JPH11125551A - Airtight structure of heating resistance type flowmeter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make preventable gas and liquid from entering and flowing out the module of a flowmeter by applying an adhesive to an exposed part of a conductive member. SOLUTION: A sub passage is located inside a main passage formed by a body constituting a gas passage of an internal combustion engine. A heat- generating resistor 3 and a thermosensitive resistor 4 are placed inside the sub passage and supported by welding or the like by a conductive member 5. The conductive member 5 is connected to an electronic circuit and is covered by an insulating member 6 around the member 5. A counterbore is provided on the insulation member 6 to have a part of the conductive member 5 exposed, and silicon containing adhesive 9 for example is applied around the exposed part. Thus flow-out and entry of gas and liquid through the conductive member 5 can be prevented. The counterbore is molded by a molding at the time of molding the insulating member which is represented by a plastic molding. Further, press molding or platinum plating may be applied to a part filled with the adhesive 9 of the conductive member 5.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an airtight structure of a flow rate measuring device for measuring a gas flow rate, and more particularly to an airtightness of a heating resistance type flow rate measuring device suitable for measuring a gas supply amount to an internal combustion engine used in an automobile. Regarding the structure.

[0002]

2. Description of the Related Art A conventional heating resistance type flow measuring device is disclosed in
As described in JP-A-5-340776, a structure is provided for preventing gas and liquid from entering and flowing out of a conductive member that electrically connects a heating resistor and a temperature-sensitive resistor to a flow device drive circuit. Did not.

[0003]

In the above prior art, the conductive member for electrically connecting the heating resistor and the temperature-sensitive resistor to the flow device drive circuit is filled with resin. Gases and liquids enter and exit from the minute gaps, which limits the life of the product. The present invention provides a technique for preventing the intrusion and outflow of gas and liquid only by adding an adhesive material without reducing productivity by making a small change to the resin mold. In addition, the catalytic action of platinum plating applied to the surface of the conductive member and the increase in the surface area and the flow path resistance due to press molding cure the silicone gel and the like, thereby preventing the gel from entering and flowing out.

[0004]

SUMMARY OF THE INVENTION A small change is made to an injection mold used for filling a conductive member for electrically connecting a heating resistor and a temperature-sensitive resistor with a flow device drive circuit with resin. Press forming and platinum plating are performed on the conductive member. Further, an adhesive member is applied to an exposed portion of the conductive member.

[0005]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS. FIG. 1 shows an example of a heating resistance type flow meter to which the present invention is applied. The sub passage 2 is located inside the main passage 1 formed by the body 7 constituting the gas passage of the internal combustion engine. A module 8 containing an electronic circuit is fixed to a side surface of the body 7. The heating resistor 3 and the temperature-sensitive resistor 4 are disposed inside the sub-passage 2 and are supported by a conductive member 5 by welding or the like. The conductive member 5 is electrically connected to an electronic circuit, and its periphery is covered with an insulating member 6.

According to the present invention, the structures of the conductive member 5 and the insulating member 6 have been particularly improved in order to prevent the outflow of gas and liquid from the module 8 and the intrusion of gas and liquid into the module 8.

As shown in FIG. 1, in the conventional product, sufficient consideration has not been given to the airtightness of the interface between the conductive member 5 and the insulating member 6. As a result, the silicone gel in the module 8 leaks out, shortening the product life and preventing the module 8
The structure was such that a liquid such as water or a gas could enter.

FIG. 2 shows an embodiment in which a counterbore is provided on the insulating member 6 so as to completely expose a part of the conductive member 5 and a silicon adhesive 9 is filled around the exposed portion. . By employing this structure, it is possible to prevent gas or liquid from entering or flowing out at at least one location of the conductive member. The counterbore portion is formed by a molding die when the insulating member 6 is molded from a plastic material such as PBT (polybutylene terephthalate).
However, at the time of molding, the conductive member 5 must be held with a sufficient force. In addition, the molding die of the counterbore portion has a structure in which the conductive member 5 is pressed down during molding and plays a role of positioning.

FIG. 3 shows an embodiment in which a part of the conductive member 5 is partially exposed. Also in this embodiment, it is possible to prevent outflow and intrusion of gas and liquid passing through the conductive member. The counterbore is formed by a molding die when forming the insulating member 6 represented by a plastic mold. However, at the time of molding, the conductive member 5 must be held with a sufficient force. In addition, the molding die of the counterbore portion has a structure in which the conductive member 5 is pressed down during molding and plays a role of positioning. When no effect is obtained in this embodiment, it is necessary to switch to a structure in which the adhesive 9 is filled all around at least one portion of the conductive member 5 as shown in FIG.

FIG. 4 shows that at least one portion of the conductive member 5 is exposed all around, and one side is an insulating member 112 such as PBT which is the same as the insulating member 6, and the other side is an insulating member constituting the sub passage 2. It is sandwiched between the elastic members 6 to maintain airtightness. Connecting the insulating member 112 and the auxiliary passage 2 to the conductive member 5 with an adhesive 9 is also an embodiment of the present invention. That is, the insulating member 112 and the conductive member 5, the insulating member 6, and the sub-passage 2 are bonded and fixed with the adhesive 9 layer.

FIG. 5 shows a case where a counterbore portion is provided at a terminal portion of the insulating member 6 on the side of the heating resistor 3 and the temperature-sensitive resistor 4, and the counterbore portion is filled with an adhesive 9 to insulate the conductive member 5. This is an embodiment in which it is possible to maintain airtightness between the conductive member 6 and the conductive member 6. At this time, the counterbore portion has a structure that exposes the entire periphery of the conductive member 5.

FIG. 6 shows a structure in which at least a part of the conductive member 5 filled with the adhesive 9 is press-formed and platinum-plated. At this time, the conductive member 5
At least one place where the press molding and the platinum plating are performed has a structure surrounding the entire periphery of the conductive member 5. The press forming performed on the surface of the conductive member 5 is as follows.
The insulating member 6 penetrates into the irregularities on the surface of the conductive member 5 at the time of molding, thereby increasing the flow path resistance between the conductive member 5 and the insulating member 6 and preventing gas and liquid from entering and flowing out. There is. Platinum plating applied to the surface of the conductive member 5 particularly has a catalytic action on the silicone gel, and has an action of converting an uncured state into a cured state. This action prevents the outflow and intrusion of the silicone gel.

FIG. 7 shows an embodiment used for an internal combustion engine, particularly for a gasoline engine. The intake air 111 to the engine is supplied to an air cleaner 12, an intake air temperature sensor 13, a body 15,
While the duct 16, the throttle angle sensor 17, the idle control valve 18, and the throttle body 19 flow through the intake passage integrated with the intake manifold 20, the flow rate is detected by the heating resistance type flow measuring device 14 according to the present invention. The signal is input to the control unit 21 in the form of voltage, frequency, etc.
2. One embodiment used for controlling a combustion unit structure and subsystems including a tachometer 23, an engine cylinder 24, an exhaust manifold 25, a gas 26, and an oxygen concentration meter 27.

FIG. 8 shows an embodiment used for an internal combustion engine, particularly a gas engine. The heating resistance type flow rate measuring device 14 detects a gas flow rate.

[0015]

According to the present invention, a small change of the injection mold of the insulating member and the application of the adhesive are performed on a small area, or the conductive member is press-formed and platinum-plated, so that the cost can be kept low. It is possible to provide a flow meter that prevents outflow and intrusion of gas and liquid.

[Brief description of the drawings]

FIG. 1 is a conventional example of a flow meter to which the present invention is applied.

FIG. 2 shows an embodiment of the present invention by filling the entire circumference of the adhesive.

FIG. 3 shows an embodiment of the present invention by partially filling the adhesive surroundings.

FIG. 4 shows an embodiment of the present invention by bonding different members.

FIG. 5 shows an embodiment of the present invention by filling a plastic mold end adhesive.

FIG. 6 shows one embodiment of the conductive member of the present invention by platinum plating and press molding.

FIG. 7 is a configuration diagram of a control system for an internal combustion engine using the present invention (gasoline engine).

FIG. 8 is a control system configuration diagram (gas engine) of an internal combustion engine using the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Main passage, 2 ... Sub passage, 3 ... Heating resistor, 4 ... Temperature sensitive resistor, 5 ... Conductive member, 6 ... Insulating member, 7, 15 ... Body, 8 ... Module, 10 ... Hole, 11 ... Platinum plating, 12 ... Air cleaner, 13 ... Intake air temperature sensor, 14
... heat generation resistance type flow measurement device, 16 ... duct, 17 ... throttle angle sensor, 18 ... idle air control valve, 19 ... throttle body, 20 ... intake manifold, 21 ... control unit, 22 ... injector, 23 ... tachometer, 24 ... Engine cylinder, 25
... exhaust manifold, 26 ... gas, 27 ... oxygen concentration meter,
28: gas tank, 29: insulating member, 111: intake air.

 ──────────────────────────────────────────────────の Continuing on the front page (72) Inventor Hiroyuki Abe 2520 Oji Takaba, Hitachinaka City, Ibaraki Prefecture Inside the Hitachi, Ltd.Automotive Equipment Division (72) Inventor Hitoshi Ishikawa 2477 Takaba, Hitachinaka City, Ibaraki Prefecture Stock Association Hitachi Car Engineering Co., Ltd.

Claims (14)

[Claims] 1. A heating resistor and a temperature sensing resistor disposed in a gas passage of an internal combustion engine used in an automobile, and a signal corresponding to a flow rate of a fluid based on heat dissipation from the heating resistor to the fluid. A conductive member having an output electronic circuit and supporting the heating resistor and the temperature-sensitive resistor is fixed by insert molding into a plastic mold member, and the heating resistor and the sensing resistor are fixed via the conductive member. In a heating resistance type flow rate measuring device, wherein a temperature resistor and the electronic circuit are electrically connected, a silicone gel is injected into the housing and hardened, and the upper surface of the housing is covered to cover the electronic circuit. The plastic member is provided in the housing between a portion electrically connected to the electronic circuit and a portion to which the heating resistor and the temperature-sensitive resistor are fixed. There is a portion exposed from the timber, the airtight structure of the heating resistor type air flow measuring apparatus characterized by injecting after applying adhesive to the exposed portion, the silicone gel in the housing. 2. A method according to claim 1, wherein a portion of said conductive member exposed in said housing is formed so as to also position said conductive member during injection molding of said plastic mold member. Airtight structure of the heating resistance type flow measurement device. 3. A portion of the conductive member, which is exposed in the housing, inside a counterbore provided in the plastic mold member according to claim 1 or 2,
An airtight structure for a heat-resistance-type flowmeter, wherein an adhesive is injected into the counterbore portion. 4. The hermetic structure of a flowmeter according to claim 3, wherein all terminals of the conductive member are exposed inside one counterbore portion of the plastic mold member. 5. The counterbore according to claim 4, wherein a counterbore is provided on the opposite side of the counterbore portion, that is, the plastic mold member is provided with a hole in which the conductive member is exposed. An airtight structure for a heating resistance type flow rate measuring device, wherein an adhesive is injected into the hole from the inside of the housing after the other side of the housing is closed with another member. 6. A device according to claim 5, wherein said another member closing said hole is a protect cap member for protecting said heat generating resistor and said temperature sensitive resistor, and said hole is closed at a joint surface with said plastic mold member. The airtight structure of the heating resistance type flow rate measuring device, characterized in that: 7. The airtight structure of a heat-resistance measuring flowmeter according to claim 6, wherein said protect cap has a shape also serving as a sub-passage through which a part of the fluid flows. 8. The method according to claim 1, wherein the adhesive has a volume sufficient to stop ingress and outflow of gas and fluid, and is permanently soft and conductive. An airtight structure of a heating resistance type flow rate measuring device, characterized in that the adhesiveness with a plastic mold member is close. 9. The heating resistance type flow rate measuring apparatus according to claim 1, wherein the adhesive is a quick-drying adhesive having low viscosity and good permeability. Airtight structure. 10. The airtight structure of a heating resistance type flow rate measuring device according to claim 1, wherein the adhesive is a silicone-based adhesive. 11. The adhesive according to claim 1, wherein the adhesive comprises the plastic mold member or a member fixing the plastic mold member and an adhesive for bonding a housing or an electronic circuit board. An airtight structure of a heating resistance type flow rate measuring device, characterized by being the same. 12. A heating resistor and a temperature-sensitive resistor arranged in a gas passage of an internal combustion engine used in an automobile, and a signal corresponding to a flow rate of the fluid based on heat dissipation from the heating resistor to the fluid. A conductive member having an output electronic circuit and supporting the heating resistor and the temperature-sensitive resistor is fixed by insert molding into a plastic mold member, and the heating resistor and the sensing resistor are fixed via the conductive member. In a heating resistance type flow rate measuring device, wherein a temperature resistor and the electronic circuit are electrically connected, a silicone gel is injected into the housing and hardened, and the upper surface of the housing is covered to cover the electronic circuit. The conductive member has a platinum film formed by plating or the like on the surface of at least a portion between the heating resistor or the temperature-sensitive resistor fixing portion and a portion exposed in the housing. Airtight structure of the heating resistor type air flow measuring apparatus characterized by being. 13. A heating resistor and a temperature-sensitive resistor disposed in a gas passage of an internal combustion engine used in an automobile, and a signal corresponding to a flow rate of the fluid based on heat dissipation from the heating resistor to the fluid. A conductive member having an output electronic circuit and supporting the heating resistor and the temperature-sensitive resistor is fixed by insert molding into a plastic mold member, and the heating resistor and the sensing resistor are fixed via the conductive member. In a heating resistance type flow rate measuring device, wherein a temperature resistor and the electronic circuit are electrically connected, a silicone gel is injected into the housing and hardened, and the upper surface of the housing is covered to cover the electronic circuit. The conductive member is a pressed member or a composite having a pressed member. In the press forming, irregularities are formed on the surface of the conductive member. Airtight structure of the heating resistor type air flow measuring apparatus characterized in that the. 14. A control system for an internal combustion engine that controls an engine using the heating resistance type flow rate measuring device according to any one of claims 1 to 13.