JPH04171240A - Fuel injection timing controller for engine - Google Patents

Abstract

PURPOSE:To provide both promotion of gasification and atomization of fuel and improvement in a responsive property by providing an assist air control amount setting means for setting an control amount of an assist air controlling valve and a fuel injection timing altering means for altering the fuel injection timing by a fuel injection valve. CONSTITUTION:An assist air controlling valve 13 is controlled such that an assist air amount flowing in an assist air path 12 is controlled according to various requirements based on the output of a running state detecting means for detecting the running state of an engine 1, for example, increased in low rotation and load and decreased in high rotation and load. Assist air controlled properly by the assist air controlling valve 13 is supplied through the assist air path 12 to the proximity of a jet of a fuel injection valve 11. Also, a fuel injection timing altering means alters the fuel injection timing of the fuel injection valve 11 according to the requirements for setting an assist air control amount setting means, so that both promotion of gasification and atomization of fuel and improvement in a responsive property can be attained.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention relates to a fuel injection timing control device for an engine that supplies assist air near the nozzle of a fuel injection valve to promote atomization of fuel. be.

(Prior art) Fuel injected into the intake passage of an engine by a fuel injection valve generally has a higher rate of vaporization than fuel supplied by a carburetor or the like.
Poor atomization. Therefore, as described in, for example, Japanese Utility Model Application Publication No. 2-46071, assist air is supplied to the vicinity of the nozzle of the fuel injection valve provided in the intake passage to promote atomization of the fuel. In this case, the assist air passage is configured to introduce air from upstream of the throttle valve in the intake passage by means of a differential pressure, and a flow control valve is usually interposed in the middle of the assist air passage.

(Problem to be solved by the invention) Conventionally, assist air has been used exclusively to atomize the injected fuel, but assist air also has the effect of increasing the flow velocity of the supplied fuel, and for that purpose. The fuel response will vary depending on the assist air supply conditions. On the other hand, depending on the engine operating state, various inconveniences may occur in terms of fuel responsiveness due to changes in the assist air supply conditions.

In other words, supplying assist air promotes fuel atomization, but if you do this when the engine is idling, the amount of intake air will increase by the amount of anostonia, which will increase the engine speed, making it difficult to maintain the engine speed at a low fuel consumption setting. I won't be able to do it.

Therefore, it may be possible to specifically supply assist air to a predetermined area other than when the engine is idling. However, when the assist air supply area and non-supply area are set in this way, when the assist air supply state is switched from the assist air supply state to the non-supply state, the fuel temporarily adheres to the vicinity of the exit of the assist air passage in the fuel injection valve. This causes a problem in that the air-fuel ratio becomes lean transiently and the running performance deteriorates.

In addition, when the engine is running at low speed and under low load, the amount of intake air is relatively small and the combustibility is poor, so it is required to atomize the fuel to improve vaporization and atomization as much as possible.
At high rotation speeds and high loads, if the vaporization and atomization are improved too much, the filling efficiency may actually decrease. Therefore, it has been considered to control the amount of assist air in accordance with operating conditions such as engine load. However, when the amount of assist air is changed according to the operating conditions in this way, the fuel flow velocity changes depending on the amount of assist air, and the time it takes for all the fuel, including attached fuel, to enter the combustion chamber changes. . Therefore, in one of the regions, the fuel injection timing deviates from the appropriate setting, causing a problem in which the fuel does not fully enter the combustion chamber during the intake stroke.

The present invention has been made in view of the above-mentioned problems, and is a device that controls the supply of assist air according to the engine operating condition, and in which the supply of assist air is controlled depending on the engine operating condition. The purpose is to achieve both acceleration of fuel vaporization/atomization and improvement of responsiveness.

(Means for Solving the Problem) The present invention recognizes the above-mentioned disadvantage caused by the change in fuel responsiveness when the assist air supply conditions are changed depending on the engine operating condition, and solves this problem by controlling the fuel injection timing. It has been found that this problem can be solved, and this configuration is as shown in FIG.

That is, the fuel injection timing control device for an engine according to the present invention includes an assist air passage that supplies assist air to the vicinity of the nozzle of the fuel injection valve provided in the intake passage of the engine;
An assist air control valve installed in this assist air passage, an operating state detection means for detecting the operating state of the engine, and a control amount of the assist air control valve according to various conditions based on the output of this operating state detection means. The present invention is characterized by comprising an assist air control amount setting means for setting an assist air control amount, and a fuel injection timing changing means for changing the timing of fuel injection by a fuel injection valve according to the setting conditions of the assist air control amount setting means.

In addition, particularly when supplying assist air specifically to a predetermined engine operating region, the assist air control amount setting means ``--'' determines whether the assist air is supplied to the assist air supply area or to the assist air non-supply area based on the engine operating state. The fuel injection timing changing means advances the fuel injection timing earlier than usual when transitioning from the assist air supply region to the assist air non-supply region.

(Function) The assist air control valve operates according to various conditions based on the output of the operating state detection means that detects the operating state of the engine.
For example, control is performed to increase the amount of assist air flowing through the assist air passage when the engine is at low speeds and under a low load, and to decrease the amount of assist air when the engine is at high speeds and under a high load. Assist air appropriately controlled by the assist air control valve is supplied to the vicinity of the nozzle of the fuel injection valve via the assist air passage, thereby promoting atomization of the fuel.

Manoni changes the fuel injection timing by the fuel injection timing changing means or the fuel injection valve according to the setting conditions of the assist air control amount setting means that defines the control amount of the assist air control valve, thereby improving the fuel responsiveness. Secured.

Further, the assist air control amount setting means is configured to set an assist air supply region and an assist air non-supply region based on the engine operating state, thereby specifying the supply of assist air to a predetermined engine operating region. In this case, the fuel injection timing changing means advances the fuel injection timing earlier than usual when transitioning from the assist air supply region to the assist air non-supply region. Even if adhering fuel temporarily accumulates near the exit of the assist air passage in the fuel injection valve when switching from the assist air supply state to the non-supply state, the
All injected fuel, including subsequent accumulated fuel, can be allowed to enter the combustion chamber of the engine during the intake stroke, thereby preventing lean air/fuel ratios during transients.

(Example) Examples will be described below based on the drawings.

FIG. 2 is an overall system diagram of an embodiment of the present invention. In this embodiment, the engine l is a ■-type multi-cylinder engine having a plurality of cylinders in left and right banks 2 and 3, respectively,
Each independent intake passage 5 communicating with the intake boat 4 of each cylinder of the left and right banks 2.3 communicates with a surge tank 6 disposed above between the left and right banks 2.3. In addition, an air cleaner 8. An air flow meter 9 and a throttle valve IO are provided, respectively.

Furthermore, a fuel injection valve 11 is provided in the independent intake passage 5 of each cylinder near the connection portion with the intake boat 4. Further, the intake passage 7 is provided with an assist air passage 2 that branches from a position upstream of the throttle valve IO, and a solenoid valve 13 is interposed in the assist air passage 12. Further, the assist air passage 12 branches on the downstream side and communicates with the vicinity of the injection port of each fuel injection valve 11. Assist air passage 1 due to differential pressure from upstream of throttle valve IO
The air introduced into the fuel injector 2 is supplied as assist air to the vicinity of the nozzle of each fuel injection valve 11 to promote atomization of the injected fuel.

The solenoid valve 13 and each fuel injection valve ll are controlled by a control unit 14. Therefore, the control unit 14 receives an intake air amount signal from the air flow meter 9.

Rotation signals and the like from the crank angle sensor 15 are input.

The supply of assist air is stopped at the low rotation and low load side of the engine, crossing line A shown in FIG. 3, and is supplied at the higher rotation and high load side of the engine.

On the other hand, fuel injection is normally performed at a set timing during the exhaust stroke, as shown by black in FIG. However, when switching from assist air supply state to non-supply state,
The fuel injection timing is advanced to the timing shown in (■) in FIG. 4 until a predetermined period of time has elapsed. The B line shown by the broken line in Fig. 3 indicates the fuel injection timing set by the above
This is the control line that changes from ■ to ■. This B line is set at a slightly higher rotation and higher load side than the assist air switching A line so that the injection timing is switched somewhat earlier when transitioning from the assist air supply state to the non-supply state.

FIG. 5 is a flowchart for executing control in this embodiment. In the figure, reference numeral S 1-316 indicates each step. This flow will be explained step by step below.

Start and first, set the intake air amount (Qa) with Sl.

Read various signals such as crank angle and engine speed (NE).

Next, in S2, the fuel injection amount is calculated. That is, Q
A/NE is multiplied by a constant K to obtain the basic injection amount, and various corrections such as acceleration correction and feedback correction are added thereto to calculate the final fuel injection amount.

Next, in S3, it is determined whether or not the area where assist air is supplied is determined depending on whether the operating state is on the high-speed, high-load side of line A in FIG.

If YES in S3, in S4 the air is turned on and the solenoid valve 13 is controlled to open.

Next, in S5, it is determined whether the engine is on the low-speed, low-load side of line B in FIG. 3. If No, the normal injection timing (2) is set in S6. Then, the process goes to S7 to determine whether or not it is the injection time based on the crank angle signal, and when the injection time comes, the injection is executed in S8.

Also, if S5 is on the low rotation and low load side from the B line, S
In step 9, change the fuel injection timing from ■ to ■, and then change the SIO
Determine whether the rotation is on the low rotation/low load side from the A line.

If YES in SIO, the process goes to S11 and the solenoid valve 13 is controlled to close in order to cut off the assist air. Also, a timer is started in S12, and the timer value T becomes the set value T in S13. It is determined whether the predetermined period of time has been reached, that is, whether a predetermined period of time has elapsed. Then, go to S7 with the injection timing set to ■ until a predetermined time has elapsed, then proceed to S8 to perform injection, and if YES, that is, the predetermined time has elapsed, go to S14 and change the fuel injection timing from ■ to ■. .

Also, if it is NO in S3, that is, it is not in the area where assist air is supplied, the process goes to S15 to close the solenoid valve 13 to cut off the assist air, sets the normal fuel injection timing ■ in S16, and goes to S7. Go to S8 and perform injection.

According to this embodiment, since the assist air is stopped in the low rotation and low load region, it is possible to suppress unnecessary increases in the engine speed due to the assist air in the region including idling, and the assist air supply By temporarily advancing the fuel injection timing when transitioning from the region to the non-supply region, deterioration of fuel responsiveness at the time of transition can be prevented.

Next, another embodiment of the present invention is shown in FIGS. 6 and 7.
This will be explained using figures.

In this embodiment, as shown in Fig. 6, the amount of assist air is increased at low engine speeds and low loads when it is especially necessary to promote vaporization and atomization of the fuel, and at high engine speeds where it is not necessary to promote vaporization and atomization by assist air. This is based on assist air control that reduces the amount of assist air when the load is high, and in this case, injection timing control is performed that takes into account changes in fuel flow velocity due to changes in the amount of assist air. In other words, in areas where the amount of assist air is large, the fuel flow rate increases due to the assist air, so even if the injection timing is delayed considerably, the fuel will enter the combustion chamber during the intake stroke.The fuel injection timing is shown by ■ in Figure 7. Set just before the intake stroke. Furthermore, in a region where the amount of assist air is small, fuel must be injected earlier than when the amount of assist air is large, so the injection timing is set at the timing shown by ■ during the exhaust stroke. Further, in the assist air non-supply region on the low rotation and low load side, the fuel injection timing is set to the earliest timing as shown by ■.

(Effects of the Invention) Since the present invention is configured as described above, the fuel injection timing can always be appropriately set according to changes in fuel responsiveness caused by anstonia supply conditions, and fuel vaporization and atomization can be promoted. It is possible to improve responsiveness at the same time.

[Brief explanation of drawings]

Fig. 1 is an overall configuration diagram of the present invention, Fig. 2 is an overall nostem diagram of an embodiment of the present invention, Figs. 3 and 4 are control characteristic diagrams of the embodiment, and Fig. 5 is a diagram of the control characteristics of the embodiment. A flowchart for executing the control, and FIGS. 6 and 7 are control characteristic diagrams according to other embodiments of the present invention. l, engine, 11・fuel injection valve, 12. Assist air passage, 13. Solenoid valve (assist air control valve)
, 14: Control unit. Agent Patent Attorney Jun Susumu Fuji −

Claims (2)

[Claims] (1) an assist air passage that supplies assist air to the vicinity of the nozzle of the fuel injection valve provided in the intake passage of the engine;
an assist air control valve interposed in the assist air passage; an operating state detection means for detecting the operating state of the engine; and control of the assist air control valve according to various conditions based on the output of the operating state detection means. The present invention is characterized by comprising an assist air control amount setting means for setting the assist air control amount setting means, and a fuel injection timing changing means for changing the timing of fuel injection by the fuel injection valve according to the setting conditions of the assist air control amount setting means. Engine fuel injection timing control device. (2) The assist air control amount setting means sets an assist air supply region and an assist air non-supply region based on the operating state of the engine, and the fuel injection timing changing means selects the assist air supply region from the assist air supply region. 2. The fuel injection timing control device for an engine according to claim 1, wherein the fuel injection timing is made earlier than usual when transitioning to the air non-supply region.