JPH0251066B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a method for igniting a spark plug using only gas fuel such as gasoline or methane gas.
The present invention relates to a control device for a cycle gas engine.

In such a gas engine, the intake valve and the exhaust valve are configured to have a uniquely determined mechanical interlock with each other by a cam connected to the crankshaft. Therefore, for example, when the load is light or when the calorific value changes depending on the composition of the gas fuel, the optimum air-fuel ratio cannot be freely achieved, and the combustion chamber becomes unstable, causing abnormally high temperature parts of the combustion chamber members. There was a drawback that this occurred. This also applies to two-stroke gas engines.

As a countermeasure to this problem, there is a method in which combustion air from the supercharger is discharged into the exhaust passage through a bypass path during light loads, thereby obtaining an optimal air-fuel ratio. However, discharging air from the supercharger to the outside in this way wastes power.

The purpose of the present invention is to eliminate these problems of the prior art, and to provide a control device for a four-cycle gas engine that efficiently achieves an optimal air-fuel ratio in order to reduce fuel consumption. It is to be.

In addition, in conventional gas engines, the compression ratio is set to a small value in gas engines that use gas fuel that is prone to knocking, and this compression ratio changes depending on the type of gas fuel, that is, the difference in knocking characteristics. The configuration is such that it is not possible to do so. Therefore, when using various gas fuels with different knocking characteristics, it is not possible to achieve an appropriate compression ratio, making knocking more likely to occur, resulting in poor combustion conditions and reduced output.

An object of the present invention is to make it possible to use various gas fuels with different knocking characteristics.
An object of the present invention is to provide a control device for a cycle gas engine.

The present invention provides control of a four-cycle gas engine that guides a mixture of gas fuel and combustion air into a combustion chamber 3 through an intake valve, and exhausts combustion gas from the combustion chamber 3 through an exhaust valve 8. In the device, the exhaust valve 8 includes an exhaust valve spring 23 that biases the valve body 22 of the exhaust valve 8 in a direction to close it, and an exhaust valve double-acting cylinder 24 that drives the exhaust valve valve body 22. A two-position switching solenoid valve 25 for the exhaust valve is provided, and the exhaust valve double-acting cylinder 24 is provided with a two-position switching solenoid valve 25 for selectively supplying pressure oil. An air supply valve 2 which has a double-acting air supply valve spring and an air supply valve double-acting cylinder that drives an air supply valve valve body, and switches and supplies pressure oil to the air supply valve double-acting cylinder. A supercharger 10 is provided, which includes a position switching solenoid valve, a turbine 26 driven by combustion gas from the exhaust valve 8, and a blower 11 driven by the turbine 26. Combustion air is force-fed to the air intake valve 7 by the blower 11 of 10, and the two-position switching solenoid valve 25 for the exhaust valve and the two-position switching solenoid valve 2 for the air intake valve are
The position switching solenoid valve is defined by the processing circuit 29.
When the load is light or the calorific value of gas fuel is small,
This control device for a four-cycle gas engine is characterized in that it is controlled to increase an overlap period W1 during which an exhaust valve 8 and an intake valve 7 are simultaneously open.

FIG. 1 is an overall system diagram of a control device for a four-stroke engine according to an embodiment of the present invention. A mixture of gaseous fuel from a pipe 5 and combustion air from a flow path 6 is introduced into a combustion chamber 3 formed by a cylinder 1 and a piston 2 via an air intake valve 7. . Combustion gas from the combustion chamber 3 is exhausted from an exhaust valve 8 through a flow path 9. This combustion gas is guided from the flow path 9 to the turbine 26 of the supercharger 10, thereby driving the blower 11. Combustion air is forced into the flow path 6 by the blower 11 .

Figure 2 shows the operation of the exhaust valve.
The valve body 22 is urged in the valve closing direction by a spring 23. This valve body 22 is driven by a double-acting cylinder 24. Pressure oil from the pump 20 is supplied to the double-acting cylinder 24 via a solenoid valve 25 . Air supply valve 7 and gas valve 2 as a second on-off valve
8 also has a similar configuration to the exhaust valve 8. Solenoid valve 2
As is clear from FIG. 2, 5 is a 4-port 2-position switching solenoid valve. The solenoid valve 25 associated with the exhaust valve 8 and similar solenoid valves associated with the air supply valve 7 and gas valve 28 are controlled by signals from a processing circuit 29, including a microcomputer or the like. Pump 20 is driven by an electric motor.

FIG. 3 is a diagram for explaining the operation of the processing device 29 of the embodiment shown in FIG. 1. When the piston 2 moves from the bottom dead center to the top dead center, the gaseous fuel and combustion air in the combustion chamber 3 are compressed.
Near top dead center, the spark plug 40 ignites, causing an explosion. When the piston 2 reaches the bottom dead center and rises again, the exhaust valve 8 opens and the combustion gas is discharged into the flow path 9. Then the air supply valve 7 opens,
Combustion air from the flow path 6 is supplied to the combustion chamber 3 and exhaust gas is forced out of the combustion chamber 3. When the piston passes the top dead center, the gas valve 28 is opened, thereby supplying combustion air and gas fuel to the combustion chamber 3 via the air supply valve 7.

In the above-described embodiment, since pressure oil is supplied to the double-acting cylinder 24 for control, the solenoid valve 25 can be downsized and the valve body can be reliably controlled to open and close with a large force.

Due to the operation of the processing circuit 29, for example, when (a) the load is light or (b) the calorific value of the gas fuel via the gas valve 28 is small, the overlap period W1 (third (see figure).
At this time, combustion air supplied from the blower 11 of the supercharger 10 is always supplied to the flow path 6. Therefore, the combustion chamber 3 and the exhaust valve 8 can be sufficiently cooled by this combustion air, and when the exhaust valve 8 is opened, the exhaust gas in the combustion chamber 3 can be quickly exhausted by the combustion air. and achieve the optimal air-fuel ratio,
It becomes possible to maintain good driving conditions.

As described above, according to the present invention, in a four-cycle gas engine, the intake valve and the exhaust valve are controlled based on signals from the processing circuit, and therefore the intake valve and the exhaust valve are opened at the same time. The overlap period can be easily varied. Therefore, for example, when the load is light or the calorific value of gas fuel is small, the overlap period can be greatly controlled.
It is possible to prevent the occurrence of local abnormally high temperature areas near the combustion chamber. In addition, combustion air can be constantly supplied without being throttled, so the combustion chamber can be cooled, and the exhaust gas in the combustion chamber can be quickly released from the exhaust valve, allowing the optimum air-fuel ratio to be maintained. It is possible to achieve this and maintain good operating conditions.

In addition, in the present invention, the opening and closing timing of the intake valve can be changed in a 4-cycle gas engine, so
The compression ratio is varied and adjusted. Therefore, it is possible to achieve a good combustion state with gas fuels having different knocking characteristics without causing knocking, and it is possible to increase the output. Especially in a 4-cycle gas engine with a supercharger, when the engine load decreases or the calorific value of the gas fuel decreases,
Exhaust valve 8 supplied to turbine 26 of supercharger 10
The energy of the combustion gas from the exhaust valve 8 in the combustion chamber is reduced, and the amount of combustion air that is force-fed from the blower 11 driven by the turbine 26 to the intake valve 7 is significantly reduced. Localized abnormally high temperature areas, or hot spots, are likely to occur in areas such as areas. On the other hand, in such a case, it is necessary to reduce the amount of combustion air to maintain the air-fuel ratio at an appropriate value. In the present invention, in such an operating state of the engine,
automatically controlling the overlap period W1;
This solves two problems in a four-cycle gas engine: preventing the occurrence of locally abnormally high temperature parts in the combustion chamber exhaust valve 8, etc., and maintaining the air-fuel ratio at an appropriate value.

[Brief explanation of the drawing]

FIG. 1 is an overall system diagram of one embodiment of the present invention, FIG. 2 is a system diagram related to the exhaust valve 8, and FIG.
FIG. 3 is a diagram for explaining the operation of the embodiment shown in the figure. 3... Combustion chamber, 7... Air supply valve, 8... Exhaust valve,
10...Supercharger, 21, 25...Solenoid valve, 29...
...processing circuit, 40...spark plug.

Claims (1)

[Claims] 1. A four-cycle gas system in which a mixture of gas fuel and combustion air is introduced into the combustion chamber 3 through an intake valve, and combustion gas from the combustion chamber 3 is discharged through an exhaust valve 8. In the engine control device, the exhaust valve 8 includes an exhaust valve spring 23 that biases the valve body 22 of the exhaust valve 8 in a direction to close it, and an exhaust valve double-acting cylinder that drives the exhaust valve valve body 22. 24, and an exhaust valve two-position switching solenoid valve 25 that switches and supplies pressure oil to the exhaust valve double-acting cylinder 24, and the air supply valve 7 closes the valve body of the air supply valve 7. It has an air supply valve spring that double-acts in the direction of the air supply valve, and a double-acting cylinder for the air supply valve that drives the valve body for the air supply valve. A supercharger 10 is provided, which includes a two-position switching solenoid valve for the exhaust valve, a turbine 26 driven by combustion gas from the exhaust valve 8, and a blower 11 driven by the turbine 26. Combustion air is force-fed to the air intake valve 7 by the blower 11 of the supercharger 10, and a two-position switching solenoid valve 25 for the exhaust valve and a two-position switching solenoid valve 2 for the air intake valve are used.
The position switching solenoid valve is defined by the processing circuit 29.
When the load is light or the calorific value of gas fuel is small,
A control device for a four-cycle gas engine, characterized in that control is performed to increase an overlap period W1 during which an exhaust valve 8 and an intake valve 7 are simultaneously open.