JPH08201137A - Air flow rate measuring apparatus - Google Patents

Abstract

PURPOSE: To make possible the maintaining of a measuring accuracy sufficiently even against heat as well by providing a second metal member to reduce the deflection of a metal screen as first metal member of a rectifier grating as caused by thermal shrinkage of a resin frame part at the rectifier grating. CONSTITUTION: A body 2 comprising a resin is constituted of an air path 6, a sensor 4 for detecting an air flow rate and a rectifier grating 3 set on the upper side of the sensor for the flow of air 5. A frame part 8 of the rectifier grating 3 is made of a resin between a metal screen 7 as the first metal member and a second metal member 9. As a result, when the body 2 and the frame part 8 of the rectifier grating 3 comprising the resin as expanded by heat generated in an internal combustion engine are shrunk thermally, the second metal member 9 provided on the rectifier grating 3 prevents a force working on the metal screen 7 as the first metal member of the rectifier grating 3 as generated by the thermal shrinkage thereby making possible the reduction of measuring errors owing to the deformation of the metal screen 7.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an air flow rate measuring device for detecting the flow rate of air supplied to an internal combustion engine, and more particularly to an air flow rate measuring device for a resin body.

[0002]

2. Description of the Related Art A conventional rectifying grid in an air flow measuring device, which is closest to the present invention, is provided with a positioning on a frame around a mesh described in Japanese Patent Application No. 5-131651 to improve the measurement accuracy. There is.

However, in this configuration, the mesh is a wire mesh,
When considering the frame as a resin, no consideration was given to the influence of heat generated in the internal combustion engine, and the measurement accuracy could not be sufficiently maintained.

[0004]

In the above-mentioned conventional technique, the measurement accuracy can be maintained only at room temperature.
The heat generated by the internal combustion engine has not been fully taken into consideration.

An object of the present invention is to make it possible to maintain sufficient measurement accuracy even with the above heat.

[0006]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention provides a deflection of a wire mesh which is a first metal member of a rectifying grid due to thermal contraction of a resin frame portion in a resin body air flow measuring device or a rectifying grid. A second metal member was provided in the rectifying grid to reduce

[0007]

The air flow rate measuring device is installed in a place susceptible to the heat generated by the internal combustion engine. Therefore, the resin body air flow rate measuring device causes thermal expansion. The wire mesh, which is the first metal member of the rectifying grid, is weak against lateral force,
Thermal contraction of the resin frame in the resin body air flow rate measuring device and the rectifying grid that has been thermally expanded causes the bending of the wire mesh, which is the first metal member of the rectifying grid. The present invention provides a second metal member inside the rectifying grid for reducing the deflection of the wire mesh, which is the first metal member of the rectifying grid, due to thermal contraction of the resin frame in the resin body air flow rate measuring device and the rectifying grid. It is provided. An air flow measuring device in which the output change due to heat generated in the internal combustion engine is small by reducing the force exerted on the wire mesh, which is the first metal member of the rectifying grid due to heat contraction, by the second metal member provided in the rectifying grid. Can be supplied.

[0008]

Embodiments of the present invention will be described below with reference to FIGS.

FIG. 1 is a sectional view of an air flow rate measuring apparatus showing an embodiment of the present invention. The air flow rate measuring device body 2 includes an air passage 6, a sensor 4 for detecting an air flow rate, and an air 5.
The sensor 4 is formed by a rectifying grid 3 installed upstream of the sensor with respect to the flow of 1), and the sensor 4 is electrically connected to the module 1 containing the drive circuit. FIG. 2 shows a rectifying grid 3 in an air flow measuring device showing an embodiment of the present invention.
3 is a plan view showing the structure of FIG. In addition, FIG. 3 is A-A of FIG.
It is sectional drawing. The frame portion 8 of the rectifying grid 3 is formed of resin between the metal net 7 which is the first metal member and the second metal member 9. According to this structure, when the resin body air flow rate measuring device 2 thermally expanded by the heat generated in the internal combustion engine and the frame portion 8 of the rectifying grid 3 are thermally contracted, the second metal member 9 provided in the rectifying grid 3 is It serves as a shield for preventing the force exerted on the wire net 7 which is the first metal member of the rectifying grid 3 due to heat contraction. Therefore, since the force applied to the wire net 7 which is the first metal member of the rectifying grid 3 becomes small, the measurement error due to the deformation of the wire net 7 can be reduced. FIG. 4 is a plan view showing the structure of the rectifying grid 3 which is an embodiment of the air flow rate measuring device. 5 is a sectional view taken along line BB of FIG. The rectifying grid 3 has a second metal member 9 installed inside a frame portion 8 formed of resin. In this embodiment, FIG.
Also, as in the embodiment shown in FIG. 3, the force applied to the wire net 7 which is the first metal member of the rectifying grid 3 generated by the second metal member 9 due to thermal contraction is reduced. Further, since the wire mesh 7 is surrounded only by the frame portion 8 formed of resin, the structure for installing the rectifying grid 3 in the air flow measuring device body 2 is simplified. Therefore, since the force applied to the wire net 7 which is the first metal member of the rectifying grid 3 becomes small, the measurement error due to the deformation of the wire net 7 can be reduced. Furthermore, it becomes easy to install the rectifying grid 3 in the air flow measuring device body 2. FIG. 6 is a plan view showing the structure of the rectifying grid 3 which is an example of the air flow rate measuring device. 7 and 8 are C-
It is C section and DD sectional drawing. Similar to the embodiment shown in FIGS. 2 and 3, the frame portion 8 of the rectifying grid 3 is formed by partially molding a resin between the wire mesh 7 as the first metal member and the second metal member 9. It has a structure. In the present embodiment, by reducing the volume of the frame portion 8 formed of resin, the force exerted on the wire mesh 7 which is the first metal member of the rectifying grid 3 caused by the thermal contraction of the resin frame portion 8 is reduced. Become. Therefore, the measurement error due to the deformation of the wire net 7 can be reduced.

[0010]

According to the present invention, the measurement accuracy of the air flow measuring device is improved.

[Brief description of drawings]

FIG. 1 is a sectional view of an air flow rate measuring device according to an embodiment of the present invention.

FIG. 2 is a plan view of a rectifying grid that is an embodiment of the present invention.

3 is a cross-sectional view of the embodiment of FIG.

FIG. 4 is a plan view of a rectifying grid that is an embodiment of the present invention.

5 is a sectional view of the embodiment of FIG.

FIG. 6 is a plan view of a rectifying grid that is an embodiment of the present invention.

7 is a cross-sectional view of the embodiment of FIG.

FIG. 8 is a sectional view of the embodiment of FIG.

[Explanation of symbols]

1 ... Module with built-in drive circuit, 2 ... Air flow rate measuring device,
3 ... Rectifying grid, 4 ... Air flow rate detection sensor, 5 ... Air flow, 6 ... Air passage.

Claims (3)

[Claims] 1. An air flow measuring device for measuring the amount of air taken into an internal combustion engine, an air flow measuring device in which a body of the air flow measuring device is made of resin, and air taken into the air flow measuring device. In the air flow rate measuring device having a rectifying grid for rectifying, the rectifying grid has a metal part and a frame part, and the frame part is made of a resin between the wire mesh as the first metal member and the second metal member. An air flow rate measuring device having a structure for molding. 2. The air flow measuring device according to claim 1, wherein the rectifying grid has the second metal member installed inside the frame made of resin. 3. The air flow rate measuring device according to claim 1, wherein the frame portion is partially molded with resin between a wire mesh which is the first metal member and the second metal member.