JPH085339Y2 - Fuel injection nozzle - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial application] The present invention relates to a fuel injection nozzle for a diesel engine.

[Prior Art] There is a type of fuel injection nozzle disclosed in Japanese Utility Model Laid-Open No. 57-8362. This fuel injection nozzle has a structure as shown in FIG.

That is, the needle valve 3 is slidably inserted in the sliding hole 2 of the nozzle body 1 in the axial direction thereof. The tip portion of the needle valve 3 is a head portion 4 having a slightly larger diameter, and the head portion 4 projects outward from the sliding hole 2. A nozzle holder 5 is connected and fixed to the base of the nozzle body 1, and a pressure chamber 6 is formed between the nozzle body 1 and the nozzle holder 5.
Fuel is pressure-fed to the pressure chamber 6 from a fuel passage 7 provided in the nozzle holder 5. The base portion 8 of the needle valve 3 is inserted into the pressure chamber 6. A base portion 8 of the needle valve 3 penetrates a sleeve 9 arranged in the pressure chamber 6, and a spring retainer 10 is externally fitted and fixed to the base end of the sleeve 9. The spring retainer 10 includes an intermediate member 11 and a pressure receiving member 12.
Are fixed, and these move together with the needle valve 3.
The needle valve 3 is biased by a nozzle spring 13 interposed between a sleeve 9 and a spring retainer 10 in a direction approaching the nozzle holder 5 (upward in the drawing). As a result, the head portion 4 of the needle valve 3 is normally seated on the tip of the nozzle body 1 and held in the closed state.
A fuel passage 14 is formed in the needle valve 3, the intermediate member 11 and the pressure receiving member 12, and an injection hole 15 provided at the tip of the needle valve 3 communicates with the fuel passage 14. The injection hole 15 is closed by the inner peripheral surface of the sliding hole 2 in the valve closed state.

In the fuel injection nozzle, when the fuel is pumped from the fuel injection pump and the fuel pressure in the pressure chamber 6 rises to the valve opening pressure, the needle valve 3 resists the elastic force of the nozzle spring 13 by the pressure of this fuel. As a result, the head portion 4 of the needle valve 3 is separated from the tip end portion of the nozzle body 1 and opened, and the injection hole 15 is slid into the sliding hole 2.
It is exposed to the outside from where fuel is injected. The maximum movement amount of the needle valve 3 is restricted by the spring retainer 10 colliding with the sleeve 9, which is the so-called lift length.

By the way, although not disclosed in the above-mentioned Japanese Utility Model Laid-Open No. 57-8362, in the structure described above, the distance between the upper end of the sleeve 9 and the lower surface of the spring retainer 10 may be reduced due to manufacturing errors and assembly errors. It is very difficult to put it out accurately, and in general, a lift length adjusting shim is inserted and arranged between the lower flange portion 16 of the sleeve 9 and the base end surface 17 of the nozzle body 1, whereby the above lift length is adjusted. It is set correctly.

In addition, in the case of this fuel injection nozzle, after mounting the shim for adjusting the lift length, a shim 18 for adjusting the valve opening pressure is mounted between the spring retainer 10 and the nozzle spring 13 and the needle valve 3 Adjusting the valve opening pressure.

[Problems to be Solved by the Invention] However, in the conventional fuel injection nozzle having the above-described configuration, two shims, that is, the lift length adjusting shim and the valve opening pressure adjusting shim 18 must be mounted, and the work is difficult. It had the drawback of being annoying.

Further, since the valve opening pressure adjusting shim 18 has a ring shape, when the shim 18 is replaced to change the valve opening pressure, the pressure receiving member 12, the intermediate member 11 and the spring retainer 10 are needled. It has to be removed from the valve 3, which is also very troublesome.

The present invention has been made in view of the problems of the above-mentioned conventional techniques, and an object thereof is to provide a fuel injection nozzle that facilitates assembly work and valve opening pressure adjustment work.

[Means for Solving the Problems] The present invention has been made in order to achieve the above-mentioned object, and its gist is that a needle valve having a fuel passage therein slides in its axial direction in a sliding hole of a nozzle body. A base portion of the needle valve is housed in a pressure chamber that is movably inserted and that is formed between the nozzle body and a nozzle holder that is connected to the base portion of the nozzle body. And is urged toward the nozzle holder side by the nozzle spring arranged outside the base of the needle valve, and when the force against the nozzle spring is applied from the fuel, the needle valve moves toward the tip side in the axial direction. In the fuel injection nozzle that changes from the valve closed state to the valve opened state, the outer circumference of the needle valve has a dimension corresponding to the lift length of the needle valve from the base end face of the nozzle body when the valve is closed. Along the circumferential direction. A groove is formed, and a stopper protruding outward in the radial direction of the needle valve is fitted and fixed in this groove. For adjusting the valve opening pressure that is substantially C-shaped in plan view between the nozzle spring and the nozzle body. In the fuel injection nozzle, the member is attached so as to sandwich the needle valve.

[Operation] When the stopper fixed to the needle valve collides with the base end surface of the nozzle body, the movement of the needle valve toward the distal end side is stopped. That is, the lift length is determined by the distance between the stopper fixed to the needle valve and the base end surface of the nozzle body when the valve is closed. The stopper is positioned by a groove provided on the needle valve, and the position of the groove on the needle valve can be extremely accurately obtained by machining. Therefore, in the case of this fuel injection nozzle, the lift length adjusting member which has been conventionally required becomes unnecessary.

Further, since the valve opening pressure adjusting member has a substantially C shape in a plan view, when replacing the valve opening pressure adjusting member, the nozzle spring is compressed in the direction away from the nozzle body, If the space between the body and the base end surface is widened, this can be easily removed by pulling out the mounted valve opening pressure adjustment member to the outside in the radial direction, and another valve opening pressure adjustment The member can be easily inserted and mounted.

[Embodiment] An embodiment of the present invention will be described below with reference to the drawings from FIG. 1 to FIG.

FIG. 1 is a vertical sectional view of the fuel injection nozzle 20, and FIG. 2 is an enlarged sectional view of a main part thereof. A nozzle holder 22 is screwed and fixed to a base end portion of a nozzle body 21 of the fuel injection nozzle 20, and a pressure chamber 23 is formed inside thereof by being surrounded by them. A fuel passage 24 is formed in the nozzle holder 22 and communicates with the pressure chamber 23. The fuel pressure-fed from a fuel injection pump (not shown) passes through the fuel passage 24 and the pressure chamber 23.
Is being led to.

On the other hand, the nozzle body 21 is formed with a sliding hole 26 penetrating from the base end surface 25 to the tip. Needle valve 27 in this sliding hole 26
Is slidably inserted in the axial direction. Needle valve 27
Is composed of a rod portion 28 and a head portion 29 formed at the lower end of the rod portion 28, the head portion 29 is projected outward from the sliding hole 26, and the upper portion of the rod portion 28 is pressure chamber 23. It is projected inside. The head portion 29 has a larger diameter than the rod portion 28, and the sealing portion 30 at the tip of the nozzle body 21 when the valve is closed.
Is supposed to sit down. Further, the needle valve 27 is formed with a fuel passage 31 extending downward from the upper end surface of the rod portion 28 along the axial direction, and a plurality of injection holes 32 provided in the lower portion of the rod portion 28 are formed in the fuel passage 31. It is connected to the fuel passage 31. The injection hole 32 is closed by the inner peripheral surface of the sliding hole 26 in the valve closed state. And the needle valve 27 is the first
When the injection hole 32 moves downward from the state shown in the figure and is exposed outward from the sliding hole 26, the fuel in the pressure chamber 23 passes through the fuel passage 31 and is injected from the injection hole 32. . The needle valve 27
Since the head part 29 has a larger diameter than the rod part 28,
When inserting the needle valve 27 into the sliding hole 26, the rod portion 28 is inserted from the tip end side of the nozzle body 21 toward the base end side.

Further, as shown in FIG. 2, the outer peripheral surface of the rod portion 28 of the needle valve 27 is separated from the base end surface 25 of the nozzle body 21 by the lift length L dimension to the upper side of the rod portion 28 when the valve is closed. A groove 33 is formed at the position over the entire circumference in the circumferential direction. Further, a sleeve 34 is fitted on the outside of the portion of the rod portion 28 inserted into the pressure chamber 23. FIG. 3 is an external perspective view of the sleeve 34. The sleeve 34 is composed of a bottom plate portion (stopper) 35 and a standing wall portion 36. Both the bottom plate portion 35 and the standing wall portion 36 are substantially C-shaped in plan view,
The bottom surface of the bottom plate portion 35 is a flat surface. And the bottom plate part
The width dimension of the U-shaped recess 37 in 35 is the rod portion of the needle valve 27.
The outer diameter of the groove 33 in the groove 28 is slightly larger than that of the groove 33.
It is made slightly larger than the outer diameter dimension of the rod portion 28 excluding. Further, the thickness dimension of the bottom plate portion 35 is equal to or slightly smaller than the height dimension of the groove 33 of the rod portion 28. This sleeve 34
Is the one that is fitted into the needle valve 27 from the outside in the radial direction of the rod portion 28, in which case the bottom plate portion 35 is fitted in the groove 33 of the rod portion 28, and the standing wall portion 36 is larger than the groove 33. It is fitted on the outside of the rod portion 28 located above. At this time, the bottom plate 35
The outer peripheral portion of the bulge protrudes radially outward from the rod portion 28.

On the outer surface of the sleeve 34 and on the base end surface 25 of the nozzle body 21, a ring-shaped spacer 39 is placed. The inner diameter of the spacer 39 is slightly larger than the outer diameter of the sleeve 34, and the sleeve 34 is slidably inserted therein.

A hollow cylindrical spring case 40 is arranged outside the sleeve 34 and above the spacer 39. A hole is provided in the bottom plate portion 41 of the spring case 40, and the sleeve 34 is slidably inserted into the hole.
In addition, a plurality of holes 43 are formed in the upper portion of the tubular portion 42 of the spring case 40.
Are formed. The function of this hole 43 will be described in detail later.

Further, a ring-shaped spring retainer 44 is arranged outside the sleeve 34 and above the spring case 40, and the spring retainer 44 is retained by a snap ring 45 mounted on the outer peripheral surface of the upper portion of the sleeve 34. ing.

Inside the spring case 40 is a nozzle spring.
46 are housed. The nozzle spring 46 has one end abutted against the bottom plate portion 41 of the spring case 40 and the other end abutted against the spring retainer 44, thereby urging the needle valve 27 upward in the drawing.

The spacer 39, the spring case 40, the nozzle spring 46, and the spring retainer 44 are inserted into the sleeve 34 to which the rod portion 28 is fitted from above in this order in FIG. 1, and then the snap ring 45 is inserted. It is installed.

Further, the spacer 39 and the bottom plate portion 41 of the spring case 40 are
A valve-opening pressure adjusting shim (valve-opening pressure adjusting member) 47 is sandwiched between and. The valve opening pressure adjusting shim 47 has a substantially C-shaped cross section as shown in FIG. 5, and the width dimension of the U-shaped recess 48 is slightly larger than the outer diameter of the standing wall portion 36 of the sleeve 34. The valve opening pressure adjusting shim 47 is prepared in various thicknesses, and the valve opening pressure of the needle valve 27 can be set to a desired value by changing the thickness. The valve opening pressure adjusting shim 47 is fitted into the sleeve 34 from the outside in the radial direction. To install and remove the valve opening pressure adjusting shim 47, insert a predetermined jig into the hole 43 of the spring case 40, and move the spring case 40 upward against the needle valve 27 against the elastic force of the nozzle spring 46. By moving the spacer 39 and the spring case 40 relatively.
Then, the valve opening pressure adjusting shim 47 can be moved in the radial direction. Therefore, the spring case 40,
The valve opening pressure adjusting shim 47 can be easily attached and removed without removing the nozzle spring 46, the spring retainer 44, and the snap ring 45.

With the valve opening pressure adjusting shim 47 attached, the distance between the upper end of the cylindrical portion 42 of the spring case 40 and the bottom surface of the spring retainer 44 when the valve is closed is determined by the lift length L.
Has been made larger than.

In the fuel injection nozzle 20 configured as described above, fuel is pumped from the fuel injection pump (not shown) to the pressure chamber 23,
When the fuel pressure in 23 rises to the valve opening pressure, the needle valve 27 is moved downward in the figure against the elastic force of the nozzle spring 46 by the fuel pressure, and the valve is opened. Then, when the bottom plate portion 35 of the sleeve 34 hits the base end surface 25 of the nozzle body 21, the downward movement of the needle valve 27 is stopped. At this time, the spring retainer 44 does not collide with the upper end of the spring case 40.

In this fuel injection nozzle 20, the lift length L of the needle valve 27 is set very accurately without using the conventionally required lift length adjusting shim. This is because in this fuel injection nozzle 20, the distance between the bottom surface of the bottom plate portion 35 of the sleeve 34 and the base end surface 25 of the nozzle body 21 is the lift length L, and the seat portion 30 of the nozzle body 21 extends from the base end surface. This is because the dimension up to 25 and the dimension from the contact point of the needle valve 27 with respect to the seat portion 30 to the groove 33 into which the bottom plate portion 35 is fitted can be obtained extremely accurately by machining. Therefore, a lift adjusting shim is not required.

Further, in the fuel injection nozzle 20, as described above, the spring retainer 44 has the spring case even when the valve is fully opened.
The bottom plate portion 35 of the sleeve 34 receives the impact force generated at the time of maximum valve opening without colliding with 40. Therefore, this impact force is hardly transmitted to the snap ring 45, or even if it is transmitted, it is divided and transmitted as a very small force. As a result, the snap ring 45 is not damaged by the impact. If the snap ring 45 is damaged, the spring retainer 44 will come off and the needle valve 27 will not operate, or even if it does not reach that point, debris generated by the damage of the snap ring 45 will pass through the fuel passage 31 of the needle valve 27. There is a risk of reaching the injection hole 32 and blocking the injection hole 32 to hinder the fuel injection. Such an accident does not occur in the fuel injection nozzle 20.

This invention is not limited to the above-mentioned embodiment, and various modes can be adopted.

[Advantages of the Invention] As described above, according to the present invention, the lift length adjusting member conventionally required in the fuel injection nozzle is not required, and the valve opening pressure can be easily adjusted. The excellent effect of becoming

[Brief description of drawings]

The drawings from FIG. 1 to FIG. 5 show one embodiment of the present invention. FIG. 1 is a vertical sectional view of a fuel injection nozzle, FIG. 2 is an enlarged vertical sectional view of the same part, and FIG. Is a perspective view of the outer appearance of the sleeve, FIG. 4 is a sectional view taken along the line IV-IV in FIG. 1, and FIG.
It is a -V sectional view. FIG. 6 is a vertical sectional view of a conventional fuel injection nozzle. 20 ... Fuel injection nozzle, 21 ... Nozzle body, 22 ... Nozzle holder, 23 ... Pressure chamber, 25 ... Base end surface, 26 ... Sliding hole, 27 ... Needle valve, 31 ... Fuel passage, 33 ... Groove, 34 ... Sleeve, 35 ... Bottom plate (stopper), 46 ... Nozzle spring, 47 ... Shim for valve opening pressure adjustment (member for valve opening pressure adjustment).

Claims (1)

[Scope of utility model registration request] 1. A needle valve having a fuel passage therein is slidably inserted in a sliding hole of a nozzle body in an axial direction thereof, and is formed between a nozzle body and a nozzle holder connected to a base portion thereof. The base portion of the needle valve is housed in the pressure chamber that is provided, and the needle valve is biased toward the nozzle holder by a nozzle spring that is arranged between the needle valve and the nozzle body and outside the base portion of the needle valve. In the fuel injection nozzle that moves from the closed state to the opened state when the needle valve moves toward the tip side in the axial direction when a force against the nozzle spring is applied from the fuel, the outer surface of the needle valve is , A groove is formed along the circumferential direction that is spaced from the base end surface of the nozzle body in the closed state to the nozzle holder side by a dimension corresponding to the lift length of the needle valve, and this groove has a radial direction that is larger than that of the needle valve. The stopper protruding outward is fixed and fitted. Between the nozzle spring and the nozzle body,
A fuel injection nozzle, wherein a valve opening pressure adjusting member having a substantially C shape in a plan view is attached so as to sandwich a needle valve.