WO2014171410A1

WO2014171410A1 - Fuel injection pump

Info

Publication number: WO2014171410A1
Application number: PCT/JP2014/060520
Authority: WO
Inventors: 信也入口
Original assignee: 三菱重工業株式会社
Priority date: 2013-04-16
Filing date: 2014-04-11
Publication date: 2014-10-23
Also published as: CN105074192A; KR20150114545A; JP2014208988A

Abstract

Provided is a fuel injection pump capable of suppressing the occurrence of cavitation. The fuel injection pump comprises: a pump case; a plunger barrel (30) formed in a tube shape and housed inside the pump case; an oil supply/discharge hole (35) penetrating a peripheral wall section (31) of the plunger barrel (30) and discharging at least the fuel inside the plunger barrel (30) to outside the plunger barrel (30); a plunger (45) slidably arranged inside the plunger barrel (30), pressurizing the fuel inside the plunger barrel (30), and opening and closing an opening (36) that opens to the inner peripheral surface of the plunger barrel (30) in the oil supply/discharge hole (35); and a deflector (40) rectifying fuel flowing inside the oil supply/discharge hole (35), and arranged inside the oil supply/discharge hole (35), positioned eccentrically towards the opening commencement side when the opening section (36) is opened using the plunger (45) during discharge of fuel inside the plunger barrel (30) from the oil supply/discharge hole (35).

Description

Fuel injection pump

The present invention relates to a fuel injection pump.

A fuel injection pump used for an internal combustion engine that operates by injecting fuel into a combustion chamber, such as a diesel engine, supplies fuel pressurized to a high pressure during operation of the engine to a fuel injection valve attached to a cylinder head It is possible to For example, in a fuel injection device described in Patent Document 1, a plunger which is installed in a pump housing and pressurizes fuel by being driven in an axial direction, a cam shaft which rotates with the rotation of a crankshaft, and a plunger It has a tappet connected and facing the cam on the camshaft. Thus, during operation of the engine, the fuel injection pump can supply fuel to the fuel injection valve side by pressurizing the fuel with a plunger operated by the rotation of the camshaft rotating with the rotation of the crankshaft. .

Further, in such a fuel injection pump, after completion of fuel injection, the high pressure fuel in the pressurizing chamber constituted by the barrel and the plunger is the oil drain hole of the fuel formed in the barrel (a hole through which the fuel flows, oil passing It is discharged to the outside of the barrel at high speed from the hole. In this case, when the high-pressure fuel flows out from the pressurizing chamber into the oil drain hole, cavitation may occur due to a sharp drop in fuel pressure. For this reason, in a conventional fuel injection pump, a deflector having a substantially conical protruding portion is provided in an oil discharge hole formed in a barrel to rectify the flow of high pressure fuel discharged through the oil discharge hole. In some cases, the occurrence of cavitation is suppressed. For example, in the fuel injection pump described in Patent Document 2, an intake and exhaust port penetrating the peripheral wall portion is formed in a barrel to which a plunger is slidably inserted, and a deflector is fixed to the intake and exhaust port.

JP 2002-54530 A JP 2000-179428 A

However, when high pressure fuel flows to the oil outlet at the end of fuel injection, the fuel flowing through the oil outlet may be a high speed jet like jet due to the pressure difference with the fuel in the barrel. Cavitation may occur when a high-speed jet-like jet flows in the oil drain hole. If cavitation occurs and collides with the inner surface of the oil drainage hole or deflector, the cavitation may collapse and wear, that is, erosion may occur on the surface of the member, resulting in a decrease in product life.

In addition, at the end of fuel injection, immediately after opening of the oil drain hole by opening of the oil drain hole by actuation of the plunger, the flow of fuel flowing in the oil drain hole is biased. It becomes easy to produce parts where the speed is faster. In the fuel injection pump, cavitation may occur in the oil drain hole even by such a local increase in fuel velocity, and this cavitation may cause erosion.

This invention is made in view of the above, Comprising: It aims at providing the fuel injection pump which can suppress generation | occurrence | production of a cavitation.

In order to solve the problems described above and to achieve the object, a fuel injection pump according to the present invention includes a pump body, a barrel formed in a tubular shape and inserted into the pump body, and a peripheral wall portion of the barrel An oil passing hole for discharging the fuel in the barrel to the outside of the barrel, and slidably installed in the barrel to pressurize the fuel in the barrel, and A plunger for opening and closing an opening opened to the inner peripheral surface, straightening the fuel flowing in the oil passing hole, and opening the opening by the plunger when the fuel in the barrel is discharged from the oil passing hole And a deflector provided eccentrically in the oil passage on the opening start side in the case.

In this invention, since the deflector is disposed eccentrically on the opening start side when the opening is opened by the plunger when the fuel in the barrel is discharged from the oil passing hole, the internal flow when the fuel flows in the oil passing hole Can be made uniform. As a result, it is possible to suppress the local increase in the velocity of the fuel, and to suppress the occurrence of cavitation caused by the increase in the fuel velocity.

In the fuel injection pump, preferably, the oil passage hole penetrates the peripheral wall portion of the barrel in a direction inclined with respect to the radial direction of the barrel.

In the present invention, since the oil passing hole is formed in the direction inclined with respect to the radial direction of the barrel, the ratio of the change of the opening area of the opening to the lift amount of the plunger can be increased. Thus, the pressure difference between the fuel in the barrel and the fuel in the oil passing hole can be reduced in a short time, so that the fuel flowing into the oil passing hole can be prevented from becoming a jet flow. it can. As a result, the occurrence of cavitation due to the fuel becoming a jet-like jet can be suppressed.

In the fuel injection pump, the oil passage hole has a plurality of downstream side holes defined around the deflector, and the downstream side holes are formed by opening the opening by the plunger. The opening area in the flow direction of the fuel flowing through the oil passing hole is the opening area of the downstream side hole located on the open end side of the downstream side hole located on the opening side in the It is preferable to be large.

In the present invention, the opening areas of the plurality of wake side holes are made larger in the wake side holes located on the open end side than the wake side holes located on the opening start side of the opening. As a result, the internal flow can be made uniform when the fuel flows into the wake side hole. As a result, it is possible to more reliably suppress the local increase in the velocity of the fuel, and to more reliably suppress the occurrence of cavitation.

Further, in order to solve the problems described above and achieve the object, the fuel injection pump according to the present invention includes a pump body, a barrel formed in a tubular shape, and fitted in the pump body and sliding on the barrel A plunger, which is internally installed to pressurize the fuel in the barrel, discharges at least the fuel in the barrel to the outside of the barrel, and a peripheral wall portion of the barrel in a direction inclined with respect to the radial direction of the barrel And an oil passing hole through which the plunger opens and closes an opening opened on the inner circumferential surface of the barrel.

The fuel injection pump according to the present invention has the effect of being able to suppress the occurrence of cavitation.

FIG. 1 is a system diagram of a fuel injection system including a fuel injection pump according to a first embodiment. FIG. 2 is a cross-sectional view of the fuel injection pump shown in FIG. FIG. 3 is a detailed view of part A of FIG. FIG. 4 is a view as viewed in the direction of the arrows BB in FIG. FIG. 5 is an explanatory view when fuel flows into the plunger chamber. FIG. 6 is an explanatory view when the fuel is pressurized in the plunger chamber. FIG. 7 is an explanatory view when the fuel is discharged from the plunger chamber. FIG. 8 is an explanatory view of a state where the oil supply and discharge oil hole starts to open by the lead groove. FIG. 9 is a cross-sectional view of the plunger barrel of the fuel injection pump according to the second embodiment as viewed in the axial direction. FIG. 10 is an explanatory view of the case where the oil supply and discharge oil holes are formed in the radial direction of the plunger barrel. FIG. 11 is an explanatory view of the change of the opening area of the oil supply and discharge hole with respect to the change of the lift amount of the plunger when opening and closing the opening of the oil supply and oil hole shown in FIG. FIG. 12 is an explanatory view of the change in the opening area of the oil supply and discharge hole with respect to the change in the lift amount of the plunger when opening and closing the opening of the oil supply and oil hole shown in FIG.

Hereinafter, an embodiment of a fuel injection pump according to the present invention will be described in detail based on the drawings. The present invention is not limited by this embodiment. Further, constituent elements in the following embodiments include those that can be easily replaced by persons skilled in the art or those that are substantially the same.

Embodiment 1
FIG. 1 is a system diagram of a fuel injection system including a fuel injection pump according to a first embodiment. The fuel injection pump 20 according to the first embodiment is included in a fuel injection system 1 that injects fuel into a combustion chamber 6 of a diesel engine 5 that is an example of an internal combustion engine. In the fuel injection system 1, the fuel supply pump 12 is connected to a fuel tank 10 storing fuel, and the fuel in the fuel tank 10 flows through the fuel injection system 1 by the fuel supply pump 12. It is possible to pump to the downstream side in the flow direction of.

A fuel filter 13 for removing impurities by filtering the fuel is disposed on the downstream side of the fuel pump 12, and the fuel main pipe 14 located on the downstream side of the fuel filter 13 is used for the cylinders of the diesel engine 5. Correspondingly, a plurality of fueling branch pipes 15 are branched. A plurality of fuel injection pumps 20 are connected to each fueling branch pipe 15. In the diesel engine 5, fuel injection valves 17 are disposed for each cylinder, and each fuel injection pump 20 is connected to the fuel injection valves 17 via injection pipes 16, respectively.

FIG. 2 is a cross-sectional view of the fuel injection pump shown in FIG. The fuel injection pump 20 has a pump case 25 which is a pump body, and a plunger barrel 30 which is a cylindrical barrel is internally provided inside the pump case 25. A plurality of oil supply / discharge oil holes (also referred to as holes through which fuel flows, oil passage holes) 35 which are holes penetrating the peripheral wall portion 31 of the plunger barrel 30 are formed in the plunger barrel 30. The oil supply / discharge oil holes 35 are capable of supplying fuel from the outside of the plunger barrel 30 to the inside of the plunger barrel 30 and discharging the fuel from the inside of the plunger barrel 30 to the outside of the plunger barrel 30. It is an oil hole. That is, the oil supply / discharge oil hole 35 doubles as an oil supply hole for supplying fuel into the plunger barrel 30 and an oil discharge hole for discharging the fuel in the plunger barrel 30.

In the pump case 25, an oil supply and discharge oil chamber 26 into which the fuel supplied from the oil supply pump 12 via the oil supply branch pipe 15 and the like flows is formed on the inner surface side. The oil drain hole 35 has an opening on the outer peripheral surface side of the plunger barrel 30 open to the oil drain chamber 26, and between the oil drain chamber 26 and the inside of the plunger barrel 30. It is possible to refuel and discharge fuel.

Further, it is provided inside the plunger barrel 30 so as to be reciprocally slidable in the axial direction of the cylinder to pressurize the fuel in the plunger barrel 30, and to the inner peripheral surface of the plunger barrel 30 at the oil supply / discharge oil hole 35. A plunger 45 is provided to open and close the opened opening 36 (see FIG. 3).

A discharge valve 55 and a valve seat 56 of the discharge valve 55 are disposed on one end side of the plunger barrel 30, and further, on the opposite side of the discharge valve 55 on which the plunger barrel 30 is located. The discharge connector 60 is disposed. Among them, the discharge valve 55 is disposed to be able to reciprocate in the axial direction of the plunger barrel 30 in the same manner as the plunger 45, and a biasing force is applied to the valve seat 56 by the discharge valve spring 57. . The discharge valve 55 reciprocates in this manner and closely adheres to the valve seat 56, so that communication and shutoff between the inside of the plunger barrel 30 and the inside of the discharge connector 60 can be switched.

Further, a fuel discharge port 61 for discharging the fuel flowing from the plunger barrel 30 side is formed on the end of the discharge connector 60 opposite to the side where the valve seat 56 is located. The other end side of the injection pipe 16 connected to the fuel injection valve 17 is connected to the discharge connector 60, and the fuel discharged from the fuel discharge port 61 can be supplied to the fuel injection valve 17.

The plunger 45 provided in the plunger barrel 30 is provided with an upper end surface 45f, which is an end surface on which the valve seat 56 is located, a surface of the valve seat 56 facing the plunger 45, and an inner surface of the plunger barrel 30. A plunger chamber 50 is defined to pressurize.

Further, in the plunger 45, a lead groove 46, which is an oil passage through which fuel passes, is formed on the outer peripheral surface. The lead groove 46 is formed in a groove shape recessed from the other portion of the outer peripheral surface of the plunger 45, and is formed from the upper end surface 45f of the plunger 45 to a predetermined range of the outer peripheral surface. More specifically, the lead groove 46 is positioned on the upper lead 47 which is a groove wall located on the upper end surface 45 f side, and on the opposite end side opposite to the side where the upper end surface 45 f is located in the plunger 45 And a lower lead 48 which is a groove wall.

At the end of the plunger 45 opposite to the upper end face 45f, a fuel cam 65 for transmitting a force for causing the plunger 45 to reciprocate using the power of the diesel engine 5 is disposed. The fuel cam 65 rotates in conjunction with the crankshaft by transmitting to the fuel cam 65 a part of the motive power output by the rotation of the crankshaft (not shown) of the diesel engine 5 via the plurality of gears. It is possible.

A tappet 66 is connected to an end of the plunger 45 on the fuel cam 65 side. The tappet 66 is disposed so as to be capable of reciprocating with the plunger 45, and a biasing force in the direction to approach the fuel cam 65 is applied by the tappet spring 68. That is, the plunger 45 is biased by the tappet spring 68 in a direction to move away from the valve seat 56 and approach the fuel cam 65.

Further, a tappet roller 67 in contact with the fuel cam 65 is disposed at a portion of the tappet 66 facing the fuel cam 65. The tappet roller 67 is rotatably disposed so that the rotation axis is parallel to the rotation axis of the fuel cam 65, and is pressed against the fuel cam 65 by the biasing force of the tappet spring 68 applied to the tappet 66. In contact with the fuel cam 65.

FIG. 3 is a detailed view of part A of FIG. A deflector 40 that rectifies the fuel flowing in the oil supply and discharge hole 35 is provided in the oil supply and discharge oil hole 35. The deflector 40 is provided to a deflector unit 43 in which the deflector 40 and an attachment portion 44 for attaching the deflector 40 to the plunger barrel 30 are integrated. The deflector unit 43 is attached to the plunger barrel 30 by attaching a mounting portion 44 with a screw 33 from the outer peripheral surface side of the plunger barrel 30 in a direction in which the deflector 40 is installed in the oil supply / discharge hole 35.

The deflector 40 extends in a direction from the outer peripheral surface side to the inner peripheral surface side of the plunger barrel 30 and is provided in the oil supply / discharge oil hole 35, and the end on the inner peripheral surface side is the oil supply / discharge oil hole 35. It does not go out into the plunger barrel 30 from the opening 36, but is located in the oil supply / discharge oil hole 35.

Further, a tip end portion 41 which is a predetermined range from the end portion on the inner peripheral surface side of the plunger barrel 30 in the deflector 40 to the outer peripheral surface side has a substantially conical shape whose diameter decreases toward the inner peripheral surface side of the plunger barrel 30 It is in the shape of a shape. The height direction of the front end portion 41 of the deflector 40 is the formation direction of the oil supply / discharge oil hole 35, the apex is located on the inner peripheral surface side of the plunger barrel 30, and the bottom surface is located on the outer peripheral surface side of the plunger barrel 30. , The apex is formed in a curved surface shape.

Further, the deflector 40 is eccentric to the opening start side when the opening portion 36 is opened by the plunger 45 when the fuel in the plunger barrel 30 is discharged from the oil supply and discharge hole 35 in the reciprocating direction of the plunger 45 . Specifically, when the plunger 45 moves from the fuel cam 65 side to the direction of the plunger chamber 50, the oil supply / discharge oil hole 35 is in a state where the lead groove 46 faces the opening 36 of the oil supply / discharge oil hole 35. At the same time, the fuel flowing through the lead groove 46 is discharged to the oil supply and discharge chamber 26 side. Therefore, the deflector 40 is eccentric to the side of the fuel cam 65 which is the opening start side when the opening 36 is opened by the plunger 45.

Further, as a result, in the portion where the deflector 40 in the oil supply / discharge oil hole 35 is disposed, the portion on the discharge valve 55 side of the portion on the fuel cam 65 side is a flow path in the direction of reciprocation of the plunger 45 The width is getting bigger.

FIG. 4 is a view as viewed in the direction of the arrows BB in FIG. The oil supply and discharge oil holes 35 have a plurality of wake side holes 37 defined around the deflector 40. The downstream side holes 37 are respectively formed as holes along the direction in which the oil supply and discharge oil holes 35 are formed, and the plurality of downstream side holes 37 are formed around the deflector 40 as the downstream side holes. Plural pieces are formed side by side along the circumferential direction of 37. That is, in the oil supply and discharge oil hole 35, a plurality of downstream flow holes 37 are open to the oil supply and discharge oil chamber 26.

A plurality of downstream holes 37 formed in this manner are downstream holes located closer to the end of the opening than the downstream holes 37 located on the opening start side when the opening 36 is opened by the plunger 45. The part 37 has a larger opening area when viewed in the flow direction of the fuel flowing through the oil supply and discharge hole 35. That is, the downstream side hole 37 has an opening area in the downstream side hole 37 located closer to the discharge valve 55 than the downstream side hole 37 located closer to the fuel cam 65. It is getting bigger.

The fuel injection pump 20 according to the first embodiment is configured as described above, and the operation thereof will be described below. During operation of the diesel engine 5, the fuel in the fuel tank 10 is filtered by the fuel filter 13 by driving the fuel supply pump 12 and supplied to the fuel injection pump 20. The fuel supplied to the fuel injection pump 20 flows into the oil supply and discharge oil chamber 26 formed between the pump case 25 and the plunger barrel 30.

On the other hand, when the diesel engine 5 is in operation, the fuel injection pump 20 rotates the fuel cam 65 in conjunction with the crankshaft. Thus, the tappet roller 67 pressed against the fuel cam 65 by the biasing force from the tappet spring 68 moves in the direction of the reciprocating movement of the plunger 45 along the shape of the surface of the fuel cam 65. Along with this, the tappet 66 provided with the tappet roller 67 and the plunger 45 connected with the tappet 66 also reciprocate with the tappet roller 67. Thus, the plunger 45 of the fuel injection pump 20 reciprocates in conjunction with the rotation of the crankshaft of the diesel engine 5, and the position at the time of the reciprocation is a position corresponding to the rotational position of the crankshaft.

The fuel injection pump 20 reciprocates the plunger 45 to take in the fuel that has flowed into the oil supply and discharge chamber 26 from the oil supply and discharge hole 35 into the plunger chamber 50, and pressurizes the fuel in the plunger chamber 50 to discharge the fuel. Send to the 55 side. The discharge valve 55 is normally in a state in which the inside of the plunger barrel 30 and the inside of the discharge connector 60 are shut off by the biasing force of the discharge valve spring 57, but the force applied to the discharge valve 55 from pressurized fuel When the pressure of the discharge valve spring 57 becomes larger than that of the discharge valve spring 57, the discharge valve 55 separates from the valve seat 56.

As a result, the discharge valve 55 is in communication with the inside of the plunger barrel 30 and the inside of the discharge connector 60, and the fuel pressurized by the plunger chamber 50 flows into the discharge connector 60. The high-pressure fuel flowing into the discharge connector 60 is discharged from the fuel discharge port 61, supplied to the fuel injection valve 17 through the injection pipe 16, and injected from the fuel injection valve 17 into the combustion chamber 6 of the diesel engine 5. The fuel injected into the combustion chamber 6 burns in the combustion chamber 6, and the combustion of the fuel drives the diesel engine 5.

The fuel injection pump 20 supplies high-pressure fuel to the fuel injection valve 17 by the reciprocating movement of the plunger 45 in the plunger barrel 30 as described above. Next, the flow of fuel relative to the movement of the plunger 45 explain.

FIG. 5 is an explanatory view when fuel flows into the plunger chamber. When the fuel flows into the plunger chamber 50, the plunger 45 opens the opening 36 of the oil supply / discharge oil hole 35, and the plunger 45 faces the fuel cam 65 in a state where the oil supply / discharge oil hole 35 and the plunger chamber 50 are in communication. The plunger chamber 50 is moved to a negative pressure with respect to the oil supply and discharge chamber 26. That is, the direction of the fuel cam 65 is such that the upper end surface 45 f of the plunger 45 is positioned closer to the fuel cam 65 than the end on the discharge valve 55 side of the opening 36 of the oil supply / discharge oil hole 35 of the plunger barrel 30. As a result, the fuel in the oil supply and discharge chamber 26 is drawn into the plunger chamber 50. Thereby, the fuel in the oil supply and discharge oil chamber 26 flows from the inside of the oil supply and discharge oil chamber 26 into the plunger chamber 50 through the oil supply and discharge oil hole 35.

FIG. 6 is an explanatory view when the fuel is pressurized in the plunger chamber. The plunger 45 moves in the direction of the discharge valve 55 in a state where the fuel flows into the plunger chamber 50, and further moves in the direction of the discharge valve 55 in a state where the opening portion 36 of the oil supply and discharge oil hole 35 is closed. The fuel in the plunger chamber 50 is pressurized. In this case, the fuel in the plunger chamber 50 is pressurized without a pressure relief, so the fuel is at a high pressure. When the force applied to the discharge valve 55 from the fuel thus high in pressure becomes greater than the biasing force of the discharge valve spring 57, the discharge valve 55 separates from the valve seat 56, and the inside of the plunger chamber 50 The fuel flows into the discharge connector 60 and is discharged from the fuel discharge port 61.

FIG. 7 is an explanatory view when the fuel is discharged from the plunger chamber. When the fuel in the plunger chamber 50 is pushed out of the plunger chamber 50 and the plunger 45 further moves in the direction of the discharge valve 55, the lead groove 46 of the plunger 45 is engaged with the oil supply / discharge oil hole 35. Since the lead groove 46 is in communication with the upper end surface 45 f of the plunger 45, high pressure fuel is flowing through the lead groove 46 in the same manner as in the plunger chamber 50. For this reason, when the opening 36 of the oil supply / discharge hole 35 is opened by the lead groove 46 covering the oil supply / discharge oil hole 35, high pressure fuel flowing through the lead groove 46 is contained in the oil supply / discharge oil hole 35. To flow. The fuel that has flowed into the oil supply and discharge oil holes 35 is rectified by the deflector 40 and discharged to the outside of the plunger 45. Thereby, the fuel in the plunger barrel 30 returns to the oil supply and discharge chamber 26 through the oil supply and discharge oil hole 35.

Here, when the oil supply and drain hole 35 starts to open in a high pressure state of fuel, the fuel vigorously flows into the oil supply and drain hole 35 from the opening start side of the oil supply and drain hole 35, but the deflector 40 Since the fuel is disposed eccentrically in the oil supply and discharge hole 35, the fuel flowing into the oil supply and discharge oil hole 35 flows while the flow rate in the oil supply and discharge oil hole 35 is adjusted.

Next, a case where high-pressure fuel starts to flow into the oil supply and discharge holes 35 when the oil supply and discharge holes 35 begin to open by the lead groove 46 will be described. FIG. 8 is an explanatory view of a state where the oil supply and discharge oil hole starts to open by the lead groove. When the plunger 45 moves in the direction of the discharge valve 55, the upper lead 47 of the lead groove 46 of the plunger 45 is closer to the discharge valve 55 than the end on the fuel cam 65 side in the opening 36. Opening when it is located closer. For this reason, the oil supply / discharge oil hole 35 first opens to the inside of the lead groove 46 from the vicinity of the end on the fuel cam 65 side in the opening 36, and the fuel flowing in the lead groove 46 is the fuel cam 65 in the The oil flows into the oil supply and drainage hole 35 from the vicinity of the side end.

Since the fuel flowing in the lead groove 46 in this case has a high pressure, the high pressure fuel flows into the oil supply and discharge oil holes 35. That is, when the oil supply and discharge oil hole 35 starts to open, more high pressure fuel flows in a portion near the fuel cam 65 in the oil supply and discharge oil hole 35.

Here, at the portion where the deflector 40 is disposed, the width of the flow passage in the direction of the reciprocation of the plunger 45 becomes larger at the discharge valve 55 side than at the fuel cam 65 side in the oil supply / discharge oil hole 35 Therefore, as the shape of the oil supply and discharge oil holes 35, the fuel tends to flow more toward the discharge valve 55. Similarly, the downstream side hole 37 formed in the oil supply / discharge oil hole 35 has the downstream side hole 37 closer to the discharge valve 55 than the downstream side hole 37 closer to the fuel cam 65. Since the opening area is large, the flow of the fuel is more facilitated in the wake side hole 37 closer to the discharge valve 55 in the wake side hole 37.

On the other hand, the high-pressure fuel flowing in the oil supply and discharge oil hole 35 immediately after the opening 36 starts to open flows more to the portion near the fuel cam 65 in the oil supply and oil drainage hole 35. The tendency of the flow of the fuel due to the shape and the tendency of the flow of the fuel due to the opening of the oil supply and discharge oil holes 35 are in a contradictory state.

For this reason, the flow of fuel flowing in the oil supply and discharge oil hole 35 cancels the tendency of the flow due to both factors, and the same amount of fuel flows between the position near the fuel cam 65 and the position near the discharge valve 55 As a result, high-pressure fuel flows in the oil supply and discharge oil hole 35 immediately after the opening 36 starts to open, without generation of drift. As a result, the oil supply / discharge oil holes 35 can equalize the internal flow and discharge the fuel in the plunger barrel 30 to the outside of the plunger barrel 30, that is, the oil supply / discharge oil chamber 26 side.

In the fuel injection pump 20 according to the first embodiment described above, the deflector 40 is disposed eccentrically to the opening start side when the opening 36 is opened by the plunger 45 when the fuel in the plunger barrel 30 is discharged from the oil supply and discharge oil hole 35. As a result, the internal flow when the fuel flows into the oil supply and discharge oil holes 35 can be made uniform. As a result, it is possible to suppress the local increase in the velocity of the fuel, and to suppress the occurrence of cavitation caused by the increase in the fuel velocity. Further, by suppressing the occurrence of cavitation, the occurrence of erosion on the surface of the member due to the collapse of the cavitation can be suppressed, and a decrease in product life can be suppressed.

Further, the plurality of downstream flow holes 37 included in the oil supply and discharge oil holes 35 are downstream of the downstream flow holes 37 located on the opening start side of the opening 36 and are located downstream of the downstream flow holes 37. Since the opening area is larger, the internal flow when the fuel flows in the wake side hole 37 can be made uniform. As a result, it is possible to more reliably suppress the local increase in the velocity of the fuel, and to more reliably suppress the occurrence of cavitation.

Second Embodiment
The fuel injection pump 20 according to the second embodiment has substantially the same configuration as the fuel injection pump 20 according to the first embodiment, but is characterized in that the oil supply and discharge oil holes 35 of the plunger barrel 30 are inclined. The other configuration is the same as that of the first embodiment, and thus the description thereof is omitted and the same reference numeral is attached.

FIG. 9 is a cross-sectional view of the plunger barrel of the fuel injection pump according to the second embodiment as viewed in the axial direction. In the fuel injection pump 20 according to the second embodiment, like the fuel injection pump 20 according to the first embodiment, the plunger barrel 30 penetrates the peripheral wall 31 and at least the fuel in the plunger barrel 30 is the plunger barrel 30. A plurality of oil supply and discharge oil holes 35 which can be discharged to the outside are formed. Unlike the first embodiment, the oil supply and discharge oil holes 35 are formed eccentrically from the center of the plunger barrel 30. More specifically, the oil supply / discharge oil hole 35 is a hole which is perpendicular to the axial center direction of the plunger barrel 30 formed in a cylindrical shape, and which penetrates the peripheral wall 31 in a direction inclined with respect to the radial direction of the plunger barrel 30 It is formed. A deflector 40 is disposed concentrically with the axial center of the oil supply / discharge hole 35 in the oil supply / discharge oil hole 35 formed in this manner.

The fuel injection pump 20 according to the second embodiment is configured as described above, and the operation thereof will be described below. Similarly to the fuel injection pump 20 according to the first embodiment, in the fuel injection pump 20 according to the second embodiment, the plunger 45 rotates in conjunction with the rotation of the fuel cam 65 in conjunction with the crankshaft of the diesel engine 5. Reciprocate in the plunger barrel 30. As a result, the plunger 45 opens and closes the opening 36 of the oil supply / discharge oil hole 35, sucks the fuel into the plunger chamber 50, pressurizes the fuel and supplies it to the fuel injection valve 17 side. The fuel is discharged from the oil supply and discharge port 35 or the like.

Here, since the oil supply and discharge oil hole 35 is formed in a direction inclined with respect to the radial direction of the plunger barrel 30, the area of the opening 36 is larger than the opening area of the oil supply and discharge oil hole 35 in the formation direction. It is getting bigger. Therefore, in the fuel injection pump 20 according to the second embodiment, the amount of change in the opening area of the opening 36 with respect to the amount of movement of the plunger 45 when the plunger 45 is reciprocated is large.

FIG. 10 is an explanatory view of the case where the oil supply and discharge oil holes are formed in the radial direction of the plunger barrel. FIG. 11 is an explanatory view of the change of the opening area of the oil supply and discharge hole with respect to the change of the lift amount of the plunger when opening and closing the opening of the oil supply and oil hole shown in FIG. That is, as shown in FIG. 10, when the oil supply / discharge oil hole 35 is formed in a direction along the radial direction of the plunger barrel 30, the shape of the opening 36 is a shape as viewed in the formation direction of the oil supply / discharge oil hole 35. It becomes an approximate shape. For this reason, the area of the opening 36 is approximately equal to the opening area of the oil supply and discharge hole 35 in the same direction. Thus, when the oil supply / discharge oil hole 35 is formed, when the plunger 45 reciprocates, the opening area of the opening 36 changes the lift amount which is the movement amount of the plunger 45 as shown in FIG. Change as you do. That is, as the lift amount of the plunger 45 increases, the opening area of the opening 36 also increases.

On the other hand, when the oil supply / discharge oil hole 35 is formed in a direction inclined with respect to the radial direction of the plunger barrel 30, the shape of the opening 36 is the same as the shape viewed in the formation direction of the oil supply / discharge oil hole 35. The circumferential size of the plunger barrel 30 is increased. For this reason, the area of the opening 36 is larger than the opening area of the oil supply and discharge hole 35 in the formation direction.

FIG. 12 is an explanatory view of the change in the opening area of the oil supply and discharge hole with respect to the change in the lift amount of the plunger when opening and closing the opening of the oil supply and oil hole shown in FIG. When the oil supply / discharge oil hole 35 is formed in a direction inclined with respect to the radial direction of the plunger barrel 30, the size of the opening 36 in the moving direction of the plunger 45 corresponds to the diameter of the plunger barrel 30 It is the same size as when formed in the direction along the direction. Therefore, the distance from the fully closed position to the fully open position of the opening 36 with respect to the movement range of the plunger barrel 30 is constant regardless of the direction of the oil supply and discharge oil holes 35 with respect to the radial direction of the plunger barrel 30.

Therefore, when the opening portion 36 having the large opening area is opened and closed by the plunger 45, as shown in FIG. 12, the change of the opening area of the opening portion 36 with respect to the change of the lift amount of the plunger 45 becomes large. That is, in the fuel injection pump 20 according to the second embodiment, when the lift amount of the plunger 45 is increased from the state where the opening 36 is closed to open the opening 36 of the oil supply / discharge oil hole 35, As compared with the case where the oil supply and discharge holes 35 are formed in the radial direction, the change of the opening area to the change of the lift amount becomes significantly large.

In other words, in the fuel injection pump 20 according to the second embodiment, the opening area increase rate of the opening 36 per unit lift is large. Therefore, when the high pressure fuel in the plunger barrel 30 is discharged by the oil drain hole 35 by making the opening 36 of the oil drain hole 35 face the lead groove 46 of the plunger 45 and opening the opening 36, The fuel in the plunger barrel 30 can be flowed into the oil supply and discharge port 35 in a short time. Thereby, the pressure difference between the fuel of the plunger barrel 30 and the fuel in the oil supply and discharge port 35 can be reduced in a short time and discharged.

In the fuel injection pump 20 according to the second embodiment described above, since the oil supply and discharge oil holes 35 are formed in the direction inclined with respect to the radial direction of the plunger barrel 30, the ratio of the change of the opening area to the lift amount of the plunger 45 Can be increased. As a result, the pressure difference between the fuel in the plunger barrel 30 and the fuel in the oil supply / discharge port 35 can be reduced in a short time, so that the fuel flowing into the oil supply / discharge port 35 becomes a jet flow. Can be suppressed. As a result, the occurrence of cavitation due to the fuel becoming a jet-like jet can be suppressed. In addition, by suppressing the occurrence of cavitation, the occurrence of erosion can be suppressed, and a decrease in product life can be suppressed.

[Modification]
In the fuel injection pump 20 according to the second embodiment, the deflector 40 is disposed concentrically with the axial center of the oil supply / discharge oil hole 35, but the deflector 40 is the same as the fuel injection pump 20 according to the first embodiment. The oil supply and discharge oil holes 35 may be eccentric. Even when the deflector 40 is disposed concentrically with the axis of the oil supply / discharge hole 35 as in the second embodiment, the oil supply / discharge oil hole 35 is formed in a direction inclined with respect to the radial direction of the plunger barrel 30. Thus, the occurrence of cavitation can be suppressed, and the occurrence of cavitation can be further suppressed when the deflector 40 is eccentric to the oil supply / discharge hole 35. Further, the oil supply and discharge oil holes 35 are formed in a direction inclined with respect to the radial direction of the plunger barrel 30 to make the deflector 40 eccentric, and further, from the wake side hole 37 located on the opening start side of the opening 36 The occurrence of cavitation can be suppressed more effectively by increasing the opening area of the wake-side hole 37 located on the open end side.

In addition, the fuel injection pump 20 may appropriately combine the configurations and the like used in the above-described embodiment and the modification, or may use a configuration other than the above-described configuration. Regardless of the configuration of the fuel injection pump 20, the deflector 40 is eccentrically installed in the oil supply / discharge hole 35, or the oil supply / discharge oil hole 35 is formed in a direction inclined with respect to the radial direction of the plunger barrel 30. Thus, the occurrence of cavitation can be suppressed.

DESCRIPTION OF SYMBOLS 1 fuel injection system 5 diesel engine 10 fuel tank 12 oil supply pump 17 fuel injection valve 20 fuel injection pump 25 pump case 26 oil supply and discharge chamber 30 plunger barrel 35 oil supply and discharge hole 36 opening 37 wake side hole 40 deflector 45 plunger 46 lead groove 50 plunger chamber 55 discharge valve 60 discharge connector 65 fuel cam 66 tappet

Claims

The pump body,
A barrel formed in a tubular shape and installed in the pump body;
An oil passing hole which penetrates the peripheral wall of the barrel and discharges at least the fuel in the barrel to the outside of the barrel;
A plunger slidably provided in the barrel to pressurize the fuel in the barrel and opening and closing an opening portion of the oil passing hole opened in the inner peripheral surface of the barrel;
The fuel flowing in the oil passing hole is rectified, and the fuel is discharged from the oil passing hole in the barrel, and the opening is eccentrically installed on the oil passing hole in the opening start side when the plunger is opened by the plunger. The deflector to be
A fuel injection pump comprising:
The fuel injection pump according to claim 1, wherein the oil passage hole penetrates a peripheral wall portion of the barrel in a direction inclined with respect to a radial direction of the barrel.
The oil passing hole has a plurality of wake side holes defined around the deflector,
In the wake-side hole, the wake-side hole located closer to the opening end than the wake-side hole located on the opening start side in the case where the opening is opened by the plunger is the The fuel injection pump according to claim 1 or 2, wherein the opening area in the flow direction of the fuel flowing through the oil passing hole is large.
The pump body,
A barrel formed in a tubular shape and installed in the pump body;
A plunger slidably installed in the barrel to pressurize fuel in the barrel;
At least the fuel in the barrel is discharged out of the barrel, penetrates the peripheral wall of the barrel in a direction inclined with respect to the radial direction of the barrel, and is opened to the inner circumferential surface of the barrel by the plunger Oil passing hole where opening and closing are done,
A fuel injection pump comprising: