Needle Valve Limit Cap Assembly for Rotation-Restricted Flow Control
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Solution Overview
Problem
The assembly of needle valve and limit cap in conventional flow control restrictors is cumbersome due to the need for fitting an annular member onto the limit cap and fixing it to the needle valve.
Innovation Solution
A flow control restrictor design featuring a needle valve with a metal first and second shaft portion, a resin pressed portion, and a metal limit cap with a projecting portion that fits into a restriction groove, allowing easy assembly by press-fitting the limit cap onto the needle valve.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an annular member is fitted onto the limit cap and the limit cap is fixed to the needle valve using conventional methods, then the connection between limit cap and needle valve is secure, but the assembly process becomes cumbersome and time-consuming
Solution Approach 1:
The limit cap is fitted directly onto the needle valve shaft in a nested configuration, where the limit cap surrounds and secures the needle valve. This nested structure eliminates the need for separate annular members and complex fitting procedures, achieving both secure connection and simplified assembly.
Solution Approach 2:
The functions of the annular member and the limit cap are merged into a single integrated limit cap structure. The limit cap itself performs both the connection and the rotation restriction functions, eliminating the need for separate components and reducing assembly steps.
2Reliability
If multiple separate components are used to fix the limit cap to the needle valve, then the connection is reliable, but the device complexity increases
Solution Approach 1:
Multiple functions (connection, rotation restriction, and positioning) are merged into the single limit cap component. The limit cap integrates the rotation restriction groove and the fitting structure, eliminating the need for separate annular members and reducing overall device complexity.
Solution Approach 2:
The limit cap serves multiple functions simultaneously: it connects to the needle valve, restricts rotation through the integrated groove, and provides structural support. This multi-functionality reduces the number of components needed while maintaining connection reliability.
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
Facilitates easy assembly of the needle valve and limit cap, reduces assembly time, and maintains precise regulation of air-fuel ratios by restricting unwanted rotation, thereby improving production efficiency and maintaining consistent air-fuel mixture concentration.
Implementation Method 1
The pressed portion of the needle valve is pressed against the inner peripheral surface of the limit cap
Data Source
AI summary
A flow control restrictor includes: a needle valve; and a limit cap which is made of metal and attached to the needle valve. In the needle valve, a first shaft portion which is made of metal and screwed into a regulation hole and a second shaft portion which is made of metal and housed inside the regulation hole are formed. On the second shaft portion, a first projection-and-recess portion is formed, and a pressed portion made of resin is provided on the first shaft portion side relative to the first projection-and-recess portion. The limit cap is fitted onto the second shaft portion. On the limit cap, a projecting portion which is inserted into a restriction groove of the regulation hole and a second projection-and-recess portion which is engaged with the first projection-and-recess portion are formed. The pressed portion is pressed against an inner peripheral surface of the limit cap.