Servovalve Spool Assembly With Clamped Feedback Spring Fixing

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Solution Overview

Problem

The existing connection between the feedback spring and the spool in servovalves is prone to wear, leading to loosening and reduced response due to movement, which affects the spool's ability to return to its null position effectively.

Innovation Solution

The method involves inserting a feedback spring into the spool's internal cavity and using fixing members with screw threads or deformable members to securely clamp the spring in place, preventing relative movement and wear by adjusting and securing the fixing members using a tool and deformable elements.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If a ball is used to connect the feedback spring to the spool, then the assembly is simple and easy to manufacture, but wear occurs at the contact surfaces leading to loosening and reduced response

Engineering Contradiction:
Improveease of assemblyVSAvoidconnection stability
Core Design Contradiction:
Ease of manufactureVSReliability

Solution Approach 1:

The connection system is divided into multiple components: the feedback spring, fixing members (screws), and clamping elements. This segmentation allows each component to perform its specific function - the spring provides feedback force while the fixing members securely attach it to the spool, eliminating the wear problem of the ball connection while maintaining ease of assembly through modular design

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The feedback spring is pre-positioned within the spool's internal cavity before final securing. The fixing members are designed to be inserted and tightened to clamp the spring in its predetermined position, ensuring proper alignment and secure attachment without requiring complex adjustment procedures during assembly

Inventive Principle:
Principle #10Preliminary action

2Reliability

If the feedback spring is securely clamped using fixing members, then wear is reduced and connection stability is improved, but the device complexity increases

Engineering Contradiction:
Improveconnection stabilityVSAvoidstructural complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The feedback spring is nested within the internal cavity of the spool, and the fixing members are inserted through the spool to clamp the spring from the inside. This nested arrangement secures the spring firmly while maintaining a compact structure that does not significantly increase the overall size or complexity of the servovalve assembly

Inventive Principle:
Principle #7Nested doll (Nesting)

Solution Approach 2:

The fixing members are designed to be simple screws or clamping elements that can be easily inserted, tightened, and secured using standard tools. Once tightened, they maintain constant clamping force on the feedback spring without requiring additional adjustment mechanisms, making the system self-sustaining and reducing operational complexity

Inventive Principle:
Principle #25Self-service

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 solution ensures the feedback spring remains securely positioned, reducing wear and maintaining the spool's accuracy in returning to its null position, enhancing the servovalve's responsiveness and reliability.

Implementation Method 1

The spool may comprise a screw thread located on a surface of an internal cavity thereof, and at least one of the two members may comprise a screw thread that cooperates with the screw thread located on the surface of the spool

Methodology Applied
Scientific EffectScrew thread mechanism: Screw

Implementation Method 2

the step of securing the fixing members in their respective set positions comprise deforming the one or more deformable members from a first position, in which at least one of the fixing members is permitted to slide or move within the spool, to a second position, in which the at least one of the fixing members is not permitted to slide or move within the spool

Methodology Applied
Scientific EffectDeformation: Deformation

Data Source

PatentEP3597935B1Spool assembly for servovalve
Publication Date: 2021.09.08 HAMILTON SUNDSTRAND CORP
  • EP3597935B1 patent drawingFigure 1~2
  • EP3597935B1 patent drawingFigure 3~4
  • EP3597935B1 patent drawingFigure 5

AI summary

The disclosure provides a method of securing a feedback spring (150) relative to a spool (110) of a servovalve, the method comprising inserting the feedback spring (150) at least partially into an internal cavity (124) of the spool (110), inserting two fixing members (160) into the internal cavity (124) such that they each oppose a portion of the feedback spring (150), bringing the fixing members (160) into respective set positions, such that the fixing members (160) clamp the feedback spring (150) and prevent relative movement between the feedback spring (150) and the spool (110), and securing the fixing members (160) in their respective set positions, such that the fixing members (160) remain in their clamping positions and prevent relative movement between the feedback spring (150) and the spool (110).