WO1999032787A1

WO1999032787A1 - Fuel injection pump

Info

Publication number: WO1999032787A1
Application number: PCT/JP1998/005764
Authority: WO
Inventors: Katsuhiko Nagakura
Original assignee: Yanmar Diesel Engine Co., Ltd.
Priority date: 1997-12-19
Filing date: 1998-12-18
Publication date: 1999-07-01
Also published as: EP1041273A1

Abstract

A fuel injection pump for a diesel engine for attaining a specially excellent combustion performance, specifically comprising a notch part (20) formed in the retraction collar (16) of a delivery valve (3), in addition to an Angleich cut (17), to increase the communicating area of a fuel path (18) between a high pressure chamber (7) and a force-feed chamber (11) according to the lift of the delivery valve (3) so as to suppress the retraction effect of the delivery valve (3) in order to prevent a residual pressure in the high pressure chamber (7) from excessively lowering particularly during high idling. An annular groove (54) communicating with a lower lead (52) is formed in the outer peripheral surface of a plunger (50), and a part of fuel inside the force-feed chamber (11) is returned, during force-feed process, to a fuel feed port (13) through the annular groove (54) so as to increase the length of an injection period in low and medium speed ranges to reduce combustion noise, and to delay the injection timing under low idle condition to reduce the emission of blue white smoke.

Description

Details Fuel injection pump Technical field

The present invention relates to a fuel injection pump for a diesel engine, and particularly to a structure that can achieve good combustion performance. Background art

FIG. 17 and FIG. 18 show a conventional fuel injection pump. As shown in the figure, a valve seat (2) is provided at the top of the pump body (1). The delivery valve (3) inside the valve seat (2) is normally closed by a spring (4). Energized in the valve direction. A high-pressure chamber (7) is provided inside the valve holder (6) for fixing the valve sheet (2) to the pump body (1), and a fuel is provided so as to communicate with the high-pressure chamber (7). A high-pressure pipe (8) is connected to the valve holder (6) and communicates with an injection nozzle (not shown).

On the other hand, a plunger (10) driven by a cam (not shown) is slidably provided at a lower portion of the pump body (1), and a pressure feed chamber is provided between the upper portion of the plunger (10) and the delivery valve (3). (11) is provided. A lower lead (12) inclined in an oblique direction is formed on the outer peripheral surface of the plunger (10), and the lower lead (12) communicates with the pressure feed chamber (11).

In the above, when the plunger (10) is moved upward by the cam and the outer peripheral surface of the plunger (10) closes the fuel supply port (13) opening toward the pressure feed chamber (11) as shown in FIG. The fuel in the pumping chamber (11) is compressed and piled by the urging force of the spring (4) to push up the delivery valve (3). As a result, the high-pressure chamber (7) and the pressure-feeding chamber (11) communicate with each other, and fuel flows into the high-pressure chamber (7) to increase the pressure in the high-pressure chamber (7). The pressure of this high pressure chamber (7) When the pressure exceeds the valve opening pressure of the injection nozzle, fuel is injected from the injection nozzle.

When the plunger (10) moves further upward and the lower lead (12) opens the fuel supply port (13), the fuel in the pumping chamber (11) is supplied through the lower lead (12). The pressure is returned to the port (13), and the pressure in the pumping chamber (11) rapidly decreases. As a result, the delivery valve (3) is pushed down by the urging force of the spring (4), and the conical valve portion (14) above the delivery valve (3) is brought into close contact with the sheet surface of the valve sheet (2) and ejected. Is completed. At this time, the fuel in the high-pressure chamber (7) is sucked back by the action of the suction pipe (16) provided below the valve section (14) of the delivery valve (3), and the residual pressure is reduced. As a result, the cut of the injection is improved, and later dropping is prevented. However, the suction operation of the delivery valve (3) has a problem that the negative pressure is generated on the high-pressure pipe (8) side in the low-speed region, and the injection amount becomes unstable. ) Is applied to the sliding surface of () to suppress the suction effect and secure the residual pressure in the high-pressure chamber (7) in the low-speed range to some extent, and inject the fuel to the rotation speed. The quantitative characteristics, that is, the N-Q characteristics are improved.

In the above fuel injection pump, the amount of fuel injection is controlled by rotating the plunger (10) in the circumferential direction within the range of the lower lead (12) to change the range of use, that is, the effective stroke, and using the lower lead (12). The fuel injection is controlled by controlling the cut timing. For example, when the load is low, the injection amount is reduced by using the shallow position of the lead, and when the load is high, the injection amount is increased by using the deep position of the lead.

Such a conventional fuel injection pump has the following disadvantages. Generally, in the low-speed range, the force of the cam to push up the plunger is weak, so that the lift amount of the delivery valve (hereinafter referred to as “lift amount”) is small. The plunger push-up force is strong, and this dynamic effect increases the lift of the delivery valve. If the lift amount of the delivery valve is large, the suction effect is also large, and the residual pressure in the high pressure chamber is reduced. In other words, the higher the speed, The residual pressure in the high pressure chamber decreases.

Conventionally, the above tendency has been observed, and if the residual pressure in the high-pressure chamber (7) is to be kept low in the low-speed region, the high-pressure chamber ( The residual pressure in 7) may be too low, and the rise of injection during the pumping process, that is, the dynamic injection timing may be delayed. In this case, a misfire is caused at the time of a cold start or the like, and a trouble such as a misfire emitting blue-white smoke is likely to occur.

On the other hand, if the residual pressure is not made too low in the high idling state, the residual pressure in the low-speed region will increase in conjunction with the securing of the pressure by the angle cutter (17), which will shorten the injection period. As a result, the formation of the air-fuel mixture and the combustion become rapid, and the combustion noise is likely to be generated.

That is, while maintaining the residual pressure in the high-pressure chamber (7) in the low-speed range low, and keeping the residual pressure in the high-pressure chamber (7) in the high idling state from becoming too low, the combustion performance is maintained satisfactorily. It was difficult to do.

In addition, the residual pressure in the low-speed range can be kept to some extent low by using a constant-pressure valve.However, in this case, the spill rate in the high-speed and high-load range is reduced, so that the injection cut-off becomes worse and the combustion performance deteriorates. Was invited.

Furthermore, conventionally, during the pumping process by the plunger (10), the pressure in the pumping chamber (11) continuously increases, so that the injection pressure also increases continuously, thereby shortening the injection period. However, there is a problem in that the mixture formation speed becomes rapid and explosively burns at once, resulting in a large combustion noise. The generation of such combustion noise is particularly remarkable in low to medium speed ranges. In addition, in the low idle state where the injection amount is small, the injection timing was advanced, and there was a problem that the combustion deteriorated and blue-white smoke was generated. Therefore, in order to solve the above-mentioned problem, a groove communicating with the lower lead is provided near the upper end of the plunger, and the fuel in the pumping chamber is partially returned to the fuel supply port through the groove during the plunger pumping process. In particular, the pressure inside the pumping chamber in low to medium speed range Various fuel injection pumps have been proposed in which the injection time is made longer by increasing the injection time slowly and the injection timing is made variable.

However, in any of the proposals, the groove formed on the outer peripheral surface of the plunger is a partial groove having one end communicating with the lower lead. This means that it is necessary to increase the effective stroke and maximize the injection amount by using the deepest position of the lead, especially at the start, but if the fuel is returned at this start, it will start. This is because the groove is formed so as to avoid the deepest position of the lead because of the poor performance.

When such a partial groove is formed on the outer peripheral surface of the plunger using a cutting machine, highly accurate positioning of the plunger with respect to how far the groove is to be cut is required. Managing the distance to the groove is also very difficult. For this reason, the plunger groove machining was very complicated, and the manufacturing cost was increased.

In addition, when the plunger is rotated to change the injection amount, the relative position between the fuel supply port and the partial groove changes and the overall length of the fuel discharge path changes, and the pressure in the pumping chamber is precisely controlled. There was a problem that it was not possible.

The present invention solves the above-mentioned drawbacks and keeps the residual pressure in the high-pressure chamber in the low-speed range to a certain extent, while the residual pressure in the high-pressure chamber in the high-speed range (particularly in the high idling state) becomes too low. The objective is to provide a fuel injection pump that achieves good combustion performance by avoiding it.

Also, part of the fuel in the pumping chamber during the pumping process can be satisfactorily discharged to reduce combustion noise in low to medium speed ranges, and to reduce blue-white smoke in the mouth-idle state. An object of the present invention is to provide a fuel injection pump in which the plunger groove processing is extremely easy. Disclosure of the invention

The present invention relates to a fuel passage connecting a high-pressure chamber to which an injection nozzle or the like is connected and a pressure-feeding chamber. In a fuel injection pump in which a delivery valve having a fuel suction function is slidably disposed, the suction collar of the delivery valve is subjected to an angleless cut, and the communication area of the fuel passage is maximized. In the step, a communication area expanding means for expanding the communication area of the fuel passage along with the movement of the delivery valve is provided separately from the expansion of the communication area of the fuel passage due to the angle cutter. is there.

As a result, in the high idling state where the injection amount is small, all the fuel to be sent into the high-pressure chamber through the fuel passage having an increased area can be sent only by slightly lifting the delivery valve. Then, the lift amount of the delivery valve, which should be large, can be reduced to suppress the suction effect, and the residual pressure in the high-pressure chamber can be secured as compared with the conventional case. Therefore, even if the residual pressure in the high-pressure chamber in the low-speed range is set to be somewhat low, the residual pressure in the high-pressure chamber in the high idling state does not become too low.

On the other hand, in the high-speed, high-load range, the injection amount is large, and the delivery valve in the high-pressure chamber lifts to a sufficient height with inertia to obtain a sufficient suction effect. Becomes sufficiently low.

Therefore, by prolonging the injection timing in the low-speed range and slowing the mixture formation and combustion, rapid heat generation can be suppressed and combustion noise can be reduced. As a result, the delay in the injection timing can be eliminated at the same time, which can significantly improve the combustion performance. In addition, despite suppressing the decrease in the residual pressure in the high idling state, the residual pressure can be sufficiently reduced by the sufficient suction effect in the high-speed and high-load range, and the injection cutoff can be prevented. Good and good combustion performance can be achieved.

Further, the communication area enlarging means includes a cutout formed in at least one of a suction / return collar of the delivery valve and a wall surface of the fuel passage. Thus, the above-described effect can be achieved with a very simple structure. Furthermore, the notch is formed by cutting out the sliding surface of the suction and return collar in a stepped or inclined shape. Furthermore, by forming the notch portion by cutting out a portion of the suction-back collar where the angle cutting is to be performed, the angle cutting and the notch portion can be simultaneously formed by a single cutting operation. The process can be simplified.

The present invention also provides a plunger having a lower lead formed on an outer peripheral surface slidably inserted into a pumping chamber, and closing a fuel supply opening opening toward the pumping chamber with a tip of the plunger. In the fuel injection pump, in which the fuel in the pressure-feeding chamber is pressure-fed before being opened by the lead, an annular groove communicating with the lower lead is formed on the outer peripheral surface of the plunger, Part of the fuel in the pressure storage chamber is returned to the fuel supply port through the annular groove.

The annular groove has the same cross-sectional shape over the entire circumference, and the width of the groove is smaller than the diameter of the fuel supply port.

As a result, in the pumping process, in the low to medium speed range where the moving speed of the plunger is slow, the time for which the fuel supply port communicates with the annular groove becomes longer, so that a large amount of fuel is discharged and the pumping capacity is sufficiently reduced. The pressure rise in the pumping chamber becomes gentle and the injection period becomes longer, thereby reducing combustion noise. In addition, it is possible to reduce blue-white smoke by delaying the injection timing in the mouth-idle state.

On the other hand, in a high-speed and high-load region, the plunger moves at a high speed, and the time required for communication between the fuel supply port and the annular groove is shortened. Therefore, the injection period becomes longer in the low to medium speed range, but in the high speed and high load range, the injection period can be shortened to maintain good combustion performance with good injection termination.

Also, by adopting an annular groove having the same cross-sectional shape, it becomes possible to extremely easily perform plunger groove processing using a cutting machine, as compared with the case of forming a conventional partial groove. Manufacturing costs can be reduced. Furthermore, when an annular groove is formed on the outer peripheral surface of the plunger, two communicating portions with the lower lead and the fuel supply port are formed, so that two fuel discharge paths can be obtained with one groove. Fuel efficiency can be increased.

Furthermore, if the plunger is rotated horizontally to change the injection amount, the relative position between the fuel supply port and the annular groove will change, but the total length of the fuel discharge path will always be the full length of the annular groove. Does not change equally. Therefore, regardless of the rotational position of the plunger, the fuel discharge condition can be kept constant, and the fuel control in the pumping chamber can be performed with high accuracy. BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is a longitudinal sectional view of a fuel injection pump according to an embodiment of the present invention, FIG. 2 is a longitudinal sectional view of the same delivery valve portion, and FIG. 3 is a longitudinal sectional view of the same when the communication area of the fuel passage is enlarged. Fig. 4 is a perspective view showing the notch of the delivery valve, Fig. 5 is a diagram showing the relationship between the lift amount of the delivery valve and the communication area of the fuel passage, and Fig. 6 is a delivery valve having an inclined notch. Fig. 7 is a front view of a delivery valve in which a cutout portion is formed in a portion where an angle cut is provided, Fig. 8 is a front view of a delivery valve in which a cutout portion is formed in a portion where an angle cut is provided, and Fig. 9 is FIG. 10 is a longitudinal sectional view showing a state in which a notch is formed in a valve seat. FIG. 10 is a longitudinal sectional view showing a state in which a notch is formed in both a delivery valve and a valve seat. Is a perspective view of the plunger, FIG. 12 is a side view showing the positional relationship between the plunger and the fuel supply port during the pumping process, FIG. 13 is a side view of the plunger having a pair of upper and lower annular grooves, FIG. 14 is a side view of the plunger in which the lower lead communicates with the annular groove through the cutout. FIG. 15 is a side view of the plunger in which the lower lead communicates with the annular groove through the cutout. 6 is a perspective view of another plunger in which an annular groove is formed, FIG. 17 is a longitudinal sectional view of a conventional fuel injection pump, and FIG. 18 is a longitudinal sectional view of the same during the pumping process. BEST MODE FOR CARRYING OUT THE INVENTION

The fuel injection pump according to the embodiment of the present invention

The combustion performance is improved by devising the structure of the above, and the other structures are almost the same as before. Members having the same functions as those in the related art are denoted by the same reference numerals.

In this fuel injection pump, a delivery valve (3) is slidably arranged vertically in a fuel passage (18) in a valve seat (2) communicating a high pressure chamber (7) and a pressure feeding chamber (11). The suction valve (16) of the delivery valve (3) is provided with the same angle cutter (17) as the conventional one. Before the communication area of the fuel passage (18) becomes maximum, the delivery valve (3) moves in the valve opening direction separately from the expansion of the fuel passage (18) by the Ang Reich cut (17). That is, a communication area expanding means for expanding the communication area of the fuel passage (18) according to the lift is provided.

As shown in FIGS. 2 to 4, the communication area enlarging means includes a cutout portion (20) formed in a suction return collar (16) of the delivery valve (3), and the cutout portion (20) The part of the sliding surface of the collar (16) opposite to the part where the angle cut (Π) is applied is cut out stepwise from the center slightly near the upper end to the lower surface.

As a result, when the delivery valve (3) is pushed up, the communication area of the fuel passage (18) is slightly increased by the angle cutter (17). Then, as shown in FIG. 3, when the upper end portion (21) of the notch ( ²⁰ ) of the delivery valve (3) is located above the lower end portion of the seat surface (15) of the valve seat (2), An opening is formed between the notch (20) and the seat surface (15), and the communication area of the fuel passage (18) further increases. When the delivery valve (3) is further pushed up and the lower end portion (22) of the notch (20), that is, the lower surface of the suction collar (16) is located above the lower end portion of the seat surface (15), The communication area of the fuel passage (18) further expands to reach the maximum communication area.

Fig. 5 shows the relationship between the lift amount of the delivery valve (3) and the communication area of the fuel passage ⁸ ). The solid line in the figure indicates that the delivery valve of the present invention provided with an angle cut (17) and further provided with a notch (20) is used, and the dotted line is the conventional one provided with only the angle cut (17). The case where the delivery valve is used is shown. As is evident from this figure, in the past, the communication area was enlarged by the angle bracket (17) immediately after the delivery valve (3) was pushed up, and then until the delivery valve (3) was completely opened. In the present invention, the delivery area is constant, but after the communication area is expanded by the angle cutter (17), the fuel passage (18) reaches the maximum communication area, that is, the delivery valve (3) is completely opened. By the time, the communication area is enlarged by the notch (20).

As described above, in the delivery valve structure of the present embodiment, when the lift amount of the delivery valve (3) is smaller than before, the notch portion (20) secures a sufficient communication area so that the inside of the pressure feed chamber (11) is reduced. Can be pumped into the high-pressure chamber (7).

For this reason, in a high idling state with a high injection speed and a small injection amount, all the fuel to be sent into the high pressure chamber (7) can be sent by only slightly lifting the delivery valve (3). The lift amount of the delivery valve (3), which would otherwise be large, can be suppressed to a small value, and the suction effect can be suppressed. On the other hand, in a high-speed and high-load region where the injection amount is large, the delivery valve (3) in the high-pressure chamber (7) lifts to a high position with inertial force, and a sufficient suction effect is obtained.

Therefore, even if the residual pressure in the high-pressure chamber (7) in the low-speed range is set to be somewhat low, the residual pressure in the high-pressure chamber (7) in the high idling state does not become too low. This makes it possible to prolong the injection period in the low-speed range, reduce combustion noise, and simultaneously eliminate delays in injection timing in the high idling state. In addition, despite suppressing the decrease in residual pressure in the high idling state, the residual pressure can be sufficiently reduced by a sufficient suction effect in a high-speed and high-load range, and the injection is good. High combustion performance. The delivery valve structure that achieves such an operation and effect is not limited to the above, and other delivery valve structures will be described below.

For example, as shown in Fig. 6, instead of the step-shaped notch (20), instead of the stepped notch (20), the center of the sliding surface of the suction-back force roller (16) is slightly inclined from the upper end to the lower surface, as shown in Fig. 6. A notch (30) may be formed which is tapered toward the bottom. In this case, while the stepped notch (20) gradually increases the communication area of the fuel passage (18), the communication area can be gradually increased, so that the fuel can be pumped smoothly. Thus, better combustion performance can be realized.

In addition, the portion where the notch is formed does not have to be the portion on the sliding surface of the suction return collar (16) opposite to the portion where the angle cut (17) is applied. For example, FIGS. 7 and 8 As shown in (5), cutouts (31) and (32) may be formed in the portion where the angle cut (17) is to be applied. The notch (31) shown in Fig. 7 is cut diagonally downward from the upper surface to the lower surface of the side of the suction-back collar (16), including the angle cut (17). I will lack it. The notch (32) shown in Fig. 8 first cuts the side of the suction-back collar (16) flat in the sliding direction, as in the case of applying the Angleich cut (17). It is notched in a tapered shape obliquely downward. In this case, the angle cutter (Π) and the notches (31), (32) can be formed simultaneously by one cutting operation, and the manufacturing process can be simplified.

Further, a plurality of notches as described above may be formed on the side of the suction / retraction force line (16) of the delivery valve (3), and tapered portions having different angles are continuously formed to form an inclined notch. It may be formed.

Furthermore, a notch is formed in the wall surface of the fuel passage (18), that is, the inner surface of the valve seat (2), so that the communication area is increased in accordance with the lift of the delivery valve (3) as described above. good. For example, as shown in FIG. 9, the corner of the seat surface (15) of the valve seat (2) is cut out in a stepped shape over the entire circumference, so that the suction force of the delivery valve (3) in the closed state is reduced. Notch located above (16) (40) may be formed. In this case, when the delivery valve (3) is pushed up and the lower surface of the suction force roller (16) is located above the lower surface of the notch portion (40), the notch portion (40) and the suction collar (16) are connected. An opening is formed between them, and the communication area of the fuel passage (18) increases.

Further, as shown in FIG. 10, the notches (30) and (40) may be formed on both the suction-back collar (16) of the delivery valve (3) and the inner surface of the valve sheet (2). . In this case, when the upper end of the notch (30) is located above the lower surface of the notch (40) of the valve seat (2), an opening is formed between the notches (30) and (40). As a result, the communication area of the fuel passage (18) is increased, and the lift amount of the delivery valve (3) required for increasing the communication area can be extremely reduced. The notch on the delivery valve (3) side may be a stepped one, and the notch on the valve seat (2) may be a tapered one. In addition, the number of cutouts and the formation site may be appropriately changed. On the other hand, as shown in FIG. 11, the plunger (50) is formed with a vertical groove (51) having a circular cross-section from the center of the upper end face toward the lower part, and substantially halfway in the oblique direction from near the upper end of the outer peripheral face. And a lower lead (52) is formed. The lower end of the vertical groove (51) and the center of the lower lead (52) communicate with each other via the horizontal groove (53).

Further, an annular groove (54) is formed over the entire circumference in the vicinity of the upper end of the outer peripheral surface of the plunger (50) so as to intersect with and communicate with the upper end of the lower lead (52). The annular groove (54) is arranged parallel to the upper end surface of the plunger (50), has the same cross-sectional shape over the entire circumference, and has a groove width larger than the diameter of the fuel supply port (13). Is also set small. The cross-sectional shape of the annular groove (54) is not limited to a rectangle, but may be a semicircle or a wedge. When such an annular groove (54) is formed using a cutting machine, the machining position of the annular groove (54), that is, the distance from the upper end surface of the plunger (50) is determined, and the cutting machine In this case, it is only necessary to press the cutting edge of, fix the plunger (50) and rotate it horizontally. This eliminates the need for high-precision positioning of the plunger and difficult distance management from the upper end surface of the plunger, as is required when machining conventional partial grooves. The process is extremely simple, and the manufacturing cost can be reduced.

FIG. 12 shows the positional relationship between the plunger (50) and the fuel supply port (13) during the pumping process. As shown in this figure, when the plunger (50) moves upward and the upper end face of the plunger (50) reaches the same height position as the upper end of the fuel supply port (13), the fuel in the pumping chamber (11) is removed. Pumping begins. In this pumping start state, the fuel supply port (13) and the annular groove (54) are in communication with each other, and the fuel in the pumping chamber (11) is filled with the vertical and horizontal grooves (51) (53), the lower lead (52) and the annular Discharge to the fuel supply port (13) through the groove (54). At this time, the annular groove (54) communicates with the fuel supply port (13) at two locations (55) and (56), and also communicates with the lower lead (52) at two locations (57) as shown in FIG. ) (58), there are two fuel discharge paths from the lower lead (52) to the fuel supply port (13) with one annular groove (54), which Can be efficiently discharged. This fuel discharge is continued until the plunger (50) moves further upward so that the annular groove (54) is located above the fuel supply port (13), and the lower lead (52) is connected to the fuel supply port (13). When the communication is established, the injection is completed.

In this pumping process, in the low to medium speed range where the moving speed of the plunger (50) is low, the time for which the fuel supply port (13) communicates with the annular groove (54) becomes long, so that a large amount of fuel is discharged and the pumping capacity is increased. Is sufficiently reduced, the pressure rise in the pumping chamber (11) is moderated, and the injection period is lengthened, whereby the combustion noise can be reduced.

On the other hand, in the high-speed and high-load region, the movement speed of the plunger (50) is high, and the time for communicating the fuel supply port (13) and the annular groove (54) is short, so that the fuel discharge amount is small and the pumping capacity is almost zero. Does not drop much. Therefore, the injection period becomes longer in the low and medium speed ranges, but in the high speed and high load range, the injection period can be shortened to maintain good combustion performance with good injection termination.

To control the injection amount, the effective stroke is changed by rotating the plunger (50) in the horizontal direction. In this case, the relative stroke between the fuel supply port (13) and the annular groove (54) is changed. Although the position will change, the total length of the fuel discharge path, that is, the total length of the two fuel discharge paths described above, is always the total length of the annular groove (54) and may vary. Absent. Therefore, regardless of the rotational position of the plunger (50), the fuel discharge condition can always be kept constant, and the fuel control in the pumping chamber (11) can be performed with high accuracy. In addition, a groove for returning a part of the fuel in the pumping chamber (11) to the fuel supply port (13) during the pumping process is formed in an annular shape formed over the entire outer peripheral surface of the plunger (50) as described above. If the groove (54) is used, a groove is also present at the deepest position of the lower lead (52), and the fuel in the pumping chamber (11) is discharged even at the start when the injection amount needs to be the dog. Will be done. However, the deterioration of the startability caused by the fuel discharge has been eliminated by adjusting the cam speed or changing the size and shape of each groove.

The plunger structure that achieves the above-described effects is not limited to the above-described one, and other plunger structures will be described below.

For example, as shown in FIG. 13, a pair of upper and lower annular grooves (54) parallel to each other may be formed on the outer peripheral surface of the plunger (50). In this case, there will be a total of four fuel discharge routes, which can significantly improve the fuel discharge efficiency.

Also, in the plunger (50) having a large effective stroke, the annular groove (54) and the upper end of the lower lead (52) may not intersect. In such a case, FIG. As shown in FIG. 4 and FIG. 15, cutouts (60) and (61) are formed on the outer peripheral surface of the plunger (50) to connect them. The notch (60) in FIG. 14 has a stepped notch near the upper end of the outer peripheral surface of the plunger (50), and the notch (61) in FIG. 15 has a tapered notch. .

Further, the plunger (50) not only has a vertical groove (51) formed at the center thereof, but also has a vertical groove formed on the outer peripheral surface thereof for communicating the pressure feeding chamber (11) and the lower lead (52). Many things can be seen. In the case of such a plunger, as shown in FIG. 16, if an annular groove (54) is formed, the annular groove (54) is inevitably provided through the vertical groove (62). ), So that it is not necessary to form a lateral groove for communicating the vertical groove and the lower lead and the above-mentioned notch.

Claims

The scope of the claims

1. A fuel injection pump in which a delivery valve having a fuel suction function is slidably disposed in a fuel passage communicating between a high pressure chamber to which an injection nozzle or the like is connected and a pressure feeding chamber. At the stage before the angle communication is performed and before the communication area of the fuel passage is maximized, apart from the enlargement of the communication area of the fuel passage due to the angler cut, the movement of the delivery valve is accompanied by the movement of the delivery valve. A fuel injection pump comprising a communication area expanding means for expanding a communication area of a passage.

2. The fuel injection pump according to claim 1, wherein said communication area expanding means comprises a cutout formed in at least one of a suction / return collar of said delivery valve and a wall surface of said fuel passage.

3. The fuel injection pump according to claim 2, wherein the cutout portion is formed by cutting a sliding surface of the suction and return collar into a stepped shape.

4. The fuel injection pump according to claim 2, wherein the cutout portion is formed by cutting out a sliding surface of the suction / return collar in an inclined manner.

5. The fuel injection pump according to any one of claims 2 to 4, wherein the notch is formed by cutting out a portion of the suction-back collar where the angle reduction is performed.

6. A plunger having a lower lead formed on its outer peripheral surface is slidably inserted into the pumping chamber, and a fuel supply port opening toward the pumping chamber is closed by the tip of the plunger. In the fuel injection pump configured to cause the fuel in the pumping chamber to be pumped before being opened, an annular groove communicating with the lower lead is formed on an outer peripheral surface of the plunger, and the pumping is performed during the pumping step. A fuel injection pump wherein a part of the fuel in the room is returned to the fuel supply port through the annular groove.

7. The fuel injection pump according to claim 6, wherein the annular groove has the same cross-sectional shape over the entire circumference.

8. The fuel injection pump according to claim 6, wherein the annular groove has a groove width smaller than a diameter of the fuel supply port.