JPH09273950A - Device for measuring heating resistance type air flow rate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the loss of function in an attaching state by providing a connection duct between an auxiliary air duct and a main air duct at the part of an auxiliary air duct constitution member difficult to receive dynamic pressure of forward air flow. SOLUTION: A heating resistor 3 and an induction resistor 4 fixed with an insulating member 7 in the inside of an auxiliary air duct 2 disposed in a main air duct 1 are arranged, and the auxiliary air duct 2 is integrally fixed with a circuit module 5 to electrically be connected. The module 5 is fixed on the outer wall of the main air duct 1, and a hole 6 is drilled through a gap 8 between an insulating member 7 and the auxiliary air duct 2 constitution member. Thereby in the case where water enters the auxiliary air duct 2, short- circuiting of the resistor 3 can be prevented from water because collected water flows from the hole 6. Furthermore, a device in which function does not influence an attaching state can be obtained without any influence on output characteristics of the device by drilling the hole 6 at the part difficult to receive the dynamic pressure in the forward direction of air of the main air duct 1.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heating resistance type air flow measuring device.

[0002]

2. Description of the Related Art As a prior art, a substantially L-shaped sub-air passage having a heating resistor and a temperature sensitive resistor described in Japanese Patent Publication No. 2-1518, and a heating resistor and a temperature sensitive resistor are electrically connected. In a heating resistance type air flow rate measuring device including a connected electronic circuit, there is a structure in which a sub passage is integrally fixed to a case member that protects the electronic circuit.

[0003]

In the prior art, when the heating resistance type air flow rate measuring device is attached to the lower side of the main passage, the sub air passage is substantially L-shaped, so that the heating resistor and the temperature sensitive resistor are provided. It is feared that water will be accumulated at the base of the body support, and the sensor unit will be electrically short-circuited, impairing the function of the heating resistance type air flow rate measuring device. For this reason, the heating resistance type air flow rate measuring device has taken measures against this problem by limiting the mounting direction and the like. An object of the present invention is to provide a heating resistance type air flow rate measuring device which does not impair its function in an attached state.

[0004]

In order to solve the above problems, it is possible to prevent water from accumulating by providing a hole communicating with the main air passage in a part of the sub air passage. Furthermore, by setting the position where it is difficult to receive the dynamic pressure of the forward air flow, it is possible to provide the heating resistance type air flow rate measuring device which has taken the above measures without impairing the output accuracy of the heating resistance type air flow rate measuring device.

[0005]

BEST MODE FOR CARRYING OUT THE INVENTION A first embodiment of the present invention will be described below with reference to FIG.

A sub air passage 2 is arranged in a main air passage 1 which is a part of an intake system in an internal combustion engine, and a heating resistor fixed inside the sub air passage 2 by an insulating member 7. 3 and a temperature sensitive resistor 4 are arranged and electrically connected to a circuit module 5 having an electronic circuit built therein.

The sub air passage 2 is fixed integrally with the circuit module 5, and the circuit module 5 is fixed to the outer wall of the main air passage 1 without directly contacting the main air passage constituent members. ing. The sub air passage 2 and the circuit module 5 are bonded to each other with, for example, a silicone adhesive. A hole 6 is provided in a portion of the sub air passage 2 that is less likely to receive dynamic pressure during forward flow, with a gap 8 between the insulating member 7 and the sub air passage 2 constituent member interposed therebetween.

In the conventional structure, for example, as shown in FIG.
When the circuit module 5 is arranged diagonally below the main passage 1, when the water 8 enters the sub-air passage 2,
The heat-generating resistor 3 and the temperature-sensitive resistor 4 are accumulated at the bases of the respective supports, which causes a short circuit of the heat-generating resistor 3 which is the sensor unit. In order to solve such a problem, by providing the hole 6 in the sub air passage 2, the accumulated water will flow out from the hole, and it is possible to prevent a short circuit due to infiltration of water. Since the hole 6 provided in the sub air passage 2 is provided in a portion of the main passage 1 that is less likely to receive dynamic pressure in the forward flow direction of air, it does not affect the output characteristics of the heating resistance type air flow rate measuring device. This makes it possible to provide a heating resistance type air flow rate measuring device whose function is not affected by the mounting state.

In the embodiment, the insulating member 7 and the sub air passage 2 are provided.
It is premised that water starts to flow from the holes 6 through the gaps between the constituent members. In the case where these are integrated or when the structure has no gap, water or the like cannot flow out only by the holes 6 shown in FIG. Therefore, the radial holes 61 of the sub-air passage 2 constituent member as shown in FIG.
By providing the axial hole 62 with the above, it is possible to provide a heating resistance type air flow rate measuring device whose function is not influenced by the mounting state even when there is no gap between the insulating member 7 and the sub air passage 2 constituent member.

[0010]

According to the present invention, by providing a hole in a portion that does not receive dynamic pressure during forward flow in the sub air passage, the heat generating resistance type air flow rate measuring device does not lose its function in the attached state. A type air flow measuring device can be provided.

[Brief description of drawings]

FIG. 1 is a sectional view of a heating resistance type air flow rate measuring device showing a first embodiment of the present invention.

FIG. 2 is a sectional view of a heating resistance type air flow rate measuring device showing a second embodiment of the present invention.

FIG. 3 is a cross-sectional view of a heating resistance type air flow rate measuring device showing a problem of the conventional structure.

[Explanation of Codes] 1 ... Main air passage, 2 ... Sub air passage, 3 ... Heating resistor, 4
... temperature sensitive resistor, 5 ... circuit module, 6 ... hole, 61 ... radial hole, 62 ... axial hole, 7 ... insulating member, 8 ... gap, 9 ... water.

 ─────────────────────────────────────────────────── ─── Continued Front Page (72) Inventor Shinya Igarashi 2477 Takaba, Hitachinaka City, Ibaraki Prefecture Hitachi Car Engineering Co., Ltd.

Claims (3)

[Claims] 1. A heating resistor used in an internal combustion engine for detecting an air flow rate, a temperature-sensitive resistor for controlling a heating temperature of the heating resistor according to an intake air temperature, and the heating resistor. An electronic circuit board electrically connected to the temperature-sensitive resistor, and a module in which an insulating member for holding and protecting the electronic circuit board is integrated, and auxiliary air provided inside a main air passage forming an intake air passage. In a heating resistance type air flow rate measuring device in which the heating resistor and the temperature sensitive resistor are arranged in a passage, a dynamic pressure of a forward air flow flowing from an intake port to an engine side in the sub air passage. An exothermic resistance type air flow rate measuring device, characterized in that a communication passage communicating with the sub air passage and the main air passage is provided at least at one portion of the sub air passage constituent member in a place where it is hard to receive. 2. The communication passage according to claim 1, comprising a gap formed when the constituent member of the sub air passage and a module insulating member are combined, and a hole provided in the constituent member of the sub air passage. Heating resistance type air flow rate measuring device. 3. The heating resistance type air flow rate measuring device according to claim 1, wherein the sub air passage has a bend at at least one position.