JP4709277B2 - Gas fuel internal combustion engine - Google Patents

Description

  The present invention relates to a crankcase compression type two-stroke (two-cycle) gas fuel internal combustion engine.

  2. Description of the Related Art A crank chamber compression type two-cycle internal combustion engine may include a fuel injection valve that directly supplies fuel into a cylinder from the viewpoint of suppressing fuel blow-through and improving fuel efficiency. This fuel injection valve generally injects high-pressure gasoline fuel from an injection nozzle (see, for example, Patent Document 1).

On the other hand, in the two-cycle internal combustion engine, gas fuel may be used in order to reduce the fuel cost. In this case, it is conceivable that gas fuel is injected and supplied into the cylinder by the fuel injection valve.
JP-A-10-252479

  By the way, when adopting a structure in which gas fuel is injected and supplied from the injection nozzle of the conventional fuel injection valve, there is a concern that the required amount of gas fuel cannot be supplied in a short time due to its structure. Filling efficiency may decrease, and fuel consumption and exhaust gas properties may deteriorate.

  Therefore, the applicant of the present application is considering opening and closing the downstream end opening of the fuel supply passage communicating with the combustion chamber with a poppet valve type fuel supply valve in order to increase the charging efficiency of the gas fuel. In this case, the valve shaft of the fuel supply valve is slidably guided by the valve guide member. However, a slight amount is required between the valve guide member and the valve shaft in order to allow the valve shaft to slide without hindrance. A gap is provided. On the other hand, since the gas pressure in the fuel supply passage is considerably high, the gas fuel leaks outside the combustion chamber through this gap, resulting in a decrease in fuel consumption and unburned gas being discharged. There is.

  The present invention has been made in view of the above circumstances, and can improve the gas fuel charging efficiency, and can reduce the fuel consumption due to the leaked fuel and prevent unburned gas from being discharged. The object is to provide an internal combustion engine.

The invention of claim 1 is a crank chamber compression type two-stroke gas fuel internal combustion engine having an exhaust port that opens to a cylinder bore, and a plurality of scavenging ports that communicate the crank chamber and the cylinder bore .
A fuel supply passage formed such that its downstream end opening is located in the combustion chamber, a poppet valve type fuel supply valve having a valve shaft formed on an umbrella-shaped valve plate that opens and closes the downstream end opening, and A valve guide member that slidably guides the valve shaft of the fuel supply valve, and gas fuel that has entered the gap between the valve guide member and the valve shaft is positioned on the opposite side of the exhaust port across the cylinder axis. A leak fuel introduction passage for introducing into the scavenging port is provided.

According to a second aspect of the present invention, in the first aspect, the leak fuel introduction passage is communicated with the valve guide member in a radial direction so as to communicate with the gap between the valve shaft and the communication passage. An annular groove formed in the outer peripheral portion of the valve guide member, a lead-out passage for leading the annular groove to the outside, and a leak fuel passage communicating the lead-out passage and the scavenging port. It is characterized by.

According to a third aspect of the present invention, in the first aspect, the check valve for preventing the flow from the scavenging port side to the leaking fuel introduction passage side is disposed in the vicinity of the scavenging port of the leakage fuel introduction passage. It is a feature.

According to a fourth aspect of the present invention, in any one of the first to third aspects, the leakage fuel inlet formed in the scavenging port is directed to a portion near the cylinder side opening of the inner wall surface of the scavenging port or to the combustion chamber. It is characterized by being formed.

According to a fifth aspect of the present invention, in any one of the first to fourth aspects, the leak fuel that has entered the valve chamber is provided with a substantially hermetic valve chamber in which a camshaft for opening and closing the fuel supply valve is housed. Is provided with a valve chamber side leak fuel introduction passage through which oil is introduced into the scavenging port via an oil separator.

  According to the first aspect of the present invention, the downstream end opening of the fuel supply passage communicating with the combustion chamber is opened and closed by a so-called poppet valve type fuel supply valve having a valve shaft formed on an umbrella-shaped valve plate. Even when the diameter of the fuel supply passage and its downstream end opening is increased, the fuel supply passage and the downstream end opening can be opened and closed without any problem. As a result, a required amount of gas fuel can be supplied to the combustion chamber in a short period of time. Thereby, charging efficiency can be improved and fuel consumption and exhaust gas properties can be improved.

  Further, in the present invention, when the poppet valve type fuel supply valve is employed, the scavenging port allows the gas fuel that has entered the gap between the valve guide member that slidably guides the valve shaft of the fuel supply valve and the valve shaft to be scavenged. Therefore, the leaked gas fuel can be recovered and burned effectively, and the reduction of heat costs and the discharge of unburned gas can be prevented.

  As described above, in the present invention, since the leak fuel can be reliably collected, it is not necessary to strictly seal the gap between the shaft valve and the valve guide member, and it is possible to introduce the lubricating oil into the gap, and as a result, the valve The lubricity of the sliding surface between the shaft and the valve guide member can be improved.

Further, since the leak fuel is introduced into the scavenging port located on the side opposite to the exhaust port, the leak fuel is introduced into the scavenging port located far from the exhaust port. Therefore, it is possible to prevent the leaked fuel from being discharged from the exhaust port together with fresh air during the scavenging stroke before the exhaust port is closed.

In the invention of claim 2 , the leak fuel introduction passage is formed in the valve guide portion so as to communicate with the gap between the valve shaft and the outer periphery of the valve guide member so as to communicate with the communication passage. Since it has an annular groove, a lead-out passage that leads the annular groove to the outside, and a leak fuel passage that communicates the lead-out passage and the scavenging port, the leak fuel that has entered the gap is reliably recovered. Can be burned.

In the invention of claim 3 , since the check valve is disposed in the vicinity of the scavenging port of the leak fuel introduction passage, it is possible to prevent the scavenging flow from being inhibited by the leak fuel flowing into the scavenging port at a high speed. That is, before the scavenging port is opened, the fresh air in the scavenging port is pressurized, so the leaked fuel in the leaked fuel introduction passage is also pressurized with the same pressure. When the scavenging port is opened in this state, leak fuel having a high pressure and flow velocity is ejected into the scavenging port, and the scavenging flow is inhibited. In the present invention, since the check valve is arranged in the vicinity of the scavenging port of the leak fuel introduction passage, the leak fuel is introduced into the scavenging port only during a period when the crank chamber is negative during the compression stroke, and the introduction of the leak fuel is prevented during the scavenging stroke. Therefore, the scavenging flow is normally performed.

In the invention of claim 4 , since the leak fuel introduction port is formed so as to be directed to the portion near the cylinder side opening of the inner wall surface of the scavenging port or to the combustion chamber, the leak fuel flows out from the exhaust port as unburned gas. Can be prevented. That is, there is a high probability that leak fuel will be mixed into fresh air from the scavenging port on the side close to the exhaust port, and there is a risk that leak fuel will flow out of the exhaust port. On the other hand, in the present invention, the leak fuel is caused to flow toward the cylinder side opening near the cylinder side opening or the combustion chamber on the inner wall surface of the scavenging port. It can be put on the flow, or can be kept on the fuel chamber side, so that leakage fuel can be prevented from flowing out from the exhaust port.

According to the fifth aspect of the present invention, since the leaked fuel that has entered the valve chamber is introduced into the scavenging port via the oil separator, the leaked fuel that has entered the valve chamber can also be recovered, and further fuel consumption and exhaust gas can be recovered. The property can be improved.

1 is a cross-sectional view of a crankcase compression type two-cycle gas fuel internal combustion engine according to an embodiment of the present invention. It is sectional drawing (II-II sectional view taken on the line of FIG. 1) of the cylinder head of the said gas fuel internal combustion engine. It is a top view of the cylinder bore part of the said cylinder head. It is a block diagram of the gas fuel supply apparatus of the said gas fuel internal combustion engine. It is a block diagram of the leak fuel introduction channel | path of the said gas fuel supply apparatus. It is a principal part expanded sectional view of the said leak fuel introduction channel | path. It is a principal part expanded sectional top view of the said leak fuel introduction channel | path. It is an expanded sectional top view which shows the modification of the said leak fuel introduction channel | path.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Gas fuel internal combustion engine 2 Crank chamber 3c Exhaust port 3d 'Scavenging port 3f Leak fuel introduction port 3g Cylinder side opening 4c Fuel supply passage 4d Downstream end opening 18 Combustion chamber 20 Fuel supply valve 20a Valve shaft 20b Valve plate 25 Valve guide member 27 Valve chamber 31 Cam shaft 60 Leak fuel introduction passage 61a Communication passage 61b Annular groove 61c Derivation passage 62 Leak fuel passage 64 Check valve 65 Oil separator 66 Valve chamber side leak fuel introduction passage d Clearance

  Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

  FIGS. 1 to 7 are views for explaining a gas fueled internal combustion engine having a two-stroke clan chamber compression type according to an embodiment of the present invention. FIG. 1 is a sectional view of the gas fueled internal combustion engine, and FIG. FIG. 3 is a plan view of a cylinder bore portion of the cylinder head, FIG. 4 is a configuration diagram of a gas fuel supply device, and FIG. 5 is a leak fuel introduction passage. FIG. 6 and FIG. 7 are enlarged sectional views of the main part of the leak fuel introduction passage.

  In the figure, reference numeral 1 denotes a crank chamber compression type two-stroke gas fuel internal combustion engine. This gas fuel internal combustion engine 1 has the following schematic structure. A cylinder block 3 is bolted to the upper joint surface 2 b of the upper and lower split crankcase 2, and a cylinder head 4 is bolted to the upper joint surface 3 a of the cylinder block 3. A crankshaft 5 is disposed in the crank chamber 2 a of the crankcase 2 and a piston 6 is disposed in a cylinder bore 3 b of the cylinder block 3. The piston 6 is connected to the crankpin 5 a of the crankshaft 5 by a connecting rod 7. It is connected.

  The crankcase 2 is formed with an intake passage 2c communicating with the crank chamber 2a. A throttle body 12 incorporating a throttle valve 11 is connected to the intake passage 2c through a backflow prevention reed valve 10. An air cleaner 13 is connected to the upstream side of the throttle body 12.

  A nozzle type fuel injection valve 14 is attached to the throttle body 12. The injection port 14 a of the fuel injection valve 14 is disposed so as to inject fuel from the downstream side of the throttle valve 11 toward the valve back of the reed valve 10. A fuel rail 15 for supplying gasoline fuel is connected to the fuel injection valve 14. The fuel injection valve 14 is used to inject and supply gasoline as an auxiliary to main gas fuel described later. The fuel injection valve 14 is not necessarily provided.

  An exhaust port 3c is formed on the side of the cylinder block 3 opposite to the intake passage 2c. The cylinder block 3 is formed with a plurality of scavenging ports 3d for introducing the air or air-fuel mixture compressed in the crank chamber 2a into the cylinder bore 3b. As shown in FIG. 3, the cylinder side opening of each scavenging port 3d is arranged so as to form a loop at a portion of the cylinder bore 3b opposite to the exhaust port 3c.

  A combustion recess 4a is formed in the lower mating surface portion of the cylinder head 4 facing the cylinder bore 3b. The cylinder head 4 is formed with a water jacket 4b so as to surround the outer periphery of the combustion recess 4a, and a cooling water discharge hose 19 is connected to the water jacket 4b.

  The gas fuel internal combustion engine 1 includes a gas fuel supply device that supplies gas fuel to the combustion recess 4a. As shown in FIG. 4, the gas fuel supply apparatus has a fuel tank 41 and an upstream end connected to a discharge port 41a of the fuel tank 41, and a downstream end connected to a fuel supply passage 4c of a cylinder head 4 described later. Gas fuel supply pipe 40.

  A manual valve 42, a fuel filter 43, a pressure sensor 44, a shut-off valve 45, a pressure regulator 46, a flow control valve 47, and a check valve 48 are provided in the gas fuel supply pipe 40 in order from the upstream side. . A shutoff valve 49 and a fuel pressure sensor 50 are connected to the discharge port 41 a of the fuel tank 41, and a fuel supply port 52 is connected via a check valve 51.

  Detection signals from the pressure sensors 44 and 50 are input to the ECU 53, and the ECU 53 is configured to control the shut-off valves 45 and 49 and the flow rate control valve 47 based on these detection signals. The shut-off valves 45 and 49 are configured to close when the main switch is turned off, when the vehicle falls over, or the like.

  Here, as the flow rate control valve 47, a proportional control type valve for controlling the opening area or an injector type valve for controlling the valve opening time can be adopted. When the injector type valve is employed, the check valve 48 is not necessary because the injector valve itself has a check valve function.

  Further, the flow control valve 47 is not limited to the one interposed in the middle of the gas fuel supply pipe 40, and may be configured to be directly attached to the cylinder head 4, for example, so as to supply the gas fuel to the pressure accumulating chamber 4f.

  The combustion recess 4a is formed in a dome shape (hemispherical shape), and a substantially hemispherical combustion chamber 18 is formed by the combustion recess 4a and the top surface 6a of the piston 6 in the vicinity of the top dead center.

  A squish surface 4 i is formed on the outer periphery of the combustion recess 4 a of the cylinder head 4. The squish surface 4i has a cut angle (for example, about 10 to 20 degrees) so that a narrow gap is formed with the top surface 6a of the piston 6 when the piston 6 is raised near the top dead center. ing. As a result, the gas fuel in the vicinity of the inner peripheral wall of the cylinder bore 3 b in the compression stroke is pushed out toward the center of the combustion chamber 10.

  A downstream end opening 4d of the fuel supply passage 4c is located at the upper center of the combustion recess 4a of the cylinder head 4, and a fuel supply valve 20 for opening and closing the opening 4d is disposed in the downstream end opening 4d. ing.

  The fuel supply passage 4c extends from the upstream end opening 4e formed in the end face on the side opposite to the exhaust port 3c of the cylinder head 4 in a direction intersecting the cylinder axis a, and then extends along the cylinder axis a to the combustion chamber 18 side. Is bent.

  The fuel supply pipe 40 is connected to the upstream end opening 4e with a check valve 48 interposed therebetween. The check valve 48 prevents the gas fuel from flowing backward from the combustion supply passage 4c toward the fuel tank 41, and is connected to the upstream end opening 4e of the fuel supply passage 4c.

  A pressure accumulating chamber 4f is formed in the vicinity of the upstream side of the fuel supply valve 20 in the fuel supply passage 4c, specifically, following the downstream end opening 4d. The pressure accumulating chamber 4f has substantially the same opening area as the downstream end opening 4d, and has a length that reaches slightly above the fuel supply passage 4c from the opening 4d, thereby securing the required fuel amount at the maximum load. It has a capacity that can.

  The fuel supply valve 20 is a so-called poppet formed by forming an umbrella-shaped valve plate 20b in contact with the peripheral edge of the downstream end opening 4d at the lower end of the valve shaft 20a disposed so as to substantially coincide with the cylinder axis a. It is a valve type.

  The valve shaft 20a protrudes upward from the upper surface of the cylinder head 4 through the pressure accumulating chamber 4f, and is slidably guided by a cylindrical valve guide member 25 press-fitted into the cylinder head 4. . A retainer 21 is mounted on the upper end of the valve shaft 20a. The fuel supply valve 20 is normally biased in the closing direction between the retainer 21 and a spring seat 4g formed on the upper surface of the cylinder head 4. A valve spring 22 is disposed.

  The upper end portion of the valve guide member 25 protrudes upward from the spring seat 4g, and the lower end portion protrudes into the pressure accumulating chamber 4f. A seal member 23 for sealing between the valve shaft 20a and the valve shaft 20a is attached to the upper end portion of the valve guide member 25. A slight gap d (see FIGS. 5 to 7) is provided between the valve guide member 25 and the valve shaft 20a for sliding the valve shaft 20a without hindrance.

  On the upper surface of the cylinder head 4, a valve-operating chamber 27 is formed by a box-shaped partition wall 4 h extending upward so as to surround the periphery of the upper end portion of the fuel supply valve 20, and a lid plate 26 disposed at the upper end opening of the partition wall 4 h. Is formed. Lubricating oil for lubricating a sliding portion, a bearing portion and the like of the cam shaft 31 described later is supplied into the valve chamber 27.

  A valve operating device 28 that opens and closes the fuel supply valve 20 is disposed in the valve operating chamber 27. One end of the valve operating device 28 abuts on the upper end of the valve shaft 20a, the other end abuts on the rocker arm 30 supported by the support shaft 29 in a vertically swinging manner, the upper surface of the rocker arm 30, and Both end portions are provided with cam shafts 31 supported by the partition walls 4h via bearings (not shown).

  The cam shaft 31 is disposed in parallel with the crankshaft 5, and a timing belt 33 is connected to a protruding portion 31 a protruding outward from the partition wall 4 h of the cam shaft 31 via a pulley 32. The camshaft 31 is rotationally driven by the crankshaft 5 via the timing belt 33, and the rocker arm 30 swings up and down as the camshaft 31 rotates to open and close the fuel supply valve 20.

  The valve operating device 28 has a variable valve operating mechanism that variably controls the opening / closing timing and the lift amount of the fuel supply valve 20. As shown in FIG. 2, the variable valve mechanism is disposed on the cam shaft 31 so as to be movable in the axial direction, and has a low cam nose 31b and a high cam nose 31c having different cam profiles in sliding contact with the rocker arm 30, and a throttle opening. A switching mechanism 54 that switches to the low cam nose 31b during low / medium load operation and switches to the high cam nose 31c during high load operation by a switching signal from the ECU 53 based on the engine speed and the engine speed. Specifically, during the low / medium load operation, the fuel supply valve 20 starts to open when the exhaust port 3c is within the open period in the compression stroke. Further, during high load operation, the fuel supply valve 20 is configured to open over the entire period from 1/2 of the open period when the exhaust port 3c is within the closed period in the compression stroke.

  A pair of spark plugs 35 are mounted on the cylinder head 4. Each of the spark plugs 35, 35, when viewed in the direction perpendicular to the crankshaft, is approximately on both sides in the crankshaft direction across the valve shaft center line (cylinder axis) a of the fuel supply valve 20 and with respect to the valve shaft centerline a. It is arranged to be inclined to form an angle of about 35 degrees. Thereby, the spark plug 35 is directed to the center of the above-mentioned hemispherical shape.

  As shown in FIG. 3, each of the spark plugs 35 is located on a straight line c extending in a direction perpendicular to the extension line b passing through the center of the exhaust port 3c from the cylinder axis a as viewed in the cylinder axis a direction. Are arranged as follows. Each of the spark plugs 35 is disposed such that the electrodes 35 a and 35 a are positioned in the vicinity of the valve plate 20 b of the fuel supply valve 20 in the combustion chamber 18.

  The gas fuel supply device is configured to introduce a part of the high-pressure gas fuel in the pressure accumulating chamber 4f that has entered the gap d between the valve guide member 25 and the valve shaft 20a of the fuel supply valve 20 into the scavenging port 3d. 60. The leak fuel introduction passage 60 has the following structure.

  As shown mainly in FIGS. 5 to 7, the leak fuel introduction passage 60 is formed in the periphery of the valve guide member 25 of the cylinder head 4, and the leak fuel that has entered the gap d is led out of the cylinder head 4. A leak fuel passage 61 for introducing the leaked fuel into the scavenging port 3d.

  The scavenging port 3d on the side opposite to the exhaust port 3c of the cylinder block 3, that is, the scavenging port 3d 'located on the opposite side of the exhaust port 3c across the cylinder axis a is formed with a leak fuel inlet 3f. The leak fuel introduction port 3f is formed obliquely downward so as to be directed to a portion S1 in the vicinity of the cylinder side opening 3g of the inner wall surface S of the scavenging port 3d ′.

  The leak fuel lead-out passage 61 is formed in the valve guide member 25 so as to extend in the radial direction, and communicates with a pair of communication passages 61a and 61a communicating with the gap d between the valve shaft 20a and each communication passage 61a. An annular groove 61b formed between the outer peripheral surface of the valve guide member 25 and the valve guide member press-fitting surface of the cylinder head 4, and a lead formed in the cylinder head 4 for leading the annular groove 61b to the outside. The outlet 61d of the outlet passage 61c is located on the opposite side of the cylinder head 4 from the fuel supply passage 4c. The upstream end of the leak fuel passage 62 is connected to the outlet 61d.

  A check valve 64 for blocking the flow of leaked fuel from the scavenging port 3d side to the leaked fuel passage 62 side is provided near the upstream side of the leaked fuel introduction port 3f of the leaky fuel passage 62. The check valve 64 may be provided in the leak fuel introduction port 3f.

  An oil separator 65 that separates oil mist in the valve operating chamber 27 is disposed on the lid plate 26 that forms the valve operating chamber 27. The oil separator 65 is connected to a valve chamber side leak fuel introduction passage 66 for introducing the leaked fuel that has entered the valve chamber 27 into the scavenging port 3d '. The fuel introduction passage 66 is connected in communication with the leak fuel passage 62.

  Although most of the leaked fuel that has entered the gap d between the valve guide member 25 and the valve shaft 20a is collected by the leak fuel outlet passage 61, a part of the leaked fuel passes through the gap of the seal member 23 and enters the valve chamber 27. May enter. The leaked fuel that has entered the valve operating chamber 27 is collected in the scavenging port 3d ′ via the leak fuel passage 62 after the mixed oil mist is separated.

  Part of the high-pressure gas fuel supplied to the pressure accumulating chamber 4f enters the gap d between the valve guide member 25 and the valve shaft 20a of the fuel supply valve 20, and becomes leaked fuel. Most of this leak fuel flows into the annular groove 61b through the communication passage 61a, passes through the lead-out passage 61c from the annular groove 61b, and is further introduced into the scavenging port 3d 'through the leak fuel passage 62. The Specifically, in the ascending stroke of the piston 6, the reed valve 10 is opened and air is sucked into the crank chamber 2a, and the check valve 64 is opened to introduce leaked fuel into the scavenging port 3d '. This leaked fuel is introduced toward the cylinder side opening 3g vicinity S1 of the scavenging port inner wall surface S, and does not flow into the crank chamber 2a side, but remains in the vicinity of the cylinder side opening 3g of the port wall.

  In the downward stroke of the piston 6, combustion gas is discharged from the exhaust port 3c, and air in the crank chamber 2a flows into the cylinder bore 3b from each scavenging port 3d, and accordingly, leaked fuel in the scavenging port 3d '. Also flows into the cylinder bore 3b.

  According to the present embodiment, a poppet valve type fuel in which the downstream end opening 4d of the fuel supply passage 4c located at the upper center of the dome type combustion chamber 18 is formed with the valve shaft 20a on the umbrella-shaped valve plate 20b. Since the supply valve 20 opens and closes, the required amount of gas fuel can be supplied into the combustion chamber 18 in a short period from the relatively large diameter downstream end opening 4d. Thereby, the charging efficiency is improved, and fuel consumption and exhaust gas properties can be improved.

  In this embodiment, when the poppet valve type fuel supply valve 20 is employed, the gap d between the valve shaft 20a of the fuel supply valve 20 and the valve guide member 25 that guides and supports the valve shaft 20a is slidable. Since the gas fuel that has entered is recovered by the leak fuel introduction passage 60 and introduced into the scavenging port 3d ′, the leak fuel can be burned effectively, and the reduction of heat costs and the discharge of unburned gas can be prevented.

  In the present embodiment, since leak fuel is introduced into the scavenging port 3d 'located on the opposite side of the exhaust port 3c across the cylinder axis a, the leak fuel is introduced into the scavenging port 3d' located farthest from the exhaust port 3c. Thus, during the scavenging stroke before the exhaust port 3c is closed, leaked fuel can be prevented from being mixed with fresh air and discharged from the exhaust port 3c as unburned gas.

  In the present embodiment, the leak fuel introduction passage 60 is formed in the valve guide portion 25 so as to extend in the radial direction, and communicates with the communication passages 61a and 61a that communicate with the gap d with the valve shaft 20a, and the communication passages 61a. An annular groove 61b formed between the outer peripheral surface of the valve guide member 25 and the valve guide member press-fitting surface of the cylinder head 4, a lead-out passage 61c for leading the annular groove 61b to the outside, and the lead-out passage 61c and the scavenging air Since the leak fuel passage 62 that communicates with the port 3d 'is provided, most of the leak fuel that has entered the gap d can be recovered.

  Further, since the leak fuel can be reliably collected, it is not necessary to strictly seal the gap d between the shaft valve 20a and the valve guide member 25, and it is possible to introduce the lubricating oil into the gap d. As a result, the lubricity of the sliding surface between the valve shaft 20a and the valve guide member 25 can be improved.

  In the present embodiment, since the check valve 64 is disposed in the vicinity of the upstream side of the scavenging port 3d ′ of the leak fuel passage 62, the flow of the scavenging is inhibited by the leak fuel flowing into the scavenging port 3d ′ at a high speed. Can be prevented. That is, since the fresh air in the scavenging port 3d is pressurized before the scavenging port 3d is opened, the leaked fuel in the leak fuel passage 62 is also pressurized with the same pressure. When the scavenging port 3d opens in this state, leak fuel having a high pressure is ejected into the scavenging port 3d ', and the scavenging flow is inhibited. In the present embodiment, since the check valve 64 is disposed in the vicinity of the scavenging port 3d ′ of the leak fuel passage 62, the leak fuel passes from the leak fuel passage 62 to the scavenging port 3d ′ only during a period in which the crank chamber 2a is negative during the compression stroke. Since the fuel is ejected at a high speed and the introduction of leaked fuel is prevented during the scavenging stroke, the scavenging flow is normally performed.

  In the present embodiment, the leak fuel introduction port 3f is formed so as to be directed to the portion S1 in the vicinity of the cylinder side opening 3g of the inner wall surface S of the scavenging port 3d ', so that the leak fuel flows away from the exhaust port 3c as unburned gas. Can be prevented. That is, when the leaked fuel flows into the crank chamber 2a, there is a high probability that the leaked fuel will be mixed into fresh air from the scavenging port 3d on the side close to the exhaust port 3c. is there. On the other hand, in the present embodiment, the leaked fuel is jetted toward the port inner wall surface portion S1 in the vicinity of the cylinder side opening 3g, so that it can be directly introduced into the cylinder bore 3b without passing through the crank chamber 2a. The above loss can be avoided. Further, the deflection of the scavenging airflow toward the exhaust port can be suppressed, and the leaked fuel can be put on the free scavenging flow. In the present invention, the leak fuel introduction port 3f may be formed obliquely upward so as to be directed to the combustion chamber. In this case, the same effect as described above can be obtained.

  In this embodiment, the valve chamber side leak fuel introduction passage 66 is connected to the valve train chamber 27 in which the camshaft 31 that drives the fuel supply valve 20 to open and close is accommodated via the oil separator 65, and the introduction passage 66 leaks. Since the fuel is connected to the scavenging port 3d ′ via the fuel passage 62, the leaked fuel that has entered the valve operating chamber 27 can be introduced into the scavenging port 3d ′ after separating the oil mist from the fuel chamber 62, and the leaked fuel can be more reliably supplied. Can be recovered.

  In the above-described embodiment, the case where there is one fuel supply valve 20 has been described. However, the present invention can also be applied to a case where a plurality of fuel supply valves 20 are provided.

  For example, as shown in FIG. 8, when two fuel supply valves 20, 20 arranged in parallel are provided, the gap between the valve shaft 20 a of each fuel supply valve 20, 20 and the valve guide member 25. What is necessary is just to comprise so that the leak fuel of d may be made to merge with the leak fuel passage 62 via the leak fuel outlet passages 61 and 61, and may be guide | induced to the scavenging port 3d '.

Claims (5)

A crank chamber compression type two-stroke gas fuel internal combustion engine having an exhaust port opened to a cylinder bore and a plurality of scavenging ports communicating with the crank chamber and the cylinder bore ,
A fuel supply passage formed such that its downstream end opening is located in the combustion chamber;
A poppet valve type fuel supply valve having a valve shaft formed on an umbrella-shaped valve plate that opens and closes the downstream end opening;
A valve guide member that slidably guides the valve shaft of the fuel supply valve;
A leak fuel introduction passage is provided for introducing gas fuel that has entered the gap between the valve guide member and the valve shaft into a scavenging port located on the opposite side of the exhaust port across the cylinder axis. Gas fuel internal combustion engine. 2. The leak fuel introduction passage according to claim 1, wherein the leak fuel introduction passage includes a communication passage formed in a radial direction so as to communicate with the valve guide member in a gap with the valve shaft, and a valve guide member configured to communicate with the communication passage. A gas fuel internal combustion engine comprising: an annular groove formed in an outer peripheral portion; a lead-out passage for leading the annular groove to the outside; and a leak fuel passage communicating the lead-out passage and the scavenging port. 2. The gas fuel internal combustion engine according to claim 1, wherein a check valve for preventing a flow from the scavenging port side to the leak fuel introducing passage side is disposed in a portion near the scavenging port of the leak fuel introducing passage. . In any one of claims 1 to 3, the formed scavenging ports were leak fuel inlet port, characterized in that it is formed so as to direct to the cylinder side opening portion near or above the combustion chamber of the inner wall of the scavenging port Gas fuel internal combustion engine. In any one of claims 1 to 4, comprising a substantially sealed shaped valve operating chamber in which the cam shaft is accommodated for opening and closing the fuel supply valve, the leak fuel that has entered the indoor animal valve via an oil separator above A gas fuel engine comprising a valve chamber side leak fuel introduction passage for introduction into a scavenging port.

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