JPS6040854Y2 - Fuel injection nozzle holder device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improvement of a holder device for a fuel injection nozzle of an internal combustion engine.

Fuel injection nozzles use springs to resiliently hold the nozzle needle in its closed position so that the injection hole does not open until the fuel supply pressure reaches a predetermined value.

Generally, this spring is a helical compression spring and must have a large spring force because the fuel supply pressure is quite high.

Therefore, even if it is desired to downsize the nozzle unit, there is a limit to the dimensions of the helical compression spring that can achieve the specified performance.
This was an obstacle to miniaturization.

In order to solve this problem, a structure using leaf springs was proposed.

For example, in the structure disclosed in Japanese Patent Publication No. 52-640, a vertically curved leaf spring is arranged in a long and narrow chamber formed in the nozzle center axis direction in the nozzle holder body. It extends in the length direction and engages the nozzle needle at one end and the nozzle holder fixing part at the other end.

The ends of the leaf springs are rounded and placed in recesses provided in the corresponding elements.

Since the spring force of the vertically curved leaf spring is utilized, the center axis of the chamber of the nozzle holder body that accommodates the leaf spring does not coincide with the nozzle center axis, that is, the center axis of the nozzle holder body.

Therefore, in addition to the complicated processing of leaf springs,
Machining of the nozzle holder main body and the components that receive the spring ends is also complicated, resulting in high costs.

Moreover, due to its structure, it is inevitable that the holder body will be long, that is, high.

An object of the present invention is to provide a fuel injection nozzle holder device that is simple in structure and inexpensive, using a straight and simple leaf spring.

According to the present invention, a straight plate spring is supported and disposed in a cantilevered manner so as to extend in a direction perpendicular to the longitudinal central axis of the nozzle holder body, which coincides with the nozzle central axis.

The nozzle needle is elastically pressed in the valve-closing direction by utilizing the deflection of this straight leaf spring supported cantilevered in the right angle direction. There is no need to give any special processing to the end of the leaf spring.

Moreover, since the chamber for accommodating the leaf spring only needs to be provided in a direction perpendicular to the longitudinal central axis of the nozzle holder main body, machining is easy and costs can be reduced.

Furthermore, by arranging the leaf springs laterally, the height of the nozzle holder can be reduced.

This is particularly advantageous for small internal combustion engines where installation space is limited.

Hereinafter, the present invention will be described by way of examples with reference to the accompanying drawings.

Referring to FIG. 1, a nozzle holder body 1 has a nozzle 3 attached to its lower end with a retaining nut 4. As shown in FIG.

The nozzle 3 has a conventionally known structure consisting of a main body 3a and a needle 3b.

The lower end surface 2 of the nozzle holder main body 1 has a nozzle needle 3b.
Acts as a stopper that determines the amount of lift.

A portion of the needle 3b protrudes into a narrow vertical hole 5 provided in the nozzle holder body 1 so as to coincide with its longitudinal central axis.

Above the needle 3b, a pin 6 is slidably inserted into the same longitudinal hole 5, the lower end of which engages the top end surface of the needle 3b.

A spring chamber 7 (preferably circular cross section) is provided at the end of the nozzle holder main body 1 opposite to the nozzle mounting end in a direction perpendicular to the nozzle center axis and therefore the longitudinal center axis of the nozzle holder. A vertical hole 5 communicates with this spring chamber 7, and the top end of the pin 6 projects into the spring chamber 7 by a predetermined amount.

A straight leaf spring 9 is installed in the spring chamber 7.
This leaf spring extends in the longitudinal direction of the spring chamber 7, that is, in a direction perpendicular to the longitudinal central axis of the nozzle holder body 1.

One end of the leaf spring 9 is fixed to the fixed bush 8, and the leaf spring 9 is supported in a cantilevered manner.

The top end 6a of the pin 6 is adapted to engage with the lower surface 9a of the leaf spring 9.

The fixed bushing 8 is press-fitted into the inner diameter of the spring chamber 7.

At the free end of the leaf spring 9, a bolt 10 is attached to its upper surface 9b.
This bolt 10 is threaded into a screw hole provided in the nozzle holder body 1, and can be locked in a predetermined position with a lock nut 11.

The engagement point of the bolt 10 with the leaf spring 9 is the point at which the bolt 10 engages with the leaf spring 9 of the pin 6.
The distance between the engagement point of the bolt 10 and the pin 6 with the leaf spring 9 is on the opposite side of the fixing point of the leaf spring 9, with the engagement point of the bolt 10 and the pin 6 as the center, and the distance between the engagement point of the bolt 10 and the pin 6 with the leaf spring 9 Although it is preferable that the distance be the same as that of , it may be changed as necessary.

Therefore, when the bolt 10 is screwed inward, the leaf spring 9
When the bolt 10 is retracted outward, the load applied to the pin 6 by the leaf spring 9 decreases.

Since the load of the leaf spring 9 is transmitted to the needle 3b via the pin 6, the opening pressure of the nozzle 3 can be set by changing the axial position of the bolt 10.

In addition, the reference numeral 14 indicates a hole through which leaked fuel from the nozzle 3 is discharged from the spring chamber 7, and the reference numeral 12.13 indicates a passage that guides fuel pressure-fed from a fuel injection pump (not shown) to the nozzle 3. It shows.

In the illustrated embodiment, the leaf spring 9 is connected to the needle 3 via the pin 6.
Although the force is transmitted to the needle 3b, it goes without saying that the leaf spring 9 and the needle 3b may be directly engaged with each other.

In operation, fuel pumped from an injection pump, not shown, enters the nozzle 3 through the passage 12.13.

When the fuel pressure inside the nozzle 3 becomes higher than the nozzle opening pressure determined by the additional load of the leaf spring 9 on the needle 3b,
The needle 3b is raised a certain distance in its axial direction, and fuel is ejected from the nozzle hole (not shown) of the nozzle 3.

At this time, the leaf spring 9 is connected to the needle 3 via the pin 6.
It is bent upward by the amount of rise b.

When the fuel pressure in the nozzle 3 falls to the nozzle closing pressure determined by the additional load of the leaf spring 9, the needle 3b descends and closes the nozzle injection hole.

FIG. 2 shows a modification of the present invention, which differs only slightly in the method of adjusting the spring force, so the same components as in FIG. 1 are given the same reference numerals.

In the embodiment of FIG. 2, a leaf spring 17 is cantilevered by a bush 15 slidably mounted in the spring chamber 7, and the leaf spring 17 has a slope on at least one side thereof (the lower side in the case shown). This sloped surface is pin 6.
It is adapted to engage with the top end 6a of.

A bolt 16 screwed into a screw hole provided in the nozzle holder body 1 and communicating with the spring chamber 7 is engaged with the opposite end of the bush 15. By moving this bolt 16 in and out, the leaf spring can be removed. 17 in the axial direction of the spring chamber 7 can be changed, and the engagement position of the pin 6 with the plate spring 17 can be changed to change the spring force applied to the pin 6.

The bolt 16 is locked in place by a lock nut 19.

In addition, in order to prevent the bushing 15 from rotating in the spring chamber 7, a pin 18 is press-fitted into a small hole in the nozzle holder body 1.
Its tip fits into a groove 20 provided in the outer peripheral surface of the bushing 15 in the axial direction.

According to the present invention, as is clear from the above description, a straight plate spring is supported in a cantilevered manner so as to extend in a direction perpendicular to the longitudinal central axis of the nozzle holder body, which coincides with the nozzle central axis. and place it.

The nozzle needle is elastically pressed in the valve closing direction by utilizing the flexure of the straight shape supported cantilevered in the right angle direction. There is no need to specially process the end of the spring.

Furthermore, since the chamber that accommodates the straight-shaped leaf spring only needs to be provided in the direction perpendicular to the longitudinal center axis of the nozzle holder body, processing is easy and a nozzle holder device with a simple structure can be obtained. , it is possible to reduce manufacturing costs.

In addition, by arranging straight leaf springs laterally, the height of the nozzle holder can be reduced, which is particularly advantageous for small internal combustion engines where installation space is limited, and is used for passenger cars. In some cases, the height of the bonnet can be lowered.

In addition, since the straight leaf spring is supported in a cantilevered manner in a direction perpendicular to the longitudinal axis of the nozzle needle, the threaded member can be brought into contact with the free end of the leaf spring, and the leaf spring can be At least one side of the leaf spring can be sloped, and the leaf spring can be moved in the longitudinal direction of the leaf spring by a screw member, so that even after the nozzle holder device is assembled, the fuel injection nozzle cannot be opened. This provides an excellent effect in that the valve pressure can be adjusted and set reliably and easily.

[Brief explanation of the drawing]

FIG. 1 is a vertical cross-sectional view showing a fuel injection nozzle holder device according to the present invention, and FIG. 2 is a first cross-sectional view showing another embodiment of the present invention.
It is a figure similar to the figure. 1... Nozzle holder body, 3... Nozzle, 4... Holding nut, 6... Zen, 7
...Spring chamber, 8...Bush, 9...
...Plate spring, 10...Bolt forming a threaded member, 11...Lock nut.

Claims (3)

[Scope of utility model registration request] (1) In a fuel injection nozzle holder device having a spring device that holds the fuel injection nozzle in an operable state and presses the nozzle needle in the valve-closing direction, the spring device has a straight plate spring aligned with the longitudinal axis of the nozzle needle. A holder device for a fuel injection nozzle, characterized in that the holder device is disposed in a cantilevered manner in a direction perpendicular to the fuel injection nozzle. (2) By bringing a screw member movable in the direction of deflection of the leaf spring into contact with the free end of the leaf spring, the opening pressure of the fuel injection nozzle can be variably set by adjusting the screw member. A holder device for a fuel injection nozzle according to claim 1 of the registered utility model claim. (3) The fuel injection nozzle is constructed by using a leaf spring having a slope on at least one side, and adjusting the installation position of the leaf spring in the longitudinal direction of the leaf spring using a screw member movable in the longitudinal direction of the leaf spring. A holder device for a fuel injection nozzle according to claim 1, which is capable of variably setting the valve opening pressure of the fuel injection nozzle.