JP2000204988A - Divided gas engine having intake fuel nozzle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a divided gas engine to inject gas fuel boosted by a fuel injection device to a subsidiary chamber and feed gas fuel to intake air through an intake fuel nozzle during high load operation and form a fuel injection device in a compact manner. SOLUTION: This divided gas engine is formed that a subsidiary chamber 2 is formed in a piston 15 reciprocated through a cylinder 14 and a fuel injection device 5 provided with a nozzle 16 and a needle valve 9 through which gas fuel is injected in the subsidiary chamber 2 is arranged in a head liner 10. An intake air fuel nozzle 33 is arranged in an intake port 65. A controller 70 controls such that gas fuel is injected from the fuel injection device 5 in the subsidiary chamber 2 during a partial load and gas fuel is injected in the subsidiary chamber 2 from the fuel injection device 5 during a high load and gas fuel is injected in intake air through the intake air fuel nozzle 33.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to natural gas, H ₂
The present invention relates to a sub-chamber type gas engine provided with an intake fuel nozzle for supplying gas fuel such as to a sub-chamber provided in a piston, igniting and burning the gas fuel, and supplying a part of the gas fuel to intake air at a high load.

[0002]

2. Description of the Related Art Conventionally, in a gas engine using natural gas or the like as fuel, natural gas is compressed to a high pressure and injected into a combustion chamber to burn natural gas in order to ensure high efficiency by diesel combustion. The method is general. However, such a gas engine requires a large amount of power to compress natural gas to a high pressure, and is consumed to compress the natural gas to a high pressure using the work obtained with high efficiency in a diesel cycle. ， Not always a satisfactory system.

Accordingly, the present inventor has developed a sub-chamber gas engine in which a sub-chamber is provided in a cylinder head, the sub-chamber is communicated with the main chamber through a communication hole, and a control valve is provided in the communication hole (Japanese Patent Laid-Open Publication No. HEI 9-163568). 6-33784). In the sub-chamber gas engine, the control valve closes the communication hole while the piston sucks air into the main chamber through the intake valve, opens the gas fuel supply valve to the sub chamber, and supplies gas fuel to the sub chamber. In the latter half of the compression stroke, the control valve opens the communication hole, allows the compressed air in the main chamber to enter the sub-chamber through the communication hole, mixes air and gaseous fuel in the sub-chamber and ignites, Next, gases such as flames and unburned air-fuel mixture in the sub-chamber are injected into the main chamber, and secondary combustion is performed in the main chamber.

Further, as a conventional sub-chamber gas engine,
Gas fuel such as natural gas is introduced into the sub-chamber, and only the intake air is compressed in the main chamber to increase the compression ratio. In addition, the in-cylinder pressure in the sub-chamber is detected by a sensor such as a piezoelectric element. Operate the fuel supply valve to control the appropriate amount of fuel supply according to the load and the number of revolutions, and open the communication hole valve of the communication hole while the air in the main room is raised to a high temperature to open the main room. It is known that compressed air is caused to flow into a sub-chamber and the gas fuel in the sub-chamber and the high-compressed air are mixed at once to ignite and burn in a short period of time (see JP-A-7-310550).

[0005]

However, in the sub-chamber gas engine, low-pressure natural gas is supplied as fuel to the sub-chamber, and the control valve opens the communication hole to supply high-pressure, high-molecular-weight air. Because it supplies from the room to the sub-room,
Natural gas and air have different specific gravities and are difficult to mix, causing unburned gas fuel to be pressed against the upper end wall of the sub-chamber and to remain, thereby deteriorating the combustion state and preventing good combustion. This causes a reduction in thermal efficiency and an increase in the generation of HC. In addition, since natural gas requires 9 to 9.5 times the amount of air for natural gas to be burned, it is necessary to burn in a state where a large amount of air exists outside natural gas. Although desirable, the conventional sub-chamber gas engine has a problem in that the gas fuel in the air is excessively dispersed and combustion does not occur continuously.

Accordingly, the present inventor has proposed that the compressed air and the gas fuel are uniformly mixed in the sub-chamber by injecting the gas fuel into a large amount of compressed air and igniting and burning the gas fuel. Without leaving the sub-chamber in the sub-chamber, the gas from the sub-chamber ignited and combusted, such as flame and unburned mixture, is spouted into the main chamber in a short period of time at the beginning of combustion.
We have developed a sub-chamber gas engine that can improve thermal efficiency and reduce the generation of HC etc.
193376).

[0007]

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems, and to provide a sub chamber in a piston,
The gas fuel compressed by the gas fuel compression means is injected into the sub-chamber by the fuel injection device to ignite and burn in the sub-chamber, and to increase the gas fuel flow rate under high load.
Gas fuel is supplied from the intake fuel nozzle to the intake passage to secure a predetermined gas fuel flow rate, and the gas fuel flow rate supplied to the sub-chamber is reduced by the flow rate of the gas fuel supplied to the intake. The volume required for compression of gaseous fuel is secured, the stroke required for gas fuel compression is secured, the amount of compression work is reduced, and the combustion temperature is increased, and at the same time, the mixture is uniformly vaporized to generate HC, NO _X , soot, etc. An object of the present invention is to provide a sub-chamber type gas engine which prevents heat and improves thermal efficiency.

According to the present invention, there is provided a combustion chamber member constituting a main chamber having an intake port in which an intake valve is disposed and which is disposed in a cylinder head, a sub-chamber communicating with the main chamber, and the sub-chamber and the main chamber. A piston that reciprocates in a cylinder having a communication hole communicating therewith, a fuel injection device including an injection hole for injecting gas fuel into the sub-chamber and a needle valve that opens and closes the injection hole, the main chamber An intake fuel nozzle for injecting the gas fuel during intake air introduced to the fuel cell, a gas fuel supply device for supplying the gas fuel to the fuel injection device, and the gas fuel from the fuel injection device into the sub-chamber at a partial load. A controller for injecting the gas fuel from the fuel injection device into the sub-chamber at the time of high load and injecting the gas fuel into the intake air from the intake fuel nozzle. For Formula gas engine.

The fuel injection device is operated by a nozzle body forming the injection hole and forming a compression chamber for accommodating the gas fuel in a hollow portion, and a driving device for compressing the gas fuel in the compression chamber. A compression spring; and a return spring for returning the compression piston to supply the gaseous fuel to the compression chamber. The needle valve reciprocates in the nozzle body to open and close the injection hole.

The tip end of the nozzle body projects from the combustion chamber member to the main chamber, enters the sub-chamber through an insertion hole formed in the piston near the top dead center of the piston, and enters the sub-chamber. The injection hole formed in the portion is opened to the sub chamber.

The compression piston has a gas fuel supply through hole in which a check valve is disposed for introducing the gas fuel supplied from the gas fuel supply device into the compression chamber, and the gas hole for opening and closing the injection hole. A hollow hole in which the needle valve slides is formed.

The nozzle body is formed of a large-diameter cylindrical portion forming the compression chamber in which the compression piston slides and a small-diameter cylindrical portion in which the needle valve slides.

The needle valve has a sliding end slidably moving within a hollow hole of the compression piston, and a valve face seated on a valve seat formed in the nozzle body to shut off the compression chamber and the injection hole. A pressure receiving surface for receiving gaseous fuel pressure in the compression chamber; and a shut-off end for slidingly moving a hollow hole formed in the small-diameter cylindrical portion of the nozzle body to open and close the injection hole.

The needle valve receives a gas fuel pressure higher than a predetermined value in the compression chamber on the pressure receiving surface of the needle valve and lifts the gas fuel against a spring force of a spring disposed in the hollow hole of the compression piston. Then, the compression chamber and the injection hole are communicated with each other. Further, an end face of the shutoff end of the needle valve constitutes a pressure receiving surface which is exposed to the sub-chamber and receives gas pressure in the sub-chamber. The needle valve lifts and the blocking end closes the orifice.

[0015] The driving device for driving the compression piston includes a cam provided on a cam shaft of a valve mechanism, a piston rod provided on the compression piston operated by the cam, and a return spring for returning the piston rod. It is composed of

The gas fuel supply device includes a fuel pump for compressing gas fuel from a gas fuel supply source, and a gas fuel valve for opening and closing a gas fuel passage for supplying gas fuel from the fuel pump to the compression chamber. It is configured.

As described above, this sub-chamber type gas engine injects all the gas fuel flow rate into the sub-chamber provided in the piston at the time of partial load, and at the time of high load such as full load or the like, the lean mixture which does not self-ignite. Part of the gaseous fuel is mixed with the intake air to ensure proper flow and good fuel efficiency. By mixing a part of the gas fuel with the intake air, it is not necessary to inject a proper amount of the gas fuel flow into the sub-chamber at a high load, so that the volume of the compression chamber for compressing the gas fuel as well as the sub-chamber is reduced. It can be made small and can secure the stroke necessary for compression of the compression piston provided in the nozzle body of the fuel injection device. Even at full load, premixed fuel that supplies gas fuel to the intake air and fuel injected to the sub chamber Is set in half, so that combustion can proceed promptly after ignition of the gaseous fuel.

Normally, natural gas has an extremely high ignition temperature at the start of combustion, for example, ignition combustion occurs at 800 ° C.
Once the fuel is burned, the combustion speed is high, so if the fuel is mixed with the intake air in advance and burned at partial load, the mixture becomes too lean and the gap between the piston and the cylinder A phenomenon occurs in which good combustion cannot be ensured due to intrusion. However, since the sub-chamber gas engine is configured as described above, the above-described undesired phenomenon does not occur.

This sub-chamber gas engine only injects gas fuel into the sub-chamber at the time of partial load, so that gas fuel, such as a flame or an unburned mixture, injected from the sub-chamber mixes with air in the main chamber. Although the fuel burns, the sub-chamber provided in the piston is a closed space, so that the fuel is uniformly mixed and is in a good mixing state. For example, for gas fuel, a gas fuel flow rate corresponding to the load is injected into the sub-chamber up to about 1/2 load,
When the load becomes higher than two loads, the remaining gas fuel flow is mixed with the intake air to become a lean premixed gas in the main chamber, and at full load, half of the gas fuel flow is injected into the sub-chamber, One half of the remaining gas fuel flow is injected into the intake.

In a normal diesel type gas engine, a predetermined amount of gas fuel is supplied from a fuel injection nozzle to a combustion chamber, so that the compressed air pressure in the combustion chamber is 40 to 50 bar.
Therefore, it is necessary to increase the pressure to a gas fuel having a higher pressure, for example, to compress the gas fuel to at least 50 to 70 bar. However, since the gas fuel of natural gas sent from the gas fuel supply source is usually about 5 bar, a large power is required to increase the gas fuel at such a pressure to a high pressure. This sub-chamber gas engine uses gas fuel compressed to about 20 to 30 bar instead of a very high pressure, and the compressed gas fuel is sealed in a compression chamber serving as a storage chamber provided in the engine, and is cammed. The gas fuel is pressurized by the pressing force of the activated compression piston,
The pressure of the gas fuel is increased to 100 to 150 bar, so that the gas fuel can be satisfactorily supplied to the sub chamber.

In the sub-chamber gas engine, when the highly compressed gas fuel is injected into the compressed air in the sub-chamber using the fuel injection device, the gas fuel can be uniformly dispersed in a large amount of air. air mixture is ignited and burned by the combustion of the auxiliary chamber can suppress the generation of NO _X, then the flame, is blown from the secondary chamber gas such as unburnt fuel-air mixture through the communication hole into the main chamber, the auxiliary chamber Gas fuel is prevented from accumulating in the main chamber, and the ejected flame and unburned gas fuel are promoted to mix with fresh air existing in the main chamber. the combustion completion, HC, to suppress the generation of NO _X, thereby improving the thermal efficiency.

[0022]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a sub-chamber gas engine according to the present invention will be described below with reference to the drawings. This sub-chamber gas engine can be applied to an engine such as a cogeneration system or an automobile engine. FIG.
1 is a sectional view showing an embodiment of the sub-chamber gas engine according to the present invention, FIG. 2 is an enlarged sectional view showing the fuel injection device of FIG.
3 is an enlarged sectional view showing the operating state of the fuel injector of FIG. 2 when it is opened, FIG. 4 is an enlarged sectional view showing the operating state of the fuel injector of FIG. 2 when it is closed, and FIG. 5 corresponds to the load. 4 is a graph showing a relationship between supply flow rates of a fuel injection device and an intake fuel nozzle.

This sub-chamber gas engine comprises a cylinder block 54, a cylinder head 3 fixed to the cylinder block 54 with a gasket 63 interposed therebetween, and a cylinder 14 fitted in a hole 23 formed in the cylinder block 54. It has a cylinder liner 22, a head liner 10 constituting a combustion chamber member arranged in a cavity 12 formed in the cylinder head 3, and a piston 15 reciprocating in a cylinder 14 formed in the cylinder liner 22. The head liner 10 includes a head lower portion 26 and a liner upper portion 27 integrally formed therewith. The main chamber 1 is formed in a region surrounded by the headliner 10 and the piston 15.

The head liner 10 is formed of a heat-resistant material such as ceramics such as Si ₃ N ₄ or a heat-resistant alloy, and is disposed in the cavity 12 of the cylinder head 3 with a heat shielding air layer 31 formed through a gasket 13. , The main chamber 1 has a heat shielding structure. In the lower part 26 of the head liner 10, an intake port 18 having a valve seat in which an intake valve 56 is arranged and an exhaust port (not shown) having a valve seat in which an exhaust valve is arranged are formed. ing. An intake port 65 and an exhaust port are formed in the cylinder head 3 so that the intake port 18 and the exhaust port formed in the headliner 10 communicate with each other.

The piston 15 includes a piston head 20 formed of a heat-resistant material such as a ceramic such as Si ₃ N ₄ or a heat-resistant alloy, and a metal such as an Al alloy fixed to the piston head 20 via a gasket 53 with a coupling ring 46. The piston skirt 36 is formed from a material. Between the piston head 20 and the piston skirt 36,
A heat shield air layer 55 is formed. Piston head 20
A sub-chamber 2 is formed in the center of. The piston head 20 has an insertion hole 7 located at the top of the center and an insertion hole 7.
A communication hole 6 is formed at the periphery of the communication hole 6. The tip 42 of the fuel injection device 5 has an insertion hole 7 near the piston top dead center.
Headliner 1 so that it can penetrate into sub-chamber 2
0 is set in a central through hole 37 formed in the head liner 10 so as to protrude from the lower portion 26 of the head to the main chamber 1. In addition, a communication hole 6 formed in the piston head 20 is formed.
Are formed at intervals around the insertion hole 7 in the circumferential direction, and extend from the center of the piston head 20 to the periphery of the cylinder. Therefore, in the fuel injection device 5, the tip end 42 projecting from the head liner 10 into the main chamber 1 enters the insertion hole 7 formed in the piston 15 near the piston top dead center, and the injection hole formed in the tip end portion 42. 16 opens into the sub-chamber 2.

The cylinder head 3 is provided with a fuel supply means comprising a gas fuel valve 11 for supplying gas fuel to the compression chamber 8 of the fuel injection device 5. The gas fuel supply device includes a fuel pump 28 for compressing gas fuel from a gas fuel supply source 39, and a gas fuel from the fuel pump 28 through a gas fuel passage 43, 52 from a gas fuel supply port 17 to a hollow space inside the nozzle body 19. It comprises a gas fuel valve 11 to be supplied to the section 35 and the compression chamber 8. Gas fuel valve 11
Are operated by the cam 32 provided on the cam shaft 68 of the valve operating mechanism to open the gas fuel supply port 17 of the gas fuel passage 52 formed in the valve main body 30, and to supply the gas fuel to the valve body 64. It comprises a valve spring 48 for returning the port 17 to the closing direction. Valve spring 48
Is disposed between the valve body 30 and the valve spring retainer 59 fixed to the end of the valve body 64. Therefore, the opening time of the gas fuel supply port 17 of the gas fuel valve 11 is adjusted by the cam 32.

The gas fuel valve 11 is mounted by arranging the valve body 30 in a mounting hole formed in the cylinder head 3. By opening the gas fuel supply port 17 of the gas fuel passage 52 formed in the valve body 30, the gas fuel valve 11 supplies gas to the hollow portion 35 formed in the nozzle body 19 of the fuel injection device 5 and the compression chamber 8. Fuel is supplied. The gas fuel passage 52 formed in the valve main body 30 communicates with the fuel pump 28 that compresses gas fuel from the gas fuel supply source 39 through the gas fuel passage 43. The fuel pump 28 is, for example, 5 bar from a gas fuel supply 39.
A rotary vane-type compressor capable of compressing about 20 to 30 bar of gas fuel can be used, and is disposed in the gas fuel passage 43.

This sub-chamber type gas engine has an intake fuel nozzle 33 for injecting a part of gas fuel through a gas fuel passage 61 at a high load on intake air introduced into the main chamber 1 through the intake ports 65 and 18, The compression piston 2 of the fuel injection device 5 which is operated to compress the gas fuel in the chamber 8
1, a driving device that presses and drives the compression piston 21, and injects gas fuel from the fuel injection device 5 to the sub-chamber 2 at a partial load, and injects the gas fuel from the fuel injection device 5 to the sub-chamber 2 at a high load. It is characterized in that it has a controller 70 for controlling the injection of gaseous fuel from the intake fuel nozzle 33 to the intake air. The engine load is detected by a load sensor 71 that detects a gas fuel supply amount and the like accompanying the operation of the fuel pump 28. A driving device for pressing and driving the compression piston 21 includes a cam 29 provided on a cam shaft 68 of a valve mechanism, and a piston rod 2 operated by the cam 29.
5, and a return spring 38 for returning the piston rod 25.

The fuel injection device 5 includes a nozzle body 19 set in the central through hole 37 of the head liner 10, a compression piston 21 reciprocally operated in a cylinder 4 formed in the nozzle body 19, a nozzle body. A compression chamber 8 formed on one side of a compression piston 21 in a compression chamber 8 for containing and compressing gas fuel, and a compression piston 2 in a nozzle body 19.
1 is provided with a hollow portion 35 formed on the back side. A needle valve 9 for opening and closing a gas fuel supply through hole 45 having a check valve 41 and a nozzle hole 16 for introducing gas fuel supplied from a gas fuel supply device into the compression chamber 8 slides on the compression piston 21. A moving hollow hole 57 is formed. The nozzle body 19 of the fuel injection device 5 is formed of a large-diameter cylindrical portion forming the compression chamber 8 in which the compression piston 21 slides and a small-diameter cylindrical portion of the distal end portion 42 protruding into the main chamber 1. ing.

The needle valve 9 has a hollow portion 35 of the compression piston 21.
The sliding end portion 60 that slides in the inside, the valve face 50 that sits on the valve seat 24 formed in the nozzle body 19 and shuts off the compression chamber 8 and the injection hole 16, and the gas fuel pressure in the compression chamber 8 is reduced. A pressure receiving surface 51 for receiving and lifting the needle valve 9, and a blocking end 34 for slidingly moving a hollow hole 62 formed in a small-diameter cylindrical portion of the nozzle body 19 to open and close the injection hole 16 are provided.
The distal end of the needle valve 9 is formed in a reduced diameter portion 67, and a large-diameter shutoff end 34 is formed at the distal end. A fuel reservoir 49 is formed between the nozzle body and the tip end portion 42. In the fuel injection device 5, when the valve face 50 of the needle valve 9 is seated on the valve seat 24 of the nozzle body 19, the communication between the sub chamber 2 and the compression chamber 8 is cut off (see FIG. 2). A spring 40 that presses the upper end surface of the needle valve 9 in the closing direction of the needle valve 9 is disposed in the hollow hole 57 of the compression piston 21. The needle valve 9 in the fuel injection device 5 responds to the gas fuel pressure in the compression chamber 8 exceeding a predetermined value, receives the gas fuel pressure on the pressure receiving surface 51 of the needle valve 9 and opposes the spring force of the spring 40. It is lifted, and the compression chamber 8 communicates with the injection hole 16 (see FIG. 3). The end surface 69 of the shutoff end 34 of the needle valve 9 is exposed in the sub-chamber 2, and forms a pressure receiving surface that receives gas pressure in the sub-chamber 2. Therefore, the fuel injector 5 lifts the needle valve 9 to the maximum amount when the gas fuel in the sub-chamber 2 rises due to the ignition of the gas fuel in the sub-chamber 2 and the shut-off end of the needle valve 9. 34 is configured to close the injection hole 16 to cut off the communication between the sub chamber 2 and the compression chamber 8 (see FIG. 4).

Since the sub-chamber gas engine is constructed as described above, it is operated as follows. This sub-chamber gas engine has, for example, a suction stroke, a compression stroke,
It is driven by repeating four cycles of an expansion stroke and an exhaust stroke. This sub-chamber type gas engine is controlled by the controller 70 in accordance with the engine load.
And the flow rate of gas fuel supplied from the intake fuel nozzle 33 is controlled. In the sub-chamber gas engine, the controller 70 receives the detection signal of the engine load from the load sensor 71, and the controller 70 changes the gas fuel flow supplied to the sub-chamber 2 and the intake air, for example, as shown in the graph of FIG. The operation of the device 5 and the intake fuel nozzle 33 is controlled.
The controller 70 injects gaseous fuel from the fuel injection device 5 into the sub-chamber 2 according to the partial load up to about 1/2 load, and in response to a high load of about 1/2 load or more. In addition, control is performed to inject gas fuel from the fuel injection device 5 into the sub-chamber 2 and to inject gas fuel from the intake fuel nozzle 33 during intake. The controller 70 is set so as to perform control of injecting a half flow rate of the total gas fuel flow rate at full load from the fuel injection device 5 into the sub-chamber 2 at high load.

This sub-chamber gas engine has a piston 15
In the intake stroke in which the air flows down in the cylinder 14, the intake valve 56 is opened and the exhaust valve closes the exhaust port, so that the intake air is supplied from the compressor of the turbocharger or the like to the main chamber 1 through the intake ports 65 and 18. Is done. At this time, the gas fuel is not supplied to the intake from the intake fuel nozzle 33 at a partial load up to the 負荷 load, and the gas fuel is supplied to the intake from the intake fuel nozzle 33 at a high load of １ ／ load or more. You. When the exhaust stroke is completed, the cam 29 pushes down the piston rod 25 against the spring force of the spring 38, and the gas fuel in the compression chamber 8 is completely injected into the sub-chamber 2 through the injection hole 16; As shown in the figure, the shut-off end 34 of the needle valve 9 closes the injection hole 16 to shut off the gas fuel passage 66 from the injection hole 16, but the compression piston 21 moves down the cylinder 4 of the nozzle body 19. Thus, the volume of the hollow portion 35 is expanding. In the suction stroke, the gas fuel valve 11 is operated by the cam 32 and the valve body 64 of the gas fuel valve 11 is lifted to lift the gas fuel supply port 17.
And the fuel pump 28 operates to compress the gas fuel (5 bar of natural gas) from the gas fuel supply source 39. Gas fuel (2) compressed by the fuel pump 28
0 to 30 bar) is supplied to the gas fuel passage 52 of the gas fuel valve 11 through the gas fuel passage 43, and is supplied to the hollow portion 35 from the opened gas fuel supply port 17.

Next, when the cam 29 rotates to release the pressing of the piston rod 25, the piston rod 25 and the compression piston 21 are raised by the action of the return spring 38. At this time, the gas fuel contained in the hollow portion 35 passes through the gas fuel through hole 45 of the compression piston 21 and pushes down the check valve 41 against the spring force of the spring 44, and the gas fuel in the hollow portion 35 Is introduced into the compression chamber 8.
In this state, as shown in FIG. 2, the needle valve 9 is pushed down by the spring 40, the valve face 50 of the needle valve 9 is seated on the valve seat 24 of the nozzle body 19, and the nozzle body 19 Is in a state where the gas fuel passage 66 and the injection hole 16 are shut off.

In the compression stroke, the piston 15 moves up in the cylinder 14, and the intake air supplied to the main chamber 1 is compressed. Near the top dead center of the compression stroke in which the piston 15 moves up the cylinder 14, the tip 42 of the fuel injection device 5 enters the insertion hole 7 of the piston 15, and the injection hole 16 of the fuel injection device 5 is inserted into the sub chamber 2. It will be located. In the latter half of the compression stroke, the cam 29 pushes down the piston rod 25, so that the compression piston 21 moves down the cylinder 4. At this time, the pressure of the gas fuel supplied to the compression chamber 8 increases as the volume of the compression chamber 8 decreases due to the lowering of the compression piston 21 because the gas fuel passage 45 is closed by the check valve 41. And, for example, 20-3
It is compressed from 0 bar to 50-70 bar.

At this time, when the gas fuel pressure in the compression chamber 8 rises, the gas fuel pressure acts on the pressure receiving surface 51 of the needle valve 9, and FIG.
As shown in FIG. 7, the needle valve 9 is lifted against the spring force of the spring 40, the valve face 50 is separated from the valve seat 24, the gas fuel passage 66 communicates with the injection hole 16, and the injection hole 16 is opened. When the injection hole 16 is opened, the gas fuel in the compression chamber 8 is jetted from the injection hole 16 into the compressed air in the sub-chamber 2, and the gas fuel in the compression chamber 8 is jetted into the sub-chamber 2 and hardly remains. At the same time, the gas fuel injected into the compressed air in the sub-chamber 2 promotes mixing with the air and ignites and burns in the sub-chamber 2.
At this time, the pressure in the sub-chamber 2 rises, and the gas pressure in the sub-chamber 2 acts on the end face 69 of the distal end portion 34 of the needle valve 9, and as shown in FIG. Since the injection hole 16 is closed,
Gases such as flames and unburned mixture in the sub-chamber 2 are prevented from flowing back from the sub-chamber 2 to the compression chamber 8 through the injection hole 16, the fuel reservoir 49, and the gas fuel passage 66. flame, gas such as unburned mixture gas is blown into the main chamber 1 through the communication hole 6, the diffusion combustion and to promote combustion rate and promote mixing with the fresh air existing in the main combustion chamber 1, NO _X The combustion is completed in a state in which the generation of HC is suppressed, and the piston 15 works.

In the expansion stroke, the piston 15 descends, and when the piston 15 descends and the gas in the sub-chamber 2 blows out to the main chamber 1, the gas pressure in the sub-chamber 2 decreases and the needle valve 9 The valve face 50 of the needle valve 9 is seated on the valve seat 24 by the spring 40, the communication between the compression chamber 8 and the injection hole 16 is cut off, and the injection hole 16 is closed. Next, the piston 15 reaches the bottom dead center and shifts to the exhaust stroke. An exhaust valve opens an exhaust port, exhaust gas is exhausted from an exhaust pipe through the exhaust port, and exhaust heat energy of the exhaust gas is, for example, a turbocharger, an energy recovery turbine, a heat exchanger, or the like incorporated in the exhaust pipe. Collected.

[0037]

The sub-chamber gas engine according to the present invention has the following features.
With the above configuration, the gas fuel, which has been pressurized to some extent by the fuel pump, is introduced into the compression chamber of the fuel injection device, and the gas fuel is compressed to a desired high pressure, for example, 50 to 70 bar, by the compression piston operated by the cam mechanism. In some cases, the pressure can be easily increased to 100 bar to 150 bar, and the high-pressure gas fuel can be injected into the compressed air in the sub chamber from the injection hole of the fuel injection device. Also,
At high load, a part of gas fuel is supplied to the intake,
There is no need to design the volume of the compression chamber provided in the fuel injection device so large, the fuel injection device can be made compact, the appropriate gas fuel flow rate can always be supplied according to the load, and the primary combustion in the sub-chamber of course, to promote secondary combustion and reduce the combustion period, can complete the combustion, NO _X, and reduce the occurrence of HC and the like, thereby improving the thermal efficiency.

[Brief description of the drawings]

FIG. 1 is a sectional view showing an embodiment of a sub-chamber gas engine according to the present invention.

FIG. 2 is an enlarged sectional view showing a fuel injection device in the sub-chamber gas engine of FIG.

FIG. 3 is an enlarged sectional view showing an operating state of the fuel injection device of FIG. 2 when it is opened.

FIG. 4 is an enlarged sectional view showing an operation state of the fuel injection device of FIG. 2 when the fuel injection device is closed.

FIG. 5 is a graph showing a relationship between supply flow rates corresponding to loads on a fuel injection device and an intake fuel nozzle.

[Description of Signs] 1 Main chamber 2 Sub chamber 3 Cylinder head 5 Fuel injection device 6 Communication hole 7 Insertion hole 8 Compression chamber 9 Needle valve 10 Head liner (combustion chamber member) 11 Fuel valve 14 Cylinder 15 Piston 16 Injection hole 17 Gas Fuel supply port 18 Intake port 19 Nozzle body 21 Compression piston 24 Valve seat 25 Piston rod 28 Fuel pump 29 Cam 33 Intake fuel nozzle 34 Blocking end 35 Hollow part 38 Return spring 39 Gas fuel supply source 40, 44 Spring 41 Non-return Valve 42 Tip 43,52 Gas fuel passage 45 Gas fuel passage 48 Valve spring 50 Valve face 51 Pressure receiving surface 56 Intake valve 57 Hollow hole 60 Sliding end 62 Hollow hole 65 Intake port 68 Camshaft 70 Controller 71 Load sensor

Claims (10)

[Claims] A combustion chamber member that is disposed in a cylinder head and has an intake port in which an intake valve is disposed, the combustion chamber member constituting a main chamber, a sub-chamber communicating with the main chamber, and a sub-chamber and the main chamber. A fuel injection device having a piston reciprocating in a cylinder having a communicating hole formed therein, an injection hole for injecting gas fuel into the sub-chamber, and a needle valve for opening and closing the injection hole, introduced into the main chamber; An intake fuel nozzle for injecting the gas fuel during the intake air to be supplied, a gas fuel supply device for supplying the gas fuel to the fuel injection device, and injecting the gas fuel from the fuel injection device into the sub-chamber at a partial load. A controller for injecting the gas fuel from the fuel injection device into the sub-chamber at the time of a high load and controlling the injection of the gas fuel into the intake air from the intake fuel nozzle. gin. 2. The fuel injection device is operated by a nozzle body forming the injection hole and forming a compression chamber for accommodating the gas fuel in a hollow portion, and a driving device for compressing the gas fuel in the compression chamber. And a return spring for returning the compression piston to supply the gaseous fuel to the compression chamber. The needle valve reciprocates in the nozzle body to open and close the injection hole. The sub-chamber gas engine according to claim 1, wherein 3. A tip end portion of the nozzle body protrudes from the combustion chamber member to the main chamber, enters the sub chamber through an insertion hole formed in the piston near a top dead center of the piston, 3. The sub-chamber gas engine according to claim 2, wherein the injection hole formed at the tip end is opened to the sub-chamber. 4. A gas fuel supply through hole provided with a check valve for introducing the gas fuel supplied from the gas fuel supply device into the compression chamber, and the injection hole is opened and closed in the compression piston. 3. The sub-chamber gas engine according to claim 2, further comprising a hollow hole through which the needle valve slides. 5. The nozzle body is formed of a large-diameter cylindrical portion forming the compression chamber in which the compression piston slides and a small-diameter cylindrical portion in which the needle valve slides. 3. The sub-chamber gas engine according to 2. 6. The needle valve is seated on a sliding end slidably moving in a hollow hole of the compression piston and a valve seat formed in the nozzle body to shut off the compression chamber from the injection hole. A valve face, a pressure receiving surface for receiving gas fuel pressure in the compression chamber, and a shutoff end for slidingly moving a hollow hole formed in the small-diameter cylindrical portion of the nozzle body to open and close the injection hole. The sub-chamber gas engine according to claim 5, comprising: 7. The needle valve receives a gas fuel pressure greater than a predetermined value in the compression chamber on the pressure receiving surface of the needle valve, and resists a spring force of a spring disposed in the hollow hole of the compression piston. 7. The sub-chamber type gas engine according to claim 6, further comprising a lifter for communicating the compression chamber with the injection hole. 8. An end face of the shutoff end of the needle valve constitutes a pressure receiving surface which is exposed to the sub-chamber and receives gas pressure in the sub-chamber. 7. The sub-chamber gas engine according to claim 6, wherein the needle valve is correspondingly lifted and the shutoff end closes the injection hole. 9. The driving device for driving the compression piston returns a cam provided on a cam shaft of a valve operating mechanism, a piston rod provided on the compression piston operated by the cam, and the piston rod. 3. The sub-chamber gas engine according to claim 2, comprising a return spring. 10. A gas fuel supply device comprising: a fuel pump for compressing gas fuel from a gas fuel supply source; and a gas fuel passage for opening and closing a gas fuel passage for supplying gas fuel from the fuel pump to the compression chamber. 3. The sub-chamber gas engine according to claim 2, comprising a valve.