Suck Back Valve Control Using Position and Load Sensors

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Solution Overview

Problem

Conventional suck back valves face challenges in accurately controlling the suck back amount due to dimensional accuracy errors in individual parts, leading to inconsistent performance.

Innovation Solution

The design incorporates a joint section with coaxially arranged tubes, an ON/OFF valve, and a suck back mechanism with position and load sensors to precisely control the displacement of pistons and diaphragms, allowing for accurate suck back control by detecting magnetic fields and load changes.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If dimensional accuracy of individual parts is improved, then manufacturing precision is improved, but manufacturing cost and complexity increase

Engineering Contradiction:

Improvedimensional accuracy of partsVSAvoidcomplexity of assembly and adjustment

Core Design Contradiction:

Manufacturing precisionVSDevice complexity

Solution Approach 1:

The detection unit automatically detects the actual position of the first diaphragm and calculates the suck back amount based on measured displacement, eliminating the need for manual adjustment or pre-calibration. The system self-adjusts for dimensional variations in individual parts through automatic detection and computation.

Inventive Principle:

Principle #25Self-service

Solution Approach 2:

The system changes from fixed dimensional specifications to dynamic parameter measurement. Instead of relying on predetermined dimensional accuracy, the suck back amount is determined by actual displacement measurements and calculated parameters, allowing compensation for manufacturing variations.

Inventive Principle:

Principle #35Parameter changes

2Measurement precision

If detection unit is added to detect vertically movable member displacement, then measurement precision is improved, but device complexity increases

Engineering Contradiction:

Improvedetection of vertically movable member displacementVSAvoidcomplexity of detection system

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The patent replaces complex mechanical adjustment mechanisms with a detection unit that uses optical or electromagnetic fields to measure displacement. This substitution reduces mechanical complexity while improving measurement precision, as the detection unit non-contactly measures the position of the vertically movable member.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The detection unit acts as an intermediary between the vertically movable member and the control system. It converts physical displacement into electrical signals that can be processed by the control unit, which then calculates the suck back amount. This intermediary approach simplifies the overall system by decoupling measurement from control.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Reliability

If home position adjustment is made difficult due to attachment position errors, then reliability is improved, but ease of operation deteriorates

Engineering Contradiction:

Improveconsistency of suck back amountVSAvoidease of home position adjustment

Core Design Contradiction:

ReliabilityVSEase of operation

Solution Approach 1:

The detection unit provides real-time feedback on the actual position of the first diaphragm and the displacement of the vertically movable member. The control unit uses this feedback to calculate the actual suck back amount and adjust control signals accordingly, ensuring consistent performance regardless of attachment position variations.

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The system automatically compensates for attachment position errors through detection and calculation, eliminating the need for manual home position adjustment. The detection unit and control unit work together to self-correct for manufacturing variations, improving both reliability and ease of operation.

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 approach enables highly accurate control of the suck back amount, independent of dimensional errors in parts, ensuring consistent performance and preventing liquid drips during the coating process.

Implementation Method 1

detecting magnetic fields and load changes

Methodology Applied

Scientific EffectMagnetic field detection: Magnetic Field

Implementation Method 2

load sensor to precisely control the displacement of pistons and diaphragms

Methodology Applied

Scientific EffectLoad detection:

Data Source

PatentUS7445163B2Suck back valve

Publication Date: 2008.11.04 SMC CORP

AI summary

A suck back valve comprises an ON/OFF valve, a suck back mechanism which includes a second piston connected to a second diaphragm to make displacement integrally and a second spring member fastened to the second piston, a load sensor which detects a load applied by a resilient force of the second spring member corresponding to a pressure of a pilot pressure to be supplied, and a second control unit which detects loads before and after displacement of the second diaphragm by using the load sensor to calculate a displacement amount of the second diaphragm based on a difference between the detected loads.