JPS6259229B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION In the present invention, two springs press the needle valve of the injection nozzle in the closing direction, the first spring controls the needle valve lift during initial injection, and the second spring presses the needle valve of the injection nozzle in the closing direction. The present invention relates to a fuel injection valve having a structure that controls the total lift of the needle valve during injection.

In diesel engines, various attempts have been made to improve combustion characteristics, particularly to reduce noise and exhaust product generation, by lowering the initial injection rate and reducing the amount of fuel injected during the ignition delay period. . For example, the injection valve known in Utility Model Publication No. 54-3224 uses two springs, and at the time of initial injection, the lift of the needle valve is reduced to reduce the fuel passage area within the nozzle, thereby reducing the injection rate. The configuration maximizes the lift of the needle valve during injection.

The valve opening pressure caused by the first spring that regulates the nozzle opening pressure can be measured using a conventionally well-known hand tester, but the valve opening pressure caused by the second spring cannot be measured using a hand tester. Impossible,
This must be measured while fuel is being injected, and in practice it is impossible to adjust the valve opening pressure while measuring the injection pressure of all injection valves on the engine stand. In addition, the set load and set dimensions of the second spring inevitably vary due to manufacturing, so it is difficult to keep the secondary lift pressure of the needle valve by the second spring of all nozzles of a multi-cylinder engine constant. It's impossible. Furthermore, since the inertial weight of moving parts such as springs is large, the closing speed of the needle valve is slow, which causes smoke to deteriorate.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide an injection valve in which the valve opening pressure of the second spring can be measured using a hand tester.

The present invention will be described below with reference to embodiments shown in the drawings.

In FIG. 1, an injection nozzle (a hole nozzle in this embodiment) 2 is attached to the end surface 1a of the nozzle holder 1 with a retaining nut 4, and when the needle valve 5 is lifted, its shoulder comes into contact with the end surface 1a, so that the injection nozzle 2 is fixed to a predetermined position. is limited to the maximum lift amount _h2 . This needle valve 5
The tip of the push rod 6 is connected to one end of the first push rod 6, the other end of the push rod 6 receives one end of a first spring 7, and the other end of the first spring 7 is connected to a first end screwed into the nozzle holder 1. The capsule 9 is pressed by the end 9a of the first capsule 9. The hole 10a of the second capsule 10 screwed into the first capsule 9 and the first capsule 9
a second push rod 8 that is slidable in the axial direction within the hole 9b;
The lower end 8a faces the end 6a of the first push rod 6, and the collar 8b formed at the upper end is located inside the second capsule 10. A second spring 11 is installed between this collar portion 8b and a spring receiving nut 12 screwed into the second capsule 10. End 6a of first push rod 6 and end 8a of second push rod 8
The distance between the pilot lifts _h1, ie, the pilot lift h1, is smaller than the maximum lift _h2 of the nozzle needle valve 5, and the valve seat opening area at this pilot lift _h1 is required to be smaller than the total area of the nozzle orifices. Therefore, when the needle valve 5 rises by _h1 due to the pressure inside the injection pipe system, the first push rod 6
and receives the force of the second spring 11 acting through the second push rod 8. Locknut 13, 14,
16 are nuts for fixing the spring receiving nut 12, the second capsule 10, and the first capsule 9, respectively. 15 is the oil-tight gasket 3 is the nozzle holder 1
It is connected to the discharge side of a fuel injection pump (not shown) through a fuel passage inside. 3a is a fuel passage in the injection nozzle 2, 9c, 10b, 12a, 13a, 14
A indicates a groove in which a driver or the like is engaged.

Next, a method of adjusting the needle valve secondary lift pressure of the second spring 11 of the injection valve will be explained. First, attach the second spring 11 to the spring retainer nut 12.
Press it harder and add the second capsule 10
The first push rod 6 and the second push rod 8 are brought into contact with each other, and the valve opening pressure is measured using a conventionally known hand tester, and the spring receiver nuts 12 are sequentially loosened to set the valve opening pressure Po ₂ to a predetermined value. . At this time, the first capsule 9 is loosened so that the load of the first spring 7 is not applied to the needle valve 5. If the valve opening pressure Po ₂ of the second spring 11 is set by the above method, the valve opening pressure Po ₂ =Fs/{π/4(Dn ² −Ds ² )}, and the needle valve secondary lift pressure P ₂ = Fs/(π/4Dn ² ), so the secondary lift pressure P ₂ is P ₂ = Po ₂ (Dn ² −
Ds ² )/Dn ² . Here, Fs is the set load of the second spring 11, Dn is the needle valve shaft diameter, Ds
is the needle valve seat diameter. Once the secondary lift pressure _P2 has been set, the spring receiver nut 12 is fixed with the lock nut 13.

Next, in order to set the valve opening pressure Po ₁ of the first spring 7, the second capsule 10 is loosened, a sufficient distance is left between the first push rod 6 and the second push rod 8, and the first capsule 9 is opened. is screwed in and adjusted using a hand tester using a conventionally known method. Next, the second capsule 10 is screwed in until the first push rod 6 and the second push rod 8 come into contact, and then the distance h ₁ between the first push rod 6 and the second push rod 8 becomes a predetermined value. Unscrew the second capsule 10. And Locknut 14
The second capsule 10 is fixed with the lock nut 16, and the first capsule 9 is further fixed with the lock nut 16.

Since the operation of this injection valve is the same as that of the conventional one, the explanation will be omitted, and the characteristics will be explained with reference to FIG. In Fig. 2, the horizontal axis shows the elapsed injection period, and the vertical axis shows the injection pipe internal pressure, needle valve lift, and injection rate. It shows. As is clear from this figure, in the conventional model, the inertial mass of the moving part is large, so the injection cutoff (the closing speed of the needle valve) is gradual, but in the present invention, the inertial mass of the moving part is kept small. This improves injection cutoff (needle valve closing speed) and suppresses smoke emissions. Further, the seating noise of the needle valve 5 can be reduced.

Note that the second spring 11 may be a disc-shaped leaf spring.

As is clear from the above description, according to the present invention, it is possible to measure the secondary lift pressure of the needle valve caused by the second spring with a hand tester, so the advantage is that it can be adjusted very easily. You can get the same effect. Furthermore, it can be implemented simply by replacing the nozzle holder in an injection valve that employs a small inertia nozzle.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view showing one embodiment of the present invention, and FIG.
The figure is a diagram showing characteristics of an injection valve according to the present invention and a conventional injection valve. DESCRIPTION OF SYMBOLS 1... Nozzle holder, 2... Injection nozzle, 5... Nozzle needle valve, 6... First push rod, 7... First spring, 8... Second push rod, 8b... Flange, 9... First capsule, 10 ...Second capsule, 11...Second spring, 12...Spring receiver nut.

Claims (1)

[Claims] 1 Consisting of a nozzle holder and an injection nozzle, between a first push rod joined to the end of the nozzle needle valve and a first capsule screwed into the nozzle holder so that the set position in the central axis direction can be adjusted. In the fuel injection valve in which the nozzle needle valve is biased by providing a first spring, a second capsule is screwed into the first capsule so that the setting position in the central axis direction can be adjusted; a second push rod that is slidable with respect to both capsules, one end of which faces the first push rod, and a flange provided at the other end that is located within the second capsule; a spring receiving nut which is screwed to adjust the setting position in the central axis direction; and a spring receiving nut provided in the second capsule, with one end abutting the flange and the other end abutting the spring receiving nut, a second spring that biases the second push rod toward the first push rod.