JPH06299906A - Fuel injection device of natural gas engine - Google Patents

Abstract

PURPOSE:To simplify the structure of a fuel injection device of natural gas engine, reduce the manufacturing cost, reduce blow-out of natural gas, reduce the discharge amount of total hydrocarbon (THC) so as to improve fuel effi ciency, and reduce the supply of natural gas into a gas engine at the time of deceleration and low load of the gas engine. CONSTITUTION:A scavenging passage 4 which supplies air into a gas engine 2 is provided, and a venturi section 32 is provided in the upstream of the scavenging passage 4 to make the venturi section 32 communicate with a fuel supply section 30 so that the fuel supply section 30 is operated in accordance with the flow rate of air which passes the venturi section 32. Also, the venturi section and the fuel supply section are provided in such a way that they communicate with each other and the venturi section and a regulator are provided in such a way that they communicate with each other so that the fuel supply section and the regulator are operated in accordance with the flow rate of air which passes the venturi section provided in the upstream of the scavenging passage.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fuel injection device for a natural gas engine, and more particularly to a fuel injection device for a natural gas engine that supplies the gas engine with natural gas as a fuel.

[0002]

2. Description of the Related Art Gasoline, light oil, etc. are mainly used as fuel for an internal combustion engine mounted on a vehicle or the like. Recently, a gas engine using natural gas such as LNG (liquefied natural gas) as fuel. Is proposed. Gas engine
Natural gas, which is the fuel, is supplied by the fuel supply device.

As a fuel supply device for an LP gas engine, as disclosed in Japanese Patent Application Laid-Open No. 2-70966, it is arranged in a slow fuel passage connecting a primary decompression chamber of a vaporizer and a mixer, and the slow fuel passage is electrically disconnected. There is a switch provided with a voltage switching means that short-circuits the solenoid valve and the power source at the time of engine startup and connects them via a resistor after engine startup based on the output signal of the solenoid valve and the starter switch.

Further, as a fuel supply device for a liquefied gas engine, as disclosed in Japanese Patent Laid-Open No. 2-149756, a liquid-phase gas fuel is supplied in the middle of a fuel supply pipe from a fuel tank to a liquefied gas engine. In a fuel supply system for a liquefied gas engine having a vaporizer for depressurizing vaporization, a backflow blocking means for blocking backflow of liquid-phase gas fuel to a fuel tank is provided in a fuel supply pipe upstream of the vaporizer, and a fuel supply pipe downstream of the vaporizer. In some of them, a volume expansion absorbing means for absorbing the volume expansion of the gas fuel is provided.

Furthermore, the fuel tank of the natural gas engine is
As shown in FIG. 6, natural gas such as LNG, CNG, and LPG is stored, and is connected to a downstream portion of the scavenging passage 104 via a fuel pipe 120.

In the middle of the fuel pipe 120, the fuel tank 108
In order from the side, the manual shutoff valve 190 and the pressure reducing valve 192
A filter 194, a solenoid valve 122, a regulator 124 for adjusting the pressure of natural gas, a chamber 126,
The fuel supply unit 130 is interposed.

The fuel supply unit 130 has a structure for supplying the scavenging passage 104 with an amount of natural gas corresponding to the operating state of the gas engine 102.

The fuel supply unit 130 includes a main body 196.
And a piston valve body 198 that reciprocates in the cylinder 196A of the main body portion 196, presses the piston valve body 198, and:
It has a cam 200 that is driven at a ratio of 1 and a spring 148 that biases the piston valve element 198 toward the cam 200.

A fuel supply passage 136 communicating with the fuel pipe 120 is formed in the fuel supply unit 130.

The fuel supply passage 136 has a main body portion 196.
A first fuel supply passage 136-1 extending from the outer circumference to the piston valve body 198, and a second fuel supply passage 136-2 extending from the outer circumference of the piston valve body 198 to a central portion and then extending downward to a portion where the spring 148 is disposed. , The third fuel supply passage 1 communicating with the injection nozzle 118 from this location
36-3.

The piston valve body 198 is shown in FIG.
As shown in FIG. 7B, the lever 204 is connected and the inlet side inlet portion 1 of the second fuel supply passage 136-2 is connected.
36A-2 is formed in a long hole having a different cross-sectional area and inclined, and the lever 204 is configured to rotate in conjunction with an accelerator (not shown).

[0012]

By the way, in a conventional spark ignition type two-cycle engine, a blow-through of fuel generally occurs, and a large amount of total hydrocarbon (THC) is emitted, resulting in deterioration of fuel efficiency. However, there is a disadvantage that it is economically disadvantageous.

Further, white smoke is emitted from the tail pipe of the two-cycle engine to which the liquid fuel is supplied, which may cause air pollution and irregular combustion peculiar to the two-cycle engine, which is a practical disadvantage. There is an inconvenience that

Further, as shown in FIG. 6, the above-described gas engine requires a cam mechanism to operate the fuel supply unit 130, which complicates the structure of the fuel supply unit 130, which is a practical disadvantage. In addition, there is a risk of increasing the manufacturing cost, which is an economical disadvantage.

[0015]

Therefore, in order to eliminate the above-mentioned inconvenience, the present invention provides a regulator, an injection valve, and a fuel supply unit in the middle of a fuel passage connecting a fuel tank storing natural gas and a gas engine. In a fuel injection device for a two-cycle natural gas engine in which is sequentially arranged, a scavenging passage for supplying air is provided in the gas engine, a venturi portion is provided at an upstream portion of the scavenging passage, and an air flow rate passing through the venturi portion. The venturi portion and the fuel supply portion are provided so as to communicate with each other to operate the fuel supply portion according to the above. Further, in a fuel injection device of a two-cycle natural gas engine in which a regulator, an injection valve and a fuel supply unit are sequentially arranged in the middle of a fuel passage connecting a fuel tank for storing natural gas and the gas engine, A scavenging passage for supplying air is provided, a venturi portion is provided at an upstream portion of the scavenging passage, and the venturi portion and the fuel supply portion are connected to operate the fuel supply portion and the regulator in accordance with the flow rate of air passing through the venturi portion. It is characterized in that the venturi portion and the regulator are provided in communication with each other.

[0016]

According to the invention as described above, when the gas engine is driven, the fuel supply section is operated according to the flow rate of the air passing through the venturi section provided in the upstream portion of the scavenging passage,
A certain amount of natural gas is supplied to the gas engine side.

Further, when the gas engine is driven, the fuel supply section and the regulator are operated according to the flow rate of the air passing through the venturi section provided in the upstream portion of the scavenging passage to supply a predetermined amount of natural gas to the gas engine side. is doing.

[0018]

Embodiments of the present invention will be described in detail below with reference to the drawings.

1 to 4 show a first embodiment of the present invention. In FIG. 1, 2 is a gas engine consisting of a spark ignition type two-cycle engine, 4 is a scavenging passage, 6 is a piston, and 8 is a fuel tank for natural gas.

The scavenging passage 4 supplies air to the crank chamber 10
To the crank chamber 10
And a second scavenging passage 4-2 connecting the combustion chamber 12 and the combustion chamber 12. A reed valve 14 and an air valve 16 are arranged in the first scavenging passage 4-1 from the downstream side, and a fuel injection nozzle 18 is arranged in the downstream side of the second scavenging passage 4-2. ing.

The fuel tank 8 is, as shown in FIG.
Natural gas such as LNG, CNG, and LPG is stored, and is provided so as to communicate with the second scavenging passage 4-2 through the fuel pipe 20, and the above-mentioned portion is joined to the second scavenging passage 4-2. As described above, the fuel injection nozzle 18 is arranged.

In the middle of the fuel pipe 20, an electromagnetic valve 22, a regulator 24 for adjusting the pressure of natural gas, a chamber 26, an injection valve 28, and a fuel supply section 30 are sequentially installed from the fuel tank 8 side. Is installed.

A venturi portion 32 is provided upstream of the first scavenging passage 4-1 and the venturi portion 32 and the fuel supply portion 30 are operated to operate the fuel supply portion 30 in accordance with the flow rate of air passing through the venturi portion 32. I have contacted and established.

More specifically, the venturi portion 32 is disposed upstream of the air valve 16 disposed in the first scavenging passage 4-1. The venturi portion 32 is provided with a venturi-side connection portion 34.

Further, a fuel supply passage 36 communicating with the fuel pipe 20 is provided in the fuel supply section 20. A needle valve element 38 that is moved forward and backward by a diaphragm mechanism 40, which will be described later, is disposed in the middle of the fuel supply passage 36. The needle valve element 38 appears and disappears in the middle of the fuel supply passage 36, and changes the passage area of the fuel supply passage 36.

Furthermore, the diaphragm mechanism 40 is
A diaphragm 46 that defines the interior into a pressure chamber 42 and a negative pressure chamber 44, the needle valve element 38 having one end connected to the diaphragm 46 and the other end protruding and retracting in the middle of the fuel supply passage 36, and a needle. And a spring 48 for urging the valve body 38 in the retracted direction. A diaphragm-side connecting portion 50 is formed in the negative pressure chamber 44. The diaphragm-side connecting portion 50 and the venturi-side connecting portion 34 of the venturi portion 32 are connected by a negative pressure supply pipe 52.

Further, the fuel injection amount per one revolution of the crankshaft 54 differs depending on the throttle opening and the number of revolutions, and must be injected in accordance with the intake ratio. The injection amount is determined by the time area and pressure. As shown in FIG. 2, the valve opening time becomes shorter as the engine speed increases.
Needle-shaped valve element 38 according to the required flow rate for maximum output rotation of OT
Thus, the fuel supply passage 36 is narrowed, and the air-fuel ratio is matched with changes in engine speed and throttle opening.

Further, as shown in FIG. 3, the negative pressure generated in the venturi portion 32 is substantially proportional to the air flow rate (intake air amount) passing through the first scavenging passage 4-1. The diaphragm mechanism is operated by the negative pressure, the passage area of the fuel supply passage 36 is set to a predetermined size by the needle valve element 38, and fuel corresponding to the air flow rate is supplied to the gas engine side.

Furthermore, the negative pressure generated in the venturi portion 32 is expressed by the following equation. PX = (WA / FA · αA · εA) ² / 2gρA PX: Venturi negative pressure WA: Air weight, FA: Venturi αA: Shrinkage coefficient, εA: Air flow coefficient 2gρA: Specific gravity of air

The diaphragm driving force is expressed by the following equation. FX = A ・ PX FX: Diaphragm driving force A: Constant

Further, the spring reaction force is expressed by the following equation. SX = μ ・ X + SO SX: Spring reaction force μ: Spring constant X: Displacement amount SO: Set pressure (spring)

Furthermore, the crankshaft 5 of the gas engine 2
4, an opening / closing mechanism 56 for the injection valve 28 is arranged. The opening / closing mechanism 56 includes a notch portion 58 formed in the crankshaft 54, a switch portion 60 that opens and closes when the crankshaft 54 rotates, and an opening / closing mechanism spring that biases the switch portion 60 in a direction in which the contact A is closed. 62, and is connected to the injection valve 28 via a battery 64.

4 (a), 4 (b) and 4
(C) is a pressure waveform in the crank chamber at a predetermined engine speed of the gas engine 2.

Next, the operation will be described.

The gas engine 2 is driven to drive the crankshaft 54.
Rotation of the crankshaft 54 causes the opening / closing mechanism 5 to rotate.
6 is operated, and the injection valve 28 is opened / closed by the opening / closing mechanism 56.

Further, the negative pressure generated in the venturi portion 32 provided in the upstream portion of the first scavenging passage 4-1 is supplied to the negative pressure chamber 44 of the diaphragm mechanism 40 and resists the urging force of the spring 48 to form a needle shape. The valve body 38 is sucked, the passage cross-sectional area of the fuel supply passage 36 of the fuel supply portion 30 is changed, and a predetermined amount of natural gas corresponding to the flow rate of air passing through the venturi portion 32 is supplied to the gas engine 2 side. There is.

As a result, the structure of the fuel supply unit 30 can be simplified by omitting the cam mechanism that operates the fuel supply unit in the conventional fuel supply device, and the manufacturing cost of the fuel injection device can be reduced, which is economical. Is advantageous.

Further, since the venturi portion 32 and the fuel supply portion 30 are connected by the negative pressure supply pipe 52 so as to operate the fuel supply portion 30 according to the flow rate of the air passing through the venturi portion 32, the natural gas is provided. Of the total hydrocarbon (THC) can be reduced, the fuel consumption can be improved, and it is economically advantageous.

Further, by supplying the natural gas to the gas engine 2, there is no fear that the natural gas in the crank chamber 10 will stay, and it is possible to prevent the white smoke from the tail pipe (not shown). Moreover, there is no fear of causing air pollution and pollution, and the use of natural gas is advantageous for lean combustion, and it is possible to prevent irregular combustion peculiar to a two-cycle engine, which is practically advantageous.

FIG. 5 shows a second embodiment of the present invention. In the second embodiment, the parts having the same functions as those of the first embodiment will be described with the same reference numerals.

The feature of this second embodiment is that a venturi portion 32 is provided upstream of the scavenging passage 4 and the fuel supply portion 30 and the regulator 24 are operated in accordance with the flow rate of air passing through the venturi portion 32. Venturi part 32
And the fuel supply section 30 are provided in communication with each other, and the venturi section 32 and the regulator 24 are provided in communication with each other.

That is, a venturi portion 32 is provided at an upstream portion of the scavenging passage 4, for example, an upstream portion of the air valve 16 disposed in the scavenging passage 4, and the venturi portion 32 has first and second venturi-side connecting portions 34-. 1, 34-2 are provided.

The first venturi side connecting portion 34-1 is
The first negative pressure supply pipe 5 is connected to the diaphragm-side connection portion 50 provided in the diaphragm mechanism 40 that operates the fuel supply portion 30.
2-1.

The second Venturi-side connecting portion 34-2 is
A second negative pressure supply pipe 52-2 communicates with the regulator-side connecting portion 72 provided on the regulator 24.

The regulator 24 includes a regulator diaphragm 74 and a regulator fuel passage 76.
And a negative pressure chamber 78 for the regulator. The regulator-side connecting portion 72 includes the negative pressure chamber 7 for the regulator.
It communicates with 8. In the regulator negative pressure chamber 78, a regulator spring 80 for urging the regulator diaphragm 74 against negative pressure is arranged. An opening / closing member 84 is connected to the regulator diaphragm 74 via a U-shaped connecting member 82. The opening / closing member 84 opens / closes the regulator fuel passage 76 by negative pressure.

Then, as in the first embodiment described above,
It is possible to reduce blow-through of natural gas, reduce the amount of total hydrocarbon (THC) emission, improve fuel efficiency, and be economically advantageous.

The venturi section 32 and the fuel supply section 30 are provided so as to communicate with each other so as to operate the fuel supply section 30 in accordance with the flow rate of the air passing through the venturi section 32.
By providing the venturi portion 32 and the regulator 24 in communication with each other, the regulator 24 that operates by negative pressure
The amount of natural gas can be adjusted with, and the supply of natural gas to the gas engine 2 can be reduced when the gas engine 2 is decelerated or when the load is low, which is practically advantageous.

Further, by supplying the natural gas to the gas engine 2, there is no fear that the natural gas stays in the crank chamber, and it is possible to prevent the white smoke from being emitted from the tail pipe and cause air pollution. With no fear,
The use of natural gas is advantageous for lean combustion, and can prevent irregular combustion peculiar to a two-cycle engine, which is practically advantageous.

The present invention is not limited to the first and second embodiments described above, and various application modifications are possible.

For example, in the first embodiment of the present invention, the opening / closing mechanism has a notch portion formed on the crankshaft, a switch portion for opening and closing by rotation of the crankshaft, and a contact portion for closing the switch portion in the direction of closing. The opening / closing mechanism is formed by the spring for the opening / closing mechanism, but the opening / closing mechanism may be configured by providing the crankshaft with a cam for setting the opening / closing timing of the solenoid valve. Further, the opening / closing mechanism can be configured by providing a notch portion or a cam for setting the opening / closing timing of the solenoid valve on the crank web.

In the first and second embodiments of the present invention, the fuel injection device for a two-cycle engine is used. However, if the scavenging passage communicating with the combustion chamber of the engine is replaced by an intake passage, a four-cycle engine is used. It can also be used as a fuel injection device.

[0052]

As described in detail above, according to the present invention, a scavenging passage for supplying air is provided in the gas engine,
Since the venturi portion is provided in the upstream part of the scavenging passage and the venturi portion and the fuel supply portion are connected to each other to operate the fuel supply portion according to the flow rate of the air passing through the venturi portion,
Compared with the conventional one, the structure can be simplified, the manufacturing cost can be reduced, it is economically advantageous, the blow-through of natural gas can be reduced, and the total hydrocarbon (THC) emissions can be reduced. It is possible to reduce the fuel consumption, the fuel efficiency is improved, and it is economically advantageous. Further, since the natural gas is supplied to the combustion chamber side of the gas engine, the natural gas is not supplied to the crank chamber, there is no fear that the natural gas will stay in the crank chamber, and white smoke is emitted from the tail pipe. It is possible to prevent malfunctions and not to cause pollution of air pollution, and to use natural gas, which is advantageous for lean combustion, and can prevent irregular combustion peculiar to a two-cycle engine, which is practically advantageous.

Further, a scavenging passage for supplying air is provided in the gas engine, a venturi portion is provided at an upstream portion of the scavenging passage, and the venturi portion is operated to operate the fuel supply portion and the regulator in accordance with the flow rate of the air passing through the venturi portion. Since the venturi part and the regulator are provided in communication with each other and the fuel supply part is provided in communication with each other, the blow-through of natural gas can be reduced and the total hydrocarbon (THC) emission amount can be reduced. Fuel economy is good,
In addition to being economically advantageous, the supply of natural gas to the gas engine can be reduced when the gas engine decelerates or when the load is low, which is practically advantageous. Further, since the natural gas is supplied to the combustion chamber side of the gas engine, the natural gas is not supplied to the crank chamber, there is no fear that the natural gas will stay in the crank chamber, and white smoke is emitted from the tail pipe. It is possible to prevent malfunctions and there is no fear of causing air pollution.
By using natural gas, lean combustion is advantageous, and irregular combustion peculiar to a two-cycle engine can be prevented,
It is practically advantageous.

[Brief description of drawings]

FIG. 1 is an enlarged cross-sectional view of a fuel injection device for a natural gas engine showing a first embodiment of the present invention.

FIG. 2 is a diagram showing a relationship between an engine speed and a time required for one crankshaft rotation.

FIG. 3 is a diagram showing a relationship between an intake air amount and a Venturi negative pressure.

FIG. 4A is a diagram showing a pressure waveform in the crank chamber at 2000 rpm (WOT). (B) It is a figure which shows the pressure waveform of the crank chamber at 4000 rpm (WOT). (C) It is a figure which shows the pressure waveform of the crank chamber at 6000 rpm (WOT).

FIG. 5 is an enlarged cross-sectional view of a fuel injection device for a natural gas engine showing a second embodiment of the present invention.

FIG. 6 is an enlarged cross-sectional view of a fuel injection device for a natural gas engine showing a conventional technique of the present invention.

FIG. 7A is a plan view of a piston valve body and a lever. (B) It is a side view of a piston valve body.

[Explanation of symbols]

 2 Gas Engine 4 Scavenging Passage 6 Piston 8 Natural Gas Fuel Tank 10 Crank Chamber 12 Combustion Chamber 14 Reed Valve 16 Air Valve 18 Fuel Injection Nozzle 20 Fuel Pipe 24 Regulator 28 Injection Valve 30 Fuel Supply Part 32 Venturi Part 36 Fuel Supply Passage 40 Diaphragm mechanism 52 Negative pressure supply pipe

Claims (2)

[Claims] 1. A fuel injection device for a two-cycle natural gas engine, in which a regulator, an injection valve, and a fuel supply section are sequentially arranged in the middle of a fuel passage connecting a fuel tank for storing natural gas and a gas engine, A scavenging passage for supplying air is provided in the gas engine, a venturi portion is provided at an upstream portion of the scavenging passage, and the venturi portion and the fuel supply portion are operated to operate the fuel supply portion according to an air flow rate passing through the venturi portion. A fuel injection device for a natural gas engine, wherein 2. A fuel injection device for a two-cycle natural gas engine, in which a regulator, an injection valve, and a fuel supply unit are sequentially arranged in the middle of a fuel passage connecting a fuel tank for storing natural gas and a gas engine, A scavenging passage for supplying air is provided in the gas engine, a venturi portion is provided at an upstream portion of the scavenging passage, and the venturi portion and the fuel supply are operated to operate the fuel supply portion and the regulator in accordance with the flow rate of air passing through the venturi portion. A fuel injection device for a natural gas engine, wherein the venturi portion and the regulator are provided in communication with each other.