JP6775629B2 - Physical quantity detection element - Google Patents

Description

The present invention relates to a physical quantity detecting device for intake air of an internal combustion engine.

Currently, mass flow rate, pressure, and temperature measurements are generally used as physical quantity detectors inserted into the intake pipe, but control using absolute humidity (water content in the air) is used for internal combustion engine control. It is attracting attention, and many molded package electronic parts are adopted for the electronic circuit board in order to integrally configure an air flow rate sensor, a humidity sensor, and a pressure sensor as a physical quantity detecting device. Therefore, a mounting structure having excellent durability is required to prevent disconnection from stress due to vibration or thermal shock at the electrical joint between the electronic component and the circuit board.

Patent Document 1 discloses a structure in which the electrical connection portion between the ponding wire and the electrode terminal is sealed with the first sealant, and the first sealant is sealed with the second sealant.

Patent Document 2 discloses a structure in which an adhesive portion and an electrical joint portion between a semiconductor sensor element and a laminated substrate are protected by a resin protective film (or epoxy resin or fluororesin), and the sealing portion is exposed on a passage.

Japanese Unexamined Patent Publication No. 2004-028631 Japanese Unexamined Patent Publication No. 2001-012987

At present, automobiles using an electronically controlled fuel injection system are becoming common, and many sensors are used for the purpose of further improvement such as low emission, low fuel consumption, and torque improvement. In addition, the demand for improving the accuracy of the characteristics of the sensor itself is increasing, and the demand for price reduction is becoming stricter year by year.

Of the many sensors, the sensor that detects the physical quantity of the intake air needs to be exposed to the intake air in order to detect the physical quantity of the intake air. On the other hand, electronic components such as microcomputers, transistors, capacitors, and resistors mounted on circuit boards must be protected from corrosive gases, water, oil, and the like. In addition, it must be protected from disconnection due to stress applied to the electrical joint due to vibration or thermal shock.

Further, the power consumption is increasing with the increase of the number of electronic components mounted on the circuit board, and the heat generation of the entire circuit is increased by converting the power consumption into heat. Therefore, a heat dissipation design that suppresses the self-heating of the circuit as much as possible is required.

An object of the present invention is to provide a physical quantity detecting device capable of improving the corrosion resistance and mechanical strength of an electrical joint on a circuit board and improving heat dissipation performance.

In order to solve the above problems, the physical quantity detection device of the present invention includes a passage that takes in a part of the gas to be measured from the intake air passage and an electronic circuit board that processes an output signal from a sensing element that measures the physical quantity. In a physical quantity detection device having a housing for separating the passage and the circuit chamber for accommodating the electronic circuit board, the electronic circuit board and the entire circuit chamber are sealed with a resin sealant. The circuit chamber sealed with the resin sealant is exposed to the intake air passage .

According to the present invention, it is possible to provide a physical quantity detecting device capable of improving the corrosion resistance and mechanical strength of the electrical joint portion on the circuit board and improving the heat dissipation performance.

The system diagram which shows an Example which used the physical quantity detection apparatus which concerns on this invention in an internal combustion engine control system. An example of a front view of a physical quantity detection device. An example of a front view of a physical quantity detection device. An example of a front view of a physical quantity detection device. The rear view of the physical quantity detection device. Left side view of the physical quantity detector. Right side view of the physical quantity detector. Top view of the physical quantity detector. The front view which shows the state which the front cover and the resin sealing material were removed from the physical quantity detection device. The rear view which shows the state which removed the back cover from a physical quantity detection device. FIG. 3-1 is a cross-sectional view taken along the line AA. Inclined view showing the state where the front cover is removed from the physical quantity detector The figure explaining the structure of the front cover. The figure explaining the structure of the back cover. Front view of the circuit board. Rear view of the circuit board. Enlarged view of the sensor room FIG. 7 (a) is a cross-sectional view taken along the line E1-E1.

The embodiment for carrying out the invention (hereinafter, Examples) described below solves various problems requested as an actual product, and particularly as a detection device for detecting a physical quantity of intake air of a vehicle. It solves various problems that are desirable for use and has various effects. One of the various problems solved by the following examples is the content described in the column of the problems to be solved by the above-mentioned invention, and one of the various effects exerted by the following examples is. It is the effect described in the column of effect of the invention. The various problems solved by the following examples and the various effects produced by the following examples will be described in the description of the following examples. Therefore, the problems and effects described in the following examples are also described in the contents other than the contents of the problem column to be solved by the invention and the effect column of the invention.

In the following examples, the same reference numerals show the same configuration even if the drawing numbers are different, and have the same effect. For the configurations already described, only reference numerals may be added to the drawings and the description may be omitted.

1. 1. An Example Using the Physical Quantity Detection Device According to the Present Invention for an Internal Combustion Engine Control System FIG. 1 shows an embodiment using a physical quantity detection device according to the present invention for an electronic fuel injection type internal combustion engine control system. It is a figure. Based on the operation of the internal combustion engine 110 including the engine cylinder 112 and the engine piston 114, the intake air is sucked from the air cleaner 122 as the gas to be measured 30 and is passed through the main passage 124, for example, the intake body, the throttle body 126, and the intake manifold 128. It is guided to the combustion chamber of the engine cylinder 112. The physical amount of the gas to be measured 30 which is the intake air guided to the combustion chamber is detected by the physical amount detection device 300 according to the present invention, fuel is supplied from the fuel injection valve 152 based on the detected physical amount, and the intake air 20 It is guided to the combustion chamber in the state of air-fuel mixture. In this embodiment, the fuel injection valve 152 is provided at the intake port of the internal combustion engine, and the fuel injected into the intake port forms an air-fuel mixture together with the measured gas 30 which is the intake air, and the fuel is formed through the intake valve 116. It is guided to the combustion chamber and burns to generate mechanical energy.

The fuel and air guided to the combustion chamber are in a mixed state of fuel and air, and are explosively burned by spark ignition of the spark plug 154 to generate mechanical energy. The gas after combustion is guided from the exhaust valve 118 to the exhaust pipe, and is discharged to the outside of the vehicle from the exhaust pipe as exhaust gas 24. The flow rate of the gas to be measured 30, which is the intake air guided to the combustion chamber, is controlled by the throttle valve 132 whose opening degree changes based on the operation of the accelerator pedal. The fuel supply amount is controlled based on the flow rate of the intake air guided to the combustion chamber, and the driver controls the opening degree of the throttle valve 132 to control the flow rate of the intake air guided to the combustion chamber. The mechanical energy generated by the engine can be controlled.

1.1 Outline of control of internal internal engine control system Physical quantities such as flow rate, temperature, humidity, and pressure of the gas to be measured 30, which is intake air taken from the air cleaner 122 and flow through the main passage 124, are detected by the physical quantity detection device 300, and the physical quantities are detected. An electric signal representing the physical quantity of the intake air is input from the detection device 300 to the control device 200. Further, the output of the throttle angle sensor 144 that measures the opening degree of the throttle valve 132 is input to the control device 200, and the positions and states of the engine piston 114, the intake valve 116, and the exhaust valve 118 of the internal combustion engine, and the rotation of the internal combustion engine. In order to measure the speed, the output of the rotation angle sensor 146 is input to the control device 200. The output of the oxygen sensor 148 is input to the control device 200 in order to measure the state of the mixing ratio of the fuel amount and the air amount from the state of the exhaust gas 24.

The control device 200 calculates the fuel injection amount and the ignition timing based on the physical quantity of the intake air which is the output of the physical quantity detection device 300 and the rotation speed of the internal combustion engine measured based on the output of the rotation angle sensor 146. Based on these calculation results, the amount of fuel supplied from the fuel injection valve 152 and the ignition timing ignited by the spark plug 154 are controlled. The fuel supply amount and ignition timing are actually based on the state of change in temperature and throttle angle detected by the physical quantity detection device 300, the state of change in engine speed, and the state of air-fuel ratio measured by the oxygen sensor 148. It is finely controlled. Further, the control device 200 controls the amount of air bypassing the throttle valve 132 by the idle air control valve 156 in the idle operation state of the internal combustion engine, and controls the rotation speed of the internal combustion engine in the idle operation state.

1.2 Importance of improving the detection accuracy of the physical quantity detection device and the installation environment of the physical quantity detection device The fuel supply amount and ignition timing, which are the main control amounts of the internal combustion engine, are calculated using the output of the physical quantity detection device 300 as the main parameter. To. Therefore, it is important to improve the detection accuracy of the physical quantity detecting device 300, suppress the change with time, and improve the reliability in order to improve the control accuracy and the reliability of the vehicle.

Particularly in recent years, there has been a very high demand for fuel efficiency of vehicles, and a very high demand for exhaust gas purification. In order to meet these demands, it is extremely important to improve the detection accuracy of the physical quantity of the intake air 20 detected by the physical quantity detecting device 300. It is also important that the physical quantity detecting device 300 maintains high reliability.

The vehicle equipped with the physical quantity detecting device 300 is used in an environment where changes in temperature and humidity are large. It is desirable that the physical quantity detecting device 300 also considers the response to changes in temperature and humidity in the usage environment and the response to dust and pollutants.

Further, the physical quantity detecting device 300 is attached to an intake pipe affected by heat generated from the internal combustion engine. Therefore, the heat generated by the internal combustion engine is transmitted to the physical quantity detecting device 300 via the intake pipe which is the main passage 124. Since the physical quantity detecting device 300 detects the flow rate of the gas to be measured by transferring heat to the gas to be measured, it is important to suppress the influence of heat from the outside as much as possible.

As described below, the physical quantity detecting device 300 mounted on the vehicle simply solves the problem described in the problem column to be solved by the invention and exerts the effect described in the effect column of the invention. Instead, as explained below, the various problems described above are fully considered, the various problems required for the product are solved, and various effects are achieved. Specific problems to be solved by the physical quantity detection device 300 and specific effects to be achieved will be described in the description of the following examples.

2. Configuration of Physical Quantity Detection Device 300 2.1 Appearance Structure of Physical Quantity Detection Device 300 FIGS. 2-1 (a) to 2-5 are views showing the appearance of the physical quantity detection device 300, and FIGS. 2-1 (a) to 2-5. 2-1 (c) is an example of a front view of the physical quantity detection device 300, FIG. 2-2 is a rear view, FIG. 2-3 is a left side view, FIG. 2-4 is a right side view, and FIG. 2-5 is a plan view. It is a figure.

The physical quantity detecting device 300 includes a housing 302, a front cover 303, and a back cover 304. The housing 302 is formed by molding a synthetic resin material, and has a flange 311 for fixing the physical quantity detection device 300 to the intake body which is the main passage 124, and electricity with an external device protruding from the flange 311. It has an external connection unit 321 having a connector for making a specific connection, and a measurement unit 331 extending from the flange 311 toward the center of the main passage 124.

The measurement unit 331 is integrally provided with the circuit board 400 by insert molding when the housing 302 is molded (see FIGS. 3-1 and 3-2). The circuit board 400 is provided with at least one detection unit for detecting the physical quantity of the gas to be measured 30 flowing through the main passage 124, and a circuit unit for processing the signal detected by the detection unit. The detection unit is arranged at a position exposed to the gas to be measured 30, and the circuit unit is arranged in a circuit chamber sealed by the front cover 303.

Sub-passage grooves are provided on the front surface and the back surface of the measuring unit 331, and the first sub-passage 305 is formed in cooperation with the front cover 303 and the back cover 304. At the tip of the measuring unit 331, a first sub-passage inlet 305a for taking a part of the gas to be measured 30 such as intake air into the first sub-passage 305 and a gas 30 to be measured from the first sub-passage 305 are mainly used. A first sub-passage exit 305b for returning to the passage 124 is provided. A part of the circuit board 400 protrudes in the middle of the first sub-passage 305, and a flow rate detection unit 602 (see FIG. 3-1), which is a detection unit, is arranged in the protruding portion to be measured. The flow rate of the gas 30 is detected.

A second sub-passage 306 for taking a part of the gas to be measured 30 such as intake air into the sensor chamber Rs is provided in the middle portion of the measuring unit 331 closer to the flange 311 than the first sub-passage 305. The second sub-passage 306 is formed in cooperation with the measuring unit 331 and the back cover 304. The second sub-passage 306 has a second sub-passage inlet 306a that opens into the upstream outer wall 336 to take in the gas to be measured 30, and a downstream side to return the gas 30 to be measured from the second sub-passage 306 to the main passage 124. It has a second sub-passage outlet 306b that opens into the outer wall 338. The second sub-passage 306 communicates with the sensor chamber Rs formed on the back side of the measuring unit 331. In the sensor chamber Rs, a pressure sensor and a humidity sensor, which are detection units provided on the back surface of the circuit board 400, are arranged.

2.2 Effect based on the external structure of the physical quantity detection device 300 The physical quantity detection device 300 is provided with a second sub-passage entrance 306a in the middle of the measurement section 331 extending from the flange 311 toward the center of the main passage 124 for measurement. A first sub-passage entrance 305a is provided at the tip of the portion 331. Therefore, the gas in the portion near the central portion away from the inner wall surface, not near the inner wall surface of the main passage 124, can be taken into the first sub-passage 305 and the second sub-passage 306, respectively. Therefore, the physical quantity detecting device 300 can measure the physical quantity of the gas in the portion away from the inner wall surface of the main passage 124, and can reduce the measurement error of the physical quantity related to heat and the decrease in the flow velocity in the vicinity of the inner wall surface. In the vicinity of the inner wall surface of the main passage 124, the temperature of the main passage 124 is easily affected, and the temperature of the gas to be measured 30 differs from the original temperature of the gas, and the average of the main gas in the main passage 124 is average. It will be different from the state. In particular, when the main passage 124 is the intake body of the engine, it is often maintained at a high temperature due to the influence of heat from the engine. Therefore, the gas near the inner wall surface of the main passage 124 is often higher than the original temperature of the main passage 124, which causes a decrease in measurement accuracy.

The measuring unit 331 has a shape extending long along an axis from the outer wall of the main passage 124 toward the center, but the thickness width has a narrow shape as shown in FIGS. 2-3 and 2-4. It is made up. That is, the measurement unit 331 of the physical quantity detection device 300 has a thin side surface and a substantially rectangular front surface. As a result, the physical quantity detecting device 300 can be provided with the first sub-passage 305 having a sufficient length, and the fluid resistance to the gas to be measured 30 can be suppressed to a small value. Therefore, the physical quantity detecting device 300 can suppress the fluid resistance to a small value and measure the flow rate of the gas to be measured 30 with high accuracy.

2.3 Structure of temperature detection unit 451 The temperature detection unit 451 constitutes one of the detection units for detecting the physical quantity of the gas to be measured 30 flowing through the main passage 124, and is provided on the circuit board 400. There is. The circuit board 400 has a protrusion 450 that protrudes from the second sub-passage inlet 306a of the second sub-passage 306 toward the upstream of the gas to be measured 30, and the temperature detection unit 451 is a protrusion 450 and is a circuit. It has a chip-type temperature sensor 453 provided on the back surface of the substrate 400. The temperature sensor 453 and its wiring portion are coated with a synthetic resin material to prevent salt water from adhering to the temperature sensor 453 and causing electrolytic corrosion.

For example, as shown in FIG. 3-2, in the central portion of the measuring unit 331 provided with the second sub-passage entrance 306a, the upstream outer wall in the measuring unit 331 constituting the housing 302 is recessed toward the downstream side. The protruding portion 450 of the circuit board 400 projects toward the upstream side from the recessed upstream outer wall. The tip of the protrusion 450 is arranged at a position recessed from the most upstream surface of the upstream outer wall. The temperature detection unit 451 is provided on the protrusion 450 so as to face the back surface of the circuit board 400, that is, the second sub-passage 306 side.

Since the second sub-passage inlet 306a is formed on the downstream side of the temperature detection unit 451, the gas to be measured 30 flowing from the second sub-passage inlet 306a into the second sub-passage 306 comes into contact with the temperature detection unit 451. The temperature is detected when the gas flows into the second sub-passage inlet 306a and comes into contact with the temperature detection unit 451. The gas to be measured 30 in contact with the temperature detection unit 451 flows directly from the second sub-passage inlet 306a into the second sub-passage 306, passes through the second sub-passage 306, and is discharged from the second sub-passage outlet 306b to the main passage 123. Will be done.

2.4 Effect related to temperature detection unit 451 The temperature of the gas flowing into the second sub-passage inlet 306a from the upstream side in the direction along the flow of the gas to be measured 30 is measured by the temperature detection unit 451, and the gas is further projected. By flowing toward the base end portion of the portion 450, the temperature of the base end portion of the protrusion 450 is cooled in a direction approaching the temperature of the gas to be measured 30. The temperature of the intake pipe, which is the main passage 124, usually rises, and heat is transferred from the flange 311 or the contact portion 343 to the base end portion of the protrusion 450 through the upstream outer wall in the measurement unit 331 or the circuit board 400. It may affect the temperature measurement accuracy by the temperature detection unit 451. As described above, after the gas 30 to be measured is measured by the temperature detection unit 451 and then flows along the base end portion of the protrusion 450, the base end portion is cooled. Therefore, it is possible to suppress heat transfer from the flange 311 or the contact portion 343 to the base end portion of the protrusion 450 through the upstream outer wall in the measurement unit 310 or the circuit board 400.

In particular, at the base end portion of the protrusion 450, the outer wall on the upstream side in the measuring unit 331 has a shape of being recessed toward the downstream side (see FIGS. 3-1 and 3-2), and therefore, from the flange 311. The length of the outer wall on the upstream side to the base end portion of the protrusion 450 can be increased, the heat conduction distance becomes longer, and the distance of the cooling portion due to the gas to be measured 30 becomes longer. Therefore, the influence of heat generated from the flange 311 or the contact portion 343 can be reduced.

2.5 Structure and effect of flange 311 The flange 311 is provided with a plurality of recesses 313 on the lower surface 312 facing the main passage 124 to reduce the heat transfer surface between the flange 311 and detect the physical quantity. The device 300 is less susceptible to heat. In the physical quantity detecting device 300, the measuring unit 331 is inserted into the inside through the mounting hole provided in the main passage 124, and the lower surface 312 of the flange 311 faces the main passage 124. The main passage 124 is, for example, an intake body, and the main passage 124 is often maintained at a high temperature. On the contrary, it is considered that the main passage 124 has an extremely low temperature at the time of starting in a cold region. If such a high temperature or low temperature state of the main passage 124 affects the temperature detection unit 451 and the flow rate measurement described later, the measurement accuracy is lowered. The flange 311 has a recess 313 in the lower surface 312, and a space is formed between the lower surface 312 facing the main passage 124 and the main passage 124. Therefore, it is possible to reduce heat transfer from the main passage 124 to the physical quantity detecting device 300 and prevent a decrease in measurement accuracy due to heat.

The screw holes 314 of the flange 311 are for fixing the physical quantity detecting device 300 to the main passage 124, and each of the screw holes 314 is so that the surface facing the main passage 124 around the screw holes 314 is kept away from the main passage 124. A space is formed between the surface of the screw hole 314 facing the main passage 124 and the main passage 124. By doing so, the structure is such that heat transfer from the main passage 124 to the physical quantity detecting device 300 can be reduced, and deterioration of measurement accuracy due to heat can be prevented.

2.6 Structure of External Connection Unit 321 The external connection unit 321 has a connector 322 provided on the upper surface of the flange 311 and protruding from the flange 311 toward the downstream side in the flow direction of the gas to be measured 30. The connector 322 is provided with an insertion hole 322a for inserting a communication cable connecting to and from the control device 200. As shown in FIG. 2-4, four external terminals 323 are provided inside the insertion hole 322a. The external terminal 323 serves as a terminal for outputting physical quantity information which is a measurement result of the physical quantity detection device 300 and a power supply terminal for supplying DC power for operating the physical quantity detection device 300.

The connector 322 has a shape that protrudes from the flange 311 toward the downstream side in the flow direction of the gas to be measured 30 and is inserted from the downstream side in the flow direction toward the upstream side, but the shape is not limited to this. For example, it may have a shape that protrudes vertically from the upper surface of the flange 311 and is inserted along the extending direction of the measuring unit 331, and various changes can be made.

2.7 Effects related to the resin encapsulant 353 The resin encapsulant 353 is provided so as to cover the entire surface of the circuit board 400, and all electronic components such as the LSI 414 and the microcomputer 415 and the aluminum wire 435 and the like are provided. Since it covers all the electrical joints of the above, it prevents corrosive gas, salt water, oil, etc. from adhering and causing electrolytic corrosion. Further, since the aluminum wire 435 is fixed by being covered with the resin encapsulant 353, it is possible to prevent disconnection due to vibration or the like. Further, since the hollow portion between the circuit board 400 and the front cover 303 is filled with the resin sealing material 353, the mechanical strength of the circuit chamber portion in the overall structure of the housing 302 is improved.

When the circuit board 400 is made of a material made of glass epoxy resin, it is not adhered to the thermoplastic resin forming the housing 302 and is measured from the first sub-passage 305 and the second sub-passage 306. Although the gas 30 leaks in, the resin encapsulant 353 has a high sealing property between the circuit board 400 and the housing 302, and the airtightness in the circuit chamber can be ensured. Therefore, the front cover 303 on the flange 311 side of the partition wall 335 can be removed, and is a part of the front cover 303 as shown in FIGS. 2-1 (b) and 2-1 (c), for example. There may be an embodiment in which the resin sealant 353 having holes is exposed on the main passage 124, and various modifications can be made.

Electronic components such as the power regulator 416, microcomputer 415, and LSI 414 generate a large amount of heat, but the resin encapsulant 353 has a thermal conductivity several to several hundred times that of the thermal conductivity of air (0.0241). Therefore, the heat released from the electronic component to the gas to be measured 30 via the resin encapsulant 353 and the front cover 303 is increased, and the effect of reducing the temperature rise due to the circuit self-heating can be obtained. Further, by processing the surface state of the resin encapsulant 353, for example, a pin-shaped protrusion as shown in FIG. 3-4 may be arranged in a sword-shaped shape, and the surface area of the resin encapsulant 353 is increased. It is also possible to improve the heat dissipation effect.

3. 3. Overall structure of housing 302 and its effects Next, the overall structure of housing 302 will be described with reference to FIGS. 3-1 to 3-3. 3-1 to 3-3 are views showing a state of the housing 302 in which the front cover 303 and the back cover 304 are removed from the physical quantity detecting device 300, and FIG. 3-1 is a front view of the housing 302 and FIG. 3-. 2 is a rear view of the housing 302, and FIG. 3-3 is a sectional view taken along line AA of FIG. 3-1.

The housing 302 has a structure in which the measuring unit 331 extends from the flange 311 toward the center of the main passage 124. A circuit board 400 is insert-molded on the base end side of the measurement unit 331. The circuit board 400 is arranged parallel to the surface of the measuring unit 331 at an intermediate position between the front surface and the back surface of the measuring unit 331, and is integrally molded with the housing 302, and the base end side of the measuring unit 331 is thickened. It is divided into one side and the other side in the parallel direction.

A circuit chamber Rc for accommodating the circuit portion of the circuit board 400 is formed on the front surface side of the measurement unit 331, and a sensor chamber Rs for accommodating the pressure sensor 421 and the humidity sensor 422 is formed on the back surface side. The circuit chamber Rc is sealed and completely isolated from the outside by attaching the front cover 303 to the housing 302. On the other hand, by attaching the back cover 304 to the housing 302, the second sub-passage 306 and the sensor chamber Rs, which is an indoor space communicating with the outside of the measurement unit 331 via the second sub-passage 306, are formed. A part of the circuit board 400 protrudes into the first sub-passage 305 from the partition wall 335 that divides the circuit chamber Rc of the measurement unit 331 and the first sub-passage 305, and the protruding portion of the flow path surface for measurement The flow rate detection unit 602 is provided in the 430.

3.2 Structure of sub-passage groove A sub-passage groove for forming the first sub-passage 305 is provided on the tip side of the measuring unit 331 in the length direction. The sub-passage groove for forming the first sub-passage 305 has a front-side sub-passage groove 332 shown in FIG. 3-1 and a back-side sub-passage groove 334 shown in FIG. 3-2. As shown in FIG. 3-1 the front sub-passage groove 332 is a base of the measuring unit 331 as it moves from the first sub-passage outlet 305b opening to the downstream outer wall 338 of the measuring unit 331 toward the upstream outer wall 336. It is curved toward the flange 311 on the end side, and communicates with the opening 333 penetrating in the thickness direction at a position near the upstream outer wall 336. The opening 333 is formed along the flow direction of the gas to be measured 30 in the main passage 124 so as to extend between the upstream outer wall 336 and the downstream outer wall 338.

As shown in FIG. 3-2, the back side sub-passage groove 334 shifts from the upstream side outer wall 336 toward the downstream side outer wall 338, and is bifurcated at an intermediate position between the upstream side outer wall 336 and the downstream side outer wall 338. One extends in a straight line as a discharge passage and opens to the discharge port 305c of the downstream outer wall 338, and the other is the flange 311 side which is the base end side of the gradual measurement unit 331 as it shifts to the downstream outer wall 338. It is curved to and communicates with the opening 333 at a position near the downstream outer wall 338.

The back side sub-passage groove 334 forms an inlet groove into which the measured gas 30 flows in from the main passage 124, and the front side sub-passage groove 332 is an outlet for returning the measured gas 30 taken in from the back side sub-passage groove 334 to the main passage 124. Form a groove. Since the front side sub-passage groove 332 and the back side sub-passage groove 334 are provided at the tip of the housing 302, the gas in the portion away from the inner wall surface of the main passage 124, in other words, the portion near the central portion of the main passage 124. The flowing gas can be taken in as the gas to be measured 30. The gas flowing near the inner wall surface of the main passage 124 is affected by the wall surface temperature of the main passage 124 and often has a temperature different from the average temperature of the gas flowing through the main passage 124 such as the intake air 20. Further, the gas flowing near the inner wall surface of the main passage 124 often shows a flow velocity slower than the average flow velocity of the gas flowing through the main passage 124. Since the physical quantity detecting device 300 of the embodiment is less susceptible to such an influence, it is possible to suppress a decrease in measurement accuracy.

As shown in FIG. 3-2, a part of the gas to be measured 30 flowing through the main passage 124 is taken into the back side sub passage groove 334 from the first sub passage inlet 305a and flows in the back side sub passage groove 334. Then, the foreign matter having a large mass contained in the gas to be measured 30 flows into the discharge passage extending in a straight line from the branch together with a part of the gas to be measured, and flows from the discharge port 305c of the downstream outer wall 338 to the main passage 124. It is discharged.

The back side sub-passage groove 334 has a shape that becomes deeper as it progresses, and the gas to be measured 30 gradually moves to the front side of the measurement unit 331 as it flows along the back side sub-passage groove 334. In particular, the back side sub-passage groove 334 is provided with a steeply inclined portion 334a that suddenly deepens in front of the opening 333, and a part of air having a small mass moves along the steeply inclined portion 334a and is inside the opening 333. It flows on the measurement flow path surface 430 side of the circuit board 400. On the other hand, a foreign substance having a large mass flows on the back surface 431 side of the flow path surface for measurement because it is difficult to change the course suddenly.

As shown in FIG. 3-1 the gas to be measured 30 that has moved to the front side through the opening 333 flows along the measurement flow path surface 430 of the circuit board, and flows with the flow rate detection unit 602 provided on the measurement flow path surface 430. Heat transfer is performed between the two, and the flow rate is measured. The air that has flowed from the opening 333 to the front sub-passage groove 332 also flows along the front sub-passage groove 332, and is discharged to the main passage 124 from the first sub-passage outlet 305b that opens to the downstream outer wall 338.

Since a substance with a large mass such as dust mixed in the gas to be measured 30 has a large inertial force, the depth of the groove sharply deepens along the surface of the steeply inclined portion 334a in the deep direction of the groove. Is difficult to change. Therefore, the foreign matter having a large mass can move toward the back surface 431 of the flow path surface for measurement, and can prevent the foreign matter from passing near the flow rate detection unit 602. In this embodiment, most of the foreign substances having a large mass other than gas pass through the back surface 431 of the measurement flow path surface, which is the back surface of the measurement flow path surface 430, and thus are caused by foreign substances such as oil, carbon, and dust. The influence of dirt can be reduced, and the decrease in measurement accuracy can be suppressed. That is, since it has a shape that suddenly changes the course of the gas to be measured 30 along the axis that crosses the axis of the flow of the main passage 124, the influence of foreign matter mixed in the gas to be measured 30 can be reduced.

3.3 Structure and effect of the second sub-passage and the sensor chamber The second sub-passage 306 has the second sub-passage inlet 306a and the second sub-passage exit in parallel with the flange 311 so as to follow the flow direction of the gas to be measured 30. It is formed in a straight line with 306b. The second sub-passage inlet 306a is formed by cutting out a part of the upstream side outer wall 336, and the second sub-passage outlet 306b is formed by cutting out a part of the downstream side outer wall 338. Specifically, it is formed by cutting out a part of the upstream side outer wall 336 and a part of the downstream side outer wall 338 from the back surface side of the measuring unit 331 at a position continuously along the upper surface of the partition wall 335. The second sub-passage inlet 306a and the second sub-passage outlet 306b are cut out to a depth position where they are flush with the back surface of the circuit board 400. Since the gas to be measured 30 passes along the back surface of the substrate body 401 of the circuit board 400, the second sub-passage 306 functions as a cooling channel for cooling the substrate body 401. Many of the circuit boards 400 have heat such as LSIs and microcomputers, and these heats can be transferred to the back surface of the substrate main body 401 and dissipated by the gas to be measured 30 passing through the second sub-passage 306.

The sensor chamber Rs is provided on the base end side of the measuring unit 331 with respect to the second sub-passage 306. A part of the gas to be measured 30 that has flowed from the second sub-passage inlet 306a into the second sub-passage 306 flows into the sensor chamber Rs, and the pressure and relative humidity are measured by the pressure sensor 421 and the humidity sensor 422 in the sensor chamber Rs, respectively. Detected. Since the sensor chambers Rs are arranged closer to the proximal end side of the measuring unit 331 than the second sub-passage 306, the influence of the dynamic pressure of the gas to be measured 30 passing through the second sub-passage 306 can be reduced. Therefore, the detection accuracy of the pressure sensor 421 in the sensor chamber Rs can be improved.

Since the sensor chamber Rs is arranged closer to the base end side of the measuring unit 331 than the second sub-passage 306, for example, when the tip side of the measuring unit 331 is attached to the intake passage in a downward posture. It is possible to prevent the pollutants and water droplets that have flowed into the second sub-passage 306 together with the gas to be measured 30 from adhering to the pressure sensor 421 and the humidity sensor 422 arranged downstream thereof.

In particular, in this embodiment, in the sensor chamber Rs, the pressure sensor 421 having a relatively large outer shape is arranged on the upstream side, and the humidity sensor 422 having a relatively small outer shape is arranged on the downstream side of the pressure sensor 421. The pollutants and water droplets that have flowed in together with the gas to be measured 30 adhere to the pressure sensor 421, and the adhesion to the humidity sensor 422 is suppressed. Therefore, the humidity sensor 422, which has low resistance to contaminants and water droplets, can be protected.

The pressure sensor 421 and the humidity sensor 422 are less affected by the flow of the gas to be measured 30 than the flow rate detection unit 602. In particular, the humidity sensor 422 only needs to secure the diffusion level of water in the gas to be measured 30. It can be provided in the sensor chamber Rs adjacent to the linear second sub-passage 306. On the other hand, the flow rate detection unit 602 requires a flow velocity of a certain level or higher, needs to keep dust and dirt away, and needs to consider the influence on pulsation. Therefore, the flow rate detection unit 602 is provided in the first sub-passage 305 having a shape that goes around in a loop shape.

In this embodiment, instead of cutting out the upstream outer wall 336 and the downstream outer wall 338, through holes are provided in the upstream outer wall 336 and the downstream outer wall 338 to provide the second sub-passage inlet 306a and the second sub-passage outlet 306b. Is forming. Like the second sub-passage shown in FIGS. 3 to 3 to 3 above, the upstream side outer wall 336 and the downstream side outer wall 338 are cut out to form the second sub-passage entrance 306a and the second sub-passage exit 306b, respectively. Then, since the width of the upstream outer wall 336 and the width of the downstream outer wall 338 are locally narrowed at such a position, the measuring unit 331 is omitted from the notch as a starting point due to heat sinking during molding or the like. It may be distorted in a character shape. According to this embodiment, since the through hole is provided instead of the notch, it is possible to prevent the measuring unit 331 from being bent in an abbreviated shape. Therefore, it is possible to prevent the housing 302 from being distorted and changing the position and orientation of the detection unit with respect to the gas to be measured 30 to affect the detection accuracy, and it is possible to ensure a constant detection accuracy without individual differences.

FIG. 7 is a diagram showing another form of the second sub-passage.

The back cover 304 may be provided with a partition wall for partitioning between the second sub-passage 306 and the sensor chamber Rs. According to such a configuration, the gas to be measured 30 can be indirectly flowed into the sensor chamber Rs from the second sub-passage 306, the influence of the dynamic pressure on the pressure sensor is reduced, and the pollutants and water droplets on the humidity sensor are reduced. Adhesion can be suppressed.

In the example shown in FIG. 7, two pressure sensors 421A and 421B are provided side by side in a row along the second sub-passage 306 in the sensor chamber Rs, and one humidity sensor 422 is provided downstream thereof. The partition walls 352A and 352B are provided on the back cover 304, and are arranged so as to extend between the second sub-passage 306 and the sensor chamber Rs by attaching the back cover 304 to the housing 302. Specifically, a partition wall 352A is arranged between the pressure sensor on the upstream side and the upstream wall of the sensor chamber Rs, and along the humidity sensor between the pressure sensor on the downstream side and the downstream wall of the sensor chamber Rs. The partition wall 352B is arranged.

3.4 Shapes and Effects of Front Cover 303 and Back Cover 304 FIG. 4 is a view showing the appearance of the front cover 303, FIG. 4 (a) is a front view, and FIG. 4 (b) is a view of FIG. 4 (a). BB line sectional view. 5A and 5B are views showing the appearance of the back cover 304, FIG. 5A is a front view, and FIG. 5B is a sectional view taken along line BB of FIG. 5A.

In FIGS. 4 and 5, the front cover 303 and the back cover 304 form a first sub-passage 305 by closing the front sub-passage groove 332 and the back-side sub-passage 334 of the housing 302. Further, the front cover 303 forms a sealed circuit chamber Rc, and the back cover 304 closes the concave portion on the back surface side of the measuring unit 331 and communicates with the second sub-passage 306 and the second sub-passage 306. make.

The front cover 303 is provided with a protrusion 356 at a position facing the flow rate detection unit 602, and is used to form a throttle between the front cover 303 and the measurement flow path surface 430. Therefore, it is desirable that the molding accuracy is high. Since the front cover 303 and the back cover 304 are made by a resin molding process of injecting a thermoplastic resin into a mold, they can be made with high molding accuracy.

The front cover 303 and the back cover 304 are provided with a plurality of fixing holes 351 into which a plurality of fixing pins 350 protruding from the measuring unit 331 are inserted. The front cover 303 and the back cover 304 are attached to the front surface and the back surface of the measuring unit 331, respectively, and at that time, the fixing pin 350 is inserted into the fixing hole 351 to perform positioning. Then, they are joined by laser welding or the like along the edges of the front side sub-passage groove 332 and the back side sub-passage groove 334, and similarly, they are joined by laser welding or the like along the edges of the circuit chamber Rc and the sensor chamber Rs.

3.5 Fixing structure and effect of the circuit board 400 by the housing 302 Next, fixing of the circuit board 400 to the housing 302 by the resin molding process will be described. The flow rate detection unit 602 of the circuit board 400 is provided at a predetermined location of the sub-passage groove for forming the sub-passage, for example, in the present embodiment, at the opening 333 which is a connecting portion between the front side sub-passage groove 332 and the back side sub-passage groove 334. The circuit board 400 is integrally molded with the housing 302 so as to be arranged.

The measurement unit 331 of the housing 302 is provided with portions 372 and 373 for fixing the outer peripheral edge portion of the base portion 402 of the circuit board 400 by embedding it in the housing 302 with a resin mold. The fixing portions 372 and 373 sandwich and fix the outer peripheral edge portion of the base portion 402 of the circuit board 400 from the front side and the back side.

The housing 302 is manufactured in the resin molding process. In this resin molding process, the circuit board 400 is built in the resin of the housing 302 and fixed in the housing 302 by the resin mold. By doing so, the shape of the sub-passage for the flow rate detection unit 602 to transfer heat to the gas to be measured 30 and measure the flow rate, for example, the shape of the front side sub-passage groove 332 and the back side sub-passage groove 334. It is possible to maintain the positional relationship and the directional relationship, which are relationships, with extremely high accuracy, and it is possible to suppress errors and variations that occur for each circuit board 400 to extremely small values. As a result, the measurement accuracy of the circuit board 400 can be greatly improved. For example, the measurement accuracy can be dramatically improved as compared with the conventional method of fixing using an adhesive.

The physical quantity detecting device 300 is often produced by mass production, and there is a limit in improving the measurement accuracy in the method of adhering with an adhesive while strictly measuring the physical quantity. However, by molding the sub-passage in the resin molding step of forming the sub-passage through which the gas to be measured 30 flows as in this embodiment and fixing the circuit board 400 at the same time, the variation in measurement accuracy can be significantly reduced. It is possible to significantly improve the measurement accuracy of the physical quantity detecting device 300.

For example, further explaining with reference to the embodiment shown in FIGS. 3-1 to 3-3, the relationship between the front side sub-passage groove 332, the back side sub-passage groove 334, and the flow rate detection unit 602 is high so as to have a specified relationship. The circuit board 400 can be fixed to the housing 302 with accuracy. As a result, in the physical quantity detection device 300 mass-produced, the relationship such as the positional relationship and the shape between the flow rate detection unit 602 and the first sub-passage 305 of each circuit board 400 can be constantly obtained with extremely high accuracy. Is possible.

In the first sub-passage 305 in which the flow rate detection unit 602 of the circuit board 400 is fixedly arranged, for example, the front side sub-passage groove 332 and the back side sub-passage groove 334 can be formed with extremely high accuracy. The work of forming the first sub-passage 305 from 334 is the work of covering both sides of the housing 302 with the front cover 303 and the back cover 304. This work is very simple, and there are few factors that reduce the measurement accuracy. Further, the front cover 303 and the back cover 304 are produced by a process in a resin molding having high molding accuracy. Therefore, it is possible to complete the sub-passage provided in the specified relationship with the flow rate detection unit 602 of the circuit board 400 with high accuracy. By such a method, high productivity can be obtained in addition to improvement of measurement accuracy.

On the other hand, conventionally, a thermal flowmeter has been produced by manufacturing a sub-passage and then adhering a measuring unit to the sub-passage with an adhesive. In the method of using the adhesive in this way, the thickness of the adhesive varies widely, and the bonding position and the bonding angle vary from product to product. Therefore, there is a limit to improving the measurement accuracy. Further, when these operations are performed in the mass production process, it becomes very difficult to improve the measurement accuracy.

In the embodiment according to the present invention, the circuit board 400 is fixed by the resin mold, and at the same time, the sub-passage groove for molding the first sub-passage 305 is formed by the resin mold. By doing so, the flow rate detection unit 602 can be fixed to the shape of the sub-passage groove and the sub-passage groove with extremely high accuracy.

A portion related to flow rate measurement, for example, a measurement flow path surface 430 to which a flow rate detection unit 602 and a flow rate detection unit 602 are attached is provided on the surface of the circuit board 400. The flow rate detection unit 602 and the measurement flow path surface 430 are exposed from the resin forming the housing 302. That is, the flow rate detection unit 602 and the measurement flow path surface 430 are not covered with the resin that forms the housing 302. The flow rate detection unit 602 and the measurement flow path surface 430 of the circuit board 400 are used as they are even after the resin molding of the housing 302, and are used for the flow rate measurement of the physical quantity detection device 300. By doing so, the measurement accuracy is improved.

In the embodiment according to the present invention, since the circuit board 400 is integrally molded with the housing 302 to fix the circuit board 400 to the housing 302 having the first sub-passage 305, the circuit board 400 is surely attached to the housing 302. Can be fixed. In particular, since the protruding portion 403 of the circuit board 400 penetrates the partition wall 335 and protrudes into the first sub-passage 305, the sealing property between the first sub-passage 305 and the circuit chamber Rc is high. It is possible to prevent the gas to be measured 30 from leaking from the first sub-passage 305 into the circuit chamber Rc, and to prevent the circuit parts and wiring of the circuit board 400 from coming into contact with the gas to be measured 30 and corroding.

4. Appearance of circuit board 400 4.1 Molding of measurement flow path surface 430 including flow rate detection unit 602 FIGS. 6-1 to 6-2 show the appearance of the circuit board 400. The shaded portion described on the appearance of the circuit board 400 indicates a fixed surface 432 and a fixed surface 434 in which the circuit board 400 is covered and fixed by the resin when the housing 302 is molded in the resin molding step.

FIG. 6-1 is a front view of the circuit board and FIG. 6-2 is a rear view of the circuit board.

The circuit board 400 has a substrate body 401, a circuit unit and a flow rate detection unit 602 which is a sensing element are provided on the front surface of the substrate body 401, and a pressure sensor 421 which is a sensing element and humidity are provided on the back surface of the substrate body 401. A sensor 422 is provided. The substrate body 401 is made of a material made of glass epoxy resin, and has a value equal to or close to the thermal expansion coefficient of the thermoplastic resin forming the housing 302. Therefore, the stress due to the difference in the coefficient of thermal expansion can be reduced when the housing 302 is insert-molded, and the distortion of the circuit board 400 can be reduced.

The substrate body 401 has a flat plate shape having a constant thickness, and has a substantially quadrangular base portion 402 and a substantially quadrangular protruding portion 403 that protrudes from one side of the base portion 402 and is one size smaller than the base portion 402. It has a substantially T-shaped plan view. A circuit portion is provided on the surface of the base portion 402. The circuit unit is configured by mounting electronic components such as LSI 414, microcomputer 415, power supply regulator 416, and chip components 417 such as resistors and capacitors on circuit wiring (not shown). Since the power supply regulator 416 generates a large amount of heat as compared with other electronic components such as the microcomputer 415 and the LSI 414, the power supply regulator 416 is arranged relatively upstream in the circuit chamber Rc. The entire LSI 414 is sealed with a synthetic resin material 419 so as to include the gold wire 411, which improves the handleability of the circuit board 400 during insert molding.

A recess 402a into which the LSI 414 is fitted is recessed on the surface of the substrate body 401. The recess 402a can be formed by laser machining the substrate body 401. The substrate body 401 made of glass epoxy resin is easier to process than the substrate body made of ceramic, and the recess 402 can be easily provided. The recess 402 has a depth at which the surface of the LSI 414 is flush with the surface of the substrate body 401. By matching the heights of the surface of the LSI 414 and the surface of the substrate body 401 in this way, wire bonding for connecting the LSI 414 and the substrate body 401 with a gold wire 411 becomes easy, and the circuit board 400 can be easily manufactured. become. The LSI 414 can be provided directly on the surface of the substrate body 401, for example. In the case of such a structure, the synthetic resin material 419 that covers the LSI 414 protrudes more greatly, but the process of forming the recess 402 in the substrate main body 401 becomes unnecessary, and the manufacturing can be simplified.

The protrusion 403 is arranged in the first sub-passage 305 when the circuit board 400 is insert-molded into the housing 302, and the measurement flow path surface 430, which is the surface of the protrusion 403, is along the flow direction of the gas to be measured 30. Extend. A flow rate detection unit 602 is provided on the measurement flow path surface 430 of the protrusion 403. The flow rate detection unit 602 transfers heat with the gas to be measured 30, measures the state of the gas 30 to be measured, for example, the flow velocity of the gas 30 to be measured, and outputs an electric signal indicating the flow rate flowing through the main passage 124. In order for the flow rate detection unit 602 to measure the state of the gas to be measured 30 with high accuracy, it is desirable that the gas flowing in the vicinity of the measurement flow path surface 430 is a laminar flow and has little turbulence. Therefore, it is desirable that the surface of the flow rate detection unit 602 and the surface of the measurement flow path surface 430 are flush with each other, or the difference is equal to or less than a predetermined value.

A recess 403a is recessed on the surface of the measurement flow path surface 430, and the flow rate detection unit 602 is fitted therein. This recess 403a can also be formed by performing laser processing. The recess 403a has a depth at which the surface of the flow rate detection unit 602 is flush with the surface of the measurement flow path surface 430. The flow rate detection unit 602 and its wiring portion are covered with a synthetic resin material 418 to prevent electrolytic corrosion due to adhesion of salt water.

Two pressure sensors 421A and 421B and one humidity sensor 422 are provided on the back surface of the substrate main body 401. The two pressure sensors 421A and 421B are divided into an upstream side and a downstream side and arranged in a row. A humidity sensor 422 is arranged on the downstream side of the pressure sensor 421B. These two pressure sensors 421A and 421B and one humidity sensor 422 are arranged in the sensor chamber Rs. In the example shown in FIG. 6-2, the case where two pressure sensors 421A and 421B and one humidity sensor 422 are provided has been described, but only the pressure sensor 421B and the humidity sensor 422 may be provided, or only the humidity sensor 422 may be provided. May be good.

In the circuit board 400, the second sub-passage 306 is arranged on the back surface side of the substrate main body 401. Therefore, the entire substrate body 401 can be cooled by the gas to be measured 30 passing through the second sub-passage 306.

4.2 Structure of the temperature detection unit 451 The temperature detection unit 451 is provided at the upstream end side of the base portion 402 and at the corner portion on the protruding portion 403 side. The temperature detection unit 451 constitutes one of the detection units for detecting the physical quantity of the gas to be measured 30 flowing through the main passage 124, and is provided on the circuit board 400. The circuit board 400 has a protrusion 450 that protrudes from the second sub-passage inlet 306a of the second sub-passage 306 toward the upstream of the gas to be measured 30, and the temperature detection unit 451 is a protrusion 450 and is a circuit. It has a chip-type temperature sensor 453 provided on the back surface of the substrate 400. The temperature sensor 453 and its wiring portion are coated with a synthetic resin material to prevent electrolytic corrosion due to the adhesion of salt water.

For example, as shown in FIG. 3-2, in the central portion of the measuring unit 331 provided with the second sub-passage entrance 306a, the upstream outer wall 336 in the measuring unit 331 constituting the housing 302 is recessed toward the downstream side. The protruding portion 450 of the circuit board 400 protrudes toward the upstream side from the recessed upstream side outer wall 336. The tip of the protrusion 450 is arranged at a position recessed from the most upstream side surface of the upstream outer wall 336. The temperature detection unit 451 is provided on the protrusion 450 so as to face the back surface of the circuit board 400, that is, the second sub-passage 306 side.

Since the second sub-passage inlet 306a is formed on the downstream side of the temperature detection unit 451, the gas to be measured 30 flowing from the second sub-passage inlet 306a into the second sub-passage 306 comes into contact with the temperature detection unit 451. The temperature is detected when the gas flows into the second sub-passage inlet 306a and comes into contact with the temperature detection unit 451. The gas to be measured 30 in contact with the temperature detection unit 451 flows directly from the second sub-passage inlet 306a into the second sub-passage 306, passes through the second sub-passage 306, and is discharged from the second sub-passage outlet 306b to the main passage 123. Will be done.

4.3 Fixing the circuit board 400 by the resin molding process and its effect The shaded area in Fig. 6-1 is the thermoplastic used in the resin molding process to fix the circuit board 400 to the housing 302 in the resin molding process. A fixed surface 432 and a fixed surface 434 for covering the circuit board 400 with resin are shown. It is important that the relationship between the flow rate detection unit 602 provided on the measurement flow path surface 430 and the measurement flow path surface 430 and the shape of the sub-passage is maintained with high accuracy so as to be related to the regulation.

In the resin molding process, since the circuit board 400 is fixed to the housing 302 in which the sub-passage is formed and the sub-passage is formed at the same time, the relationship between the sub-passage and the measurement flow path surface 430 and the flow rate detection unit 602 can be established with extremely high accuracy. Can be maintained. That is, since the circuit board 400 is fixed to the housing 302 in the resin molding process, the circuit board 400 can be positioned and fixed with high accuracy in the mold for molding the housing 302 having the sub-passage. Become. By injecting a high-temperature thermoplastic resin into the mold, the sub-passage is formed with high accuracy and the circuit board 400 is fixed with high accuracy. Therefore, it is possible to suppress the error and variation generated for each circuit board 400 to a very small value. As a result, the measurement accuracy of the circuit board 400 can be greatly improved. In this embodiment, the outer periphery of the base portion 402 of the substrate main body 401 is covered with the fixing portions 372 and 373 of the mold resin for molding the housing 302 to form the fixing surfaces 432 and 434.

Although the embodiments of the present invention have been described in detail above, the present invention is not limited to the above-described embodiments, and various designs are designed without departing from the spirit of the present invention described in the claims. You can make changes. For example, the above-described embodiment has been described in detail in order to explain the present invention in an easy-to-understand manner, and is not necessarily limited to the one including all the described configurations. Further, it is possible to replace a part of the configuration of one embodiment with the configuration of another embodiment, and it is also possible to add the configuration of another embodiment to the configuration of one embodiment. Further, it is possible to add / delete / replace a part of the configuration of each embodiment with another configuration.

30 Measured gas 124 Main passage 300 Physical quantity detection device 302 Housing 303 Front cover 304 Back cover 305 First sub-passage 305a First sub-passage entrance 305b First sub-passage exit 306 Second sub-passage 306a Second sub-passage inlet 306b Second Sub-passage outlet 311 Flange 312 Facing the main passage 124 Lower surface 313 Recess 314 Screw hole 321 External connection 322 Connector 322a Insert hole 323 External terminal 332 Front side sub-passage groove 333 Opening 334 Back side Sub-passage groove 334 a Steep slope 336 Upstream side Outer wall 338 Downstream outer wall 350 Cover upstream side protrusion 351 Cover downstream side protrusion 353 Resin sealant 400 Circuit board 415 Electronic parts (microcomputer)
421A, 421B Pressure sensor 422 Humidity sensor 430 Measurement flow path surface 431 Measurement flow path surface back surface 435 Aluminum wire 436 Heat transfer surface exposed part 450 Projection part 451 Temperature detection part 453 Temperature sensor 602 Flow rate detection part

Claims (4)

A circuit chamber having a passage for taking in a part of the gas to be measured from the intake air passage and an electronic circuit board for processing an output signal from a sensing element for measuring a physical quantity, and accommodating the passage and the electronic circuit board. In a physical quantity detector in which a housing is formed of a thermoplastic resin so as to separate
The electronic circuit board is a glass epoxy resin, and is integrally molded with the housing by a fixing portion on the electronic circuit board.
And said entire electronic circuit board and the circuit chamber is sealed with a resin sealant, the feature that the resin sealing the circuit chamber is sealed by agent is exposed to the suction air passage Physical quantity detector. In the physical quantity detecting device according to claim 1,
The resin encapsulant covers all electrical joints between the wires and electronic components in the circuit chamber and the electronic circuit board. In the physical quantity detecting device according to claim 1,
The physical quantity detecting device is characterized in that the resin encapsulant is adhered to the housing member on the side surface of the circuit chamber and the electronic circuit board and the cover. In the physical quantity detecting device according to claim 1,
A physical quantity detecting device characterized in that pin-shaped protrusions are arranged in a sword-shaped shape on the surface of the resin sealant.

Images