Open Center Control Valve Spool Bore Distortion Reduction
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Solution Overview
Problem
Existing multiple-spool control valves experience pressure drop losses, complexity in plumbing due to workport orientation, spool bore distortion, and the need for multiple pressure relief valves, which affect reliability and efficiency.
Innovation Solution
The design includes a valve section with a longitudinal bore, workport and return passages configured to reduce pressure drop, allow for oriented workports to simplify plumbing, and a single relief valve to protect both chambers of an actuator, along with a spool that shifts to divert fluid flow efficiently.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stress or pressure
If high pressure fluid flows through internal passages of the valve section, then the fluid can reach the actuator, but the longitudinal bore accommodating the spool may be distorted under pressure
Solution Approach 1:
The valve section is divided into multiple independent passages (open-center passage, supply passage, workport passages, return passages) that are spatially separated and disposed on one side of the valve section. This segmentation isolates the high-pressure fluid flow paths from the spool bore, preventing pressure-induced distortion while maintaining functional integrity.
Solution Approach 2:
The patent arranges all fluid passages (supply, workport, return, and open-center passages) on one side of the valve section rather than distributing them symmetrically around the spool bore. This dimensional reorganization moves the high-pressure fluid paths away from the longitudinal bore in the radial dimension, eliminating the distortion problem while preserving pressure transmission capability.
2Reliability
If multiple pressure relief valves are installed to protect each chamber of the actuator, then the actuators are protected from high pressure levels, but the cost and device complexity increase
Solution Approach 1:
The patent merges the functions of multiple relief valves into a single relief valve located in the open-center passage. This single valve protects both chambers of the actuator by providing a common pressure relief path, thereby reducing device complexity and cost while maintaining comprehensive actuator protection.
Solution Approach 2:
The single relief valve in the open-center passage serves a universal function by protecting both actuator chambers simultaneously. Instead of having dedicated relief valves for each chamber, this multi-functional approach allows one valve to monitor and relieve pressure from both sides of the actuator, simplifying the overall valve assembly.
3Device complexity
If workports are oriented in a particular direction to reduce plumbing complexity, then the plumbing becomes simpler, but the layout of fluid passages and coring design inside the valve sections is affected
Solution Approach 1:
The valve section is segmented into distinct functional zones with passages disposed on one side, allowing workports to be oriented optimally for simplified external plumbing. This segmentation decouples the internal passage layout from external connection requirements, enabling independent optimization of both plumbing simplicity and manufacturing feasibility.
Data Source
AI summary
An example valve section includes: a housing having: (i) a longitudinal bore, (ii) a first and second workport passages configured to be fluidly coupled to an actuator, (iii) a first and second return passages, (iv) an open-center passage configured to be fluidly coupled to a source of fluid, and (v) a supply passage disposed between the first and second workport passages. The valve section also includes a spool movable in the longitudinal bore to shift between: (i) a neutral position that allows the open-center passage to permit fluid flow therethrough, and (ii) a shifted position that allows fluid to be diverted from the open-center passage to the supply passage, and connects the supply passage to either the first or second workport passage while connecting the other workport passage to a corresponding return passage of the first and second return passages.