JP2578012Y2 - Fuel injection device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a fuel injection device, and more particularly, to a unit injector used for a diesel engine.

(Prior Art) As is well known, in a diesel engine, which is one of the internal combustion engines, fuel from a fuel supply system is injected into high-pressure air in a combustion chamber by using an injection pump and an injection nozzle. Is burned, and an output corresponding to the heat energy generated thereby is obtained.

Meanwhile, as a structure used in the above-described fuel supply system, a unit injector in which a fuel injection pump and an injection nozzle are integrated is known.

This unit injector has the advantage that the line resistance can be reduced by reducing the length of the high-pressure oil supply passage, the transmission delay of the pressure wave from the pump to the nozzle is reduced, and the injection timing can be easily adjusted.

That is, the above-described unit injector is attached to the upper cylinder head 2 in the combustion chamber 1 of the diesel engine as shown in FIG.

The unit injector 3 has a fuel injection nozzle 4 at the lower part and a fuel injection pump 5 at the upper part, and sends high pressure between the plunger chamber 6 in which the upper plunger 6A slides and the lower nozzle chamber 7. They are connected by an oil passage 8.

The high-pressure oil supply passage 8 branches off in the middle, and the branch passage 9 is connected to the low-pressure passage 11 via an electromagnetic valve 10 to form a spill passage.

The solenoid valve 10 includes a needle valve 12 and a valve driving unit 13 that opens and closes the needle valve 12. The valve driving unit 13
Are driven by the valve control device 14.

In the unit injector shown in FIG. 4, when the solenoid valve 10 is closed, fuel is injected into the combustion chamber 1, and when opened, the oil in the high-pressure oil passage 8 is returned and spilled.

The fuel injection pressure (P
f) is a high-pressure oil supply line 8 which is always in communication with the high-pressure oil supply line 8.
Is V, the compression volume in the high-pressure oil passage, which is the sliding volume of the plunger 6A, is ΔV, and the bulk modulus is K, it is statically obtained by the following equation.

Pf = K · ΔV / V (1) (Problem to be Solved by the Invention) By the way, in the above-described fuel injection device, the injection timing is adjusted by shortening the pipe length. It is possible to set the optimal injection timing at, but since the fuel injected at this time is concentrated at one time,
It may cause ignition delay and cause noise.

That is, when the metered fuel is injected into the compressed air, it is difficult for the flame to be propagated smoothly, and a rapid combustion occurs at a certain time, and the explosion sound and the vibration sound are generated correspondingly. Become.

Further Separately, the concentrates of the fuel injection at one time, so that generation of the NO _X is much from the temperature of the cylinder after combustion is significantly increased risk also.

Further, for example, when the load is low, the fuel injection amount is small, and the in-cylinder (in-cylinder) temperature after combustion is low.
Once harmful substances such as soot, HC, and CO are generated, they may be discharged as they are without being oxidized. Further, at the time of high load, cylinder temperature after combustion by the fuel injection amount becomes relatively large is liable to increase, the occurrence of similarly NO _X in the case where fuel injection is concentrated is remarkably at one time as described above Cheap. In addition, at high load, the fuel injection pressure increases due to the longer valve opening time, and the fuel spray injected into the cylinder burns only at the outer periphery of the combustion space along the swirl in the combustion space. And the activation of combustion in the combustion space is hindered.

Therefore, an object of the present invention is to prevent the generation of vibration and noise during combustion and the generation of harmful components in exhaust gas in consideration of the above-mentioned problems in the conventional fuel injection device, and to determine the engine load. Regardless, it is an object of the present invention to provide a fuel injection device capable of obtaining a good combustion state.

(Means for Solving the Problems) In order to achieve this object, the invention according to claim 1 includes a plunger chamber supplied with fuel from a fuel supply system supported by an engine body during an internal combustion period, and the internal combustion engine. A plunger that receives the driving force from the output shaft to pressurize the fuel in the plunger chamber, and a high-pressure fuel from the plunger chamber is supplied through a high-pressure oil supply passage, and the high-pressure fuel is supplied when the needle valve is opened. Fuel is injected by opening and closing the low-pressure oil passage between the injection nozzle for injecting the fuel into the internal combustion engine and the low-pressure oil passage for spilling the return oil from the plunger chamber. A fuel injection device in which a fuel injection solenoid valve for adjusting a timing and an injection amount is disposed in an integrated structure, wherein the fuel injection solenoid valve receives engine rotation information and engine load information. The control unit is connected to the control unit. The control unit sets the fuel injection timing and the injection amount in accordance with the information, and at least performs the fuel injection so that a small amount of fuel is injected after the main injection. It is characterized by controlling the operation of the electromagnetic valve for use.

According to a second aspect of the present invention, in the fuel injection device according to the first aspect, the control unit operates the fuel injection solenoid valve such that a small amount of fuel is injected before the main injection and after the main injection. Is controlled.

(Operation) According to the invention, a small amount of fuel is injected at least after the main injection.

According to the present invention, a small amount of fuel is injected before the main injection and after the main injection.

(Embodiment) Hereinafter, the embodiment of the present invention will be described in detail with reference to FIGS. 1 to 3.

FIG. 1 is a sectional view corresponding to FIG. 4 showing the overall configuration of a fuel injection device according to an embodiment of the present invention.

In FIG. 1, a fuel injection device injects fuel into a combustion chamber 20 of a diesel engine, and has a base 22 incorporated and fixed in a cylinder head 21 of the diesel engine.

A fuel injection pump 23 is provided above the base 22, and a fuel injection nozzle 24 is provided below the base 22, and both are connected by a high-pressure oil supply passage 25.

The fuel injection pump 23 includes a plunger chamber 26 formed in the base 22 and a plunger 27 slidable in the same chamber, and a plunger drive system 29 for pressing the plunger 27 against the elastic force of the return spring 28. It consists of

The plunger chamber 26 described above has an inflow port 30 on its inner wall,
Further, an outlet 31 is formed on the bottom wall, the inlet 30 is connected to a feed pump (not shown) via a low-pressure fuel supply path 32, and the outlet 31 is connected to a high-pressure oil supply path 25. is there.

Also, the plunger 27 is at the pressurization start position where the inlet 30 is closed.
The reciprocating movement is performed within a range in which the stroke S is moved from B1 to reach the pressurization end position B2, and the pumping of the fuel is continued during the forward movement.

The above-described plunger drive system 29 includes a rocker arm pivotally connected to a drive cam 33, a push rod 34, and a shaft 35.
The driving cam 33 is pivotally attached to a base (not shown) of the diesel engine, receives the output rotation of the engine, and rotates at half its rotation speed. The drive cam 33 is attached to the plunger 27 via a push rod 35 reciprocally driven by the drive cam 33.
The driving force is transmitted. In the present embodiment, the lift operation of the driving cam 33 is configured to overlap the vicinity of the compression top dead center of the engine before and after the timing.

Therefore, the fuel injection nozzle 24 includes an injection port 37 for injecting fuel into the combustion chamber 20, a nozzle chamber 38 inside the injection port 37,
By providing a needle valve 39 for closing the valve 37 and opening and closing the nozzle 37, the needle valve 39 is
The lift operation is performed by receiving the pressure of the nozzle chamber 38 by the annular pressure receiving portion 40.

On the other hand, a branch passage 41 is formed to extend from the bottom of the plunger chamber 26, and the tip of the branch passage 41 can communicate with the low-pressure oil passage 43 via an electromagnetic spill valve 42 as a fuel injection electromagnetic valve. The low-pressure oil passage 43 communicates with a drain pipe of a fuel tank (not shown), and serves as a return passage for oil in the plunger chamber 26.

The above-described electromagnetic spill valve 42 includes a valve driving unit 47 and a needle valve 48.
The tip of the needle valve 48 is separated from the valve seat 49 at the time of non-excitation, that is, when it is off, and the tip of the needle valve 48 contacts the valve seat 49 at the time of excitation, that is, when it is on, so that the branch passage 41 is provided. Is closed to shut off the return path, and at this time, the fuel injection nozzle 24 performs the injection operation via the pressure in the plunger chamber 26.

The electromagnetic spill valve 42 is connected to a controller 50 as control means for the excitation timing and the excitation period.

That is, the main part of the controller 50 is constituted by a microcomputer, which includes an engine rotation sensor 51 for outputting engine rotation information, an accelerator opening degree sensor 52 for outputting engine load information, and other elements, such as the engine warming-up. At least a sensor (not shown) that outputs device information and the like is connected.

In the process of the engine controller, the controller 50 determines the fuel injection timing (the deviation angle α from the reference position K in FIG. 2) from the engine speed, the so-called engine speed, load information, so-called accelerator opening, warm-up information, and the like. ) And the injection amount (a value proportional to the time width indicated by the symbol T in FIG. 2), and based on the latest fuel injection timing and injection amount calculated for each injection process. Electromagnetic spill valve 42 via injector drive circuit 501
Drive.

Then, in the controller 50, in addition to the setting of the fuel injection timing and the fuel injection amount based on the above-described information, based on the above-described information, at least a control of performing a small amount of fuel injection after the main injection is performed. It has become.

FIG. 3 shows an example in which a case where a small amount of fuel is injected after the main injection is combined with a case where a small amount of fuel is injected before the main injection.

In FIG. 3, a small amount of fuel is injected after the main injection, so that at low load when the temperature in the cylinder is low, the temperature in the cylinder is increased by the flame of the small amount of fuel injection.

At a high load where the fuel injection amount is relatively large and the in-cylinder temperature after combustion tends to increase, a small amount of fuel is injected after the main injection to cool the flame and to reduce the temperature of the cylinder. The combustion flame is agitated so that the combustion flame tends to concentrate only in the vicinity of the outer periphery of the cylinder along the swirl, thereby activating the combustion in the entire region of the cylinder.

Furthermore, by performing a small amount of fuel injection before and after the main injection, it enables continuous flame propagation,
At the time of the low load, the fuel injection amount of the main injection is reduced to set the injection energy so that the combustion flame is not concentrated more than necessary toward the inner and outer peripheral portions of the cylinder. The air in the central part of the combustion chamber space in the surplus state can be utilized. Further, at the time of the high load, the fuel injection pressure is increased to prevent the fuel spray from easily reaching only the outer peripheral portion of the in-cylinder combustion chamber, and the excess air in the central portion of the combustion space is effectively used. To make good combustion in the whole area of the cylinder.

In this way, by performing a small amount of fuel injection after the main injection, the temperature rise in the cylinder is suppressed to reduce the generation of NO _X , and at the time of a low load, the fuel is re-burned, Once generated, soot, HC, CO, and the like are reburned to promote oxidation, and can be purified and discharged into H ₂ O and CO ₂ . Further, at the time of high load, the combustion flame can be prevented from being biased.

Further, by performing a small amount of fuel injection before and after the main injection, it is possible to prevent deviation of the fuel spray and prevent occurrence of a situation in which complete combustion is inhibited in the entire region in the cylinder. It has become.

Since the present embodiment is configured as described above, when the controller 50 sets the fuel injection timing and the fuel injection amount based on the engine rotation information and the engine load information, and further based on the warm-up information and the like, at least the main After the injection, the injection timing and injection amount of a small amount of fuel injection are set, and based on this, a drive signal is output to the injector drive circuit 501 to control the injection operation of the fuel injection nozzle 24.

(Effects of the Invention) As described above, according to the invention of claim 1, at least a small amount of fuel is injected after the main injection, so that at low load, the fuel injection charge is small and the in-cylinder temperature after combustion is low. However, once soot or HC or CO is generated, it will be discharged without being oxidized.However, it is necessary to raise the in-cylinder temperature by using a small amount of fuel supplied after the main injection. As a result, soot, HC, CO, and the like are reburned, oxidation is promoted, and it becomes possible to purify and discharge H ₂ O and CO ₂ .

At high load, the fuel injection amount becomes relatively large, so that the in-cylinder temperature after combustion tends to rise.However, the flame can be cooled by a small amount of fuel injection after the main injection. It becomes possible to reduce the generation of NO _X by suppressing the remarkable temperature rise of the internal temperature. In addition, the small-volume fuel injection performed after the main injection is a small-volume injection with respect to the combustion flame of the main injection that is burning while swirling along the swirl (in-cylinder swirling flow) in the combustion chamber. Therefore, since the injection pressure does not reach such a level as to cause swirl, it can be injected as a jet in a radial direction in the cylinder, which is a direction orthogonal to the swirl, and combustion is caused by generating turbulence in the combustion flame by the main injection. Stir the flame,
It becomes possible to activate combustion and obtain a favorable combustion state in which generation of harmful components does not occur.

According to the invention of claim 2, by performing a small amount of fuel injection before and after the main injection, the fuel injection can be prevented from being concentrated at one time, so that continuous and smooth flame propagation occurs, It is possible to reduce the explosion sound and the increase in vibration caused by the occurrence of excessive combustion.
Moreover, since the rapid combustion does not occur, it is possible to suppress the remarkable increase in temperature of the cylinder temperature after combustion, it is possible to reduce generation of NO _X.

Furthermore, when the load is low, the fuel injection amount of the main injection is reduced by performing a small amount of fuel injection before and after the main injection, and the injection energy of the main injection can be reduced. Since the fuel is not distributed, and at the time of a low load in which air surpluses the fuel amount in the cylinder, mainly before the main injection in the central part of the combustion space,
Continuous combustion by the main injection and each injection after the main injection can be performed. Thereby, the fuel spray does not unnecessarily disperse toward the outer peripheral portion of the combustion chamber, so that it is possible to prevent the complete combustion in the entire cylinder from being hindered.

In addition, at high load, the injection pressure becomes considerably high due to the long valve opening time of the solenoid valve so that the main injection fuel amount becomes larger than the injection amount before and after the main injection. It is easy to reach the outer periphery of, and it will burn only mainly around the outer periphery along the swirl,
Since the pressure of the fuel injected in a small amount after the main injection is not so high, the fuel can be combusted by effectively utilizing the excess air in the center of the combustion space. Can be promoted.

[Brief description of the drawings]

FIG. 1 is a sectional view showing the overall configuration of a fuel injection device according to an embodiment of the present invention, FIG. 2 is a diagram for explaining one operation of a control unit in the fuel injection device shown in FIG. 1, and FIG. FIG. 4 is a diagram for explaining the operation obtained by the fuel injection device shown in FIG. 1, and FIG. 4 is a cross-sectional view corresponding to FIG. 1 showing a main structure of a conventional fuel injection device. 20: combustion chamber, 24: fuel injection nozzle, 25: high-pressure oil passage, 26
... plunger room, 27 ... plunger, 32 ... fuel supply path, 39
… Needle valve, 42… solenoid valve for fuel injection, 43… low pressure oil passage,
50 ... Controller.

 ──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Yoharu Yamada 10 Okura-cho, Nakahara-ku, Kawasaki-shi, Kanagawa Prefecture Mitsubishi Motors Engineering Co., Ltd. Kawasaki Office (56) References JP-A-60-27775 Opened Sho 57-12972 (JP, U) Opened Sho 60-41570 (JP, U)

Claims (2)

(57) [Scope of request for utility model registration] 1. A plunger chamber to which fuel is supplied from a fuel supply system supported by an engine body of an internal combustion engine, and pressurizing the fuel in the plunger chamber by receiving a driving force from an output shaft of the internal combustion engine. A plunger, an injection nozzle for supplying high-pressure fuel from the plunger chamber through a high-pressure oil supply passage, and injecting the high-pressure fuel into the fuel chamber of the internal combustion engine when the needle valve is opened; A fuel injection solenoid valve that adjusts the fuel injection timing and injection amount by opening and closing the low pressure oil passage located between the low pressure oil passage that spills return oil from the plunger chamber is integrated into an integrated structure. In the fuel injection device arranged, a control unit for inputting engine rotation information and engine load information is connected to the fuel injection solenoid valve, and the control unit includes:
The fuel injection timing and injection amount are set in accordance with each of the information, and at least the operation of the fuel injection solenoid valve is controlled so that a small amount of fuel is injected after the main injection. Injection device. 2. The fuel injection device according to claim 1, wherein the control unit controls the operation of the fuel injection solenoid valve such that a small amount of fuel is injected before the main injection and after the main injection. A fuel injection device characterized by the above-mentioned.