JPH0361665A - Fuel injector - Google Patents

Abstract

PURPOSE:To reduce the dimension of an engine by externally fitting a tappet at the edge part of a plunger onto a plunger barrel onto which a fuel plunger is internally fitted, in slidable manners and installing a guide for preventing the slip-off of the tappet onto a sliding part. CONSTITUTION:A tappet 39 which is guided by the pump part of a fuel injector is directly guided by a plunger barrel 21. Therefore, the need of an injector body is obviated. Further, the whole diameter can be reduced in comparison with the conventional state by installing a slip-off guide 49 for the tappet 39 between the tappet 39 and the barrel 21, and the fuel faculty can be improved by increasing the diameter of the plunger barrel 21 by that portion. On the contrary, the combustion faculty is improved by reducing the diameter of the pump part having the largest outside diameter of the fuel injection device, and the dimension of the engine can be reduced furthermore.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a fuel injection device, particularly a fuel injection device for a diesel engine.

Conventional technology A unit injector that is integrally equipped with a fuel injection pump and a fuel injection nozzle is conventionally used as a fuel injection device for a diesel engine.The main component of the unit injector is a plunger for pumping fuel. , a barrel into which the plunger is inserted, and a tappet attached to the end of the plunger. The tappet is brought into contact with the fuel injection valve arm or cam side, and the plunger is driven by the tappet being pushed and slid by the valve arm or cam, but it is necessary to stabilize these operations. In order to do this, a guide for the sliding movement of the tappet is required. FIG. 4 shows a conventional unit injector equipped with these components.

In Fig. 4, (1) is an injector body, and its tip is equipped with a nozzle part (6) consisting of a nozzle nut (2), a nozzle body (3), a nozzle valve (4), a nozzle spring (5), etc. There is. Injector body (1)
A plunger barrel (7) is inserted into the plunger barrel (7) from above, and a plunger (8) is inserted into the plunger barrel (7) so as to be vertically slidable. A cylindrical tappet (9) attached to the upper end of the plunger (8) is slidably inserted into the upper end of the injector body (1), and the tappet ( 9) is designed to slide. Further, a tappet return spring (11) is interposed between the lower end of the tappet (9) and a spring receiver (10) provided between the injector body (1) and the plunger barrel (7).

To the vertical long hole (12) formed in the tappet (9),
A retaining guide (13) inserted into the injector body (1) from the outside protrudes. Further, in order to position the retaining guide (13) itself in the diametrical direction, a support plate (14) fixed to the outer peripheral surface of the injector body (1) is provided on the outside of the retaining guide (13). On the other hand, the fuel suction hole (15) of the plunger barrel (7) is connected to the communication hole (1) of the injector body (1).
6) through the circular groove (17) formed on the inner periphery of the injector body (1), or spill fuel flows in the opposite direction.
8> is attached to the annular groove (17), and this spill protector (18) is positioned in the circumferential direction by a spring pin (19) inserted into the injector body (1).

Problem to be Solved by the Invention By the way, in a unit injector used as this type of fuel injection device, the diameter of the plunger (8) disposed in the pump section is made as large as possible to shorten the injection period. There is a request to make it shorter. This makes it possible to easily control the injection rate and improve exhaust color and NOx. Further, by increasing the diameter of the plunger, the rigidity of the plunger itself is increased, and by increasing the pressure, these problems can be further improved. In this way, if the plunger diameter is increased, the diameter of the pump section, that is, the entire unit injector body, will inevitably increase accordingly, but conventionally, the tappet (9) is connected to the injector body (1) as described above. ) and the tappet (9) is guided by this injector body (1), and since the plunger barrel (7> is installed inside this injector body (1), the pump part, i.e. Unit injector body (1) The diameter of the plunger itself is large, and if it were made larger than this, it would be difficult to install it in the cylinder head, and it would also be an obstacle to downsizing diesel engines, so it is said that the plunger diameter cannot be increased as it is. In addition, in direct injection engines, it is desirable to insert the unit injector vertically into the combustion chamber for combustion, but as mentioned above, the diameter of the unit injector itself is originally large. Therefore, due to the relationship with other parts, it is not possible to insert it vertically, so it has to be inserted diagonally.In order to make such vertical insertion possible, the diameter of the unit injector itself has to be made as small as possible. Further, in the spill protector (1B) provided on the outside of the fuel intake hole (15) of the plunger barrel (7), this spill protector (18) is also attached to the injector body (1) as described above. )
installed inside the injector body (1
) The injector body (19) is inserted into the injector body (19) for positioning in the circumferential direction, which increases the thickness of the injector body (1), making it impossible to reduce the overall diameter.

This invention solves these problems by making the plunger diameter larger than the conventional one when the diameter of the injector body remains the same, thereby improving combustion performance. If it were to be the same as the conventional one, the diameter of the entire unit injector would be reduced by 1
5. This makes it possible to further downsize the diesel engine.

Means for Solving the Problems: As a means of the present invention for solving the above problems, the tappet at the end of the plunger is slidably fitted onto a plunger barrel in which a plunger for pumping fuel is installed. It is characterized by

Further, in the above, it is conceivable to provide a guide for preventing the tappets from coming off between the tappets and the plunger barrel.

Furthermore, in order to reduce the diameter of the spill protector part,
In the third invention of this application, a spill protector is attached to the outer periphery of the plunger barrel so as to surround the fuel intake hole of the plunger barrel, and a quick-made elastic fixture is also fitted and fixed to the outer periphery of the plunger barrel, and this elastic The spill protector is characterized in that the position of the spill protector in the circumferential direction is determined by a protrusion formed on the fixture.

The working tappet is guided directly by the plunger barrel, so that a conventional injector body is not required. Furthermore, the spill protector is similarly positioned circumferentially by a fixture externally fitted onto the plunger barrel, likewise eliminating the need for an injector body.

Embodiment In FIG. 1 showing an embodiment of the present invention, (21> is a plunger barrel, and this plunger barrel (21)
) A nozzle nut (23) is screwed into a male screw (22) integrally formed at the lower end of the nozzle nut (23) to tighten and fix the spacer (24) and nozzle body (25) on the lower side. In addition, a spring receiver (28) that is pressed downward by a nozzle spring (27) is provided in the recess (26) formed in the male thread (22>), and the spring receiver (28) allows the lower side of the nozzle valve (2
9) is always biased in the closing direction. A plunger insertion hole (30) is formed in the plunger barrel (21) from its upper end to near the lower end.
0), a plunger (31) is slidably inserted from above. The insertion hole (30) on the lower end side of the plunger (31)
) A fuel supply hole (33> is formed in the radial direction from the plunger chamber (32) toward the outer periphery of the barrel (21). Through the outer mouth of this fuel supply hole (33>),
An annular fuel reservoir (34) is formed, and this fuel reservoir (3
4), and the spill protector (
35) is installed.

Further, the plunger (31) has a reed (36) formed on its outer periphery so that the injection amount can be adjusted by changing the communication position with the fuel supply hole (33). The upper end of the plunger barrel (21) has a stepped portion (37
), and a generally cylindrical tappet (39) is fitted onto this small diameter portion (38>) from above so as to be vertically slidable. The upper end of the plunger (31) penetrates through the upper part of this tappet (39) and protrudes upward, and the large diameter part (40) near the upper end of this plunger (31) comes into contact with the upper surface side of this tappet (39). are in contact with each other. tapet) (
A connecting portion (43) is integrally formed so as to protrude upward from the large diameter 7 flange (42) formed at the upper end of the connecting portion (43).
A stopper (44) is attached that comes into contact with the upper end surface of the holder.

By pushing this stopper (44) from above with a valve arm or the like, the plunger (31) is slid downward.

Also, the plunger (3
1) A control lever (45) is attached to the end, and the lever (45) rotates the plunger (31) in the circumferential direction to connect the lead (36) and the fuel supply hole (
33) so that the communication position can be changed. A plunger return spring (46) is provided between the flange (42) and the step (37) of the plunger barrel (21).
is interposed. A vertically long elongated hole (48) is formed in one part of the cylindrical part of the tappet (39).
A retaining guide (49) is inserted into the elongated hole (48) and attached to the small diameter portion (38> of the plunger barrel (21) from the inner peripheral surface of the plunger insertion hole (30) side.
) protrudes, and by this retaining guide (49),
This prevents the tappet (39) from rotating in the circumferential direction and from coming off upward.

Figure 2 is an enlarged view of the installation of the stop guide (49) after the above, and shows the small diameter part (38) of the plunger barrel (21).
) has a mounting hole (50〉) with a small diameter on the outer circumference.
It is formed into a two-stage shape by the step portion (51). On the other hand, the retaining guide (49) has a two-stage shape with a smaller diameter on the protruding part side. (52) comes into contact with the step part (51),
It is inserted so that it cannot fall out. Further, an annular groove (53) is formed on the inner periphery of the plunger insertion hole (31) so as to pass through the hole (50) for this installation.
3), a holding ring (54) formed of wire or other elastic material is fitted from the inside, and the holding ring (54) holds the large diameter part (52) of the retaining guide (49). It is always urged to press against the stepped portion (51) and prevents it from coming off inward.

As a result, the retaining guide (49>) is housed compactly in the sliding portion between the plunger barrel (21) and the tappet (39) so as not to protrude in either direction.

FIG. 3 shows an exploded view of the spill protector (35), which has several fuel communication holes (55) at appropriate intervals in the circumferential direction.
) is formed, thereby providing communication between the fuel reservoir (34) and the outside.

The spill protector (35) covers the fuel reservoir (34) and the plunger barrel (21).
The upper end of the first
As shown in the figure, it is in contact with a downwardly facing step (57) on the outer circumference of the plunger barrel (21).

On the other hand, on the lower end side of the spill protector (35),
An annular groove (5) formed on the outer periphery of the plunger barrel (21)
8), a fixing ring (59) formed of a wire or other elastic member as shown in FIG. 3 is fitted and attached. One end of this fixing ring (59>) is bent upward almost vertically and protrudes, and this protrusion (60) extends from the groove (58) of the plunger barrel (21) into the fuel reservoir (
The upper end of the groove (61) is engaged with the vertical groove (61) formed over the spill protector (61).
35) It is positioned so as not to rotate in the circumferential direction by engaging with a notch (62) formed at one location on the lower end.

Effects of the Invention As described above, according to the present invention, the tappet, which was conventionally guided by the injector body, that is, the pump part of the fuel injection device, is directly guided by the plunger barrel, so that the tappet is guided directly by the plunger barrel. There is no need for an injector body for this, and the guide to prevent the tappet from coming off is also provided between the tappet and the barrel, so the overall diameter can be made much smaller than the conventional one. The diameter of the plunger barrel can be increased accordingly to improve combustion performance, or conversely, the diameter of the entire unit injector, that is, the diameter of the pump section with the largest outer diameter of the fuel injection device, can be reduced. As mentioned above, since it is possible to mount the fuel cell at right angles to the combustion chamber, it is possible to similarly improve the combustion performance and contribute to further downsizing of the diesel engine. In addition, since the injector body as described above is not required, the number of parts is also reduced. This also applies to the spill protector, which is fitted onto the plunger barrel and prevented from rotating in the circumferential direction by a fixture fitted onto the plunger barrel. Compared to a type that prevents rotation using a spring pin inserted into the body, no special member is required on the outside of the spill protector, the overall diameter can be made smaller, and the overall diameter can be made more compact or the plunger diameter can be increased. becomes possible.

[Brief explanation of drawings]

FIG. 1 is an overall vertical sectional view of a unit injector showing an embodiment of the present invention, FIG. 2 is an enlarged view of the main part of FIG. 1, and FIG.
The figure is an exploded perspective view of a spill protector and its fixing member, and FIG. 4 is an overall vertical sectional view of a conventional unit injector. (21) Plunger barrel, (31) Plunger, (33) Fuel supply hole, (35) Spill protector, (39) Tappet, (49)... Guide to prevent tappet from coming off,
(58) ...Fixing ring. patent

Claims (1)

[Scope of Claims] 1. A fuel injection device characterized in that a tappet at the end of the plunger is slidably fitted onto a plunger barrel housing a plunger for pumping fuel. 2. The fuel injection device according to claim 1, wherein the guide for preventing the tappet from coming off is attached to a sliding portion between the tappet and the plunger barrel. 3. Surround the fuel intake hole of the plunger barrel,
A spill protector is attached to the outer periphery of the plunger barrel, and a ring-shaped elastic fixture is also fitted and fixed to the outer periphery of the plunger barrel, and the projections formed on this elastic fixture position the spill protector in the circumferential direction. A fuel injection device characterized by: