JPH0224942Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Field of Application] The present invention relates to a fuel injection pump for an internal combustion engine, and more particularly to a fuel injection pump in which the fuel injection start time can be variably controlled with a simple structure.

[Conventional technology]

In general, a fuel injection pump includes a plunger 3 that makes a constant reciprocating motion by pushing up a cam 1 and pushing down a plunger spring 2, as shown in FIG. It has a plunger barrel 6 in which a suction/discharge hole 5 is formed for sucking and discharging the fuel oil in the storage chamber 4, and the fuel oil sucked into the plunger barrel 6 from the suction/discharge hole 5 during the pushing down process of the plunger 3 is transferred to the plunger barrel 6. The fuel is compressed in the pushing-up process, pushing up the discharge valve 7, and being force-fed to a fuel injection nozzle (not shown). The plunger 3 is formed with a shaft hole 8 communicating with the inside of the plunger barrel 6 and a spiral notch (lead) 9. When the notch 9 meets the suction/discharge hole 5 during the pushing up process, the inside of the plunger barrel 6 The compressed fuel oil escapes into the oil storage chamber 4 through the shaft hole 8, the notch 9, and the suction/discharge hole 5, and the fuel oil injection ends. That is, a in Fig. 2
The position where the tip of the plunger 3 closes the suction/discharge hole 5 as shown in FIG. Determine the amount. In order to vary the effective stroke l, a control sleeve 11 with a pinion 10 for rotating the plunger 3 is fitted to the lower end of the plunger 3, and by moving a control rack 12 meshed with the pinion 10, The plunger 3 can be rotated regardless of its up and down reciprocating motion. Note that 13 is a pump housing.

[The problem that the idea aims to solve]

However, in the fuel injection pump having the above configuration, since the position of the fuel intake/discharge hole 5 is constant,
It is difficult to vary the injection start timing, and therefore it is also difficult to control exhaust gas.

Recently, it has been proposed that a convex or concave portion is formed at the tip of the plunger to vary the fuel injection start timing, but since the concave and convex portion is formed directly on the plunger, it does not affect the effective stroke. There was a problem with the issue.

In addition, in order to vary the injection start timing, the plunger barrel is provided so as to be freely movable in the axial direction (Utility Model Publication No. 78718/1983, Japanese Patent Application Publication No. 188763/1973, Japanese Patent Publication No. 1887/1973).
-11323) has also been proposed, but it requires space and a mechanism to move the plunger barrel in the axial direction, making the structure complicated.

The present invention was devised in order to eliminate the drawbacks of the above-mentioned conventional technology, and its purpose is to provide a fuel injection system that can reliably and variably control the fuel injection start timing with a simple structure and that can easily control exhaust gas. Our goal is to provide pumps.

[Means and actions to solve the problem]

In order to achieve the above object, the present invention has a double cylindrical flange barrel fitted around the outer periphery of the plunger so that the inner and outer cylinders can rotate relative to each other, and at least one of the inner and outer cylinders is attached to the outer periphery of the plunger. The slits are spiral-shaped and intersect with each other, and the intersection is used as a fuel intake/discharge hole, and the position of the fuel intake/discharge hole is varied in the axial direction of the plunger barrel by relatively rotating the inner and outer cylinders. This is what I did.

When the inner and outer cylinders are rotated relative to each other, the intersection of the slits, that is, the fuel intake and exhaust hole, moves in the axial direction of the plunger barrel, so unlike conventional fuel injection pumps that move the plunger barrel in the axial direction,
No space or configuration is required to move the plunger barrel axially.

For example, if the inner cylinder is fixed to the pump housing and the outer cylinder is fixed to the control sleeve, there is no need for a special drive mechanism to relatively rotate the inner and outer cylinders.

〔Example〕

A preferred embodiment of the present invention will be described in detail below with reference to the accompanying drawings.

In FIG. 3, 11 is a control sleeve with a pinion 10, and 3 is a plunger whose lower end is fitted into the control sleeve 11 so that it can only reciprocate up and down. This plunger 3 is formed with a shaft hole 8 and a spiral notch 9 for communicating the inside of the plunger barrel 6 and the suction/discharge hole 5 formed in the plunger barrel 6. In the embodiment, the plunger 3 is viewed from the bottom. It consists of a right lead plunger that rotates to the right (clockwise) to increase the effective stroke and therefore the amount of fuel injection.

The plunger barrel 6 fitted around the outer periphery of the plunger 3 is composed of a double cylinder body consisting of a cylindrical inner cylinder body 14 and an outer cylinder body 15 that are rotatable with respect to each other. Cylindrical bodies 14, 15
As shown in FIG. 4, spiral slits 16 and 17 having different inclination directions are respectively formed in the slits 16 and 17, and the intersections of these slits 16 and 17 are formed as the fuel intake and discharge holes 5. That is, the plunger barrel 6 is configured so that the position of the fuel intake/discharge hole 5 can be changed by relatively rotating the inner and outer cylindrical bodies 14 and 15 that form the plunger barrel 6, thereby making it possible to change the fuel injection start timing. has been done. In order to prevent fuel oil from overflowing and being sucked out along the notch 16 of the inner cylinder 14, a short pipe 18 that can be slid on both sides is hung at the intersection of the two slits 16 and 17, as shown in FIG. It is preferable that the fuel intake/discharge hole 5 is defined by this short pipe.

In particular, in the embodiment, the inner cylindrical body 14 has a plunger 3.
A slit 16 for the right lead, which is the same as the notch 9, is formed in the outer cylinder 15, and a slit 17 for the left lead is formed in the outer cylinder body 15. Further, the upper end of the inner cylindrical body 14 is fixed to the pump housing (see number 13 in FIG. 1), and the lower end of the outer cylindrical body 15 is fitted and fixed to the control sleeve 11. Therefore, the outer cylinder body 15
are rotated in the same direction together with the plunger 3, so that when the plunger 3 is rotated in the direction of increasing the fuel injection amount (clockwise when viewed from the bottom), the fuel intake/discharge hole 5 is rotated.
moves upward, delaying the fuel injection start time, and conversely, when the plunger 3 is rotated in a direction to decrease the fuel injection amount, the fuel intake/discharge hole 5 moves downward, making the fuel injection start time earlier. .

Next, the operation of the above embodiment will be described.

When the plunger 3 is rotated in the direction of increasing the fuel injection amount via the control sleeve 11, the outer cylinder 15 of the plunger barrel 6 also rotates in the same direction, and the slit 17 of the outer cylinder 15 and the inner The fuel intake/discharge hole 5, which is the intersection with the slit 16 of the cylinder 14, moves upward. By this, plunger 3
Since the distance from the tip of the fuel injection hole 5 to the fuel intake/discharge hole 5 becomes longer, the fuel injection start timing is delayed, and it is possible to reduce Nox, which is likely to be generated in exhaust gas under high load. Conversely, when the plunger 3 is rotated in the direction of decreasing the fuel injection amount, the fuel intake/discharge hole 5 moves downward and the fuel injection start timing is advanced, thereby reducing HC that is likely to be generated in the exhaust gas at low load. .

[Variation of the idea]

In addition, each slit 16, 17 in the above embodiment
The inclination angle (lead angle) may be changed in various ways. For example, by increasing these inclination angles, the selection range of the fuel injection start timing can be increased. Further, in the embodiment described above, when the outer cylinder body 15 is rotated, the fuel intake/discharge hole 5 moves in the circumferential direction and also in the axial direction, but the slit 16 of the inner cylinder body 14 is formed in the axial direction. By doing so, the fuel intake/discharge hole 5 may be moved only in the axial direction. According to this, since the fuel intake/discharge hole 5 does not move in the circumferential direction together with the plunger 3, the effective stroke can be made more accurate.

[Effects of the Invention] In summary, the present invention provides the following excellent effects.

(1) The plunger barrel is formed of a double cylindrical body, and the intersection of the slits formed in each body is used as a fuel intake/discharge hole, which is displaced by the rotation of the cylindrical body, so that the timing of starting fuel injection can be adjusted. It has a simple structure, can be reliably varied, and does not affect the effective stroke.

(2) Therefore, since the fuel injection start timing can be adjusted according to the load, exhaust gas control can be easily performed.

(3) Since the structure is simple, it is easy to manufacture, difficult to break down, and easy to maintain.

[Brief explanation of the drawing]

FIG. 1 is a cutaway perspective view showing a conventional fuel injection pump, FIG. 2 is an enlarged perspective view of the same essential parts, and FIG. 3 is a sectional view showing an embodiment of the fuel injection pump according to the present invention.
FIG. 4 is a perspective view of the same, and FIG. 5 is a front view showing a modification in which a short tube is inserted into the intersection of the slits. In the figure, 3 is a plunger, 5 is a fuel intake/discharge hole, 6 is a plunger barrel, 14 is an inner cylinder, 15 is an outer cylinder, and 16 and 17 are slits.

Claims (1)

[Claims for Utility Model Registration] (1) A double-cylindrical plunger barrel is fitted around the outer periphery of the plunger so that the inner and outer cylinders can rotate relative to each other, and at least one of the inner and outer cylinders has a slit. slits that intersect with each other are formed in a spiral shape, and the intersections are used as fuel intake and discharge holes, and the position of the fuel intake and discharge holes is varied in the axial direction of the plunger barrel by relatively rotating the inner and outer cylinders. A fuel injection pump characterized by: (2) The fuel injection pump according to claim 1, wherein the inner cylinder is fixed to a pump housing and the outer cylinder is fixed to a control sleeve that rotates a plunger.