Hydraulic Valve Spool Annuli for Fluid Exchange
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Solution Overview
Problem
Existing hydraulic valves face inefficiencies in fluid exchange due to viscosity changes with temperature, leading to sluggish spool movement and slow fluid exchange, particularly in cold weather, as the annulus in prior designs never shuts off, resulting in small fluid passage areas and unwanted pressure buildup.
Innovation Solution
The hydraulic valve design includes a spool with annuli that connect drain passages to end bores in a neutral position, allowing increased fluid exchange initially before blocking fluid flow, and optional electro-hydraulic proportional pressure reducing valves can maintain simultaneous pressure on both spool ends to facilitate fluid transfer without spool movement, optimizing annulus clearance for efficient fluid exchange.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the annulus in prior hydraulic valve designs remains always open, then fluid can continuously exchange between end bores and drain chambers, but the fluid passage area becomes small and unwanted pressure buildup occurs, leading to sluggish spool movement
Solution Approach 1:
The annulus is designed to dynamically change its state between open and closed positions based on spool location. In the neutral position, the annulus opens to provide large fluid passage area for efficient fluid exchange. When the spool shifts to active positions, the annulus closes to prevent unwanted pressure buildup. This dynamic behavior resolves the contradiction by providing large passage area only when needed for fluid exchange while preventing pressure buildup during operation.
Solution Approach 2:
The annulus operates periodically, opening during the neutral position to facilitate fluid exchange and closing during active positions to prevent pressure buildup. This periodic opening and closing action, synchronized with spool movement, optimizes fluid exchange efficiency while maintaining spool movement speed by preventing harmful pressure effects.
2Quantity of substance
If the annulus passage area is increased to improve fluid exchange, then more fluid can be exchanged, but unwanted pressure buildup occurs leading to sluggish spool movement
Solution Approach 1:
The annulus passage area is dynamically adjusted through the spool's axial movement. When the spool is in the neutral position, the annulus is positioned to provide a large fluid passage area, maximizing the quantity of fluid exchanged. When the spool shifts to active positions, the annulus moves to a closed position, preventing pressure buildup. This dynamic adjustment resolves the contradiction between exchanging large quantities of fluid and preventing unwanted pressure effects.
3Speed
If fluid viscosity increases due to cold weather, then fluid exchange becomes slower, but increasing passage area to compensate causes unwanted pressure buildup
Solution Approach 1:
The system dynamically responds to operating conditions through the spool position. In cold weather when fluid viscosity increases, the spool remains in or returns to the neutral position more frequently, keeping the annulus open to provide maximum passage area for compensating the slower fluid exchange rate. When operation is needed, the spool shifts and the annulus closes to prevent pressure buildup, allowing the system to adapt to viscous fluid conditions without the harmful effects of constant large passage area.
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
This design enhances fluid exchange efficiency by allowing a greater quantity of fluid to be exchanged in the neutral position and reduces parasitic losses, while preventing unwanted pressure buildup, thereby improving spool movement speed and fluid transfer rates.
Implementation Method 1
fluid acting on one of the ends to block fluid flow from the first and second bores to the first and second drain passages
Data Source
AI summary
A hydraulic valve includes a valve body having first and second ends, a bore extending therebetween, and first and second drain passages opening to the bore; a spool disposed in the bore and biased in a neutral position, the spool having first and second ends and first and second annuli axially spaced from the first and second ends respectively, whereby when the spool is in the neutral position, the first and second drain passages are connected to first and second bores respectively via the respective annulus, and wherein the spool is axially movable relative to the body by fluid acting on one of the ends to block fluid flow from the first and second bores to the first and second drain passages.