JP2842973B2 - Air flow meter - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates, for example of a preferred air flow rate to detect an intake air flow amount of the automobile engine.

[0002]

2. Description of the Related Art In an automobile engine, reduction of harmful exhaust gas and improvement of fuel efficiency are urgently required to protect the natural environment and save energy. In response, electronic control devices that use a microcomputer to perform high-precision control of fuel and ignition timing have become mainstream.
This electronic control device requires many sensors and actuators for obtaining information from the engine. However, with the increase of these electrical components, reduction in size and weight has become an important issue.

The sensors and actuators determine the system accuracy of the electronic control unit. In addition to the essential operation accuracy (for example, the detection accuracy of the sensor), the fact that they do not malfunction due to noise is an extremely important item. ing.

In view of the above background, as an air flow meter aimed at miniaturization and improvement of noise resistance, for example, Japanese Patent Application Laid-Open No.
There is an example shown in Japanese Patent No. 7817.

[0005]

In this example, the mounting pins of the temperature-sensitive resistors (heat generating resistors for measuring the air flow rate and the temperature compensating resistors ) used for detecting the air flow rate are welded to the lead frame. Triggered by pin and lead frame
Conductivity supporting each of the thermal resistor and the temperature compensating resistor
A supporting member (lead member) is formed, and the heating resistor and the temperature compensating resistor are connected to a driving circuit for air flow measurement via the conductive supporting member.
Since it is composed of two parts, the number of parts is large, and since there are work steps such as connection of pins and lead frames by welding, there is a point to be improved in terms of workability.

Further, in order to prevent electronic circuits due to noise, a shield case and a feedthrough capacitor are used in a circuit module, but a complicated device is also required for electrical connection between the shield case and a metal base .

[0007] The present invention has been made in view of the above, the main
The main purpose is the heating resistor of the air flow meter and the resistor for temperature compensation.
Simplification of the number of parts of the body support member, and thus the air flow meter
The present invention aims to rationalize the manufacture of the semiconductor device and to achieve prevention of a malfunction of a circuit due to intrusion of noise with a simple structure.

[0008]

Means for Solving the Problems A first method for solving the above problems is described below .
Basically, the heat generation resistance for air flow measurement
Body, temperature compensating resistor, the heating resistor and temperature compensating
Air flow with circuit board electrically connected to resistor
In total, the gold in the metal base for mounting the circuit board
From the circuit board mounting surface through the holes provided in the metal base
Mold resin is protruded toward the opposite surface.
The heat generating resistor and the temperature compensating resistor
Each conductive support member that supports in the electrical state is buried except for a part.
And a conductive support member of the heating resistor and a resistor for temperature compensation.
Each of the conductive support members is formed by pressing a metal plate.
Of one of these conductive support members.
The circuit board is arranged in an array mode in which the edges are all aligned.
Electrically connected and conductive support of the heating resistor
The material and the conductive support member of the temperature compensating resistor are
The antibody and the temperature compensation resistor are different in the air flow direction
Bent forming with different shapes so that they can be mounted in positions
(This is referred to as the first problem solving solution.)
Stage).

Further , in connection with the above-mentioned invention, in order to enhance the accuracy of detecting the air flow rate, for example, the molding resin is used in the molding resin.
A step is formed on the end face of the heating resistor and the temperature compensation resistor mounting side.
Is attached to the surface of one of the steps.
Conductive support of one of thermal resistor and temperature compensating resistor
The holding member protrudes as it is, and the
A rib is attached integrally with the mold resin, and through this rib
Provide one with the other conductive support member protruding.
Proposal to (referred to as second means for solving problems).

Further, a heating resistor for measuring an air flow rate, a temperature,
Temperature compensation resistor, the heating resistor and the temperature compensation resistor
A circuit board electrically connected to the circuit board, and mounting the circuit board
Metal base, housing for circuit coupled with the metal base
In an air flow meter provided with a housing,
Has one end connected to the circuit board and the other end
Metal terminator that serves as a connector element for connecting parts
The metal terminal has one end and the other end
We propose a device that has been subjected to such a surface treatment (this is referred to as a third means for solving the problem).

Further, a heating resistor for measuring an air flow rate, a temperature
Temperature compensation resistor, the heating resistor and the temperature compensation resistor
A circuit board electrically connected to the circuit board, and mounting the circuit board
Metal base, housing for circuit coupled with the metal base
In an air flow meter provided with a housing,
Has one end connected to the circuit board and the other end
Metal terminator that serves as a connector element for connecting parts
And the metal terminal is provided on the circuit board.
One end of the side connected to the
Buried in the resin surface.
On the other hand, the metal terminal is located at a low position like a valley bottom and its surface
Relationship between the width W1 of the exposed portion and the width W2 of the metal terminal
W1 <W2, and the gold of the housing
On the other side that is combined with the genus base, a cover is
A coupling groove is provided, and the groove is positioned inside the groove.
The height of the side wall of the housing is increased (this is referred to as fourth problem solving means).

Furthermore, a heating resistor for measuring the air flow rate,
Temperature compensation resistor, the heating resistor and the temperature compensation resistor
A circuit board electrically connected to the circuit board, and mounting the circuit board
An air flow meter having a metal base, wherein the circuit board
Has a filter circuit for removing noise.
Grounding terminal of the road and a grounding protrusion provided on the metal base
Part between one ground terminal and the ground protrusion.
More than one aluminum wire bonding
Suggest those that (referred to as fifth means for solving problems).

[0013]

The function of the first means for solving the problem: for measuring the air flow rate
Conventionally used conductive support members for heating resistors and temperature compensation resistors
Multiple members (eg metal frame and pin members)
Each metal plate is press-formed without being divided into
By configuring one of the members, as it is an insulating holder for welding with conventional such pins and the metal frame as required
Can be buried while leaving a part of the mold resin
And the number of parts can be reduced. Further, a small-sized conductive support member can be realized by cold pressing.

Further, a conductive support member of the heating resistor and
The conductive support member of the temperature compensation resistor is
Can be molded into any shape, especially for air flow measurement.
Thermal resistor and temperature compensating resistor have different air flow direction
Bent forming with different shapes so that they can be mounted in positions
Even if, at an array mode having one end aligned in all a row
Since it can be electrically connected to the circuit board,
Connection work with the circuit board is performed while preventing scattered locations
Make it easier.

Further , as described above, all the conductive support members
If one end is arranged in a line, the mold resin
At the time of molding, it is a press molded product that is all connected together,
Molded together with the conductive support members of
It can be set in a resin mold and buried in resin.
After the molding of the grease, disconnect the joints and separate the conductive support members.
It is possible to incorporate a manufacturing process such as independence
Thus, the manufacturing operation can be rationalized .

Operation of the Second Means for Solving the Problem : Measurement of Air Flow Rate
The heating resistor for temperature and the resistor for temperature compensation
When mounting on a support member, the temperature compensation resistor
Positioned staggered to avoid thermal effects on body side
However, in this way, the heating resistor and the temperature compensating resistor
If the position is shifted, the conductive support
Each resistor (heating resistor) from the base of the mold resin of the holding member
Antibody, temperature compensation resistor) The distance to the mounting position is extremely large
different.

[0017] Therefore, the molding resin and the conductive
Heat transmitted to each resistor through the electrical support member (for example, an air flow meter
To use as an engine intake air flow sensor
Is the difference in the amount of heat transferred from the engine)
Differences can offset these thermal noises from each other.
There is an error in air flow measurement accuracy because there is no measurement).

However, according to the present invention, the conductive support portion
According to each conductive support member on the mold resin surface that protrudes the material
To form a step surface, and the rib provided on one side
From the surface and the rib, the mounting position of the heating resistor of each conductive support member and
And the length to the mounting position of the temperature compensation resistor can be adjusted in advance.
This allows the heating resistor and temperature compensation resistor to receive
External thermal noise can be equalized, and these thermal noise
Can improve the measurement accuracy of the temperature-sensitive resistor.
Can be.

Operation of the third means for solving the problems : the air flow meter
One end of the metal terminal provided in the housing is
Circuit board and the other end is connected to external electrical components.
Of the metal terminal
By applying different surface treatments to the end and the other end,
There is a point.

For example, one end of a metal terminal is
Circuit board and wire bonder housed inside housing
When connecting with a terminal, etc.
Kel plating is preferable, and connector
The other end of the bare terminal fits securely with the external plug
To be resilient and corrosion resistant on its surface
Surface treatment of metal materials (eg gold plating and tin plating)
It is preferable that the present invention meets such a demand.
Can be

Function of the fourth means for solving the problem: When the housing of the air flow meter is molded from a resin, and a part of the metal terminal is buried in the resin while leaving its surface, the resin molding is conventionally performed. In this case, a gap is formed between the metal terminal and the mold resin due to the resin contraction after molding the housing due to a difference in thermal expansion between the metal terminal and the resin, and the mounting strength of the terminal is significantly reduced.

However, as in the means for solving the problem, the metal terminal is located at a low position at the bottom of the valley with respect to the resin surface, and the relationship between the width W1 of the surface exposed portion of the metal terminal and the width W2 of the terminal is expressed as W1 <W2. Then, a force acts such that the resin corresponding to the width of W2-W1 contracts in the direction of sandwiching the front and back surfaces of the metal terminal, and as a result, the mounting strength of the metal terminal can be increased. In addition, the housing
On the other side of the ring that is joined to the metal base,
A groove is provided around the circumference to connect with the cover.
The adhesive is filled to join the cover to the
The height of the housing side wall located inside the groove
Adhesive flows inside the housing due to the height
Can be prevented.

[0023] When the ground connection via a filter circuit for the electronic circuit noise removal using the working ... air flow measurement of a fifth means for solving problems, conventionally using a metal frame or the like as a ground terminal, it It had been welded to a substrate, etc. On the other hand, if wire bonding is used for the ground connection as in the means for solving the problem, it is possible to reduce the weight of the connection member and simplify the connection work. However, since wire bonding is a wire, the impedance is high with respect to the metal frame. However, if two or more ground wire bondings per terminal are used for the noise removal filter circuit, the overall wire cross-sectional area can be increased, so that low impedance can be achieved and a large-capacity ground can be obtained. The protection effect against

[0024]

BRIEF DESCRIPTION OF THE DRAWINGS FIG.

FIG. 1 is a diagram showing a temperature-sensitive resistor (a heating resistor for measuring an air flow rate and a temperature ) in an air flow meter according to an embodiment of the present invention.
Plan view showing a support structure (support ) of the temperature compensation resistor) ;
FIG. 2 is a front view and FIG. 3 is a side sectional view. 4, 5, and 6 are specific examples of the temperature-sensitive resistor used in the above embodiment. FIG. 7 is a perspective view of a conductive support member (lead member) before assembling a substrate. FIGS. explanatory view showing a bonding state of the dissimilar metal to the conductive support member used in FIG. 10, FIG. 1
FIG. 1 is an explanatory diagram showing a state before the conductive support member is used.

[0026] This example illustrates the measures the engine intake air flow rate if example embodiment.

1 to 3, reference numeral 1 denotes a metal base made of aluminum. As shown in FIG. 7, the metal base 1 is press-formed, and a pair of support members for supporting a temperature-sensitive resistor is provided near the center thereof.
A hole 17 is provided for inserting and setting the conductive support member 21 and a pair of conductive support members 22 similarly. This hole 1
In a state where the conductive support members 21 and 22 are set on the column 7, a columnar resin 4 (shown in FIGS. 1 to 3) is molded, and these conductive support members are placed on the metal base via the resin 4 as an insulator.
The base 1 is integrally connected.

A part of the molding resin 4 is shown in FIGS.
Mold hole 17 in the metal base 1 top as shown in
Is formed on the metal base 1 in such a manner that the remaining columnar portion passes through the hole 17, and a part of the molding resin 4 is applied to the step 16 to prevent the resin from falling off. The hole 17 and the step 16 are non-circular.
This is to prevent rotation of the resin 4 when a gap is formed between the mold resin 4 and the hole 17 due to shrinkage after molding.

The metal base 1 has a step 1 for molding.
6, the step 15 and the step 1
4 is press formed. Among these, the step 15 is for setting a mold at the time of molding the molding resin 4.
Metal circuit board 6 to be described later (shown in FIG. 15) stepped portion 14
It becomes an adhesive groove for bonding to the base 1.

A projection 41 (see FIGS. 1 and 3) which is at the same level as the height of one surface 18 (circuit board mounting surface) of the metal base 1 is integrally formed on the upper surface of the mold resin 4. The protrusion 41 has a flat upper surface and serves as an adhesive surface of the circuit board together with the one surface 18 of the metal base.
Is provided, the metal base 1 has a recess, and thus plays a role of securing an adhesive surface for a circuit board in the recess. Also, the conductive support portion of a part of the upper surface of the mold resin 4
One end of the timber 21 (the circuit board connecting portion) 21a, 21b
Is molded to be one step higher in order to facilitate connection with a circuit board mounted on the metal base 1.

The metal base 1 includes, in addition to the elements described above,
Protrusions 11, 12 provided on metal base 1 by pressing
The projections 12 are used for positioning when fixing the circuit board described later, and the projections 11 are electrodes for wire bonding for connecting to the ground of the circuit board. Money
Genus base 1 to the upper surface, the frame-like projection 13 for fitting the housing 5 will be described later (shown in FIG. 13) are molded integrally with the metal base 1.

The conductive support member 21 and 22, a part (tip) protrudes from the mold resin 4, the heating resistor 31 for air flow measurement is mounted on the projecting portion of the conductive support member 21, conductive support member 22 The temperature compensating resistor 32 is attached by welding. The conductive support members 21 and 22 are electrically insulated by the mold resin 4 and are fixed to the metal base 1 by the mold resin 4.

Heating resistor 31, Temperature compensating resistor 32
Have the same temperature-resistance characteristics, and in this embodiment, since they are used for an air flow meter, the heating resistor 31 has a constant resistance value even if the air flow rate increases or decreases from a circuit described later. heating current is controlled supply for maintaining, while the resistor antibody 32
Is used as a temperature compensation resistor of the heating resistor 31.

[0034] These resistors antibodies 31 and 32, for example, as shown in FIG. 4, the ceramic bobbin 300, the lead 3
01 is fixed with an adhesive 302, a resistance wire 303 (for example, a platinum wire) is wound around and connected to the lead 301, and the surface is covered with a coating agent (for example, glass, polyimide resin, or the like), or as shown in FIG. Like, a resistive film (for example, platinum,
Nickel 305) is formed on the surface of the ceramic bobbin,
One with spiral trimming to adjust the resistance value,
As shown in FIG.
Is formed, and the cap 306 to which the lead 301 is welded is formed.
After the resistance value is adjusted by spiral trimming, the resistance surface is protected by a coating agent 304. These resistors antibodies 31 and 32, guide by welding
It is attached to the tip of the electric support members 21 and 22.

Before the conductive support members 21 and 22 are mounted, they are integrally connected by a connecting portion 23 as shown by a virtual line in FIG. This is for facilitating attachment to the mold at the time of molding with the resin 4, and the connecting portion 23 is cut off after the molding. Also, the conductive support members 21 and
No. 2 is punched out from a single plate by press working as shown in the developed view of FIG. 10, and then bent into a form as shown in FIG.
That is, in the present embodiment, a circuit board as shown in FIG.
6 provided on the metal base 1 on which the metal base 6 is mounted.
7 from the circuit board mounting surface to the opposite surface
The molding resin 4 is protruded and molded.
Heating resistor 31 for air flow measurement and resistor for temperature compensation
32 are electrically conductive.
It is buried except for a part . The conductive support of the heating resistor 31
Holding member 21 and conductive support member 22 of temperature compensating resistor 32
Is a single material formed by pressing a metal plate
And one end 21b, 22 of these conductive support members.
b are arranged in a line so that the circuit board 6
And the conduction of the heating resistor 31
Conductive support member 2 of support member 21 and resistor 32 for temperature compensation
2 means that the heating resistor 31 and the temperature compensating resistor 32 are empty.
Shape each other so that they can be installed at different positions in the air flow direction.
It is bent differently . This configuration
Then, the conductive support members 21 and 22 are respectively
Divided into multiple members (eg metal frame and pin members)
Composed of a single press-formed member without
The conventional method of welding pins and metal frames
Unnecessary for molding resin to be used as insulation holder
It can be buried while leaving a part, and the number of parts is small.
I can do it. In addition, a small conductive support member is formed by cold pressing.
I can do it. Furthermore, these conductive support members 21 and 22
Can be formed into any shape by pressing.
The heating resistor and the temperature compensation resistor are different in the air flow direction.
Bend differently from each other so that
Even if it is shaped, it is arranged in an array where one end is all aligned.
Can be electrically connected to the circuit board 6 by
Connection work with the circuit board is performed while preventing scattered locations
Make it easier. Also, as described above, all the conductive support members 2
If one end of each of the first and second 22 is arranged in a line,
Press molding in which all parts are integrally connected when molding resin
Product, all conductive support members are integrated together
Can be buried in resin by setting it to a mold
After molding the mold resin, disconnect the connection and
Incorporate manufacturing processes such as independent support members
Is possible, and the manufacturing operation can be rationalized .

Since the temperature-sensitive resistor detects the flow of air (air temperature), the temperature-sensitive resistor is connected to the heat-generating resistor 31 with the temperature.
When using degrees compensating resistor 32 in pairs, it is desirable characteristics equal. For this purpose, resistor antibody 31
It is necessary to make the width of the air flow passing through the installation section equal, and the following measures are taken in this embodiment.

[0037] That is, if mounted directly to the conductive support member (plate) 21, 22 on behalf of the resistor antibodies 31 and 32 to the pin, resistor antibody attachment portion of the conductive support member and the width W 'as shown in FIG. 11 the plate The cross section was square (square) having the same thickness W. Thus, as shown in FIG. 7, the conductive support portion
Of the materials 21 and 22, the heat generating resistor mounting portion of the conductive support member 21 is bent so as to be located forward of the temperature compensation resistor mounting portion of the conductive support member 22, and these resistors 31 and 22 are bent.
When installing the 32, the heating resistor attached to conductive support member 21 is performed by the plate thickness surface of the conductive support member, the other, conductive
The temperature compensating resistor attached to the support member 22 is performed by the width surface of the conductive support member <br/>, this time, positioned forward guide
Interval between electrical support members 21 and 21 (temperature-sensitive resistor air passage width)
The distance between the conductive support members 22 and 22 (the temperature-sensitive resistor air passage width) is determined by the thickness W and the width W ′ of the temperature-sensitive resistor mounting portions of the conductive support members 21 and 22. Since they are the same, they can be made equal and the measurement accuracy can be improved.

As shown in FIG. 10, the conductive support member 21,
The weldability of the 22 temperature-sensitive resistors (heat-generating resistors, temperature-compensating resistors) can be improved by adding an R to the corner.

As shown in FIG. 7, the conductive support members 21 and
A different metal is bonded to the P portion of No. 2 (the upper surface of the electrical connection portions 21b and 22b with the circuit board), and in this example, aluminum 24 is clad as shown in FIG. FIG. 9 shows an example in which the bonding pad 25 is fixed with solder or a conductive adhesive 26 in the example. By providing such a dissimilar metal, electrical connection with a circuit board, for example, wire bonding is enabled.

Next, referring to FIG. 3, the heating resistor 31 and the temperature compensation will be described.
The arrangement of the resistor 32 and consideration of the shape of the molding resin 4 related thereto will be described.

The heating resistor 31 and the temperature compensating resistor 32
They are mounted on the conductive support members 21 and 22 with their positions shifted from each other. On the other hand, the conductive support member 2 in the mold resin 4
Steps 43 are provided on the protruded surfaces of the first and second 22 and one of the steps 43 is provided with a temperature- sensitive resistor ( temperature compensation).
The conductive support member 22 of the first resistor 32 is directly projected, and a rib 42 integral with the mold resin 4 is provided on the other step surface, and the other temperature-sensitive resistor (heat-generating resistor) is passed through the rib 42. 31 conductive support members 21 project,
The conductive support member 2 from the step surfaces 43 and the ribs 42 to the temperature-sensitive resistor mounting portion is formed by the step surfaces 43 and the ribs 42.
The length 1 of 1, 22 has been determined.

When the temperature-sensitive resistor 31 is used, for example, as a heating resistor for measuring the air flow rate, and another temperature-sensitive resistor 32 is used as a resistor for temperature compensation, these temperature-sensitive resistors become In order to avoid the thermal effect on the heating resistor side, the compensating one is placed at the shifted position as described above, but if the position of the temperature sensitive resistors is shifted as described above, there is no consideration In this case, the distance 1 from the resin mold surface of the conductive support member to the mounting position of the temperature-sensitive resistor significantly differs for each temperature-sensitive resistor. Therefore, heat transmitted from the outside to the temperature sensitive resistors 31 and 32 via the mold resin 4 and the conductive support members 21 and 22 (for example, when the temperature sensitive resistor is used as an intake air amount sensor of the engine, the heat of the engine ) A difference occurs in the amount of transmission. If the difference in the amount of heat transfer occurs, these thermal noises cannot cancel each other, so that an error occurs in the air flow measurement accuracy.

For this purpose, the distance 1 needs to be adjusted. In this embodiment, the adjustment of the distance 1
The molding resin 4 has a step surface 43 corresponding to the positional deviation of the heating resistor 21 and the temperature compensating resistor 22.
The distance 1 between the conductive support member 21 on the side of the heating resistor 31 and the distance 1
When adjusting the distance 1 of the conductive support member 22 on the temperature compensating resistor 32 side, in addition to the heat transfer amount from the mold resin 4 side, each temperature-sensitive resistor on the conductive support members 21 and 22 is adjusted.
(Heating resistors, temperature compensating resistor) from the mounting position Shirubeden支
It is necessary to consider the difference in the amount of heat radiation at the distance 1 'to the tip of the holding member . Since the amount of heat dissipation is larger on the conductive support member 21 side by 1 'than that on the conductive support member 22, the heat transfer distance 1 on the conductive support member 21 side is anticipated.
Must be somewhat shorter than the conductive support member 22 side.
The rib 42 is provided for the adjustment.

That is, each of the steps 43 and the ribs 42
By adjusting the length 1 of the conductive support members 21 and 22 to the temperature-sensitive resistors 31 and 32 in advance, the amount of external thermal noise received by the temperature-sensitive resistors can be equalized, and these thermal noises can be offset. Therefore, the measurement accuracy of the temperature-sensitive resistor can be improved.

FIG. 12 is a bottom view of the support structure of the temperature-sensitive resistor of the present invention. Two holes 19 for attaching the metal base 1 to another device are arranged on the diagonal line L, and the center C where the temperature sensitive resistor is arranged at a fixed position is arranged on the straight line L. In this way, when a bolt or the like is tightened in the mounting hole 19, an even fixing force is applied to the metal base 1 with only two holes, thereby stably fixing the metal base 1 and thus the temperature-sensitive resistor portion. Can be done. According to the above embodiment, there is an effect that a supporting structure for a temperature-sensitive resistor that is small, lightweight, mechanically stable, and whose detection accuracy is a target even when a plurality of temperature-sensitive resistors are set can be realized. Next, a description will be given of an embodiment of a housing which is combined with a support of the temperature-sensitive resistor. 13A is a plan view of a housing 5 according to an embodiment of the present invention, FIG. 13B is a partial cross-sectional view of a terminal portion, and FIG. 14 is a cross-sectional view of the housing.

The housing 5, the terminal case 5A and the resin was decorated metal terminal 51 Yes integrally molded, and presents a frame-shaped, above-described metal as shown in FIG. 1
It is connected and arranged on the base 1 and its lower surface is
A groove 58 for fitting into the frame-shaped projection 13 of the metal base 1 is formed, and the cover 7 (FIG.
(See FIG. 5). The groove 55 is located outside the side wall 57 of the housing 5 and is formed over the entire circumference of the housing 5. The inner side wall 57 of the groove 55 is made higher. If you do this,
When the adhesive is applied to the groove 55 to join the cover 7, the adhesive can be prevented from flowing into the housing 5.

Each terminal 51 has two locations 51 at both ends.
Although the base materials are the same for a and 51b, different surface treatments are applied. For example, at one end 51a serving as a connector element ,
Ni will be connected to the external plug and reliably fit, subjected to a surface treatment of the resilient and corrosion resistant metal material on the surface (e.g., gold plating or tin plating), the circuit board to the other end 5 1b
And nickel plated to allow for wire bonding 16.

In this embodiment, three terminals 51 are used, and are integrated by a connecting portion 53 before molding to the housing 5. The connecting portion 53 is cut off after the molding. One end 51b of the terminal 51, to perform ultrasonic aluminum wire bonding as described later, it is necessary to ultrasonic energy makes efficiently enough fixed as transmitted to the terminal 5 1. The V-shaped groove mold 54 in FIG. 14 is provided for this purpose.

That is, when adopted in the V-shaped groove mold 54 of FIG. 14, one end 51b of the terminal 51 is buried with a resin by exposing only a part of the surface. And the terminal width W1 and the terminal width W2
W1 <W2.

In this way, a force is exerted on the resin corresponding to the width of W2-W1 to contract in the direction (arrow direction) between the front and back surfaces of the terminal end 51b, and as a result, the mounting strength of the metal terminal is reduced. The above problems can be solved.

In the absence of the above considerations, if a part of the metal terminal is simply resin-molded while leaving the surface thereof, the difference between the thermal expansion of the metal terminal and the resin causes the resin shrinkage after the housing is molded, and the metal terminal and the molding resin are molded. And a gap is formed between them, and the mounting strength of the terminal is significantly reduced.

Next, the overall configuration of the air flow meter of this embodiment will be described.

FIG. 15 is a plan view of the air flow meter of this embodiment.
16 is a sectional view thereof, FIG. 17 is a circuit diagram of an air flow meter, FIG. 18 is an embodiment of a noise prevention filter circuit used in the air flow meter, and FIG. 19 is another embodiment of the filter circuit. FIG. 20 is an embodiment of an air flow meter disposed in an air flow path.

[0054] As shown in FIG. 15, metal base mentioned until now
The housing 5 is connected to the base 1 by fitting and bonding the projections 13 and the grooves 58, and the circuit board 6 is housed inside the housing 5.

On the surface of the circuit board 6, a transistor T,
A detection circuit including an IC (A), a resistor, a capacitor, and the like, and a filter circuit are mounted. The circuit board 6 has an adhesive 64
To the metal base 1.

One end of each of the conductive support members 21 and 22 is connected to a pad 61 on the circuit board 6 by aluminum wire bonding. Similarly, the terminal 51 of the housing 5 and the pad 61 on the circuit board 6 are also connected by wire bonding 63. Have been.

The ground electrode section 11 of the metal base 1 and the circuit board 6 are connected by two aluminum wire bonds 62. Here, the pad 61 of the circuit board 6 is not indispensable, and is unnecessary if the conductor terminal is made of a material capable of aluminum wire bonding. 8, in the portion that fits in the passage through which the detected air in the air flow meter, so as to prevent leakage of air in the sealing member 81, the heating resistor 3
1. The temperature compensating resistor 32 is disposed in the air passage.

The operation as an air flow detector will be described with reference to FIG. The temperature compensating resistor 32, the heating resistor 31, the resistor R8, and the resistors R1 and R7 form a bridge by a part of the operational amplifier A1 in the IC (A). This bridge circuit is stabilized by equation (1).

[0059]

RH = R1 (R8 + Rc) / R7 RH: resistance value of the temperature compensating resistor 32 Rc: resistance value of the heating resistor 31 RH and Rc are each represented by the following equation (2).

[0060]

RH = RHO (1 + αT) Rc = RcO (1 + βT) RHO: resistance value at RH reference temperature RcO: resistance value at Rc reference temperature α, β: temperature coefficient T: temperature Accordingly, heat generating resistor 31, the heating current Ih is supplied at a constant temperature higher than the temperature compensating resistor 3 2.

On the other hand, the relationship between the heated resistor and the air flow rate is expressed by Equation 3 from King's equation.

[0062]

Ih ² Rh = (A + B√q) (dTh) (3) A, B: constants q: air flow rate dTh: temperature difference between the temperature compensating resistor 32 and air. The current is detected by the resistor R1, and the voltage is converted into a voltage signal, a current, or a frequency suitable for output to the outside by the processing circuit DA, and the air flow signal O is output.

[0063] In addition FIG 17, _{V B} power supply (+), G
Is a power supply (-), and OUT is connected to an external load via a wire harness.
Noise is applied by induction and static electricity, and enters the circuit board side. The filter F prevents this intrusion.

The filter F is, as shown in FIGS. 18 and 19, a filter circuit composed of capacitors C1, C2 and ferrite beads B, or a circuit of a three-terminal capacitor C5 and ferrite beads B. Furthermore, these grounds are connected to the metal base 1. This means that when excessive noise is applied to the wire harness, the free electrons of the aluminum of the metal base 1 are emitted (inhaled) and the noise current is prevented from flowing through the circuit board. Therefore, the connection impedance can be reduced, and the number of wire bondings 62 in this portion is two (or two or more).

FIG. 20 shows the air passage 8 of the air flow meter.
This is a detailed illustration of the arrangement of the air flow, and a part q (q = Q / K) of the air Q flowing to the air passage 8 is introduced into the bypass passage in which the temperature-sensitive resistors 31.32 are arranged, and the total air flow rate Is to be detected. A screw 82 penetrates through the mounting hole of the metal base 1, and the air flow meter of FIG. 15 is fixed to the wall of the air passage. If the passage 8 is made of metal, the noise resistance is further improved. By doing so, there is an effect that a small and lightweight air flow meter excellent in the effect of preventing noise can be provided.

As described above, according to the present embodiment, various effects can be obtained.
I do.

[0067]

According to the present invention, the heating resistance of the air flow meter is
Simplification of the number of parts of the support member of the body and the temperature compensation resistor
Streamlining the production of air flow meters, and
Simple structure preventing malfunction of the circuit according to penetration of noise into beauty
And can contribute to the miniaturization, light weight, and high accuracy (noise resistance) of an automobile engine control device.

[Brief description of the drawings]

FIG. 1 shows a temperature-sensitive resistor (heating resistor ) according to an embodiment of the present invention.
Plan view of the support structure of the body

FIG. 2 is a front view of the temperature-sensitive resistor support structure.

FIG. 3 is a side sectional view of the temperature-sensitive resistor support structure.

FIG. 4 is a structural diagram of a temperature-sensitive resistor.

FIG. 5 is a structural diagram of a temperature-sensitive resistor.

FIG. 6 is a structural diagram of a temperature-sensitive resistor.

FIG. 7 is an external view of a conductive support member and a metal base used in the above embodiment.

FIG. 8 is an explanatory diagram showing an example of bonding the conductive support member and a dissimilar metal.

FIG. 9 is an explanatory view showing an example of bonding the conductive support member and a dissimilar metal.

FIG. 10 is an explanatory diagram showing a cross-sectional shape of the conductive support member at a temperature-sensitive resistor welded portion.

FIG. 11 is an explanatory view showing a state of the conductive support member before molding.

FIG. 12 is a bottom view of the temperature-sensitive resistor support structure.

FIG. 13 is a plan view of a housing according to one embodiment of the present invention and a partial cross-sectional view of a terminal part holding shape.

FIG. 14 is a sectional view of the housing.

FIG. 15 is a plan view of an air flow meter according to one embodiment of the present invention.

FIG. 16 is a sectional view of the air flow meter.

FIG. 17 is a circuit diagram of the air flow meter.

FIG. 18 is a filter circuit diagram of the air flow meter.

FIG. 19 is a diagram showing another example of the filter circuit.

FIG. 20 is an explanatory diagram showing a state where the air flow meter is provided in an air passage.

[Explanation of symbols]

1: Metal base , 4: Mold resin, 5: Housing,
Reference numeral 7: cover, 11: protrusion (protruding electrode), 16: non-circular step, 18: one surface of the metal base (circuit board mounting surface), 1
9: Hole for fixing metal base , 21, 22: Conductive support
Wood, different metals provided in 24 ... conductive support member, 31, 32
... temperature-sensitive resistor, 41 ... mold protrusion, 42 ... rib, 4
3: mold step surface, 51: metal terminal, 62: aluminum wire bonding for ground, F: filter circuit.

──────────────────────────────────────────────────の Continuing from the front page (72) Inventor Mitsukuni Tsutsui 2520 Oaza Takaba, Katsuta-shi, Ibaraki Co., Ltd. Inside the Automotive Equipment Division of Hitachi, Ltd. (56) References JP-A-1-97817 (JP, A) JP-A-60-36916 (JP, A) JP-A-61-194316 (JP, A) JP-A-63- 307315 (JP, A) JP-A-64-32050 (JP, A) JP-A-63-191023 (JP, A) JP-A-63-182524 (JP, A) Japanese Utility Model Laid-Open No. 62-71525 (JP, U) (58) Field surveyed (Int. Cl. ⁶ , DB name) G01F 1/68 F02D 45/00 366

Claims (10)

(57) [Claims] 1. A heating resistor for temperature measurement of air flow, temperature compensation
Resistor, heating resistor, temperature compensating resistor and electricity
An air flow meter having a circuit board which is electrically connected to a metal base on which the circuit board is mounted.
Hole from the circuit board mounting surface to the opposite surface
Mold resin is protruded and molded.
Supports the heating resistor and the temperature compensating resistor in a conductive state.
Each of the conductive support members is embedded except for a part of the conductive support member, and the conductive support member of the heating resistor and the conductive member of the temperature compensation resistor are connected.
Each of the electrical support members is formed by pressing a metal plate.
One end of these conductive support members
The circuit board is electrically connected to the circuit board in an all-in-one arrangement.
And the conductive support member of the heating resistor
The conductive support member of the temperature compensating resistor is the heating resistor
And the temperature compensating resistor are in different positions in the air flow direction.
Bend-formed in different shapes so that they can be attached to
Air flow meter, characterized by that. 2. The heating resistor and the temperature compensating resistor.
Each conductive support member is used when molding the molding resin.
A press-formed product that is integrally connected with the molding resin
2. The connection part is separated and independent after shaping.
Air flow meter as described . 3. The metal base is an aluminum plate.
Around the hole through which the molding resin passes,
Non-circular step where a part of is fitted is press-formed
The air flow meter according to claim 1 or 2 . 4. The metal base is provided with an electrode of the circuit board.
Protruding electrode for connecting to a ground terminal and the metal base
The protrusion for fitting with the housing mounted on the
The hollow according to any one of claims 1 to 3, which is formed.
Air flow meter . 5. The heating resistor and the temperature compensating resistor.
Each conductive support member includes a mounting portion for the heating resistor and a temperature compensator.
It is the same width and thickness dimensions mounting portion in square each償用resistor
5. A method according to claim 1, wherein the distance is equal to or substantially equal to the distance.
2. The air flow meter according to claim 1 . 6. The metal base is provided at two places on the metal base.
Mounting holes for fixing
Arrange so that the holes are aligned with the center of the molding resin.
The air according to any one of claims 1 to 5, wherein the air is provided.
Flow meter . 7. The heating resistor of the molding resin.
Also, make a step on the end face of the temperature compensation resistor mounting side.
The heating resistor and the heating resistor are provided on one of the steps.
One of the conductive support members of the
The mold resin is projected on the other step surface
A rib is attached together with the
7. The method according to claim 1, wherein one of the conductive support members protrudes.
An air flow meter according to any one of the preceding claims . 8. A heating resistor for temperature measurement of air flow, temperature compensation.
Resistor, heating resistor, temperature compensating resistor and electricity
Circuit board to be electrically connected, and a metal base on which the circuit board is mounted.
And a housing for a circuit coupled to the metal base.
In the air flow meter provided , one end of the housing is connected to the circuit board,
The other end has a connector element for connecting to external electrical components.
Metal terminal is provided.
An air flow meter characterized in that one end and the other end are subjected to different surface treatments . 9. A heating resistor for air flow measurement, temperature compensation.
Resistor, heating resistor, temperature compensating resistor and electricity
Circuit board to be electrically connected, and a metal base on which the circuit board is mounted.
And a housing for a circuit coupled to the metal base.
In the air flow meter provided , one end of the housing is connected to the circuit board,
The other end has a connector element for connecting to external electrical components.
Metal terminal is provided.
One end of the side connected to the circuit board is part of the surface
And is buried with mold resin.
The metal terminal is located at the bottom of the valley with respect to the resin surface.
The width W1 of the exposed surface and the metal terminal
W1 <W2, and the opposite of the housing is connected to the metal base.
On the side, a groove is provided around the entire circumference to connect with the cover.
Height of the housing side wall located inside the groove
An air flow meter characterized by a higher height . 10. A heating resistor and a temperature compensator for measuring an air flow rate.
The compensation resistor, the heating resistor and the temperature compensation resistor and the
Circuit board to be connected pneumatically, metal for mounting the circuit board
In an air flow meter having a base, the circuit board has a filter circuit for removing noise.
Provided on the ground terminal of the filter circuit and the metal base.
The grounding protrusion is one ground terminal and grounding protrusion
With two or more aluminum wire bonds per part
An air flow meter that is connected .