Sensor unit and intake system of internal combustion engine

Abstract

To provide a sensor unit and an intake system of an internal combustion engine, which can suppress or prevent an entry of a foreign object and a freeze of a liquid or a liquid object such as fuel, water, and a blowby gas, so as to be able to detect a pressure of an intake gas with high accuracy.SOLUTION: A sensor unit U includes: a pressure sensor 20 for detecting a pressure of an intake gas in an intake pipe; a first storage part 13 for storing the pressure sensor; and a case 10 including a communication path for making a pressure receiving chamber Rc of the pressure sensor and an intake path Ip1 of the intake pipe communicate with each other. The communication path includes: a first communication path Cp1 arranged in a manner to open to a first region A1 in the intake path; and a second communication path Cp2 arranged in a manner to open to a second region A2 in which the intake gas flows slower than in the first region in the intake path.SELECTED DRAWING: Figure 14

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, motorcycle, or other vehicle to detect state quantities (pressure, temperature) of intake air, and to an intake system of an internal combustion engine. [Background technology]

[0002] A known conventional sensor unit is a pressure sensor device with an integrated temperature sensor, which includes a case into which a terminal is inserted, a pressure detection element connected to the terminal and disposed within the case, a port portion connected to the case and having a pressure introduction hole leading to the pressure-receiving chamber of the pressure detection element, and a temperature detection element connected to the terminal and provided in the port portion (for example, Patent Document 1 and Patent Document 2).

[0003] In the above-mentioned temperature sensor integrated pressure sensor device, the pressure introducing hole formed in the port portion is formed as a single straight passage with a relatively large passage area, so if a foreign object is present in the intake manifold, the foreign object may enter the pressure receiving chamber through the pressure introducing hole, making it impossible to accurately detect the intake pressure.

[0004] Another known sensor unit is a pressure sensor device that includes a sensor storage 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 the pressure introduction chamber of the pressure detection element, a temperature sensor disposed in a temperature sensor storage protrusion formed in the base, and a circuit board disposed in the housing to which the pressure detection element and the temperature sensor are electrically connected (for example, Patent Document 3).

[0005] In the pressure sensor device, in order to prevent foreign matter from entering the pressure introduction chamber through the pressure introduction passage, a labyrinth structure is formed in the pressure introduction passage near its open end to reduce the passage area. Therefore, in the labyrinth structure area, liquids or liquid substances such as fuel blown back, moisture in the intake air, blow-by gas, etc. may adhere to the passage or freeze in cold conditions, further narrowing or blocking the passage, making it difficult to accurately detect the intake pressure. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] JP 2006-194683 A [Patent Document 2] JP 2005-274412 A [Patent Document 3] Japanese Patent Application Publication No. 11-30535 Summary of the Invention [Problem to be solved by the invention]

[0007] The present invention has been made in consideration of the above-mentioned circumstances, and its object is to provide a sensor unit and an intake system for an internal combustion engine that can suppress or prevent the intrusion of foreign matter, and can suppress or prevent the adhesion or freezing of liquids or liquid substances such as fuel, moisture in the intake air, and blow-by gas, and can detect the intake pressure with high accuracy. [Means for solving the problem]

[0008] The sensor unit of the present invention is a sensor unit that is arranged in the intake pipe of an internal combustion engine, and comprises a pressure sensor that detects the pressure of the intake air in the intake pipe, a first accommodating section that accommodates the pressure sensor, and a case including a communication passage that connects the pressure receiving chamber of the pressure sensor to the intake passage of the intake pipe, the communication passage including a first communication passage arranged to open into a first region in the intake passage, and a second communication passage arranged to open into a second region in the intake passage where the flow of intake air is slower than that of the first region.

[0009] In the above sensor unit, a configuration may be adopted in which the first communication passage has a predetermined passage length so as to open into a region away from the inner wall surface of the intake pipe toward the center, and the second communication passage has a passage length shorter than the passage length of the first communication passage so as to open into a region close to the inner wall surface of the intake pipe.

[0010] In the above sensor unit, a configuration may be adopted in which the first communication passage includes a first passage having a predetermined passage area and a first passage length, and a first air hole communicating with the first passage and having an opening area smaller than the passage area of ​​the first passage, and the second communication passage includes a second passage having the same passage area as the passage area of ​​the first passage and a second passage length shorter than the first passage length, and a second air hole communicating with the second passage and having an opening area smaller than the passage area of ​​the second passage.

[0011] In the sensor unit, a configuration may be employed in which the opening area of ​​the first air hole is the same as the opening area of ​​the second air hole.

[0012] In the sensor unit, a configuration may be employed in which the opening area of ​​the first air hole is larger than the opening area of ​​the second air hole.

[0013] In the sensor unit, a configuration may be adopted in which the first air hole and the second air hole are formed as circular holes.

[0014] In the above sensor unit, a configuration may be adopted in which the first communication passage and the second communication passage are formed adjacent to each other and open to the intake passage at different positions.

[0015] In the above sensor unit, the pressure sensor may include a sensor main body having a pressure receiving portion, and a sensor cover connected to the sensor main body to cover the pressure receiving portion and define a pressure receiving chamber, and the first air vent and the second air vent may be formed in the sensor cover.

[0016] In the above sensor unit, a configuration may be employed in which the first air hole and the second air hole are formed biased toward a side portion away from a central region of the pressure-receiving chamber.

[0017] In the above sensor unit, a configuration may be adopted in which the case includes a case main body including a joining surface to be joined to the intake pipe, and a cylindrical sleeve protruding in a predetermined axial direction from the case main body, and the first passage and the second passage are formed to extend within the sleeve.

[0018] In the above sensor unit, the sleeve may include a first end face where the first passage opens into the intake passage, and a second end face where the second passage opens into the intake passage at a position axially spaced from the first end face.

[0019] The sensor unit may include a temperature sensor that detects the temperature of intake air in the intake pipe, and the case may include a second housing portion that houses the temperature sensor.

[0020] In the above sensor unit, a configuration may be adopted in which the case includes a case main body including a joining surface to be joined to the intake pipe, and a cylindrical sleeve protruding in a predetermined axial direction from the case main body, and the first passage, the second passage, and the second accommodating portion are formed to extend within the sleeve.

[0021] The above sensor unit may include a temperature sensor that detects the temperature of the intake air in the intake pipe, the case including a case main body including a joint surface that is joined to the intake pipe, a cylindrical sleeve protruding in a predetermined axial direction from the case main body, and a second accommodating portion that accommodates the temperature sensor, the first passage, the second passage, and the second accommodating portion are formed to extend within the sleeve, and the sleeve includes a first end face where the first passage opens into the intake passage, a second end face where the second passage opens into the intake passage at a position axially separated from the first end face, and a tip outer wall portion formed protruding from the first end face and defining the outer wall of the second accommodating portion.

[0022] The sensor unit may include a circuit board to which the pressure sensor and the temperature sensor are electrically connected, and the case may include a third housing portion that houses the circuit board.

[0023] In the above sensor unit, a configuration may be adopted in which the first storage section, the second storage section, and the third storage section are sealed by filling with a molding resin material with the pressure sensor, the temperature sensor, and the circuit board respectively arranged therein.

[0024] In the sensor unit, a configuration may be adopted in which the case surrounds and exposes a plurality of terminals connected to the wiring on the circuit board, and includes a connector to be connected to the outside.

[0025] In the above sensor unit, the case may include a case main body including a joining surface that is joined to the intake pipe, a cylindrical sleeve protruding in a predetermined axial direction from the case main body, and an annular groove formed on the outer periphery of the sleeve into which an annular sealing member is fitted.

[0026] In the above sensor unit, a configuration may be adopted in which the sleeve includes a large diameter cylindrical portion continuous with 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.

[0027] The intake system of the internal combustion engine of the present invention comprises an intake pipe that defines an intake passage that guides intake air to the combustion chamber of the internal combustion engine, a fuel injection valve that injects fuel into the intake passage or into the combustion chamber, a throttle device that is located in the intake pipe and opens and closes the intake passage, and a sensor unit that detects the state quantity of the intake air, and is configured to adopt any of the sensor units configured as described above as the sensor unit.

[0028] In the intake system of the internal combustion engine, a configuration may be adopted in which the sensor unit is disposed in the intake pipe downstream of the throttle device. Effect of the Invention

[0029] The sensor unit having the above configuration can suppress or prevent the intrusion of foreign matter, and can also suppress or prevent the adhesion or freezing of liquids or liquid substances such as fuel, moisture in the intake air, and blow-by gas, and can detect the state quantities (pressure, temperature) of the intake air with high accuracy. [Brief description of the drawings]

[0030] [Figure 1] 1 is a system diagram showing an intake system of an internal combustion engine to which a sensor unit according to an embodiment of the present invention is applied. [Diagram 2] FIG. 2 is a perspective view showing the sensor unit according to one embodiment, as viewed from the outside of the case. FIG. [Diagram 3] FIG. 2 is a perspective view showing the sensor unit according to one embodiment, as viewed from the joining surface side of a case joined to an intake pipe. [Figure 4] FIG. 2 is a plan view showing a sensor unit according to one embodiment, showing a joining surface of a case joined to an intake pipe. [Diagram 5] 1 is a partial cross-sectional view showing a state in which a sensor unit according to an embodiment is attached to an intake pipe; [Figure 6] FIG. 2 is an exploded perspective view of a sensor unit according to one embodiment, viewed from one side. [Figure 7]FIG. 2 is an exploded perspective view of the sensor unit according to the embodiment, viewed from the other side. [Figure 8] 4 is a cross-sectional view of the sensor unit according to one embodiment, taken along a plane passing through a center line of a first air hole and a center line of a second air hole. FIG. [Figure 9] 4 is a cross-sectional view of a sensor unit according to one embodiment, taken along a plane including a center line of a first passage that forms a first communication passage and a center line of a first air hole. FIG. [Figure 10] 4 is a cross-sectional view of a sensor unit according to one embodiment, taken along a plane including a center line of a second passage that forms a second communication passage and a center line of a second air hole. FIG. [Figure 11] 2 is a perspective cross-sectional view of a pressure sensor (sensor body and sensor cover) in a sensor unit according to one embodiment. FIG. [Figure 12] 2 is an exploded perspective view of a sensor body and a sensor cover that constitute a pressure sensor in a sensor unit according to one embodiment; FIG. [Figure 13] 4 is a cross-sectional view showing a temperature sensor accommodated in a second accommodation portion in a sensor unit according to one embodiment. FIG. [Figure 14] FIG. 1 is a schematic diagram showing the relationship between the flow velocity distribution of intake air in an intake passage and the area where the first and second communication passages open when a sensor unit according to one embodiment is attached to an intake pipe downstream of a throttle device (butterfly-type throttle valve). [Figure 15] FIG. 1 is a schematic diagram showing the relationship between the flow velocity distribution of intake air in an intake passage and the area where the first and second communication passages open, when a sensor unit according to one embodiment is attached to an intake pipe downstream of a throttle device (a butterfly valve type throttle valve). [Figure 16] FIG. 1 is a schematic diagram illustrating the flow of intake air in communication passages (a first communication passage including a first passage and a first air hole, and a second communication passage including a second passage and a second air hole) that connect the pressure receiving chamber and the intake passage in a sensor unit according to one embodiment. [Figure 17]13 is a schematic diagram showing the relationship between the flow velocity distribution of intake air in an intake passage and the area where the first communication passage and the second communication passage are open, in a state in which a sensor unit according to another embodiment is attached to an intake pipe. FIG. [Figure 18] FIG. 11 is a schematic diagram illustrating the flow of intake air in communication passages (a first communication passage including a first passage and a first air hole, and a second communication passage including a second passage and a second air hole) that connect the pressure receiving chamber and the intake passage in a sensor unit according to yet another embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0031] Hereinafter, an embodiment of the present invention will be described with reference to the accompanying drawings. The sensor unit U of the present invention is incorporated in an intake system of an internal combustion engine E mounted on a vehicle such as an automobile or motorcycle. The internal combustion engine E includes a cylinder block 1, a piston 2, a cylinder head 3, an intake valve 4a that opens and closes the intake port 3a, an exhaust valve 4b that opens and closes the exhaust port 3b, an ignition plug 5, and a cam mechanism 6 that drives the intake valve 4a and the exhaust valve 4b.

[0032] 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 midway through the intake pipe Ip, an air cleaner Ac connected to the upstream end of the intake pipe Ip, a fuel injection valve Iv arranged downstream of the intake pipe Ip, and a sensor unit U arranged in the intake pipe Ip downstream of the throttle device M and upstream of the fuel injection valve Iv.

[0033] The intake pipe Ip defines an intake passage Ip1 that guides intake air to a combustion chamber C of the internal combustion engine E. The throttle device M includes a butterfly-type throttle valve m1 that opens and closes the intake passage Ip1, and a bypass passage m2 that bypasses the throttle valve m1. The exhaust system of the internal combustion engine E includes an exhaust pipe Ep connected to the cylinder head 3 so as to lead to the exhaust port 3b, a catalytic converter Cc disposed midway through the exhaust pipe Ep, an oxygen sensor Os, and the like.

[0034] A sensor unit U according to one embodiment includes a case 10, a pressure sensor 20, a temperature sensor 30, a circuit board 40, a plurality of terminals 50, a molded resin material 60, and an annular seal member 70, as shown in FIGS.

[0035] The case 10 is molded using a resin material and includes a case main body 11, a cylindrical sleeve 12, a first accommodating portion 13, a second accommodating portion 14, a third accommodating portion 15, a first passage 16, a second passage 17, an annular groove 18, and a connector 19.

[0036] As shown in Figures 3 and 5, the case main body 11 has a flat joint surface 11a that is joined to the outer wall of the intake pipe Ip, and a flange portion 11b that includes a circular hole 11b1 through which a fastening screw (not shown) that is screwed into a screw hole in the intake pipe Ip passes. The sleeve 12 is formed in a two-stage cylindrical shape extending in the direction of an axis S perpendicular to the joint surface 11a of the case body 11. That is, the sleeve 12 is formed to include a large diameter cylindrical portion 12a, a small diameter cylindrical portion 12b continuous with the large diameter cylindrical portion 12a, a first end face 12c, a second end face 12d, and a tip outer wall portion 12e. The large diameter cylindrical portion 12a is a region that is fitted into a fitting hole H of the intake pipe Ip, and an annular groove 18 into which an annular seal member 70 is fitted is formed on the outer periphery thereof. The small diameter cylindrical portion 12b is a region that is disposed so that a part of it protrudes into the intake passage Ip1 when joined to the intake pipe Ip. The first end surface 12c defines an opening end where the first passage 16 opens into the intake passage Ip1. The second end surface 12d defines an opening end where the second passage 17 opens into the intake passage Ip1 at a position away from the first end surface 12c in the axial direction S, that is, at a position close to the inner wall surface W of the intake pipe Ip. The tip outer wall portion 12e protrudes from the first end face 12c in the direction of the axis S and is formed in a hemispherical shape, defining the outer wall of the second housing portion 14. Then, as shown in FIG. 5, in a state where the sensor unit U is assembled to the intake pipe Ip, the large-diameter cylindrical portion 12a is fitted into the fitting hole H of the intake pipe Ip, and a part of the small-diameter cylindrical portion 12b protrudes into the intake passage Ip1 of the intake pipe Ip. That is, the second end face 12d is close to the inner wall surface W, and the region including the first end face 12c and the tip outer wall portion 12e protrudes from the inner wall surface W into the intake passage Ip1 and is arranged.

[0037] As shown in FIGS. 6, 8 to 10, the first housing portion 13 is a region for housing and holding the pressure sensor 20, and is formed in the inner region of the case main body portion 11. As shown in FIG. 13, the second housing portion 14 is a region for housing the temperature sensor 30, and is formed in a region that extends from the inner region of the case main body portion 11 to the inner region of the sleeve 12 and reaches the inside of the tip outer wall portion 12e. As shown in FIG. 6, the third housing portion 15 is a region for housing and holding the circuit board 40, and is formed in the inner region of the case main body portion 11.

[0038] As shown in FIGS. 8 and 9, the first passage 16 has a first passage length Ls1 inside the sleeve 12 and a constant passage area, and is formed to linearly extend in the direction of the axis S from the first end face 12c of the sleeve 12 to the first housing portion 13 of the case main body portion 11. The back-side opening end of the first passage 16 communicates with a first vent hole 22d formed in the sensor cover 22 of the pressure sensor 20. As shown in FIGS. 8 and 10, the second passage 17 has a second passage length Ls2 (Ls2 < Ls1) shorter than the first passage length Ls1 inside the sleeve 12 and a constant passage area, and is formed to linearly extend in the direction of the axis S adjacent to the first passage 16 from the second end face 12d to the first housing portion 13 of the case main body portion 11. The back-side opening end of the second passage 17 communicates with a second vent hole 22e formed in the sensor cover 22 of the pressure sensor 20.

[0039] Here, the first passage 16 and the second passage 17 are formed to have the same passage area but different passage lengths (first passage length Ls1>second passage length Ls2). For example, the first passage length Ls1 of the first passage 16 is 1.2 to 1.3 times the second passage length Ls2 of the second passage 17. The first passage 16 is formed to communicate between the pressure receiving chamber Rc of the pressure sensor 20 and the intake passage Ip1 of the intake pipe Ip through the first air hole 22d, and the second passage 17 is formed to communicate between the pressure receiving chamber Rc of the pressure sensor 20 and the intake passage Ip1 of the intake pipe Ip through the second air hole 22e.

[0040] As shown in Figs. 5, 7 and 8, the annular groove 18 is formed in the region of the large diameter cylindrical portion 12a of the sleeve 12 of the case 10 by hollowing out the outer periphery in an annular shape so that an annular seal member 70 can be fitted therein. As shown in Figures 9 and 10, the connector 19 protrudes from the case main body 11 in a direction perpendicular to the axis S, and is formed so as to expose and surround multiple (here, four) terminals 50 connected to the circuit board 40 and to be connected to the outside.

[0041] As shown in FIGS. 11 and 12, the pressure sensor 20 is composed of a sensor body 21 and a sensor cover 22. The sensor body 21 includes a pressure receiving portion 21a such as a diaphragm equipped with a semiconductor strain gauge, lead wires 21b extending from the pressure receiving portion 21a, and an annular portion 21c surrounding the periphery of the pressure receiving portion 21a. The sensor cover 22 includes a disk-shaped bottom 22a, an annular step portion 22b, an annular outer wall portion 22c, a first air hole 22d, and a second air hole 22e. The sensor cover 22 functions as a protective cover that covers the pressure-receiving portion 21a, and is connected to the sensor body 21 by fitting the annular portion 21c into the annular outer wall portion 22c to define the pressure-receiving chamber Rc. The pressure sensor 20 outputs, as an electrical signal, a change in electrical resistance that corresponds to the amount of deformation caused in the pressure receiving portion 21a by the pressure of the intake air introduced into the pressure receiving chamber Rc through the first air hole 22d and the second air hole 22e. Further, the pressure sensor 20 detects the pressure of the intake air flowing through the intake passage Ip1 downstream of the throttle device M when the sensor unit U is attached to the intake pipe Ip.

[0042] Here, as shown in Figures 9 and 11, the first air vent 22d has a passage length Lc corresponding to the thickness of the bottom 22a, and is a circular hole with an opening area (inner diameter Ds) sufficiently smaller than the passage area of ​​the first passage 16, and is formed to communicate with the first passage 16. As shown in Figures 10 and 11, the second air vent 22e has a passage length Lc corresponding to the thickness of the bottom 22a, and is a circular hole with an opening area (inner diameter Ds) that is sufficiently smaller than the passage area of ​​the second passage 17 and the same as the opening area of ​​the first air vent 22d, and is formed so as to communicate with the second passage 17.

[0043] According to the above configuration, the communication passage connecting the pressure receiving chamber Rc of the pressure sensor 20 and the intake passage Ip1 of the intake pipe Ip is formed to include a first communication passage Cp1 having a predetermined passage length L1 (= Ls1 + Lc) so as to open into a region away from the inner wall surface W of the intake pipe Ip toward the center, and a second communication passage Cp2 having a passage length L2 (= Ls2 + Lc) shorter than the passage length L1 of the first communication passage Cp1 so as to open into a region close to the inner wall surface W of the intake pipe Ip. Specifically, the first communication passage Cp1 includes a first passage 16 having a predetermined passage area and a first passage length Ls1, and a first air hole 22d that communicates with the first passage 16 and has an opening area smaller than the passage area of ​​the first passage 16, while the second communication passage Cp2 includes a second passage 17 that has the same passage area as the first passage 16 and a second passage length Ls2 that is shorter than the first passage length Ls1, and a second air hole 22e that communicates with the second passage 17 and has an opening area smaller than the passage area of ​​the second passage 17.

[0044] Here, the first communication passage Cp1 is formed with a predetermined passage length L1 so as to open into a region away from the inner wall surface W of the intake pipe Ip toward the center, and the second communication passage Cp2 is formed with a passage length L2 shorter than the passage length L1 of the first communication passage Cp1 so as to open into a region close to the inner wall surface W of the intake pipe Ip.

[0045] Incidentally, in a state where the sensor unit U is disposed downstream of the throttle device M (throttle valve m1) in the intake pipe Ip, the flow of intake air in the intake passage Ip1 is such that in an opening range where the throttle valve m1 is small, as shown in Figures 14 and 15, the maximum flow velocity (Vmax) occurs in an area biased from the central area toward the inner wall surface W as indicated by the solid line. On the other hand, when the throttle valve m1 is fully opened, as shown by the two-dot chain line, the maximum flow velocity (Vmax) occurs in the central area, as in the case of a typical straight passage.

[0046] In addition, for the intake air flowing through the intake passage Ip1, if the air is not flowing at ultra-high speed, it is considered to be a non-viscous and non-compressible fluid, and Bernoulli's theorem, kinetic energy + pressure energy + potential energy = constant, can be used approximately. Specifically, the density of the fluid is ρ(kg / m 3 ), flow velocity is V (m / s), pressure is P (pa), gravitational acceleration is g (m / s2), and height is Z, then ρV 2 / 2+P+ρgZ = constant. In the intake air flow in the intake pipe Ip, potential energy can be ignored, so ρV 2 This can be approximated as / 2+P = constant. That is, in the intake passage Ip1, as the flow velocity V increases (speeds up), the pressure P decreases (lowers), and as the flow velocity V decreases (slows down), the pressure P increases (highers).

[0047] Therefore, the first communication passage Cp1 is arranged to open into the first region A1 in the intake passage Ip1 where the flow of intake air is fast (at a speed V1), and the second communication passage Cp2 is arranged to open into the second region A2 in the intake passage Ip1 where the flow of intake air is slower (at a speed V2) than in the first region A1. This results in a pressure difference ΔP (=P2-P1=(V1 2 -V2 2 ) / 2). This pressure difference ΔP generates a trigger flow that originates from the pressure receiving chamber Rc and is drawn from the first communication passage Cp1 into the intake passage Ip1, and a following flow that follows this trigger flow and flows from the intake passage Ip1 through the second communication passage Cp2 into the pressure receiving chamber Rc.

[0048] As a result, in the sensor unit U, a flow of intake air occurs in the communication passages (first communication passage Cp1 and second communication passage Cp2), which makes it possible to suppress or prevent liquid or liquid substances such as fuel, moisture in the intake air, and blow-by gas from adhering to the inside of the communication passages and also to prevent the adhering substances from freezing, etc. Therefore, the pressure sensor 20 can detect the pressure of the intake air led to the pressure receiving chamber Rc with high accuracy.

[0049] On the other hand, the passage resistance (pressure loss) of the communicating passage is expressed as Δp (Pa), the friction coefficient of the passage is λ (dimensionless), the length of the passage is L (m), the inner diameter of the passage is D (m), and the density of the fluid is ρ (kg / m 3 ), and the flow rate is V (m / s), Δp = λLρV 2 / 2D. That is, the pressure loss Δp is inversely proportional to the inner diameter D of the passage and proportional to the passage length L. In addition, as the passage length L becomes longer, the pressure loss Δp becomes larger. Here, since the relationship between the first passage length Ls1 of the first passage 16 and the second passage length Ls2 of the second passage 17 is Ls1>Ls2, the pressure loss Δp1 of the first passage 16 is greater than the pressure loss Δp2 of the second passage 17 (Δp1>Δp2). In other words, when only the first passage 16 and the second passage 17 are compared, the first communication passage Cp1 has a passage configuration in which the passage resistance is greater than that of the second communication passage Cp2. However, this communication passage is configured to ensure a pressure difference ΔP between the first communication passage Cp1 and the second communication passage Cp2 to the extent that the passage resistance can be ignored. Therefore, as described above, a flow of intake air occurs in the communication passage (first communication passage Cp1 and second communication passage Cp2), and liquid or liquid-like matter such as fuel, moisture in the intake air, and blow-by gas can be suppressed or prevented from adhering to the inside of the communication passage, and freezing of the adhering matter can be prevented, and the pressure sensor 20 can detect the pressure of the intake air led to the pressure receiving chamber Rc with high accuracy.

[0050] Here, the first communication passage Cp1 and the second communication passage Cp2 are formed adjacent to each other and open at different positions to the intake passage Ip1, that is, the first passage 16 opens at a first end face 12c arranged in a first region A1 where the flow of intake air is fast, and the second passage 17 opens at a second end face 12d arranged in a second region A2 where the flow of intake air is slower than that of the first region A1. The first end face 12c and the second end face 12d are separated from each other in the direction of the axis S, but open in regions close to each other within the intake passage Ip1. As a result, by simply setting the position of the opening end (first end face 12c) of the first communication passage Cp1 and the position of the opening end (second end face 12d) of the second communication passage Cp2 appropriately, the pressure difference ΔP can be appropriately adjusted, and the flow rate of intake air flowing through the communication passages (first communication passage Cp1 and second communication passage Cp2) can be easily adjusted.

[0051] In addition, the first air vent 22d and the second air vent 22e are formed to have an opening area smaller than the passage area of ​​the first passage 16 and the second passage 17, so that they serve to prevent foreign matter, etc. mixed in the intake air from entering the pressure-receiving chamber Rc (a trap function). In particular, the first ventilation hole 22d and the second ventilation hole 22e are formed at a distance Cd offset from a central region including the center line CL of the pressure receiving chamber Rc, as shown in FIG. As a result, even if a foreign object or the like enters the pressure-receiving chamber Rc through the first air vent 22d and the second air vent 22e, it is possible to prevent the foreign object or the like from colliding directly with the pressure-receiving portion 21a, and it is possible to suppress or prevent the effects of pressure due to the impact of the foreign object or the dynamic pressure corresponding to the flow velocity of the intake air, thereby enabling the pressure to be detected with high accuracy. Furthermore, since the first ventilation hole 22d and the second ventilation hole 22e are formed as circular holes, they are easier to process than holes of an irregular shape.

[0052] The pressure sensor 20 having the above configuration is disposed in a die and molded integrally when the case 10 is molded from a resin material using a die so as to be accommodated in the first accommodation portion 13 of the case main body 11. The pressure sensor 20 has the lead wires 21b electrically connected to the circuit board 40, and is then covered and sealed with the molded resin material 60. The pressure sensor 20 may be fitted into the first housing portion 13 of the case 10, which has been molded in advance from a resin material, in a later process, and sealed with the molded resin material 60.

[0053] 6, 7 and 13, the temperature sensor 30 is a lead-type sensor and is composed of a temperature sensing element 31, such as a thermistor, and a lead wire 32 extending from the temperature sensing element 31. That is, the temperature sensor 30 is inserted into the second housing portion 14 of the case 10, the temperature sensing element 31 is disposed in the inner region of the tip outer wall portion 12e of the sleeve 12, and the lead wire 32 is electrically connected to the circuit board 40, and then is covered and sealed with a molded resin material 60. The temperature sensor 30 detects the temperature of the intake air flowing through the intake passage Ip1 downstream of the throttle device M when the sensor unit U is attached to the intake pipe Ip.

[0054] The circuit board 40 has printed wiring and various electronic components (not shown) surface-mounted, and as shown in Figures 6 and 7, has three through holes 41 to which the lead wires 21b of the pressure sensor 20 are electrically connected, and four through holes 42 to which the lead wires 32 of the temperature sensor 30 are electrically connected. During assembly, the circuit board 40 is placed in the third housing portion 15 of the case body 11, the lead wires 21b and 32 are electrically connected, and then the circuit board 40 is covered with the molded resin material 60 and sealed.

[0055] The terminal 50 is formed from a conductive metal material and, as shown in Figures 9 and 10, is embedded in the case main body 11, one end is connected to the through hole 42 of the circuit board 40, and the free end side is exposed inside the connector 19 and is arranged so as to be surrounded by the connector 19.

[0056] The molding resin material 60 is a sealing material such as epoxy resin, which is injected into the case 10 to fill the gap spaces while the pressure sensor 20, the temperature sensor 30, and the circuit board 40 are housed and held in the first housing section 13, the second housing section 14, and the third housing section 15 of the case 10, respectively, and then solidified. As a result, as shown in Figures 8, 9, 10, and 13, the first accommodating section 13, the second accommodating section 14, and the third accommodating section 15 are sealed by filling them with molding resin material 60, with the pressure sensor 20, the temperature sensor 30, and the circuit board 40 respectively arranged in place.

[0057] The annular sealing member 70 is made of a rubber material having excellent heat resistance, swelling resistance, etc., and is formed into a circular ring shape as shown in Figures 8 to 10, and is fitted into annular groove 18 formed on the outer periphery of sleeve 12 of case 10. As shown in FIG. 5, the annular seal member 70 seals between the fitting hole H of the intake pipe Ip and the sleeve 12 when the sensor unit U is attached to the intake pipe Ip.

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

[0059] When the internal combustion engine E is in an operating state, the sensor unit U detects the pressure and temperature, which are state quantities of the intake air, downstream of the throttle device M. That is, the temperature of the intake air is detected by the temperature sensor 30. Specifically, since the temperature sensor 31 is disposed near the inside of the tip outer wall portion 12e protruding from the first end face 12c of the sleeve 12, the temperature of the intake air flowing through the intake passage Ip1 is detected in an area away from the wall surface of the intake pipe Ip. This makes it possible to suppress the influence of the temperature of the wall surface of the intake pipe Ip.

[0060] In addition, the pressure sensor 20 detects the pressure of the intake air flowing through the intake passage Ip1 via the first communication passage Cp1 including the first passage 16 and the first air vent 22d and the second communication passage Cp2 including the second passage 17 and the second air vent 22e. Specifically, when comparing the ease of flow between the first communication passage Cp1 and the second communication passage Cp2, the first communication passage Cp1 is located in the first region A1 where the flow of intake air is faster, and the second communication passage Cp2 is located in the second region A2 where the flow of intake air is slower than that of the first region A1, so that the intake air in the pressure receiving chamber Rc is more easily sucked out through the first communication passage Cp1 than through the second communication passage Cp2. Therefore, as shown in FIG. 16, the intake air in the pressure receiving chamber Rc is sucked into the intake passage Ip1 through the first communication passage Cp1, and in conjunction with this flow of intake air, the intake air in the intake passage Ip1 flows into the pressure receiving chamber Rc through the second communication passage Cp2.

[0061] This flow is continuous, so that intake air is supplied into the pressure receiving chamber Rc, and the pressure receiving portion 21a detects the pressure of the intake air. This flow of intake air also suppresses or prevents liquid or liquid-like matter such as fuel, moisture in the intake air, and blow-by gas from adhering to the inner wall surfaces of the first communication passage Cp1 and the second communication passage Cp2, and therefore suppresses or prevents freezing of these. Furthermore, the first ventilation hole 22d and the second ventilation hole 22e prevent foreign matter and the like from entering the pressure receiving chamber Rc.

[0062] In this manner, the pressure of the intake air is detected by the pressure sensor 20, and the temperature of the intake air is detected by the temperature sensor 30. The respective detected information is input as control information for the ECU, and the internal combustion engine E is appropriately controlled.

[0063] As described above, the sensor unit U comprises a pressure sensor 20 that detects the pressure of the intake air in the intake pipe Ip, a first accommodating section 13 that accommodates the pressure sensor 20, and a case 10 that includes a communication passage that connects the pressure receiving chamber Rc of the pressure sensor 20 to the intake passage Ip1 of the intake pipe Ip. The communication passage includes a first communication passage Cp1 that is arranged to open into a first region A1 in the intake passage Ip1 where the flow of intake air is faster, and a second communication passage Cp2 that is arranged to open into a second region A2 in the intake passage Ip1 where the flow of intake air is slower than that of the first region A1.

[0064] According to this, a pressure difference occurs between the opening end of the first communication passage Cp1 and the opening end of the second communication passage Cp2, causing a trigger flow to occur in the first communication passage Cp1, and in response to this flow, a flow is also generated in the second communication passage Cp2, and a flow is generated in the entire communication passage. Therefore, it is possible to suppress or prevent stagnation of the intake air flow in the areas of the first communication passage Cp1, the pressure receiving chamber Rc, and the second communication passage Cp2. Therefore, the intake air in the intake passage Ip1 can be constantly supplied to the pressure receiving chamber Rc, the intrusion of foreign matter can be suppressed or prevented, and the adhesion or freezing of liquids or liquid substances such as fuel, moisture in the intake air, and blow-by gas can be suppressed or prevented, and the intake pressure can be detected with high accuracy by the pressure receiving section 21a.

[0065] In the above embodiment, the intake pipe Ip is a straight pipe that defines a linear intake passage Ip1. However, this is not limited to this. For example, as shown in FIG. 17, the sensor unit U may be adopted in an intake pipe Ip that is a curved pipe that defines a curved intake passage Ip1. In this embodiment, the flow velocity distribution of the intake air flowing through the intake passage Ip1 is such that the flow is fast on the outer inner wall surface Wo side and slow on the inner inner wall surface Wi side. Therefore, the first communication passage Cp1 is arranged to open into an outer first region A1 in the intake passage Ip1 where the flow of intake air is faster, and the second communication passage Cp2 is arranged to open into a second region A2 in the intake passage Ip1 where the flow of intake air is slower than the first region A1. That is, the first communication passage Cp1 has a short passage length so as to open into a region close to the inner wall surface Wo of the intake pipe Ip, and the second communication passage Cp2 has a passage length longer than the first communication passage Cp1 so as to open into a region away from the inner wall surface Wo of the intake pipe Ip toward the center. In this case, as in the case described above, a pressure difference occurs between the opening end of the first communication passage Cp1 and the opening end of the second communication passage Cp2, causing a trigger flow to occur in the first communication passage Cp1, which in turn causes a flow to occur in the second communication passage Cp2 in conjunction with that flow, thereby generating a flow throughout the entire communication passage.

[0066] In the above embodiment, the first air vent 22d and the second air vent 22e formed in the sensor cover 22 are shown as the first and second air vents, but this is not limited to this, and the first air vent and the second air vent formed in the sleeve of the case may also be used. For example, a first vent hole may be provided at a position that divides the first passage in two, and a second vent hole may be provided at a position that divides the second passage in two. In addition, the first air vent 22d and the second air vent 22e, which are circular holes, are shown as the first and second air vents, but this is not limited to this, and first and second air vents having the same opening area and a shape other than a circular hole may be used.

[0067] In the above embodiment, the first ventilation hole 22d and the second ventilation hole 22e having the same opening area are shown as the first ventilation hole and the second ventilation hole, but this is not limited to this, and as shown in FIG. 18, a configuration may be adopted in which the opening area of ​​the first ventilation hole 122d is larger than the opening area of ​​the second ventilation hole 22e. In this embodiment, the passage resistance of the first air vent 122d is smaller than that of the first air vent 22d, and the flow is easier in the first communication passage CP1 (the first passage 16 and the first air vent 122d) than in the second communication passage Cp2 (the second passage 17 and the second air vent 22e).

[0068] In the above embodiment, the first communication passage Cp1 and the second communication passage Cp2 are formed adjacent to each other and open at different positions relative to the intake passage Ip1, i.e., the first passage 16 opens at the first end face 12c and the second passage 17 opens at the second end face 12d. However, this is not limited to this, and other configurations may be adopted as long as a pressure difference can be set between the opening end of the first communication passage and the opening end of the second communication passage.

[0069] In the above embodiment, in addition to the pressure sensor 20, a sensor unit U is shown that includes a temperature sensor 30 and a circuit board 40 that electrically connects the pressure sensor 20 and the temperature sensor 30. However, this is not limited to this, and a sensor unit that does not include the temperature sensor 30 but includes the circuit board 40 and the pressure sensor 20, or a sensor unit that does not include the temperature sensor 30 but includes only the pressure sensor 20, may be adopted.

[0070] In the above embodiment, a sensor unit U including a sleeve 12 forming the first passage 16 and the second passage 17 is shown as part of the first and second communication passages that connect the pressure receiving chamber Rc of the pressure sensor 20 to the intake passage Ip1 of the intake pipe Ip. However, this is not limited to this, and a sensor unit having a case including other shapes than a sleeve may be used as long as it is configured to include the first and second communication passages.

[0071] In the above embodiment, a two-stage cylindrical sleeve 12 including a large diameter cylindrical portion 12a and a small diameter cylindrical portion 12b is shown as a cylindrical sleeve protruding from the case main body portion 11 in the direction of the axis S. However, this is not limited to this, and a cylindrical sleeve having the same outer diameter may be used.

[0072] In the above embodiment, the pressure sensor 20 equipped with a semiconductor strain gauge is shown as the pressure sensor, but this is not limited to this, and a capacitance type pressure sensor may be adopted, and other types and forms of pressure sensors may be adopted as long as they have a pressure receiving part that receives the intake pressure. In addition, in the above embodiment, the pressure sensor is shown as pressure sensor 20 having a sensor main body 21 and a sensor cover 22, but this is not limited to this, and a pressure sensor without a sensor cover and with the pressure receiving part exposed to the outside may be adopted, and in the first housing part in which the pressure sensor is housed, a pressure receiving chamber may be defined by the pressure sensor and the inner wall surface of the first housing part of the case in cooperation with each other.

[0073] As described above, the sensor unit of the present invention can suppress or prevent the intrusion of foreign matter, and can suppress or prevent the adhesion or freezing of liquids or liquid substances such as fuel, moisture in the intake air, and blow-by gas, and can detect the state quantities (pressure, temperature) of the intake air with high accuracy, so it is not only applicable to the intake systems of internal combustion engines of automobiles, motorcycles, etc., but is also useful in internal combustion engines of other vehicles. [Explanation of symbols]

[0074] E. Internal combustion engine C. Combustion chamber Ip intake pipe W, Wo Inner wall surface Ip1 intake passage Ac Air Cleaner M Throttle Device m1 throttle valve U Sensor unit 10 Cases 11 Case body 11a Joint surface 12 Sleeve S axis 12a Large diameter cylindrical section 12b Small diameter cylindrical section 12c 1st end face 12d 2nd end face 12e Tip outer wall 13 First storage section 14 Second storage section 15 Third Storage Section Cp1 1st communication passage L1 Passage length of the first communication passage Cp2 2nd communication passage L2: Length of the second communication passage 16 1st aisle (1st connecting aisle) Ls1 First passage length 17 2nd passage (2nd connecting passage) Ls2 Second passage length 18 Annular groove 19 Connectors 20 Pressure Sensor Rc pressure receiving chamber 21 Sensor body 21a Pressure receiving part 21b Lead Wire 21c Circular section 22 Sensor cover 22a bottom 22b Annular step 22c Circular outer wall 22d, 122d First ventilation hole (first communication passage) 22e Second ventilation hole (second communication passage) 30 Temperature Sensor 31 Thermosensor 32 Lead Wire 40 Circuit Board 50 Terminals 60 Molding resin material 70 Annular seal member

Claims

1. A sensor unit arranged in an intake pipe of an internal combustion engine, a pressure sensor for detecting the pressure of intake air in the intake pipe; a case including a first housing portion that houses the pressure sensor and a communication passage that communicates a pressure receiving chamber of the pressure sensor with an intake passage of the intake pipe, The communication passage includes a first communication passage arranged to open into a first region in the intake passage, and a second communication passage arranged to open into a second region in the intake passage where the flow of intake air is slower than that of the first region. A sensor unit comprising:

2. the first communication passage has a predetermined passage length so as to open into a region away from an inner wall surface of the intake pipe toward a center side, the second communication passage has a passage length shorter than a passage length of the first communication passage so as to open into a region adjacent to an inner wall surface of the intake pipe; 2. The sensor unit according to claim 1.

3. the first communication passage includes a first passage having a predetermined passage area and a first passage length, and a first air hole communicating with the first passage and having an opening area smaller than the passage area of ​​the first passage, the second communication passage includes a second passage having a passage area equal to a passage area of ​​the first passage and a second passage length shorter than the first passage length, and a second air hole communicating with the second passage and having an opening area smaller than the passage area of ​​the second passage, 3. The sensor unit according to claim 2.

4. The opening area of ​​the first ventilation hole is the same as the opening area of ​​the second ventilation hole.

4. The sensor unit according to claim 3.

5. The opening area of ​​the first ventilation hole is larger than the opening area of ​​the second ventilation hole.

4. The sensor unit according to claim 3.

6. The first ventilation hole and the second ventilation hole are formed as circular holes.

4. The sensor unit according to claim 3.

7. The first communication passage and the second communication passage are formed adjacent to each other and open at different positions relative to the intake passage.

2. The sensor unit according to claim 1.

8. The pressure sensor includes a sensor body having a pressure receiving portion, and a sensor cover connected to the sensor body so as to cover the pressure receiving portion and define the pressure receiving chamber, the first ventilation hole and the second ventilation hole are formed in the sensor cover; 4. The sensor unit according to claim 3.

9. The first vent hole and the second vent hole are formed biased toward a side portion away from a central region of the pressure receiving chamber.

4. The sensor unit according to claim 3.

10. the case includes a case body including a joint surface to be joined to the intake pipe, and a cylindrical sleeve protruding in a predetermined axial direction from the case body, The first passage and the second passage are formed to extend within the sleeve.

4. The sensor unit according to claim 3.

11. the sleeve includes a first end surface at which the first passage opens into the intake passage, and a second end surface at a position spaced apart from the first end surface in the axial direction at which the second passage opens into the intake passage, The sensor unit according to claim 10 .

12. a temperature sensor for detecting a temperature of the intake air in the intake pipe; The case includes a second housing portion that houses the temperature sensor.

2. The sensor unit according to claim 1.

13. the case includes a case body including a joint surface to be joined to the intake pipe, and a cylindrical sleeve protruding in a predetermined axial direction from the case body, The first passage, the second passage, and the second housing are formed to extend within the sleeve. The sensor unit according to claim 12 .

14. a temperature sensor for detecting a temperature of the intake air in the intake pipe; the case includes a case body including a joint surface to be joined to the intake pipe, a cylindrical sleeve protruding from the case body in a predetermined axial direction, and a second housing portion housing the temperature sensor, the first passage, the second passage, and the second receiving portion are formed to extend within the sleeve; the sleeve includes a first end surface at which the first passage opens into the intake passage, a second end surface at which the second passage opens into the intake passage at a position spaced apart from the first end surface in the axial direction, and a tip outer wall portion formed to protrude from the first end surface and defining an outer wall of the second accommodation portion, 4. The sensor unit according to claim 3.

15. a circuit board to which the pressure sensor and the temperature sensor are electrically connected; The case includes a third housing portion that houses the circuit board. The sensor unit according to claim 12 .

16. the first housing portion, the second housing portion, and the third housing portion are sealed by filling with a molding resin material, with the pressure sensor, the temperature sensor, and the circuit board being disposed therein, respectively; The sensor unit according to claim 15 .

17. the case includes a connector that exposes and surrounds a plurality of terminals connected to wiring on the circuit board and is connected to an external device; 17. The sensor unit according to claim 16.

18. The case includes a case body including a joint surface to be joined to the intake pipe, a cylindrical sleeve protruding in a predetermined axial direction from the case body, and an annular groove formed on an outer periphery of the sleeve and into which an annular seal member is fitted.

2. The sensor unit according to claim 1.

19. the sleeve includes a large diameter cylindrical portion continuous with the joining surface and a small diameter cylindrical portion continuous with the large diameter cylindrical portion, The annular groove is formed in the large diameter cylindrical portion.

20. The sensor unit according to claim 18.

20. an intake pipe defining an intake passage for introducing 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 disposed midway through the intake pipe for opening and closing the intake passage; A sensor unit for detecting a state quantity of the intake air, The sensor unit is a sensor unit according to any one of claims 1 to 19. An intake system for an internal combustion engine.

21. The sensor unit is disposed in the intake pipe downstream of the throttle device.

21. An intake system for an internal combustion engine as claimed in claim 20.

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