Hydraulic Pressure Oscillation Control
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The cyclical pressurization and depressurization of the high pressure chamber in hydraulic fluid systems of variable valve train systems cause severe pressure fluctuations, leading to undesirable engine noise, vibration, and harshness (NVH) issues due to sudden pressure spikes during the operation of control valves.
Innovation Solution
A hydraulic fluid system with a bypass valve that provides a secondary flowpath between the middle and high pressure chambers, allowing hydraulic fluid flow based on pressure, which reduces pressure oscillations by closing the bypass flowpath when a threshold pressure is reached, thereby minimizing impulsive forces on the engine valve.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If the control valve is closed to pressurize the high pressure chamber for valve actuation, then the hydraulic fluid pressure rises to open the engine valve, but severe pressure oscillations and sudden pressure spikes occur causing NVH issues
Solution Approach 1:
A bypass valve is introduced as an intermediary component between the high pressure chamber and the middle pressure chamber. This bypass valve provides a secondary flowpath that allows hydraulic fluid to bypass the control valve, thereby mediating the pressure transmission and reducing sudden pressure spikes and oscillations that would otherwise directly affect the engine valve actuation system
Solution Approach 2:
The invention utilizes hydraulic principles by implementing a bypass flowpath that allows hydraulic fluid to flow between chambers based on pressure differentials. The bypass valve leverages hydraulic pressure relationships to automatically regulate flow, smoothing pressure transitions without requiring additional mechanical components or complex control mechanisms
2Productivity
If the control valve closes instantaneously to direct hydraulic fluid to the high pressure chamber, then valve actuation is achieved, but severe pressure fluctuations and noise are generated
Solution Approach 1:
The bypass valve enables continuous hydraulic fluid flow between the middle pressure chamber and the high pressure chamber, even when the control valve is closed. This continuity prevents abrupt pressure changes by allowing gradual pressure equalization through the bypass flowpath, thereby reducing pressure fluctuations and associated noise while maintaining effective valve actuation
3Speed
If hydraulic fluid is rapidly pressurized in the high pressure chamber to open the engine valve, then valve response time is improved, but impulsive forces and vibration increase
Solution Approach 1:
The bypass valve acts as a cushioning mechanism by providing a secondary flowpath that prevents sudden pressure spikes before they can generate harmful impulsive forces. The bypass flowpath allows hydraulic fluid to gradually equalize pressure differences, cushioning the pressure rise in the high pressure chamber and reducing impulsive forces on the engine valve while maintaining rapid response capability
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 bypass valve effectively reduces pressure oscillations and NVH issues by smoothing pressure transitions and minimizing the rate of pressure rise in the high pressure chamber, resulting in a more stable and quiet engine operation.
Implementation Method 1
A bypass valve is arranged between the middle pressure chamber and the high pressure chamber to selectively provide a second flowpath for hydraulic fluid between the middle pressure chamber and the high pressure chamber based on a pressure of the hydraulic fluid in the high pressure chamber
Implementation Method 2
When the control valve is open, the hydraulic fluid in the high pressure chamber is at a first pressure such that a biasing element urges a spool of the bypass valve to a first position in which the second flowpath is open
Data Source
AI summary
A hydraulic fluid system for a variable valve train system is provided that allows hydraulic fluid flow from a high pressure chamber to a medium pressure chamber during a higher pressure phase after a control valve closes. The hydraulic fluid system includes a housing defining (a) the middle pressure chamber which is connected to a hydraulic fluid supply, and (b) the high pressure chamber which contains hydraulic fluid that is pressurized by a pump piston assembly configured to engage a rotating cam. A control valve selectively provides a first flowpath for hydraulic fluid between the middle pressure chamber and the high pressure chamber. A bypass valve selectively provides a second flowpath for hydraulic fluid between the middle pressure chamber and the high pressure chamber based on a pressure of the hydraulic fluid in the high pressure chamber.