JPS5813154A - Injection nozzle for diesel engine - Google Patents

Abstract

PURPOSE:To prevent fuel leakage from butted surfaces of a nozzle holder and a nozzle body by dispensing with passage of high pressure fuel through said butted surfaces. CONSTITUTION:A nozzle body 3 is formed with a drill hole 15 leading from an end surface 3b to an oil reservoir 8, and an opening end of the drill hole 15 at the end surface 3b side is closed with a drive plug 16 to form a fuel path 17. The nozzle body 3 is further provided with a fuel path 18 extending laterally of the fuel path 17 and opening to the outer peripheral surface of the nozzle body 3. The opening end of the fuel path 18 is formed with a counter-bore 19, and a nozzle nut 2 is formed radially with a screwed hole 20 in alignment with the counter-bore 19. A connector 12 is threaded into the screwed hole 20. Before the threading the connector into the hole 20, a seal is fitted in the counter- bore 19. Thus, fuel is supplied without passing through butted surfaces 1a, 3b of a nozzle holder 1 and the nozzle body 3 so that fuel leakage is prevented.

Description

[Detailed Description of the Invention] ``The present invention relates to an improvement in an injection nozzle used to inject high-pressure fuel from an injection pump into a combustion chamber of a diesel engine. , a mechanical type that opens and closes with a valve operated by a cam that rotates in synchronization with the engine, and an automatic type that opens and closes the fuel injection hole automatically with a valve that responds to the pressure of fuel from the injection pump. is known, and the latter automatic opening/closing injection nozzle is roughly divided into outward-opening type and inward-opening type depending on the direction of valve opening operation of the above-mentioned valve. Although the present invention can be applied to all automatic opening/closing type injection nozzles, regardless of whether they are of the type that opens inward or the type that opens inward, in this specification, for the sake of brevity, the description of the present invention will be limited to the automatic opening/closing type injection nozzle that opens inward. do.

Conventionally, this type of injection nozzle has a nozzle nut 2 screwed into the tip of a nozzle holder L, and a nozzle main body 3 is held by a shoulder 2a of the nozzle nut.
11 of the nozzle body J by pressing it onto the nozzle holder L through a.
11tlJl) to the nozzle body l correspondence 1111[/! L
Press and hold. Then, attach the needle valve l to the nozzle body J.
from the nozzle holder/side, and the tip needle bar a and the conical surface of the needle valve are inserted into and seated in the corresponding fuel injection hole 30 and valve seat 3d of the nozzle body 3, respectively. At this time, the needle valve is in the closed position □゛, and this closed position is maintained by the nozzle spring j in the nozzle holder l via the spring retainer 4 and the bushing rod 7. The nozzle body 3 has an oil reservoir l facing the valve seat 3d, three fuel passages t leading from this oil to IllIrM3b, and these passages 9.
Grooves 10 and e are provided on the first surface 3b, respectively.

In addition, the nozzle holder l has a fuel passage/
An opening is provided in the outer circumferential surface of the nozzle holder I, and a connector I2 that is integrated with the end of a fuel conduit (not shown) extending from an injection pump (not shown) is screwed into this opening 13. When screwing in the connector 2, a gasket is inserted between the screwing tip of the connector 12 and the nozzle holder I, thereby preventing leakage of high-pressure fuel from the connector 12 toward the fuel passage. do.

In this configuration, each time high-pressure fuel is supplied from the injection pump through the connector /2 and into the oil sump l via the passage l11 groove 10 and the passage D, the oil sump v
) The fuel pressure generated in f moves the needle valve /
X ''f 9 , > r j &: Resistance 1' rise in Figure 1!1.

Open the fuel injection hole 3o. Therefore, every time high-pressure fuel is supplied from the engine pump, the injection nozzle injects the fuel from the fuel injection hole 70 into the engine combustion chamber, thereby enabling the engine to operate.

However, in such a conventional injection nozzle, the end If Jb of the nozzle body 3 is pressed and held against the increased surface /a of the nozzle holder l by the binding force of the nozzle nut 1, and a pressing force of 1N is applied.
! 11 provides a liquid-tight seal for both A1 surfaces, tb, and /l, so if the nozzle holder L and nozzle body J are both new, the contact end surfaces of both /& and Jb are still precisely finished. However, if you disassemble and reassemble for the purpose of repair etc.
/, 9 often leaked from between the 1i11 surfaces 711 and 76. This means that once the injector nozzle is assembled, the butt 1l
11/L, Jk) are both scratched, and even if the nozzle holder I and nozzle body 3 are placed in the same relative position as before and butted against each other during reassembly, the above fuel leakage cannot be completely avoided. That's the reality! ◎ For this reason, there are many complaints that conventional injection nozzles leak fuel at the above-mentioned parts, resulting in poor fuel efficiency once they are sent for repair. It had become noticeable.

In order to solve this problem, it is possible to insert a gasket between the ends [1/a and 76, as proposed in Japanese Patent Application Laid-Open No. 1410-19, but in this case, the number of parts Not only is this expensive and difficult to handle, but especially if a different type of oil is accidentally mixed into the fuel, depending on the material of the gasket, it may corrode and become useless, or the pieces that fall off may cause damage to the needle valve. There are concerns that the problem may be damaged, such as damaging the PIL sheet or clogging the fuel injection hole 30, and it has been confirmed that a complete solution to the problem cannot be expected despite these inconveniences.

Therefore, from the above viewpoint, the applicant has provided a fuel passage leading to the oil reservoir by opening on the outer circumferential surface of the nozzle body so that there is no need for high-pressure fuel to pass through the abutting surface between the nozzle holder 1 and the nozzle body. Japanese Patent Laid-Open No. 16-11 discloses an in-1 engine nozzle for diesel engines, which is constructed so that a fuel conduit from an engine engine pump is connected to the opening, thereby completely solving the above-mentioned problem of fuel leakage.
However, in this configuration, which was previously proposed in the No. As a result of the increased sliding contact area between the nozzle body and the needle valve, there is a possibility that the needle valve becomes reluctant to stroke due to the increased sliding resistance between the nozzle body and the nozzle body.

Therefore, the present invention further improves the injection nozzle so that the above-mentioned limit does not occur. Specifically, the aim (support) product between the needle valve and the nozzle body is
Easel engine injection with a gap of 1° between the needle valve and the nozzle body, leaving the minimum length necessary for guiding the needle valve, so as to provide the minimum distance necessary for guiding the needle valve. The aim is to provide a nozzle.

Hereinafter, the present invention will be described in detail based on illustrated embodiments, and its effects will be mentioned.

FIG. 3 and FIG. q show an example configuration of the injection nozzle of the present invention. In the present invention, a drill hole j is formed in the nozzle body 3 from its end surface 3b to the oil reservoir l,
The open end of this drill hole /S on the mtlJb side is closed with a plug 14 (which may be screwed in) to form a fuel passage T. The nozzle body 3 further includes a fuel passage /I extending laterally from the fuel passage 17.
A counterbore 19 is formed at the end of the opening.

A radial screw hole X is formed in the nozzle nut 2 in alignment with the counterbore 19, and the connector 2 described above is screwed into this screw hole. Prior to this screwing, seal the counterbore/de,
I/l-fit together, and when screwing in this seal to connector I2,
By applying pressure between this and the bottom of the counterbore 19,
□Seal the seal between the S-viewers.

Regarding the “□” configuration of the present invention, the connector 12
be located relatively close to the fuel injection hole 3C.
□, the bushing rod 7 shown in FIG. 1 becomes unnecessary, and the spring retainer 6 can be directly placed over the needle valve. Therefore, the nozzle hole kll can be made into a cylindrical shape, and the spring retainer 4 can be placed at the open end of the center hole of the nozzle holder, which is close to the end face L, and the total length of the injection nozzle can be shortened.

In addition, in the present invention, a needle valve that slidably penetrates into the needle valve guide hole n provided in the nozzle body 3,
Other than the minimum length necessary for guiding the needle valve -
(!I!!I In the illustration, except for the predetermined length guide part of the needle valve near the oil sump r) is g.

As shown in T, the diameter is smaller than that of the guide hole n, and an annular gap 2? is formed between the two. f - Set. Note that the gap n does not necessarily have to be annular as in the illustrated example, and in short, it is an i-id hole.
It is fine if the sliding contact area between the inner peripheral surface of the needle valve and the needle valve does not interfere with the guide of the needle valve. It is also possible to set a gap between the hole n and the inner peripheral surface.Furthermore,
In setting the above-mentioned gap, instead of machining the needle valve as in the illustrated example, the inner diameter of the guide hole n may be increased or a vertical groove may be formed on the inner peripheral surface thereof.

In the injection nozzle of the present invention having such a configuration, the fuel is supplied into the oil reservoir t through the passages /I and /7, and the fuel is injected into the engine combustion chamber from IL3(:i to the engine combustion chamber in the same manner as in the conventional case). However, during this time, the fuel is fed without passing through the mating surfaces /a, jb of the nozzle holder l and the nozzle body 3.
Fuel leakage, which has been a problem in the past, can be completely eliminated.

Furthermore, in the present invention, the nozzle body 3 is a needle valve due to the above *S location of the connector 12).

- Although the sliding area between the inner circumferential surface of the guide hole n provided in the nozzle body J and the needle valve valve tends to increase as the needle valve becomes longer in the evening direction (vertical direction in FIG. 3), as described above, the needle □ A gap n is set between the needle valve and the inner circumferential surface of the guide hole n within a range that does not interfere with the guide of the needle valve ginseng, and the structure is configured so as to eliminate as much as possible of the bacteria that are in contact with the needle valve. Nozzle body! By reducing the resistance between the two, smooth strokes can be achieved, and the occurrence of stiffness can be prevented.

French addition/l) Related original inventions are Ill! The fuel passage leading to the I reservoir is formed on the outer circumferential surface of the nozzle body, and the fuel conduit is connected to this opening. In order to eliminate this inconvenience, since the needle valve tends to stiffen, a device was devised to eliminate the sliding contact area between the nozzle body and the needle valve.

[Brief explanation of the drawing]

III/It is a longitudinal cross-sectional view of the conventional injection nozzle, Fig. 2 is a cross-sectional view of the Moom of Fig. 1, Fig. 3 is a vertical 11111m view of the injection nozzle of the present invention, and the Nozzle also shows the nozzle voice and body. IF on the J1th B-B line
I-, and the horizontal 11 [1f diagram] seen in the direction of the arrow. . I...Nozzle holder, /a...l, $Mating end 1, K...Nozzle nut, 2a...Shoulder J,,,,j'
l:? @ Noz At heather body, ja...shoulder, Jb...butt end face, 30...fuel injection hole, Jd...valve seat, 3...needle valve, daa...needle bar, Da b...cone d
l, reference c...needle valve small diameter part! ... Nozzle spring, 6... Pulp retainer, 7... Bush rod, t... Oil sump, 9. //...Fuel passage, 10
...Groove, 12...Connector, /l...Putskin,
/4...Plug, /? , /1...Fuel passage, l
De・° counterbore, 〃...screw hole, 1...seal, n...
...knee, dollar valve guide hole, n...gap. Patent applicant Shin Kano Figure 1 = Shoulder Figure 2

Claims (1)

[Scope of Claims] L A nozzle nut screwed into the nozzle holder presses and holds the nozzle body contained within the nozzle nut, and is slidably inserted into the nozzle body, and a nozzle spring is inserted into the nozzle body. The needle valve, which is kept in a closed position, is opened against the nozzle spring by the fuel pressure supplied to the oil reservoir formed in the nozzle body, so that fuel can be injected. In the nozzle, the fuel passage leading to the oil reservoir is formed only by a hole drilled in the nozzle body. At the same time, the end of the fuel passage far from the oil reservoir is opened on the outer peripheral surface of the nozzle body, and a screw hole is provided in the nozzle nut so as to be aligned with the opening of the fuel passage, and the injection pump is extended into the screw hole. The connector connected to the end of the fuel conduit is screwed to connect the fuel conduit to the fuel passage opening in a liquid-tight manner, and the necessary material for guiding the needle valve is provided between the two-dollar valve and the nozzle body. Diesel engine injection nozzle featuring a gap set by cutting the minimum length part.