JPS61118526A - Method of supplying mixture into gas engine - Google Patents

Abstract

PURPOSE:To provide an engine which is less in blow-by and has a high combustibility, by dividing the intake-air passage into two system one of which is for air alone while the other one of which is for mixture alone, and by making the timing of intake-air of one of the systems different from that of the other one of the systems. CONSTITUTION:A supercharged by a turbocharger 9 flows through an intercooler 10, and is divided into streams passing through pipes 7, 11 and led into an engine cylinder 1 through two intake valves 2, 4 provided for each engine cylinder. A mixer 14 disposed in the pipe 11 feeds fuel gas into mixture through a valve 13 controlled in accordance with a feed air pressure signal. Just before termination of exhaust stroke of the engine cylinder 1 the intake valve 4 alone opens to scavenge exhaust gas, and thereafter the intake valve 2 opens after an exhaust valve 3 closes to feed mixture. The timings of closing of intake valves, 2 are made to be the same.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a mixture supply method applied to a gas engine equipped with a carburetor that uses gasoline, kerosene, FiLPG, or the like as fuel.

The air-fuel mixture supply method in a gas engine is roughly divided into a continuous supply method using a carburetor and a timing supply method using an injection nozzle.

The former continuous supply method (a) does not require precision parts such as fuel injection pumps and injection valves, and is easy to handle.

(b) Since no injection pump is used, there is no need for a driving device for this, and the overall structure is simple.

(c) Cost is low.

) Good mixture of air-fuel mixture.

2) It is easy to obtain the proper mixture ratio during starting, and the starting characteristics are good.

It has these advantages and is mainly used in small gas engines with a bore of 200AS class or less.

In addition, the latter timing supply method (a) allows a wide range of mixture ratio adjustment (setting), and evenly distributes the mixture.

(b) Since there is no restriction in the intake system, the intake efficiency is good.

(c) Transient characteristics such as acceleration and deceleration of the engine are improved, and responsiveness is improved.

) Fuel can be adjusted.

(e) Exhaust gas characteristics are improved.

(F) There is no air-fuel mixture blow-through during the polymerization period (pulp overchip) when the supply and exhaust valves are open.

(g) Since the palfo-burlap period can be as busy as that of conventional diesel engines, the heat load on pistons, etc. is lower than that of the former continuous supply system.

It has the advantages of mainly a bore of 200 jIll.
It is used in the larger Naka and Daisei gas engines.

By the way, the above-mentioned continuous supply method and timing supply method each have advantages and disadvantages, and in the end, it can be said that they have advantages and disadvantages overall.

An object of the present invention is to provide a mixture supply method in which a continuous supply method and a timing supply method are used in combination, in which the advantages of these methods are exhibited and the disadvantages are compensated for.

The present invention provides a cylinder with a scavenging pulp and an air manifold dedicated to air, opens the scavenging pulp just before the end of the exhaust stroke to scavenge the inside of the cylinder, and opens the mixture pulp almost simultaneously with the clogging of the exhaust pulp to fill the cylinder. By introducing the air-fuel mixture and closing either the scavenging pulp or the air-fuel mixture valve near the bottom dead center of the piston, and closing the other pulp at the same time as or before the above one pulp, the above-mentioned The purpose has been achieved.

The present invention will be explained in detail below.

FIGS. 1 and 2 show a mixture supply device for implementing the mixture supply method of the present invention, and in the figures, 1 is a cylinder. This cylinder IK is provided with a mixture valve 2, an exhaust valve 3, and a scavenging pulp 4, which are opened and closed synchronously with the movement of a piston (not shown) inserted in combination into the cylinder 1, which will be described later. It is configured. Although a plurality of cylinders 1 are arranged in parallel, only one of them is depicted in the drawing.

A mixture manifold 5 is connected to the mixture pulp 20 portion, an exhaust manifold 6 is connected to the exhaust pulp 30 portion, and an air manifold 7 is connected to the scavenging pulp 4 portion. Further, a supercharger 9 equipped with a compressor 8 is provided at the exhaust end of the exhaust manifold 6, and an air cooler 10 is provided on the compressor 8 side of the supercharger 9.
The air manifold 7 and the air supply end of the air supply pipe 11 are connected to each other on the downstream side of the air cooler 10.

On the other hand, the fuel gas supply pipe 12 is provided with a gas regulator 13 , and the fuel gas supply pipe 12 and the air supply pipe 11 are connected to the air-fuel mixture manifold 5 via a carburetor 14 . The gas regulator 13 operates in response to the air supply pressure and adjusts the fuel gas supply pressure to keep the differential pressure between the air pressure pa and the fuel gas pressure Pg constant. Therefore, regardless of the increase or decrease in the amount of air-fuel mixture, a mixture with a constant air-fuel ratio can always be obtained in the carburetor 14.
and the connection portion between the mixture manifold 5, the bypass pipe 15 of the compressor 8, and the air cooler 10 and the air manifold 7.
A mixture volume adjustment pulp 16, an air volume adjustment pulp 17, and a scavenging volume adjustment valve 18 are respectively provided at the connecting portion of the air mixture volume adjustment valve 16, and the mixture volume adjustment valve 16 is controlled by a governor 19 in the usual manner. Engine speed (engine output)
is now being adjusted.

Here, an example of the timing of opening and closing of the air-fuel mixture valve 2, exhaust valve 3, and scavenging pulp 4 will be explained with reference to FIG. 3. In this figure, TDC indicates the top dead center of the piston, and BDC indicates the bottom dead center of the piston. It is something.

First, the exhaust valve 3 opens at time t1 at the end of the combustion stroke, before the piston reaches bottom dead center, and closes at time t, when the exhaust stroke ends and the piston passes past top dead center and enters the intake stroke. In addition, the scavenging pulp 4 is generated at the end of the exhaust stroke, at time t before the piston reaches the top dead center, when the VC is opened, and at the time 1 when the intake stroke ends and the piston passes the bottom dead center and enters the compression stroke.
[close.

Further, the mixture valve 2 opens at time t, simultaneously with the closing of the exhaust valve 3, and closes together with the scavenging pulp 4 at time t.

Next, a description will be given of the air-fuel mixture supply method of the present invention, which is carried out by the air-fuel mixture supply apparatus configured as described above.

The air is supplied to a compressor 8 of a supercharger 9 operated by exhaust gas.
After being compressed by the cooler 10, the vaporizer 1
4, which is combined with the fuel gas sent to the carburetor 14 through the gas regulator 13, becomes a mixed gas with a predetermined air-fuel ratio, passes through the air-fuel mixture manifold 5, and enters the cylinder 1 from the air-fuel mixture valve 2. is inhaled. As described above, the time when the mixture valve 2 opens is the time t when the piston passes the top dead center and enters the intake stroke and the exhaust pulp 3 is closed. Shortly before the mixture pulp 2 opens and the mixture enters the cylinder l, that is, before the piston on the exhaust stroke reaches top dead center, the scavenging valve 4 is opened and the cooler 10
A part of the cooled air is sent into the cylinder 1 through the air manifold 7, and at the same time, the combustion gas remaining in the cylinder is completely scavenged out of the cylinder, and at the same time, parts facing the combustion chamber such as the piston are to cool down.

After the intake stroke ends and the compression stroke begins, and the piston passes the bottom dead center, the mixture valve 2 and the scavenging valve 4 are closed simultaneously, but the ratio of the mixture and air sent into the cylinder l, that is, 1, The final air-fuel ratio is obtained by adjusting the gas regulator 13 and adjusting the air-fuel mixture amount at a predetermined air-fuel ratio in the carburetor 14 and adjusting the openings of the air volume adjustment valve 17 and the scavenging volume adjustment valve 18. It is determined by the ratio to the amount of air.

After the compression stroke, the combustion stroke begins, and the exhaust valve 3 opens at a time t1 before the combustion stroke reaches the end and the piston reaches the bottom dead center, and exhaust begins. As already explained, the scavenging valve 4 is opened before the end of the exhaust stroke, and the exhaust valve 3 is closed after entering the intake stroke, thus completing the cycle.

In the above, the mixture valve 2 is opened at the same time as the exhaust pulp 3 closes, but even if the mixture valve 2 is opened a short time after the exhaust pulp 3 is closed, good. Furthermore, although the air-fuel mixture valve 2 and the scavenging valve 4 are configured to close at the same time, one of the valves 2 (4) closes near the bottom dead center of the piston, and the other valve 4 (2) closes near the bottom dead center of the piston. It is also possible to implement the present invention by closing it earlier than that. When the air volume adjustment valve 17 and the scavenging volume adjustment valve 18 are completely closed,
The gas engine shown in the figure operates as a continuous feed type gas engine with a carburetor.

On the other hand, if the air-fuel ratio of the air-fuel mixture obtained by the carburetor 14 is made extremely small (high gas concentration), the characteristics will approach those of a timing supply type gas engine.

Further, in the figure, the air volume adjusting pulp 17 is connected to the governor 19 at an appropriate link lever ratio, and an appropriate amount of air after passing through the compressor 8 is circulated in response to the movement of the governor. Therefore, the amount of air passing through the compressor 8 becomes larger than the amount of air sucked into the engine, and the surge margin of the supercharger 9 becomes larger. Particularly when the engine load is cut off, the mixture volume adjustment valve 16 of the carburetor 14 is close to fully closed, and the closed air pressure in the air pipe 11 rises rapidly, causing surging, but in this case, the above-mentioned By increasing the opening degree of the air volume adjustment valve 17 and increasing the circulating air volume, it is possible to suppress the occurrence of surging.

As explained above, in the present invention, before the end of the exhaust stroke, the scavenging valve is opened to completely scavenge the combustion gas remaining in the cylinder, at the same time the combustion chamber is cooled, and the exhaust pulp is closed. Since the air-fuel mixture is supplied to the button inside the cylinder, it is possible to prevent the air-fuel mixture from blowing through, and
It is possible to reduce the heat load on pistons, etc. and improve exhaust gas characteristics. In addition, the mixing ratio can be easily adjusted over a wide range, an extremely lean mixture can be easily created, and the occurrence of surging during load shedding operation can be suppressed.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram of a gas engine to explain the mixture supply method of the present invention, FIG. 2 is a schematic diagram showing the relationship between the carburetor, mixture manifold, air manifold, etc. in FIG. 1, and FIG. FIG. 3 is a process diagram showing an example of timing of opening and closing of a mixture pulp, an exhaust pulp, and a scavenging valve. 1...Cylinder, 2...Mixture valve, 3...Exhaust valve, 4...Scavenging valve, TDC...Top dead center , BDC...Bottom dead center. Figure 1

Claims (1)

[Claims] Just before the end of the exhaust stroke near the top dead center of the piston,
The scavenging valve is opened to let air into the cylinder to scavenge the combustion gas, and almost at the same time as the exhaust valve is closed, the mixture valve is opened to supply the mixture into the cylinder, and either the scavenging valve or the mixture valve is A method for supplying a mixture to a gas engine, characterized in that one valve is closed near the bottom dead center of the piston, and the other valve is closed at the same time as or before the one valve.