CN216077383U

CN216077383U - Plunger type oil injection pump of medium-speed engine

Info

Publication number: CN216077383U
Application number: CN202122418406.XU
Authority: CN
Inventors: 周勇; 杨欢; 陈廷博; 龚元华; 张鹏; 黄威; 杨清; 徐伟; 田梦江
Original assignee: Chongqing Hongjiang Machinery Co Ltd
Current assignee: Chongqing Hongjiang Machinery Co Ltd
Priority date: 2021-10-08
Filing date: 2021-10-08
Publication date: 2022-03-18
Anticipated expiration: 2031-10-08

Abstract

The utility model discloses a plunger type oil injection pump of a medium-speed engine, which comprises a pressing plate, an isobaric oil outlet valve component, a plunger matching part, an oil injection pump body, a plunger sleeve positioning screw, a check ring and a lubricating oil fine filter valve. The clamp plate design has the conical surface, isobaric delivery valve subassembly includes delivery valve upper seat, delivery valve, relief pressure valve and delivery valve lower seat, and delivery valve upper seat design has the sphere, and delivery valve lower seat design has the orifice. The plunger matching part comprises a plunger and a plunger sleeve, an oil control groove is formed in the head position of the plunger, an annular groove and an oil hole for communicating the annular groove with a low-pressure fuel oil cavity of the fuel injection pump are designed in the inner wall of a middle hole of the plunger sleeve, and a positioning groove is designed in the outer wall of the plunger sleeve. The bottom of the oil injection pump body is provided with a rectangular groove. The plunger sleeve positioning screw is designed with a cylindrical boss. The medium-speed plunger type oil injection pump provided by the utility model can adapt to the national second-stage emission standard of a diesel engine, and effectively improves the reliability and stability of the plunger type oil injection pump and prolongs the service life of the plunger type oil injection pump.

Description

Plunger type oil injection pump of medium-speed engine

Technical Field

The utility model relates to the technical field of marine diesel engines, in particular to a plunger type oil injection pump.

Background

In recent years, as emission regulations become more stringent, diesel engines are required to achieve efficient combustion and ultra-low emissions. The fuel injection system, as the "heart" of the diesel engine, has a great influence on the performance of the diesel engine. Accordingly, the demand for diesel fuel injection systems has become higher and higher. The fuel injection pump is the most important part of the fuel injection system of the diesel engine, and the working condition of the fuel injection system is directly influenced by the working condition of the fuel injection pump. The plunger type fuel injection pump is the fuel injection pump which lasts for the longest time and is widely applied, and has high reliability. The existing plunger type fuel injection pumps suitable for four-stroke, exhaust gas turbocharging, intercooling and irreversible diesel engines are difficult to adapt to the emission requirements of the diesel engines, and a plurality of places for further optimization and improvement exist in the aspects of structure, performance and the like. Therefore, further research and development is still needed in the art of fuel injection pumps to achieve higher fuel economy and better emission levels in diesel engines.

Disclosure of Invention

In order to adapt to increasingly severe emission requirements of diesel engines and overcome the defects in the prior art, the utility model provides a medium-speed plunger type oil injection pump which can adapt to the national second-stage emission standard of the diesel engine, avoid secondary injection of the diesel engine, reduce the leakage of fuel oil from the clearance of a plunger matching part and improve the reliability.

The technical scheme of the utility model is as follows:

a plunger type oil injection pump of a medium-speed engine comprises a pressing plate, an isobaric oil outlet valve component, a plunger matching part and an oil injection pump body. The plunger matching part comprises a plunger and a plunger sleeve, the plunger sleeve is arranged in the inner cavity of the oil injection pump body, and the step surface of the plunger sleeve is tightly attached to the step surface of the inner cavity of the oil injection pump body. The isobaric oil outlet valve assembly comprises an oil outlet valve upper seat, an oil outlet valve, a pressure reducing valve and an oil outlet valve lower seat, and the bottom surface of the oil outlet valve lower seat is tightly attached to the top surface of the plunger sleeve. The pressing plate is tightly attached to the oil outlet valve upper seat and is connected with the oil injection pump body through screws. The pressure plate is provided with a conical surface, the oil outlet valve upper seat is provided with a spherical surface, a screw is screwed, and the spherical surface is pressed through the conical surface, so that the isobaric oil outlet valve component and the plunger matching part are pressed in an inner cavity of the oil injection pump body.

Furthermore, the lower oil outlet valve seat is provided with a throttling hole formed by communicating a large hole with a small hole, and after the isobaric oil outlet valve assembly is assembled, the throttling hole and a cavity of the upper oil outlet valve seat, which is used for accommodating the pressure reducing valve, are positioned on the same central axis.

Furthermore, a first group of oil control grooves consisting of a first spiral groove and a second group of oil control grooves consisting of a third spiral groove and a fourth spiral groove are designed at the head of the plunger. The first group of oil control grooves and the second group of oil control grooves are symmetrically distributed along the central axis. The first spiral groove is identical to the third spiral groove, and the second spiral groove is identical to the fourth spiral groove. The first spiral groove comprises 1-N sections of spiral lines, and the lead of the Nth section of spiral line is S_N(N is more than or equal to 1 and less than or equal to 5). What is needed isThe second spiral groove has 1 section of spiral line with the lead of S₆。

Further, plunger bushing mesopore inner wall design has annular and oilhole, the oilhole is the through-hole, the intercommunication annular and injection pump low pressure fuel oil chamber. The plunger sleeve is provided with a first oil inlet and return hole and a second oil inlet and return hole, a positioning groove is arranged at one end, close to the outside, of the first oil inlet and return hole or the second oil inlet and return hole, and the positioning groove is an arc-shaped groove sunken towards the hole in the plunger sleeve.

And the plunger sleeve positioning screw is arranged on the oil injection pump body, and the plunger sleeve positioning screw and the first oil inlet and the second oil inlet of the plunger sleeve are positioned on the same central axis. The plunger sleeve positioning screw is designed with a cylindrical boss, and the boss is subjected to special heat treatment. A small part of the boss extends into the positioning groove, and a sufficient distance is reserved between the boss and the oil inlet and return hole outlet, so that oil can flow through the boss and the oil inlet and return hole outlet cannot be blocked.

The oil injection pump further comprises a check ring, a rectangular groove is designed at the bottom of the oil injection pump body, and the groove bottom of the rectangular groove is higher than the installation position of the check ring.

And the lubricating oil fine filtering valve is arranged at a lubricating oil inlet of the oil injection pump body and is communicated with a lubricating oil channel on the plunger sleeve. The lubricating oil fine filter valve comprises a nut, a gasket, a filter screen, a filter element, a spring, a steel ball and a valve body. The valve body is provided with a first cavity and a second cavity from an inlet to an outlet, the first cavity is communicated with the second cavity through an oil hole, and the first cavity is provided with an internal thread for connecting an oil inlet pipe. And one end of the second cavity, which is close to the first cavity, is designed with a sealing conical surface which is matched with the steel ball for sealing. The second cavity is designed with internal threads. The spring, the filter element, the filter screen, the gasket and the nut are sequentially installed at one end, close to the steel ball, of the second cavity. An outer hexagon is designed at one end, close to the first cavity, of the valve body. And an external thread is designed at one end of the valve body close to the second cavity.

Further, the diameter of the oil outlet valve is phi 14-phi 15mm, and the lift range of the oil outlet valve is 1.0-1.5 mm; the diameter of the plunger is phi 22-phi 25mm, and the stroke of the plunger is 22-26 mm. The starting pressure of the lubricating oil fine filtering valve is 0.1-0.3 MPa.

The utility model has the following beneficial effects:

1. the mode that adopts conical surface and sphere contact between clamp plate and the isobaric delivery valve subassembly can avoid because of the processing of contact surface is not good, and there is the slope in the good back clamp plate of injection pump assembly, and each connecting screw atress is uneven in the working process takes place the fracture.

2. The lower seat of the oil outlet valve is provided with a throttling hole, so that secondary injection of the diesel engine can be avoided.

3. Two groups of oil control grooves which are symmetrically distributed along the central axis at the head part of the plunger piston can enable the oil injection pump to adapt to the national second-stage emission standard of the diesel engine.

4. The plunger sleeve has annular groove and oil hole communicating the annular groove and the low pressure fuel oil cavity of the fuel injection pump in the inner wall of the central hole, and can reduce the leakage of fuel oil from the clearance of the plunger matching part.

5. The plunger bushing is first advance oil gallery or the second advances the oil gallery and is close to outside one end design and have the constant head tank, with the cooperation of plunger bushing set screw, can play the positioning action, prevents that the plunger bushing from taking place to rotate in the working process. Meanwhile, the positioning groove of the plunger sleeve is designed into an arc shape sunken towards the middle hole, so that cavitation erosion damage can be avoided. Besides the positioning function, the installation position of the plunger sleeve positioning screw is over against the oil inlet and return hole of the plunger sleeve, so that the phenomenon that the oil injection pump body is subjected to cavitation erosion against the oil inlet and return hole is avoided, and the oil injection pump body is protected.

6. The design of oil spout pump body bottom has the rectangular channel, the assembly of the retaining ring of being convenient for.

7. The lubricating oil fine filter valve is integrated on the oil injection pump, and is designed to be detachable, so that the oil injection pump is convenient to replace and maintain. Meanwhile, lubricating oil can be finely filtered before entering the oil injection pump, and foreign matters and impurities are prevented from entering a gap of the plunger and barrel assembly to cause seizure. The lubricating oil fine filtering valve is a one-way valve, so that lubricating oil polluted by fuel oil can be prevented from flowing back to the lubricating oil tank. The diesel engine fuel injection pump has the advantages that the diesel engine fuel injection pump is adaptive to the emission requirement of a diesel engine, and the reliability, the stability and the service life of the fuel injection pump are obviously enhanced.

Drawings

The utility model is further described below with reference to the accompanying drawings and embodiments:

FIG. 1 is a profile view of an injection pump assembly;

FIG. 2 is a schematic cross-sectional view of an injection pump assembly;

FIG. 3 is a cross-sectional view of an injection pump assembly;

FIG. 4 is a cross-sectional view of the platen;

FIG. 5 is a cross-sectional view of an isobaric oil outlet valve assembly;

FIG. 6 is a cross-sectional view of the plunger and barrel assembly;

FIG. 7 is a plunger sleeve profile view;

FIG. 8 is an expanded view of the plunger head;

fig. 9 is a cross-sectional view of the oil fine filter valve.

In the figure: 1-pressing plate, 11-pressing plate conical surface, 2-isobaric oil outlet valve component, 21-oil outlet valve upper seat, 211-oil outlet valve upper seat spherical surface, 22-oil outlet valve, 23-pressure reducing valve, 24-oil outlet valve lower seat, 241-orifice, 241 a-large hole, 241 b-small hole, 3-plunger coupling component, 31-plunger, 311-first group oil control groove, 311 a-first spiral groove, 311 b-second spiral groove, 312-second group oil control groove, 312 a-third spiral groove, 312 b-fourth spiral groove, 32 plunger sleeve, 321-ring groove, 322-oil hole, 323-first oil inlet and return hole, 324-second oil inlet and return hole, 325-positioning groove, 4-oil injection pump body, 41-rectangular groove, 5-plunger sleeve positioning screw, 51 boss, 6-retainer ring, 7-lubricating oil fine filter valve, 71-nut, 72-gasket, 73-filter screen, 74-filter element, 75-spring, 76-steel ball, 77-valve body, 771-first cavity, 772-second cavity and A-low pressure fuel cavity of fuel injection pump.

Detailed Description

The structure and operation of the present invention will be described in further detail with reference to the accompanying drawings and examples.

It should be noted that the embodiments and features of the embodiments may be combined with each other without conflict. Examples of which are illustrated in the accompanying drawings, wherein like reference numerals refer to the same or similar elements or elements having the same or similar function throughout.

In the description of the present invention, it is to be understood that the terms "upper", "lower", "left", "right", "bottom", "inner", "outer", "axial", "radial", "circumferential", and the like, indicate orientations and positional relationships based on those shown in the drawings, and are used merely for convenience in describing the present invention and for simplicity in description, and do not indicate or imply that the referenced devices or elements must have a particular orientation, be constructed and operated in a particular orientation, and thus, are not to be construed as limiting the present invention.

As shown in fig. 1 to 6, the medium-speed plunger type fuel injection pump in the embodiment is composed of a pressure plate (1), an isobaric fuel outlet valve assembly (2), a plunger and barrel assembly (3), a fuel injection pump body (4) and the like. The plunger and barrel assembly (3) comprises a plunger (31) and a plunger sleeve (32), the plunger sleeve (32) is installed in the inner cavity of the oil injection pump body (4), and the step surface of the plunger sleeve (32) is tightly attached to the step surface of the inner cavity of the oil injection pump body (4). The isobaric oil outlet valve component (2) comprises an oil outlet valve upper seat (21), an oil outlet valve (22), a pressure reducing valve (23) and an oil outlet valve lower seat (24), and the bottom surface of the oil outlet valve lower seat (24) is tightly attached to the top surface of the plunger sleeve (32). The pressure plate (1) is connected with the oil injection pump body (4) through screws. The pressure plate (1) is provided with a conical surface (11), the oil outlet valve upper seat (21) is provided with a spherical surface (211), screws are screwed, and the spherical surface (211) is pressed through the conical surface (11), so that the isobaric oil outlet valve component (2) and the plunger matching part (3) are pressed in an inner cavity of the oil injection pump body (4). By adopting the mode of conical surface and spherical surface contact, the phenomenon that the pressure plate (1) is inclined after the fuel injection pump assembly is assembled due to poor processing of the contact surface and the fracture of each connecting screw due to uneven stress in the working process can be avoided.

In this embodiment, as shown in fig. 5, the outlet valve lower seat (24) is designed with an orifice (241) composed of a large hole (241 a) and a small hole (241 b), and the orifice (241) is a through hole. After the isobaric oil outlet valve assembly (2) is assembled, the throttle hole (241) and a cavity of the oil outlet valve upper seat (21) for accommodating the pressure reducing valve (23) are located on the same central axis. Through the design, the fuel flowing back from the pressure reducing valve (23) can be prevented from flowing into the cavity of the plunger sleeve (32) too fast, so that the fuel on the side, close to the pressure reducing valve (23), of a high-pressure oil pipe is prevented from being decompressed too fast, and secondary injection of a diesel engine is avoided.

In this embodiment, as shown in fig. 8, the head portion of the plunger (31) is designed with a first set of oil control grooves (311) composed of a first spiral groove (311 a) and a second spiral groove (311 b), and a second set of oil control grooves (312) composed of a third spiral groove (312 a) and a fourth spiral groove (312 b). The first spiral groove (311 a) is identical to the third spiral groove (312 a), and the second spiral groove (311 b) is identical to the fourth spiral groove (312 b). The first group of oil control grooves (311) and the second group of oil control grooves (312) are symmetrically distributed along the central axis. The first spiral groove (311 a) comprises 1-5 sections of spiral lines, and the lead of the Nth section of spiral line is S_N(N is more than or equal to 1 and less than or equal to 5). The second spiral groove (311 b) has 1 section of spiral line with the lead of S₆. The structure of accuse oil groove in this embodiment can make the diesel engine change the plunger pretravel at specific operating mode to reduce the oil supply advance angle of diesel engine, and then adapt to the emission requirement of diesel engine. For example: first helicla flute (311 a) of certain model injection pump has included 2 sections helices, and the helical lead of 1 st section helix is 50 ~ 60mm, and the helical lead of 2 nd section helix is 80 ~ 90mm, second helicla flute (311 b) has 1 section helix, and the helical lead of helix is 40 ~ 50mm, can make injection pump adapt to the emission standard of diesel engine national second stage.

In this embodiment, as shown in fig. 3, 6, and 7, an annular groove (321) and an oil hole (322) are designed on an inner wall of a central hole of the plunger sleeve (32), the oil hole (322) is a through hole and communicates the annular groove (321) with the low-pressure fuel chamber a of the injection pump, high-pressure fuel leaks from a clearance between the plunger and barrel to the annular groove (321), so that oil pressure is greatly reduced, and the high-pressure fuel returns to the low-pressure fuel chamber a of the injection pump through the oil hole (322), thereby reducing leakage of fuel from the clearance between the plunger and barrel. The plunger sleeve (32) is provided with a first oil inlet and return hole (323) and a second oil inlet and return hole (324), and a positioning groove (325) is arranged at one end, close to the outside, of the first oil inlet and return hole (323) or the second oil inlet and return hole (324). The positioning groove (325) is an arc-shaped groove which is sunken towards the middle hole of the plunger sleeve (32), so that cavitation damage can be avoided.

In this embodiment, as shown in fig. 2, the plunger sleeve positioning device further includes a plunger sleeve positioning screw (5), the plunger sleeve positioning screw (5) is designed with a cylindrical boss (51), and the boss (51) is subjected to special heat treatment. The plunger sleeve positioning screw (5) is arranged on the oil injection pump body (4), and the plunger sleeve positioning screw (5) and a first oil inlet and return hole (323) and a second oil inlet and return hole (324) of the plunger sleeve (32) are located on the same central axis. A small part of the boss (51) extends into the positioning groove (325), and a sufficient distance is reserved between the boss (51) and the oil inlet and return hole outlet, so that the oil inlet and return hole outlet cannot be blocked. The plunger sleeve positioning screw (5) is matched with the positioning groove (325) to play a positioning role, so that the plunger sleeve (32) is prevented from rotating in the working process. In addition, the installation position of the plunger sleeve positioning screw (5) is over against the oil inlet and return hole of the plunger sleeve (32), so that the oil injection pump body (4) is prevented from being directly corroded by cavitation against the oil inlet and return hole, and the oil injection pump body (4) is protected.

In this embodiment, as shown in fig. 2 and 3, the fuel injection pump further includes a retainer ring (6), a rectangular groove (41) is designed at the bottom of the fuel injection pump body (4), and the bottom of the rectangular groove (41) is higher than the installation position of the retainer ring (6), so that the retainer ring (6) can be conveniently installed and removed.

In this embodiment, as shown in fig. 9, the fuel injection pump further includes a fuel fine filtering valve (7) installed at a fuel inlet of the fuel injection pump body (4) and communicated with the fuel passage on the plunger sleeve. The lubricating oil fine filtering valve (7) comprises a nut (71), a gasket (72), a filter screen (73), a filter element (74), a spring (75), a steel ball (76) and a valve body (77). The valve body (77) is provided with a first cavity (771) and a second cavity (772) from an inlet to an outlet, the first cavity (771) and the second cavity (772) are communicated through oil holes, and the first cavity (771) is designed with internal threads and used for being connected with an oil inlet pipe. One end of the second cavity (772) close to the first cavity (771) is designed with a sealing conical surface which is matched with the steel ball (76) for sealing. The second cavity (772) is designed with an internal thread. One end of the second cavity (772), which is close to the steel ball (76), is sequentially provided with the spring (75), the filter element (74), the filter screen (73), the gasket (72) and the nut (71). One end of the valve body (77) close to the first cavity (771) is designed with an external hexagon. One end of the valve body (77) close to the second cavity (772) is designed with an external thread. The starting pressure of the lubricating oil fine filtering valve (7) is 0.1-0.3 MPa. The lubricating oil fine filtering valve (7) is integrated on the oil injection pump, lubricating oil can be filtered more finely once before entering the oil injection pump, and foreign matter and impurities are prevented from entering a gap of the plunger and barrel assembly to cause seizure. The lubricating oil fine filtering valve (7) is detachable on the oil injection pump, and is favorable for replacement and maintenance. In addition, the lubricating oil fine filtering valve (7) is a one-way valve, so that lubricating oil polluted by fuel oil can be prevented from flowing back to a lubricating oil tank.

In the embodiment, the diameter of the oil outlet valve (22) is phi 14-phi 15mm, and the lift range of the oil outlet valve (22) is 1.0-1.5 mm; the diameter of the plunger (31) is phi 22-phi 25mm, the stroke of the plunger (31) is 22-26 mm, and the maximum geometric oil supply is 6000mm³The circulation can meet the requirements of the medium-speed diesel engine on performance indexes such as oil supply quantity and the like. For example: the maximum rotating speed of a certain type of diesel engine is 650r/min, and the maximum single-cylinder power is 350 KW.

Finally, the above embodiments are only for illustrating the technical solutions of the present invention and not for limiting, although the present invention has been described in detail with reference to the preferred embodiments, it should be understood by those skilled in the art that modifications or equivalent substitutions may be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, and all of them should be covered in the claims of the present invention.

Claims

1. A middle-speed engine plunger type oil injection pump comprises a pressure plate (1), an isobaric oil outlet valve component (2), a plunger matching part (3) and an oil injection pump body (4); the plunger matching part (3) comprises a plunger (31) and a plunger sleeve (32), the plunger sleeve (32) is installed in the inner cavity of the oil injection pump body (4), and the step surface of the plunger sleeve (32) is tightly attached to the step surface of the inner cavity of the oil injection pump body (4);

the isobaric oil outlet valve component (2) comprises an oil outlet valve upper seat (21), an oil outlet valve (22), a pressure reducing valve (23) and an oil outlet valve lower seat (24), and the bottom surface of the oil outlet valve lower seat (24) is tightly attached to the top surface of the plunger sleeve (32); the pressure plate (1) is tightly attached to the oil outlet valve upper seat (21) and is connected with the pressure plate (1) and the oil injection pump body (4) through screws; the method is characterized in that: the pressure plate (1) is provided with a conical surface (11), the oil outlet valve upper seat (21) is provided with a spherical surface (211), screws are screwed, and the spherical surface (211) is pressed through the conical surface (11), so that the isobaric oil outlet valve component (2) and the plunger matching part (3) are pressed in an inner cavity of the oil injection pump body (4).

2. The medium speed plunger-type fuel injection pump according to claim 1, characterized in that: the oil outlet valve lower seat (24) is provided with an orifice (241) formed by communicating a large hole (241 a) with a small hole (241 b), and the orifice (241) and a cavity of the oil outlet valve upper seat (21) for accommodating the pressure reducing valve (23) are positioned on the same central axis.

3. The medium speed plunger-type fuel injection pump according to claim 1, characterized in that: the head position of the plunger (31) is provided with a first group of oil control grooves (311) consisting of a first spiral groove (311 a) and a second spiral groove (311 b), anA second set of oil control grooves (312) consisting of a third helical groove (312 a) and a fourth helical groove (312 b); the first group of oil control grooves (311) and the second group of oil control grooves (312) are symmetrically distributed along a central axis, the first spiral groove (311 a) is completely the same as the third spiral groove (312 a), and the second spiral groove (311 b) is completely the same as the fourth spiral groove (312 b); the first spiral groove (311 a) comprises 1-N sections of spiral lines, and the lead of the Nth section of spiral line is S_N，N is more than or equal to 1 and less than or equal to 5, the second spiral groove (311 b) is provided with 1 section of spiral line, and the lead of the spiral line is S₆。

4. The medium speed plunger-type fuel injection pump according to claim 1, characterized in that: the plunger sleeve (32) is provided with a first oil inlet and return hole (323) and a second oil inlet and return hole (324), one end, close to the outside, of the first oil inlet and return hole (323) or the second oil inlet and return hole (324) is provided with a positioning groove (325), and the positioning groove (325) is an arc-shaped groove which is sunken towards the middle hole of the plunger sleeve (32).

5. The medium speed plunger-type fuel injection pump according to claim 4, characterized in that: the fuel injection pump further comprises a plunger sleeve positioning screw (5) which is arranged on the fuel injection pump body (4), and the plunger sleeve positioning screw (5) and a first oil inlet and return hole (323) and a second oil inlet and return hole (324) of the plunger sleeve (32) are positioned on the same central axis; the plunger sleeve positioning screw (5) is provided with a cylindrical boss (51), the boss (51) is subjected to heat treatment, a small part of the boss (51) extends into the positioning groove (325), and a distance for allowing oil to flow is reserved between the boss (51) and an outlet of the oil inlet and return hole.

6. The medium speed plunger-type fuel injection pump according to claim 1, characterized in that: plunger bushing (32) mesopore inner wall design has annular (321) and oilhole (322), oilhole (322) are the through-hole, intercommunication annular (321) and injection pump low pressure fuel oil chamber A.

7. The medium speed plunger-type fuel injection pump according to claim 1, characterized in that: the oil injection pump further comprises a check ring (6), a rectangular groove (41) is designed at the bottom of the oil injection pump body (4), and the groove bottom of the rectangular groove (41) is higher than the installation position of the check ring (6).

8. The medium speed plunger-type fuel injection pump according to claim 1, characterized in that: the lubricating oil fine filtering valve (7) is arranged at a lubricating oil inlet of the oil injection pump body (4) and is communicated with a lubricating oil channel on the plunger sleeve; the lubricating oil fine filtering valve (7) comprises a nut (71), a gasket (72), a filter screen (73), a filter element (74), a spring (75), a steel ball (76) and a valve body (77); the valve body (77) is provided with a first cavity (771) and a second cavity (772) from an inlet to an outlet, and the first cavity (771) is communicated with the second cavity (772) through an oil hole; the first cavity (771) is designed with internal threads and is used for connecting an oil inlet pipe; one end of the second cavity (772) close to the first cavity (771) is designed with a sealing conical surface which is matched with the steel ball (76) for sealing; one end of the second cavity (772) close to the steel ball (76) is sequentially provided with the spring (75), the filter element (74), the filter screen (73), the gasket (72) and the nut (71); the second cavity (772) is designed with internal threads; and one end of the valve body (77) close to the second cavity (772) is designed with an external thread and is in threaded connection with the oil injection pump body (4).

9. The medium speed plunger-type fuel injection pump according to claim 8, characterized in that: the starting pressure of the lubricating oil fine filtering valve (7) is 0.1-0.3 MPa.

10. The medium speed plunger-type fuel injection pump according to claim 1, characterized in that: the diameter of the oil outlet valve (22) is phi 14-phi 15mm, and the lift range of the oil outlet valve (22) is 1.0-1.5 mm; the diameter of the plunger (31) is phi 22-phi 25mm, and the stroke of the plunger (31) is 22-26 mm.