JPH0417768A - Bar filter for fuel injection valve - Google Patents

Abstract

PURPOSE:To make an excessive fuel flow hardly occur, and reduce a fuel pressure loss by providing at least one end of a bar filter body with a sectional area reduction section gradually becoming smaller toward the end of a bar filter. CONSTITUTION:A fuel passage area cellularized with the internal surface of a fuel passage and the external surface of a bar filter body 16 is gradually reduced from an upstream side to a downstream side with a cross section reduction section 28 at the downstream end of a bar filter 15. The aforesaid area is also gradually enlarged from the upstream side to the downstream side with a cross section reduction section 29 at the downstream end of the bar filter 15. A fuel pressure loss can be reduced by gradually changing the cross sectional area of the fuel passage at the upstream and downstream sides of the bar filter 15. Also, a foreign material in fuel can be removed in a gap between the small bore section of the bar filter 15 and the inner surface of the fuel passage at the intermediate section of the bar filter 15.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention relates to a bar filter for fuel injection valves.
Specifically, the invention relates to an improvement in a bar filter that prevents foreign matter in fuel from entering a nozzle.

(Prior art) Conventionally, many fuel injection valves for diesel engines have been used.
If foreign matter contained in the fuel enters the nozzle, it may cause a malfunction or a drop in performance, so a bar filter is installed near the fuel supply port to prevent such problems from occurring. -1104, etc.).

A conventional bar filter, for example, as shown in FIG.
A bar filter 3 is fixed in the fuel passage 2 formed in the fuel injection valve main body 1 with a press-fitted part 4. A first fuel guide groove 5 to a second fuel guide groove 6 are formed on the outer periphery of the bar filter 3. When fuel flows in the direction of the arrow, foreign matter in the fuel is collected in the gap between the small diameter outer circumference of the bar filter and the inner wall surface of the fuel passage.

(Problem to be Solved by the Invention) However, with such conventional bar filters for fuel injection valves, there is a sudden change in the area of the fuel passages before and after both ends of the bar filter, which causes vortices in the fuel flow. occurs,
There is a problem of increased energy loss.

For example, as shown in FIG. 11, the cross-sectional area of the fuel passage suddenly narrows at the end face 8 on the pump side of the bar filter 3, and the cross-sectional area of the fuel passage suddenly changes so that the fuel passage suddenly expands at the end face 9 on the nozzle side. This poses a problem in that energy loss during pumping of fuel becomes excessive.

The present invention was made to solve these problems, and reduces the energy loss of the fuel flow while maintaining the ability to remove foreign substances from the fuel at the same level or higher than that of conventional systems. The purpose of the present invention is to provide a bar filter for fuel injection valves.

(Means for Solving the Problems) For this purpose, the bar filter for a fuel injection valve of the present invention is a bar filter that can be attached to a fuel passage formed in a fuel injection valve body, a press-fitting part; a small-diameter part formed in the bar filter body and having an outer diameter smaller than that of the press-fitting part; and a plurality of first holes extending in the axial direction from the filter end on the outer circumferential wall surface of the small-diameter part and not penetrating the other end of the filter.
a fuel guide groove; a second fuel guide groove that extends in the axial direction from between the first fuel guide groove and the adjacent first fuel guide groove to the other end of the filter and does not penetrate the filter end;
The bar filter main body is characterized in that it includes a reduced cross-sectional area portion formed at at least one end of the bar filter body and whose cross-sectional area becomes gradually smaller toward the tip.

(Function) According to the bar filter of the present invention, the cross-sectional area of the fuel passage defined by the inner wall surface of the fuel passage and the outer peripheral wall surface of the bar filter main body is gradually reduced from the upstream side to the downstream side at the upstream end of the bar filter. At the downstream end of the bar filter, it is gradually expanded from the upstream side to the downstream side. Therefore, the cross-sectional area of the fuel flow path changes gently before and after the bar filter, so the pressure loss of the fuel is reduced. Further, in the middle part of the bar filter, foreign matter in the fuel is removed in the gap between the small diameter part and the inner wall surface of the fuel passage.

(Example) Embodiments of the present invention will be described below based on the drawings.

1 to 5 show a bar filter for a fuel injection valve according to a first embodiment of the present invention.

As shown in FIG. 4, the fuel injection valve lO installed in a diesel engine is composed of a holder body 11, a retaining nut 12, and a nozzle 13. A passage 2 is opened, and a bar filter 15 is press-fitted into the fuel passage 2.

The bar filter 15 has a large diameter cylindrical press fit part 17 having the maximum outer diameter of the main body at one end of the bar filter main body 16.
is formed. The outer peripheral wall surface of this press-fitting portion 17 becomes a press-fitting contact surface when inserted into a fuel passage 2, which will be described later. The downstream side of the press-fitting part 17 is a small-diameter part 18 having a smaller diameter than the press-fitting part, and the gap δ formed between this small-diameter outer peripheral part 18 and the fuel passage inner wall surface 2a shown in FIG. 5 performs a filter function. .

As shown in FIG. 2, three first fuel guides 420, 21, 22 are formed from the end of the bar filter main body 16 on the pump side and extend in the axial direction of the bar filter at positions 120 degrees apart from each other. The terminal end of the first tPN material guide groove is provided so as not to penetrate the other end of the bar filter 15 on the nozzle side. From the nozzle side end of the bar filter main body 16, the first fuel guide/! Three second fuel guides at positions shifted by 60 degrees from the positions of I20.21.22/#! 2
3, 24, 25 are formed extending in the axial direction, and these second fuel guide grooves 23, 24, 25 are formed non-penetratingly at the end on the pump side. The first fuel guide grooves 20.21.22 and the second fuel guide grooves 23.24.25 overlap in the axial direction in the middle, as shown in FIG. Beyond the small diameter portions 18a and 18b, respectively, they communicate with the second fuel guide groove 23.

At the end of the bar filter 15 on the pump side, a first protrusion 28 having a streamlined shape whose cross-sectional area gradually decreases toward the tip.
is formed. The first protrusion 28 has a streamlined outer circumferential surface that gradually curves gradually toward the downstream in the axial direction. A flat surface 28a is formed at the tip of the first protrusion 28 as a portion to which a load is applied during press-fitting.

A second protrusion 2 is provided at the nozzle side end of the bar filter main body 16.
9 is formed. The second protrusion 29 is the first protrusion 28
Similarly, it is formed into a streamlined shape so that the cross-sectional area decreases toward the tip.

The first protrusion 28 or the second protrusion 29 is finished, for example, by cutting a cylindrical material using a lathe. After that, the first fuel guide groove 20.21.22 and the second fuel guide groove 2
3.24.25 are formed by groove processing.

Next, the flow of fuel will be explained based on FIG. 5.

Fuel flowing into the bar filter 15 through the fuel passage 2 passes through the first fuel guides 42o and 21.22, passes through the gap δ formed between the fuel passage inner wall surface 2a and the small diameter portion 18, and passes through the gap δ shown in FIG. The fuel flows in the direction of the arrow, and the second fuel guide reaches 23.
It flows in at 24.25. At this time, the foreign matter in the fuel is in the gap δ
Since it cannot pass through the first fuel guide groove 20.2.
1.22 and foreign matter is removed from the fuel. The fuel from which foreign matter has been removed is transferred to the second fuel guide groove 23.24.2.
5, and is force-fed to the fuel passage 2 on the nozzle side through the periphery of the second protrusion 29.

The fuel flowing into the bar filter 15 enters the first fuel guide grooves 2o, 21.22 through the fuel flow path formed between the first protrusion 28 and the inner wall surface 2a of the fuel passage. The fuel flow path is gently narrowed around the portion 28. Second
The fuel flowing through the fuel guide 23, 24, 25 flows around the second protrusion 29 and flows out from the bar filter 15, but the cross-sectional area of the fuel flow path is the same as the outer circumferential surface of the second protrusion 29 and the inner circumferential wall surface of the fuel passage. The fuel flow path surrounded by 2a gradually widens toward the downstream side. This suppresses vortex generation within the fuel flow and reduces pressure loss in the fuel flow.

Next, the energy loss between the first embodiment of the present invention and the conventional example will be compared based on FIG.

It has been found that, assuming that the pressure loss of the bar filter according to the conventional example is 100, the pressure loss of the bar filter according to the first embodiment of the present invention is reduced to about one-fifth of that of the conventional example. To explain this in detail, first, at the end of the bar filter on the pump side, in the conventional example, the cross-sectional area of the fuel passage is rapidly reduced, so the inlet loss C becomes a large value, and then when passing through the first fuel guide groove, the loss C gradually decreases. Pressure loss gradually increases,
The loss increases more slowly at the confluence of the first fuel guide groove and the second fuel guide groove. Next, when the first fuel guide groove ends and only the second fuel guide groove is left, the rate of increase in pressure loss increases slightly, and the outlet loss rapidly increases at the nozzle side end. On the other hand, in the first embodiment of the present invention, the inlet loss and the outlet loss are considerably small, and as a result,
In the first embodiment, the overall pressure loss is reduced by about 80% compared to the conventional example.

The effect of "fuel passage area" on fuel injection characteristics is that as the fuel passage area becomes smaller, the flow velocity of the fuel increases, so friction loss occurring between the fuel passage wall surface and the fuel flow increases, and the injection pressure decreases. In addition, the effect on fuel injection characteristics is
The effect of "change in fuel passage cross-sectional area" is that when the fuel passage cross-sectional area suddenly changes, vortices are likely to occur in the flow of fuel, increasing pressure loss and thus lowering the injection pressure. This is clear from the fact that in the conventional example, the loss at the inlet and the loss at the outlet are extremely large, as shown in FIG. 6. In the first embodiment, since the cross-sectional area of the fuel passage is gradually changed between the inlet and the outlet, the energy loss is significantly reduced, and the energy loss of the bar filter as a whole can be reduced. Ta.

7 to 10 show a bar filter for a fuel injection valve according to a second embodiment of the present invention. In this case, the means for gradually changing the fuel flow path is to change the cross-sectional area of the fuel flow path by gradually shallowing or deepening the groove depth by using a groove instead of the protrusion in the first embodiment. This is what I did.

A first inclined fuel guide groove 3o whose cross-sectional area gradually decreases toward the tip of the bar filter main body 16 on the pump side.
, 31, 32 are formed, and the downstream portions thereof are respectively provided with first fuel guide grooves 20, 2 similar to those described in the first embodiment.
1.22, respectively. Bar filter body 1
Similarly to the first embodiment, the nozzle side end of No. 6 communicates with the second fuel guide groove 23, 24, 25, and the tip (
The second fuel inclined guide l whose cross-sectional area is gradually reduced according to
l133.34.35 is formed. It should be noted that other components that are substantially the same as those in the first embodiment are designated by the same reference numerals and explanations thereof will be omitted.

According to the second embodiment, the inclined fuel guide fIt30.31.3 is provided at the pump-side end and the nozzle-side end of the bar filter main body 16, and the depth gradually increases toward the tip.
2.33.34.35, the fuel flow path is gradually and gently contracted or expanded, so that swirling of the fuel is less likely to occur (and the pressure loss of the fuel flow is reduced).

(Effects of the Invention) As explained above, the bar filter for fuel injection valves of the present invention not only has the effect of removing foreign matter in the fuel, but also has a gentle cross-sectional area of the fuel flow path before and after the bar filter. Since the configuration is such that the fuel vortex is less likely to occur and pressure loss can be reduced, the maximum pressure of the pump can be reduced and the pump can be made smaller. Furthermore, by increasing the injection pressure, atomization of the fuel is promoted, and by increasing the air utilization rate during combustion, exhaust gas characteristics can be improved.

[Brief explanation of drawings]

1 is a side view showing a bar filter according to a first embodiment of the present invention, FIG. 2 is an enlarged view taken in the direction of arrow 11 shown in the first drawing, and FIG. 3 is an enlarged view taken in the direction of arrow 11 shown in the first drawing; Figure 4 is a partially cutaway sectional view of a fuel injector with a bar filter attached to it, Figure 5 is a sectional view of the bar filter attached to the fuel injector, and Figure 6 is the axial position of the bar filter. FIG. 7 is a side view showing the bar filter according to the second embodiment of the present invention, and FIG. 8 is a diagram showing the relationship between the conventional example and the first embodiment of the present invention. Fig. 9 is a view taken in the direction of the arrow ■ shown in Fig. 7, Fig. 10 is a partial perspective view of the bar filter shown in Fig. 7, and Fig. 11 is a sectional view for explaining the conventional example. It is. 23.24.25... Second fuel guide groove, 28... First projection (reduced cross-sectional area part), 29... Second protrusion (reduced cross-sectional area part), 30.31.32... 1st fuel inclined guide groove (cross-sectional area reduced part), 33.34.35... 2nd fuel inclined guide groove (cross-sectional area reduced part).

Claims (1)

[Claims] (1) A bar filter that can be press-fitted into a fuel passage formed in a fuel injection valve body, the bar filter having a press-fit portion formed in the bar filter body, and a bar filter formed in the bar filter body having an outer diameter smaller than the press-fit portion. a small diameter portion; a plurality of first fuel guide grooves extending axially from an end of the filter on the outer peripheral wall surface of the small diameter portion and not penetrating the other end of the filter; the first fuel guide groove and the first fuel adjacent thereto; a second fuel guide groove that extends in the axial direction from between the guide grooves to the other end of the filter and does not penetrate the filter end; and a second fuel guide groove that is formed in at least one end of the bar filter body and has a cross-sectional area as it approaches the tip. 1. A bar filter for a fuel injection valve, comprising: a reduced cross-sectional area portion in which the cross-sectional area gradually becomes smaller;