Sensor unit and intake system of internal combustion engine

Abstract

To provide a sensor unit and an intake system of an internal combustion engine capable of generating a flow of intake air positively in a passage from a detection unit of a sensor to an intake passage, to suppress or prevent freezing of liquid or liquid substance such as fuel, moisture and blow-by gas, and capable of detecting state quantities (pressure, temperature) of the intake air with high accuracy.SOLUTION: A sensor unit is arranged in an intake pipe of an internal combustion engine, and includes: sensors 30, 40 for detecting state quantities of intake air flowing through an intake passage Ip1 defined by the intake pipe, and a case Ca for housing the sensors. The case Ca includes a first passage 24 and a second passage 25 that communicate with each other and each open into the intake passage so as to expose detection units Rc, 41 of the sensors to the intake air flowing through the intake passage, and a collision wall 26a that collides the intake air flowing through the intake passage near the opening of the second passage.SELECTED DRAWING: Figure 12

Description

Technical Field

[0001] The present invention relates to a sensor unit that is applied to an intake system of an internal combustion engine mounted on an automobile, a motorcycle, or other vehicles, etc., and detects intake state quantities (pressure, temperature), and an intake system of an internal combustion engine.

Background Art

[0002] As a conventional sensor unit, there is known a temperature sensor integrated pressure sensor device including a case into which a terminal is inserted, a pressure detection element connected to the terminal and disposed in the case, a port portion connected to the case and having one pressure introduction hole leading to a pressure receiving chamber of the pressure detection element, and a temperature detection element connected to the terminal and provided at the tip of the port portion (for example, Patent Document 1, Patent Document 2).

[0003] In the above temperature sensor integrated pressure sensor device, the pressure introduction hole formed in the port portion is formed as one linear passage having a relatively large passage area. Therefore, when foreign matter exists in the intake manifold, there is a risk that the foreign matter may enter the pressure receiving chamber through the pressure introduction hole and the intake pressure cannot be accurately detected.

[0004] As another sensor unit, there is known a pressure sensor device including a sensor housing container composed of a base and a box-shaped housing, a pressure detection element disposed in the housing, a pressure introduction path formed by the base and a pipe and leading to a pressure introduction chamber of the pressure detection element, a temperature sensor disposed in a temperature sensor housing protrusion formed in the base, and a circuit board on which the pressure detection element and the temperature sensor are electrically connected and disposed in the housing (for example, Patent Document 3).

[0005] In the above pressure sensor device, in order to suppress foreign matter from entering the pressure introduction chamber through the pressure introduction passage, a labyrinth structure with a reduced passage area is formed in the pressure introduction passage near its open end. Therefore, in the region of this labyrinth structure, liquids such as fuel due to blowback, moisture in the intake air, blow-by gas, etc., or liquid substances may adhere to the passage or freeze during cold conditions, further narrowing or blocking the passage, and there is a risk that the intake pressure cannot be accurately detected.

Prior Art Documents

Patent Documents

[0006]

Patent Document 1

Patent Document 2

Patent Document 3

Summary of the Invention

Problems to be Solved by the Invention

[0007] The present invention has been made in view of the above circumstances, and its object is to actively generate an intake air flow in the passage leading from the detection part of the sensor to the intake passage, suppress or prevent the adhesion or freezing of liquids or liquid substances such as fuel, moisture in the intake air, blow-by gas, etc., and provide a sensor unit and an intake system for an internal combustion engine that can accurately detect the state quantity of the intake air.

Means for Solving the Problems

[0008] The sensor unit of the present invention is a sensor unit disposed in the intake pipe of an internal combustion engine, and includes a sensor for detecting a state quantity of intake air flowing through an intake passage defined by the intake pipe, and a case for housing the sensor. The case includes a first passage and a second passage that communicate with each other to expose the detection part of the sensor to the intake air flowing through the intake passage and open to the intake passage respectively, and a collision wall that collides the intake air flowing through the intake passage in the vicinity of the opening of the second passage.

[0009] In the above sensor unit, the collision wall may adopt a configuration including a guiding part that guides the intake air flowing through the intake passage toward the inside of the second passage.

[0010] In the above sensor unit, the guiding part may adopt a configuration including a curved surface that inclines toward the inside of the second passage.

[0011] In the above sensor unit, the guiding part may adopt a configuration including side surfaces continuously formed on both sides of the curved surface.

[0012] In the above sensor unit, the first passage may have a first opening that opens at a first end surface that is away from the inner wall surface of the intake pipe toward the central side, and the second passage may have a second opening that opens at a second end surface closer to the inner wall surface of the intake pipe than the first opening.

[0013] In the above sensor unit, the case may include a sleeve that extends in a predetermined axial direction. The sleeve includes a partition wall that defines the first passage and the second passage to extend adjacent to each other, and the partition wall includes the collision wall.

[0014] In the above sensor unit, the sensor may include a pressure sensor for detecting the pressure of the intake air and a temperature sensor for detecting the temperature of the intake air. The case may include a case body for housing the temperature sensor and the pressure sensor, and a sleeve that is joined to the case body and defines the first passage, the second passage, and the collision wall.

[0015] In the above sensor unit, the first passage and the second passage may be configured to extend from the region facing the detection part of the temperature sensor to the intake passage, and the detection part of the pressure sensor may be configured to face the middle of the second passage.

[0016] In the above sensor unit, the case body may include a recess exposing the detection part of the temperature sensor, and the sleeve may include a protruding wall inserted into the recess to cooperate with the recess to define a part of the first passage and the second passage.

[0017] In the above sensor unit, the second passage may include a bent passage between the region facing the detection part of the pressure sensor and the region facing the detection part of the temperature sensor, and the first passage may include a bent passage on the way to the first opening opening to the intake passage from the region facing the detection part of the temperature sensor.

[0018] In the above sensor unit, the first passage and the second passage may be configured to include a bent passage formed by three-dimensionally bending.

[0019] In the above sensor unit, the bent passage may be configured such that its inner wall surface is curved to be streamline continuous.

[0020] In the above sensor unit, the detection part of the pressure sensor may include a pressure receiving chamber exposed to the intake air, and the pressure receiving chamber may be configured to communicate with the second passage through a communication hole having an opening area smaller than the cross-sectional area of the second passage.

[0021] In the above sensor unit, the communication hole may be arranged to face the second opening of the second passage opening to the intake passage in the extending direction of the second passage.

[0022] In the above sensor unit, a configuration including a circuit board in which the pressure sensor and the temperature sensor are electrically connected and housed in the case body may be adopted.

[0023] In the above sensor unit, the temperature sensor may adopt a configuration in which it is a surface-mounted temperature sensor mounted on a circuit board.

[0024] In the above sensor unit, the case may adopt a configuration including a case body having a joint surface joined to the intake pipe, a sleeve protruding from the case body in a predetermined axial direction and defining a first passage, a second passage, and a collision wall, and an annular groove formed on the outer periphery of the sleeve into which an annular seal member is fitted.

[0025] In the above sensor unit, the sleeve may adopt a configuration including a large-diameter cylindrical portion protruding from the joint surface and a small-diameter cylindrical portion continuous with the large-diameter cylindrical portion, and the annular groove is formed in the large-diameter cylindrical portion.

[0026] The intake system of the internal combustion engine of the present invention includes an intake pipe defining an intake passage for guiding intake air to a combustion chamber of the internal combustion engine, a fuel injection valve for injecting fuel into the intake passage or the combustion chamber in the middle of the intake passage, a throttle device interposed in the middle of the intake pipe for opening and closing the intake passage, and a sensor unit for detecting a state quantity of the intake air flowing through the intake passage. As the sensor unit, any of the sensor units having the above configuration is adopted.

[0027] In the intake system of the above internal combustion engine, the sensor unit may adopt a configuration in which it is arranged in the intake pipe on the downstream side of the throttle device.

Effects of the Invention

[0028] According to the sensor unit having the above configuration, an intake air flow is actively generated in the passage leading from the detection part of the sensor to the intake passage, and adhesion or freezing of liquids or liquid-like substances such as fuel, moisture in the intake air, and blow-by gas can be suppressed or prevented, and the state quantity (pressure, temperature) of the intake air can be detected with high accuracy.

Brief Description of the Drawings

[0029]

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Mode for Carrying Out the Invention

[0030] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. The sensor unit U of the present invention is incorporated into, for example, an intake system of an internal combustion engine E mounted on a vehicle such as an automobile or a motorcycle. The internal combustion engine E includes a cylinder block 1, a piston 2, a cylinder head 3, an intake valve 4a for opening and closing an intake port 3a, an exhaust valve 4b for opening and closing an exhaust port 3b, a spark plug 5, a cam mechanism 6 for driving the intake valve 4a and the exhaust valve 4b, and the like.

[0031] The intake system of the internal combustion engine E includes an intake pipe Ip connected to the cylinder head 3 so as to communicate with the intake port 3a, a throttle device M connected in the middle of the intake pipe Ip, an air cleaner Ac connected to the upstream end of the intake pipe Ip, a fuel injection valve Iv disposed on the downstream side of the intake pipe Ip, and a sensor unit U disposed in the intake pipe Ip on the downstream side of the throttle device M and on the upstream side of the fuel injection valve Iv.

[0032] The intake pipe Ip defines an intake passage Ip1 for guiding intake air to the combustion chamber C of the internal combustion engine E. The throttle device M includes a butterfly-type throttle valve m1 for opening and closing the intake passage Ip1, a bypass passage m2 for bypassing the throttle valve m1, and the like. The exhaust system of the internal combustion engine E includes an exhaust pipe Ep connected to the cylinder head 3 so as to communicate with the exhaust port 3b, a catalytic converter Cc disposed in the middle of the exhaust pipe Ep, an oxygen sensor Os, and the like.

[0033] As shown in FIGS. 2 to 12, the sensor unit U according to the first embodiment includes a case body 10 as a case Ca, a sleeve 20 extending in the direction of axis S, a pressure sensor 30, a temperature sensor 40, a circuit board 50, a plurality of terminals 60, and a mold resin material 70.

[0034] The case body 10 is formed by using a resin material, and includes a joint surface 11 that forms a part of the joint surface Ca1 of the case Ca, a fitting recess 12, a recess 13, accommodating portions 14 and 15, a flange portion 16, and a connector 17.

[0035] As shown in FIG. 3, the joint surface 11 is formed as a flat surface to be joined to the outer wall of the intake pipe Ip. The fitting recess 12 is a region where the sleeve 20 is fitted and joined, is formed as an annular recess, and has a positioning cutout portion 12a at a part of its inner peripheral surface. The recess 13 is formed so as to be recessed in a substantially rectangular shape from the bottom surface 12b of the fitting recess 12. The protruding wall 27 of the sleeve 20 is inserted therein, and the detection portion 41 of the temperature sensor 40 is defined continuously on its bottom surface 13a. The accommodating portion 14 is a region for accommodating and holding the pressure sensor 30, and is formed in a region adjacent to the bottom surface 12b of the fitting recess 12. The accommodating portion 15 is a region for accommodating and holding the circuit board 50, and is formed in a region on the side opposite to the joint surface 11. The flange portion 16 defines a part of the joint surface 11 and has a circular hole 16a through which a fastening screw (not shown) to be screwed into the screw hole of the intake pipe Ip passes. The connector 17 protrudes in a direction perpendicular to the axis S, exposes and surrounds a plurality (here, four) of terminals 60 connected to the circuit board 50, and is formed to be connected to the outside.

[0036] The sleeve 20 is formed using a resin material, is formed in a cylindrical shape extending in the axial direction S, and includes a fitting portion 21, a large-diameter cylindrical portion 22, a small-diameter cylindrical portion 23, a first passage 24, a second passage 25, a partition wall 26 partitioning the first passage 24 and the second passage 25, and a protruding wall 27 protruding in the axial direction S from the fitting portion 21.

[0037] The fitting portion 21 is formed in a disc shape and includes a positioning projection 21a formed on a part of its outer periphery, an annular joint surface 21b flush with the joint surface 11 to form a part of the joint surface Ca1, and an end surface 21c in close contact with the bottom surface 12b of the fitting recess 12 of the case body 10. When the fitting portion 21 is closely fitted into the fitting recess 12 of the case body 10, the sleeve 20 is joined to the case body 10 to define the case Ca.

[0038] The large-diameter cylindrical portion 22 is a region fitted into the fitting hole H of the intake pipe Ip, protrudes from the joint surface 21b of the fitting portion 21, and has an annular groove 22a formed on its outer periphery for fitting an annular seal member Sr. The annular seal member Sr is formed in an annular shape using a rubber material excellent in heat resistance, swelling resistance, etc., and is fitted into the annular groove 22a. As shown in FIG. 3, the annular seal member Sr seals between the fitting hole H of the intake pipe Ip and the sleeve 20 in a state where the sensor unit U is assembled to the intake pipe Ip. The small-diameter cylindrical portion 23 is continuously formed with the large-diameter cylindrical portion 22 and is a region protruding into the intake passage Ip1 in a state of being joined to the intake pipe Ip. Further, the small-diameter cylindrical portion 23 includes a first end surface 23a defining the first opening 24a of the first passage 24 on the tip side in the axial direction S, and a second end surface 23b defining the second opening 25a of the second passage 25 closer to the large-diameter cylindrical portion 22 than the first end surface 23a.

[0039] Then, with the sensor unit U attached to the intake pipe Ip, as shown in FIG. 3, the first end face 23a and the first opening 24a are positioned closer to the center of the intake passage Ip1 from the inner wall surface W of the intake pipe Ip, and the second end face 23b and the second opening 25a are positioned closer to the inner wall surface W of the intake pipe Ip than the first end face 23a.

[0040] The first passage 24 is formed to extend in the axial direction S from the region At (the recess 13 into which the protruding wall 27 is inserted) facing the detection part 41 of the temperature sensor 40 to the first opening 24a opening at the first end face 23a so as to expose the detection part of the sensor to the intake air flowing through the intake passage Ip1. Also, as shown in FIGS. 7 and 10, the first passage 24 includes a bent passage 24b defined by a bent inner wall surface in the middle of the path from the region At facing the detection part 41 of the temperature sensor 40 to the first opening 24a. As shown in FIGS. 6 and 9, the bent passage 24b is formed to be bent two-dimensionally in the XY plane.

[0041] The second passage 25 is formed to extend in the axial direction S from the region At (the recess 13 into which the protruding wall 27 is inserted) facing the detection part 41 of the temperature sensor 40 to the second opening 25a opening at the second end face 23b so as to expose the detection part of the sensor to the intake air flowing through the intake passage Ip1. Also, as shown in FIG. 8, the second passage 25 extends linearly along the straight line L in the axial direction S from the second opening 25a to the region Ap facing the detection part (pressure receiving chamber Rc) of the pressure sensor 30, and as shown in FIG. 9, between the region Ap facing the detection part (pressure receiving chamber Rc) of the pressure sensor 30 and the region At facing the detection part 41 of the temperature sensor 40, it includes a bent passage 25b defined by a bent inner wall surface. As shown in FIGS. 7 and 10, the bent passage 25b is formed to be bent two-dimensionally in the XZ plane.

[0042] That is, the first passage 24 and the second passage 25 communicate with each other in the region At facing the detection unit 41 of the pressure sensor 30 and open to the intake passage Ip1 respectively. Also, in the range extending from the region Ap facing the detection unit (pressure receiving chamber Rc) of the pressure sensor 30 to the region At facing the detection unit 41 of the temperature sensor 40 and covering the region in the middle of the first passage 24, as shown in FIG. 11, it is formed to include the bent passages 24b and 25b formed by being bent three-dimensionally. In this way, by including the bent passages 24b and 25b bent three-dimensionally, compared with the case where the two passages as the first passage and the second passage are formed as passages bent two-dimensionally, the two passages (the first passage 24 and the second passage 25) can be concentrated and arranged closer to the center, and the reduction of the diameter and the miniaturization of the sleeve 20 can be achieved.

[0043] The partition wall 26 extends in the direction of the axis S and partitions the first passage 24 and the second passage 25, and is formed to include a collision wall 26a in the vicinity of the second opening 25a on the tip side in the direction of the axis S. As shown in FIG. 3, the collision wall 26a is formed as a flat surface arranged toward the upstream side of the intake passage Ip1 so as to collide the intake air flowing through the intake passage Ip1 in the state where the sensor unit U is attached to the intake pipe Ip. In this way, by forming a part of the partition wall 26 to also serve as the collision wall 26a, the shape of the sleeve 20 can be simplified compared with the configuration in which a separate collision wall following the second opening is provided.

[0044] The protruding wall 27 is formed as a substantially rectangular piece protruding in the direction of the axis S from the end face 21c of the fitting portion 21. And in the state where the sleeve 20 is joined to the case body 10, the protruding wall 27 is inserted into the recess 13 of the case body 10, partially bisects the region At in the recess 13, and cooperates with the recess 13 to define a part of the first passage 24 and a part of the second passage 25. In this way, by inserting the protruding wall 27 into the recess 13 to define a part of the first passage 24 and a part of the second passage 25, the shape of the recess 13 of the case body 10 can be simplified, and the mold release becomes easier when molding the case body 10.

[0045] As shown in FIGS. 4, 5, 8, and 11, the pressure sensor 30 is composed of a sensor main body portion 31 and a sensor cover 32. The sensor main body portion 31 includes a pressure receiving portion 31a such as a diaphragm provided with a semiconductor strain gauge, a lead wire 31b extending from the pressure receiving portion 31a, an annular portion 31c surrounding the pressure receiving portion 31a, and the like. The sensor cover 32 includes a disc-shaped bottom portion 32a, an annular outer wall portion 32b, and a communication hole 32c. The communication hole 32c is formed as a circular hole having an opening area smaller than the passage area of the second passage 25. Then, the sensor cover 32 functions as a protective cover covering the pressure receiving portion 31a and defines a pressure receiving chamber Rc as a detection portion. The annular portion 31c is fitted into the annular outer wall portion 32b and connected to the sensor main body portion 31.

[0046] Then, the pressure sensor 30 outputs, as an electrical signal, a change in electrical resistance corresponding to the amount of deformation generated in the pressure receiving portion 31a due to the pressure of the intake air introduced into the pressure receiving chamber Rc through the communication hole 32c. Here, the pressure receiving chamber Rc as the detection portion of the pressure sensor 30 is formed so as to face the middle of the second passage 25 through the communication hole 32c. Further, as shown in FIG. 8, the communication hole 32c is arranged so as to face, on a straight line L, that is, in the extending direction of the second passage 25, the second opening portion 25a of the second passage 25 that opens into the intake passage Ip1. The above pressure sensor 30 is configured to detect the pressure of the intake air flowing through the intake passage Ip1 on the downstream side of the throttle device M in a state where the sensor unit U is assembled to the intake pipe Ip.

[0047] In this way, by communicating the pressure receiving chamber Rc to the second passage 25 through the communication hole 32c, it is possible to prevent foreign matters or the like mixed in the intake air from entering the pressure receiving chamber Rc. Further, since the communication hole 32c is arranged so as to face the second opening 25a of the second passage 25 on the straight line L, it is possible to actively guide the intake air flowing in from the second opening 25a to the pressure receiving chamber Rc while suppressing the passage resistance.

[0048] The temperature sensor 40 is a surface-mounted temperature sensor forming a semiconductor chip. As shown in FIG. 5, it is surface-mounted on the circuit board 50. In a state where the circuit board 50 is housed in the housing portion 15, as shown in FIGS. 8, 10, and 11, it includes a detection portion 41 defined adjacent to the bottom surface 13a of the recess 13. The detection portion 41 is exposed to the intake air flowing through the intake passage Ip1 through the first passage 24 and the second passage 25 in the region of the recess 13. The above temperature sensor 40 is configured to detect the temperature of the intake air flowing through the intake passage Ip1 on the downstream side of the throttle device M in a state where the sensor unit U is assembled to the intake pipe Ip. In this way, by using a surface-mounted temperature sensor as the temperature sensor 40, it is possible to achieve miniaturization of the sleeve 20, integration and miniaturization of components in the case Ca.

[0049] The circuit board 50 has printed wiring and various electronic components (not shown) surface-mounted thereon. As shown in FIGS. 4 and 5, it includes three through-holes 51 to which the lead wires 31b of the pressure sensor 30 are electrically connected, and four through-holes 52 to which four terminals 60 are electrically connected. Then, at the time of assembly, the circuit board 50 is arranged in the housing portion 15 of the case body 10, the lead wires 31b and the terminals 60 are electrically connected, and then it is covered and sealed with the mold resin material 70.

[0050] The terminal 60 is formed of a conductive metal material. As shown in FIGS. 4 and 9, it is embedded in the case body 10, one end is connected to the through hole 52 of the circuit board 50, and the free end side is exposed in the connector 17 and is arranged so as to be surrounded by the connector 17.

[0051] The mold resin material 70 is a sealing material such as an epoxy resin. The circuit board 50 on which the pressure sensor 30, the temperature sensor 40, and other electronic components (not shown) are mounted is respectively accommodated and held in the accommodation portions 14 and 15 of the case body 10, and is injected into the case body 10 so as to fill the gap space and solidified.

[0052] Next, in the sensor unit U having the above configuration, the principle that the detection portions of the sensors (the pressure receiving chamber Rc of the pressure sensor 30 and the detection portion 41 of the temperature sensor 40) are exposed to the intake air flowing through the intake passage Ip1 via the first passage 24 and the second passage 25 will be described. In the intake air flowing through the intake passage Ip1, when it is not at an ultra-high speed, Bernoulli's theorem of kinetic energy + pressure energy + potential energy = constant can be approximately used as a non-viscous and incompressible fluid.

[0053] Specifically, when the density of the fluid is ρ (kg / m 3 ), the flow velocity is V (m / s), the pressure is P (pa), the gravitational acceleration is g (m / s2), and the height position is Z, it is expressed as ρV 2 / 2 + P + ρgZ = constant. In the flow of the intake air in the intake pipe Ip, the potential energy can be ignored, so it can be approximated as ρV 2 / 2 + P = constant. That is, in the intake passage Ip1, when the flow velocity V increases (becomes faster), the pressure P decreases (becomes lower), and when the flow velocity V decreases (becomes slower), the pressure P increases (becomes higher).

[0054] Here, when the collision wall 26a is arranged parallel to the intake air flow direction and the sensor unit U is attached to the intake pipe Ip, the intake air flowing through the intake passage Ip1 does not collide with the collision wall 26a. In this case, between the pressure P1 in the vicinity of the first opening 24a (first end face 23a) of the first passage 24 and the pressure P2 in the vicinity of the second opening 25a (second end face 23b) of the second passage 25, there is a pressure difference ΔPo (= P2 - P1 = (V1 2 - V2 2 ) / 2) holds.

[0055] On the other hand, as shown in FIG. 3, when the sensor unit U is attached to the intake pipe Ip with the collision wall 26a facing the upstream side of the intake air flow so that the intake air flowing through the intake passage Ip1 collides with the collision wall 26a, in the vicinity of the second opening 25a, a stagnant region Sa where the intake air collides with the collision wall 26a and the velocity of the intake air becomes zero (V2 = 0) is generated. Therefore, as shown in FIG. 12, the pressure difference between the vicinity of the second opening 25a where the stagnant region Sa is generated and the vicinity of the first opening 24a is ΔPa = P2 - P1 = V1 2 / 2. That is, the relationship ΔPa > ΔPo holds. And due to the pressure difference ΔPa, the intake air flowing through the intake passage Ip1 flows into the second passage 25 from the second opening 25a, passes through the region Ap facing the detection part (pressure receiving chamber Rc) of the pressure sensor 30 and the region At facing the detection part 41 of the temperature sensor 40, flows through the first passage 24, and flows out again into the intake passage Ip1 from the first opening 24a.

[0056] Thereby, in the sensor unit U, due to the intake air flow occurring in the first passage 24 and the second passage 25, it is possible to suppress or prevent liquids or liquid substances such as fuel, moisture in the intake air, and blow-by gas from adhering to the inside of the passages, and it is also possible to prevent freezing of the adherents. Therefore, the pressure sensor 30 can accurately detect the pressure of the intake air led to the detection part (pressure receiving chamber Rc), and the temperature sensor 40 can accurately detect the temperature of the intake air led to the detection part 41.

[0057] Here, since the detection part (pressure receiving chamber Rc) of the pressure sensor 30 communicates with the second passage 25 through the communication hole 32c having an opening area smaller than the passage area of the second passage 25, it is possible to prevent foreign matters or the like mixed in the intake air from entering the pressure receiving chamber Rc. Further, even when the temperature sensor 40 is mounted on the circuit board 50 and the detection part 41 is disposed on the inner side of the case Ca, since the second passage 25 and the first passage 24 communicate with the region At facing the detection part 41, the intake air flowing through the intake passage Ip1 can be guided to the region At, and the detection part 41 can be surely exposed to the intake air.

[0058] Next, in the internal combustion engine E provided with the sensor unit U, the detection operation of the sensor unit U will be described. First, when the internal combustion engine E is in the idle operation region, the throttle valve m1 is in a state of closing the intake passage Ip1, and the intake air flowing through the intake passage Ip1 flows through the bypass passage m2 so as to bypass the throttle valve m1 and then flows out again to the downstream intake passage Ip1. On the other hand, when the internal combustion engine E is in an operation region other than the idle operation region, the throttle valve m1 is within a predetermined opening range, and the intake passage Ip1 is in an open state. Therefore, the intake air flowing through the intake passage Ip1 flows through the intake passage Ip1 without passing through the bypass passage m2 and is sucked into the internal combustion engine E.

[0059] Then, in the operation state of the internal combustion engine E, the pressure sensor 30 detects the pressure and temperature, which are the state quantities of the intake air, on the downstream side of the throttle device M. That is, the pressure sensor 30 detects the pressure of the intake air flowing through the intake passage Ip1 through the second passage 25 and the communication hole 32c. Further, the communication hole 32c can prevent foreign matters or the like from entering the pressure receiving chamber Rc.

[0060] Also, the temperature sensor 40 detects the temperature of the intake air in the region At where the second passage 25 makes a U-turn toward the first passage 24. In this way, the intake pressure is detected by the pressure sensor 30, the intake temperature is detected by the temperature sensor 40, and the detected information is taken in as control information for the ECU, and the internal combustion engine E is appropriately controlled.

[0061] As described above, the sensor unit U includes sensors (pressure sensor 30 and temperature sensor 40) that detect the state quantity of the intake air flowing through the intake passage Ip1 defined by the intake pipe Ip, and a case Ca that houses the sensors. The case Ca has a first passage 24 and a second passage 25 that communicate with each other to expose the detection parts (pressure receiving chamber Rc, detection part 41) of the sensors to the intake air flowing through the intake passage Ip1 and open to the intake passage Ip1 respectively, and a configuration including a collision wall 26a that collides the intake air flowing through the intake passage Ip1 in the vicinity of the opening of the second passage 25.

[0062] According to this, a pressure difference ΔPa is generated between the vicinity of the first opening 24a of the first passage 24 and the vicinity of the second opening 25a of the second passage 25, and the intake air flowing through the intake passage Ip1 can cause a continuous flow of intake air, flowing in from the second opening 25a, flowing from the second passage 25 to the first passage 24, and flowing out from the first opening 24a to the intake passage Ip1. Therefore, in the region Ap facing the detection part (pressure receiving chamber Rc) of the pressure sensor 30 and the region At facing the detection part 41 of the temperature sensor 40, it is possible to suppress or prevent the occurrence of stagnation in the intake air flow. Therefore, the intake air flow can be actively generated in the passages (first passage 24 and second passage 25) communicating from the detection parts (pressure receiving chamber Rc, detection part 41) of the sensors (pressure sensor 30 and temperature sensor 40) to the intake passage Ip1, and the adhesion or freezing of liquids or liquid-like substances such as fuel, moisture in the intake air, and blow-by gas can be suppressed or prevented, and the state quantities (pressure, temperature) of the intake air can be detected with high accuracy by the sensors (pressure sensor 30 and temperature sensor 40).

[0063] Figures 13 to 18 show the sensor unit U according to the second embodiment. Since the sensor unit U according to the second embodiment has the same configuration as the sensor unit U according to the first embodiment except that the sleeve 20 is changed to a sleeve 120, the same components are denoted by the same reference numerals and the description thereof is omitted.

[0064] The sensor unit U according to the second embodiment includes a case body 10 as a case Ca, a sleeve 120 extending in the direction of the axis S, a pressure sensor 30, a temperature sensor 40, a circuit board 50, a plurality of terminals 60, and a molded resin material 70. The sleeve 120 is formed using a resin material, is formed in a cylindrical shape extending in the direction of the axis S, and includes a fitting portion 21, a large-diameter cylindrical portion 22, a small-diameter cylindrical portion 23, a first passage 24, a second passage 25, a partition wall 126 partitioning the first passage 24 and the second passage 25, and a protruding wall 27 protruding in the direction of the axis S from the fitting portion 21.

[0065] The partition wall 126 extends in the direction of the axis S to partition the first passage 24 and the second passage 25, and is formed to include a collision wall 126a in the vicinity of the second opening 25a on the tip side in the direction of the axis S. As shown in FIG. 14, the collision wall 126a is disposed toward the upstream side of the intake passage Ip1 so as to collide with the intake flowing through the intake passage Ip1 in a state where the sensor unit U is attached to the intake pipe Ip, and is formed as a curved surface inclined toward the second passage 25. Therefore, the collision wall 126a functions as a guide portion for guiding the intake flowing through the intake passage Ip1 toward the second passage 25. Here, although the entire collision wall 126a is formed as a curved surface, it may be formed to partially include a curved surface.

[0066] Then, as shown in FIG. 18, when the sensor unit U is attached to the intake pipe Ip with the collision wall 126a facing the upstream side of the intake flow so that the intake flowing through the intake passage Ip1 collides with the collision wall 126a, the amount of intake flowing into the second passage 25 from the second opening 25a increases as compared with the first embodiment shown in FIG. 12. As a result, the pressure difference ΔPb between the vicinity of the second opening 25a and the vicinity of the first opening 24a becomes larger than the pressure difference ΔPa in the first embodiment. That is, the relationship of ΔPb > ΔPa > ΔPo holds. And due to the pressure difference ΔPb, the intake air flowing from the intake passage Ip1 into the second passage 25 increases compared to the first embodiment.

[0067] Thereby, in the sensor unit U, when an intake air flow occurs in the first passage 24 and the second passage 25, it is possible to suppress or prevent liquids or liquid substances such as fuel, moisture in the intake air, and blow-by gas from adhering to the passages, and it is also possible to prevent freezing of the deposits. Therefore, the pressure sensor 30 can accurately detect the pressure of the intake air guided to the detection part (pressure receiving chamber Rc), and the temperature sensor 40 can accurately detect the temperature of the intake air guided to the detection part 41.

[0068] FIG. 19 shows a sensor unit U according to the third embodiment. The sensor unit U according to the third embodiment is obtained by partially modifying the sleeve 120 of the sensor unit U according to the second embodiment, and the same components are denoted by the same reference numerals and the description thereof is omitted. The sleeve 120 of the sensor unit U according to the third embodiment is formed such that the partition wall 126 partitioning the first passage 24 and the second passage 25 includes side surfaces 126b continuously formed on both sides of the curved surface as the collision wall 126a. The side surface 126b functions as a guide part for guiding the intake air flowing through the intake passage Ip1 into the second passage 25 together with the curved surface of the collision wall 126a.

[0069] According to the third embodiment, after the intake air flowing through the intake passage Ip1 collides with the collision wall 126a, the flow rate from the periphery of the collision wall 126a toward the downstream side of the intake passage Ip1 is suppressed by the side surface 126b, and the flow rate flowing into the second opening 25a increases. As a result, similarly to the above, by causing an intake air flow in the first passage 24 and the second passage 25, it is possible to suppress or prevent liquids or liquid substances such as fuel, moisture in the intake air, and blow-by gas from adhering to the passages, and it is also possible to prevent freezing of the deposits. Therefore, the pressure sensor 30 can accurately detect the pressure of the intake air guided to the detection part (pressure receiving chamber Rc), and the temperature sensor 40 can accurately detect the temperature of the intake air guided to the detection part 41.

[0070] Figs. 20 to 25 show the sensor unit U according to the fourth embodiment. Since the sensor unit U according to the fourth embodiment has the same configuration as the sensor unit U according to the second embodiment except that the sleeve 120 is changed to the sleeve 220, the same components are denoted by the same reference numerals and the description thereof is omitted.

[0071] The sensor unit U according to the fourth embodiment includes a case body 10 as a case Ca, a sleeve 220 extending in the direction of the axis S, a pressure sensor 30, a temperature sensor 40, a circuit board 50, a plurality of terminals 60, and a mold resin material 70. The sleeve 220 is formed by molding using a resin material, is formed in a cylindrical shape extending in the direction of the axis S, and includes a fitting portion 21, a large-diameter cylindrical portion 22, a small-diameter cylindrical portion 23, a first passage 224, a second passage 225, a partition wall 126 partitioning the first passage 24 and the second passage 25, and a protruding wall 27 protruding in the direction of the axis S from the fitting portion 21.

[0072] The first passage 224 is formed to extend in the direction of the axis S from a region At (recess 13 into which the protruding wall 27 is inserted) facing the detection part 41 of the temperature sensor 40 to a first opening 224a that opens at the first end face 23a so as to expose the detection part of the sensor to the intake air flowing through the intake passage Ip1. Further, as shown in Figs. 21 and 23, the first passage 224 includes a bent passage 224b defined by a bent inner wall surface 224b1 on the way from the region At facing the detection part 41 of the temperature sensor 40 toward the first opening 224a. As shown in FIG. 21, the bent passage 224b bends two-dimensionally in the XY plane, and its inner wall surface 224b1 is formed to be curved so as to be streamline continuous.

[0073] The second passage 225 is formed to extend in the axial direction S from a region At (a recess 13 into which the protruding wall 27 is inserted) facing the detection part 41 of the temperature sensor 40 to a second opening 225a that opens at the second end surface 23b so as to expose the detection part of the sensor to the intake air flowing through the intake passage Ip1. Also, as shown in FIG. 22, the second passage 225 linearly extends along a straight line L in the axial direction S from the second opening 225a to a region Ap facing the detection part (pressure receiving chamber Rc) of the pressure sensor 30, and has a bent passage 225b defined by a bent inner wall surface 225b1 between the region Ap facing the detection part (pressure receiving chamber Rc) of the pressure sensor 30 and the region At facing the detection part 41 of the temperature sensor 40. As shown in FIG. 20, the bent passage 225b bends two-dimensionally in the XZ plane, and its inner wall surface 225b1 is formed to be curved so as to be streamline continuous.

[0074] That is, the first passage 224 and the second passage 225 communicate with each other in the region At facing the detection part 41 of the pressure sensor 30 and open to the intake passage Ip1 respectively, and in the range extending from the region Ap facing the detection part (pressure receiving chamber Rc) of the pressure sensor 30 to the region At facing the detection part 41 of the temperature sensor 40 and across a region in the middle of the first passage 224, as shown in FIG. 24, they are formed to include bent passages 224b and 225b that are bent three-dimensionally.

[0075] By including the bent passages 224b and 225b that are bent three-dimensionally in this way, compared with the case where the two passages as the first passage and the second passage are formed simply as passages that bend two-dimensionally, the two passages (the first passage 224 and the second passage 225) can be concentrated and arranged closer to the center, and miniaturization and downsizing of the sleeve 20 can be achieved. In particular, since the inner wall surfaces 224b1 and 225b1 of the bent passages 224b and 225b are formed to be curved so as to be streamline - continuous, as shown in FIGS. 24 and 25, the intake air flows in a streamline manner. As a result, the passage resistance can be reduced, and the flow rate of the intake air flowing through the first passage 224 and the second passage 225 can be increased.

[0076] In the above - described embodiment, the first openings 24a and 224a of the first passages 24 and 224 open at the first end face 23a, the second openings 25a and 225a of the second passages 25 and 225 open at the second end face 23b which is at a position different from the first end face 23a, and the collision walls 26a and 126a are formed as part of the partition walls 26 and 126. However, the present invention is not limited to this configuration. For example, the first opening of the first passage and the second opening of the second passage may be formed to open at the same end face, a collision wall may be formed to project continuously from the second end face on the second - opening side, and the first opening and the second opening may be arranged so as to be aligned in a direction perpendicular to the flow direction of the intake air, and a configuration in which the intake air is made to collide with the collision wall may be adopted.

[0077] In the above - described embodiment, the case where the first passages 24 and 224 and the second passages 25 and 225 are formed so as to cooperatively define three - dimensionally bent passages 24b, 25b, 224b, and 225b is shown. However, the present invention is not limited to this, and only one of the first passage and the second passage may be formed so as to define a three - dimensionally bent passage, or the first passage and the second passage may be formed so as to respectively define three - dimensionally bent passages.

[0078] In the above - described embodiment, as a sensor for detecting the state quantity of the intake air, a sensor unit U including a pressure sensor 30 and a temperature sensor 40 and a circuit board 50 for electrically connecting the pressure sensor 30 and the temperature sensor 40 is shown. However, the present invention is not limited to this, and a configuration including only one of the pressure sensor 30 and the temperature sensor 40 may be adopted.

[0079] In the above-described embodiment, as an example of the case, the case Ca including the case body 10 and the sleeves 20, 120, 220 joined to the case body 10 is shown. However, the present invention is not limited thereto, and a case in which the case body and the sleeves are integrally formed may be adopted. Further, as the sleeves constituting the case Ca, the sleeves 20, 120, 220 having a two-stage cylindrical shape including the large-diameter cylindrical portion 22 and the small-diameter cylindrical portion 23 are shown. However, the present invention is not limited thereto, and a cylindrical sleeve having the same outer diameter may be adopted.

[0080] In the above-described embodiment, as the temperature sensor, the temperature sensor 40 formed of a semiconductor chip (surface-mounted temperature sensor) is shown. However, the present invention is not limited thereto, and other types and forms of temperature sensors may be adopted.

[0081] As described above, the sensor unit of the present invention can actively generate an intake air flow in the passage leading from the detection portion of the sensor to the intake passage, thereby suppressing or preventing the adhesion or freezing of liquids or liquid-like substances such as fuel, moisture in the intake air, and blow-by gas. Since the state quantity (pressure, temperature) of the intake air can be detected with high accuracy, the present invention can be applied not only to the intake systems of internal combustion engines of automobiles, motorcycles, etc., but also to the internal combustion engines of other vehicles.

Description of Reference Numerals

[0082] E Internal combustion engine C Combustion chamber Ip Intake pipe W Inner wall surface Ip1 Intake passage Ac Air cleaner M Throttle device m1 Throttle valve U Sensor unit Ca Case Ca1 Joint surface 10 Case body (case) 11 Joint surface 12 Fitting recess 13 Recess 20 Sleeve (Case) S Axis 21 Fitting Part 21b Joint Surface 22 Large-Diameter Cylindrical Part 22a Annular Groove 23 Small-Diameter Cylindrical Part 23a First End Face 23b Second End Face 24 First Passage At Region Facing the Detection Part of the Temperature Sensor 24a First Opening 24b Bent Passage 25 Second Passage Ap Region Facing the Detection Part of the Pressure Sensor 25a Second Opening 25b Bent Passage 26 Partition Wall 26a Collision Wall 27 Protruding Wall 30 Pressure Sensor 32c Communication Hole L Straight Line Rc Pressure-Receiving Chamber (Detection Part) 40 Temperature Sensor 41 Detection Part 50 Circuit Board 60 Terminal 70 Mold Resin Material Sr Annular Sealing Member 120 Sleeve 126 Partition Wall 126a Collision Wall (Curved Surface, Guide Part) 126b Side Surface (Guide Part) 220 Sleeve 224 First Passage 224a First Opening 224b Bent Passage 224b1 Inner Wall Surface 225 Second Passage 225a Second Opening 225b Bent Passage 225b1 Inner Wall Surface

Claims

1. A sensor unit disposed in an intake pipe of an internal combustion engine, comprising: a sensor for detecting a state quantity of intake air flowing through an intake passage defined by the intake pipe; a case for housing the sensor; and the case includes a first passage and a second passage that communicate with each other to expose a detection part of the sensor to the intake air flowing through the intake passage and open to the intake passage respectively, and a collision wall that collides the intake air flowing through the intake passage near an opening of the second passage; A sensor unit characterized by the above.

2. The collision wall includes a guiding part for guiding the intake air flowing through the intake passage toward the inside of the second passage; The sensor unit according to claim 1, characterized by the above.

3. The guiding part includes a curved surface inclined toward the inside of the second passage; The sensor unit according to claim 2, characterized by the above.

4. The guiding part includes side surfaces continuously formed on both sides of the curved surface; The sensor unit according to claim 3, characterized by the above.

5. The first passage has a first opening that opens at a first end face that is away from the inner wall surface of the intake pipe toward the central side; The second passage has a second opening that opens at a second end face closer to the inner wall surface of the intake pipe than the first opening; The sensor unit according to claim 1, characterized by the above.

6. The case includes a sleeve extending in a predetermined axial direction; The sleeve includes a partition wall that defines the first passage and the second passage so as to extend adjacent to each other; The partition wall includes the collision wall; The sensor unit according to claim 5, characterized by the above.

7. The sensor includes a pressure sensor for detecting the pressure of the intake air and a temperature sensor for detecting the temperature of the intake air; The case includes a case body for housing the temperature sensor and the pressure sensor, and a sleeve joined to the case body and defining the first passage, the second passage, and the collision wall; The sensor unit according to claim 1, characterized by the above.

8. The first passage and the second passage are formed so as to extend from a region facing the detection part of the temperature sensor to the intake passage respectively; The detection part of the pressure sensor is formed so as to face the middle of the second passage; The sensor unit according to claim 7, characterized by the above.

9. The case body includes a concave part for exposing the detection part of the temperature sensor; The sleeve includes a protruding wall inserted into the recess so as to cooperate with the recess to define a part of the first passage and the second passage. The sensor unit according to claim 8, characterized in that.

10. The second passage includes a bent passage between a region facing the detection part of the pressure sensor and a region facing the detection part of the temperature sensor. The first passage includes a bent passage on the way from a region facing the detection part of the temperature sensor to a first opening opening to the intake passage. The sensor unit according to claim 8, characterized in that.

11. The first passage and the second passage include a bent passage formed by being bent three-dimensionally. The sensor unit according to claim 10, characterized in that.

12. The bent passage is formed by curving so that its inner wall surface is continuously streamlined. The sensor unit according to claim 10, characterized in that.

13. The detection part of the pressure sensor includes a pressure receiving chamber exposed to the intake air. The pressure receiving chamber is formed so as to communicate with the second passage through a communication hole having an opening area smaller than the passage area of the second passage. The sensor unit according to claim 8, characterized in that.

14. The communication hole is arranged so as to face the second opening of the second passage opening to the intake passage in the extending direction of the second passage. The sensor unit according to claim 13, characterized in that.

15. Including a circuit board in which the pressure sensor and the temperature sensor are electrically connected and housed in the case body. The sensor unit according to claim 7, characterized in that.

16. The temperature sensor is a surface mount type temperature sensor mounted on the circuit board. The sensor unit according to claim 15, characterized in that.

17. The case includes a case body including a joint surface joined to the intake pipe, a sleeve protruding from the case body in a predetermined axial direction and defining the first passage, the second passage, and the collision wall, and an annular groove formed on the outer periphery of the sleeve into which an annular seal member is fitted. The sensor unit according to claim 1, characterized in that.

18. The sleeve includes a large-diameter cylindrical part protruding from the joint surface and a small-diameter cylindrical part continuous with the large-diameter cylindrical part. The annular groove is formed in the large-diameter cylindrical part. The sensor unit according to claim 17, characterized in that.

19. An intake pipe that defines an intake passage for guiding intake air into a combustion chamber of an internal combustion engine, a fuel injection valve that injects fuel into the intake passage or into the combustion chamber, a throttle device that is interposed in the middle of the intake pipe and opens and closes the intake passage, and a sensor unit that detects a state quantity of the intake air flowing through the intake passage. The sensor unit is the sensor unit according to any one of claims 1 to 18. An intake system for an internal combustion engine, characterized in that.

20. The sensor unit is disposed in the intake pipe on the downstream side of the throttle device. An intake system for an internal combustion engine according to claim 19, characterized in that.

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