JPH03149345A - Fuel injection nozzle - Google Patents

Abstract

PURPOSE:To reduce the volume of a sack part so enough as well as to abate the extent of HC content in exhaust gases and white smoke during idling and so on by housing a ceramic ball larger in diameter than a nozzle excellent in heat resistance, abrasion resistance, hardness and impact resistance in this sack part. CONSTITUTION:A sack part 4 provided with a nozzle 3 is installed in the tip of a nozzle body 2 having a needle valve 1 inserted in and held free of slide motion, and this sack part 4 and a fuel sump chamber 5 formed in this nozzle body 2 are both interrupted by the neddle valve 1. A ceramic ball 6 larger in diameter than a bore of the nozzle 3 and excellent in heat resistance, abrasion resistance, hardness and impact resistance is housed in the sack part 4 whereby volumetrical capacity in the sack part 4 is reduced as far as a portion equivalent to the volume of this ceramic ball 6. Accordingly, after closing the needle valve 1, an amount of fuel seeping out of the nozzle 3 is decreased as far as a portion equivalent to the volume of the ceramic ball 6. Consequently, HC content in exhaust gases is abated and simultaneously white smoke being seen during idling is ameliorated.

Description

Detailed Description of the Invention (Industrial Application Field) The present invention relates to a fuel injection nozzle that injects and supplies fuel to the combustion chamber of a diesel engine, and specifically relates to a fuel injection nozzle that injects fuel into the combustion chamber of a diesel engine. This invention relates to a fuel injection nozzle that can reduce the amount of water.

(Prior Art) In order to reduce the HC concentration in the exhaust gas of a diesel engine and white smoke during idling operation, conventionally, as shown in FIG. A low sack nozzle in which the tip of the needle valve C that opens and closes is largely protruded into the sack part to reduce the volume of the sack part, and a valve force bar provided with a spout on the seat surface of the needle valve. There are orifice nozzles, etc. (New Automotive Engineering Handbook (Part 4))
(See page 98, Figure 1-268, published by the Society of Automotive Engineers of Japan, September 30, 1980). d is the nozzle body, e
is a spout.

(Problem to be solved by the invention) By the way, in the former low sack nozzle, although the volume of the sack part can be reduced by an amount commensurate with the amount of thrust of the tip of the needle valve, there is a limit to increasing the amount of thrust. On the other hand, in the latter type of valve force bar orifice nozzle, it is necessary to close the nozzle with a needle valve, so the seat surface of the needle valve and nozzle body becomes large, and heat is transferred from this seat surface to the needle valve. There is a problem in that the fuel may be transmitted and cause a secondary failure, or the seating of the needle valve may be deteriorated due to the fuel trapped in the sack portion.

The present invention has been made in view of the above circumstances, and it is possible to reduce the HC concentration in exhaust gas and the white smoke during idling by sufficiently reducing the volume of the sack portion without adversely affecting the seating performance of the needle valve. The purpose of this project is to provide a fuel injection nozzle that can reduce the

<Means for Solving the Problems> In order to achieve the above object, the present invention increases the pressure in the fuel reservoir chamber to isolate the sack portion formed at the tip of the nozzle body and the fuel reservoir chamber. In a fuel injection nozzle that lifts a needle valve to inject fuel from a fuel reservoir chamber through a nozzle and into a combustion chamber, the fuel injection nozzle has a diameter larger than the inner diameter of the nozzle and has good heat resistance, wear resistance, hardness, and It is characterized in that ceramic balls with excellent impact resistance are housed in the sack portion.

<Operation> In the fuel injection nozzle configured as described above, when fuel discharged from the fuel injection pump is supplied to the fuel reservoir chamber and the pressure of the fuel reservoir chamber increases, the needle valve is lifted. Then, the fuel in the fuel reservoir chamber flows into the sack part, and is injected from this sack part through the nozzle into the combustion chamber.
When the pressure in the fuel reservoir chamber decreases as this injection progresses, the needle valve seats and closes the sack portion, thus ending fuel injection.

By the way, even after the needle valve is closed, the fuel in the tick part flows out (oozes) from the nozzle, but in the present invention, since the ceramic sphere is housed in the sack part, the fuel in the tick part is equivalent to the volume of the ceramic sphere. The volume of the sack portion is reduced accordingly, and the amount of fuel oozing out after the needle valve is closed is accordingly reduced.

Therefore, the HC concentration in the exhaust gas decreases, and
White smoke during idling can be improved.

In addition, since there is no need for the tip of the needle valve to extend far into the sack portion, even if the seat portion is worn out, there is no occurrence of a pushing-up phenomenon in which the tip of the needle valve comes into contact with the inner wall of the sack portion. The seating performance of the needle valve is not impaired. Furthermore, since there is no need to make the seat surface of the needle valve or nozzle body larger than necessary, excessive heat will not be transmitted to the needle valve and cause secondary damage. The seating performance of the needle valve will not deteriorate due to fuel.

<Example> Examples of the present invention will be described in detail below based on the drawings.

FIG. 1 is an enlarged cross-sectional view of the nozzle tip showing an embodiment of the fuel injection nozzle according to the present invention. A nozzle body 2 has a needle valve l slidably inserted therein, and a nozzle 3 has an injection port 3 at the tip. A sack portion 4 is provided, and this sack portion 4 and a fuel reservoir chamber 5 formed in the nozzle body 2 are isolated by the needle valve l. The needle valve l is urged to slide downward in the figure by a needle spring (not shown), and its tip seat is seated on the seat of the nozzle body 2, and the pressure in the fuel reservoir chamber 5 increases. When the lift force acting on the pressure receiving surface of the needle valve 1 becomes higher than the valve closing force by the needle spring, the needle valve 1 is lifted upward in the figure against the needle spring, and the fuel in the fuel reservoir chamber 5 is transferred to the sac portion 4. This is substantially the same as the conventional system.

Here, in the present invention, the ceramic balls 6 having a larger diameter than the inner diameter of the nozzle 3 and having excellent heat resistance, abrasion resistance, hardness, and impact resistance are housed in the sack portion 4. The volume of the sack portion 4 is reduced by an amount corresponding to the volume.

Therefore, after the needle valve 1 is closed, the amount of fuel seeping out from the nozzle 3 is reduced by an amount corresponding to the volume of the ceramic ball 6. For this reason, the HC concentration introduced into the exhaust gas is reduced, and at the same time, white smoke observed during idling operation is improved.

Furthermore, since the volume of the sack portion 4 is reduced by accommodating the ceramic balls 6, there is no need for the tip of the needle valve to protrude greatly into the sack portion, as is the case with conventional low sack nozzles, for example. Furthermore, unlike conventional valve force bar orifice nozzles, there is no need to enlarge the seat surface of the needle valve and nozzle body, and furthermore, the fuel is not trapped in the sac portion, so the seating performance of the needle valve may deteriorate. In addition, it has no heat resistance, abrasion resistance,
Since the ceramic balls 6 having excellent hardness and impact resistance are housed, the ceramic balls 6 will not be worn out or damaged.

In the above embodiment, the tip of the needle valve l is made flat to prevent interference between the tip of the needle valve l and the ceramic ball 6 when the needle valve l is seated. Sack part 4 by increasing the angle
Interference between the tip of the needle valve l and the ceramic ball 6 may be prevented by reducing the amount of plunge into the needle valve l.

(Effects of the Invention) As is clear from the above description, according to the present invention, a ceramic ball having a larger diameter than the nozzle, which has excellent heat resistance, abrasion resistance, hardness, and impact resistance, is accommodated in the sack part. By reducing the volume of this suck portion, it is possible to reduce the amount of fuel seeping out after the needle valve is closed. Therefore, according to the present invention, the volume of the sac portion can be sufficiently reduced without adversely affecting the seating performance of the needle valve, and He
It can reduce the concentration and white smoke during idling operation.

[Brief explanation of the drawing]

FIG. 1 is an enlarged sectional view of a nozzle tip showing an embodiment of the present invention, and FIG. 2 is an enlarged sectional view of a nozzle tip showing a conventional example. 1-... Needle valve 2... Tuzzle body 3...
・Nozzle port 4...Sack portion 5...Fuel reservoir chamber Low...Ceramic bulb Patent applicant Hino Motors Co., Ltd. Figure 1 Figure 2

Claims (1)

[Claims] (1) By increasing the pressure in the fuel reservoir chamber, the needle valve that shuts off the sac portion formed at the tip of the nozzle body and the fuel reservoir chamber is lifted, and the fuel in the fuel reservoir chamber is transferred from the sac portion to the nozzle outlet. In a fuel injection nozzle that injects fuel into a combustion chamber through Features a fuel injection nozzle.