Servo Valve Nozzle Assembly for Easier Axial Calibration
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Solution Overview
Problem
The tight interference fit between nozzles and nozzle housing in servo valves makes calibration difficult due to the challenge of moving the nozzle axially within the housing, especially at varying temperatures, which is essential for precise actuator control.
Innovation Solution
A servo valve design with a cylindrical nozzle receiving bore and a locking pin receiving bore, allowing for a loose or close fit, and a threaded connection for calibration tools, facilitates easier axial movement of the nozzle during calibration while maintaining a leak-proof seal, using a locking pin to secure the nozzle in position.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the nozzle is interference fitted into the nozzle housing with a tight fit, then the nozzle remains in the correct position within the housing at all operating temperatures, but it becomes difficult to move the nozzle axially within the housing for calibration
Solution Approach 1:
The invention divides the nozzle assembly into two separate components: the nozzle itself and the locking pin. The locking pin acts as an independent element that can be inserted or removed to lock or unlock the nozzle in place. This segmentation allows the nozzle to be firmly held during operation while enabling easy removal and repositioning during calibration by simply removing the locking pin.
Solution Approach 2:
The locking pin is pre-positioned in the locking pin receiving bore to secure the nozzle in its calibrated position before operation begins. This preliminary locking action ensures the nozzle remains stable during operation while allowing for easy recalibration by removing the pin and repositioning the nozzle as needed.
2Reliability
If the nozzle is interference fitted into the nozzle housing, then the nozzle remains securely positioned, but the dimensional tolerances and manufacturing precision requirements increase
Solution Approach 1:
By introducing the locking pin as a separate component, the invention eliminates the need for tight interference fits between the nozzle and housing. The locking pin bears the responsibility of securing the nozzle, allowing the nozzle-housing interface to use looser tolerances while still achieving reliable positioning.
Solution Approach 2:
The locking pin serves as an intermediary element between the nozzle and the housing. Instead of relying on a precise interference fit between the nozzle and housing, the locking pin mediates the connection by engaging with both components, thereby securing the nozzle position with less stringent dimensional requirements.
3Reliability
If the nozzle is interference fitted into the nozzle housing, then the nozzle remains in position at elevated temperatures, but the resistance to axial movement becomes excessive for calibration purposes
Solution Approach 1:
The invention separates the functions of thermal stability and calibration accessibility by using the locking pin to secure the nozzle thermally while allowing easy removal for calibration. The locking pin maintains the nozzle position under thermal conditions but can be quickly removed to enable axial movement during calibration without excessive resistance.
Solution Approach 2:
The locking pin provides a dynamic solution where the nozzle can be easily moved during calibration by removing the pin, and then firmly locked in place for operation. This dynamic approach allows the system to transition between two states: easy movement during calibration and firm positioning during operation, resolving the contradiction between thermal stability and calibration accessibility.
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 simplifies the calibration process, reduces the need for precise dimensional tolerances and manufacturing costs, and allows for easier refurbishment or repair by enabling easier removal of the nozzle, while maintaining sufficient resistance at elevated temperatures.
Implementation Method 1
a locking pin (20) arranged to engage with the nozzle (10) to lock the nozzle (10) in position within the nozzle housing (8)
Implementation Method 2
nozzles, which inject the fluid
Implementation Method 3
Deflection of the flapper can control the amount of fluid injected from the nozzles, and thus the amount of fluid communicated to the actuator
Data Source
Figure 1
Figure 2a~2b
Figure 3
AI summary
A nozzle assembly (N) comprises a nozzle (10) received in a nozzle receiving bore (8c) of a nozzle housing (8). The nozzle receiving bore (8c) has a longitudinal axis (X-X). The nozzle housing (8) further comprises a locking pin receiving bore (30) having a longitudinal axis (Y-Y) that is perpendicular to the nozzle housing axis (X-X). The locking pin receiving bore (30) intersects the nozzle receiving bore (8c), whereby an aperture (34) is formed between the locking pin receiving bore (30) and the nozzle receiving bore (8c). A locking pin (20) is received in the locking pin receiving bore (30), a portion of the locking pin (20) protruding through the aperture (34) and into the nozzle receiving bore (8c) so as to engage a circumferential portion (36) of the nozzle (10).