Pilot Type Switching Valve Segmented Spool Design
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Solution Overview
Problem
In hydraulic circuits, increasing the flow rate of pilot type switching valves to ensure relief flow rates leads to an increase in valve size due to increased pressure receiving area and bias force, necessitating larger bias springs, which further enlarges the valve.
Innovation Solution
A pilot type switching valve design with a valve element having a pressure receiving surface area smaller than the housing bore sectional area, featuring a pilot chamber formed inside the valve element to reduce pilot pressure reception and bias force, thereby preventing size increase while maintaining relief flow rates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the diameter of the valve element is increased to ensure relief flow rate, then the flow rate is improved, but the pressure receiving area is increased which requires larger bias spring and increases valve size
Solution Approach 1:
The valve element is divided into multiple sections with different diameters. The upstream section has a larger diameter to ensure adequate flow rate, while the downstream section has a smaller diameter to reduce the pressure receiving area in the pilot chamber. This segmentation allows the valve to maintain both sufficient flow capability and compact size by having different sections optimized for different functions.
2Productivity
If the pressure receiving area is increased to improve flow rate capability, then the flow rate is improved, but the bias force by pilot pressure is increased requiring larger bias spring
Solution Approach 1:
The valve element is divided into multiple sections with different diameters. The upstream section has a larger diameter to ensure adequate flow rate, while the downstream section has a smaller diameter to reduce the pressure receiving area in the pilot chamber. This segmentation allows the valve to maintain both sufficient flow capability and compact size by having different sections optimized for different functions.
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 design effectively suppresses the size increase of the pilot type switching valve while ensuring adequate relief flow rates by reducing the pilot pressure receiving area and bias force, allowing for a more compact device.
Implementation Method 1
a pilot chamber to which pilot pressure biasing the valve element in the valve opening direction is guided
Implementation Method 2
a bias member configured to bias the valve element in the valve closing direction
Data Source
AI summary
A pilot type switching valve includes: a housing bore formed in a valve body, the housing bore having an opening end; a spool slidably housed in the housing bore, the spool being configured to allow or block a flow of the working fluid to a first relief valve; a pilot chamber to which pilot pressure biasing the spool in the valve opening direction is guided; and a spring configured to bias the spool in the valve closing direction. The spool has a bottom surface on which the pilot pressure acts in such a manner that the spool is biased in the valve opening direction, and the area of the bottom surface is smaller than the sectional area of the housing bore.