JPH05209767A - Heating resistor type air flowmeter - Google Patents

Abstract

PURPOSE:To obtain the objective flowmeter enhanced in jamming resistance by preventing the detachment of the cover being the accessory part, constituting the air sub-passage of a heating resistor type air flowmeter, and taking electrical continuity at the same time. CONSTITUTION:A member having conductivity is built in the body 1 of a heating resistor type air flowmeter constituted of a non-conductive member and the cover arranged in a main air passage 3 and constituted of the non-conductive member being the accessory part constituting an air sub-passage and a structure covering a sensor part and providing mechanical strength by soldering or welding and taking the continuity with the GND of a drive circuit is provided.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heating resistor type air flow meter provided in a flow path, and more particularly to a heating resistor type air flow meter suitable for measuring an intake air amount of an internal engine.

[0002]

2. Description of the Related Art As a conventional apparatus, for example, Japanese Patent Laid-Open No. 61-65
Some are described in Japanese Patent No. 053.

[0003]

In the heat generating type air flow meter having the structure as described above, if the cover is accidentally dropped due to the joining method by thermal welding, the cover passes through the duct, enters the inside of the engine, and then the engine. Cause damage. Further, even in the structure of screw fixing, the same result is obtained when the screw and the cover fall, and further, an insert bush having a thread cut on the other side for fixing the screw is required, resulting in a high cost.

It is an object of the present invention to provide a heat generating type air flow meter which prevents the cover from dropping at a low cost.

Another object of the present invention is to improve the resistance to electromagnetic interference by covering the sensor section with a conductive member.

[0006]

SUMMARY OF THE INVENTION In order to achieve the above-mentioned object, the present invention uses a thermal welding method to leak air to the joints of a block body and a lid-shaped cover that form a sub-air flow path. Cover the sensor part with a conductive member inserted in the main body and cover and give it mechanical strength,
The block body and the cover are joined together.

[0007]

According to the above structure, since the cover has mechanical strength with the conductive member inserted in the block body which is a part of the air flow meter main body, the cover is dropped unless the air flow meter main body is broken. It can be prevented. In addition, by covering the sensor part with a conductive member and establishing electrical connection with the GND of the drive circuit, it is possible to escape the radio waves struck by lightning to the sensor part, thus improving the radio wave obstacle resistance of the heating air flow meter. It is possible.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An air flow meter according to the present invention will be described in detail below with reference to the illustrated embodiment, taking a thermal air flow meter as an example.

First, FIG. 1 is a cross-sectional view of a heating resistance type air flow meter showing an embodiment of the present invention, and FIG. 2 is a line A--A of FIG.
It is a cross section. In the present embodiment, the body 1 is made of a non-conductive member that adopts the bypass passage method as the air passage method (in this embodiment, plastic is used as the material).
And the module containing the drive circuit are connected using a screw 10. The module has an aluminum base 9 formed by inserting an indicator pin 7 for fixing the heat generating resistor 5 and the temperature sensitive resistor 6 into a mold 24, a housing 2 serving as an outer wall, and a substrate 15 serving as a drive circuit main body. It is put on and fixed by adhesion. The connection between the substrate 15 and the indicator pin 7 is bonded to an aluminum pad 27 mounted on the substrate 15 via an aluminum wire 26 and electrically connected to a drive circuit. A plastic cover 16 is attached to the outer side of the housing 2 to protect the substrate 15 of the drive circuit body.

Here, the body 1 is a shield composed of a conductive member which is installed so as to cover the heating resistor 5, the temperature sensitive resistor 6 and the support pin 7 which are the sensors for measuring the air flow rate. A material 11 is embedded, and one end of the material 11 is electrically connected to the substrate 15 of the drive circuit via the screw 10. Further, also in the cover 8 made of a non-conductive member used to form the sub air flow path 4, the shield material 12 made of a conductive member is similarly embedded inside the cover. The air leakage between the cover 8 and the body 1 is prevented by heat welding.
Also, the shield material 12 is welded or soldered to the shield material protrusion 13 so that the body 1 and the cover 8 have mechanical strength, and at the same time, electrical conduction is established. As a result, the cover 8 can be prevented from coming off from the body 1, and at the same time, it can be electrically connected to the GND of the drive circuit, and the radio waves struck by lightning can be escaped to the sensor section, thus improving the radio wave interference resistance. A heating resistance type air flow meter can be provided.

Further, FIG. 3 is an AA cross section similar to FIG. 2, but shows an embodiment constituted by a shield material having a structure in which the shield material 30 and the shield material 31 are provided with clamp-like hooks. Is.

[0012]

As described above, according to the present invention, not only is air leakage prevented at the joint between the body main body made of the non-conductive member of the heating resistance type air flow meter and the cover,
The cover can be prevented from falling off, and the GN of the drive circuit can be prevented.
By connecting to D, it is possible to escape the radio wave struck by the lightning to the sensor section, so that it is possible to provide a heating resistance air flowmeter with improved resistance to radio interference.

[Brief description of drawings]

FIG. 1 is a sectional view of a body of a heating resistance type air flow meter showing an embodiment of the present invention.

FIG. 2 is a sectional view taken along line AA of FIG.

FIG. 3 is a cross-sectional view of a heating resistance type air flow meter having a structure in which a clamp-like hook is provided at a joint between a body and a cover, showing an embodiment of the present invention.

[Explanation of symbols]

1 ... Body, 2 ... Housing, 3 ... Main passage, 4 ... Bypass passage, 5 ... Heating resistor, 6 ... Heat sensitive resistor, 7 ... Indicator pin, 8 ... Cover, 9 ... Aluminum base, 10 ... Screw,
11 ... Shield material A, 12 ... Shield material B, 13 ... Shield material protrusion, 15 ... Substrate, 16 ... Plastic cover,
24 ... Mold, 26 ... Aluminum wire, 27 ... Aluminum pad, 28 ... Heat welding part, 29 ... Insert bush,
30 ... Shield material A with clamp, 31 ... Shield material B with clamp.

Claims (4)

[Claims] 1. A body formed of a non-conductive member having a main air flow path through which intake air flows, and a sub air flow path installed in the main air flow path and through which a part of the intake air flows. A block body provided with an air flow rate detecting element for detecting an intake air flow rate, the sub air flow path has an inlet opening to the main air flow path, and is formed parallel to the main flow path. And a groove-shaped sub-air flow path formed in a direction substantially perpendicular to the above-mentioned axial sub-flow path and a cover, which is an accessory component of a lid-shaped non-conductive member, and has an opening in the main air flow path. In the axial flow type air flowmeter having an outlet, a heating resistance characterized by forming a sub air flow path by inserting a conductive member into each of the block body and the lid-like cover and joining the conductive members. Air flow meter. 2. The heat resistance type air flow meter according to claim 1, wherein the block body and the lid-like cover are joined by soldering. 3. The heat resistance type air flow meter according to claim 1, wherein the block body and the lid-like cover are joined by welding. 4. A heating resistance type air flow meter according to any one of claims 1 to 3, wherein a clamp-shaped retainer is provided at a portion where each of the block body and the lid-shaped cover is joined. ..