JP2657457B2 - Dual fuel diesel 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 four-cycle dual fuel diesel engine using both gas fuel and liquid fuel.

[0002]

2. Description of the Related Art Gas fuel is supplied to an engine of this type by a premixing method (Japanese Patent Laid-Open No. 62-214238) in which gas fuel is dispersed in suction air and supplied, and gas fuel is injected by an injector. There is a supply system. In the latter method, gas fuel is injected and supplied in the compression step (Japanese Patent Laid-Open No. 62-58031, Japanese Utility Model Publication No. 3-558).
No. 10). In many cases, a gas injector similar to a liquid fuel injector is used to inject and supply gas fuel. For example, the actual fairness mentioned above 3-
In Japanese Patent Application Laid-Open No. 55810, an actuator pump driven synchronously using engine power is provided similarly to a liquid fuel injection pump, and the control oil controls the opening and closing of a gas injector. Regarding the gas fuel supply system and control system of the dual fuel diesel engine according to the present invention, see Japanese Patent Application Laid-Open No. Sho 62-5006.
It is publicly known from Japanese Patent No. 74.

[0003]

In the premixing method, gas fuel is supplied together with intake air in an intake process.
Gas fuel can be evenly dispersed in the combustion air, and it is easy to ignite, which is advantageous for complete combustion. However, there is a waste that a part of the gas fuel is discharged together with the exhaust gas as so-called raw gas in the early stage of the intake process. The gas concentration of the air-fuel mixture to be sucked is not always constant, and the amount of gas fuel for each cylinder tends to vary, making it difficult to obtain a stable operating state.

In the method of injecting and supplying gaseous fuel, raw gas is not discharged because gaseous fuel is supplied in the compression step. The supply amount of gas fuel can also be set strictly. However, since a relatively high-pressure gas fuel needs to be supplied, the fuel supply device for that purpose must be complicated.For example, a dedicated actuator pump must be provided to control the opening and closing of the injector and control oil must be supplied. There is. It is difficult to uniformly disperse the gaseous fuel in the compressed combustion air, and incomplete combustion is likely to occur. In particular, when gaseous fuel is injected and supplied simultaneously with liquid fuel, both fuels cannot be uniformly mixed with combustion air, and black smoke is likely to be generated. In any of the fuel supply systems, it is necessary to appropriately supply gas fuel and liquid fuel in accordance with the purpose of use of the engine and the application environment. However, a control device therefor is more complicated than that of an ordinary engine.

It is an object of the present invention to provide a dual fuel diesel engine capable of supplying gaseous fuel with a simpler fuel supply device and reducing the emission of raw gas and harmful components such as black smoke to a minimum. It is in. Another object of the present invention is to realize a dual fuel diesel engine by adding necessary equipment without redesigning or extensively remodeling a cylinder block or a head block. An object of the present invention is to provide a fuel supply system suitable for converting a diesel engine into a dual fuel and a control system therefor.

[0006]

SUMMARY OF THE INVENTION A dual fuel diesel engine according to the present invention comprises a liquid fuel supply system 11 for supplying liquid fuel and a gas fuel supply system 12 for supplying gas fuel.
And The gas fuel supply system 12 includes a gas cylinder 16 for storing fuel gas, a regulator 18 for adjusting the pressure of the gas supplied from the gas cylinder 16 to a predetermined pressure, and a gas adjusted to the predetermined pressure via the intake port 6. And an electromagnetically operated gas injector 19 for injecting and supplying the gas into the cylinder 1a. The fuel injection pump 14 constituting the liquid fuel supply system 11 has an electromagnetically operated pump actuator 32 for adjusting the fuel supply amount.
Is attached. The fuel injection timing of the gas injector 19 provided for each cylinder 1a is set between the time when the exhaust valve 5 is closed and the time when the intake valve 4 is closed in the intake stroke. An electronic controller 30 that controls the operation states of the gas injector 19 and the pump actuator 32 to control the supply amounts of the liquid fuel and the gas fuel.
It has. Specifically, between the head block 2 and the intake manifold 8, an injection block 26 having a relay passage 27 connecting each intake port 6 and the corresponding air passage 8a is interposed. The gas injector 19 is mounted on the hopper.

[0007]

The gas fuel is injected and supplied by the gas injector 19 between the time when the exhaust valve 5 is closed in the intake process and the time when the intake valve 4 is closed, so that all the gas fuel is contained in the cylinder 1a. Raw gas can be prevented from flowing into the exhaust gas. The gas fuel is injected and supplied into the cylinder 1a through the intake port 6 together with the sucked air, so that the gas fuel can be uniformly mixed with the combustion air, and all the fuel is completely burned. Since the gas injector 19 is provided for each cylinder 1a, gas fuel can be appropriately supplied without excess or deficiency. Since the gas fuel is injected and supplied into the cylinder 1a in the negative pressure state during the intake process, the injection gas pressure can be reduced, and the structure of the gas injector 19 can be simplified. Control peripheral devices such as an actuator pump can be omitted. The supply amount of gas fuel is controlled by an electromagnetically operated gas injector 19 and the injection pump 14 is controlled.
Since the supply amount of the liquid fuel is controlled by the electromagnetically operated pump actuator 32 attached to the controller, the supply control of the gas fuel and the liquid fuel can be easily controlled by the electronic controller 30, and the interlocking mechanism and matching required for the fuel control can be controlled. And the like can be omitted.

[0008]

According to the present invention, the gas fuel is injected and supplied by the gas injector 19, and the injection timing is set between the closing of the exhaust valve 5 and the closing of the intake valve 4 in the intake process. As a result, all the gaseous fuel is sealed in the cylinder 1a without the raw gas flowing out into the exhaust gas. Then, all the fuel can be completely burned by uniformly dispersing and mixing the gas fuel with the combustion air. Moreover, the gas fuel is supplied to each cylinder 1a for the control purpose, so that the performance of the dual fuel diesel engine can be improved as a whole.

Since the gas fuel is injected and supplied into the cylinder 1a in the negative pressure state through the intake port 6, the pressure of the injected gas can be reduced, and the load amount is smaller than that of the injector for injecting and supplying the gas fuel in the compression process. However, a gas injector 19 having a small and simple structure can be applied. Further, the gas injector 19 is of an electromagnetically operated type, and the supply control of the liquid fuel is controlled by an electromagnetically operated pump actuator 3.
2, the supply of the whole fuel can be controlled electrically, the device for supplying the fuel and the entire device for the control can be simplified, and the dual fuel diesel engine can be provided at low cost.

[0010] Since the injection block 26 is mounted between the head block 2 and the intake manifold 8 and the gas injector 19 is mounted on the injection block 26, the gas injector 19 can be easily added to an existing engine. Converting a diesel engine to a dual fuel diesel engine can be performed with minimal effort and at low cost.

[0011]

1 to 5 show an embodiment of a dual fuel diesel engine according to the present invention. In FIG.
Reference numeral 1 is a cylinder block, 2 is a head block, and 3 is a piston. An intake valve 4 and an exhaust valve 5 are arranged in the head block 2, and an intake port 6 opened and closed by each valve 4.
And an exhaust port 7 are provided. 8 is the intake manifold, 9
Is an exhaust manifold.

The engine is provided with a liquid fuel supply system 11 for supplying a liquid fuel such as light oil and a gas fuel supply system 12 for supplying a gas fuel such as natural gas. In FIG. 1, a liquid fuel supply system 11 includes a fuel tank 13, a fuel pump (not shown), a fuel injection pump 14, a liquid injector 15 mounted on the head block 2, and the like.

The gas fuel supply system 12 includes a gas cylinder 16 for storing natural gas in a gaseous state, an electromagnetically operated on-off valve 17, and a regulator 18 for adjusting the gas pressure down.
And a gas injector 19 for injecting and supplying gas supplied from the regulator 18 and a gas passage connecting each device. In an unused state, the gas cylinder 16 is filled with natural gas pressurized to about 250 kg / cm ² . This high pressure gas is supplied to the regulator 1
At 8, the pressure is adjusted and supplied to the gas injector 19. This supply pressure can be selected in the range of ^{2 to} 25 kg / cm ² . A heat exchanger 21 is incorporated in the regulator 18 to alleviate the cooling effect of the expansion gas during pressure reduction. The heat exchanger 21 uses hot water generated by a radiator of the engine as a heat exchange medium.

Although the gas injector 19 has substantially no difference in basic structure from the fuel injection nozzle for liquid fuel, the point that the on-off valve for opening and closing the fuel supply passage is switched by a solenoid, that is, the electromagnetically operated fuel injection There is a difference in that it is configured as a valve. The maximum engine speed is 5000r
pm, and the gas fuel injection timing is limited to a very short time as described later. Therefore, a gas injector 19 having a sufficiently high response speed and no operation delay is used. For example, an injector (model number SP051) manufactured by Servojet Products International, USA is one example. The gas injector 19 changes the amount of supplied fuel by changing the opening / closing time of the on-off valve to a larger or smaller time.

The gas injector 19 is provided for each cylinder 1
The gas fuel is injected and supplied to the combustion chamber together with the combustion air via the intake port 6. For this purpose, an injection block 26 is interposed between the head block 2 and the intake manifold 8, and a gas injector 19 corresponding to each cylinder 1a is mounted on the injection block 26. The injection block 26 is formed of an aluminum alloy. As shown in FIG. 2, a relay passage 27 connecting each intake port 6 and the air passage 8a of the intake manifold 8 is formed so as to cross the block laterally. . Further, a mounting hole 28 for mounting the gas injector 19 is formed on the upper surface of the block. As shown in FIG. 3, the injection block 26 is fastened and fixed together with the intake manifold 8 by using a mounting screw 29 of the intake manifold 8. In FIG. 2, reference numeral 41 denotes a throttle lever.

The gas fuel is injected and supplied in the intake process. Generally, the intake process is started by opening the intake valve 4 at a predetermined angle before the top dead center, closing the exhaust valve 5 at a predetermined angle after the top dead center, and then starting the predetermined operation after the bottom dead center as shown in FIG. The intake valve 4 is closed at an angle, and the process is terminated. In the present invention, fuel injection is performed between the time when the exhaust valve 5 is closed and the time when the intake valve 4 is closed. For example, when the exhaust valve 5 is closed at a position 20 degrees from the top dead center and the intake valve 4 is closed at a position 55 degrees from the bottom dead center, the closing positions of the two valves 5.4 are sandwiched. Fuel injection is performed with the angle range of 215 degrees maximized.
This is because a part of the supplied gas fuel is exhausted together with the exhaust gas through the exhaust valve 5 in the overlap period indicated by reference numeral a in FIG.

In FIG. 1, a controller 30 having a microprocessor for controlling the supply amounts of the liquid fuel and the gaseous fuel is provided.
Is provided with an electromagnetically operated pump actuator 32 for operating the control rack. The controller 30 controls the operation amount signal 33 of the throttle lever 41 (or the accelerator pedal), the engine speed signal, and the rack position sensor 38.
Position signal and timing sensor 3 output from
4, a timing pulse output from the intake air temperature sensor 35, an intake pressure signal output from the intake manifold pressure sensor 36, a cooling water temperature signal output from the cooling water temperature sensor 37, if necessary. Upon receiving a signal such as a primary-side gas pressure signal, the operation state of the gas injector 19 and the fuel injection pump 14 is controlled based on a preset control algorithm. The basic operation mode, always mode for the gas fuel and the main fuel, priority mode output improvement of the engine, harmful components in the exhaust gas (graphite, NO _X, etc.) include priority mode lowering of interest Various modes can be set according to. Reference numeral 39 denotes a display provided with various display lamps and the like.

In order to convert an already operating existing diesel engine into a dual fuel diesel engine,
The following equipment can be supplied as a retrofit kit:
The components constituting the gas fuel supply system 12, the injection block 26, the pump actuator 32 for the fuel injection pump 14, the controller 30, the sensors 34 to 38, and the brackets for fixing these fixedly , A holder, a wiring code, a display 39, and the like. In this modified kit, each device can be added to the diesel engine. For example, there is no need to change the structure of the cylinder block 1 or the head block 2 or perform any additional processing, so that the cost required for remodeling can be reduced. Although the cost of the remodeling kit accounts for much of the remodeling cost, both the gas injector 19 and the pump actuator 32 to be controlled are electromagnetically operated, so that the remodeling is more expensive than when the control is performed mechanically. The total cost of the kit is low and the overall cost can be reduced to a dual fuel diesel engine.

The fuel pump 14 may be a distribution type pump other than the Bosch type. The injection block 26 can be formed in a plurality.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram conceptually showing the contents of the present invention.

FIG. 2 is a schematic sectional view of a main part of an engine.

FIG. 3 is a perspective view showing a structure of an injection block.

FIG. 4 is an explanatory diagram showing an injection timing of gas fuel.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Cylinder block 2 Head block 6 Intake port 8 Intake manifold 11 Liquid fuel supply system 12 Gas fuel supply system 15 Liquid injector 16 Gas cylinder 18 Regulator 19 Gas injector 26 Injection block 27 Relay passage 30 Controller 32 Pump actuator

──────────────────────────────────────────────────続 き Continuation of the front page (51) Int.Cl. ⁶ Identification number Agency reference number FI Technical display location F02M 21/02 301 F02M 21/02 301R 25/00 25/00 KR 69/04 69/04 A

Claims (2)

(57) [Claims] 1. A liquid fuel supply system 1 for supplying a liquid fuel.
1 and a gas fuel supply system 12 for supplying gaseous fuel, wherein the gas fuel supply system 12 is supplied from a gas cylinder 16 for storing fuel gas and a gas cylinder 16. A regulator 18 for reducing the pressure of the gas to a predetermined pressure, and an electromagnetically operated gas injector 19 for injecting the gas adjusted to the predetermined pressure into the cylinder 1a through the intake port 6; Fuel injection pump 14 constituting system 11
Is provided with an electromagnetically operated pump actuator 32 for adjusting the fuel supply amount. The fuel injection timing of the gas injector 19 provided corresponding to each cylinder 1a is determined when the exhaust valve 5 is closed in the intake stroke. To the time point when the intake valve 4 closes, the gas injector 19 and the pump actuator 3
2. A dual fuel diesel engine comprising an electronic controller 30 that controls the operating state of the second and controls the supply amounts of the liquid fuel and the gas fuel. 2. Each intake port 6 and a corresponding air passage 8a are provided between the head block 2 and the intake manifold 8.
2. The dual fuel diesel engine according to claim 1, further comprising an injection block provided with a relay passage connecting the fuel injector and a gas injector mounted on the injection block.