JP2501710Y2 - Fuel injection device for internal combustion engine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a fuel injection device for an internal combustion engine.

[Conventional technology]

Japanese Patent Publication No. 63-500322 discloses the operation of a spark ignition type two-cycle internal combustion engine having a combustion chamber, an engine cycle for controlling gas emission from the combustion chamber, and an exhaust port which is opened and closed in a timely manner. At low engine loads and low speeds, at least 80% of the metered amount of fuel is pumped into the combustion chamber after the exhaust is closed, and at least at some high engine load, at least some of the metered amount of fuel is 80
A method is disclosed that includes injecting a metered amount of fuel directly into the combustion chamber such that the% is pumped into the combustion chamber prior to closing the exhaust.

[Problems to be solved by the device]

In a two-cycle internal combustion engine, the amount of burnt residual gas in the combustion chamber increases at low load, so if the fuel spray is diffused throughout the combustion chamber, the air-fuel mixture becomes lean and the ignitability deteriorates.
Also, combustion becomes unstable. Therefore, the fuel injection is directed to the upper space of the combustion chamber to form a relatively high-concentration air-fuel mixture in the vicinity of the spark plug to improve ignitability and combustion stability.

However, when fuel is injected near the spark plug, during medium load operation of the engine, the mixture concentration becomes excessive near the spark plug and the initial combustion speed is accelerated, so the combustion pressure rises rapidly and combustion noise and knocking occur. In addition to being easy to generate, a large amount of fuel spray concentrates near the spark plug at high load, so uniform combustion cannot be obtained in the entire combustion chamber, resulting in reduced output or smoldering of the spark plug. Comes out.

Therefore, in order to obtain good combustion over the entire load range of the engine, it is necessary to concentrate the fuel spray near the spark plug when the engine load is low and to evenly spread the fuel spray throughout the combustion chamber when the engine load is high. Become.

This problem occurs not only in the 2-cycle internal combustion engine but also in the 4-cycle internal combustion engine.
-500322 cannot be solved by the fuel injection method.

[Means for solving the problem]

According to the present invention, it is provided with the first and second fuel injection ports that are open to the inner wall of the combustion chamber of the internal combustion engine and the engine load detection means, and when the engine is under a low load operation, the first fuel injection port is connected to the first fuel injection port. Fuel is injected toward the upper space of the combustion chamber, and during operation of the engine at medium and high load, fuel is injected from the second fuel injection port toward the lower space of the combustion chamber and the first space
There is provided a fuel injection device for an internal combustion engine, which is characterized by reducing the amount of fuel injected from the fuel injection port.

[Action]

During engine low load operation, fuel is injected from the fuel injection port that directs to the upper space of the combustion chamber, so a rich air-fuel mixture is formed near the spark plug even if a small amount of fuel is injected. Also, during the institution,
During high-load operation, fuel is injected from the fuel injection port that is directed toward the lower part of the combustion chamber toward the center of the combustion chamber, so that a large amount of fuel can be uniformly diffused throughout the combustion chamber.

〔Example〕

1 and 2 show a case where the present invention is applied to a two-cycle engine having an intake / exhaust valve. In the figure, 1 is a cylinder block, 2 is a piston, 3 is a cylinder head,
4 is a combustion chamber formed between the piston 2 and the cylinder head 3, 5 is a pair of air supply valves, 6 is an air supply port, 7 is a pair of exhaust valves, 8 is an exhaust port, and 9 is a cylinder head. 3 shows a spark plug arranged substantially in the center of FIG. In the present embodiment, the peripheral wall of the valve seat of the intake valve 5 on the exhaust valve side forms a pair of mask walls 10 extending in an arc shape along the periphery of the intake valve 5, and the intake valve 5 is fully opened. The exhaust valve side of the opening formed between the valve body of the air supply valve 5 and the valve seat is closed. Therefore, the inflowing fresh air descends from the air supply valve 5 along the cylinder wall on the air supply valve 5 side to form a transverse scavenging airflow that flows along the top surface of the piston. Further, fuel injection ports 22 and 23 of the fuel injection valves 20 and 21 are opened at the peripheral edge of the inner wall of the cylinder head 3. In this embodiment, as shown in FIG. 1, the fuel injection port 22 of the fuel injection valve 20 has its central axis A directed toward the vicinity of the spark plug 9 above the combustion chamber 4, and the fuel injection of the fuel injection valve 21. The mouth 23 is arranged such that its central axis B points toward the lower part of the combustion chamber 4 in the state where the piston 2 is at the bottom dead center.

In this embodiment, the fuel injection valves 20 and 21 are air blast valves that inject fuel together with compressed air, and the fuel injection valves 20 and 21 have the same structure.

FIG. 3 shows the structure of the fuel injection valve. FIG. 3 shows the fuel injection valve 21, but the fuel injection valves 20 and 21 are exactly the same in structure except for the mounting angle to the cylinder head.

In the figure, the fuel injection valve 21 is provided with a fuel injection passage 31 that extends almost straight, and one end of the fuel injection passage 31 opens to the inner wall of the cylinder head 3 to form a fuel injection port 22. Further, 32 is a valve body for opening and closing the fuel injection port 22, one end of which extends in the fuel injection passage 31 and is connected to an electromagnetic actuator 33 for opening and closing. The valve body 32 always closes the fuel injection port 22 by the compression spring 34, and the electromagnetic actuator
Only when the solenoid 35 of 33 is energized, it is displaced toward the combustion chamber 4 to open the fuel injection port 22. Further, reference numeral 36 is a nozzle chamber, and an injection nozzle 38 of a fuel valve 37 is opened inside thereof, and fuel is injected in the axial direction of a compressed air outlet passage 39 connecting the nozzle chamber 36 and the fuel injection passage 31. To be done.

A compressed air source such as an engine-driven air pump 41 is connected to the nozzle chamber 36 via a compressed air inlet passage 40. The compressed air inlet passage 40, the nozzle chamber 36, the compressed air outlet passage 39 and the fuel injection passage. Fill 31 with compressed air.

An electromagnetic actuator 33 for opening and closing the valve element 32 and a fuel valve
The operation of 37 is controlled by the electronic control unit 42 based on the engine intake air amount detected by the air flow meter 43 and the engine rotation speed detected by the rotation speed sensor 44 as described later. Fuel is injected from the nozzle 38 into the fuel injection passage 31 along the axis of the compressed air outlet passage 39, and then the electromagnetic actuator 33 drives the valve body 32,
The fuel injection port 22 is opened. When the fuel injection port 22 is opened, fuel is injected from the injection port 22 into the combustion chamber 4 together with the compressed air in the form of fine spray. The fuel injection amount is adjusted by changing the opening time of the fuel valve 37.

In this embodiment, the engine intake air amount Q detected by the air flow meter 43 is used as a parameter representing the engine load.
To the engine speed N detected by the engine speed sensor 44 Q /
Based on N, the operation of the fuel injection valves 20 and 21 is switched by the electronic control unit 42 described above.

FIG. 4A shows an example of setting the operating regions of the fuel injection valves 20 and 21. In this example, when the load Q / N is a set value L (L is a value at which the engine load is about 20% of the maximum load) or less, the fuel injection valve 20 operates and the fuel is near the spark plug 9 above the fuel chamber 4. Be sprayed on. When the engine load is low, the flow velocity of the fresh air flowing from the intake valve is low, and the transverse scavenging air flow is weak.
The fuel injected from 20 does not diffuse and a relatively rich air-fuel mixture is formed in the vicinity of the spark plug 9, improving the ignitability. Further, when the load increases and Q / N exceeds L and enters the middle and high load region, the fuel injection valve 20 stops operating, the fuel injection valve 21 operates, and the fuel is directed toward the center of the combustion chamber 4. Is jetted. In the medium-high load region, the fresh air flowing in from the intake valve 5 forms a strong transverse scavenging flow, so a large amount of fuel injected from the fuel injection valve 21 toward the center of the fuel chamber 4 is evenly distributed throughout the combustion chamber. Can be diffused into. Therefore, the high-concentration air-fuel mixture does not concentrate near the spark plug 9 and the initial combustion speed does not become excessive in the medium load region, so that combustion noise and knocking do not occur. Further, smoldering of the spark plug 9 does not occur in the high load region, and a uniform combustion state can be obtained in the entire combustion chamber.

Further, in this embodiment, the fuel injection valves 20 and 21 are near Q / N = L.
The operating regions of the fuel injection valves 20 and 21 are overlapped in the vicinity of Q / N = L so that fuel injection is not temporarily interrupted when and are switched.

FIG. 4B shows another embodiment of setting the operating region of the fuel injection valves 20 and 21, and in this embodiment, only the fuel injection valve 20 operates in the low load region of Q / N = L or less, and Q Both the fuel injection valves 20 and 21 operate in the medium / high load region of / N = L or more. In this way, the air-fuel mixture formed in the combustion chamber 4 by simultaneously injecting fuel from both fuel injection valves is further homogenized, and combustion is further stabilized. However, in this case, the spark plug 9
In order to prevent the generation of smolder and combustion noise, it is necessary to reduce the fuel injection amount from the fuel injection valve 20 so that the fuel concentration of the air-fuel mixture near the spark plug 9 does not become excessive.

In the above embodiment, the case where the air blast valve is used for the fuel injection valves 20 and 21 has been described, but the fuel injection valve may be of a type other than the air blast valve. The present invention can be applied not only to a 2-cycle internal combustion engine but also to a 4-cycle internal combustion engine.

[Effect of device]

According to the present invention, which is configured as described above, stable combustion can be obtained over the entire load range of the engine from low load to medium and high load, combustion noise and knocking at medium load, and high load. Smoldering of the spark plug can be effectively prevented.

[Brief description of drawings]

FIG. 1 is a side sectional view showing an embodiment of the present invention, FIG. 2 is a view of a cylinder head of the same embodiment, FIG. 3 is a partial sectional view of a fuel injection valve of the same embodiment, and FIG. 4A is a fuel. One embodiment of setting the operating area of the injection valve, FIG. 4B shows another embodiment of setting the operating area of the fuel injection valve. 4 ... Combustion chamber, 5 ... Air supply valve, 7 ... Exhaust valve, 20, 21 ...
… Fuel injection valve, 22, 23 …… Fuel injection port, 31 …… Fuel injection passageway, 32 …… Valve body, 33 …… Electromagnetic actuator, 37 ……
Fuel valve, 42 ... Electronic control unit, 43 ... Air flow meter, 44 ... Rotation speed sensor.

Continuation of front page (51) Int.Cl. ⁶ Identification number Office reference number FI technical display area F02M 67/02 F02M 67/02

Claims (1)

(57) [Scope of utility model registration request] 1. A first and a second fuel injection port opening to the inner wall of a combustion chamber of an internal combustion engine, and an engine load detection means, wherein the combustion is performed from the first fuel injection port during engine low load operation. Fuel is injected toward the upper space of the chamber, and during operation of the engine at medium and high loads, fuel is injected from the second fuel injection port toward the lower space of the combustion chamber and is injected from the first fuel injection port. A fuel injection device for an internal combustion engine, which is characterized by reducing the amount of fuel to be used.