JP2889973B2 - Multi-cylinder sub-chamber lean-burn gas engine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a multi-cylinder sub-chamber lean-burn gas engine which is operated by supplying supply air having a low fuel concentration to a main combustion chamber and supplying fuel gas to a sub-combustion chamber. .

[0002]

2. Description of the Related Art The concentration of nitrogen oxides contained in exhaust gas discharged from a gas engine is reduced as the fuel concentration of the supply air becomes leaner, that is, as the amount of oxygen contained in the supply air increases. However, since the fuel cannot be burned if the fuel concentration in the air is lean, the fuel gas is supplied from the gas pipe to the auxiliary combustion chamber leading to the main combustion chamber, so that the air is lean-burned in the main combustion chamber. ing.

[0003] In such a sub-chamber lean-burn gas engine, a throttle valve that operates according to the engine load is provided in the middle of the supply pipe in order to adjust the amount of air supplied to the main combustion chamber in accordance with the engine load. Provided. In addition, since it is necessary to adjust the amount of fuel gas supplied to the sub-combustion chamber according to the amount of air supplied to the main combustion chamber, the fuel is supplied in the middle of the gas pipe for supplying the fuel gas to the sub-combustion chamber. A regulator for adjusting the gas flow rate is provided. The regulator operates in accordance with the supply pressure downstream of the throttle valve. As a result, when the engine load increases and the opening of the air supply pipe by the throttle valve increases, the air supply pressure on the downstream side of the throttle valve increases, so the fuel supplied from the gas pipe to the auxiliary combustion chamber via the regulator The gas flow increases. Further, when the engine load decreases and the degree of opening of the air supply pipe by the throttle valve decreases, the air supply pressure on the downstream side of the throttle valve decreases, so the fuel gas supplied from the gas pipe to the sub-combustion chamber via the regulator The flow rate decreases. Also,
When the engine load is cut off, the opening degree of the supply pipe by the throttle valve is minimized, and the flow rate of the fuel gas supplied from the gas pipe to the auxiliary combustion chamber via the regulator is also minimized.

[0004]

When the engine load is cut off and the opening of the air supply pipe by the throttle valve is minimized, the amount of air supplied to the main combustion chamber sharply decreases. In this case, the amount of fuel gas passing through the regulator also decreases, but the fuel gas that has passed through the regulator immediately before the load is cut off remains in the fuel gas passage downstream of the regulator. The amount of the remaining fuel gas increases because the fuel gas passage becomes longer as the number of cylinders of the engine increases. When a large amount of fuel gas remaining in the gas passage is supplied to the sub-combustion chamber, the amount of air supplied to the main combustion chamber is rapidly reduced. Run short. Therefore, there is a problem that a misfire occurs, fuel gas in the combustion chamber flows into the exhaust manifold, and explodes in the exhaust manifold.

An object of the present invention is to solve the above-mentioned problems of the prior art.

[0006]

A feature of the present invention is that the main combustion chamber is supplied with air having a lean fuel concentration from an air supply pipe, and the auxiliary combustion chamber is supplied with fuel gas from a gas pipe. A throttle valve that operates in accordance with the engine load is provided in the middle of the trachea, and a regulator for adjusting the flow rate of the fuel gas is provided in the middle of the gas pipe. This regulator is provided in accordance with the supply pressure downstream of the throttle valve. Multi-cylinder sub-chamber lean-burn gas engine
A communication passage is provided for communicating the air supply passage with a fuel gas passage downstream of the regulator, and an electromagnetic on-off valve for opening and closing the communication passage is provided. Is to open for a certain period of time.

[0007]

According to the structure of the present invention, when the engine load is cut off, the air supply passage and the fuel gas passage downstream of the regulator are opened for a predetermined time by the electromagnetic on-off valve. The fuel gas that has passed through the regulator is supplied to an air supply passage. Thus, a large amount of fuel gas is not supplied to the sub-combustion chamber when the engine load is cut off.

[0008]

Embodiments of the present invention will be described below with reference to the drawings.

First, a fuel system of a multi-cylinder sub-chamber lean-burn V-type engine 1 according to an embodiment of the present invention will be described with reference to FIG.

The V-type engine 1 has 12 cylinders,
A cylinder block 2 forming a cylinder arranged in a V-shape as viewed from the front, a piston 3 reciprocating in the cylinder block 2, a crankshaft 4 connected to the piston 3, and a cylinder covering the cylinder block 2 from above And a head 5. The upper part of the piston 3 in the cylinder block 2 is the main combustion chamber 6. A sub-combustion chamber 7 communicating with the main combustion chamber 6 is formed inside the cylinder head 5.

The main combustion chamber 6 is supplied with supply air having a low fuel concentration. First, the fuel gas supplied from the fuel supply main pipe 10 is reduced to approximately atmospheric pressure by the regulator 11, and thereafter, the pair of flow control devices 12a, 12b
Supplied to Each of the flow control devices 12a and 12b includes flow control valves 13a and 13b and on-off valves 14a and 14b. Each valve 13a, 13b, 14a, 14b is connected to the control device 1
The control device 115 is connected to a speed sensor 116 of the engine 1. Thereby, each valve 1
The opening degree of each of 3a, 13b, 14a, and 14b is adjusted by the control device 115 in accordance with the speed of the engine 1.
The flow rate of the fuel gas according to the rotation speed of the
a, 12b.

The fuel gas sent from each of the flow controllers 12a and 12b is supplied to a pair of mixers 15a and 15b. Each of the mixers 15a and 15b mixes the fuel gas and the air supplied through the air filters 16a and 16b by using a Venturi tube, and sends out a supply air with a low fuel concentration.

The air supplied from one mixer 15a is supplied to one of a pair of exhaust turbochargers 17a and 17b.
The air supply supplied to the compressor a and supplied from the other mixer 15b is supplied to the compressor of the other exhaust turbocharger 17b.

A supply pipe 18a for supplying air supplied from the compressor of one exhaust turbocharger 17a and a supply pipe 18b for supplying air supplied from the compressor of the other exhaust turbocharger 17b are connected to form a single unit. Is the first air supply pipe 19.

The first air supply pipe 19 is branched and connected to a pair of water-cooled intercoolers 20a and 20b for cooling the air supply.

A supply pipe 21a for supplying air supplied from one intercooler 20a and a supply pipe 21b for supplying air supplied from the other intercooler 20b are connected to form a single second supply pipe 22.

The second air supply pipe 22 is branched and connected to a pair of air supply manifolds 23a and 23b. From one air supply manifold 23a, air is supplied via a branch pipe 24a to each main combustion chamber 6 of the cylinders of the V-type engine 1 along the row on the left side in FIG. In addition, the supply air is supplied from the other supply manifold 23b to the main combustion chambers 6 of the cylinders along the other row of the V-type engine via the branch pipe 24b.

A fuel gas is supplied to the sub-combustion chamber 7.
That is, a bypass pipe 30 branched from the fuel supply main pipe 10 is formed, and a compressor 31 for increasing the pressure of the fuel gas flowing through the bypass pipe 30 is provided. The delivery pipe for the fuel gas delivered from the compressor 31 is branched into a first gas main pipe 32a and a second gas main pipe 32b. Fuel gas is supplied from the first gas main pipe 32a to the sub-combustion chamber 7 along the left column in FIG. 2 via the branch pipe 33a. Further, the fuel gas is supplied from the second gas main pipe 32b to the sub-combustion chamber 7 along the other row via the branch pipe 33b. A check valve 70 shown in FIG. 8 is interposed between each branch 33a, 33b and the sub combustion chamber 7 so that the fuel gas does not flow backward from the sub combustion chamber 7 to the gas main pipes 32a, 32b. The check valve 70 includes a housing 71, a fuel gas inlet 75 formed in the housing 71, and a fuel gas outlet 72.
And a valve 73 for opening and closing the fuel gas outlet 72. The valve 73 is urged by a spring 74 in a direction to close the outlet 72. Thereby, when the pressure of the sub-combustion chamber 7 communicating with the outlet 72 side in the intake process becomes small,
The valve 73 moves downward due to the spring 74 and the pressure of the fuel gas flowing from the inlet 75, and the outlet 72 opens to supply the fuel gas to the sub-combustion chamber 7. In addition, when the pressure in the sub-combustion chamber 7 increases in the exhaust step or the compression step, the valve 73 moves upward to close the outlet 72, so that backflow of fuel from the sub-combustion chamber 7 is prevented.

The exhaust gas is supplied from a pair of exhaust manifolds 90a and 90b to the turbines of the exhaust turbochargers 17a and 17b via exhaust pipes 91a and 91b.
After that, it is discharged from the V-type engine 1.

A throttle valve 40 is disposed inside the second air supply pipe 22. This throttle valve 4
0 operates according to the engine load. When the engine load increases, the opening degree of the second air supply pipe is increased to supply a large amount of supply air to the main combustion chamber 6, and when the engine load decreases, the supply to the main combustion chamber 6 is performed. Less air supply. The operation of the throttle valve 40 is controlled by the electronic governor device 100. Further, the opening degree of the second air supply pipe 22 is minimized by shutting off the engine load, and the supply of air supply to the main combustion chamber 6 is minimized. The engine load cutoff signal is sent from the engine load control device 105 to the electronic governor device 100, and the electronic governor device 100 immediately operates the throttle valve 40 to the minimum opening position.

The amount of fuel gas sent to the sub-combustion chamber 7 is adjusted in response to the change in the amount of air supplied to the main combustion chamber 6 according to the engine load. That is, the regulators 41a and 41b are provided in the middle of the first gas main pipe 32a and the second gas main pipe 32b, respectively. Each of the regulators 41a and 41b includes a main body block 44 as shown in FIG.
a, an inlet 42 communicating with the upstream side of 32b,
a and an outlet 43 communicating with the downstream side of 32b. An on-off valve 45 for adjusting the opening of a passage 47 between the inlet 42 and the outlet 43 is provided. This on-off valve 45
7 is urged in a direction to close the passage 47 by being pressed downward in FIG. The on-off valve 45 is connected to a diaphragm 48, and a pressure chamber 49 is formed below the diaphragm 48. A spring 150 that pushes the diaphragm 48 upward in FIG. 7 is disposed inside the pressure chamber 49. Further, a connection port 51 is formed in the pressure chamber 49, and a connection pipe 50 connected to the connection port 51 connects the inside of the pressure chamber 49 and an air supply passage downstream of the throttle valve 40.

As a result, when the engine load increases and the degree of opening of the second supply pipe 22 by the throttle valve 40 increases, the supply pressure downstream of the throttle valve 40 increases, so that the pressure in the pressure chamber 49 increases. Become.
Then, as the diaphragm 48 moves upward in FIG. 7, the on-off valve 45 moves upward, and the opening of the passage 47 increases. Accordingly, in response to an increase in the amount of supply air supplied to the main combustion chamber 6, the gas main pipes 32a and 32b
The amount of fuel gas supplied to the fuel cell increases.

When the engine load is reduced and the opening of the second supply pipe 22 by the throttle valve 40 is reduced, the supply pressure downstream of the throttle valve 40 is reduced, so that the pressure in the pressure chamber 49 is reduced. . Then
When the diaphragm 48 moves downward in FIG. 7, the on-off valve 45 moves downward, and the opening of the passage 47 decreases.
Accordingly, the amount of fuel gas supplied from the gas main pipes 32a and 32b to the sub-combustion chamber 7 decreases in response to the decrease in the amount of supply air supplied to the main combustion chamber 6.

When the throttle valve 40 is actuated by a load cutoff signal and the opening of the second supply passage 22 is minimized, the amount of air supplied to the main combustion chamber 6 decreases sharply. In this case, the amount of fuel gas passing through the regulators 41a and 41b also decreases. However, the fuel gas that has passed through the regulators 41a and 41b immediately before the load cutoff signal is
It remains in the fuel gas passage downstream of the regulators 41a and 41b. The amount of fuel gas remaining in the fuel gas passage downstream of the regulators 41a and 41b is V
As the number of cylinders of the engine 1 increases, the number of fuel gas passages increases because the length of the fuel gas passage increases. If a large amount of fuel gas remaining in the fuel gas passage is supplied to the sub combustion chamber 7, the main combustion chamber 6
The amount of air supplied to the sub-combustion chamber 7 is insufficient because oxygen is insufficient to burn the fuel gas in the sub-combustion chamber 7 and a misfire occurs. Then, unburned fuel gas explodes in the exhaust manifolds 90a and 90b.

In order to prevent such a situation from occurring, the first gas main pipe 32 downstream of the regulators 41a and 42b is used.
a, a fuel gas passage inside 32b, and an air filter 1
Communication passages 60a and 60b are provided for communicating the air supply passages between the mixers 6a and 16b and the mixers 15a and 15b. In addition, electromagnetic on-off valves 61a and 61b for opening and closing the communication passages 60a and 60b are provided. The electromagnetic on-off valves 61a and 61b are of a normally closed type, and open the communication paths 60a and 60b for a predetermined time in response to an engine load cutoff signal from the control device 105. As a result, when the engine load is cut off, the fuel gas remaining in the fuel gas passage downstream of the regulators 41a and 41b reaches the supply passage through the communication passages 60a and 60b. No fuel gas is supplied and misfires and exhaust manifold 90
Explosion accidents at a and 90b can be prevented.
The time for opening the electromagnetic on-off valves 61a and 61b is appropriately set according to the number of cylinders, the displacement, etc. of the V-type engine 1.

The first gas main pipe 32a and the second gas main pipe 32b are connected by a communication pipe 65 downstream of the regulators 41a and 41b.
The fuel gas pressure in the chamber is made uniform.

Next, the structure of the V-type engine 1 will be described with reference to FIGS.

The V-type engine 1 drives a generator 80 as an engine accessory, and the V-type engine 1 and the generator 80 are installed on a common bed 81.

As shown in FIG. 5, a pair of exhaust manifolds 90a and 90b are arranged inside a V bank of a cylinder formed in a V shape when viewed from the front. By arranging the exhaust manifolds 90a and 90b inside the V-bank in this way, safety when the exhaust manifolds 90a and 90b explode is achieved. Exhaust manifold 90a,
Since 90b is arranged inside the V bank, the pair of air supply manifolds 23a and 23b are arranged outside the V bank.

One end of the engine body (left end in FIG. 2)
A pair of exhaust turbochargers 17a and 17b is arranged above the. It is difficult to use a single exhaust turbocharger in the V-type engine 1 because the exhaust turbochargers 17a and 17b are paired, and the efficiency of the exhaust turbocharger is improved. This is to reduce the size. As shown in FIG. 3, a mixer 15a for mixing the fuel gas supplied from the fuel supply main pipe 10 and the air supplied through the air filters 16a and 16b is provided outside the exhaust turbochargers 17a and 17b. 15b are arranged.

A pair of intercoolers 20 for cooling air supply is provided above the other end (right end in FIG. 2) of the engine body.
a and 20b are arranged. Intercooler 20a, 2
The reason why 0b is paired is that if it is made single, it becomes large,
In order to make the V-type engine 1 compact, a pair is used.

The delivery pipes 18a for the supply air supplied from the compressors of the respective exhaust turbochargers 17a, 17b,
18b are connected to form a single first air supply pipe 19. The first air supply pipe 9 is disposed inside the V bank and below the exhaust manifolds 90a and 90b, as shown in FIGS. Thereby, the air supplied from each of the exhaust turbochargers 17a and 17b is supplied to the first air supply pipe 1
9 and the amount of air supply and the mixing ratio between fuel and air are made uniform. Then, the first air supply pipe 19 is branched and connected to each of the intercoolers 20a and 20b.

The supply pipes 21a and 21b for supplying the air supplied from the intercoolers 20a and 20b are connected to form a single second air supply pipe 22. This second air supply pipe 22
Is located inside the V bank and above the first air supply pipe 19 and the exhaust manifolds 90a, 90b.
Thereby, the air supplied from each of the intercoolers 20a and 20b is mixed inside the single second air supply pipe 22b, so that the amount of air supply and the mixing ratio of air and fuel are made uniform. In addition, since the second air supply pipe is located inside the V bank and above the first air supply pipe 19, the width of the V-type engine 1 can be reduced to make it compact.

The second air supply pipe 22 is branched and connected to each of the air supply manifolds 23a and 23b. Supply air is supplied from the respective supply manifolds 23a and 23b to the main combustion chamber 6 of the V-type engine 1 via branch pipes 24a and 24b. As shown in FIG. 5, each of the branch pipes 24a and 24b has an L-shape, and the cross-sectional area of the flow passage decreases toward the main combustion chamber 6 in order to reduce the air supply. Thereby, even if the flow path resistance is not uniform due to the difference in the distance from the inlets of the air supply manifolds 23a, 23b to the respective main combustion chambers 6, the air supply flow rate is made uniform by the throttle portions in the branch pipes 24a, 24b. Thus, the amount of air supplied to each main combustion chamber 6 is made uniform.

As shown in FIGS. 2 and 6, the second air supply pipe 22
The throttle valve 40 provided inside is connected to the electronic governor device 100 via a link 101. The electronic governor device 100 is cooled by being arranged near the intercooler 20a.

As shown in FIG. 3, a bypass pipe 30 for supplying fuel to the auxiliary combustion chamber 7 of the V-type engine 1 branches at one end of the V-type engine 1. As shown in FIG. 1, a first gas main pipe 32 branched from the bypass pipe 30
a and the second gas main pipe 32b are arranged outside the V bank. Regulators 41 a and 41 b provided in the middle of each gas main pipe 32 a and 32 b are arranged at one end of the V-type engine 1. A communication passage 60 that communicates a fuel gas passage downstream of the regulators 41a and 41b with a passage between the air filters 16a and 16b and the mixers 15a and 15b.
a and 60b are constituted by piping at one end of the V-type engine 1. Electromagnetic on-off valves 61a, 61b for opening and closing the communication passages 60a, 60b are arranged at one end of the V-type engine 1. A communication pipe 6 that connects the first gas main pipe 32a and the second gas main pipe 32b downstream of the regulators 41a and 41b.
5 is disposed on the other end side of the V-type engine 1 as shown in FIGS.

As shown in FIGS. 5 and 6, the first air supply pipe 19
Is a double pipe, air supply flows inside the inner pipe 19a, and cooling water flows between the outer pipe 19b and the inner pipe 19a. As the cooling water, a part of the cooling water flowing through the cooling water jacket inside the cylinder block 2 of the V-type engine 1 is used. Therefore, the first air supply pipe 19 and the cylinder block 2 are connected via the cooling water pipe 110. Also, this inner tube 19a
The cooling water flowing between the cooling water and the outer pipe 19b is discharged through the cooling water collecting pipe 111.

Generator 8 driven by V-type engine 1
0 is disposed below the intercoolers 20a and 20b. Cooling water pipes 120a and 120b for supplying cooling water to the intercooler and the intercooler 20
a, cooling water pipe 1 for discharging cooling water from 20b
The pipes 21b and 121a are piped outside the generator 80. Thereby, the pipes 120a, 120b, 1
This prevents water leaks from 21a and 121b from falling onto generator 80.

The interior of the bed 81 on which the V-type engine 1 and the generator 80 are installed is the oil pan 8 of the V-type engine 1.
3 and through a pipe 84. Thus, the interior of the bed 81 is a tank for lubricating oil. The cooling water pipes 120b and 121b of the one intercooler 20b penetrate the inside of the bed 81. Thus, the lubricating oil of the V-type engine 1 is cooled by the intercooler cooling water, and the capacity of the lubricating oil cooler (not shown) can be reduced. The engine accessory is not limited to the generator, but may be, for example, a compressor.

[0040]

According to the multi-cylinder sub-chamber lean-burn gas engine of the present invention, it is possible to prevent a large amount of fuel gas from being supplied to the sub-combustion chamber when the engine load is cut off. Explosion of fuel gas in the fuel cell can be prevented.

[Brief description of the drawings]

FIG. 1 is a diagram showing a fuel system of a V-type engine according to an embodiment of the present invention.

FIG. 2 is a side view of a V-type engine according to the embodiment of the present invention.

FIG. 3 is a front view of a V-type engine according to the embodiment of the present invention.

FIG. 4 is a rear view of the V-type engine according to the embodiment of the present invention.

FIG. 5 is a cross-sectional view of a V-type engine according to the embodiment of the present invention.

FIG. 6 is a longitudinal sectional view of a main part of a V-type engine according to the embodiment of the present invention.

FIG. 7 is a sectional view of a regulator according to an embodiment of the present invention.

FIG. 8 is a sectional view of a check valve according to an embodiment of the present invention.

[Explanation of symbols]

 Reference Signs List 1 V-type engine 6 Main combustion chamber 7 Sub-combustion chamber 22 Second air supply pipe 32a, 32b Gas main pipe 40 Throttle valve 41a, 41b Regulator 60a, 60b Communication path 61a, 61b Electromagnetic on-off valve

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int. Cl. ⁶ , DB name) F02M 21/00-21/06 F02B 19/10

Claims (1)

(57) [Claims] An air supply having a lean fuel concentration is supplied to a main combustion chamber from an air supply pipe, a fuel gas is supplied to a sub combustion chamber from a gas pipe, and a throttle valve that operates in accordance with an engine load in the middle of the air supply pipe. A regulator for controlling the flow rate of fuel gas is provided in the middle of the gas pipe, and this regulator operates in accordance with the supply pressure downstream of the throttle valve in a multi-cylinder sub-chamber lean-burn gas engine. A communication passage communicating the air supply passage with the fuel gas passage downstream of the regulator; and an electromagnetic on-off valve for opening and closing the communication passage. The electromagnetic on-off valve is connected by an engine load cutoff signal. A multi-cylinder sub-chamber lean-burn gas engine characterized by opening a passage for a certain period of time.