JPH0240074A - Fuel injection pump - Google Patents

Abstract

PURPOSE:To abate the extent of combustion noise by forming a groove, interconnectible to a slip port, on the head outer circumferential surface of a plunger, and setting a fuel leak part minimum sectional area being interconnected to this groove and a plunger top face, to be adjustable. CONSTITUTION:A nearly horizontal parallel groove 35 is notched in the head 24 of a plunger 14. This parallel groove 35 is formed in a position lowered as much as a Y size from a top face 17. In addition, a throttle passage 36 is opened to a central part of this parallel groove 35. On the other hand, a primary injection stroke is set up from height (a) of a slip port 12 and the said Y size. In a low speed state, when a pressure-feed speed of the plunger 14 is small and a fuel leak part minimum sectional area of the throttle passage 36 is large, there is a leak action, so that primary injection is brought to nothing, namely, only secondary injection. Consequently, in a medium low speed, high load area, injection timing is delayed as far as a portion for no primary injection, controlling cylinder internal maximum pressure, so that combustion noise is abated.

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, the ignition delay period of the fuel spray is longer during low-speed operation than during high-speed operation. 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 a technique that employs a two-stage injection system as disclosed in Japanese Utility Model Application Publication No. 5930555, for example, is known as a technique for achieving this. It is being

Incidentally, recently there has been a demand for suppressing the cylinder pressure and reducing noise in the medium-low speed and high load ranges where the cylinder pressure is high and the combustion noise is loud, but fuel injection pumps capable of such two-stage injection are still unknown. It has not been done.

Furthermore, there is no known fuel injection pump that can control the injection rate of two-stage injection in a high-speed operating range while delaying the injection timing in a medium-low speed range.

Patent application No. 62292587 as prior art related to this case
There is a number.

(Objective of the Invention) An object of the present invention is to provide a fuel injection pump that can control the injection rate to generate two-stage injection in the high speed range while delaying the injection timing in the medium and low speed range.

(Structure of the Invention) (1) Technical Means The present 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 communicating reed in the form of a diagonal groove, and adjusting the timing of communication between the reed 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 groove is formed on the outer circumferential surface of the head of the plunger to communicate with the slit port within a range of relative rotation between the barrel and the plunger, and this groove communicates with the top surface of the plunger to prevent fuel leakage. The minimum cross-sectional area A min is set to be adjustable, and the primary injection stroke Sl in which the plunger slides in a state where the plunger head closes the barrel port and the groove does not communicate with the barrel port is set in a medium-low speed range. By setting the primary injection stroke Sl and the minimum cross-sectional area of the fuel leak part A ll1in as small as possible so that the primary injection does not occur, retarded first-stage injection without primary injection can be achieved in the medium and low speed range. This is a fuel injection pump that is characterized by exhibiting characteristics and performing two-stage fuel injection in a high-speed range.

(2) Effect Since the primary injection stroke Sl is small, primary injection does not occur in the medium to low speed range where the plunger speed is slow, only secondary injection occurs, and the injection timing is retarded.

When the plunger speed increases in a high-speed range, primary injection occurs even with a small primary injection stroke Sl, and the injection timing is advanced in steps at the time when primary injection occurs.

(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;
On one side, that is, the left side in the figure, there is a horizontally long rectangular slit port extending in the circumferential direction]2 (barrel port)
is formed.

A plunger insertion hole 13 is formed in the axial center of the barrel 11 so as to communicate with the slit 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 an injector (not shown) provided in each cylinder of the engine (not shown). It is designed to be pumped to

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 circumferential surface 25 of the head 24 of the plunger 14, a diagonal groove-shaped lower lead 26 (lead) is provided at an appropriate distance from the top surface 17, extending approximately half the circumference thereof. It has been formed over the years. Further, this lower lead 26 is connected to the plunger 14 through a fuel relief hole 27 extending in the axial direction of the plunger.
It communicates with the top surface 17 of. Note that 28 in FIG. 1 is a supply pipe through which fuel flows to the slit port 12.

Therefore, by rotating the plunger insertion hole 13 relative to the barrel 11, the relative timing of communication between the lower lead 26 of the plunger 14 and the slit port 12 of the barrel 11 is changed, and the period when the slit port 12 is closed 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. , has a function of sucking back fuel by a sucking back stroke Ω1 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.

A metering mechanism consisting of such a combination of the slit port 12 and the lower lead 26 that communicates with the slit port 12 is conventionally known, but this embodiment is not limited to this; It also has a function that can control the injection rate of two-stage injection in the high-speed range while delaying the injection timing in the medium-low speed range. Although this adjustable two-stage injection characteristic is not variable after being set for one day, it can be arbitrarily set according to the characteristics required by the engine.

In FIG. 2, a substantially horizontal parallel groove 35 is cut into the head 24 of the plunger 14 by two points from the outer peripheral surface 25 (FIG. 3). This parallel groove 35 is formed at a height B at a position lower than the top surface ]7 by a dimension Y. In addition, the parallel groove 35
A throttle passage 36 opens across E (Fig. 3) in the center, and the minimum cross-sectional area A of the fuel leak part of the throttle passage 36 is
min, is A min, = B X E − (1
)become.

Next, the positional relationship between the parallel groove 35 and the slit port 12 is such that the top surface 17 and the upper edge of the slit port 12 are aligned and are spaced apart by a primary injection stroke Sl, which will be described in detail later.
Secondary injection stroke S with plunger 14 raised
It separates the 2. The size of the slit port 12 is width b1
The height is set to a. Therefore, the primary injection stroke Sl becomes 5I=Ya (2). Note that the slit port 12 is not limited to the oval-shaped elongated hole shape shown in the drawings with both left and right end portions shaped like arcs, but may be rectangular with a rectangular cross section.

Once the minimum cross-sectional area A min 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 adjusted according to the fuel injection characteristics required by the engine. It is possible to set it to any value,
As described in detail later, the minimum cross-sectional area of the fuel leak part A m
By changing the values of tn and primary injection stroke S, primary injection is stopped in the medium-low speed range where the plunger speed is slow, only secondary injection is generated, and the injection timing is retarded.
It is possible to do so. In addition, the plunger speed becomes faster in the high-speed range, and even with a small primary injection stroke Sl, the plunger speed becomes faster.
It is possible to advance the injection timing in steps at the time when the next injection occurs and the first injection occurs.

The lower lead 26 is inclined at an angle θL at a position lower than the top surface 17 by an amount It's communicating.

The fuel relief passage of the plunger 14 is not limited to the hole-shaped fuel relief hole 27 shown in FIG. 2, but a vertical groove-shaped fuel relief passage may be provided on the outer peripheral surface 25 of the plunger 14.

In the above configuration, since the aforementioned Angleich cut is not formed in the delivery valve 20, the dynamic injection timing FIR changes as the rotational speed N increases in the low to medium speed range, as shown in FIG. As shown in the characteristic CI, the dynamic injection timing FIR gradually becomes slower at a predetermined delay angle (the dynamic injection timing FII? is earlier in the upper part of FIG. 7). Eventually, when the rotational speed N reaches about 300 rpm, the characteristic C1 increases (advances) in a stepwise manner. This phenomenon occurs because as the rotational speed N increases, the plunger speed increases, so primary injection occurs, and the injection timing is advanced by that amount. At high loads, the characteristic C2 occurs, and in this embodiment, the delivery valve 20 (Fig. 1) is not provided with an Angleich cut, so the load timer function retards the dynamic injection timing FIR as the load increases (retard operation). There isn't.

Barrel 11 with said slit port 12 and parallel groove 35
In FIG. 8 showing a two-stage injection stroke by the plunger 14 with a
The lower edge of the slit port 12 coincides with the lower edge of the slit port 12, and in this state, even if the plunger] 4 rises, the fuel in the high pressure chamber 18 is not compressed.

Next, when the top surface 17 and the upper edge of the slit port 12 match in (b), the slit port 12 is closed by the plunger 14, and as the plunger 14 rises, the high pressure chamber 18
θ of (X) begins to be compressed and indicates the injection pattern.
The primary injection 11 starts from the beginning. This primary injection 11 is injected during the primary injection stroke Sl until the parallel groove 35 communicates with the slit port 12, and when the upper edge of the parallel groove 35 and the lower edge of the slit port 12 match in (C), , the slit port 12 and the high pressure chamber]8 communicate through the fuel relief hole 27 and the throttle passage 36, the compression process of the fuel in the high pressure chamber 18 is completed, and the primary injection 11 is completed at 02 of (X). .

In the state of (d), the slit port 12 and the high pressure chamber 18 are in communication through the parallel 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 section △θ゛.

Eventually, at (e), the lower edge of the parallel groove 35 and the slit port 1
When the upper edges of 2 coincide, the high pressure chamber 18 is sealed again.
Secondary injection I2 starts at θ3 of (X). This secondary injection I
2 continues over the section S2, and in (f) the lower lead 26 and the lower edge of the slit port 12 match, and the lower edge is one]
2. Slit port 1 via door 26 and communication hole 37 (Fig. 2)
2 and the high pressure chamber 18 communicate with each other, that is, at 04 of (X) 2
Next injection I2 ends.

Therefore, △θ and △θ° of (X) are Δθ=SI
+a+B...(3)△θ' =a+B...
(4) Become.

As described above, the primary injection I1 is generated by the primary injection stroke Sl, and the rotational speed at which the two-stage injection characteristic (X) begins to occur changes as described above.

In addition, in a low rotation state, the speed at which the plunger 14 pumps is small, and if the minimum cross-sectional area Am1n of the fuel leak part is large, there is a leakage effect, so that the fuel cannot be circulated within a very short time. The primary injection 11 shown in FIG. 8(X) disappears, leaving only the secondary injection I2. Therefore, in the region Da of the medium-low speed and high load range in FIG. 9, which is a graph of rotation speed N - mountain power W, the injection timing is delayed by the absence of the primary injection 11, and the maximum cylinder pressure PmaX is suppressed. Reduce combustion noise. Also, the region D in FIG. 9 is the region (high-speed region) after the characteristics C1 and C2 rise like a star in FIG. 7.
At b, primary injection If occurs, and the initial injection rate is controlled,
dp/dθ (rate of change in cylinder pressure) becomes smaller, and the maximum cylinder pressure p+++ax also becomes lower, reducing combustion noise and Nox (nitrogen oxide) concentration in exhaust gas.

In this embodiment, the delivery valve 2° (Fig. 1)
Since there is no Angleich cut that functions to increase the fuel injection amount at low loads, even in the operating range where both the rotation speed and the fuel injection amount are small, the residual pressure will be reduced as will be explained in detail in the second example below. does not occur.

(2) Second Embodiment Compared to the first embodiment, this second embodiment mainly differs in the shape and arrangement of the fuel relief passage formed in the plunger 14 and the Angleich cut in the delivery valve 20 (FIG. 1). Since the only difference is the provision of , only the differences will be explained below, and the same or equivalent parts will be illustrated with the same reference numerals.

First, in Figure 10, collar 33 has an Angreich power button 4.
0 is a notch. Therefore, when the valve body 30 shown in FIG. It has become. When the amount of fuel sucked back decreases, the residual pressure in the pipe from the delivery valve 20 to the injector increases by that amount, and as a result, the amount of fuel injection increases in accordance with the increase in residual pressure.

In the above second embodiment, fuel injection ff1Q-in-pipe residual pressure P
As shown in FIG. 11, which is a graph of r, due to the addition of residual pressure in the pipe by the Angleich cut 40 of the delivery valve 20, the characteristic C1 at low speed, the characteristic C2 at medium speed, and the characteristic C at high speed.
3, as the fuel injection amount Q decreases, the residual pressure in the pipe Pr
becomes higher.

Therefore, as shown in Fig. 12, the dynamic injection timing FIR at light load is approximately averagely advanced over the entire rotation speed range as shown in characteristic CI, reducing blue-white smoke during high-speed no-load operation (high idle). . Next, at high loads, approximately 3
000 rpm, advance in steps near
IR will be delayed.

As shown in FIG. 13, in addition to the effects of the regions Da and Db, the rotational speed N is
A two-stage injection characteristic occurs in a region where one output W is small, that is, in the region DC, and the noise in the region DC is reduced.

(3) Third Embodiment FIG. 14 shows a fuel injection pump for a diesel engine according to a third embodiment of the present invention. In FIG. A barrel is fitted and fixed in the pump body 10, and a main port 42 (barrel hoard) in the form of a through hole is formed on one side of the barrel 11, that is, on the left side in the figure. A sub port 42a (barrel port) in the form of a small diameter through hole is formed on the right side of the barrel 11 so as to face the barrel port 2. Both ports 42.42a communicate with the annular passage 19 between the barrel 11 and the body 10.

A plunger insertion hole 13 is formed in the axial center of the barrel 11 so as to communicate with the main port 42. A plunger 14 is fitted into the plunger insertion hole 13 so as to be relatively rotatable and slidable.
By reciprocating in the axial direction by the spring force of the plunger spring 15 and the cam action of the fuel cam 16,
The fuel sucked into the high pressure chamber 18 formed on the top surface 17 is pressurized and delivered to the engine (
The fuel is fed under pressure to injection nozzles or injectors (not shown) provided in each cylinder of the cylinder (not shown).

Further, in FIG. 14, reference numeral 21 is a plunger rotation wheel attached to the plunger 14 so as to be able to engage with it in the circumferential direction, and the plunger 14 is engaged with the rotation wheel 21 by a metering operator 22. By appropriately pushing and pulling the rack gear 23, it is relatively rotated within the barrel 11, thereby performing a predetermined metering action. That is, the outer circumferential surface 25 of the head 24 of the plunger 14 has the markings shown in FIG.
As shown in FIG. 15, a diagonal groove-shaped lower lead 26 is formed at an appropriate distance from the top surface 17 over approximately half the circumference thereof. 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. Note that 28 in FIG. 14 indicates the main port 42 and the sub port 42.
This is a supply pipe 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 main port 42 of the barrel 11 is changed, and the period when the main port 42 is closed is changed. By adjusting, the amount of fuel to be injected is adjusted.

A metering mechanism consisting of a combination of the main port 42 and the lower lead 26 which communicates with the main port 42 is conventionally known, but this embodiment is not limited to this. Similarly to the first embodiment, the fuel injection system also has a function of controlling the injection rate of two-stage injection in the high speed range while delaying the injection timing in the medium and low speed range.

Although this adjustable two-stage injection characteristic is not variable once it is set, it can be arbitrarily set according to the characteristics required by the engine.

15 and 15a, a parallel groove 43 (groove) is cut in the head 24 of the plunger 14 by two points from the outer peripheral surface 25 (FIG. 3). This parallel groove 43 is formed at a height B at a position lower than the top surface ]7 by a dimension Y. This parallel groove 43 causes the plunger 14 to rotate, and the position of the sub port 42a of the barrel 11 to move relatively left and right, so that the primary injection stroke Sl can be increased or decreased according to the load, as will be described in detail later. It has become. In addition, the parallel groove 4
3 may be replaced by an inclined groove.

Further, a vertical groove 44 is formed at the right end of the IL row groove 43, and the minimum cross-sectional area A min of the fuel leak part where the vertical groove 44 and the parallel groove 43 communicate is determined by the depth of the vertical groove 44 being parallel to E1. If the height of the groove 43 is B, then A min, = E x
B - becomes (5). The minimum cross-sectional area A min of the fuel leak portion is smaller than the cross-sectional area of the sub-port 42a, and is set so as to be able to exert a fuel throttling effect in a high rotation range, as will be described in detail later.

As mentioned above, the plunger 14 is connected to the center line CLI in FIG.
to Cl3, both ports 4242a move relative to each other at a port movement angle θp, and the parallel groove 43 and the sub port 42a do not communicate with each other near the center line CL2 where the maximum injection amount is reached. There is.

Next, the positional relationship between the parallel groove 43 and the sub-port 42H is as follows:
The top surface 17 and the upper edge of the sub-port 42a are aligned and separated by a primary injection stroke Sl, which will be described in detail later. The diameter of the sub-port 42a is set to d. Therefore, the primary injection stroke Sl is as follows: Sl = Y-d (6).

Once the minimum cross-sectional area A min of the fuel leak part and the primary injection stroke Sl shown in Equations (5) and (6) above are set, they are not variable, but can be adjusted according to the fuel injection characteristics required by the engine. It can be set to any value,
As in the case of the first embodiment described above, by changing the values of the minimum cross-sectional area A mjn of the fuel leak part and the primary injection stroke Sl, the primary injection is stopped in the medium and low speed range where the plunger speed is slow, and It is possible to generate only the next injection and retard the injection timing. In addition, in the high speed range, the plunger speed increases, primary injection occurs even with a small primary injection stroke Sl, and it is possible to advance the injection timing in steps at the time when primary injection occurs.

In the above configuration, since the aforementioned Angleich cut is not formed in the delivery valve 20, the dynamic injection timing FIR changes in steps as the rotational speed N increases as shown in FIG. advance in the same direction.

In FIG. 16, which shows a two-stage injection stroke using the barrel 11 with the sub-port 42a and the plunger 14 with the parallel groove 43, the top surface 17 of the plunger 14 is in contact with the main port 42 before reaching the state of (a). In this state, the fuel in the high pressure chamber 18 is not compressed even if the plunger 4 rises.

Next, when the top surface 17 and the upper edge of the main port 42 match in (a), the barrel port 42 is closed by the plunger 14,
As the plunger] 4 rises, the fuel in the high pressure chamber 18 begins to be compressed, and from θ1 to 1 of (X) indicating the injection pattern.
Next injection 11 begins. This primary injection (1) is injected during the primary injection stroke Sl until the parallel groove 43 communicates with the sub port 42a, and in (b) the upper edge of the parallel groove 43 and the lower edge of the sub port 42a are aligned. Then, the fuel relief hole 27, the vertical groove 4
4 (FIGS. 14 and 15a), the secondary port 42a and the high pressure chamber 18 communicate with each other, the compression stroke of the fuel in the high pressure chamber 18 is once completed, and the primary injection 11 is completed at θ2 in (X).

In the state of (e), the sub port 42a and the high pressure chamber]8 are in communication through the parallel groove 43 and the fuel relief hole 27, so even if the plunger 14 moves up, the fuel in the high pressure chamber 18 is not compressed, and the fuel in the high pressure chamber [X ) Fuel injection stops in the △θ゛ section. Eventually, as shown in (d), when the lower edge of the parallel groove 43 and the upper edge of the sub boat 42a coincide, the high pressure chamber 18 is sealed again, and the secondary injection I2 begins at C3 in (X). This secondary injection I2 continues over the section of the secondary injection stroke S2 during which both ports 42.degree. 42a are closed by the plunger 14 and the lower lead 26 communicates with the main port 42.

In (c), the lower edge of the lower lead 26 and the main port 42 match, and the main port 42 and the high pressure chamber 18 communicate with each other via the lower lead 26 and the communication hole 37 (FIG. 14), that is, 0 in (X).
4, the secondary injection I2 ends.

Therefore, 80 and 80° of (X) are △θ−31,
+d+B ・・・(7)△θ' =d×B ・・・
(8) Become.

Here, the angles Δθ and θ° are angles obtained from the cam lift characteristics corresponding to each dimension on the right side of the above equation.

In the case of the third embodiment described above, as in the case of the first embodiment shown in FIG. occurs.

(4) Fourth Embodiment This fourth embodiment is an embodiment in which the delivery valve 20 is provided with the Angleich cut 40 shown in FIG. 10 in the third embodiment shown in FIGS. 13 to 15a.

Therefore, in the fourth embodiment, the dynamic injection timing FIR is 12th.
The characteristics CI and C2 in the figure become the same, and the injection pattern becomes the same as in FIG. 13.

(Effect of the invention) As explained above, in the fuel injection pump according to the present invention,
The primary injection stroke St is set small enough that primary injection does not occur in the medium and low speed range, and this primary injection stroke Sl
By appropriately setting the fuel leak portion minimum cross-sectional area A min, it is possible to exhibit retarded first-stage injection characteristics without primary injection in the medium-low speed range, and to exhibit two-stage fuel injection in the high-speed range. Therefore, in the medium and low speed range where the plunger speed is slow, primary injection does not occur and only secondary injection occurs, making it possible to retard the injection timing and reduce the maximum cylinder pressure P.
IIlaX, can be suppressed, and combustion noise can be reduced.

When the plunger speed increases in the high-speed range, primary injection occurs even with a small primary injection stroke Sl, and at the time when primary injection occurs, the injection timing can be advanced in steps, and 2 It is possible to exhibit a staged injection pattern, control the initial injection rate of two-stage injection, and achieve low noise and NOX (nitrogen oxide).

[Brief explanation of the drawing]

FIG. 1 is a longitudinal 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.
The figure is a longitudinal cross-sectional view of the delivery valve, Figure 5 is a side view of the valve body of the delivery valve, Figure 6 is a cross-sectional view taken along line A-A in Figure 5, Figure 7 is a graph of rotation speed vs. dynamic injection timing, and Figure 8 is a graph of rotation speed vs. dynamic injection timing. The figure is a stroke diagram of two-stage injection, Figure 9 is a graph showing the injection pattern,
Figure 0 is a schematic diagram of the structure of the Angleich cut, Figure 11 is a graph of fuel injection amount vs. cylinder residual pressure, Figure 12 is a graph of rotation speed vs. dynamic injection timing of the second embodiment, and Figure 13 is a graph of the second embodiment. Graph showing the injection pattern of the embodiment, FIG. 14 is a longitudinal sectional view showing the third embodiment, FIG. 14a is a side view of the plunger, and FIG.
The figure is a view from arrow a in Fig. 14a, and Fig. 15a is a view from a in Fig. 15.
The arrow view and FIG. 16 are stroke diagrams of two-stage injection. ]C0・
・Pump body, 11... Barrel, 12... Slit port, 14... Plunger, 20... Delivery valve, 26... Lower lead, 27... Fuel relief hole,
35... Parallel groove, 36... Throttle passage Patent applicant Yanmar Diesel Co., Ltd. Figure 16 (a) (b) (c) (d) (e)

Claims (1)

[Claims] (1) Fuel can be pressurized and pumped by reciprocating the plunger within the barrel, and an oblique groove-shaped 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 amount of fuel to be injected is adjusted by appropriately rotating the plunger and the barrel relative to each other to adjust the communication timing between the lead and a slit port of the barrel formed in the barrel. A groove that can communicate with the slit port within the relative rotation range of the barrel and the plunger is formed on the outer peripheral surface of the head, and a fuel leak portion that communicates with the top surface of the plunger has a minimum cross-sectional area Amin. set to adjustable,
The primary injection stroke Sl in which the plunger slides in a state where the plunger head closes the barrel port and the groove does not communicate with the barrel port is set small enough to prevent primary injection from occurring in the medium and low speed range, and this 1. Next injection stroke Sl
and minimum cross-sectional area of fuel leak part Amin. A fuel injection pump characterized in that, by appropriately setting , a retarded first-stage injection characteristic without primary injection is achieved in a medium-low speed range, and a two-stage fuel injection is achieved in a high-speed range.