JP2881606B2 - Engine fuel injection timing control device - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a fuel injection timing control device for an engine that supplies assist air to the vicinity of an injection port of a fuel injection valve in order to promote atomization of fuel. is there.

(Prior Art) Fuel injected into an intake passage of an engine by a fuel injection valve is generally less vaporized and atomized than fuel supplied by a carburetor or the like. Therefore, as described in, for example, Japanese Utility Model Laid-Open No. 2-46071, assist air is supplied to the vicinity of an injection port of a fuel injection valve provided in an intake passage to promote atomization of fuel. In this case, the assist air passage is configured to introduce air by a differential pressure from the upstream of the throttle valve of the intake passage, and a flow control valve is generally provided in the middle of the assist air passage.

(Problems to be Solved by the Invention) Conventionally, the assist air has been used only for atomizing the injected fuel. However, the assist air also has an effect of increasing the flow rate of the supplied fuel. The fuel responsiveness changes depending on the supply condition of the assist air. Therefore, depending on the operating state of the engine, various inconveniences arise in terms of fuel responsiveness due to changes in the supply condition of the assist air.

In other words, the supply of assist air promotes atomization of fuel, but if this is done at the time of engine idling or the like, the amount of intake air will increase by the amount of assist air, and the rotation will increase, and the engine rotation at the low fuel consumption setting will be reduced. No longer available. Therefore, it is conceivable that the assist air supply is performed by specifying the air supply to a predetermined area other than an idle time. However, when the supply area and the non-supply area of the assist air are set in this way, when the state is switched from the assist air supply state to the non-supply state, the fuel adhering temporarily near the outlet of the assist air passage in the fuel injection valve. As a result, there is a problem that the air-fuel ratio transiently becomes lean and travelability deteriorates.

In addition, when the engine is running at low speed and low load, it is required to atomize the fuel to improve vaporization and atomization as much as possible, while the intake amount is relatively small and the combustibility is poor. On the other hand, if the vaporization / atomization is made too good, there is a disadvantage that the filling efficiency is rather lowered.
Therefore, it has been considered to perform control such that the amount of assist air is changed according to an operating state such as an engine load.
However, when the assist air amount is changed in accordance with the operation state in this way, the fuel flow velocity changes according to the assist air amount, and the time until all the fuel including the adhering fuel enters the combustion chamber changes. . Therefore, in any region, the fuel injection timing deviates from an appropriate setting, and there is a problem that the fuel cannot enter the combustion chamber during the intake stroke.

The present invention has been made in view of the above problems,
In controlling the supply of assist air according to the engine operating state, an appropriate fuel injection timing is always obtained according to a change in fuel responsiveness due to the assist air,
The purpose is to achieve both promotion of fuel vaporization and atomization and improvement of responsiveness.

(Means for Solving the Problems) The present invention recognizes the inconvenience caused by the change in fuel responsiveness when the supply condition of the assist air is changed according to the engine operating state, and solves this by fuel injection timing control. It has been found that this 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 for supplying assist air near the injection port of a fuel injection valve provided in an intake passage of the engine, and an assist air passage provided in the assist air passage. An air control valve, operating state detecting means for detecting an operating state of the engine, assist air control amount setting means for setting a control amount of the assist air control valve according to various conditions based on an output of the operating state detecting means, 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.

In particular, when the supply of assist air is specified and performed in a predetermined engine operation region, the assist air control amount setting means sets the assist air supply region and the assist air non-supply region based on the operation state of the engine. The fuel injection timing changing means makes the fuel injection timing earlier than usual when shifting from the assist air supply region to the assist air non-supply region.

In such a case, the fuel injection timing is normally set to the timing during the exhaust stroke, and when switching from the assist air supply region to the assist air non-supply region, the fuel injection timing is set earlier than usual until a predetermined time has elapsed. It is better to do so.

The assist air control amount setting means sets the assist air supply region and the assist air non-supply region based on the operating state of the engine, and sets the low engine speed and low load side in the assist air supply region to the assist air amount. The region may be set to be large, and the high rotation and high load side may be set to a region where the amount of assist air is small.

Then, in that case, the fuel injection timing changing means sets the fuel injection timing to the timing immediately before the intake stroke in the region where the assist air amount is large, and sets the fuel injection timing to the timing during the exhaust stroke in the region where the assist air amount is small. Preferably, the fuel injection timing is set to a timing earlier than the above-mentioned timings in the assist air non-supply region on the low rotation speed and low load side.

(Operation) The assist air control valve increases the amount of assist air flowing through the assist air passage at low rotation speed and low load, for example, according to various conditions based on the output of the operating state detecting means for detecting the operating state of the engine. At the time of high rotation and high load, control is performed to reduce the assist air amount. Then, the assist air properly controlled by the assist air control valve is supplied to the vicinity of the injection port of the fuel injection valve through the assist air passage, whereby the atomization of the fuel is promoted.
Further, the fuel injection timing changing means changes the fuel injection timing of the fuel injection valve according to the setting condition of the assist air control amount setting means for defining the control amount of the assist air control valve, thereby securing the fuel responsiveness. Is done.

In addition, the assist air control amount setting means sets the assist air supply region and the assist air non-supply region based on the operating state of the engine, so that the assist air supply is specified in a predetermined engine operation region. In that case, the fuel injection timing changing means, when shifting from the assist air supply region to the assist air non-supply region, makes the fuel injection timing earlier than usual, Even when the deposited fuel temporarily accumulates near the outlet of the assist air passage in the fuel injection valve at the time of switching from the assist air supply state to the non-supply state, all the injected fuel including the temporarily accumulated fuel is removed. During the intake stroke, the combustion chamber of the engine can be made to pass completely, thereby preventing the air-fuel ratio from becoming lean during a transient.

(Example) Hereinafter, an example is described based on drawings.

FIG. 2 is an overall system diagram of one embodiment of the present invention.
In this embodiment, the engine 1 is a V-type multi-cylinder engine having a plurality of cylinders in left and right banks 2, 3, respectively.
The independent intake passages 5 communicating with the intake ports 4 of the respective cylinders of the left and right banks 2 and 3 are respectively connected to a surge tank 6 disposed above the left and right banks 2 and 3. Also,
In an intake passage 7 connected to the inlet of the surge tank 6, an air cleaner 8, an air flow meter 9 and a throttle valve 10 are provided from the upstream. Further, in the independent intake passage 5 of each cylinder, a fuel injection valve 11 is provided in the vicinity of a connection portion with the intake port 4. Further, an assist air passage 12 branched from an upstream position of the throttle valve 10 is provided in the intake passage 7, and a solenoid valve 13 is provided in the assist air passage 12. The downstream side of the assist air passage 12 is branched and communicated with the vicinity of the injection port of each fuel injection valve 11. The air introduced into the assist air passage 12 by the differential pressure from the upstream of the throttle valve 10 is supplied as assist air to the vicinity of the injection port of each fuel injection valve 11 to promote atomization of the injected fuel.

The solenoid valve 13 and each fuel injection valve 11 are controlled by a control unit 14. Therefore, the control unit 14 receives an intake air amount signal from the air flow meter 9, a rotation signal from the crank angle sensor 15, and the like.

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

On the other hand, the fuel injection is normally performed at a timing set during the exhaust stroke as shown in FIG. However,
When switching from the assist air supply state to the non-supply state, the fuel injection timing is advanced to the timing shown in FIG. 4 until a predetermined time has elapsed. A dashed line B in FIG. 3 is a control line for changing the fuel injection timing from the above when shifting from the assist air supply zone to the non-supply zone as indicated by an arrow in the figure. The B line is set slightly higher than the A line for assist air switching so that the injection timing switches slightly earlier when shifting from the assist air supply state to the non-supply state.

FIG. 5 is a flowchart for executing the control of this embodiment. In the figure, reference numerals S1 to S16 indicate each step. Less than,
This flow will be described step by step.

First, various signals such as intake air amount (Qa), crank angle and engine speed (NE) are read in S1.

Next, the fuel injection amount is calculated in S2. That is, Qa / N
A basic injection amount is obtained by multiplying E by a constant K, and various corrections such as acceleration correction and feedback correction are added thereto to calculate a final fuel injection amount.

Next, in S3, it is determined whether or not it is in the region where the assist air is supplied, based on whether or not the operation state is on the higher rotation and higher load side than the line A in FIG. If YES in S3, the solenoid valve is turned on in S4 to turn on the assist air.
13 is controlled to open.

Next, in S5, it is determined whether or not the rotation speed is lower than the line B in FIG. 3, and if NO, the normal injection timing is set in S6. Then, the process proceeds to S7, where it is determined whether or not it is the injection timing based on the crank angle signal. When the injection timing is reached, the injection is performed in S8.

On the other hand, if it is determined in S5 that the rotation speed is lower than that of the B line at low rotation,
To change the fuel injection timing from
It is determined whether or not the speed is lower than the line on a low rotation and low load side.

If YES in S10, the process goes to S11 to close the solenoid valve 13 to cut the assist air. Also, S12
In determining the timer is started, whether the timer value T reaches the set value T ₀ in S13, that is, whether the elapsed predetermined time. Until a predetermined time has elapsed, the process proceeds to S7 with the injection timing set, and injection is performed in S8. If YES, that is, if the predetermined time has elapsed, the fuel injection timing is returned from S14.

If NO in S3, that is, if it is not in the region for supplying the assist air, the process goes to S15 to close the solenoid valve 13 so as to cut off the assist air, sets a normal fuel injection timing in S16, and goes to S7. Inject at S8.

According to this embodiment, since the assist air is stopped in the low-speed low-load region, unnecessary increase of the engine speed due to the assist air can be suppressed in the region including the idling time. By temporarily advancing the fuel injection timing when shifting from the area to the non-supply area, deterioration of fuel responsiveness at the time of shifting is prevented.

Next, another embodiment of the present invention will be described with reference to FIGS. 6 and 7. FIG.

In this embodiment, as shown in FIG. 6, the assist air amount is increased at the time of low engine speed and low load where the engine is particularly required to promote vaporization and atomization of the fuel. At the time of high load, it is assumed that assist air control is performed to reduce the amount of assist air. In this case, injection timing control is performed in consideration of a change in fuel flow velocity due to a change in assist air amount. That is, in the region where the assist air amount is large, the fuel flow rate is increased by the assist air, so that even if the injection timing is considerably delayed, the fuel enters the combustion chamber during the intake stroke, and the fuel injection timing is as shown in FIG. Set immediately before the intake stroke.
Further, in the region where the assist air amount is small, the fuel must be injected earlier than when the assist air amount is large, so that the injection timing is set at the timing shown during the exhaust stroke. Further, in the low-speed low-load assist air non-supply region, the fuel injection timing is set to the earliest timing as shown by.

(Effect of the Invention) Since the present invention is configured as described above, the fuel injection timing can always be appropriately set according to the change in fuel responsiveness due to the assist air supply condition, and the fuel vaporization / atomization promotion and response Compatibility can be achieved.

[Brief description of the drawings]

1 is an overall configuration diagram of the present invention, FIG. 2 is an overall system diagram of one embodiment of the present invention, FIGS. 3 and 4 are control characteristic diagrams of the embodiment, and FIG. FIGS. 6 and 7 are control characteristic diagrams according to another embodiment of the present invention. 1: engine, 11: fuel injection valve, 12: assist air passage, 1
3: Solenoid valve (assist air control valve), 14: Control unit.

────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Masayuki Tanaka 3-1, Shinchi, Fuchu-cho, Aki-gun, Hiroshima Prefecture Inside Mazda Co., Ltd. (56) References Hira 3-17278 (JP, U) Hira 2 −141647 (JP, U) (58) Field surveyed (Int. Cl. ⁶ , DB name) F02D 41/34

Claims (5)

(57) [Claims] An assist air passage for supplying assist air to the vicinity of an injection port of a fuel injection valve provided in an intake passage of an engine, an assist air control valve provided in the assist air passage, and an operating state of the engine Operating state detecting means for detecting the air conditioner, assist air control amount setting means for setting a control amount of the assist air control valve in accordance with various conditions based on an output of the operating state detecting means, and an assist air control amount setting means. A fuel injection timing control device for an engine, comprising: fuel injection timing changing means for changing a timing of fuel injection by the fuel injection valve according to a set condition. 2. An assist air control amount setting means for setting an assist air supply area and an assist air non-supply area based on an operating state of an engine. 2. The fuel injection timing control device for an engine according to claim 1, wherein the fuel injection timing is set earlier than usual when shifting from the range to the assist air non-supply region. 3. The fuel injection timing changing means always sets the fuel injection timing to a timing during an exhaust stroke, and when the fuel is switched from the assist air supply region to the assist air non-supply region, the fuel injection timing is changed until a predetermined time elapses. 3. The fuel injection timing control device for an engine according to claim 2, wherein the timing is set earlier than usual. 4. An assist air control amount setting means sets an assist air supply region and an assist air non-supply region based on an operation state of the engine, and assists a low engine speed and low load side in the assist air supply region. 2. The fuel injection timing control device for an engine according to claim 1, wherein the region with a large amount of air is defined as a region where the high-speed high-load side is defined as a region with a small amount of assist air. 5. The fuel injection timing changing means sets the fuel injection timing to a timing immediately before the intake stroke in a region where the assist air amount is large, and sets the fuel injection timing to a timing during the exhaust stroke in a region where the assist air amount is small. 5. The fuel injection timing control device for an engine according to claim 4, wherein the fuel injection timing is set earlier than the both timings in the assist air non-supply region on the low rotation speed and low load side.