JP2000205049A - Indirect injection gas engine with fuel cooler - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the durability of fuel injectors by cooling fuel gas to be supplied to auxiliary chambers with fuel coolers and holding its pressure always constant despite of variations in its flow rate so that a proper fuel-gas flow rate is fed to compression chambers. SOLUTION: The indirect injection gas engine has an auxiliary chamber 2 formed in a piston 15, and a compression chamber 8 formed in a combustion chamber member 10 placed in a cylinder head 3. A fuel injector 5 has nozzle holes 16 adapted to open into the auxiliary chamber 2 in the piston 15 brought near the top dead center. Fuel gas compressed by a fuel pump 28 is cooled by a fuel cooler 47, regulated in temperature depending on variations in its flow rate and kept at a prescribed pressure before fed into the compression chamber 8, wherein it is boosted up by a compression piston 21 before injected into the auxiliary chamber 2 via the nozzle holes 16.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sub-chamber gas engine provided with a fuel cooling device for supplying gas fuel from a gas fuel supply device for compressing and cooling gas fuel to a sub-chamber provided on a piston for igniting and burning. About.

[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.

In a conventional sub-chamber type 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 and to reduce the in-cylinder pressure in the sub-chamber. A state in which the air in the main room is raised to a high temperature by detecting a sensor with a piezoelectric element or the like and operating the fuel supply valve based on the information to control the appropriate amount of fuel supply according to the load and the number of revolutions. It is known that the communication hole valve of the communication hole is opened to allow the highly compressed air in the main chamber to flow into the sub chamber, and the gas fuel and the high compressed air in the sub chamber are mixed at once to ignite and burn in a short 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 remain in the sub-chamber, causing the combustion state to deteriorate, making it impossible to perform good combustion and lowering thermal efficiency. This causes the generation of HC to increase. In order for natural gas to burn, the amount of natural gas must be one.
Therefore, it is desirable to burn in a state where a large amount of air exists outside the natural gas. However, in the conventional sub-chamber gas engine, the air amount is required to be increased to 9 to 9.5 times. There is a problem that the gas fuel is excessively dispersed and the 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,
Gas fuel is injected into the sub-chamber by the fuel injection device and ignites and burns in the sub-chamber. At this time, the pressure of the compressed gas fuel is kept constant according to the change in the gas fuel supply amount according to the load of the engine. Therefore, the compression piston is operated properly even when the gas fuel flow rate changes according to the load by cooling the compressed fuel at a high pressure during the partial load and cooling the compressed fuel when the full load fuel is large. the pressure of the gas fuel supplied to the auxiliary chamber and held at a predetermined value, HC, NO _X, provides a sub-chamber type gas engine with and prevent the occurrence of soot such as a fuel cooling system for improving the thermal efficiency i.e. fuel consumption That is.

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 needle valve that opens and closes an injection hole for injecting gas fuel into the sub-chamber, and contains the gas fuel injected into the sub-chamber. A fuel injection device having a compression chamber that performs compression, and a gas fuel supply device that supplies the gas fuel to the compression chamber to the fuel injection device. A fuel pump for compressing fuel, a fuel cooling device provided downstream of the fuel pump and cooling the compressed gas fuel to reduce the gas fuel pressure, and a gas cooling device provided downstream of the fuel cooling device and provided About pre-combustion chamber gas engine consists configured from a gas fuel valve is actuated to be supplied to the compression chamber.

The fuel cooling device includes a heat transfer member for forming a heat transfer passage for transferring heat from the gas fuel compressed by the fuel pump, and a heat transfer member disposed outside the heat transfer member. It comprises an outer heat radiating member forming a heat radiating passage for absorbing and radiating heat, and a cooling pump for feeding a cooling fluid into the heat radiating passage.

The controller for controlling the flow rate of gas fuel supplied to the sub-chamber reduces the operating state of the cooling pump to reduce the heat radiation from the heat radiation passage of the fuel cooling device at the time of partial load, and increases the load of the fuel pump. In some cases, control is performed to increase the operation state of the cooling pump in order to increase the heat radiation from the heat radiation passage, and to control the gas fuel flow rate while maintaining a predetermined gas fuel pressure according to the engine load.

An intake fuel nozzle for injecting the gaseous fuel during the intake air introduced into the main chamber is provided, and the controller injects the gaseous fuel from the fuel injection device into the sub-chamber at a partial load, At the time of load, control is performed to inject the gas fuel into the sub-chamber from the fuel injection device and to inject the gas fuel into the intake air from the intake fuel nozzle.

The fuel injection device includes a nozzle body in which the injection hole and the compression chamber are formed, a compression piston operated by a driving device to compress the gas fuel in the compression chamber, and the gas in the compression chamber. A return spring for returning the compression piston to supply fuel is provided, and the needle valve disposed in the compression piston via a spring reciprocates in the nozzle body to open and close the injection hole.

The compression piston has a gas fuel 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 needle for opening and closing the injection hole. A hollow hole through which the valve slides is formed.

[0014] 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 of a predetermined value or more 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.

The end surface of the shutoff end of the needle valve constitutes a pressure receiving surface exposed to the sub-chamber and receiving the gas pressure in the sub-chamber, and in accordance with a predetermined gas pressure in the sub-chamber. The needle valve lifts and the blocking end closes the orifice.

In this sub-chamber type gas engine, as described above, the fuel cooling device is provided in the gas fuel supply device, so that the gas fuel is supplied in accordance with the gas fuel flow rate supplied to the sub-chamber, which varies according to the engine load. While cooling and maintaining a constant gas fuel pressure, the gas fuel is supplied to the compression chamber of the fuel injection device, whereby the compression piston which pressurizes the gas fuel in the compression chamber is always properly operated, and is operated in the sub chamber. To improve the fuel efficiency by preventing the generation of HC, NO _X , soot and the like. That is, the gas fuel supplied to the sub chamber is determined by the volume of the compression chamber and the stroke of the compression piston in the fuel injection device. By cooling the gas fuel supplied to the sub chamber, the pressure of the gas fuel is reduced. As a result, a predetermined gas fuel flow rate can be secured, the gas fuel can be constantly controlled to a predetermined pressure, and the durability of the cam, the compression piston and the like can be guaranteed.

In the case of a piston type, a large stroke is required to compress gas fuel. Therefore, in order to compress the gaseous fuel in one step to a high pressure, for example, 10 MPa,
The compression ratio must be 27 or higher. In order to make the gas fuel compression ratio 27 or more, the stroke of the piston becomes extremely large. Therefore, for example, if the gas fuel pressure is increased to about 0.7 Mpa by the fuel pump of the first-stage gas fuel supply device and pressurized by the compression piston of the fuel injection device, the compression ratio becomes about 7 to 10 Mpa. Can be pressurized. This gas fuel pressure condition is a condition when the engine is operated at full load. However, if the gas fuel temperature is high, the volume of the compression chamber in the fuel injection device must be increased. To do so, it is necessary to lower the temperature of the gas fuel supplied from the fuel pump with a fuel cooling device. On the other hand, at the time of partial load, since the gas fuel flow rate is small, if the gas fuel is excessively cooled by the fuel cooling device, the gas fuel pressure becomes small, and the gas fuel cannot be injected into the sub chamber. In such a case, the operating state of the fuel cooling device is reduced by reducing the amount of air blown from the cooling pump to reduce the cooling effect, maintaining the gas fuel pressure at a predetermined high pressure, and controlling the gas fuel injected from the compression chamber into the sub-chamber. Maintain pressure. In the case of a temporary change state, ie, a transient, the rotation of the fuel pump is adjusted to control the pressure and the gas fuel flow rate.

This sub-chamber type gas engine injects all the gas fuel flow rate into the sub-chamber provided at the piston at a partial load, and a part of the gas fuel which does not self-ignite under a high load such as a full load. Is mixed with the intake air to ensure an appropriate flow rate 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 piston A phenomenon occurs in which good combustion cannot be ensured due to penetration into a gap or the like. However, since the sub-chamber gas engine is configured as described above, the above-described undesired phenomenon does not occur.

In this sub-chamber type gas engine, only gas fuel is injected into the sub-chamber at the time of partial load, so that gas fuel such as flame and 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 gas fuel, for example, up to about 1/2 load, a gas fuel flow rate according to the load is injected into the sub-chamber, and
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.

A normal diesel type gas engine supplies a predetermined amount of gas fuel 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 type gas engine uses gas fuel compressed by a fuel pump to about 20 to 30 bar, fills the compressed gas fuel into a compression chamber provided in the engine, and pushes a compression piston operated by a cam. The gas fuel is pressurized by the pressure, and the pressure of the gas fuel is increased by 10
The gas fuel can be satisfactorily supplied to the sub-chamber.

In this sub-chamber gas engine, when 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, the mixture of the emitted flame and the unburned gas fuel with fresh air existing in the main chamber is promoted, the secondary combustion speed in the main chamber is increased, and the the combustion completion in, HC, to suppress the generation of NO _X, thereby improving the thermal efficiency.

[0024]

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 is a fuel corresponding to the load. A graph showing the relationship between the supply flow rate of the injector and the intake fuel nozzle,
6 is an enlarged sectional view showing the gas fuel supply device of FIG.

This sub-chamber type gas engine comprises a cylinder block 54, a cylinder head 3 fixed to the cylinder block 54 via a gasket 63, 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 headliner 10 is formed of a heat-resistant material such as a ceramic 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 ceramics 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 by a coupling ring 46 via a gasket 53. 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.

This sub-chamber type gas engine is particularly characterized by a gas fuel supply device that supplies gas fuel to the compression chamber 8 of the fuel injection device 5. The gas fuel supply device is provided with a fuel pump 28 that compresses gas fuel supplied from a gas fuel supply source 39 through a gas fuel passage 79, and is provided downstream of the fuel pump 28 and supplies the gas fuel from the fuel pump 28 to the gas fuel passage 43. Cooling device 47 fed through
And a gas fuel valve 11 provided downstream of the fuel cooling device 47 and operated to supply gas fuel to the compression chamber 8. The fuel cooling device 47 is constituted by a heat exchanger and has a function of cooling the gas fuel compressed by the fuel pump 28 to reduce the gas fuel pressure. Gas fuel valve 1
1 opens and closes the gas fuel supply port 17 in order to supply the gas fuel adjusted to an appropriate gas fuel pressure by the fuel cooling device 47 to the hollow portion 35 in the nozzle body 19 and the compression chamber 8.

Further, the fuel cooling device 47 includes the fuel pump 2
Heat transfer passage 75 for transferring heat from the gaseous fuel compressed at 8
, A heat dissipating member 78 disposed outside of the heat transfer member 76 and forming a heat dissipating passage 77 for absorbing and dissipating the heat of the heat transferring member 76, and supplying a cooling fluid to the heat dissipating passage 77 through the fluid passage 74. It is composed of a cooling pump 73 for feeding in. The fuel cooling device 47 is configured such that water or air is used as a refrigerant, and the refrigerant flows through the fluid passage 74 to remove heat from the heat radiation member 78. The heat transfer member 76 is accommodated in a case 86 made of a heat transfer material through which a fluid cannot pass. The heat transfer member 76 is formed of a porous member or a honeycomb structure made of a metal or ceramic capable of passing the gas fuel and receiving the heat of the gas fuel. The heat radiating member 78 is accommodated in a case 85 made of a heat transfer material through which a fluid cannot pass. The heat radiation member 78
It is formed of a porous member or a honeycomb structure made of metal or ceramic capable of receiving the heat of the heat transfer member 76 through the passage of the refrigerant fluid. Therefore, the heat transfer member 76 and the heat dissipation member 7
8, the heat transfer becomes extremely good, the heat from the gaseous fuel is properly absorbed, and the gaseous fuel can be adjusted to an appropriate gaseous fuel pressure.

The gas fuel valve 11 opens the gas fuel supply port 17 of the gas fuel passage 52 formed in the valve body 30 so that the hollow portion 35 formed in the nozzle body 19 of the fuel injection device 5 and the compression chamber are opened. 8 is supplied with gaseous fuel. The gas fuel passage 52 formed in the valve body 30 communicates with the fuel cooling device 47 through the gas fuel passage 43. The fuel pump 28 is, for example, 5b from the gas fuel supply source 39.
Ar gaseous fuel can be compressed to about 20 to 30 bar. The fuel pump 28 is formed as a rotary vane type or reciprocating piston type compressor. For example, as shown in FIG. 6, a rotary vane type compressor has a rotating shaft 81 eccentrically arranged in a pump casing 80 and a plurality of radial grooves formed on the rotating shaft 81, each of which is outwardly directed by a spring 87. Vanes 8 placed in a pressed state
2 and a plurality of pump chambers 83 partitioned by vanes 82.

The controller 70 receives the signal of the engine load from the load sensor 71, and controls the driving of the motor 71 and the driving of the cooling pump 73. Motor 7
2 drives the fuel pump 28 to operate, and gas fuel is sucked into the fuel pump 28 from the gas fuel supply source 39 through the gas fuel passage 79. The gas fuel sucked into the pump chamber 83 of the fuel pump 28 is compressed, and the compressed gas fuel is sent to the fuel cooling device 47 through the gas fuel passage 43. In the fuel cooling device 47, the gaseous fuel passes through a heat transfer passage 75 formed of a heat transfer member 76 having a porous structure to transfer the heat of the gaseous fuel to the heat transfer member 76. The gas is sent to the gas fuel valve 11 through the gas fuel passage 43. On the other hand, when the cooling pump 73 is driven, the air (water) of the refrigerant is sent through the fluid passage 74 into the heat dissipation passage 77 formed by the porous heat dissipation member 78 of the fuel cooling device 47, and the air (water) is discharged. ) Indicates the heat radiation member 78
And is discharged from the outlet passage 84 to the outside.
Therefore, the gas fuel which has been heated by compression is cooled by air (water), and the gas fuel pressure supplied to the compression chamber 8 is reduced, and the pressure is controlled to an appropriate pressure.

The sub-chamber gas engine also includes an intake fuel nozzle 33 for injecting a part of gas fuel through a gas fuel passage 61 at a high load to 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 sensor 71 that detects a gas fuel supply amount and the like.
The driving device for pressing and driving the compression piston 21 includes a cam 29 provided on a cam shaft 68 of a valve operating mechanism, a piston rod 25 operated by the cam 29, and a return spring 38 for returning the piston rod 25.

The gas fuel valve 11 is mounted by arranging the valve body 30 in a mounting hole formed in the cylinder head 3. The gas fuel valve 11 is operated by a cam 32 provided on a cam shaft 68 of a valve operating mechanism to open a gas fuel supply port 17 of a gas fuel passage 52 formed in the valve main body 30, and a valve body 64. Of the gas fuel supply port 17 is closed. The valve spring 48 includes a valve spring retainer 59 fixed to the ends of the valve body 30 and the valve body 64.
And is located between. Therefore, the gas fuel valve 11 is
The opening time of the gas fuel supply port 17 is adjusted by the cam 32.

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 through hole 45 provided with 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 hollow hole 57 is formed. Further, a compression piston 21 is provided on the nozzle body 19 of the fuel injection device 5.
Are formed from a large-diameter cylindrical portion forming the compression chamber 8 in which the sliding movement is performed, and a small-diameter cylindrical portion of the distal end portion 42 protruding into the main chamber 1.

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 distal end of the needle valve 9 is formed with a blocking end portion 34 having a large diameter portion. The fuel pool 49 between the nozzle body and the tip 42
Are formed. 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). End face 6 of shutoff end 34 of needle valve 9
Reference numeral 9 denotes a pressure receiving surface that is exposed in the sub-chamber 2 and receives the gas pressure in the sub-chamber 2. Therefore, the fuel injection device 5
When the gas fuel in the sub-chamber 2 is ignited and burned in the sub-chamber 2 and the gas pressure in the sub-chamber 2 rises, the needle valve 9 is lifted to the maximum amount, and the shut-off end 34 of the needle valve 9 closes the injection hole 16. It is configured to close and cut off communication between the sub chamber 2 and the compression chamber 8 (FIG. 4).
reference).

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.
When controlling the flow rate of gas fuel supplied from the intake fuel nozzle 33 and controlling the flow rate of gas fuel supplied to the sub-chamber 2, the heat radiation from the radiation passage 77 of the fuel cooling device 47 during partial load is reduced. In order to increase the heat radiation from the heat radiating passage 77 at a high load, the operating condition of the cooling pump 73 is strengthened in order to increase the heat radiation from the heat radiation passage 77 so that the gas fuel pressure is adjusted to a predetermined gas fuel pressure according to the engine load. It is characterized in that the control for changing the gas fuel flow rate is performed while maintaining it.

This sub-chamber type gas engine has a load sensor 7
In response to the detection signal of the engine load from the controller 1, the controller 70 determines the flow rate of the gas fuel supplied to the sub-chamber 2 and the intake air, for example, the operation of the fuel injection device 5 and the intake fuel nozzle 33 as shown in the graph of FIG. Control. Controller 70
Is the fuel injection device 5 depending on the partial load up to 1/2 load.
Gas fuel is injected into the sub-chamber 2 from the
In addition, the fuel injection device 5 according to a high load of 1/2 load or more.
Control is performed to inject gas fuel 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 actuated by the action of the return spring 38.
And rise. At this time, the gas fuel contained in the hollow portion 35 passes through the gas fuel through hole 42 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 FIGS. 1 and 2, the needle valve 9 is pushed down by the spring 40, and the valve face 50 of the needle valve 9 is seated on the valve seat 24 of the nozzle body 19. The 19 gas fuel passage 66 and the injection hole 16 are in a state of being shut off.

In the compression stroke, the piston 15 rises 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 shut-off end 34 of the needle valve 9, as shown in FIG. Since the end 34 closes the injection hole 16, gases such as flames and unburned mixture in the sub-chamber 2
Backflow from the gas through the injection hole 16, the fuel reservoir 49, and the gas fuel passage 66 to the compression chamber 8, and the gas such as the flame and the unburned mixture in the sub-chamber 2 passes through the communication hole 6. is sprayed into the chamber 1, the diffusion combustion and to promote combustion rate and promote mixing with the fresh air existing in the main combustion chamber 1, NO _X, combustion while suppressing generation of HC completed, work piston 15 do.

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.

[0043]

The sub-chamber gas engine according to the present invention has the following features.
With the above configuration, even if the flow rate of gas fuel supplied by the engine load changes, a predetermined gas fuel pressure can be maintained by controlling the temperature of the gas fuel by the fuel cooling device, and the predetermined gas fuel pressure can be maintained. since the pressurized in the compression chamber in pressure results in the gaseous fuel is always correct injection gas fuel pressure to the secondary chamber, NO _X, and reduce the occurrence of HC and the like, thereby improving the thermal efficiency. That is, gas fuel, which has been pressurized to some extent by a fuel pump, is introduced into a compression chamber of a fuel injection device, and the gas fuel is supplied to a desired high pressure, for example, 50 to 70 bar, for example, 100 to 150 bar by a compression piston operated by a cam mechanism. The pressure can be easily increased by this time, 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,
When the load is high, the gas fuel supplied to the sub-chamber is pressurized by the fuel pump, and then the compressed gas fuel is cooled by the fuel cooling device. Therefore, the pressure of the gas fuel decreases. It can be injected into the sub chamber by fuel pressure. In addition, since a part of the gas fuel is supplied to the intake, the volume of the compression chamber provided in the fuel injection device does not need to be designed so large that the fuel injection device can be made compact, gas fuel flow can be supplied to the sub chamber in the primary combustion, of course, to promote secondary combustion and reduce the combustion period, you can complete combustion, reducing NO _X, the generation of HC and the like,
Thermal efficiency can be improved.

[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.

FIG. 6 is an enlarged sectional view showing the gas fuel supply device of FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Main chamber 2 Sub chamber 3 Cylinder head 5 Fuel injection device 6 Communication hole 8 Compression chamber 9 Needle valve 10 Headliner (combustion chamber member) 11 Fuel valve 14 Cylinder 15 Piston 16 Injection hole 18, 65 Intake port 19 Nozzle body 21 Compression Piston 24 Valve seat 28 Fuel pump 33 Intake fuel nozzle 34 Shutoff end 38 Return spring 39 Gas fuel supply source 40 Spring 41 Check valve 43, 52, 61, 66 Gas fuel passage 45 Gas fuel passage 47 Fuel cooling device ( Heat exchanger) 50 Valve face 51 Pressure receiving surface 56 Intake valve 57 Hollow hole 60 Sliding end 62 Hollow hole 69 End surface of shutoff end 70 Controller 73 Cooling pump 74 Fluid passage 75 Heat transfer passage 76 Heat transfer member 77 Radiation passage 78 Heat dissipation member

Claims (9)

[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 piston that reciprocates in a cylinder having a communicating hole formed therein, a needle valve that opens and closes an injection hole for injecting gas fuel into the sub-chamber, and a compression that stores the gas fuel injected into the sub-chamber A fuel injection device having a chamber, and a gas fuel supply device for supplying the gas fuel to the compression chamber to the fuel injection device, wherein the gas fuel supply device supplies the gas fuel from a gas fuel supply source. A fuel pump for compression; a fuel cooling device provided downstream of the fuel pump for cooling the compressed gas fuel to reduce the gas fuel pressure; and a fuel cooling device provided downstream of the fuel cooling device for compressing the gas fuel. A sub-chamber gas engine comprising a gas fuel valve operated to supply the chamber. 2. The fuel cooling device according to claim 1, further comprising: a heat transfer member that forms a heat transfer passage for transferring heat from the gas fuel compressed by the fuel pump; 2. The sub-chamber gas engine according to claim 1, further comprising a heat radiating member for forming a heat radiating passage for absorbing and radiating heat of the member, and a cooling pump for feeding a cooling fluid to the heat radiating passage. 3. A controller for controlling a flow rate of gaseous fuel supplied to the sub-chamber weakens an operation state of the cooling pump to reduce heat radiation from the heat radiation passage of the fuel cooling device at a partial load. At high load, control is performed to increase the operation state of the cooling pump in order to increase heat radiation from the heat radiation passage, and control is performed to change the gas fuel flow rate while maintaining a predetermined gas fuel pressure according to the engine load. The sub-chamber type gas engine according to claim 2, comprising: 4. An intake fuel nozzle for injecting the gas fuel during intake air introduced into the main chamber, and the controller injects the gas fuel from the fuel injection device into the sub chamber at a partial load. 4. A sub-chamber system according to claim 3, wherein at the time of a high load, control is performed to inject said gas fuel from said fuel injection device into said sub-chamber and to inject said gas fuel into said sub-chamber from said intake fuel nozzle. Gas engine. 5. A fuel injection device comprising: a nozzle body having the injection hole and the compression chamber formed therein; a compression piston operated by a driving device for compressing the gas fuel in the compression chamber; A return spring for returning the compression piston to supply the gaseous fuel, wherein the needle valve disposed in the compression piston via a spring reciprocates in the nozzle body to open and close the injection hole; The sub-chamber type gas engine according to claim 1, comprising: 6. The compression piston opens and closes a gas fuel through hole in which a check valve is arranged for introducing the gas fuel supplied from the gas fuel supply device into the compression chamber, and the injection hole. 6. The sub-chamber gas engine according to claim 5, wherein a hollow hole through which the needle valve slides is formed. 7. The compression valve according to claim 7, wherein the needle valve is seated on a sliding end that slides 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: 8. The needle valve receives a gas fuel pressure greater than or equal to 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. 8. The sub-chamber gas engine according to claim 7, further comprising a lift for communicating the compression chamber with the injection hole. 9. 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.