JPH07133724A - Combustion equipment of gasoline engine - Google Patents

Abstract

PURPOSE:To prolong injection periods of fuel and air, respectively, and moderate their high responsiveness by attaching a fuel holding chamber to the front part of a combustion chamber and interposing an opening-out type mixture injection valve between the two chambers while providing a fuel valve and an air valve of respectively electromagnetic open/close types inside the fuel holding chamber. CONSTITUTION:An electromagnetic open/close fuel valve 5 is opened when a piston 11 goes into its expansion stroke. On the other hand, an electromagnetic open/close air valve 8 is closed. A mixture injection valve 9 communicating with a combustion chamber 12a is also closed. The electromagnetic open/close fuel valve 5 is taken closed, by metering the required fuel, during a period from the intake stroke until the exhaust port is closed. Now that the exhaust port is closed, air is guided into a fuel holding chamber 9a by opening the electromagnetic open/close air valve 8, the opening-out type mixture injection valve 9 is pushed opened to the combustion chamber 12a side by raising the pressure and the mixture is injected into the combustion chamber 12a by atomizing it with air. When the compression stroke comes close to its end, the opening-out type mixture injection valve 9 is automatically closed and injection is completed.

Description

Detailed Description of the Invention

[0001]

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

[0002]

2. Description of the Related Art A conventional in-cylinder injection combustion device for a small high-speed two-cycle gasoline engine will be described with reference to FIGS. 4 to 6. Reference numeral 112 denotes a cylinder head above the engine, and the cylinder head 112 is provided with a combustion chamber 112a. ,
There are an electromagnetic opening / closing fuel valve 105 and an electromagnetic opening / closing air valve 10.
9 and a spark plug 113 are provided.

The electromagnetic opening / closing fuel valve 105 and the passage portion 112b at the outlet of the electromagnetic opening / closing air valve 109 are open to the combustion chamber 112a, and the fuel injected from the electromagnetic opening / closing fuel valve 105 is injected from the electromagnetic opening / closing air valve 109. By the air
It is atomized, injected into the combustion chamber 112a, and ignited in the air-fuel mixture by the spark of the spark plug 113 near the end of the compression stroke and burned. The above combustion device is a so-called air-assisted in-cylinder injection combustion device.

The fuel is supplied from the fuel tank 101.
Depending on the pump 102, several kgf / cm ²Pressurize to fuel
After the pressure is adjusted by the regulator 103, the electromagnetic opening / closing fuel valve 10
It is injected through 5. This electromagnetic opening / closing fuel valve 105
Electrically connected to the control device 115, and the engine crankshaft
Based on the crank angle signal by the rotation angle sensor 116
The injection timing and injection period (amount) are controlled.

The air in the air reservoir 106 is adjusted to several kgf / cm ² by an air regulator 107 and is injected through an electromagnetic opening / closing air valve 109. The electromagnetic opening / closing air valve 109 is electrically connected to the control device 115, and similarly to the electromagnetic opening / closing fuel valve 105, the engine crankshaft rotation angle sensor 116 sets the injection timing and the injection period (amount) on the basis of the crank angle signal. Controlled.

In a small two-stroke gasoline engine, the fuel injection timing is to open the valve after 220 ° CA after TDC when the exhaust port is closed in order to prevent the fuel blow-through. Further, the fuel injection period controls the injection together with the injection hole area of the injection valve and the injection pressure.
The injection amount (load) is controlled by the injection period, and is approximately 5 ° CA
It becomes 40 ° CA (idle to maximum injection amount). On the other hand, the injection timing and injection period of air are controlled to be substantially the same as the fuel.

As described above, in the in-cylinder injection combustion device for a small high speed two-cycle engine, the controlled fuel and air are injected into the fuel in a short period in the early stage of the compression stroke of about 5 ° CA to 40 ° CA after the exhaust port is closed. It is injected into the room and compressed TD
I ignite and burn before C.

[0008]

Many small and high speed two-stroke gasoline engines have a displacement of about 50 cc / 1 cyl and a rotational speed of over 10000 rpm. Therefore, in this class of in-cylinder injection combustion device, a small amount of fuel injection is required. Accurately in a short time (about 0.2 s, 0.5 mm ³ / s
t) The electromagnetic opening / closing fuel valve for injection requires a very high voltage in order to strengthen the electromagnetic force, and in reality, it is scarcely produced.

In the conventional electromagnetic opening / closing fuel valve, the injection amount is about 2 mm ³ / st at the minimum, and this electromagnetic opening / closing fuel valve also obtains its high response, so the spring force in the electromagnetic opening / closing fuel valve is weakened. Therefore, the fuel supply pressure is also 2-3 kg /
It is set as low as cm ² . Therefore, if the compression pressure in the combustion chamber becomes equal to or higher than the fuel injection pressure, the injection cannot be performed, and therefore, it is necessary to end the injection at the beginning of the compression stroke.

The same applies to the electromagnetic on-off air valve, and in order to obtain a high response, the air pressure cannot be set high, so that it is necessary to end the air injection at the beginning of the compression stroke as well. In a small-sized high-speed two-cycle engine combustion device, fuel injection is performed in order to reduce blow-through of fuel in a so-called overlap period in which a scavenging port and an exhaust port are simultaneously opened (reduction of unburned fuel (HC) emissions). Since it is important to carry out the timing after the end of the exhaust port (beginning of the compression stroke), the injection period is limited to an extremely short time in addition to the above reason.

Thus, it is necessary to inject a small amount of fuel and air in a short time, but in reality, as described above, it is not possible to manufacture an electromagnetic injection valve capable of high-speed response control, and therefore relatively responsive. The fuel valve and the air are injected relatively quickly before the exhaust port is closed, and the injection period is extended. Therefore, unburned fuel (HC)
There is a problem that exhaust gas is polluted by exhaust gas and the fuel efficiency is deteriorated.

The present invention has been proposed in view of the above problems, and the object thereof is to significantly reduce the high responsiveness of the electromagnetic opening / closing fuel valve and the electromagnetic opening / closing air valve. In addition, the blow-through of unburned gas can be greatly reduced and the fuel consumption rate can be greatly reduced. Another object of the present invention is to provide a combustion device for a gasoline engine, which can reduce damage to the electromagnetic opening / closing fuel valve and the electromagnetic opening / closing air valve due to combustion gas.

[0013]

In order to achieve the above object, the present invention provides a gasoline engine combustion apparatus for injecting, igniting and burning fuel directly into a combustion chamber of a cylinder. A fuel storage chamber is provided in the front part, and an externally open air-fuel mixture injection valve that is normally closed by spring force and opens and closes due to the pressure difference between the fuel storage chamber and the combustion chamber is provided between the fuel storage chamber and the combustion chamber. An electromagnetic opening / closing fuel valve and an electromagnetic opening / closing air valve, in which the injection timing and period of fuel and air are controlled for each cycle by a control device based on the engine rotation angle signal, are provided in the room.

In the gasoline engine combustion apparatus, a control device opens and closes the electromagnetic opening / closing fuel valve between the end of combustion in the previous cycle and the start of the compression process in the next cycle, thereby controlling the required amount of fuel in the fuel storage chamber. While injecting fuel, after opening the compression process of the next cycle, the electromagnetic on-off air valve is opened to inject air into the fuel storage chamber, and the mixture injection valve is automatically operated by the pressure increase in the fuel storage chamber. Open and inject the air-fuel mixture into the combustion chamber, close the air-fuel mixture injection valve due to increase in the compression pressure in the combustion chamber, the air-fuel mixture ignites and burns,
The electromagnetic on-off air valve may be controlled to be closed before the fuel chamber pressure becomes lower than the air injection pressure in the expansion stroke.

[0015]

The gasoline engine combustion apparatus of the present invention is constructed as described above, and the electromagnetic on-off fuel valve is controlled by the control unit in synchronization with the engine rotation angle signal.
When the piston enters the expansion stroke, the electromagnetic opening / closing fuel valve opens. At this time, the electromagnetic opening / closing air valve is closed. Further, the air-fuel mixture injection valve communicating with the combustion chamber is also closed by being pressed by the cylinder internal pressure. The electromagnetic on-off fuel valve is closed by metering the required fuel during the period from the supply stroke to the closing of the exhaust port. When the exhaust port is closed, the electromagnetic opening / closing air valve is opened by the control device, air is introduced into the fuel storage chamber, the pressure in the air storage chamber rises, and it is closed by a relatively weak spring force. The air-fuel mixture injection valve is pushed toward the combustion chamber side, and the air-fuel mixture is atomized by air and ejected into the combustion chamber. Near the end of the compression stroke,
When the pressure in the cylinder rises and becomes higher than the air pressure in the fuel storage chamber, the outward-opening type mixture injection valve automatically closes, and the injection ends. The air-fuel mixture in the combustion chamber evaporates and is eventually ignited by the spark plug in the vicinity of TDC, the flame propagates throughout the combustion chamber, enters the expansion stroke, and eventually the combustion ends. On the other hand, the electromagnetic opening / closing air valve is closed before the pressure in the cylinder in the expansion stroke becomes equal to or lower than the injection air pressure. After the electromagnetic opening / closing air valve is closed, the electromagnetic opening / closing fuel valve is opened again, and the same control cycle is repeated.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, a combustion apparatus for a gasoline engine according to the present invention will be described with reference to an embodiment shown in FIGS. 1 of FIG.
Is a main body of the engine, and a combustion chamber 12a formed in an upper portion of a cylinder head 12 of the main body of the engine 10 is provided with an ignition plug 13 and an outward-opening mixture gas injection valve 9.
As shown in FIG. 2, a fuel storage chamber 9a is provided in the upper portion of the outwardly opening type air-fuel mixture injection valve 9, and a spring 9 is provided in the lower portion thereof.
An outer opening valve 9b closed by c is provided, and the outer opening valve 9b faces the combustion chamber 12a.

An electromagnetic opening / closing fuel valve 5 and an electromagnetic opening / closing air valve 8 are provided above the fuel storage chamber 9a. The electromagnetic opening / closing fuel valve 5 is a general small electromagnetic valve, and is electrically connected to the control device 15. The electromagnetic opening / closing air valve 8 is electrically connected to the control device 15. The control device 15
The engine rotation angle signal (piston position signal) from the engine crank angle sensor 16 is input to the valve so that the opening / closing timings of the electromagnetic opening / closing fuel valve 5 and the electromagnetic opening / closing air valve 8 are controlled in synchronization with the piston position. It has become.

1, 1 is a fuel tank, 2 is a fuel supply pump, 3 is a fuel regulator, 4 is a fuel supply pipe, 6 is an air reservoir, 7 is an air regulator, 14 is a spark plug control device, and FIGS. 11 is a piston, 8a in FIG. 2 is a coil of the electromagnetic opening / closing air valve 8, 8b is a valve portion of the electromagnetic opening / closing air valve 8,
Reference numeral 8c is a spring of the electromagnetic opening / closing air valve 8. FIG. 3 is a crank angle time block diagram of the combustion device.

Next, the operation of the gasoline engine combustion apparatus shown in FIGS. 1 to 3 will be described in detail. Controller 15
The electromagnetic open / close fuel valve 5 is controlled in synchronization with the engine rotation angle signal. However, when the piston 11 enters the expansion stroke, the electromagnetic open / close fuel valve 5 opens. At this time, the electromagnetic opening / closing air valve 8 is closed. Further, the air-fuel mixture injection valve 9 communicating with the combustion chamber 12a is also pressed by the cylinder pressure,
It's closed. The electromagnetic opening / closing fuel valve 5 is closed by metering the required fuel during the period from the supply stroke to the closing of the exhaust port.

When the exhaust port is closed, the controller 15
The electromagnetic open / close air valve 8 is opened by this, the air is introduced into the fuel storage chamber 9a, the pressure in the air storage chamber 9a rises, and the outer opening type air-fuel mixture injection valve 9 which has been closed by a comparatively weak spring force.
Is pushed open to the combustion chamber 12a side, and the air-fuel mixture is atomized by the air and ejected into the combustion chamber 12a. When the compression stroke approaches the end, the pressure in the cylinder rises and the fuel storage chamber 9
When it becomes higher than the air pressure of a, the outward-opening type mixture injection valve 9
Automatically closes and the injection ends. The air-fuel mixture in the combustion chamber 12a evaporates, and eventually the spark plug 1 near TDC.
3 is ignited, the flame propagates to the entire combustion chamber 12a, enters the expansion stroke, and eventually the combustion ends.

On the other hand, the electromagnetic opening / closing air valve 8 is closed before the pressure in the cylinder in the expansion stroke becomes lower than the injection air pressure.
After the electromagnetic opening / closing air valve 8 is closed, the electromagnetic opening / closing fuel valve 5 is opened again, and the same control cycle is repeated.

[0022]

As described above, the combustion apparatus for a gasoline engine according to the present invention can take a long fuel injection period (metering period) and air injection period. Therefore, an electromagnetic opening / closing fuel valve and an electromagnetic opening / closing valve are provided. The high responsiveness of the air valve can be greatly eased. Further, the injection timing of the air-fuel mixture can be set after the exhaust port is closed, so that the blow-through of unburned gas can be greatly reduced and the fuel consumption rate can be greatly reduced.

Further, since the electromagnetic opening / closing fuel valve and the electromagnetic opening / closing air valve are not directly exposed to the combustion chamber, damage to the electromagnetic opening / closing fuel valve and the electromagnetic opening / closing air valve due to combustion gas can be reduced.

[Brief description of drawings]

FIG. 1 is a system diagram showing an embodiment of a gasoline engine combustion apparatus of the present invention.

FIG. 2 is a vertical cross-sectional side view showing a combustion chamber and its peripheral portion of the combustion apparatus.

FIG. 3 is a crank angle time block diagram of the combustion device.

FIG. 4 is a system diagram showing an in-cylinder injection combustion device of a conventional small-sized high-speed two-cycle gasoline engine.

FIG. 5 is a vertical cross-sectional side view showing a combustion chamber and its peripheral portion of the combustion apparatus.

FIG. 6 is a crank angle time block diagram of the combustion device.

[Explanation of symbols]

 5 Electromagnetic open / close fuel valve 8 Electromagnetic open / close air valve 9 Air-fuel mixture injection valve 9a Fuel storage chamber 10 Engine body 11 Piston 12a Combustion chamber 13 Spark plug 15 Control device

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Office reference number FI technical display area F02M 69/10

Claims (2)

[Claims] 1. In a combustion apparatus for a gasoline engine, in which fuel is directly injected into a combustion chamber of a cylinder, ignited and burned, a fuel storage chamber is provided in front of the combustion chamber, and the fuel storage chamber and the combustion chamber are connected to each other. An externally open air-fuel mixture injection valve that is normally closed by spring force and opened / closed by the pressure difference between the two chambers is installed between the fuel injection chamber and the fuel storage chamber by the control device based on the engine rotation angle signal. Also, a combustion device for a gasoline engine is provided with an electromagnetic opening / closing fuel valve and an electromagnetic opening / closing air valve for controlling the injection timing and period of air. 2. The control device opens and closes the fuel valve to inject a required amount of fuel into the fuel storage chamber between the end of combustion in the previous cycle and the start of the compression process in the next cycle. After entering the compression process of the cycle, the electromagnetic on-off air valve is opened to inject air into the fuel storage chamber, and the air-fuel mixture injection valve is automatically opened due to the pressure increase in the fuel storage chamber to open the air-fuel mixture in the combustion chamber. Is injected, and the mixture injection valve is closed by the increase of the compression pressure in the combustion chamber, the mixture is ignited and burned, and the electromagnetic opening / closing air valve is closed before the pressure in the fuel chamber falls below the air injection pressure in the expansion stroke. 2. The combustion apparatus for a gasoline engine according to claim 1, wherein the combustion apparatus is controlled as follows.