Fuel supply system and fuel supply method

Abstract

To provide a configuration that prevents an auxiliary valve from impairing flexibility of a shape of an auxiliary combustion chamber in a fuel supply system for supplying fuel by using an auxiliary supply passage.SOLUTION: A fuel supply system 1 includes an intake port 10, an intake valve 13, an auxiliary supply passage 20 and an auxiliary valve 23. The intake port 10 is a flow passage for supplying an air-fuel mixture to a main combustion chamber 4. The intake valve 13 is disposed between the intake port 10 and the main combustion chamber 4, and enables switching between an open state where the air-fuel mixture is caused to flow into the main combustion chamber 4 and a closed state where a space between the intake port 10 and the main combustion chamber 4 is closed. The auxiliary supply passage 20 connects the intake port 10 and the auxiliary combustion chamber 5. The auxiliary valve 23 is disposed in a middle part of the auxiliary supply passage 20, and enables switching between an open state where the air-fuel mixture is caused to flow into the auxiliary combustion chamber 5 and a closed state where the auxiliary supply passage 20 is closed.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] This application relates primarily to a fuel supply system that supplies fuel to a pre-combustion chamber of an engine. [Background technology]

[0002] Patent Document 1 discloses a gas engine equipped with a pre-chamber gas valve. A pre-chamber gas passage is formed in the cylinder head of the gas engine of Patent Document 1. A pre-chamber gas valve is disposed at the boundary between the pre-chamber gas passage and the pre-chamber. When open, the pre-chamber gas valve is located inside the pre-chamber. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2002-303165 Summary of the Invention [Problem to be solved by the invention]

[0004] In the gas engine of Patent Document 1, the pre-chamber gas valve occupies a certain area of ​​the pre-chamber when open, so the shape of the pre-chamber needs to be determined based on the position, movement, size, etc. of the pre-chamber gas valve.

[0005] Considering the technology disclosed in Patent Document 1, in a conventional fuel supply system, when an auxiliary supply passage for supplying fuel to the auxiliary combustion chamber is provided, the degree of freedom in the shape of the auxiliary chamber tends to be low.

[0006] The present application has been made in consideration of the above circumstances, and its main purpose is to provide a fuel supply system that supplies fuel using a secondary supply passage, in which the secondary valve does not hinder the freedom of designing the secondary combustion chamber. [Means for solving the problem]

[0007] The problem to be solved by the present application is as described above. Next, the means for solving this problem and the effects thereof will be explained.

[0008] According to an aspect of the present application, there is provided a fuel supply system having the following configuration. That is, the fuel supply system includes an intake port, an intake valve, an auxiliary supply passage, and an auxiliary valve. The intake port is a flow path that supplies an air-fuel mixture to a main combustion chamber. The intake valve is disposed between the intake port and the main combustion chamber, and is switchable between an open state that allows the mixture to flow into the main combustion chamber and a closed state that closes the communication between the intake port and the main combustion chamber. The auxiliary supply passage connects the intake port and the auxiliary combustion chamber. The auxiliary valve is disposed midway through the auxiliary supply passage, and is switchable between an open state that allows the mixture to flow into the auxiliary combustion chamber and a closed state that closes the auxiliary supply passage. [Effects of the Invention]

[0009] According to the present application, it is possible to realize a fuel supply system in which the sub-valve does not hinder the degree of freedom in the shape of the sub-combustion chamber. [Brief explanation of the drawings]

[0010] [Figure 1] 1 is a cross-sectional view of a fuel supply system according to an embodiment of the present application; [Figure 2] FIG. 10 is a perspective view showing two first auxiliary supply passages joining together into one valve passage. [Figure 3] FIG. 10 is a cross-sectional view of the vicinity of the sub-valve when the sub-supply passage is in an open state. [Figure 4] Cross section AA of Figure 3. [Figure 5] FIG. 10 is a cross-sectional view of the vicinity of the sub-valve when the sub-supply passage is in a closed state. [Figure 6] Cross section B-B of Figure 5. [Figure 7] 6 is a graph showing the change over time in the concentration of the mixture near the connecting hole, the fuel injection period, the intake valve opening period, and the auxiliary valve opening period. DETAILED DESCRIPTION OF THE INVENTION

[0011] Next, an embodiment of the present application will be described with reference to the drawings.

[0012] A fuel supply system 1 of this embodiment shown in Fig. 1 is provided to an engine 2. The fuel supply system 1 supplies fuel to a combustion chamber 3 of the engine 2. The fuel used in the engine 2 may be a liquid fuel such as gasoline, or a gas fuel such as natural gas or hydrogen.

[0013] As shown in FIG. 1, the engine 2 has an intake port 10. Air taken in from outside the engine 2 flows through the intake port 10. An injector 11 is also provided in the intake port 10. The injector 11 injects fuel into the intake port 10. In particular, when the fuel is liquid fuel, the intake port 10 injects the liquid fuel in the form of a mist. In the intake port 10, the injected fuel mixes with air. Hereinafter, a gaseous substance formed by mixing air and fuel is referred to as an air-fuel mixture. Note that the injector 11 is not an essential component. For example, when the fuel is gaseous fuel, the fuel may be supplied by opening and closing a fuel valve that supplies the fuel.

[0014] An intake hole 12 is formed between the intake port 10 and the combustion chamber 3, and an intake valve 13 is provided therebetween. The intake valve 13 includes a valve head 13a and a valve stem 13b.

[0015] The valve head 13a is positioned at a position where it can block the intake hole 12. When the valve head 13a blocks the intake hole 12, the air-fuel mixture in the intake port 10 does not flow into the combustion chamber 3. Hereinafter, the state in which the intake hole 12 is blocked and the air-fuel mixture in the intake port 10 cannot flow into the combustion chamber 3 will be referred to as the "closed state." Furthermore, when the valve head 13a moves and the intake hole 12 is opened, the air-fuel mixture in the intake port 10 flows into the combustion chamber 3 through the intake hole 12. Hereinafter, the state in which the intake hole 12 is open and the air-fuel mixture in the intake port 10 can flow into the combustion chamber 3 will be referred to as the "open state."

[0016] The valve stem 13b is a rod-shaped member connected to the valve head 13a. The valve stem 13b passes through an insertion hole 14 formed in the intake port 10 and extends through the wall of the intake port 10 toward the intake camshaft 30 located outside the intake port 10. The valve stem 13b is biased toward the intake camshaft 30. The intake cam 31 of the intake camshaft 30 acts to press the valve stem 13b, causing the valve head 13a to move away from the intake port 12 toward the combustion chamber 3. This switches the intake valve 13 from a closed state to an open state. After that, the action of the intake cam 31 is released, causing the biasing force to move the valve stem 13b toward the intake camshaft 30 again, and the valve head 13a closes the intake port 12. This switches the intake valve 13 from an open state to a closed state.

[0017] The combustion chamber 3 of the engine 2 of this embodiment has a main combustion chamber 4 and an auxiliary combustion chamber 5. The main combustion chamber 4 is the space where most of the combustion in the engine 2 occurs. An air-fuel mixture is supplied to the main combustion chamber 4 through an intake hole 12 of an intake port 10. The piston 6 is driven to reciprocate by the combustion that occurs in the main combustion chamber 4. The auxiliary combustion chamber 5 has a smaller space than the main combustion chamber 4. The air-fuel mixture is supplied to the auxiliary combustion chamber 5 through an auxiliary supply passage 20, which will be described later. An ignition plug 7 is provided in the auxiliary combustion chamber 5. The action of the spark plug 7 ignites the air-fuel mixture in the auxiliary combustion chamber 5. By providing the auxiliary combustion chamber 5 in addition to the main combustion chamber 4, it is possible to stabilize combustion, for example.

[0018] In the gas flow direction in the intake port 10, a connection hole 15 is formed downstream of the insertion hole 14. The gas flow direction in the intake port 10 is the direction from the upstream end to the downstream end along the flow path of the intake port 10. The downstream end of the intake port 10 is the intake hole 12. The "gas" in the gas flow direction refers to air or an air-fuel mixture.

[0019] An auxiliary supply passage 20 is connected to the connecting hole 15. The auxiliary supply passage 20 is a flow path that connects the intake port 10 and the auxiliary combustion chamber 5. The flow path cross-sectional area of ​​the auxiliary supply passage 20 is smaller than the flow path cross-sectional area of ​​the intake port 10. The auxiliary supply passage 20 is connected to a side surface of the auxiliary combustion chamber 5, in other words, a surface different from the surface on which the ignition plug 7 is provided. This allows the auxiliary supply passage 20 to be connected to the auxiliary combustion chamber 5 while ensuring space for providing the ignition plug 7.

[0020] To effectively utilize the auxiliary combustion chamber 5, it is necessary to supply a sufficient amount of fuel to the auxiliary combustion chamber 5. Therefore, in this embodiment, the injector 11 injects fuel toward the connecting hole 15 to facilitate the supply of fuel to the auxiliary combustion chamber 5. "Toward the connecting hole 15" means that the connecting hole 15 is located on an extension of the axial direction of the injector 11, or that the connecting hole 15 is located within a range of a locus obtained by changing the extension of the axial direction of the injector 11 by a predetermined angle. The predetermined angle is, for example, ±15 degrees up or down. Note that the extension of the axial direction of the injector 11 may overlap the connecting hole 15 or may overlap the range between the connecting hole 15 and the downstream end of the intake port 10.

[0021] When the injector 11 injects fuel toward the connecting hole 15, if liquid fuel is injected, the fuel adheres to the periphery of the connecting hole 15. The adhered fuel vaporizes and then mixes with air. This tends to increase the concentration of fuel around the connecting hole 15. Also, when gaseous fuel is injected, the fuel is injected toward the connecting hole 15, so the concentration of fuel around the connecting hole 15 tends to increase. As described above, in this embodiment, the concentration of fuel heading from the auxiliary supply passage 20 toward the auxiliary combustion chamber 5 can be increased.

[0022] The auxiliary supply passage 20 has a first auxiliary supply passage 21 and a second auxiliary supply passage 22. A valve passage 28 is provided at the boundary between the first auxiliary supply passage 21 and the second auxiliary supply passage 22. In other words, the first auxiliary supply passage 21 is a flow path that connects the intake port 10 and the valve passage 28. The second auxiliary supply passage 22 is a flow path that connects the valve passage 28 and the auxiliary combustion chamber 5.

[0023] As shown in FIG. 2, the engine 2 of this embodiment has two intake ports 10. For the purpose of describing FIG. 2 only, the two intake ports 10 will be distinguished and referred to as a first intake port 10a and a second intake port 10b, respectively. A first auxiliary supply passage 21 is connected to each of the first intake port 10a and the second intake port 10b. These two first auxiliary supply passages 21 are connected to a single valve passage 28. In other words, the first auxiliary supply passage 21 connected to the first intake port 10a and the first auxiliary supply passage 21 connected to the second intake port 10b merge in the valve passage 28. The valve passage 28 and the auxiliary combustion chamber 5 are connected by a single second auxiliary supply passage 22.

[0024] With this configuration, the number of valve passages 28 and second auxiliary supply passages 22 can be reduced compared to a configuration in which a valve passage 28 and a second auxiliary supply passage 22 are provided for each intake port 10, thereby simplifying the piping. Note that this configuration is not essential, and another configuration in which a valve passage 28 and a second auxiliary supply passage 22 are provided individually for the first intake port 10a and the second intake port 10b may be employed. In this other configuration, the two second auxiliary supply passages 22 may be connected individually to the auxiliary combustion chamber 5, or the two second auxiliary supply passages 22 may be joined and connected to the auxiliary combustion chamber 5. Furthermore, the engine 2 may be provided with one intake port 10, or three or more intake ports 10.

[0025] The valve passage 28 is a linear passage with a circular cross section. The valve passage 28 intersects with the secondary supply passage 20. The valve passage 28 extends toward the intake camshaft 30. The secondary valve 23 is disposed in the valve passage 28. The secondary valve 23 includes a rod-shaped body 24 and a biasing member 25. The rod-shaped body 24 is a rod-shaped member with a circular cross section. The axial direction of the rod-shaped body 24 coincides with the axial direction of the valve passage 28. The diameter of a cross section of the rod-shaped body 24 cut in the axial direction substantially coincides with the diameter of the valve passage 28 cut in the same direction. In other words, the rod-shaped body 24 is disposed so that there is almost no gap between the rod-shaped body 24 and the valve passage 28. The biasing member 25 biases one end of the rod-shaped body 24 toward the intake camshaft 30. As a result, the other end of the rod-shaped body 24 is pressed against the secondary cam 32 of the intake camshaft 30. With this configuration, the sub-cam 32 of the intake camshaft 30 acts to press the rod-shaped body 24 , causing the rod-shaped body 24 to move away from the intake camshaft 30 .

[0026] Further, a through hole 26 is formed in the rod-shaped body 24. The axial direction of the through hole 26 is a direction connecting the first sub-supply passage 21 and the second sub-supply passage 22. In other words, by aligning the position of the through hole 26 with the positions of the first sub-supply passage 21 and the second sub-supply passage 22, the first sub-supply passage 21 and the second sub-supply passage 22 are connected via the through hole 26. This allows the air-fuel mixture to flow into the sub-combustion chamber 5 via the sub-supply passage 20. Hereinafter, this state will be referred to as the "open state." Figures 3 and 4 show the sub-valve 23 in the open state. As shown in Figure 3, the open state occurs when the sub-cam 32 acts to press the rod-shaped body 24 toward the biasing member 25.

[0027] Furthermore, as the action of the sub-cam 32 is released, the rod-shaped body 24 is urged by the urging member 25 and moves closer to the intake camshaft 30. In this state, the position of the through-hole 26 does not match the positions of the first sub-supply passage 21 and the second sub-supply passage 22. As a result, the air-fuel mixture cannot flow into the sub-combustion chamber 5 via the sub-supply passage 20. Hereinafter, this state will be referred to as the "closed state." Figures 5 and 6 show the sub-valve 23 in the closed state.

[0028] With this configuration, by determining an appropriate shape for the sub-cam 32, it is possible to cause the air-fuel mixture to flow at appropriate timing into the sub-combustion chamber 5. The timing for operating each component of the fuel supply system 1 will be described later.

[0029] 6, there is a small gap between the rod-shaped body 24 and the valve passage 28. Therefore, even when the sub-valve 23 is closed, the first sub-supply passage 21 and the second sub-supply passage 22, which are in a closed state, may be connected through this gap. In this regard, in this embodiment, a sealing portion 27 for closing this gap is formed on the rod-shaped body 24. The sealing portion 27 is an elastically deformable protrusion. When the sealing portion 27 is pressed against the valve passage 28, the sealing portion 27 elastically deforms and seals the gap.

[0030] The rod-shaped body 24 is preferably formed with both a sealing portion 27 for covering the gap between the rod-shaped body 24 and the valve passage 28 on the first sub-supply passage 21 side and a sealing portion 27 for covering the gap between the rod-shaped body 24 and the valve passage 28 on the second sub-supply passage 22 side. However, only one of the sealing portions 27 may be formed on the rod-shaped body 24. The sealing portion 27 may be integrally molded with the rod-shaped body 24 or may be a separate member. The sealing portion 27 is preferably loop-shaped (closed circuit-shaped) so as to cover the periphery of the gap between the rod-shaped body 24 and the valve passage 28 on the first sub-supply passage 21 side. Similarly, the sealing portion 27 is preferably loop-shaped (closed circuit-shaped) so as to cover the periphery of the gap between the rod-shaped body 24 and the valve passage 28 on the second sub-supply passage 22 side. This improves the sealing performance when the sub-valve 23 is closed.

[0031] The sub-valve 23 in this embodiment is located midway through the sub-supply passage 20. This means that the sub-valve 23 is not located inside the sub-combustion chamber 5. As a result, the position, size, operation, etc. of the sub-valve 23 do not need to be taken into consideration when designing the sub-combustion chamber 5. Therefore, in this embodiment, there is a greater degree of freedom in the shape of the sub-combustion chamber 5 compared to a configuration in which the sub-valve 23 is located in the sub-combustion chamber 5.

[0032] The engine 2 also has an exhaust port 40. Similar to the intake side, the exhaust port 40 is provided with an exhaust hole 41 and an exhaust valve 42. By operating the exhaust valve 42, exhaust gas, which is a gas after combustion present in the main combustion chamber 4, can be discharged from the main combustion chamber 4 to the exhaust port 40 at an appropriate timing.

[0033] Next, with reference to FIG. 7, the operation timing of each component of the fuel supply system 1, particularly the operation timing of the sub-valve 23, will be described.

[0034] The engine 2 of this embodiment is a four-stroke engine, and is divided into an intake stroke, a compression stroke, an expansion stroke (in other words, a combustion stroke), and an exhaust stroke according to the crank angle. As described above, when the injector 11 injects liquid fuel, the fuel adhering to the vicinity of the connecting hole 15 is vaporized and then mixed with air. Therefore, as shown in FIG. 7, there is a time lag between the completion of fuel injection and the time when the fuel concentration near the connecting hole 15 increases.

[0035] Taking this into consideration, in this embodiment, fuel injection into the intake port 10 is performed early. Specifically, fuel injection starts in the latter half of the expansion stroke and ends in the first half of the exhaust stroke. Note that this period is just an example, and fuel injection may start in the first half of the exhaust stroke or end in the second half of the exhaust stroke.

[0036] Furthermore, in order to allow fuel to flow from the auxiliary supply passage 20 into the auxiliary combustion chamber 5, it is necessary to open the intake valve 13 to create a pressure difference. Therefore, it is preferable that the timing at which the auxiliary valve 23 switches to its open state is the same as or after the intake valve 13 switches to its open state. If there is too much difference in the switching timing between the auxiliary valve 23 and the intake valve 13, the air-fuel mixture will be supplied to the main combustion chamber 4 through the intake hole 12, reducing the fuel concentration. Therefore, it is preferable that the switching timing of the auxiliary valve 23 and the intake valve 13 be close to each other. For example, it is preferable that the difference in crank angle be several degrees (e.g., 2 degrees or less or 5 degrees or less).

[0037] As described above, the fuel supply system 1 of this embodiment includes the intake port 10, the intake valve 13, the auxiliary supply passage 20, and the auxiliary valve 23. The intake port 10 is a passage that supplies an air-fuel mixture to the main combustion chamber 4. The intake valve 13 is disposed between the intake port 10 and the main combustion chamber 4, and is switchable between an open state that allows the mixture to flow into the main combustion chamber 4 and a closed state that closes the communication between the intake port 10 and the main combustion chamber 4. The auxiliary supply passage 20 connects the intake port 10 and the auxiliary combustion chamber 5. The auxiliary valve 23 is disposed midway through the auxiliary supply passage 20, and is switchable between an open state that allows the mixture to flow into the auxiliary combustion chamber 5 and a closed state that closes the auxiliary supply passage 20. This completes Feature 1.

[0038] Since the sub-valve 23 is disposed in the middle of the sub-supply passage 20, the sub-valve 23 does not hinder the degree of freedom in the shape of the sub-combustion chamber 5.

[0039] The fuel supply system 1 of this embodiment includes an injector 11 that injects fuel into an intake port 10. The injector 11 starts injecting fuel during the expansion stroke or the exhaust stroke of the four-stroke cycle, and stops injecting fuel before the sub-valve 23 opens. This is Feature 2.

[0040] As a result, the sub-valve 23 opens after the concentration of fuel in the intake port 10 becomes high. As a result, high-concentration fuel is more likely to be supplied to the sub-combustion chamber 5.

[0041] The fuel supply system 1 of this embodiment includes an injector 11 that injects fuel into an intake port 10. A connection hole 15 to which a sub-supply passage 20 is connected is formed in the intake port 10. The injector 11 injects fuel toward the connection hole 15. This is Feature 3.

[0042] Since fuel is more likely to be present in the vicinity of the connecting hole 15, the concentration of fuel is more likely to be high in the vicinity of the connecting hole 15. As a result, fuel is more likely to be supplied to the auxiliary combustion chamber 5.

[0043] In the fuel supply system 1 of this embodiment, the intake valve 13 has a valve head 13a and a rod-shaped valve stem 13b. The valve head 13a closes the space between the intake port 10 and the main combustion chamber 4. The rod-shaped valve stem 13b is connected to the valve head 13a and extends toward the intake camshaft 30. The intake port 10 is formed with an insertion hole 14 through which the valve stem 13b is inserted, and a connection hole 15 to which the secondary supply passage 20 is connected. The connection hole 15 is formed downstream of the insertion hole 14 in the gas flow direction in the intake port 10. This is Feature 4.

[0044] Since the auxiliary supply passage 20 can be connected relatively downstream of the intake port 10, fuel can be easily supplied to the auxiliary combustion chamber 5.

[0045] In the fuel supply system 1 of this embodiment, the connection hole 15 is formed between the insertion hole 14 and the downstream end of the intake port 10 in the gas flow direction in the intake port 10. This is the fifth feature.

[0046] The sub-supply passage 20 can be connected to a position that is relatively downstream of the intake port 10 and is less likely to interfere with the valve stem 13b.

[0047] The fuel supply system 1 of this embodiment includes an injector 11 that injects fuel into the intake port 10. The injector 11 injects fuel toward a range downstream of the insertion hole 14 and upstream of the downstream end of the intake port 10 in the gas flow direction in the intake port 10. This is Feature 6.

[0048] The fuel adheres to the area where the connecting hole 15 is formed, which tends to increase the concentration of fuel near the connecting hole 15. As a result, the fuel is more easily supplied to the auxiliary combustion chamber 5.

[0049] In the fuel supply system 1 of this embodiment, the sub-valve 23 is a rod-shaped valve arranged so as to intersect with the sub-supply passage 20. The rod-shaped valve is driven by the intake camshaft 30. This is the seventh feature.

[0050] Driving the sub valve 23 with the sub cam 32 attached to the intake camshaft 30 simplifies the structure and makes it easier to synchronize the operation timing with the intake valve 13 compared to when a dedicated drive mechanism is provided for the sub valve 23. Furthermore, by using a rod-shaped valve, the sub valve 23 can be arranged linearly from the sub supply passage 20 toward the intake camshaft 30, thereby reducing the space occupied by the sub valve 23.

[0051] In the fuel supply system 1 of this embodiment, the sub-valve 23 is inserted into a valve passage 28 that intersects with the sub-supply passage 20. The sub-valve 23 has a rod-shaped body 24 with a through hole 26 formed therein. The sub-valve 23 is opened when the through hole 26 is aligned with the sub-supply passage 20, and the sub-valve 23 is closed when the part of the rod-shaped body 24 other than the through hole 26 is aligned with the sub-supply passage 20. This is Feature 8.

[0052] The simple and compact structure allows switching between open and closed states.

[0053] In the fuel supply system 1 of this embodiment, the sub-valve 23 is formed with a sealing portion 27. The sealing portion 27 closes the space connecting the gap between the valve passage 28 and the rod-shaped body 24 with the sub-supply passage 20. This is Feature 9.

[0054] Using a simple structure, it is possible to prevent fuel from flowing in through the gap between the valve passage 28 and the rod-shaped body 24.

[0055] The fuel supply system 1 of this embodiment has a first intake port 10a and a second intake port 10b as intake ports 10. The auxiliary supply passage 20 of the first intake port 10a and the auxiliary supply passage 20 of the second intake port 10b join together and are then connected to the auxiliary combustion chamber 5. An auxiliary valve 23 is disposed downstream of the joining point of the auxiliary supply passages 20. This is feature 10.

[0056] Since the sub-valve 23 can be shared, the structure can be simplified.

[0057] In this embodiment, the fuel supply method is performed as follows. In the fuel supply method, fuel is supplied to the combustion chamber 3, which includes the main combustion chamber 4 and the auxiliary combustion chamber 5, via the intake port 10. In the fuel supply method, the injector 11 starts injecting fuel into the intake port 10 during the expansion stroke or the exhaust stroke of the four-stroke cycle. In the fuel supply method, after the injector 11 stops injecting fuel, the intake valve 13 is operated to allow the air-fuel mixture to flow from the intake port 10 into the main combustion chamber 4, and the auxiliary valve 23 is operated to allow the air-fuel mixture to flow from the intake port 10 into the auxiliary combustion chamber 5 via the auxiliary supply passage 20.

[0058] As a result, the sub-valve 23 opens after the concentration of fuel in the intake port 10 becomes high. As a result, high-concentration fuel is more likely to be supplied to the sub-combustion chamber 5.

[0059] The above-described features 1 to 10 can be combined as follows to realize the fuel supply system 1. The same applies to the method. [Configuration 1] Fuel supply system 1 having feature 1. [Configuration 2] In addition to configuration 1, the fuel supply system 1 further has feature 2. [Configuration 3] In addition to configuration 1 or 2, the fuel supply system 1 further has feature 3. [Configuration 4] A fuel supply system 1 having any one of configurations 1 to 3, and further having feature 4. [Configuration 5] In addition to configuration 4, the fuel supply system 1 further has feature 5. [Configuration 6] A fuel supply system 1 having any one of configurations 1 to 5, and further having feature 6. [Configuration 7] A fuel supply system 1 having any one of configurations 1 to 6, and further having feature 7. [Configuration 8] A fuel supply system 1 having any one of configurations 1 to 7, and further having feature 8. [Configuration 9] A fuel supply system 1 having any one of configurations 1 to 8, and further having feature 9.

[0060] The preferred embodiment of the present application has been described above, but the above configuration can be modified, for example, as follows. Each modification may be made alone, or multiple modifications may be made in any combination.

[0061] The auxiliary supply channel 20 (specifically, the second auxiliary supply channel 22) in the above embodiment includes a bent or curved flow path. Alternatively, the auxiliary supply channel 20 may be a straight flow path.

[0062] In the above embodiment, the sub-valve 23 is driven by the intake camshaft 30. Alternatively, the sub-valve 23 may be driven by a cam connected to a shaft different from that of the cam that drives the intake valve 13. Also, instead of using a cam to switch between the open and closed states, an electric device such as an electromagnetic valve may be used to switch between the open and closed states.

[0063] In the above embodiment, the connection hole 15 is formed downstream of the insertion hole 14 in the gas flow direction in the intake port 10, but the connection hole 15 may be formed upstream of the insertion hole 14.

[0064] In the configuration according to the invention that focuses on the operation timing of the sub-valve 23 described above, the sub-valve 23 may be provided at the downstream end of the sub-supply passage 20 or at the boundary between the sub-supply passage 20 and the sub-combustion chamber 5. [Explanation of symbols]

[0065] 1 Fuel supply system 2 engines 3 Combustion chamber 4 Main combustion chamber 5 Pre-combustion chamber 10 Intake port 11 Injector 12 Air intake 13 Intake valve 20 Sub-supply channel 21 1st sub-supply route 22 Second sub-supply route 23 Sub-valve

Claims

1. an intake port which is a flow path that supplies a mixture of air and fuel to the main combustion chamber; an intake valve disposed between the intake port and the main combustion chamber, switchable between an open state that allows the air-fuel mixture to flow into the main combustion chamber and a closed state that closes the space between the intake port and the main combustion chamber; a secondary supply passage connecting the intake port and the secondary combustion chamber; an auxiliary valve disposed midway through the auxiliary supply passage and switchable between an open state in which the air-fuel mixture flows into the auxiliary combustion chamber and a closed state in which the auxiliary supply passage is closed; A fuel supply system comprising:

2. 2. The fuel supply system of claim 1, an injector that injects fuel into the intake port; The injector starts injecting fuel during the expansion stroke or the exhaust stroke of the four-stroke cycle, and stops injecting fuel before the sub-valve is opened.

3. 2. The fuel supply system of claim 1, an injector that injects fuel into the intake port; a connection hole to which the sub-supply passage is connected is formed in the intake port; The injector injects fuel toward the connecting hole.

4. 2. The fuel supply system of claim 1, The intake valve is a valve head that closes the gap between the intake port and the main combustion chamber; a rod-shaped valve stem connected to the valve head and extending toward an intake camshaft; It has The intake port is formed with an insertion hole through which the valve stem is inserted and a connection hole to which the sub-supply passage is connected, a connecting hole formed downstream of the insertion hole in a gas flow direction in the intake port;

5. 5. The fuel supply system of claim 4, a connecting hole formed between the insertion hole and a downstream end of the intake port in a gas flow direction in the intake port;

6. 6. The fuel supply system of claim 5, an injector that injects fuel into the intake port; The injector injects fuel toward a range downstream of the insertion hole and upstream of a downstream end of the intake port in a gas flow direction in the intake port.

7. 2. The fuel supply system of claim 1, the secondary valve is a rod-shaped valve arranged to cross the secondary supply passage, A fuel delivery system wherein the stem valve is driven by an intake camshaft.

8. 2. The fuel supply system of claim 1, the sub-valve is a rod-shaped valve inserted into a valve passage that intersects with the sub-supply passage, The rod-shaped valve has a rod-shaped body having a through hole formed therein, The sub-valve is in the open state when the through hole is aligned with the sub-supply passage, and the sub-valve is in the closed state when the part of the rod-shaped body other than the through hole is aligned with the sub-supply passage.

9. 9. The fuel supply system of claim 8, The rod-shaped valve has a sealing portion formed thereon, The sealing portion closes a space connecting the valve passage, the gap between the rod-shaped body, and the sub-supply passage.

10. 2. The fuel supply system of claim 1, The intake port includes a first intake port and a second intake port, the auxiliary supply passage of the first intake port and the auxiliary supply passage of the second intake port are joined together and then connected to the auxiliary combustion chamber, a fuel supply system, wherein the secondary valve is disposed downstream of a joining point of the secondary supply passages.

11. A fuel supply method for supplying fuel to a combustion chamber including a main combustion chamber and an auxiliary combustion chamber through an intake port, comprising: During the expansion stroke or the exhaust stroke of the four-cycle engine, the injector starts injecting fuel into the intake port, a fuel supply method, after the injector stops injecting fuel, operating an intake valve to allow the mixture to flow from the intake port into the main combustion chamber, and operating an auxiliary valve to allow the mixture to flow from the intake port into the auxiliary combustion chamber via an auxiliary supply passage.

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