JPH03100368A - Fuel injection device of internal combustion engine - Google Patents

Abstract

PURPOSE:To improve the stability of ignition and the propagation of a flame by forming external shape of a valve shaft part asymmetrically about the center of a poppet valve and drive-rotating it in accordance with an operational condition so as to increase distribution of fuel in the vicinity of a spark plug at the time of at least low load operation. CONSTITUTION:When a poppet valve 4 is opened by a solenoid 6, supplied fuel to a passage 7 from a fuel supply valve 8, while being mixed with pressure air supplied to the passage 7 from an air introducing hole 12, is energetically jetted from the point end of a nozzle part 3. Here a flow amount is increased in a side of larger passage sectional area in the periphery of the valve 4, and a fuel atomized amount from a nozzle part 2A is increased in a side of larger sectional area of the passage 7 as shown by a two-dot chain line. Accordingly, by holding the valve shaft part 4A of the valve 4 in a rotational position apart from a spark plug 27 by a control circuit 35, during low speed/low load operation a region E toward the spark plug 27 is enlarged in a jet flow to a combustion chamber 19 from the passage 7 with ignitability stabilized simultaneously with stratified combustion performed by uniformly propagating a flame.

Description

[Detailed description of the invention] (Industrial application field) The present invention relates to a fuel injection position for an internal combustion engine.

(Prior Art) In order to improve the output performance and exhaust performance of two-stroke engines and the like, it has been considered to inject fuel directly into the combustion chamber.

Therefore, in order to achieve good mixing of the conventionally injected fuel with the atomized intake air, a fuel injection device has been proposed that injects the fuel together with a predetermined amount of pressurized air, as shown in FIG. (Refer to JP-A-62-93481).

To explain this, the fuel injection device 1 has a body 2
The elongated nozzle part 3 attached to the body 2 and the nozzle,
A poppet valve 4 that penetrates the nozzle portion 3 to open and close the tip of the nozzle portion 3, a disc spring 5 that biases the poppet valve 4 in the closing direction, and a solenoid 6 that opens the poppet valve 4.
, an annular mixing passage 7 formed around the poppet valve 4 , and a fuel supply valve 8 attached to the side of the body 2
The fuel sent from the fuel pump 9 to the fuel supply valve 8 passes through a supply chamber 10 with a predetermined volume to the mixing passage 7, and the pressurized air sent from a pressurized air supply source 11 such as a near compressor is The air is supplied to the mixing passage 7 through the air introduction hole 12 located behind the supply chamber 10.

Therefore, when the poppet valve 4 is opened by the solenoid 6, the fuel supplied from the supply chamber 10 to the mixing passage 7 is mixed with the pressurized air supplied from the air introduction hole 12 to the mixing passage 7, The fuel is vigorously ejected from the tip, which promotes atomization of the fuel in a very short period of time, resulting in good mixing with the intake air.

In addition, 13 is a fuel tank, 14 and 15 are pressure regulators, 16 is an engine rotation sensor, 17 is an engine load sensor, and 18 is based on these signals to drive the solenoid 6 upstream fuel supply valve 8 to control the fuel supply. This is a control circuit that controls the injection amount and injection timing.

(Problems to be Solved by the Invention) However, in the combustion chamber of a spark-ignition internal combustion engine in which the 7, 2' nozzle portions 3 of the fuel injection device 1 are installed in line with the spark plug, the jet flow containing fuel is transmitted to the nozzle portion 3. Since the fuel is ejected radially around the ignition plug, if the fuel supply amount decreases during low-speed, low-load operation, the distribution of fuel will decrease even in the area near the ignition plug, worsening ignition stability and flame propagation, resulting in lower fuel consumption and lower fuel consumption. There was a problem in that it caused an increase in exhaust emissions.

The present invention aims to solve these conventional problems.

(Means for solving the problem) In order to achieve the dual purpose, the present invention includes a port that opens into the combustion chamber, and a poppet valve that is inserted into this port to open and close the opening of the port on the combustion chamber side. Equipment, ;t: -)
,! : Hohey) t(Ruff (7) valve!mMz6Q
rJl+:: In a fuel injection device for an internal combustion engine, which defines a passage and is configured to inject fuel together with pressurized air from a port into a combustion chamber by opening a poppet valve, the valve stem is located at the center of the Moeki poppet pulp. The outer shape of the poppet valve is asymmetrically formed, and a control means is provided to rotate the poppet valve according to the operating conditions so as to enhance the fuel distribution in the vicinity of the α powder at least during low load operation.

(Function) Based on the above configuration, when the poppet valve is opened, in the process in which fuel and air flow through the passage while mixing, the flow rate increases on the side with a larger cross-sectional area of the passage around the poppet valve, so the combustion chamber There is also a bias in the distribution of fuel ejected. Therefore, by changing the rotational position of the poppet valve according to operating conditions, the distribution of fuel around the ignition plug can be improved during low-speed, low-load operation, promoting ignition stability and flame propagation, reducing fuel consumption. While reducing exhaust emissions, the spark plug and anti-NIi during high-speed, high-load operation! I
By increasing the fuel distribution of I, the air inside the m combustion chamber is effectively used, and unburned fuel flowing into the exhaust port can be reduced.

(Example) Hereinafter, an example of the present invention will be described based on FIG. 1. Note that the same reference numerals are given to parts that are substantially the same as those of the conventional example.

In the two-stroke engine 21, fuel is injected together with pressurized air from the fuel injection device 1 while the piston 23 is rising, and near the top dead center, the ignition plug 27 ignites the air-fuel mixture to cause combustion. As the piston 23 descends, the exhaust port 25 and the scavenging port 24 open in the sill 22, and combustion gas is discharged from the exhaust port 25, and air sent from the crank chamber passes through the scavenging port 24 and flows into the combustion chamber 19. There is an inflow into the country.

/Glue 112A of the fuel injection device 1 in the cylinder head 26
, the spark plugs 27 are installed side by side and 1. The ignition plug 27 is disposed approximately on the center line of the cylinder 22, and is connected to the fuel injection device 1.
The nozzle portion 2A is disposed between the ignition plug 27 and the scavenging port 24 toward the center of the combustion chamber 19.

As shown in FIG. 2, in the fuel injection device 1, a nozzle portion 2A formed integrally with a body 2 fits into a shilling head 26, and a port 29 penetrating the body 2 is connected to a combustion chamber 19.
Open to. The valve stem portion 4A of the poppet valve 4 is inserted into the port 29, and the umbrella portion 4B formed at the tip of the poppet valve 4 is inserted into the seat portion 29 formed at the open end of the port 29.
4 AIs are seated to open and close this.

y) A disc spring 5 is connected to the base end 4C of the valve shaft 4A of the valve 4 via a nut 31 that biases it in the closing direction, and the poppet valve 4 is moved in the opening direction against the disc spring 5. A solenoid 6 is provided to drive the motor.

A passage 7 having an annular cross section is defined between the port 29 and the valve stem portion 4A of the poppet valve 4. A fuel supply valve 8 is connected in the middle of this passage 7 via a supply chamber 10 having a predetermined volume, and pressurized air from a near compressor or the like is supplied via a pipe 12.

The valve stem portion 4A of the poppet valve 4 is formed eccentrically with respect to the base end portion 4C and the umbrella portion 4B, and as shown in Figure @3, the cross-sectional area of the passage 7 is on the opposite side from which the valve stem portion 4A is eccentric. It becomes large in a crescent shape in some parts.

Incidentally, as shown in FIG. 4, the valve stem portion 4A of the poppet valve 4 may be formed to have a crescent-shaped cross section to partially enlarge the cross-sectional area of the passage 7.

As a means for rotationally driving the poppet valve 4, its base J
A motor 33 is connected to the IS4C via a nut 32.

The control circuit 35 inputs the detection signals of the rotation sensor 16 and the opening sensor 17 of the throttle valve 34, and controls the motor 3.
3 to poppet valve 4 during predetermined low speed and low load operation.
The valve stem 4A is switched to a rotational position where the valve stem 4A moves away from the ignition plug 27 under other operating conditions, and the valve stem 4A is switched to a rotational position where the valve stem 4A approaches the ignition plug 27 under other operating conditions.

Next, the effect will be explained.

When the poppet valve 4 is opened by the valve/id 6, the fuel supplied from the fuel supply valve 8 to the passage 7 mixes with the pressurized air supplied to the passage 7 from the air introduction hole 12 and reaches the tip of the nozzle part 3. Force erupts often from the part.

In the process where fuel and pressurized air flow through the passage 7 while mixing,
Around the poppet valve 4, the flow rate is larger on the side with a larger cross-sectional area of the passage, so the amount of fuel injected from the nozzle part 2A is larger on the side with a larger cross-sectional area of the passage 7, as shown by the two-point iA line in FIG. More on the side.

Therefore, when the valve stem 4A of the poppet valve 4 is held in a rotational position where it moves away from the spark plug 27 during low speed and low load operation, the jet jet ejected from the passage 7 into the combustion chamber 19 has a force directed toward the spark plug 27 (PIS 1). (indicated by the shaded area E) increases. This improves the distribution of fuel around the spark plug 27 in the combustion chamber 19, stabilizing the ignitability, and the flame propagates evenly to the opposite side of the spark plug 27 from the nozzle portion 2A, resulting in stratified combustion. This can reduce fuel consumption and exhaust emissions.

On the other hand, during high-speed, high-load operation, the valve stem 4 of the poppet valve 4
When A is held in a rotational position close to the ignition plug 27, the distribution of fuel injected from the nozzle portion 2A is reversed, and the fuel is injected at a point where it crosses the air flow flowing into the combustion chamber 19 from the scavenging port 24. By increasing the force of the fuel (indicated by the shaded area F in FIG. 1), the air in the combustion chamber 19 is effectively used, and the output is improved. In this way, even if the distribution of the fuel injected from the nozzle portion 2A becomes relatively small near the ignition plug 27, the fuel injection amount increases during high-load operation, so that sufficient ignition performance can be obtained.

(Effects of the Invention) As described above, according to the present invention, in a fuel injection device that injects fuel into a combustion chamber together with pressurized air by opening a poppet valve, there is provided a port that opens into the combustion chamber, and a poppet that opens and closes this port. A passage for guiding fuel and air is defined around the valve stem of the valve, and the outer shape of the valve stem is asymmetrical about the center of the poppet valve, so as to enhance fuel distribution near the ignition plug at least during low-load operation. By installing a control means that rotates the poppet valve according to operating conditions, the jet containing fuel ejected from the port into the combustion chamber can increase its force toward the ignition plug during low-load operation, improving ignition efficiency. In addition to ensuring stability, it also promotes flame propagation within the combustion chamber, improving fuel efficiency, output performance, and exhaust emissions.

[Brief explanation of drawings]

FIG. 1 is a longitudinal sectional view of an engine showing an embodiment of the present invention, wII
Figure 2 is a cross-sectional view of the fuel injection system, and figure fJfJ3 is the same figure A-
A sectional view taken along line A, and FIG. 4 is a sectional view showing another embodiment. tIS5 is a configuration diagram showing a conventional example. DESCRIPTION OF SYMBOLS 1... Fuel injection device, 2... Body, 2A... Nozzle part, 4... Poppet valve, 4A... fpId
1 part, 4B... Umbrella part, 4C... Base i part, 5... Belleville spring, 6... Solenoid, 7... Passage, 8... Fuel supply valve, 12... Air Piping, 27...Spark plug, 2
1...port, 33...motor, 35...control circuit. Figure 5

Claims (1)

[Claims] It is equipped with a port that opens into the combustion chamber, and a poppet valve that is inserted into the port to open and close the combustion chamber side opening of the port, and defines a passage between the port and the valve stem of the poppet valve. In a fuel injection device for an internal combustion engine configured to inject fuel together with pressurized air from a port into a combustion chamber by opening the valve, the outer shape of the valve stem portion is formed asymmetrically with respect to the center of the poppet valve, at least during low load operation. 1. A fuel injection device for an internal combustion engine, comprising a control means for rotationally driving a poppet valve according to operating conditions so as to improve fuel distribution near the ignition plug.