JPH07189862A - Fuel injection pump - Google Patents

Abstract

PURPOSE:To provide a fuel injection pump which has both pre-flow effect function at fuel injection start and fuel spill control function at fuel injection finish are both obtained and resolves various problems with a fuel injection pump having pre-flow effect. CONSTITUTION:A sub-port 15 is formed to be lower than a main-port 14. An upper sub-lead 21 and an upper main-lead 26 are formed. A lower sub-lead and a lower main-lead are formed to be inclined lead. At the rotational position of a plunger 7 in starting, the main port 14 is closed by an upper end 7A of the plunger 7 where the upper main lead is not formed, and also the sub-port 15 is closed by the upper end 7a of the plunger 7 where the upper sub-lead is not formed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fuel injection pump, and more particularly to a fuel injection pump in which a main port and a sub port are formed as a fuel intake / exhaust hole in a plunger barrel.

[0002]

2. Description of the Related Art Generally, as a characteristic of a fuel injection pump,
It is desirable to advance (advance) the fuel injection timing when the engine is rotating at high speed, and the timing is adjusted by the structure of the fuel injection pump itself without separately using a timer (automatic advance device) for adjusting such injection timing. Some have an adjustment mechanism.

Among such timing adjusting mechanisms, the preflow effect at the time of high speed rotation, that is, the phenomenon in which the fuel is pumped by the dynamic effect (throttle effect) before the fuel feed hole (suction / exhaust hole) is closed is used to advance. Some try to obtain angular characteristics.

However, even if the injection timing characteristic at the time of high speed rotation of the engine is good due to the preflow effect, the injection timing at the time of starting the engine or at the torque point (low speed / high load) is delayed (retarded) due to this preflow effect. However, there is a drawback that it is difficult to realize the optimum timing of the engine as a result.

Therefore, it is required that both the advance angle at the time of high speed rotation and the advance angle at the time of starting are compatible with each other, and the advance angle characteristic is arbitrarily set according to the load condition (low load, high load) of the engine. There has been a demand for a configurable fuel injection pump.

In order to meet such a demand, a main port and a sub port are formed as intake and exhaust holes, an upper main lead that can communicate with the main port, and an upper sub lead that can communicate with the sub port are formed to achieve a preflow effect during high speed rotation of the engine. A fuel injection pump that can be advanced and can also advance at the time of starting, and can set advance angle characteristics arbitrarily according to the engine load condition (low load, high load) and engine speed (low speed, high speed) was suggested.

However, for the fuel injection pump which can set the advance angle characteristic according to the load state and the rotation speed by providing such a preflow effect, only the control of the start point of the fuel injection by the preflow effect is performed. Is.

Particularly, in such a fuel injection pump, the cam lift is high by the amount of the preflow stroke,
In other words, since the fuel is pumped by the cam portion with a high oil feed rate, the fuel injection rate tends to increase, and therefore the maximum fuel injection rate at low speed and high load cannot be reduced, and smoke (black Smoke) and particulates (soot)
There is a problem that it is difficult to control the occurrence of

As described above, the injection characteristics are attempted to be improved by appropriately controlling the fuel injection start timing, while the intake / exhaust holes have a larger diameter in order to appropriately control the fuel injection end timing. There is a port which has a smaller diameter and is formed separately on the plunger barrel to improve the injection characteristics by improving the fuel shortage and controlling the injection amount according to the load level.

For example, in the fuel injection pump according to Japanese Patent Laid-Open No. 55-101761 (Japanese Patent Publication No. 60-8343), a large diameter oil drain hole 8b which is a set of main ports and a small diameter discharge port which is a set of sub ports are provided. Oil hole 8a, first plunger lead 14b and second plunger lead 1
4a and a control land 15 for controlling the opening and closing of the large-diameter oil drain hole 8b is provided on the plunger head, and a preflow effect is exerted by this control land, and a small-diameter oil drain is provided on the low load side. A spill is made from the hole 8a to prevent a sharp decrease in the fuel injection amount at low speed and low load.

However, it is necessary to provide one set for each of the main port and the sub port, and
Since spilling is attempted from the small diameter oil drain hole 8a on the low load side, there is a problem that the spill from the sub port cannot be performed on the high load side, resulting in insufficient output.

Further, there is a problem that the pre-flow stroke amount cannot be selected depending on the load due to the provision of the control land, and the fuel injection start control cannot be performed by the load because the upper lead is not formed.

[0013]

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and by forming a main port and a sub port, and a main lead and a sub lead, the preflow effect at the start of fuel injection can be improved. An object of the present invention is to provide a fuel injection pump that has both the function and the function of fuel spill control at the end of fuel injection and that can solve various problems of the fuel injection pump having the preflow effect.

[0014]

That is, according to the present invention, a main port and a subport for achieving a preflow effect are formed, a combination of an upper main lead and a lower main lead facing the main port, and a subport facing each other. Focusing on the combination of the upper sub-lead and the lower sub-lead, the pump housing, the plunger barrel that is attached to the pump housing, and has the fuel suction hole that communicates with the fuel storage chamber, and the plunger barrel And a plunger having an inclined lead formed at a position where it can be slidably and reciprocally and rotatably inserted and can communicate with the suction / discharge hole, and a fuel pressure chamber is formed between the plunger and the plunger barrel. , The reciprocating sliding of this plunger causes It draws fuel from Ri chamber to the fuel chamber, a fuel injection pump for pumping the fuel injection nozzle, as the suction and discharge hole in the plunger barrel, a larger diameter main port and a smaller diameter than the sub-port,
The upper edge of the sub-port is formed to be equal to or less than the upper edge of the main port, and the head of the plunger has an upper sub-lead capable of communicating with the sub-port over a predetermined range according to the rotation of the plunger, and the main portion. An upper main lead that can communicate with the port is formed, and even if the main port is closed by the upper edge of the upper main lead within a predetermined range associated with the rotation of the plunger, the sub-port is connected to the upper sub-lead. The upper main lead and the upper sub lead are formed so that they can communicate with each other, and the plunger can communicate with the sub-port over a predetermined range accompanying the rotation of the plunger and at a position below the upper edge of the plunger. Lower sub lead and lower main lead that can communicate with the above main port The de formed as the inclined lead,
Furthermore, at the rotation position of the plunger at the time of starting,
The main port can be closed by the upper end edge of the plunger not forming the upper main lead, and the sub port can be closed by the upper end edge of the plunger not forming the upper sub lead. It is a fuel injection pump.

Particularly, at the pivotal position of the plunger under high load, the main port does not communicate with the lower main lead even if the sub port communicates with the lower sub lead due to the movement of the plunger in the pumping direction. In addition, at the plunger rotation position under a low load, even if the main port communicates with the lower main lead due to the movement of the plunger in the pumping direction, it seems that the subport does not communicate with the lower sublead. Can be

As an example of a specific configuration for this purpose, for example, regarding the inclination of the lower main lead and the lower sub lead that descends below the plunger from the low load side to the high load side, It is conceivable that the inclination gradient is larger than that of the lower sub-lead.

[0017]

In the fuel injection pump according to the present invention, the structure having the preflow effect is designed to allow the fuel for the preflow stroke to escape from the subport at a low speed and to pump the fuel after the subport is closed, that is, the fuel by the subport and the sublead. Since no spill (completion of pumping) is performed, the portion of the cam with a high cam speed is used, so there is the problem that the fuel injection rate becomes high at low speeds, but the fuel injection end timing can be determined. The formation of the lower main lead and the lower sub lead made it possible to control the fuel spill even at low speeds, so this problem can be solved, and fuel injection can be performed by selecting the inclination state of the lower main lead and the lower sub lead. The load range that can determine the end time and the load range that does not determine the end time It can also be selected.

Further, by selecting the inclination states of the lower main lead and the lower sub lead, the load area where spill is generated from the subport portion, and the subport spill stroke (from the spill from the subport to the spill from the main port) is selected. Plunger stroke) can be selected.

Furthermore, since the upper main lead is formed together with the upper sub-lead and the main port and the sub-port can be closed at the upper edge of the plunger which is not formed at the time of starting, the advance angle at the time of starting is arbitrary. Can be set to.

[0020]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, a fuel injection pump according to a first embodiment of the present invention will be described with reference to FIGS. Figure 1
2 is a vertical cross-sectional view of the fuel injection pump 1, and FIG. 2 is a vertical cross-sectional view of a main part. The fuel injection pump 1 includes a pump housing 2, a cam 4 attached to a cam shaft 3 connected to an engine (not shown), It has an injection amount control rack 5, a plunger barrel 6, a plunger 7, a delivery valve 8, and a delivery valve holder 9.

The cam 4 receives the drive of the engine via the cam shaft 3 and the plunger 7 via the tappet roller 10.
Reciprocate vertically.

The control rack 5 is connected to an accelerator (both not shown) via a governor,
By moving in a direction perpendicular to the plane of the drawing, the plunger 7 is rotated through a control sleeve 11 for controlling the injection amount by a predetermined angle with its axis as a rotation axis.

The plunger barrel 6 is fixed inside the pump housing 2 and attached thereto. The plunger barrel 6 accommodates the plunger 7 in such a manner that it can reciprocate and rotate, and a fuel reservoir chamber 12 is provided between the plunger barrel 6 and the pump housing 2. A fuel pressure chamber 13 is formed between the delivery valve 8 and the delivery valve 8.

A larger-diameter main port 14 and a smaller-diameter sub-port 15 are formed in the plunger barrel 6 as fuel intake / exhaust holes.

As shown in the enlarged view of FIG. 2, the upper edge 14A of the main port 14 and the upper edge 15A of the sub-port 15 are not at the same height or at the same horizontal position, and are spaced 180 degrees apart in the circumferential direction. This is formed.

The positional relationship between the upper edge 14A of the main port 14 and the upper edge 15A of the sub port 15 is as follows.
If necessary, the upper edge 15A of the sub-port 15 may be formed so as to be located below the upper edge 14A of the main port 14.

The plunger 7 reciprocates in the plunger barrel 6 to suck the fuel from the fuel reservoir chamber 12 and compress it in the fuel pressure chamber 13 to deliver it to the delivery valve 8.
Is opened and the fuel is pressure-fed to the fuel injection nozzle (not shown) through the injection pipe 16 (FIG. 1).

The fuel injection nozzle is of a throttle type suitable for a so-called indirect injection type auxiliary combustion chamber type diesel engine used in a diesel engine having a secondary combustion chamber such as a pre-combustion chamber or a swirl chamber. If a fuel injection nozzle is adopted, combustion will proceed gradually after partial fuel injection into this sub-combustion chamber, so the combustion noise will be low,
The generation of nitrogen oxides can be suppressed to a low level, and a slight lift of the needle valve of the fuel injection nozzle causes a large change in the nozzle opening area.By adjusting this lift, the fuel injection rate can be controlled. It is relatively easy to control the generation of smoke and particulates.

FIG. 3 is a lead development view of the head of the plunger 7, showing the main port 14 and the sub-port 15 with a broken line (at the time of starting) and a solid line (at the time of low load and high load), and between them. The relative positional relationship is shown.

As shown in FIGS. 2 and 3, on the peripheral surface of the head of the plunger 7, a vertical main fuel passage 17 communicating with the fuel pressure chamber 13 and an inclination communicating with the vertical main fuel passage 17 are provided. -Shaped lower main lead 18 and fuel pressure chamber 1
3, the vertical sub-fuel passage 19 communicating with the fuel pressure chamber 13
And the upper main lead 20 communicating with the fuel pressure chamber 1
3, an upper sub-lead 21 communicating with 3 and an inclined lower sub-lead 22 communicating with the vertical sub-fuel passage 19 are formed.

Both the lower main lead 18 and the lower sub lead 22 are formed below the upper end edge 7A of the plunger 7, and control the timing of spill of the fuel to be pumped (end of pumping).

The inclination of the lower main lead 18 is larger than that of the lower sub lead 22. That is, with respect to the inclinations of the lower main lead 18 and the lower sub lead 22 descending below the plunger 7 from the low load side to the high load side, the slope of the lower main lead 18 is the slope of the lower sub lead 22. It is formed larger. However, by appropriately selecting the inclinations of the lower main lead 18 and the lower sub lead 22 as in other embodiments described later,
The fuel injection characteristic can be appropriately determined.

The region of the upper main lead 20 facing the main port 14 and the region of the upper sub lead 21 facing the sub port 15 correspond to the engine from low load to high load, and the region of the upper end edge 7A of the plunger 7 corresponds to starting. To do.

Since the plunger 7 reciprocates up and down in the plunger barrel 6 by the action of the cam 4, the upper main lead 20, the upper sub lead 21, the lower sub lead 22, the vertical main fuel passage 17 and the lower main lead 18 in FIG. At the same time, it moves up and down with respect to the main port 14 and the sub port 15 in the fixed position.

The plunger 7 is the control rack 5
Since it rotates in the plunger barrel 6 by the action of the above, the upper main lead 20 and the upper sub lead 2 in FIG.
1, the lower sub lead 22, the vertical main fuel passage 17, and the lower main lead 18 move left and right with respect to the main port 14 and the sub port 15 in the fixed position.

In the fuel injection pump 1 having such a structure, as the plunger 7 descends, the fuel sump chamber 12
Is sucked into the fuel pressure chamber 13 from the main port 14 and the sub port 15.

As the plunger 7 rises, the upper edge 7A of the plunger 7 and the upper edge 20 of the upper main lead 20
A or the upper edge 21A of the upper sub-lead 21,
Fuel compression starts when the main port 14 or the sub port 15 is closed, and when the main port 14 engages with the lower main lead 18, or the sub port 1
When 5 is engaged with the lower sub-lead 22, the pumping of fuel is terminated.

That is, the stroke from the bottom dead center of the plunger 7 to the start of the fuel pressure feed is the prestroke,
The stroke from the closing of the sub-port 15 to the opening of the main port 14 is an effective stroke, and the depth of the upper sub-lead 21 is a starting advance step L1 for a low speed.
Is. It should be noted that the depth of the upper main lead 20 is the starting advance angle step L2 with respect to the high speed, and this difference (L
1-L2) is the preflow stroke, that is, the advance step L
It is 3.

More specifically, when the engine is started, the main port 14 and the subport 15 are not the upper main lead 20 or the upper sublead 21, but are opposed to the upper edge 7A in the starting region of the plunger 7. There is.

Therefore, the effective stroke of the fuel pressure feeding is maximum, and the fuel injection amount required at the time of engine start can be secured.

By forming the upper main lead 20, the upper end edge 7A of the plunger 7 is set to the upper main lead 20.
Since it is positioned higher than the upper edge 20A of the above, the angle of advance is more advanced at the time of starting than at the time of low speed and low load.

During operation of the engine under low load and high load, the main port 14 is connected to the upper main lead 20,
The subports 15 can face the upper subleads 21, respectively.

In low speed and low load operation such as idling,
Since the main port 14 is located to the left of the lower main lead 18 in FIG. 3, the effective stroke is small, and the subport 15 engages with the upper sublead 21.
After being closed by A, substantial fuel pumping is started.

When the engine speed is increased and high-speed low-load operation is performed, the main port 14 is located to the left of the lower main lead 18, but the subport 15 causes the subport 15 to upper end edge 2 of the upper sublead 21 due to the throttling effect.
Since the fuel pressure feed is started before the fuel is completely closed by 1A, the fuel injection timing advances (advances) and the actual pressure feed stroke increases.

FIG. 4 is a timing map shown in the NQ characteristic diagram (hereinafter, "advance" means "advance angle" and "late").
Indicates "retard" respectively). As shown in the figure, it becomes possible to obtain the advance angle characteristic both at the time of starting and at the time of high speed.

Referring particularly to FIG. 3, the fuel pumping start points at low load and high load are the same, but at the end of pumping, the main port 14 spills first from the main port 14 at the low load side and becomes high. On the load side, the spill comes from the subport 15 first. The stroke of the plunger 7 after the spill from the sub port 15 to the spill from the main port 14 on the high load side is the sub port spill stroke.

Movement (upward movement) of the plunger 7 in the pressure feeding direction
Accordingly, on the low load side, even if the main port 14 is in the spill starting state, the sub port 15 has not yet reached the communication with the lower sub lead 22, and thus it is possible to maintain substantially the same injection characteristics as the conventional one. .

On the other hand, on the high load side, even if the subport 15 starts to spill, the main port 14 has not yet communicated with the lower main lead 18, so that fuel spill from the subport 15 will occur especially at low speeds. Done. It should be noted that at high speed, due to the throttling effect of the subport 15, the subport 15 remains substantially closed even if the subport 15 is engaged with the lower sublead 22, and the injection characteristics similar to those of the conventional case can be maintained. it can.

FIG. 5 is a graph showing the relationship of the fuel injection amount Q with respect to the engine speed N. In the fuel injection pump combined with the conventional standard throttle type fuel injection nozzle, at low speed and high load. The fuel injection rate ΔQ with respect to the cam speed at the torque point has a steep point (protruding maximum injection rate) (see the solid line), but in the fuel injection pump 1 of the present invention, this is gentle and the maximum injection is performed. The rate can be significantly reduced (see the dotted line).

That is, at low speed and high load, the fuel is slowly spilled by the engagement of the sub port 15 and the lower sub lead 22 from the middle of the effective stroke accompanying the rise of the plunger 7, and the actual oil feed rate at low speed rotation is reduced. It is possible to reduce NOx, NOx, combustion noise, smoke and particulates at low speed and high load, and increase the fuel injection amount under the same smoke condition at low speed and high load as an engine. Therefore, the improvement of the low speed torque and the improvement of the output can be realized.

At the rated point at high speed and high load,
The relationship of the fuel injection rate ΔQ to the cam angle in the fuel injection pump combined with the conventional standard throttle type fuel injection nozzle (not shown) is maintained substantially the same in the fuel injection pump 1 of the present invention. can do.

Furthermore, since the injection rate at low speed can be suppressed even if the oil feed rate is improved, the fuel injection rate (oil feed rate) at high speed and high load is increased accordingly, and the output is improved. It is possible to improve fuel efficiency.

FIG. 6 is a graph showing the relationship between the engine speed N and the fuel injection amount Q when the injection amount control rack is fixed. The NQ characteristic is left-downward at low speed and high load. be able to.

Thus, since the preflow effect plunger 7 having the subport 15 is used and the upper sublead 21 is formed at an appropriate position, it is possible to realize both high speed advance and advance advance.

When it is desired to advance the engine angle at the time of starting more than at high speed and under high load, the upper edge 7A of the plunger 7 should be formed further upward so as to face the main port 14 and the sub port 15 at the time of starting. Good.

Further, in addition to the control at the time of starting the fuel injection, as described above, the lower main lead 18 and the lower sub lead 22, the main port 14 and the sub port 1 are provided.
By combining with 5, it is possible to control the end time of fuel injection.

Next, in the present invention, both the start and end of the pressure feeding of fuel can be controlled, and various modifications other than the above-described first embodiment can be considered.

In each of the following embodiments, the upper edge 14A of the main port 14 and the sub port 1 are the same as in FIG.
It is assumed that the upper edge 15A and the upper edge 15A are not formed at the same height or in the same horizontal position, and a detailed description thereof will be omitted.

For example, FIG. 7 is an explanatory view showing a simplified lead development view of the head of the plunger 7 similar to that of FIG. 3 in the fuel injection pump 30 according to the second embodiment of the present invention. The upper edge 7A and the upper sub lead 21 are similar to those of the first embodiment of FIG. 3, and the inclination of the lower main lead 31 corresponding to the lower main lead 18 and the inclination of the lower sub lead 32 corresponding to the lower sub lead 22 are the same. The gradient of is the same as that of the first embodiment of FIG.

However, a single vertical main fuel passage 33 corresponding to the vertical main fuel passage 17 is provided, and the lower main lead 31 and the lower sub lead 32 are provided only at one end of each vertical main fuel passage 33.
Is in communication with.

FIG. 8 is an explanatory view showing a simplified lead development view of the head of the plunger 7 in the fuel injection pump 40 according to the third embodiment of the present invention. An inclined upper sub lead 41 is formed so that the sub port 15 on the load side faces the lower main lead 18.
By setting the direction opposite to that of the lower sub-lead 22 and from the low load side to the high load side,
In particular, it is possible to control the starting point of the pressure feeding of the fuel at the low speed side so that the low pressure side becomes slower.

The inclination gradient of the lower sub lead 22 and the lower main lead 18 is the same as that of the first embodiment of FIG. 3, and the main port 14 spills first on the low load side and on the high load side on the sub port 15 side. It is configured to spill first.

FIG. 9 is an explanatory view showing a simplified lead development view of the head of the plunger 7 in the fuel injection pump 42 according to the fourth embodiment of the present invention. The upper end edge 7A of the plunger 7 and the upper sub lead are shown. 41 is the same as that of the third embodiment of FIG. 8, but by forming the position of the lower main lead 18 further below the plunger 7 than in the case of the third embodiment, a low load side and a high load side are provided. On the load side, the sub-port 15 is spilled first.

FIG. 10 is an explanatory view showing a simplified lead development view of the head of the plunger 7 in the fuel injection pump 43 according to the fifth embodiment of the present invention. The upper end edge 7A of the plunger 7 and the upper sub lead are shown. As for 41, FIG.
9 is similar to the third embodiment of FIG. 9 and the fourth embodiment of FIG. 9, but the inclination of the lower sub-lead 22 is made larger than the inclination of the lower main lead 18 so that the sub-port at the low load side is It spills first from 15 and spills from the main port 14 first on the high load side.

FIG. 11 is an explanatory view showing a simplified lead development view of the head of the plunger 7 in the fuel injection pump 50 according to the sixth embodiment of the present invention. Inclined upper sub-leads 51 facing the main ports 14 on the load side and the high load side
By forming the upper sub-lead 51 to be inclined in the same direction as the lower main lead 18 and the lower sub-lead 22, the fuel feeding start time is increased from the low load side to the high load side. Can be controlled to be slower on the high load side.

The slopes of the lower sub leads 22 and the lower main leads 18 are the same as those in the first embodiment shown in FIG. 3, and the main port 14 spills first on the low load side and the sub port 15 on the high load side. It is configured to spill first.

FIG. 12 is an explanatory view showing a simplified lead development view of the head of the plunger 7 in the fuel injection pump 52 according to the seventh embodiment of the present invention. The upper end edge 7A of the plunger 7 and the upper sub lead are shown. 51 is shown in FIG.
However, by forming the position of the lower sub lead 22 above the plunger 7 as compared with the case of the sixth embodiment, both the low load side and the high load side can be connected to the sub port 15 from It is designed to spill first.

FIG. 13 is an explanatory view showing a simplified lead development view of the head of the plunger 7 in the fuel injection pump 53 according to the eighth embodiment of the present invention. The upper end edge 7A of the plunger 7 and the upper sub lead are shown. As for 51, FIG.
The sixth embodiment of FIG. 1 and the seventh embodiment of FIG. 12 are the same, but the inclination of the lower sub-lead 22 is set to be larger than the inclination of the lower main lead 18 to reduce the load on the low load side. Spill from subport 15 first,
On the high load side, the main port 14 is spilled first.

FIG. 14 is an explanatory view showing a simplified lead development view of the head of the plunger 7 in the fuel injection pump 60 according to the ninth embodiment of the present invention. An inclined upper sub lead 61 is formed so that the sub ports 15 on the loaded side and the high loaded side face each other, and the upper sub lead 61 is inclined in the same direction as the lower main lead 18 and the lower sub lead 22. As the load goes from the low load side to the high load side, it is possible to control the fuel pumping start point particularly at the low speed side so that the fuel load start side becomes slower on the high load side.

The inclination of the lower sub-lead 22 and the lower main lead 18 is the same as that of the first embodiment shown in FIG. 3, and the main port 14 spills first on the low load side and the sub-port 15 on the high load side. It is configured to spill first.

FIG. 15 is an explanatory view showing a simplified lead development view of the head of the plunger 7 in the fuel injection pump 70 according to the tenth embodiment of the present invention.
An upper main lead 71 is formed at the upper edge 7 </ b> A of the main port 14 on the low load side and the main port 14 on the high load side to face each other. By setting it in the opposite direction to 22, it is possible to control the fuel pumping start time to be delayed on the low load side from the low load side to the high load side.

The inclination of the lower sub-lead 22 and the lower main lead 18 is the same as that of the first embodiment shown in FIG. 3, with the main port 14 spilling first on the low load side and the sub-port 15 on the high load side. It is configured to spill first.

In the present invention, in addition to the above-mentioned respective embodiments, the inclination gradient of the lower main lead 18 and the lower sub lead 22, the upper edge 7A of the plunger 7, the upper main leads 20, 51, 71 and the like. Reed,
By appropriately selecting the formation position and inclination state of the upper sub leads such as the upper sub leads 21, 41 and 51, it is possible to control the start timing and the end timing of the fuel injection to obtain an arbitrary fuel injection characteristic.

[0074]

As described above, according to the present invention, the preflow effect of the subport and the upper sublead is utilized, and the lower main lead and the lower sublead capable of combining the respective inclined states are used, and the main ports face each other. Since the fuel injection pump is formed with the upper main lead, the smoke timer can be controlled especially at low speed and high load while maintaining the speed timer function that can control the fuel injection timing at low speed and high speed, and the advance function at startup. (Black smoke) and particulates (soot) are reduced, the fuel injection amount can be increased, and the torque can be increased.

Furthermore, since the fuel injection rate at low speed does not increase even if the oil feed rate is improved, the fuel injection rate (oil feed rate) at high speed and high load can be improved, and the output can be improved. It is possible to improve fuel efficiency.

[0076]

[Brief description of drawings]

FIG. 1 is a fuel injection pump 1 according to a first embodiment of the present invention.
FIG.

FIG. 2 is a vertical sectional view of the same.

FIG. 3 is a lead development view of the head of the plunger 7.

FIG. 4 is a timing map shown in the NQ characteristic diagram.

FIG. 5 is a graph showing a relationship between a fuel injection amount Q and an engine speed N.

FIG. 6 is a graph showing the relationship between the engine speed N and the fuel injection amount Q when the injection amount control rack is fixed.

FIG. 7 is a fuel injection pump 3 according to a second embodiment of the present invention.
FIG. 4 is an explanatory diagram in which a lead development view of the head of the plunger 7 similar to that in FIG.

FIG. 8 is a fuel injection pump 4 according to a third embodiment of the present invention.
It is explanatory drawing which simplified and drawn the lead development view of the head of the plunger 7 in 0.

FIG. 9 is a fuel injection pump 4 according to a fourth embodiment of the present invention.
It is the explanatory view which simplified and drawn the lead development view of the head of the plunger 7 in 2.

FIG. 10 is an explanatory diagram showing a simplified lead development view of the head of the plunger 7 in the fuel injection pump 43 according to the fifth embodiment of the present invention.

FIG. 11 is an explanatory view showing a simplified lead development view of the head of the plunger 7 in the fuel injection pump 50 according to the sixth embodiment of the present invention.

FIG. 12 is an explanatory view showing a simplified lead development view of a head portion of a plunger 7 in a fuel injection pump 52 according to a seventh embodiment of the present invention.

FIG. 13 is an explanatory view showing a simplified lead development view of the head of the plunger 7 in the fuel injection pump 53 according to the eighth embodiment of the present invention.

FIG. 14 is an explanatory view showing a simplified lead development view of a head of a plunger 7 in a fuel injection pump 60 according to a ninth embodiment of the present invention.

FIG. 15 is an explanatory view showing a simplified lead development view of the head of the plunger 7 in the fuel injection pump 70 according to the tenth embodiment of the present invention.

[Explanation of symbols]

1 Fuel Injection Pump 2 Pump Housing 3 Cam Shaft 4 Cam 5 Injection Volume Control Rack 6 Plunger Barrel 7 Plunger 7A Plunger 7 Top Edge 8 Delivery Valve 9 Delivery Valve Holder 10 Tappet Roller 11 Injection Volume Control Sleeve 12 Fuel Pool 13 Fuel pressure chamber 14 Main port (fuel intake / exhaust hole) 14A Main port 14 upper edge 15 Sub port (fuel intake / exhaust hole) 15A Sub port 15 upper edge 16 Injection pipe 17 Vertical main fuel passage 18 Lower main lead 19 Vertical sub fuel passage 20 Upper Main Lead 20A Upper Main Lead 20 Upper Edge 21 Upper Sub Lead 21A Upper Sub Lead 21 Upper Edge 22 Lower Sub Lead 30 Fuel Injection Pump 31 Lower Main Lead 32 Lower Sub Lead 33 Vertical Direction Main fuel passage 40 Fuel injection pump 41 Inclined upper sub-lead 42 Fuel injection pump 43 Fuel injection pump 50 Fuel injection pump 51 Inclined upper sub-lead 52 Fuel injection pump 53 Fuel injection pump 60 Fuel injection pump 61 Inclined upper sub-lead 70 Fuel injection pump 71 Inclined upper main lead L1 Depth of the upper sub lead 21 (start advance angle step for low speed) L2 Upper depth of the main lead 20 (start advance angle step for high speed) L3 Pre Flow stroke or advance step (L1-
L2)

Claims (1)

[Claims] 1. A pump housing, a plunger barrel attached to the pump housing and having a fuel intake / exhaust hole communicating with the fuel storage chamber, and reciprocally slidably and rotatably inserted into the plunger barrel. A fuel pressure chamber is formed between the plunger and the plunger barrel, and a reciprocating sliding movement of the plunger causes the fuel pool to move. A fuel injection pump that sucks fuel into the fuel pressure chamber from the chamber and pressure-feeds it to a fuel injection nozzle, wherein a larger-diameter main port and a smaller-diameter subport are provided as the suction and discharge holes in the plunger barrel at the upper end of the subport. The edge of the plunger is formed so that the edge is below the upper edge of the main port. Is formed with an upper sub-lead that can communicate with the sub-port over a predetermined range associated with the rotation of the plunger and an upper main lead that communicates with the main port, and within a predetermined range associated with the rotation of the plunger. The upper main lead and the upper sub-lead are formed so that the sub-port can communicate with the upper sub-lead even if the main port is closed by the upper edge of the upper main lead. A lower sub-lead that can communicate with the sub-port and a lower main lead that can communicate with the main port are formed as the inclined lead over a predetermined range accompanying the rotation and below the upper edge of the plunger. In the rotating position of the plunger at A fuel characterized in that the main port can be closed by the upper end edge of the plunger without forming the main lead, and the subport can be closed by the upper end edge of the plunger without forming the upper sub lead. Injection pump.