JP2526627Y2 - Fuel injection valve for internal combustion engine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a fuel injection valve for an internal combustion engine.

[Conventional technology]

As shown in FIG. 3 (a), a conical valve seat c that expands outward is formed on the front end surface b of the fuel injection valve a, and the front end b of the fuel injection valve around the valve seat c is removed. 2. Description of the Related Art A known fuel injection valve is formed from a flat surface, has a conical valve body d seated on a valve seat c, and injects fuel from a nozzle port formed between the valve seat c and the valve body d. Yes (Shinkai Sho64
-69180). In this fuel injection valve, the fuel ejected from the nozzle port spreads conically.

[Problems to be solved by the invention]

However, when the fuel is ejected from the nozzle port, the air around the nozzle port is sucked into the fuel that advances, so that the pressure around the nozzle port becomes lower than other parts. As described above, when the pressure around the nozzle opening decreases, part of the injected fuel is drawn back around the nozzle opening. At this time, if the front end face b of the fuel injection valve around the nozzle opening is formed as a flat surface as shown in FIG. 3 (A), the pulled back fuel gradually adheres to the front end face b. When the fuel adheres in this manner, the adhered fuel is in a state of burning, so that not only a large amount of unburned HC and CO is generated, but also a large amount of deposits e, which are burnt residues, are deposited on the front end face b. This deposit e affects the spread angle of the fuel ejected from the nozzle port, and as shown in FIG. 3 (A), when the deposit e adheres to the tip surface b, the spread of the fuel increases as the amount of the deposit e increases. The corners are getting smaller.

Further, as shown in FIG. 3 (B), when the valve element d is protruded from the distal end face b, fuel adheres to the protruding outer peripheral surface portion and the distal end face b of the valve element d, and a deposit e is deposited,
As shown in FIG. 3 (c), when the valve element d is retracted from the front end face b, the fuel adheres to the front end outer peripheral portion of the valve seat c and the front end face b, and the deposit e is deposited. Therefore the third
In any of the structures shown in FIGS. (A), (B), and (C), not only a large amount of unburned HC and CO is generated due to the adhesion of the fuel, but also as the amount of deposit e increases, the amount of the injected fuel increases. This causes a problem that the spread angle changes.

[Means for solving the problem]

In order to solve the above problems, according to the present invention, a conical valve seat is formed at the distal end of the fuel injection valve, and the conical valve seat is seated on the valve seat. In the fuel injection valve, in which fuel is ejected from between the valve body and the valve seat by moving the valve body outward, the entire distal end surface of the conical valve body exposed in the combustion chamber is changed from a flat surface or a concave surface. The cross-sectional shape of the tip of the annular fuel injection valve having a conical valve seat is formed into a knife-edge shape forming an acute angle β, and the cross-sectional shape of the peripheral edge of the conical valve body is substantially equal to the acute angle β. It is formed in the shape of a knife edge having an acute angle α, so that when the valve body is closed, the point of the tip of the knife edge of the conical valve body and the point of the tip of the knife edge fuel injector overlap each other. I have.

[Action]

As described above, if the acute angle α and the acute angle β are substantially equal, the pulled back fuel is unlikely to reach either the outer peripheral surface of the fuel injector distal end portion or the distal end surface of the valve element. As a result, the deposit hardly adheres to both the outer peripheral surface of the fuel injection valve distal end portion and the distal end surface of the valve element. Even if the deposit adheres, the degree of adhesion to the outer peripheral surface of the front end surface of the fuel injection valve and to the front end surface of the valve body becomes the same, so that the fuel injection direction does not change.

〔Example〕

Referring to FIG. 1, reference numeral 1 denotes a fuel injection valve shown schematically, and the fuel injection valve 1 is a combustion chamber 2 of an internal combustion engine.
It is attached to the cylinder head 3 for injecting fuel into the inside. The fuel injection valve 1 includes a movable core 5 operated by a solenoid 4 and a needle 6 operated by the movable core 5. Fuel is supplied from a fuel supply port 8 into a fuel passage 7 around the needle 6. When the solenoid 4 is energized and the movable core 5 is lowered, the needle 6 is lowered, whereby the fuel injector 1
Is injected into the combustion chamber 2 from the front end 9 of the fuel cell.

FIGS. 2A and 2B show the tip 9 of the fuel injector 1 of FIG.

2 (A) and 2 (B), a conical valve seat 10 which expands outward is provided at the tip 9 of the fuel injection valve 1.
The needle 6 has a valve seat 10 at its tip.
A conical valve body 11 seated on the upper part is integrally formed. When the needle 6 is lowered, an annular nozzle port is formed between the valve seat 10 and the valve element 11, and fuel is ejected from the nozzle port. The distal end portion 9 of the fuel injection valve 1 extends annularly around the valve seat 10, and the cross-sectional shape of the annular distal end portion 9 is formed in a knife edge shape having an acute angle β. Further, the cross-sectional shape of the peripheral edge of the distal end of the valve element 11 is also formed in a knife edge shape forming an acute angle α. Further, as shown in FIG. 2, the tip 12 of the distal end portion 9 is formed flush with the distal end surface 13 of the valve body 11 when the valve body 11 is closed, and accordingly, the valve body 11 is closed. When the valve is opened, the pointed position of the peripheral edge of the knife-edge-shaped tip of the valve element 11 and the pointed position of the distal end of the knife-edge-shaped fuel injection valve overlap each other. In the embodiment shown in FIG. 2 (A), the distal end surface 13 of the valve body 11 is formed flat, and the angle α is formed slightly larger than the angle β. On the other hand, in the embodiment shown in FIG. 2 (B), the distal end surface 13 of the valve element 11 is formed in a concave surface, and the angle α is formed substantially equal to the angle β.

When the needle 6 is lowered and the valve body 11 separates from the valve seat 10, fuel is injected into the combustion chamber 2 from a nozzle port formed between the valve body 11 and the valve seat 10. At this time, the fuel is the valve seat
As the fuel proceeds along the inner surface of the 10 conical shapes, the fuel spreads conically into the combustion chamber 2 as shown by F in FIG. 2 (A). However, when the fuel is ejected from the nozzle opening as described above, the fuel draws in the surrounding air as soon as the fuel is ejected from the nozzle opening, and thus the pressure around the ejected fuel is reduced. However, as shown in FIG. 2, when the periphery of the fuel injection valve tip 9 is formed from a conical outer peripheral surface 14, the tip surface 9 is smaller than in the conventional case where the fuel injection valve tip has a large area. The pressure around the distal end surface 9 does not decrease so much because the amount of surrounding air is large. as a result,
The effect of drawing the fuel toward the periphery of the front end face 9 is weakened.
In addition, since the periphery of the tip 9 is formed from the conical outer peripheral surface 14, the distance between the injected fuel and the conical outer peripheral surface 14 becomes longer, so that the injected fuel does not reach the conical outer peripheral surface 14. Become easy. As a result, it becomes difficult for fuel to adhere to the conical outer peripheral surface 14, and thus it is possible to suppress generation of a large amount of unburned HC and CO. Also, if fuel squirts, valve seat 10
Fuel adheres to the conical inner wall surface and the conical outer peripheral surface of the valve body 11, but if the valve body 11 is closed as shown in FIG. 2, the adhered fuel is not directly exposed to the combustion gas. Therefore, unburned HC and CO are not generated by the deposited fuel, and no deposit is deposited on the conical inner wall surface of the valve seat 10 and the conical outer peripheral surface of the valve body 11, so that the spread angle of the fuel is reduced. There is no change.

Even if deposits accumulate on the conical outer peripheral surface 14 of the distal end portion 9 and the distal end surface 13 of the valve element 11, the deposits have almost no effect on the spread angle of the fuel because the angles α and β are acute. Absent. Even if the influence is exerted, in the embodiment shown in FIG. 2 (A), there is no large difference between the angle α and the angle β, so that the divergence angle of the fuel does not change much, and the embodiment shown in FIG. Since the angle α is equal to the angle β, the spread angle of the fuel does not change.

That is, as shown in FIGS. 2A and 2B, when the angle α is substantially equal to the angle β, the deposit adheres to the conical outer peripheral surface 14 of the distal end portion 9 and the distal end surface 13 of the valve element 11. Even so, the amount of deposit attached to the conical outer peripheral surface 14 and the distal end surface 13 is substantially the same. As a result, these deposits have the same effect on the deflecting action of the injected fuel F in the flight direction, that is, the deposit attached to the conical outer peripheral surface 14 reduces the spread angle of the injected fuel F. The deposits attached to the tip surface 13 act to increase the spread angle of the injected fuel F. However, since these actions become almost the same, even if the deposits are attached, the spread angle of the injected fuel F is It is maintained at the normal spread angle when it is not attached.

[Effect of the invention]

After the injection, the pulled back fuel hardly reaches either the outer peripheral surface of the distal end portion of the fuel injection valve or the distal end surface of the valve body. Deposits are difficult to adhere. As a result, it is possible to prevent the spread angle of the injected fuel from changing. Even if deposits adhere to the outer peripheral surface of the distal end portion of the fuel injection valve and the distal end surface of the valve element, the amount of these deposits is substantially the same. Therefore, these deposits have the same effect on the flight direction of the injected fuel, so that the spread angle of the injected fuel does not change even in this case.

[Brief description of the drawings]

FIG. 1 is a schematic side sectional view of a fuel injection valve, and FIG.
The figure is an enlarged side sectional view of the tip of the fuel injection valve, and FIG. 3 is a view showing an undesired tip shape of the fuel injection valve. 6 ... Needle, 9 ... Fuel injection valve tip, 10 ... Valve seat, 11 ...
Valve body, 12 ... pointed.

 ──────────────────────────────────────────────────続 き Continuation of the front page (56) References Japanese Utility Model Showa 49-49115 (JP, U) Japanese Utility Model Showa 58-2363 (JP, U) Japanese Utility Model Showa 57-204463 (JP, U)

Claims (1)

(57) [Scope of request for utility model registration] 1. A fuel injection valve having a conical valve seat formed at the tip thereof and expanding outward, and a conical valve body seated on the valve seat. In a fuel injection valve in which fuel is ejected from between a valve body and a valve seat by moving the valve body toward the combustion chamber, the entire distal end surface of the conical valve body exposed in the combustion chamber is formed from a flat surface or a concave surface, and the conical valve The cross-sectional shape of the tip of the annular fuel injection valve forming the seat is formed as a knife edge forming an acute angle β, and the cross-sectional shape of the tip peripheral edge of the conical valve body is formed at an acute angle α substantially equal to the acute angle β.
The fuel injection for an internal combustion engine in which the point of the tip of the knife-edge-shaped tip of the conical valve and the point of the tip of the knife-edge-shaped fuel injection valve overlap each other when the valve is closed. valve.