JPH0220432Y2 - - Google Patents

Description

[Detailed description of the invention] This invention relates to an internal combustion engine, and in particular, it is possible to selectively switch the operating mode between gaseous fuel operation and liquid fuel operation for each cylinder, and it is possible to selectively switch the operating mode between gaseous fuel operation and liquid fuel operation for each cylinder. The present invention relates to an internal combustion engine that is capable of operating in a state where cylinders coexist and that provides a stable combustion state when operating on gaseous fuel.

BACKGROUND ART Conventionally, in LNG ships and the like, evaporated gas has been used as engine fuel in order to effectively utilize the gas that evaporates during transportation and reduce transportation costs. A specific example is:
The engine shown in Fig. 1 is an engine that compresses gaseous fuel to a high pressure of, for example, 200 to 250 bar, and transfers the compressed high-pressure gaseous fuel to a high-pressure gas valve.
This is a method in which the air is blown directly into the cylinder 2. In this case, combustion of the gaseous fuel is performed by injecting a small amount of liquid fuel such as diesel oil into the cylinder 2 from the liquid fuel pilot valve 3, and pilot ignition by compression ignition of this diesel oil. However, as a result, it is possible to achieve a combustion cycle close to that of a diesel cycle, and it is possible to improve combustion efficiency compared to an automatic cycle.

By the way, in so-called dual-fuel diesel engines that use liquid fuel such as diesel oil or heavy oil as pilot fuel along with gaseous fuel as described above, the injection valve for liquid fuel such as diesel oil is injected only for liquid fuel. It is necessary to design so that an output close to full load can be obtained even when the load is off.
The diameter of the nozzle must be large. As a result, when injecting a small amount of pilot fuel,
It is impossible to reduce the amount of pilot fuel relative to gas fuel below a certain limit because the injection amount is irregular and the spray is not sufficiently finely divided, making proper pilot ignition difficult. Moreover, if the fuel valve and fuel injection pump wear out due to long-term use, this limit amount will further increase. Therefore, even though an output commensurate with the evaporated gas is required, extra liquid fuel is required, and the amount thereof is considerable for the above-mentioned reasons, which is not economical. In addition, when gas fuel with a low methane number is used, its ignitability is poor, so the pilot ignition method using a small amount of liquid fuel is particularly prone to combustion failures.To prevent this, it is necessary to significantly increase the proportion of liquid fuel. It is also uneconomical.

In order to solve the above problems, it would be ideal to operate the engine only with gaseous fuel instead of using both gaseous fuel and liquid fuel as described above. Considering that there may be a shortage of gaseous fuel, and that there is a desire to use liquid fuel when entering and exiting ports, the engine must be designed to be able to operate on either gaseous or liquid fuel. The reality is that we don't get it.

This idea was created in view of the above, and its purpose is to enable selective switching of the operating mode between gaseous fuel operation and liquid fuel operation for each cylinder in an internal combustion engine, and to make it possible to selectively switch the operating mode between gaseous fuel operation and liquid fuel operation for each cylinder, and An object of the present invention is to provide an internal combustion engine that can be operated in a state where cylinders coexist.

The internal combustion engine of this invention which meets the above purpose is an internal combustion engine having a plurality of cylinders, each cylinder is equipped with a high pressure gas valve for injecting highly compressed gaseous fuel into the cylinder, and the gaseous fuel is An ignition plug for ignition and a fuel injection valve for injecting liquid fuel are respectively installed, and gaseous fuel operation is performed by the operation of the high pressure gas valve and the ignition plug, and liquid injection is performed by the operation of the fuel injection valve. The present invention is characterized by having a control device for selectively switching fuel operation for each cylinder.

As a result of the above, it becomes possible to selectively switch between gaseous fuel operation and liquid fuel operation for each cylinder by the control device, so normally the operation is performed using gaseous fuel, and when entering and leaving the port, It is possible to freely switch the fuel used, such as operating with liquid fuel when there is a shortage of gaseous fuel, and it is also possible to operate with cylinders with different operating modes coexisting. It becomes possible. Also,
When operating on gaseous fuel, liquid fuel such as diesel oil is not used as pilot fuel, so the amount of fuel residue that accumulates inside the cylinder is extremely small, and the amount of fuel residue that accumulates in the piston ring and cylinder liner is extremely small. Since wear can be reduced and ignition is reliably performed by the ignition plug, it is possible to maintain a stable combustion state within the cylinder.

Next, specific embodiments of the internal combustion engine of this invention will be described in detail with reference to the drawings.

In FIGS. 2 to 4, 11 indicates a cylinder, and since each cylinder 11 has substantially the same structure, only the structure of one cylinder 11 will be described below. That is, at the top of the cylinder 11 there is a cylinder head 12.
is placed therein, and a piston 13 that reciprocates in the vertical direction is arranged inside it. The cylinder head 12 is supplied with high pressure (for example,
a high-pressure gas valve 14 for blowing gaseous fuel compressed to 200-250 bar into the cylinder 11;
A spark plug 15 for igniting gaseous fuel within the cylinder 11 is attached to each cylinder.

The high-pressure gas valve 14 is connected to the high-pressure gas storage tank 18 via a line 17, and also to the ignition plug 1.
5 are each connected via a line 19 to an ignition device (not shown). Furthermore, a fuel injection valve 20 is attached to the cylinder head 12, and this fuel injection valve 20 is for injecting liquid fuel into the cylinder 11. It is connected to the fuel tank 22. A control device 23 is provided for controlling the operation of the high-pressure gas valve 14, spark plug 15, and fuel injection valve 20 in each cylinder 11, respectively, and switching the operating state for each cylinder 11. The control device 23 will be explained below, focusing on its operating state.

First, for the cylinder 11 that operates using gaseous fuel, the valve 24 installed in the line 17 connecting the high-pressure gas storage tank 18 and the high-pressure gas valve 14, the ignition plug 15, and the ignition device are connected. While connecting the contacts 25 provided in the connecting line 19, the fuel injection valve 20 and the fuel tank 22 are connected.
A valve 26 provided in the line 21 connecting the two is kept closed. As a result, the supply of liquid fuel to this cylinder 11 is stopped, gaseous fuel is supplied into the cylinder 11, and the spark plug 15
operates, making it possible to operate using gaseous fuel. On the other hand, for the cylinder 11 that operates using liquid fuel, the valve 26 may be opened and the valve 24 and the contact 25 may be cut off, contrary to the above. The switching command signal to the control device 23 may be input manually or may be input based on another detection signal.

As mentioned above, since the control device 23 can selectively switch between gaseous fuel operation and liquid fuel operation for each cylinder 11, normally operation is performed using gaseous fuel, It is possible to freely switch the fuel used, such as operating on liquid fuel when entering or exiting a port or when there is a shortage of gaseous fuel, and it is also possible to operate with cylinders with different operating modes coexisting. It is also possible to do so. Furthermore, when operating with gaseous fuel, liquid fuel such as diesel oil is not used as the pilot fuel, and the ignition is ignited by the spark plug 15. The amount of material can be significantly reduced, reducing wear.

Although one embodiment of the internal combustion engine of this invention has been described above, the internal combustion engine of this invention is not limited to the above embodiment, and has various points such as the spacing and number of spark plugs, the supply and exhaust system, etc. It will be obvious that the invention can be implemented with various modifications. Further, as the spark plug in the above, an electric spark or a high-temperature heat plug can be used.

The internal combustion engine of this invention is constructed as described above. Therefore, according to the internal combustion engine of this invention, gaseous fuel operation and liquid fuel operation are controlled for each cylinder by the control device. Since it is possible to selectively switch, the fuel used can be changed, such as normally operating on gaseous fuel, and operating on liquid fuel when entering or exiting port or when gaseous fuel is insufficient. It becomes possible to switch freely, and it is also possible to operate in a state where cylinders with different operating modes coexist. In addition, when operating on gaseous fuel, liquid fuel such as diesel oil is not used as pilot fuel, so the amount of fuel residue that accumulates inside the cylinder is extremely small, reducing wear. Along with getting
Since the spark plug ensures ignition, it is possible to maintain a stable combustion state within the cylinder. Moreover, as a result of the above, even a fuel with a low methane number and poor ignitability can be put to practical use.

[Brief explanation of the drawing]

Fig. 1 is an explanatory diagram showing a conventional device, Fig. 2 is an explanatory diagram showing an embodiment of the combustion chamber of the gas engine of this invention, and Fig. 3 is an explanatory diagram showing the groove structure of one cylinder in the above embodiment. It is. 11... Cylinder, 14... High pressure gas valve, 15
... Spark plug, 20 ... Fuel injection valve, 23 ... Control device.

Claims (1)

[Scope of utility model registration request] In an internal combustion engine having multiple cylinders, each cylinder includes a high-pressure gas valve for blowing gaseous fuel compressed to high pressure into the cylinder, a spark plug for igniting this gaseous fuel, and a liquid fuel. A fuel injection valve for injecting the fuel is installed, and gaseous fuel operation by the operation of the high-pressure gas valve and spark plug, and liquid fuel operation by the operation of the fuel injection valve are selected for each cylinder. An internal combustion engine characterized in that it has a control device for switching between the two.