JP2003262174A - Internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent deterioration in fuel consumption, exhaust emission and starting ability due to adhesion of the fuel to an intake pipe wall when starting at low temperature in an intake-pipe-inside fuel injection type internal combustion engine. <P>SOLUTION: In a spark ignition type internal combustion engine provided with a fuel injection valve for injecting the fuel to a suction port 5a, a first fuel injection valve 6-1 having a relatively large injection particle diameter and a second fuel injection valve 6-2 having a relatively small injection particle diameter are provided as the fuel injection valves. When starting at low temperature, the fuel having excellent atomization characteristic is injected for supply to prevent deterioration of fuel consumption and exhaust emission due to adhesion of the fuel. After starting, fuel injection is switched to the fuel injection by the first fuel injection valve in the predetermined timing to cope with the operation in an ordinary range. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement of a spark ignition type internal combustion engine for injecting fuel into an intake pipe.

[0002]

2. Description of the Related Art In an internal combustion engine of the intake pipe fuel injection system, a part of the injected fuel adheres to the intake pipe inner wall and the intake valve and stays, especially at low temperature where fuel vaporization is delayed. It was necessary to inject and supply extra fuel accordingly, which was a factor that deteriorated fuel efficiency and exhaust performance.

On the other hand, the applicant of the present invention has filed Japanese Patent Application Laid-Open No. 2000-8776.
As No. 8, the low temperature startability is improved by injecting and supplying the fuel before opening the intake valve to promote the vaporization of the fuel, or opening and closing the intake valve for several degrees to promote the intake flow to promote the vaporization of the fuel. I am proposing what I did. However, this is not always sufficient from the viewpoint of preventing fuel from adhering to the wall surface of the intake pipe.

As a means for vaporizing the fuel adhering to the intake pipe wall or the like, it is considered that the opening / closing timing of the intake valve is set so that a part of the exhaust gas flows into the intake pipe, and the adhering fuel is vaporized by the exhaust heat. . However, it is difficult to sufficiently vaporize the liquid fuel only by the exhaust heat at the time of extremely low temperature or cold start, and a reliable effect cannot be expected.

[0005]

A first aspect of the present invention is a spark ignition internal combustion engine having a fuel injection valve for injecting fuel into an intake passage, wherein the fuel injection valve has a relatively large atomized particle size. The fuel injection valve No. 1 and the second fuel injection valve having a relatively small spray particle size were provided.

A second invention is that the second fuel injection valve is
It was located downstream of the first fuel injection valve.

In a third aspect of the invention, the spray angle of the second fuel injection valve is wider than that of the first fuel injection valve.

In a fourth aspect of the invention, the position and angle of the first fuel injection valve are set so that the fuel spray almost reaches the inner peripheral region of the intake valve umbrella portion.

In a fifth aspect of the present invention, the first and second fuel injection valves are set so as to inject fuel toward substantially the center of the intake valve head portion.

According to a sixth aspect of the present invention, the second fuel injection valve is
The fuel injection valve is positioned downstream of the first fuel injection valve and has a spray angle wider than that of the first fuel injection valve, and each of the fuel injection valves is directed toward a substantially central portion of the intake valve umbrella portion. It was set to jet.

In a seventh aspect of the invention, the first and second fuel injection valves are provided for each cylinder of a multi-cylinder engine.

An eighth aspect of the present invention comprises means for detecting an operating state in the first aspect of the present invention, and injects fuel from the first fuel injection valve or the second fuel injection valve according to the detected operating state. I decided to do it.

According to a ninth aspect of the present invention, the starting state of the engine is detected as the operating state, fuel is supplied from the second fuel injection valve at the beginning of start cranking, and then fuel is supplied from the first fuel injection valve. To start.

In a tenth aspect of the present invention, the intake pipe pressure is detected as the operating state of the ninth aspect, and when the intake pipe pressure becomes equal to or lower than a reference value after the start cranking, the fuel from the first fuel injection valve is detected. The injection was started.

An eleventh aspect of the present invention detects the engine speed as the operating state of the ninth aspect, and when the engine speed becomes equal to or higher than a reference value after the start cranking, the fuel from the first fuel injection valve is injected. The injection was started.

A twelfth invention detects the intake valve temperature as the operating state of the ninth invention, and when the intake valve temperature becomes equal to or higher than a reference value after the start cranking, the fuel from the first fuel injection valve is detected. The injection was started.

A thirteenth aspect of the invention is to detect the engine rotational speed as the operating state of the ninth aspect of the invention, and when a predetermined time elapses after the engine rotational speed becomes equal to or higher than a reference value after the start cranking, the first aspect of the invention. The fuel injection from the fuel injection valve was started.

In a fourteenth aspect based on the ninth aspect, the second aspect is the same as when the fuel injection from the first fuel injection valve is started.
The fuel injection from the fuel injection valve was stopped.

[0019]

According to the present invention, since two kinds of fuel injection valves having different spray particle sizes are provided side by side, it is possible to form an appropriate fuel spray according to the operating condition. For example, second
Since the fuel injection valve has a small fuel particle size and does not easily adhere to the intake passage wall or the like, it can be used at the time of starting at low temperature or during low load operation to improve fuel efficiency and exhaust performance. On the other hand, the first fuel injection valve can handle operating conditions that require high response or injection at a high injection rate.

The second fuel injection valve having a small spray particle size is first
By arranging it on the downstream side of the fuel injection valve, the amount of fuel adhering to the intake passage wall can be further reduced. Further, the second fuel injection valve located in the portion close to the combustion chamber in this way can set the spray angle to a large value as much as it is difficult for fuel to adhere to the intake pipe wall. There is a correlation between the spray angle of the fuel injection valve and the fuel particle size, and the smaller the fuel particle size, the wider the spray angle. That is, by increasing the spray angle of the second fuel injection valve, it is possible to reduce the fuel particle size and further suppress the adhesion of fuel to the intake pipe wall.

On the other hand, it is preferable that the first fuel injection valve, which has a relatively large fuel particle diameter, has its fuel spray reaching the inner peripheral region of the intake valve head portion. The temperature of the intake valve head portion is higher than that of the wall of the intake passage, and the temperature rises more quickly even when starting cold. Therefore, supplying the spray having a large fuel particle size to the inner peripheral region of the intake valve umbrella portion is effective for promoting vaporization of the injected fuel and mixing with the intake air. Further, from the viewpoint of preventing fuel from adhering to the intake passage wall, both the first and second fuel injection valves may be set to inject fuel toward substantially the center of the intake valve umbrella portion. desirable. In the multi-cylinder engine, the first and second fuel injection valves are provided for each cylinder.

At the beginning of engine starting cranking, fuel is supplied from the second fuel injection valve, and then fuel supply from the first fuel injection valve is started to improve exhaust performance and startability at the time of starting. be able to. Since the crankshaft rotation speed is low at the time of starting cranking, the negative pressure downstream of the throttle valve is small, and the pressure difference between the inside of the cylinder when the intake valve is open is small. For this reason, fuel vaporization due to blowback of cylinder gas cannot be expected so much. Under such conditions, by supplying fuel from the second fuel injection valve having a small fuel particle size, it is possible to suppress fuel adhesion to the intake passage wall and deterioration of the exhaust gas composition in the starting process, and improve startability. it can.

The operation of the starting cranking can be known, for example, from the state of the ignition key switch, but the timing for starting the fuel injection by the first fuel injection valve after the starting can be set based on the intake pipe pressure, for example. .
When the complete combustion is completed, the engine speed rapidly rises and the intake pipe negative pressure downstream of the throttle valve rapidly increases. Therefore, it is possible to determine the complete explosion from the change in the intake pipe pressure and switch to the first fuel injection valve. Of course, the engine speed may be detected and switched to the first fuel injection valve. The reference value of the rotation speed in this case is determined based on the crankshaft rotation speed at the time of complete explosion, which is determined by the engine.

In order to ensure the effect of heating the fuel spray from the first fuel injection valve in the intake valve umbrella portion to promote vaporization, in order to ensure the effect of vaporization, when the intake valve temperature becomes equal to or higher than the reference value after the start cranking. It is desirable to start fuel injection from the first fuel injection valve. It is considered that the reference value is, for example, about 80 ° C. Further, instead of directly detecting the intake valve temperature as described above, the fuel injection from the first fuel injection valve is started when a predetermined time has elapsed after the engine speed became equal to or higher than the reference value after the start cranking. You may do it. The elapsed time until the intake valve temperature rises sufficiently after the complete explosion is determined by the characteristics of the engine, so this is set in advance experimentally. As a result, the same effect as described above can be obtained with a simple configuration that does not use a temperature sensor.

At the time of switching from the second fuel injection valve to the first fuel injection valve, in order to stabilize the respective fuel pressures and injection characteristics, the first fuel injection valve starts the injection and the second fuel injection valve starts the injection. It is desirable to stop the fuel injection of.

[0026]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows a schematic mechanical configuration of the embodiment. In the figure, an internal combustion engine 1 includes an intake valve 3 and an exhaust valve 4 that are driven to open and close by a valve train 2.
Each cylinder intake port portion 5a of the intake passage 5 is provided with a first fuel injection valve 6-1 and a second fuel injection valve 6-2, and a combustion chamber 7 is provided with an ignition plug 8 and an ignition coil 9. A throttle valve 10, an air flow meter 11 for detecting an intake air amount, and a pressure sensor 16 for detecting an intake pipe pressure downstream of the throttle valve 10 are provided in an upstream portion of the intake passage 5.

As means for detecting the operating state, a crank angle sensor 12 for outputting a reference signal at the reference position of the engine crankshaft and a unit angle signal for each minute crank angle, and a water temperature for detecting the engine cooling water temperature. An intake valve temperature sensor 14 for detecting the temperature of the sensor 13 and the intake valve 3 is provided. The detection signals of the sensors are output to the control unit 15 together with the starting state signal from the ignition key switch 17.

The control unit 15 is composed of a microcomputer including a CPU and its peripheral devices, and outputs a fuel injection signal to the fuel injection valve 6 on the basis of the various detection signals to perform fuel injection control and ignition. An ignition signal is output to the coil 9 to perform ignition control, and an injection signal is output to the fuel injection valves 6-1 and 6-2 to perform fuel injection control.

The fuel injection valves 6-1 and 6-2 are shown in FIGS.
As shown in FIG. 3, on the curved outer side portion of the suction port portion 5a,
It is provided so as to face the port opening to the combustion chamber 7. The second fuel injection valve 6-2 is located downstream of the first fuel injection valve 6-1 and the respective fuel injection directions are set substantially in the center of the umbrella portion 3a of the intake valve 3. There is. The first fuel injection valve 6-1 has a characteristic that the fuel spray angle θ1 is relatively narrow and the particle size of the injected fuel is relatively large.
The second fuel injection valve has a relatively wide spray angle θ2 and a relatively small fuel particle size.

The spray angle θ1 of the first fuel injection valve 6-1 is
As shown also in FIG. 4, the spread of the spray is set so as to substantially fall within the inner region of the intake valve umbrella portion 3a. On the other hand, the spray angle θ2 of the second fuel injection valve 6-2 is set so that the spray spreads slightly outside the intake valve umbrella portion 3a.

FIG. 3 shows an example of application to a cylinder head having a single intake valve structure having one intake valve 3 per cylinder. On the other hand, the injection valve layout as illustrated in FIG. 5 or FIG. 6 can be applied to a cylinder head having a two-intake intake valve structure in which two intake valves 3 are provided per cylinder. In the intake 2 valve type,
As shown in the drawing, the intake port portion 5a of each cylinder generally has a configuration in which it branches toward the two intake valves 3 on the way. In such a port configuration, as shown in FIG.
Each of the fuel injection valves 6-1 and 6-2 is a two-way nozzle and is provided at a position upstream of the port branching portion so that fuel is distributed and supplied from each injection valve in two directions. On the other hand, in the one shown in FIG. 6, the first fuel injection valve 6-1 and the second fuel injection valve 6-2 are provided in each of the branched ports. According to the configuration of FIG. 6, for example, when a variable valve operating device is applied to improve combustion at low speed and low load and only one intake valve 3 is opened to generate a swirl in the cylinder, the valve opening is performed. It is possible to inject and supply the fuel only to the intake port portion on the side where the fuel injection is performed.

Next, the fuel injection control executed by the control unit 15 will be described with reference to the flow charts of FIGS. 7 to 10 are flow charts showing a processing routine of fuel injection control, and this processing is, for example, about 1
It is repeatedly executed at a cycle of 0 milliseconds. In the following description and flow chart, the symbol S represents a processing step number.

FIG. 7 shows the main routine of this control.
When a certain operating condition (hereinafter referred to as "operating condition 1") is satisfied, the satisfied flag is set to 1 and then the second flag is set until the flag is reset to 0 by a predetermined release condition.
Fuel injection is performed from the fuel injection valve 6-2 (S101 to S
102) and thereafter, the fuel injection is switched to the fuel injection from the second fuel injection valve 6-1 (S102 to S103).

FIG. 8 shows a processing routine for setting the satisfaction flag of the operating condition 1. In this case, the operating condition 1 is that the engine starting operation is started, and this is determined by the state of the ignition key switch 17 (see FIG. 1). That is, when the ignition key switch 17 is operated from the OFF position to the ON position and the starter ON position, the operating condition 1 satisfaction flag is set to 1 (S201 to S202). After that, while the ignition key switch 17 continues to be in the ON state, it is determined whether or not a flag indicating that the release condition of the operating condition 1 described later is satisfied is set to 1, and the release flag is set to 1 If so, the operating condition 1 satisfaction flag is reset to 0 and the process returns to the main routine (S203 to S205). If the release flag is not 1, then the state of the operating condition 1 satisfaction flag is checked, and the state of the satisfaction flag is maintained regardless of the state of the release flag (S204 to S20)
2, S205). When it is determined in S301 that the ignition key switch 17 is off, the routine of FIG. 8 is ended without doing anything. Note that the operating condition 1 satisfaction flag and the operating condition 1 cancellation flag are both set to 0 in advance as initial values.

FIG. 9 shows a subroutine for determining whether to cancel the operating condition 1. In this case, the release condition is that the engine has completed a complete explosion, and this is detected by a signal from the intake pipe pressure sensor 16 (see FIG. 1). That is, when the engine completes a complete explosion, the pressure downstream of the throttle valve drops sharply as compared to during cranking as the engine speed increases (see FIG. 11). Therefore, the intake pipe pressure P1 at this time is read (S301), and if it is lower than the reference value Po, the operating condition 1 release flag is set to 1 (S302 to S30), assuming that the complete explosion has occurred.
3) If the detected pressure P1 is equal to or higher than the reference value Po, it is determined that the cranking is not in the state of complete explosion, and the operating condition 1 cancellation flag is reset to 0 (S302 to S304).

In order to determine the completion of start-up explosion, the engine speed N is detected by the signal from the crank angle sensor 12 (see FIG. 1) and compared with the reference value No as shown in FIG. You may That is, in FIG. 10, the rotational speed N is read in S301, and compared with the reference value No in S302, and if N> No, it is determined that the engine is in a complete explosion and the operating condition 1 release flag is set to 1, and N ≤ No
If so, the operating condition 1 release flag is reset to 0.

In the process shown in FIG. 9 or 10, even if the operating condition 1 release flag is set to 1 by starting the engine, if it stalls after that, P1 ≧ Po or N ≦ No
Therefore, the release flag becomes 0, but as described above, once the release condition is satisfied by the processing of S204 of FIG. 8, the operation condition 1 satisfaction flag remains 0, so the control returns to the initial state. There is no such thing.

FIG. 11 is a timing chart during the control. When the engine completes a complete explosion, at the time of low speed operation such as idling, a blowback phenomenon occurs in which the combustion gas flows back to the intake system when the intake valve opens. Since this blow-back is combustion gas, it is effective for vaporization and mixing promotion of the injected fuel. Therefore, in this control, the fuel injection is switched to the first fuel injection valve 6-1 having a large fuel particle size after the engine is started. The effect of the above-mentioned blowback gas cannot be obtained until the engine completes the complete explosion, so the fuel particle size is small and atomization is good from the start of cranking to the complete explosion, and the fuel does not easily adhere to the port wall surface. Fuel injection is performed by the second fuel injection valve 6-2.

FIG. 12 and FIG. 13 show other determination methods for the release conditions, respectively. These are the first fuel injection valve 6-2 to the first fuel injection valve 6-2 on condition that the intake valve temperature rises.
The fuel injection valve 6-1 is changed over. In FIG. 12, first, the intake valve temperature Tv is read by the intake valve temperature sensor 14 (see FIG. 1) (S301), and if it is higher than the reference value To, the operating condition 1 release flag is set to 1 (S302 to S303), Intake valve temperature Tv
Is less than the reference value To, the operating condition 1 cancellation flag is reset to 0 (S302 to S304).

FIG. 13 shows that the temperature sensor is not used.
The configuration is simplified by estimating the rise in intake valve temperature from the elapsed operating time after the complete explosion of the start. In this processing routine, first, the engine speed N is read and compared with the reference value N1 for the complete explosion determination (S301 to S302). If N> N1, the counter C for measuring the elapsed time is incremented and then compared with the determination reference value Co (S303 to S).
304). At this time, if C> Co, the operating condition 1 cancellation flag is set to 1 (S305). In each of the above determination processes, when N ≦ N1 or C ≦ Co, the operating condition 1
The release flag is maintained at 0 and the current process is terminated (S3).
06). The counter C is cleared at the initial setting of the main routine shown in FIG.

FIG. 14 is a timing chart during the control shown in FIG. 12 or FIG. The fuel is injected by the second fuel injection valve 6-2, which has good atomization, from the start cranking of the engine until the intake valve temperature rises to some extent after the start, and the first fuel injection valve after the intake valve temperature rises. 6-
The fuel injection is switched to 1. The fuel injected from the fuel injection valve 6-1 has a relatively large fuel particle size, but when the intake valve temperature rises, the fuel particles are heated when they collide with the intake valve umbrella portion 3a, and vaporization is promoted. , A good mixture can be formed. According to the control utilizing the heating action by the intake valve, the fuel atomization can be promoted even under the condition that the combustion gas is not blown back.

[Brief description of drawings]

FIG. 1 is a schematic diagram of a mechanical configuration of an embodiment of the present invention.

FIG. 2 is a schematic plan view of a cylinder head showing an arrangement of fuel injection valves of the embodiment.

FIG. 3 is a side sectional view of an intake port portion for showing the arrangement of the fuel injection valve of the embodiment.

FIG. 4 is an explanatory diagram regarding a spray region of two fuel injection valves according to the embodiment.

FIG. 5 is a schematic plan view of a cylinder head of another embodiment regarding arrangement of fuel injection valves.

FIG. 6 is a schematic plan view of a cylinder head of another embodiment relating to the arrangement of fuel injection valves.

FIG. 7 is a first flowchart showing the control content of the embodiment.

FIG. 8 is a second flowchart showing the control content of the embodiment.

FIG. 9 is a third flowchart showing the control content of the embodiment.

FIG. 10 is a fourth flowchart showing the control content of the embodiment.

FIG. 11 is a timing chart at the time of control according to FIGS.

FIG. 12 is a fifth flowchart showing the control content of the embodiment.

FIG. 13 is a sixth flowchart showing the control content of the embodiment.

FIG. 14 is a timing chart at the time of control according to FIGS.

[Explanation of symbols]

1 Internal combustion engine 2 Valve drive 3 intake valve 3a Intake valve umbrella part 4 exhaust valve 5 Intake passage 5a Suction port 6-1 First fuel injection valve 6-2 Second fuel injection valve 7 Combustion chamber 8 spark plug 9 ignition coil 10 Throttle valve 11 Air flow meter 12 crank angle sensor 13 Water temperature sensor 14 Intake valve temperature sensor 15 Control unit 16 Intake pipe pressure sensor 17 Ignition key switch

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) F02M 69/04 F02M 69/00 320F 69/28 350P 320B 320K F term (reference) 3G066 AA01 AB02 AD10 BA01 BA14 BA19 CC48 DA01 DA02 DA04 DB01 DB08 DB09 DB13 DB19 DC09 DC13 DC19 3G301 HA01 JA00 JA02 JA21 KA01 KA02 KA08 LB02 MA19 PA07Z PE00Z PE01Z PE03Z PE08Z PF16Z

Claims (14)

[Claims] 1. A spark ignition internal combustion engine comprising a fuel injection valve for injecting fuel into an intake passage, wherein the fuel injection valve is a first fuel injection valve having a relatively large atomized particle size,
An internal combustion engine comprising: a second fuel injection valve having a relatively small atomized particle size. 2. The internal combustion engine according to claim 1, wherein the second fuel injection valve is located downstream of the first fuel injection valve. 3. The internal combustion engine according to claim 2, wherein the spray angle of the second fuel injection valve is wider than that of the first fuel injection valve. 4. The first fuel injection valve according to claim 1, wherein a position and an angle of the first fuel injection valve are set so that the fuel spray almost reaches the inner peripheral region of the intake valve umbrella portion. Internal combustion engine. 5. The fuel injection valve according to claim 1, wherein the first and second fuel injection valves are set so as to inject fuel toward a substantially central portion of an intake valve head portion. Internal combustion engine. 6. The second fuel injection valve is located downstream of the first fuel injection valve and has a spray angle wider than that of the first fuel injection valve. ,
The internal combustion engine according to claim 1, wherein fuel is injected toward substantially the center of the intake valve umbrella portion. 7. The internal combustion engine according to claim 1, claim 2, claim 3, or claim 6, wherein the first and second fuel injection valves are provided for each cylinder of a multi-cylinder engine. organ. 8. The method according to claim 1, further comprising means for detecting an operating state, wherein the fuel is injected and supplied from the first fuel injection valve or the second fuel injection valve according to the detected operating state. Internal combustion engine. 9. An engine starting state is detected as an operating state,
The internal combustion engine according to claim 8, wherein fuel is supplied from the second fuel injection valve at the beginning of the start-up cranking, and then fuel supply from the first fuel injection valve is started. 10. The method according to claim 9, wherein the intake pipe pressure is detected as the operating state, and the fuel injection from the first fuel injection valve is started when the intake pipe pressure becomes equal to or lower than a reference value after the start cranking. Internal combustion engine. 11. An engine speed is detected as an operating state,
The internal combustion engine according to claim 9, wherein fuel injection from the first fuel injection valve is started when the engine speed becomes equal to or higher than a reference value after the start cranking. 12. The fuel injection from the first fuel injection valve is started when the intake valve temperature is detected as an operating condition and the intake valve temperature becomes equal to or higher than a reference value after the start cranking. Internal combustion engine. 13. An engine speed is detected as an operating state,
The internal combustion engine according to claim 9, wherein fuel injection from the first fuel injection valve is started when a predetermined time has elapsed after the engine rotation speed became equal to or higher than the reference value after the start cranking. 14. The internal combustion engine according to claim 9, wherein when the fuel injection from the first fuel injection valve is started, the fuel injection from the second fuel injection valve is stopped.