Branch Flow Channel Layout to Keep Foreign Matter from Flow Sensors

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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 passage, which can reduce detection accuracy by interfering with the flow rate detection unit.

Innovation Solution

The device incorporates a passage flow channel with a branch flow channel and a physical quantity detector, featuring a guiding surface that redirects foreign matter away from the detector, and a configuration where the inflow and outflow surfaces are designed to prevent foreign matter from entering the measurement area, ensuring accurate flow rate detection.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If a branch passage is provided to discharge fluid for measurement, then flow rate detection is enabled, but foreign matter with relatively large mass may still enter the branch passage and reduce detection accuracy

Engineering Contradiction:

Improveflow rate detection accuracyVSAvoidforeign matter interference

Core Design Contradiction:

Measurement precisionVSObject-affected harmful factors

Solution Approach 1:

The patent utilizes the linear motion tendency of foreign matter with relatively large mass as a beneficial characteristic. By designing the discharge passage to be substantially straight rather than curved, the foreign matter naturally follows the linear path and is discharged from the outflow port without entering the branch passage, thereby protecting the flow rate detection unit from contamination while maintaining measurement functionality.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

Solution Approach 2:

The patent segments the flow channel into two distinct paths: a discharge passage for main fluid flow and foreign matter discharge, and a branch passage for measurement. The discharge passage is designed as a substantially straight path that separates foreign matter discharge from the measurement function, allowing the two functions to operate independently without interference.

Inventive Principle:

Principle #1Segmentation

2Productivity

If the discharge passage is curved to facilitate flow, then fluid discharge is improved, but foreign matter with relatively large mass may deviate from the curved path and enter the branch passage

Engineering Contradiction:

Improvefluid discharge efficiencyVSAvoidflow rate detection accuracy

Core Design Contradiction:

ProductivityVSMeasurement precision

Solution Approach 1:

Instead of curving the discharge passage as conventionally done to facilitate fluid flow, the patent inverts the approach by making the discharge passage substantially straight. This inversion leverages the inertial motion of foreign matter to achieve both efficient discharge and protection of the measurement unit, resolving the contradiction between fluid discharge efficiency and measurement precision.

Inventive Principle:

Principle #13The other way round (Inversion)

Data Source

PatentUS10907762B2Physical quantity measurement device

Publication Date: 2021.02.02 DENSO CORP

AI summary

A physical quantity measurement device includes a passage flow channel, a branch flow channel, and a physical quantity detection unit. An inflow region extending from the inflow port and a lateral region laterally arranged to the inflow region are included in at least one of the passage flow channel and the branch flow channel. The physical quantity detection unit is disposed in the lateral region. A guiding surface that guides away from the lateral region in the lateral direction foreign matter is included in at least one of an inner peripheral surface of the passage flow channel and an inner peripheral surface of the branch flow channel at a position upstream of the lateral region.