JPH0614080Y2 - Fuel injection nozzle device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial application] The present invention relates to a fuel injection nozzle device used in a diesel engine, and more particularly to a fuel injection nozzle device having excellent durability against cavitation erosion.

[Conventional technology]

As a conventional fuel injection nozzle device, for example, the actual Kaisho Sho 60-1
The device proposed in Japanese Patent No. 80736 is known and will be described with reference to FIGS. 2 to 4.

The needle valve 2 of the fuel injection nozzle device N is urged by the spring 5a in the spring chamber 5 through the restraining shaft 6 that projects from the center of the shoulder portion 20 and extends through the through hole 8 of the intermediate plate 4. It is configured such that the fuel is stopped and the shoulder 20 abuts the intermediate plate 4 against the spring 5a by the pressure of the fuel passing through the fuel supply hole 10a. That is, the needle valve 2 is slidably fitted into the body 1 that is clamped to the holder 3 by the cap nut 12, and the lift amount is increased by the intermediate plate 4 arranged between the body 1 and the holder 3. It is limited, and this intermediate plate 4 has a fuel filling hole 10
A passage 10 communicating with a is provided.

The fuel leaked through the gap between the body 1 and the needle valve 2 flows into the spring chamber 5 of the nozzle holder 3 through the through hole 8 opened in the center of the intermediate plate 4.

A space 13 is formed in a portion surrounded by the body 1, the needle valve 2 and the intermediate plate 4, and the space 13 is formed only by the through hole 8 of the intermediate plate 4 through which the holding shaft 6 of the needle valve 2 penetrates. Is connected to the spring chamber 5 through the
When the fuel is stopped by the needle valve 2 being lowered by the urging force of 5a, the volume of the space 13 rapidly increases, so that a negative pressure is generated in the space 13 and bubbles are generated in the fuel in the space 13.

The bubbles are crushed by the high positive pressure generated by the sudden decrease in the volume of the space 13 during the fuel injection state in which the needle valve 2 rises in the opposite direction, and a higher pressure is generated. If this pressure is extremely high, it will corrode the surrounding wall.

This phenomenon is generally called cavitation erosion, but it is particularly likely to occur in an extremely narrow area of the restraining shaft root portion 7, and when the corrosion is severe, the restraining shaft root portion 7 is weakened due to gouge damage. There is a problem that an accident occurs in which it is lowered and broken.

In order to prevent the cavitation and erosion of the retaining shaft root portion 7, the above-mentioned Japanese Utility Model Laid-Open No. 60-180736 discloses, in a portion other than the contact portion of the needle valve shoulder portion 20 of the intermediate plate 4, By providing the communication hole 9 that connects the space portion 13 and the spring chamber 5, the pressure change due to the rapid volume change when the needle valve 2 is raised in the fuel injection state or lowered in the fuel stop state is passed through the communication hole 9. This is an attempt to suppress the fuel by taking it in or letting it escape.

By the way, in recent years, there is a tendency to increase the fuel injection pressure in order to improve fuel economy and improve exhaust gas characteristics. Therefore, when such high-pressure fuel injection is performed, the above-described pressure adjustment action by the communication hole 9 alone causes: The effect of attenuating the impact force due to cavitation becomes insufficient, and there is a risk that breakage of the holding shaft 6 of the needle valve 2 due to cavitation erosion may occur.

This is because both the needle valve shoulder 20 and the regulating surface 21 of the intermediate plate 4 with which the needle valve shoulder 20 contacts are orthogonal to the sliding axis of the needle valve 2 as shown in FIG. , Needle valve shoulder 20 subjected to impact force from cavitating
This is because it is not possible to secure a sufficient pressure receiving area and it is not possible to disperse the impact force of cavitation that is concentratedly generated at the portion of the holding shaft root portion 7 of the needle valve 2.

In addition, since the pressure receiving area of the needle valve shoulder 20 that collides with the restriction surface 21 of the intermediate plate 4 when the needle valve 2 is closed is small, the impact force per unit area received when the valve is closed is large and damage due to wear occurs. There was a problem.

[Problems to be solved by the device]

Therefore, in order to solve the above problems, the needle valve shoulder
This needle valve shoulder 20
By making the contact surface between the intermediate plate 4 and the intermediate plate 4 an inclined surface, the impact force of cavitation concentratedly generated at the restraining shaft root portion is dispersed, and the impact force per unit area received when the valve is closed is also reduced. However, it is proposed in Japanese Utility Model Publication No. 37-8651.

However, by making the shape of the needle valve shoulder 20 a frustoconical shape, the impact force of cavitation applied to the needle valve shoulder 20 can be dispersed to some extent, but the cross-sectional shape of the inclined surface is linear. Therefore, the effect of dispersing the impact force is not yet sufficient, and there is a problem that if it is used for a long period of time, the holding shaft 6 of the needle valve 2 may be broken due to cavitation erosion.

Further, even if the needle valve shoulder portion 20 has a frustoconical shape as described above, the pressure receiving area of the needle valve shoulder portion 20 that collides with the restriction surface 21 of the intermediate plate 4 when the valve is closed is not yet sufficiently large. However, the impact force per unit area received when the needle valve 2 is closed is still large, and there is a problem that damage due to wear cannot be sufficiently suppressed.

Further, since a corner is formed from the needle valve shoulder 20 to the axial direction of the needle valve 2, a turbulent flow occurs in the oil at this corner, and the turbulent flow deteriorates the oil flow. Therefore, there is a problem that the responsiveness of opening and closing the needle valve 2 is reduced.

In view of the above problems, the present invention can disperse the impact force of cavitation applied to the needle valve shoulder much more efficiently than the conventional fuel injection nozzle device.
Prevents breakage of the holding shaft even after long-term use, and further reduces wear when the needle valve is closed by reducing the impact force applied to the needle valve shoulder and the regulation surface of the intermediate plate. It is an object of the present invention to provide a fuel injection nozzle device capable of improving the opening / closing responsiveness of a needle valve by smoothing the flow of oil.

[Means for Solving the Problems]

To achieve the above object, a fuel injection nozzle device of the present invention comprises an intermediate plate through which a holding shaft of a needle valve penetrates, a body that abuts on one surface of the intermediate plate, and a holder that abuts on another surface of the intermediate plate. In the spring chamber formed in this holder, a spring for urging the restraining shaft in the body direction is housed, and the contact surface of the needle valve shoulder portion facing the intermediate plate is formed into a spherical shape, and The contact surface of the intermediate plate facing the shoulder portion of the needle valve is formed into a spherical shape so as to make surface contact with the contact surface.

[Action]

In the fuel injection nozzle device of the present invention, the contact surfaces of the needle valve shoulder portion and the contact surface of the intermediate plate, which face each other, are formed into spherical shapes, respectively. When the surface contact is made and the spring extends freely, the impact force of cavitation is applied to the contact surface of the needle valve shoulder formed in a spherical shape. The particles are dispersed very efficiently in the azimuth direction, and the durability against cavitation erosion is significantly improved as compared with the conventional frustoconical shape.

Therefore, even if the needle valve is used for a long period of time, it is possible to reliably prevent corrosion such that the holding shaft of the needle valve is broken.

Further, since the mutual contact surfaces of the needle valve shoulder portion and the intermediate plate that collide when the needle valve is closed are formed into a spherical shape,
A sufficient pressure receiving area can be secured without increasing the diameter of the needle valve, and as a result, damage due to wear can be significantly reduced.

Furthermore, since the needle valve shoulder is formed into a spherical shape, there is no corner portion that causes turbulence in the oil flow at this needle valve shoulder, so the oil flow is spherical. Therefore, the responsiveness of opening and closing the needle valve can be significantly improved.

〔Example〕

Hereinafter, the present invention will be described with reference to FIG. 1 only for the structure that is characteristic of the present invention, while avoiding duplication with the conventional example shown in FIGS.

A space 13 surrounded by the body 1 and the needle valve 2 is formed below the intermediate plate 4, and the needle valve shoulder 20 and the regulation surface 21 of the intermediate plate 4 with which the needle valve shoulder 20 abuts, Spherical inclined surface 25 formed in a concave shape on the intermediate plate 4 side
And a convex spherical inclined surface 24 of the needle valve shoulder 20 are formed so as to face each other so as to be in surface contact with each other when the needle valve 2 is closed. The spherical inclined surface 24 is formed so as to be smoothly and continuously connected to the outer peripheral surface of the cylindrical shaft portion of the needle valve 2.

Thus, by forming the contact surface 25 of the needle valve shoulder 20 and the contact surface 25 of the regulating surface 21 of the intermediate plate 4 into spherical shapes, respectively, the needle valve 2 is operated by the pressure of the fuel passing through the oil supply hole 10a. When the needle valve 2 suddenly descends to the fuel stopped state by the spring 5a of the spring chamber 5 from the fuel injection state in which the needle valve shoulder 20 abuts against the intermediate plate 4 and is regulated, when the needle valve 2 suddenly descends to the fuel stopped state When the impact force of cavitation generated concentrated on 7 is applied to the spherical contact surface 24 of the needle valve shoulder portion 20, this impact force is dispersed in all directions with respect to the contact surface 24. The impact force due to cavitation can be dispersed very efficiently, and breakage of the restraining shaft 6 due to cavitation erosion can be prevented.

Further, the contact surface 24 of the needle valve shoulder 20 and the contact surface 25 of the restriction surface 21 of the intermediate plate 4 which the contact surface 24 collides with when closing the needle valve 2 may be in surface contact with each other. Since it is formed in a spherical shape as described above, the pressure receiving area can be efficiently secured without increasing the diameter of the needle valve 2, and the impact force at the time of valve closing per unit area can be reduced. It is possible to suppress abrasion due to impact and prevent damage to both contact surfaces 24 and 25.

Furthermore, since the inclined surface 24 of the needle valve shoulder 20 is formed into a spherical shape, the oil smoothly flows along this spherical surface,
Generation of turbulence is suppressed. Therefore, the responsiveness of the opening / closing operation of the needle valve 2 is improved.

[Effect of device]

The fuel injection nozzle device of the present invention is provided with an intermediate plate through which the holding shaft of the needle valve penetrates, a body that contacts one surface of the intermediate plate, and a holder that contacts the other surface of the intermediate plate. A spring for urging the restraining shaft in the direction of the body is housed in the spring chamber, and the contact surface of the needle valve shoulder portion facing the intermediate plate is formed into a spherical shape so that the contact surface is in surface contact. In addition, since the contact surface of the intermediate plate facing the needle valve shoulder is formed into a spherical shape, the following effects can be obtained.

The contact surfaces of the needle valve shoulder and the contact surface of the intermediate plate facing each other are formed into spherical shapes, respectively, so that the contact surfaces of the springs are in surface contact with each other when the springs are elastically pressed, and the springs have a free length. In the stretched state, the impact force of cavitation is applied to the contact surface of the needle valve shoulder formed in a spherical shape, so this impact force is dispersed very efficiently from the contact surface subjected to the impact force in all directions. As a result, the durability against cavitation erosion is remarkably improved as compared with the conventional frustoconical shape.

Therefore, even if the needle valve is used for a long period of time, it is possible to reliably prevent corrosion such that the holding shaft of the needle valve is broken.

Further, since the mutual contact surfaces of the needle valve shoulder portion and the intermediate plate that collide when the needle valve is closed are formed into a spherical shape,
A sufficient pressure receiving area can be secured without increasing the diameter of the needle valve, and as a result, damage due to wear can be significantly reduced.

Furthermore, since the needle valve shoulder is formed into a spherical shape, there is no corner portion that causes turbulence in the oil flow at this needle valve shoulder, so the oil flow is spherical. Therefore, the responsiveness of opening and closing the needle valve can be significantly improved.

[Brief description of drawings]

FIG. 1 is a vertical cross-sectional view of a fuel injection nozzle device according to an embodiment of the present invention, FIG. 2 is a vertical cross-sectional view of a conventional fuel injection nozzle device, and FIG. 3 is a vertical cross-sectional view of a conventional fuel nozzle device. FIG. 4 is a plan view of the intermediate plate of the fuel injection nozzle device of FIG. 1 ... Body, 2 ... Needle valve, 3 ... Holder, 4
...... Intermediate plate, 5 ...... Spring chamber, 5a ...... Spring,
6 ... Holding shaft, 20 ... Needle valve shoulder, 24 ... Contact surface,
25 ... Contact surface, N ... Fuel injection nozzle device.

Claims (1)

[Scope of utility model registration request] 1. An intermediate plate (4) through which a holding shaft (6) of a needle valve (2) penetrates, and a body (1) abutting against one surface of this intermediate plate (4).
And a holder (3) that comes into contact with the other surface of the intermediate plate (4), and in the spring chamber (5) formed in the holder (3), the pressing shaft (6) is attached in the direction of the body (1). Spring (5
Needle valve shoulder that accommodates a) and faces the intermediate plate (4)
The contact surface (24) of (20) is formed in a spherical shape, and the contact surface of the intermediate plate (4) facing the needle valve shoulder (20) is formed so as to make surface contact with this contact surface (24) ( 25) A fuel injection nozzle device (N) having a spherical shape.