Sensor unit and air intake system of internal combustion engine

Abstract

The invention provides a sensor unit and an air intake system of an internal combustion engine, which can inhibit or prevent invasion of foreign matters or can inhibit or prevent freezing of liquid or liquid substances such as fuel, moisture in intake air, blow-by gas and the like, and can detect the pressure of the intake air with high precision. This sensor unit is disposed in an intake pipe of an internal combustion engine, and is provided with: a pressure sensor (20) that detects the pressure of intake air in the intake pipe; and a housing (10) that includes a first housing part (13) that houses the pressure sensor, and a communication path that connects a pressure receiving chamber (Rc) of the pressure sensor and an air intake path (Ip1) of the air intake pipe, the communication path including: a first communication path (Cp1) having a predetermined path length (Lo); and a second communication passage (Cp2) having the same passage length as the first communication passage and including a region (opening area of a second vent hole (22e)) having a passage area smaller than that of the first communication passage.

Description

Technical Field

[0001] The present invention relates to a sensor unit used in an intake system of an internal combustion engine mounted on an automobile, a motorcycle, or other vehicles to detect a state quantity (pressure, temperature) of intake air, and the intake system of the internal combustion engine. Background Art

[0002] As a previous sensor unit, there is known a temperature sensor integrated pressure sensor device, which includes: a shell having a terminal embedded therein; a pressure detection element connected to the terminal and arranged in the shell; a port portion connected to the shell and having a pressure inlet hole connected to a pressure receiving chamber of the pressure detection element; and a temperature detection element connected to the terminal and arranged at the port portion (for example, Patent Document 1, Patent Document 2).

[0003] In the temperature sensor integrated pressure sensor device, the pressure introduction hole formed in the port portion is formed as a linear passage with a relatively large passage area. Therefore, if there is foreign matter in the intake manifold, there is a concern that the foreign matter may intrude into the pressure receiving chamber through the pressure introduction hole, thereby failing to accurately detect the intake air pressure.

[0004] In addition, as another sensor unit, there is known a pressure sensor device, which includes: a sensor storage container, which is composed of a base and a box-shaped outer shell; a pressure detection element, which is arranged in the outer shell; a pressure introduction path, which is formed by a base and a tube and is connected to the pressure introduction chamber of the pressure detection element; a temperature sensor, which is arranged in a temperature sensor storage protrusion formed on the base; and a circuit substrate, which is electrically connected to the pressure detection element and the temperature sensor and is arranged in the outer shell (for example, patent document 3).

[0005] In the pressure sensor device, a labyrinth structure with a reduced passage area is formed near the opening end of the pressure introduction passage to suppress foreign matter from entering the pressure introduction chamber through the pressure introduction passage. Therefore, in the area of ​​the labyrinth structure, there is a concern that liquids, such as blowback fuel, moisture in the intake air, blowby gas, and other liquids or liquid substances may adhere to the passage or freeze during cooling, further narrowing or clogging the passage and failing to correctly detect the intake air pressure.

[0006] [Prior art literature]

[0007] [Patent Document]

[0008] [Patent Document 1] Japanese Patent Application Publication No. 2006-194683

[0009] [Patent Document 2] Japanese Patent Application Publication No. 2005-274412

[0010] [Patent Document 3] Japanese Patent Application Laid-Open No. 11-30535 Summary of the invention

[0011] [Problems to be solved by the invention]

[0012] The present invention is made in view of the above situation, and its purpose is to provide a sensor unit and an intake system of an internal combustion engine that can inhibit or prevent the intrusion of foreign matter or the adhesion or freezing of liquids or liquids such as fuel, moisture in intake air, blowby gas, etc. and can detect the pressure of intake air with high precision.

[0013] [Technical means to solve the problem]

[0014] The sensor unit of the present invention is a sensor unit arranged in the intake pipe of an internal combustion engine, and is constructed to include: a pressure sensor for detecting the pressure of the intake air in the intake pipe; and a housing including a first housing portion for accommodating the pressure sensor, and a connecting passage for connecting the pressure-receiving chamber of the pressure sensor with the intake passage of the intake pipe, the connecting passage including: a first connecting passage having a prescribed passage length; and a second connecting passage having a passage length that is the same as the passage length of the first connecting passage and including a region whose passage area is smaller than the passage area of ​​the first connecting passage.

[0015] In the sensor unit, the following structure may also be adopted, wherein the first connecting path includes: a first path having a prescribed path area; and a first vent hole connected to the first path and having an opening area smaller than the path area of ​​the first path, and the second connecting path includes: a second path having the same path length and path area as the first path; and a second vent hole connected to the second path and having an opening area smaller than the opening area of ​​the first vent hole.

[0016] In the sensor unit, a configuration may be adopted in which the first ventilation hole and the second ventilation hole are formed as circular holes, and an inner diameter of the second ventilation hole is smaller than an inner diameter of the first ventilation hole.

[0017] In the sensor unit, a configuration may be adopted in which the first communication passage and the second communication passage are formed to open to the intake passage at positions adjacent to each other.

[0018] In the sensor unit, the pressure sensor may include a sensor body having a pressure receiving portion and a sensor cover connected to the sensor body to cover the pressure receiving portion and define a pressure receiving chamber, wherein the first vent hole and the second vent hole are formed in the sensor cover.

[0019] In the sensor unit, a configuration may be adopted in which the first vent hole and the second vent hole are formed to be biased toward a side away from a central region of the pressure receiving chamber.

[0020] In the sensor unit, the following structure may be adopted, wherein the housing includes: a housing body including a joint surface joined to the intake pipe; and a cylindrical sleeve protruding from the housing body in a predetermined axial direction, and the first passage and the second passage are formed to extend inside the sleeve.

[0021] In the sensor unit, a configuration may be adopted in which the first passage and the second passage are formed to open to the intake passage adjacent to each other at an opening end of the sleeve.

[0022] The sensor unit may include a temperature sensor for detecting the temperature of the intake air in the intake pipe, and the housing may include a second housing portion for housing the temperature sensor.

[0023] In the sensor unit, the following structure can also be adopted, wherein the shell includes: a shell body including a joint surface joined to the intake pipe; and a cylindrical sleeve protruding from the shell body in a specified axial direction, and the first passage, the second passage and the second housing portion are formed to extend within the sleeve.

[0024] In the sensor unit, the sleeve may include an end surface for opening the first passage and the second passage to the intake passage, and a front end outer wall portion formed as an outer wall protruding from the end surface and defining the second housing portion.

[0025] The sensor unit may also have a structure including a circuit substrate electrically connected to the pressure sensor and the temperature sensor, wherein the housing includes a third housing portion for housing the circuit substrate.

[0026] In the sensor unit, a configuration may be adopted in which the first housing portion, the second housing portion, and the third housing portion are sealed by filling with a mold resin material in a state where the pressure sensor, the temperature sensor, and the circuit board are disposed respectively.

[0027] In the sensor unit, a configuration may be adopted in which the housing includes a connector that exposes and surrounds a plurality of terminals connected to wirings on the circuit board and is connected to the outside.

[0028] In the sensor unit, the following structure can also be adopted, wherein the shell includes: a shell body including a joint surface joined to the intake pipe; a cylindrical sleeve protruding from the shell body in a specified axial direction; and an annular groove formed on the outer periphery of the sleeve for the annular sealing component to be embedded.

[0029] In the sensor unit, the sleeve may include 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.

[0030] The intake system of the internal combustion engine of the present invention is constructed as follows, including: an intake pipe, which defines an intake passage that guides the intake air to the combustion chamber of the internal combustion engine; a fuel injection valve, which injects fuel into the middle of the intake passage or the combustion chamber; a throttle device, which is located in the middle of the intake pipe and opens / closes the intake passage; and a sensor unit, which detects the state quantity of the intake air, and any sensor unit with the above structure is used as the sensor unit.

[0031] In the intake system of the internal combustion engine, a structure may be adopted in which the sensor unit is arranged in the intake pipe on the downstream side of the throttle device.

[0032] [Effects of the Invention]

[0033] The sensor unit having the above-described structure can suppress or prevent the intrusion of foreign matter or the adhesion or freezing of liquids or liquids such as fuel, moisture in intake air, and blowby gas, and can detect the state quantity (pressure, temperature) of the intake air with high precision. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 This 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.

[0035] Figure 2 It is a diagram showing a sensor unit according to one embodiment, and is an external perspective view of a housing as seen from the outside.

[0036] Figure 3 The figure shows the sensor unit according to one embodiment and is an external perspective view as viewed from the joining surface side of the housing joined to the intake pipe.

[0037] Figure 4 It is a diagram showing a sensor unit according to an embodiment and is a plan view of a joining surface of a housing joined to an intake pipe.

[0038] Figure 5 This is a partial cross-sectional view showing a state where a sensor unit according to an embodiment is attached to an intake pipe.

[0039] Figure 6 This is an exploded perspective view showing a sensor unit according to one embodiment disassembled and viewed from one side.

[0040] Figure 7 This is an exploded perspective view of the sensor unit according to one embodiment, which is exploded and viewed from the other side.

[0041] Figure 8 This is a perspective cross-sectional view of the sensor unit according to one embodiment, taken along a plane passing through the center line of the first ventilation hole and the center line of the second ventilation hole.

[0042] Fig. 9This is a cross-sectional view taken along a plane including a center line of a first passage forming a first communication passage and a center line of a first vent hole in a sensor unit according to an embodiment.

[0043] Fig.10 This is a cross-sectional view taken along a plane including a center line of a second passage forming a second communication passage and a center line of a second vent hole in a sensor unit according to an embodiment.

[0044] Fig.11 It is a perspective cross-sectional view of a pressure sensor (sensor main body, sensor cover) in a sensor unit according to an embodiment.

[0045] Fig.12 This is an exploded perspective view showing a sensor main body and a sensor cover that constitute a pressure sensor in a sensor unit according to an embodiment.

[0046] Fig.13 It is a cross-sectional view showing a temperature sensor accommodated in a second accommodation portion in a sensor unit according to an embodiment.

[0047] Fig.14 A schematic diagram illustrating the flow of intake air in a communication passage (a first communication passage including a first passage and a first vent hole and a second communication passage including a second passage and a second vent hole) that communicates a pressure receiving chamber with an intake passage in a sensor unit according to an embodiment.

[0048] Fig.15 A schematic diagram illustrating the flow of intake air in a communication passage (a first communication passage including a first passage and a first vent hole and a second communication passage including a second passage and a second vent hole) that communicates a pressure receiving chamber with an intake passage in a sensor unit according to another embodiment.

[0049] Fig.16 This is a schematic diagram for explaining the flow of intake air in the communication passages (first communication passage and second communication passage) that communicate the pressure receiving chamber with the intake passage in the sensor unit according to still another embodiment.

[0050] [Explanation of Symbols]

[0051] E: Internal combustion engine

[0052] C: Combustion chamber

[0053] IP: Intake pipe

[0054] Ip1: Intake passage

[0055] Ac: Air Purifier

[0056] M: Throttling device

[0057] U: Sensor unit

[0058] 10: Shell

[0059] 11: Shell body

[0060] 11a: Joint surface

[0061] 12: Sleeve

[0062] S: Axis

[0063] 12a: Large diameter cylindrical part

[0064] 12b: Small diameter cylindrical part

[0065] 12c: End face

[0066] 12d: Front end outer wall

[0067] 13: Containment Sector 1

[0068] 14: Containment Sector II

[0069] 15: Containment Sector III

[0070] Cp1: First connected path

[0071] Cp2: Second connecting path

[0072] Lo: Length of the first communication path, length of the second communication path

[0073] 16: First passage (first connecting passage)

[0074] 17: Second passage (second connecting passage)

[0075] Ls: path length of the first path, path length of the second path

[0076] 18: Annular groove

[0077] 19: Connector

[0078] 20: Pressure sensor

[0079] Rc: Pressure chamber

[0080] 21: Sensor body

[0081] 21a: Pressure part

[0082] 21b: Wire

[0083] 21c: Annular part

[0084] 22: Sensor cover

[0085] 22a: Bottom

[0086] 22b: Annular step portion

[0087] 22c: Annular outer wall portion

[0088] 22d: First ventilation hole (first communication path)

[0089] D1: Inner diameter of the first vent hole

[0090] 22e: Second ventilation hole (second communication path)

[0091] D2: Inner diameter of the second vent hole

[0092] 30: Temperature sensor

[0093] 31: Temperature sensing element

[0094] 32: Wire

[0095] 40: Circuit board

[0096] 50: terminal

[0097] 60: Molded resin

[0098] 70: Annular sealing member DETAILED DESCRIPTION

[0099] Hereinafter, embodiments of the present invention will be described with reference to the drawings.

[0100] The sensor unit U of the present invention is, for example, a sensor unit that is incorporated into an intake system of an internal combustion engine E mounted on a vehicle such as an automobile or a motorcycle.

[0101] The internal combustion engine E includes: a cylinder block 1, a piston 2, a cylinder head 3, an intake valve 4a for opening / closing an intake port 3a, an exhaust valve 4b for opening / closing an exhaust port 3b, a spark plug 5, the intake valve 4a, and a cam mechanism 6 for driving the exhaust valve 4b.

[0102] 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 throttling device M connected to the middle of the intake pipe Ip, an air cleaner Ac connected to the upstream end of the intake pipe Ip, a fuel injection valve Iv arranged on the downstream side of the intake pipe Ip, and a sensor unit U arranged in the intake pipe Ip at a position downstream of the throttling device M and upstream of the fuel injection valve Iv.

[0103] The intake pipe Ip defines an intake passage Ip1 for guiding intake air to the combustion chamber C of the internal combustion engine E. As shown in FIG.

[0104] The throttle device M includes a butterfly-type throttle valve m1 for opening and closing the intake passage Ip1 , a bypass passage m2 for bypassing the throttle valve m1 , and the like.

[0105] The exhaust system of the internal combustion engine E includes an exhaust pipe Ep connected to the cylinder head 3 so as to communicate with the exhaust port 3b, a catalytic converter Cc disposed in the middle of the exhaust pipe Ep, an oxygen sensor Os, and the like.

[0106] like Figures 2 to 13 As shown, the sensor unit U according to one embodiment includes a housing 10 , a pressure sensor 20 , a temperature sensor 30 , a circuit board 40 , a plurality of terminals 50 , a mold resin material 60 , and an annular sealing member 70 .

[0107] The housing 10 is molded using a resin material and includes a housing body 11 , a cylindrical sleeve 12 , a first housing portion 13 , a second housing portion 14 , a third housing portion 15 , a first passage 16 , a second passage 17 , an annular groove 18 , and a connector 19 .

[0108] like Figure 3 and Figure 5 As shown, the housing body 11 has a flat joint surface 11a joined to the outer wall of the intake pipe Ip, and a flange portion 11b including a circular hole 11b1 for passing a fastening screw (not shown) screwed into a screw hole of the intake pipe Ip.

[0109] The sleeve 12 is formed into a two-stage cylindrical shape extending in the axis S direction perpendicular to the joint surface 11a of the housing 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.

[0110] Moreover, if Figure 5 As shown, when 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 the small diameter cylindrical portion 12b slightly protrudes into the intake passage Ip1 of the intake pipe Ip.

[0111] like Figure 6 , Figures 8 to 10 As shown, the first housing portion 13 is a region for housing and holding the pressure sensor 20 , and is formed in an inner region of the housing body 11 .

[0112] like Fig.13 As shown, the second housing portion 14 is an area for housing the temperature sensor 30, and is formed in an area extending from the inner area of ​​the shell body 11 in the inner area of ​​the sleeve 12 until it reaches the inner side of the hemispherical front end outer wall portion 12d of the outer wall protruding from the end face 12c of the sleeve 12.

[0113] like Figure 6 As shown, the third housing portion 15 is a region for housing and holding the circuit board 40 , and is formed in an inner region of the housing body 11 .

[0114] like Figure 8and Fig. 9 As shown, the first passage 16 is formed to have a predetermined passage length Ls inside the sleeve 12 and to extend linearly along the axis S direction from the end surface 12c defining the open end of the sleeve 12 to the first receiving portion 13 of the housing body 11 with a certain passage area. Moreover, the inner opening end of the first passage 16 is connected to the first vent hole 22d formed in the sensor cover 22 of the pressure sensor 20.

[0115] like Figure 8 and Fig.10 As shown, the second passage 17 is formed to have the same passage length Ls as the first passage 16 on the inner side of the sleeve 12 and to extend linearly from the end surface 12c along the axis S direction to the first accommodation portion 13 of the housing body 11 with the same passage area as the passage area of ​​the first passage 16 adjacent to the first passage 16. In addition, the inner opening end of the second passage 17 is connected to the second vent hole 22e formed in the sensor cover 22 of the pressure sensor 20.

[0116] 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. Furthermore, 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 via the first vent 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 via the second vent hole 22e.

[0117] like Figure 5 , Figure 7 , Figure 8 As shown, the annular groove 18 is formed in the region of the large diameter cylindrical portion 12 a of the sleeve 12 of the housing 10 in a manner of annularly thinning the outer circumference so that the annular sealing member 70 can be inserted.

[0118] like Fig. 9 As shown, the connector 19 is formed to protrude from the housing body 11 in a direction perpendicular to the axis S, and exposes and surrounds a plurality of (four in this case) terminals 50 connected to the circuit board 40 , and is connected to the outside.

[0119] like Fig.11 and Fig.12 As shown, the pressure sensor 20 is composed of a sensor body 21 and a sensor cover 22 .

[0120] The sensor main body 21 includes a pressure receiving portion 21 a such as a diaphragm including a semiconductor strain gauge, a lead wire 21 b extending from the pressure receiving portion 21 a , and an annular portion 21 c surrounding the pressure receiving portion 21 a .

[0121] The sensor cover 22 includes a disc-shaped bottom 22a, an annular step portion 22b, an annular outer wall portion 22c, a first vent hole 22d, and a second vent hole 22e. The sensor cover 22 is connected to the sensor body 21 by embedding the annular portion 21c in the annular outer wall portion 22c, so as to function as a protective cover covering the pressure receiving portion 21a and define the pressure receiving chamber Rc.

[0122] The pressure sensor 20 outputs a change in resistance in the form of an electric signal according to the amount of deformation of the pressure receiving portion 21 a caused by the pressure of the intake air introduced into the pressure receiving chamber Rc through the first vent hole 22 d and the second vent hole 22 e .

[0123] In addition, the pressure sensor 20 detects the pressure of the intake air flowing in the intake passage Ip1 on the downstream side of the throttle device M in a state where the sensor unit U is assembled to the intake pipe Ip.

[0124] Here, the first ventilation hole 22d is formed as follows Fig. 9 As shown in FIG. 1 , the passage length Lc may be equivalent to the wall thickness of the bottom 22a or as shown in FIG. Fig.11 As shown, the first passage 16 is in the form of a circular hole whose opening area (inner diameter D1 ) is sufficiently smaller than the passage area of ​​the first passage 16 , and communicates with the first passage 16 .

[0125] The second vent hole 22e is formed as follows Fig.10 As shown in FIG. 1 , the passage length Lc may be equivalent to the wall thickness of the bottom 22a or as shown in FIG. Fig.11 As shown, it is a circular hole having an opening area (inner diameter D2) sufficiently smaller than the passage area of ​​the second passage 17 and smaller than the opening area of ​​the first vent hole 22d (ie, D1>D2), and communicates with the second passage 17.

[0126] 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.

[0127] The passage length Lc of the first ventilation hole 22d and the second ventilation hole 22e is the same as the plate thickness of the bottom portion 22a, and is, for example, approximately 1.0 to 1.7 times the inner diameters D1 and D2.

[0128] According to the structure, the connecting passage that connects the pressure chamber Rc of the pressure sensor 20 with the intake passage Ip1 of the intake pipe Ip is formed to include: a first connecting passage Cp1, having a specified passage length Lo (= Ls + Lc); and a second connecting passage Cp2, having the same passage length Lo (= Ls + Lc) as the first connecting passage Cp1, and including a region (second ventilation hole 22e) whose passage area is smaller than the passage area of ​​the first connecting passage Cp1.

[0129] Specifically, the first connecting passage Cp1 is formed to include: a first passage 16 having a specified passage length Ls and a passage area; and a first ventilation hole 22d, which is connected to the first passage 16 and has a passage length Lc and an opening area smaller than the passage area of ​​the first passage 16. The second connecting passage Cp2 is formed to include: a second passage 17 having the same passage length Ls and passage area as the first passage 16; and a second ventilation hole 22e, which is connected to the second passage 17 and has a passage length Lc and an opening area smaller than the opening area of ​​the first ventilation hole 22d.

[0130] Here, the first vent hole 22d and the second vent hole 22e are formed to have an opening area smaller than the passage area of ​​the first passage 16 and the second passage 17, thereby playing a role in preventing foreign matter mixed in the intake air from entering the pressure receiving chamber Rc (trapping function).

[0131] In particular, Fig.11 As shown in FIG. 1 , the first vent hole 22d and the second vent hole 22e are formed to be offset by a distance Cd to the side away from the central region including the center line CL of the pressure receiving chamber Rc.

[0132] Therefore, even if foreign matter or the like intrudes into the pressure-receiving chamber Rc through the first vent hole 22d and the second vent hole 22e, the foreign matter or the like can be prevented from directly colliding with the pressure-receiving portion 21a, and the pressure caused by the impact of the foreign matter or the like or the influence of the dynamic pressure corresponding to the flow rate of the intake air can be suppressed or prevented, thereby detecting the pressure with high precision.

[0133] In addition, the opening area (inner diameter D2) of the second ventilation hole 22e is formed to be smaller than the opening area (inner diameter D1) of the first ventilation hole 22d.

[0134] Usually, the pressure loss corresponding to the channel resistance is ΔP (Pa), the friction coefficient of the channel is λ (dimensionless), the channel length is L (m), the inner diameter of the channel is D (m), and the density of the fluid is ρ (kg / m 3 ), when the flow velocity is V (m / s), it is expressed as ΔP = λLρV 2 / 2D. That is, the pressure loss ΔP is inversely proportional to the inner diameter D of the passage and is proportional to the passage length L. Therefore, if the passage area or the opening area becomes smaller, the pressure loss becomes larger, that is, the passage resistance becomes larger, and the fluid becomes difficult to flow.

[0135] Here, assuming that the inner diameter of the first vent hole 22d is D1, the path length of the first vent hole 22d is L1, the inner diameter of the second vent hole 22e is D2, and the path length of the second vent hole 22e is L2, since Lc=L2=L1, D2<D1, the pressure loss ΔP2 of the second vent hole 22e is greater than the pressure loss ΔP1 of the first vent hole 22d (ΔP2>ΔP1), that is, the path resistance of the second vent hole 22e is greater than the path resistance of the first vent hole 22d.

[0136] Therefore, the passage resistance (pressure loss) of the second communication passage Cp2 connected to the pressure receiving chamber Rc via the second passage 17 and the second vent hole 22e is greater than the passage resistance (pressure loss) of the first communication passage Cp1 connected to the pressure receiving chamber Rc via the first passage 16 and the first vent hole 22d.

[0137] According to the structure, when negative pressure is generated near the end face 12c of the sleeve 12 as the piston 2 descends, a trigger flow is generated with the pressure chamber Rc as the starting point, which is sucked from the first connecting passage Cp1 with small passage resistance into the intake passage Ip1, and a follow-up flow is generated following this, which flows from the intake passage Ip1 via the second connecting passage Cp2 into the pressure chamber Rc.

[0138] Thus, in the sensor unit U, by generating a flow of intake air in the communication passage (the first communication passage Cp1 and the second communication passage Cp2), it is possible to suppress or prevent liquid or liquid-like substances such as fuel, moisture in intake air, and blowby gas from adhering to the communication passage, or to prevent the adhering substances from freezing, etc. Therefore, the pressure sensor 20 can detect the pressure of the intake air guided to the pressure receiving chamber Rc with high accuracy.

[0139] Here, the first communication passage Cp1 and the second communication passage Cp2 are formed to open to the intake passage Ip1 at adjacent positions. That is, the first passage 16 and the second passage 17 are formed to open adjacent to each other at the opening end (end surface 12 c ) of the sleeve 12 .

[0140] As a result, the pressure environments in the open ends of the first connecting passage Cp1 and the second connecting passage Cp2 become equal, so the difference in the passage resistance (pressure loss) of the first connecting passage Cp1 and the passage resistance (pressure loss) of the second connecting passage Cp2 can be easily determined only by the difference (difference in opening area) between the first vent hole 22d and the second vent hole 22e.

[0141] Furthermore, since the first vent hole 22d and the second vent hole 22e are formed as circular holes, a desired passage resistance (pressure loss) can be easily set by calculation compared to the case of irregular-shaped holes.

[0142] The pressure sensor 20 having the above structure is arranged in the mold and molded integrally when the housing 10 is molded from a resin material using a mold so as to be accommodated in the first accommodation portion 13 of the housing body 11. Then, the lead wire 21b of the pressure sensor 20 is electrically connected to the circuit board 40, and then covered and sealed with the molded resin material 60.

[0143] Alternatively, the pressure sensor 20 may be embedded in the first housing portion 13 of the housing 10 that is previously molded from a resin material in a subsequent process and sealed with the mold resin material 60 .

[0144] like Figure 6 , Figure 7 , Fig.13 As shown, the temperature sensor 30 is a lead type sensor, for example, composed of a temperature sensing element 31 such as a thermistor and a wire 32 extending from the temperature sensing element 31. That is, the temperature sensor 30 is inserted into the second receiving portion 14 of the housing 10, the temperature sensing element 31 is arranged in the inner area of ​​the front end outer wall portion 12d of the sleeve 12, and the wire 32 is electrically connected to the circuit substrate 40, and then covered and sealed by the molded resin material 60.

[0145] Then, in a state where the sensor unit U is assembled to the intake pipe Ip, the temperature sensor 30 detects the temperature of the intake air flowing through the intake passage Ip1 on the downstream side of the throttle device M.

[0146] The surface of the circuit substrate 40 is packaged with printed wiring and various electronic components (not shown), such as Figure 6 and Figure 7 As shown, it includes three through holes 41 electrically connected to the wires 21 b of the pressure sensor 20 and four through holes 42 electrically connected to the wires 32 of the temperature sensor 30 .

[0147] Furthermore, the circuit board 40 is disposed in the third housing portion 15 of the case body 11 during assembly, the lead wires 21 b and the lead wires 32 are electrically connected, and then covered and sealed with the mold resin material 60 .

[0148] The terminal 50 is formed of a conductive metal material, such as Fig. 9 and Fig.10 As shown, it is arranged to be embedded in the housing body 11 , one end of which is connected to the through hole 42 of the circuit board 40 , and the free end side is exposed in the connector 19 and is surrounded by the connector 19 .

[0149] The molded resin material 60 is a sealing material such as epoxy resin, and is injected into the housing 10 and cured in a manner to fill the gap space while the pressure sensor 20, the temperature sensor 30 and the circuit board 40 are respectively accommodated and held in the first accommodation portion 13, the second accommodation portion 14 and the third accommodation portion 15 of the housing 10.

[0150] Therefore, if Figure 8 , Fig. 9 , Fig.10 , Fig.13 As shown, the first housing portion 13 , the second housing portion 14 , and the third housing portion 15 are sealed by filling with a mold resin material 60 in a state where the pressure sensor 20 , the temperature sensor 30 , and the circuit board 40 are disposed respectively.

[0151] The annular sealing member 70 is made of a rubber material having excellent heat resistance and swelling resistance, such as Fig.13 and Fig.14 As shown, it is formed in an annular shape and is fitted into an annular groove 18 formed on the outer periphery of the sleeve 12 of the housing 10 .

[0152] Moreover, if Figure 5 As shown, in a state where the sensor unit U is assembled to the intake pipe Ip, the annular seal member 70 seals between the fitting hole H of the intake pipe Ip and the sleeve 12 .

[0153] Next, in the internal combustion engine E including the sensor unit U, the detection operation of the sensor unit U will be described.

[0154] First, when the internal combustion engine E is in the idling range, the throttle valve m1 closes the intake passage Ip1, and the intake air flowing in the intake passage Ip1 flows through the bypass passage m2 to bypass the throttle valve m1 and flows out to the downstream intake passage Ip1 again.

[0155] On the other hand, when the internal combustion engine E is in an operation range other than the idling operation range, the throttle valve m1 is in a predetermined opening range, and the intake passage Ip1 is opened.

[0156] Therefore, the intake air flowing through the intake passage Ip1 flows through the intake passage Ip1 and is sucked into the internal combustion engine E without passing through the bypass passage m2.

[0157] Then, in the operating state of the internal combustion engine E, the pressure and temperature as state quantities of the intake air are detected by the sensor unit U on the downstream side of the throttle device M.

[0158] That is, the temperature of the intake air is detected by the temperature sensor 30. Specifically, since the temperature sensing element 31 is arranged near the inner side of the front end outer wall portion 12d protruding from the end surface 12c of the sleeve 12, the temperature of the intake air flowing in the intake passage Ip1 is detected in an area away from the wall surface of the intake pipe Ip. As a result, the influence of the wall surface temperature of the intake pipe Ip can be suppressed.

[0159] The pressure sensor 20 detects the pressure of the intake air flowing in the intake passage Ip1 via the first communication passage Cp1 including the first passage 16 and the first vent hole 22d and the second communication passage Cp2 including the second passage 17 and the second vent hole 22e.

[0160] Specifically, when comparing the ease of flow in the first communication passage Cp1 and the second communication passage Cp2, since the second communication passage Cp2 includes the second vent hole 22e having a large passage resistance (pressure loss), the flow in the first communication passage Cp1 is easier than in the second communication passage Cp2.

[0161] Therefore, if Fig.14 As shown, the intake air in the pressure receiving chamber Rc is sucked into the intake passage Ip1 via the first communication passage Cp1, and in conjunction with the flow of the intake air, the intake air in the intake passage Ip1 flows into the pressure receiving chamber Rc via the second communication passage Cp2.

[0162] By continuously performing the above flow, intake air is supplied to the pressure receiving chamber Rc, and the pressure of the intake air is detected by the pressure receiving portion 21a. In addition, by the above flow of intake air, liquids or liquids such as fuel, moisture in the intake air, and blowby gas can be suppressed or prevented from adhering to the inner wall surfaces of the first communication passage Cp1 and the second communication passage Cp2, thereby suppressing or preventing them from freezing. In addition, by the first vent hole 22d and the second vent hole 22e, foreign matter can be prevented from intruding into the pressure receiving chamber Rc.

[0163] As described above, 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 detected information is acquired as control information of the electronic control unit (ECU), thereby controlling the internal combustion engine E appropriately.

[0164] As described above, the sensor unit U is constructed to include: a pressure sensor 20 for detecting the pressure of the intake air in the intake pipe Ip; and a housing 10, including a first housing portion 13 for accommodating the pressure sensor 20, and a connecting path for connecting the pressure chamber Rc of the pressure sensor 20 with the intake passage Ip1 of the intake pipe Ip, the connecting path including: a first connecting path Cp1 having a prescribed passage length Lo; and a second connecting path Cp2 having the same passage length Lo as the first connecting path Cp1, and including a region (a second vent 22e) having a passage area smaller than the passage area of ​​the first connecting path Cp1.

[0165] Accordingly, 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 flow of intake air 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. That is, by generating a trigger flow in the first communication passage Cp1, a flow is also generated in the second communication passage Cp2 in conjunction with the flow, thereby generating a flow in the entire communication passage.

[0166] Therefore, in the regions of the first communication passage Cp1 , the pressure receiving chamber Rc, and the second communication passage Cp2 , it is possible to suppress or prevent the occurrence of stagnation in the flow of the intake air.

[0167] Therefore, the intake air in the intake passage Ip1 can be always supplied to the pressure receiving chamber Rc, and the intrusion of foreign matter can be suppressed or prevented, or the adhesion or freezing of liquids or liquid substances such as fuel, moisture in the intake air, and blowby gas can be suppressed or prevented, and the pressure of the intake air can be detected with high precision through the pressure receiving portion 21a.

[0168] In the embodiment described, Figure 5 and Fig.14 1 , the sensor unit U is mounted in a state where the end surface 12 c of the sleeve 12 slightly protrudes from the inner wall surface of the intake pipe Ip, but the present invention is not limited to this.

[0169] For example, the end surface 12c of the sleeve 12 of the sensor unit U may be Fig.15 As shown in the figure, it is arranged in a state protruding to the vicinity of the center of the intake passage Ip1.

[0170] Normally, the flow velocity of the intake air in the intake passage Ip1 differs depending on the location, for example, it becomes faster in the central area and slower near the wall. The first connecting passage Cp1 and the second connecting passage Cp2 open on the same end surface 12c in a mutually adjacent state, and therefore are not affected by the flow velocity, i.e., the pressure, which depends on the location in the intake passage Ip1. The flow of intake air can be generated by utilizing only the difference in passage resistance (pressure loss) between the first connecting passage Cp1 and the second connecting passage Cp2.

[0171] In the embodiment, as a connecting passage including a first connecting passage having a prescribed passage length, and a second connecting passage having the same passage length as the first connecting passage and including a region with a passage area smaller than that of the first connecting passage, a form including a first connecting passage Cp1 and a second connecting passage Cp2 is shown, wherein the first connecting passage Cp1 includes a first passage 16 having a prescribed passage area, and a first vent 22d connected to the first passage 16 and having an opening area smaller than that of the first passage 16, and the second connecting passage Cp2 includes a second passage 17 having the same passage length Ls and passage area as those of the first passage 16, and a second vent 22e connected to the second passage 17 and having an opening area smaller than that of the first vent 22d, but the present invention is not limited thereto.

[0172] For example, the following form can also be adopted: Fig.16 As shown, the opening areas of the first vent hole 122d and the second vent hole 122e are formed to be the same, and a region Pa having a passage area smaller than the passage area of ​​the first connecting passage Cp1 (here, the passage area of ​​the first passage 16 and the opening area of ​​the first vent hole 122d) is formed in the middle of the second passage 17.

[0173] In the described form, as in the above, the passage resistance (pressure loss) of the second connecting passage Cp2 is greater than the passage resistance (pressure loss) of the first connecting passage Cp1, a trigger flow is generated in the first connecting passage Cp1 that is sucked out from the pressure-receiving chamber Rc to the intake passage Ip1, and a follow-up flow is generated in the second connecting passage Cp2 that flows from the intake passage Ip1 into the pressure-receiving chamber Rc.

[0174] In the above embodiment, the first vent hole 22d and the second vent hole 22e formed in the sensor cover 22 are shown as the first vent hole and the second vent hole, but the present invention is not limited thereto and the first vent hole and the second vent hole formed in the sleeve of the housing may be used.

[0175] For example, the first ventilation hole may be provided at a position dividing the first passage into two, and the second ventilation hole may be provided at a position dividing the second passage into two.

[0176] In addition, as the first vent hole and the second vent hole, the first vent hole 22d and the second vent hole 22e in the form of circular holes are shown, but as long as the pressure loss of the second vent hole is greater than the pressure loss of the first vent hole, the first vent hole and the second vent hole in a shape other than a circular hole may also be used.

[0177] In the embodiment, the first connecting passage Cp1 and the second connecting passage Cp2 are formed to open to the intake passage Ip1 at positions adjacent to each other, that is, the first passage 16 and the second passage 17 are formed to open adjacent to each other at the open end (end face 12c) of the sleeve 12, but it is not limited to this. As long as the difference in passage resistance (pressure loss) can be set between the first connecting passage and the second connecting passage without being affected by the flow velocity (pressure) distribution in the intake passage Ip1, other forms may also be used.

[0178] In the embodiment, a sensor unit U is shown which includes a pressure sensor 20 and a temperature sensor 30 and includes a circuit substrate 40 which electrically connects the pressure sensor 20 and the temperature sensor 30. However, the present invention is not limited to this. A sensor unit may be used which eliminates the temperature sensor 30 and includes the circuit substrate 40 and the pressure sensor 20, or may be used which eliminates the temperature sensor 30 and the circuit substrate 40 and includes only the pressure sensor 20.

[0179] In the embodiment, a sensor unit U is shown which includes a sleeve 12 forming a first passage 16 and a second passage 17 as a part of a first connecting passage and a second connecting passage for connecting a pressure receiving chamber Rc of a pressure sensor 20 with an intake passage Ip1 of an intake pipe Ip. However, the present invention is not limited to this. If the structure includes the first connecting passage and the second connecting passage, a sensor unit including a shell in other forms other than a sleeve may also be used.

[0180] In the embodiment, as a cylindrical sleeve protruding from the shell body 11 in the direction of the axis S, a sleeve 12 having a two-stage cylindrical shape including a large diameter cylindrical portion 12a and a small diameter cylindrical portion 12b is shown, but it is not limited to this, and a cylindrical sleeve with the same outer diameter may also be used.

[0181] In the above embodiment, the pressure sensor 20 including a semiconductor strain gauge is shown as the pressure sensor, but the present invention is not limited to this. An electrostatic capacitance type pressure sensor may be used. As long as it includes a pressure receiving portion that receives the pressure of the intake air, other types and forms of pressure sensors may be used.

[0182] In addition, in the embodiment, as a pressure sensor, a pressure sensor 20 including a sensor body 21 and a sensor cover 22 is shown, but it is not limited to this. A pressure sensor without a sensor cover and with the pressure-receiving portion exposed to the outside may be used, or a pressure sensor may be provided in a first housing portion that accommodates the pressure sensor, and the pressure sensor and the inner wall surface of the first housing portion of the shell cooperate to define a pressure-receiving chamber.

[0183] As described above, the sensor unit of the present invention can inhibit or prevent the intrusion of foreign matter or can inhibit or prevent the adhesion or freezing of liquids or liquid substances such as fuel, moisture in the intake air, and blowby gas, and can detect the state quantity (pressure, temperature) of the intake air with high precision. Therefore, it can of course be applied to the intake system of internal combustion engines of automobiles, motorcycles, etc., and is also useful in internal combustion engines of other vehicles.

Claims

1. A sensor unit, arranged in an intake pipe of an internal combustion engine, wherein the sensor unit is characterized by comprising: A pressure sensor for detecting the pressure of the intake air in the intake pipe; as well as The housing includes a first housing portion for housing the pressure sensor and a communication passage for connecting the pressure receiving chamber of the pressure sensor with the 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 that of the first communication passage.

2. The sensor unit according to claim 1, characterized in that 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 that of the first vent hole.

3. The sensor unit according to claim 2, characterized in that The first vent hole and the second vent hole are formed as circular holes. An inner diameter of the second vent hole is smaller than an inner diameter of the first vent hole.

4. The sensor unit according to claim 1, characterized in that The first communication passage and the second communication passage are formed to open to the intake passage at positions adjacent to each other.

5. The sensor unit according to claim 2, characterized in that The pressure sensor includes: a sensor body having a pressure receiving portion; and a sensor cover connected to the sensor body to cover the pressure receiving portion and define the pressure receiving chamber. The first vent hole and the second vent hole are formed in the sensor cover.

6. The sensor unit according to claim 2, characterized in that The first vent hole and the second vent hole are formed to be biased toward a side away from a central area of ​​the pressure receiving chamber.

7. The sensor unit according to claim 2, characterized in that The housing includes: a housing body including a joint surface to be joined to the intake pipe; and a cylindrical sleeve protruding from the housing body in a predetermined axial direction. The first passage and the second passage are formed to extend inside the sleeve.

8. The sensor unit according to claim 7, characterized in that The first passage and the second passage are formed to open to the intake passage adjacent to each other at an open end of the sleeve.

9. The sensor unit according to claim 2, characterized in that comprising a temperature sensor for detecting the temperature of the intake air in the intake pipe, The housing includes a second receiving portion for receiving the temperature sensor.

10. The sensor unit according to claim 9, characterized in that The housing includes: a housing body including a joint surface to be joined to the intake pipe; and a cylindrical sleeve protruding from the housing body in a predetermined axial direction. The first passage, the second passage, and the second housing portion are formed to extend inside the sleeve.

11. The sensor unit according to claim 10, characterized in that The sleeve includes an end surface for the first passage and the second passage to open to the intake passage, and a front end outer wall portion formed as an outer wall protruding from the end surface and defining the second housing portion.

12. The sensor unit according to claim 9, characterized in that comprising a circuit substrate electrically connected to the pressure sensor and the temperature sensor, The housing includes a third housing portion for housing the circuit substrate.

13. The sensor unit according to claim 12, characterized in that The first housing portion, the second housing portion, and the third housing portion are sealed by being filled with a mold resin material in a state where the pressure sensor, the temperature sensor, and the circuit board are arranged respectively.

14. The sensor unit according to claim 13, characterized in that The housing includes a connector that exposes and surrounds a plurality of terminals connected to wirings on the circuit substrate and is connected to the outside.

15. The sensor unit according to claim 1, characterized in that The housing includes: a housing body including a joint surface joined to the intake pipe; a cylindrical sleeve protruding from the housing body in a predetermined axial direction; and an annular groove formed on the outer periphery of the sleeve for an annular sealing member to be embedded.

16. The sensor unit according to claim 15, characterized in that The sleeve includes: a large diameter cylindrical portion, which is continuous with the joint surface; and a small diameter cylindrical portion, which is continuous with the large diameter cylindrical portion. The annular groove is formed in the large-diameter cylindrical portion.

17. An intake system for an internal combustion engine, characterized in that: include: An intake pipe defines an intake passage for guiding intake air to a combustion chamber of an internal combustion engine; a fuel injection valve that injects fuel into the middle of the intake passage or into the combustion chamber; A throttle device is disposed in the middle of the intake pipe to open / close the intake passage; as well as The sensor unit detects the state quantity of the intake air. The sensor unit is the sensor unit according to any one of claims 1 to 16.

18. The air intake system of an internal combustion engine according to claim 17, characterized in that: The sensor unit is arranged in the intake pipe on the downstream side of the throttle device.

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