WO2015045435A1 - Débitmètre thermique - Google Patents

Débitmètre thermique Download PDF

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Publication number
WO2015045435A1
WO2015045435A1 PCT/JP2014/052604 JP2014052604W WO2015045435A1 WO 2015045435 A1 WO2015045435 A1 WO 2015045435A1 JP 2014052604 W JP2014052604 W JP 2014052604W WO 2015045435 A1 WO2015045435 A1 WO 2015045435A1
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WO
WIPO (PCT)
Prior art keywords
passage
intake port
gas
main
sub
Prior art date
Application number
PCT/JP2014/052604
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English (en)
Japanese (ja)
Inventor
征史 深谷
毅 森野
淳 井上
直生 斎藤
昌信 猪野
恵二 半沢
博 鬼川
忍 田代
Original Assignee
日立オートモティブシステムズ株式会社
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Application filed by 日立オートモティブシステムズ株式会社 filed Critical 日立オートモティブシステムズ株式会社
Publication of WO2015045435A1 publication Critical patent/WO2015045435A1/fr

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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01F—MEASURING VOLUME, VOLUME FLOW, MASS FLOW OR LIQUID LEVEL; METERING BY VOLUME
    • G01F1/00—Measuring the volume flow or mass flow of fluid or fluent solid material wherein the fluid passes through a meter in a continuous flow
    • G01F1/68—Measuring the volume flow or mass flow of fluid or fluent solid material wherein the fluid passes through a meter in a continuous flow by using thermal effects
    • G01F1/684—Structural arrangements; Mounting of elements, e.g. in relation to fluid flow
    • G01F1/6842—Structural arrangements; Mounting of elements, e.g. in relation to fluid flow with means for influencing the fluid flow
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01F—MEASURING VOLUME, VOLUME FLOW, MASS FLOW OR LIQUID LEVEL; METERING BY VOLUME
    • G01F1/00—Measuring the volume flow or mass flow of fluid or fluent solid material wherein the fluid passes through a meter in a continuous flow
    • G01F1/68—Measuring the volume flow or mass flow of fluid or fluent solid material wherein the fluid passes through a meter in a continuous flow by using thermal effects
    • G01F1/684—Structural arrangements; Mounting of elements, e.g. in relation to fluid flow
    • G01F1/6845—Micromachined devices

Definitions

  • the present invention relates to a thermal flow meter.
  • a thermal flow meter that measures the flow rate of gas includes a flow rate detection unit for measuring the flow rate, and performs heat transfer between the flow rate detection unit and the gas to be measured, thereby reducing the flow rate of the gas. It is configured to measure.
  • the flow rate measured by the thermal flow meter is widely used as an important control parameter for various devices.
  • a feature of the thermal flow meter is that it can measure a gas flow rate, for example, a mass flow rate, with relatively high accuracy compared to other types of flow meters.
  • a vehicle equipped with an internal combustion engine has a very high demand for fuel saving and exhaust gas purification. In order to meet these demands, it is required to measure the intake air amount, which is a main parameter of the internal combustion engine, with high accuracy.
  • a thermal flow meter for measuring the amount of intake air led to an internal combustion engine includes a sub-passage that takes in a part of the intake air amount and a flow rate detector disposed in the sub-passage, and the flow rate detector is a gas to be measured.
  • the state of the gas to be measured flowing through the sub-passage is measured by performing heat transfer between and the electric signal, and an electric signal representing the amount of intake air guided to the internal combustion engine is output.
  • Patent Document 1 describes a measuring device in which a bulge for turning particles and liquid is formed in an inflow passage of a measurement casing on the upstream side of a measurement element, and the inflow passage extends from the inflow opening to the main flow.
  • a measuring device in which a raised portion is formed so as to be inclined at a predetermined angle with respect to a direction is disclosed.
  • the measuring element is located in a plane in which the inlet opening of the measuring casing on the upstream side of the measuring element is projected in the main flow direction in the pipe. For this reason, even if a member for turning liquid particles or dust particles is arranged upstream of the measurement element, there is a flow that bypasses the member, and the particles carried in the flow reach the measurement element. sell. Therefore, the effect of preventing the measuring element from being damaged by the fouling substance is not sufficient.
  • the present invention has been made in view of the above points, and the object of the present invention is not only to supply a fluid to be measured with a stable flow rate to a flow rate detection unit, but also to a fluid to be measured.
  • An object of the present invention is to provide a thermal flow meter that can reduce the amount of fouling substances contained in the flow rate detection unit.
  • the thermal flow meter includes a sub-passage that takes in part of the gas to be measured flowing through the main passage, and a flow rate detection unit that detects the flow rate of the gas to be measured flowing through the sub-passage.
  • the sub-passage is formed from a main intake port facing upstream of the main passage to an exhaust port for discharging part of the taken measurement gas so as to take in the measured gas flowing through the main passage. 1 passage, and a second passage formed from the sub intake port for taking in the gas to be measured flowing in the first passage toward the flow rate detection unit.
  • the upstream passage from the main intake port to the sub intake port in the first passage is separated from the flow rate detection unit with respect to the flow direction of the gas to be measured flowing through the main passage. It is inclined.
  • the flow rate detection unit and the discharge port are out of the projection range in which the main intake port is projected in the flow direction of the gas to be measured in the main passage.
  • the area of the discharge port is smaller than the area of the main intake port.
  • the fluid to be measured having a stable flow rate be supplied to the flow rate detection unit, but also the amount of fouling substances contained in the fluid to be measured reaches the flow rate detection unit can be reduced. it can.
  • FIG. 1 is a system diagram showing an embodiment in which a thermal flow meter according to the present invention is used in an internal combustion engine control system.
  • the front view which shows the external appearance of the thermal type flow meter which concerns on this invention.
  • the left view which shows the external appearance of the thermal type flow meter which concerns on this invention.
  • the rear view which shows the external appearance of the thermal type flow meter which concerns on this invention.
  • the right view which shows the external appearance of the thermal type flow meter which concerns on this invention.
  • the front view which shows the state of the housing which removed the front cover from the thermal type flow meter which concerns on this invention.
  • the rear view which shows the state of the housing which removed the back cover from the thermal type flow meter which concerns on this invention.
  • FIG. 2B is a cross-sectional view taken along line AA in FIG.
  • FIG. 6 is a schematic conceptual diagram of a sub-passage (Example 1) shown in FIG. 5. Schematic diagram showing a modified example (Example 2) of FIG. The schematic diagram which showed the modification (Example 3) of FIG. The schematic diagram which showed another modification (Example 4) of FIG.
  • FIG. 1 is a system diagram showing an embodiment in which a thermal flow meter according to the present embodiment is used in an electronic fuel injection type internal combustion engine control system.
  • an internal combustion engine 110 including an engine cylinder 112 and an engine piston 114
  • intake air is sucked from an air cleaner 122 as a measured gas IA and includes an intake pipe 71 in which a main passage 124 is formed.
  • the air is guided to the combustion chamber of the engine cylinder 112 through the intake body, the throttle body 126, and the intake manifold 128.
  • the flow rate of the gas to be measured IA that is the intake air led to the combustion chamber is measured by the thermal flow meter 30 according to the present embodiment, and fuel is supplied from the fuel injection valve 152 based on the measured flow rate. Together with the gas to be measured IA, which is introduced into the combustion chamber in the state of the air-fuel mixture.
  • 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 IA that is intake air, and is connected via the intake valve 116. It is guided to the combustion chamber and burns to generate mechanical energy.
  • the thermal flow meter 30 can be used not only for the method of injecting fuel into the intake port of the internal combustion engine shown in FIG. 1 but also for the method of directly injecting fuel into each combustion chamber. In both types, the basic concept of the control parameter measurement method including the method of using the thermal flow meter 30 and the control method of the internal combustion engine including the fuel supply amount and the ignition timing is substantially the same. A method of injecting fuel into the port is shown in FIG.
  • the fuel and air guided to the combustion chamber are in a mixed state of fuel and air, and are ignited explosively by spark ignition of the spark plug 154 to generate mechanical energy.
  • the combusted gas is guided from the exhaust valve 118 to the exhaust pipe, and is exhausted from the exhaust pipe to the outside as exhaust EA.
  • the flow rate of the gas to be measured IA that is the intake air led to the combustion chamber is controlled by a 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 flow rate of the intake air guided to the combustion chamber by controlling the opening degree of the throttle valve 132, thereby
  • the mechanical energy generated by the engine can be controlled.
  • the flow rate, humidity, and temperature of the measurement target gas IA that is the intake air that is taken in from the air cleaner 122 and flows through the main passage 124 are measured by the thermal flow meter 30, and the flow rate, humidity, and temperature of the intake air are measured from the thermal flow meter 30.
  • the electric signal to be represented is input to the control device 200.
  • 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.
  • 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.
  • the control device 200 calculates the fuel injection amount and the ignition timing based on the flow rate, humidity, and temperature of the intake air, which is the output of the thermal flow meter 30, and the rotation speed of the internal combustion engine from 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 intake air temperature and throttle angle change state measured by the thermal flow meter 30, the engine speed change state, and the air-fuel ratio state measured by the oxygen sensor 148. Are controlled. The control device 200 further controls the amount of air that bypasses the throttle valve 132 by the idle air control valve 156 in the idle operation state of the internal combustion engine, thereby controlling the rotational 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 all calculated using the output of the thermal flow meter 30 as a main parameter. Therefore, improvement in measurement accuracy of the thermal flow meter 30, suppression of changes over time, and improvement in reliability are important in terms of improving the control accuracy of the vehicle and ensuring reliability.
  • improvement in measurement accuracy of the thermal flow meter 30, suppression of changes over time, and improvement in reliability are important in terms of improving the control accuracy of the vehicle and ensuring reliability.
  • FIG. 2 shows the appearance of the thermal flow meter 30.
  • 2A is a front view of the thermal flow meter 30,
  • FIG. 2B is a left side view,
  • FIG. 2C is a rear view, and
  • FIG. 2D is a right side view.
  • the thermal flow meter 30 includes a housing 302, a front cover 303, and a back cover 304.
  • the housing 302 has an external connection portion (connector portion) having a flange 312 for fixing the thermal flow meter 30 to the intake body constituting the main passage and an external terminal for electrical connection with an external device.
  • a sub-passage groove for making a sub-passage is provided inside the measurement unit 310.
  • a casing having a sub-passage is formed. Inside the measurement unit 310, a circuit including a flow rate detection unit 602 for measuring the flow rate of the measurement target gas IA flowing through the main passage and a temperature detection unit 452 for measuring the temperature of the measurement target gas IA flowing through the main passage.
  • a package 400 is provided (see FIGS. 3A and 3B).
  • the measuring unit 310 is supported in a cantilever manner in the main passage by fixing the flange 312 to the intake body (intake pipe) 71.
  • the intake pipe 71 is indicated by a virtual line.
  • the measurement unit 310 of the thermal flow meter 30 has a shape extending long from the flange 312 toward the center of the main passage 124 in the radial direction, and a part of the measurement target gas IA such as intake air is provided at the tip thereof.
  • a main intake port 350 for taking in the sub-passage and an exhaust port 355 (see FIG. 2D) for returning the measured gas IA from the sub-passage to the main passage 124 are provided.
  • the main intake port 350 of the thermal flow meter 30 is provided on the distal end side of the measuring unit 310 extending from the flange 312 toward the central direction in the radial direction of the main passage, so that the portion away from the inner wall surface of the main passage is provided. Gas can be taken into the secondary passage. Thereby, it becomes difficult to be influenced by the temperature of the inner wall surface of the main passage, and a decrease in measurement accuracy of the gas flow rate and temperature can be suppressed.
  • the center of the main intake port 350 is offset with respect to the center line CL along the direction D in which the measured gas IA in the main passage 124 flows.
  • the main intake port 350 is provided at the distal end portion of the thin and long measuring unit 310 extending from the flange 312 toward the center of the main passage. Gas can be taken into the sub-passage (measurement passage). Further, since the discharge port 355 of the sub passage is also provided at the tip of the measuring unit 310, the gas flowing in the sub passage can be returned to the vicinity of the central portion of the main passage 124 having a high flow velocity.
  • the measuring unit 310 has a shape extending long along the axis from the outer wall of the main passage 124 toward the center, but the width has a narrow shape as shown in FIGS. 2B and 2D. That is, the measurement unit 310 of the thermal flow meter 30 has a side surface that is thin and has a substantially rectangular front surface. Thus, the thermal flow meter 30 can be provided with a sufficiently long sub-passage with a reduced fluid resistance with respect to the gas to be measured IA.
  • the temperature detection unit 452 for measuring the temperature of the measurement target gas IA is located at the center of the measurement unit 310 at a position where the upstream outer wall in the measurement unit 310 is recessed toward the downstream side, upstream from the upstream outer wall. It is provided with a shape that protrudes toward the surface.
  • the front cover 303 and the back cover 304 are formed in a thin plate shape and have a shape with a wide cooling surface. For this reason, the thermal flow meter 30 has an effect that air resistance is reduced, and further, the thermal flow meter 30 is easily cooled by the gas to be measured flowing through the main passage 124.
  • the external terminal includes a terminal for outputting a flow rate and temperature as measurement results, and a power supply terminal for supplying DC power.
  • the correction terminal is a terminal used to store a correction value related to the thermal flow meter 30 in a memory inside the thermal flow meter 30.
  • FIG. 3A and 3B show a state of the housing 302 with the front cover 303 or the back cover 304 removed from the thermal flow meter 30.
  • FIG. 3A is a front view showing the state of the housing with the front cover removed from the thermal flow meter according to the present invention
  • FIG. 3B shows the state of the housing with the back cover removed from the thermal flow meter according to the present invention.
  • the housing 302 is provided with a sub-passage groove for forming a sub-passage on the distal end side of the measuring unit 310.
  • the sub passage 330 is a passage formed in the thermal flow meter 30 in order to take in a part of the gas to be measured flowing through the main passage 124.
  • auxiliary passage grooves 332 and 334 are provided on both the front and back surfaces of the housing 302.
  • a part of the measurement target gas IA flowing through the main passage is taken into the back side sub passage groove 334 from the main intake port 350 via the inlet groove 531 and flows through the back side sub passage groove 334.
  • a part of the sub-passage 330 upstream of the first passage 31 and the second passage 32 is formed in the thermal flow meter 30.
  • the first passage 31 is a passage for discharging a pollutant formed from a main intake port 350 for taking in the measurement target gas IA flowing through the main passage 124 to a discharge port 355 for discharging a part of the taken measurement target gas IA. It is.
  • the second passage 32 is a flow rate measurement passage formed toward the flow rate detection unit 602 from the sub intake port 34 for taking in the measurement target gas IA flowing in the first passage 31.
  • the main intake port 350 is opened facing the upstream side of the main passage 124
  • the discharge port 355 is opened facing the downstream side of the main passage 124
  • the opening area of the discharge port 355 is: It is smaller than the opening area of the main intake port 350.
  • the passage groove of the second passage 32 (passage to the flow rate detection unit 602) has a shape that becomes deeper as it advances in the flow direction, and in the front side direction as it flows along the groove.
  • the gas to be measured IA moves gradually.
  • the back side sub-passage groove 334 is provided with a steeply inclined portion 347 that suddenly deepens in the upstream portion 342 of the circuit package 400. A part of the air having a small mass moves along the steeply inclined portion 347 and flows in the upstream portion 342 of the through portion 382 of the circuit package 400 toward the measurement channel surface 430 shown in FIG.
  • a foreign substance having a large mass cannot easily flow along the steeply inclined portion 347 because it is difficult to change the course due to centrifugal force, and flows along the measurement channel back surface 431 shown in FIG. After that, it passes through the downstream portion 341 of the penetrating portion 382 and flows through the front side auxiliary passage groove 332 shown in FIG. 3A.
  • the portion of the circuit package 400 that includes the measurement flow path surface 430 is disposed in the cavity of the through portion 382, and the through portion 382 is provided on the left and right sides of the circuit package 400 having the measurement flow passage surface 430.
  • the groove 334 and the front side auxiliary passage groove 332 are connected.
  • this flow rate measurement principle may be a general detection principle for a thermal flow meter, and flows through the main passage based on the measurement value measured by the flow rate detection unit 602 of the circuit package 400 as in this embodiment. As long as the flow rate of the gas to be measured can be detected, the configuration for detection is not particularly limited.
  • An outlet groove 353 forming 352 is discharged into the main passage 124.
  • the second passage formed by the back side sub-passage groove 334 is curved toward the flange direction from the tip of the housing 302 while drawing a curve, and the measured gas IA flowing through the sub-passage is closest to the flange side.
  • the flow is in the opposite direction to the flow of the main passage 124.
  • the sensor upstream side passage 32a provided on the back surface side of the second passage 32 provided on one side of the housing 302 is a second portion provided on the other side of the second passage 32 provided on the one side of the housing 302.
  • the sensor downstream side passage 32b provided on the surface side of the second passage 32 is connected.
  • the front end side of the circuit package 400 is disposed in the cavity of the through portion 382.
  • the space of the upstream portion 342 located on the upstream side of the circuit package 400 and the space of the downstream portion 341 located on the downstream side of the circuit package 400 are included in the penetration portion 382, and the penetration portion 382 is as described above.
  • the housing 302 is pierced so as to penetrate the front surface side and the back surface side.
  • the sensor upstream side passage 32a formed by the front side secondary passage groove 332 on the front surface side of the housing 302 and the sensor downstream side secondary passage groove 334 formed by the back side secondary passage groove 334 are formed.
  • the passage 32b communicates.
  • the space on the measurement flow path surface 430 side and the space on the measurement flow path back surface 431 side are divided by the circuit package 400 inserted in the housing 302, and depending on the housing 302 It has not been.
  • One space formed by the space of the upstream portion 342, the space of the downstream portion 341, the space on the measurement flow channel surface 430 side, and the space on the measurement flow channel back surface 431 side is the front and back surfaces of the housing 302.
  • the circuit package 400 inserted into the housing 302 protrudes in a cantilever manner in this one space.
  • the sub-passage grooves can be formed on both surfaces of the housing 302 in a single resin molding step, and the structure connecting the sub-passage grooves on both surfaces can be formed together.
  • the circuit package 400 is fixed by being embedded in a fixing portion 372, 373, 376 of the housing 302 by a resin mold.
  • a fixing structure can be mounted on the thermal flow meter 30 by insert molding the circuit package 400 into the housing 302 simultaneously with resin molding of the housing 302.
  • the back side sub-passage groove 334 includes a first passage wall 395, a back side sub-passage inner peripheral wall (second passage wall) 392, and a back side sub-passage outer peripheral wall ( Second wall 391).
  • the front end portions of the back side sub-passage inner peripheral wall 392 and the back side sub-passage outer peripheral wall 391 and the inner side surface of the back cover 304 are in close contact with each other, so that the first passage 31 and the second passage of the housing 302 A sensor upstream side passage 32a of the passage 32 is formed.
  • a front side sub-passage inner peripheral wall (second passage wall) 393 and a front side sub-passage outer peripheral wall (second passage wall) 394 are provided on both sides of the front side sub-passage groove 332, and these front side sub-passage inner peripheral walls 393. And the front end portion in the height direction of the front side sub-passage outer peripheral wall 394 and the inner side surface of the front cover 303 are in close contact with each other to form a downstream side sub-passage of the housing 302.
  • the gas IA to be measured that has been taken in from the main inlet 350 and has flowed through the first passage 31 constituted by the back side sub-passage groove 334 flows from the right side to the left side in FIG. 3B.
  • a part of the taken measurement gas IA flows in a diverted flow into the sub intake port 34 of the second passage 32 formed to branch from the first passage 31.
  • the gas to be measured IA flows through the upstream portion 342 of the penetrating portion 382 through the channel 386 formed by the surface of the measurement channel surface 430 of the circuit package 400 and the protrusion 356 provided on the front cover 303. Flows (see FIG. 4).
  • Other gas to be measured IA flows in the flow path 387 formed by the measurement flow path back surface 431 and the back cover 304. Thereafter, the measured gas IA that has flowed through the flow path 387 moves toward the front side sub-passage groove 332 via the downstream portion 341 of the penetrating portion 382, and merges with the measured gas IA that flows through the flow path 386.
  • the gas to be measured IA that has joined flows through the front side sub-passage groove 332 and is discharged from the outlet 352 to the main passage.
  • the sub-passage groove is such that the measured gas IA guided from the back side sub-passage groove 334 to the flow path 386 via the upstream portion 342 of the penetrating part 382 is bent more than the flow path guided to the flow path 387. Is formed. Thereby, a substance having a large mass such as dust contained in the measurement target gas IA collects in the flow path 387 with less bending.
  • the protrusion 356 forms a throttle, and the measurement gas IA is made into a laminar flow with little vortex. Further, the protrusion 356 increases the flow velocity of the measurement target gas IA. Thereby, measurement accuracy improves.
  • the protrusion 356 is formed on the front cover 303, which is a cover that faces the heat transfer surface exposed portion 436 of the flow rate detector 602 provided on the measurement flow path surface 430.
  • a hollow portion 336 is formed in the housing 302 between the flange 312 and the portion where the sub-passage groove is formed.
  • a terminal connection portion 320 that connects the connection terminal 412 of the circuit package 400 and the inner end 361 of the external terminal of the external connection portion 305 is provided.
  • the connection terminal 412 and the inner end 361 are electrically connected by spot welding or laser welding.
  • the gas to be measured IA in the main passage 124 flows in the forward direction, ie, the direction D, and is measured from the inlet of the sub-passage to be described, that is, from the main intake port 350 of the first passage 31.
  • the fluid IA flows with the fouling substance P.
  • the fouling substance is a substance that may foul the flow rate detection unit 602, and includes both solid (solid) and liquid (liquid).
  • the pollutant is granular, and for example, the solid granular material includes dust, and the liquid granular material includes, for example, water droplets and oil mist.
  • the dust collides with the flow rate detection unit (flow rate detection element) 602 and is damaged, or the oil mist adheres to the flow rate detection unit 602, resulting in measurement errors. May occur.
  • the measurement target gas IA in the main passage 124 includes water droplets
  • the water droplets adhere to the flow rate detection unit 602
  • an abnormality occurs in the measurement value of the mass flow rate.
  • the first passage 31 described above is provided, and the second passage 32 in which the flow rate detection unit 602 is disposed is formed so as to branch from the first passage 31. .
  • the first passage 31 takes in the measurement object taken in from the main intake port 350 facing the upstream side of the main passage 124 so as to take in the measurement gas IA flowing in the main passage 124.
  • This is a passage formed up to a discharge port 355 for discharging a part of the gas IA, and a part of the measured gas IA flowing into the sub-passage 330 from the main intake port 350 is discharged from the discharge port 355 together with the pollutant P. Is done.
  • the second passage 32 is formed from the sub intake port 34 that takes in the measurement target gas IA flowing in the first passage 31 toward the flow rate detection unit 602.
  • the upstream passage from the main intake port 350 to the first passage 31 is linear from the main intake port 350 to the upstream opening edge 34a of the sub intake port 34,
  • the upstream passage 31A from the main intake port 350 to the upstream opening edge 34a of the sub intake port 34 is a flow rate detection unit 602 with respect to the flow direction D of the gas to be measured flowing through the main passage. Inclined away from.
  • the center of the main intake port 350 of the first passage 31 is offset with respect to the center line CL along the direction D in which the measured gas IA of the main passage 124 flows (specifically,
  • the intake port 350 is formed at a position deviated from the center line CL), and upstream of the first passage 31 from the main intake port 350 to the sub intake port 34 (specifically, the upstream opening edge 34a).
  • the side passage 31A is inclined with respect to the center line CL so as to move away from the center line CL as it proceeds from the main intake port 350 to the sub intake port 34.
  • the upstream-side passage 31 ⁇ / b> A is provided at a certain angle ⁇ with respect to the direction D in which the measurement target gas IA flows in the main passage 124.
  • the upstream passage 31A restrains the direction of the flow flowing into the first passage 31 from the main intake port 350 along the upstream passage 31A, and the first passage 31 and the second passage In the 32 branching portions, the flow is made easier to be directed to the discharge port 355 side by moving away from the first passage 31 side.
  • the pollutant flowing in from the main intake port 350 is discharged from the discharge port 355.
  • the pollutant having a large particle size has a large inertia force and a large straightness
  • the pollutant flowing from the main intake port 350 flows into the upstream passage 31A with linearity. It becomes easy to discharge.
  • the discharge port 355 is formed in the direction in which the upstream side passage 31A extends from the main intake port 350, so that the pollutant that flows through the upstream side passage 31A is efficiently transferred to the discharge port 355. Can be shed.
  • the flow rate detection unit 602 is out of the projection range R in which the intake port 350 is projected in the flow direction D of the measurement target gas IA in the main passage 124, the pollutant that has flowed from the main intake port 350 travels straight. And never touch. Further, the remaining pollutant that has not been discharged from the first passage 31 is carried to the flow from the branch portion (sub-intake 34) toward the second passage 32, but the second passage 32 has a bend. Therefore, it is deflected to the outer peripheral side under the action of centrifugal force at the bent portion. For this reason, the pollutant passes through a position away from the flow rate detection unit 602 in the passage. As a result, the amount of fouling substances reaching the flow rate detection unit 602 is reduced.
  • the discharge port 355 is formed in the direction in which the upstream side passage 31A extends from the main intake port 350, the pollutant that flows through the upstream side passage 31A is efficiently transferred to the discharge port 355. Can be shed.
  • the center of the main intake port 350 of the first passage 31 is in the direction D in which the measured gas IA flows in the main passage 124. It is offset with respect to the center line CL along.
  • the pollutant is easily contained in the vicinity of the center line CL of the main passage 124 as compared with other portions, by disposing the center of the main intake port 350 at a position offset from this position, The amount of fouling substances flowing into the sub passage 330 can be reduced.
  • the upstream from the main intake port 350 to the sub intake port 34 (specifically, the upstream opening edge portion 34a) in the first passage 31 in the offset state.
  • the side passage 31A is inclined with respect to the center line CL so as to move away from the center line CL as it proceeds from the main intake port 350 to the sub intake port 34.
  • the thermal flow meter 30 is disposed at such an offset position in this way with respect to the center line CL. Since the gas to be measured IA (arrow ia in the figure) flows along the inclined direction, the main intake port 350 follows the flow (arrow ia in the figure) without obstructing the flow of the gas to be measured IA. It can be taken into the secondary passage 330.
  • the discharge port 355 is out of the projection range R in which the main intake port 350 is projected in the flow direction D of the measurement target gas IA in the main passage 124.
  • the flow that flows in from the main intake port 350 is less likely to go straight toward the discharge port 355.
  • the area of the discharge port 355 is smaller than the area of the main intake port 350. Thereby, the flow which flowed in from the main intake port 350 is restrict
  • the flow rate flowing out from the first passage 31 is suppressed, and the flow rate detection unit 602 is out of the projection range R in which the intake port 350 is projected in the flow direction D of the measurement target gas IA in the main passage 124.
  • a shortage of the flow rate supplied to the flow rate detection unit 602 via the second passage 32 serving as a curved passage is avoided.
  • the upstream opening edge 34 a located on the side is at the same distance as the wall surface 31 b facing the sub intake port 34.
  • the downstream opening edge 34b is formed away from the upstream opening edge 34a with respect to the wall 31b facing the sub intake port 34 among the walls forming the first passage 31. Good.
  • the flow path of the first passage 31 is restricted in the downstream opening edge 34b located on the downstream side of the first passage 31 forming the sub intake port 34. Therefore, the pollutant does not easily collide with the downstream opening edge 34b, and the pollutant from the main intake port 350 easily flows toward the discharge port 355 of the first passage 31.
  • FIG. 7 is a schematic diagram showing a modification of FIG.
  • the wall surface of the upstream passage 31A continuous with the sub intake port 34 has a convex shape along the flow direction of the measured gas IA.
  • the wall surface facing this has a concave shape corresponding to the concave wall surface so as to maintain the channel cross-sectional area.
  • the upstream passage 31A restrains the direction of the flow of the gas to be measured flowing into the upstream passage 31A from the main intake port 350 along the upstream passage 31A, and the first passage 31 and the second passage In the 32 branching portions, the measurement target gas IA can be easily directed to the discharge port 355 side. Therefore, by the same operation as in the first embodiment, the pollutant that reaches the flow rate detection unit 602 can be reduced, and the mass flow measurement error and the abnormal value detection frequency can be reduced. And it can avoid that the flow volume supplied to a flow volume detection part runs short, and the sensitivity of the flow volume detection part 602 can be maintained.
  • FIG. 8 is a schematic diagram showing a modification of FIG.
  • the wall surface of the upstream side passage 31A continuous with the sub intake port 34 has a concave shape along the flow direction of the measured gas IA.
  • the wall surface which opposes this becomes the convex shape corresponding to a convex-shaped wall surface so that a flow-path cross-sectional area may be maintained.
  • the upstream passage 31A restrains the direction of the flow of the gas to be measured flowing into the upstream passage 31A from the main intake port 350 along the upstream passage 31A, and the first passage 31 and the second passage In the 32 branching parts, the flow is kept away from the second passage 32 side so as to be easily directed to the discharge passage 3 side. Therefore, by the same operation as in the first embodiment, the pollutant that reaches the flow rate detection unit can be reduced, and the measurement error of the mass flow rate and the detection frequency of the abnormal value can be reduced. And it can avoid that the flow volume supplied to a flow volume detection part runs short, and can maintain the sensitivity of a flow sensor.
  • FIG. 9 is a schematic diagram showing another modification of FIG. Parts having the same functions corresponding to the first to third embodiments are denoted by the same reference numerals.
  • the second passage 32 is configured such that the flow path turns approximately 360 degrees so that the main intake port 350 faces the flow direction D of the gas 30 to be measured flowing through the main passage 124.
  • the outlet 355 opened toward the upstream side, and the outlet 355 opened toward the downstream side in the fluid flow direction.
  • FIG. 9 is a cross-sectional view showing an example in which the configuration of the second passage 32 is different from the above-described embodiment. In FIG. 9, only the sub-passage portion of the body 1 (housing 302) is shown, and a cross section substantially similar to FIGS. 6 to 8 is shown.
  • the first passage 31 of the present embodiment has an upstream passage 31A communicating with the main intake port 350, and the upstream passage 31A is linear.
  • the upstream passage 31 ⁇ / b> A is provided at a certain angle ⁇ with respect to the flow direction D of the measurement target gas 30 flowing through the main passage 124.
  • the upstream passage from the main intake port 350 to the first passage 31 is linear from the main intake port 350 to the sub intake port 34, and the first Of the passage 31, the upstream passage 31 ⁇ / b> A from the main intake port 350 to the sub intake port 34 is inclined so as to be away from the flow rate detection unit 602 with respect to the flow direction D of the gas to be measured flowing through the main passage. .
  • the center of the main intake port 350 of the first passage 31 is offset with respect to the center line CL along the direction D in which the measured gas IA of the main passage 124 flows (specifically, The intake port 350 is formed at a position deviated from the center line CL), and the upstream passage 31A from the main intake port 350 to the sub intake port 34 (specifically, the upstream end portion) in the first passage 31. Is inclined with respect to the center line CL so as to move away from the center line CL as it proceeds from the main inlet 350 to the sub inlet 34.
  • the second passage 32 is branched from the first passage 31, and the outlet 355 of the first passage 31 is open to a side surface at one end in the thickness direction of the thermal flow meter.
  • the second passage 32 is provided with a flow rate detection unit 602 mounted on the circuit package 400 in the middle thereof.
  • the sub passage 2 is partially bent, and the circuit package 400 and the flow rate detection unit 602 are arranged on the downstream side of the bent portion.
  • the outlet 352 of the second passage 32 opens to the main passage 124 on the tip side of the thermal flow meter. Since the flow rate detection unit 602 is out of the projection range R in which the intake port 350 is projected in the flow direction D of the gas IA to be measured in the main passage 124, the pollutant that has flowed from the main intake port 350 travels straight. There is no contact. Further, the discharge port 355 is out of the projection range R in which the main intake port 350 is projected in the flow direction D of the measurement target gas IA in the main passage 124. As a result, the flow that flows in from the main intake port 350 is less likely to go straight toward the discharge port 355. Furthermore, the area of the discharge port 355 is smaller than the area of the main intake port 350.
  • the upstream-side passage 31 ⁇ / b> A is linear and is provided at a certain angle ⁇ with respect to the (main) flow direction D of the measurement target gas IA flowing through the main passage 124.
  • the upstream passage 31A changes the direction of the flow that flows into the main intake port 350 from the inside, and the flow from the second passage 32 side at the branch portion of the first passage 31 and the second passage 32 is changed. It is easy to face the discharge port 355 side by keeping away.
  • the discharge port 355 is out of the projection range R in which the main intake port 350 is projected in the flow direction D of the measurement target gas IA in the main passage 124.
  • the flow that flows in from the main intake port 350 is less likely to go straight toward the discharge port 355.
  • the area of the discharge port 355 is smaller than the area of the main intake port 350.
  • squeezed by the discharge port 355, and fluid resistance is large. Accordingly, the flow rate flowing out from the first passage 31 is suppressed, and the flow rate detection unit 602 is out of the projection range R in which the intake port 350 is projected in the flow direction D of the measurement target gas IA in the main passage 124.
  • a shortage of the flow rate supplied to the flow rate detection unit 602 via the second passage 32 serving as a curved passage is avoided.
  • the present invention is not limited to the above-described embodiments, and various designs can be made without departing from the spirit of the present invention described in the claims. It can be changed.
  • the above-described embodiment has been described in detail for easy understanding of the present invention, and is not necessarily limited to one having all the configurations described.
  • a part of the configuration of an embodiment can be replaced with the configuration of another embodiment, and the configuration of another embodiment can be added to the configuration of an embodiment.

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  • Physics & Mathematics (AREA)
  • Fluid Mechanics (AREA)
  • General Physics & Mathematics (AREA)
  • Measuring Volume Flow (AREA)

Abstract

Selon l'invention, afin de créer un débitmètre thermique qui est capable d'éliminer les changements au cours du temps des propriétés de détection d'un gaz à mesurer causés par une substance contaminante, même lorsque la substance contaminante entre dans un canal auxiliaire, le canal auxiliaire (330), qui admet une partie du gaz (IA) à mesurer qui circule dans un canal principal (124), comprend : un premier canal (31) formé de façon à admettre le gaz (IA) à mesurer qui circule dans le canal principal (124), et formé entre un orifice d'admission principal (350) qui est orienté vers l'amont dans le canal principal (124) et l'orifice de refoulement (355) qui refoule une partie du gaz (IA) à mesurer qui a été admis ; et un deuxième canal (602) formé vers une unité de détection de débit (602) à partir d'un orifice d'admission auxiliaire (34) permettant d'admettre le gaz (IA) à mesurer qui circule dans le premier canal (31). Le canal côté amont (31) entre l'orifice d'admission principal (31) et l'orifice d'admission auxiliaire (34) dans le premier canal (350) est incliné de façon à s'éloigner d'une unité de détection de débit (602) par rapport à la direction d'écoulement (D) du gaz (IA) à mesurer qui circule dans le canal principal (124). L'unité de détection de débit (602) et l'orifice de refoulement (355) sont séparés dans la direction d'écoulement (D) du gaz (IA) à mesurer dans le canal principal (124) à partir d'une portée de saillie (R) où l'orifice d'admission principal est en saillie. L'aire surfacique de l'orifice de refoulement (355) est plus petite que l'aire surfacique de l'orifice d'admission principal (350).
PCT/JP2014/052604 2013-09-30 2014-02-05 Débitmètre thermique WO2015045435A1 (fr)

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JP2017067611A (ja) * 2015-09-30 2017-04-06 日立オートモティブシステムズ株式会社 熱式流量計
WO2017073417A1 (fr) * 2015-10-28 2017-05-04 日立オートモティブシステムズ株式会社 Débitmètre thermique
JP2017215192A (ja) * 2016-05-31 2017-12-07 日立オートモティブシステムズ株式会社 熱式流量計
WO2017212801A1 (fr) * 2016-06-07 2017-12-14 日立オートモティブシステムズ株式会社 Débitmètre thermique
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JP6658659B2 (ja) * 2017-04-13 2020-03-04 株式会社デンソー 物理量計測装置
DE112019000711T9 (de) 2018-02-07 2021-01-07 Denso Corporation Vorrichtung zur Messung einer physikalischen Größe
JP2019138707A (ja) 2018-02-07 2019-08-22 株式会社デンソー 物理量計測装置

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JP2017067611A (ja) * 2015-09-30 2017-04-06 日立オートモティブシステムズ株式会社 熱式流量計
WO2017073417A1 (fr) * 2015-10-28 2017-05-04 日立オートモティブシステムズ株式会社 Débitmètre thermique
JP2017083304A (ja) * 2015-10-28 2017-05-18 日立オートモティブシステムズ株式会社 熱式流量計
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JPWO2017212801A1 (ja) * 2016-06-07 2019-02-21 日立オートモティブシステムズ株式会社 熱式流量計
WO2017212801A1 (fr) * 2016-06-07 2017-12-14 日立オートモティブシステムズ株式会社 Débitmètre thermique
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CN109073432A (zh) * 2016-06-24 2018-12-21 日立汽车系统株式会社 热式流量计
JPWO2017221680A1 (ja) * 2016-06-24 2019-01-24 日立オートモティブシステムズ株式会社 熱式流量計
WO2017221680A1 (fr) * 2016-06-24 2017-12-28 日立オートモティブシステムズ株式会社 Débitmètre thermique
US10942050B2 (en) 2016-06-24 2021-03-09 Hitachi Automotive Systems, Ltd. Thermal flowmeter

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