Stepped Flow Channel Prevents Particle Contamination in Physical Quantity Measurement

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Solution Overview

Problem

Conventional physical quantity measurement devices for fluids, such as air flow meters, face challenges in accurately measuring flow rates due to foreign matter entering the measurement flow channel, which can lead to reduced detection accuracy and inefficiencies in fluid measurement.

Innovation Solution

The design incorporates a passage flow channel with inflow and outflow step surfaces that guide foreign matter back to the inflow or outflow ports, preventing it from entering the measurement flow channel, thereby enhancing detection accuracy by ensuring only fluid enters the measurement area.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If a simple discharge passage is used, then the device structure is simple, but foreign matter can enter the measurement flow channel reducing detection accuracy

Engineering Contradiction:

Improveflow rate detection accuracyVSAvoidpassage structure complexity

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The discharge passage is segmented into multiple regions by introducing a stepped portion that divides the passage into a first discharge region (upstream) and a second discharge region (downstream). This segmentation creates distinct functional zones that guide foreign matter away from the measurement flow channel while maintaining overall structural simplicity.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The stepped portion acts as an intermediary structure between the discharge passage and the measurement flow channel. It serves as a physical barrier and guide that intercepts foreign matter and redirects it toward the discharge port, preventing foreign matter from entering the measurement flow channel without requiring complex additional components.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Measurement precision

If foreign matter is allowed to flow freely, then the fluid flow path is simple, but detection accuracy is reduced due to foreign matter interference

Engineering Contradiction:

Improvephysical quantity detection accuracyVSAvoidfluid flow path simplicity

Core Design Contradiction:

Measurement precisionVSEase of operation

Solution Approach 1:

The stepped portion is positioned upstream in the discharge passage to preliminarily intercept and redirect foreign matter before it can reach the measurement flow channel. This preliminary action prevents foreign matter from interfering with measurements without requiring post-processing or complex control mechanisms.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

Instead of trying to prevent foreign matter from entering the discharge passage or using complex filtration systems, the invention inverts the approach by using the stepped portion to actively guide foreign matter toward the discharge port. This inverted guidance mechanism simplifies the overall system while maintaining high detection accuracy.

Inventive Principle:

Principle #13The other way round (Inversion)

Data Source

PatentUS11555723B2Physical quantity measurement device having a stepped portion to prevent particles from entering the measurement flow channel

Publication Date: 2023.01.17 DENSO CORP

AI summary

A physical quantity measurement device that measures a physical quantity of a fluid has an inflow port and an outflow port, and includes a passage flow channel, a branch flow channel, and a physical quantity detector. An inner peripheral surface of the passage flow channel extends over a pair of facing surfaces, which face each other across the flow passage boundary portion and the inflow port on an upstream side of the flow channel boundary portion. The inner peripheral surface further includes an inflow step surface which forms a step facing the inflow port side.