JPH0223811Y2 - - Google Patents

Description

[Detailed Description of the Invention] (Field of Industrial Application) The present invention relates to an air-fuel ratio correction device for a gas engine that prevents the gas engine from misfiring when the load suddenly increases.

(Prior art and its problems) For gas engines, a so-called mixer system is known in which gas fuel and air are mixed in advance and the mixture is increased or decreased. To achieve this, it is necessary to widen the overlap between the intake and exhaust valves to scavenge residual gas and lower the combustion chamber temperature.

However, if residual gas is scavenged using the mixer method, the air-fuel mixture will blow through, resulting in a decrease in thermal efficiency.

Therefore, the present applicant has developed a system for separately supplying gas fuel and air using two throttle valves, and has already filed an application for this system.

As shown in FIG. 3, this throttle valve system includes a gas passage 12 and an air passage 14 connected to the intake port 10, a gas throttle valve 16 in the gas passage 12, and an air throttle valve 18 in the air passage 14. is provided. This air passage 14 is connected to an exhaust turbocharger (not shown). 20
is the governor.

The gas pressure in the gas passage 12 is controlled by a diaphragm-type gas regulator 22, and the gas regulator 22 is connected to a feedback pipe 24, a supercharging air pressure pipe 26, an intake port pressure pipe 28, etc.
A supercharging correction chamber 30 is provided. 32 is a pressure regulating bolt, 34 is a boost pressure regulating valve, and 36 is a valve that defines gas supply timing.

In such a gas engine, during normal steady operation, the pressure at each part is as shown in the boost pressure characteristic Pc, gas pressure characteristic Pg, and intake port pressure Pi in Figure 4, which is a graph of load PS - pressure P at each part. I'm getting used to it, but
When the load suddenly increases, as shown in Figure 5, the time
After the load suddenly increases at t1, the intake port pressure characteristic Pi1 becomes higher pressure than the gas pressure characteristic Pg1, and even if the gas throttle valve 16 is opened, gas does not flow into the intake port 10 from the gas passage 12, and from time t1 to There is a problem that a misfire occurs during time t2.

Therefore, the load response of the engine deteriorates, and when a gas engine is used for the generator, the frequency characteristics deteriorate.

Additionally, unignited gaseous fuel may be discharged from the exhaust pipe, potentially causing a flue explosion.

(Purpose of the invention) The present invention aims to provide an air-fuel ratio correction device for a gas engine that can prevent misfires in a supercharged gas engine having a gas amount control valve and an air amount control valve in the event of a sudden increase in load. The purpose is

(Structure of the device) (1) Technical means The device includes an air flow control valve in the air passage upstream of the intake port, and a gas flow control valve in the gas passage communicating between the air flow control valve and the intake port. In a supercharged gas engine, a main gas regulator for controlling the gas pressure supplied to the engine is provided in the gas passage upstream of the gas amount control valve, and a sub-gas regulator is provided in parallel with the main gas regulator to control the outlet gas of the main gas regulator. This is an air-fuel ratio correction device for a gas engine, characterized in that gas is supplied from the auxiliary gas regulator only when the load suddenly increases when the intake port pressure becomes higher than the air pressure.

(2) Effect When the load increases in the auxiliary gas regulator where the intake port pressure becomes higher than the outlet gas pressure of the main gas regulator, gas fuel is supplied and the gas pressure is increased to increase the supply of gas fuel and prevent misfires.

(Example) In FIG. 1 showing a gas engine employing the present invention, parts given the same reference numerals as those in FIG. 3 indicate the same or equivalent parts.

In FIG. 1, the valve body 40 of the main gas regulator 22
A bypass passage 42 is provided in parallel with the gas passage 12, which communicates the upstream side and the downstream side of the gas passage 12 with the gas passage 12 in between. An auxiliary gas regulator 44, which is the gist of the present invention, is interposed in the middle of this bypass passage 42, and a valve body 46 of the auxiliary gas regulator 44 is provided.
The opening/closing of the bypass passage 42 is controlled by the opening and closing of the bypass passage 42. The valve body 46 is connected to a diaphragm 48, and the diaphragm 48 is urged in the valve closing direction by a coil spring 50.

A passage 54 is provided that communicates the lower chamber 52 of the auxiliary gas regulator 44 with the intake port 10 downstream of the air throttle valve 18. Also, upper chamber 5
6 and the gas passage 12 upstream of the gas throttle valve 16 are provided.

Next, the action will be explained. In the embodiment shown in FIG. 1, when the load suddenly increases, the gas throttle valve 16 and the air throttle valve 18 are fully opened, and the intake port 10 is fully opened.
The pressure after time t1 is the boost pressure characteristic Pc1 (Fig. 2)
rises to .

The pressure in the intake port 10 is introduced into the lower chamber 52 of the auxiliary gas regulator 44 through the passage 54, and the pressure in the lower chamber 52 becomes higher than that in the upper chamber 56. This pressure difference between the lower chamber 52 and the upper chamber 56 pushes up the diaphragm 48, opens the valve body 46, and gas fuel flows from the bypass passage 42 to the gas passage 12. Therefore, the pressure in the gas passage 12 rises rapidly as shown by the gas pressure characteristic Pg2 in FIG.

Since the gas pressure characteristic Pg2 has a steeper pressure rise than the conventional gas pressure characteristic Pg1 (Fig. 5),
The pressure increases to the same pressure as the intake port pressure characteristic Pi1 in a short period of time from time t1 to time t3, and gas fuel is supplied from the gas passage 12 to the intake port 10 after time t3.

Therefore, the engine misfire time is from time t1 to time t3
The load response of the engine is improved.

After time t3, the pressure in the upper chamber 56 becomes higher than that in the lower chamber 52, so the valve body 46 closes and the air-fuel ratio is controlled only by the gas fuel supplied from the main gas regulator 22.

Furthermore, when the engine is started with the throttle fully open, such as when starting the engine, no differential pressure is generated between the intake port 10 and the gas passage 12, and the auxiliary gas regulator 44 does not operate. Furthermore, when the load suddenly decreases, the pressure in the gas passage 12 is higher than that in the intake port 10, so the auxiliary gas regulator 44 does not operate, and the main gas regulator 22 operates as usual.
to control the air-fuel ratio.

Note that, although an electric control means can of course be used in place of the auxiliary gas regulator 44, a mechanical auxiliary gas regulator 44 is suitable in terms of response time.

(Effect of the invention) As explained above, the air-fuel ratio correction device for a gas engine according to the invention includes an air amount control valve (air throttle valve 18) in the air passage 14 upstream of the intake port 10, and an air amount control valve (air throttle valve 18). In a supercharged gas engine having a gas flow control valve (gas throttle valve 16) in the gas passage 12 communicating between the valve and the intake port 10, the gas is supplied to the engine in the gas passage 12 upstream of the gas flow control valve. A main gas regulator 22 is provided to control the gas pressure that is generated, and an auxiliary gas regulator 44 is provided in parallel with the main gas regulator 22. Only when the intake port pressure becomes higher than the outlet gas pressure of the main gas regulator 22 when the load suddenly increases, the auxiliary gas regulator 4 is activated.
4, the gas pressure characteristic Pg2 can be increased more rapidly than before, as shown in FIG. 2, and the misfire time can be shortened from time t1 to time t3.

Therefore, the load response of the engine is improved, and unignited gaseous fuel does not flow into the exhaust pipe, making it possible to prevent a flue explosion.

[Brief explanation of the drawing]

Fig. 1 is a structural diagram of a gas engine adopting the present invention, Fig. 2 is a pressure-time graph of each part, Fig. 3 is a structural diagram showing a conventional example, and Fig. 4 is a graph of the conventional example in a steady state. , FIG. 5 is a graph of a conventional example when the load suddenly increases. 10...Intake port, 12...Gas passage, 14
...Air passage, 16...Gas throttle valve, 1
8...Air throttle valve, 22...Main gas regulator, 44...Sub-gas regulator, 52...
...Lower chamber, 54...Aisle, 56...Upper chamber, 58...
aisle.

Claims (1)

[Scope of utility model registration request] In a supercharged gas engine that has an air flow control valve in the air passage upstream of the intake port, and a gas flow control valve in the gas passage communicating between the air flow control valve and the intake port, A main gas regulator is installed in the side gas passage to control the gas pressure supplied to the engine, and an auxiliary gas regulator is installed in parallel with the main gas regulator, and the auxiliary gas regulator is activated only when the load suddenly increases when the intake port pressure becomes higher than the outlet gas pressure of the main gas regulator. An air-fuel ratio correction device for a gas engine, characterized in that the air-fuel ratio correction device is configured such that gas is supplied from.