JPH0830459B2 - Fuel injection pump - Google Patents

Description

The present invention relates to a fuel injection pump, and more particularly to a fuel injection pump adopting a two-stage injection system.

(Prior Art) Generally, in a diesel engine, the ignition delay period of the fuel spray is longer than that in other operation regions during low speed / low load operation such as idle operation, and therefore combustion after ignition is rapidly performed. The rate of pressure increase in the cylinder increases,
This causes a problem that a large combustion noise is generated.

In order to suppress such combustion noise, it is effective to suppress the pressure rise rate in the cylinder due to the combustion, in other words, to slowly perform the combustion of the air-fuel mixture in the cylinder, considering the cause of the combustion noise. There is known a device which realizes this, for example, a device which adopts a two-stage injection system as disclosed in Japanese Utility Model Laid-Open No. 59-30555.

(Problems to be Solved by the Invention) However, in this known example, since the fuel is injected in two stages throughout the entire operating region of the engine, it is slow in the low-speed / low-load operating region of the engine. Combustion noise is reduced by effective combustion, but in operating regions other than such low-speed / low-load operating regions, on the contrary, a decrease in fuel injection rate suppresses an increase in engine internal cylinder pressure, resulting in sufficient output performance. There was a problem that I could not get it.

Therefore, in the present invention, two-stage injection is reliably realized only in the low load / low speed operation region where the combustion noise reduction request is the highest, and good output performance is obtained as the single-stage injection in the other operation regions. In addition, the initial injection is properly controlled to reduce NO _X and improve fuel efficiency, especially in the medium-load, medium-speed, and high-speed operation regions, and from the low-load operating region to the medium-load operating region. The other purpose is to improve the driving characteristics during the transition.

(Means for Solving the Problems) As a means for solving the problems of the conventional apparatus, the present invention uses a barrel 2 as illustrated in FIGS. 1 to 13.
By reciprocating the plunger 3 inside, the fuel in the pressurizing chamber 16 formed on the top surface 3b of the plunger 3 is pressurized.
On the other hand, the head 3a of the plunger 3 is provided with a slanting groove-like lead 11 for defining the end of fuel injection, which communicates with the top surface 3b of the plunger 3, on the side peripheral surface 3c of the plunger 3 while allowing the plunger 3 to be pumped. And the barrel 2 are appropriately rotated relative to each other to reed the lead.
In the fuel injection pump in which the fuel injection amount is controlled by changing the communication timing between 11 and the barrel port 10 for defining the fuel injection end period formed in the barrel 2, the barrel port 10 is replaced with the first barrel port. When this is done, in a circumferential position different from this first barrel port 10,
A second barrel port 18 having a smaller cross-sectional area than the first barrel port 10 is formed, and the side peripheral surface of the plunger 3 is formed.
3c, inclined in the same direction as the lead 11 and in the full speed range of the engine low load operation range and the middle load operation range
The pressurizing chamber is in communication with the second barrel port 18 at a predetermined intermediate time during the fuel injection period in the high speed range.
It is characterized in that a slit groove 14 is formed so as to allow the 16 and the second barrel port 18 to temporarily communicate with each other.

(Operation and Effect of the Invention) According to the present invention, the following operation and effect are obtained by such means.

In the low load / low speed operation range including the idle operation of the engine, that is, in the operation range in which the output is not so required but the combustion noise reduction request is high, the two-stage injection is surely realized. That is, in this low load / low speed operation range,
The slit groove 14 of the plunger 3 is allowed to overlap and communicate with the second barrel port 18 of the barrel 2 at a predetermined intermediate time point during the fuel injection period, and the speed of the plunger 3 is low because of the low speed operation. Slit groove 14 and second
The polymerization time with the barrel port 18 becomes relatively long, and a sufficient period of fuel outflow from the slit groove 14 and the second barrel port 18 is secured. Therefore, when the plunger 3 is raised, the slit groove 14 becomes the second barrel port 18 from the time when the second barrel port 18 of the barrel 2 is closed by the side peripheral surface 3c of the plunger 3. Primary injection of fuel (primary injection stroke S ₁ ) is performed during the period until the polymerization communication is established, and the interior of the pressurizing chamber 16 is maintained during the period when the slit groove 14 is communicated with the second barrel port 18. Pressurized fuel from the slit groove 14 to the second barrel port
When the injection is temporarily interrupted because it flows out from the pressurizing chamber 16 via 18, and the communication between the slit groove 14 and the second barrel port 18 is interrupted again as the plunger 3 rises, Secondary injection is performed during the period (secondary injection stroke S ₂ ) from that point until the lead 11 and the first barrel port 10 for defining the fuel injection end period communicate with each other.

Therefore, in the low load / low speed operation region, the fuel injection rate decreases and the combustion becomes slower due to the realization of the two-stage injection, so that the combustion noise caused by the large pressure increase rate in the cylinder due to the rapid combustion is generated. The engine can be reduced as much as possible to realize quiet engine operation.

Further, in this case, the slit groove 14 is formed by the lead 11
Since it inclines in the same direction as, the primary injection stroke gradually reduces with the transition from the high load side to the low load side even within the same low load operating range.
The injection amount of the next injection gradually decreases as it approaches the limit load on the low load side. Therefore, for example, when the primary injection stroke is constant in the entire load range of the low load operation range, the fuel injection rate is reduced in all the load range included in the low load operation range to reduce the combustion noise. Depending on the size of the load, this effect may not be obtained in some areas, but
When configured as in the present invention, the above effect can be reliably obtained in all load regions in the low load operation region where two-stage injection is required, and combustion noise can be reduced by more precise fuel control. It can be made even more reliable.

Further, since the slit groove 14 is inclined toward the same direction as the lead 11, when two-stage injection is performed in the low load operating region, with an increase in the load in the low load operating region, The injection rate of the secondary injection hardly changes, and only the injection rate of the primary injection gradually increases.
As a result, at the time of transition from the low load operating region to the medium load operating region, the injection rate of the primary injection in the low load operating region and the injection rate of the initial injection in the first stage injection in the medium load operating region are as much as possible. And the change in the combustion characteristics of the engine due to the shift of the operating region is small, and the better operating characteristics are realized.

In the low load / medium speed operation region and the low load / high speed operation region, the slit groove 14 of the plunger 3 communicates with the second barrel port 18 of the barrel 2 at a predetermined intermediate point during the fuel injection period. In the operating region of, the fuel injection amount is originally small, the speed of the plunger 3 is high, and the overlapping time of the slit groove 14 and the second barrel port 18 is short, so that the slit groove 14 and the second barrel port 18 The fuel outflow period is virtually eliminated. Therefore, in these operating regions, although the fuel injection should be interrupted in the middle of the injection period to become the two-stage injection as in the low load / low speed operating region, the fuel injection It is in a one-stage injection state without interruption. Therefore, good output performance is ensured in such an operating region.

In the medium-load / low-speed operation range, the slit groove 14 of the plunger 3 and the second barrel port 18 of the barrel 2 do not communicate with each other during the fuel injection period, so that a single-stage injection is realized and good output performance is secured. It is what is done.

In the medium-load / medium-speed and medium-load / high-speed operation regions, the slit groove 14 of the plunger 3 and the second barrel port 18 of the barrel 2 communicate with each other in the middle of the fuel injection period. Should be interrupted in the middle of the operation, and two-stage injection should be performed. In these operating regions, the fuel injection amount itself is relatively large, and the speed of the plunger 3 is high, and the slit groove 14 and the second barrel port are high. Since the outflow time of fuel through 18 is extremely short, the outflow amount of fuel is small even if the slit groove 14 and the second barrel port 18 communicate with each other. A single-stage injection having a continuous mountain-shaped injection rate characteristic having injection rate peak points is realized.

Therefore, because of the single-stage injection, good output performance is ensured, and the injection rate of the initial injection is smaller than the injection rate of the initial injection in the one having the injection rate characteristic of one peak, so NO _X Reduction and improvement of fuel efficiency are achieved.

In the high load operation range, the slit groove 14 of the plunger 3 and the second barrel port 18 of the barrel 2 do not communicate with each other in the entire speed range, so that the fuel injection is not interrupted, and a single peak injection rate characteristic is obtained. One-stage injection is realized,
Good output performance can be obtained.

(Embodiment) A preferred embodiment of the present invention will be described below with reference to FIGS. 1 to 13.

First Embodiment FIG. 1 shows a fuel injection pump for a diesel engine according to a first embodiment of the present invention. In FIG. 1, reference numeral 1 is a pump main body with an integral mounting flange, and 2 is the pump main body 1. Is a barrel that is fitted and fixed in the plunger 2. A plunger fitting insertion hole 4 is formed in the axial center portion of the barrel 2, and the plunger 3 is relatively rotated in the axial direction in the plunger fitting insertion hole 4. It is slidably inserted, and the plunger 3 has a spring force of a plunger spring 5 and a fuel cam (not shown).
By the reciprocating motion in the axial direction by the cam action of, the fuel sucked into the pressurizing chamber 16 formed on the top surface 3b of the plunger 3 is pressurized, and this is injected through the delivery valve 6 to the engine (not shown). The fuel is supplied to an injector (not shown) provided in each cylinder.

Further, in FIG. 1, reference numeral 7 is a plunger rotating wheel that is attached to the plunger 3 in a circumferentially engageable manner, and the plunger 3 is a crack gear that meshes with the plunger rotating wheel 7 by a metering operator 8. By appropriately pushing and pulling 9, the barrel 9 is relatively rotated in the barrel 2 to perform a predetermined metering action as described later. That is, as shown in FIGS. 2 and 3, a barrel port 10 having a circular cross-section with an inner diameter d ₁ is bored on one side of the barrel 2, while the side peripheral surface 3c of the head 3a of the plunger 3 is formed. Are separated from the top surface 3b as appropriate and are formed in a slanted groove.
11 is formed over almost half of the circumference. Further, the lead 11 is communicated with the top surface 3b of the plunger 3 through a fuel-releasing communication groove 12 extending in the axial direction of the plunger 3.

In this type of fuel injection pump, fuel injection and metering are performed as follows. That is, first, the plunger 3 is lowered in the barrel 2 so that the fuel is sucked into the barrel 2 through the fuel suction port (not shown). Subsequently, when the plunger 3 is raised, the fuel is not pressurized while the barrel port 10 and the fuel suction port are open. However, at a predetermined stroke of the plunger 3, first, the fuel suction port is moved to the plunger head 3a. Pressurization (injection) of fuel when it is closed by the side surface 3c and then the barrel port 10 is completely closed by the side surface 3c.
Then, the plunger 3 further rises and the lead 11 of the plunger 3 overlaps with the barrel port 10 so that the high pressure fuel oil in the pressurizing chamber 16 escapes to the barrel port side through the communication groove 12. Injection continues. That is, in this type of fuel injection pump, the barrel port 10
The end of the fuel injection is defined by the superposition of the lead 11 and the lead 11, and the end of the fuel injection is changed by rotating the plunger 3 to change the superposition timing of the barrel port 10 and the groove 11 of the lead 11. (That is, control of the fuel injection amount) is performed.

A fuel metering mechanism composed of such a combination of the barrel port 10 and the lead 11 which is in communication with the barrel port 10 is called a Bosch type fuel injection pump or a sleeve metering type fuel injection pump. Although it is a conventionally known one, in the present embodiment, in addition to this, the present invention is further applied to this metering mechanism portion so as to have a function of changing the injection form.

That is, in this embodiment, as shown in FIGS. 2 and 3, a portion of the side peripheral surface 3c of the head 3a of the plunger 3 located between the lead 11 and the top surface 3b of the plunger 3. In addition, a slit groove 14 having a width B and a depth L extending in the circumferential direction of the plunger in the same inclination direction as the lead 11 and at an angle θ with respect to the top surface 3b is formed so as to be appropriately separated from the top surface 3b. ing. The slit groove 14 constitutes a throttle outflow passage together with the inner peripheral surface of the plunger fitting insertion hole 4 facing the slit groove 14.

On the other hand, another barrel port 18 having a smaller diameter than the barrel port 10 and an inner diameter d ₂ is bored in the barrel ₂ at a circumferential position apart from the barrel port 10 by a center angle α.
In the fuel injection pump of the present invention, the two barrel ports 10 and 18 are thus formed in the barrel 2, but in the present specification, the action of defining the end of fuel injection among these two barrel ports 10 and 18 is performed. The large-diameter barrel port 10 that does this is called the first barrel port, and the other small-diameter barrel port 18 is called the second barrel port.

Next, the relationship between the first and second barrel ports 10 and 18 and the lead 11 and the slit groove 14 will be described with reference to FIGS. 4 to 5 together.
It shows how the mutual communication relationship between the barrel ports 10 and 18, the lead 11 and the slit groove 14 changes with the rotation of the.

In the actual fuel injection pump, the barrel 2 side is fixed,
Although the plunger 3 side rotates and moves up and down,
In the drawing, for convenience of drawing, one lead 11 and one slit groove 14 of the plunger 3 are set at fixed positions, respectively, and the first and second barrel ports 10 and 18 on the barrel 2 side are set to the rotation angle of the plunger 3. Multiple items are listed in correspondence with (engine load condition). On the other hand, in FIG. 5, the relative relationship between the two is shown by a method of fixing the barrel 2 and vertically displacing the plunger 3 according to the actual fuel injection pump. Further, FIGS. 4 and 5 show, as an example, the communication relationship at low speed in each of the three load regions of low load, medium load and high load.

First, the formation range of the slit groove 14 is the second barrel port 18 in the low load operation region (small fuel injection region).
The second barrel port 18 (positions indicated by 18C, 18D, 18E, 18F in Fig. 4) in the medium / high load operation state within the angular range until the point overlaps with (positions indicated by 18A, 18B in Fig. 4) The range is on the smaller fuel injection amount side, and one end thereof is communicated with the communication groove 12.

Therefore, the second barrel port 18 always communicates with the slit groove 14 in the middle of the reciprocating motion of the plunger 3 in the low load / low speed operation region of the engine, while the second barrel port 18 has the medium load / low speed operation region and high load of the engine. In the low speed operation region, the slit groove 14 is maintained in the non-communication state with the second barrel port 18 during the entire plunger stroke.

In the low-load medium-speed and high-speed operation regions, as the speed changes from low speed → medium speed → high speed, the plunger 3 is in the fuel decreasing direction, that is, the slit groove 14 and the second barrel port 18 are superposed. Since it is rotationally displaced in the direction of the rotation, the slit groove 14 and the second barrel port 18 maintain the overlapping state as in the case of low speed (that is, in the low load operating region, the slit groove 14 and Second barrel port
18 and 18 are in a polymerized state.

In the medium-speed and high-speed operation region of medium load, the plunger 3 is changed as the speed changes from low speed to medium speed → high speed.
Is rotationally displaced in the fuel decrease direction, that is, in the direction in which the slit groove 14 and the second barrel port 18 are overlapped,
The slit groove 14 and the second barrel port 18 are in a non-overlapping state at low speed, but the slit groove 14 and the second barrel port 18 are in a superposed state when shifting to the medium speed and high speed regions.

In the medium-speed and high-speed operation regions of high load, as in the medium-load operation region, the plunger 3 is rotationally displaced in the fuel reducing direction as the speed changes from low speed to medium speed → high speed. Since the gap width between the slit groove 14 and the second barrel port 18 is large, the slit groove 14 and the second barrel port 18 are maintained in the non-communication state in spite of the increase in speed.

By setting the communication relationship between the slit groove 14 and the second barrel port 18 as described above, the following injection rate characteristics and the like can be obtained in each operating region.

Low load / low speed operation range When the engine is low load / low speed operation, barrel 2
When the first and second barrel ports 10 and 18 are closed by the side peripheral surface 3c of the plunger 3 (from FIG. 5 (b), the second barrel port 18 communicates with the slit groove 14 (see FIG. 4).
Fuel is injected (primary injection) in the plunger stroke (primary injection stroke S ₁ ) up to the position indicated by 18A in FIG. 5C, but the second barrel port
When 18 communicates with the slit groove 14 in an overlapping manner (Fig. 5 (d)),
In this operating region, the fuel injection amount itself is relatively small, the plunger speed is low, and the communication time between the slit groove 14 and the second barrel port 18 is relatively long. The portion flows out to the communication groove 12 side through the slit groove 14 in a throttled state, and fuel injection is interrupted. Furthermore, as the plunger 3 moves up, the second barrel port
When the communication between 18 and the slit groove 14 is interrupted again (Fig. 5 (e)), the first barrel port 10 communicates with the lead 11 in a superposed manner from that point (Figs. 10B and 5 in Fig. 4). In the plunger stroke (secondary injection stroke S ₂ ) up to (f)), the fuel is injected again (secondary injection). The injection rate characteristic of the two-stage injection in this case is shown in the low load / low load region (region X) of FIG.

Therefore, in this low load / low speed operation region, the fuel injection rate becomes lower due to the execution of the two-stage injection than that in the case of the one-stage injection, so that the slow combustion of the air-fuel mixture is realized and the rapid increase in the cylinder pressure occurs. The resulting combustion noise can be effectively reduced, and quiet operation of the engine can be realized.

In this case, since the slit groove 14 is inclined in the same direction as that of the lead 11, even if it is in the same low load operation region, the slit groove 14 changes from the high load side to the low load side. The next injection stroke is gradually reduced, and the injection amount of the primary injection is gradually reduced as it approaches the limit load on the low load side. Therefore, the effect of lowering the fuel injection rate to lower the combustion noise can be reliably obtained in all of the load regions in the low load operation region where the two-stage injection is required, and more precise fuel control can be achieved. By this, the reduction of combustion noise can be further ensured. Incidentally, for example, when the primary injection stroke is constant over the entire low load operating range, the above operation and effect are not obtained over the entire load range included in the low load operating range, Depending on the size, a region where this effect is not sufficiently obtained may occur.

Further, since the slit groove 14 is inclined toward the same direction as the lead 11, when two-stage injection is performed in the low load operating region, with an increase in the load in the low load operating region, The injection rate of the secondary injection hardly changes, and only the injection rate of the primary injection gradually increases.
As a result, at the time of transition from the low load operating region to the medium load operating region, the injection rate of the primary injection in the low load operating region and the injection rate of the initial injection in the first stage injection in the medium load operating region are as much as possible. And the change in the combustion characteristics of the engine due to the shift of the operating region is small, and the better operating characteristics are realized.

As described above, in the engine provided with the fuel injection pump of this embodiment, the injection amount of the primary injection is set in the entire low load operation region and corresponding to the load size (region region). As a result, operating noise is effectively reduced in the entire low load operating range of the engine.
The characteristics of such a fuel injection pump are particularly useful in a large marine engine for a fishing boat, which requires trolling due to low speed / low load operation for a long time.

Low-load / medium-speed / high-speed operation region In the low-load / medium-speed operation region and low-load / high-speed operation region, the slit groove 14 of the plunger 3 is the second barrel of the barrel 2 at a predetermined intermediate point during the fuel injection period. Although they communicate with the port 18 in an overlapping manner, in these operating regions, the fuel injection amount is originally small, the speed of the plunger 3 is high, and the overlapping time between the slit groove 14 and the second barrel port 18 is short. The period of fuel outflow from 14 and the second barrel port 18 is substantially eliminated. Therefore, in these operating regions, although the fuel injection should be interrupted in the middle of the injection period to become the two-stage injection as in the low load / low speed operating region, the fuel injection It is in a one-stage injection state without interruption. Therefore, good output performance is ensured in such an operating region.

The injection rate characteristics in this operating region are shown in the low load, medium speed and high speed regions (lower half of region Y) in FIG.

Medium-load / low-speed operation range In the medium-load / low-speed operation range, the second barrel port 18 and slit groove 14 are shown in Fig. 4 (reference numerals 18C, 18D).
Since it is always not connected as shown, the first barrel port 10
In the plunger stroke range from (10D, 10F) until the first barrel port 10 overlaps with the lead 11 from the time when the side wall 3c of the plunger 3 is closed,
Fuel injection is continuously performed without interruption in the middle (realization of one-stage injection). Therefore, since a high fuel injection rate is obtained in this operating region, high-power operation of the engine is realized and engine performance is improved. The injection rate characteristics in this operating region are shown in the medium load / low speed region (lower half of region Z) in FIG.

Medium-load / medium-speed / high-speed operation range In medium-load / medium-speed / medium-load / high-speed operation range,
The slit groove of the plunger 3 during the fuel injection period
Since 14 and the second barrel port 18 of the barrel 2 communicate with each other, the fuel injection should originally be interrupted in the middle to be a two-stage injection, but in these operating regions, the fuel injection is performed. The amount itself is relatively large, and the speed of the plunger 3 is high, and the slit groove 14 and the second barrel port are
Since the fuel outflow time through 18 and is extremely short,
Even if the slit groove 14 and the second barrel port 18 communicate with each other in an overlapping manner, the amount of fuel outflow is small, and as a result, a continuous mountain-shaped injection rate characteristic having injection rate peak points in the early injection period and the late injection period is obtained. A single-stage injection is realized. The injection rate characteristics in this operating region are shown in the medium load / medium speed and high speed regions (the upper half of the region Y) in FIG.

Therefore, in these operating regions, good output performance is ensured due to the single-stage injection, and the injection rate of the initial injection is higher than the injection rate of the initial injection in the case where the injection rate characteristics have a single peak. Since it is small, NO _X can be reduced and fuel consumption can be improved.

High load operation region In the high load operation region, the slit groove 14 of the plunger 3 and the second barrel port 18 of the barrel 2 do not overlap and communicate with each other in the entire speed range, so that there is no interruption of fuel injection and there is a single mountain shape. A one-stage injection having an injection rate characteristic is realized and good output performance is obtained. The injection rate characteristics in this operating region are shown in the high load / low speed, medium speed and high speed regions (the upper half of the region Z) in FIG.

In addition, in the above-described embodiment, the slit groove 14 is formed to be shallow, thin, and partially, so that the load is low as described above.
It is possible to reduce the noise by performing the two-stage injection only in the low-speed operation region X. In this case, the interval ψ of the two-stage injection is ψ = d ₂ + B and the slit groove width B and the first Inner diameter of 2 barrel port
It can be set arbitrarily by d ₂ .

Further, in the low load / medium speed / high speed operation area and the area Y corresponding to the medium load / medium speed / high speed operation area, the slit groove is formed.
The second barrel port 18 and the second barrel port 18 are temporarily overlapped or joined, but in this case, the slit groove 14 and the second barrel port 18 are set as described above by setting the opening area of both to an appropriate size. It is possible to prevent excessive pressure leak of the fuel during the polymerization period with 18, and to make a single-stage injection.

Second Embodiment FIGS. 7 to 9 show the essential parts of a fuel injection pump according to a second embodiment of the present invention. This fuel injection pump has the same basic configuration as that of the first embodiment, but is different from the first embodiment only in the positions of the slit groove 14 and the second barrel port 18.

That is, in this embodiment, as shown in FIG. 7 to FIG.
The side peripheral surface 3c of the plunger 3 which is bored in the barrel port 10 at the opposite position and faces the lead 11 installation portion as the slit groove 14.
To the top surface 3b (not to the communication groove 12)
It is a partially formed shallow thin slit groove inclined in the same direction as 11.

Also in the second embodiment, the same operation as in the first embodiment, that is, the effect of reducing combustion noise during low load operation of the engine, the effect of improving engine performance during high load operation, and the slit groove are provided. The effect of increasing / decreasing the effective stroke of the primary injection by the 14 regions can be obtained.

Third Embodiment FIGS. 10 to 13 show the essential parts of a fuel injection pump according to a third embodiment of the present invention. This fuel injection pump also has the same basic configuration as that of the first embodiment, but is different from the first embodiment only in the positions of the slit groove 14 and the second barrel port 18.

That is, in this embodiment, FIG.
As shown in FIG. 12, the slit groove 14 is formed in the same communication direction as the lead 11 in the same inclination direction as that of the lead 11 but in the communication groove with an angle θ.
It communicates with 12, but is provided below the lead 11, and the second barrel port 18 of the barrel 2 is also drilled at a height corresponding to this and at a position forming a central angle α with the first barrel port 10. The same operation as the first embodiment is performed.

The first to third embodiments will be described with reference to the first
The barrel port 10 and the second barrel port 18 of the above have been described as having a circular cross-section, but the present invention is not limited to having a circular cross-section, and may have a cross-section of any shape. The barrel port 18 may have a smaller cross-sectional area than the first barrel port 10.

[Brief description of drawings]

1 to 6 relate to a fuel injection pump according to a first embodiment of the present invention. FIG. 1 is an overall longitudinal sectional view thereof, FIG. 2 is an enlarged view of a II portion of FIG. 1, and FIG. The figure shows II in Figure 2.
I-III arrow view, FIG. 4 is a development view of the plunger and barrel, FIG. 5 is an explanatory view of the two-stage injection action at the time of idling operation, FIG. 6 is an explanatory view of the fuel injection rate pattern, FIG. FIG. 9 relates to a fuel injection pump according to the second embodiment, FIG. 7 is an enlarged view corresponding to FIG. 2, FIG. 8 is a plan view with respect to FIG. 3, and FIG. 9 is a plunger and a barrel. Developments, FIGS. 10 to 13 relate to the fuel injection pump according to the third embodiment. FIG. 10 is an enlarged view corresponding to FIG. 2, and FIG. 11 is a plan view corresponding to FIG. , 12th
FIG. 13 is a development view of the plunger and barrel, and FIG. 13 is an explanatory view of the two-stage injection action during idling operation. 2 …… Barrel 3 …… Plunger 3a …… Head 3b …… Top surface 3c …… Side peripheral surface 10 …… First barrel port 11 …… Lead 14 …… Slit groove 16 …… Pressure chamber 18 …… Second barrel port

Claims (1)

[Claims] 1. A fuel in a pressurizing chamber (16) formed on a top surface (3b) of the plunger (3) is pressurized by reciprocating the plunger (3) in the barrel (2). On the side peripheral surface (3c) of the head (3a) of the plunger (3), while being capable of being pumped, a slant groove shape for communicating with the top surface (3b) of the plunger (3) for defining the end of fuel injection. Of the lead (11), and the plunger (3) and the barrel (2) are appropriately rotated relative to each other to form the lead (11) and the barrel (2). (10) A fuel injection pump configured to control a fuel injection amount by changing a communication timing with the first barrel port (10) when the barrel port (10) is a first barrel port. From the first barrel port (10) at a circumferential position different from 10) A second barrel port (18) having a cross-sectional area is formed, and the side peripheral surface (3c) of the plunger (3) is inclined in the same direction as the lead (11) and has a low load operation region of the engine. At a predetermined intermediate time during the fuel injection period in the full speed range and the medium / high speed range of the medium load operation range, the second barrel port (18) communicates with the second barrel port (18) to communicate with the pressurizing chamber (16) and the second A fuel injection pump characterized in that a slit groove (14) for temporarily communicating with the barrel port (18) of is formed.