Spool Valve Layout With Opposed Pilot and Load Pressure
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Solution Overview
Problem
Conventional spool valves require a large space and have a large size due to the direction of action of the pilot pressure being perpendicular to the load pressure, and the imbalance between these pressures makes it impractical to adjust the areas acted upon by them.
Innovation Solution
A spool valve design where the pilot pressure acts opposite to the load pressure, with equal areas for the load pressure acting surface and a shoulder's first acting surface, and a smaller area for the pilot pressure acting surface, allowing the spool to move based on pilot pressure while being balanced by a biasing member.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the pilot pressure acts from a direction perpendicular to the load pressure direction, then the spool valve can control movement of the spool, but the fluid apparatus requires a large space and has a large size
Solution Approach 1:
The patent inverts the conventional arrangement by making the pilot pressure act in the opposite direction to the load pressure (both axial), rather than perpendicular to it. This inversion allows both pressure directions to be aligned axially, enabling compact design while maintaining spool control functionality
Solution Approach 2:
The patent merges the pilot pressure action and load pressure action into the same axial direction, allowing the spool valve body to accommodate both pressure inputs along the axis. This combining of pressure directions eliminates the need for perpendicular arrangements, reducing overall apparatus size
2Adaptability or versatility
If the pilot pressure acts opposite to the load pressure direction, then the layout requirements are satisfied, but the area ratio between pilot pressure surface and load pressure surface becomes difficult to balance due to the small magnitude of pilot pressure
Solution Approach 1:
The patent segments the spool structure into distinct functional surfaces: a load pressure acting surface and a pilot pressure acting surface, with the pilot pressure surface being smaller in area. This segmentation allows independent optimization of each surface area to achieve proper force balance with opposite-acting pressures
Solution Approach 2:
The patent applies local quality by creating a smaller pilot pressure acting surface area compared to the load pressure acting surface area. This localized area differentiation compensates for the smaller magnitude of pilot pressure, enabling force balance when pressures act in opposite axial directions
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 results in a compact spool valve system where the pilot pressure direction is opposite to the load pressure direction, reducing the overall size and enabling precise control of the spool movement without requiring a large space.
Implementation Method 1
a pilot pressure acting surface formed on another axial end side of the spool and acted on by a pilot pressure
Implementation Method 2
a load pressure acting surface formed on one axial end side of the spool and acted on by a load pressure
Implementation Method 3
a first biasing member for pressing the spool toward the one axial end side
Data Source
Figure 1
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Figure 3
AI summary
A spool valve (10) includes: a valve body (20); and a spool (30) housed in the valve body (20) so as to be movable in an axial direction, the spool (30) having a load pressure acting surface (31) and a pilot pressure acting surface (32), the load pressure acting surface (31) being formed on one axial end side of the spool (30) and configured to be acted on by a load pressure, the pilot pressure acting surface (32) being formed on another axial end side of the spool (30) and configured to be acted on by a pilot pressure, The spool (30) includes a spool body (33) and a shoulder (34) radially enlarged from the spool body (33), and the shoulder (34) has a first acting surface (34a) positioned on the other axial end side and a second acting surface (34b) positioned on the one axial end side. The spool (30) has a first communication hole (35) and a second communication hole (36) formed therein, the first communication hole (35) communicating between the load pressure acting surface (31) and the first acting surface (34a), the second communication hole (36) communicating between the pilot pressure acting surface (32) and the second acting surface (34b).