JPS60122240A - Fuel injector of engine - Google Patents

Abstract

PURPOSE:To prevent blow-by of injected fuel in a system wherein the fuel injection completion timing of a fuel injection valve disposed in an intake port is set to the proximity of an intake valve closing timing by compensating the fuel injection completion timing to a slower timing in the operating range where much fuel is injected. CONSTITUTION:In operation of an engine, CPU15 reads and stores each signal of a pressure sensor 8, a water temperature sensor 9, a crank angle sensor 10 and an ignitionn switch 11. If the operation is not made for engine start, CPU computes a reference injection quantity from an engine rpm and a suction negative pressure, and compensates the reference injection quantity according to the temperature of cooling water so as to redetermine the reference injection quantity as an actual injection quantity. From the actual fuel injection quantity an injection angle theta is determined and from both suction valve fully-closed timing and specified-injection completion timing compensatory quantity, an injection completion timing thetaic is determined so as to determine whether theta is larger than the crank angle made between thetaic and an exhaust valve fully-closed timing, or not. If determination of YES is obtained, an injection start timing thetaio according to the injection angle theta is determined based on the timing thetaic, so as to control a fuel injection valve 6.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a fuel injection device for an engine.

[Prior art]

Conventionally, as shown in Japanese Unexamined Patent Application Publication No. 56-148636, in partial load regions where high engine output is not required, fuel is injected almost in the latter half of the intake stroke and the fuel is injected into the upper layer of the combustion chamber where the spark plug is located. There is one in which the air-fuel mixture is formed in the upper part and the air is formed in the lower part, and combustion is carried out in that state.

In this type of fuel injection system, the air-fuel mixture in the upper layer only needs to be brought to an air-fuel ratio that can be ignited using a spark plug (on the other hand, the air-fuel mixture in the lower layer is only air or has a very lean mixture, so the air-fuel mixture as a whole is The fuel ratio becomes extremely lean, which greatly improves fuel efficiency and reduces NOx.

This has the advantage that unburned components such as CO can be reduced.

Furthermore, the mixture layer in the combustion chamber is concentrated in a narrow area near the spark plug, and the gas spoon is occupied by air or a very thin mixture, making it difficult for foreign mixture combustion to occur. It also has the advantage of less occurrence of knocking.

By the way, in the fuel injection system of the L7 engine that performs such stratified combustion, it is desirable that the end timing of fuel injection coincides with the fully closing timing of the intake valve, but in reality it is Fully closed (= intake J1 near J
', the lift amount is small and it is not possible to secure a 1-minute passage area, and there is a certain distance between the fuel injection valve and the combustion chamber, so it takes a long time for the fuel to reach the combustion chamber from the fuel injection valve. Due to reasons such as a delay, it is necessary to set the fuel injection end timing before the intake valve closing timing a. .

And 1. In the device described in the conventional publication, the fuel injection end timing is set to a certain crank angle before the intake valve fully closed timing; ? This injection end crank angle is 4-+7.
The injection start crank angle position was calculated based on the engine position, and the amount of fuel was injected and supplied according to the operating state of the engine.

However, in this conventional fuel injection device, when the amount of fuel to be injected increases, the fuel injection start timing becomes earlier (intake, 1) within the overlap region of the 1st valve (intake, 1st).
) 1 in Fig. 4 showing the valve rift 1 of F air jfl;
Each 1:, R) may be 7 degrees/angle () 7 positions, in which case the injected fuel will directly flow into the exhaust system, worsening combustibility and reducing engine output. There is also the problem that unburned components in the exhaust gas increase, resulting in worsening of emissions. Further, since the fuel flow rate is large, the vaporization of the fuel becomes poor, and this also causes the problem that the combustibility changes to IU().

[Purpose of the invention]

SUMMARY OF THE INVENTION The present invention aims to solve such problems by providing a fuel injection device for an engine that can prevent blow-out of injected fuel in an operating region where there is a lot of dirt and fuel injection, and can promote vaporization and atomization of fuel. be.

[Structure of the invention]

Therefore, the present invention prevents the fuel injection start timing from advancing beyond a predetermined crank angle position in an operating range where the amount of fuel injection is large, thereby preventing the injected fuel from blowing through and is corrected to the delayed side, thereby securing the fuel shortage, and at the same time, a part of the fuel is taken in at the beginning of the next intake stroke, and the heat of the intake valve and the turbulent flow of intake air are used to vaporize the lP charge. It was designed to promote the

〔Example〕

Hereinafter, practical examples of the present invention will be explained with reference to the drawings.

FIG. 1 shows a fuel injection system for an engine according to an embodiment of the present invention. In the figure, 1 is an engine having four cylinders, first to fourth (however, only one cylinder is shown in the figure), and each cylinder has an intake pipe and an exhaust pipe. , 3 are connected, and a slot 7 is connected to the pension part of the intake pipe 2.
Torque valves 4a and 4b are provided, and -1 of the intake pipe 2, the flow bm
Has reached: L Clear 5. A fuel injection valve 6 is disposed in each intake pipe 2 in the vicinity of the intake bow 1-, and each fuel injection valve 6 is connected to a C fuel tank (not shown) via a leg pulley. The fuel injector 6 is supplied with fuel pressure such that the differential pressure with the intake pipe pressure is always constant () through the Regigo rake.

Also, in the figure, 8 is the moon-kasenza that detects the pressure of the air flow in the intake pipe 2, and 9 is the cooling water for the engine 1! i
10 is a crank angle sensor that detects the engine crank angle and the piston top dead center TDC of the first cylinder from the rotation angle of the distributor;
1 is the ignition switch, 12 is the starter motor,
13 is an interface 14, a CPU 15 and a memory 16
The memory 16 stores programs for arithmetic processing of the CPU 15 as shown in a flowchart in FIG. 2. And -1-C
P U15 applies a starting injection pulse to the fuel injection valve 6 so that a predetermined amount of fuel is injected when starting the engine;
On the other hand, after starting the engine, determine the actual fuel injection amount according to the engine operating condition, and if this is less than the setting 91, determine the injection start timing based on the predetermined injection end time of the intake valve fully closed timing, and set the In this case, set the injection start time to 1 no 1.
The fuel injection valve is set to the fully closed crank angle position, and the above-mentioned injection end timing is corrected to the delayed side by notching it, and from this, a fuel injection pulse corresponding to the above-mentioned actual fuel injection amount is applied to the fuel injection valve 6. The fuel injection control is performed.), 1,. Note that 7G is a catalyst installed in the exhaust system.

In the above configuration, the CPUI 5 includes a detection means for detecting that the fuel injection start timing has reached a predetermined crank angle position and outputting a detection signal, and a detection means that outputs a detection signal when the fuel injection start timing has reached a predetermined crank angle position. After the fuel injection end timing is reached, the fuel injection end timing correction means is configured to correct the fuel injection end timing to the delayed side.

Next, the operation will be explained using FIGS. 2 to 4. Here, Figure 3 (al (bl) shows the relationship between the opening/closing timing of the intake valve and the fuel injection timing during operation with a small amount of fuel injection and during operation with a large amount of fuel injection, respectively.
JJI valve lift amount and suction.

The relationship with the opening/closing timing of the exhaust valve is shown. In the figure, F
, O, IO are IJ air valve, intake valve opening timing, E
The fully open timing of the C-JJi air valve, EX, and IN are the valve lift characteristics of the exhaust valve and intake valve.

When the engine starts, the CPU 15 reads the signals from the crank angle sensor Io, pressure sensor 8, and water temperature sensor 9, and stores the respective values in registers T and B.

Wl (steps 20 to 22), reads the starter signal from the ignition switch 11 and stores it in the register S (step 23), and then determines whether or not it is time to start the engine from the contents of the register S. (Step 24).

When the engine starts, the CPU 15 performs step 24.
If YES is determined in step 25, the process proceeds to step 25, where the predetermined starting injection amount β is stored in register I.
A starting injection pulse is created based on the value of , and is applied to the fuel injection valve 6 of the cylinder to be injected, which is determined according to the TDC signal of the first cylinder (step 26), and the process returns to step 2o, where the above-mentioned Repeat the process. The reason why a preset starting injection pulse is generated when the engine is started is because the fuel injection amount cannot be calculated based on the intake air amount at this starting time.

When the engine starts, the CPU 15 makes a negative determination in step 24 and proceeds to step 27, where the engine speed is calculated using the crank angle in the register T and stored in the register R. 1. Calculate the basic fuel injection amount using the engine speed and intake negative pressure in registers R and B, and record it in register 1. O (step 28).

Next, the CPU 15 compares the engine coolant temperature in the register W1 with a set value W, for example 60°C, and if the coolant temperature is below the set value W, the difference between the two (W-Wl> and the correction coefficient 01
Multiply by
+CI (W-Wl) is stored in the register (Step 29), the injection angle θ (see FIG. 3 (al)) is determined from the actual fuel injection amount in the register I, and it is stored in the register θ (Step 30). ), and the intake valve fully closed timing θvc
(Determine the injection end time θ1c-(see FIG. 3 (al)) using the predetermined injection end time correction punch Δθ and the injection end time θic (step 31), and then the injection angle θ is set to the injection end time θic. Step 32).

Here, the closing timing OvC of the intake valve may be set at a crank angle position that does not cause intake air to blow back at a reference engine speed, for example, 3000 rpm, which is the maximum torque. In the valve lift characteristic diagram of the intake valve, this is the initial crank angle position of the ramp portion A at the end of the intake stroke.

Then, if the fuel injection amount is small and the injection angle θ is set (I is smaller than γ, the CPU 15 sets N at step 32).
It is determined that the injection end time θ is determined as o, and the process proceeds to step 33.
ic, determines the injection start time θio (see Figure 3 +8+) according to the actual injection amount θ in the register θ, waits in step 34 until the injection start time θio is reached, and when the injection start time θio is reached, In step 35, a "1" signal is applied to the fuel injection valve 6, and while the valve 6 continues to be driven, step 3
6, and when the injection end time θic is reached, the output of the "1" signal is stopped (step 37). After applying the fuel injection pulse in this way, the process returns to step 20.

In this way, after the engine has started, and if the injection start time does not reach the exhaust valve fully closed crank angle position, the injection start time is advanced according to the engine operating condition, and the set injection starts from the injection start time of -l1, -. Control is performed to apply fuel injection pulses during the end period.

Next, when the fuel injection amount increases and the injection angle θ becomes larger than the set value γ, the CPU 15 executes Y in step 32.
It is determined that E S, and the process proceeds to step 38, where the injection start timing θIO is changed to the exhaust valve fully open crank angle position EC (Fig. 3 (11).
)), and use the equation θ-γ-80 to correct the injection end timing to 980° (see Figure 3 (t, +l
(see step 39). Here, 80 is a crank angle for adjusting the set injection end time θic in a region where the fuel injection amount is small. Next, CP tJ 15 corrects the set injection end time θic to the delayed side using the injection end time correction 980'' obtained above, and calculates the actual injection end time θic' in this case (Fig. 3 (l+ )) (step 40') 1., j-steps 34 to 3
Follow route 7.

In this way, after the engine has started and the injection start timing is I
When the exhaust valve is in the fully closed position, control is performed to set the injection start timing to the exhaust valve fully closed crank angle position and thereby correct the injection end timing for the insufficient fuel to the delayed side.

By the way, if the fuel injection end timing is corrected to the delayed side in this way, -91 of the fuel will be carried into the next intake stroke, and the stratified combustion will be delayed.
Under operating conditions in which a large amount of fuel is supplied, fuel is inhaled over almost the entire period of the intake stroke, and the benefits of stratified combustion described above cannot be expected. Therefore, even if stratified combustion breaks down, a separate Support is ineffective.

In the device of this embodiment as described above, the fuel injection start timing is prevented from advancing beyond the exhaust valve fully closed crank angle position, so blow-out of the injected fuel does not occur, and as a result, the combustion This can prevent deterioration of performance and emissions. Furthermore, since the fuel injection end timing is delayed, it is possible to secure fuel for the shortage caused by restrictions on the fuel injection start timing. Further, a part of the fuel remains in the intake valve 1- after the intake stroke, and this fuel is vaporized and atomized by the heat of the intake valve, and is rapidly inhaled at the beginning of the next intake stroke 7, and the fuel is inhaled at the beginning of the next intake stroke. Good combustibility is maintained because the turbulence of the UIN mixes well with the air.

In the example described above, when starting fuel injection, G1 should not be advanced beyond the fully closed crank angle position of the exhaust valve. (Gage ζ is also acceptable at a predetermined crank angle position on the more delayed side). Mano, two, the present invention uses G to avoid stratified combustion in full operation ↑ 1f1 power, and reduces stratified combustion in some operating ranges, for example, in the partial 1rj ′ian range, not only in the 7-speed engine. The same applies to what you do. Furthermore, the present invention provides fuel
The present invention is not limited to one in which the injection end timing is fixed at a constant lσr crank angle position, but can similarly be applied to one in which it is variably controlled depending on the operating condition, for example.

[Invention glue J fruit]

According to the present invention, the end of the intake stroke rj);
Finished injection by furnace at 11) I! ll is set, and as the injection amount increases, the timing of the injection amount kt) is advanced.
When the amount of fuel injected is large, the injection timing (8/1 open 9f) is prevented from advancing beyond the 8s fixed rank angle position, and the injection end timing is delayed, so that the injection ζ can be prevented, thereby significantly improving combustibility and emissions, and further accelerating vaporization and atomization of fuel, which also has the effect of improving combustibility.

[Brief explanation of drawings]

FIG. 1 is a schematic configuration diagram of an engine fuel injection device according to an embodiment of the present invention, and FIG. 2 is a CPU 15 in the L device.
Fig. 3+8) and tb) are flowcharts of the calculation processing of the L device, respectively. The fourth figure 1 is a diagram showing the relationship between the valve lift amount of the intake and exhaust valves and the opening/closing timing of the intake and exhaust valves. 6...Fuel injection valve, 15...C))tJ (detection means, fuel injection end timing correction means). Patent Applicant Toyo Kogyo Co., Ltd. Agent Patent Attorney Ken Rise - Figure 3 (b) l: IU Si

Claims (1)

[Claims] (1) A fuel injection valve is installed in the intake passage leading to the combustion chamber via the intake valve, and the fuel injection end time of the fuel injection valve is set to approximately the intake valve closing time, and the fuel injection amount is increased. Accordingly, in the fuel injection device for an engine which advances the fuel injection start timing, there is provided a detection means for detecting that the fuel injection start timing of the fuel injection valve has reached a predetermined crank angle position and outputting a detection signal; , after the fuel injection start time reaches a predetermined crank angle position in response to the detection signal of the detection means, the fuel injection end time correction means corrects the fuel injection end time of the fuel injection valve to the delayed side after the fuel injection start time reaches a predetermined crank angle position. A fuel injection device for an engine, characterized in that: