JPH0559267B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a fuel injection device for an engine in which the intake period is controlled by a control valve installed in an intake passage.

(Prior art) Conventionally, a control valve (rotary valve) that opens and closes at a predetermined timing in conjunction with the rotation of the crankshaft is provided in the intake passage upstream of the intake valve of an engine, and the opening and closing timing of this control valve is controlled by throttle operation. For example, a technology that adjusts according to the
It is known as seen in No. 55-96313. In this engine, by adjusting the opening/closing timing (particularly the closing timing) of the control valve installed in the intake passage, the closing timing of the intake stroke that started with the opening operation of the intake valve, that is, the end timing of intake, can be adjusted. It is possible to adjust the actual intake period and thereby change the amount of intake air according to the load, thereby reducing pumping loss.

In addition, in engines equipped with a fuel injection device, the fuel injection valve is installed in the intake passage that leads to the combustion chamber via the intake valve. Stratified combustion technology, in which fuel is unevenly distributed in the upper part of the combustion chamber and combustion is performed in a stratified state, is known, for example, as seen in JP-A-56-148636 or JP-A-58-85319. ing. This stratified combustion is
By unevenly distributing fuel in the upper layer of the combustion chamber, the air-fuel ratio necessary for ignition can be secured near the spark plug, and good combustibility can be obtained in the lower layer even with only air or a very dilute mixture. This has the advantage of making the overall air-fuel ratio leaner, improving fuel efficiency, and suppressing the emission of unburned components, thereby improving emission performance.

However, when applying the stratified charge combustion technology to an engine equipped with the control valve, or when attempting to atomize the injected fuel by injecting fuel when the intake flow velocity is high, it is necessary to simply adjust the fuel injection timing. It is not possible to select the optimal injection timing by simply injecting in response to the opening and closing of the intake valve.

(Object of the Invention) In view of the above-mentioned circumstances, the present invention provides a fuel injection device that selects the optimum fuel injection timing in an engine in which a control valve is provided in the intake passage to control the actual intake closing timing. The purpose is to

(Structure of the Invention) The fuel injection device of the present invention adjusts the fuel injection timing by the fuel injection valve provided in the intake passage near the intake valve according to the closing timing of the control valve interposed in the intake passage. The present invention is characterized by being equipped with a control device that advances the injection timing if the timing is earlier, and controls the fuel to be injected in the latter half of the period between when the intake valve opens and when the control valve closes.

(Effects of the Invention) According to the present invention, the fuel injection timing is controlled according to the opening and closing of the control valve that controls the actual intake closing timing,
For example, by setting the fuel injection timing to perform fuel injection in the latter half of the intake period between when the intake valve opens and the control valve closes when the load is low, the fuel that flows into the combustion chamber at a relatively late time can be injected into the combustion chamber. It is possible to achieve stratified combustion through stratification by unevenly distributing the fuel in the upper layer, thereby improving fuel efficiency and emission performance.
In addition, for example, the fuel injection timing is set to coincide with the intake period when the control valve opens and closes, and when the piston speed is high. If the closing timing of the engine is advanced, the stratification effect of injecting fuel in the latter half of the intake period can improve combustibility, so the fuel injection timing is selected to be the optimal injection timing that meets various requirements. It is something that can be done.

(Example) Hereinafter, an example of the present invention will be described with reference to the drawings.
FIG. 1 shows an overall configuration diagram of an engine with a fuel injection device, and the engine 1 has four cylinders C, first to fourth (however, only one cylinder is shown in the figure), Combustion chamber 2 of each cylinder C above
are connected to an intake passage 5 and an exhaust passage 6 via an intake valve 3 and an exhaust valve 4, respectively, and each intake passage 5 has a control valve 7 formed of a rotary valve.
is installed. This control valve 7 is rotationally driven in conjunction with a crankshaft (not shown) to open and close the intake passage 5 at predetermined timing, and the opening/closing timing relative to the crank angle is changed in conjunction with the throttle operation. It is set in. An air cleaner 9 is connected to the upstream end of the intake passage 5, and an air flow meter 10 for measuring the intake air flow rate is provided downstream of the air cleaner 9. A fuel injection valve 12 is disposed in a downstream portion of each intake passage 5 facing the intake valve 3, and a fuel supply passage 13 is connected to each fuel injection valve 12 via a regulator (not shown). The fuel injection valve 12 is connected to a fuel tank, and fuel pressure is supplied to the fuel injection valve 12 via the regulator so that the pressure difference between the pressure and the intake passage pressure is always constant.

The specific structure of the intake passage 5 is shown in FIG. 2.
A piston 15 is disposed in the cylinder C of the cylinder block 14 so as to be able to reciprocate.
The upper end of a connecting rod 16 is swingably connected to the connecting rod 5. A cylinder head 17 is mounted on the cylinder block 14, and an intake port 18 and an exhaust port 19 are opened to communicate with a combustion chamber 2 recessed in the bottom surface of the cylinder head 17, and an intake passage 5 and an exhaust passage 6 are respectively opened. is connected to.
The intake and exhaust ports 18 and 19 are provided with an intake valve 3 and an exhaust valve 4, which are seated on respective valve seats.

An intake manifold 20 that forms the intake passage 5 is provided with a control valve 7 that is a rotary valve that is driven from the crankshaft of the engine 1 via, for example, a gear transmission mechanism. This control valve 7 is rotated at a reduced speed of 1/2 of the crankshaft rotation speed, and
The opening/closing timing is adjusted by an opening/closing timing adjusting means (not shown), and when the load increases due to a large amount of accelerator operation, the closing timing of the control valve 7 is adjusted to be delayed to increase the amount of intake air. This is to increase the output.

In addition, on the downstream side of the control valve 7 of the intake passage 5, the fuel injection valve is located at a position relatively close to the intake port 18 that is opened and closed by the intake valve 3, and so as to inject fuel toward the combustion chamber 2. A valve 12 is provided. That is, the fuel injected from the fuel injection valve 12 is configured to directly flow into the combustion chamber 2 from the intake port 18.

The fuel injection timing and injection amount by this fuel injection valve 12 are controlled by a control device 22 as shown in FIG.
This is done by a control signal from the (CPU), that is, a fuel injection pulse.

The control device 22 receives an intake air amount signal from the air flow meter 10, and also receives a phase signal from a phase sensor 23 (in this example , the opening timing signal of the control valve 7) and the crank angle signal from the crank angle sensor 24 which detects the crank angle of the engine 1 and the piston top dead center TDC of the first cylinder from the rotation angle of the distributor, respectively. This is what is input. Note that 25 is an ignition switch.

The control device 22 determines the fuel injection amount according to the engine speed and the amount of intake air, and also determines the amount of fuel to be injected from the fuel injection valve 12 in accordance with the opening/closing timing of the control valve 7, for example, when the engine is under low load. In the second half of the period, the fuel necessary for one combustion is injected and supplied for one intake stroke, and the fuel injection timing is set to perform stratified combustion, and the pulse width corresponding to the fuel injection amount is set at a predetermined timing. This outputs a fuel injection pulse to the fuel injection valve 12 of each cylinder.

As shown in Fig. 3, the fuel injection timing for carrying out the stratified charge combustion is determined when the intake valve 3 begins to open before top dead center TDC in the opening curve of the intake valve 3.
During the intake stroke from when the intake valve 3 closes after bottom dead center BDC to IC, the control valve 7 closes much earlier than the closing timing IC of the intake valve 3 at low load, as shown by the solid line. In general, the intake period during which intake air flows into the combustion chamber 2 is shortened, and at the same time, when the load is high, the intake valve 3 is closed at a later time near IC, as shown by the broken line, to lengthen the intake period. This increases the amount of air.

With respect to the opening/closing timing of the intake valve 3 and the opening/closing timing of the control valve 7, the fuel injection end timing is set such that the fuel injection ends in the latter half of the intake period, that is, a predetermined period earlier than the control valve 7 closes. θ ₂ is set, and the injection start timing θ ₁ is set at a time that is advanced by a period θ corresponding to the pulse width corresponding to the fuel injection amount with respect to the injection end timing θ ₂ .

As a result, fuel flows into the combustion chamber 2 relatively late in the intake period when the intake valve 3 and the control valve 7 are open, and is unevenly distributed and supplied to the upper part of the combustion chamber 2.
Stratification is maintained.

Next, the operation of the control device 22 will be explained with reference to the flowchart shown in FIG.

When the engine starts (starts) as the ignition switch 25 is turned on, the control device 22 stores the opening timing and closing timing of the intake valve 3 in the registers Io and Ic in step S1, and then the crank angle sensor 24 and the closing timing of the intake valve 3. Each signal of the air flow meter 10 and phase sensor 23 is read and each value is stored in registers T, F, and _R1 (steps S2 to
S4). Next, in step S5, the engine speed is calculated using the crank angle in register T and stored in register N, and then fuel injection is performed using the engine speed and intake air amount in registers N and F. Calculate the amount, perform acceleration correction and temperature correction as necessary, and store the actual injection amount in register Q (step
S6), determine the injection angle θ for one intake stroke from the actual fuel injection amount in the register Q and store it in the register θ (step S7). Step S8
Now, add the known valve opening period R of control valve 7 to the control valve opening timing in register _R1 to determine the control valve closing timing.
_R2 is calculated, and then, in step S9, the air inflow period A from the intake valve opening timing Io to the control valve closing timing _R2 is calculated.
Calculate.

Next, in step S10, the injection end timing θ ₂ is calculated and in step S11, the injection start timing θ ₁ is calculated and determined. This injection end timing θ ₂ is determined at a predetermined timing earlier than the control valve closing timing R ₂ by multiplying the air inflow period A by a coefficient α (α>1) and adding it to the intake valve opening timing Io. Based on this injection end time θ ₂ , the injection start time θ ₁ is determined according to the actual injection amount θ in the register θ.

In this way, when the injection start timing θ ₁ and the injection end timing θ ₂ are determined, the system waits in step S12 until the injection start timing θ ₁ is reached, and when the injection start timing θ ₁ is reached, the fuel injection valve is adjusted in step S13. 12, and waits in step S14 while continuing to drive the fuel injector 12. When the injection end time θ ₂ has arrived, the output of the "1" signal is stopped (step S15), and the fuel is injected as described above. After applying the injection pulse, follow the steps above.
Return to S1.

In this way, the fuel injection amount is determined according to the engine speed and the intake air amount, and the control valve 7
determines the air inflow period corresponding to the closing timing of the engine, determines the injection start timing and injection end timing suitable for stratified combustion according to the fuel injection amount and the air inflow period,
Control is performed to apply fuel injection pulses from the injection start time to the injection end time.

According to the embodiments described above, stratified combustion is performed by unevenly distributing fuel, thereby improving fuel efficiency and combustion efficiency.

Incidentally, in the above embodiment, a case has been described in which the increase/decrease control of the fuel injection amount is performed by variable control of the injection time, but the fuel injection amount can be controlled by variable control of the injection time and increase/decrease control of the fuel pressure of the fuel injection valve. You may perform increase/decrease control.

Further, in the above embodiment, an example is explained in which the fuel injection timing is set to perform stratified combustion, but in other cases, for example, the fuel injection timing for achieving fuel atomization is set when the intake valve 3 is open. The setting may be made to correspond to the fuel injection pulse width, centered around the time when the piston speed reaches its maximum approximately in the middle of the valve period. In order to avoid fuel injection after the control valve closes, the set timing is changed forward by a time corresponding to the delay time for the injected fuel to flow into the combustion chamber 2 from the closing timing of the control valve 7. As described above, the fuel injection timing is changed and controlled in response to the change in the closing timing of the control valve 7.

[Brief explanation of the drawing]

Fig. 1 is an overall configuration diagram of an engine with a fuel injection device according to an embodiment of the present invention, Fig. 2 is a vertical sectional view of main parts showing a specific structural example of the engine, and Fig. 3 is an opening/closing diagram of an intake valve and a control valve. FIG. 4 is a timing chart showing the fuel injection timing with respect to the timing, and FIG. 4 is a flowchart showing the processing of the control device. 1... Engine 2... Combustion chamber 3... Intake valve 5... Intake passage 7... Control valve 12... Fuel injection valve 22... Control device 23... Phase sensor 24... Crank angle sensor.

Claims (1)

[Claims] 1. In an engine in which a control valve that is opened and closed in conjunction with the rotation of the crankshaft is provided in the intake passage upstream of the intake valve, and the actual intake closing timing is controlled in accordance with the closing timing of this control valve, A fuel injection valve is provided in an intake passage near the intake valve that communicates with the combustion chamber via the intake valve, and when the closing timing of at least the control valve is controlled to advance in accordance with the closing timing of the control valve, the intake valve is opened and controlled. 1. A fuel injection device for an engine, comprising a control device that changes and controls fuel injection timing from a fuel injection valve so that fuel is injected in the latter half of an intake period during which a valve is closed.