JPH06147062A - Fuel injection system of internal combustion engine - Google Patents

Abstract

PURPOSE:To prevent any clogging in an air mixture pipeline due to deposits from occurring by keeping off the spitting of gas to this air mixture pipeline after combustion. CONSTITUTION:When an electronic control unit 4 is so judged that a driving state in an internal combustion engine is low speed and high load by each signal so far fed out of each sensor detecting the driving state of this engine, an air control valve 28, being installed in an air mixture pipeline 27 installed for spraying a part of intake air to a nozzle part of a fuel injection valve 26, is closed, thereby any spitting of gas after combustion is prevented from occurring in the air mixture pipeline 27.

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 part of intake air on the upstream side of a throttle valve is supplied to the vicinity of a nozzle hole of the fuel injection valve to inject fuel The present invention relates to a fuel injection device that promotes atomization and reduces harmful components in exhaust gas.

[0002]

2. Description of the Related Art Conventionally, a fuel injection device for injecting fuel into an air system of an internal combustion engine by injecting fuel from a fuel injection valve and controlling the operating state thereof has been widely used. 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 Utility Model Publication No. 4 or Japanese Utility Model Application Laid-Open No. 58-1662622 is 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.

As described above, these techniques are aimed at atomizing the fuel. On the other hand, the actual exploitation Sho 62-4775
A fuel injection device such as the fuel injection device described in Japanese Patent Laid-Open No. 7-75758 or Japanese Patent Laid-Open No. 2-75758 has been proposed, which cuts off the air supply at a high speed and a high load, or cuts off the air supply during an excessive operation. All of these are ideas regarding the control method of the air control valve in terms of vehicle and engine performance.

[0005]

Considering the reliability of the fuel injection device, deposits such as carbon adhere to the fuel injection device provided in the intake pipe with time, and the spray characteristics deteriorate. There is a potential problem.
One of the causes of this dehodge is the blowback of the gas after combustion during the valve overlap period in which both the intake valve and the exhaust valve of the internal combustion engine open to the intake passage side. Especially at low speed and high load, this blowback is strong and appears as a backflow phenomenon of intake air. This strong blow-back, that is, the backflow of the gas after combustion, becomes a backflow to the air pipe in the device that attempts to supply air to the vicinity of the injection hole portion, leading to a problem that the air pipe is clogged due to adhesion of carbon deposits.

The above-mentioned prior art is devised only from the viewpoint of atomizing the fuel or from the viewpoint of satisfying both the atomization of the fuel and the performance of the vehicle / engine. The purpose is to prevent backflow into the pipeline.

[0007]

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.
A fuel injection unit M3 that is provided in the intake system of the internal combustion engine M1 and injects 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 detection unit M2; Part of the intake air flowing through the intake system,
An air conduit M4 that bypasses the throttle valve and is supplied near the injection point of the fuel injection means M3, and the air conduit M
4, an opening / closing means M5 that connects or disconnects the air conduit M4, and the opening / closing means M5 when the internal combustion engine M1 is operating at low speed / high load based on the detection of the operating state detecting means M2. Opening / closing control means M for holding the closed state
And 6 are provided.

In the fuel injection system for an internal combustion engine according to a second aspect of the present invention, a valve overlap period in which the opening / closing means M5 is operating during low speed / high load operation of the internal combustion engine M5 and both intake and exhaust valves are open. It keeps the inside closed.

[0009]

In the invention of claim 1, when the operating condition of the internal combustion engine M1 detected by the operating condition detecting means M2 is low speed / high load, the opening / closing means M5 is closed by the opening / closing control means M6, so that the air conduit M4. Of the gas after combustion at the time of valve overlap can be prevented from flowing back to the air pipe M4.
As a result, it is possible to prevent clogging of the air pipeline due to carbon deposits. In the invention of claim 2, the internal combustion engine M
No. 1 keeps the opening / closing means M5 in the closed state only during the valve overlap period when the low rotation / high load operation and the intake / exhaust valves are both open, so the air supply for atomization is maximized. Therefore, it is possible to prevent backflow of the gas after combustion to the air pipeline M4, and it is possible to prevent clogging of the air pipeline due to carbon deposit.

[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, a signal for every 60 degrees CA is an N signal, and a signal for every 720 degrees CA is a G signal. The engine speed Ne is detected by this N signal, 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 4b 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 on the upstream side of the throttle valve 14 in the intake pipe 12 flows into the inside of the air mixing socket 41 from the air mixing pipe 27 (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 ECU
4 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 calculate a basic injection amount Q / Ne, and calculates the basic injection amount. In Q / Ne, the water temperature sensor 35
The cooling water temperature detected by the intake air temperature sensor 32, the intake air temperature measured by the intake air temperature sensor 32, and various correction factors corresponding to the air-fuel ratio signal output from the oxygen concentration sensor 36 are multiplied to open the fuel injection valve 26. Calculate the valve time TAU. 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 of the air control valve 28 is performed by the fuel injection valve 26.
The valve opening timing is preceded by T1 time.
Further, the valve closing is T with respect to the valve closing timing of the fuel injection valve 26.
It will be delayed by 2 hours.

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 fuel injection valve 26
It is determined whether or not the valve opening timing has been reached. 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 step S50 is performed.
Move to 0. Next, in step S500, it is determined whether or not the air control valve 28 is at the closing timing, and the air control valve 28
Since the valve has not been opened yet, it is determined that it is not the valve closing timing, and the process proceeds to step S600. Further, step S60
At 0, 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 yet.
00, it is determined whether or not 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 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, the startup correction time T1
(Ms) has passed, and in step S400, the fuel injection valve 2
When it is determined that the valve opening timing of 6 has been reached, step S
At 900, the control signal to the fuel injection valve 26 is raised to open the valve, and further, the valve opening time TA after the fuel injection valve 26 is opened.
When it is determined that the valve closing timing of the fuel injection valve 26 has been reached in step S600 after the passage of U + TAUV, the control signal to the fuel injection valve 26 is lowered and closed in step S1100. Then, in step S500, the air control valve 2
If it is determined that 8 is the valve closing timing, step S1000
In step S700, the control signal to the air control valve 28 is lowered to close the valve, and in step S700, it is determined that the opening / closing operations of the air control valve 28 and the fuel injection valve 26 are finished, and this routine is finished.

Next, step S of the above-mentioned control routine.
Opening of the air control valve 28 executed by the ECU 4 at 200
A routine for calculating the valve closing timing will be described. FIG. 5 is a flowchart of the routine, and FIG. 6 is an air control valve 38.
FIG. 7 is a time chart showing the control signals of the fuel injection valve and the air control valve in the operating range in which the control state is switched.

As shown in FIG. 5, the ECU 4 executes step S
At 201, it is determined whether the rotation speed Ne of the engine 2 detected by the rotation angle sensor 37 is 2000 rpm or more. When it is 2000 rpm or more, the air control valve 28 is opened at step S202 and this routine is finished. To do. That is, steps S300 to S11
In the process of 00, the air control valve 28 is operated together with the fuel injection valve 26.
Is controlled in synchronization with the rotation of the engine 2,
This is because when the rotation speed of the engine 2 rises, a problem of responsiveness of the air control valve 28 arises and a delay occurs in its opening / closing operation.
Further, at this time, a large amount of intake air is introduced into the combustion chamber 8 according to the opening degree of the throttle valve 14 to control the number of revolutions thereof, so that the air control valve 28 is opened and closed as in the idle operation. Operate and air mix conduit 27
This is also because it is not necessary to adjust the supply amount of mixing air from the.

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, if it is less than 2000 rpm in step S201, the flow proceeds to step S203, where the opening of the slot valve detected by the throttle position sensor 33 (that is, the rotation angle from the fully closed position of the throttle valve).
Hereinafter referred to as throttle opening. ) Is 70 ° or more. Here, when the throttle opening is 70 ° or more, it corresponds to the operating region A, that is, the low speed and high load region in the operating region classification shown in FIG. 6, and in this case, the process branches from step S203 to step S207 and the air control valve 28 is closed. This routine is ended as timing. Therefore, in the operating region A, as shown in FIG. 7, the air control valve 28 is always kept closed regardless of the control state of the fuel injection valve 26.

Next, when the throttle opening is less than 70 ° in step S203, it corresponds to the operating region B shown in FIG.
In step S204, it is determined whether or not the fuel injection valve 26 is ahead by a time within T1 (ms) with respect to the opening timing of the fuel injection valve 26. In step S205, it is determined whether or not the fuel injection valve 26 is open. Also, in step S206, after the fuel injection valve 26 is closed, that is, after the fuel injection is completed, T2.
It is determined whether it is within (ms). And step S20
If any one of the determinations in steps 4 to S206 is YES, the process branches to step S202 to set the air control valve 28 to the opening timing, and if all determinations in steps S204 to S206 are NO, the step S207 is performed. Then, the routine ends with the air control valve 28 closed timing. This step S204
By the processing of step S202, in the operating region B shown in FIG. 6, that is, in the low rotation medium load or less, as shown in FIG. During this period, the air control valve 28 is opened.

As described above, the fuel injection device of this embodiment supplies air to the injection hole portion of the fuel injection valve 26 at low rotation speed and high load. The air control valve 28 is connected to the communication of the air pipeline 27.
Air line 2 for post-combustion gas by closing and shutting off
Prevents backflow to 7. As a result, it is possible to prevent clogging of the air pipeline 27 due to carbon deposits.

Next, FIGS. 8 to 9 show an embodiment corresponding to the second embodiment of the invention. In contrast to step S203 of the control flowchart of FIG. 5 according to the present embodiment, as shown in FIG. 8, it is determined in step S203A that the slot opening is 70.
It is determined whether or not it is above ° and during the valve overlap period. As a result, the air control valve 28 is closed only during the valve overlap period in the operating region A as shown in the control time chart of the fuel injection valve 26 and the air control valve 28 shown in FIG.

In this embodiment, the engine 2 as the internal combustion engine M1 and the air flow meter 31, the intake air temperature sensor 32, the throttle position sensor 33, the water temperature sensor 35, which are used as the operating state detecting means M2 for determining the intake air amount, An oxygen concentration sensor 36, a rotation angle sensor 37, and an idle switch 3 for detecting an idle operation of the engine 2.
4 function as the fuel injection means M3, the fuel injection valve 26 functions as the fuel injection means M3, the air mixing conduit 27 functions as the air conduit M4, and the air control valve 28 functions as the opening / closing means M5. As step S20
1 to step S207, step S300, step S
The ECU 4 functions when executing the processes of 500, step S800, and step S1000.

[0033]

As described above, the fuel injection device for an internal combustion engine according to the invention of claim 1 is provided in the air pipeline for supplying a part of the intake air and the air pipeline in the vicinity of the injection location of the fuel injection means. Based on the detection of the opening / closing means by the operating state detecting means, the internal combustion engine is equipped with an opening / closing control means for keeping the closed state during low-speed / high-load operation. As a result, it is possible to prevent carbon deposits from adhering to the air pipeline and prevent clogging of the air pipeline.

Further, in the fuel injection device for an internal combustion engine according to a second aspect of the present invention, the opening / closing means is held in the closed state only during the low engine speed / high load operation and the valve overlap period. Even in the above operating range, the air supply for atomization can be maximized.

[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 structure in the vicinity of a fuel injection hole portion of a fuel injection valve of a fuel injection device for an engine which is an embodiment of the present invention.

FIG. 4 is a flowchart showing a control routine of a fuel injection valve and air control 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 device for the engine according to the embodiment of the present invention.

FIG. 6 is a diagram showing an operation basin in which the control state of the air control valve of the engine fuel injection device according to the embodiment of the present invention is switched.

FIG. 7 is a time chart showing control signals of the fuel injection valve and the air control valve of the engine fuel injection device according to the 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 device for the engine according to the embodiment of the present invention.

FIG. 9 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.

[Explanation of symbols]

 2 Engine 4 Electronic Control Unit (ECU) 26 Fuel Injection Valve 27 Air Mixing Device 28 Air Control Valve 31 Air Flow Meter 32 Intake Temperature Sensor 33 Throttle Position Sensor 34 Idle Switch 35 Water Temperature Sensor 36 Oxygen Concentration Sensor 37 Rotation Angle Sensor

Claims (2)

[Claims] 1. An operating state detecting means for detecting an operating state of an internal combustion engine; and an operating state detecting means, which is provided in an intake system of the internal combustion engine, according to an operating state of the internal combustion engine detected by the operating state detecting means. Fuel injection means for injecting a fixed amount of fuel into the intake system; an air pipeline for supplying a part of intake air flowing through the intake system to a vicinity of an injection point of the fuel injection means, bypassing a throttle valve; An opening / closing means provided in the air pipeline for communicating or blocking the air pipeline, and a state in which the opening / closing means is closed when the internal combustion engine is in a low rotation / high load operation based on the detection of the operating state detecting means. And an opening / closing control unit that holds the fuel injection device for an internal combustion engine. 2. The opening / closing control means holds the opening / closing means in a closed state during a valve overlap period in which the internal combustion engine is operating at low rotation speed and high load and both intake and exhaust valves are open. The fuel injection device for an internal combustion engine according to claim 1, wherein the fuel injection device is a fuel injection device.