JPH08338345A - Combustion device for two cycle gasoline engine - Google Patents

Abstract

PURPOSE: To prevent the blowby flow of air-fuel mixture, improve combustion, reduce discharge of unburnt hydrocarbon, and thereby enhance a fuel consumption efficiency. CONSTITUTION: A cylinder head is equipped with an air-fuel mixture chamber 45 where an air-fuel mixture is formed out of fuel fed from an electromagnetic fuel valve 30, and of compressed air from the inside of its own cylinder. In the engine where an air-fuel mixture valve (poppet valve) 43 is disposed at a communication part with the air-fuel mixture chamber and a combustion chamber 7, and an air-fuel mixture formed at the air-fuel mixture chamber is injected into the combustion chamber, it is ignited so as to be burnt, and air is compressed in a pump chamber 12 which is formed while the stepped cylinder 1 of its own engine and its stepped piston 2 are being combined. And air pressure is so constituted as to act on the diaphragm 42 of a pressure type air-fuel mixture injection valve 40 so as to allow the poppet valve 43 to be driven.

Description

Detailed Description of the Invention

[0001]

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

[0002]

2. Description of the Related Art FIG. 4 is a structural explanatory view of a conventional example of a combustion apparatus for a small high speed two-cycle gasoline engine, and FIG. 5 is a vertical sectional view around a cylinder head in the engine shown in FIG. Next, the configuration and operation of the conventional example will be described with reference to FIGS. Cylinder head 104 on top of engine
A combustion chamber 104a is formed therein, and an electromagnetically driven air-fuel mixture valve 107 and an ignition plug 106 are disposed on the upper wall surface thereof. The poppet valve 10 of the mixture valve 107
The air-fuel mixture chamber 104b is formed in the upper part of the valve umbrella of No. 8, and the air-fuel mixture chamber 104b is connected to the electromagnetic fuel valve 105 arranged in the cylinder head 104 in the vicinity of the air-fuel mixture valve 107 by the fuel passage 104d. It is in communication.

This combustion device is a device that does not use a carburetor, and electrically controls the electromagnetic fuel valve 105 and the air-fuel mixture valve 107 in synchronization with the rotation of the crankshaft 110 to generate compressed air in the cylinder 101 itself. A part of the mixture is stored in the air-fuel mixture chamber 104b and is directly injected into the combustion chamber 104a together with the fuel spray supplied to the air-fuel mixture chamber 104b through another route.

Fuel is introduced from a fuel tank 112 to a fuel pressure regulator 114 by a fuel supply pump 113, regulated to about 5 kgf / cm ² by the regulator, and then introduced into an electromagnetic fuel valve 105. The electromagnetic fuel valve 105 is an electromagnetic control valve whose opening / closing timing and injection amount are controlled by the controller 116, and supplies fuel to the air-fuel mixture chamber 104b in synchronization with the rotation angle signal of the crankshaft 110 detected by the crank angle signal sensor 118. To do. At the time of supply, the mixture valve 107 is being closed.

FIG. 6A shows an example of the opening / closing timing diagram of the engine exhaust / exhaust ports shown in FIGS. 4 and 5, and FIG. 6B shows an example of the control timing diagram of the poppet valve and the electromagnetic fuel valve. The air-fuel mixture valve 107 is also a solenoid valve whose opening and closing are controlled by the crank angle signal sensor 118 and the controller 116, and the poppet valve 10 is operated from the end of the exhaust action to the beginning of the compression action.
8 is opened, and the poppet valve 108 is closed from about the middle of compression operation to the end thereof. During the first half of the period when the poppet valve 108 is opened, the air-fuel mixture is supplied from the air-fuel mixture chamber 104b to the combustion chamber 10.
4a, and the compressed air from the cylinder 101 in the latter half of the period is pumped into the air-fuel mixture chamber 104b to accumulate the pressure.

As described above, the fuel is supplied from the electromagnetic fuel valve 105 into the air having a pressure of several kgf / cm ² accumulated in the air-fuel mixture chamber 104b in the latter half of the opening period of the poppet valve in the previous cycle to operate. At the beginning of the compression action of the cycle, the poppet valve 108 is opened via the sliding pin 107a of the mixture valve 107, the mixture is injected from the mixture chamber 104b to the combustion chamber 104a, and the piston 103 is at the top dead center. It is a device that ignites and burns the air-fuel mixture by the spark discharge of the spark plug 106 when it reaches the vicinity, and promotes the uniform air-fuel mixture generation by utilizing the compressed air of its own cylinder without having a vaporizer. I am trying.

[0007]

The two-cycle gasoline engine has a drawback inherent to the two-cycle system in which the air-fuel mixture is blown through due to the overlap of the scavenging action and the exhaust action. This is a factor of reduced efficiency. The combustion apparatus for a two-cycle gasoline engine described as a conventional example employs a self-compressed air assisted combustion system for the purpose of solving the above-mentioned problems.

By adopting the combustion method, it is possible to prevent blow-through of scavenging gas, realize stable and good combustion, reduce emission of unburned hydrocarbons, and improve fuel consumption efficiency. However, in constructing the combustion apparatus, a solenoid is used by adopting a method that uses electromagnetic force to drive both the fuel valve and the mixture valve. Therefore, the need for a solenoid that is small and lightweight, has sufficient high-speed responsiveness, and has low cost, its control device, and their power supply is a practical issue, especially when it is applied to a small high-speed engine. There is.

The object of the present invention is to solve the above-mentioned problems and to improve the discharge of unburned hydrocarbons and the reduction of fuel efficiency, which are the drawbacks peculiar to the two-cycle engine due to the blow-by of the scavenging air, and to mix the cylinder heads. A two-stroke gasoline engine that can realize a compact, lightweight engine and cost reduction by configuring a mixture injection valve that injects an air-fuel mixture from an air chamber into a cylinder by using compressed air generated in the cylinder itself. To provide a combustion device of.

[0010]

A two-stroke gasoline engine combustion apparatus according to the first aspect of the present invention produces a mixture by fuel supplied from an electromagnetic fuel valve 30 to a cylinder head 2 and compressed air from the cylinder 1 itself. An air-fuel mixture chamber 45 is provided, and an air-fuel mixture valve 43 for opening and closing the air-fuel mixture chamber is provided in a communication portion between the air-fuel mixture chamber and the combustion chamber 7 on the cylinder side. In a two-stroke gasoline engine in which fuel is directly injected into a combustion chamber and ignited by a spark plug 19 to burn, the mixture valve is formed as a poppet valve that opens to the combustion chamber side, and the piston 3 is reciprocated by being sucked into the cylinder. A pressure type mixture injection valve 40 in which a diaphragm 42 on which the pressure of compressed air generated by the mixture acts, the mixture valve, and a valve spring 44 for holding the mixture valve in a closed state are incorporated. Attached to the cylinder head, the air pressure the mixture valve and drives the diaphragm acting.

In the combustion apparatus of the two-stroke gasoline engine of the second invention, the check valve is provided in the pressurized air communication passage 16 for guiding the compressed air for driving the pressure type mixture injection valve to one side of the diaphragm 42. It is characterized in that a high pressure air relief valve 17 is provided which is activated when a pressure of 15 or more or more than a prescribed pressure is applied.

In the combustion apparatus for a two-cycle gasoline engine of the third invention, a large diameter portion 3b is provided in the lower portion of the piston 3, and the large diameter portion of the piston and the large diameter portion 1b formed in the lower portion of the cylinder 1 are provided. A pump chamber 12 for generating the compressed air is formed between them.

[0013]

Next, the operation of the above configuration will be described with reference to FIG. 3 showing the timing of the operation. When the piston 3 descends due to the pressure of the combustion gas in the combustion chamber 7 and the exhaust port 8 opens, the combustion gas in the combustion chamber 7 blows out from the exhaust port 8 with its own gas pressure, and then the scavenging port 9 At the time of opening, the air in the crankcase 6 compressed by the back surface of the piston 3 when the piston 3 descends is transferred to the scavenging port 9 through the main scavenging passage (not shown).
Is introduced into the combustion chamber 7 through the scavenging port and the residual gas in the combustion chamber 7 is scavenged to the exhaust port 8 side.

At the beginning of when the piston 3 has passed the bottom dead center (BDC) and moved to the upward stroke, the poppet valve 43 is opened to transfer the mixture formed from the mixture chamber 45 to the combustion chamber 7 in the previous cycle. To jet. The poppet valve 43 supplies air pressurized by displacement of the piston 3 in a pump chamber 12 formed by a combination of a stepped cylinder and a stepped piston, through a pressurized air communication passage 16 to a pressure type mixture injection valve 40. Of the diaphragm 42 using the air pressure introduced into the pressure working chamber 41 of
The valve is opened by pushing down, and is normally kept closed by the urging force of the valve spring 44.

A high pressure air relief valve 17 is provided in the middle of the pressurized air communication passage 16 and is opened when the air pressure in the pressurized air communication passage 16 exceeds a set pressure to release the high pressure air to the atmosphere. Release inside. As a result, the air pressure acting on the diaphragm 42, the pressure in the cylinder, and the operating condition of the poppet valve are as shown in FIG.

Thereafter, the piston 3 is further raised to close the scavenging port 9, and subsequently the exhaust port 8 is also closed to start the action of compression. As the action of compression progresses, a mixed gas of air and a mixture compressed from the cylinder side is accumulated in the mixture chamber 45, and then the poppet valve 43 is closed. It is stored in the air-fuel mixture chamber 45 until the beginning of compression in the cycle. In addition, at a predetermined time during this period, a predetermined amount of fuel is injected from the electromagnetic fuel valve 30 into the air-fuel mixture chamber 45 to form the air-fuel mixture.

At the time when the piston 3 further rises and reaches near the top dead center (TDC) at the end of the compression action, a spark discharge from the spark plug 19 mounted on the cylinder head 2 causes a mixture gas in the combustion chamber 7. When ignited, a flame nucleus is generated in the discharged electrode portion, and the flame propagates from there to progress combustion.

In consideration of the responsiveness of the valve when the valve is opened, the poppet valve 43 is opened immediately before the scavenging port 9 and the exhaust port 8 are closed, and the mixture gas from the mixture chamber 45 to the combustion chamber 7 is mixed. As a result, the fuel is prevented from blowing through to the exhaust port. Further, since the compressed air from the own cylinder is stored in the air-fuel mixture chamber 45, when the poppet valve 43 is opened, good fuel spray is obtained by the air assist effect, and stable and good combustion is achieved.

The expansion of the combustion gas causes the piston 3 to descend in the cylinder 1 toward the bottom dead center (BDC), and as the piston 3 descends, the exhaust port 8 is opened and the combustion gas is ejected from the port. Then, the scavenging port 9 is opened and residual gas is scavenged from the exhaust port 8.

[0020]

1 is a vertical sectional view of a small high speed two-cycle gasoline engine according to an embodiment of the first to third inventions.
FIG. 2 is a configuration explanatory view of a combustion device for the engine shown in FIG. 1. Next, the configuration of the embodiment will be described with reference to FIGS.

In FIG. 1, 1 is a cylinder, 1a is a small diameter portion formed on the upper portion of the cylinder, 1b is a large diameter portion formed on the lower portion of the cylinder, 2 is a cylinder head, and 3 is a small diameter portion 3a. A stepped piston having a diameter portion 3b is slidably fitted into the stepped cylinder 1 having the small diameter portion 1a and the large diameter portion 1b. A piston ring 3c is fitted on the small diameter portion 3a of the piston 3, and a seal ring 3d is fitted on the large diameter portion 3b.

A combustion chamber 7 is formed by the top surface of the small diameter portion 3a of the piston 3, the small diameter portion 1a of the cylinder 1 and the lower surface of the cylinder head 2, and the small diameter portion 3a of the piston 3 and the cylinder 1 are formed.
The pump chamber 12 is formed by the large-diameter portion 1b. Four
Is a connecting rod, 5 is a crankshaft, 6 is a crankcase, and 7 is the above-mentioned combustion chamber. Reference numeral 8 is an exhaust port formed in the small diameter portion 1a of the cylinder 1, 9 is a scavenging port, and 10 is an intake port provided in the crankcase 6, which communicates with the atmosphere via a check valve 11. The check valve 11 is configured to allow only the flow of air toward the crankcase 6 side, and the crankcase 6 is connected to the scavenging port 9 via a main scavenging passage (not shown).

13 is an air cleaner 18 in the pump chamber 12.
An air inflow path for introducing air through the check valve 1
The check valve 14 is communicated with the pump chamber 12 via 4, and the check valve 14 is configured to allow only the flow of air from the air inflow passage 13 side toward the pump chamber 12.

A pressurized air communication passage 16 is connected to the outlet side of the pump chamber 12 via a check valve 15 to communicate the pump chamber 12 and the pressure working chamber 41 of the pressure type mixture injection valve 40. The check valve 15 is configured to allow only the flow of air from the pump chamber 12 side toward the pressurized air communication passage 16. Reference numeral 17 is a high-pressure air relief valve disposed in the middle of the conduit of the pressurized air communication pipe 16, and is configured to open when an air pressure above a set value acts.

Reference numeral 30 denotes an electromagnetic fuel valve provided in the cylinder head 2, and the fuel supplied to the fuel valve is a fuel tank 34.
From the fuel supply pump 33 to the fuel pressure regulator 3
The pressure is regulated by the regulator, and then introduced into the electromagnetic fuel valve 30. The electromagnetic fuel valve 30 is an electromagnetic control valve whose fuel injection timing and injection amount are controlled by a controller 50 which receives a signal detected by a crank angle signal sensor 51.

Reference numeral 40 denotes a pressure type air-fuel mixture injection valve, which is a pressure working chamber 41 for introducing pressurized air pressure-fed from the pump chamber 12 through the pressurized air communication passage 16, and a poppet type air-fuel mixture valve by air pressure. A diaphragm 42 that pushes down the (poppet valve) 43, a spring 44 that urges the poppet valve 43 to a normally closed state, a fuel supplied from the electromagnetic fuel valve 30 and compressed air sealed from the cylinder itself to form a mixture. The air-fuel mixture chamber 45, and the air-fuel mixture chamber 45 and the combustion chamber 7
The poppet valve 43 that opens and closes the communication part of the.

Next, the operation of the above configuration will be described with reference to FIG. 3 showing the operation timing. When the piston 3 descends due to the pressure of the combustion gas in the combustion chamber 7 and the exhaust port 8 opens, the combustion gas in the combustion chamber 7 blows out from the exhaust port 8 with its own gas pressure, and then the scavenging port 9 At the time of opening, the air in the crankcase 6 compressed by the back surface of the piston 3 when the piston 3 descends is guided to the scavenging port 9 through the main scavenging passage (not shown), and the combustion chamber is discharged from the scavenging port. 7, and the residual gas in the combustion chamber 7 is swept out to the exhaust port 8 side.

At the beginning of when the piston 3 has passed the bottom dead center (BDC) and moved to the upward stroke, the poppet valve 43 is opened to transfer the air-fuel mixture formed in the previous cycle from the air-fuel mixture chamber 45 to the combustion chamber 7. To jet. The poppet valve 43 pressurizes the air pressurized by the displacement of the piston 3 in the pump chamber 12 formed by the combination of the stepped cylinder and the stepped piston through the pressurized air communication passage 16 to the pressure type mixture injection valve 40. Of the diaphragm 42 using the air pressure introduced into the pressure working chamber 41 of
The valve is opened by pushing down, and is normally kept closed by the urging force of the valve spring 44.

A high-pressure air relief valve 17 is provided in the middle of the pressurized air communication passage 16 and opens when the air pressure in the pressurized air communication passage 16 exceeds a set pressure to release the high pressure air to the atmosphere. Release inside. As a result, the air pressure acting on the diaphragm 42, the pressure in the cylinder, and the operating condition of the poppet valve are as shown in FIG.

After that, the piston 3 further rises and the scavenging port 9 is closed, and then the exhaust port 8 is also closed to start the action of compression. As the action of compression progresses, a mixed gas of air and a mixture compressed from the cylinder side is accumulated in the mixture chamber 45, and then the poppet valve 43 is closed. It is stored in the air-fuel mixture chamber 45 until the beginning of compression in the cycle. In addition, at a predetermined time during this period, a predetermined amount of fuel is injected from the electromagnetic fuel valve 30 into the air-fuel mixture chamber 45 to form the air-fuel mixture.

At the time when the piston 3 further rises to reach the top dead center (TDC) near the end of the compression action, the spark discharge from the spark plug 19 mounted on the cylinder head 2 causes the air-fuel mixture in the combustion chamber 7 to be discharged. When ignited, a flame nucleus is generated in the discharged electrode portion, and the flame propagates from there to progress combustion.

In consideration of the responsiveness of the valve when the valve is opened, the poppet valve 43 is opened immediately before the scavenging port 9 and the exhaust port 8 are closed, and the mixture gas from the mixture chamber 45 to the combustion chamber 7 is mixed. As a result, the fuel is prevented from blowing through to the exhaust port. Further, since the compressed air from the own cylinder is stored in the air-fuel mixture chamber 45, when the poppet valve 43 is opened, good fuel spray is obtained by the air assist effect, and stable and good combustion is achieved.

The expansion of the combustion gas causes the piston 3 to descend in the cylinder 1 toward the bottom dead center (BDC), and as the piston 3 descends, the exhaust port 8 is opened and the combustion gas is ejected from the port. Then, the scavenging port 9 is opened and residual gas is scavenged from the exhaust port 8.

[0034]

According to the present invention, combustion is improved by applying a combustion device of an in-cylinder mixture injection system that uses compressed air from its own cylinder as a means for atomizing fuel to a two-cycle gasoline engine. The prevention of air-fuel mixture blow-through is achieved, and it becomes possible to significantly reduce the emission of unburned hydrocarbons and significantly improve the fuel consumption efficiency.
According to the second aspect of the invention, it is possible to precisely control the ejection of the air-fuel mixture from the air-fuel mixture chamber, and according to the third aspect of the invention, the air-fuel mixture valve (poppet valve) can be driven by means of a simple structure. Since it does not require a power source, the cost can be reduced and the engine structure can be made small and lightweight.

[Brief description of drawings]

FIG. 1 is a vertical sectional view of a small high-speed two-cycle gasoline engine according to an embodiment of the present invention.

FIG. 2 is a structural explanatory view of a combustion device of the engine shown in FIG.

FIG. 3 is an explanatory diagram of an operating state of the engine shown in FIG.

FIG. 4 is a structural explanatory view of a conventional example of a combustion device for a small high-speed two-cycle gasoline engine.

5 is a longitudinal sectional view around a cylinder head in the engine shown in FIG.

6 is an opening / closing timing diagram (a) of the engine sweep and exhaust ports shown in FIGS. 4 and 5, and a control timing diagram (b) of the poppet valve and the electromagnetic fuel valve.

[Explanation of symbols]

1 ... Cylinder, 2 ... Cylinder head, 3 ... Piston, 4
... connecting rod, 5 ... crankshaft, 6 ... crankcase, 7 ... combustion chamber, 8 ... exhaust port, 9 ... scavenging port, 10 ... intake port, 11 ... check valve, 12 ... pump chamber, 13 ... air inflow path , 14 ... Check valve, 15 ... Check valve,
16 ... Pressurized air communication passage, 17 ... High pressure air relief valve, 18 ...
Air cleaner, 19 ... Spark plug, 20 ... Ignition control device, 30 ... Electromagnetic fuel valve, 31 ... Fuel supply pipe, 32 ... Regulator, 33 ... Fuel supply pump, 34 ... Fuel tank,
40 ... Pressure mixture injection valve, 41 ... Pressure working chamber, 42 ...
Diaphragm, 43 ... Mixture valve (poppet valve), 44 ...
Valve spring, 45 ... Mixture chamber, 50 ... Controller, 51 ...
Crank angle signal sensor.

Continuation of the front page (51) Int.Cl. ⁶ Identification number Office reference number FI Technical display location F02F 3/00 F02F 3/00 E F02M 69/10 F02M 69/10 (72) Inventor Shunichi Mori Fukahori Town, Nagasaki City 5-717-1 Mitsubishi Heavy Industries, Ltd. Nagasaki Research Institute (72) Inventor Hiroshi Nakagawa 5-717-1, Fukahoricho, Nagasaki City Nagasaki Research Institute, Mitsubishi Heavy Industries, Ltd.

Claims (3)

[Claims] 1. An electromagnetic fuel valve (3) is attached to a cylinder head (2).
0) is provided with a fuel-air mixture chamber (45) for generating a fuel-air mixture by the fuel supplied from the cylinder (1) and compressed air from the cylinder (1), and the communication portion between the fuel-air mixture chamber and the combustion chamber (7) on the cylinder side. A two-cycle gasoline in which an air-fuel mixture valve (43) for opening and closing the communication portion is arranged in the fuel cell, and the air-fuel mixture generated in the air-fuel mixture chamber is directly injected into the combustion chamber and ignited by a spark plug (19) to burn. In the engine, the air-fuel mixture valve is formed as a poppet valve that opens to the combustion chamber side, and a diaphragm (42) on which the pressure of compressed air generated by the reciprocating motion of the piston (3) that is sucked into the cylinder acts,
A pressure type air-fuel mixture injection valve (40) incorporating the air-fuel mixture valve and a valve spring (44) for holding the air-fuel mixture valve in a closed state is mounted on a cylinder head, and air pressure acts on the air-fuel mixture valve. Driven by a diaphragm 2
Combustion device for cycle gasoline engine. 2. A non-return valve (15) and a pre-specified valve or more are provided in a pressurized air communication passage (16) for guiding the compressed air for driving the pressure type mixture injection valve to one side of the diaphragm (42). The combustion system for a two-cycle gasoline engine according to claim 1, further comprising a high-pressure air relief valve (17) which is activated when pressure is applied. 3. A large diameter portion (3) is provided at a lower portion of the piston (3).
b) is provided, and the large diameter part of the piston and the cylinder (1) are provided.
The combustion apparatus for a two-cycle gasoline engine according to claim 1, wherein a pump chamber (12) for generating the compressed air is formed between the pump chamber (12) and a large diameter portion (1b) formed in the lower part of the.