JPS6123639Y2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an air-fuel gas supply system for a two-cycle gas fuel engine that uses, for example, city gas, vaporized LPG, or the like as fuel.

Conventionally, this type of device has a structure in which gas fuel whose pressure has been reduced to about atmospheric pressure by a pressure regulator is mixed with air via a gas mixer, and the speed is adjusted by opening and closing a throttle valve to adjust the flow rate of the mixture. There is. Therefore, the suction of air-fuel mixture useful for scavenging is insufficient due to the resistance of the throttle valve, which tends to reduce scavenging efficiency and output. Also, since the amount of fuel supplied varies depending on the negative pressure in the intake pipe,
Low speed operation such as idling or light load operation has the disadvantage that hunting is likely to occur.

In view of these circumstances, the present invention aims to eliminate the decrease in scavenging efficiency and output, increase fuel efficiency, and enable stable operation even at low speeds.

In order to achieve this objective, the present invention has an air supply passage and a fuel gas supply passage connected to the crank chamber in parallel and independent of each other, and the fuel gas supply passage connected in series from the side farthest from the crank chamber. A pressure regulator, a fuel cut valve, and a flow rate control valve are interposed, and the pressure receiving chamber of the fuel cut valve is communicated with the crank chamber, and the valve body of the fuel cut valve is elastically biased toward the valve closing side, and the pressure of the crank chamber is By opening the valve when the internal pressure has fallen below a predetermined value, a large amount of air useful for scavenging can flow into the crank chamber from the air supply path without encountering resistance from the throttle valve, and the pressure can be adjusted from the fuel gas supply path. The main feature is that the fuel gas, whose pressure has been stabilized in the chamber, flows into the crank chamber through a fuel cut valve and a flow rate control valve to form an air-fuel mixture within the crank chamber.

Hereinafter, embodiments of the present invention will be described based on the drawings.

FIG. 1 is a longitudinal cross-sectional rear view of a water-cooled two-stroke gas fuel engine, and reference numeral 1 generally indicates the engine body.

An air supply passage 3 is communicated with the crank chamber 2 of the engine body 1 via the lower half of the cylinder chamber 4, and a fuel gas supply passage 5 independent of the air supply passage 3 is communicated directly.

In the case of this example, the air supply path 3 is substantially constituted only by an intake port formed inside the wall of the engine body 1, and the air cleaner 6 is fixed in direct communication with the inlet of this intake port. It is free to change the design so that another intake pipe is interposed between the intake port and the air cleaner 6.

A pressure regulator 7, a fuel cut valve 14, and a flow rate control valve 8 are installed in series in the fuel gas supply path 5 in order from the one farthest from the crank chamber 2.

That is, fuel gas supplied from a gas fuel supply source (not shown) to the crank chamber 2 through the fuel gas supply path 5 is reduced to a predetermined pressure (for example, about atmospheric pressure) by the pressure regulator 7, and its flow rate is adjusted. It is necessary to adjust the amount of fuel by the flow control valve 8 so that the amount of fuel supplied is independent of the internal pressure of the crank chamber 2 and the air supply path 3.

Further, the cylinder chamber 4 and the crank chamber 2 are communicated with each other by a scavenging passage 31 formed inside the wall of the engine body 1 .

This scavenging passage 31 is formed by merging two passages 31a formed in the wall of the crank chamber 2 and two passages 31b formed in the flesh wall of the cylinder chamber 4. 31 is opened at the bottom of the crank chamber 2, and its terminal end is opened at the scavenging port 32.
It opens in the side wall 4a of the cylinder chamber 4.

The structure of the pressure regulator 7 is not particularly limited, and may be, for example, the same structure as a commercially available so-called zero governor.

As shown in FIG. 2, the flow rate control valve 8 includes a valve case 9 and a valve body 11 that connects and disconnects a gas passage 10 that extends through the valve case 9. The valve body 11 is connected to the gas passage 10
The valve case 9 is rotatably supported by the valve case 9 around an axis orthogonal to the valve case 9, and has a hole 12 through which a gas passage 10 is communicated. As shown in FIG. 3, the hole 12 is formed to be tapered in the downstream direction so that it is difficult for the reverse flow of the fuel gas or air-fuel mixture to pass through.

One end of the valve body 11 is made to protrude outside the valve case 9, and is connected to a speed setting device (not shown) via a lever 13.
and a governor device (not shown) that is linked thereto, so that a valve opening corresponding to the speed set by the speed setting device, fluctuations in the governor lever of the governor device, etc. can be obtained. Incidentally, FIG. 4a shows the open state of the flow control valve 8 during idling, and FIG. 4b shows the open state of the flow control valve 8 during load operation.

The fuel cut valve 14 is an on-off valve that uses the internal pressure of the crank chamber 2 as the pilot operating pressure, and as shown in FIG. diaphragm 18
Equipped with. A valve body 20 that approaches and separates from an annular valve seat 19 provided on the wall of the fuel gas chamber 17 is interlocked and connected to the diaphragm 18, and is closed by a valve closing spring 21 inserted into the pressure receiving chamber 16. When the internal pressure of the crank chamber 2 is equal to or higher than a predetermined value, the fuel gas supply path 5 is closed to reliably prevent wasteful outflow or backflow of fuel gas from the crank chamber 2. The pressure receiving chamber 16 is connected to the crank chamber 2 through a pilot passage 22, and in a negative pressure state where the internal pressure of the crank chamber 2 exceeds a predetermined value, the diaphragm 1
8 overcomes the valve closing spring 21 and closes the valve body 20 to the valve seat 19.
Float from the surface and open the valve. The fuel gas chamber 17 communicates with an inlet 24 through a passage 23 extending through the valve seat 19, and with the flow rate control valve 8 through an outlet 25 opening in the wall of the fuel gas chamber 17.

In this example, the valve case 9 of the flow control valve 8 and the valve case 15 of the fuel cut valve 14 are integrated, but these valve cases 9 and 15 may be formed separately.

In addition, in this example, the lubricating oil is stored in the reserve tank 26.
From there, the oil passes through an oil heating path 28 that passes through the cylinder wall portion 27 of the engine body 1, and is sent to the middle of the air supply path 3 by an oil pump 30 that is communicatively connected to the crankshaft 29. With this configuration, the temperature of the lubricating oil can be raised to a certain level while passing through the oil heating path 28, the viscosity of the lubricating oil can be averaged, and the oil supply amount can be stabilized. Therefore, there is an advantage that atomization of the lubricating oil in the air supply path 3 is promoted.

With this configuration, since the air supply path 3 is not equipped with anything that causes ventilation resistance such as a throttle valve, the air passing through the air supply path 3 is not subjected to ventilation resistance, and a large amount of air flows into the crank chamber 2. Supplied.

Further, since the pressure receiving chamber 16 of the fuel cut valve 14 installed in the fuel gas supply path 5 is communicated with the crank chamber 2, the fuel cut valve 14
The valve body 20 will be operated.

That is, when the engine is operating at low speed, the operation of the fuel cut valve 14 closely follows the rise and fall of the piston 33, and there is almost no delay in the timing of opening and closing of the fuel cut valve 14.
increases and the internal pressure of the crank chamber 2 is lower than a predetermined value, the flow rate of the fuel gas passing through the fuel gas supply path 5 opened by the fuel cut valve 14 is adjusted by the flow rate control valve 8, Sufficient fuel gas is supplied to the crank chamber 2 as required for low speed operation.

Therefore, sufficient fuel gas is supplied into the crank chamber 2, the concentration of the mixed gas increases, and the engine rotation becomes stable.

Furthermore, when the engine rotates at high speed, the operation of the fuel cut valve 14 cannot follow the rise and fall of the piston 33, causing a delay in the timing of opening and closing of the fuel cut valve 14. There will be less inflow.

Therefore, the concentration of the mixed gas becomes thinner during high-speed rotation, which is originally stable, and fuel efficiency improves.

Now, as mentioned above, in this invention, a large amount of air is sucked into the crank chamber from the air supply path without being subjected to resistance from the throttle valve, so the amount of scavenged air is large and the scavenging efficiency is increased. , high combustion efficiency and sufficient output can be obtained.

In addition, the pressure receiving chamber of the fuel cut valve installed in the fuel gas supply path is communicated with the crank chamber, and the fuel cut valve is opened when the internal pressure of the crank chamber is lower than a predetermined value. When the internal pressure of the fuel gas drops below a predetermined value, the fuel gas is adjusted to the pressure regulated by the pressure regulator and the flow rate is adjusted by the flow rate control valve, regardless of the internal pressure of the crank chamber or air supply path. can be supplied to the crank chamber.

Moreover, when the engine is rotating at low speed, sufficient fuel gas can be supplied to the crank chamber to increase the concentration of the mixed gas, so the engine rotation is stable and can be used during no-load or light-load operation. In the case of low-speed operation, hunting can be extremely effectively prevented.

Additionally, when the engine is operating at high speeds, the supply to the crank chamber can be reduced and the concentration of the mixed gas can be diluted, improving fuel efficiency when operating at high speeds where the rotation is already stable. can be done.

Moreover, the fuel gas and air are sufficiently mixed and disturbed in the crank chamber by the volume change caused by the rotational movement of the crankshaft and the reciprocating movement of the piston, and are further mixed while passing through the scavenging passage. The mixture of gas and air is uniformly mixed and supplied into the cylinder chamber. Therefore, the ignition performance of the air-fuel mixture in the cylinder chamber is good, and stable combustion is always possible, so stable operation can be performed even at low speeds.

Furthermore, there is the advantage that a gas mixer with a complicated structure can be omitted, the structure becomes simple, and it can be implemented at low cost.

[Brief explanation of the drawing]

The drawings show an embodiment of the present invention, and FIG. 1 shows a water-cooled 2
A longitudinal rear view of a cycle gas fuel engine, Figure 2 is an enlarged longitudinal rear view of the A arrow section, and Figure 3 is an enlarged longitudinal rear view of the A-pointed part.
Figure 4a is a cross-sectional view taken along the line B-B in the figure, Figure 4a is a view taken in the direction of arrow C in Figure 3 during idling, and Figure 4b is a cross-sectional view of the
Fig. C is a view in the direction of arrow C. 1...Engine body, 2...Crank chamber, 3...
...Air supply path, 5...Fuel gas supply path, 7...Pressure regulator, 8...Flow rate control valve.

Claims (1)

[Scope of utility model registration request] Air supply passage 3 to crank chamber 2 of engine body 1
and a fuel gas supply path 5 are connected to each other independently and in parallel, and the fuel gas supply path 5 has a pressure regulator 7, a fuel cut valve 14, and a flow rate control valve 8 arranged in series in order from the one furthest from the crank chamber 2. is installed to communicate the pressure receiving chamber 16 of the fuel cut valve 14 with the crank chamber 2,
The valve body 20 of the fuel cut valve 14 is elastically biased toward the valve closing side, and the valve opens when the internal pressure of the crank chamber 2 is lower than a predetermined value, and the side wall 4a of the cylinder chamber 4 is opened.
An air-fuel gas supply device for a two-cycle gas fuel engine, characterized in that a scavenging port 32 formed in the 2-cycle gas fuel engine communicates with a crank chamber 2 through a scavenging passage 31.