JP2822633B2 - Fuel injection device for internal combustion engine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a fuel injection valve (hereinafter referred to as an "air blast valve") for injecting a measured fuel together with a pressurized gas such as air into a combustion chamber.
The present invention relates to a fuel injection device for an internal combustion engine provided with:

[Conventional technology]

Air blast valves that inject fuel together with pressurized air into a combustion chamber are often used in high-speed engines because they can inject a large amount of fuel into a combustion chamber in a short time while maintaining a good atomization state. Normally, pressurized air injected from an air blast valve is generated by, for example, an air pump or a compressor mechanically driven from the engine, and is always kept at a predetermined pressure (for example, 3 to 5 kg / cm ² G) during operation of the engine. It is supplied to the air blast valve.

However, in the above-described fuel injection device, when the engine is stopped for a long time and then restarted, the pressure of the pressurized air system of the air blast valve is reduced while the engine is stopped. After starting, it is necessary to drive the air pump by cranking or the like and wait for the pressure of the air system to rise to a predetermined value, which has a problem that it takes a long time to start the engine.

The fuel injection device disclosed in Japanese Unexamined Patent Publication No. Hei. 1-503555 solves the above problem.

The apparatus disclosed in the publication does not supply fuel to the air blast valve for a predetermined period after the start of the engine, and opens the air blast valve only when the cylinder is in the compression or expansion stroke and the in-cylinder pressure is high. Is introduced into the valve. That is, by using the in-cylinder pressure during the compression stroke, the internal pressure of the valve (and the pressurized air system) is accumulated, and the pressure of the air system is increased to a pressure at which fuel can be injected in a short time, thereby shortening the engine startup time. It is.

[Problems to be solved by the invention]

Introducing the in-cylinder pressure into the air blast valve at the time of starting the engine, as in the apparatus disclosed in Japanese Patent Publication No. 1-503555, is extremely effective in reducing the starting time.

However, in the above-described device, the gas remaining in the cylinder is introduced into the valve when the engine is started, so that there is the following problem.

That is, it is the exhaust gas after gas combustion remaining in the cylinder when the engine is stopped, and contains various corrosive components.
In particular, since the moisture and CO ₂ is the main component of the exhaust gas to form a strong carbonate of corrosive at low temperatures, aluminum and iron are the main constituent material of the air blast valve and enters the valve with the cylinder interior gas at the time of the in-cylinder pressure introduced May corrode. The amount of the corrosive liquid introduced is small, and the corrosive liquid comes into contact with each part for a short time until the start of fuel injection.However, since the inside of the air blast valve is precisely machined, starting the engine, If stopping is repeated, there is a problem that a failure occurs due to the progress of corrosion.

Further, carbon generated by combustion adheres to the wall surface of the combustion chamber, and the carbon is in a state where it is easily peeled off with cooling of the wall surface after the engine is stopped. When the carbon particles are separated from the wall surface at the time of starting the engine and are sucked into the air blast valve together with the residual exhaust gas in the cylinder, the carbon particles may be caught and cause a malfunction of the air blast valve. Introducing residual gas in the cylinder at the time of starting the engine into the air blast valve as described above may reduce the reliability of the air blast valve, which is problematic.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and has as its object to provide a fuel injection device capable of accumulating pressure when starting an engine without reducing the reliability of an air blast valve.

[Means for solving the problem]

The fuel injection device of the present invention does not introduce the in-cylinder pressure into the air blast valve immediately after the start of the engine, and performs the cylinder injection after the engine is cranked for a predetermined period and the scavenging for replacing the residual exhaust gas in the cylinder with fresh air is completed. It is characterized in that the introduction of the internal pressure is started.

That is, according to the present invention, a fuel injection valve for injecting fuel together with pressurized gas into the combustion chamber is provided, and after starting the engine,
The fuel injection valve is kept closed to scavenge residual gas in the cylinder for a predetermined first period, and after the first period has elapsed, the fuel supply to the fuel injection valve is stopped for a predetermined second period. A fuel injection device for an internal combustion engine, wherein the fuel injection valve is opened during a compression or expansion stroke of the cylinder, and the in-cylinder pressure after the completion of the scavenging is introduced into the fuel injection valve. You.

(Operation)

Exhaust gas, corrosive liquid, carbon particles, and the like remaining in the cylinder are quickly discharged to the exhaust system by cranking the engine and scavenging the cylinder, and the inside of the cylinder is replaced with fresh air. Therefore, by introducing the in-cylinder pressure into the air blast valve after the completion of scavenging, only clean air can be introduced into the valve.

〔Example〕

FIG. 1 is a view showing a cross section of an air blast valve 20 used in the present embodiment. A nozzle port 24 that opens into the cylinder combustion chamber 10 is provided in a housing 21 of the air blast valve 20, and a needle 23 that opens and closes the nozzle port extends inside the housing 21. The needle 23 is driven by the biasing spring 22 in the combustion chamber.
The valve body 25 at the tip of the needle 23 is urged away from the nozzle 10 to close the nozzle port 24. The end of the needle 23 opposite to the valve body 25 is in contact with the movable core 26, and a solenoid 28 for sucking the movable core 26 in the direction of the combustion chamber 10 is provided in the housing 21. When the solenoid 28 is excited, the movable core 26 moves toward the combustion chamber 10 and pushes the needle 23 against the urging force of the spring 22, so that the nozzle 24 is opened.

On the other hand, a nozzle chamber 29 is formed in the housing 21. In addition to the opening of the injection port of the fuel injection valve 33, a compressed air inflow passage 30 is provided in the nozzle chamber 29, and is connected to a compressed air source 31 such as a compressor or an air pump. Further, the nozzle chamber 29 communicates with the nozzle port 24 via the compressed air outflow passage 32.

When the solenoid 28 is demagnetized, the nozzle port 24
Nozzle chamber 29, compressed air passages 30, 32
The inside is filled with compressed air from a compressed air source 31. The fuel injection from the fuel injection valve 33 to the nozzle chamber 29 is performed in this state before the nozzle 24 of the air blast valve 8 is opened, and the fuel injected from the injection valve 33 collects near the valve body 25.
It adheres to the wall of the nozzle chamber 29 and the compressed air passages 30 and 32. Next, when the fuel injection timing to the combustion chamber 10 comes, the solenoid 28 is excited and the nozzle port 24 is opened. When the nozzle port 24 opens, the compressed air in the housing 21 blows out from the nozzle port 24,
The fuel near the valve body 25 is injected into the combustion chamber 10, and the airflow spouted from the nozzle port 24 from the compressed air source 31 through the compressed air passages 30, 32 carries away the fuel attached to the passage wall surface.
Therefore, when the nozzle port 24 is opened, the entire amount of the fuel injected from the fuel injection valve 33 is immediately injected together with the compressed air from the nozzle port 24, so that the injection can be completed in a short time and good atomization of the injected fuel can be obtained. be able to.

Reference numeral 40 denotes an electronic control unit (hereinafter, referred to as "ECU") composed of a digital computer, and a solenoid 28 is provided.
In addition, the fuel injection valve 33 is driven to perform in-cylinder fuel injection, and also controls in-cylinder pressure introduction according to the present invention. For this control, the ECU 40 receives a crankshaft rotation angle signal from a crank rotation angle sensor 41 provided on a crankshaft (not shown).
Further, an engine start signal is input from a start sensor 42 provided in a starter circuit of the engine.

FIG. 2 shows the operation timing of the air blast valve during normal operation. The figure shows the phase of the crankshaft, BDC
Indicates the bottom dead center of the piston, and TDC indicates the top dead center. The air blast valve normally opens the fuel injection valve 33 for a predetermined period of time very early before the bottom dead center (section F in FIG. 2).
Then, a predetermined amount of fuel is injected into the nozzle chamber 29. Fuel injection valve
The valve opening period of 33, that is, the fuel injection amount is set according to the engine operating conditions. Fuel injection into the cylinder starts after the piston enters the compression stroke past the bottom dead center (section I in FIG. 2). This in-cylinder fuel injection timing is preferably performed when the in-cylinder pressure is not increasing so much, and is preferably performed when the intake valve is not closed. In this embodiment, the timing at which the air blast valve completes the injection and the nozzle 24 closes is represented by the crank angle BTDC (before top dead center) θ, the period during which the valve is open is φ, and the fuel injection valve is opened. The period during which it is
At the time of fuel injection, θ and φ are set to θ _I and φ _I , respectively, and ψ is set to a value _{Ｉ I} determined by the engine operating conditions.

Next, FIG. 3 shows the operation timing in the case where the air blast valve accumulates pressure after the engine is started. In this case, fuel is not injected from the fuel injection valve 33, and the air blast valve is opened when the piston reaches the bottom dead center, is kept open during the compression stroke, and is located before or at the top dead center. The valve closes at a predetermined time after the dead center. That is, the above θ and φ are θ _A ,
is set to phi _A, [psi is set to zero.

FIG. 4 is a flowchart showing an in-cylinder pressure introduction control operation at the time of engine startup according to the present invention. This control operation is executed as the main routine of the ECU 40 described above.

The following description will be made according to the flowchart.
0 is a step for determining whether the engine is started or not,
It is determined whether or not the starter is operating, that is, whether or not the engine is cranking, based on the presence or absence of the output of the start sensor 42. If the start has been completed, the routine proceeds to step 150, where a normal fuel injection timing is set. If it is determined in step 100 that the engine is cranking, the process proceeds to step 110. Step 110 is a step for judging whether or not the engine has rotated by a predetermined number of revolutions after startup. The ECU 20 counts the crankshaft rotation signal of the crank rotation angle sensor 41 from the time when the start signal is input from the engine start sensor 42, and updates and stores the number of rotations N after the engine is started. In the present invention, as described above, the predetermined number N ₁
Only the in-cylinder pressure is not introduced into the air blast valve until the engine rotates. In step 110, N
_It is determined whether or not _one rotation has been made.If the rotation has not reached N1 rotation, the routine proceeds to step 130, where the air blast valve opening period and the fuel injection valve opening period ψ are set to zero and each valve is opened. Absent. It is known that scavenging before the start of in-cylinder pressure introduction is completed in an extremely short time.
N ₁ is one rotation. This can prevent foreign matters such as exhaust gas and carbon remaining in the cylinder from entering the air blast valve.

In the present embodiment, N ₁ rotation (N ₁ : 1) after the engine is started.
Have started cylinder pressure introduction into the rear air blast valve is N ₁ is not required to be one rotation, also, without detecting the in-cylinder pressure introduction start timing at a rotational speed of the engine for a predetermined time or a predetermined crank angle After the rotation, the in-cylinder pressure introduction may be started.

Engine at step 110 moves then to step 120 if it is determined by rotating N ₁ rotation or the scavenging barrel complete, whether the number of rotations after starting has reached N ₂ is determined. N ₂ by introducing the cylinder pressure in the air blast valve, and is set in advance for each type of engine as the number of rotations required to accumulator to a predetermined value. Because when the rotation number at step 120 was N ₂ or less not completed accumulator proceeds to step 140, to set the operation timing of the air blast valve to the state of FIG. 3 theta, phi, respectively [psi theta _A , φ _A and zero (FIG. 3) are set. Further, it is the engine rotational number N ₂ or more at step 120, if it is determined that the accumulator is completed the flow proceeds to step 150, normal fuel injection timing of the second diagram the operation timing of the air blast valve (theta = theta _I , φ = φ _I ). At this time, the valve opening period の of the fuel injection valve is also set to a value _ＩI corresponding to the engine operating conditions. In step 160, θ and φ set as described above are output to the drive circuit of the air blast valve, and the operation of the air blast valve is performed. After the engine started by the engine is opened at the time between compression stroke until a predetermined number of revolutions N ₂ after rotating N ₁ without opening the air blast valve until (N ₁ = 1 in this example) N ₁ Rotation The pressure can be accumulated by introducing the in-cylinder pressure.

〔The invention's effect〕

As described above, after starting the engine, the air blast valve is closed until the scavenging of the cylinder is completed so that the pressure accumulation is not performed, so that the residual exhaust gas and foreign matter in the cylinder can be prevented from entering the air blast valve. This can improve the operation reliability of the air blast valve. In addition, while the fuel supply to the air blast valve is stopped for a predetermined period after the completion of scavenging, the air blast valve is opened during the compression or expansion stroke of the cylinder to introduce the in-cylinder pressure after the completion of the scavenging, thereby increasing the pressure of the air blast valve. Since the pressure in the compressed air system can be quickly increased, the engine can be started in a short time without lowering the reliability of the air blast valve.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a sectional view of an air blast valve used in an embodiment of the present invention, FIG. 2 and FIG. 3 show operation timing of the air blast valve, and FIG. 4 is a flowchart showing an in-cylinder pressure introduction control operation. 20 ... air blast valve, 31 ... compressed air source, 33 ... fuel injection valve, 40 ... electronic control unit (ECU), 41 ... crank rotation angle sensor, 42 ... start sensor.

Continuation of the front page (72) Inventor Takahiro Kushibe 1 Toyota Town, Toyota City, Aichi Prefecture Inside Toyota Motor Corporation (56) References JP-A-62-129541 (JP, A) A) Hikaru Hira 1-166764 (JP, U) (58) Field surveyed (Int. Cl. ⁶ , DB name) F02M 67/02-67/04 F02M 67/12 F02M 69/08 F02D 41/00- 41/40 F02D 45/00

Claims (1)

(57) [Claims] A fuel injection valve for injecting fuel together with a pressurized gas into a combustion chamber, wherein after starting the engine, the fuel injection valve is held closed for a first predetermined period to scavenge residual gas in the cylinder. After the lapse of the first period, the fuel supply to the fuel injection valve is stopped for a predetermined second period, and the fuel injection valve is opened during the compression or expansion stroke of the cylinder. A fuel injection device for an internal combustion engine, wherein internal pressure is introduced into a fuel injection valve.