JPH06147061A - Fuel injection system of internal combustion engine - Google Patents

Abstract

PURPOSE:To prevent a deposit from sticking to a fuel injection valve due to the spitting of gas to the side of an inlet apssage after combustion to be caused at the time of valve overlapping. CONSTITUTION:An air control valve 28 installed in an air mixture pipeline 27 is opened synchronously with the fuel injection of a fuel injection valve 26 by means of control of an electronic control unit 4 and thereby a part of intake air is sprayed to a nozzle part of the fuel injection valve 26, through which fuel is atomized. In addition, the air control valve 28 is opened by the electronic control unit 4 synchronously with a valve overlapping period when both intake and exhaust valves 10 and 19 of this engine are opened, whereby a part of intake air is sprayed to a nozzle part of the fuel injection valve 26, so any possible sticking of deposits is prevented from occurring.

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 internal combustion engine, and more particularly, to a portion of intake air upstream of a throttle valve for injection holes of the fuel injection valve at a time substantially synchronized with fuel injection. The present invention relates to a fuel injection device configured to supply atomized fuel in the vicinity of a portion to promote atomization of injected fuel and reduce harmful components in exhaust gas.

[0002]

2. Description of the Related Art Conventionally, there has been widely used a fuel injection device for injecting fuel into an intake system of an internal combustion engine from a fuel injection valve to control its operating state. There is a strong demand for a technique that further promotes atomization of the injected fuel in order to prevent the harmful components in the exhaust gas from increasing due to the deterioration of the combustion state. Therefore, in response to this request, for example, Japanese Patent Publication No. 57-5462.
The fuel injection device described in Japanese Patent No. 4 or Japanese Utility Model Laid-Open No. 58-162262 has been proposed.

In these fuel injection systems, in the intake system of an internal combustion engine, the upstream side of the throttle valve and the vicinity of the injection hole of the fuel injection valve are connected by an air pipe, and an air control valve is connected to this air pipe. Provided so that when the fuel injected from the fuel injection valve cannot be expected to be sufficiently atomized, for example, during idle operation of the internal combustion engine, the air control valve is controlled to open and close almost in synchronization with the fuel injection. It is configured. Therefore, at the time of this idle operation or the like, as the air control valve is opened / closed, a part of the intake air near the atmospheric pressure on the upstream side of the throttle valve passes through the air pipe line at a time substantially in synchronism with the fuel injection, and the injection hole portion. It is supplied to the vicinity and collides with the injected fuel to promote its atomization. In this way, since the supply of intake air is limited to the time of fuel injection, as compared with the case where intake air is continuously supplied,
The injected fuel is sufficiently atomized by a large amount of intake air while suppressing the increase of the idle speed. As described above, these techniques are characterized in that the intake air is supplied to the vicinity of the injection hole portion of the fuel injection valve substantially in synchronization with the timing of fuel injection.

[0004]

Here, considering the reliability of the fuel injection valve, the problem that a deposit such as carbon adheres to the injection hole portion of the fuel injection valve with the passage of time and the injection amount decreases. There is a potential. One of the causes of this deposit is the time when the intake valve and the exhaust valve of the internal combustion engine are both open, that is, the gas is blown back to the intake passage side after combustion during the so-called valve overlap period. As a measure against this problem, a method of cleaning the deposit in the injection hole portion by mixing a cleaning agent into the fuel has been adopted in the market.

Although the above-mentioned prior art is devised only from the viewpoint of atomizing the fuel, the present invention aims to improve the above-mentioned potential problems of the fuel injection valve in addition to atomizing the fuel.

[0006]

As shown in FIG. 1, an internal combustion engine fuel injection system according to a first aspect of the present invention includes an operating state detecting means M2 for detecting an operating state of the internal combustion engine M1.
Fuel injection means M provided in the intake system of the internal combustion engine M1 and injecting a predetermined amount of fuel into the intake system according to the operating state of the internal combustion engine M1 detected by the operating state detecting means M2.
3, an air pipe M4 for supplying a portion of intake air flowing through the intake system to the vicinity of the injection point of the fuel injection means M3 by bypassing a throttle valve, and an air pipe M4 provided to the air pipe M4. Opening / closing means M for connecting or disconnecting the pipeline M4
5, during a period substantially in synchronization with the fuel injection of the fuel injection means M3, and when the fuel injection by the fuel injection means M3 is not performed and the load of the internal combustion engine M1 is equal to or less than the medium load, An opening / closing control means M6 for holding the opening / closing means M5 in an open state during a period substantially in synchronization with a valve overlap period in which the exhaust valve and the exhaust valve are both open.

A fuel injection device for an internal combustion engine according to a second aspect of the present invention is the fuel injection device for an internal combustion engine according to the first aspect, wherein an air pipe M4 that bypasses a throttle valve and reaches the opening / closing means M5. Is provided with a pressurizing means for pressurizing the intake air in the air conduit M4, and the opening / closing means 5 is held in an open state during a period substantially synchronized with the valve overlap period even under a high load.

[0008]

According to the first aspect of the invention, fuel is injected from the fuel injection means M3 into the intake system of the internal combustion engine M1 in accordance with the operating state of the internal combustion engine M1 detected by the operating state detection means M2, and the The operation of the internal combustion engine M1 is continued by the fuel, and the opening / closing means M5 is opened by the opening / closing control means M6 during a period substantially synchronized with the fuel injection, so that a part of the intake air is injected through the air pipeline M4. The fuel is supplied to the vicinity of the injection point of the means M3 to promote atomization of the injected fuel, and based on the detection of the operating state detection means M2, the load of the internal combustion engine M1 is equal to or less than the medium load and during the valve overlap period. When the fuel injection means M3 is not injecting fuel, part of the intake air passes through the air conduit M4 and is close to the injection point of the fuel injection means M3 even during the period substantially synchronized with the valve overlap period. It is supplied to, to prevent adhesion of carbon or the like deposits on the injection portion of the fuel injection means M3 by blowback to the intake passage side of the gas after combustion during the valve overlap period.

In the invention of claim 2, the air pipe M4
By arranging the pressurizing means in the valve, it becomes possible to supply air to the vicinity of the injection point of the fuel injection means M3 even when the load is high (for example, when the throttle valve is fully opened). Even during the overlap period, air can be supplied to prevent deposits from adhering to the injection points.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment in which the fuel injection device for an internal combustion engine of the present invention is embodied as a fuel injection device for an engine will be described below.

FIG. 2 is a system configuration diagram of an engine fuel injection apparatus according to an embodiment of the present invention. As shown in FIG. 2, an engine fuel injection device 1 includes an engine 2, an air mixing device 3, and an electronic control device (hereinafter, simply referred to as “EC
U ”). The engine 2 forms a combustion chamber 8 from a cylinder 5, a piston 6 and a cylinder head 7, and an ignition plug 9 is arranged in the combustion chamber 8. The intake system of the engine 2 includes an intake port 11 and an intake pipe 12 that communicate with the combustion chamber 8 through an intake valve 10, a surge tank 13 that absorbs pulsation of intake air,
It is composed of a throttle valve 14 for adjusting the intake air amount and an air cleaner 15. The exhaust system of the engine 2 includes an exhaust port 19 communicating with the combustion chamber 8 via an exhaust valve 18, an exhaust pipe 20, and a catalytic converter 2.
It is composed of 1.

The ignition system of the engine 2 includes an igniter 22 that outputs a high voltage required for ignition, and a distributor 23 that supplies the high voltage generated by the igniter 22 to an ignition plug in conjunction with a crankshaft (not shown). It is configured.

The fuel system of the engine 2 includes a fuel tank 24 for storing fuel, a fuel pump 25 for pumping the fuel, and an electromagnetic fuel injection valve (fuel injector) for injecting the pumped fuel to the intake port 11. It is composed of 26.

The air mixing device 3 introduces a part of the intake air from the upstream side of the throttle valve 14 of the intake pipe 12 to promote atomization of the fuel, and the fuel injection hole portion of the fuel injection valve 26. Air mixture pipeline 2 to be fed nearby
7 and the air mixing conduit 27, the EC
The air control valve 28 is a two-port two-position solenoid valve that opens and closes according to the control of U4 and connects and disconnects the air mixing conduit 27.

The fuel injection device 1 of the engine 2 is provided as a detector on the upstream side of the throttle valve 14 of the intake pipe 12 to measure the intake air amount.
1. An intake air temperature sensor 32 for measuring the intake air temperature, a throttle position sensor 33 for detecting the opening of the throttle valve 14, and an idle switch for detecting the fully closed state of the throttle valve 14 provided inside the air flow meter 31. 34, a water temperature sensor 35 that is arranged in the cooling system of the cylinder block 5a to detect the cooling water temperature, and an oxygen concentration sensor that is provided in the exhaust pipe 20 and outputs an air-fuel ratio signal according to the residual oxygen concentration in the exhaust gas. 36, every 1/12 rotation and every 1/1 rotation of the camshaft of the distributor 23, that is, every 60 degrees in crank angle and 72
A rotation angle sensor 37 that also functions as a rotation speed sensor that outputs a rotation angle signal every 0 degrees is provided. Here, the signal at every 60 ° C. A is the N signal, and the signal at every 720 ° C. A is the G signal.
The signal detects the engine speed Ne, and
The crank angle is detected by the G signal and the N signal.

The detection signal of each sensor and switch is E
Input to the CU 4, the ECU 4 controls the engine 2 and the air mixing device 3. ECU4 is CPU4a, R
A logical operation circuit is configured around the OM 4b and the RAM 4c,
It is connected to the input / output unit 4e via the common bus 4d to perform input / output with the outside.

Next, the structure in the vicinity of the fuel injection hole portion of the fuel injection valve 26 in the air mixing device 3 will be described. FIG. 3 is a partially enlarged cross-sectional view showing the structure in the vicinity of the fuel injection hole portion of the fuel injection valve of the engine fuel injection device according to the embodiment of the present invention.

As shown in the drawing, in the vicinity of the fuel injection hole portion of the fuel injection valve 26, the fuel injection valve 26 and the air mixing conduit 2 are provided.
7 and an air mixing socket 41. A plurality of air injection holes 42 and a fuel injection hole 43 are formed in the air socket 41. Also,
The passage cross-sectional area of the air duct 27 and the air control valve 28 is set to an area larger than the total of the passage cross-sectional areas of the air injection hole portions 42, and as a result, the air injection hole portion 42 has the smallest restriction.

During operation of the engine 2, the inside of the intake port 11 has a negative pressure, while the upstream side of the throttle valve 14 is maintained at a pressure close to atmospheric pressure. Therefore, due to the differential pressure, when the air control valve 28 is opened,
A part of the intake air upstream of the throttle valve 14 in the intake pipe 12 flows down from the air mixing conduit 27 into the air mixing socket 41 (hereinafter, the intake air at this time is simply referred to as “mixing air”). , Atomizes from each of the air injection holes 42 of the air mixture socket 41 and collides with the fuel droplets injected from the fuel injection holes 43 of the fuel injection valve 26. As described above, since the air injection hole portion 42 has the smallest restriction with respect to the air mixing conduit 27 and the air control valve 28, the flow velocity of the mixing air is maximized at this portion, and the kinetic energy is increased. It is effectively used for atomizing fuel. After that, the atomized fuel droplets flow out from the fuel injection hole portion 43 into the intake port 11 as a jet flow.

Next, a control routine of the fuel injection valve 26 and the air control valve 28 executed by the ECU 4 will be described. Figure 4
Is a fuel injection device E for an engine according to an embodiment of the present invention.
It is a flowchart which shows the control routine of the fuel injection valve 26 and the air control valve 28 which CU4 performs.

In the routine shown in FIG. 4, first, the EC
U4 calculates the valve opening time of the fuel injection valve 26 corresponding to the fuel injection amount in step S100. That is, as is well known, the ECU 4 divides the intake air amount Q measured by the air flow meter 31 by the rotation speed Ne of the engine 2 detected by the rotation angle sensor 37 to obtain the basic injection amount Q / Ne.
Is calculated, and the basic injection amount Q / Ne is calculated based on the cooling water temperature detected by the water temperature sensor 35, the intake air temperature measured by the intake air temperature sensor 32, and the air-fuel ratio signal output from the oxygen concentration sensor 36. The valve opening time TAU of the fuel injection valve 26 is calculated by multiplying by various correction factors corresponding to the above. Further, the invalid injection time TAUV mapped in advance according to the battery voltage is added to obtain the valve opening time TAU + TAUV which is the excitation time of the fuel injection valve 26.

Next, in step S200, the air control valve 2
The opening / closing timing calculation process 8 is executed. Although details will be described later, the opening timing of the air control valve 28 precedes the opening timing of the fuel injection valve 26 or the opening timing of the intake valve (for example, 8 ° C. before intake top dead center) by T1 time. Done. Further, the valve closing timing is the closing timing of the fuel injection valve 26 or the closing timing of the exhaust valve (for example, 1 after intake top dead center).
It is performed with a T2 time delay with respect to 0 ° C A).

Thereafter, the ECU 4 determines in step S300 whether or not the air control valve 28 is at the opening timing, and if not, the process proceeds to step S400 and the opening timing of the fuel injection valve 26 (for example, at the crank angle). Intake BTDC18
0 degree CA) is determined. As described above, since the fuel injection valve 26 always opens later than the air control valve 28, it is assumed that the opening timing of the fuel injection valve 26 has not yet been reached at this point, and the process proceeds to step S500. Next, in step S500, the air control valve 28
Is determined to be the valve closing timing. Since the air control valve 28 has not been opened yet, it is determined that it is not the valve closing timing, and the process proceeds to step S600. Further, in step S600, it is determined whether or not the closing timing of the fuel injection valve 26 has been reached. Since this fuel injection valve 26 has not yet been opened, it is determined that the closing timing has not been reached and the process proceeds to step S700. Then, it is determined whether the opening / closing operations of the air control valve 28 and the fuel injection valve 26 have been completed. Since they have not been completed, the process returns to the step S300, and the processes of steps S300 to S700 are repeated.

Then, in step S300, the air control valve 2
When it is determined that 8 is the valve opening timing, as shown in FIG.
After the control signal to the air control valve 28 is raised and opened in step S800, the steps are repeated from step S300 to step S300.
The processing of 700 is repeated. Next, when T1 (ms) has elapsed and it is determined in step S400 that the opening timing of the fuel injection valve 26 has been reached, in step S900 a control signal to the fuel injection valve 26 is raised to open the valve, and When it is determined in step S600 that the valve opening time TAU + TAUV has elapsed since the fuel injection valve 26 was opened and the closing timing of the fuel injection valve 26 has been reached, the control signal to the fuel injection valve 26 is set in step S1100. Lower and close the valve. After that, if it is determined in step S500 that the air control valve 28 closes, the air control valve 2 is determined in step S1000.
The control signal for the control valve 28 to 8 is closed and closed, and it is determined in step S700 that the opening / closing operation of the air control valve 28 and the fuel injection valve 26 is completed, and this routine is completed.

Next, the routine for calculating the opening / closing timing of the air control valve 28 executed by the ECU 4 in step S200 will be described. FIG. 5 is a flowchart of the routine, and FIG. 6 is a time chart showing control signals of the fuel injection valve and the air control valve with respect to the crank angle of the engine. As shown in FIG. 5, the ECU 4 determines in step S201 whether or not the rotation speed Ne of the engine 2 detected by the rotation angle sensor 37 is 2000 rpm or more.
When the speed is 00 rpm or more, the air control valve 28 is opened at step S202. That is, 200
At 0 rpm or more, the valve is always open.

In step S201, it is determined whether or not the rotation speed Ne of the engine 2 is 2000 rpm or more, and when it is 2000 rpm or more, the air control valve 28 is always kept open in step S202. In the processes of steps S300 to S1100, the air control valve 28 is controlled to open and close in synchronization with the rotation of the engine 2 together with the fuel injection valve 26, so that the responsiveness of the air control valve 28 increases when the rotation speed of the engine 2 increases. This is because the opening / closing operation is delayed due to the above problem. Further, at this time, since a large amount of intake air is introduced into the combustion chamber 8 according to the opening degree of the throttle valve 14 and the rotation speed thereof is controlled, the air control valve 28 is set as in the idle operation. This is also because it is not necessary to adjust the amount of mixing air supplied from the air mixing conduit 27 by opening and closing.

Since the air control valve 28 is held in the open state in this way, the intake air upstream of the throttle valve 14 passes through the air mixing conduit 27 and enters the intake port 11 from the air injection hole 42. Is continuously supplied as mixing air, and plays a role of atomizing the fuel injected from the fuel injection hole portion 43.

Next, when the speed is less than 2000 rpm in step S201, the process proceeds to step S203, and it is determined whether or not there is a timing that precedes the valve opening start timing of the fuel injection valve 26 by a time within T1 (ms), and then in step S204. Then, it is determined whether or not the fuel injection valve 26 is open, that is, whether or not fuel injection is in progress. In step S205, it is determined whether or not the fuel injection valve 26 is closed, that is, within T2 (ms) after the end of fuel injection. To judge.

If any one of the determinations in steps S203 to S205 is YES, the process branches to step 202 and the air control valve 28 is opened,
NO in all determinations in steps S203 to S205
If so, the process proceeds to step S206. This step S20
As shown in FIG. 6, by the processing of 3 to S205, from the time T1 (ms) before the start of fuel injection to the time T2 (m
During the period up to s), the air control valve 28 is opened.

Next, if the engine speed is less than 2000 rpm and the opening timing is not reached, the process proceeds to step S206. In this step, it is determined whether or not the above-mentioned Q / Ne corresponding to the engine load is a predetermined value or more. If it is equal to or higher than the predetermined value, that is, if the load is high, the process branches to step S210, and the air control valve 28 is closed to end this routine.

If Q / Ne is less than the predetermined value in step S206, that is, if the load is equal to or less than the medium load, the process proceeds to subsequent steps S207 to S209, and it is determined whether the valve overlap period or not. That is, in step S207, it is determined whether the timing is within T1 (ms) before the start of the intake valve opening, in step S208 it is determined whether the valve overlap period is in progress, and in step S209, the exhaust valve is opened. It is determined whether it is within T2 (ms) after closing the valve.

If any one of the determinations in steps S207 to S209 is YES, the process branches to step S202 described above to set the air control valve 28 at the opening timing, and if all determinations are NO, step S21.
The routine proceeds to 0 and the air control valve 28 is set to the closing timing to end this routine. By the processing of S207 to S209, as shown in FIG. 6, even during a period other than during fuel injection,
From the time T1 (ms) before the start of the intake valve opening to the time T2 (ms) after the exhaust valve is closed, the air control valve 28 is opened.

As described above, in the fuel injection device of this embodiment, the air control valve 28 is opened for a period from the time T1 (ms) before the start of fuel injection to the time T2 (ms) after the end of fuel injection to mix air. This not only promotes atomization of fuel, but also opens the valve from the time T1 (ms) before the start of the intake valve opening of the engine to the time T2 (ms) after the exhaust valve is closed to supply air to the injection hole. By doing so, it is possible to prevent carbon in the gas after combustion that blows back to the intake passage side from adhering to the injection hole portion of the fuel injection valve 26 when the valves overlap.

In this embodiment, the engine 2 functions as the internal combustion engine M1, the air flow meter 31 and the rotation angle sensor 37 used for determining the intake air amount function as the operating state detecting means M2, and the fuel injection is performed. The fuel injection valve 26 functions as the means M3, the air mixture conduit 27 functions as the air conduit M4, and the air control valve 28 functions as the opening / closing means M5.
201 to step S210, step S300, step S500, step S800 and step S1000.
Each of the ECUs 4 functions when executing the processing of.

Next, FIGS. 7 and 8 show an embodiment corresponding to the second embodiment of the invention. In this embodiment, as shown in FIG. 7, an air pump 38, which is a pressurizing means for pressurizing intake air, is arranged in the air mixing conduit 27 in the apparatus of FIG. The intake air in the air mixture pipe 27 is pressurized by the air pump 38 to the atmospheric pressure or higher, and the air can be supplied to the vicinity of the injection point of the fuel injection valve 26 even when the engine is under a heavy load (for example, when the throttle valve is fully opened). Become.

FIG. 8 shows a control flow chart in this embodiment.
Shown in. As described above, in the present embodiment, the mixing air can be supplied even under a high load. Therefore, the flowchart shown in FIG. 8 is substantially the same as the flowchart of FIG. 5 in which step S206 for load determination is deleted. is there. As a result, it becomes possible to supply air for atomizing the injected fuel and for supplying air during the valve overlap period for preventing deposits from adhering to the injection hole portion of the fuel injection valve 28 in the full load range.

[0037]

As described above, in the fuel injection device for an internal combustion engine according to the first aspect of the invention, the opening / closing means provided in the air pipeline is opened during the period substantially synchronized with the fuel injection of the fuel injection means. The fuel injection is performed during the valve overlap period in which the load of the internal combustion engine is equal to or lower than the medium load and both the intake valve and the exhaust valve of the internal combustion engine are open based on the detection of the operating state detection means. If not, since the opening / closing control means for holding the opening / closing means in the open state is provided even during the period substantially synchronized with the valve overlap period, the atomization of the fuel by the intake air during the fuel injection is performed. Not only is it promoted, but it is possible to prevent carbon and other deposits from adhering to the injection hole of the fuel injection valve, which is caused by blowback of post-combustion gas to the intake passage side during valve overlap, thus improving reliability. .

The fuel injection device for an internal combustion engine according to a second aspect of the present invention is the fuel injection device according to the first aspect, wherein the intake air in the air pipeline is bypassed to the opening / closing means by bypassing the throttle valve. By arranging the pressurizing means for pressurizing the intake air, it is possible to supply the intake air to the vicinity of the fuel injection point not only under a medium load but also under a high load,
It is possible to atomize the fuel and prevent deposits from adhering to the injection hole portion of the fuel injection.

[Brief description of drawings]

FIG. 1 is a claim correspondence diagram conceptually showing the content of one embodiment of the present invention.

FIG. 2 is a system configuration diagram of a fuel injection device for an engine that is an embodiment of the present invention.

FIG. 3 is a partially enlarged cross-sectional view showing a configuration in the vicinity of a fuel injection hole portion of a fuel injection valve of a fuel injection device for an engine according to an embodiment of the present invention.

FIG. 4 is a flowchart showing a control routine of a fuel injection valve and an air control valve executed by an ECU of a fuel injection device for an engine which is an embodiment of the present invention.

FIG. 5 is a flowchart showing a routine for calculating the opening / closing timing of the air control valve, which is executed by the ECU of the fuel injection system for the engine according to the embodiment of the present invention.

FIG. 6 is a time chart showing control signals of the fuel injection valve and the air control valve with respect to the crank angle of the fuel injection device for the engine according to the embodiment of the present invention.

FIG. 7 is a system configuration diagram of a fuel injection device for an engine which is another embodiment of the present invention.

FIG. 8 is a flowchart showing a routine for calculating the opening / closing timing of the air control valve, which is executed by the ECU of the fuel injection system for an engine according to another embodiment of the present invention.

[Explanation of symbols]

 2 Engine 4 Electronic Control Unit (ECU) 26 Fuel Injection Valve 27 Air Mixing Pipeline 28 Air Control Valve 31 Air Flow Meter 37 Rotation Angle Sensor 38 Air Pump

Claims (2)

[Claims] 1. A driving state detecting means for detecting a driving state of an internal combustion engine, and a predetermined amount according to a driving state of the internal combustion engine, which is provided in an intake system of the internal combustion engine and detected by the driving state detecting means. Fuel injection means for injecting the above fuel into the intake system, an air pipeline for supplying a part of the intake air flowing through the intake system to the vicinity of the injection point of the fuel injection means bypassing the throttle valve, and the air pipe An opening / closing means that is provided in the passage and connects or disconnects the air pipeline, a period that is substantially synchronized with the fuel injection by the fuel injection means, and fuel injection by the fuel injection means is not performed, and And an opening / closing control means for holding the opening / closing means in an open state during a period substantially synchronized with a valve overlap period in which both the intake valve and the exhaust valve are opened when the load of the internal combustion engine is equal to or less than a medium load. The fuel injection system for an internal combustion engine characterized by Rukoto. 2. A pressurizing means for pressurizing intake air in the air pipeline is disposed in the air pipeline that bypasses the throttle valve and reaches the open / close means, and the open / close control means comprises:
2. The fuel injection device for an internal combustion engine according to claim 1, wherein the opening / closing means is held in an open state during a period substantially synchronized with the valve overlap period even under a high load.