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 in an intake gas, and a blowby gas, so as to be able to detect a pressure of the intake gas with high accuracy.SOLUTION: A sensor unit arranged in an intake pipe of an internal combustion engine includes: a pressure sensor 20 for detecting a pressure of an intake gas in the 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 having a predetermined path length Lo; and a second communication path Cp2 which has the same path length as that of the first communication path and a region with a path area (opening area of a second vent hole 22e) smaller than that of the first communication path.SELECTED DRAWING: Figure 8

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 placed in the intake manifold of an internal combustion engine, and comprises a pressure sensor that detects the pressure of the intake air in the intake manifold, a first accommodating portion 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 manifold's intake manifold, the communication passage including a first communication passage having a predetermined passage length, and a second communication passage having the same passage length as the first communication passage and including a region with a passage area smaller than the passage area of ​​the first communication passage.

[0009] 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 air vent 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 length and passage area as the first passage and a second air vent hole communicating with the second passage and having an opening area smaller than the opening area of ​​the first air vent.

[0010] 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, and the inner diameter of the second air hole is smaller than the inner diameter of the first air hole.

[0011] In the sensor unit, a configuration may be adopted in which the first communication passage and the second communication passage are formed to open into the intake passage at positions adjacent to each other.

[0012] 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.

[0013] 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.

[0014] 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.

[0015] In the above sensor unit, a configuration may be adopted in which the first passage and the second passage are formed adjacent to each other at an open end of the sleeve and open into the intake passage.

[0016] 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.

[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, the second passage, and the second accommodating portion are formed to extend within the sleeve.

[0018] In the above sensor unit, the sleeve may include an end surface where the first passage and the second passage open into the intake passage, and a tip outer wall portion protruding from the end surface to define the outer wall of the second accommodating portion.

[0019] 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.

[0020] 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.

[0021] 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.

[0022] 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.

[0023] 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.

[0024] The intake system of an internal combustion engine of the present invention comprises an intake pipe that defines an intake passage that guides intake air to a 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 a sensor unit having any of the above configurations as the sensor unit.

[0025] 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

[0026] 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]

[0027] [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 perspective cross-sectional view of a 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 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 15] 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 another embodiment. [Figure 16] 13 is a schematic diagram illustrating the flow of intake air in communication passages (first communication passage, second communication passage) that communicate between the pressure receiving chamber and the intake passage in a sensor unit according to still another embodiment. FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0028] 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.

[0029] 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.

[0030] 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.

[0031] 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.

[0032] 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.

[0033] 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 and a small diameter cylindrical portion 12b continuous with the large diameter cylindrical portion 12a. As shown in FIG. 5, when the sensor unit U is attached to the intake pipe Ip, the large diameter cylindrical portion 12a is fitted into the fitting hole H of the intake pipe Ip, and the small diameter cylindrical portion 12b is positioned so as to protrude slightly into the intake passage Ip1 of the intake pipe Ip.

[0034] The first housing portion 13 is an area that houses and holds the pressure sensor 20, as shown in FIGS. 6, 8 to 10, and is formed in an inner area of ​​the case body portion 11. As shown in FIG. 13, the second accommodating section 14 is an area that accommodates the temperature sensor 30, and is formed in an area that extends from the inner area of ​​the case main body section 11 through the inner area of ​​the sleeve 12 to the inside of the hemispherical tip outer wall section 12d that defines the outer wall protruding from the end face 12c of the sleeve 12. As shown in FIG. 6, the third accommodating portion 15 is an area for accommodating and holding the circuit board 40, and is formed in an inner area of ​​the case body 11.

[0035] 8 and 9, the first passage 16 is formed inside the sleeve 12, having a predetermined passage length Ls and a constant passage area, extending linearly in the direction of the axis S from an end face 12c that defines the open end of the sleeve 12 to the first housing portion 13 of the case main body 11. The rear open end of the first passage 16 communicates with a first air hole 22d formed in the sensor cover 22 of the pressure sensor 20.

[0036] 8 and 10, the second passage 17 is formed inside the sleeve 12 so as to have the same passage length Ls as the first passage 16 and the same passage area as the first passage 16, and extends linearly in the direction of the axis S adjacent to the first passage 16 from the end face 12c to the first housing portion 13 of the case body 11. The rear open end of the second passage 17 communicates with a second air hole 22e formed in the sensor cover 22 of the pressure sensor 20.

[0037] That is, the first passage 16 and the second passage 17 are formed to have the same passage length Ls and the same passage area. The first passage 16 is formed to communicate the pressure receiving chamber Rc of the pressure sensor 20 with the intake passage Ip1 of the intake pipe Ip through the first air hole 22d, and the second passage 17 is formed to communicate the pressure receiving chamber Rc of the pressure sensor 20 with the intake passage Ip1 of the intake pipe Ip through the second air hole 22e.

[0038] 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 FIG. 9, 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.

[0039] 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.

[0040] 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.

[0041] Here, as shown in FIG. 9, the first air vent 22d has a passage length Lc corresponding to the thickness of the bottom 22a, and as shown in FIG. 11, the first air vent 22d is a circular hole with an opening area (inner diameter D1) sufficiently smaller than the passage area of ​​the first passage 16, and is formed to communicate with the first passage 16. As shown in FIG. 10, the second air vent 22e has a passage length Lc corresponding to the thickness of the bottom 22a, and as shown in FIG. 11, the second air vent 22e is a circular hole with an opening area (inner diameter D2) that is sufficiently smaller than the passage area of ​​the second passage 17 and smaller than the opening area of ​​the first air vent 22d (i.e., D1>D2), and is formed to communicate with the second passage 17. For example, the inner diameter D2 of the second vent hole 22e is 0.6 to 0.7 times the inner diameter D1 of the first vent hole 22d. Specifically, as an example, D1=1.5 mm, and D2=1.0 mm. Further, the passage length Lc of the first vent hole 22d and the second vent hole 22e is the same as the plate thickness dimension of the bottom portion 22a, and is, for example, about 1.0 to 1.7 times the inner diameters D1 and D2.

[0042] According to the above configuration, the communication passage that connects 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 Lo (= Ls + Lc), and a second communication passage Cp2 having the same passage length Lo (= Ls + Lc) as the first communication passage Cp1 and including a region (second air hole 22e) whose passage area is smaller than the passage area of ​​the first communication passage Cp1. Specifically, the first communication passage Cp1 includes a first passage 16 having a predetermined passage length Ls and passage area, and a first air vent 22d that communicates with the first passage 16, has a passage length Lc, and has an opening area smaller than the passage area of ​​the first passage 16, while the second communication passage Cp2 is formed to include a second passage 17 that has the same passage length Ls and passage area as the first passage 16, and a second air vent 22e that communicates with the second passage 17, has a passage length Lc, and has an opening area smaller than the opening area of ​​the first air vent 22d.

[0043] Here, 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, and therefore perform a trap function to prevent foreign matter, etc. mixed in with the intake air from entering the pressure-receiving chamber Rc. In particular, as shown in FIG. 11, the first vent hole 22d and the second vent hole 22e are formed so as to be offset by a distance Cd to a side portion outside the central region including the center line CL of the pressure receiving chamber Rc. Thus, even if foreign matter or the like enters the pressure receiving chamber Rc through the first vent hole 22d and the second vent hole 22e, it is possible to prevent it from directly colliding with the pressure receiving portion 21a, and suppress or prevent the influence of the dynamic pressure according to the pressure and the intake air flow velocity due to the impact of foreign matter or the like, and detect the pressure with high accuracy.

[0044] Further, the opening area (inner diameter D2) of the second vent hole 22e is formed to be smaller than the opening area (inner diameter D1) of the first vent hole 22d. Generally, when the pressure loss corresponding to the passage resistance is ΔP (Pa), the friction coefficient of the passage is λ (dimensionless), the passage length 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 fluid velocity 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. Therefore, when the passage area or the opening area becomes smaller, the pressure loss becomes larger, that is, the passage resistance becomes larger, and it becomes difficult for the fluid to flow.

[0045] Here, when the inner diameter of the first vent hole 22d is D1, the passage length is L1, the inner diameter of the second vent hole 22e is D2, and the passage length is L2, since Lc = L2 = L1 and D2 < D1, the pressure loss ΔP2 of the second vent hole 22e is larger than the pressure loss ΔP1 of the first vent hole 22d (ΔP2 > ΔP1), that is, the passage resistance of the second vent hole 22e is formed to be larger than the passage resistance of the first vent hole 22d.

[0046] Therefore, the passage resistance (pressure loss) of the second communication passage Cp2 communicating to the pressure receiving chamber Rc through the second passage 17 and the second vent hole 22e is formed to be larger than the passage resistance (pressure loss) of the first communication passage Cp1 communicating to the pressure receiving chamber Rc through the first passage 16 and the first vent hole 22d.

[0047] According to the above configuration, when negative pressure occurs near the end face 12c of the sleeve 12 due to the descent of the piston 2, a trigger flow is generated that starts from the pressure receiving chamber Rc and is sucked into the intake passage Ip1 through the first communication passage Cp1, which has a small passage resistance, and a following flow is generated that flows from the intake passage Ip1 through the second communication passage Cp2 into the pressure receiving chamber Rc. 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.

[0048] Here, the first communication passage Cp1 and the second communication passage Cp2 open into the intake passage Ip1 at positions adjacent to each other, i.e., the first passage 16 and the second passage 17 are formed so as to open adjacent to each other at the opening end (end face 12c) of the sleeve 12. As a result, the pressure atmosphere at the opening ends of the first communication passage Cp1 and the second communication passage Cp2 becomes equivalent, so that the difference in the passage resistance (pressure loss) between the first communication passage Cp1 and the second communication passage Cp2 can be easily determined solely by the difference between the first air hole 22d and the second air hole 22e (difference in opening area). Furthermore, since the first ventilation hole 22d and the second ventilation hole 22e are formed as circular holes, a desired passage resistance (pressure loss) can be easily set by calculation, compared to the case of holes with irregular shapes.

[0049] 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.

[0050] 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 12d 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.

[0051] 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.

[0052] 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.

[0053] 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.

[0054] 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 13 and 14, and is fitted into annular groove 18 formed on the outer periphery of the sleeve 12 of the 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.

[0055] 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.

[0056] 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 12d protruding from the 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.

[0057] 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 easier to flow through than the second communication passage Cp2 because the second communication passage Cp2 includes the second air hole 22e, which has a large passage resistance (pressure loss). Therefore, as shown in FIG. 14, 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.

[0058] 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.

[0059] 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.

[0060] 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 having a predetermined passage length Lo, and a second communication passage Cp2 that has the same passage length Lo as the first communication passage Cp1 and includes a region (second air hole 22e) with a passage area smaller than the passage area of ​​the first communication passage Cp1.

[0061] As a result, the passage resistance (pressure loss) of the second communication passage Cp2 is greater than the passage resistance (pressure loss) of the first communication passage Cp1, and the intake air flow from the pressure receiving chamber Rc toward the intake passage Ip1 is more likely to occur in the first communication passage Cp1 than in the second communication passage Cp2. In other words, when a trigger flow occurs in the first communication passage Cp1, a flow is also generated in the second communication passage Cp2 in conjunction with that flow, 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.

[0062] In the above embodiment, as shown in Figures 5 and 14, the end face 12c of the sleeve 12 of the sensor unit U is attached so as to protrude slightly from the inner wall surface of the intake pipe Ip, but this is not limited to this. For example, as shown in FIG. 15, an embodiment may be adopted in which the end surface 12c of the sleeve 12 of the sensor unit U is disposed so as to protrude toward the center of the intake passage Ip1. Generally, the flow speed of the intake air within the intake passage Ip1 varies depending on the location; for example, it is faster in the central region and slower near the wall surface. However, since the first communication passage Cp1 and the second communication passage Cp2 are adjacent to each other and open to the same end face 12c, the flow speed is not affected by location-dependent flow speed, i.e., pressure, within the intake passage Ip1, and the intake air flow can be generated solely by the difference in passage resistance (pressure loss) between the first communication passage Cp1 and the second communication passage Cp2.

[0063] In the above embodiment, the communication passage includes a first communication passage having a predetermined passage length and a second communication passage having the same passage length as the first communication passage and including a region with a passage area smaller than the passage area of ​​the first communication passage. The communication passage includes a first communication passage Cp1 including a first passage 16 having a predetermined passage area and a first air vent 22d communicating with the first passage 16 and having an opening area smaller than the passage area of ​​the first passage 16, and a second communication passage Cp2 including a second passage 17 having the same passage length Ls and passage area as the first passage 16 and a second air vent 22e communicating with the second passage 17 and having an opening area smaller than the opening area of ​​the first air hole 22d. However, the communication passage is not limited to this.

[0064] For example, as shown in FIG. 16, a configuration may be adopted in which the opening areas of the first air vent 122d and the second air vent 122e are made the same, and a region Pa having a passage area smaller than the passage area of ​​the first communication passage Cp1 (here, the passage area of ​​the first passage 16 and the opening area of ​​the first air vent 122d) is formed in the middle of the second passage 17. In this configuration, as described above, the passage resistance (pressure loss) of the second communication passage Cp2 is greater than the passage resistance (pressure loss) of the first communication passage Cp1, and a trigger flow is generated in the first communication passage Cp1, in which the pressure receiving chamber Rc is sucked into the intake passage Ip1, and a follow-up flow is generated in the second communication passage Cp2, in which the intake passage Ip1 flows into the pressure receiving chamber Rc.

[0065] 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, while the first air vent 22d and the second air vent 22e, which are circular holes, are shown as the first air vent and the second air vent, first air vent and second air vent having a shape other than a circular hole may be used as long as the pressure loss of the second air vent is greater than the pressure loss of the first air vent.

[0066] In the above embodiment, the first communication passage Cp1 and the second communication passage Cp2 open into the intake passage Ip1 at positions adjacent to each other, i.e., the first passage 16 and the second passage 17 are formed so as to open adjacent to each other at the opening end (end face 12c) of the sleeve 12, but this is not limited to this, and other configurations may be adopted as long as a difference in passage resistance (pressure loss) can be set between the first communication passage and the second communication passage without being affected by the flow velocity (pressure) distribution in the intake passage Ip1.

[0067] 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.

[0068] 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.

[0069] 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.

[0070] 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.

[0071] 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]

[0072] E. Internal combustion engine C. Combustion chamber Ip intake pipe Ip1 intake passage Ac Air Cleaner M Throttle Device 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 end face 12d Tip outer wall 13 First storage section 14 Second storage section 15 Third Storage Section Cp1 1st communication passage Cp2 2nd communication passage Lo: Length of the first communication passage, length of the second communication passage 16 1st aisle (1st connecting aisle) 17 2nd passage (2nd connecting passage) Ls: Length of the first passage, length of the second passage 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 First ventilation hole (first communication passage) D1 Inner diameter of first vent hole 22e Second ventilation hole (second communication passage) D2 Inner diameter of second vent hole 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 having a predetermined passage length, and a second communication passage having the same passage length as the first communication passage and including a region having a passage area smaller than the passage area of ​​the first communication passage, A sensor unit comprising:

2. the first communication passage includes a first passage having a predetermined passage area and a first vent 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 the same passage length and passage area as the first passage, and a second vent hole communicating with the second passage and having an opening area smaller than an opening area of ​​the first vent hole, 2. The sensor unit according to claim 1.

3. The first ventilation hole and the second ventilation hole are formed as circular holes, The inner diameter of the second vent hole is smaller than the inner diameter of the first vent hole.

3. The sensor unit according to claim 2.

4. The first communication passage and the second communication passage are formed to open into the intake passage at positions adjacent to each other.

2. The sensor unit according to claim 1.

5. 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; 3. The sensor unit according to claim 2.

6. 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.

3. The sensor unit according to claim 2.

7. 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.

2. The sensor unit according to claim 1.

8. The first passage and the second passage are formed adjacent to each other at an open end of the sleeve so as to open into the intake passage.

8. The sensor unit according to claim 7.

9. 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.

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, the second passage, and the second housing are formed to extend within the sleeve.

10. The sensor unit according to claim 9.

11. The sleeve includes an end surface at which the first passage and the second passage open into the intake passage, and a tip outer wall portion formed to protrude from the end surface and define an outer wall of the second accommodation portion. The sensor unit according to claim 10 .

12. 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.

10. The sensor unit according to claim 9.

13. 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 12 .

14. 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; The sensor unit according to claim 13 .

15. 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.

16. 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. The sensor unit according to claim 15 .

17. 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 16. An intake system for an internal combustion engine.

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

18. An intake system for an internal combustion engine according to claim 17.

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