JPH051653Y2 - - Google Patents

Description

[Detailed explanation of the idea] [Industrial application field] The present invention relates to a unit injector.

[Prior Art] Unit injectors are known, and one example thereof will be described with reference to FIG. In the figure, a cam follower 2 that reciprocates following a cam (not shown) that rotates in synchronization with the rotation of the engine is mounted on the top of a unit injector body (hereinafter referred to as the body) 1.
The main body 1 is provided with a plunger barrel 5 into which a plunger 3 that is reciprocally driven by the cam follower 2 is fitted. An annular fuel chamber 7 communicating with a fuel inlet 6 is provided on the upper outer periphery of the plunger barrel 5, and the fuel chamber 7 and the plunger chamber 8 are connected to a feed hole 9 formed in the plunger barrel 5.
It is communicated with. The plunger chamber 8 communicates with the nozzle 11 through a feed passage 10, and the nozzle spring chamber 14, which houses a nozzle spring 12 that determines the valve opening pressure and is formed in the nozzle holder 13, communicates with the fuel chamber 7 through an overflow passage 15. . In addition, in the figure, 4 is a plunger spring, and 16 is a nozzle retainer nut. By the way, in such a unit injector, in order to adjust the valve opening pressure of the nozzle 11,
When adjusting pressure is applied from the fuel inlet 6 as shown by the arrow, that pressure acts on the fuel chamber 7 and acts on the nozzle spring chamber 14 via the overflow passage 15, thus ensuring normal valve opening pressure adjustment. was difficult.

Furthermore, as shown in FIG. 10, in a unit injector in which a feed hole 9a is provided in the plunger barrel 5 opposite to the feed hole 9, when checking the fuel injection start timing, it is necessary to check the nozzle retainer nut when the unit injector is alone. 16 is removed, the plunger 3 closes the feed holes 9, 9a, and the fuel stops coming out from the tip of the feed passage 10. However, when the unit injector is attached to the engine, it is impossible to visually see that fuel stops coming out from the lower end of the feed passage 10, making it difficult to inspect and adjust the fuel injection start timing.

Regarding a unit injector, the present applicant has proposed a unit injector in Japanese Utility Model Application Publication No. 165258/1988, in which the opening degree of the nozzle port changes depending on the pressure in the fuel passage.

[Purpose of the invention] Accordingly, an object of the invention is to provide a unit injector that allows easy adjustment of valve opening pressure and inspection of fuel injection start timing.

[Structure of the invention] According to the invention, an engagement surface is formed at the opening of the feed hole that communicates the inside and outside of the plunger barrel of the unit injector, and an engagement surface that engages with the engagement surface is formed on the unit injector main body. A fuel supply connector body with a surface is removably attached.

[Operation and effect of the invention] Therefore, the part of the unit injector body facing the feed hole opening is always closed with a blind plug, and when adjusting the valve opening pressure, the blind plug is removed and the connector bolt, which is the connector body, is attached to that part. and apply adjusting pressure through its connector bolt. Since this adjustment pressure is applied to the nozzle from the feed passage and not to the fuel chamber, normal valve opening pressure adjustment can be easily performed without acting on the nozzle spring chamber via the overflow passage.

When inspecting the fuel injection start timing, install the connector bolt as above, pump fuel into the fuel chamber using the priming pump of the fuel pump, etc., and check when the plunger closes the feed hole and fuel no longer comes out from the connector bolt. The fuel injection start timing can be easily checked.

[Preferred Embodiment] When carrying out the present invention, it is preferable to use a tube having a conical engagement surface and a connector bolt containing the tube as the connector body.
A connector bolt with a smooth engagement surface may also be used.

[Examples] Examples of the present invention will be described below with reference to the drawings. In those drawings, Figures 9 and 10
Portions corresponding to the figures are given the same reference numerals and redundant explanation will be omitted. In FIG. 1, a cone surface 20, which is an engagement surface, is formed at the outer opening of the feed hole 9, and a screw hole 21 is formed at the portion of the main body 1 that faces the cone surface 20. 21 is normally closed with a blind plug 22 that screws into the screw hole 21.

As shown in FIGS. 2 and 3, the screw hole 21 is selectively fitted with a tube 23 which is a connector body.
and connector bolt 24 containing tube 23
is installed. The tube 23 has a cone surface 23a that engages with the cone surface 20 of the feed hole 9.
is inserted into the inner hole of the connector bolt 24, and the connector bolt 24 is inserted into the screw hole 21 of the main body 1.
are screwed together.

When adjusting the valve opening pressure, as shown in Figure 4,
screw the connector bolt 24 into the cone surface 23a of the tube 23 to the cone surface 2 of the feed hole 9.
0 to press and engage. And connector bolt 2
Apply adjustment pressure from one end of 4 as shown by the arrow.
Then, the adjustment pressure does not act on the fuel chamber 7, but instead flows through the tube 2 as shown by the arrow.
3, is transmitted to the nozzle 11 via the feed hole 9, the plunger chamber 8 and the feed passage 10. Therefore, normal valve opening pressure adjustment can be easily performed.

When checking the fuel injection start timing, screw the connector bolt 24 into the screw hole 21 in the same way as when adjusting the valve opening pressure, and press the cone surface 23a of the tube 23 into the cone surface 20 of the feed hole 9 (the third
figure). Then, as shown in FIG. 5, fuel is pumped through the fuel inlet 6 by a priming pump or the like of a feed pump (not shown). Then, the fuel is discharged from the connector bolt 24 via the fuel chamber 7, feed holes 9a, 9, and tube 23 as shown by the arrow. Next, as shown in FIG. 6, when the cam follower 2 moves and the plunger 3 rises to close the feed holes 9a, 9, the outflow of fuel from the connector bolt 24 is stopped. The fuel injection start timing can be easily checked based on when the fuel injection stops.

FIG. 7 shows another embodiment of the present invention, in which the engaging surface of the opening of the feed hole 9 and the connector bolt 25
This is an example in which both of the engaging surfaces are formed as smooth surfaces 26. In this embodiment, the valve opening pressure can be easily adjusted as in FIG.

FIG. 8 shows yet another embodiment of the present invention, in which both the engagement surface of the opening of the feed hole 9 and the engagement surface of the connector bolt 25 are formed into a smooth surface 26. In this embodiment, the fuel injection start timing can be easily checked as in FIG. 5.

[Summary] As explained above, according to the present invention, it is possible to easily adjust the valve opening pressure and check the fuel injection start timing by engaging the engaging surface of the connector body with the engaging surface of the feed hole when necessary. I can do it.

[Brief explanation of the drawing]

Figures 1 to 3 show one embodiment of the present invention, Figure 1 is a cross-sectional view showing the state in which the blind plug is normally attached, and Figure 2 is a cross-sectional view showing the state in which the connector body is attached. , Fig. 3 is a vertical cross-sectional view of the main part of Fig. 2, Fig. 4 is a longitudinal cross-sectional view showing the state at the time of valve opening pressure adjustment, and Fig. 5 and Fig. 6 are respectively the state at the time of checking the fuel injection start timing. FIGS. 7 and 8 are cross-sectional views showing main parts of different embodiments of the present invention, and FIGS. 9 and 10 are respectively illustrative of conventional unit injector valve opening pressure adjustment and FIG. 3 is a longitudinal cross-sectional view showing the state at the time of fuel injection start timing inspection. 1... Unit injector, 5... Plunger barrel, 9... Feed hole, 20... Cone surface, 22... Blind plug, 23... Tube, 2
3a... Cone surface, 24... Connector bolt, 2
5...Connector bolt, 26...Smooth surface.

Claims (1)

[Scope of utility model registration request] An engaging surface is formed at the opening of a feed hole that communicates the inside and outside of the plunger barrel of the unit injector, and a connector body for fuel supply is provided with an engaging surface that engages with the engaging surface on the unit injector main body. A unit injector characterized by being removably attached.