JP6995020B2 - Physical quantity detector - Google Patents

Description

The present disclosure relates to a physical quantity detection device.

Conventionally, an invention relating to an air flow rate measuring device for measuring an air flow rate with a flow rate sensor has been known (see Patent Document 1 below). The air flow rate measuring device described in Patent Document 1 includes a sub-flow path, a flow rate sensor, and a circuit unit (see the same document, claim 1 and the like).

The secondary flow path takes in a part of the air flowing inside the duct. The sub-sub-channel takes in a part of the air flowing through the sub-channel. The flow rate sensor has a heat generation resistor that generates heat when energized, and measures the air flow rate flowing through the sub-secondary flow path based on the temperature distribution generated by the heat generation resistor. The circuit unit has a function of controlling the energizing current to the heat generation resistor. This conventional air flow rate measuring device is characterized in that a circuit portion is arranged in a sub-sub-channel and is exposed to the flow of air flowing through the sub-sub-channel.

According to the above configuration, since it is not necessary to provide a dedicated space for arranging the circuit portion inside the sensor body, the physique of the sensor body does not increase in size. Further, the space for forming the sub-secondary flow path inside the sensor body is not reduced. As a result, the air flow rate flowing through the sub-secondary flow path can be accurately measured without increasing the flow path loss of the sub-secondary flow path. Further, by arranging the circuit unit in the sub-sub-channel, the circuit unit can be cooled by the air flowing through the sub-sub-channel, so that the heat dissipation to the circuit unit is improved (see the same document, paragraph 0007, etc.). ..

Japanese Patent No. 4968267

In the above-mentioned conventional air flow rate measuring device, a part of the air flowing inside the duct is taken into the sub-channel, and a part of the air flowing through the sub-channel is taken into the sub-sub-channel and flows through the sub-sub-channel. The air flow rate is measured by a flow sensor. However, the sub-secondary flow path extends vertically inside the sensor body, that is, in a direction orthogonal to the air flow direction inside the duct (see the same document, FIG. 1 and paragraph 0013, etc.).

Therefore, the air flowing through the sub-channel is strongly pressed against the wall surface of the sub-subchannel that is branched from the sub-channel and is located on the downstream side of the sub-channel, and the air flowing into the sub-subchannel is pressed. As the flow velocity increases, the amount of dust flowing into the sub-secondary flow path may increase. If the amount of dust flowing from the sub-channel to the sub-subchannel increases, the accumulation of dust on the circuit unit and the flow rate sensor may proceed in a short period of time, and the measurement accuracy of the flow rate sensor may decrease in a short period of time.

The present disclosure provides a physical quantity detecting device capable of reducing dust flowing into a second sub-passage branching from a first sub-passage and improving stain resistance.

One aspect of the present disclosure is a physical quantity detecting device for detecting a physical quantity of a gas flowing through a main passage, comprising a sensor for detecting the physical quantity and a housing for accommodating the sensor, and the housing comprises the main passage. It has a flange fixed to and a measuring unit extending from the flange toward the center of the main passage, and the measuring unit is provided at a tip portion opposite to the flange and is provided along the central axis of the main passage. It has a first sub-passage extending from the first sub-passage, a second sub-passage branching from the first sub-passage toward the flange and arranging the sensor, and a rectifying surface provided at the tip of the tip portion. The rectifying surface is provided on the upstream rectifying surface provided so as to approach the flange from the upstream side to the downstream side of the main passage, and on the downstream side of the main passage with respect to the upstream rectifying surface. It is a physical quantity detecting device characterized by having a downstream rectifying surface extending along the central axis of the housing.

According to the above aspect, it is possible to provide a physical quantity detecting device capable of reducing the dust flowing into the second sub-passage branching from the first sub-passage and improving the stain resistance.

A system diagram of an internal combustion engine control system using a physical quantity detection device. The front view of the physical quantity detection apparatus shown in FIG. The front view which shows the state which removed the cover of the physical quantity detection apparatus shown in FIG. An enlarged view of the tip of the measurement unit of the physical quantity detection device shown in FIG. 3. The enlarged view which shows the modification of the physical quantity detection apparatus shown in FIG. The enlarged view which shows the modification of the physical quantity detection apparatus shown in FIG. The enlarged view which shows the modification of the physical quantity detection apparatus shown in FIG.

Hereinafter, embodiments of the physical quantity detection device according to the present disclosure will be described with reference to the drawings.

FIG. 1 is a system diagram of an electronic fuel injection type internal combustion engine control system 1 using the physical quantity detection device 20 according to the embodiment of the present disclosure. Based on the operation of the internal combustion engine 10 including the engine cylinder 11 and the engine piston 12, the intake air is sucked from the air cleaner 21 as the measured gas 2, for example, the intake body which is the main passage 22, the throttle body 23, and the intake manifold 24. It is guided to the combustion chamber of the engine cylinder 11 via the engine. The physical amount of the measured gas 2 which is the intake air guided to the combustion chamber is detected by the physical amount detecting device 20, fuel is supplied from the fuel injection valve 14 based on the detected physical amount, and the air-fuel mixture is supplied together with the measured gas 2. It is guided to the combustion chamber in the state of. In the present embodiment, the fuel injection valve 14 is provided in the intake port of the internal combustion engine, and the fuel injected into the intake port forms an air-fuel mixture together with the gas to be measured 2 and is guided to the combustion chamber via the intake valve 15. It burns and generates 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 the spark ignition of the spark plug 13 to generate mechanical energy. The gas after combustion is guided to the exhaust pipe from the exhaust valve 16 and is discharged to the outside of the vehicle from the exhaust pipe as exhaust gas 3. The flow rate of the gas to be measured 2 which is the intake air guided to the combustion chamber is controlled by the throttle valve 25 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 25 to control the flow rate of the intake air guided to the combustion chamber, thereby internal combustion. The mechanical energy generated by the engine can be controlled.

The physical quantity such as the flow rate, temperature, humidity, and pressure of the gas to be measured 2 which is the intake air taken in through the air cleaner 21 and flows through the main passage 22 is detected by the physical quantity detection device 20, and the physical quantity of the intake air is detected by the physical quantity detection device 20. An electric signal representing the above is input to the control device 4. Further, the output of the throttle angle sensor 26 that measures the opening degree of the throttle valve 25 is input to the control device 4, the position and state of the engine piston 12 of the internal combustion engine, the intake valve 15 and the exhaust valve 16, and the rotation of the internal combustion engine. In order to measure the speed, the output of the rotation angle sensor 17 is input to the control device 4. The output of the oxygen sensor 28 is input to the control device 4 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 3.

The control device 4 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 20 and the rotation speed of the internal combustion engine measured based on the output of the rotation angle sensor 17. Based on these calculation results, the amount of fuel supplied from the fuel injection valve 14 and the ignition timing ignited by the spark plug 13 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 20, the state of change in engine rotation speed, and the state of air-fuel ratio measured by the oxygen sensor 28. It is finely controlled. Further, the control device 4 controls the amount of air bypassing the throttle valve 25 by the idle air control valve 27 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.

The fuel supply amount and ignition timing, which are the main control amounts of the internal combustion engine, are both calculated using the output of the physical quantity detection device 20 as the main parameter. Therefore, it is important to improve the detection accuracy of the physical quantity detecting device 20, suppress the change with time, and improve the reliability in order to improve the control accuracy and the reliability of the vehicle. Especially 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, which is the gas to be measured 2 detected by the physical quantity detection device 20. It is also important that the physical quantity detection device 20 maintains high reliability.

The vehicle equipped with the physical quantity detection device 20 is used in an environment where changes in temperature and humidity are large. It is desirable that the physical quantity detection device 20 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 detection device 20 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 detection device 20 via the intake pipe which is the main passage 22. Since the physical quantity detection device 20 detects the flow rate of the gas to be measured by conducting heat transfer with 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 20 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 20 and specific effects to be achieved will be described in the description of the following embodiments.

FIG. 2 is a front view of the physical quantity detection device 20 shown in FIG. The physical quantity detection device 20 is inserted into the main passage 22 through an attachment hole provided in the passage wall of the main passage 22 and used. The physical quantity detection device 20 includes a housing 201 and a cover 202 attached to the housing 201. The housing 201 is formed by injection molding a synthetic resin material, and the cover 202 is made of a plate-shaped member made of a conductive material such as an aluminum alloy. The cover 202 is formed in the shape of a thin plate and has a wide flat cooling surface.

The housing 201 is provided with a flange 211 fixed to the intake body, which is the main passage 22, a connector 212 protruding from the flange 211 and exposed to the outside from the intake body for electrical connection with an external device, and the flange 211. It has a measuring unit 213 extending so as to project toward the center of the main passage 22.

The flange 211 has, for example, a substantially rectangular shape in a plan view having a predetermined plate thickness, and has a through hole at a corner portion. The flange 211 is fixed to the main passage 22 by, for example, a fixing screw being inserted into a through hole at a corner and screwed into a screw hole of the main passage 22.

The connector 212 is provided with, for example, four external terminals and a correction terminal inside the connector 212. The external terminals are terminals for outputting physical quantities such as flow rate and temperature, which are measurement results of the physical quantity detection device 20, and power supply terminals for supplying DC power for operating the physical quantity detection device 20. The correction terminal is a terminal used to measure the produced physical quantity detection device 20, obtain a correction value for each physical quantity detection device 20, and store the correction value in the memory inside the physical quantity detection device 20. ..

The measuring unit 213 has a thin and long shape extending from the flange 211 toward the center of the main passage 22, and has a wide front surface 221 and a back surface, and a pair of narrow side surfaces, an upstream end surface 223 and a downstream end surface 224. Have. The measuring unit 213 is inserted into the inside through a mounting hole provided in the main passage 22, for example, and the flange 211 is brought into contact with the main passage 22 and fixed to the main passage 22 with a screw, whereby the measuring unit 213 is mainly inserted through the flange 211. It is fixed to the passage 22.

The measuring unit 213 projects from the inner wall of the main passage 22 toward the central axis 22a of the main passage 22 in a state where the physical quantity detection device 20 is attached to the main passage 22. The front surface 221 and the back surface are arranged in parallel along the central axis 22a of the main passage 22, and the upstream end surface of the measurement unit 213 on one side in the lateral direction of the narrow upstream end surface 223 and the downstream end surface 224 of the measurement unit 213. The 223 is arranged so as to face the upstream side of the main passage 22, and the downstream end surface 224 on the other side in the lateral direction of the measuring unit 213 is arranged so as to face the downstream side of the main passage 22.

The front surface 221 of the measuring unit 213 is flat from the upstream end surface 223 to the downstream end surface 224 along the lateral direction. On the other hand, the back surface of the measuring unit 213 is chamfered at the corner portion on the downstream end surface 224 side, and is inclined in a direction gradually approaching the front surface as it shifts from the intermediate position in the lateral direction to the downstream end surface 224. As a result, the cross-sectional shape of the measuring unit 213 is so-called streamlined. Therefore, the gas to be measured 2 flowing from the upstream of the main passage 22 can be smoothly guided downstream along the front surface 221 and the back surface of the measurement unit 213, and the fluid resistance of the measurement unit 213 to the gas to be measured 2 is reduced. be able to.

The measuring unit 213 has a stepped end in the protruding direction, and with the physical quantity detection device 20 attached to the main passage 22, the lower surface 226 on the upstream side of the main passage 22 and the downstream side of the main passage 22. It has a rectifying surface 227 of the above. In the measuring unit 213, the rectifying surface 227 on the downstream side protrudes in the protruding direction from the lower surface 226 on the upstream side, and the upstream end surface 228 is a stepped surface connecting the lower surface 226 on the upstream side and the rectifying surface 227 on the downstream side. Is arranged so as to face the upstream side of the main passage 22.

Although the details will be described later, the physical quantity detection device 20 of the present embodiment has the following configuration as the greatest feature. The measuring unit 213 has a rectifying surface 227 provided at the tip of the tip portion 213a. The rectifying surface 227 has an upstream rectifying surface 227a and a downstream rectifying surface 227b. The upstream straightening surface 227a is provided so as to approach the flange 211 from the upstream side to the downstream side of the main passage 22. The downstream rectifying surface 227b is provided on the downstream side of the main passage 22 with respect to the upstream rectifying surface 227a, and extends along the central axis 22a of the main passage 22.

Further, the measuring unit 213 places a part of the gas to be measured 2 such as intake air in the auxiliary passage in the measuring unit 213 on the upstream end surface 228 of the tip portion 213a which is opposite to the flange 211 and protrudes from the lower surface 226 on the upstream side. The entrance 231 for taking in the air is provided as an opening. Then, at the downstream end surface 224 of the tip portion 213a of the measuring unit 213, a first outlet 232 and a second outlet 233 for returning the gas to be measured 2 taken into the sub-passage in the measuring unit 213 to the main passage 22 are opened. It is provided.

That is, the measurement unit 213 has an upstream end surface 223 as a first wall portion arranged toward the upstream side in the flow direction of the gas to be measured 2 in the main passage 22. Further, the measuring unit 213 is arranged toward the upstream side in the flow direction of the measured gas 2 at a position downstream of the upstream end surface 223 as the first wall portion in the main passage 22 in the flow direction of the measured gas 2. The second wall portion has an upstream end surface 228 of the tip portion 213a. The entrance 231 of the sub-passage is opened in the upstream end surface 228, which is the stepped surface of the tip portion 213a.

In the physical quantity detecting device 20, since the inlet 231 of the sub-passage is provided at the tip portion 213a of the measuring unit 213 extending from the flange 211 toward the center of the main passage 22, the physical quantity detecting device 20 is not near the inner wall surface of the main passage 22. The gas in the part near the central part away from the inner wall surface can be taken into the sub-passage. Therefore, the physical quantity detection device 20 can measure the flow rate of the gas in the portion away from the inner wall surface of the main passage 22, and can suppress the deterioration of the measurement accuracy due to the influence of heat or the like.

In the vicinity of the inner wall surface of the main passage 22, the temperature of the main passage 22 is easily affected, and the temperature of the gas to be measured 2 is different from the original temperature of the gas. It will be different from the state. In particular, when the main passage 22 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 in the vicinity of the inner wall surface of the main passage 22 is often higher than the original temperature of the main passage 22, which causes a decrease in measurement accuracy. Further, the fluid resistance is large in the vicinity of the inner wall surface of the main passage 22, and the flow velocity is lower than the average flow velocity of the main passage 22. Therefore, if the gas near the inner wall surface of the main passage 22 is taken into the sub-passage as the gas to be measured 2, a decrease in the flow velocity with respect to the average flow velocity of the main passage 22 may lead to a measurement error.

Since the physical quantity detection device 20 is provided with the inlet 231 at the tip portion 213a of the thin and long measuring unit 213 extending from the flange 211 toward the center of the main passage 22, it is related to the decrease in the flow velocity near the inner wall surface of the main passage 22. The measurement error to be performed can be reduced. Further, in the physical quantity detecting device 20, not only the inlet 231 is provided at the tip portion 213a of the measuring unit 213 extending from the flange 211 toward the center of the main passage 22, but also the first outlet 232 and the second exit of the sub passage are provided. Since the 233 is also provided at the tip portion 213a of the measurement unit 213, the measurement error can be further reduced.

The physical quantity detecting device 20 has a shape in which the measuring unit 213 extends long along the axis from the outer wall of the main passage 22 toward the center, but the width of the upstream end surface 223 and the downstream end surface 224 is larger than the width of the front surface 221. It is narrow and the measuring unit 213 has a plate-like shape. As a result, the physical quantity detection device 20 can suppress the fluid resistance to a small value with respect to the gas to be measured 2.

FIG. 3 is a front view showing a state in which the cover 202 of the physical quantity detection device 20 shown in FIG. 2 is removed. Note that FIG. 3 omits the illustration of the sealing material that seals the circuit board 207.

The measurement unit 213 is provided with a sub-passage groove 250 for forming the sub-passage 234 and a circuit chamber 235 for accommodating the circuit board 207. The circuit chamber 235 and the sub-passage groove 250 are recessed in the front surface of the measuring unit 213, and are arranged separately on one side and the other side in the lateral direction of the measuring unit 213. The circuit chamber 235 is arranged at a position upstream of the flow direction of the measured gas 2 in the main passage 22, and the sub-passage 234 is located downstream of the circuit chamber 235 in the flow direction of the measured gas 2 in the main passage 22. Placed in position. In the flow direction of the gas to be measured 2 in the main passage 22, the surface on the upstream side of the wall portion on the upstream side of the circuit chamber 235 is set to the upstream end surface 223 of the measurement unit 213, so that space can be saved.

The sub-passage groove 250 forms the sub-passage 234 in cooperation with the cover 202. The sub-passage 234 is provided so as to extend along the longitudinal direction of the measuring unit 213, which is the protruding direction of the measuring unit 213. The sub-passage groove 250 forming the sub-passage 234 has a first sub-passage groove 251 and a second sub-passage groove 252 that branches in the middle of the first sub-passage groove 251.

The first sub-passage groove 251 extends between the inlet 231 that opens at the upstream end surface 228 of the tip portion 213a of the measuring unit 213 and the first outlet 232 that opens at the downstream end surface 224 of the tip portion 213a of the measuring unit 213. , Is formed so as to extend along the lateral direction of the measuring unit 213. The inlet 231 is opened so as to face the upstream side in the flow direction of the gas to be measured 2 in the main passage 22. The first sub-passage groove 251 forms a first sub-passage 234a extending from the inlet 231 along the central axis 22a of the main passage 22 to the first exit 232 with the cover 202.

The first sub-passage 234a takes in the measured gas 2 flowing in the main passage 22 from the inlet 231 and returns the taken-in measured gas 2 to the main passage 22 from the first outlet 232. The first sub-passage 234a extends from the inlet 231 along the flow direction of the gas to be measured 2 in the main passage 22, and is connected to the first outlet 232.

The second sub-passage groove 252 branches toward the base end portion of the measuring unit 213, that is, the flange 211 at an intermediate position of the first sub-passage groove 251 in the longitudinal direction of the measuring unit 213, that is, in the central axis 22a of the main passage 22. It extends in a direction that intersects, for example, in a direction that is approximately orthogonal to the central axis 22a. Further, the second sub-passage groove 252 bends back toward the tip portion 213a in the vicinity of the flange 211 of the measurement unit 213, for example, in a U-shape or an arc shape, and is folded back in the longitudinal direction of the measurement unit 213, that is, in the main passage 22. It extends in a direction intersecting the central axis 22a, for example, in a direction substantially orthogonal to the central axis 22a.

The second sub-passage groove 252 is finally bent toward the downstream end surface 224 of the measuring unit 213 so as to be curved in an arc shape, for example, and is connected to the second outlet 233. The second outlet 233 is opened so as to face the downstream side in the flow direction of the gas to be measured 2 in the main passage 22. The second outlet 233 has an opening area substantially equal to or slightly larger than that of the first outlet 232, and is formed at a position adjacent to the proximal end side of the measuring unit 213 in the longitudinal direction of the first outlet 232. .. The second sub-passage groove 252 forms a second sub-passage 234b that branches from the first sub-passage 234a toward the flange 211 and reaches the second outlet 233 with the cover 202.

The second sub-passage 234b passes through the gas to be measured 2 branched from the first sub-passage 234a and flows back to the main passage 22 from the second outlet 233. The second sub-passage 234b has a reciprocating path along the longitudinal direction of the measuring unit 213. More specifically, the second sub-passage 234b has, for example, a linear upstream portion, an arc-shaped curved portion, and a linear downstream portion.

The upstream portion of the second sub-passage 234b branches from the first sub-passage 234a and extends straight toward the flange 211 of the measurement unit 213. The curved portion of the second sub-passage 234b is connected to the upstream portion in the vicinity of the flange 211, and is curved in an arc shape or a U shape so as to be folded back toward the tip portion 213a of the measurement unit 213. The downstream portion of the second sub-passage 234b is connected to the curved portion in the vicinity of the flange 211, extends straight toward the tip portion 213a of the measuring unit 213, and curves toward the downstream end surface 224 at the tip portion 213a to be the second. It is connected to exit 233.

In the second sub-passage 234b, for example, a flow rate sensor 205 is arranged in an upstream portion. More specifically, in the upstream portion of the second sub-passage 234b, the flow rate sensor 205 is arranged in the intermediate portion between the first sub-passage 234a and the curved portion. By having the curved shape as described above, the second sub-passage 234b can secure a longer passage length and reduce the influence on the flow rate sensor 205 when pulsation occurs in the main passage. be able to.

According to the above configuration, the sub-passage 234 can be formed along the longitudinal direction which is the projecting direction of the measurement unit 213, and the length of the sub-passage 234 can be sufficiently long. As a result, the physical quantity detection device 20 can be provided with a sub-passage 234 having a sufficient length. Therefore, the physical quantity detection device 20 can suppress the fluid resistance to a small value and can measure the physical quantity of the gas to be measured 2 with high accuracy.

Since the first sub-passage 234a extends from the inlet 231 in the lateral direction of the measuring unit 213, that is, along the central axis 22a of the main passage 22 to reach the first exit 232, the first sub-passage 234a has entered the first sub-passage 234a from the inlet 231. Foreign matter such as dust can be discharged as it is from the first outlet 232. As a result, it is possible to suppress foreign matter from entering the second sub-passage 234b and to suppress the influence on the flow rate sensor 205 arranged in the second sub-passage 234b.

The inlet 231 and the first exit 232 of the first sub-passage 234a have a larger opening area at the inlet 231 than at the first outlet 232. By making the opening area of the inlet 231 larger than that of the first outlet 232, the gas to be measured 2 that has flowed into the first sub-passage 234a is also transferred to the second sub-passage 234b that is branched in the middle of the first sub-passage 234a. It can be surely guided.

In the vicinity of the inlet 231 of the first sub-passage groove 251, a protrusion 253 is provided at the center position of the inlet 231 in the longitudinal direction of the measuring unit 213. The protrusion 253 bisects the size of the inlet 231 in the longitudinal direction of the measuring unit 213, and the opening area of each of the bisected inlets 231 is larger than the opening areas of the first outlet 232 and the second outlet 233. I'm making it smaller. The protrusion 253 limits the size of foreign matter that can enter the first sub-passage 234a from the inlet 231 to those smaller than those smaller than the first outlet 232 and the second outlet 233, and the foreign matter causes the first outlet 232 and the second outlet. It is possible to prevent the 233 from being blocked.

The circuit board 207 is housed in a circuit chamber 235 provided on one side of the measuring unit 213 in the lateral direction. The circuit board 207 has a rectangular shape extending along the longitudinal direction of the measuring unit 213, and has a chip package 208, a pressure sensor 204, a temperature / humidity sensor 206, and an intake temperature sensor on the surface thereof. 203 and is implemented. The circuit board 207 has a mounting portion common to all sensors, and can be commonly used for mounting patterns of various sensors. The surface of the circuit board 207 is arranged substantially parallel to the gas to be measured 2 flowing through the main passage 22, for example. This makes it possible to reduce the thickness of the measuring unit 213 and reduce the pressure loss of the gas to be measured 2 flowing through the main passage 22.

The chip package 208 is mounted on the circuit board 207. A flow rate sensor 205 and an LSI, which is an electronic component for driving the flow rate sensor 205, are mounted on the chip package 208 and sealed by a transfer mold. The chip package 208 has a part of the chip package 208 from the circuit board 207 to the second sub-passage 234b at the center position in the longitudinal direction of the circuit board 207 so that the flow sensor 205 is arranged in the second sub-passage 234b. It is mounted in a protruding state.

The chip package 208 is arranged between the sub-passage 234 and the circuit chamber 235. As a result, the circuit chamber 235 and the sub-passage 234 are separated, and the flow to the flow rate sensor 205 arranged in the chip package 208 is rate-controlled by the shape of the sub-passage 234. Therefore, there is no barrier that obstructs the flow of the gas to be measured 2 in the sub-passage 234, and a stable flow of the gas to be measured 2 can be supplied to the flow rate sensor 205. Therefore, it is possible to reduce the size of the measurement unit 213 while maintaining the flow velocity sensitivity, noise performance, and pulsation characteristics of the flow rate sensor.

The flow rate sensor 205 does not necessarily have to be provided in the chip package 208. For example, the flow rate sensor 205 may be arranged in the sub-passage 234 by projecting a part of the circuit board 207, or the flow rate sensor 205 mounted on the circuit board 207 may be arranged in the sub-passage 234 by a plate-shaped support. May be good.

The flow rate sensor 205 and the LSI may be integrally formed on the same semiconductor element or may be formed as different semiconductor elements. The flow rate sensor 205 is sealed with a resin so that the flow rate measuring portion on the surface is at least exposed. Although the structure in which the LSI is provided in the chip package 208 has been described, the structure in which the LSI is mounted on the circuit board 207 may be used. The advantage of providing the LSI in the chip package 208 is that it is not necessary to mount the LSI on the circuit board 207, which contributes to the miniaturization of the circuit board 207.

The chip package 208 has a concave groove extending along the flow direction of the gas to be measured 2 in the upstream portion of the second sub-passage 234b, and the flow sensor 205 is provided at the bottom of the concave groove. The concave groove of the chip package 208 has a narrowed shape in which the width gradually narrows from both ends to the center in the flow direction of the gas to be measured 2 flowing upstream of the second sub-passage 234b, and the narrowest center. A flow rate sensor 205 is arranged in the section. Due to this throttle shape, the gas to be measured 2 flowing through the sub-passage 234 is rectified, and the influence of noise can be reduced.

The pressure sensor 204 is mounted on the longitudinal proximal end side of the circuit board 207 with respect to the chip package 208, and the temperature / humidity sensor 206 is mounted on the longitudinal distal end side of the circuit board 207 with respect to the chip package 208. .. The lead of the intake air temperature sensor 203 is connected to the surface of the circuit board 207. The lead of the intake air temperature sensor 203 is connected to the position on the longitudinal tip side of the circuit board 207 with respect to the temperature / humidity sensor 206, and the sensor body 203b protrudes from the circuit board 207 in the longitudinal direction and is exposed to the outside of the measuring unit 213. It is implemented to be placed in.

The intake air temperature sensor 203 is arranged between the upstream end surface 223 on the flange 211 side of the measuring unit 213 and the upstream end surface 228 of the tip portion 213a. The intake air temperature sensor 203 is mounted on the circuit board 207 and is provided so as to be exposed to the outside of the measurement unit 213. The intake air temperature sensor 203 is composed of an axial lead component having a columnar sensor body and a pair of leads projecting from both ends in the axial direction of the sensor body in a direction away from each other. The measuring unit 213 is provided with a protector 202a for protecting the intake air temperature sensor 203.

In the measuring unit 213, (1) the pressure sensor 204, (2) the flow sensor 205, (toward the protruding direction of the measuring unit 213) from the base end side to the tip end side along the longitudinal direction thereof. 3) The temperature / humidity sensor 206 and (4) the intake air temperature sensor 203 are arranged in this order. The pressure sensor 204 detects the pressure of the gas to be measured 2, and the flow rate sensor 205 detects the flow rate of the gas to be measured 2. The temperature / humidity sensor 206 detects the humidity of the gas to be measured 2, and the intake air temperature sensor detects the temperature of the gas 2 to be measured.

FIG. 4 is an enlarged view of the tip portion 213a of the measurement unit 213 of the physical quantity detection device 20 from which the cover 202 shown in FIG. 3 is removed. Hereinafter, the characteristic portion of the physical quantity detection device 20 of the present embodiment will be described in detail.

As described above, the physical quantity detection device 20 of the present embodiment has the following configuration as the greatest feature. The measuring unit 213 has a rectifying surface 227 provided at the tip of the tip portion 213a and provided so as to approach the flange 211 from the upstream end surface 228 toward the downstream end surface 224. The portion of the rectifying surface 227 on the downstream side of the upstream side in the forward flow direction of the gas to be measured 2 flowing through the main passage 22 is closer to the flange 211 and closer to the inner wall surface of the main passage 22 to which the flange 211 is attached. ing.

The straightening surface 227 may have, for example, a plurality of planes, angles, and steps, but has a streamlined shape continuous from the upstream end surface 228 to the downstream end surface 224 with respect to the gas to be measured 2 flowing through the main passage 22. It is preferable to have it. For example, the slope of the tangent of the rectifying surface 227 continuously changes from the upstream side to the downstream side in the direction of the forward flow of the gas to be measured 2 flowing through the main passage 22. In the front view shown in FIG. 4, the straightening vane 227 has an S-shaped smooth curved shape having an inflection point.

The rectifying surface 227 has an upstream rectifying surface 227a and a downstream rectifying surface 227b, respectively, on the upstream side and the downstream side in the direction of the forward flow of the gas to be measured 2 flowing through the main passage 22. That is, the upstream rectifying surface 227a and the downstream rectifying surface 227b are a portion on the upstream side of the rectifying surface 227 and a portion on the downstream side of the rectifying surface 227, respectively. Here, "upstream" and "downstream" are based on the direction of the forward flow of the gas to be measured 2 flowing through the main passage 22. That is, in the example shown in FIG. 1, the one relatively close to the air cleaner 21 is the upstream side, and the one relatively close to the internal combustion engine 10 is the downstream side.

The upstream rectifying surface 227a is provided so as to approach the flange 211 from the upstream end surface 228 of the tip portion 213a of the measuring unit 213 toward the downstream side of the main passage 22. More specifically, the upstream straightening surface 227a is inclined at an inclination angle of less than 90 degrees with respect to the central axis 22a of the main passage 22 so as to approach the flange 211 from the upstream side to the downstream side of the main passage 22. It has a surface 227c.

The inclined surface 227c of the upstream straightening surface 227a passes through the center of the tip portion 213a in the lateral direction of the measuring unit 213 and is closer to the upstream end surface 228 than the center line CL parallel to the longitudinal direction of the measuring unit 213, for example. To the downstream rectifying surface 227b. In the front view shown in FIG. 4, the upstream portion of the inclined surface 227c is provided in a convex curved surface shape that bulges toward the protruding direction of the measuring unit 213, and the downstream portion in the vicinity of the downstream straightening surface 227b of the inclined surface 227c. Is provided in the shape of a concave curved surface opposite to the convex curved surface of the upstream portion.

The inclined surface 227c shown in FIG. 4 has an inclined angle of, for example, 45 degrees or less with respect to the central axis 22a of the main passage 22 shown in FIG. As shown in FIG. 4, when the inclined surface 227c is a curved surface, the inclination angle of the inclined surface 227c is the angle of the tangent line of the inclined surface 227c. That is, the inclined surface 227c shown in FIG. 4 has a tangential angle of 45 degrees or less over the entire flow direction of the gas to be measured 2 flowing through the main passage 22.

Further, the upstream straightening surface 227a has an upstream flat surface portion 227d extending from the upstream end surface 228 toward the downstream side of the main passage 22 along the central axis 22a of the main passage 22. The upstream plane portion 227d is, for example, a plane parallel to the central axis 22a of the main passage 22, and is provided on the upstream side of the main passage 22 with respect to the center line CL of the tip portion 213a of the measuring unit 213.

The downstream rectifying surface 227b is provided on the downstream side of the main passage 22 with respect to the upstream rectifying surface 227a, and extends to the downstream end surface 224 along the central axis 22a of the main passage 22. The downstream straightening surface 227b is, for example, a plane substantially parallel to the central axis 22a of the main passage 22, and is provided on the downstream side of the main passage 22 with respect to the center line CL of the tip portion 213a of the measuring unit 213.

Hereinafter, the operation of the physical quantity detection device 20 of the present embodiment will be described.

As shown in FIG. 1, the physical quantity detection device 20 is inserted into the main passage 22 through a mounting hole provided in the passage wall of the main passage 22, and the flange 211 shown in FIGS. 2 and 3 is inserted into the main passage 22. It is fixed to the passage wall of. Based on the operation of the internal combustion engine 10, the intake air is sucked from the air cleaner 21 as the measured gas 2, and the measured gas 2 flows through the main passage 22. The gas to be measured 2 flowing through the main passage 22 flows substantially along the central axis 22a and is taken into the first sub-passage 234a from the inlet 231 provided in the measurement unit 213 of the physical quantity detection device 20.

A part of the gas to be measured 2 taken into the measuring unit 213 from the inlet 231 of the physical quantity detection device 20 flows through the first sub-passage 234a extending along the central axis 22a of the main passage 22, and is discharged from the first outlet 232. It is returned to the main passage 22. Further, a part of the gas to be measured 2 flowing through the first sub-passage 234a flows into the second sub-passage 234b branching from the first sub-passage 234a toward the flange 211.

The gas to be measured 2 that has flowed into the second sub-passage 234b flows on the front surface side and the back surface side of the chip package 208 shown in FIG. At this time, the flow rate sensor 205 provided in the chip package 208 detects the flow rate of the gas to be measured 2 flowing through the concave groove on the surface side of the chip package 208. Further, the intake air temperature sensor 203 detects the temperature of the gas to be measured 2 before being taken into the inlet 231 of the measuring unit 213, and the pressure sensor 204 and the temperature / humidity sensor 206 measure the measured gas in the circuit chamber 235 of the measuring unit 213. The pressure and humidity of the gas 2 are detected.

The gas to be measured 2 that has flowed into the upstream portion of the second sub-passage 234b and has passed through the chip package 208 is folded back toward the tip portion 213a of the measuring unit 213 at an arc-shaped or U-shaped curved portion, and is turned back toward the tip portion 213a of the measuring unit 213. It passes through the downstream portion of the passage 234b, is discharged from the second exit 233, and returns to the main passage 22. In the physical quantity detection device 20 having such a configuration, if the tip portion 213a of the measurement unit 213 does not have the rectifying surface 227, the following problems may occur.

The gas to be measured 2 that is taken into the measuring unit 213 from the inlet 231 of the physical quantity detection device 20 and flows through the first sub-passage 234a is strongly pressed against the wall surface 252a on the downstream side of the second sub-passage 234b. Then, in the cross section of the second sub-passage 234b, the maximum flow velocity of the gas to be measured 2 may increase. The amount of dust flowing from the first sub-passage 234a to the second sub-passage 234b is proportional to the maximum flow velocity and flow rate of the gas to be measured 2 in the cross section of the second sub-passage 234b. Therefore, if the maximum flow velocity of the gas to be measured 2 in the cross section of the second sub-passage 234b increases, the dust flowing from the first sub-passage 234a into the second sub-passage 234b may increase. As a result, the accumulation of dust on the chip package 208 and the flow rate sensor 205 may proceed in a short period of time, and the measurement accuracy of the flow rate sensor 205 may decrease in a short period of time.

On the other hand, the physical quantity detection device 20 of the present embodiment is a device for detecting the physical quantity of the gas to be measured 2 flowing through the main passage 22, and is characterized by the following configuration.

The physical quantity detection device 20 is a device that detects the physical quantity of the gas to be measured 2 flowing through the main passage 22. The physical quantity detecting device 20 includes a sensor for detecting the physical quantity and a housing 201 for accommodating the sensor. The housing 201 has a flange 211 fixed to the main passage 22, and a measuring unit 213 extending from the flange 211 toward the center of the main passage 22. The measuring unit 213 has a first sub-passage 234a provided at the tip portion 213a on the opposite side of the flange 211 and extending along the central axis 22a of the main passage 22, and branches from the first sub-passage 234a toward the flange 211. It has a second sub-passage 234b in which the sensor is arranged, and a rectifying surface 227 provided at the tip of the tip portion 213a. The rectifying surface 227 is provided on the upstream rectifying surface 227a provided so as to approach the flange 211 from the upstream side to the downstream side of the main passage 22 and on the downstream side of the main passage 22 with respect to the upstream rectifying surface 227a. Has a downstream straightening surface 227b extending along the central axis 22a of the main passage 22.

More specifically, the physical quantity detecting device 20 includes a circuit board 207 on which a sensor for detecting the physical quantity is mounted, and a housing 201 for accommodating the circuit board 207. As described above, the housing 201 has a flange 211 fixed to the main passage 22 and a measuring unit 213 extending from the flange 211 toward the center of the main passage 22. The measuring unit 213 has an inlet 231, a first outlet 232, a second outlet 233, a first sub-passage 234a, a second sub-passage 234b, and a rectifying surface 227. The inlet 231 is provided on the upstream end surface 228 of the tip portion 213a on the opposite side of the flange 211. The first outlet 232 and the second outlet 233 are provided on the downstream end surface 224 of the tip portion 213a. The first sub-passage 234a extends from the inlet 231 along the central axis 22a of the main passage 22 to reach the first exit 232. The second sub-passage 234b branches from the first sub-passage 234a toward the flange 211 and reaches the second exit 233. The rectifying surface 227 is provided at the tip of the tip portion 213a and has an upstream rectifying surface 227a and a downstream rectifying surface 227b. The upstream straightening surface 227a is provided so as to approach the flange 211 from the upstream end surface 228 toward the downstream side of the main passage 22. The downstream rectifying surface 227b is provided on the downstream side of the main passage 22 with respect to the upstream rectifying surface 227a, and extends to the downstream end surface 224 along the central axis 22a of the main passage 22.

With such a configuration, as shown in FIG. 4, the gas to be measured 2 flowing through the main passage 22 flows from the upstream end surface 228 to the main passage 22 along the shape of the upstream rectifying surface 227a in the process of flowing along the rectifying surface 227. The flow direction changes so as to approach the flange 211 toward the downstream side of the. This change in the flow direction of the gas to be measured 2, that is, the deflection of the gas to be measured 2, not only affects the flow of the gas to be measured 2 over a wide radial range of the main passage 22, but also affects the upstream side of the rectifying surface 227. It also affects the gas to be measured 2 flowing through. That is, the flow of the gas to be measured 2 in the main passage 22 shifts so as to approach the flange 211 as a whole.

As a result, the gas to be measured 2 flowing through the first sub-passage 234a is conventionally applied to the wall surface 252a which is the wall surface of the second sub-passage 234b branched from the first sub-passage 234a and is located on the downstream side of the first sub-passage 234a. Can be collided more gently than. In other words, it is possible to suppress the flow of the gas to be measured 2 from being pressed against the wall surface 252a of the second sub-passage 234b and reduce the maximum flow velocity of the gas to be measured 2 in the cross section of the second sub-passage 234b. can. As a result, the amount of dust flowing from the first sub-passage 234a to the second sub-passage 234b is reduced.

Further, the rectifying surface 227 has a downstream rectifying surface 227b, and the downstream rectifying surface 227b is provided on the downstream side of the main passage 22 with respect to the upstream rectifying surface 227a, and is along the central axis 22a of the main passage 22 up to the downstream end surface 224. Is extending. With this configuration, the gas to be measured 2 flowing through the main passage 22 changes its flow direction from the upstream end surface 228 toward the downstream side of the main passage 22 toward the flange 211 along the shape of the upstream rectifying surface 227a, and then changes in the flow direction. , Flows along the downstream straightening surface 227b. The direction of the flow of the gas to be measured 2 flowing along the downstream straightening surface 227b is corrected to be along the central axis of the main passage 22.

As a result, the physical quantity detection device 20 is directed from the direction in which the gas to be measured 2 flows through the first sub-passage 234a, is discharged from the first outlet 232, and returns to the main passage 22 along the central axis 22a of the main passage 22. It is possible to suppress the change toward the flange 211 of the. By suppressing the direction of the flow of the gas to be measured 2 discharged from the first outlet 232 from changing from the direction along the central axis 22a of the main passage 22, the measured gas is measured in the cross section of the second sub-passage 234b. The increase in the flow rate of the gas 2 is suppressed. As a result, the increase of dust flowing from the first sub-passage 234a to the second sub-passage 234b is suppressed.

Therefore, according to the present embodiment, the accumulation of dust on the chip package 208 and the flow rate sensor 205 can be suppressed, the measurement accuracy of the flow rate sensor 205 can be maintained with high accuracy for a long period of time, and the stain resistance can be improved. A possible physical quantity detection device 20 can be provided.

Further, in the physical quantity detecting device 20 of the present embodiment, the upstream rectifying surface 227a is less than 90 degrees with respect to the central axis 22a of the main passage 22 so as to approach the flange 211 from the upstream side to the downstream side of the main passage 22. It has an inclined surface 227c inclined at an inclined angle.

With this configuration, it is possible to suppress the occurrence of separation of the gas to be measured 2 whose flow direction changes so as to approach the flange 211 from the upstream end surface 228 toward the downstream side of the main passage 22 along the shape of the upstream rectifying surface 227a. be able to. As a result, as described above, in the cross section of the second sub-passage 234b, the maximum flow velocity of the measured gas 2 is more reliably reduced and the increase in the flow rate of the measured gas 2 is suppressed, and the first sub-passage 234a is used. The amount of dust flowing into the second sub-passage 234b can be reduced more reliably.

Further, in the physical quantity detection device 20 of the present embodiment, the inclination angle of the inclined surface 227c with respect to the central axis 22a of the main passage 22 is 45 degrees or less.

With this configuration, it is more certain that the gas to be measured 2 whose flow direction changes so as to approach the flange 211 from the upstream end surface 228 toward the downstream side of the main passage 22 along the shape of the upstream rectifying surface 227a is separated. Can be suppressed. As a result, as described above, in the cross section of the second sub-passage 234b, the maximum flow velocity of the measured gas 2 is more reliably reduced and the flow rate of the measured gas 2 is reduced, and the first sub-passage 234a to the second The amount of dust flowing into the sub-passage 234b can be more reliably reduced.

Further, in the physical quantity detection device 20 of the present embodiment, the upstream rectifying surface 227a is the main passage 22 from the upstream end surface 228 of the tip portion 213a of the measuring unit 213 facing the upstream side of the main passage 22 toward the downstream side of the main passage 22. It has an upstream plane portion 227d extending along the central axis 22a of the above.

With this configuration, the gas to be measured 2 that flows from the upstream side of the physical quantity detection device 20 in the main passage 22 along the central axis 22a of the main passage 22 easily flows along the upstream plane portion 227d of the rectifying surface 227. As a result, the flow direction changes so that more gas to be measured 2 flowing along the upstream plane portion 227d flows along the inclined surface 227c and approaches the flange 211. As a result, in the cross section of the second sub-passage 234b, the maximum flow velocity of the gas to be measured 2 is more reliably reduced, and the amount of dust flowing from the first sub-passage 234a to the second sub-passage 234b is further reliably reduced. be able to.

Further, in the physical quantity detecting device 20 of the present embodiment, the rectifying surface 227 is a measuring unit 213 facing the downstream side of the main passage 22 from the upstream end surface 228 of the tip portion 213a of the measuring unit 213 facing the upstream side of the main passage 22. It has a streamlined shape that is continuous up to the downstream end surface 224 of the tip portion 213a.

With this configuration, the gas to be measured 2 flowing along the central axis 22a of the main passage 22 from the upstream side of the physical quantity detection device 20 in the main passage 22 easily flows along the rectifying surface 227. As a result, the flow direction of more gas to be measured 2 flowing along the rectifying surface 227 changes so as to approach the flange 211. As a result, in the cross section of the second sub-passage 234b, the maximum flow velocity of the gas to be measured 2 is more reliably reduced, and the amount of dust flowing from the first sub-passage 234a to the second sub-passage 234b is further reliably reduced. be able to.

As described above, according to the present embodiment, there is provided a physical quantity detecting device 20 capable of reducing the dust flowing into the second sub-passage 234b branched from the first sub-passage 234a and improving the stain resistance. can do. The physical quantity detection device according to the present disclosure is not limited to the configuration of the physical quantity detection device 20 according to the above-described embodiment. Hereinafter, some modifications of the physical quantity detection device 20 according to the above-described embodiment will be described.

FIG. 5 is an enlarged view showing a modified example of the physical quantity detection device 20 shown in FIG. In the modification shown in FIG. 5, the rectifying surface 227 is the tip portion 213a of the measuring unit 213 facing the downstream side of the main passage 22 from the upstream end surface 228 of the tip portion 213a of the measuring unit 213 facing the upstream side of the main passage 22. It is composed of a plurality of continuous planes up to the downstream end face 224. More specifically, the rectifying surface 227 is composed of three continuous planes, that is, an upstream flat surface portion 227d that is a flat surface, an inclined surface 227c that is a flat surface, and a downstream rectifying surface 227b that is a flat surface. The number of planes is not particularly limited, and the straightening plane 227 may be formed by four or more continuous planes. Also in this modification, the same effect as that of the physical quantity detection device 20 according to the above-described embodiment can be obtained.

FIG. 6 is an enlarged view showing another modification of the physical quantity detection device 20 shown in FIG. In the modified example shown in FIG. 6, the straightening surface 227 is composed of two continuous planes from the upstream end surface 228 to the downstream end surface 224 of the tip portion 213a of the measuring unit 213. More specifically, the rectifying surface 227 is composed of two continuous planes, an upstream rectifying surface 227a formed of a flat inclined surface 227c and a flat downstream rectifying surface 227b. Also in this modification, the same effect as that of the physical quantity detection device 20 according to the above-described embodiment can be obtained.

FIG. 7 is an enlarged view showing another modification of the physical quantity detection device 20 shown in FIG. In the modified example shown in FIG. 7, the rectifying surface 227 is composed of an upstream rectifying surface 227a having an inclined surface 227c which is a curved surface and a downstream rectifying surface 227b which is a flat surface. The inclined surface 227c is a curved surface having a constant curvature in the front view shown in FIG. 7, and is a partially cylindrical surface having an arc shape. Further, the straightening surface 227 has a streamlined shape continuous from the upstream end surface 228 to the downstream end surface 224 of the tip portion 213a of the measuring unit 213. Also in this modification, the same effect as that of the physical quantity detection device 20 according to the above-described embodiment can be obtained.

Although the embodiment of the physical quantity detection device according to the present disclosure has been described in detail with reference to the drawings, the specific configuration is not limited to the above-described embodiment, and the design does not deviate from the gist of the present disclosure. Any changes, etc., are included in this disclosure.

2 Measured gas (gas)
20 Physical quantity detection device 22 Main passage 22a Central axis 201 Housing 203 Intake air temperature sensor (sensor)
204 Pressure sensor (sensor)
205 Flow sensor (sensor)
206 Temperature / humidity sensor (sensor)
211 Flange 213 Measuring part 213a Tip part 224 Downstream end surface 227 Rectifying surface 227a Upstream rectifying surface 227b Downstream rectifying surface 227c Inclined surface 227d Upstream plane part 228 Upstream end surface 234a First sub-passage 234b Second sub-passage

Claims (6)

A physical quantity detection device that detects the physical quantity of gas flowing through the main passage.
A sensor for detecting the physical quantity and a housing for accommodating the sensor are provided.
The housing has a flange fixed to the main passage and a measuring unit extending from the flange toward the center of the main passage.
The measuring unit has a first sub-passage provided at the tip on the opposite side of the flange and extends along the central axis of the main passage, and the sensor is arranged by branching from the first sub-passage toward the flange. The second sub-passageway, the front and back surfaces arranged along the central axis of the main passage, the upstream end face that is narrower than the front and back and faces the upstream side of the main passage, and the front and back surfaces. The downstream end surface which is narrower and faces the downstream side of the main passage, the entrance of the first sub-passage provided on the upstream end surface of the tip portion, and the downstream end surface provided on the tip portion. 1 The first outlet of the sub-passage, the second outlet of the second sub-passage provided adjacent to the flange side of the first outlet of the downstream end surface of the tip, and the tip of the tip. With a rectified surface,
The rectifying surface is provided on the upstream rectifying surface provided so as to approach the flange from the upstream side to the downstream side of the main passage, and on the downstream side of the main passage with respect to the upstream rectifying surface. A physical quantity detecting device comprising: a downstream rectifying surface extending along a central axis to the tip of the downstream end surface adjacent to the first outlet . The upstream straightening surface is characterized by having an inclined surface inclined at an inclination angle of less than 90 degrees with respect to the central axis of the main passage so as to approach the flange from the upstream side to the downstream side of the main passage. The physical quantity detection device according to claim 1. The physical quantity detection device according to claim 2, wherein the inclination angle is 45 degrees or less. The upstream straightening surface is characterized by having an upstream plane portion extending along the central axis of the main passage from the upstream end surface of the tip portion facing the upstream side of the main passage toward the downstream side of the main passage. The physical quantity detection device according to claim 3. The straightening surface is characterized by having a streamlined shape continuous from the upstream end surface of the tip portion facing the upstream side of the main passage to the downstream end surface of the tip portion facing the downstream side of the main passage. The physical quantity detecting device according to any one of claims 1 to 4. The straightening surface is characterized by being composed of a plurality of planes continuous from the upstream end surface of the tip portion facing the upstream side of the main passage to the downstream end surface of the tip portion facing the downstream side of the main passage. The physical quantity detecting device according to any one of claims 1 to 4.

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