JPH0217179Y2 - - Google Patents

Description

[Detailed Description of the Invention] Industrial Application Field This invention relates primarily to improvements in fuel injection nozzles used in direct injection diesel engines.

BACKGROUND ART Conventionally, injection nozzles used in direct injection diesel engines have generally been of the internal type, and for example, the one described in Japanese Utility Model Application No. 112918/1983 is known. That is, in such an internally opening type injection nozzle, as shown in FIG. 1, the tip of the main body 1 is formed into a substantially conical shape, and
A seat portion 2 is formed on the inner wall surface of the tip, and a plurality of nozzle holes 3 are formed at the position of the seat portion 2. Furthermore, a needle valve 4 is slidably inserted into the body main body 1, and a substantially conical seat is provided at the tip of the needle valve 4 to seat on the seat portion 2 and close the nozzle hole 3. A surface 5 is formed. Further, a pressure stage 6 is formed in the needle valve 4, and an oil reservoir 7 is formed between the pressure stage 6 and the inner wall surface of the body main body 1.
A small clearance portion 10 is formed between the lower inner wall surface 8 of the needle valve 4 and the tip end surface 9 of the needle valve 4.

However, in the case of such a conventional inward-opening injection nozzle, the fuel that has flowed toward the tip of the body main body 1 during fuel injection also flows into the clearance part 10 and accumulates therein, so that the fuel that has flowed toward the distal end of the body main body 1 during fuel injection flows into the clearance part 10 and accumulates therein. The seat part 5 of the needle valve 4 is attached to the seat part 2 of the
Since the fuel in the clearance portion 10 is pressed by the tip surface 9 of the needle valve 4 immediately before the needle valve descends and is seated, the seating cannot be performed smoothly due to the pressure reaction force. Therefore, the fuel injection becomes difficult to achieve, resulting in poor combustion, and as a result, even if the clearance portion 10 is set small, there is a problem in that the HC concentration in the exhaust gas cannot be reduced sufficiently.

There are also external injection nozzles which do not have the above disadvantages and are mostly used in gasoline engines. Although such an injection nozzle is not shown, a needle valve is slidably inserted into the body, and a conical seat formed at the tip of the needle valve is formed on the outer surface of the tip of the body. The fuel is seated on a seat section with a circular shape formed between the seat section and the seating section to close off a circular nozzle hole formed between the seat section and the seating section. Since the fuel is always injected into the combustion chamber while being widely diffused, the penetration power of the spray becomes weak, and it is not necessarily suitable for diesel engines that require strong penetration power. In addition, for example, in the case of an outward-opening injection nozzle described in Japanese Utility Model Application Publication No. 57-8362, the injection hole is formed in the peripheral wall of the nozzle valve, and the injection hole is laterally formed on the peripheral wall surface of the nozzle body. Because it is blocked from the direction, not only is the atomization promotion and swirl generation in the early stage of injection insufficient, but also the penetration force in the middle to late stages of injection is weak, making it impossible to obtain a good combustion state. It is not possible to sufficiently improve fuel injection cut-off at times.

Purpose of the present invention The present invention was devised in view of the problems of the internally opening type injection nozzle and the externally opening type injection nozzle as described above. While ensuring a wide range of fuel diffusion in the early stage, strong penetration power of the spray is obtained from the middle to late stages of injection, improving the overall combustion state, and reducing the HC concentration in the exhaust gas. The purpose is to improve exhaust performance.

Purpose of the present invention The present invention was devised in view of the problems of the internally opening type injection nozzle and the externally opening type injection nozzle as described above. While ensuring a wide range of fuel diffusion in the early stage of injection, strong penetration power of the spray is obtained from the middle to late stages of injection, improving the overall combustion state and reducing the HC concentration in the exhaust gas. The purpose is to improve the exhaust performance of.

The injection nozzle for diesel engines according to the present invention is
A body body having an oil reservoir inside, a guide hole formed at the tip of the body body, a seat portion formed near the outer edge of the tip portion of the guide hole, and an oil reservoir opening in the seat portion and containing the oil. A nozzle hole formed in the body main body in an expanded shape and communicating with the reservoir, a needle shaft slidably inserted into the body main body, and a needle shaft formed at the tip of the needle shaft and fitted into the guide hole. The valve head is formed at the tip of the actuating part to have a larger diameter than the actuating part, and is seated on the seat part from the outside to close the nozzle hole from a substantially vertical direction. .

Embodiment of the present invention Hereinafter, a specific embodiment of the present invention will be described in detail based on the drawings.

FIG. 2 shows the entire injection nozzle according to the present invention, where 11 is a body body held by a holder 30, and 12 is a needle shaft slidably inserted into the body body 11. , the needle shaft 12 has a spring seat 21,
A coil spring 23 disposed between 22 constantly biases the coil spring 23 in the backward direction, that is, upward in the figure.

As shown in FIGS. 2 and 3, the body main body 11 has an oil reservoir portion 1 inside which communicates with a fuel passage 13.
4, a cylindrical guide hole 15 is formed in the tip portion 11a, and a circular seat portion 16 is provided near the outer edge of the tip portion of the guide hole 15.
is formed. Further, on the outside of the guide hole 15, there are a plurality of nozzle holes 18 which are arranged at a certain angle and spread out, with one end communicating with the oil reservoir part 14 and the other end opening into the seat part 16. is formed. On the other hand, as shown in FIG. 3, the needle shaft 12 has a cylindrical actuating part 19 formed at its distal end 12a that vertically slides into the guide hole 15 of the body main body 11, and the distal end of the actuating part 19. A valve head 20 is formed on the upper surface of the valve head 20, and a substantially conical seating surface 20a is provided on the upper surface of the valve head 20 to directly sit on the seat 16 and close the opening 18a of the nozzle hole 18.
The structure has been formed.

Next, the operation of the above embodiment will be explained. Since the needle shaft 12 is urged upward by a coil spring 23 as shown in FIGS. 2 and 3, in the normal state, the needle shaft 12
is seated on the seat portion 16 of the body main body 11, but when the pressure of the fuel that has entered the oil reservoir portion 14 through the fuel passage 13 increases and exceeds the set pressure of the coil spring 23, as shown in FIG. As shown, the operating portion 19 of the needle shaft 12 is pressed downward along the guide hole 15 of the main body 11, and the seating surface 20a of the valve head 20 is separated from the seat portion 16 accordingly. Therefore, the fuel O in the oil reservoir 14 passes through the injection hole 18 and is injected from the opening 18a of the seat 16. Then, at the beginning of the descent of the shaft 12, a small amount of the fuel reaches the seating surface 2 of the valve head 20.
It strongly interferes with the upper surface near the outer periphery of 0a and is injected to the periphery of the combustion chamber while being diffused in a fan shape. Therefore, fuel atomization is promoted and a strong swirl is generated, thereby improving air utilization efficiency. Further, in the latter half of the descent when the shaft 12 further descends, the valve head 20 is located within the fuel injection angle range as shown in FIG. 5, so a large amount of fuel O collides with the seating surface 20a of the valve head 20. The fuel is directly injected into the center of the combustion chamber with a strong penetrating force, and the fuel forms a so-called walget and effectively mixes with the air around the combustion chamber. As described above, the operation of the needle shaft 12 causes the fuel to spread over a wide range within the combustion chamber.

Next, at the end of fuel injection, the valve 12 is raised by the biasing force of the coil spring 23 due to the reverse action, and the seating surface 20a of the valve head 20 closes the opening 18a of the nozzle hole 18 from below and outside. 18a from a substantially perpendicular direction, fuel injection is reliably and promptly blocked.

Incidentally, in the above embodiment, the nozzle hole 18 is formed by a plurality of small holes, but it is also possible to form a plurality of long holes.If the nozzle hole 18 is formed by a plurality of long holes, not only will the nozzle hole 18 be easily formed, Fuel injection power can be changed.
Also, the seating surface 2 can be adjusted by arbitrarily changing the expansion angle of the nozzle hole 18.
It is also possible to freely set the collision period of the injected fuel with respect to 0a.

Effects of the Present Invention As is clear from the above description, the injection nozzle for diesel engines according to the present invention has an injection hole that opens in the seat portion of the body main body and communicates with the oil reservoir portion, which is located approximately vertically at the valve head of the needle shaft. Since it is configured to close from the direction, the fuel can be shut off reliably and immediately at the end of injection, so unlike conventional internal injection nozzles, the combustion condition deteriorates and the HC concentration in the exhaust gas decreases due to poor injection cutoff. The problem of not being thin enough is eliminated.

Moreover, unlike the case of conventional outward-opening injection nozzles, the nozzle hole according to the present invention is configured to open in the seat portion, communicate with the oil reservoir, and be formed in the body main body in an expanded shape. During the initial stage of the needle shaft's descent, the fuel interferes with the valve head and is injected into the periphery of the combustion chamber, promoting atomization and generating a strong swirl, while in the later stages of the needle shaft's descent, a strong penetrating force directly penetrates into the combustion chamber. It is injected approximately into the center of the combustion chamber. Therefore, it is possible to inject a large amount of fuel with strong penetrating force while ensuring fuel injection over a wide range within the combustion chamber, which improves combustion by improving air utilization efficiency and prevents the above-mentioned injection failure. Combined with the good performance, fuel consumption can be reduced and exhaust gas countermeasures can be thoroughly implemented.

[Brief explanation of the drawing]

Fig. 1 is a sectional view of a main part showing a conventional internally opening type injection nozzle, Fig. 2 is a sectional view showing an embodiment of an injection nozzle according to the present invention, and Fig. 3 is a sectional view of a main part showing the same embodiment. , FIG. 4 is an explanatory diagram showing the initial downward state of the needle valve in the same embodiment, and FIG. 5 is an explanatory diagram showing the late descending state of the needle valve in the same embodiment. DESCRIPTION OF SYMBOLS 11... Body main body, 11a... Tip part, 12... Needle shaft, 12a... Tip part, 14... Oil reservoir part, 15... Guide hole, 16... Seat part, 18... Nozzle hole, 18a... Opening part, 19... Operating part , 20...valve head.

Claims (1)

[Scope of utility model registration request] a body body having an oil reservoir inside; a guide hole formed at the tip of the body body; and a seat portion formed near the outer edge of the tip of the guide hole;
a nozzle hole that opens in the seat portion and communicates with the oil reservoir portion, and is formed in the body main body in an expanded shape;
a needle shaft slidably inserted into the body; an actuating part formed at the tip of the needle shaft and fitting into the guide hole; An injection nozzle for a diesel engine, comprising a valve head that is formed and seats on the seat portion from the outside and closes the injection hole from a substantially vertical direction.