JPH0277619A - Hot-wire type air flowmeter and preparation thereof - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a hot wire air flow meter and a heating resistor used therein, and is particularly suitable for detecting the intake air amount of an internal combustion engine for an automobile. This invention relates to a meter, a heating resistor used therein, and a manufacturing method thereof.

[Conventional technology]

A hot wire air flow meter installs a hot wire of a heating resistor in the air flow path where the flow rate is to be measured, and heats it by increasing the current flowing through the hot wire to counteract the cooling of the hot wire by the air flow. This device detects the air flow rate based on the amount of increase in this current.There are no moving parts and the mass flow rate can be directly detected, so it is widely used for controlling the air-fuel ratio of internal combustion engines for automobiles. .

The heating resistor used in this flowmeter is extremely thin.
For example, a metal wire such as platinum with a diameter of several tens of microns is used.
The heating resistor described in Japanese Patent No. 326 was constructed by winding a metal wire serving as the heating resistance wire around a core wire, ie, a bobbin, using ceramics or the like.

Another method is to wind a metal wire into a coil.
An application has been filed for a bobbin-less heating resistor in which the heating resistor is coated with glass except for both ends to be welded to the support of the heating resistor.

Furthermore, JP-A-62-83622 discloses a bobbinless heating resistor in which a metal wire is wound around a Mo wire in a coil shape, the outer surface of the wire is coated with glass, and the Mo wire is removed by etching. has been done.

[Problem to be solved by the invention]

Among the above-mentioned conventional techniques, in a heating resistor in which a metal wire is wound around a core wire of ceramics or the like, that is, a bobbin, the heat that heats the bobbin itself and the amount of heat transmitted to the support of the heating resistor through the bobbin cannot be ignored. Because the transient response to changes in air flow rate is delayed, there has been a problem in that surging occurs when a car suddenly accelerates or decelerates. Further, in the manufacturing process, it is necessary to perform winding work for each heating resistor, making it difficult to automate the work.

On the other hand, with the bobbinless method, the response is improved and the winding work can be performed on multiple heating resistors in succession, increasing the automation rate. There was a manufacturing problem in that it was difficult to handle the wire and sufficient workability could not be obtained for assembly work such as holding it on a support. In addition, the support member that supports the coiled metal wire is coated glass, but in order to ensure sufficient strength as a product, the thickness of the glass layer cannot be made too thin, and glass with poor thermal conductivity cannot be used. The problem is that the layers cause a delay in heat transfer between the metal wire and the airflow, impairing transient response.

Further, in the above-mentioned bobbinless method, the inner wall surface (the surface on which the metal wire is threaded) of the cylindrical member made of the glass coating is in contact with the outside air. For this reason, if the air in the air flow path to be measured contains dust or ionic substances, these dust or ionic substances may adhere to the inner wall surface of the cylindrical member, or in the worst case, In this case, it will be in a filled state. In such a case, the heat generated from the wire will be conducted using the dust as a medium, and the merits of the bobbinless system will be lost. Furthermore, when an ionic substance is attached and filled, a short circuit occurs between adjacent coiled metal wires, and the characteristics of the heating resistor itself change. In addition, in the conventional bobbin-less manufacturing method for heating resistors, a method is adopted in which a metal wire is wound around a bobbin in a coil shape and then the bobbin is removed. It uses etching.

For this reason, an etching process is particularly required, which complicates the work.

An object of the present invention is to provide a hot wire air flow meter with high responsiveness, a heating resistor thereof, and a method for manufacturing the same.

The present invention also provides a hot-wire air flowmeter, a heat-generating resistor thereof, and a heat-generating resistor therefor, which not only does not have its responsiveness impaired by dust or ionic substances in the air, but also does not cause characteristic deterioration. Another object of the present invention is to provide a hot-wire air flowmeter, a heating resistor thereof, and a method for manufacturing the same, which can be easily manufactured, can be manufactured at a high automation rate, and eliminates the complexity of one operation. The purpose is to provide

[Means to solve the problem]

The present invention includes a heating resistor installed in an air passage to measure the air flow rate, and a drive circuit that controls the current of the heating resistor and outputs an output voltage of the heating resistor as a signal corresponding to the air flow rate. In a hot wire air flow meter, one heat generating resistor is located between a metal wire wound into a coil, a metal lead wire connected to both ends of the metal wire, and a connection portion between the metal wire and the metal lead wire, and a connection portion between the metal wire and the metal lead wire. This can be achieved by constructing a support member that covers and supports the metal wire, such as a glass member.

In addition, such a heating resistor consists of a metal core wire or a glass core wire of a predetermined length, a metal wire wound around this to become a heating resistance wire, and lead wires welded to both ends of the metal wire. After preparing the part and then overcoating the metal wire with a glass material so as to also cover the welded part and firing.

Manufactured by removing the metal core wire. However, if a glass core wire is used, it is not necessary to remove it.

Moreover, in order to achieve the said object, this invention.

A glass member serving as a cylindrical support member, and a coil screwed inside the glass member along the inner wall surface of the glass member with the same center axis and having one both ends electrically drawn out of the glass member. A heating resistor for a hot-wire air flowmeter is characterized in that both ends of the glass member are closed.

In addition, when manufacturing the heating resistor, there is a step of spirally winding a metal wire as a heating resistance wire around a sublimable core wire, and only the electrical lead-out portions at both ends of the wound wire. However, the method includes at least the steps of coating the wire with a porous glass material along with the core wire, and sublimating the core wire and sintering the glass material by heat treatment.

Further, the above object of the present invention is to provide a heating resistor comprising a heating resistance wire, that is, a metal wire, a lead wire connected thereto, and a support member that covers and supports the heating resistance wire, wherein the support member is a composite of ceramics and glass. This is achieved by a heating resistor formed of a layer of material.

It is effective if the heating resistor has a hollow part, the glass component contained in the composite layer forming the support member forms one surface layer, and the glass component is a continuous phase that reaches the hollow part. It is.

Also, ceramics included in the composite layer.

It is also effective to use ceramics having a thermal conductivity of at least 10 W/m-, and the proportion of the glass component contained in the composite layer is preferably 2 to 60% by volume. Furthermore, it is effective to include a glass component having a softening point (also referred to as Littleton point) of 700°C or less and a glass component having a softening point higher than 700°C in the glass component contained in the composite material layer.

A heating resistor may be used in which the heating resistance wire is made of a film circuit formed on a ceramic substrate, and the support member is made of a composite layer of ceramic and glass covering the circuit and the ceramic substrate.

Furthermore, the above-mentioned problem includes a step of preparing a member consisting of a metal core wire of a predetermined length, a metal wire wound around the metal wire to become a heat-generating resistance wire, and lead wires connected to both ends of the metal wire, and a step of winding the wire. a step of attaching ceramic particles to the heated metal wire, coating and firing it; a step of removing the metal core wire; melting a glass component to coat the fired layer; and infiltrating the fired ceramic layer with the glass component. The present invention is also achieved by a method of manufacturing a heat generating resistor for an air flowmeter, which includes a step of forming a composite material layer.

Here, in the step of preparing a member consisting of a metal core wire, a metal wire, and a lead wire, first, a metal wire serving as a heat generating resistor is continuously wound around the metal core wire, and after cutting it to a predetermined length, A method of connecting lead wires to both ends of the metal wire, or a method of connecting lead wires to both ends of a metal core wire (of a predetermined length), and then connecting one end of the metal wire that will become a heating resistance wire to one of the lead wires. A method can be adopted in which the other end is connected to the other lead wire after being connected and wound around a metal core wire.

Alternatively, a composite layer of ceramics and glass may be formed by adhering a mixture of ceramic particles and glass particles to a wound metal wire, coating it, and firing it, or a composite layer formed from this. Further glass may be melt-coated on top.

Instead of mixing ceramic particles and glass particles, it is also possible to manufacture particles of a composite material of ceramics and glass, and to apply the particles to a metal wire wound around a metal core wire, coat it, and fire it.

1 piece of an air flow meter for an automobile having the heating resistor described above and a drive circuit section that controls the current of the heating resistor and extracts the output voltage of the heating resistor as a signal corresponding to the air flow rate. Therefore, the above object can also be achieved by an anemometer including the heating resistor and means for detecting the temperature of the heating resistor.

[Effect]

In the present invention, a metal wire is continuously wound around a metal core wire or a glass core wire having a length necessary to make a plurality of heating resistors continuous in the longitudinal direction.

At this time, since the metal wire is continuously wound on a plurality of successive heating resistors by an automatic winding machine, the automation rate of manufacturing can be significantly increased.

Next, the core wire wound with metal wire in this manner is cut to a predetermined length, and lead wires are welded to both ends of the core wire. The welds are overcoated with glass and secured together with the metal wire between the welds.

Therefore, the heating resistor is ultimately supported (integrally fixed) by the lead wire and the glass member, and there is no need to connect the thin metal wire to the support of the heating resistor, making handling easier. .

Since the metal core wire is conductive, the lead wires may be short-circuited, so the metal core wire is removed by etching with acid. The heat generating portion can be provided with mechanical strength and corrosion resistance by overcoating glass. As a result, the heat generated when the metal wire is energized does not heat the bobbin, which has a large heat capacity, as in the conventional bobbin type, nor does it travel through the bobbin and escape to the support, but instead is transferred to the air. be done. Therefore, the transient response when the air flow rate suddenly changes is greatly improved, and the hot wire air flow meter outputs a signal by following the true air flow rate change, so surging can always occur through appropriate fuel supply control. It is possible to solve problems such as

When a glass core wire is used, there is no need to remove the glass core wire because it is insulating. In this case, the mechanical strength can be provided by the core wire, so the glass overcoat can be made thinner, and the overall heat capacity can be reduced, so the response is not as bad as when the metal core wire is removed. .

It is also possible to use a manufacturing method in which the metal core wire is removed and then filled with glass. The characteristics are the same as when using a glass core wire.

As the metal wire, platinum wire with high heat resistance and corrosion resistance is usually used, but tungsten wire can also be used. A platinum-iridium alloy wire or the like is used for the lead wire.

If the glass is heated to too high a temperature, the platinum wire will become brittle and its electrical properties will change. 1200
Prolonged heating above ℃ should be avoided.

Therefore, the temperature of the glass member supporting the heating resistor is 8.
It is necessary to use a material having a viscosity of 104 poise or more and 107 poise or less between 00°C and 850°C, and to bake at 1200°C or less. Although the coefficient of thermal expansion of the glass does not necessarily have to match that of the platinum wire (90×10-'/° C.), it is advantageous for the coefficient of thermal expansion to be close to that of the platinum wire in order to alleviate stress caused by thermal cycles during use. Furthermore, when the core wire is etched away with acid, the glass must not be significantly eroded. The acid resistance of glass is related to the bonding strength of the glass structure as well as its viscosity characteristics, and it was confirmed that glass with this viscosity characteristic can suppress the depth of erosion during etching to 1 μm or less. Such glass has sufficient water resistance, oil resistance, etc. during use. Glass whose viscosity decreases at lower temperatures can be fired at lower temperatures, but it has insufficient acid resistance, water resistance, oil resistance, etc.

The above-mentioned support member is made of 50-65% by weight of SiO2°20~
35 wt% PbO, 10-20 wt% R20 (Rz
○ is the sum of K2O and N a t○), or lead-potash glass, lead-soda glass, or lead-potash-soda glass whose main component is 65-75% by weight of SiO2, 4-15% by weight (
7) RO (RO is the sum of MgO, CaO and BaO), 10
Soda-lime glass, soda-barium glass, potash-lime glass, or kalibarium glass containing ~25% by weight of R20 (R20 is the sum of K2O and Na2O) as a main component is applied.

As the metal core wire, molybdenum wire or nickel-iron alloy wire is used. It is not preferable to heat these to 1200° C. or higher in the atmosphere from the viewpoint of oxidation, and by using glasses with the above-mentioned characteristics, it is possible to use them in combination. In particular, nickel-iron alloy wire can match the coefficient of thermal expansion with platinum wire, and can reduce thermal stress during glass firing.

In addition, since both ends of the cylindrical glass member with the coil formed along the inner wall surface are closed, dust and ionic substances in the air may adhere to or fill the inner wall surface of the glass member. Nothing will happen at all. Therefore, no foreign matter will enter the surface of the coil.

Thermal or electrical stability is achieved, and the above objectives are achieved.

Further, in manufacturing, a sublimable substance is used for the core wire, and the core wire is sublimated by the heat required for the sintering operation during glass sintering. Therefore, when removing the core wire, an etching process is not necessary, so that the process work can be facilitated.

Even when the support member is made of a composite layer of ceramics and glass, both ends of the metal wire are connected to the lead wire, so there is no need to connect the thin metal wire to the support, making handling easier. Become. In particular, usually the metal wire is covered with a support member, including the connection part between the metal wire and the lead wire, and the metal wire and the lead wire are fixed, so the heating resistor is ultimately supported by the lead wire and the support member. , the structure is suitable for handling.

Since the metal core wire is conductive, it will cause a short circuit between the lead wires, so the metal core wire is removed by etching with acid or oxidation and sublimation due to elevated temperature in the atmosphere. The heat generating part can be provided with mechanical strength and environmental resistance by covering the composite material. Heat generated by energizing the metal wire is transferred to the air through the composite layer. At this time, while the thermal conductivity of glass is about IW/m-, by combining it with ceramics whose thermal conductivity is 10 W/m- or more, the thermal conductivity of the composite layer can be reduced to about that of glass. It can be multiplied by 10 times or more.

Therefore, unlike the case where a metal wire is coated only with glass, there is no large delay in changes in heat transfer due to changes in air flow, and transient response is improved.

If the coating layer of the metal wire is heated at too high a temperature, the platinum wire will become brittle and its electrical characteristics will change. Heating at temperatures above 1200°C for long periods of time must be avoided. Therefore, if only ceramics with good thermal conductivity are coated, firing will not be performed sufficiently and the strength of the heating resistor will be insufficient.

By melting glass, coating it and infiltrating it into a fired layer with ceramics to form a composite layer.

Strength and high thermal conductivity are ensured, and when ceramics and glass are simultaneously attached to a metal wire and fired,
Even below 1200℃, the sintering effect of the glass provides a high-strength coating! ! A composite layer is obtained. If voids remain in the composite layer, high strength can be obtained by melting and coating with additional glass.

By attaching the particles of the glass-ceramic composite layer to a metal wire, coating it, and firing it, the composite layer becomes more uniform and the blending ratio can be controlled more accurately.

The glass used for coating has a softening point of 700
Workability is better if you use glass with a temperature below ℃.

If the glass component of the composite layer forms a continuous phase, the strength will be high, and if the glass component is too small, the strength will be insufficient. If it is too large, the effect of combining ceramics to improve thermal conductivity will be lost. The proportion of the glass component in the composite material layer is suitably 2 to 60% by volume.

Molybdenum wires and nickel-iron alloy wires used as metal core wires can be removed by acid etching.

In the case of molybdenum wire, it sublimates by being oxidized in the atmosphere, so it can be removed at the same time as the coating layer is fired.

The air flow rate sensor element, that is, the heating resistor, is a thin element in which a heating circuit is formed in the form of a film on an alumina substrate, and a support member covering the film circuit and the alumina substrate is provided.

〔Example〕

Example 1 FIG. 1 shows an example of the configuration of a hot wire air flowmeter for an automobile internal combustion engine using a heating resistor 1 according to the present invention. In this embodiment, the same heating resistor 1 is used as a pair for measuring air temperature, and is represented by air temperature measuring resistor 6. As shown in FIG. 1, the heating resistor 1 and the air temperature measuring resistor 6 are connected to a bypass passage of a body 73, which has a main passage 71 through which most of the intake air passes and a bypass passage 72 through which a portion of the intake air flows. It is fixed to the support body 8 in 72.

Figure 2 shows an example of a drive circuit for a hot wire air flow meter.
Heat generating resistor 1, air temperature measuring resistor 6, operational amplifier 9,
10, power transistor 11, capacitor 12. It is composed of resistors 13-17. In addition, a battery (not shown) is connected to the collector terminal 18 of the power transistor 11.
The (+) pole of the resistor 13 is connected to the ground terminal 19 of the battery (not shown), and the (7) (-) pole of the resistor 13 is connected to the ground terminal 19 of the resistor 13. Input terminals of a microcomputer (not shown) that controls the engine using the output signal of the flowmeter are connected to each of the input terminals.

In such a configuration, the power transistor 11 supplies current to the heating resistor 1 to heat it, and controls the temperature thereof to be always higher than the air temperature measuring resistor 6 by a constant temperature. At this time, only a minute current is passed through the air temperature measuring resistor 6 so that heat generation is negligible, and this is used to detect the intake air temperature and correct the temperature of the intake air. When the air flow hits the heating resistor 1, the drive circuit operates so that the temperature difference between the heating resistor 1 and the air temperature measuring resistor 6 is always constant, as described above. The operation is such that the voltage obtained by dividing the voltage difference across the heating resistor 1 by the resistor 14 and 15 is always equal to the voltage obtained by amplifying the voltage drop across the resistor 13 caused by the current flowing through the heating resistor 1 by the operational amplifier 9. This is done by applying feedback to Therefore, when the air flow rate changes, the current flowing through the heating resistor 1 changes,
The air flow rate is measured by the voltage drop appearing across the resistor 13 in accordance with the current.

FIG. 3 is a configuration diagram showing another embodiment of the heating resistor for a hot wire air flow meter according to the present invention.

In the figure, there is a cylindrical glass member 4.

Inside this glass member 4, a platinum wire 2 is screwed along the inner wall surface of the glass member 4 with the same central axis.
It is equipped with Each end of this platinum wire 2 is connected to a lead Is! supported by the glass member 4, respectively. 3 and is electrically drawn out to the outside of the glass member 4. Both ends of the glass member 4 are closed with the same material as the glass member.

Next, an example of a method for manufacturing a heat generating resistor constructed as described above will be described with reference to FIGS. 4(A) and 4(B).

(A) shows a state in which platinum wire 2 with a diameter of 20 μm is continuously wound around a molybdenum core wire 5 with a diameter of 0.4 m using an automatic winding machine. (B) is cut from the member shown in (A) to a length of approximately 6 ml, the length of one heating resistor, and has a diameter of 0.13 mm at both ends.
This figure shows a state in which lead wires made of platinum iridyrim alloy of mm are welded at the connecting portion 21.

(C) shows a state in which a glass member 41 is coated around the platinum wire 2 wound around the molybdenum core wire 5 by electrophoresis and fired in an oxidizing atmosphere. The glass member 41 used here is, for example, S i Oz B2Oa
- P b O glass with a viscosity of 1 at a temperature of 800°C
The viscosity at 850° C. is 104.2 poise. In firing this glass member 41,
As the temperature rises, the oxidation of the molybdenum core wire 5 progresses to become MoOa, and when the temperature reaches 795°C, Mo0
a sublimes, but since the glass member 41, which has a viscosity of 104.5 poise at a temperature of 800°C, maintains a sufficient gap, M
The sublimate of o0a is volatilized from the gaps between the particles of the glass member 41, and the molybdenum core wire 5 is removed.

After that, the glass member 4 is held at a temperature of 950°C for 20 minutes.
1 is completed, the glass member 41 is sublimated Mo0a.
As the fluidity decreases due to the reaction, the material becomes porous and the surface smoothness is not sufficient. Therefore, as shown in (D), a second layer of glass member 42 was coated and fired in an electric furnace in an oxidizing atmosphere. . The glass member 42 used here is, for example, Zn0-
It is a B2Oa-8iOz glass and has a viscosity of 108 poise at a temperature of 600°C and a viscosity of 104 poise at 690°C. Therefore, by firing at a temperature of 720° C. for 20 minutes, the pores of the first layer glass member 41, which was porous, are sufficiently filled and the surface becomes smooth, thereby obtaining the heating resistor 1 shown in FIG. 3.

In addition, as in this method, the molybdenum core wire 5 is
The heating resistor obtained by coating and firing the layered glass member 42 has the glass member covering the inside of the platinum wire 2 wound into a coil, as shown in the enlarged view in (E). The wire 2 can be supported more firmly.

In the heat generating resistor constructed in this way, both ends of the cylindrical glass member with the coil formed along the inner wall surface are closed, so that dust and ionic substances in the air are absorbed by the glass member. No adhesion to or filling of the inner wall surface occurs at all. For this reason, no foreign matter enters the surface of the coil, so stability can be achieved from a thermal or electrical standpoint.

Further, in the method for manufacturing a heating resistor described above, by using a core wire made of a sublimable material, for example, a molybdenum core wire 5, sublimation can be performed during sintering of the glass member. This allows the core wire to be removed without having to carry out wet etching or the like, thereby making the work less complicated.

FIG. 5 is a response characteristic diagram of a hot wire-large air flowmeter using the heating resistor obtained in this example. Time (ms) is plotted on the horizontal axis, and flow rate (kg/h) is plotted on the vertical axis.

Change the air flow rate from a low flow rate of about 20 kg/h to a high flow rate of about 20 kg/h.
The output voltage of the hot wire flowmeter when switched to 0 kg/h was measured, converted to flow rate, and shown on the vertical axis. Compared to the air flow meter using a conventional bobbin-type heating resistor shown in curve B, the air flow meter of the present invention is shown in curve A. It can be seen that the time to reach the final value has been significantly improved.

Therefore, even when a car suddenly accelerates or decelerates, the hot-wire air flow meter outputs a signal that follows the true change in air volume, allowing the appropriate amount of injection from the injector to be determined and eliminating the surging problem.

The reason why the response performance has been greatly improved is that the heat generated by the platinum wire 2 of the heating resistor 1 heats the bobbin, that is, the core wire, and travels through the bobbin to support the bobbin, unlike conventional bobbin type heating resistors. This is because it does not escape to the body, but is mostly transmitted to the air, and responds sensitively to changes in the amount of air.

An anemometer fabricated by combining the heating resistor of the present invention with a circuit that detects temperature from changes in its resistance value and converts it into wind speed also showed high responsiveness.

Example 2 Next, another example of the method for manufacturing the heating resistor shown in FIG. 3 will be described below.

The platinum wire 2 with a diameter of 20 μm is made into a wire with a diameter of 0.4 μm using an automatic winding machine.
It is wound around a molybdenum core wire 5 of mm, and a wire with a diameter of 0.
．． A 13 mm platinum-iridium alloy lead wire 3 is welded at the welding part 21, and a glass member 4 is coated from the outside of the platinum wire 2 and lead wire 3 by electrophoresis, however, both ends of the molybdenum core wire 5 are left uncovered. FIG. 6 shows the state in which this was fired in an electric furnace in an oxidizing atmosphere. The glass member 4 used here is ZnO-B2O3-based glass, and the temperature is 68
It has a viscosity of 104 poise at 0°C, crystallizes at 750°C, and has a remelting temperature of 1000°C or higher. During firing of the glass member 4, as the temperature rises, the molybdenum core wire 5 is oxidized to Mo0a, and the softened glass member is sealed at a temperature of 680°C, but when it reaches 750°C, it crystallizes and its shape becomes stable. Thereafter, the molybdenum core wire 5 is removed by increasing the temperature to sublimate M o Oa, and the firing is completed by holding at 950° C. for 20 minutes, but M o Os is sublimated and volatilized at both ends of the glass member 4. Since the opening remains, the heating resistor shown in FIG. 3 is obtained by sealing the opening by melting glass with the heat of the flame.

Example 3 Further, another example of the method for manufacturing the heating resistor shown in FIG. 3 will be described below.

The platinum wire 2 with a diameter of 20 μm is made into a wire with a diameter of 0.4 μm using an automatic winding machine.
A platinum-iridium alloy lead wire 3 with a diameter of 0.13 nn is welded to both ends of the glass member 4 by winding it around a molybdenum core wire 5 having a diameter of 0.13 mm and cutting it to a length of 6IIWII corresponding to one element, that is, one heating resistor. FIG. 3 shows the state in which the material was coated by electrophoresis and then fired in an electric furnace in an oxidizing atmosphere. The glass member 4 used here is AQ2Oa-P2Or
It is a + type glass and has a viscosity of 108.7 poise at a temperature of 820'C and a viscosity of 104 poise at 910C. In firing this glass member, the molybdenum core wire 5 oxidizes as the temperature rises, and when it reaches 795°C, it sublimes and is removed.The firing is completed by holding at 1080°C for 1 hour, and the heating resistor shown in Fig. 3 is formed. Get 1.

The above experiments were carried out using glass members of various compositions for the glass member 4 shown in FIG.
If the material has a characteristic that the viscosity at .degree. C. is 107 poise or less, the heating resistor 1 shown in FIG. 3 can be obtained.

In addition, experiments were carried out using glass members of various compositions as shown in FIG.
The hot wire air flow sensor 1 shown in FIG. 3 can be obtained as long as it does not lose its shape at temperatures below 00°C.

In each of the above-mentioned examples, an electrophoretic method was used to coat the glass member, but even methods other than electrophoretic, such as applying a paste-like glass member, may be used. A heating resistor 1 shown in FIG. 3 can be obtained.

Embodiment 4 FIG. 7 is a cross-sectional view of a first embodiment of a heating resistor used in the hot wire air flow meter of the present invention. The heating resistor 1 that detects the amount of intake air includes a platinum wire 2 wound into a coil, a platinum-iridium alloy lead wire 3 connected to both ends of the platinum wire 2,
It includes a glass member °4 supporting those connecting parts 21 and platinum wires 2.

A method of manufacturing this heating resistor 1 will be explained based on FIGS. 8(A) to 8(D).

(A) is a Ni-Fe core wire containing 52% Ni with a diameter of 0.5 mm for winding a platinum wire, that is, a bobbin 5, and a platinum wire 2 with a diameter of 20 μm is wrapped around a plurality of heating resistors using an automatic winding machine. (B
) was cut into lengths of 6 mm, and a diameter of 0.13 mm was placed on both ends.
(D) shows a state in which the lead wire 3 made of platinum-iridium alloy is welded at the connection part 21, and (D) shows a state in which the connection part 21 and the platinum wire 2 are overcoated with a glass material 4 as a support member and fired. The glass material used here has a composition of 5iO
Z56% by weight, Pb030% by weight.

K2O6% by weight, Na206% by weight, Ca11% by weight,
It is lead potassium soda glass containing 1% by weight of AQ2Oa. The viscosity of this glass is 10B-3 poise at 800°C, 850
It was 104 poise at ℃. For overcoating, prepare an electrodeposition solution in which the glass is dispersed using denatured alcohol and water as a solvent, magnesium nitrate and aluminum nitrate as electrolytes, and electrodeposit between the two electrodes using a platinum wire as a cathode and an aluminum plate as an anode. A voltage of 30 V was applied in the liquid, and glass powder was adhered to the platinum wire by electrophoresis. This was fired in an electric furnace by heating at 800° C. for a long time. The thickness of the glass after firing is approximately 100 μm. This was immersed in a mixed acid of nitric acid and sulfuric acid at a temperature of 80° C. for one hour, and the core wire 5 was removed. The depth of erosion of the glass due to immersion in the mixed acid was 1 μm or less. The heat generating resistor 1 thus obtained was strong enough to be handled with tweezers and could be handled as a single element, so it was easy to handle during subsequent assembly, and sufficient workability could be obtained. It was confirmed that the air flow meter using this device showed high responsiveness as shown in FIG.

Example 5 In the same manner as in Example 4, the seventh
A heating resistor with the structure shown in the figure was fabricated.

Table 1 shows the composition of the glass used. Table 2 shows the viscosity of each glass at 800° C. and 850° C., the firing temperature, the presence or absence of embrittlement of the platinum wire due to firing, and the presence or absence of damage when the heating resistor was pinched with tweezers after the core wire was removed. Note that damage includes cases where the glass is eroded when the core wire is etched, exposing the platinum wire and loosening it.

As can be seen from Table 2, glasses with a viscosity exceeding 107 poise at 800°C must be fired at 1000°C or higher, which has the disadvantage of causing embrittlement of the platinum wire. Further, glass having a viscosity of less than 104 poise at 850° C. may require a low firing temperature, but has the drawback that it is easily attacked by acid during etching and has low strength.

Table 2 shows the heating resistor (
The hot-wire air flowmeter shown in FIG. 1 was manufactured using glass (b, e, f, h, i).

In both cases, a significant improvement in responsiveness was observed, as shown in FIG. 5, compared to the conventional air flow meter using a bobbin-type heating resistor.

Table 2 In addition, it was confirmed that this example can be sufficiently applied to a method in which the Mo wire used as the core wire 52 is removed by flame at the same time as the coating glass is fired, as in Example 1. The properties were also good.

Example 6 A Mo wire with a diameter of 0 and 5 nu was used as the core wire 5, and the third
Similar to the manufacturing process shown in Figures (A) to (D), a plurality of platinum wires with a diameter of 20 μm are wound over a length using an automatic one-wire machine, and a rear end lead wire cut to a predetermined length is welded.
Glass was attached to this welded part and the platinum wire using the dip method. The glass composition used was 274% by weight of Si0, 9% by weight of Ca, 8% by weight of K2O, and 274% by weight of Na2O3.

-XQ2Os 1% by weight. The viscosity of this glass is 3
It was 10 B-" poise at 00°C and 10+5.6 poise at 850°C. Next, the glass was fired by heating at 1000°C in an electric furnace for an egg minute. At this time, the atmosphere in the electric furnace was air, and the firing At the same time, the MO core wire was oxidized, sublimated, and removed.Therefore, the inside of the coiled platinum wire 2 was in a bobbin-less state.

The heating resistor obtained had a working strength that did not hinder subsequent assembly, and an air flow meter using it showed high responsiveness as shown in Figure 5.

Example 7 Non-alkali glass fibers with a diameter of 10 μm were bundled into a bundle with a diameter of 0.
A glass wire of 3 rrn was used as a core wire, and a platinum wire was wound around it, and then cut into a length of 10 mm.

After welding lead wires to both ends, the same glass as in Example 4 was attached by electrophoresis. At this time, the core wire and platinum wire including the welded portion were all covered with the attached glass, and the thickness of the attached glass was 275 mm as in Example 4. Next, the glass was fired by heating at 900° C. for a sufficient amount.

The obtained heating resistor had even higher strength than the heating resistor of Example 1, and did not break even when dropped from a height of 1 m to the floor. The response was a little steeper than in Example 6, but at speeds above 100 kg/h, the speed was slow, and after 30 m5, it was the same as in Example 6.

Example 8 A heating resistor shown in FIG. 2(E) was produced in the same manner as in Example 4. At this time, the thickness of the attached and fired glass is
Implementation [Half of 4. Next, the composition was 35% by weight of 5iOz and 58% by weight of Pb.

Glass containing 7% by weight of K2O was dispersed in an organic solvent and filled into the cavity from which the core wire of the heating resistor was removed.

This was heated to a sufficient amount at 650°C in an electric furnace and fired. Although the second glass filled inside contains many pores after firing, the resulting heating resistor is similar to the heating resistor of Example 1. showed similar strength. The responsiveness was also similar to Example 6.

Example 9 FIG. 9 is a structural diagram of another example of the heat generating resistor produced according to the present invention. Lead wires 3 made of platinum-iridium alloy are connected to both ends of a heat-generating resistor wire 2 made of a platinum wire wound into a coil, and the heat-generating resistor 2 including the connecting portion 21 is made of a composite material layer of ceramic and glass. Covered with 4.

A method of manufacturing this heating resistor will be explained based on FIGS. 10(A) to 10(E).

(A) is a diameter of 0.5 mm for winding platinum wire.
This is a molybdenum (Mo) core wire 5. This core wire 5 is 5m
Following the circular section, a flat section with a length of 2 nm is provided, and this is repeated. (B) is a platinum wire with a diameter of 30 μm (
This figure shows a state in which a plurality of heating resistors) 2 are continuously wound. (C
) is cut at the center of the flat part, and a diameter of 0.13 is attached to both ends.
m platinum iridium alloy lead wire 3 is connected to the connection part 21.
This shows the welded state. For the flat part, connect the lead wire 3 to the core wire 5.
It is provided to improve workability by making it easy to install. This part is formed by plastic working by compression. The flat part is formed vertically symmetrically.
Preferable from the viewpoint of workability. (D) shows the state in which the heat generating resistance wire 2 is covered with the composite material 4 and fired. When coating, denatured alcohol and water are used as solvents, magnesium nitrate and aluminum nitrate are used as electrolytes, alumina and PbO
- Prepare an electrodeposition solution in which particles of 5ift glass are dispersed at a ratio of 95:5, and set the platinum wire in the state (C) as a cathode and the aluminum plate as an anode, and apply 40V in the electrodeposition solution between both electrodes.
Alumina and glass particles were attached to the platinum wire by electrophoresis by applying a voltage of . FIG. 11 schematically shows this state, and shows the platinum wire 5 wound around the MO core wire 51.
A layer 53 of alumina and glass containing pores 54 is deposited around 2, making it a porous layer. (D) was heated in an electric furnace and held at 900°C for 1 hour to oxidize and sublimate the Mo core wire, then further heated to 1100°C and held for 30 minutes to bake the electrodeposition layer. Indicates the condition. The thickness of the fired layer 4 is approximately 80 μm. The softening point of the glass used at this time was 850° C., and although the fired layer 5 was in a porous state, it had sufficient strength for handling. Fig. 7E shows a state in which this is coated with Pb07B2Oa-8ioz glass powder having a softening point of 680°C, fired at 850°C for 90 minutes to penetrate into the fired layer 4, and the composite layer is closed. A cross section of the resulting heating resistor! 11 According to the results, the coated glass forms a surface layer and reaches into the hollow part after the Mo core wire is removed, forming a continuous phase, and the volume percentage of glass in the composite layer is It was 32%. In addition, the force required to crush the obtained heating resistor is approximately 0.5 kg in crushing strength in the case of the conventional technology.
It was 2.1 kg.

Example 1O Ni containing 52% nickel with a diameter of 0.5 mm as a core wire
Using a -Fe wire, a platinum wire was wound and cut in the same manner as in the steps shown in FIGS. 10(A) to (E), and then lead wires were welded. Alumina particles were attached to the welded part and the platinum wire using the dip method. The dip method involves creating a solution in which alumina particles are dispersed in an organic solvent (terpineol).

In this method, a heating resistor with a platinum wire wrapped around the core wire and a lead wire attached is dipped in this and pulled up, thereby attaching alumina particles to the heating resistor. At this time, one end of the core wire was exposed. Next, the alumina was fired in an electric furnace at 1500° C. for 2 minutes. Next, it was immersed in a mixed acid of nitric acid and sulfuric acid at a temperature of 80°C for 3 hours,
The core wire was removed by etching. This was coated with pb○-3iOz glass powder with a softening point of 600°C, and heated to 820°C.
The alumina was fired for 90 minutes to penetrate into the fired alumina layer to form a composite layer. The crushing strength of the heating resistor obtained is 1
．． It weighed 8 kg. Further, the volume fraction of the coating glass in the composite material layer was 41%.

Example 11 In the same manner as in Examples 9 and 1o, heating resistors having different volume fractions of the glass component in the composite layer were produced. A heating resistor with a small volume fraction of glass components is obtained by simultaneously depositing ceramic particles and glass particles on a platinum wire at a predetermined ratio using the same electrophoresis method as in Example 9, and firing under conditions that sufficiently melt the glass. It was produced without subsequent glass coating. At these times, if ceramic particles and glass particles are mixed in advance at a predetermined ratio, heated to melt the glass, solidified, and then crushed, composite particles are prepared in advance and attached to a platinum wire. The uniformity of the composite layer is increased. For example, when particles are attached using electrophoresis, the effect of the surface charge of a single particle is used, so the way the particles attach differs depending on the type of particle. It does not necessarily adhere at the same mixing ratio, and there is a possibility that the adhering mixing ratio may be uneven depending on the location. However, this problem can be avoided by preparing each particle in advance into composite particles having a predetermined blending ratio. In addition to alumina, ceramic components include silicon carbide, silicon nitride,
Aluminum nitride was used. Alumina has a thermal conductivity of 21
W/m-K.

Silicon carbide at 40W/m-, silicon nitride at 12W/m-
-, aluminum nitride is 2'lW/m-. When materials other than alumina were used, the firing after deposition was performed in an inert gas.

The crushing strength and response time of the manufactured heating resistor were investigated. Figure 12 shows the volume ratio R (%) occupied by the glass component in the composite layer on the horizontal axis and the crushing strength F on the vertical axis.
(kg) and shows the relationship between the two.

The broken line Fo indicates the crushing strength required for the heating resistor, and the area surrounded by solid lines C1 and D is the range where the crushing strength exhibited by the heating resistor manufactured in this example exists. The crushing strength varies depending on the type of ceramic component used. Figure 13 is a graph showing the relationship between the volume ratio R (%) of the glass component on the horizontal axis and the response time T (, ms) of the heating resistor on the vertical axis, as in Figure 12. be. There are also differences in response time depending on the type of ceramics used.

When the volume fraction of the glass component in the composite layer was less than 2%, the strength of the coating layer was so low that it could not be handled with tweezers or the like. Furthermore, when fired at high temperature for a long time to increase strength, the properties of the platinum wire change, making it unsuitable for use as a heat-generating resistor.

If the volume percentage of the ceramic component in the composite layer is less than 40%, that is, if the volume percentage of the glass component exceeds 60%, the response as an air flowmeter will be the same as when platinum wire is covered with glass alone. However, the effect of combining ceramics and glass was not good.

Example 12 In Examples 9 to 11, the metal wire serving as the heat generating resistance wire was continuously wound around the metal core wire, and the lead wire was connected after cutting it to a predetermined length. However, in this example After cutting the metal core wire to a predetermined length and connecting lead wires to both ends of the metal core wire, one end of the metal wire that will become the heating resistance wire is connected to one of the lead wires, and this is connected to the metal core wire. After winding, the other end was connected to the other lead wire. 14th (A) to 14th (D) show the manufacturing procedure of the heat generating resistor that has been moved laterally in this way, and (A) is 14th.

(B) shows a state in which a platinum-iridium alloy lead wire 3 with a diameter of 0.13 mm+ is connected to both ends of a molybdenum core wire 5 with a diameter Q of 5 mm and a flat portion at both ends. After welding the platinum wire (heat-generating resistor) 2 at the connection part 21, it is wound around the core wire 5, and the other end is welded to the other lead wire 3 at the connection part 21, (C) shows the state in which the heat-generating resistance wire 2 is combined (D) shows a state in which glass powder is coated, fired, and permeated into the fired layer 4 to form a composite layer.

Example 13 An example of a heating resistor formed on an alumina substrate will be described with reference to FIGS. 15(A) to 16(D) and FIG. 16. Width 4
m, length 10wn, thickness 0.3mm alumina substrate 91
A platinum thick film circuit 94 was formed thereon by a lift-off method.

15(A) to (D) show the main steps of the lift-off method, and FIG. 12A shows a photoresist mask 9 on a substrate 91.
2 shows the process of forming 2.

(B) shows the step of applying platinum paste 93 thereon to form a film, (C) shows the step of swelling the resist with a developer and shearing the film, and (D) shows the step of shearing the film by applying a platinum paste 93 thereon. The steps of etching removal and firing to form a platinum circuit 94 are shown in cross-sectional views of the heating resistor. The platinum film circuit was patterned with a line width of 400 μm and a line spacing of 100 μm, and a resistance value of 12Ω.
And so. Large area portions were provided at both ends of the pattern, and lead wires 95 made of platinum iridium alloy were connected to these portions by brazing. Next, a paste containing a 2:3 ratio of PbO-8iOz glass and alumina with a softening point of 600°C (7) was applied to cover the platinum thick film circuit, and heated to 800°C.
The composite layer was baked for 15 minutes to form a composite layer of 96°. The response speed of the air flowmeter using the obtained heating resistor 100 is as follows:
This was twice as high as when the circuit was covered only with glass.

〔Effect of the invention〕

According to the present invention, since the metal wire can be wound continuously, the heating resistor can be manufactured with a high degree of automation, and because it is supported by the lead wire and glass, it is easy to handle and has excellent workability.

Furthermore, since both ends of the glass member are closed, it is possible to obtain a heat generating resistor whose responsiveness is not impaired by dust or ionic substances in the air, and whose characteristics do not deteriorate.

Furthermore, according to the present invention, since the support member covering the heating resistor is made of a composite material layer of ceramics and glass, it is possible to obtain sufficient crushing strength and response speed.
A heat generating resistor for an air flowmeter that is easy to handle and has good performance was obtained.

Since the element has a hollow part and the glass component contained in the composite material layer forming the supporting member forms the surface layer and forms a continuous phase reaching the hollow part, the glass component provides sufficient strength as the supporting member. Ta.

The ceramic component contained in the composite layer has a thermal conductivity of at least 10 W/m-.

A heating resistor for an air flow meter with high responsiveness was obtained, in which the current of the heating resistor, which follows changes in the surface temperature of the support member covering the heating resistor, changed quickly.

Since the ratio of the glass component in the composite material layer forming the support member is 2 to 60%, it is possible to obtain a high response speed while maintaining the necessary crushing strength, and it is easy to handle and generates heat with good performance. A resistor was obtained.

Since the composite material layer constituting the support member contains a glass component with a softening point of 700°C or less and a glass component with a softening point higher than 700°C, the workability of coating the glass component is improved.

Furthermore, the heating resistor is formed as a membrane circuit on a ceramic substrate, and the substrate and membrane circuit are covered with a composite material layer made of ceramics and glass. A heating resistor for a flowmeter is obtained, and the surface to which dust contained in the airflow adheres is small compared to the entire surface of the heating resistor, reducing the rate of change in performance due to adhesion of dust, etc. It became possible.

Further, according to the present invention, a member consisting of a metal core wire, a metal wire wound around the metal wire serving as a heating resistor, and a lead wire system connected to both ends of the metal wire is prepared, and then ceramic particles are applied to the wound metal wire. A process of adhering, coating and firing, a process of removing the metal core wire, and a process of melting and melting the glass components.
The method for producing a heating resistor for an air flowmeter includes the steps of coating and infiltrating a fired ceramic layer to form a composite layer, so that a heating resistor for an air flowmeter that is easy to handle and has good responsiveness can be produced. can get.

If ceramic particles and glass particles are attached in a mixed state and fired, the manufacturing procedure will be simplified.If ceramic particles and glass particles are attached as a composite particle in advance, the mixing ratio of the attached ceramic and glass will be reduced. This has the effect of eliminating unevenness and making the performance of the heating resistor uniform.

In addition, when glass particles and ceramic particles are mixed and attached, fired, and then melted and coated with glass, the glass component penetrates into the hollow part of the sensor, and the surface layer is covered with the glass component, which can be used as a support member. This has the effect of increasing the strength of

[Brief explanation of the drawing]

Fig. 1 is a sectional view of a hot wire air flow meter according to the present invention, Fig.
The figure is a wiring diagram of a drive circuit related to the hot-wire air flowmeter of FIG. D) is a manufacturing process diagram of the heating resistor shown in FIG. 3, FIG. 4(E) is an enlarged view of a portion of the heating resistor shown in FIG. 4(D), and FIG. 5 is a hot wire method according to the present invention. A graph showing the response characteristics of an air flow meter, FIG. 6 is an explanatory diagram showing another embodiment of the method for manufacturing a heat generating resistor according to the present invention, and FIG. 7 is a cross section of another heat generating resistor according to the present invention. 8(A) to 8(D) are manufacturing process diagrams of the heating resistor of FIG. 7, FIG. 9 is a longitudinal sectional view of the heating resistor of another embodiment of the present invention, and FIG. A) to (E) are manufacturing process diagrams of the heating resistor shown in Figure 9, Figure 11 is a cross-sectional view showing the state in which ceramics and glass are attached to the heating resistor wound around the core wire, and Figure 12 is a diagram showing the manufacturing process of the heating resistor shown in Figure 9. A graph showing the relationship between the volume % of the glass component and crushing strength, FIG. 13 is a graph showing the relationship between the volume % of the glass component and the response time, and FIGS. 14 (A) to (D)
15 is an explanatory diagram showing another example of the manufacturing process of the heating resistor shown in FIG. 9, FIGS. The figure is a perspective view of an embodiment of a heating resistor equipped with a membrane circuit. DESCRIPTION OF SYMBOLS 1... Heating resistor, 2... Platinum wire, 3... Lead wire, 4... Support member, butt... Core wire, 6... Air temperature measuring resistor, 8... Support body , 71... Main passage, 72... Bypass passage, 73... Body. (D) Me 5 prisoners B=! 14th country

Claims (1)

[Scope of Claims] 1. A heating resistor installed in an air passage for measuring the air flow rate, controlling the current of the heating resistor, and using the output voltage of the heating resistor as a signal corresponding to the air flow rate. In a hot wire air flow meter including a drive circuit section to be taken out, the heating resistor includes a bobbinless metal wire wound into a coil, a metal lead wire connected to both ends of the wire,
A hot wire type air flowmeter characterized in that it includes a connection portion between the metal wire and the metal lead wire, and a support member that covers and supports the metal wire. 2. In claim 1, the supporting member has a viscosity of 1 at a temperature of 800°C to 850°C.
A hot wire air flowmeter made of glass with a diameter of 0^4 poise or more and 10^7 poise or less. 3. In claim 1 or 2, the support member has a diameter of 50 to 6.
5 wt% SiO_2, 20-35 wt% PbO, 1
0-20% by weight of R_2O (R_2O is K_2O and Na
A hot-wire air flow meter that is lead potash glass, lead soda glass, or lead potash soda glass whose main component is lead potash glass (sum of _2O). 4. In claim 1 or 2, the support member has a diameter of 65 to 7.
5 wt% SiO_2, 4-15 wt% RO (RO is the sum of MgO, CaO, and BaO), 10-25 wt% R
A hot-wire air flow meter that is soda-lime glass, soda-barium glass, potash-lime glass, or calibarium glass whose main component is _2O (R_2O is the sum of K_2O and Na_2O). 5. The hot wire air flowmeter according to claim 1 or 2, wherein the support member is made of borosilicate glass. 6. Includes a heating resistor installed in the air passage that measures the air flow rate, and a drive circuit unit that controls the current of the heating resistor and extracts the output voltage of the heating resistor as a signal corresponding to the air flow rate. In the method for manufacturing a hot wire air flowmeter, the heating resistor is made of a metal core wire of a predetermined length, a metal wire wound around the metal core wire to become a heating resistance wire, and lead wires welded to both ends of the metal wire. A hot-wire air flow meter characterized by comprising the steps of: preparing a member made of the metal wire, then overcoating the welded portion and the metal wire with glass and firing the same, and removing the metal core wire. Production method. 7. Includes a heating resistor installed in the air passage that measures the air flow rate, and a drive circuit unit that controls the current of the heating resistor and extracts the output voltage of the heating resistor as a signal corresponding to the air flow rate. In the method of manufacturing a hot wire air flowmeter, the heating resistor is composed of a glass core wire of a predetermined length, a metal wire wound around the glass core wire to become a heating resistance wire, and lead wires welded to both ends of the metal wire. A method for manufacturing a hot-wire air flow meter, comprising the steps of preparing a member, and then overcoating the metal wire between the welded parts with glass and firing it. 8. The method of manufacturing a hot wire air flowmeter according to claim 6 or 7, wherein the glass overcoating the metal wire is glass having a viscosity of 10^6 poise to 10^7 poise at a temperature of 800 to 850 °C. 9. In claim 6, the glass overcoating the metal wire is any one of lead potash glass, lead soda glass, lead potash soda glass, soda lime glass, soda barium glass, potash lime glass, calibarium glass, and borosilicate glass. A method for manufacturing a hot wire air flow meter. 10. Includes a heating resistor installed in the air passage that measures the air flow rate, and a drive circuit unit that controls the current of the heating resistor and extracts the output voltage of the heating resistor as a signal corresponding to the air flow rate. In a hot wire air flow meter; the heating resistor is screwed into a cylindrical glass member along the inner wall surface of the glass member with the same central axis inside the glass member, and both ends extend outside the glass member. a coil of metal wire electrically drawn out by a metal lead, and
A hot wire airflow meter characterized in that both ends of the glass member are closed. 11. Includes a heating resistor installed in the air passage that measures the air flow rate, and a drive circuit unit that controls the current of the heating resistor and extracts the output voltage of the heating resistor as a signal corresponding to the air flow rate. In the method for manufacturing a hot wire air flowmeter, the heating resistor is formed by: spirally winding a metal wire around a sublimable core wire; and electrical leads welded to both ends of the wound wire. A hot wire air flowmeter characterized by comprising the steps of: covering the wire together with the core wire with a glass material; and sublimating the core wire and sintering the glass material by heat treatment. manufacturing method. 12. Includes a heating resistor installed in the air passage that measures the air flow rate, and a drive circuit unit that controls the current of the heating resistor and extracts the output voltage of the heating resistor as a signal corresponding to the air flow rate. In a hot wire air flow meter; the heating resistor includes: a metal wire coil serving as a heating resistance wire, a lead wire connected to the metal wire coil, and a support member that covers and supports the connection portion of the metal wire coil and the lead wire. 1. A hot wire air flow meter, wherein the support member is formed of a composite layer of ceramics and glass. 13. In claim 12, the hot wire type air has a hollow part, and a glass component contained in the composite layer forming the support member forms a surface layer and the glass component is a continuous phase reaching the hollow part. Flowmeter. 14. The hot wire air flowmeter according to claim 12 or 13, wherein a ceramic component included in the composite material layer forming the support member has a thermal conductivity of at least 10 W/m·K. 15. In any one of claims 12 to 14, the composite material layer forming the support member contains a glass component of 2 to 60% by volume.
Includes hot wire air flow meter. 16. In any one of claims 12 to 15, the composite material layer forming the support member is a hot-wire type air containing a glass component having a softening point of 700°C or less and a glass component having a softening point higher than 700°C. Flowmeter. 17. Includes a heating resistor installed in the air passage that measures the air flow rate, and a drive circuit unit that controls the current of the heating resistor and extracts the output voltage of the heating resistor as a signal corresponding to the air flow rate. In the hot wire air flowmeter; the heating resistor includes a heating resistance wire made of a membrane circuit formed on a ceramic substrate, and a composite material layer of ceramic and glass that covers and supports the membrane circuit. Features of hot wire air flow meter. 18. Includes a heating resistor installed in the air passage that measures the air flow rate, and a drive circuit unit that controls the current of the heating resistor and extracts the output voltage of the heating resistor as a signal corresponding to the air flow rate. In a method for manufacturing a hot wire air flow meter, the heating resistor includes a metal core wire of a predetermined length, a metal wire wound around the metal core wire to become a heating resistance wire, and lead wires connected to both ends of the metal wire. a step of attaching and coating the wound metal wire with ceramic particles and firing it; a step of removing the metal core wire; and a step of melting and coating the glass component and firing the ceramic. A method for manufacturing an air flow meter, comprising the step of forming a composite material layer by infiltrating the layer. 19. Includes a heating resistor installed in the air passage that measures the air flow rate, and a drive circuit unit that controls the current of the heating resistor and extracts the output voltage of the heating resistor as a signal corresponding to the air flow rate. In the method for manufacturing a hot wire air flow meter, the heating resistor is made of a metal core wire of a predetermined length, a metal wire wound around the metal core wire to serve as a heating resistor, and lead wires connected to both ends of the metal wire. A step of preparing a member consisting of the wire, a step of attaching ceramic particles and glass particles to the wound metal wire, coating and firing it to form a composite material layer, and a step of removing the metal core wire. A method for manufacturing an airflow meter. 20. In claim 19, after forming the composite material layer,
A method for manufacturing a hot wire air flowmeter, including a step of melting and coating glass on the composite layer. 21. The method of manufacturing a hot-wire air flowmeter according to claim 19 or 20, wherein the ceramic particles attached to the wound metal wire are composite particles of ceramic and glass prepared in advance. 22. An anemometer comprising the heating resistor according to any one of claims 1 to 21 and means for detecting the temperature of the heating resistor. 23. An internal combustion engine comprising the hot wire air flow meter according to any one of claims 1 to 21 in an intake passage, which improves transient response to sudden changes in air flow rate and can supply an appropriate amount of fuel. . 24. Includes a bobbinless metal wire wound into a coil, a metal lead wire connected to both ends of the wire, a connection portion between the metal wire and the metal lead wire, and a support member that covers and supports the metal wire. A heating resistor for a hot-wire air flow meter, which is characterized by: 25. Claim 24, wherein the supporting member has a viscosity of 1 at a temperature of 800°C to 850°C.
A hot wire air flowmeter made of glass with a diameter of 0^4 poise or more and 10^7 poise or less. 26. In claim 24 or 25, the support member comprises 5
0-65 wt% SiO_2, 20-35 wt% Pb
O, 10-20% by weight of R_2O (R_2O is K_2O
A heating resistor for a hot-wire air flowmeter that is made of lead potash glass, lead soda glass, or lead potash soda glass, the main component of which is the sum of Na_2O and Na_2O. 27. Claim 24 or 25, wherein the support member comprises 6
5-75 wt% SiO_2, 4-15 wt% RO (
RO is the sum of MgO, CaO, and BaO), 10 to 25% by weight of R_2O (R_2O is the sum of K_2O and Na_2O)
A heating resistor for a hot wire air flowmeter that is made of soda-lime glass, soda-barium glass, potash-lime glass, or kalibarium glass, the main component of which is soda-lime glass, soda-barium glass, potash-lime glass, or potassium glass. 28. The heating resistor for a hot wire air flowmeter according to claim 24 or 25, wherein the support member is made of borosilicate glass. 29. A step of preparing a member consisting of a metal core wire of a predetermined length, a metal wire wound around this to become a heating resistance wire, and a lead wire welded to both ends of the metal wire, and then the step of preparing the welded portion. A method for manufacturing a heating resistor for a hot wire air flow meter, comprising the steps of: overcoating the metal wire with glass and firing it; and removing the metal core wire. 30. Preparing a member consisting of a glass core wire of a predetermined length, a metal wire wound around the glass core wire to become a heat generating resistance wire, and a lead wire welded to both ends of the metal wire, and then a step between the welded parts. A method for producing a heating resistor for a hot wire air flow meter, comprising the steps of overcoating the metal wire with glass and firing the same. 31. A cylindrical glass member, which is screwed into the glass member along the inner wall surface of the glass member with the same central axis, and whose both ends are electrically led out of the glass member by metal leads. 1. A heating resistor for hot-wire air flow, characterized in that the glass member is closed at both ends. 32. Except for the step of spirally winding a metal wire around a sublimable core wire and the electrical lead-out parts welded to both ends of the wound wire, the wire is made of glass material along with the core wire. 1. A method of manufacturing a heating resistor for hot wire air flow, comprising the steps of: coating; and sublimating the core wire and sintering the glass material through heat treatment. 33. A metal wire coil serving as a heat-generating resistance wire, a lead wire connected to the metal wire coil, and a support member that covers and supports the connection portion of the metal wire coil and the lead wire, the support member being a composite of ceramics and glass. A heating resistor for an air flow meter, characterized by being formed of a material layer. 34. Preparing a member consisting of a metal core wire of a predetermined length, a metal wire wound around the metal wire to become a heating resistance wire, and lead wires connected to both ends of the metal wire, and A step of attaching and coating ceramic particles to a wire and firing it, a step of removing the metal core wire, and a step of melting and coating a glass component on the ceramic layer and infiltrating the fired layer of ceramic to form a composite layer. 1. A method of manufacturing a heating resistor for an air flow meter, the method comprising: forming a heat generating resistor for an air flow meter. 35. Preparing a member consisting of a metal core wire of a predetermined length, a metal wire wound around the metal wire to serve as a heat generating resistor, and lead wires connected to both ends of the metal wire, and the wound metal wire 1. A method for producing a heating resistor for an airflow meter, comprising the steps of: attaching ceramic particles and glass particles to a material, coating and firing them to form a composite material layer; and removing the metal core wire.