Servo Valve Nozzle Assembly with Grooved Fixing for Easy Calibration

Solution Overview

Problem

The tight interference fit of nozzles in servo valve assemblies makes calibration difficult and increases manufacturing costs due to strict tolerances required for maintaining the fit at various operating temperatures.

Innovation Solution

The nozzle assembly incorporates an annular groove with a vent passage and a threaded portion for easy calibration, using a setting material like plastic (e.g., PEKK, PEEK, PPS, or PVDF) to secure the nozzle in place, allowing for a loose fit that facilitates calibration and reduces manufacturing complexity.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a tight interference fit is used to secure the nozzle in the housing, then the nozzle remains in the correct position at all operating temperatures, but it becomes difficult to calibrate the servo valve and increases manufacturing cost due to strict tolerances

Engineering Contradiction:

Improvenozzle position stabilityVSAvoidcalibration difficulty

Core Design Contradiction:

ReliabilityVSEase of operation

Solution Approach 1:

The nozzle assembly is segmented into three functional zones: an annular groove at the first end for receiving setting material, a vent passage at the second end for air evacuation, and a threaded portion for calibration. This segmentation allows the nozzle to be securely fixed in position while maintaining ease of calibration through the threaded interface.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The setting material acts as an intermediary substance that fills the annular groove and secures the nozzle in the housing. This intermediary provides a reliable fixed connection without requiring a tight interference fit, thereby enabling both secure positioning and easier calibration.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Reliability

If a tight interference fit is used to secure the nozzle in the housing, then the nozzle remains in the correct position at all operating temperatures, but manufacturing cost and time increase due to strict tolerances

Engineering Contradiction:

Improvenozzle position stabilityVSAvoidmanufacturing complexity

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The nozzle assembly is segmented into three functional zones: an annular groove at the first end for receiving setting material, a vent passage at the second end for air evacuation, and a threaded portion for calibration. This segmentation allows the nozzle to be securely fixed in position while maintaining ease of calibration through the threaded interface.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The setting material (e.g., plastic such as PEKK, PEEK, PPS, or PVDF) serves as a cost-effective alternative to precision-machined interference fits. This material-based fixing method reduces manufacturing complexity and tolerances while providing reliable nozzle positioning.

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

3Ease of operation

If a loose fit is used to facilitate calibration, then calibration becomes easier and manufacturing is simpler, but the nozzle may not remain securely fixed at operating temperatures

Engineering Contradiction:

Improvecalibration easeVSAvoidnozzle position stability

Core Design Contradiction:

Ease of operationVSReliability

Solution Approach 1:

The annular groove is pre-formed at the first end of the nozzle to receive setting material before final assembly. This preliminary preparation enables the nozzle to be securely fixed in the housing while maintaining ease of calibration through the threaded portion at the opposite end.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The setting material acts as an intermediary substance that fills the annular groove and secures the nozzle in the housing. This intermediary provides a reliable fixed connection without requiring a tight interference fit, thereby enabling both secure positioning and easier calibration.

Inventive Principle:

Principle #24Intermediary (Mediator)

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 simplifies the calibration process, reduces manufacturing costs, and ensures the nozzle remains fixed within the operating temperature range without the need for costly friction reduction treatments, while maintaining precise control over actuator movement.

Implementation Method 1

The setting material is configured to fix the nozzle in position within the nozzle cavity throughout the operating temperature range

Methodology Applied

Scientific EffectThermal expansion: Thermal Expansion

Data Source

PatentEP3597972B1Nozzle and nozzle assembly for a servo valve

Publication Date: 2021.04.21 HAMILTON SUNDSTRAND CORP

Figure 1
Figure 2a~2b
Figure 3a~3b

AI summary

A nozzle (10) for a servo valve comprises an annular body (12) defining an outer circumferential surface (12a) and an inner circumferential surface (11a) of the nozzle (10). An annular groove (12b) is disposed around the circumference of the annular body (12) in the outer circumferential surface (12a). A nozzle assembly (N) for a servo valve comprises the nozzle (10) and a nozzle housing (20) having a nozzle cavity (20c) defined by an inner circumferential cavity surface (22a). The nozzle housing (20) has an annular groove (22b) disposed around the circumference of the nozzle cavity (20c) in the inner circumferential cavity surface (22a). The nozzle (10) is received within the nozzle cavity (20c) such that the annular grooves (12b, 22b) in the nozzle and the nozzle housing (10, 20) are in fluid communication with each other.