JP3254086B2 - Combustion device for two-cycle gasoline engine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a combustion apparatus for a two-stroke gasoline engine.

[0002]

2. Description of the Related Art FIG. 4 is an explanatory view of the configuration of a conventional example of a fuel injection and combustion apparatus in a cylinder of a small two-stroke gasoline engine.
FIG. 5 is an enlarged vertical sectional view around the cylinder head in FIG. 4, and FIG. 6 is a timing diagram for operation of the engine. Hereinafter, the configuration and operation of the combustion device of the engine will be described with reference to FIGS.

[0003] A combustion chamber 04b is formed in the cylinder head 04, and an electromagnetic fuel injection valve 05, an electromagnetic air injection valve 07, and a spark plug 011 are provided on the wall surface thereof. The outlet of the fuel injection valve 05 and the outlet of the air injection valve 07 form a merging passage portion 04a. The fuel injected from the fuel injection valve 05 is atomized by the air flow injected from the air injection valve 07 and injected into the combustion chamber 04b, and the piston 03 near the end of the compression stroke has a top dead center (TDC). At the time of reaching the vicinity, the air-fuel mixture is ignited and burned by spark discharge of the electrode portion of the ignition plug 011. This is a so-called air-assisted in-cylinder fuel injection combustion device.

As shown in FIG. 4, fuel is guided from a fuel tank 013, is pressurized to several kgf / cm ² by a fuel supply pump 014, and is supplied to a fuel pressure regulator 015.
And supplied to the rear fuel injection valve 05. The fuel injection valve 05 is an electromagnetic control valve controlled by the controller 017. The fuel injection valve 05 uses a crankshaft angle signal detected by a crank angle signal sensor 019 to determine the fuel injection timing,
The injection amount is controlled.

[0005] Air is guided from an air reservoir 012, adjusted to a pressure of several kgf / cm ² by an air pressure regulator 012a, and supplied to an air injection valve 07 from an air introduction pipe 012b. The air injection valve 07 is also an electromagnetic control valve controlled by the controller 017. Like the fuel injection valve 05, the air injection timing and injection amount are controlled by the crankshaft angle signal detected by the crank angle signal sensor 019. .

As shown in the timing diagram of FIG. 6, the injection timing of fuel and air is controlled by the controller 017 so as to be substantially the same, and the atomization of fuel is attempted. Even if the pressure in the cylinder 01 rises, the injection is terminated within a period in which the cylinder pressure is lower than the fuel supply pressure and the air supply pressure.

[0007]

The above-described prior art in-cylinder fuel injection and combustion system for a two-cycle gasoline engine has the following problems. A small two-stroke gasoline engine applied to a portable mower, chainsaw, etc., has a displacement of several tens of cc and a rotation speed of 10
Although there are cases where it exceeds 000 rpm, the fuel injection amount per injection is extremely small.

[0008] In the in-cylinder fuel injection device of such a class of engine, the electromagnetic fuel injection valve 0 described above is used.
In order to inject fuel with high accuracy every time from 5, it is necessary to make the nozzle hole diameter of the fuel injection valve 05 extremely small and to shorten the injection period as much as possible. However, actually, the fuel injection valve 05
Because of the high-speed response and the dimensional limitations of the nozzle hole diameter, the fuel injection pressure (supply pressure) is lowered to prolong the injection period to solve this problem.

For this reason, the atomization of the injected fuel is inferior and is hardly atomized, and is in a state close to a rod-shaped liquid column. Therefore, even if fuel is injected into the combustion chamber in such a state, good combustion cannot be expected, so that air is injected from the air injection valve 07 at substantially the same time as fuel injection to assist atomization of the fuel. Is the current situation.

[0010] However, small two-cycle gasoline engines are often used for portable applications such as agricultural mowers and chainsaws. In such a case, there is a problem that there is no air source for air injection. . In addition, since this class of engine is kept low in cost, it can be said that it is practically impossible to mount a small air compressor that uses a part of the driving power. Therefore, in a class of engines applied to portable mowers, chainsaws, etc., the fuel is injected into the cylinder without an air injection valve, which leads to deterioration of combustion and a large amount of unburned combustible components. The exhaust gas contained in is discharged.

The small-sized electromagnetic fuel injection valve, which is usually used, has a valve seat portion that opens inward, and the valve opening pressure is low in order to ensure high-speed response. The combustion gas from the valve seat portion of the injector reversely penetrates into the injector, causing damage to the injector.

An object of the present invention is to solve the above-mentioned problems and eliminate the need for mounting an air reservoir or an air compressor for air injection,
Good combustion has been realized, reducing the emission of unburned combustible components and improving fuel consumption efficiency, and preventing the reverse flow of the compressed air-fuel mixture and combustion gas into the fuel injection valve to improve engine durability. Another object of the present invention is to provide a combustion apparatus for a two-stroke gasoline engine that can achieve the following.

[0013]

According to a first aspect of the present invention, there is provided a combustion apparatus for a two-stroke gasoline engine, wherein a combustion is generated in a cylinder head (4) in an electromagnetic fuel injection valve (5) and a crankcase (2) in a two-stroke gasoline engine. air reservoir chamber for introducing compressed air to the (4a) provided, the air Kitamarishitsu (4
a) and a solenoid valve (7) for opening and closing between the combustion chamber (4b) and the solenoid valve (7) and the combustion chamber.
(4b) and a mixture throttle passage (4c) , and the electromagnetic mixture injection valve (5) is connected to the mixture throttle passage via an injection fuel passage (4d) fitted with a check valve (6). (4c) , and the electromagnetic fuel is passed through the mixture throttle passage (4c).
The fuel from the injection valve (5) and the fuel from the air reservoir (4a)
The electromagnetic fuel injection valve (5) is configured to be mixable with air;
The electromagnetic on-off valve (7) is controlled to open and close at a predetermined timing by a controller (17).

In the combustion apparatus for a two-cycle gasoline engine according to a second aspect of the present invention, the controller (17) opens the solenoid on-off valve (7) near bottom dead center and simultaneously or slightly later than the solenoid on-off valve (7). The electromagnetic fuel injection valve (5) is opened.

A combustion device for a two-cycle gasoline engine according to a third aspect of the invention is characterized in that the solenoid valve is an electromagnetic valve provided with an open-open poppet valve 8 for opening the electromagnetic valve 7 to the combustion chamber 4b. .

[0016]

In the two-stroke engine of the crankcase compression type, when the piston 3 goes down, the internal pressure of the crankcase 2 rises, and the air through which the crankcase air introduction pipe 12 communicates to guide pressurized air from the crankcase 2. The internal pressure of the storage chamber 4a also increases. When the piston 3 descends and reaches near the bottom dead center (BDC), the pressure in the crankcase becomes the highest.

The electromagnetic fuel injection valve 5 and the electromagnetic opening / closing valve 7 in the air chamber arranged in the cylinder head 4 are connected to the controller 1.
7, the control is performed in synchronization with the angle signal of the crankshaft of the engine. Depending on the operating conditions of the engine, such as the number of revolutions and the load, the opening and closing of the solenoid valve 7 of the air reservoir is controlled by the controller 17 immediately before the piston 3 reaches the bottom dead center. The air flows into the mixture passage 4
After that, the fuel is injected into the combustion chamber 4b.

At the same time as the injection of the pressurized air, the electromagnetic fuel injection valve 5 is opened under the control of the controller 17 to inject fuel at a pressure of several kgf / cm ² . The injected fuel pushes the check valve 6 open, and is injected into the air-fuel mixture throttle passage 4c via the injection fuel passage 4d. Mixture throttle passage 4
Since air is also ejected to c, the ejected fuel is atomized by the fast air flow and diffuses into the combustion chamber 4b.

Although the fuel injection period varies depending on the operating conditions of the engine, when the fuel injection is completed, the electromagnetic on-off valve 7 in the air reservoir is closed, and the injection of air is also stopped. After that, the piston 3 moves up to the compression stroke, and the piston 3
When the air-fuel mixture reaches the vicinity of the top dead center, the ignition plug 11 ignites the air-fuel mixture, the flame propagates over the entire combustion chamber 4b, and the combustion is completed. Thereafter, the operation of the engine proceeds from expansion to scavenging, and one cycle is completed.

[0020]

FIG. 1 is an explanatory view of the configuration of an in-cylinder fuel injection and combustion apparatus of a small two-stroke gasoline engine according to an embodiment of the first invention, and FIG. 2 is an enlarged longitudinal sectional view around a cylinder head in FIG. FIG. 3 is a timing chart of the operation of the engine shown in FIGS. Hereinafter, the configuration and operation of the combustion device of the engine will be described with reference to FIGS.

A cylinder head 4 is mounted on the upper portion of the cylinder 1, and a combustion chamber 4b is formed surrounded by the lower surface, the top surface of the piston 3, and the inner wall surface of the upper portion of the cylinder. A discharge electrode portion is formed on the inner wall surface of the combustion chamber. A spark plug 11 is arranged in a peek. An air reservoir 4a is formed in the cylinder head 4, and a lower end of the air reservoir communicates with the combustion chamber 4b. Is provided with a poppet valve 8 of an electromagnetic on-off valve 7 and is normally closed. A cylinder head air passage 4e communicating with the air reservoir 4a is formed in an upper portion of the cylinder head 4, and the air passage 4e has a crankcase air passage serving as a flow passage for pressurized air sent from the crankcase 2. The introduction pipe 12 is connected.

The cylinder head 4 is provided with an electromagnetic fuel injection valve 5. The injection fuel passage 4d at the outlet of the fuel injection valve 5 is an extremely narrow passage, and a check valve 6 for preventing a compressed air-fuel mixture or combustion gas from flowing backward from the combustion chamber 4b in the middle of the injection fuel passage 4d. Is fitted, and the end of the passage on the outflow side communicates with the mixture throttle passage 4c. At the side of the crankcase 2 is a crankcase air introduction pipe 1
2 is provided and connected to the air passage 4 e formed in the cylinder head 4.

The electromagnetic opening / closing valve 7 in the air reservoir is a controller 1
The timing from which the electromagnetic on-off valve 7 is opened and closed is controlled by a signal from the crank angle signal sensor 19, which is electrically connected to the crank angle signal sensor 19. The solenoid on-off valve 7 has a solenoid 7a on its upper part,
A sliding pin 7b is incorporated therein, and an outwardly opening poppet valve 8 is provided below the poppet valve 8.
, The valve seat at the lower end is in a closed state.

When the piston 3 moves down in the cylinder 1,
As shown in FIG. 3, the air pressure in the crankcase 2 increases and reaches the maximum pressure near the bottom dead center (BDC), and usually generates a pressure of 1 kgf / cm ² or less. When the piston 3 reaches the vicinity of the bottom dead center, the solenoid 7 incorporated in the electromagnetic opening / closing valve 7 of the air reservoir is controlled by the controller which inputs the signal from the crank angle signal sensor 19.
a) The poppet valve 8 is pushed down and opened in the air reservoir 4a via the sliding pin 7b. When the poppet valve 8 is pushed open,
The compressed air in the crankcase 2 flows from the air reservoir 4a via the crankcase air inlet pipe 12 and the cylinder head air passage 4e to the combustion chamber 4b via a mixture throttle passage 4c.
Spouts. The mixture throttle passage 4c is formed by appropriately narrowing the passage area in order to increase the air flow rate and enhance the ejector effect.

On the other hand, the fuel in the fuel tank 13 is fed to a fuel pressure regulator 15 via a fuel supply pump 14 and adjusted to a required fuel pressure before being supplied to the electromagnetic fuel injection valve 5. Under the control of the controller 17, the electromagnetic fuel injection valve 5 is opened and fuel is injected at the same time as the compressed air ejection by the operation of the poppet valve 8 or slightly delayed as shown in FIG. 3. The injected fuel pushes open the check valve 6 in the injected fuel passage 4d, and is ejected to the mixture throttle passage 4c.

The fuel injected into the air-fuel mixture throttle passage 4c is atomized by the high-speed air flow and diffuses into the combustion chamber 4b. As shown in FIG. 3, when the fuel injection by the operation of the electromagnetic fuel injection valve 5 is completed, the poppet valve 8 of the air reservoir 4a is closed by the solenoid 7a of the electromagnetic on-off valve 7 and the biasing spring 9, and the air is released. Close the eruption.

Thereafter, the piston 3 rises to the compression stroke, the pressure in the cylinder rises, and when the air-fuel mixture is ignited by the spark plug 11 near the top dead center (TDC), the flame propagates throughout the combustion chamber 4b. Burn. At this time, the combustion chamber 4
The pressure inside b becomes higher than 10 kgf / cm ² , but the backflow of the combustion gas into the crankcase 2 is suppressed by the open-open poppet valve 8 provided in the air reservoir 4a. Further, intrusion of the combustion gas into the electromagnetic fuel injection valve 5 can be suppressed by the check valve 6 fitted in the injection fuel passage 4d.

[0028]

The following effects can be obtained by the combustion apparatus for a two-cycle gasoline engine according to the present invention. Since the atomization of the injected fuel is promoted by using the compressed air generated in the crankcase of the self-cylinder, it is not necessary to install an air reservoir or an air compressor for air injection. By appropriately narrowing the passage area of the air-fuel mixture passage to increase the flow velocity of the air ejected from the air reservoir and promoting the atomization of the fuel ejected to the passage and the mixing with the air, the combustion is improved. As a result, the amount of unburned combustible components discharged can be reduced, and the fuel consumption efficiency can be improved. The reverse flow of the compressed air-fuel mixture or combustion gas from the combustion chamber to the crankcase is suppressed by the poppet valve, and the intrusion of the combustion gas into the electromagnetic fuel injection valve is suppressed by the check valve, preventing damage and preventing engine damage. Performance can be improved.

[Brief description of the drawings]

FIG. 1 is a configuration explanatory view of an in-cylinder fuel injection combustion device of a small two-stroke gasoline engine according to an embodiment of the present invention.

FIG. 2 is an enlarged longitudinal sectional view around a cylinder head in FIG. 1;

FIG. 3 is a timing chart for the operation of the engine shown in FIGS. 1 and 2;

FIG. 4 is an explanatory view of a configuration of an in-cylinder fuel injection and combustion apparatus of a small two-cycle gasoline engine according to the related art.

FIG. 5 is an enlarged longitudinal sectional view around a cylinder head in FIG. 4;

FIG. 6 is a dimming diagram for the operation of the engine shown in FIGS. 4 and 5;

[Explanation of symbols]

1 ... cylinder, 2 ... crankcase, 3 ... piston, 4
... Cylinder head, 4a ... Air chamber, 4b ... Combustion chamber, 4
c ... air-fuel mixture throttle passage, 4d ... injection fuel passage, 4e ... cylinder head air passage, 5 ... electromagnetic fuel injection valve, 6 ... check valve, 7 ... electromagnetic opening / closing valve (air reservoir), 7a ... solenoid (electromagnetic opening / closing) Valve), 7b ... sliding pin (electromagnetic on-off valve), 8 ...
Poppet valve, 9 ... biasing spring, 11 ... spark plug, 12 ...
Crankcase air inlet pipe, 13 ... fuel tank, 14 ...
Fuel supply pump, 15: fuel pressure regulator, 16: fuel inlet supply pipe, 17: controller, 18: high voltage generator for ignition, 19: crank angle signal sensor.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification code FI F02M 67/02 F02M 67/02 69/00 310 69/00 310E (56) References JP-A-5-195787 (JP, A) JP-A-5-321796 (JP, A) JP-A-3-222827 (JP, A) JP-A-3-134262 (JP, A) JP-A-4-330374 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) F02B 1/00-23/10 F02M 51/00 F02M 67/02

Claims (3)

(57) [Claims] 1. In a two-stroke gasoline engine,
An air reservoir (4a) for introducing compressed air generated in the electromagnetic fuel injection valve (5) and the crankcase (2) is provided in the cylinder head (4), and the air reservoir (4a) and the combustion chamber (4) are provided.
b) with an electromagnetic on-off valve (7) for opening and closing between
In, the electromagnetic on-off valve (7) and the combustion chamber air-fuel mixture throttle passage (4c) between the (4b) provided, the electromagnetic fuel injection valve (5)
Is connected to the mixture throttle passage (4c) via an injection fuel passage (4d) fitted with a check valve (6), and the electromagnetic fuel injection valve (5 ) is connected to the mixture throttle passage (4c). ) From fuel
Air and the air from the air reservoir (4a) can be mixed.
The electromagnetic fuel injection valve (5) and the electromagnetic on-off valve
A combustion apparatus for a two-cycle gasoline engine, characterized in that opening and closing of (7) is controlled at a predetermined timing by a controller (17). Wherein said controller (17) is opened the solenoid valve (7) at the bottom dead center near the electromagnetic on-off valve (7)
2. A combustion apparatus for a two-stroke gasoline engine according to claim 1, wherein said electromagnetic fuel injection valve (5) is opened simultaneously or slightly later. 3. The combustion on-off valve (7) is provided in a combustion chamber (4b).
2. The combustion device for a two-stroke gasoline engine according to claim 1, wherein the valve is an electromagnetic on-off valve provided with an outward opening type poppet valve (8) that opens to the side.