JPH01151770A - Fuel injection pump - Google Patents

Abstract

PURPOSE:To enable two stage fuel injection in random intermediate/heavy load operation area by forming main and sub-ports at facing positions on a barrel fitted with a plunger and forming an inclined groove communicatable with the sub-port in the head section of the plunger. CONSTITUTION:Main and sub-ports 12, 12a are formed in the barrel 11 of a fuel injection pump and communicated each other through an annular path 19 arranged between the barrel 11 and a body 10, An inclined groove 35 is formed in the head section of a plunger 14 fitted in the plunger insertion hole 13 of the barrel 11, and a throttle path 36 communicated with a fuel spill port 27 is opened to the central section of the groove 35. Secondary fuel injection can be obtained in random operation area by regulating the primary injection stroke of the plunger 14 and the minimum cross-section area at fuel leak section of the throttle path 36 under a condition where the main port 12 is closed by the plunger head section and the inclined groove 35 is not communicated with the sub-port 12a.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a fuel injection pump for an internal combustion engine.

(Prior art and its problems) In general, in diesel engines, during low-speed operation, the spark delay of fuel spray is longer than during high-speed operation, and therefore, during low-speed operation, combustion occurs rapidly after ignition, resulting in There is a problem in that the rate of pressure rise within the combustion chamber becomes large, which causes large combustion noise.

In order to suppress such combustion noise, considering the cause of its occurrence, it is necessary to suppress the rate of pressure rise in the cylinder due to combustion.
In other words, it is effective to cause the mixture to burn slowly in the cylinder, and to achieve this, for example, the method disclosed in Japanese Utility Model Application Publication No. 59-30555 is proposed.
A technology that employs a staged injection method is known.

Incidentally, recently there has been a demand for two-stage fuel injection to suppress the maximum pressure in the cylinder in any operating range of medium-high load operation, but fuel injection pumps capable of such two-stage injection are still unknown. It has not been done.

Furthermore, there is still no known fuel injection pump that can further reduce combustion noise by increasing or decreasing the first-stage injection amount in response to increases or decreases in load.

(Objective of the Invention) The first invention provides a fuel injection pump that injects fuel in two stages in any operating range of medium to high load operation and can increase or decrease the first stage injection amount according to the load using an inclined groove. A second object of the present invention is to provide a fuel injection pump that can increase or decrease the first stage injection amount depending on the load using a combination of parallel grooves and an upper lead.

(Structure of the Invention) (1) Technical Means The first invention makes it possible to pressurize and force-feed fuel by reciprocating a plunger within a barrel. The amount of fuel injection is adjusted by forming a lower lead in the form of a diagonal groove that communicates with the barrel, and adjusting the timing of communication between the lead and a barrel port formed in the barrel by appropriately rotating the plunger and the barrel relative to each other. In the fuel injection pump, a sub-barrel port is formed at a position substantially opposite to the barrel port of the barrel, a fuel relief passage is formed that communicates the top surface of the plunger with the lead, and the top surface of the plunger is connected to the top surface of the plunger. An inclined groove that can communicate with the sub-barrel port within the relative rotation range of the barrel and the plunger is formed on the outer circumferential surface, and as the load increases, the plunger head moves toward the barrel port. a fuel leak portion of a throttle passage that communicates the inclined groove with the fuel relief passage, which is set so that the primary injection stroke Sl in which the plunger slides increases when the inclined groove is closed and the inclined groove does not communicate with the sub-barrel port; By setting the minimum cross-sectional area A sin and the primary injection stroke SL to be adjustable, and arbitrarily setting the primary injection stroke Sl and the minimum cross-sectional area A1n of the fuel leak part, the two-stage fuel injection can be performed in any operation. This patented injection pump is characterized in that the primary injection stroke SI is increased or decreased in accordance with an increase or decrease in load using an inclined groove.

The second invention makes it possible to pressurize and force-feed the fuel by reciprocating the plunger within the barrel, and at the same time, a lower lead in the form of a diagonal groove is provided on the outer peripheral surface of the head of the plunger, which communicates with the top surface of the plunger. In a fuel injection pump, the fuel injection amount is adjusted by appropriately rotating the plunger and the barrel relative to each other to adjust the communication timing between the lead and a barrel port formed in the barrel, An auxiliary barrel port is formed at a position substantially facing the barrel port of the barrel, a fuel relief passage is formed that communicates the top surface of the plunger with the lead, and a auxiliary barrel port is formed on the outer circumferential surface of the head of the plunger at a position substantially opposite to the barrel port of the barrel and the plunger. forming a parallel groove that can communicate with the sub-barrel port in a rotational range, and adjustable a minimum cross-sectional area A n+in of a fuel leak part of a throttle passage that communicates the parallel groove with the fuel relief passage;
A primary injection stroke Sl in which the plunger slides in a state where the plunger head closes the barrel port and the parallel groove does not communicate with the sub-barrel port is set to be adjustable, and the plunger head closes the sub-barrel port. An upper lead that increases the primary injection stroke Sl as the load increases is formed at a position where communication is possible, and the primary injection stroke Sl and the minimum cross-sectional area A 1n of the fuel leak part are arbitrarily set. This fuel injection pump is characterized in that two-stage fuel injection can be obtained in any operating range, and the primary injection stroke Sl can be increased or decreased in accordance with the increase or decrease in load using the inclined groove.

(2) Effect In the first invention, the relative rotation of the plunger and the barrel increases or decreases the stroke length in which the inclined groove and the sub-barrel port do not communicate, thereby increasing or decreasing the primary injection stroke S1.

In the second invention, the stroke length in which the parallel groove and the sub-barrel port do not communicate is increased or decreased by using the upper lead with an inclined lower surface,
Increase or decrease the primary injection stroke St.

(Embodiments) (1) First Embodiment FIG. 1 shows a fuel injection pump for a diesel engine according to a first embodiment of the present invention.
0 is a pump body with an integrated mounting flange; 11 is a barrel fitted and fixed in the pump body 10;
A barrel port 12 (main port) in the form of a through hole is formed on one side surface, that is, the left side surface in the figure. On the right side of the barrel 11 facing this barrel port 2,
A sub-barrel port 12a is formed in the form of a small diameter through hole. Both ports 12, 12a are connected to the barrel 11 and the main body 10.
It communicates with the annular passage 19 between the two.

A plunger insertion hole 13 is formed in the axial center of the barrel 11 so as to communicate with the barrel port 12. A plunger 14 is fitted into the plunger insertion hole 13 so as to be relatively rotatable and slidable, and the plunger 14 is reciprocated in the axial direction by the spring force of the plunger spring 15 and the cam action of the fuel cam 16. By doing so, the fuel sucked into the high pressure chamber 18 formed on the top surface 17 is pressurized, and the fuel is delivered via the delivery valve 20 to the injection nozzle or injector (not shown) provided in each cylinder of the engine (not shown). (not shown).

Further, in FIG. 1, reference numeral 21 is a plunger rotating wheel that is attached to the plunger 14 so as to be able to engage in the circumferential direction, and the plunger 14 is engaged with the rotating wheel 21 by a metering operator 22. By appropriately pushing and pulling the rack gear 23, it is caused to rotate relative to each other within the barrel 11,
It is adapted to carry out a predetermined metering action. That is, as shown in FIGS. 2 and 3, on the outer peripheral surface 25 of the head 24 of the plunger 14, a diagonal groove-shaped lower lead 26 is provided at an appropriate distance from the top surface 17 over approximately half the circumference. It is formed.

Further, this lower lead 26 is communicated with the top surface 17 of the plunger 14 via a fuel relief hole 27 (fuel relief passage) extending in the plunger axial direction. In addition, the first
28 in the figure is the barrel port 12 and the sub-barrel port 12
This is a supply vibe that distributes fuel to a.

Therefore, by rotating the plunger insertion hole 13 relative to the barrel 11, the relative communication timing between the lower lead 26 of the plunger 14 and the barrel port 12 of the barrel 11 is changed, and the closing period of the barrel port 12 is changed. By adjusting, the amount of fuel to be injected is adjusted.

As shown in FIGS. 4 and 5, the delivery valve 20 includes a valve body 30, a valve seat 31, and a delivery spring 3.
2 (FIG. 1), the valve body 30 is biased against the valve seat 31 to open and close.The valve body 30 is integrally formed with an annular collar 33 as shown in FIG. 1. It has a function of sucking back fuel by the sucking back stroke 291 in FIG. 4 when the delivery valve 20 is closed (fuel injection end timing). Note that the collar 33 of this embodiment is not provided with the conventionally known Angleich cut.

Although such a metering mechanism consisting of a combination of the barrel port 12 and the lower lead 26 superimposed and communicating with the barrel port 12 is conventionally known, this embodiment is not limited to this; It also has a function to arbitrarily adjust the operating range in which two-stage injection characteristics are exhibited during medium-load operation, and a function to control the initial injection rate by increasing or decreasing the primary injection amount according to the load. Although this adjustable two-stage injection operating range is not variable once it is set, it can be set arbitrarily depending on the characteristics required by the engine.

In FIGS. 2 and 3a, the head 24 of the plunger 14 has an inclined groove 35 cut upwardly to the right in the drawings by 2 from the outer circumferential surface 25 (FIG. 3). This inclined groove 35 is formed on the top surface 1
It is formed with a height (width) of B at a position that is lower than the dimension Y from 7. This inclined groove 35 allows the plunger 1
4 rotates, and the position of the sub-barrel port 12a of the barrel 11 moves relatively to the left and right.
The next injection stroke Sl is increased or decreased depending on the load.

Further, a throttle passage 36 is opened in the center of the inclined groove 35, and the minimum cross-sectional area A 1n of the fuel leak part of the throttle passage 36 is
, is the diameter of the throttle passage 36, and is the diameter of the sub-barrel port 12a.
Let d be the diameter of Aln, -yr when d>M
/ 4 ・When M2d<M A m1n, -π/ 4
*d becomes 2-(1).

As mentioned above, the plunger 14 is connected to the center line CLI in FIG.
to Cl3, both ports 12° 12a move relative to each other at an angle of boat movement angle θp, and the inclined groove 35 and the sub-barrel port 12a do not communicate with each other near the center line CL2 where the maximum injection amount occurs. It has become.

Next, the positional relationship between the inclined groove 35 and the barrel port 12 is such that the top surface 17 and the upper edge of the barrel port 12 are aligned and separated by a primary injection stroke St, which will be described in detail later. The diameter of the barrel port 12 is set to D. Therefore, the primary injection stroke S1 becomes St-Y-d (2).

Once the minimum cross-sectional area Aa+in of the fuel leak part and the primary injection stroke Sl shown in equations (1) and (2) above are set, they are not variable, but can be set arbitrarily according to the fuel injection characteristics required by the engine. It is possible to set it to the value of
As will be described in detail later, the minimum cross-sectional area of the fuel leak part A w
By changing the value of the primary injection stroke Sl to in, the two-stage injection characteristic can be exhibited even during medium load operation where two-stage injection could not be obtained conventionally.

The lower lead 26 is located at a position lower than the top surface 17 by an amount of 26 communicate with each other through a communication hole 37. Further, the inclined groove 35 is inclined at an angle between 0 and set in the relationship θL>0M (3).

In the above configuration, since the aforementioned Angleich cut is not formed in the delivery valve 20, the dynamic injection timing TI changes to a predetermined value as the no-load characteristic C1 as the rotational speed N increases, as shown in FIG. The dynamic injection timing Tm gradually retards at the delay angle of
m is fast).

When the load is high, the characteristic C2 occurs, and since the delivery valve 20 (Fig. 1) is not provided with an Angleich cut in this embodiment, as the load increases, the dynamic injection timing Tm
There is no load timer function to delay (retard operation).

In addition, when an Angleich cut 40 is formed in the collar 33 as shown in FIG. 6a, when the valve body 30 in FIG. 4 closes, fuel flows from this Angleich cut 40 and is sucked back. The amount of fuel sucked back by the stroke g1 is reduced by the fuel leakage from the Angleich cut 40, tti. When the amount of fuel sucked back decreases, the residual pressure in the pipe from the delivery valve 20 to the injector increases accordingly, and as a result, the amount of fuel injection increases in accordance with the increase in residual pressure. Due to this increase in residual pressure, the characteristic CI' at no load changes to the characteristic C2° at high load, and the load timer function by the retard operation is performed.

Barrel 11 with the sub-barrel port 12a and inclined groove 3
No. 8 showing a two-stage injection stroke by the plunger 14 with a
In the figure, before reaching state (a), the top surfaces 1 and 7 of the plunger 14 are open to the barrel port 12, and in this state, even if the plunger 14 rises, the fuel in the high pressure chamber 18 is Not compressed. Next, in (a), the top surface 17
When the upper edge of the barrel port 12 coincides with the upper edge of the barrel port 12, the barrel port 12 is closed by the plunger 14, and as the plunger 14 rises, the fuel in the high pressure chamber 18 begins to be compressed. Injection begins. This primary injection It is injected during the primary injection stroke S until the inclined groove 35 communicates with the barrel port 12, and in (b) the upper edge of the inclined groove 35 and the lower edge of the sub-barrel port 12a are injected. When they match, the sub-barrel port 12a and the high pressure chamber 18 communicate through the fuel relief hole 27 and the throttle passage 36 (FIGS. 2 and 3a), and the compression stroke of the fuel in the high pressure chamber 18 is once completed, and the state shown in (X) At 02, the primary injection ■l ends.

In the state (C), the secondary barrel port 12a and the high pressure chamber 18 are in communication through the inclined groove 35 and the fuel relief hole 27, so even if the plunger 14 rises, the fuel in the high pressure chamber 18 is not compressed, and (X ) Fuel injection stops in the Δθ° section. Eventually, when the lower edge of the inclined groove 35 and the upper edge of the auxiliary barrel port 12a match in (d), the high pressure chamber 18 is sealed again, and the secondary injection I2 starts at θ3 in (X). This secondary injection I2 continues during the secondary injection stroke S2 during which both ports 12.12a are closed by the plunger 14 and the lower lead 26 communicates with the main barrel port 12.

At (e), the lower edge of the lower lead 26 and the barrel port 12 coincide, and the barrel port 12 and the high pressure chamber 18 communicate with each other via the lower lead 26 and the communication hole 37 (Fig. 2), that is, (X
), the secondary injection I2 ends at θ4.

Therefore, Δθ and Δθ゛ of (X) are Δθ−3L
+d+B...(4)△θ' -d+B...
(5) Become. The angles Δθ and θ° are angles obtained from the lift characteristics of the fuel cam corresponding to the dimensions on the right side of the above equation.

As described above, the primary injection II occurs due to the primary injection stroke St, and the rotational speed Nc at which the two-stage injection characteristic (X) begins to occur changes as shown by the characteristic c3 in FIG. 9.

In addition, since the sliding speed of the plunger 14 is slow in a low rotation state, even if the minimum cross-sectional area Am1n of the fuel leak portion is small, the fuel is allowed to flow through the throttle passage 36 and the sub-barrel port 12a and the high pressure chamber 18 are communicated with each other. However, as the engine speed increases, plunger 1
The sliding speed of No. 4 becomes faster, and the small fuel leak part with the minimum cross-sectional area Am1n has a throttling effect, making it impossible to circulate the viscous fuel within a very short time.
The Δθ° shown in FIG. The rotational speed Nr at which the second-stage injection changes to the first-stage injection changes as shown in characteristic C4 according to the minimum cross-sectional area A 1n of the fuel leak portion, as shown in FIG. 1O.

Therefore, by appropriately adjusting this primary injection stroke S1 and the minimum cross-sectional area of the fuel leak part All1n,
The first graph is a graph of fuel injection ff1Q-pump rotation speed n.
It is possible to arbitrarily control the rotational speed Nc at which the second-stage injection starts and the rotational speed Nr at which the first-stage injection starts as shown in FIG.

As shown in FIG. 12, in this embodiment, since the delivery valve 20 (FIG. 1) is not provided with an Angleich cut that functions to increase the fuel injection mQ at low load, the rotation speed N1 fuel injection In the operating range where both the amount Q and the amount Q are small, residual pressure and pressure, which will be described in detail in the following second embodiment, are not generated, and neither is the primary injection ll. On the other hand, at medium load, by arbitrarily setting the primary injection stroke Sl and the minimum cross-sectional area A1n of the fuel leak part, the areas D a and D of (a) and (b) in FIG.
As shown in b, the operating range in which the two-stage injection characteristic is exhibited can be arbitrarily adjusted. In Fig. 12, the lower characteristic C5 is the fuel injection EI.
The characteristic CB in the upper row shows the time of low load when Q is small, and the characteristic CB in the upper row shows the time of high load when there is a lot of fuel injection ff1Q.

In the case where the Angleich cut 40 shown in FIG. 6a is provided,
The two-stage injection characteristic can be maintained even in the idling state in the region DI while reducing the fuel injection amount Ql by the primary injection 11 in the region Dy in FIG. 12(b).

Therefore, the two-stage injection characteristic is exhibited at medium loads, where the two-stage injection characteristic could not be exhibited in the past, thereby alleviating the sudden increase in the cylinder pressure of the engine and reducing engine combustion noise.

Next, the control operation of the primary injection stroke S1 by the inclined groove 35 will be explained.

Head 24 of plunger 14 illustrated in FIGS. 2 and 3a
As shown in FIG. 13, which is an expanded version of the figure, when the load is low, both ports 12.12a move up and down relative to each other by the reciprocating motion of the plunger 14 along the center line Of, 02, and when the load is high, the ports 12.12a move relative to each other by the rotation of the plunger 14. Move to the left, center line 03,
Both boats 12.12a move up and down along 04.

First, when the load is low, the secondary barrel port 12a is located at the center line 01.
, and primary injection is performed over a relatively short primary injection stroke Sl. At this time, the main barrel port 12 moves up and down along the center line 02, and similarly performs the secondary injection with a short secondary injection stroke S2.

When the load is high, the sub-barrel port 12a moves up and down along the center line 03, performs primary injection over a long primary injection stroke Sl°, and increases the primary injection amount according to the load. The main barrel port 12 moves up and down along the centerline 04 and performs a large amount of secondary injection with a long secondary injection stroke S2°.

Therefore, not only the secondary injection amount but also the primary injection amount is controlled according to the load to further reduce combustion noise. Note that Utility Model Publication No. 50-32651 discloses a technology to control the primary injection amount using an inclined groove, but it is not possible to perform two-stage injection at low loads, and only two-stage injection is possible at high loads. do not have.

(2) Second Embodiment In this second embodiment, the upper lead 50 and the parallel groove 35 formed on the plunger 14 are mainly different from the first embodiment.
Since the only difference is a, we will explain only the differences below,
Identical or equivalent parts are shown with the same reference numerals.

A first diagram showing the head 24 of the plunger 14 of this second embodiment.
4 and 15a, substantially horizontal parallel grooves 35a are formed on the outer circumferential surface 2.
It is cut by 2 from 5 (Fig. 15). This parallel groove 35 is formed at a position below the top surface 17 by a dimension Y, and has a height (width) of B, and has the same height and width in the lateral direction.

Next, the positional relationship between the parallel groove 35a and the barrel port 12 is such that the top surface 17 and the upper edge of the barrel port 12 are aligned and separated by a primary injection stroke S1, which will be described in detail later.

In FIG. 15a, the upper right side of the parallel groove 35a has a top surface 17.
The upper lead 50, which is inclined downward to the right at an angle β from , is a notch. The upper lead 50 is cut to a depth P in FIG. Note that this upper lead 50
may be formed by cutting off the top surface 17, or may be formed not only in the right half of the parallel groove 35a but also over the entire upper part of the parallel groove 35a.

In the above second embodiment, β of the upper lead 50.

Primary injection stroke depending on the load depending on the inclination angle.

-The primary injection stroke S increases and decreases when the load is low.
l becomes shorter, and the primary injection stroke S1 becomes longer when the load is high.

Therefore, in FIG. 16, which shows the dynamic injection timing Tll1 when the Angleich cut is not provided, the dynamic injection timing Tm changes from the characteristic C7 at the time of no negative cocoon to the characteristic C8 at the time of high load with a large delay angle. . Because at high speed, the 15th
This is because the sub boat 12a moves to the right in Figure A, and the compression start time is delayed by the upper lead 50. Note that when an Angleich cut is added, a retard operation is performed as in FIG. 7, and a load timer function is generated.

Next, in FIG. 17(a), two-stage injection is performed in area Da', and (
In b), the primary injection timing Sl is retarded by the action of the upper lead 50 as the rotational speed increases, and as the load increases,
Similarly, the primary injection timing St is advanced due to the effect of the upper lead 50, and two-stage injection is performed in the region Db'.

(Effects of the Invention) As explained above, in the fuel injection pump according to the first invention, the primary injection stroke St and the minimum cross-sectional area A sin of the fuel leak part can be adjusted arbitrarily in advance according to the required characteristics of the engine, and the inclination The groove 35 allows the primary injection stroke Sl to be increased or decreased in accordance with an increase or decrease in load, thereby making it possible to reduce -layer combustion noise.

In the second invention, the primary injection stroke St can be similarly controlled using the upper lead 50 and the parallel groove 35a, which are easy to process, instead of the inclined groove 35.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal cross-sectional view showing the first embodiment of the present invention, FIG. 2 is a side view of the plunger, FIG. 3 is a view in the direction of the ■ arrow in FIG.
Figure a is a view taken in the direction of arrow a in Figure 3, Figure 4 is a longitudinal sectional view of the delivery valve, Figure 5 is a side view of the valve body of the delivery valve, and Figure 6 is a side view of the valve body of the delivery valve.
The figure is a sectional view taken along the line A-A in Fig. 5, Fig. 6a is a longitudinal sectional view showing the Angleich cut, Fig. 7 is a graph of rotation speed vs. dynamic injection timing, Fig. 8 is a stroke diagram of two-stage injection, FIG. 9 is a graph of the rotation speed at which two-stage injection begins to occur versus the primary injection stroke, FIG. 10 is a graph of the transition rotation speed versus the minimum cross-sectional area of the fuel leak part, and FIG. 11 is a graph of the rotation speed versus the fuel injection amount. Fig. 12 is a graph of rotation speed vs. fuel injection amount when the primary injection stroke and the minimum cross-sectional area of the fuel leak part are adjusted, Fig. 13 is a developed view of the plunger head, and Fig. 14 is the plunger of the second embodiment. A side view of the head, FIG. 15 is a view in the direction of the arrow a in FIG. 14, FIG. 15a is a view in the direction of the a in FIG. , and FIG. 17 is a graph of rotation speed versus fuel injection amount when the primary injection stroke and the minimum cross-sectional area of the fuel leak part are adjusted in the second embodiment. 1
0...Pump body, 11...Barrel, 12...Barrel port, 12a...Sub-barrel port, 14...
Plunger, 20... Delivery valve, 26... Lower lead, 27... Fuel relief hole, 35... Inclined groove,
36...Aperture passage, 40...Angleich cut,
50... Upper lead, 35a... Parallel groove Shunka Figure 17 Ogonpu TiBI! ! Maki η (rpm) Nr-Isso- N NN (rp
m) □ Figure 15 Atsushi 15θ diagram

Claims (2)

[Claims] (1) Fuel can be pressurized and pumped by reciprocating the plunger within the barrel, while a diagonal groove-shaped lower lead communicating with the top surface of the plunger is formed on the outer peripheral surface of the head of the plunger, In a fuel injection pump, the fuel injection amount is adjusted by appropriately rotating the plunger and the barrel relative to each other to adjust the communication timing between the lead and a barrel port formed in the barrel,
A sub-barrel port is formed at a position substantially facing the barrel port of the barrel, a fuel relief passage is formed that communicates the top surface of the plunger with the lead, and an auxiliary barrel port is formed on the outer peripheral surface of the head of the plunger at a position substantially opposite to the barrel port of the barrel and the plunger. An inclined groove that can communicate with the auxiliary barrel port is formed in a rotation range, and as the load increases, the plunger head closes the barrel port, and the slanted groove is connected to the auxiliary barrel port. The minimum cross-sectional area A_m_i_n of the fuel leak part of the throttle passage that communicates this inclined groove with the fuel relief passage and the primary injection stroke S1 are set so that the primary injection stroke S1 in which the plunger slides without communicating with By setting the primary injection stroke S1 and the minimum cross-sectional area of the fuel leak part A_m_i_n to be adjustable, two-stage fuel injection can be obtained in any operating range, and the inclined groove can be used to reduce the load. A fuel injection pump characterized in that the primary injection stroke S1 is increased or decreased in accordance with the increase or decrease. (2) While making it possible to pressurize and force-feed the fuel by reciprocating the plunger within the barrel, a lower lead in the form of a diagonal groove is formed on the outer peripheral surface of the head of the plunger and communicates with the top surface of the plunger, In a fuel injection pump, the fuel injection amount is adjusted by appropriately rotating the plunger and the barrel relative to each other to adjust the communication timing between the lead and a barrel port formed in the barrel,
A sub-barrel port is formed at a position substantially facing the barrel port of the barrel, a fuel relief passage is formed that communicates the top surface of the plunger with the lead, and an auxiliary barrel port is formed on the outer peripheral surface of the head of the plunger at a position substantially opposite to the barrel port of the barrel and the plunger. A parallel groove that can communicate with the auxiliary barrel port is formed in a rotation range, a minimum cross-sectional area A_m_i_n of a fuel leak part of a throttle passage communicating with the parallel groove and the fuel relief passage is set to be adjustable, and the plunger head The primary injection stroke S1 in which the plunger slides is set to be adjustable in a state where the barrel port is closed and the parallel groove does not communicate with the sub-barrel port, and the head of the plunger is located at a position where the plunger can communicate with the sub-barrel port. To,
By forming an upper lead that increases the primary injection stroke S1 as the load increases, and by arbitrarily setting the primary injection stroke S1 and the minimum cross-sectional area A_m_i_n of the fuel leak part, two-stage fuel injection can be performed. A fuel injection pump characterized in that the primary injection stroke S1 can be obtained in any operating range, and that the primary injection stroke S1 can be increased or decreased in accordance with an increase or decrease in load using an inclined groove.