JPS60162049A - Fuel injection valve controller - Google Patents

Abstract

PURPOSE:To aim at reduction in an exhaust harmful component owing to good atomization in times of low speed and load as well as improvements in durability at high speed and load, by making valve opening pressure in a fuel injection valve controller variable in a manner conformable to an engine's operating state. CONSTITUTION:In case of low speed and low load, a spool valve 27 moves to some extent and a small diametral part 27d is interconnected to a back pressure chamber 6a whereby it comes to the same state that a nozzle spring grows strong. And, a needle valve 19 starts its injection at high pressure as compared with that by normal fuel injection valves. Likewise, in case of high speed and high load, the spool valve 27 comes into contact with an end part at the side of a hydraulic chamber 25 in its head part and thereby a through hole 27b is interconnected to the back pressure chamber 6a of a plunger hole 6. Then, the back pressure chamber 6a is interconnected to a leak oil passage 35 of a nozzle holder 2 from the through hole 17b by way of a throttle oil passage 27c and a spring chamber 26, while fuel oil inside the back pressure chamber 6a is discharged out by combined lift of the needle valve 19 and a plunger 13 via the throttle oil passage 27c.

Description

DETAILED DESCRIPTION OF THE INVENTION An object of the present invention is to provide a fuel injection control device that can vary the injection pressure between low speed and high speed. The injection pressure of the fuel injection device is determined by the opening pressure of the fuel injection valve. Therefore, depending on the engine characteristics, the valve opening pressure may be set so that sufficient injection pressure can be obtained at low speeds, and the valve opening pressure may be set so that sufficient injection pressure can be obtained at high speeds. There is. However, since injection pressure has the characteristic of increasing as the speed increases, if the valve opening pressure is set to obtain sufficient injection pressure at low speeds,
If the injection pressure becomes too high on the high speed side, the durability of the injector becomes a problem, and if the valve opening pressure is set to obtain sufficient injection pressure on the high speed side, the injection pressure becomes too low on the low speed side, causing fog. This has the disadvantage that it becomes difficult to suppress the emission of harmful exhaust gas components.

Therefore, as proposed in Japanese Patent Application Laid-Open No. 58-41258, the centrifuge of the nozzle blade is made variable so that the valve opening pressure can be controlled to be high at low speed loads and low at high speeds and high loads, and injection is performed at low speeds. There is one that increases the pressure and suppresses excessive pressure rise at high speeds.

However, such a configuration requires a large force to press down the nozzle spring that receives the injection pressure, and furthermore, the injection pressure cannot be accurately controlled.

In order to solve the above-mentioned problems, the present invention provides a fuel injection valve device that makes injection pressure variable by controlling the valve opening pressure of the fuel injection valve. The plunger is equipped with a plunger and is displaceable in conjunction with the riff 1 of the needle valve, and a control means for controlling the displacement of the plunger according to the operating state of the engine, and the control means guides injection pressure to the plunger and causes the displacement. control or release the plunger to atmospheric pressure to allow free displacement.

By configuring the valve opening pressure to be controllable, it is possible to set the injection pressure high at low speeds and low loads to maintain good fuel atomization and reduce harmful exhaust components, and at high speeds and high loads. To obtain a fuel injection valve control device that prevents an excessive increase in injection pressure and has improved durability.

An embodiment of the present invention will be described below with reference to the drawings.

In FIG. 1, two nozzle bodies 3 are integrally fastened to the tip of a nozzle holder 2 of a fuel injection valve control device 1 of the present invention with a retaining naso 1-5 via a stance piece 4. As shown in FIG. At the axial center of the nozzle holder 2, a plunger hole 6 is connected in the axial direction via a spring chamber 7 having a slightly larger diameter and a stepped portion 8. The spring chamber 7 opens at the end surface of the nozzle body 3 of the nozzle holter 2,
The tapered hole 9 is aligned with the tapered hole 9 of the stance piece 4, and the tapered hole 9 is aligned with the needle guide hole 11 of the nozzle body 3 through the small hole 10. Nozzle holder 2
The diameter of the head 2a on the side opposite to the nozzle body 3 is slightly increased.

A diametrical valve hole 2 is formed. The valve hole 12 crosses the plunger hole 6 on the side opposite to the nozzle bottom in a T-rod shape, and a plunger 13 is fitted into the plunger hole 6 so as to be freely displaceable. The shaft portion 14 at one end of the plunger 13 extends into the spring chamber 7, and a spring receiving portion L4a is formed at a predetermined position of the cough shaft portion 14.

A spring seat I7 is arranged on the stepped portion 8 between the plunger hole 6 and the spring chamber 7, and a spring seat I7 is arranged between the spring seat 17 and the spring receiving portion of the shaft portion 14], 4
A return spring 18 is compressed between the a and the a. On the other hand, needle valves 19 are displaceably fitted into the needle kite holes 11 of the nozzle body 3, and the head shafts +9a of all the valves 19 extend into the tapered holes 9 of the test stance piece 4. A nozzle spring 22 is compressed between a spring seat 20 supported by the head shaft portion 19a and the spring seat 17 of the return spring 18. Thus, during non-injection, the needle valve 19 is biased by the nozzle spring 22 and seats on the valve seat 3a of the nozzle tenon 3 to close the nozzle 3b, while the plunger 13 is biased by the return spring 18 and closes the tip of the shaft portion 14. It is in contact with the head 20a of the spring seat 20. Further, the valve hole 12 side of the plunger hole 6 has a plunger 1 between the end surface of the plunger 3 and the boundary surface with the valve hole 12.
3 back pressure chambers 6a are defined. The valve hole 12 is opened on the circumferential surface of the head 2a of the nozzle holder 2. The opening is formed by screwing the screw plug 24 through the backing 24a into the valve hole 12.
is oil-tightly closed. A spool valve 27 is located inside the valve hole I2.
The spool valve 27 defines a hydraulic chamber 25 and a spring chamber 26, respectively. The spool valve 27 is in the hydraulic chamber 2
The end face on the fifth side is formed into a spherical shape, and a radial through hole 27b and a small diameter portion 27d are formed at a predetermined intermediate position. The through hole 27b is communicated with the spring chamber 26 by an axially extending oil passage 27c that opens at the end surface of the spool valve 27 on the spring chamber 26 side, and the spool valve 27 is always kept under hydraulic pressure by the spring 30 contracted in the spring chamber 26. It is pressed toward the chamber 25 side. In this state, the radial through hole 27b of the spool valve 27 communicates with the back pressure chamber 6a. A hydraulic inlet 34 and a leak oil outlet 35 are formed in the head 2a of the nozzle holter 2 to be radially opposite to each other, the hydraulic inlet 34 communicates with the hydraulic chamber 25, the leak oil outlet 35 communicates with the spring chamber 26, and The spring chamber 26 is communicated with the spring chamber 7 at the axial center of the nozzle holder 2 through a leak oil passage 46 . On the other hand, the tip of the head 2a of the nozzle holter 2 has a fuel population 4.
7 is opened, and the fuel port 47 passes through fuel oil passages 49, 50, and 51 that are sequentially bored in the nozzle holder 2, the distance piece 4, and the nozzle body 3, and enters into the nozzle body 3 facing the tapered pressure receiving part 19b of the needle valve 19. It communicates with a pressure chamber 3c formed in this manner.

FIG. 3 shows a configuration in which the hydraulic pressure of the spool valve 27 is guided from the pump chamber of the fuel injection pump connected to the fuel injection valve control device 1, and the fuel tank 70 is connected to the sedimenter 71, feed pump 72. It is connected to the fuel injection pump 60 by a pipe line 8o which sequentially connects the filter 73. Further, the fuel delivery port 61 of the fuel injection pump 60 is connected to the fuel inlet 4 of the fuel injection valve control device I by an injection pipe 81.
7 is connected. Pump chamber 6 of fuel injection pump 60
2 is P port 74p', A port 74AT port, door
4 T is connected to the P port 74p of the electromagnetic switching valve 74 through a pipe 82, and the A boat 74^ of the electromagnetic switching valve 74 is connected to the hydraulic inlet 34 of the fuel injection valve control device 1 through a pipe 83. There is. The overflow outlet 63 of the fuel injection pump 60, the leak oil outlet 35 of the fuel injection valve control device 1, and the T-boat 74T of the electromagnetic switching valve 74 are connected to a pipe 84 communicating with each fuel tank 70.

In the above configuration, when the engine (not shown) is in a low speed and low load state, the electromagnetic switching valve 74 is energized to connect the pipes 82 and 83, and the hydraulic pressure in the pump chamber 62 is transferred from the hydraulic inlet 34 to the hydraulic pressure chamber. 25 and spring 3
0 and moves the spool valve 27 to the second position shown in FIG. In this second position, the small diameter portion 27d of the spool valve 27 communicates with the back pressure chamber 6a of the plunger 13, and the back pressure chamber 6a receives fuel pressure from the fuel port 47, making the nozzle splash stronger. become a state.

On the other hand, fuel pressurized by the fuel injection pump 60 is sent from the fuel outlet 6I of the fuel injection pump 60 to the fuel inlet 47 through the injection pipe 81. The fuel is in the fuel oil passages 49, 50
, 5] and reaches the pressure chamber 3c in the nozzle body 3. When the fuel oil pressure acting on the pressure receiving part 19b of the needle valve 19 reaches a predetermined value.

The needle valve 19 compresses the nozzle spring 22 to lift it, and at the same time the needle valve 19 compresses the return spring 18 to lift the plunger 13. Therefore, the plunger 13 removes the fuel in the back pressure chamber 6a of the plunger hole 6. The pressure makes it difficult to lift. Therefore, the needle valve 19 starts injection at a higher pressure than a normal fuel injection valve. In other words, the valve opening pressure increases. This increases the injection rate, improves atomization of the two fuels, improves ignitability, and suppresses the emission of harmful exhaust components. Next, when the engine is operating at high speed and high load, the electromagnetic switching valve 74 is deenergized to shut off the pipes 82 and 83 that communicate the pump chamber 62 and the hydraulic inlet 34 to the fuel injection pump 60. The spool valve 27 is pressed by the spring 30 so that its head abuts the end on the hydraulic chamber 25 side, and reaches the first position shown in FIG. It's communicating. Therefore, the back pressure chamber 6a is communicated with the leak oil wI35 of the nozzle holder 2 through the radial passage hole 27b- of the spool valve 27, the throttle oil passage 27c, and the spring chamber 2G, and the fuel oil in the back pressure chamber 6a is When the needle valve 19° plunger 13 is lifted by the injection, the oil is discharged through the throttle oil passage 27c. As described above, an excessive increase in valve opening pressure can be prevented, and a fuel injection valve control device with good durability and capable of removing harmful exhaust gas components can be obtained. When the needle valve 19 is operated, the fuel oil discharged from the back pressure chamber 6a as the plunger 13 lifts is subjected to resistance by the throttle/restriction oil passage 27c. The lift speed becomes slower. When the needle valve 19 returns, the needle valve 19 is immediately separated from the plunger 13 by the spring force of the nozzle spring 22 and is seated. The fuel injection rate due to the operation of the needle valve 19 is shown by line 1 in FIG.

Compared to line 1', which shows normal high fuel injection characteristics, a characteristic in which the injection rate increases more slowly is obtained, and the amount of fuel injected during the ignition delay 11 period can be made smaller than before, reducing combustion noise. , effective in achieving controlled combustion. Note that the switching of the electromagnetic switching valve 74 can be automatically operated based on the engine speed or the displacement signal of the accelerator pedal.9 FIG. 5 shows another embodiment of the present invention, which is different from the embodiment described above. Identical components are given the same reference numerals.

In this embodiment, the throttle oil passage 27C in the first embodiment is replaced with a tapered throttle oil passage 27c', and this configuration facilitates machining of the throttle oil passage.

As explained above, according to the present invention, the valve opening pressure of the fuel injection valve control device can be made variable according to the operating condition of the engine, so that when the engine is operated at low speed and under low load, the fuel injection pressure increases and fuel is exposed. gets better. Therefore, the ignitability is improved, and it is possible to reduce harmful exhaust gas components. During high-speed, high-load operation of the engine, it is possible to prevent an excessive increase in fuel injection pressure, and also to moderate the increase in injection rate, reducing the amount of fuel injected during the ignition delay period and eliminating sudden combustion.
Complete combustion is achieved, allowing the engine to operate quietly and without smoke. Moreover, by communicating the back pressure chamber with the leakage oil passage through the throttle, it is possible to control the injection rate over the entire area, and combustion can be freely controlled.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal cross-sectional view showing one embodiment of the fuel injection valve control device according to the present invention, FIG. 2 is a longitudinal cross-sectional view of the main part of the spool valve used in FIG. 1 with different operating positions, and FIG. FIG. 4 is a block diagram showing an example of a fuel injection device to which the invention is applied, FIG. 4 is a graph showing the injection rate characteristics of the device of the invention, and FIG. 5 is a longitudinal sectional view of a main part of another embodiment of the invention. I Fuel injection valve control device, 3... Nozzle body, 6
Plunger hole, 6a/back pressure chamber, 13 Plunger, 19
4 valves, 27 spool valves, 27c. 270' - Crest oil passage, 35 - Leak oil passage, 47...Fuel inlet applicant Diesel @P! Seven Co., Ltd. Agent Patent Attorney Toshihiko Seibu Patent Attorney Kanji Nagato Figure 1

Claims (1)

[Scope of Claims] 1. A fuel injection valve control device that varies injection pressure by controlling the opening pressure of a fuel injection valve, comprising: a plunger hole formed in a main body; and a needle fitted into the plunger hole. It has a plunger that can be displaced in conjunction with the lift of the valve, and a control means that controls the displacement of the plunger according to the engine motion state, and the control means guides injection pressure to the plunger and controls the displacement, or controls the displacement of the plunger. 1. A fuel injection valve control device, characterized in that the fuel injection valve is opened to atmospheric pressure to allow free displacement, thereby controlling the valve opening pressure and making the injection pressure variable. 2. A back pressure chamber filled with fuel oil is formed in the plunger hole to resist displacement of the plunger due to lift of the needle valve, and the control means is configured to move between a first position and a second position depending on the operating state of the engine. It is characterized by comprising a spool valve that is switched to a spool valve, and in a first position communicates the back pressure chamber with a leak oil passage via a throttle oil passage, and in a second position communicates the back pressure chamber with a fuel inlet. Claim 1
The fuel injection valve control device described in Section 1.