Blow-by gas recirculation device

Abstract

To stabilize the combustion of gas fuel whose specific gravity is lower than that of air.SOLUTION: A blow-by gas recirculation device is provided with: a supply pipe for sending a blow-by gas in an engine to an intake port (86); an intake pipe (54) installed at an upstream side of the intake port; and an injector (83) for injecting gas fuel toward the intake port. The intake pipe is bent into a circular arc shape, and the injector is installed at a pipe wall (87) of the intake pipe at the outside of a curvature radius direction so as to be capable of injecting the gas fuel from an injection port (92) which is oriented toward the intake port. An introduction port (95) for introducing the blow-by gas from the supply pipe is formed at the intake pipe so as not to be overlapped on a region (A1) in which the injection port is extended in an injection direction in a cross section view which is cut along axial lines of the intake pipe and the injector.SELECTED DRAWING: Figure 7

Description

[Technical field]

[0001] The present invention relates to a blow-by gas recirculation device. [Background technology]

[0002] An engine for a saddle-type vehicle is provided with a blow-by gas recirculation device that returns blow-by gas leaking from the crank chamber to an intake passage for re-burning (see, for example, Patent Document 1). In the blow-by gas recirculation device described in Patent Document 1, a nipple is provided in the intake pipe of the engine, and a gas hose extending from the crank chamber of the engine is connected to the nipple. A gas flow passage is formed near the intake port, and an outlet of the gas flow passage opens downstream of the injector. Blow-by gas is sent from the crank chamber through the gas hose and the gas flow passage to the intake port and re-burned. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Publication No. 6-48093 Summary of the Invention [Problem to be solved by the invention]

[0004] However, when a gas fuel engine such as a hydrogen engine is mounted on the straddle-type vehicle described in Patent Document 1 and the specific gravity of the gas fuel is smaller than that of air, the gas fuel is easily affected by the flow in the intake passage. Therefore, the flow of the gas fuel injected from the injector may be disturbed by blow-by gas, which may cause unstable combustion.

[0005] The present invention has been made in view of the above-mentioned problems, and has an object to provide a blow-by gas recirculation device that stabilizes the combustion of gas fuel, which has a lower specific gravity than air. [Means for solving the problem]

[0006] One embodiment of the blow-by gas recirculation device of the present invention is a blow-by gas recirculation device that recirculates blow-by gas to an engine that uses a gas fuel having a smaller specific gravity than air, and is equipped with a supply pipe that sends the blow-by gas in the engine to an intake port, an intake pipe installed upstream of the intake port, and an injector that injects gas fuel toward the intake port, wherein the intake pipe is curved in an arc, and the injector is installed on the pipe wall on the outer side of the radius of curvature of the intake pipe so as to be able to inject gas fuel from a nozzle facing the intake port, and the intake pipe is formed with an inlet for introducing blow-by gas from the supply pipe so that it does not overlap with a region extended from the nozzle in the injection direction in a cross-sectional view cut along the axis of the intake pipe and the injector, thereby solving the above-mentioned problem. Effect of the Invention

[0007] According to the blow-by gas recirculation device of one aspect of the present invention, the inlet of the blow-by gas is out of the injection direction of the gas fuel, so the flow of the gas fuel is less affected by the blow-by gas that has entered the intake pipe from the inlet. Therefore, the flow of the gas fuel, which has a smaller specific gravity than air, is less likely to be disturbed by the blow-by gas, and the combustion of the gas fuel is more likely to be stabilized, improving the controllability of the engine. In addition, the intake system can be made compact by providing the injector and the inlet of the blow-by gas in the intake pipe. [Brief description of the drawings]

[0008] [Figure 1] FIG. 2 is a left side view of the vehicle internal structure of the present embodiment. [Diagram 2] FIG. 2 is a right side view of the vehicle internal structure of the present embodiment. [Diagram 3] FIG. 2 is a left side view of the center portion of the vehicle body of the present embodiment. [Figure 4] FIG. 2 is a right side view of the center portion of the vehicle body of the present embodiment. [Diagram 5] FIG. 2 is a perspective view of an upper part of the engine according to the embodiment. [Figure 6]1 is a perspective view of a blow-by gas recirculation device according to an embodiment of the present invention; [Figure 7] 7 is a cross-sectional view of the blow-by gas recirculation device of FIG. 6 taken along line AA. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] A blow-by gas recirculation device according to one aspect of the present invention recirculates blow-by gas to an engine using a gas fuel having a lower specific gravity than air. An intake pipe curved in an arc shape is installed upstream of an intake port of the engine. Gas fuel is injected from an injector toward the intake port, and blow-by gas in the engine is sent to the intake port through a supply pipe. An injector is installed on a pipe wall on the outer side of the curvature radius direction of the intake pipe so as to be able to inject gas fuel from an injection port facing the intake port. In addition, an inlet for introducing blow-by gas from the supply pipe is formed in the intake pipe so as not to overlap with a region in which the injection port is extended in the injection direction in a cross-sectional view cut along the axis of the intake pipe and the injector. Since the inlet for blow-by gas is out of line with the injection direction of the gas fuel, the flow of the gas fuel is less likely to be affected by the blow-by gas that has entered the intake pipe from the inlet. Therefore, the flow of the gas fuel having a lower specific gravity than air is less likely to be disturbed by the blow-by gas, and the combustion of the gas fuel is more likely to be stabilized, improving the controllability of the engine. In addition, by providing an injector and a blow-by gas inlet in the intake pipe, the intake system can be made compact. EXAMPLES

[0010] Hereinafter, a saddle-type vehicle of this embodiment will be described with reference to the accompanying drawings. Fig. 1 is a left side view of the internal structure of the vehicle of this embodiment. Fig. 2 is a right side view of the internal structure of the vehicle of this embodiment. In the following drawings, the arrow Fr indicates the front of the vehicle, the arrow Re indicates the rear of the vehicle, the arrow L indicates the left side of the vehicle, and the arrow R indicates the right side of the vehicle.

[0011] As shown in Figures 1 and 2, a saddle-type vehicle 1 is configured by mounting various covers (not shown) as the exterior of the vehicle body to a body frame 10 made of steel or aluminum alloy. A head pipe 11 is provided at the front end of the body frame 10, and a support frame 12 extends diagonally rearward and downward from an upper portion of the head pipe 11. A pair of first down frames 13 branch off to the left and right and extend downward from a lower portion of the support frame 12, and a pair of second down frames 14 branch off to the left and right and extend downward from a lower portion of the head pipe 11. A pair of main frames 15 are connected to the lower portions of the pair of first and second down frames 13, 14.

[0012] The pair of main frames 15 extend toward the rear of the vehicle, and their middle portions are connected by an upper bridge 16. A pair of asymmetrical side frames 17 extend downward from the front ends of the pair of main frames 15. Each side frame 17 is bent rearward under the vehicle and then extends diagonally upward and rearward toward the rear portions of the pair of main frames 15. The pair of main frames 15 and the pair of side frames 17 form the front half of the body frame 10 into a cradle shape. A pair of footboards 18 are attached to the pair of side frames 17.

[0013] A pair of seat frames 19 extend rearward from the rear portions of the pair of main frames 15. The distance between the pair of seat frames 19 increases toward the middle of each frame and then decreases toward the rear ends of each frame. The pair of seat frames 19 are formed in an arch shape, and the rear ends of the pair of seat frames 19 are connected to each other. The front portions of the pair of seat frames 19 are connected by an upper bridge 21. The rear portions of the pair of side frames 17 are connected to the upper bridge 21, and the upper bridge 21 is supported from below by the pair of side frames 17.

[0014] A pair of asymmetric lower frames 22 extend rearward from the lower portions of the pair of side frames 17. The rear ends of the pair of lower frames 22 are connected by a lower bridge 23. A left subframe 28 extends diagonally upward and rearward from the left end of the lower bridge 23, and the left subframe 28 supports the seat frame 19 from below. A side bridge 25 connects the right end of the lower bridge 23 to an intermediate portion of the right side frame 17. A right subframe 29 extends diagonally upward and rearward from the intermediate portion of the side bridge 25, and the right subframe 29 supports the seat frame 19 from below.

[0015] A front fork 33 is supported on the head pipe 11 so as to be steerable, and a front wheel 34 is supported rotatably on the lower part of the front fork 33. A gas tank 61 is installed inside a cradle portion in the front half of the body frame 10, and a tank valve 63 is installed on the rear end part of the gas tank 61. Gas fuel such as hydrogen is stored in the gas tank 61, and the inflow and outflow of the gas fuel is controlled by the tank valve 63. The gas fuel is supplied from the tank valve 63 to an injector 83 (see FIG. 7) above the unit swing engine 41 via gas fuel supply system parts such as multiple pipes and a fuel hose 71.

[0016] A unit swing engine (engine) 41 is supported swingably on the support plates 31 of the left and right subframes 28, 29. The unit swing engine 41 is operated by combustion energy of gas fuel supplied from a gas tank 61. The cylinder axis of the unit swing engine 41 is tilted forward and close to horizontal, and a cylinder assembly 43 extends toward the front of the vehicle from a crankcase 42. The cylinder assembly 43 is inserted between the left subframe 28 and the right subframe 29, and the front end of the cylinder assembly 43 is brought close to a tank valve 63 of the gas tank 61.

[0017] Intake system parts such as an air cleaner 51 are connected to the upper part of the cylinder assembly 43, and exhaust system parts such as an exhaust pipe 56 and a muffler 58 are connected to the lower part of the cylinder assembly 43. A CVT cover 47 is attached to the left side of the crankcase 42. The rear wheel 35 is rotatably supported at the rear part of the CVT cover 47. A belt-type continuously variable transmission (not shown) is housed inside the CVT cover 47, and the driving force of the unit swing engine 41 is transmitted to the rear wheel 35 via the belt. The muffler 58, CVT cover 47, rear wheel 35, and unit swing engine 41 are all swung together.

[0018] Meanwhile, the saddle riding type vehicle 1 is provided with a blow-by gas recirculation device 80 (see FIG. 5) that returns the blow-by gas to the intake passage and re-burns it. In this embodiment, hydrogen gas, which has a lower specific gravity than air, is used as the gas fuel. Therefore, when the gas fuel is injected from the injector 83 into the intake passage, the flow of the gas fuel may be disturbed by the blow-by gas, which may cause unstable combustion. If the blow-by gas inlet is moved away from the injector 83 so as not to disturb the flow of the gas fuel, the intake passage will become larger. Therefore, in this embodiment, a blow-by gas inlet is formed in the intake passage in consideration of the injection range of the gas fuel from the injector 83.

[0019] The peripheral structure of the unit swing engine will be described with reference to Fig. 3 to Fig. 5. Fig. 3 is a left side view of the center part of the body of this embodiment. Fig. 4 is a right side view of the center part of the body of this embodiment. Fig. 5 is a perspective view of the upper part of the engine of this embodiment. Note that Fig. 3 to Fig. 5 are shown without the body frame.

[0020] 3 and 4, the cylinder assembly 43 of the unit swing engine 41 is formed by stacking a cylinder 44, a cylinder head 45, and a cylinder head cover 46. An air cleaner 51 is installed above the cylinder head 45. The air cleaner 51 is connected to an intake port 86 at the top of the cylinder head 45 via a U-shaped outlet tube 52, a throttle body 53, and an intake pipe 54. Air is sent from the air cleaner 51 to the throttle body 53 via the outlet tube 52, and after the intake amount is adjusted by the throttle body 53, the air is supplied to the cylinder head 45 through the intake pipe 54.

[0021] An exhaust pipe 56 is connected to the exhaust port at the bottom of the cylinder head 45. A bent portion 57 that curves rearward from the cylinder head 45 is formed in the exhaust pipe 56, and the downstream side of the bent portion 57 of the exhaust pipe 56 passes to the right side of the crankcase 42 and extends toward the rear of the vehicle. A muffler 58 (see FIG. 2) that is inclined diagonally upward and rearward on the right side of the rear wheel 35 is connected to the rear end of the exhaust pipe 56. Exhaust gas discharged from the unit swing engine 41 flows through the exhaust pipe 56 and muffler 58, which are exhaust system components, and the exhaust gas warms the exhaust pipe 56 and muffler 58 to a high temperature.

[0022] A link mechanism 37 for attaching the suspension 36 to the vehicle body is provided below the cylinder head 45. The link mechanism 37 is provided with a link lever 38 that is arc-shaped in side view, and an intermediate portion of the link lever 38 is swingably connected to a bracket of the vehicle body frame 10 (lower bridge 23). The upper end of the link lever 38 is swingably connected to the lower portion of the crankcase 42 via a link arm 39, and the rear end of the suspension 36 is swingably connected to the lower end of the link lever 38. The suspension 36 expands and contracts in accordance with the swing of the unit swing engine 41, thereby absorbing vibrations transmitted to the vehicle body.

[0023] A gas tank 61 is installed in front of the unit swing engine 41. The gas tank 61 is formed in a cylindrical shape, and both ends of the gas tank 61 are bulged out in a hemispherical shape. The longitudinal direction of the gas tank 61 is directed forward and backward, and the gas tank 61 is slightly tilted so that the front end of the gas tank 61 is higher than the rear end. A tank valve 63 is installed at the rear end of the gas tank 61, and a pipe joint 65 is connected to a relief valve pipe 64 that extends diagonally upward and rearward from the lower part of the tank valve 63. Therefore, the pipe joint 65 is positioned in the space between the tank valve 63 and the cylinder head 45 in a side view.

[0024] A pressure sensor 66 is attached to the upper part of the pipe joint 65, and a relief valve 67 is attached to the lower part of the pipe joint 65. The pressure in the gas flow path is detected by the pressure sensor 66, and when the pressure of the gas fuel rises to or above a predetermined pressure, the relief valve 67 is opened. The gas fuel is released toward the ground from a discharge port facing downward of the relief valve 67. Since the pipe joint 65 is positioned on the left side of the vehicle body (the other side in the vehicle width direction) and the exhaust pipe 56 is positioned on the right side of the vehicle body (one side in the vehicle width direction), the gas fuel released from the relief valve 67 is unlikely to come into contact with the exhaust pipe 56.

[0025] An injector joint 91 is connected to the pipe joint 65 via an upstream pipe 69, a fuel hose 71, and a downstream pipe 72. The upstream pipe 69 and the downstream pipe 72 are formed of a hard pipe material such as metal, and the fuel hose 71 is formed of a soft rubber hose. The upstream pipe 69 crosses below the tank valve 63 and extends from the pipe joint 65 on the left side of the vehicle body to the right side of the vehicle body. On the right side of the vehicle body, the lower end of the fuel hose 71 is connected to the upstream pipe 69, and the fuel hose 71 extends upward through the right side of the gas tank 61. The upper end of the fuel hose 71 is connected to the injector joint 91 above the cylinder head 45 via the downstream pipe 72.

[0026] In this way, a gas flow path from the gas tank 61 to the unit swing engine 41 is formed by the relief valve pipe 64, the pipe joint 65, the upstream piping 69, the fuel hose 71, and the downstream piping 72. Because a part of the gas flow path is formed by the fuel hose 71, the unit swing engine 41 is allowed to swing due to bending deformation of the fuel hose 71. By attaching the relief valve 67 to the pipe joint 65, the relief valve 67 is interposed in the middle of the gas flow path. This increases the degree of freedom in installing the relief valve 67, and allows the relief valve 67 to be installed in a safer location.

[0027] As described above, the pipe joint 65 has an attachment portion for the pressure sensor 66, an attachment portion for the relief valve 67, a connection portion for the relief valve pipe 64, and a connection portion for the upstream piping 69 (fuel hose 71) formed integrally therewith. By forming each attachment portion and each connection portion in the pipe joint 65, the pressure sensor 66 and the relief valve 67 are compactly installed and the relief valve pipe 64 and the upstream piping 69 are compactly connected. The pipe joint 65 is supported via a bracket on a side bridge that connects the side frame 17 on the left side of the vehicle body and the left subframe 28.

[0028] 5, an intake passage between an air cleaner 51 and a cylinder head 45 is formed by an outlet tube 52, a throttle body 53, and an intake pipe 54. The left front side of the air cleaner 51 protrudes forward, and a U-shaped outlet tube 52 is connected to the front side of the protruding part of the air cleaner 51. The outlet tube 52 is connected to the upper surface of the cylinder head 45 via the throttle body 53 and the intake pipe 54. The throttle body 53 is located above the cylinder head cover 46, and the intake pipe 54 is curved to connect the throttle body 53 and the cylinder head 45.

[0029] An injector joint 91 is attached to the upper part of intake pipe 54, and injector 83 is installed in intake pipe 54 by injector joint 91. Injector 83 is oriented in the vertical direction of the vehicle and is tilted slightly forward to match the curved shape of intake pipe 54. A fuel hose 71 is connected to the upper part of injector joint 91 via L-shaped downstream piping 72. A hose stopper 73 is provided on throttle body 53, and the downstream end of fuel hose 71 is held by hose stopper 73.

[0030] A PCV valve 81 is provided on the right side of the cylinder head cover 46, and the intake pipe 54 is connected to the PCV valve 81 via a PCV hose (supply pipe) 82. The PCV valve 81 is opened when the intake pipe 54 becomes negative pressure. Blow-by gas inside the cylinder head cover 46 is returned to the intake pipe 54 through the PCV hose 82, and the blow-by gas is sent to an intake port 86 of the cylinder head 45 and re-burned. Because the PCV hose 82 is made of a soft rubber hose, bending deformation of the PCV hose 82 allows the unit swing engine 41 to swing.

[0031] The details of the blow-by gas reflux device will be described with reference to Fig. 6 and Fig. 7. Fig. 6 is a perspective view of the blow-by gas reflux device of this embodiment. Fig. 7 is a cross-sectional view of the blow-by gas reflux device of Fig. 6 taken along line AA. Note that the fuel hose and the PCV hose are omitted in Fig. 6 and Fig. 7.

[0032] 6 and 7, the intake pipe 54 is curved in an arc shape, and a flange portion 84 is formed at the upstream end of the intake pipe 54, and a flange member 85 is fixed to the downstream end of the intake pipe 54. The flange portion 84 of the intake pipe 54 is fixed to the throttle body 53 (see FIG. 5), and the intake pipe 54 is installed downstream of a throttle valve (not shown) in the throttle body 53. The flange member 85 is fixed to the cylinder head 45 (see FIG. 5), and the intake pipe 54 is installed upstream of an intake port 86 in the cylinder head 45 via the flange member 85.

[0033] An injector installation section 89 protrudes upward from a pipe wall 87 on the outer side in the curvature radius direction of the intake pipe 54. A gas fuel nozzle 92 is formed in the pipe wall 87 on the outer side in the curvature radius direction so as to face the intake port 86, and an injector 83 is installed in the injector installation section 89 so as to be able to inject gas fuel from the nozzle 92. An injector joint 91 is attached to the upper end surface of the injector installation section 89, and the injector 83 is fixed to the intake pipe 54 by the injector joint 91. Gas fuel is supplied to the injector joint 91, and the gas fuel is injected by the injector 83 toward the intake port 86.

[0034] A concave surface 93 is formed on the pipe wall 87 on the outer side in the curvature radius direction of the intake pipe 54 downstream of the injection port 92. Even when gas fuel is injected from the injector 83, the concave surface 93 prevents the gas fuel from adhering to the pipe wall 87, stabilizing the air-fuel ratio of the mixture. A nipple 94 protrudes laterally from the right pipe wall 88 intersecting the curvature radius direction of the intake pipe 54, and the PCV hose 82 (see FIG. 5) is attached to the nipple 94. A blow-by gas inlet 95 is formed in the right pipe wall 88. An inlet passage 96 is formed from the nipple 94 to the inlet 95, and the blow-by gas is sent from the PCV hose 82 to the intake port 86 through the inlet passage 96.

[0035] 7 shows a state in which the intake pipe 54 is cut along the axes C1, C2 of the intake pipe 54 and the injector 83, i.e., a state in which the intake pipe 54 is cut along a plane including the axes C1, C2. In a cross-sectional view of the intake pipe 54, an inlet 95 is formed in the intake pipe 54 so as not to overlap with an area A1 obtained by extending the injection port 92 in the injection direction. Since the inlet 95 for blow-by gas is out of alignment with the injection direction of the gas fuel, the flow of the gas fuel is less affected by the blow-by gas that has entered the intake pipe 54 from the inlet 95.

[0036] More specifically, the injection port 92 and the introduction port 95 are located outside the axis C1 of the intake pipe 54 in the curvature radius direction. Furthermore, the introduction port 95 is located upstream of the injection port 92, and the injection port 92 and the introduction port 95 are located at the same height. Even if blow-by gas is introduced from the introduction port 95, the gas fuel before diffusion is less likely to be affected by the blow-by gas, so the flow of the gas fuel with a low specific gravity is less likely to be disturbed, and the combustion of the gas fuel is stabilized. Note that the injection port 92 and the introduction port 95 being at the same height does not necessarily mean that the injection port 92 and the introduction port 95 are at exactly the same height, but it is sufficient that the injection port 92 and the introduction port 95 are at approximately the same height.

[0037] As described above, the concave surface 93 is formed downstream of the injection port 92, and the concave surface 93 makes it difficult for the injection of gas fuel by the injector 83 to be obstructed by the pipe wall 87 of the intake pipe 54. The intake pipe 54 is formed with an inlet 95 so as to avoid the concave surface 93. In a front view of the intake pipe 54, the inlet 95 is offset to the right of the concave surface 93 (see FIG. 6), and in a cross-sectional view of the intake pipe 54, the inlet 95 is positioned upstream of the concave surface 93 (see FIG. 7). By separating the inlet 95 from the concave surface 93, the flow of gas fuel near the concave surface 93 is less likely to be disturbed by blow-by gas.

[0038] An injection port 92 is formed in the pipe wall 87 on the outer side in the radius of curvature direction, and an introduction port 95 is formed in the pipe wall 88 on the right side intersecting the radius of curvature direction. The injection port 92 is directed toward the intake port 86, and the introduction port 95 is directed toward the radially inner side of the intake pipe 54 by bending an introduction passage 96 extending from a nipple 94. The injection direction of the fuel gas from the injection port 92 and the introduction direction of the blow-by gas from the introduction port 95 are separated toward the downstream of the intake pipe 54. Since the introduction direction of the blow-by gas does not intersect with the injection direction of the fuel gas and the introduction direction of the blow-by gas is separated from the injection direction of the fuel gas, the flow of the gas fuel is less likely to be disturbed by the blow-by gas.

[0039] As described above, according to the blow-by gas recirculation device 80 of this embodiment, the blow-by gas inlet 95 is out of alignment with the injection direction of the gas fuel, so the flow of the gas fuel is less affected by the blow-by gas that has entered the intake pipe 54 from the inlet 95. Therefore, the flow of the gas fuel, which has a smaller specific gravity than air, is less likely to be disturbed by the blow-by gas, and the combustion of the gas fuel is more likely to be stabilized, improving the controllability of the unit swing engine 41. In addition, the intake system can be made compact by providing the injector 83 and the blow-by gas inlet 95 in the intake pipe 54.

[0040] In this embodiment, the inlet is located upstream of the jet orifice, but the inlet may be located downstream of the jet orifice as long as the inlet is formed so as not to overlap with the area obtained by extending the jet orifice in the jet direction in the cross-sectional view shown in Figure 7.

[0041] In addition, in this embodiment, the inlet port is formed in the right pipe wall intersecting the curvature radius direction of the intake pipe, but the inlet port may also be formed in the left pipe wall intersecting the curvature radius direction of the intake pipe.

[0042] In addition, in this embodiment, a unit swing engine is exemplified as the engine, but the engine is not limited to a unit swing engine as long as it is operated by the combustion energy of gas fuel.

[0043] Furthermore, in this embodiment, hydrogen is exemplified as the gas fuel, but the gas fuel may be any gas fuel having a specific gravity smaller than that of air, and the gas fuel may be LNG, for example.

[0044] Further, in this embodiment, the cylinder axis of the unit swing engine is inclined forward and close to horizontal, but the cylinder axis of the unit swing engine may be horizontal.

[0045] In addition, in this embodiment, the gas tank is formed in a cylindrical shape with both ends bulging out into a hemisphere, but the shape of the gas tank is not limited as long as the gas tank has a shape capable of storing gas fuel.

[0046] The blow-by gas recirculation device of the present embodiment may be used in other types of saddle-ride vehicles as well as the above-mentioned saddle-ride vehicles. Note that the saddle-ride vehicles are not limited to vehicles in general in which the rider sits on the seat, but also include scooter-type vehicles in which the rider does not sit on the seat.

[0047] As described above, the first embodiment is a blow-by gas recirculation device (80) that recirculates blow-by gas to an engine (unit swing engine 41) that uses a gas fuel having a smaller specific gravity than air, and includes a supply pipe (PCV hose 82) that sends the blow-by gas in the engine to an intake port (86), an intake pipe (54) installed upstream of the intake port, and an injector (83) that injects gas fuel toward the intake port, the intake pipe is curved in an arc, and an injector is installed in a pipe wall (87) on the outer side in the radial direction of curvature of the intake pipe so as to be able to inject gas fuel from an injection port (92) facing the intake port, and an inlet (95) for introducing blow-by gas from the supply pipe is formed in the intake pipe so as not to overlap with a region (A1) formed by extending the injection port in the injection direction in a cross-sectional view taken along the axes (C1, C2) of the intake pipe and the injector. According to this configuration, the blow-by gas inlet is out of the injection direction of the gas fuel, so the flow of the gas fuel is less affected by the blow-by gas that has entered the intake pipe from the inlet. Therefore, the flow of the gas fuel, which has a smaller specific gravity than air, is less likely to be disturbed by the blow-by gas, and the combustion of the gas fuel becomes more stable, improving the controllability of the engine. In addition, the intake system can be made compact by providing the injector and the blow-by gas inlet in the intake pipe.

[0048] In the second aspect, in the first aspect, the introduction port is located at the same height as the injection port. With this configuration, the gas fuel before diffusion is less likely to be affected by blow-by gas, so that the flow of the gas fuel is less likely to be disturbed and the combustion of the gas fuel is stabilized.

[0049] In the third aspect, in the first or second aspect, a concave surface (93) is formed on the pipe wall on the outer side in the curvature radius direction of the intake pipe downstream of the injection port, and an inlet is formed in the intake pipe so as to avoid the concave surface. With this configuration, the concave surface is formed on the pipe wall on the outer side in the curvature radius direction of the intake pipe, so that the injection of gas fuel by the injector is less likely to be hindered by the pipe wall of the intake pipe. By forming the inlet so as to avoid the concave surface, the flow of gas fuel near the concave surface is less likely to be disturbed by blow-by gas.

[0050] A fourth aspect is any one of the first to third aspects, in which a concave surface is formed on the pipe wall on the outer side in the curvature radius direction of the intake pipe downstream of the injection port, and an inlet port is formed on the intake pipe upstream of the concave surface. With this configuration, the concave surface is formed on the pipe wall on the outer side in the curvature radius direction of the intake pipe, so that the gas fuel from the injector is less likely to be obstructed by the pipe wall of the intake pipe. By separating the inlet port from the concave surface, the flow of the gas fuel near the concave surface is less likely to be disturbed by blow-by gas.

[0051] In a fifth aspect, in any one of the first to fourth aspects, an injection port is formed in a pipe wall on an outer side in the curvature radius direction of the intake pipe, and an introduction port is formed in a lateral pipe wall (88) intersecting the curvature radius direction of the intake pipe. With this configuration, the introduction direction of the blow-by gas does not intersect with the injection direction of the gas fuel, so that the flow of the gas fuel is less likely to be disturbed by the blow-by gas.

[0052] A sixth aspect is any one of the first to fifth aspects, in which the injection direction of the fuel gas from the injection port and the introduction direction of the blow-by gas from the introduction port are separated toward the downstream of the intake pipe. With this configuration, the introduction direction of the blow-by gas is separated from the injection direction of the fuel gas, so that the flow of the gas fuel is less likely to be disturbed by the blow-by gas.

[0053] Although the present embodiment has been described, other embodiments may be made by combining the above-described embodiments and modifications in whole or in part.

[0054] In addition, the technology of the present invention is not limited to the above examples, and may be modified, substituted, or altered in various ways without departing from the spirit of the technical idea. Furthermore, if the technical idea can be realized in a different way due to the progress of technology or a different technology derived therefrom, the invention may be implemented using that method. Therefore, the claims cover all embodiments that may be included within the scope of the technical idea. [Explanation of symbols]

[0055] 1: Saddle-type vehicle 41: Unit Swing Engine (Engine) 54: Intake pipe 80: Blow-by gas recirculation device 82: PCV hose (supply pipe) 83: Injector 86: Intake port 87: Pipe wall on the outer side in the radial direction of curvature 88: Side pipe wall intersecting the curvature radius direction 92: Nozzle 93: Concave 95: Introduction A1: Area extending from the nozzle in the direction of injection

Claims

1. A blow-by gas recirculation device for recirculating blow-by gas to an engine using a gas fuel having a smaller specific gravity than air, A supply pipe that sends blow-by gas in the engine to the intake port; an intake pipe disposed upstream of the intake port; an injector that injects gas fuel toward the intake port, the intake pipe is curved in an arc shape, and the injector is installed on a pipe wall on an outer side in a curvature radius direction of the intake pipe so as to be capable of injecting gas fuel from an injection port facing the intake port, A blow-by gas recirculation device characterized in that the intake pipe is formed with an inlet for introducing blow-by gas from the supply pipe so that it does not overlap with a region extended from the injection nozzle in the injection direction when viewed in a cross-sectional view cut along the axis of the intake pipe and the injector.

2. 2. The blow-by gas recirculation device according to claim 1, wherein the inlet is positioned at the same height as the injection port.

3. a concave surface is formed on a pipe wall of the intake pipe on an outer side in a curvature radius direction, the concave surface being located downstream of the injection port; 3. The blow-by gas recirculation device according to claim 1, wherein the inlet is formed in the intake pipe so as to avoid the concave surface.

4. a concave surface is formed on a pipe wall of the intake pipe on an outer side in a curvature radius direction, the concave surface being located downstream of the injection port; 3. The blow-by gas recirculation device according to claim 1, wherein the intake port is formed on the intake pipe upstream of the concave surface.

5. 3. The blow-by gas recirculation device according to claim 1, wherein the injection port is formed in a pipe wall on an outer side in the curvature radius direction of the intake pipe, and the introduction port is formed in a pipe wall on a side intersecting the curvature radius direction of the intake pipe.

6. 3. The blow-by gas recirculation device according to claim 1, wherein a direction in which the fuel gas is injected from said injection port and a direction in which the blow-by gas is introduced from said introduction port are separated toward a downstream of said intake pipe.

Images