JPS6027826Y2 - fuel injection valve - Google Patents

Description

[Detailed explanation of the idea] The present invention relates to a fuel injection valve.

Conventionally, the fuel injection valve used in the fuel injection device is
To explain the figure, a needle valve 2 is inserted into a nozzle body 1, and high-pressure fuel is sent from a fuel injection pump 3 to a fuel reservoir 5 through a fuel passage 4, against the force of a spring 6. When the needle valve 2 opens upward, fuel is injected from the hole nozzle 8 through the zipper volume 7 provided at the tip of the nozzle body 1.

After fuel injection, the fuel pressure in the fuel reservoir 5 decreases, the needle valve 2 closes downward by the force of the spring 6, and the fuel supply is cut off.

In such a conventional fuel injection valve, the lift characteristic of the needle valve 2 is such that the initial rise speed (□=tanθ) is strong as shown by the dotted line 9 in Fig. 4, so the amount of injection during the ignition delay is large. As a result, diesel knock is more likely to occur, and a large amount of noise and vibration from the diesel engine and NOx in the exhaust gas are generated.

However, in conventional slot nozzles where the bottle portion at the tip of the nozzle valve has two stages, pilot injection is performed to reduce the amount of injection during ignition delay to alleviate the above problem. This slot nozzle is quite troublesome to process, and it also has the problem that it cannot be applied to a hole nozzle.

The purpose of the present invention is to solve the above-mentioned problems by reducing the injection amount during the ignition delay, thereby reducing the cylinder's maximum explosion pressure and maximum combustion gas temperature, thereby reducing the noise, vibration, and contaminants in the exhaust gas of the diesel engine. The purpose of the present invention is to provide a fuel injection valve for a diesel engine that reduces the NOx chemical composition, improves engine performance, and prevents pollution.

Hereinafter, an embodiment of the fuel injection valve according to the present invention will be described with reference to FIGS. 2 and 3.

Here, the same or equivalent components as those of the conventional device will be described using the same reference numerals.

As shown in FIG. 2, the nozzle tip 10 consists of a nozzle body 1 and a needle valve 2, and is assembled into a nozzle holder and attached to a cylinder bed.The nozzle tip 10 and its tip are composed of a cylinder head and a piston 11. Combustion chamber 1
7 and is provided protrudingly.

The outer shape of the nozzle body 1 is a stepped cylinder having a large and small outer diameter, the tip of which is shaped like a protrusion, and has an oil reservoir 5 and a valve seat 13 at the bottom of the axis, and a spiral on its inner surface. A central hole provided with a groove 12a and a fuel passage 4 that communicates the upper circular groove of the nozzle body 1 with the oil reservoir 5 are bored, and a hole nozzle 8 is formed radially from the back volume 7 provided at the lower end of the center. is drilled.

The needle valve 2 inserted into the nozzle body 1 is made of a stepped cylinder having a large and small outer diameter, and its tip is shaped like a cone and comes into contact with the valve seat 13 at that part. As shown in the figure, a spiral strip 12b that engages with a back gap h' is formed at a position corresponding to the spiral groove 12a of the nozzle body 1, and the back gap h' between the spiral groove 12a and the spiral groove 12b is formed with a needle It is configured to be larger than the maximum lift h of the valve 2.

The needle valve 2 is always urged downward in the direction of arrow A by a spring 6 as shown in FIG. ing.

The oil reservoir 5 in the nozzle tip 10 and the fuel injection pump 3 are communicated through a fuel passage 4.

Next, its effect will be explained.

As shown in FIGS. 2 and 3, the spiral strip 12b of the needle valve 2 and the spiral groove 12a of the nozzle body 1 engage with each other with a back gap, and the upper surface portion of the spiral strip 12b and the spiral groove 12a They are at rest in contact with each other.

At the end of the compression stroke of the cylinder, a fuel injection pump 3 driven by the crankshaft is passed through a fuel passage 4 to a nozzle tip 1.
When high-pressure fuel is sent to the fuel reservoir 5 at 0, the needle valve 2 rotates along the spiral groove 12a engaged by the spiral strip 12b against the force of the spring 6, and rises at a low speed by the lift h. The fuel passes through the sack volume 7 and is injected from the hole nozzle 8.

After fuel injection, the pressure of the fuel in the fuel reservoir 5 decreases, and the needle valve 2 closes the axial clearance h provided between the nozzle bodies 1.
', the nozzle valve 2 freely descends under the force of the spring 6, similar to the conventional nozzle valve 2.

After the needle valve 2 contacts the valve seat 13, it rotates due to the torsional bias applied to the needle valve 2, and the conical part of the needle valve 2 and the valve seat 13 of the nozzle body 1 are in close contact with each other, and the upper surface of the spiral thread 12b It returns to its original state as shown in FIG. 3, where it is in contact with the spiral groove 12a, and comes to rest.

Since the needle valve 2 rises while rotating as shown in the lift curve shown by the solid line 14 in FIG. Since the fuel injection amount is reduced, diesel knock is less likely to occur, and the explosion pressure in the cylinder
As shown in the figure, the temperature decreases from the broken line 15 to the solid line 16, and the fuel gas temperature also decreases.

Therefore, engine noise, vibration, NOx in exhaust gas, etc. can be reduced.

Note that the pitch of the spiral 12 must be large because it does not automatically tighten, and by selecting various pitch lengths, the rising speed of the needle valve 2 can be arbitrarily changed.

As described above, in the fuel injection valve of the present invention, the nozzle body and the needle valve inserted therein are engaged with each other by a pair of helical grooves and helical strips having an axial clearance larger than the maximum lift of the needle valve. Therefore, when the needle valve rises (opens), it rises while rotating along the spiral groove, which reduces the rising speed, reduces the amount of fuel injected during ignition delay, prevents knocking, and increases the cylinder's maximum explosion pressure. It also has the effect of lowering combustion gas temperature, reducing diesel engine noise and vibration, and NOx in exhaust gas, improving engine performance, and preventing engine pollution.

Note that when the needle valve is lowered (closed), there is a gap greater than the maximum lift of the needle valve provided between both helices, so the needle valve of the present invention freely descends due to the spring force, similar to conventional needle valves. Therefore, the running out of fuel after fuel injection is exactly the same as in the past, and the implementation of the present invention does not cause any negative effects such as the generation of black smoke.

[Brief explanation of drawings]

Fig. 1 is a schematic sectional view of a conventional device, Fig. 2 is a schematic sectional view of an embodiment of the present invention, Fig. 3 is an enlarged sectional view of the helical engagement part in Fig. FIG. 5 shows a characteristic curve of the lift h as a function of the needle valve time t, and FIG. 5 shows a characteristic curve of the explosion pressure p as the crank angle φ changes. 1... Nozzle body, 2... Needle valve, 12a... Spiral groove, 12b... Spiral strip.

Claims (1)

[Scope of utility model registration request] A heat injection valve comprising a nozzle body with a valve seat provided at the lower end of a center hole, and a needle whose tip inserted into the center hole of the nozzle body abuts the valve seat and is biased toward the valve seat. , a spiral groove is formed in the center hole of the nozzle body, and a spiral strip is formed that engages with the stem portion of the needle valve with a back gap, and the back gap between the spiral groove and the spiral strip is formed in the needle valve. A fuel injection valve characterized in that the lift is larger than the maximum lift of the valve, and the needle valve is incorporated so as to be constantly biased in the screwing direction.