internal combustion engine

Abstract

The internal combustion engine is provided with a blowby gas treatment device. A joint portion having a connection port for connecting a connecting pipe and a throttling portion whose passage cross-sectional area is smaller than that of the connection port is provided on a cylinder head cover of the internal combustion engine. The joint portion is communicated with the interior of the cylinder head, and the space in the joint portion becomes an oil separator. The pressure sensor is connected to the space in the oil separator via a connecting passage. The connecting passage is composed of a first pipe, a second pipe, and a chamber having a first connection port for connecting the first pipe and a second connection port for connecting the second pipe. Furthermore, the first connection port and the second connection port open in the same direction in the chamber.

Description

Technical Field

[0001] The present invention relates to an internal combustion engine provided with a blow-by gas treatment device. Background Art

[0002] Japanese Patent Application Laid-Open No. 2019-132233 discloses an internal combustion engine including a blow-by gas treatment device for treating blow-by gas leaking from a combustion chamber to a crankcase by causing the blow-by gas to flow back from a cylinder head cover to an intake passage.

[0003] The cylinder head cover of the internal combustion engine is provided with a pipe joint connected to a connecting pipe connected to an intake passage. A throttling portion is provided inside the pipe joint. Thus, the connecting pipe is connected to the inside of the cylinder head cover via the throttling portion. And, the other end of the connecting pipe is connected to the intake passage. Thus, the inside of the cylinder head cover and the intake passage are connected through the connecting pipe. In addition, a connecting pipe portion connected to a pressure sensor is provided between the portion of the pipe joint to which the connecting pipe is connected and the throttling portion.

[0004] When the connecting pipe is loosened from the pipe joint or the intake passage, the pressure value detected by the pressure sensor changes suddenly. Therefore, by monitoring the pressure value detected by the pressure sensor, it is possible to detect that the connecting pipe is loose. In addition, when the connecting pipe is damaged, the pressure value detected by the pressure sensor also changes suddenly. Therefore, by monitoring the pressure value detected by the pressure sensor, it is also possible to detect damage to the connecting pipe. Summary of the invention

[0005] Intake pulsation occurs during the operation of the internal combustion engine. Therefore, if the intake pulsation propagates through the connecting pipe, the pressure value detected by the pressure sensor also changes due to the influence of the intake pulsation. As a result, it is impossible to properly detect abnormalities in the connecting pipe.

[0006] Means for solving the above-mentioned problems and their effects are described below.

[0007] An internal combustion engine for solving the above-mentioned problem is an internal combustion engine equipped with a blow-by gas treatment device for treating blow-by gas leaking from a combustion chamber to a crankcase by returning the blow-by gas to an intake passage. In the internal combustion engine, a joint portion is provided on a cylinder head cover, and the joint portion has a connection port for connecting a connecting pipe connected to the intake passage and a throttle portion having a passage cross-sectional area smaller than the connection port. In addition, in the internal combustion engine, the joint portion is connected to the inside of the cylinder head via the throttle portion, and a space between the throttle portion and the connection port in the joint portion becomes an oil separator for separating oil contained in the blow-by gas. In addition, the internal combustion engine is equipped with a pressure sensor connected to the space in the oil separator in the joint portion via a connecting passage and detecting the pressure in the oil separator. In addition, the connecting passage is composed of a first pipe connected to the joint portion, a second pipe connected to the pressure sensor, and a chamber having a first connection port for connecting the first pipe and a second connection port for connecting the second pipe. Furthermore, in this internal combustion engine, the first connection port and the second connection port open in the chamber in the same direction.

[0008] According to the above structure, the pressure sensor is connected to the joint part via the first piping, the chamber, and the second piping. Therefore, even if the intake pulsation propagates to the joint part, the intake pulsation is mitigated when passing through the chamber. In addition, the first connection port and the second connection port open in the same direction in the chamber. Therefore, the intake pulsation propagated into the chamber through the first piping is not easy to propagate to the second connection port. Therefore, the change in the pressure value detected by the pressure sensor caused by the influence of the intake pulsation can be suppressed. Therefore, by monitoring the pressure value detected by the pressure sensor, the abnormality of the connecting piping can be properly detected.

[0009] In one embodiment of the internal combustion engine, the chamber forms a space surrounded by a ceiling, a floor surface, and a side wall. Furthermore, the first connection port and the second connection port are each provided on the side wall. In addition, the first connection port and the second connection port are opened toward a side wall of the chamber that is opposite to the side wall on which the first connection port and the second connection port are provided.

[0010] The pressure wave propagating into the chamber through the first connection port is easily attenuated if it collides with the side wall of the chamber. According to the above configuration, the pressure wave propagating through the first connection port collides with the side wall and is attenuated, thereby alleviating the influence of intake air pulsation on the pressure value detected by the pressure sensor.

[0011] In one aspect of the internal combustion engine, the first connection port and the second connection port open toward a common side wall in the chamber, and a distance from the first connection port to the common side wall is shorter than a distance from the second connection port to the common side wall.

[0012] The shorter the distance between the side wall and the first connection port, the easier it is for the pressure wave to be attenuated by colliding with the side wall. However, if the second connection port is also located near the side wall, the pressure wave that collides with the side wall and bounces back is easy to enter the second connection port.

[0013] In contrast, if the first connection port is close to the opposite side wall but the second connection port is away from the side wall as in the above structure, the rebound effect of the pressure wave from the side wall can be suppressed. Therefore, the pressure wave propagating from the first connection port into the chamber can collide with the side wall and effectively alleviate the effect of the intake pulsation.

[0014] In one aspect of the internal combustion engine, the second connection port is located vertically above the first connection port in a posture in which the internal combustion engine is mounted.

[0015] Blow-by gas contains oil mist and water. If oil or water derived from the oil mist and water adheres to the pressure sensor, the detection sensitivity of the pressure sensor decreases.

[0016] According to the above configuration, since the second connection port is located vertically above the first connection port, even if oil or water enters the chamber through the first connection port by the flow of blowby gas, it is difficult to reach the second connection port. Therefore, it is possible to suppress oil or water from adhering to the pressure sensor.

[0017] In one aspect of the internal combustion engine, the floor surface is inclined so as to be located vertically downward as the floor surface approaches the first connection port from the second connection port side in a posture in which the internal combustion engine is mounted.

[0018] If the oil mist and water that have entered the chamber collide with the wall of the chamber and separate from the gas, they become droplets and drip onto the floor of the chamber. According to the above structure, the oil and water that have dripped onto the floor flow down toward the first connection port by their own weight. Therefore, the water and oil generated in the chamber can be discharged from the first connection port.

[0019] In one aspect of the internal combustion engine, the joint portion is provided with a third connection port to which the first pipe is connected. The third connection port is located vertically below the first connection port when the internal combustion engine is mounted, and the first pipe is inclined so that the first pipe is located vertically above the first connection port when the internal combustion engine is mounted as it moves from the third connection port side to the first connection port side.

[0020] According to the above configuration, the first pipe has an upward slope from the third connection port toward the first connection port. Therefore, even if oil or water enters the first pipe from the third connection port by the flow of blowby gas, it is easy to flow down in the first pipe by its own weight and return to the joint.

[0021] Furthermore, when the oil and water in the chamber are discharged from the first connection port into the first pipe, the oil and water are easily discharged into the first pipe and discharged toward the joint portion. This can prevent the oil and water from adhering to the pressure sensor. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Features, advantages and technical and industrial significance of exemplary embodiments of the present invention will be described below with reference to the accompanying drawings, in which like numerals represent like elements, and in which:

[0023] Figure 1 This is a schematic diagram showing one embodiment of an internal combustion engine.

[0024] Figure 2 It is a top view of the cylinder head cover of the internal combustion engine according to this embodiment.

[0025] Figure 3 It is a side view of the joint portion and the cavity in the above-mentioned cylinder head cover.

[0026] Figure 4 It is along Figure 3 Cross-sectional view along line 4-4.

[0027] Figure 5 It is along Figure 3 Cross-sectional view along line 5-5. DETAILED DESCRIPTION

[0028] In the following, regarding one embodiment of the internal combustion engine, refer to Figure 1 to Figure 5 To explain.

[0029] <Structure of Internal Combustion Engine 90>

[0030] like Figure 1 As shown, the internal combustion engine 90 includes a cylinder block 91 , a cylinder head 97 , a cylinder head cover 98 , a crankcase 95 , and an oil pan 96 .

[0031] A plurality of cylinders 92 are formed in the cylinder block 91. Each of the cylinders 92 houses a piston 94 that reciprocates in conjunction with the rotation of a crankshaft housed in a crankcase 95.

[0032] The intake valve and exhaust valve of the internal combustion engine 90 are assembled in the cylinder head 97. In addition, the cylinder head cover 98 mounted on the cylinder head 97 covers the camshaft that drives the intake valve and the exhaust valve. The cylinder head cover 98 is formed of a resin material. A baffle is mounted on the cylinder head 97 side of the cylinder head cover 98.

[0033] The oil pan 96 stores oil for lubricating various parts of the internal combustion engine 90 and the hydraulic drive mechanism.

[0034] The internal combustion engine 90 includes a combustion chamber 93 defined by a cylinder 92, a piston 94, and a cylinder head 97. The internal combustion engine 90 includes an intake passage 71 for introducing intake air into the combustion chamber 93. The internal combustion engine 90 also includes an exhaust passage 78 for discharging a mixture burned in the combustion chamber 93 as exhaust gas.

[0035] The internal combustion engine 90 includes a supercharger 80. A turbine 82 of the supercharger 80 is disposed in the exhaust passage 78. In addition, a compressor 81 connected to the turbine 82 is disposed in the intake passage 71.

[0036] An air filter 72 is provided in a portion of the intake passage 71 of the internal combustion engine 90 on the upstream side of the compressor 81. An intercooler 73 is provided in a portion of the intake passage 71 on the downstream side of the compressor 81. A throttle valve 74 is provided in a portion of the intake passage 71 on the downstream side of the intercooler 73. An intake manifold 75 is provided in a portion of the intake passage 71 on the downstream side of the throttle valve 74. The intake manifold 75 is connected to the cylinder head 97.

[0037] The intake air passing through the intake manifold 75 is introduced into the combustion chamber 93 via the intake port 76 formed in the cylinder head 97. The cylinder head 97 also has an exhaust port 77 for discharging exhaust gas from the combustion chamber 93. The exhaust gas discharged from the combustion chamber 93 is discharged into the exhaust passage 78 via the exhaust port 77.

[0038] <About the blowby gas treatment device 30>

[0039] The blow-by gas treatment device 30 provided in the internal combustion engine 90 includes a blow-by gas passage 49 that connects the crankcase 95 and the intake passage 71 , and causes the blow-by gas leaking from the combustion chamber 93 to the crankcase 95 to flow back to the intake passage 71 .

[0040] The blow-by gas treatment device 30 includes a first separator 43 as an oil separator that is provided in the blow-by gas passage 49 and separates the oil contained in the blow-by gas. The first separator 43 is provided in the cylinder head cover 98. The first separator 43 is connected to the intake manifold 75 of the intake passage 71 through the blow-by gas release pipe 47. As the blow-by gas release pipe 47, a rubber hose or a resin pipe or the like can be used. The blow-by gas release pipe 47 is provided with a PCV valve 48 that opens and closes the communication between the first separator 43 and the intake manifold 75. The PCV valve 48 opens when the pressure in the intake manifold 75 is lower than the pressure in the first separator 43, thereby connecting the first separator 43 and the intake manifold 75.

[0041] The blow-by gas treatment device 30 includes a suction passage 41 for introducing blow-by gas in the crankcase 95 to the first separator 43. The suction passage 41 is formed in the cylinder block 91 and the cylinder head 97. The suction passage 41 is provided with a pre-separator 42 for separating oil from the blow-by gas passing through the suction passage 41.

[0042] The blowby gas treatment device 30 includes a connecting pipe 31 for introducing fresh air from the intake passage 71 into the crankcase 95. As the connecting pipe 31, a rubber hose or a resin pipe or the like can be used. One end of the connecting pipe 31 is connected between the air filter 72 and the compressor 81 in the intake passage 71. The other end of the connecting pipe 31 is connected to a second separator 32 which is an oil separator provided in the cylinder head cover 98. The second separator 32 is divided by the cylinder head cover 98 and the baffle. The second separator 32 includes a joint portion 10 connected to the connecting pipe 31. A pressure sensor 54 for detecting the pressure in the connecting pipe 31 is connected to the joint portion 10 via the connecting passage 60.

[0043] The connection passage 60 is composed of a first pipe 61 connected to the joint portion 10 , a second pipe 62 connected to the pressure sensor 54 , and a chamber 63 to which the first pipe 61 and the second pipe 62 are connected.

[0044] The detection signal of the pressure sensor 54 is input to the control device of the internal combustion engine 90. The control device detects the pressure in the connecting pipe 31 based on the detection signal of the pressure sensor 54, and detects abnormality of the connecting pipe 31 when the pressure fluctuation exceeds a predetermined range and increases.

[0045] The cylinder block 91 is formed with a communication passage 99 that communicates with the crankcase 95. The intake passage 71 and the crankcase 95 are connected via the connecting pipe 31, the second separator 32, and the communication passage 99. Hereinafter, the passage that includes the connecting pipe 31 and connects the intake passage 71 and the crankcase 95 is sometimes referred to as a "fresh air introduction passage."

[0046] The blow-by gas treatment device 30 includes an ejector 50 that generates negative pressure as the supercharger 80 is driven. The ejector 50 includes an ejector body 51 connected to the first separator 43. The first intake air circulation path 52 connected between the compressor 81 and the intercooler 73 in the intake passage 71 and the second intake air circulation path 53 connected between the air filter 72 and the compressor 81 in the intake passage 71 are connected to the ejector body 51. The connection portion between the second intake air circulation path 53 and the intake passage 71 is located on the downstream side of the connection portion between the connection pipe 31 and the intake passage 71. The ejector body 51 includes a nozzle portion 51A that ejects the intake air supplied through the first intake air circulation path 52 toward the second intake air circulation path 53. A diffuser portion 51B in which the flow path of the gas is gradually expanded is provided on the ejector body 51 on the second intake air circulation path 53 side relative to the nozzle portion 51A. The ejector 50 is composed of an ejector body 51 , a first intake air circulation path 52 , and a second intake air circulation path 53 .

[0047] When the internal combustion engine 90 is not operated in the supercharging range and the pressure in the intake manifold 75 is lower than the pressure in the first separator 43, the PCV valve 48 is opened and the blow-by gas in the first separator 43 is introduced into the intake passage 71. At this time, the blow-by gas in the crankcase 95 is introduced into the first separator 43 via the suction passage 41. In addition, the intake air is introduced from the intake passage 71 into the crankcase 95 via the fresh air introduction passage.

[0048] On the other hand, when the internal combustion engine 90 is operating in the supercharging range, the intake air flowing into the first intake circulation path 52 from the downstream side of the compressor 81 in the intake passage 71 returns to the upstream side of the compressor 81 via the ejector body 51 and the second intake circulation path 53. When the intake air passes through the nozzle portion 51A of the ejector body 51, negative pressure is generated inside the ejector body 51. At this time, the ejector 50 sucks the blow-by gas in the crankcase 95 via the first separator 43. And, the ejector 50 releases the blow-by gas that has passed through the diffuser 51B to the intake passage 71 via the second intake circulation path 53.

[0049] It should be noted that when the internal combustion engine 90 is operating in the supercharging range, the pressure of the blow-by gas leaking from the combustion chamber 93 to the crankcase 95 is relatively high. When the pressure in the crankcase 95 is higher than the internal pressure of the portion of the intake passage 71 to which the connecting pipe 31 is connected, the blow-by gas in the crankcase 95 flows into the intake passage 71 via the fresh air introduction passage. In addition, even when the internal combustion engine 90 is not operating in the supercharging range, for example, when the throttle valve 74 is fully opened, the blow-by gas leaking from the combustion chamber 93 to the crankcase 95 may flow into the intake passage 71 via the fresh air introduction passage.

[0050] <About Connection Path 60>

[0051] use Figure 2 to Figure 5 The connection path 60 will be described in detail.

[0052] exist Figure 2 A top view of the cylinder head cover 98 is shown in FIG. Figure 2 to Figure 4 As shown, the joint portion 10 of the second separator 32 includes a connection port 25. The connection port 25 is inserted into the connection pipe 31, and the connection pipe 31 and the joint portion 10 are connected.

[0053] like Figure 2 to Figure 4 As shown, the joint portion 10 includes a third connection port 23 to which the first pipe 61 is connected. Figure 2 and Figure 3 As shown, the third connection port 23 is inserted into one end of the first pipe 61, and the first pipe 61 and the joint portion 10 are connected. Figure 3 1 is a side view of the joint portion 10 and the chamber 63 in the posture in which the internal combustion engine 90 is mounted on the vehicle. Figure 3The lower part in the middle becomes the vertical lower part in the posture where the internal combustion engine 90 is mounted.

[0054] Regarding the second separator 32, Figure 4 As shown, a throttle portion 13 is provided on the floor surface of the joint portion 10. The floor surface provided with the throttle portion 13 becomes a partition wall, and the second separator 32 is divided into a sub-chamber formed by the joint portion 10 and a main chamber in the cylinder head cover 98. It should be noted that the passage cross-sectional area of ​​the hole penetrating the partition wall, i.e., the floor surface, i.e., the throttle portion 13, is narrower than the passage cross-sectional area of ​​the connection port 25. In addition, the floor surface of the joint portion 10 is inclined toward the throttle portion 13 in such a way that the portion provided with the throttle portion 13 becomes the lowest portion. In addition, in Figure 4 In FIG. 2 , the central axis of the connection port 25 is represented as a third axis C3 .

[0055] like Figure 2 As shown in FIG. 1 , a box-shaped chamber 63 is provided in the cylinder head cover 98. The interior of the chamber 63 is a space surrounded by a ceiling, a floor surface, and side walls. Figure 2 and Figure 3 as well as Figure 5 As shown, the chamber 63 is provided with a first connection port 66 and a second connection port 67 which are cylindrical and communicate with the internal space of the chamber 63 .

[0056] like Figure 2 and Figure 3 As shown, the first connection port 66 is inserted into the other end of the first pipe 61 to connect the first pipe 61 and the chamber 63. As a result, the space in the joint portion 10 and the space in the chamber 63 are connected via the first pipe 61. Figure 3 As shown, the third connection port 23 is located vertically below the first connection port 66 when the internal combustion engine 90 is mounted on the vehicle. Therefore, the first pipe 61 is inclined so as to be located vertically upward as it goes from the third connection port 23 side to the first connection port 66 side.

[0057] The second pipe 62 is connected to the second connection port 67. Figure 2 and Figure 3 As shown, the pressure sensor 54 is connected to the end of one side of the second piping 62. And, the second connection port 67 is inserted into the end of the other side of the second piping 62, and the second piping 62 and the chamber 63 are connected. Thus, the space in the chamber 63 and the pressure sensor 54 are connected via the second piping 62. In the internal combustion engine 90, in this way, the pressure sensor 54 and the chamber 63 are connected by the second piping 62, and the chamber 63 and the joint part 10 are connected by the first piping 61. That is, the first piping 61, the chamber 63 and the second piping 62 constitute a connection passage 60 connecting the pressure sensor 54 and the joint part 10. Thus, the pressure in the joint part 10 can be detected by using the pressure sensor 54 connected to the joint part 10 via the connection passage 60.

[0058] like Figure 3 As shown, the pressure sensor 54 is located vertically above the second connection port 67 when the internal combustion engine 90 is mounted on the vehicle. In addition, the second connection port 67 is located vertically above the first connection port 66 when the internal combustion engine 90 is mounted on the vehicle.

[0059] And, if Figure 3 As shown by the dotted line, the floor surface 64 in the space inside the chamber 63 is inclined so as to be located vertically downward as it approaches the first connection port 66 from the second connection port 67 side when the internal combustion engine 90 is mounted.

[0060] like Figure 5 As shown, the side wall of the chamber 63 is divided into seven parts, namely, side wall 65A to side wall 65G. Side wall 65B extends at an angle of about 90 degrees relative to side wall 65A. Side wall 65F, which extends approximately parallel to side wall 65B and is located opposite to side wall 65B, is shorter than side wall 65B. The end of side wall 65A on the side of side wall 65F is connected to side wall 65G. Side wall 65G is inclined relative to side wall 65A and connected to side wall 65F. As a result, the side wall 65B is Figure 5 The upper end of the middle and the side wall 65F Figure 5 The upper end portions of the plurality of electrodes are connected via the side wall 65A and the side wall 65G.

[0061] On the other hand, the side wall 65B Figure 5 The lower end of the middle portion and the side wall 65F Figure 5 The lower end of the side wall 65C is connected to the side wall 65E. Figure 5 As shown in FIG. 1 , the side wall 65C and the side wall 65E extend in parallel with the side wall 65A. The side wall 65C and the side wall 65E are connected by the side wall 65D extending in parallel with the side wall 65B and the side wall 65F. Thus, the side wall 65C, the side wall 65D and the side wall 65E form a side wall bent in a crank shape. That is, the side wall 65B is Figure 5 The lower end of the middle portion and the side wall 65F Figure 5 The lower end portion of the middle portion is connected via a side wall formed by side walls 65C to 65E and bent into a crank shape.

[0062] like Figure 5 As shown, side wall 65E is located closer to side wall 65C. Figure 5 In addition, the first connection port 66 is provided on the side wall 65E. Figure 5 In FIG. 6A , the central axis of the first connection port 66 is indicated as the first axis C1 . On the other hand, the second connection port 67 is provided on the side wall 65C. That is, the first connection port 66 and the second connection port 67 are provided on the side wall of the chamber 63 .

[0063] exist Figure 5 In the figure, the central axis of the second connection port 67 is represented as the second axis C2. The first connection port 66 and the second connection port 67 open in the same direction in the chamber 63. Specifically, the first axis C1 and the second axis C2 are parallel and both intersect the side wall 65G. That is, the first connection port 66 and the second connection port 67 both open toward the side wall 65G. In addition, the side wall 65G is inclined, and the side wall 65E is located closer to the side wall 65C than the side wall 65C. Figure 5 Therefore, a distance D1 from the first connection port 66 to the side wall 65G is shorter than a distance D2 from the second connection port 67 to the side wall 65G.

[0064] <Function of this embodiment>

[0065] The internal combustion engine 90 includes a joint portion 10 in which the third connection port 23 to which the pressure sensor 54 is connected is provided at the connection port 25 side of the throttle portion 13. Therefore, when the connection piping 31 is loosened or damaged, the portion provided with the third connection port 23 is opened to the atmosphere and the detection value of the pressure sensor 54 is likely to change in a manner close to the atmospheric pressure. That is, when an abnormality occurs in the connection piping 31, the abnormality can be detected by the change in the detection value of the pressure sensor 54.

[0066] Intake pulsation is generated during the operation of the internal combustion engine 90. The pressure sensor 54 is connected to the joint portion 10 via the first pipe 61, the chamber 63, and the second pipe 62. Therefore, even if the intake pulsation propagates to the joint portion 10, the intake pulsation is mitigated when passing through the chamber 63. In addition, the first connection port 66 and the second connection port 67 open in the same direction in the chamber 63. Therefore, the intake pulsation propagated into the chamber 63 through the first pipe 61 first propagates in the direction away from the second connection port 67. Therefore, it is not easy to propagate to the second connection port 67.

[0067] In addition, the pressure wave propagating into the chamber 63 through the first connection port 66 is easily attenuated if it collides with the side wall of the chamber 63. According to the structure of the above embodiment, the pressure wave propagating through the first connection port 66 is attenuated by colliding with the side wall 65G, so that the influence of the intake pulsation on the pressure value detected by the pressure sensor 54 can be alleviated.

[0068] <Effects of the present embodiment>

[0069] (1) Since the chamber 63 having a wide space is provided in the middle of the connecting passage 60, the intake air pulsation propagated into the chamber 63 through the first pipe 61 is not easily propagated to the second connecting port 67. Therefore, it is possible to suppress the pressure value detected by the pressure sensor 54 from being affected by the intake air pulsation. Therefore, by monitoring the pressure value detected by the pressure sensor 54, it is possible to appropriately detect an abnormality in the connecting pipe 31.

[0070] (2) Since the first connection port 66 and the second connection port 67 open in the same direction in the chamber 63 , the intake air pulsation propagating into the chamber 63 through the first pipe 61 is less likely to propagate to the second connection port 67 .

[0071] (3) The pressure wave propagating through the first connection port 66 collides with the side wall 65G and is attenuated, thereby alleviating the influence of the intake air pulsation on the pressure value detected by the pressure sensor 54 .

[0072] (4) The shorter the distance between the first connection port 66 and the opposite side wall, the easier it is for the pressure wave to be attenuated by colliding with the side wall. However, if the second connection port 67 is also located near the side wall, the pressure wave that collides with the side wall and bounces back is easy to enter the second connection port 67.

[0073] In contrast, if the first connection port 66 is close to the opposite side wall 65G but the second connection port 67 is separated from the side wall 65G as in the above-mentioned structure, the influence of the rebound of the pressure wave from the side wall 65G can be suppressed. Therefore, the pressure wave propagating from the first connection port 66 into the chamber 63 can collide with the side wall 65G, thereby effectively alleviating the influence of the intake pulsation.

[0074] (5) Oil mist and water are contained in the blowby gas. If oil or water derived from such oil mist or water adheres to the pressure sensor 54, the detection sensitivity of the pressure sensor 54 decreases. According to the structure of the above-mentioned embodiment, the second connection port 67 is located vertically above the first connection port 66. Therefore, even if oil or water intrudes into the chamber 63 through the first connection port 66 along with the flow of the blowby gas, it is not easy to reach the second connection port 67. Therefore, it is possible to suppress the oil or water from adhering to the pressure sensor 54.

[0075] (6) The oil mist and water that have entered the chamber 63 collide with the wall surface of the chamber 63 and separate from the gas, and then become liquid droplets and drip onto the floor surface 64 of the chamber 63. According to the structure of the above embodiment, since the floor surface 64 is inclined toward the first connection port 66, the oil and water that have dripped onto the floor surface 64 flow down toward the first connection port 66 by their own weight. Therefore, the water and oil generated in the chamber 63 can be discharged from the first connection port 66.

[0076] (7) In the structure of the above embodiment, the first pipe 61 is inclined so as to be located vertically upward as it goes from the third connection port 23 side to the first connection port 66 side. That is, the first pipe 61 is inclined upward from the third connection port 23 toward the first connection port 66. Therefore, even if oil or water intrudes into the first pipe 61 from the third connection port 23 by the flow of blowby gas, it is easy to flow down in the first pipe 61 by its own weight and return to the joint portion 10.

[0077] (8) When the oil or water in the chamber 63 is discharged from the first connection port 66 into the first pipe 61, the oil or water easily flows down the first pipe 61 and is discharged toward the joint portion 10. This can prevent the oil or water from adhering to the pressure sensor 54.

[0078] <Change example>

[0079] This embodiment can be implemented by being modified as follows. This embodiment and the following modified examples can be implemented in combination with each other within the range that there is no technical contradiction.

[0080] The structure of connecting the pressure sensor 54 from the joint portion 10 via the connecting passage 60 in the above embodiment can also be applied to other pipes connecting the cylinder head cover 98 and the intake passage 71. For example, it can also be applied to the blowby gas passage 49. Specifically, the same structure as in the above embodiment can also be applied to the joint portion where the blowby gas release pipe 47 is mounted on the first separator 43. In this case, the pressure sensor 54 is used to detect abnormalities in the blowby gas release pipe 47.

[0081] In the above embodiment, an example is shown in which the floor surface of the joint portion 10 is inclined toward the throttle portion 13 , but the floor surface does not need to be inclined.

[0082] In the above embodiment, an example in which the floor surface 64 of the chamber 63 is inclined is shown, but the floor surface 64 does not need to be inclined.

[0083] Although the example in which the third connection port 23 is located vertically below the first connection port 66 is shown, this positional relationship does not necessarily have to be such. For example, the third connection port 23 and the first connection port 66 may be arranged horizontally.

[0084] The example in which the second connection port 67 is located vertically above the first connection port 66 is shown, but this positional relationship may not be the case. For example, the second connection port 67 and the first connection port 66 may be arranged horizontally. In addition, the second connection port 67 may be located vertically below the first connection port 66.

[0085] The example in which the distance D1 from the first connection port 66 to the side wall 65G is shorter than the distance D2 from the second connection port 67 to the side wall 65G is shown. On the other hand, the distances from the connection ports to the side walls may not have such a relationship in magnitude.

[0086] · An example is shown in which the first connection port 66 and the second connection port 67 open toward the side wall 65G. That is, an example is shown in which the first connection port 66 and the second connection port 67 open toward the same side wall. In contrast, the side wall to which the first connection port 66 opens and the side wall to which the second connection port 67 opens may be different. At least the first connection port 66 and the second connection port 67 may face the same direction in the chamber 63.

[0087] The internal combustion engine 90 in the above embodiment is provided with a supercharger 80, but the supercharger 80 is not an essential structure. Even in the internal combustion engine 90 without the supercharger 80, the pressure sensor 54 can be used to detect abnormalities in the connecting pipe 31 in the same manner as in the above embodiment. Even in the internal combustion engine 90 without the supercharger 80, when the throttle valve 74 is fully opened, blowby gas leaking from the combustion chamber 93 to the crankcase 95 may flow into the intake passage 71 through the fresh air introduction passage.

[0088] In the internal combustion engine 90 in the above embodiment, the negative pressure is generated by the ejector 50 to release the blow-by gas into the intake passage 71 when the internal combustion engine 90 is operating in the supercharging range, but the ejector 50 may be omitted. In this case, when the internal combustion engine 90 is operating in the supercharging range, the blow-by gas can be released into the intake passage 71 via the fresh air introduction passage.

Claims

1. An internal combustion engine comprising a blow-by gas treatment device for treating blow-by gas leaking from a combustion chamber to a crankcase by causing the blow-by gas to flow back to an intake passage, wherein: The blow-by gas treatment device includes a connecting pipe, one end of which is connected to the intake passage, and fresh air is introduced from the intake passage into the crankcase. The cylinder head cover is provided with a joint portion, the joint portion including a connection port to which the other end of the connection pipe is connected and a throttle portion having a passage cross-sectional area smaller than that of the connection port. The joint portion is connected to the interior of the cylinder head via the throttle portion, and a space between the throttle portion and the connection port in the joint portion serves as an oil separator for separating oil contained in the blow-by gas. The internal combustion engine includes a pressure sensor connected to the space in the oil separator in the joint portion via a connection passage and detecting the pressure in the oil separator. The connection passage is composed of a first pipe connected to the joint portion, a second pipe connected to the pressure sensor, and a chamber having a first connection port to which the first pipe is connected and a second connection port to which the second pipe is connected. The first connection port and the second connection port open in the chamber toward the same direction.

2. The internal combustion engine according to claim 1, The interior of the chamber is a space surrounded by a ceiling, a floor and side walls. The first connection port and the second connection port are respectively disposed on the side wall, The first connection port and the second connection port are opened toward a side wall of the chamber that is opposite to the side wall on which the first connection port and the second connection port are provided.

3. The internal combustion engine according to claim 2, The first connection port and the second connection port open toward a common side wall in the chamber, A distance from the first connection port to the common side wall is shorter than a distance from the second connection port to the common side wall.

4. The internal combustion engine according to claim 2 or 3, The second connection port is located vertically above the first connection port in a posture in which the internal combustion engine is mounted.

5. The internal combustion engine according to claim 2 or 3, The floor surface is inclined so as to be located vertically downward as it approaches the first connection port from the second connection port side in the posture in which the internal combustion engine is mounted.

6. The internal combustion engine according to any one of claims 1 to 3, The joint portion is provided with a third connection port to which the first pipe is connected, The third connection port is located vertically below the first connection port when the internal combustion engine is mounted. The first pipe is inclined so as to be located vertically upward as it goes from the third connection port side to the first connection port side in the posture in which the internal combustion engine is mounted.

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