JPS60119368A - Throttle type fuel injection nozzle - Google Patents

Abstract

PURPOSE:To perform initial injection with wide angle while main injection with limited angle, by arranging such that the first boundary at the end of nozzle will come at the boundary of valve seat of body and injection hole upon completion of initial lift while come above said boundary under total lift. CONSTITUTION:Fuel is pressure fed through a fuel injection pump, and upon reaching of the fuel pressure to the initial injection valve open level of nozzle needle 1, said needle 1 will start lifting to separate the seat section 1b from the valve seat 3a face of body 3 thus to inject fuel by the amount corresponding with the area of gap (a1). Upon further lifting to the initial lift (l1), the first boder line A will position in the border D of injection hole 3c and valve seat 3a while the third border line C of pin section 2 will position below the opening face 3b of injection hole 3c to complete initial lift thus to inject fuel through injection hole 3c with wide angle. Upon reaching of fuel pressure to main injection valve open level, the needle 1 will further lift to lift the first and third border lines A, C respectively from the border D and the opening face 3b and finally reaches to total lift thus to inject fuel with limited angle.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to improvements in throttle type fuel injection nozzles used in diesel engines and the like.

A throttle-type fuel injection nozzle generally used for diesel engines, etc. has a pin section at the tip of the nozzle needle, and this pin section is inserted into the nozzle hole at the tip of the nozzle body, and during the initial lift of the nozzle needle, the pin section and the nozzle hole The fuel injection rate is suppressed by the throttle action to perform initial injection, and the gap between the pin part and the injection hole is widened between the initial lift and the full lift of the needle to inject the required amount of fuel. Injecting the fuel in the combustion chamber of the engine makes it relatively smooth and prevents diesel knock.5 By the way, in the conventional throttle-type fuel injection nozzle mentioned above, fuel is generally injected along the cylindrical injection wall. Since fuel is injected, the injection angle is narrow, and the injection angle of the fuel is constant throughout the initial injection and main injection. However, from the aspect of fuel combustion, in the initial injection, the injection angle is wide to improve the ignitability of the fuel, which atomizes the fuel and improves its mixing with the air, and in the main injection, the injection angle is narrowed to improve the fuel ignitability. It is necessary to increase the penetration power of the fuel particles, that is, the distance that the fuel particles reach, and to uniformly distribute the spray throughout the combustion chamber.

Regarding the above-mentioned problem, the applicant filed an earlier application in 1983-34.
In No. 790, a sub-nozzle hole is formed that penetrates from the circumferential side of the upper pin portion at the tip of the throttle type fuel injection nozzle to the tip surface of the lower pin portion, and the tip opening of the sub-nozzle hole is made into a tapered hole that widens toward the tip. , a throttle-type fuel injection nozzle was proposed in which wide-angle injection is performed from a sub-nozzle hole during the initial injection period, and narrow-angle injection is performed from a nozzle hole in the nozzle body during the main injection period. However, according to this proposal, the diameter 1
The pin portion of the nozzle, which is less than mm in diameter, must be processed into a sub-nozzle hole shell, which is difficult and reduces the strength of the pin portion.

In view of the above-mentioned problems, an object of the present invention is to provide a throttle type fuel injection nozzle that is easy to manufacture and enables wide-angle fuel injection in the initial injection region and narrow-angle fuel injection in the main injection region, and achieves this object. In order to do this, 3- the pin part at the tip of the nozzle needle is extended from the bottom of the seat part of the nozzle needle to the tip, and the cylindrical part, the tapered first conical part that touches this at the first boundary line, and the second boundary The second conical part has a thicker end and the third conical part has a third taper. The diameter of the cylindrical part of the part is made small, and the diameter of the third boundary line is made smaller than the diameter of the cylindrical part, and the cylindrical part overlaps the nozzle hole and the nozzle needle for a length equivalent to the initial lift, and the initial lift of the nozzle needle is At the end of the lift, the first boundary line is located at the boundary between the nozzle hole of the nozzle body and the valve seat, and the third boundary line is located below the opening surface of the nozzle hole. The dimensions of each part are set so that the first boundary line is located above the boundary between the nozzle hole and the valve seat, and the third boundary line is located within the nozzle hole.

Embodiments of the present invention will be described below with reference to the drawings.

Figures 1 to 3 show the first embodiment. Figure 1 shows the nozzle needle when it is seated, Figure 2 shows the state when the initial lift is completed, and Figure 3 shows the state when the nozzle needle is fully lifted. shown respectively.

In the figure, a nozzle needle 1 has a tapered conical seat part 1b formed at the lower part of its shaft part 1a, and a small diameter pin part 2 whose diameter is reduced through a step part is formed at the lower part thereof. This pin part 2 includes a cylindrical part 2a from the base to the tip, a tapered first conical part 2b that touches this at a first boundary line A, and a second conical part 2b that is in contact with this at a first boundary line A.
A thicker conical portion 2c that contacts at a boundary line B, and a third conical portion that contacts this at a third boundary line C are formed in this order. On the other hand, the nozzle body 3 is formed with a valve seat 3a having a conical surface corresponding to the seat portion IJ of the nozzle needle I, and a cylindrical nozzle hole 3c that opens at the distal end surface of the nozzle body 3 following this valve seat 3a. Then, the diameter d of the cylindrical portion 2a of the pin portion 2 is made smaller than the diameter do of the nozzle hole 3c, and the diameter d of the cylindrical portion 2a is
1, the diameter d2 of the third boundary line C is made smaller. Further, as shown in FIG. 1, when the seat portion 1b of the nozzle needle 1 is seated on the valve seat 3a of the nozzle body 3, that is, when the nozzle needle 1 is seated, the cylindrical portion 2a moves between the nozzle hole 3c and the initial lift amount Q of the nozzle needle 1. When the nozzle needle 1 is lifted by the initial lift fl as shown in FIG. The second boundary line B enters the nozzle hole 3c, and the third boundary line C enters the opening surface 3 of the nozzle hole 3c.
Further, as shown in FIG. 3, when the nozzle needle 1 lifts by a total lift amount Q, the third boundary line C enters the inside of the nozzle hole 3c, and the first boundary line A enters the inside of the nozzle hole 3c.
The dimensions of each part are set so that they are located above the boundary between valve seat 3a and valve seat 3a.

The operation of the first embodiment having the above configuration will be explained with reference to the nozzle hole flow rate characteristic diagram shown in FIG. When the nozzle needle 1 is closed, the seat portion 1b of the nozzle needle 1 is seated on the valve seat 3a of the nozzle body 3, and the cylindrical portion 2a overlaps with the nozzle hole 3c by a length corresponding to the initial lift amount Ω1 of the nozzle needle 1, and at this time, the fuel No injection is made. (Fig. 1) Next, fuel is fed under pressure from a fuel injection pump (not shown), and when the fuel pressure reaches the initial injection valve opening pressure of the nozzle needle 1, the nozzle needle l starts to lift, and the nozzle needle 1
The seat portion tb is separated from the valve seat 3a surface of the nozzle body 3, and the gap a remains until the area of the gap a becomes equal to the area of the gap a2 between the nozzle hole 3c and the cylindrical portion 2a of the pin portion 2.
An amount of fuel corresponding to the area of 1 is injected. The flow rate characteristic during this period is shown by line P in FIG.

, the nozzle needle 1 further lifts, and the initial lift amount Q1
When lifted, the first boundary line A is the nozzle hole 3 of the nozzle body 3.
c and the valve seat 3a, and the third boundary line of the pin part 2 is located below the opening surface 3b of the nozzle hole 3c, and the initial lift ends (FIG. 2). During this time, the area of 1 gap al increases, but the area of gap a2 is smaller than that of the cylindrical part 2a and the nozzle hole 3c.
The fuel is injected from the nozzle hole 3c in a constant amount corresponding to the area of the gap a2. The flow rate characteristic during this period is shown by line Q in FIG. During this initial lift of the nozzle needle 1, the fuel flows from the gap a1 to the gap a2 along the first conical part 2b of the pin part 2, and finally flows outward in the radial direction through the second conical part 2c having a thicker taper. is deflected and injected from the nozzle hole 3c at a wide angle.

Subsequently, when the fuel pressure of the fuel injection pump reaches the main injection valve opening pressure of the nozzle needle 1, the nozzle needle 1 further lifts, and the first boundary line A becomes the first boundary line from the boundary between the injection hole 3c and the valve seat 3a. The three boundary lines C each rise from the opening surface 3b of the nozzle hole 3c and finally reach the total lift amount Q2. (Fig. 3) During this time, the area of the gap a3 between the first conical portion 2b and the nozzle hole 3c is expanded, and the fuel is supplied to the nozzle hole 3c in an amount corresponding to the area of this gap a3.
is injected from. The flow rate characteristic during this period is shown by line R in FIG.

During this main injection lift, the fuel flows from the gap a1 to the gap a3 along the first conical part 2b of the pin part 2, and reaches the second conical part 2b, where the flow is deflected in the radial direction. Since the convex surface including the third boundary line C formed by the third conical portion 2c and the third conical portion 2d is inside the nozzle hole 3c, the fuel flow is guided by the cylindrical inner wall of the nozzle hole 3c and is injected at an included angle. It is injected from the hole 3c.

The distance m1 between the third boundary line C and the opening surface 3b of the nozzle hole 3c at the end of the initial lift of the nozzle needle l, and the distance m1 between the third boundary line C and the opening surface 3b of the nozzle hole 3 at the end of the entire lift. When the distance m2 between the two and It has been confirmed through experiments that it is most effective to make the fuel injection a wide angle at the initial injection and a narrow angle at the main injection when the angles are made to match.

FIG. 5 shows the second embodiment in a state at the end of the initial lift of the nozzle needle 1, and components corresponding to those of the first embodiment are designated by the same reference numerals.

In this embodiment, the boundary D' between the nozzle hole 3c of the nozzle body 3 and the valve seat 3a is formed by a circular surface substantially parallel to the conical surface of the nozzle needle 1, and the other configuration is the same as that of the first embodiment. Similar to the example. According to this configuration, during the initial lift period, there is a gap between the seat portion of the nozzle needle 1 and the valve seat 3a.
Since the flow path resistance of the fuel flowing into the nozzle hole 3c is reduced by the conical boundary portion D', the fuel collides with the second cone portion 2c with a strong flow force and is deflected radially outward, and the fuel flows into the nozzle hole 3c. Wide-angle jetting is made more reliable.

FIG. 6 shows the flow rate characteristics of the nozzle hole of the second embodiment. The characteristic line Q of constant flow rate corresponding to the gap a2 with the hole 3c is followed by the characteristic line S of increasing flow rate corresponding to the gap a,1 between the boundary part D' and the first conical part 2b formed by the conical surface. The rear nozzle hole 3c and the first
Characteristic line R of increase in flow rate corresponding to the gap a3 with the conical part 2b
continues.

According to this embodiment, at the end of the initial lift of the nozzle needle 1, the position of the first boundary line A of the pin part 2 is within the boundary part D' forming the conical surface.

A difference occurs in the throttle injection amount due to the tolerance of the initial lift end position of the nozzle needle l.

The third embodiment is designed so that there is no difference in the throttle injection amount regardless of whether there is a tolerance between the initial and lift end positions of the nozzle needle 1, and FIG. Components shown in the state at the end of the initial lift and corresponding to those in the previous embodiment are designated by the same reference numerals.

In this embodiment, the boundary D'' between the nozzle hole 3c and the valve seat 3a of the nozzle body 3 is connected to a cylindrical hole D1'' which has a slightly larger diameter than the nozzle hole 3c following the valve seat 3a, and the cylindrical hole D1'' and the nozzle hole 3c. A conical hole D2'' is formed to connect the nozzle needle 1, and the first boundary line A of the pin portion 2 is located at the cylindrical hole D1'' portion of the boundary portion D'' at the end of the initial lift of the nozzle needle 1. Here, the nozzle needle 1 starts to lift from the valve closed position, and the gap a1 between the seat part 1b of the nozzle needle 1 and the valve seat 3a and the nozzle hole 3c
and the cylindrical part 2a of the pin part 2, and when the areas of the gap a2 become equal, the first boundary line A of the pin part 2 exactly coincides with the boundary part E between the conical hole D2'' and the nozzle hole 3c. Then, the flow rate characteristics of the nozzle hole will be as shown in Fig. 8. That is, the flow rate increase characteristic line P corresponds to the gap a1 between the seat part 1b of the nozzle needle l and the valve seat 3a, and the flow rate increase characteristic line P corresponds to the cylindrical part 2a of the pin part 2 and the conical part 2a. A current increase characteristic line T corresponding to the gap a5 with the hole D2'', a constant flow rate characteristic line U corresponding to the gap a6 between the cylindrical part 2a and the cylindrical hole 2'', and the first cone of the pin part 2. The nozzle hole flow rate characteristic is formed by a flow rate increase characteristic line V corresponding to the gap a7 between the portion 2b and the cylindrical hole.

Also, a gap a1 between the seat portion 1b of the nozzle needle 1 and the valve seat 3a, and a gap a2 between the nozzle hole 3c and the cylindrical portion 2a of the pin portion 2.
If the cylindrical portion 2a of the pin portion 2 overlaps the nozzle hole 3c when both areas become equal, the flow rate characteristic of the nozzle hole will be as shown in FIG. 9. That is, there is a gap a between the cylindrical portion 2a and the nozzle hole 3c between the line P and the line T in FIG.
A characteristic line Q with a constant flow rate corresponding to 2 is interposed. In any of the above configurations, when the initial lift of the nozzle needle 1 is completed, the position of the first boundary line A of the pin part 2 is the boundary part D''
This position is within the cylindrical hole D1'' of FIGS. 8 and 9.
Since it is on the constant flow rate line U in the figure, even if there is a tolerance in the initial lift end position of the nozzle needle 1, there will be no difference in the throttle injection amount.

Further, the effect that the flow path resistance of the amount of fuel flowing toward the first conical portion 2b is reduced by the boundary portion D'' of the above-mentioned structure is the same as that of the second conical portion 2b.
This is similar to the embodiment.

12- As explained above, according to the present invention, the pin portion at the tip of the nozzle needle has a cylindrical portion extending from the bottom of the seat portion of the nozzle needle to the tip, and a tapered first portion that contacts this at the first boundary line. A conical part, a second conical part with a thicker taper that contacts this at a second boundary line, and a third tapered conical part that contacts this at a third boundary line are sequentially formed, while a nozzle hole that connects to the valve seat of the nozzle body is formed. Make it cylindrical.

The diameter of the cylindrical portion of the pin portion is made smaller than the diameter of the nozzle hole, and the diameter of the third boundary line is made smaller than the diameter of the cylindrical portion.

The cylindrical portion overlaps the nozzle hole and the nozzle needle for a length equivalent to the initial lift, and when the initial lift of the nozzle needle ends, the first boundary line is located at the boundary between the nozzle hole and the valve seat of the nozzle body, and the first boundary line is located at the boundary between the nozzle hole and the valve seat of the nozzle body. The third boundary line is located below the opening surface of the nozzle hole, and the first boundary line is located above the boundary between the nozzle hole and the valve seat when the nozzle needle is fully lifted, and the third boundary line is located below the opening surface of the nozzle hole. By setting the dimensions of each part so that the fuel is located within the center, a wide-angle fuel injection is performed during the initial injection, which atomizes the fuel and mixes well with the air, improving ignitability, and a narrow-angle injection is performed during the main injection. As a result, the penetration power of the fuel is increased, the spray is uniformly distributed throughout the combustion chamber, the combustibility of the fuel is improved, and quiet and smokeless operation of the engine can be achieved.

The throttle type fuel injection nozzle according to the present invention is particularly suitable for application to the two-stage injection type nozzle holder disclosed in Japanese Utility Model Application No. 57-186657.

[Brief explanation of the drawing]

Figures 1 to 3 are enlarged views of the tip of the first embodiment;
The figure shows the state when the nozzle needle is closed, FIG. 2 shows the state at the end of the initial stage, and FIG. 3 shows the state at the full lift. FIG. 4 is a graph showing the nozzle flow rate characteristics of the same example. 5 and 7 are enlarged views of the tips of the second and third embodiments, respectively, showing the state at the end of the initial lift, and FIG. 6 is a graph showing the nozzle flow rate characteristics of the second embodiment, FIGS. 8 and 9 are graphs showing the nozzle flow rate characteristics of two types of configurations of the third embodiment, respectively. 1... Nozzle needle, lb... Seat part, 2...
... Bottle part, 2a... Cylindrical part, 2b... First conical part, 2c... Second conical part, 2d... Third conical part, 3a
... Valve seat, 3b. Self-mouthing surface, 3c.. Nozzle hole, A.
...First boundary line, B...Second boundary line, C...Third boundary line, D, D', D"...Boundary part, D1"...
Cylindrical hole, D2''...conical hole. Applicant: Diesel Kikai Co., Ltd. Agent Patent Attorney: Toshihiko Watanabe

Claims (1)

[Claims] 1. The pin portion at the tip of the nozzle needle extends from the bottom of the seat portion of the nozzle needle to the tip, and connects the cylindrical portion, the tapered first conical portion that contacts this at the first boundary line, and the cylindrical portion. The second conical part has a thicker taper that touches the second boundary line, and the third conical part has a tapered taper that touches the third boundary line. The diameter of the cylindrical part of the pin part is smaller than the diameter of the third part.
The diameter of the boundary line is made small, and the cylindrical part overlaps the nozzle hole and the nozzle needle for a length equivalent to the initial lift, and at the end of the initial lift of the nozzle needle, the first boundary line becomes the line between the nozzle body nozzle hole and the valve seat. The third boundary line is located at the boundary and is located below the opening surface of the nozzle hole, and the first boundary line is located above the boundary between the nozzle hole and the valve seat when the nozzle needle is fully lifted. A throttle type fuel injection nozzle, characterized in that the dimensions of each part are set such that the third boundary line is located within the nozzle hole. 2. The boundary between the nozzle hole and the valve seat of the nozzle body. 2. The throttle-type fuel injection nozzle according to claim 1, wherein the throttle-type fuel injection nozzle is formed with a conical surface substantially parallel to the conical surface of the first conical portion of the nozzle needle. 3. The boundary between the nozzle hole and the valve seat of the nozzle body is formed by a cylindrical hole with a slightly larger diameter than the nozzle hole, and a conical hole connecting the cylindrical hole and the nozzle hole, and At the end of the lift, the first boundary line of the nozzle needle is
2. The throttle type fuel injection nozzle according to claim 1, wherein the throttle type fuel injection nozzle is configured to be located within the cylindrical hole at the boundary. 4. The opening surface of the nozzle hole of the nozzle body is made to coincide with approximately the midpoint position of the same position of the third boundary line of the pin portion at the end of the initial lift of the nozzle needle and at the end of the full lift. A throttle type fuel injection nozzle according to any one of claims 1 to 3.