JPH09158729A - Indirect injection gas engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the unburnt gas from being left in a sub-chamber by scavenging the sub-chamber with the sucked air, and feeding a part of the gas fuel in a main chamber in an indirect injection gas engine. SOLUTION: In an indirect injection gas engine, a sub-chamber opening/ closing valve 5 is arranged on a communication port 6 to communicate a main chamber 1 with a sub-chamber 2, a gas fuel feed valve 5 to feed the gas fuel to the sub-chamber 2 is provided, a bypass passage 7 to communicate an intake port 9 with the sub-chamber 2 is provided, and a bypass valve 8 is arranged on the bypass passage 7. The opening/closing timing of the bypass valve 8 is controlled in response to the engine load by a controller 20, the sub-chamber 2 is scavenged by introducing the sucked air from an intake port 9 into the sub-chamber 2 through the bypass passage 7 during the medium to high load operating condition, and a part of the gas fuel is fed from the sub-chamber 2 to the main chamber 1 through the bypass passage 7 and the intake port 9.

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 having an intake bypass passage, which has a sub chamber in a cylinder head and a main chamber on the cylinder side.

[0002]

2. Description of the Related Art Heretofore, as a gas engine, there has been considered a method in which a sub-chamber is provided in a cylinder head, the sub-chamber is made rich in fuel, ignitability is ensured in a lean region, and combustion is stabilized. However, the gas engine uses natural gas, that is, natural gas as fuel, and the fuel is gas. Therefore, when gas is sucked in the suction stroke and then compressed, the air-fuel mixture is highly compressed and its temperature rises, causing a phenomenon of self-ignition, that is, knocking. That is,
The gas fuel of natural gas will self-ignite unless the compression ratio is about 11-13. Regarding the thermal efficiency of the engine, there is a phenomenon that the thermal efficiency decreases when the compression ratio is small.

Therefore, in the sub-chamber gas engine, in order to further stabilize the lean combustion, a sub-chamber opening / closing valve is installed in a communication hole that communicates the sub-chamber with the main chamber, and the sub-chamber opening / closing valve is provided during the intake stroke. Keep it closed and inhale only air into the main chamber and introduce natural gas into the sub chamber. Then, the sub-chamber opening / closing valve is opened just before the top dead center of the compression stroke, and air is instantaneously introduced into the sub-chamber due to the pressure difference between the main chamber and the sub-chamber, and natural gas and air are rapidly mixed and ignited and burned. Then, the lean burn is completed in a short time while flowing from the sub chamber to the main chamber through the communication hole.

[0004]

By the way, the applicant of the present invention has developed a gas engine that solves the above-mentioned problems, and has previously filed as Japanese Patent Application No. 6-124678. The gas engine introduces a gas fuel such as natural gas into the sub chamber,
In addition to increasing the compression ratio by compressing only the intake air in the main chamber,
The cylinder pressure in the sub chamber is detected by a sensor such as a piezoelectric element, and based on this information, the fuel supply valve is operated to control the proper fuel supply amount that matches the load and the number of revolutions, and the air in the main chamber is controlled. Ignite in a short period of time by opening the communication hole valve of the communication hole while raising the temperature to high temperature to allow the highly compressed air in the main chamber to flow into the sub chamber and mixing the gas fuel and highly compressed air in the sub chamber all at once. To burn. Moreover, since the auxiliary combustion chamber fuel is rich state is combusted suppressing state generation of NO _X, flame short as much as possible uniform mixture of secondary combustion by causing sprayed once in the main chamber from the auxiliary chamber It is completed in a short time to reduce the generation of NO _x , HC, etc., particularly to improve the thermal efficiency, prevent self-ignition of gas fuel, and prevent knocking.

By the way, in the sub-chamber gas engine, when the sub-chamber opening / closing valve is opened, air flows from the main chamber to the sub-chamber, is rapidly mixed with gas fuel, and is self-ignited to start combustion. ing. In order to perform active combustion with a high air utilization rate in the main chamber, ignition occurs in the region farthest from the main chamber of the sub chamber, combustion progresses, and an unburned mixture or flame is ejected from the sub chamber to the main chamber. Is considered ideal.

However, in the conventional sub-chamber gas engine, the combustion state greatly changes depending on the equivalence ratio (the amount of air existing in the sub-chamber) in the sub-chamber before opening the sub-chamber opening / closing valve, so that the engine load changes. There is a problem that the change of combustion is large. In addition, since the air flowing from the main chamber to the sub chamber is mixed in the entire sub chamber by opening the communication port of the sub chamber opening / closing valve, the ignition position in the sub chamber is not specified, and Since the ignition in the sub chamber occurs while the air is flowing in, the pressure in the sub chamber rises,
The amount of air introduced into the sub chamber is limited. Therefore, there is a problem that combustion cannot be performed in the sub chamber until the pressure rises enough to eject the gas fuel in the sub chamber into the main chamber. If the gas fuel in the sub-chamber does not burn sufficiently and the pressure does not rise sufficiently, unburned gas stays in the sub-chamber for a long period of time, which deteriorates the efficiency in the high load region.

[0007]

SUMMARY OF THE INVENTION An object of the present invention is to solve the above problems, and a sub-chamber provided in a cylinder head and an intake port are connected by a bypass passage, and a bypass valve provided in the bypass passage. Control the opening and closing timing in response to the engine load, and scavenge the subchamber with intake air to prevent residual gas from staying in the subchamber for a long time.
To provide a sub-chamber gas engine with an intake bypass passage, which can stabilize combustion by sending a portion of gas fuel that is diluted to such an extent that it does not ignite spontaneously from the sub-chamber to the main chamber through the bypass passage and the intake port. Is.

According to the present invention, an intake / exhaust port formed in the cylinder head, an intake / exhaust valve for opening / closing the intake / exhaust port, and a sub-chamber arranged in the cylinder head and substantially in the center of the cylinder are formed. A sub-chamber structure, a communication port formed in the sub-chamber structure for communicating the sub-chamber with the main chamber on the cylinder side, a sub-chamber opening / closing valve for opening and closing the communication port, and a gas fuel for the sub-chamber Gas fuel supply valve for opening and closing a gas fuel supply port provided in the sub chamber for supplying to the sub chamber, a bypass passage for connecting the sub chamber and the intake port, a bypass valve for opening and closing the bypass passage, and a response to an engine load And a controller for controlling the opening / closing timing of the bypass valve, and a sub-chamber gas engine with an intake bypass passage.

The sub-chamber opening / closing valve opens the communication port from the vicinity of the end of the compression stroke during the period in which the gas fuel supply valve closes the gas fuel supply port to the sub chamber by opening the communication port. It communicates with the main chamber. The gas fuel supply valve supplies the gas fuel to the sub chamber by opening the gas fuel supply port from a suction stroke to a compression stroke while the sub chamber opening / closing valve closes the communication port. Is.

In addition, the controller closes the bypass passage in response to the low load operation of the bypass valve, and responds to the medium load operation in the latter half of the exhaust stroke from the gas fuel supply port by the gas fuel supply valve. The bypass passage is opened until the latter half of the intake stroke at the start of opening, and in response to the high load operation, the bypass passage is controlled from near the latter half of the exhaust stroke to near the end of the intake stroke.

Further, while the controller operates the bypass valve in response to the medium load operation to open the bypass passage, intake air is supplied to the sub chamber through the bypass passage. The sub chamber is scavenged.

Further, in response to the high load operation, the controller supplies intake air to the sub chamber through the bypass passage during the period in which the bypass valve is operated to open the bypass passage. Part of the gas fuel into the main chamber through the intake port due to the pressure difference between the suction pressure and the supply pressure of the gas fuel in the sub chamber with the communication port closed. To supply. Therefore, the gas fuel having the same flow rate as that during the medium load operation is supplied to the sub chamber, and the ignition combustion in the sub chamber has an appropriate equivalence ratio, and the gas fuel is discharged in the lower portion of the sub chamber. It is possible to stably ignite and burn in the sub chamber without causing an excessive concentration and causing an ignition error.

The bypass valve is driven by electromagnetic force, and the valve timing of the bypass valve is controlled by a command from the controller. Therefore,
The bypass valve can optimally control valve timing in response to engine load.

Since this sub-chamber gas engine is constructed as described above, a sub-chamber opening / closing valve is provided at the communication port that connects the main chamber and the sub-chamber to the bypass passage in response to the engine load. The opening / closing timing of the bypass valve can be controlled, the compression ratio can be set without being restricted by the startability, knocking does not easily occur even if the compression ratio is increased to 17-18, and the thermal efficiency can be improved. It is possible to introduce intake air into the sub-chamber through the passage to scavenge the sub-chamber, prevent unburned gas from staying in the sub-chamber for a long period of time, and prevent the wall of the sub-chamber from becoming abnormally hot. It is possible to stabilize the medium load operation and the high load operation.

Further, in this sub-chamber type gas engine, at the time of high load operation, the bypass valve is operated to open the bypass passage to bypass a part of the gas fuel which becomes a lean air-fuel mixture from the sub-chamber so as not to ignite spontaneously. It can be supplied to the main chamber through the passage and the intake port, the equivalence ratio in the sub chamber can be controlled to be constant, and combustion can be stabilized. In addition, the primary chamber is ignited and burned in a rich air-fuel mixture state in the sub-chamber rapidly to suppress the generation of NO _X , and then the main chamber is generated by the jet energy of the combustion gas jetted from the communication port to the main chamber. With, it is possible to improve the air utilization rate by involving fresh air and rapidly perform secondary combustion, shorten the combustion period and improve the thermal efficiency.

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of a sub-chamber gas engine according to the present invention will be described below with reference to the drawings. 1 is a schematic cross-sectional view showing an embodiment of a sub-chamber gas engine according to the present invention, FIG. 2 is a diagram showing the valve timing of each valve in the sub-chamber gas engine of FIG. 1, and FIG. 4 is an explanatory view showing the valve timing during low load operation of the room type gas engine, FIG. 4 is an explanatory view showing valve timing during the medium load operation of the auxiliary chamber type gas engine of FIG. 1, and FIG. 5 is an auxiliary chamber of FIG. It is explanatory drawing which shows the valve timing at the time of high load operation of a gas engine.

This sub-chamber gas engine is driven by a diesel cycle using a gas fuel such as natural gas as a fuel. For example, a cylinder head 13 fixed to a cylinder block 24 has an intake port 9 and an exhaust port. 17
The intake valve 11 is disposed in the intake port 9, and the exhaust valve 12 is disposed in the exhaust port 17. This sub-chamber gas engine includes, for example, a cylinder head 13 fixed to a cylinder block 24 via a gasket 30, a combustion chamber structure constituting the main chamber 1 arranged in a cavity 29 formed in the cylinder head 13, a cylinder head. It has a sub chamber structure 3 forming a sub chamber 2 arranged in a cavity 16 formed in 13, and a piston 15 reciprocating in a cylinder 14 formed by a cylinder liner 23. The combustion chamber structure includes a head liner 10 in which a head lower surface portion 31 and a liner upper portion 32 are integrated. An intake port 26 connected to the intake port 9 and an exhaust port 27 connected to the exhaust port 17 are formed in the head lower surface portion 31. Between the headliner 10 and the cylinder head 13, the main chamber 1 has a heat shield structure by the gasket 19 and the heat shield air layer 28.

In this sub-chamber type gas engine, the sub-chamber structure 3 is arranged in the cavity 16 formed in the cylinder head 13 so as to form the sub-chamber 2 substantially at the center of the cylinder shaft. The lower end of the sub-chamber structure 3 protruding from the lower surface of the cylinder head is arranged in a fitting hole 33 formed substantially in the center of the head lower surface portion 31 of the head liner 10 forming the main chamber 1. A sub-chamber opening / closing valve 4 for opening / closing the communication port 6 is arranged at the communication port 6 formed in the headliner 10. Further, in this sub-chamber gas engine, the headliner 10 forming the main chamber 1 and the sub-chamber structure 3 forming the sub-chamber 2 are, for example, silicon nitride excellent in heat resistance,
It is made of ceramics such as silicon carbide and sialon. Further, since the sub-chamber structure 3 and the headliner 10 become hot, the sub-chamber opening / closing valve 4 arranged in the communication port 6 is made of a heat-resistant metal having high temperature strength and excellent in heat resistance, ceramics such as silicon nitride and silicon carbide. It is manufactured.

The gas fuel from the gas fuel supply source 50 is supplied from the gas fuel passage 25 formed in the cylinder head 13 when the valve body 51 of the gas fuel supply valve 5 opens the gas fuel supply port 22. It is supplied to the sub chamber 2 through the mouth 22. A fuel supply source 50 containing natural gas as a fuel, that is, a gas fuel, is provided at an appropriate place, and the gas fuel from the fuel supply source 50 is sent to the gas fuel passage 25 through a fuel supply pipe 52. Gas fuel supply source 5
Gas fuel of 0 is, for example, 5 to 7 kg in the booster chamber.
The pressure is increased to / cm ² , and the pressurized gas fuel is supplied to the gas fuel supply passage 25 through the fuel supply pipe 25.
The gas fuel supply valve 5 is operated by an electromagnetic force from the electromagnetic drive device 60 according to a command from the controller 20. When the gas fuel supply valve 5 operates according to a command from the controller 20, the gas fuel is quickly supplied from the fuel supply pipe 52 through the gas fuel passage 25 through the gas fuel supply valve 5 into the sub chamber 2 at a low pressure. Further, the pressure sensor 61 installed in the sub-chamber 2 detects that the gas fuel pressure in the sub-chamber 2 has reached the gas fuel pressure required for the engine load and the number of revolutions, and outputs the detection signal to the controller 20. When a predetermined amount of gas fuel is supplied to the sub chamber 2, the controller 2
For 0, a command is issued to close the gas fuel supply valve 5, and the supply of gas fuel to the sub chamber 2 is completed. The opening / closing operation of the gas fuel supply valve 5 can be performed by a valve mechanism that is synchronized with the rotation of the engine.

In this sub-chamber type gas engine, as shown in FIG. 2, the sub-chamber opening / closing valve 4 opens the communication port 6 from the vicinity of the end of the compression stroke to the beginning of the suction stroke.
Is set to communicate with the main chamber 1, and during this period, the gas fuel supply valve 5 closes the gas fuel supply port 22. Also, the gas fuel supply valve 5
Is set to open the gas fuel supply port 22 and supply the gas fuel to the sub chamber 2 from the intake stroke to the compression stroke. During this period, the sub chamber opening / closing valve 4 closes the communication port 6. It is a period of time.

This sub-chamber type gas engine is particularly suitable for the sub-chamber 2
And the intake port 9 are communicated with each other through the bypass passage 7, the bypass valve 8 is arranged in the bypass passage 7, and the controller 20
It is characterized in that the bypass valve 8 is operated by a command in response to the engine load to control the opening / closing timing of the bypass passage 7. The bypass passage 7 is connected to the sub chamber 2 through a bypass opening 21 formed in an upper portion of the sub chamber 2 that is farthest from the communication port 6. The bypass valve 8 is configured to open and close the bypass passage 7 by a valve body 81 that is operated by an electromagnetic drive device 34 that is driven by electromagnetic force, and the valve timing is controlled by a command from the controller 20. Further, in this sub-chamber gas engine, the gas fuel supply pressure P _G , the boost pressure P _B, and the exhaust gas pressure P _E are set in the following relationship. That is, P _G > P _B
> P _E relationship.

The controller 20 receives the load signal detected by the load sensor 18 and controls the opening / closing timing of the bypass valve 8. First,
As shown in FIG. 3, the controller 20 controls the bypass valve 8 to close the bypass passage 7 in response to the low load operation. In the low load operation, the flow rate of the gas fuel supplied to the sub-chamber 2 is small and the boost pressure of the intake air is low, so that the bypass valve is not scavenged by the intake air. 8 is a state in which the bypass passage 7 is always closed.

Further, the controller 20 has a configuration shown in FIGS.
In response to the medium load operation, the gas fuel supply port 22 by the gas fuel supply valve 5 starts near the latter half of the exhaust stroke, as shown in FIG.
The bypass valve 8 is operated and the bypass passage 7 is controlled to open during the period up to the middle of the suction stroke at the start of opening (shown as pattern A in FIG. 2). Further, the controller 20 responds to the medium load operation by operating the bypass valve 8 and opening the bypass passage 7 during the period from the latter half of the exhaust stroke to the middle of the intake stroke through the bypass passage 7. Air is supplied to the sub-chamber 2 so that the combustion gas remaining in the sub-chamber 2 is pushed out to the main chamber 1 to scavenge the sub-chamber 2 and the bypass valve 8 closes the bypass passage 7. Next, the gas fuel is supplied into the sub-chamber 2, but since the air existing in the sub-chamber 2 is not at a high temperature and the air amount is small, the gas fuel is spontaneously emitted even if the sub-chamber 2 is supplied with the gas fuel. There is no fire.

Further, the controller 20 has a configuration shown in FIGS.
In response to the high load operation, the bypass valve 8 is operated to open the bypass passage 7 from the vicinity of the latter half of the exhaust stroke to the end of the intake stroke (shown as pattern B in FIG. 2). . In addition, the controller 20
Intake air is supplied to the sub chamber 2 through the bypass passage 7 during the period from the latter half of the exhaust stroke in which the bypass valve 8 is opened in response to the high load operation to open the bypass passage 7 to the middle of the intake stroke. Then, the inside of the sub chamber 2 is scavenged by pushing out the combustion gas remaining in the sub chamber 2. Then
Although the gas fuel is supplied into the sub-chamber 2, the bypass valve 8 and the gas fuel supply valve 5 are wrapped and opened, but the gas fuel does not spontaneously ignite like the above, and the communication port 6 is provided. Near the end of the intake stroke when the gas fuel supply port 22 is closed and the gas fuel supply port 22 is opened, as described above, P _G > P _B > P
_In the relationship of _E , the gas fuel in the sub chamber 2 is transferred to the main chamber 1 through the bypass passage 7 and the intake port 9 by the boost pressure, that is, the differential pressure ΔP between the suction pressure P _B and the gas fuel supply pressure P _G. Part is supplied and then the bypass passage 7 is closed by the bypass valve 8. The flow rate of the gas fuel supplied to the main chamber 1 is small and becomes a lean mixture, but even if it is compressed in the main chamber 1 to become a high temperature gas, it does not ignite spontaneously.

In this sub-chamber gas engine, the controller 20 controls the gas fuel supply valve 5 to supply the sub-chamber 2 with an appropriate flow rate of gas fuel corresponding to the engine load and the engine speed.
Can be controlled to improve fuel efficiency and thermal efficiency. The controller 20 includes a load sensor 18 for detecting the engine load, a rotation sensor 62 for detecting the engine speed, a position sensor 63 for detecting the open / closed state of the sub chamber opening / closing valve 4, and a pressure sensor 61 for detecting the in-cylinder pressure of the sub chamber 2. Gas fuel supply valve 5 so that the flow rate of the gas fuel supplied into the sub chamber 2 becomes a preset fuel gas pressure that is optimum for the engine load based on the detection signals. Can be operated to supply the gas fuel to the sub chamber 2.

The sub-chamber gas engine is constructed as described above, and is operated, for example, as follows. This sub-chamber gas engine is operated by sequentially repeating four strokes of an exhaust stroke, an intake stroke, a compression stroke and an expansion stroke. In this sub-chamber gas engine,
The load sensor 18 detects the engine load and is input to the controller 20. In response to the detected engine load, that is, low load operation, medium load operation, and high load operation, the bypass valve 8 is operated as described above. Of course is controlled.

This sub-chamber type gas engine is as follows when the operation of the bypass valve 8 is not considered. In this sub-chamber gas engine, when the sub-chamber opening / closing valve 4 starts to lift near the end of the compression stroke, first, the sub-chamber opening / closing valve 4 separates from the communication port 6 to open the communication port 6, and at the same time, the main chamber 1 The hot compressed air inside flows into the sub chamber 2. The gas fuel supplied to the sub-chamber 2 is immediately mixed with the gas fuel in the sub-chamber 2 and ignited and burned, and the primary combustion is rapidly performed in the sub-chamber 2 to increase the pressure in the sub-chamber 2 and the expansion stroke. Then, the unburned gas and the combustion gas of flame are jetted from the sub chamber 2 through the communication port 6 to the main chamber 1. The air present in the main chamber 1 is entrained by the jet energy of the unburned air-fuel mixture and flame from the sub chamber 2 to burn rapidly and completes the secondary combustion in a short time, causing the piston 15 to do work. Improves thermal efficiency.

Next, in the exhaust stroke, the exhaust valve 1
2 opens the exhaust port 17, discharges the exhaust gas in the main chamber 1 and the sub chamber 2 through the exhaust port 17 at the beginning of the exhaust stroke, and the sub chamber opening / closing valve 4 opens the communication port 6 near the end of the exhaust stroke.
To close. Next, in the intake stroke, the auxiliary chamber opening / closing valve 4 closes the communication port 6, the intake valve 11 opens the intake port 9, intake air is supplied to the main chamber 1, and the gas fuel supply valve 5 Is activated and gas fuel supply port 2
2, the gas fuel is supplied to the sub chamber 2 through the gas fuel supply port 22, and the sub chamber 2 is filled with the gas fuel at an appropriate flow rate.

The sub-chamber 2 is filled with a predetermined amount of gas fuel through the suction stroke and the compression stroke after the sub-chamber opening / closing valve 4 closes the communication port 6. In the compression stroke, the intake valve 11 closes the intake port 9 and the subchamber opening / closing valve 4 closes the communication port 6, so that the intake air supplied into the main chamber 1 is highly compressed to a high pressure. It Next, when the sub chamber opening / closing valve 4 opens the communication port 6 near the end of the compression stroke, high-temperature compressed air is introduced into the sub chamber 2 through the communication port 6. In this sub-chamber gas engine, the engine is driven by repeating the above cycle.

[0030]

The sub-chamber gas engine according to the present invention is
As described above, the sub-chamber arranged substantially in the center of the cylinder and the main chamber formed on the cylinder side are communicated with each other through the communication port, and the sub-chamber opening / closing valve is arranged in the communication port to transfer the gas fuel to the sub-chamber. A gas fuel supply valve for supply is provided, and in particular, the sub chamber and the intake port are communicated with each other through a bypass passage in which a bypass valve is arranged, and a controller controls the opening / closing timing of the bypass valve in response to an engine load. Therefore, at the time of low load operation, the boost pressure is low, the flow rate of the gas fuel supplied to the sub chamber is small, and the sub chamber can be scavenged by the intake air. Supply operation is not performed. Further, since unburned gas may stay in the sub chamber during medium load operation, the bypass passage is opened to communicate the intake port with the sub chamber, and intake air is introduced into the sub chamber. Scavenging the sub-chamber. Furthermore, in response to high load operation,
The bypass passage is opened to communicate the intake port with the sub chamber, intake air is introduced into the sub chamber to perform scavenging of the sub chamber, and at the same time, the opening of the bypass passage is continued to maintain gas fuel. During the open overlap with the supply valve, the sub-chamber supplies a quantity equal to or less than the ignition limit of gas fuel to the main chamber through the bypass passage and the intake port.

As described above, in this sub-chamber type gas engine, by purging the sub-chamber with intake air, residual gas does not stay in the sub-chamber for a long period of time, and the wall temperature of the sub-chamber is maintained. An abnormally high temperature is prevented to prevent spontaneous ignition of gas fuel to prevent knocking, a compression ratio is increased to improve thermal efficiency, and efficiency during high load operation is not reduced. Therefore, in this sub-chamber gas engine, it is possible to promote combustion with a rich air-fuel mixture in the sub-chamber to reduce the generation of NO _X , reduce the generation of unburned HC and the like, and improve the thermal efficiency. It is possible, and there is no reduction in efficiency especially under high load.

[Brief description of the drawings]

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

FIG. 2 is a diagram showing the valve timing of each valve in the sub-chamber gas engine of FIG.

FIG. 3 is an explanatory diagram showing valve timing during low load operation of the sub-chamber gas engine of FIG. 1.

FIG. 4 is an explanatory diagram showing a valve timing during a medium load operation of the sub-chamber type gas engine of FIG. 1.

5 is an explanatory diagram showing valve timing during high load operation of the sub-chamber gas engine of FIG. 1. FIG.

[Explanation of symbols]

 1 Main Chamber 2 Sub Chamber 3 Sub Chamber Structure 4 Sub Chamber Open / Close Valve 5 Gas Fuel Supply Valve 6 Communication Port 7 Bypass Passage 8 Bypass Valve 9 Intake Port 11 Intake Valve 12 Exhaust Valve 13 Cylinder Head 14 Cylinder 17 Exhaust Port 18 Load Sensor 20 controller 22 gas fuel supply port

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Office reference number FI technical display location F02B 29/02 F02B 29/02 D 43/04 43/04 F02D 13/02 F02D 13/02 CL F02F 1/24 F02F 1/24 D E F02M 21/02 F02M 21/02 L

Claims (7)

[Claims] 1. A suction / exhaust port formed in a cylinder head, a suction / exhaust valve for opening / closing the suction / exhaust port, and a sub chamber which is disposed in the cylinder head and is formed in a substantially central portion of the cylinder. A chamber structure, a communication port formed in the sub chamber structure that communicates the sub chamber with the main chamber on the cylinder side, a sub chamber opening / closing valve for opening and closing the communication port,
A gas fuel supply valve that opens and closes a gas fuel supply port provided in the sub chamber for supplying gas fuel to the sub chamber, a bypass passage that connects the sub chamber and the intake port, and a bypass valve that opens and closes the bypass passage. And a controller for controlling the opening / closing timing of the bypass valve in response to an engine load. 2. The sub-chamber opening / closing valve opens the communication port from the vicinity of the end of the compression stroke during the period in which the gas fuel supply valve closes the gas fuel supply port to the beginning of the intake stroke to open the sub chamber. The sub-chamber gas engine according to claim 1, which communicates with the main chamber. 3. The gas fuel supply valve opens the gas fuel supply port from a suction stroke to a compression stroke in a period in which the sub chamber opening / closing valve closes the communication port to supply the gas fuel to the sub chamber. The sub-chamber gas engine according to claim 1 or 2, which supplies the gas. 4. The controller closes the bypass passage in response to a low load operation of the bypass valve,
In response to a medium load operation, the bypass passage is opened from around the latter half of the exhaust stroke to the latter half of the intake stroke when the opening of the gas fuel supply port by the gas fuel supply valve is started, and near the latter half of the exhaust stroke in response to high load operation. The sub-chamber gas engine according to any one of claims 1 to 3, wherein control is performed so as to open the bypass passage from the end of the intake stroke to the end of the intake stroke. 5. The intake air is supplied to the sub chamber through the bypass passage while the controller operates the bypass valve in response to a medium load operation to open the bypass passage. The scavenging of the sub chamber is performed.
The sub-chamber gas engine according to any one of claims 1 to 4. 6. The intake air is supplied to the sub chamber through the bypass passage while the controller operates the bypass valve in response to a high load operation to open the bypass passage. The sub-chamber is scavenged, and then the gas fuel in the sub-chamber is partially discharged to the main chamber through the intake port due to the pressure difference between the suction pressure and the supply pressure of the gas fuel with the communication port closed. The sub-chamber gas engine according to any one of claims 1 to 4, which supplies the gas. 7. The bypass valve is driven by an electromagnetic force, and the valve timing of the bypass valve is controlled by a command from the controller.
The subchamber gas engine according to the item.