WO2010079720A1 - Fuel injection pump - Google Patents

Abstract

A fuel injection pump (1) configured so as not cause blackening of fuel due to a lubricating oil mixed into the fuel after passing through a gap between a plunger (10) and a plunger barrel (11).  A fuel injection pump (1) is provided with a projecting guide section (12a) provided to a partition wall between a tappet chamber (16) below a plunger barrel (11) and a cam chamber (23) provided below the tappet chamber (16), and also with a roller tappet (20) inserted in the projecting guide section (12a) and connecting to the lower end of the plunger (10).  The roller tappet (20) is adapted to be able to reciprocate and slide along the projecting guide section (12a) of a pump case (12) in association with the rotational motion of a cam (21).  In the entire range of the sliding stroke of the roller tappet (20), the upper end of the roller tappet (20) always projects to the plunger barrel (11) side from the upper end surface of the projecting guide section (12a).

Description

Fuel injection pump

The present invention relates to a fuel injection pump of a fuel injection device mounted on an engine, and more particularly to a structure relating to prevention of mixing of lubricating oil into fuel in the fuel injection pump.

2. Description of the Related Art Conventionally, in a fuel injection pump of a fuel injection device mounted on an engine, a structure related to prevention of mixing of lubricating oil into fuel is known (for example, see Patent Document 1).
The fuel injection pump described in Patent Literature 1 includes a communication passage that communicates the inside of the tappet and the outside of the tappet.
The fuel injection pump described in Patent Document 1 can prevent the lubricating oil that has flowed into the tappet from being discharged to the outside of the tappet through the communication path, thereby preventing the lubricating oil from accumulating inside the tappet and being mixed into the fuel. .

JP 2005-146984 A

However, the fuel injection pump described in Patent Document 1 cannot prevent the lubricating oil from being applied to the plunger.
That is, in the fuel injection pump described in Patent Document 1, the lubricating oil applied to the plunger is mixed into the fuel through the gap between the plunger and the plunger barrel, which causes blackening of the fuel and incomplete combustion. There was a problem that exhaust smoke deteriorated due to the carbon flower adhering to the nozzle part of the fuel injection nozzle.

The problems to be solved by the present invention are as described above. Next, means for solving the problems will be described.

That is, in the present invention, a pump case, a hydraulic head provided on the top of the pump case, a plunger barrel inserted into the hydraulic head, a plunger sliding in the plunger barrel, An overhang guide portion provided in a partition wall between a tappet chamber below the plunger barrel and a cam chamber provided under the tappet chamber; a tappet inserted into the overhang guide portion and connected to the lower end of the plunger; A pressure chamber in which a fuel is pressurized between the upper end of the plunger and the plunger barrel, the campet being provided in a cam chamber below the tappet and contacting the tappet. Is a fuel injection pump that can reciprocate along the overhang guide portion of the pump case in conjunction with the rotational movement of the cam. Te, the upper end of the tappet is to always protrude into the plunger barrel side from the upper end surface of the projecting guide portions in the entire sliding stroke.

In the present invention, there is provided a scattering preventing member that protrudes in a direction orthogonal to the sliding direction of the tappet and prevents the lubricating oil from being applied to the plunger.

In the present invention, the scattering prevention member has a separate structure from the tappet.

In the present invention, the pump case is provided with a cam chamber that houses the cam member, and a rack chamber that includes a rack is provided on the upper surface of the pump case, and the cam chamber and the rack chamber are vented. And an inflow prevention member for preventing the lubricating oil from flowing into the vent hole.

In the present invention, the fuel injection pump is provided with a delivery valve that prevents the fuel from flowing into the pressurizing chamber, a distribution shaft that distributes the pumped fuel to the delivery valve, and a shaft coaxial with the distribution shaft. A transmission shaft for transmitting power to the distribution shaft, and a positioning member for positioning the axial position of the transmission shaft, and the inflow prevention member is fastened together with the positioning member to the pump case. It can be attached.

In the present invention, a pump case, a hydraulic head provided on the top of the pump case, a plunger barrel inserted into the hydraulic head, a plunger sliding in the plunger barrel, and the plunger barrel An overhang guide portion provided in a partition wall between a tappet chamber below the tappet chamber and a cam chamber provided under the tappet chamber, a tappet inserted into the overhang guide portion and connected to the lower end of the plunger, and the tappet And a cam that contacts the tappet, and a pressurizing chamber is provided between the upper end of the plunger and the plunger barrel to pressurize the fuel. A fuel injection pump capable of reciprocatingly sliding along an overhang guide portion of the pump case in conjunction with the rotational movement of the cam, Pets and the gap between the plunger barrel in which comprises a covering member which covers over the sliding entire stroke of the tappet.

In the present invention, the tappet has a vent hole for venting the inside of the tappet.

In this invention, it has a receiving part which receives the edge part by the side of the said plunger barrel of the said urging | biasing member.

In the present invention, the tappet has a cam top portion that holds a state where the tappet is located at the top dead center.

As the effects of the present invention, the following effects are obtained.

In the present invention, it is possible to prevent the lubricating oil from being applied to the plunger by the protruding portion of the tappet and to prevent the lubricating oil from being mixed into the fuel. It is possible to suppress the deterioration of exhaust smoke caused by the carbon flower adhesion.

In the present invention, it is possible to prevent the lubricating oil from being applied to the plunger by the scattering preventing member, and to prevent the lubricating oil from being mixed into the fuel. Deterioration of exhaust smoke caused by carbon flower adhesion can be suppressed.

In the present invention, since the outer shape of the tappet is not complicated, the outer periphery of the tappet can be easily polished, and the manufacturing cost can be reduced.

In the present invention, since the inflow preventing member can prevent the lubricating oil from flowing into the vent hole, the lubricating oil that has passed through the vent hole is not applied to the plunger. Thereby, since mixing of the lubricating oil into the fuel can be prevented, it is possible to suppress the deterioration of exhaust smoke due to the blackening of the fuel and the carbon flower adhering to the fuel injection nozzle nozzle due to incomplete combustion.

In the present invention, since the inflow prevention member and the positioning member can be attached at a time, the efficiency of the attachment work is improved.

In the present invention, since the gap between the tappet and the plunger barrel is covered by the covering member, it is possible to prevent the lubricating oil from being applied to the plunger through the gap between the tappet and the plunger barrel. Thereby, since mixing of the lubricating oil into the fuel can be prevented, it is possible to suppress the deterioration of exhaust smoke due to the blackening of the fuel and the carbon flower adhering to the fuel injection nozzle nozzle due to incomplete combustion.

In the present invention, even if the gap between the tappet and the plunger barrel is covered with the covering member, the inside of the tappet can be surely vented.

In the present invention, since it is not necessary to provide a dedicated member for receiving the biasing member, the number of parts can be reduced and the part cost can be reduced.

In the present invention, since the tappet is held at the top dead center, the lubricating oil from the space for accommodating the cam (hereinafter referred to as “cam chamber”) is less likely to be applied to the plunger, Since contamination of the lubricating oil can be prevented, deterioration of exhaust smoke due to carbon blackening of the fuel and adhesion of carbon flower to the fuel injection nozzle nozzle due to incomplete combustion can be suppressed.

1 is a side cross-sectional view showing a state where a roller tappet is located at a top dead center in a fuel injection pump according to a first embodiment of the present invention. FIG. 2 is a front sectional view of FIG. 1. 1 is a side cross-sectional view illustrating a state where a roller tappet is located at a bottom dead center in a fuel injection pump according to a first embodiment of the present invention. FIG. 4 is a front sectional view of FIG. 3. The side view which showed the cam. The top view which showed the inflow prevention member. FIG. 5 is a cross-sectional view taken along the line A-A ′ in FIG. Sectional drawing which showed the inflow prevention member which concerns on a modification. The partial front sectional view which showed the roller tappet. Front sectional drawing which showed the fuel-injection pump provided with the roller tappet which concerns on a modification. The front fragmentary sectional view which showed the roller tappet with which the fuel injection pump which concerns on 2nd Example of this invention is equipped.

Next, a mode for carrying out the invention will be described.

First, a fuel injection pump 1 according to a first embodiment of the present invention will be described with reference to FIGS.

In the following, for the sake of convenience, the direction in which the gravity acts is defined as “downward” and the direction opposite to the direction in which the gravity acts is defined as “upward” based on the posture when the fuel injection pump 1 is attached to the engine. Defines the "vertical direction", defines the "front-rear direction" as the direction perpendicular to the vertical direction, and defines the "left-right direction" as the direction perpendicular to the vertical direction and the front-rear direction. A description will be given using directions.
Further, the arrow T direction shown in FIG. 1 is the upward direction, the arrow D direction is the downward direction, the arrow F direction is the forward direction, and the arrow Re direction is the backward direction. Also, the direction of arrow Ri shown in FIG. 2 is the right direction, and the direction of arrow L is the left direction. The same applies to the subsequent drawings.

As shown in FIGS. 1 to 4, the fuel injection pump 1 according to the first embodiment is a component that constitutes a fuel injection device of an engine, and pumps fuel at a high pressure. The fuel injection pump 1 is a distribution type fuel injection pump that distributes and pumps fuel to each cylinder (not shown) of the engine by a single plunger 10.

The plunger 10 is provided in the plunger barrel 11 so as to be capable of reciprocating in the vertical direction. The plunger barrel 11 is inserted into a hydraulic head 13 provided on the top of the pump case 12. In the hydraulic head 13, a thermo element 14 that is a cold start timer mechanism is provided on the right side of the plunger barrel 11, and an accumulator 37 is provided on the left side of the plunger barrel 11. A pressurizing chamber 15 communicating with a fuel tank (not shown) is formed between the plunger barrel 11 and the upper end portion of the plunger 10.

The lower end portion of the plunger barrel 11 is inserted into a tappet chamber 16 formed in the upper and lower directions on the upper part of the pump case 12. In the tappet chamber 16, the plunger 10 projects downward from the lower end portion of the plunger barrel 11. An upper spring receiver 17 is fixed to the outer periphery of the lower end portion of the plunger barrel 11, and a lower spring receiver 18 is fixed to the lower end portion of the plunger 10. A spring 19 is provided between the upper surface of the lower spring receiver 18 and the lower surface of the upper spring receiver 17 to apply a downward urging force to the plunger 10. A roller tappet 20 is provided at the lower end portion of the plunger 10 so as to be reciprocally slidable in the vertical direction along the overhang guide portion 12 a of the pump case 12.

1 and 2 show the fuel injection pump 1 in a state in which the roller tappet 20 is located at the top dead center. FIGS. 3 and 4 show a state in which the roller tappet 20 is located at the bottom dead center. 1 shows a fuel injection pump 1.

The roller tappet 20 has a cylindrical shape opened upward. A lower spring receiver 18 is fixed in the roller tappet 20, and the roller tappet 20 is urged downward together with the plunger 10 by the spring 19 through the lower spring receiver 18. A roller portion 201 that is in contact with the cam 21 is pivotally supported via a roller shaft 202 at a lower portion of the roller tappet 20. An adjustment shim 206 is provided between the upper surface in the roller tappet 20 and the lower surface of the lower spring receiver 18. The adjustment shim 206 adjusts the gap between the cam 21 and the roller tappet 20 to an appropriate value.

The cam 21 is fixed on the cam shaft 22 and is accommodated in a front portion in a cam chamber 23 formed in the lower portion of the pump case 12. The cam chamber 23 is filled with lubricating oil, and the cam 21 is lubricated with this lubricating oil. The cam shaft 22 is installed in the cam chamber 23 in the front-rear direction, and is pivotally supported by the pump case 12 via a bearing 221.

A front end portion of the cam shaft 22 protrudes forward from the front portion of the pump case 12, and a gear 222 to which power from an engine crank shaft (not shown) is transmitted is fixed to the front protruding portion of the cam shaft 22. Is done. A rear end portion of the cam shaft 22 protrudes rearward from the rear portion of the pump case 12, and a governor sleeve 24 and a governor weight 25, which are components constituting a governor mechanism (not shown), are provided on the rear protruding portion of the cam shaft 22. Is provided.

In the rear part of the cam chamber 23, a bevel gear 223 fixed on the cam shaft 22 is accommodated. From the upper surface of the rear part in the cam chamber 23, a lower end portion of a transmission shaft 26 that is pivotally supported by the pump case 12 and extends in the vertical direction protrudes downward. A bevel gear 261 that meshes with the bevel gear 223 is fixed to the lower end portion of the transmission shaft 26.

The upper end of the transmission shaft 26 is pivotally supported by the shaft support 121 of the pump case 12 and the position in the axial direction (vertical direction) is positioned by the positioning member 28. Above the transmission shaft 26, a rack chamber 27 is formed on the upper surface of the pump case 12. The rack chamber 27 houses a rack (not shown) that is a component constituting the injection amount adjustment mechanism of the fuel injection pump 1. The rack chamber 27 communicates with the cam chamber 23 through the vent holes 30 and 30.

The vent holes 30 and 30 are communicated from the rack chamber 27 to the cam chamber 23 in the pump case 12. The opening end surface (opening end surface on the rack chamber 27 side) of the upper end portion of the vent holes 30 and 30 is covered with an inflow prevention member 31 (see FIGS. 6 and 7).

At the upper end of the transmission shaft 26, a distribution shaft 32 is fixed on the same axis as the transmission shaft 26 via a joint 33. The inside of the distribution shaft 32 and the pressurizing chamber 15 are communicated by an oil passage 131 formed in the hydraulic head 13. In the hydraulic head 13, on the rear side of the distribution shaft 32, a check valve is provided at the end of the injection of the fuel injection pump 1 to prevent the fuel in the injection pipe (not shown) from flowing into the pressurizing chamber 15. A delivery valve 34 is provided via a holder 341.

In the fuel injection pump 1 having such a configuration, when the cam 21 is rotated, the roller tappet 20 is reciprocated in the vertical direction by the rotation of the cam 21 and the lower spring receiver 18 fixed to the roller tappet 20 is provided. Through this, the plunger 10 is also reciprocated. At this time, the lubricating oil that fills the cam chamber 23 by the reciprocating motion of the roller tappet 20 and the lubricating oil that is injected into the outer peripheral surface of the roller tappet 20 pass through the gap between the outer peripheral surface of the roller tappet 20 and the inner peripheral wall of the tappet chamber 16. Move up through.
Then, the reciprocating motion of the plunger 10 alternately performs the fuel suction stroke into the pressurizing chamber 15 and the fuel discharge stroke from the pressurizing chamber 15. That is, in the intake stroke, when the plunger 10 is pushed down by the biasing force of the spring 19 and descends, the fuel from the fuel tank is sucked into the pressurizing chamber 15 and in the discharge stroke, the plunger 10 is pressed by the biasing force of the spring 19. When pushed up and lifted, the fuel sucked into the pressurizing chamber 15 is pressurized and fed to the distribution shaft 32 through the oil passage 131.
Thereafter, the fuel pressure-fed to the distribution shaft 32 is distributed to the delivery valve 34 by the distribution shaft 32 and injected from a fuel injection nozzle (not shown) through the injection pipe.

Next, the cam 21 will be described with reference to FIG.
As shown in FIG. 5, the cam 21 has three cam ridges 212, 212, and 212 at a constant interval around the center 213 of the base circle 211 (at intervals of 120 degrees with respect to the center 213). 212 is provided.

In addition, since the structure of the cam nose portions 212, 212, and 212 is substantially the same, in the following description, one cam nose portion 212 will be mainly described, and the other cam nose portions 212 will be explained only when necessary. To do.

The cam mountain portion 212 has a cam top portion 212A. The cam top portion 212 </ b> A has an arc shape formed with a constant radius r from the center 213 of the base circle portion 211. That is, the cam top portion 212A has a shape that can be held in a state where the roller tappet 20 is located at the top dead center.

Next, the inflow preventing member 31 will be described with reference to FIGS.
As shown in FIGS. 6 and 7, the inflow preventing member 31 includes a substrate 311 and a pair of side plates 312 and 312. The inflow preventing member 31 is fixed to the shaft support 121 of the pump case 12 together with the positioning member 28 by bolts 29 and 29. That is, the inflow preventing member 31 is attached to the shaft support part 121 of the pump case 12 together with the positioning member 28 by the bolts 29 and 29. The long side of the substrate 311 on the transmission shaft 26 side is notched into a shape (substantially arcuate) along the outer peripheral shape of the transmission shaft 26.

The substrate 311 and the pair of side plates 312 and 312 are substantially rectangular plate-shaped members. The long sides of the pair of side plates 312 and 312 are connected to the pair of short sides of the substrate 311.

In this embodiment, a pair of side plates 312 and 312 is formed from a pair of short sides of the substrate 311 so that the metal plate protrudes in parallel to the plate surface of the substrate 311, and then a pair of substrates 311 is formed. By bending the metal plate so that the plate surface of the substrate 311 and the plate surface of the pair of side plates 312 and 312 are substantially perpendicular to each other at the boundary line between the short side portion and the pair of side plates 312 and 312. The inflow preventing member 31 is configured. That is, the inflow preventing member 31 has a pair of side plates 312 on the outside of the vent holes 30 when viewed from the left-right direction (the side opposite to the side where the one vent hole 30 and the other vent hole 30 face each other). -The "substantially gate shape" where 312 is located.

Predetermined gaps D1, D2, D3, and D4 are formed between the inflow preventing member 31 and the pump case 12 so that the air vents 30 and 30 are smoothly vented.

Specifically, a gap D1 is formed between the plate surface of the substrate 311 facing the horizontal surface 123 of the pump case 12 and the opening end surface (opening end surface on the rack chamber 27 side) of the upper end portions of the vent holes 30 and 30. (See FIG. 7), a gap D2, a shaft support 121, and a shaft support between the vertical surface 122 of the pump case 12 and the long side of the substrate 311 facing the vertical surface 122 and the short sides of the pair of side plates 312 and 312. A gap D3 is formed between the short sides of the pair of side plates 312 and 312 facing 121, and a gap D4 is formed between the horizontal surface 123 of the pump case 12 and the long sides of the pair of side plates 312 and 312 facing the horizontal surface 123. It is formed.

The inflow preventing member 31 according to the present embodiment is formed by bending (pressing) a plate-like member, but the inflow preventing member according to the present invention is formed by welding or screwing a plurality of members, for example. A combination or a baffle plate 35 as shown in FIG. 8 may be used.

As shown in FIG. 8, the baffle plate 35 is shaped so that a predetermined gap D5 is formed between the opening end surfaces (opening end surfaces on the rack chamber 27 side) of the upper end portions of the vent holes 30 and 30 (for example, , A shape that bends in a direction away from the opening end face of the vent holes 30. The baffle plate 35 is fixed to the horizontal surface 123 of the pump case 12 in the rack chamber 27 by welding or screwing.

Next, a structure for preventing the lubricant oil from entering the fuel of the roller tappet 20 will be described with reference to FIG.
As shown in FIG. 9, the upper portion of the roller tappet 20 always protrudes upward (from the plunger barrel 11 side) from the upper end portion of the overhang guide portion 12 a of the pump case 12 over the entire sliding stroke 203. That is, the upper end portion of the roller tappet 20 is always positioned above (on the plunger barrel 11 side) the upper end portion T of the overhang guide portion 12a of the pump case 12 shown in FIG. An anti-scattering member 204 is provided on the roller tappet 20.

The anti-scattering member 204 protrudes in the horizontal direction (direction orthogonal to the sliding direction of the roller tappet 20) over the entire circumference of the outer peripheral surface of the roller tappet 20, and prevents the lubricating oil from being applied to the plunger 10. The shape of the scattering prevention member 204 is, for example, “substantially ring shape” when viewed from the sliding direction (vertical direction) of the roller tappet 20.

The shape of the scattering prevention member according to the present invention may be any shape that covers the gap between the outer peripheral surface of the tappet and the inner peripheral wall of the tappet chamber. Preferably, for example, the shape of the scattering prevention member 204 is such that the area surrounded by the outer periphery of the scattering prevention member 204 is larger than the opening area of the tappet chamber 16 and surrounded by the outer periphery of the scattering prevention member 204. A gap between the outer peripheral surface of the roller tappet 20 and the inner peripheral wall of the tappet chamber 16 is located inside (when viewed from above, between the outer peripheral surface of the roller tappet 20 and the inner peripheral wall of the tappet chamber 16 by the anti-scattering member 204). In this case, it is possible to reliably prevent the lubricating oil from being applied to the plunger 10.

With such a configuration, as the roller tappet 20 reciprocates, the lubricating oil from the cam chamber 23 side moves upward through a gap between the outer peripheral surface of the roller tappet 20 and the inner peripheral wall of the tappet chamber 16 ( (Hereinafter referred to as “transition lubricating oil”), the transition lubricating oil cannot pass over the upper end of the roller tappet 20, and splashes of the transition lubricating oil are blocked by the scattering prevention member 204 (FIG. 9).

As described above, the fuel injection pump 1 according to the first embodiment of the present invention includes the pump case 12, the hydraulic head 13 provided on the top of the pump case 12, and the plunger barrel inserted into the hydraulic head 13. 11, a plunger 10 that slides in the plunger barrel 11, an overhang guide portion 12 a provided in a partition wall between a tappet chamber 16 below the plunger barrel 11 and a cam chamber 23 provided below the tappet chamber 16. A roller tappet 20 inserted into the overhang guide portion 12a and connected to the lower end of the plunger 10, and a cam 21 provided in the cam chamber 23 below the roller tappet 20 and in contact with the roller tappet 20. A pressurizing chamber 15 in which fuel is pressurized is provided between the upper end of 10 and the plunger barrel 11, and a roller tappet 20 The fuel injection pump 1 is configured to be reciprocally slidable along the overhang guide portion 12a of the pump case 12 in conjunction with the rotational movement of the cam 21, and the upper end portion of the roller tappet 20 is in the entire sliding stroke. It always projects from the upper end surface of the overhang guide portion 12a toward the plunger barrel 11 side.
With such a configuration, it is possible to prevent the lubricating oil from being applied to the plunger 10 by the protruding portion of the roller tappet 20, and to prevent the lubricating oil from being mixed into the fuel. Therefore, fuel blackening and fuel injection due to incomplete combustion It is possible to suppress the deterioration of exhaust smoke caused by the carbon flower adhering to the nozzle orifice.

And it has the scattering prevention member 204 which protrudes in the direction orthogonal to the sliding direction of the roller tappet 20 and prevents lubricating oil from being applied to the plunger 10.
With such a configuration, the splashing prevention member 204 can prevent the lubricating oil from being applied to the plunger 10 and can prevent the lubricating oil from being mixed into the fuel. Deterioration of exhaust smoke due to carbon flower adhesion to the part can be suppressed.

Further, the scattering prevention member 204 has a separate structure from the roller tappet 20.
With such a configuration, since the outer shape of the roller tappet 20 is not complicated, the outer periphery of the roller tappet 20 can be easily polished, and the manufacturing cost can be reduced.

Further, in the fuel injection pump 1, the cam chamber 23 and the rack chamber 27 are communicated by the vent holes 30, 30, and an inflow preventing member 31 that prevents the lubricating oil from flowing into the vent holes 30, 30 is provided. It is to be prepared.
With such a configuration, the inflow preventing member 31 can prevent the lubricating oil from flowing into the vent holes 30 and 30, so that the lubricating oil that has passed through the vent holes 30 and 30 is not applied to the plunger 10. Thereby, since mixing of the lubricating oil into the fuel can be prevented, it is possible to suppress the deterioration of exhaust smoke due to the blackening of the fuel and the carbon flower adhering to the fuel injection nozzle nozzle due to incomplete combustion.

A transmission shaft 26 that is provided coaxially with the distribution shaft 32 of the fuel injection pump 1 and transmits power to the distribution shaft 32; and a positioning member 28 that positions an axial position of the transmission shaft 26; The inflow preventing member 31 is attached together with the positioning member 28.
With such a configuration, the inflow prevention member 31 and the positioning member 28 can be attached at a time, so that the efficiency of the attachment work is improved.

The cam 21 has a cam top portion 212A that holds the roller tappet 20 at a top dead center.
With such a configuration, since the roller tappet 20 is held at the top dead center, the lubricating oil from the cam chamber 23 side is less likely to be applied to the plunger 10, and the mixing of the lubricating oil into the fuel can be prevented. It is possible to suppress the deterioration of exhaust smoke due to carbon flower adhesion to the fuel injection nozzle nozzle due to incomplete fuel combustion.

Further, the fuel injection pump 1 according to the present embodiment is provided with the anti-scattering member 204 on the upper portion of the roller tappet 20, but as shown in FIG. 10, no anti-scattering member is provided on the upper portion of the roller tappet 20. It is also possible to constitute the fuel injection pump 1.

Next, a fuel injection pump 1 according to a second embodiment of the present invention will be described with reference to FIG. In addition, in FIG. 11, since the member of the same code | symbol as 1st Example is the same structure as 1st Example, detailed description is abbreviate | omitted.

As shown in FIG. 11, the fuel injection pump 1 according to the second embodiment includes a covering member 36.

The covering member 36 covers the gap between the roller tappet 20 and the plunger barrel 11 over the entire sliding stroke of the roller tappet 20. The covering member 36 has a cylindrical shape opened downward. The inner diameter of the covering member 36 is slightly larger than the outer diameter of the roller tappet 20. That is, the roller tappet 20 can slide within the covering member 36. The covering member 36 includes a receiving portion 361 and a covering portion 362.

The receiving portion 361 is a portion that receives the upper end portion (end portion on the plunger barrel 11 side) of the spring 19. The covering portion 362 is a portion that covers the gap between the roller tappet 20 and the plunger barrel 11 over the entire sliding stroke of the roller tappet 20. A vent hole 362A for venting the inside of the roller tappet 20 is formed in the covering portion 362.

The vent hole 362A is located above the upper end of the roller tappet 20 over the entire sliding stroke of the roller tappet 20. That is, the vent hole 362 </ b> A is provided at a position where it is not blocked by the roller tappet 20.

It should be noted that the shape, number and installation position of the vent holes according to the present invention are not limited. That is, the vent holes according to the present invention may be any shape, number, and installation position that can vent the inside of the tappet.

With such a configuration, the transition lubricating oil is blocked by the covering member 36 (covering part 362) and cannot flow into the roller tappet 20, and splashes of the transition lubricating oil are also generated by the covering member 36 (covering part 362). It will be blocked.

As described above, in the fuel injection pump 1 according to the second embodiment of the present invention, the plunger 10 is provided in the plunger barrel 11 so as to be slidable back and forth, and fuel is added between one end of the plunger 10 and the plunger barrel 11. While the pressurizing chamber 15 to be pressed is provided, the other end of the plunger 10 protrudes from the plunger barrel 11 in the direction opposite to the pressurizing chamber 15 and can be interlocked with the roller tappet 20. The fuel injection pump 1 is capable of reciprocatingly sliding in the tappet chamber 16 that accommodates the plunger barrel 11 and the plunger 10 by direct driving by the roller tappet 20. A covering member 36 covering the entire stroke is provided.
With such a configuration, since the gap between the roller tappet 20 and the plunger barrel 11 is covered by the covering member 36, it is possible to prevent the lubricating oil from being applied to the plunger 10 through the gap between the roller tappet 20 and the plunger barrel 11. Thereby, since mixing of the lubricating oil into the fuel can be prevented, it is possible to suppress the deterioration of exhaust smoke due to the blackening of the fuel and the carbon flower adhering to the fuel injection nozzle nozzle due to incomplete combustion.

The covering member 36 has a vent hole 362A for venting the inside of the roller tappet 20.
With such a configuration, even if the gap between the roller tappet 20 and the plunger barrel 11 is covered by the covering member 36, the air inside the roller tappet 20 can be reliably ensured.

Further, a spring 19 is provided as an urging member for urging the plunger 10 in the direction of the cam 21, and the covering member 36 has a receiving portion 361 that receives an end of the spring 19 on the plunger barrel 11 side.
With such a configuration, there is no need to provide a dedicated member for receiving the spring 19, so that the number of parts can be reduced and the part cost can be reduced.

DESCRIPTION OF SYMBOLS 1 Fuel injection pump 11 Plunger barrel 10 Plunger 15 Pressurization chamber 16 Tappet chamber 19 Spring (biasing member)
20 Roller tappet (tappet)
21 Cam (Cam member)
23 Cam chamber 26 Transmission shaft 27 Rack chamber 28 Positioning member 30 Vent hole 31 Inflow preventing member 32 Distribution shaft 36 Cover member 204 Splash preventing member 212A Cam top portion 361 Receiving portion 362A Vent hole

Claims (9)

A pump case,
A hydraulic head provided at the top of the pump case;
A plunger barrel inserted into the hydraulic head;
A plunger sliding in the plunger barrel;
An overhang guide portion provided in a partition wall between a tappet chamber below the plunger barrel and a cam chamber provided below the tappet chamber;
A tappet inserted into the overhang guide and connected to the lower end of the plunger;
A cam provided in the cam chamber below the tappet and abutting the tappet,
A pressurizing chamber is provided between the upper end of the plunger and the plunger barrel to pressurize the fuel;
The tappet is a fuel injection pump that is reciprocally slidable along the overhang guide portion of the pump case in conjunction with the rotational movement of the cam,
The upper end portion of the tappet is a fuel injection pump that always protrudes from the upper end surface of the overhang guide portion toward the plunger barrel over the entire sliding stroke. The fuel injection pump according to claim 1, further comprising a scattering prevention member that protrudes in a direction orthogonal to a sliding direction of the tappet and prevents lubricant from being applied to the plunger. The fuel injection pump according to claim 2, wherein the scattering prevention member has a separate structure from the tappet. The pump case is provided with a cam chamber that houses the cam member, and a rack chamber that includes a rack is provided on the upper surface of the pump case, and the cam chamber and the rack chamber communicate with each other through a vent hole. The fuel injection pump according to claim 3, further comprising an inflow prevention member for preventing lubricating oil from flowing into the vent hole. The fuel injection pump includes a delivery valve that prevents the fuel from flowing into the pressurizing chamber, a distribution shaft that distributes the pumped fuel to the delivery valve, and a coaxial shaft that is provided on the distribution shaft. 5. A transmission shaft for transmitting power and a positioning member for positioning an axial position of the transmission shaft are provided, and the inflow prevention member is attached to the pump case together with the positioning member. The fuel injection pump described in 1. A pump case,
A hydraulic head provided at the top of the pump case;
A plunger barrel inserted into the hydraulic head;
A plunger sliding in the plunger barrel;
An overhang guide portion provided in a partition wall between a tappet chamber below the plunger barrel and a cam chamber provided below the tappet chamber;
A tappet inserted into the overhang guide and connected to the lower end of the plunger;
A cam provided in the cam chamber below the tappet and abutting the tappet,
A pressurizing chamber is provided between the upper end of the plunger and the plunger barrel to pressurize the fuel;
The tappet is a fuel injection pump that is reciprocally slidable along the overhang guide portion of the pump case in conjunction with the rotational movement of the cam,
A fuel injection pump comprising a covering member that covers a gap between the tappet and the plunger barrel over the entire sliding stroke of the tappet. The fuel injection pump according to claim 6, wherein the covering member has a vent hole for venting the inside of the tappet. The fuel injection pump according to claim 7, wherein the covering member has a receiving portion for receiving an end portion of the biasing member on the plunger barrel side. The fuel injection pump according to any one of claims 1 to 8, wherein the cam member has a cam top portion that holds a state in which the tappet is located at a top dead center.

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