Mitsubishi Electric Corporation

Kazuto Akagi

Masahiro Kawai

Yuji Ariyoshi

Naoyuki Kishikawa

Hiroyuki Uramachi

Hiroshi Sakanoue

Shinichiro Hidaka

Provide a flow measuring device which inhibits a reduction of flow detection accuracy, which is caused by an influence of a bottom flow which is flowed and inputted from a fit gap between a flow detecting element and an installing portion of the flow detecting element. A concave portion, which inhibits an influence of a bottom flow which is flowed and inputted from a fit gap between an installing portion and a flow detecting element, is provided at a bottom surface of the installing portion of a plate which is positioned on a projected area of a cavity of the flow detecting element.

Flow measuring device

A flow measuring device includes a sub-bypass passage arranged to precede a bypass passage which is linked to a flow detecting element. Bypass passage wall surfaces, which are positioned adjacent the sub-bypass passage, are inclined toward a direction of a sub-inflow opening, and an inner-circumference-side wall surface and an outer-circumference-side wall surface of the sub-bypass passage are inclined toward a direction of a sub-outflow opening. The described structure minimizes variations in the size of the bypass passage due to build-up of foreign material, and results in a more stable flow velocity of measured fluid past the flow detecting element.

Flow measuring device having plurality of bending portions

An environment sensor arranged in a measuring chamber disposed in a circuit board receiving portion does not affect a flow of air through a bypass passage, and thus does not affect detection accuracy of a flow rate detection element arranged in the bypass passage. A recessed portion is disposed in a side surface of a base parallel to a flow direction A of intake air passing through a main passage and a communication port of the measuring chamber is disposed in the recessed portion, and thus the measuring chamber is unlikely to be infiltrated by fouling substances, water droplets, and the like contained in the intake air. The communication port has a small length dimension L, and thus an environment parameter of the intake air is likely to propagate to the measuring chamber and high levels of detection response, detection accuracy, and reliability are ensured for the environment sensor.

Flow rate measurement device

A flow rate measuring device includes: a bypass passage; a flow rate detecting element; and a flow rate measuring circuit. The bypass passage includes: an inflow port; an outflow port; and a plurality of bent portions. The plurality of bent portions include first to third bent portions for forming U-shapes, and a fourth bent portion for bending the bypass passage bent at the third bent portion so as to be parallel to a mainstream flowing direction. The flow rate detecting element is arranged inside the bypass passage in a part after bending at the fourth bent portion. A route connecting the inflow port and the flow rate detecting element as a straight line is blocked by an inner wall surface of the bypass passage on an outer peripheral side, which is formed between the first bent portion and the second bent portion.

Flow rate measuring device

Dust with various particle diameters entering a bypass passage, particularly, relatively large dust with a particle diameter of 100 to 200 &#x3bc;m or so, is reliably caused to collide with a first step-shaped part, a second step-shaped part and a plate-like member to be sufficiently decelerated and reach a flow rate detecting device with low collision energy. This can prevent the flow rate detecting device from being damaged by collision of dust. Furthermore, the placement position of the plate-like member is optimized to suppress air turbulence at a flow rate detecting part, which achieves a good balance between flow rate detection accuracy and dust tolerance.

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Tokyo, Japan

Kazuto Akagi