Internal combustion engine

Abstract

To provide a four-cycle port injection type internal combustion engine using gas fuel as fuel, wherein charging efficiency of air into a cylinder is improved, occurrence of abnormal combustion such as backfire is suppressed, while mixing of the gas fuel and air is promoted, and furthermore injected unburned gas fuel is less likely to remain inside the internal combustion engine.SOLUTION: An internal combustion engine 1 is a four-cycle port-injection-type internal combustion engine using hydrogen as fuel, comprising: a mixing passage 10 provided along an intake port 33; and an injector 8 provided so as to inject hydrogen toward the inside of the mixing passage 10. The mixing passage 10 includes: a guide-in part 12 that introduces air from the intake port 33 into the inside of the mixing passage 10; and a guide-out part 13 that guides hydrogen and air from the inside of the mixing passage 10 to the intake port 33.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to an internal combustion engine.

Background Art

[0002] Conventionally, a fuel injection device including a hydrogen gas injector for injecting hydrogen gas is known (see, for example, Patent Document 1). The fuel injection device described in Patent Document 1 includes a jet pipe through which hydrogen gas injected from the hydrogen gas injector flows. The injection port of the jet pipe is opened at a position close to the umbrella portion of the intake valve in the intake port of the internal combustion engine. Hydrogen gas is ejected from the injection port of the jet pipe to a position close to the umbrella portion of the intake valve in the intake port, and is mixed with air on the downstream side in the intake port from the ejected position.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] When using a configuration such as the jet pipe of the above-described conventional technology, the filling of hydrogen gas in the intake port is suppressed, and an improvement in the filling efficiency of the intake air into the cylinder can be achieved. Further, during the operation of the internal combustion engine, the remaining hydrogen gas in the intake port is suppressed, and the occurrence of backfire (abnormal combustion) can be suppressed.

[0005] However, in a configuration such as the jet pipe of the above-mentioned conventional technology, when hydrogen gas is injected from the hydrogen gas injection injector, the jet pipe may become filled with hydrogen gas. If it is difficult to ensure a sufficient mixing distance between hydrogen gas and air, hydrogen gas may become locally rich in the cylinder, which may lead to the generation of NOx or deterioration of fuel efficiency. In addition, when the internal combustion engine is stopped, it is desirable to reduce the amount of unburned hydrogen gas (gaseous fuel) remaining inside the internal combustion engine. In this regard, in a configuration such as the jet pipe of the above-mentioned conventional technology, it may be difficult to eliminate the state in which hydrogen gas remains in the jet pipe.

[0006] The present invention aims to provide a four-stroke port injection type internal combustion engine that uses gas fuel as fuel, which improves the efficiency of filling air into the cylinder and suppresses the occurrence of abnormal combustion such as backfire, while promoting mixing of gas fuel and air and making it easier to eliminate the residue of injected unburned gas fuel inside the internal combustion engine. [Means for solving the problem]

[0007] One embodiment of the present invention is a four-stroke port injection type internal combustion engine that uses gas fuel as fuel, and is equipped with a mixing passage provided along an intake port, and a fuel injection valve provided to inject gas fuel toward the inside of the mixing passage, and the mixing passage has an inlet section that introduces air from the intake port into the inside of the mixing passage, and an outlet section that discharges the gas fuel and air from the inside of the mixing passage to the intake port.

[0008] In an internal combustion engine according to one aspect of the present invention, gaseous fuel is injected by a fuel injection valve toward the inside of a mixing passage provided along an intake port. Such a mixing passage contributes to improving the air filling efficiency into the cylinder and suppressing the occurrence of abnormal combustion such as backfire by suppressing hydrogen filled in the intake port from obstructing the air flow and hydrogen remaining in the intake port. Here, in the internal combustion engine according to one aspect of the present invention, air from the intake port is introduced into the inside of the mixing passage via an introduction portion. Thereby, the injected gaseous fuel and the introduced air are mixed inside the mixing passage. The gaseous fuel and air mixed inside the mixing passage are led out to the intake port via a lead-out portion and taken into the cylinder as intake air. Therefore, for example, compared with the case where the introduction portion is not provided or the mixing passage itself is not provided, the mixing of gaseous fuel and air is promoted. Further, when the injection of gaseous fuel by the fuel injection valve stops, the gaseous fuel remaining inside the mixing passage is pushed out to the lead-out portion by the air introduced from the introduction portion. Therefore, when the internal combustion engine stops, gaseous fuel hardly remains inside the mixing passage. Accordingly, according to the internal combustion engine according to one aspect of the present invention, in a four-cycle port injection type internal combustion engine using gaseous fuel as fuel, while improving the air filling efficiency into the cylinder and suppressing the occurrence of abnormal combustion such as backfire, the mixing of gaseous fuel and air is promoted, and it becomes easier to eliminate the remaining unburned gaseous fuel injected inside the internal combustion engine.

[0009] In one embodiment, the mixing passage is a pipe member provided so as to extend from the upstream side to the downstream side of the intake port inside the intake port. An introduction portion is provided on the upstream side of the intake port in the pipe member, a lead-out portion is provided on the downstream side of the intake port in the pipe member, and the fuel injection valve may be provided so as to inject gaseous fuel toward the introduction portion. In this case, the mixing passage can be constituted by the pipe member provided inside the intake port.

[0010] In one embodiment, the mixing passage is a partial passage partitioned by a partitioning member provided to extend from the upstream side to the downstream side of the intake port inside the intake port. An introduction part is provided on the upstream side of the intake port in the partial passage, and a derivation part is provided on the downstream side of the intake port in the partial passage. The fuel injection valve may be provided to inject gaseous fuel toward the introduction part. In this case, the mixing passage can be constituted by the partial passage partitioned by the partitioning member provided inside the intake port.

[0011] In one embodiment, the derivation part may be located on the side opposite to the ignition plug of the cylinder with respect to the valve stem of the intake valve. In this case, it is possible to suppress the gaseous fuel from approaching the ignition plug by utilizing the fact that the flow of the gaseous fuel and air derived into the intake port through the derivation part is obstructed by the valve stem of the intake valve.

Advantages of the Invention

[0012] According to the present invention, in a four-cycle port injection type internal combustion engine using gaseous fuel as fuel, while improving the air filling efficiency into the cylinder and suppressing the occurrence of abnormal combustion such as backfire, the mixing of gaseous fuel and air is promoted, and it becomes easier to eliminate the remaining unburned gaseous fuel injected inside the internal combustion engine.

Brief Description of the Drawings

[0013]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Figure 11

Embodiments for Carrying Out the Invention

[0014] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In the drawings, the same or equivalent elements are denoted by the same reference numerals, and duplicate explanations are omitted.

[0015] The internal combustion engine 1 according to the embodiment is configured as a four-cycle port injection type reciprocating engine that uses gas fuel as fuel. As the gas fuel, for example, hydrogen gas (hereinafter simply referred to as "hydrogen") is used.

[0016] FIG. 1 is a schematic configuration diagram of an internal combustion engine according to an embodiment. As shown in FIG. 1, the internal combustion engine 1 has a plurality (for example, four) of cylinders 2 and a cylinder head 3 having an intake valve 31 and an exhaust valve 32. In each cylinder 2, a combustion chamber 5 is defined by the inner wall surface 2a of the cylinder 2, the cylinder head 3, and the piston 4 (see FIG. 2). An intake port 33 and an exhaust port 34 are formed in the cylinder head 3 so as to communicate with the combustion chamber 5. An intake valve 31 is provided at the downstream end of the intake port 33.

[0017] An intake passage 6 and an exhaust passage 7 are connected to the cylinder head 3. The intake passage 6 has an intake manifold 6a attached to the cylinder head 3 so as to communicate with, for example, an intake port 33 of the cylinder head 3. The intake passage 6 means a passage for intake air from the introduction portion of intake air including an air cleaner (not shown) to the downstream end after the branch of the intake manifold 6a. A throttle valve 6b for adjusting the flow rate of intake air may be provided in the intake passage 6.

[0018] Here, the internal combustion engine 1 is configured as a 2-valve crossflow as an example. In one cylinder 2, one intake valve 31 and one exhaust valve 32 are provided in the cylinder head 3, and the intake port 33 and the exhaust port 34 extend in opposite directions to each other. The intake valve 31 and the exhaust valve 32 are arranged side by side, for example, on the side opposite to the intake manifold 6a in the cylinder head 3. The internal combustion engine 1 intakes air and hydrogen through the intake valve 31, burns hydrogen in the combustion chamber 5, and exhausts the exhaust gas generated by combustion to the exhaust passage 7 through the exhaust valve 32.

[0019] FIG. 2 is a schematic perspective view showing a mixing passage of the first example. In FIG. 2, the downstream end of the intake manifold 6a shows its outer shape, but the cylinder 2, the intake port 33, and the exhaust port 34 are not shown in their outer shapes for the sake of illustration. That is, actually, the cylinder, the intake port, and the exhaust port are spaces formed inside the cylinder head or the cylinder block, and the shapes of the cylinder 2, the intake port 33, and the exhaust port 34 shown in FIG. 2 represent the shapes of the boundary surfaces that define the space inside, such as a surface model of 3D-CAD. In the following description, when referring to the cylinder 2, the intake port 33, and the exhaust port 34, it is intended to refer to the actual cylinder, intake port, and exhaust port (the same applies in FIGS. 3, 4, 7 to 10).

[0020] As shown in FIG. 2, the intake port 33 connects the downstream end of the intake manifold 6a and the combustion chamber 5. The connection portion 6c between the downstream end of the intake manifold 6a and the intake port 33 corresponds to the side surface of the cylinder head 3. An injector (fuel injection valve) 8 is attached above the connection portion 6c on the side surface of the cylinder head 3. The injector 8 is inserted and fixed in a through-hole formed in the cylinder head 3 such that the tip of the injector 8 faces the intake port 33.

[0021] As shown in FIG. 1, the injector 8 is connected to an ECU [Electronic Control Unit] 50. The ECU 50 is an electronic control unit that controls the internal combustion engine 1. An engine rotation sensor and an intake air amount sensor are connected to the ECU 50 as sensors for acquiring the operating state of the internal combustion engine 1 (not shown). Based on the engine speed and the intake air amount, the ECU 50 calculates the fuel injection amount by the injector 8 by a known method and transmits a control signal for injecting hydrogen to the injector 8.

[0022] As shown in FIG. 2, the intake valve 31 and the exhaust valve 32 are supported by the cylinder head 3 so as to be reciprocally movable. The intake valve 31 has a valve stem 31a and an umbrella portion 31b provided at the lower end of the valve stem 31a. The valve stem 31a passes through a through-hole 33a provided in the cylinder head 3 and is slidably guided through a cylindrical valve guide (not shown) coaxially inserted into the through-hole 33a. The intake valve 31 opens and closes the intake port 33 by the umbrella portion 31b (see FIG. 4) being separated from or contacting a valve seat (not shown) attached to the opening of the intake port 33 that opens into the combustion chamber 5. Here, the intake valve 31 is arranged such that the valve stem 31a extends substantially parallel to the axial direction of the cylinder 2 and the lower surface of the umbrella portion 31b is substantially parallel to the top surface of the piston 4. Note that the exhaust valve 32 is configured in the same manner as the intake valve 31, for example, except for the size of the umbrella portion.

[0023] The upstream side of the intake port 33 extends along the lower surface of the cylinder head 3 in a direction substantially orthogonal to the axial direction of the cylinder 2, with the downstream end of the intake manifold 6a as the inlet. The downstream side of the intake port 33 is a bent portion 33b that bends and extends toward the opening of the intake port 33 that opens into the combustion chamber 5. Above the bent portion 33b in the intake port 33, a through-hole 33a through which the valve stem 31a of the intake valve 31 passes is open. Above the bent portion 33b in the intake port 33, the portion around the through-hole 33a has a thickness so as to surround the valve guide, and a bulging portion 33c bulging toward the internal space of the intake port 33 is formed.

[0024] The internal combustion engine 1 includes a mixing passage 10 provided along the intake port 33. The mixing passage 10 is a passage for intake air for promoting the mixing of hydrogen (gas fuel) and air while suppressing the state in which hydrogen fills the entire intake port 33. As a first example, the mixing passage 10 can be a pipe member 11 provided to extend from the upstream side to the downstream side inside the intake port 33. The pipe member 11 extends, for example, from the upstream side to the downstream side of the intake port 33, from the injector 8 toward the opening of the intake port 33 that opens into the combustion chamber 5, in a direction inclined with respect to the extending direction of the intake port 33. The pipe member 11 has an upstream end portion 11a disposed toward the downstream end of the intake manifold 6a and the injector 8, and a downstream end portion 11b disposed toward the opening of the intake port 33 that opens into the combustion chamber 5.

[0025] The pipe member 11 has a straight portion 11c that extends linearly coaxially with the injector 8 for a predetermined length from the upstream end portion 11a. The straight portion 11c can be, for example, a portion that extends linearly coaxially with the injector 8 from the upstream end portion 11a and reaches the inner wall surface below the intake port 33. Due to the straight portion 11c of the pipe member 11, it is difficult for the hydrogen injected from the injector 8 to hit the inner wall surface of the pipe member 11, and it becomes easier for the hydrogen injected from the injector 8 and the air to mix. The cross-sectional area of the pipe member 11 may be determined, for example, according to the design of the output characteristics of the internal combustion engine 1, the injection amount of hydrogen, etc.

[0026] FIG. 3 is a schematic plan view showing an introduction part of the mixing passage of the first example. In FIG. 3, in order to show the inside of the intake port 33, the boundary surface defining the internal space of the intake port 33 is cut away, but actually, where the metal part of the cylinder head 3 becomes hatched, it is illustrated for convenience as a thin-walled tube (the same in FIGS. 4, 7 to 10).

[0027] As shown in FIG. 3, the upstream end portion 11a of the tube member 11 is fixed to the inner wall surface of the intake port 33. The upstream end portion 11a is abutted, for example, around the through hole of the cylinder head 3 into which the injector 8 is inserted, and is fixed to the inner wall surface of the intake port 33. The upstream end portion 11a is arranged coaxially with the injector 8.

[0028] An introduction part 12 is provided on the upstream side of the intake port 33 in the tube member 11. The introduction part 12 is an opening for introducing air from the intake port 33 into the inside of the tube member 11. The introduction part 12 is formed, for example, by cutting away a part of the outer peripheral surface (for example, a half circumference of the outer peripheral surface) of the tube member 11 at the upstream end portion 11a. The introduction part 12 opens, for example, toward the upstream side in the air flow direction in the intake port 33. Inside the tube member 11, the tip of the injector 8 faces immediately inside the introduction part 12. That is, the injector 8 is provided so as to inject hydrogen toward the introduction part 12.

[0029] FIG. 4 is a schematic perspective view showing the outlet portion of the mixing passage of the first example. As shown in FIGS. 2 and 4, the downstream end portion 11b of the pipe member 11 is curved along the bent portion 33b of the intake port 33. The downstream end portion 11b of the pipe member 11 is curved, for example, along the inner wall surface on the lower side of the intake port 33 from the portion where the straight portion 11c extending from the upstream end portion 11a reaches the inner wall surface on the lower side of the intake port 33. The downstream end portion 11b of the pipe member 11 is curved downward along the bent portion 33b of the intake port 33 so that the axial direction of the pipe member 11 approaches the axial direction of the cylinder 2. The downstream end portion 11b of the pipe member 11 may be fixed to the inner wall surface of the intake port 33 by being sandwiched between the inner wall surface on the lower side of the intake port 33 and the bulging portion 33c on the upper side of the bent portion 33b.

[0030] An outlet portion 13 is provided on the downstream side of the intake port 33 in the pipe member 11. The outlet portion 13 is an opening for guiding gas fuel and air from the inside of the pipe member 11 to the intake port 33. The introduction portion 12 and the outlet portion 13 are arranged in this order from the upstream side to the downstream side, for example, along the flow direction of air in the intake port 33. The outlet portion 13 is, for example, the opening at the lower end of the pipe member 11 where the pipe member 11 is cut planar to have a circular cross section. In the example of FIG. 4, the outlet portion 13 opens toward the umbrella portion 31b along the axial direction of the cylinder 2.

[0031] FIG. 5 is a diagram for explaining the promotion of the mixing of gas fuel and air. In FIGS. 5(a) and (b), the outer cylinder 41 corresponds to the intake port, the inner cylinder 42 corresponds to the jet pipe of the prior art, and the inner cylinder 44 corresponds to the mixing passage. FIGS. 5(a) and (b) show, in grayscale, a state where gas fuel (black in the figure) is injected into the inner cylinder 42 and the inner cylinder 44, and the mixing of the air (white in the figure) and the gas fuel is simulated inside the outer cylinder 41.

[0032] Figure 5(a) shows a comparative example where the introduction part is not provided in the inner cylinder 42. In this case, when the gas fuel is injected into the inner cylinder 42, almost the entire inside of the inner cylinder 42 turns dark black. This means that the inside of the inner cylinder 42 is in a state filled with gas fuel. In this configuration, since the gas fuel and air start to mix behind the downstream end of the inner cylinder 42, it can be seen that it is difficult to achieve sufficient mixing of the gas fuel and air, for example, within the distance to the downstream end of the outer cylinder 41.

[0033] In Figure 5(b), the nozzle 43 of the gas fuel and the inner cylinder 44 have different diameters, and the gap between them functions as the introduction part. In this case, when the gas fuel is injected into the inner cylinder 44, the inside of the nozzle 43 is dark black, but inside the inner cylinder 44, the black color becomes lighter and there is a shading. This means that since air is introduced from the introduction part, the mixing of the gas fuel and air is progressing inside the inner cylinder 44 behind the introduction part. In this configuration, it can be seen that, compared with Figure 5(a), for example, there is a margin in the distance to the downstream end of the outer cylinder 41, and the mixing of the gas fuel and air is promoted.

[0034] Figure 6 is a diagram for explaining that it is difficult for gas fuel to remain inside the mixing passage. Figures 6(a) and (b) show, using the same configuration as Figures 5(a) and (b), the state of simulating the remaining gas fuel in the inner cylinders 42 and 44 after injecting the gas fuel into the inner cylinders 42 and 44, shown in grayscale.

[0035] Figure 6(a) shows a comparative example where the introduction part is not provided in the inner cylinder 42. In this case, after injecting the gas fuel into the inner cylinder 42, black portions remain in a gradation pattern over a wide range inside the inner cylinder 42. In this configuration, it can be seen that it is difficult to eliminate the state where the gas fuel remains inside the inner cylinder 42 after injecting the gas fuel into the inner cylinder 42 (for example, when the internal combustion engine stops).

[0036] In Fig. 6(b), after the gas fuel is injected into the inner cylinder 44, almost no black color remains in the inner cylinder 44. This means that since air is introduced from the introduction part, the gas fuel remaining inside the inner cylinder 44 is pushed out (purged) by the air introduced from the introduction part. In this configuration, it can be seen that compared with Fig. 6(a), after injecting the gas fuel into the inner cylinder 44 (for example, when the internal combustion engine stops), it becomes easier to eliminate the remaining gas fuel inside the inner cylinder 44.

[0037] Fig. 7 is a schematic plan view showing the lead-out part of the mixing passage of the first example. As shown in Fig. 7, the lead-out part 13 is located, for example, on the side opposite to the spark plug 9 of the cylinder 2 with respect to the valve stem 31a of the intake valve 31. In Fig. 7, the electrode of the spark plug 9 is shown at the lower right of the drawing. The spark plug 9 is attached to the cylinder head 3 so that the electrode faces, for example, near the center of the upper part of the combustion chamber 5 (see Fig. 11). In Fig. 7, when the direction viewed from the center of the intake valve 31 is represented by an angle with the counterclockwise direction as the positive sign in the plan view of Fig. 7 with the direction of the broken line as 0°, the center P of the lead-out part 13 is arranged at a position of about 225°. The center of the lead-out part 13 is not limited to the position of about 225°, and may be arranged, for example, within the range of 135° to 315°. The center P of the lead-out part 13 may be arranged at a position deeper from the spark plug (position of about 45°) than the virtual plane that is orthogonal to the virtual line connecting the spark plug and the valve stem 31a and extends including the axis of the valve stem 31a.

[0038] Here, FIG. 11 is a schematic cross-sectional view showing an example of the in-cylinder flow of an internal combustion engine of a comparative example. The internal combustion engine 100 in FIG. 11 differs from the internal combustion engine 1 in that it does not include the mixing passage 10. FIG. 11 shows the in-cylinder flow obtained by analyzing the distribution of the air excess ratio and the streamlines of the intake air when the intake valve 131 of the internal combustion engine 100 is open by simulation. As shown in FIG. 11, in the internal combustion engine 100, a vortex is generated in the combustion chamber 105 near the ignition plug 109. This vortex is formed because the air flow passing through the gap on the side farther from the ignition plug 109 (the left side in the figure) of the gap where the intake valve 131 is open collides with the top surface of the piston 104 and becomes a counterclockwise air flow in the figure, and collides with the air flow passing through the gap on the side closer to the ignition plug 109 (the right side in the figure) of the gap where the intake valve 131 is open. It can be considered that due to this vortex, hydrogen flowing from the intake port 133 into the combustion chamber 105 is easily drawn into the vicinity of the ignition plug 109, which may contribute to abnormal combustion such as backfire.

[0039] In this regard, by suppressing the hydrogen from the intake port from approaching the vicinity of the ignition plug, it may be possible to suppress abnormal combustion such as backfire. Therefore, as shown in FIG. 7, by positioning the lead-out portion 13 on the side opposite to the ignition plug 9 of the cylinder with respect to the valve stem 31a of the intake valve 31, the flow of hydrogen and air led out to the intake port 33 through the lead-out portion 13 is blocked by the valve stem 31a, making it difficult for hydrogen to approach the ignition plug 9. That is, it becomes possible to delay the inflow of hydrogen into the vicinity of the ignition plug 9 (to slow it down). When the inflow of hydrogen is delayed, the temperature of the ignition plug 9 decreases before the hydrogen approaches the ignition plug 9. Therefore, it is presumed to be effective in making it difficult for ignition to occur in abnormal combustion where hydrogen approaches the ignition plug 9 and ignites.

[0040] [Actions and Effects] In the internal combustion engine 1, hydrogen is injected by the injector 8 toward the inside of the mixing passage 10 provided along the intake port 33. Such a mixing passage 10 contributes to improving the air filling efficiency into the cylinder 2 and suppressing the occurrence of abnormal combustion such as backfire by suppressing the hydrogen filled in the intake port 33 from obstructing the air flow (air block effect) and suppressing the hydrogen from remaining in the intake port 33. Here, in the internal combustion engine 1, air from the intake port 33 is introduced into the inside of the mixing passage 10 through the introduction portion 12. Thereby, the injected hydrogen and the introduced air are mixed inside the mixing passage 10. The hydrogen and air mixed inside the mixing passage 10 are led out to the intake port 33 through the lead-out portion 13 and sucked into the cylinder 2. Therefore, for example, compared with the case where the introduction portion 12 is not provided or the mixing passage 10 itself is not provided, the mixing of hydrogen and air is promoted. Further, when the injection of hydrogen by the injector 8 stops, the hydrogen remaining inside the mixing passage 10 is pushed out (purged) to the lead-out portion 13 by the air introduced from the introduction portion 12. Therefore, when the internal combustion engine 1 stops, it is difficult for hydrogen to remain inside the mixing passage 10. Accordingly, according to the internal combustion engine 1, in the four-cycle port injection type internal combustion engine 1 using hydrogen as fuel, while improving the air filling efficiency into the cylinder 2 and suppressing the occurrence of abnormal combustion such as backfire, the mixing of hydrogen and air is promoted, and it becomes easier to eliminate the remaining of the unburned hydrogen injected inside the internal combustion engine 1.

[0041] The mixing passage 10 is a pipe member 11 provided so as to extend from the upstream side to the downstream side of the intake port 33 inside the intake port 33. An introduction portion 12 is provided on the upstream side of the intake port 33 in the pipe member 11, and a lead-out portion 13 is provided on the downstream side of the intake port 33 in the pipe member 11. The injector 8 is provided so as to inject hydrogen toward the introduction portion 12. Thereby, the pipe member 11 provided inside the intake port 33 can constitute the mixing passage 10 of the first example.

[0042] The derivation section 13 is located on the side opposite to the spark plug 9 of the cylinder 2 with respect to the valve stem 31a of the intake valve 31. Thereby, by utilizing the fact that the flow of hydrogen and air led to the intake port 33 through the derivation section 13 is obstructed by the valve stem 31a of the intake valve 31, it is possible to suppress the approach of hydrogen to the spark plug 9.

[0043] [Modification Example] As described above, the embodiments according to the present invention have been explained, but the present invention is not limited to the above-described respective embodiments.

[0044] In the above embodiment, the pipe member 11 is exemplified as the mixing passage 10, but it is not limited to this example. The mixing passage may be, for example, a pipe member 11A with the direction of the derivation section 13 changed as shown in FIG. 8. FIG. 8 is a schematic perspective view showing a modification example of the derivation section of the mixing passage of the first example. On the downstream side of the intake port 33 in the pipe member 11A, a derivation section 13A with a direction different from that of the derivation section 13 is provided. The derivation section 13A is inclined with respect to the axial direction of the cylinder 2 and opens toward the umbrella portion 31b. The center of the derivation section 13A may be arranged at a position aimed at, for example, about 270°, different from the position of 225° in FIG. 7. By thus inclining the derivation section 13A and opening it toward the umbrella portion 31b, hydrogen can be introduced into the cylinder 2 along the swirl flow in the cylinder 2.

[0045] In the above embodiment, the introduction section 12 opened toward the upstream side in the air flow direction in the intake port 33, but it is not limited to this example. The introduction section may open toward other than the upstream side in the air flow direction in the intake port 33. Alternatively, the introduction section may be a punching section including a large number of through holes penetrating in the radial direction of the pipe member 11.

[0046] In the above-described embodiment, the upstream end portion 11a abutted against the periphery of the through-hole of the cylinder head 3 into which the injector 8 is inserted, but the present invention is not limited to this example. For example, the outer peripheral surface of the pipe member 11 may be fixed to the inner wall surface of the intake port 33 via a member that functions as a stay, so that the entire end surface of the upstream end portion 11a may be separated from the injector 8 or the cylinder head 3.

[0047] Further, as another example of the mixing passage 10, for example, like the internal combustion engine 1A shown in FIGS. 9 and 10, a pipe member may not be used. FIG. 9 is a schematic perspective view showing a mixing passage of a second example. FIG. 10 is a schematic perspective view showing a lead-out portion of the mixing passage of the second example. The mixing passage 10 of the second example is a partial passage 15 partitioned by a partitioning member 14 provided so as to extend from the upstream side to the downstream side of the intake port 33 inside the intake port 33.

[0048] The partitioning member 14 is, for example, a plate-like member provided inside the intake port 33 so as to divide the space inside the intake port 33 into two along the extending direction of the intake port 33. The partitioning member 14 extends along the width direction of the intake port 33 so as to divide the space inside the intake port 33 into upper and lower parts on the upstream side of the intake port 33. The partitioning member 14 extends from the upstream side to the downstream side of the intake port 33 so as to face the opening of the intake port 33 that opens from the injector 8 to the combustion chamber 5. The partitioning member 14 is continuous with the inner wall surface of the intake port 33 at both ends in the width direction of the intake port 33. The partitioning member 14 may be integrally formed with the intake port 33 by casting. Alternatively, the partitioning member 14 may be a plate-like member separate from the intake port 33 joined to the inner wall surface of the intake port 33.

[0049] Here, the partial passage 15 is the upper space among the spaces obtained by dividing the space inside the intake port 33 into upper and lower parts. The cross-sectional area of the partial passage 15 may be determined, for example, according to the design of the output characteristics of the internal combustion engine 1, the injection amount of hydrogen, and the like. In the examples of FIGS. 9 and 10, the cross-sectional area of the upstream side of the partial passage 15 is equal to or smaller than the cross-sectional area of the portion of the intake port 33 excluding the partial passage 15.

[0050] An introduction part 16 is provided upstream of the intake port 33 in the partial passage 15. The introduction part 16 is an opening for introducing air from the intake port 33 into the interior of the partial passage 15. The introduction part 16 is, for example, the upper opening among the two divisions of the inlet opening of the intake port 33 in the connection part 6c with the intake manifold 6a in the vertical direction. The tip of the injector 8 faces the introduction part 16 inside the partial passage 15. That is, the injector 8 is provided to inject hydrogen toward the introduction part 16.

[0051] As shown in FIG. 10, at the downstream end 15a of the partial passage 15, the downstream end 14a of the partitioning member 14 is curved along the bent part 33b of the intake port 33. The end face of the downstream end 14a of the partitioning member 14 is located deeper than the valve stem 31a of the intake valve 31 when viewed from the upstream side of the intake port 33. Therefore, the cross-sectional area on the downstream side of the partial passage 15 is made smaller than the cross-sectional area of the part excluding the partial passage 15 of the intake port 33. At the downstream end 14a of the partitioning member 14, a through hole 14b for inserting the valve stem 31a of the intake valve 31 is provided. At the downstream end 14a of the partitioning member 14, a recess 14c may be provided so as not to interfere with the umbrella part 31b of the intake valve 31 in the closed valve state.

[0052] A derivation part 17 is provided downstream of the intake port 33 in the partial passage 15. The derivation part 17 is an opening for deriving gas fuel and air from the interior of the partial passage 15 to the intake port 33. The derivation part 17 is, for example, the opening at the lower end of the downstream end 15a of the partial passage 15. In the example of FIG. 10, the derivation part 17 is located on the side opposite to the ignition plug 9 of the cylinder 2 with respect to the valve stem 31a of the intake valve 31 and opens toward the umbrella part 31b. In the internal combustion engine 1A, the ignition plug 9 is arranged in the same manner as in FIG. 7.

[0053] In the mixing passage 10 of the second example as described above, the mixing passage 10 is a partial passage 15 partitioned by a partitioning member 14 provided so as to extend from the upstream side to the downstream side of the intake port 33 inside the intake port 33. An introduction part 16 is provided on the upstream side of the intake port 33 in the partial passage 15. A lead-out part 17 is provided on the downstream side of the intake port 33 in the partial passage 15. The injector 8 is provided so as to inject hydrogen toward the introduction part 16. Thereby, the partial passage 15 partitioned by the partitioning member 14 provided inside the intake port 33 can constitute the mixing passage 10 of the second example. In this configuration, compared with the case of using the pipe member 11, the mountability can be improved in that the trouble of mounting the pipe member 11 can be saved.

[0054] In the above-described embodiment, the lead-out parts 13 and 17 were located on the side opposite to the spark plug 9 of the cylinder 2 with respect to the valve stem 31a of the intake valve 31, but this arrangement is not essential.

[0055] In the above-described embodiment, the introduction part 12 of the pipe member 11 and the introduction part 16 of the partial passage 15 were provided at their respective upstream end parts, but they may be provided at positions other than the upstream end parts (for example, positions other than the upstream end parts within their respective upstream ranges). The lead-out part 13 of the pipe member 11 and the lead-out part 17 of the partial passage 15 were provided at their respective downstream end parts, but they may be provided at positions other than the downstream end parts (for example, positions other than the downstream end parts within their respective downstream ranges).

[0056] In the above-described embodiment, the introduction part 12 and the lead-out part 13 were arranged in this order from the upstream side to the downstream side, for example, along the air flow direction in the intake port 33, but the present invention is not limited to this example. The introduction part and the lead-out part may be arranged in the reverse order from the upstream side to the downstream side, for example, along the air flow direction in the intake port 33. In this case, the mixing passage may be a loop-shaped passage that passes outside the intake port along the intake port so as to introduce air from the introduction part arranged on the downstream side of the air flow direction in the intake port 33 and lead out air from the lead-out part arranged on the upstream side of the air flow direction in the intake port 33.

[0057] Hereinafter, the constituent elements of various aspects of the present invention will be described. [1] A four-cycle port injection internal combustion engine using gas fuel as fuel, a mixing passage provided along the intake port, and a fuel injection valve provided to inject the gas fuel toward the inside of the mixing passage. The mixing passage has an introduction part for introducing air from the intake port into the inside of the mixing passage, and a lead-out part for leading out the gas fuel and the air from the inside of the mixing passage to the intake port. The internal combustion engine. [2] The mixing passage is a pipe member provided so as to extend from the upstream side to the downstream side of the intake port inside the intake port, the introduction part is provided on the upstream side of the intake port in the pipe member, the lead-out part is provided on the downstream side of the intake port in the pipe member, The fuel injection valve is provided to inject the gas fuel toward the introduction part. The internal combustion engine according to [1]. [3] The mixing passage is a partial passage partitioned by a partition member provided so as to extend from the upstream side to the downstream side of the intake port inside the intake port, the introduction part is provided on the upstream side of the intake port in the partial passage, the lead-out part is provided on the downstream side of the intake port in the partial passage, The fuel injection valve is provided to inject the gas fuel toward the introduction part. The internal combustion engine according to [1]. [4] The lead-out part is located on the side opposite to the ignition plug of the cylinder with respect to the valve stem of the intake valve. The internal combustion engine according to any one of [1] to [3].

Explanation of reference numerals

[0058] 1,1A…Internal combustion engine, 2…Cylinder, 8…Injector (fuel injection valve), 9…Spark plug, 10…Mixing passage, 11,11A…Pipe member, 12,16…Introduction part, 13,13A,17…Outlet part, 14…Partition member, 15…Partial passage, 31…Intake valve, 31a…Valve stem, 33…Intake port.

Claims

1. A four-cycle port injection internal combustion engine that uses gas fuel as fuel, a mixing passage provided along the intake port, and a fuel injection valve provided to inject the gas fuel toward the inside of the mixing passage, and the mixing passage has an introduction part that introduces air from the intake port into the inside of the mixing passage, and a derivation part that derives the gas fuel and the air from the inside of the mixing passage to the intake port. An internal combustion engine.

2. The mixing passage is a pipe member provided so as to extend from the upstream side to the downstream side of the intake port inside the intake port, the introduction part is provided on the upstream side of the intake port in the pipe member, the derivation part is provided on the downstream side of the intake port in the pipe member, The internal combustion engine according to claim 1, wherein the fuel injection valve is provided to inject the gas fuel toward the introduction part.

3. The mixing passage is a partial passage partitioned by a partition member provided so as to extend from the upstream side to the downstream side of the intake port inside the intake port, the introduction part is provided on the upstream side of the intake port in the partial passage, the derivation part is provided on the downstream side of the intake port in the partial passage, The internal combustion engine according to claim 1, wherein the fuel injection valve is provided to inject the gas fuel toward the introduction part.

4. The internal combustion engine according to claim 2 or 3, wherein the derivation part is located on the side opposite to the ignition plug of the cylinder with respect to the valve stem of the intake valve.

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