JPH10159619A - Fuel injection device for engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To form an air-fuel mixture even around the spark plug of a combustion chamber by arranging the position of the fuel injection nozzle hole of a fuel injection valve on the circumferential edge part of the combustion chamber on the intake port side viewing from the axial direction of a cylinder, beginning fuel injection at the first half of an intake stroke, and injecting fuel dividedly into a plurality of times in the intake stroke. SOLUTION: A spark plug 15 is arranged on the top part of the combustion chamber 2 of an engine, namely the center part of a combustion chamber viewing from the axial direction of a cylinder, meanwhile a fuel injection valve 16 is arranged on the side part of the combustion chamber 2 against the spark plug 15 so that an intake port 5a is sandwiched with the spark plug 15 and the fuel injection valve 16, and the position of the fuel injection nozzle hole of the fuel injection valve 16 is arranged on the circumferential edge part of the combustion chamber 2 on the intake port 5a side viewing from the axial direction of a cylinder. By injecting fuel from the fuel injection valve 16, for example dividedly into injection begun from the first half of the intake stroke and injection at the second half of the intake stroke, the fuel is uniformly diffused in the whole combustion chamber 2, and uniformalization of air-fuel mixture is promoted so as to improve combustibility of the engine.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fuel injection device for an engine, and more particularly, to injecting fuel so as to form a uniform mixture around a spark plug in a combustion chamber, thereby making the mixture more uniform. It belongs to the technical field although it is designed.

[0002]

2. Description of the Related Art In general, in order to perform stratified combustion of an air-fuel mixture of an engine, a fuel injection valve is disposed facing a combustion chamber of the engine as disclosed in, for example, Japanese Utility Model Laid-Open No. 58-2363. There is known a fuel injector in which fuel is supplied from a fuel injection valve to the vicinity of an ignition plug so that a rich mixture is unevenly distributed around the ignition plug of a combustion chamber, thereby enabling stratified combustion of the mixture.

[0003]

In order to perform good combustion in the combustion chamber of the engine, it is necessary to form a uniform air-fuel mixture in the entire combustion chamber. If the injection valve is used to inject fuel in the middle of the intake stroke, it is difficult for fuel spray to reach the vicinity of the ignition plug located at a position distant from the main flow of intake air sucked by the piston heading to the bottom dead center, and the entire combustion chamber It is difficult to have a high degree of uniformity of the fuel, and it is inevitable that the degree of uniformity decreases. Therefore, separately from the fuel injection valve provided in the combustion chamber, a fuel supply means for forming a fuel spray around the ignition plug is required.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and has as its object to form an air-fuel mixture around a spark plug of a combustion chamber while using one fuel injection valve provided in the combustion chamber of the engine. An object of the present invention is to make it possible to favorably form a uniform air-fuel mixture throughout the combustion chamber.

[0005]

In order to achieve the above object, according to the present invention, the fuel injection from the fuel injection valve facing the combustion chamber is performed a plurality of times in the intake stroke so that the combustion chamber is divided in the intake stroke. While the fuel injection valve is configured to inject fuel, a mixture can be formed also around the ignition plug in the combustion chamber.

More specifically, according to the first aspect of the present invention, when viewed from the cylinder axis direction, the ignition plug is disposed at the center of the combustion chamber, and the fuel injection valve for injecting fuel is provided in the combustion chamber. Assume an injection device.

The position of the fuel injection port of the fuel injection valve is located at the periphery of the combustion chamber on the intake port side when viewed from the cylinder axis direction. Further, there is provided injection control means for controlling the fuel injection valve so that fuel injection is started in the first half of the intake stroke of the cylinder and fuel is dividedly injected a plurality of times in the intake stroke.

[0008] With the above configuration, the injection control means 1
By dividing and injecting the fuel from the two fuel injection valves into, for example, injection starting in the first half of the intake stroke and injection in the second half of the intake stroke, the fuel can be uniformly diffused throughout the combustion chamber. For this reason, while using one fuel injection valve facing the combustion chamber, the diffusivity of the fuel in the entire combustion chamber can be increased, and the uniformity of the air-fuel mixture can be promoted, so that the combustibility of the engine can be improved.

According to the second aspect of the present invention, the flow of the intake air generated in the combustion chamber of the engine is utilized so that the fuel injected from the fuel injection valve rides on the flow of the intake air. In this case, the injected fuel spreads in the combustion chamber along with the flow of the intake air, so that the uniformity of the air-fuel mixture can be further promoted by diffusing the air-fuel mixture throughout the combustion chamber and promoting the vaporization and atomization of the fuel.

[0010]

FIG. 1 shows an overall structure of a fuel injection device for an engine according to an embodiment of the present invention. Reference numeral 1 denotes an engine, and 2 denotes a piston 4 slidably fitted into a cylinder 3 of the engine 1. A combustion chamber 5 having a variable volume has one end communicating with the atmosphere via an air cleaner 6 and the other end opening to the combustion chamber 2 to supply intake air, and 7 has one end connected to the combustion chamber 2. The other end is open to the atmosphere and is an exhaust passage for discharging exhaust. The intake passage 5 is provided with a throttle valve 8 for adjusting the amount of intake air, while the exhaust passage 7 is provided with a catalyst device 10 for purifying exhaust gas.

In the combustion chamber 2, an intake valve 12 is provided at an opening (intake port 5a) of the intake passage 5, and an exhaust valve 13 is provided at an opening (exhaust port 7a) of the exhaust passage 7.
Are arranged respectively. And the above intake port 5
The intake air from a generates an intake air flow in the combustion chamber 2. Further, at the top of the combustion chamber 2, that is, at the center of the combustion chamber 2 when viewed from the axial direction of the cylinder 3,
An ignition plug 15 for igniting the air-fuel mixture is arranged.

Further, a fuel injection valve 16 for injecting fuel into the combustion chamber 2 is disposed on a side of the combustion chamber 2 so as to face the combustion chamber 2. The fuel injection valve 16 is disposed at such a position as to sandwich the intake port 5a between the ignition plug 15 and the fuel injection valve 16 with respect to the ignition plug 15, and a fuel injection port (described later) of the fuel injection valve 16 is provided. The position of the leading end opening 16c1) is located at the periphery of the combustion chamber 2 on the intake port 5a side when viewed from the axial direction of the cylinder 3.

In addition, reference numeral 20 denotes an air flow sensor for detecting an intake air amount upstream of the throttle valve 8, reference numeral 21 denotes an intake air temperature sensor for detecting intake air temperature, and reference numeral 22 denotes a throttle valve 8.
, A negative pressure sensor for detecting the intake negative pressure downstream of the throttle valve 8, and a negative pressure sensor 25 disposed on the upstream side of the catalyst device 10 in the exhaust passage 7, based on the oxygen concentration component in the exhaust gas. An air-fuel ratio sensor 26 for detecting an air-fuel ratio is a rotation speed sensor for detecting the rotation angle (that is, engine rotation speed) of the signal disk plate 1a connected to the output shaft of the engine 1 and rotating synchronously. Although not shown, a water temperature sensor for detecting the temperature of the cooling water of the engine 1 is provided.

The above sensors 20 to 23, 2
5 and 26 (intake air amount signal ISa, intake temperature signal ISt, throttle valve opening signal ISh, intake negative pressure signal ISb, cooling water temperature signal ISs, air-fuel ratio signal ISo,
The engine speed signals ISn)
0 has been entered. The controller 30 is internally provided
Input / output port 31 for each of the above detection signals and control signals, RO
An M32, a RAM 33 and a CPU 34 are provided, and the controller 30 controls the operation of the fuel injection valve 16.

Next, a specific configuration of the fuel injection valve 16 is shown in FIG. The fuel injection valve 16 internally supplies a fuel supply unit 16a that injects an amount of fuel according to a control signal (injection pulse) transmitted from the controller 30.
And a supply control unit 16b for controlling the supply of the fuel supplied from the fuel supply unit 16a to the engine combustion chamber 2 and the stop thereof. The former fuel supply unit 16a is provided in FIG.
As shown in the figure, the fuel tank 37 is connected to a fuel tank 37 via a fuel supply pipe 36 provided with a fuel injection pump 35 interposed therebetween.

On the other hand, in FIG. 2, the latter supply control unit 1
A fuel injection passage 16c is formed in the center of the fuel injection passage 6b along an extension of the axis of the fuel supply portion 16a. The rear end of the fuel injection passage 16c is connected to the fuel supply section 16a.
The front end faces the combustion chamber 2 of the engine 1. The fuel supplied from the fuel supply section 16a is supplied to the fuel supply passage 1c by the fuel injection passage 16c.
The fuel is injected into the combustion chamber 2 via 6c, and this fuel amount is supplied around the ignition plug 15.

Further, a pressurized air passage 16d which intersects the axis of the fuel supply portion 16a at a predetermined narrow angle at the rear end of the fuel injection passage 16c is opened in the supply control portion 16b. As shown in FIG. 1, the pressurized air passage 16 d is connected to a pressurized air accumulation tank 39 via a pressurized air intake air amount passage 38, and the pressurized air tank 39 is provided upstream of the air flow sensor 21. Pressurized air is accumulated by the operation of the air pump 41 provided in the air introduction passage 40 communicating with the intake passage 5 on the side.

Further, referring to FIG.
A control valve 16e that opens and closes the fuel supply passage 16c at a front end opening 16c1 as a fuel injection port having a shape that opens obliquely outward is disposed at the front end of c. The control valve 16
e has a poppet valve 16f for opening and closing the tip opening 16c1, and the poppet valve 16f is connected to the tip opening 1c.
The valve body 16f1 is detachably seated on the valve body 6c1 and a spring 16f2 for urging the valve body 16f1 in the seating direction. A hollow pressing member 16g is arranged at the rear end of the valve element 16f1 of the poppet valve 16f, and an excitation coil 16h for moving the pressing member 16g in the front-rear direction by electromagnetic force is provided outside the pressing member 16g. Is arranged. When the exciting coil 16h is energized, the pressing force of the pressing member 1 is increased by the electromagnetic force.
6g is moved forward, and the valve element 16f of the poppet valve 16f is moved.
1 is disengaged against the urging force of the spring 16f2 to open the poppet valve 16f, thereby opening the front end opening 16c1 of the fuel supply passage 16c and allowing fuel or air-fuel mixture to flow therethrough. When the exciting coil 16h is not energized, the valve body 16f1 of the poppet valve 16f is moved rearward together with the pressing member 16g by the urging force of the spring 16f2 to seat the poppet. The valve 16f is closed, the tip opening 16c1 of the fuel supply passage 16c is closed, and the supply of fuel to the combustion chamber 2 is stopped.

The control valve 16 of the fuel injection valve 16 is used.
"e" indicates that fuel is dividedly injected twice in the intake stroke of the cylinder 3 and the injected fuel is supplied to the intake port 5 of the engine 1.
The intake air flow generated in the combustion chamber 2 by the intake air from a. The injection timing of each of the two divided injections of fuel is such that the central timing of the first and second divided injections is earlier than the central timing of the intake stroke (approximately 90 ° crank angle after top dead center of the piston). Thus, the two divided injections are set so as to be shifted to the front side of the intake stroke as a whole, that is, the first fuel injection is set in the early part of the first half of the intake stroke, and the second fuel injection is set in the early part of the second half of the intake stroke. ing.

More specifically, the control valve 16e is controlled by the controller 30 at a predetermined time when the flow of intake air in the first half of the intake stroke is relatively small and the intake air flow rate is small, as indicated by the symbol A in the fuel injection timing characteristic diagram shown in FIG. Open control is performed to supply a part of the fuel around the ignition plug 15 of the combustion chamber 2 and, at a predetermined time when the intake air flow is relatively large and the intake air flow rate is large in the latter half of the intake stroke, the symbol B in FIG. Open control is similarly performed by the controller 30 as shown,
A larger amount of fuel is supplied to the combustion chamber 2 than the fuel supply amount in the first half of the intake stroke.

The specific operation control of the control valve 16e will be described. As shown in FIG. 4, the poppet valve 16f is controlled to open at a predetermined time in the latter half of the intake stroke, and fuel is supplied when the poppet valve 16f is opened. The opening (operation) of the portion 16a is controlled, and the fuel supplied from the fuel supply portion 16a is supplied with pressurized air to open the front end portion 16c of the fuel supply passage 16c.
1 to the combustion chamber 2. After the closing control of the poppet valve 16f, the fuel supply unit 16a is opened (operated) for a short period of time so that the supplied fuel is stored in the tip opening 16c1 of the fuel supply passage 16c. In this state, only the poppet valve 16f is controlled to be opened in the first half of the next intake stroke, and the fuel accumulated in the tip opening 16c1 is supplied around the ignition plug of the combustion chamber 2 by pressurized air.

With the configuration of the controller 30 as described above, the fuel injection valve 16 (specifically, the control valve 16e) is controlled so that fuel is injected twice in the intake stroke of the cylinder 3, and the intake stroke in the first half of the intake stroke is controlled. At a predetermined time when the flow is small, a part of the fuel is injected around the spark plug 15 of the combustion chamber 2, and the fuel injection valve 16 is operated so as to inject the fuel into the combustion chamber 2 at a predetermined time when the intake flow is large in the latter half of the intake stroke. The injection control means 42 is constituted.

Therefore, in the above-described embodiment, at a predetermined time in the first half of the intake stroke, the poppet valve 16f of the fuel injection valve 16 is controlled to open by the combustion control means 42, and accumulates in the tip opening 16c1 of the fuel supply passage 16c. The fuel is injected toward the ignition plug 15 around the combustion chamber 2 while being pressurized by the pressurized air, and the first fuel injection is performed. At the time when the injected fuel passes through the intake port 5a, the flow of the intake air supplied from the intake port 5a is small. Therefore, as shown in FIG. And adheres to the wall surface of the combustion chamber 2 near the ignition plug 15. Thereafter, as time passes, atomization and diffusion gradually occur near the spark plug 15.

In the latter half of the intake stroke, the operation of the fuel injection valve 16 is again controlled by the injection control means 42, fuel is supplied from the fuel injection valve 16, and the second fuel injection is performed. However, in this case, since the flow of the intake air is large, the injected fuel is pushed away by the intake air from the intake port 5a as shown in FIG. It is pushed and bent and diffuses uniformly throughout the combustion chamber 2 as the intake stroke progresses.

As a result, the fuel supplied in the first half of the intake stroke is located near the ignition plug 15 in the combustion chamber 2, the rich mixture is unevenly distributed in the vicinity of the ignition plug 15, and the fuel supplied in the second half of the intake stroke is Is uniformly diffused throughout the combustion chamber 2, and the fuel diffusivity throughout the combustion chamber 2 is increased. As a result, uniformity of the air-fuel mixture in the entire combustion chamber 2 is promoted, and the combustibility of the engine 1 can be improved by promoting such uniformity of the air-fuel mixture.

In the above embodiment, the fuel injection valve 16
Is constituted by a two-fluid type fuel injection valve capable of supplying pressurized air together with the fuel, but it is needless to say that it may be constituted by a normal fuel injection valve which supplies only the fuel.

[0027]

As described above, according to the fuel injection system for an engine of the first aspect of the present invention, one fuel injection valve provided in the combustion chamber is divided into a plurality of times during the intake stroke of the cylinder. By performing the fuel injection, the fuel injection from the fuel injection valve is divided into at least two times, the injection starting from the first half of the intake stroke and the injection in the second half of the intake stroke, and the fuel is injected into the entire combustion chamber. It is possible to uniformly diffuse the fuel and increase the diffusibility of the fuel in the entire combustion chamber while using one fuel injection valve facing the combustion chamber, thereby promoting the uniformity of the air-fuel mixture and improving the combustibility of the engine. .

According to the second aspect of the present invention, the fuel injected from the fuel injection valve is carried on the flow of the intake air in the combustion chamber, thereby promoting the diffusion of the air-fuel mixture below the combustion chamber and the vaporization and atomization of the fuel. This further promotes the homogenization of the air-fuel mixture and further improves the combustibility of the engine.

[Brief description of the drawings]

FIG. 1 is a diagram showing an overall schematic configuration of a fuel injection device for an engine according to an embodiment of the present invention.

FIG. 2 is a sectional view of a main part showing a specific configuration of a fuel injection valve arranged in a combustion chamber of an engine.

FIG. 3 is a diagram showing fuel injection timing characteristics.

FIG. 4 is a diagram showing a temporal operation relationship of a fuel supply unit and a poppet valve in a fuel injection valve arranged in a combustion chamber of an engine.

FIG. 5 is a diagram illustrating the operation of fuel injection.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Engine 2 Combustion chamber 5a Intake port 15 Spark plug 16 Fuel injection valve 16a Fuel supply section 16c Fuel supply passage 16c1 Tip opening 16e Control valve 16f Poppet valve 30 Controller 42 Injection control means

────────────────────────────────────────────────── ─── Continued on the front page (51) Int.Cl. ⁶ Identification code FI F02M 57/06 F02M 57/06 61/14 310 61/14 310S

Claims (2)

[Claims] 1. A fuel injection device for an engine in which an ignition plug is disposed at a central portion of a combustion chamber as viewed from a cylinder axis direction and a fuel injection valve for injecting fuel is provided in the combustion chamber. The position of the injection port is located at the periphery of the combustion chamber on the intake port side when viewed from the cylinder axis direction, and fuel injection is started in the first half of the cylinder intake stroke.
A fuel injection device for an engine, further comprising injection control means for controlling the fuel injection valve so that fuel is split and injected a plurality of times during an intake stroke. 2. The engine fuel injection system according to claim 1, wherein the fuel injected from the fuel injection valve rides on the flow of intake air generated in the combustion chamber. Injection device.