JPS6238871A - Fuel injection nozzle device for engine - Google Patents

Abstract

PURPOSE:To facilitate maintenance inspection and obtain the ideal starting-up characteristic of injection rate by allowing at least one among a plurality of injection ports to communicate to a suck hole and another to communicate to a damper chamber and allowing the damper chamber to communicate to the seat part in the upper part of the suck hole. CONSTITUTION:A needle valve 20 is lifted by the pressure of the fuel which flows into a nozzle body 3, and when the part between the seat surface 8a of the nozzle body 3 and the tapered surface 20a of the needle valve 20 is opened, a portion of the above-described fuel flows into a damper chamber 13 through a bypass passage 14. An other portion flows into a suck hole 6, passing through the above-described seat surface 8a. The fuel which flows into the damper chamber 13 is jetted into a combustion chamber from an injection hole 7b, and the fuel which flows into the suck hole 6 is jetted into the combustion chamber from other injection holes 7a. Therefore, in the ignition delay period, the gentle starting-up characteristic of the injection rate can be obtained, and the fuel injection rate can be softened by the damper chamber.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field 1] The present invention relates to a hole nozzle type fuel injection nozzle device employed in direct injection engines and the like.

[Prior art and problems to be solved by the invention] As is well known, for example, in a direct injection diesel engine, the fuel droplets immediately after injection take away the latent heat for evaporation, so the compression heat temperature in the combustion chamber decreases. Temporarily drops, causing a delay in ignition. Thereafter, a foreflame reaction starts and combustion begins, but at this point the fuel droplets that have been injected up to that point burn at an extremely linear speed. From this, if we reduce the fuel nozzle [L'-() during the ignition delay period, and if we take the rise characteristic of the injection rate loosely, the sudden rise in combustion pressure in the combustion chamber will be prevented, and static combustion will be achieved. It is known that it is possible to obtain

For example, in Japanese Unexamined Patent Publication No. 55-23375, a 7 cumulator is connected to a spring chamber in which a spring for biasing a needle valve is built-in, and an orifice is interposed between the akicomulator and the spring chamber to supply fuel. When the needle valve is moved upward by the pressure W, the pressure in the spring chamber gradually increases, and a portion of the air or leaked fuel in the spring chamber passes through the orifice and flows into the akicomulator. As a result, the lift distance of the needle valve becomes looser,
A technique has been disclosed in which the amount of fuel injected into the combustion chamber is suppressed to obtain a gentle rise-L rise characteristic of the injection rate. However, according to this prior art, fuel is injected from all nozzle holes at the same timing even during the ignition delay period, so there is a limit to how ideal the rise characteristics of the injection rate can be.

In addition, since the accumulator and orifice are formed inside the nozzle body, the structure is complicated and maintenance and inspection is extremely complicated.Moreover, the accumulator is equipped with movable members such as springs, and this movable member is damaged. In case,
Another disadvantage is that the entire fuel injection nozzle must be replaced.

[Objective of the Invention] The present invention has been made in view of the above circumstances, and provides a simple structure, easy maintenance and inspection, and ideal rise characteristics of the injection rate without adding any movable members. The object of the present invention is to provide a fuel injection nozzle device for an engine.

[Means for Solving the Problems] In the engine fuel injection nozzle device according to the present invention, a plurality of nozzle holes are formed at the tip of the nozzle body, and the number of nozzle holes (
One of the nozzle holes is in communication with the suck hole formed in the nozzle body, and at least one other nozzle hole is in communication with a damper chamber formed in the nozzle body. The seat formed at the upper part of the backpack hole is connected to the seat section, and the tapered surface of the needle valve, which is inserted into the nozzle body so that it can move forward and backward, can be moved closely and away from the seat section. be.

That is, when the needle valve is lifted by the pressure of the fuel flowing into the nozzle body and the space between the seat part of the nozzle body and the tapered surface of the needle valve is opened, a part of the fuel flows into this seat part. It flows into the damper chamber via the exposed bypass passage. The other part flows into the suck hole after passing through the above-mentioned sea. The fuel that has flowed into the damper chamber is first injected from the nozzle hole into the combustion chamber, and then the fuel that has flowed into the suck hole is ejected from other nozzle holes into the combustion chamber.

[Embodiments of the invention] Hereinafter, the present invention will be described in detail with reference to the drawings.

The drawings relate to one embodiment of the present invention, and FIG. 1 is an enlarged view of part A in FIG. FIG. 3 is a characteristic diagram showing the crank angle on the shaft.

In these figures, numeral 1 is a fuel injection nozzle;
2 is a retaining nut. This retaining nut 2 includes a nozzle body 3, a distance piece 4. The nozzle bodies 5 are each screwed on from below.

The tip of the nozzle body 3 is attached to the retaining nut 2.
A suck hole 6 is formed inside the nozzle body 3, and this suck hole 6 protrudes from the tip surface 3a of the nozzle body 3.
It communicates with a nozzle hole 7a bored in the hole 7a. Further, a second seat surface 8b is formed at the upper end of the suck hole 6, and a barrel portion 9 is communicated with the second seat surface 8b. has been formed. Furthermore, an oil reservoir chamber 10 is formed at the upper end of this first seat surface 8a.

On the other hand, a damper chamber 13 is formed with a notch in the side of the tip surface 3a of the nozzle body 3, and a lid body 1 is formed in this damper chamber 13.
2 is tightly fixed to the lid body 12, and another nozzle hole 7b communicating with the damper chamber 13 is bored in this lid body 12. Further, a bypass passage 14 is communicated with this damper chamber 13, and the other end of this bypass passage 14 is exposed to the first seat surface 8a indicated in 4-.

Further, a high-pressure fuel supply passage 15 is communicated with the oil reservoir chamber 10, and this high-pressure fuel supply passage 15 passes through the distance piece 4 and the nozzle body 5, and the fuel supply passage attached to the nozzle body 5 is connected to the high-pressure fuel supply passage 15. It communicates with the port 16. Furthermore, a fuel injection pump 18 is connected to this fuel supply port 16 via a high pressure pipe 17.

In addition, a guide hole 19 is provided in the second part of the oil reservoir chamber 10.
A needle valve 20 is inserted into this guide hole 19 so as to be freely advanced and retracted.A tapered valve lift surface 8G is formed in the portion of the needle valve 20 exposed to the oil reservoir chamber 10. , furthermore, in the distal direction thereof, a first tapered surface 20a that is in close contact with and can be separated from the first seat surface 8a, a second tapered surface 20b that is in close contact with and able to be separated from the second seat surface 8b, and the barrel portion. 9 is integrally formed with a step portion 20C which can be freely fitted and removed and has a predetermined height h.

Further, a journal 20d protruding from the base end of the needle valve 200 is inserted through the distance piece 4, and its end surface is connected to the prefix 1? It is fitted into four parts (not shown) formed on the lower end surface of the pin 21. Further, a gap dt is provided between the distance piece 4 and the base end surface 2Oe of the needle valve 20, and this gap /! Ut is set to be somewhat larger than the height h of the stepped portion 20C.

Furthermore, the pressure pin 21 is connected to the nozzle body 5.
The spring chamber 22 formed in the
A pressure spring 23 is installed inside the pressure spring 2, and this pressure spring 23 is connected to the pressure pin 2.
1, the needle valve 20 is pressed and biased in the valve closing direction.

Further, a predetermined number of washers 24 are interposed between the upper surface of the spring chamber 22 and the pressure spring 23, and by increasing or decreasing the number of washers 24, the pressure spring 23 is more resilient to the needle valve 20. The pressure can be adjusted.

Further, a fuel return passage 25 is communicated with the upper surface of the spring chamber 22, and this fuel return passage 25 is connected to a return fuel F31+31 outlet 26 mounted on the side of the nozzle body 5.
It is communicated with. Further, this return fuel outlet 26 is communicated with a fuel tank 28 via a fuel return pipe 27.

In addition, this fuel tank 28 and fuel injection bomb 18
are communicated with each other via a fuel pipe 30.

Next, the operation of the fuel injection nozzle device having the above configuration will be explained.

When the engine starts and the fuel injection pump 18 starts operating,
The fuel stored in the fuel tank 28 is transferred to the high pressure pipe 17. Fuel supply port 16. The oil is fed under pressure through the high-pressure fuel supply passage 15 to the oil reservoir chamber 10 formed in the nozzle body 3, and its pressure pushes the valve lift surface 8G of the needle valve 20 upward against the biasing force of the pressure spring 23.

As a result, the needle valve 20 rises, opening between the first seat surface 8a and the first tapered surface 20a, and the fuel flows into this opening. The fuel flowing into this opening passes through the bypass passage 14 to the tip surface 3 of the nozzle body 3.
It flows into the damper chamber 13 formed in a.

The pressure of the fuel that has flowed into the damper chamber 13 is attenuated until it is filled with the damper chamber 13.
The injection rate from

Furthermore, since the barrel portion 9 is closed until the lift width of the needle valve 20 reaches the height h of the stepped portion 20G formed at the lower end of the first tapered surface 20a, fuel flows into the hole 6. Not done. Therefore, the ignition delay period,
That is, until the lift amount of the needle valve 20 reaches the height h, fuel is injected only from the injection hole 7b, and a sudden pressure increase in the combustion chamber is prevented.

Then, the lift amount of the needle valve 20 is
When the height of c is equal to or higher than h, an opening is formed between the stepped portion 20G of the needle valve 200 and the barrel portion 9, and fuel flows into the barrel portion 9 through this opening. The fuel flowing into the barrel portion 9 flows through the opening between the second seat surface 8b formed on the nozzle body 3 and the second tapered surface 20b formed on the needle valve 20. The fuel flows into the suck hole 6, and is vigorously ejected into the combustion chamber from the nozzle hole 7a communicating with the suck hole 6.

Of course, at this time, the pressure of the fuel flowing into the damper chamber 13 is also rising, so the fuel is also vigorously jetted out from the nozzle hole 7b.

To explain this using the characteristic diagram in Figure 3, a small amount of fuel is injected from the nozzle hole 7b during the ignition delay period (between -θ1 and -02), so the nozzle 4 rate (a) during this period is small. ,
Therefore, a gradual rise characteristic is obtained, and the top dead center (T, D,
In the vicinity of C), the fuel is vigorously injected from both the nozzle holes 7a and 7b, so the injection rate is rapidly increased and the fuel is combusted smoothly. As a result, combustion becomes quieter overall.

Note that a part of the fuel that has flowed into the oil reservoir chamber 10 leaks into the spring chamber 22 from between the needle valve 20 and the guide hole 19 that supports the needle valve 20. is the fuel return passage 25. Return fuel outlet 26. The fuel is returned to the fuel tank 28 via the fuel return pipe 27.

Furthermore, the time difference between the fuel discharged from the nozzle holes 7b and 7a is determined by the time it takes for the stepped portion 20c formed in the needle valve 20 to escape from the barrel portion 9, so the height of this stepped portion 20G It can be set by increasing or decreasing h. Alternatively, it can be set by changing the biasing pressure of the spring 23 that resists the fuel discharge pressure.

By the way, Japanese Patent Application Laid-Open No. 55-23375 shown in the conventional example above
The spring chamber of the fuel injection nozzle device disclosed in the publication does not communicate with the fuel return passage as in the present invention, so if air gets mixed into the spring chamber, it cannot be removed. As a result, the air mixed into the spring chamber as the needle valve moves up and down is rapidly compressed and expanded, causing τ noise. On the other hand, since the spring chamber 22 of the fuel injection nozzle device according to the present invention is communicated with the fuel return passage 25, the air mixed in the spring chamber 22 can be removed from the fuel return passage 25. Therefore, the inconveniences mentioned above do not occur.

It should be noted that the fuel injection nozzle device according to the present invention is not limited to the above-mentioned embodiments. A plurality of injection holes may be communicated with the suck hole 6 and the damper chamber 13, respectively.

Furthermore, since the damper chamber 13 is directly communicated with the first seat surface 8a of the nozzle body 3 via the bypass passage 14, the nozzle hole 7b communicated with the damper chamber 13 is communicated with the suck hole 6. Since the nozzle hole 7a is located closer to the oil reservoir chamber 10 than the nozzle hole 7a, fuel is ejected from the nozzle hole 7b side somewhat earlier. Therefore, even if the step portion 20G is not formed in the needle valve 20, the oil reservoir chamber 10 and the nozzle hole 7 can be
By setting a length difference in the distance between a and 71), a time difference can be added to the injection timing. Note that the fuel pump pumps fuel intermittently in synchronization with the ignition timing of the engine. Therefore, when the pressure decreases, the needle valve moves down and fuel injection is stopped.

[Effect of the Invention 1 As explained above, according to the present invention, a plurality of nozzle holes are formed at the tip of the nozzle body, and at least one of the nozzle holes is communicated with the rick hole formed in the nozzle body. , and at least one other nozzle hole communicates with a damper chamber formed in the nozzle body, and this damper chamber communicates with a sheet surface formed in the L portion of the suck hole, and roughly this On the seat surface, the taper of the needle valve, which is inserted into the nozzle body so that it can move forward and backward, can be moved closely and away from each other, so that the fuel first flows into the damper chamber and then into the 1J-hole. . As a result, during the ignition delay period, fuel can be injected only from the nozzle holes communicating with the damper chamber, and a gradual rise characteristic of the injection rate can be obtained. is relaxed, the rise characteristics of the injection rate become ideal.

Furthermore, since the structure is simple, maintenance and inspection are easy.

Furthermore, since the fuel injection nozzle device according to the present invention is designed to set a time difference between the fuel discharged from each nozzle hole without adding any movable parts, it is possible to reduce the number of failures, increase the service life, and improve the reliability of the product. is white clay.

[Brief explanation of the drawing]

The drawings relate to an embodiment of the present invention, and FIG. 1 is an enlarged view of part A in FIG. 2, FIG. 2 is a partially cross-sectional schematic diagram of the fuel injection nozzle, and FIG. 3 shows the injection Ql* on the vertical axis. , is a characteristic diagram showing crank superelectricity on the horizontal axis. 3... Nozzle body, 3a... Tip, 6... Rick hole, 7a, 7b... Nozzle hole, 8a... Seat part,
9... Barrel portion 9.12... Vessel body, 13... Damper chamber, 20... Needle valve, 20a... Tapered surface, 20c... Step portion.

Claims (1)

[Claims] A plurality of nozzle holes are formed at the tip of the nozzle body, at least one of the nozzle holes communicates with a suck hole formed within the nozzle body, and at least one other nozzle hole is formed within the nozzle body. The damper chamber communicates with a seat portion formed in the upper part of the suck hole, and the tapered surface of the needle valve inserted into the nozzle body so as to be freely retractable can be inserted into the seat portion. A fuel injection nozzle device for an engine, characterized in that the nozzles can be freely spaced closely together.