JPH08200181A - Fuel injection pump for diesel engine - Google Patents

Abstract

PURPOSE: To increase torque on the low speed side simultaneously with the increase of an output on the high speed side by a method wherein when closing movement is low speed rotation, a given amount of fuel is reduced and further during high load running, the initial stage of the fuel actual forced feed of a plunger is delayed. CONSTITUTION: A cut stepped part 8 shortened in an axial direction and further an upper lead part 9 are arranged at a part of the tip forced feed side of a plunger 7. A small hole support 11 is opened to the side corresponding to the cut steeped part 8 of the tip part of the plunger 7 of a plunger barrel 10 and a large hole main port 12 is opened to the vicinity of the side corresponding to an upper lead part 9. During rotation of an engine, the cut steeped part 8 of the plunger 7 is moved over a position, to which the support 11 is opened, and moved to above in an axial direction and the support 11 is closed with the wall surface of the plunger 7. When the closing movement is low speed rotation, a given amount of fuel is reduced, and during high load, through rotation of the plunger 7 in a peripheral direction, the upper lead 9 and the main port 12 are overlapped with each other to delay the initial stage of the fuel actual forced feed of the plunger 7.

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 for a multi-cylinder short stroke diesel engine, and more particularly to a fuel injection pump in which a main port and a sub port are formed in a plunger barrel as fuel intake and exhaust holes.

[0002]

2. Description of the Related Art Generally, a short stroke engine capable of lowering an average piston speed as compared with a long stroke engine can easily achieve high output due to high rotation and high speed and high output. Was satisfied, but the torque retention performance at low speed rotation was inferior. If a short stroke engine that can reduce the weight of an engine with the same output is used in a vehicle traveling on a soft ground such as an agricultural tractor, the weight of the entire vehicle can be reduced and it is effective for improving the running performance at high engine speed. is there. However, as a drawback, once the engine speed decreases, the output decreases greatly, and it becomes necessary to change the traveling vehicle speed to a low speed stage, or when the power is taken out through the PTO shaft to work, the work load is reduced. Etc. are required, and it may be troublesome.

For this reason, in some short-stroke diesel engines, a timer (injection timing automatic advance device) for adjusting the timing of fuel injection is separately attached in order to improve torque maintenance at low speed rotation. As described above, in the case where the timer is separately attached, the cost is high and the size and weight are increased, which will be described later in detail.

Further, the diesel engine has an optimum fuel injection timing according to its operating condition, such that the injection timing is delayed at low engine speed, the injection timing is accelerated at high engine speed, and the injection timing is accelerated at light load. It is necessary to change the injection timing late when the load is heavy. However, in a general engine in which the drive shaft that drives the fuel injection pump is integrated, the "pressure feed start" by the plunger of the fuel injection pump is constant regardless of the rotation and load, and the "injection delay" actually causes The injection timing of is contrary to the optimum injection timing.
As indicated by the solid line, the angle advances when the engine speed is low and the angle is retarded when the engine speed is high. Therefore, if the injection timing is set to be optimal on the high rotation side, the injection angle advances on the low rotation side, which leads to an increase in fuel consumption, smoke, and noise.

In an actual engine, the fuel injection timing is adjusted to the high speed rotation side in the case of a high speed specification engine and the fuel injection timing is adjusted to the low speed rotation side in a low speed specification engine while observing the operating conditions. Or, so that moderate performance is obtained at both low speed and high speed,
The fuel injection timing is set at a compromised middle point.
In particular, when used for agricultural tractors, it is used over a wide range of engine speeds, but stickiness is required by maintaining torque at low speeds, so it tends to be set with emphasis on the low speed side. It was difficult to pursue output improvement performance.

In order to solve these problems, as an example, a "mechanical fuel injection timing automatic advance timer" is attached, and the centrifugal force of the rotating weight imparts a phase difference between the drive shaft and the driven shaft to increase the rotation. Although the one that advances the driven shaft side to advance the fuel injection timing has been implemented, the disadvantage of this "timer" is that if it is additionally set to the conventional engine, it requires a major modification such as the governor case, The number of parts increases and the unit price increases, the size and weight increase compared to the conventional engine, it goes against the weight and size reduction, and the timer function corresponds only to the engine speed, and it responds to load fluctuations I didn't.

On the other hand, in the agricultural tractor, as described above, it is the most important point that high torque is required on the low speed side while the torque characteristic withstands a sudden load change and overload. In addition, tractors are becoming fully equipped from the standpoint of improving product efficiency such as work efficiency and comfort, and demand for increased engine output at high speeds has also become stronger. Most of the agricultural tractors used long strokes from the viewpoint of "focusing on low-speed rotation type torque". Certainly, if it is a low speed rotation type engine, there are some advantages over the short stroke engine due to piston heat load, noise, etc., but the piston speed becomes faster in response to the demand for high speed and high output, for example, A 100 mm stroke engine could not be expected to rotate at more than 3,600 rpm.

According to the present invention, the basic engine is a short-stroke diesel engine capable of realizing high-speed rotation and high-output, and high output on the high-speed side is realized while at the same time supplementing "mechanical fuel injection timing automatic advance timer" and the like. It is intended to increase the torque on the low speed side by using the "fuel injection pump with automatic injection timing control" that can change the "actual pressure feed start" of the injection pump according to the rotation and load of the engine without using a machine. is there. This "fuel injection pump with automatic injection timing control" does not require auxiliary equipment such as a "timer" and has a timer function in the pump itself, so the device can be installed without major changes on the engine side. be able to.

[0009]

SUMMARY OF THE INVENTION The present invention is intended to solve the above-mentioned problems of the conventional device,
The following technical measures were taken. That is, a plurality of short stroke pistons 1, 1. ． Each of the combustion chambers 3,3. ． Nozzle attached to 4. ． And plunger pump type fuel injection pump 5, 5. ． Between the injection pipes 6,6. ． In which a predetermined amount of fuel is pressure-fed from the fuel injection pump 5 to the nozzle 4 side, a cutting step portion 8 shortened in the axial direction is provided in a part of the tip end pressure-feeding side of the plunger 7 of the fuel injection pump 5, An upper lead 9 which is a chamfer is provided on the other end of the plunger 7 at the tip pressure feeding side. The subport 11 of the hole is opened, and the main port 12 of the large diameter hole is opened in the vicinity of the side corresponding to the upper lead 9, and the cut step portion 8 of the plunger 7 exceeds the opening position of the subport 11 in the axial direction when the engine rotates. To close the sub port 11 on the wall of the plunger 7,
If this closing movement is a low speed rotation, reduce the predetermined amount of fuel,
Further, when the load is high, the plunger 7 is rotated in the circumferential direction to overlap the upper lead 9 and the main port 12 to delay the start of actual fuel pressure feeding of the plunger 7. did.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An agricultural tractor 13 is shown in the figure, and the present invention is folded into a diesel engine 2 mounted between the front wheels 14 of the machine body. Embodiments of the present invention will be described in detail below with reference to the drawings. However,
The dimensions, materials, shapes, relative positions, etc., of the components described in this embodiment are not intended to limit the scope of the present invention thereto, unless otherwise specified, and simply It's just an example.

The entire agricultural tractor 13 will be described with reference to FIG. A radiator 15 is arranged in front of the engine 2 of a frame (not shown) on which the engine 2 is mounted, and air is sucked and cooled by a fan 16 at the rear. A clutch housing 17 containing a main clutch (not shown) is attached to the rear of the engine 2, and a front transmission case 18 and a rear transmission case 19 are attached to the rear of the clutch housing 17.

A hydraulic cylinder case 20 is attached to an upper portion of the rear transmission case 19, and lift arms 21 and 21 are vertically moved up and down by an internal hydraulic piston and a cylinder (not shown). Rear axle cases 22, 22 are provided on both left and right sides of the rear transmission case 19 so as to extend outward, and rear wheels 23, 23 are provided at the protruding ends.
Is installed.

The upper and inner sides of the rear wheels 23, 23 are covered with fenders 24, 24.
Seats 25 are provided between 24. A steering wheel 26 for steering the front wheels 14 and 14 is provided in front of the driver sitting in the seat 25, and a floor 27 on which a foot is placed is provided at a lower front portion of the seat 25. The front, upper and side of the engine 2 are covered with a bonnet 28, and the rear is covered with an instrument panel 29 and a rear cover 30.

The driving force of the engine 2 is transmitted through the main clutch in the clutch housing 17 and then to the front transmission case 18.
And transmission gears (not shown) in the rear transmission case 19.
Then, the traveling speed and the rotation speed of the PTO shaft 52 are increased / decreased to drive the front and rear wheels 14 and 23 to travel, and the drive rotation speed to a working machine (not shown) attached to the end of the machine body is adjusted. And work.

FIG. 4 is a front sectional view of the diesel engine 2, in which a plurality of pistons 1 provided in the front-rear direction, a crank shaft 31 to which a connecting rod 33 is attached, and the like are mounted, and a pump case 34 is provided on the right front side of a cylinder body 32.
Bulge integrally, and a plurality of fuel injection pumps 5, 5 ,. ． And pump cam shaft 35
Although not shown, the pump cam shaft 35 is driven and rotated with a predetermined phase difference with respect to the crankshaft 31 by the power that drives and transmits the driving rotation of the crankshaft 31 through a plurality of gears.

The pump case 34 has an upper opening,
This opening is closed by a lid body 36, and a cylindrical tubular portion 37 is projectingly provided on the pump cam shaft 35 side below the lid body 36, and the plunger barrel 10 is moved in the vertical and rotational directions in the tubular portion 37. It is installed impossible. A fuel intake port 38 is provided on the outer side of the lid body 36, and the fuel in the fuel tank 39 is sent via a feed pump 40. The fuel that has passed through the fuel intake port 38 is the upper portion of the plunger barrel 10. The pressure reaches the main port 12 that is open at a pressure of approximately normal pressure.

Main port 12 of plunger barrel 10
A subport 11 having a diameter of about 0.4 mm is opened on the opposite side. The plunger 7 is provided in the central hole 41 portion of the cylindrical plunger barrel 10 that is open vertically in the axial direction.
The central hole 41 is operably attached in the axial direction and the rotational direction. The upper end of the plunger 7 moves up and down and rotates in the vicinity of the main port 12 and the sub port 11 of the plunger barrel 10. As will be described later in detail, the fuel is automatically adjusted to the combustion chamber 3 by adjusting the amount of the fuel. It is pumped.

At the upper end of the plunger 7, a cutting step portion 8 shortened in the axial direction is provided at a part on the side of the sub-port 11 on the tip pressure feeding side, and another portion on the side of the main port 12 on the tip pressure feeding side of the plunger 7. An upper lead 9 which is a chamfer inclined in a V shape is provided on the circumferential portion. This top lead 9
A main lead 42 which is spirally inclined is provided in a groove shape on the outer periphery of the plunger 7 below the core hole 5 of the plunger 7.
It communicates with 3.

The core hole 53 of the plunger 7, the main port 12 and the sub port 11 are communicated with the fuel intake port 38 through the fuel. Then, when the plunger 7 rises in the center hole 41 of the plunger barrel 10, the center hole 41 of the plunger barrel 10 moves from the main port 12 to the center hole 41.
When the upper edge of the plunger 7 passes through the upper edge of the hole of the main port 12, the compressed inflow of the fuel flowing into the inner upper portion is started, and then a part of the main lead 42, which is a groove, is moved to the hole of the main port 12. The fuel pumping ends when it touches the lower edge. Since the main lead 42 is spirally inclined in the effective stroke at this time, the effective stroke changes when the plunger 7 is rotated.

The rotation of the plunger 7 will be described. A driving face 43 is provided below the plunger 7, and a control sleeve engaged with the driving face 43 is rotated by a control rack to rotate the plunger 7 to control the injection timing and the injection amount. A developed view of the effective stroke is shown in FIG. At the no-load state position “A”, the plunger 7 is rotated to a position where the distance between the main port 12 and the main lead 42 is close, and even if the plunger 7 is pushed up by the cam 44 of the pump cam shaft 35, there is almost no effective stroke. Therefore, there is little fuel pumping. From the rated rotation position “B” to the maximum torque position “C”, the effective stroke is reduced by the notch portion of the upper lead 9 and the fuel pumping is reduced. At the starting position "D", the fuel is pressure-fed over substantially the entire effective stroke. As shown in the development view of FIG. 6, the upper lead 9 which is a V-shaped notch is composed of a gentle inclination of about 30 degrees and a steep inclination of about 90 degrees. However, this angle, direction, and setting position will naturally change if the required fuel differs depending on the engine characteristics and engine specifications, and the shape of the upper lead 9 is not limited to the embodiment, and the effective stroke is If it can be changed to the decreasing side, the inclination angle and the setting position may be changed.

A shim 45 and a roller 46 are arranged between the lower end of the plunger 7 and the cam 44. The thickness of the shim 45 is changed to adjust the start of actual pressure feeding, and the roller 46 drives the cam 44. It is devised to easily convert the rotational force into an axial movement of the plunger 7. The plunger 7 is a return spring and is constantly pressed toward the cam 44. The cam 44 provided on the pump cam shaft 35 is a substantially linear tangent cam in the base engine, but in the present invention, it is a substantially arc-shaped arc cam.

With this arc cam, 1.5
Average oil transfer rate for a liter diesel engine 2 7.
What was 85 cubic mm / degree was lowered to 6.6 cubic mm / degree. As a result, the ignition delay can be shortened and the main combustion section can be lifted compared to the base engine, which reduces fuel consumption and
x and noise were improved. However, the noise of 1 decibel worsened at the torque point smoke and the maximum no-load rotation. In order to solve this, an upper lead 9, a subport 11, and a cut step portion 8 which will be described in detail below are provided.

The fuel pressurized by the effective stroke of the plunger 7 passes above the central hole 41 of the plunger barrel 10, opens the delivery valve, and reaches the nozzle 4 via the injection pipe 6. The main port 12 is closed by the first upper edge surface 47, which is the uppermost edge of the plunger 7, at the no-load position A or at the starting position D, and at the rated output position B or at the maximum output position B, which is closed by the upper lead 9 later. There is a case at the torque position C, which is performed by rotating the control sleeve engaged with the driving face 43 under the plunger 7 by the control rack as described above. That is, the load is automatically measured by the governor rotation to determine which of the plungers 7 is to be operated and to what extent, and the increase / decrease of the fuel is determined according to the load state so as to supply the required fuel. When the upper lead 9 is not provided, the pumped fuel is simply reduced in the low load and increased in the high load, but the first upper edge surface 47 of the plunger 7 is increased.
Considering the setting part of the barrel upper lead 9 which is notched in a V shape, the closing position of the main port 12 is delayed at the rated output position B and at the maximum torque position C, so that when the load is relatively low, The injection timing is advanced by accelerating the pumping start, and the injection timing is retarded by delaying the pumping start when the load is high.

This technically realizes the function of advancing the injection timing change due to the change of the load, which has been difficult in the past, when the load is low and retarding it when the load is high. Next, the subport 11 provided on the upper portion of the plunger barrel 10 will be described. The sub-port 11 is a small hole of about 0.4 mm opened on the opposite side of the main port 12, and is provided with a cutting step portion 8 that is an upper portion of the plunger 7 cut out in a half-moon shape in plan view,
Exert its effect.

When the first upper edge surface 47 of the plunger 7 exceeds the upper edge of the hole of the main port 12 and the effective stroke for pressurizing the fuel is started, the sub port 11 serves as a throttle. More specifically, the first upper edge surface 47 is equal to or higher than the subport 11 at this time, but the second upper edge surface 4
The fuel cell 8 is located below the sub-port 11, and the fuel slightly escapes from the sub-port 11 even within the effective stroke. That is, when the diesel engine 2 rotates at a low speed, the rising speed of the plunger 7 is slow, and the change in pressurization is slow even when the main port 12 of the plunger barrel 10 is closed. Therefore, the fuel escapes through the small-diameter subport 11 and the pressure rises. Then, the pressure rise starts when the plunger 7 is further raised to close the subport 11 with the second upper edge surface 48, and the fuel pressure feeding to the nozzle 4 side is started.

When the diesel engine 2 rotates at a high speed, the ascending speed of the plunger 7 is high, and even if the sub port 11 is opened when the main port 12 of the plunger barrel 10 is closed, this sub port 11 acts as an orifice.
When the pressure changes abruptly, the pressure escaping to the downstream side of the sub-port 11 is throttled. Therefore, even when the sub-port 11 is opened, the pressure feeding of the fuel to the nozzle 4 side is started.

This causes a difference in the start of the actual pressure-feeding of fuel depending on the rotational speed of the diesel engine 2. The fuel injection is retarded at a relatively low speed, and the fuel injection is advanced at a relatively high speed. , Has technically realized the action of approaching an ideal injection pattern. In the illustrated example, the hole diameter of the subport 11 is set to 0.4 mm, but this naturally changes when the outer diameter dimension of the plunger 7, the total stroke dimension, the number of rotations used, etc. differ, and it is sufficient if the throttling effect is produced. It is not limited only to the hole diameter shown in the figure.

In the diesel engine 2 of our company, in the conventional standard pump plunger without the sub-port 11 and the cutting step portion 8, the smoke concentration at the maximum torque point is No. 4 in Bosch number, and further increase in torque causes smoke. This causes a decrease in pollution and engine durability. Furthermore, in order to increase the torque in the low speed range, the smoke concentration should be made as low as possible, but if the injection system and combustion system of the base engine are simply adjusted to the low speed range, the most important high speed side rated point Performance deteriorates. By providing the sub-port 11 and the cutting step portion 8, the peak of the initial combustion (premixed combustion) is reduced and the main combustion (diffusion combustion) is increased to shorten the combustion period, and the rapid rise of the combustion pressure is reduced. ing.

Also, in the base engine, the static optimum fuel injection timing is required to be 19 degrees before top dead center at the rated point and 14 degrees before top dead center at the torque point. 17 degrees, which is important, is set. In order to improve smoke at the torque point, it is necessary to send the fuel injection timing up to 14 degrees. In this invention, by setting the sub-port 11, the cutting step portion 8 and the upper lead 9, a timer function of 7.6 degrees in speed and 4.8 degrees in load is added at the maximum torque rotation speed as compared with the standard pump. Although noise reduction at the torque point and improvement of Nox were observed, conversely, noise at the torque point smoke, rated point and maximum unloaded rotation increased, and fuel consumption at the rated point deteriorated. In order to improve this, the present invention changes the inner diameter of the injection pipe 6 from 1.2 mm to 2.0 mm.
The injection rate was optimized by increasing the inner diameter to mm and changing the opening area characteristics of the nozzle 4. The injection rate is changed from the nozzle number 005 of the base to the nozzle number 027,
Fuel was reduced in the early stage and increased in the middle and late stages.

The fuel pressurized by the effective stroke of the plunger 7 passes above the central hole 41 of the plunger barrel 10, opens the delivery valve, reaches the nozzle 4 via the injection pipe 6, and reaches the swirl chamber of the cylinder head 49. Reaching the combustion chamber 3 of the formula. FIG. 7 shows the combustion chamber 3 of the present invention, and FIG. 8 shows the conventional combustion chamber 3c of the present invention.

The combustion chamber 3 has a ceiling part 3a having a semi-circular dome shape and a large radius as shown in the figure, and an upright wall cylinder part 3 having the same diameter.
The hot plugs 50 are attached to the upper and lower openings of FIG. Conventional combustion chamber 3c
Has a hemispherical egg-shaped ceiling shape. The hot plug 50 is provided with an inclined opening 51 for ejecting a combustion gas mixed with fuel to the piston 1 side. In the conventional hot plug 50a of the present invention, the injection port 51a is ejected at an angle of 38 degrees with respect to the upper surface of the piston 1, but the hot plug 50 of the present invention is ejected at a tight inclination angle of 41 degrees. Further, this injection port 51 has an area of 1.3% compared to the area of the piston 1 in the conventional product, but in the present invention, it is reduced to 1.1% to restrict the injection of combustion gas, and the injection port 5
The exhaust temperature is lowered by performing ideal combustion, such as increasing the jet outlet speed from No. 1 or giving resistance to the jet of combustion gas to achieve high output and high torque in spite of clean exhaust. .

As described above, by improving the fuel feeding rate, the injection timing, and the injection rate, the smoke in the low speed range changes from Bosch number 4 to Bosch number 2.3, that is, an improvement of 1.7. I was able to. Furthermore, it was possible to reduce noise and exhaust gas components, especially Nox, while maintaining fuel efficiency. Especially, the noise was improved over the whole area, and the idle noise was reduced by 3.5 dB.

[0033]

As described above, according to the present invention, the cutting step portion 8 shortened in the axial direction is provided in a part of the plunger 7 at the tip pumping side with respect to the standard plunger of the base engine, and further the tip of the plunger 7 is provided. An upper lead 9 which is an inclined chamfer is provided on the other portion on the pressure feeding side, and a small diameter sub-port 11 is provided on the side corresponding to the cut step portion 8 at the tip of the plunger 7 of the cylindrical plunger barrel 10 for inserting and supporting the plunger 7. And a large-diameter main port 12 is opened in the vicinity of the side corresponding to the upper lead 9, and the cut step portion 8 of the plunger 7 moves axially upward beyond the opening position of the sub port 11 when the engine rotates. The sub-port 11 is closed by the wall surface of 7, and a predetermined amount of fuel is reduced when this closing movement is a low speed rotation. Further, when the load is high, the plunger 7 is rotated in the circumferential direction to move upward. Since the slow start fuel actual pumping of the plunger 7 by polymerizing the lead 9 and the main port 12,
The amount of fuel pumped to the nozzle 4 side is set to the diesel engine 2
Can reduce fuel consumption at low speed to improve smoke at low speed range, reduce noise at high speed range and exhaust gas components especially No.
x can be reduced, and torque can be increased and maintained without increasing fuel consumption. Furthermore, since this performance improvement can be achieved by simply processing around the plunger 7 without attaching a special fuel injection timing automatic advance timer, when using it as an engine of a vehicle traveling on a soft land such as an agricultural tractor, the weight of the engine is reduced. Since there is almost no increase, it is easy to promote use as a new-type vehicle without giving much consideration to the overall balance.

[Brief description of drawings]

FIG. 1 is an enlarged cross-sectional view of a main part.

FIG. 2 is a cross-sectional view of a main part showing a fuel pressure feeding start state when the engine rotates at a low speed.

FIG. 3 is a cross-sectional view of a main part, showing a fuel pressure feeding start state at the time of engine high speed rotation.

FIG. 4 is a front sectional view of the entire diesel engine.

FIG. 5 is a side view of the entire agricultural tractor on which the engine is mounted.

FIG. 6 is an operation state development explanatory diagram showing the operation of the main configuration.

FIG. 7 is an enlarged cross-sectional view of a combustion chamber that is another main part of the present invention.

FIG. 8 is an enlarged sectional view of a combustion chamber of a conventional base engine.

FIG. 9 is a comparison diagram of an ideal engine fuel injection pattern and an actual engine fuel injection pattern.

[Explanation of symbols]

 1 Piston 2 Diesel Engine 3 Combustion Chamber 4 Nozzle 5 Fuel Injection Pump 6 Injection Pipe 7 Plunger 8 Cutting Stage 9 Upper Lead 10 Plunger Barrel 11 Sub Port 12 Main Port

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification number Internal reference number FI Technical display location F02M 45/00 E 59/10 C 59/28 F (72) Inventor Toru Shinomiya Toyo Iyo-gun, Ehime Prefecture No. 1 Hachikura, Ichi, Agricultural Machinery Co., Ltd.

Claims (1)

[Claims] 1. A plurality of short stroke pistons 1, 1. ． Each of the combustion chambers 3,3. ． Nozzle attached to 4. ． And plunger pump type fuel injection pump 5, 5. ． Between the injection pipes 6,6. ． In which a predetermined amount of fuel is pressure-fed from the fuel injection pump 5 to the nozzle 4 side, a cutting step portion 8 shortened in the axial direction is provided in a part of the tip end pressure-feeding side of the plunger 7 of the fuel injection pump 5, , An upper lead 9 which is a chamfer is provided on the other end of the plunger 7 on the pressure feeding side,
A sub-portion 11 having a small diameter hole is opened on the side corresponding to the cut step portion 8 at the tip of the plunger 7 of a cylindrical plunger barrel 10 for inserting and supporting the plunger 7, and a main portion having a large diameter hole is provided near the side corresponding to the upper lead 9. The port 12 is opened, and the cut step portion 8 of the plunger 7 moves axially upward beyond the opening position of the sub port 11 when the engine is rotating, and closes the sub port 11 by the wall surface of the plunger 7. In this case, a predetermined amount of fuel is reduced, and further, when the load is high, the plunger 7 is rotated in the circumferential direction so that the upper lead 9 and the main port 12 are superposed to delay the start of the actual fuel pressure feeding of the plunger 7. Fuel injection pump for diesel engine.