CN113464337A

CN113464337A - Common rail injector of marine diesel engine

Info

Publication number: CN113464337A
Application number: CN202110670048.3A
Authority: CN
Inventors: 普东方; 杨丽; 文李明
Original assignee: China Shipbuilding Power Engineering Institute Co Ltd
Current assignee: China Shipbuilding Power Engineering Institute Co Ltd
Priority date: 2021-06-16
Filing date: 2021-06-16
Publication date: 2021-10-01
Anticipated expiration: 2041-06-16
Also published as: CN113464337B

Abstract

The invention discloses a common rail oil injector of a marine diesel engine, which comprises a needle valve coupling part, wherein a first channel communicated with the needle valve coupling part and a first inner cavity for accommodating the needle valve are arranged in the needle valve coupling part; the oil injector body is internally provided with a second channel, a third channel, a cooling channel and a second inner cavity for accommodating the control valve matching part and the driving mechanism, the second channel, the first channel and part of the first inner cavity are communicated to form an oil inlet channel, the control valve matching part is provided with a fourth channel capable of communicating the second channel and the second inner cavity, and the third channel can be sequentially communicated with the second inner cavity and the first inner cavity to form an oil return channel; the mounting cap is fixedly arranged at the top end of the second inner cavity, and the mounting cap, the first inner cavity and the second inner cavity can enclose a mounting cavity for sequentially arranging the needle valve, the control valve matching part and the driving mechanism from bottom to top; and the locking nut is sleeved on the outer surfaces of the needle valve matching part and the oil injector body so as to connect the needle valve matching part and the oil injector body into a whole.

Description

Common rail injector of marine diesel engine

Technical Field

The invention relates to the technical field of diesel engine electric control fuel injection, in particular to a common rail fuel injector of a marine diesel engine.

Background

The diesel engine is widely applied to various fields with the advantages of high thermal efficiency, good economy, high reliability, wide power range and the like, and plays an important role in the development process of the modern society. The development of diesel engines has been perfected since the new century, and diesel engines will remain dominant in the marine power sector in the foreseeable future. However, as the emission regulations of all countries in the world are more and more strict, the diesel engine is more and more the subject to be restricted by the emission regulations because of the greater adverse effect on the environment, and therefore, how to improve the working quality of the diesel engine becomes more and more urgent.

The fuel oil system is used as a core system of the diesel engine, and the quality of the performance of the fuel oil system has great influence on the combustion performance, the emission performance and the like of the diesel engine, so that the optimization of the working performance of the fuel oil system is particularly important for improving the working quality of the diesel engine. The high-pressure common rail system has the characteristics of high injection pressure, regular oil injection, timing oil injection, circulating oil injection quantity and the like, and the technical characteristics of the high-pressure common rail make the high-pressure common rail become the technical means which has the most potential for solving the problem of the emission performance of the diesel engine and optimizing the working performance of the diesel engine at present. For a marine diesel engine, a high power requirement puts high requirements on the performance of a fuel system, so that technical problems of poor control precision of small oil quantity, poor stability of large flow, large electromagnetic force of a required driving mechanism and the like in the design of a common rail fuel injector of the marine high-power diesel engine are urgently needed to be solved.

Disclosure of Invention

The invention aims to provide a common rail oil sprayer of a marine diesel engine, which is used for solving the problems of large oil injection quantity, poor sealing of a control valve and large electromagnetic force required to drive the valve of the marine high-power diesel engine common rail oil sprayer in the prior art.

The above object of the present invention can be achieved by the following technical solutions:

the invention provides a common rail injector of a marine diesel engine, which comprises: the needle valve coupling piece is internally provided with a first channel communicated with a first inner cavity for accommodating a needle valve, the bottom end of the needle valve coupling piece is provided with a pressure chamber, and the surrounding wall of the pressure chamber is provided with a plurality of spray holes; the oil injector body is internally provided with a second channel, a third channel, a cooling channel and a second inner cavity for accommodating a control valve matching part and a driving mechanism, the second channel, the first channel and part of the first inner cavity are communicated to form an oil inlet channel, the control valve matching part is provided with a fourth channel capable of communicating the second channel and the second inner cavity, and the third channel can be sequentially communicated with the second inner cavity and the first inner cavity to form an oil return channel; the mounting cap is fixedly arranged at the top end of the second inner cavity, and the mounting cap, the first inner cavity and the second inner cavity can enclose a mounting cavity for the needle valve, the control valve matching part and the driving mechanism to be sequentially arranged from bottom to top; the locking nut is sleeved on the outer surfaces of the needle valve matching part and the oil injector body so as to connect the needle valve matching part and the oil injector body into a whole; the actuating mechanism drive control valve matching parts drive under the state of needle valve upward movement, part high pressure fuel can be followed oil feed passageway flows through follow behind the fourth passageway oil return passage flows out, another part high pressure fuel can be followed oil feed passageway flows through the part enter behind the first inner chamber the pressure chamber is followed a plurality of orifice spouts.

Preferably, wherein, the first passageway with the junction of first inner chamber is provided with flourishing oil groove the below of flourishing oil groove, first inner chamber with be formed with the intercommunication between the needle valve the oil feed clearance of pressure chamber, just the bottom of needle valve can support tightly the top of pressure chamber is in order to cut off the oil feed clearance.

Preferably, wherein, still establish including the cover the cooling jacket in the bottom of needle valve idol piece, the cooling jacket with enclose between the bottom of needle valve idol piece and establish and be formed with the cooling chamber, just the pressure chamber bulge downwards in the cooling jacket is in order to pass through high-pressure fuel a plurality of orifice blowout.

Preferably, the control valve matching part comprises: an upper spring; the upper spring seat comprises a first body with a first insertion cavity at the bottom and a central rod arranged at the top end of the first body, the top end of the central rod is fixedly connected with the driving mechanism, a shoulder seat part for mounting the upper spring is formed at the joint of the central rod and the first body, the upper spring can be sleeved on the central rod, and two ends of the upper spring are respectively abutted between the shoulder seat part and the driving mechanism; the lower spring seat comprises a second body and an insertion part, wherein the bottom of the second body is provided with a second insertion cavity used for accommodating a push rod, the insertion part can be abutted to the top end of the second body, the insertion part is accommodated in the first insertion cavity and is fixedly connected with the first body, the top end of the second body is provided with an oil return throttling hole capable of communicating the second insertion cavity with the second inner cavity, the peripheral surface of the top end of the second insertion cavity is provided with an oil inlet throttling hole capable of communicating the second channel with the second insertion cavity, the top end of the push rod and the second insertion cavity are surrounded to form a control cavity with variable volume, and the oil return throttling hole, the oil inlet throttling hole and the control cavity form a fourth channel in the state that the driving mechanism drives the control valve coupling piece to drive the needle valve to move upwards; and the lower spring is sleeved on the ejector rod, and two ends of the lower spring are respectively abutted against the bottom end of the second body and the top end of the needle valve.

Preferably, the control valve matching part further comprises: the two ends of the limiting seat are respectively abutted against the driving mechanism and the upper spring, and an installation groove is formed in the circumferential direction of the limiting seat; and the O-shaped sealing ring is partially accommodated in the mounting groove to prevent the high-pressure fuel from continuously moving upwards.

Preferably, the top end of the ejector rod is provided with a notch along the circumferential direction of the ejector rod.

Preferably, wherein the first body and the central rod are integrally formed; or the first body and the center rod are detachably connected.

Preferably, wherein the drive mechanism comprises: the iron core is wound with a preset number of coils; the armature is arranged at the lower end of the iron core and is connected with the central rod into a whole through a nut; the iron core and the armature are both made of soft magnetic materials.

Preferably, wherein the length of the insertion portion is less than the depth of the first insertion cavity; and/or

The diameter of the oil inlet throttling hole is not larger than that of the oil return throttling hole.

Preferably, the oil injector body is further provided with a plurality of oil return ports, and each oil return port is communicated with the oil return channel.

The invention has the characteristics and advantages that:

according to the invention, the on-off of the oil outlet of the control valve can be realized only by overcoming smaller spring pressing force, so that hydraulic balance is realized, the requirement of the control valve on electromagnetic force is further reduced, and the design difficulty of the electromagnet is reduced.

Drawings

In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings needed to be used in the description of the embodiments will be briefly introduced below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art to obtain other drawings based on these drawings without creative efforts.

FIG. 1 is a schematic perspective view of a common rail injector of a marine diesel engine according to the present invention;

FIG. 2 is a structural sectional view of the common rail injector of the marine diesel engine according to the invention;

FIG. 3 is a sectional view of the needle valve coupling of the present invention;

FIG. 4 is a cross-sectional view of the injector body of the present invention;

FIG. 5 is a cross-sectional view of the control valve assembly of the present invention;

FIG. 6 is a structural cross-sectional view of the drive mechanism of the present invention;

FIG. 7 is a structural cross-sectional view of the mounting cap of the present invention;

FIG. 8 is a partial cross-sectional view of another angle of the injector body of the present invention;

FIG. 9 is a partial cross-sectional view of another angle of the injector body of the present invention.

Reference numerals and description:

100. a common rail injector of a marine diesel engine; 1. a needle valve coupling piece; 11. a first channel; 12. a needle valve; 13. a first lumen; 131. an oil containing groove; 132. an oil inlet gap; 14. a pressure chamber; 141. spraying a hole; 15. a cooling jacket; 151. a cooling chamber; 2. an injector body; 21. a second channel; 22. a third channel; 23. a cooling channel; 24. a second lumen; 25. an oil return port; 3. a control valve coupling member; 32. an upper spring; 33. an upper spring seat; 331. a first body; 3311. a first insertion cavity; 332. a center pole; 3321. a shoulder seat portion; 34. a lower spring seat; 341. a second body; 3411. a second insertion cavity; 342. an insertion portion; 3412. a return orifice; 3413. an oil inlet orifice; 343. a control chamber; 35. a top rod; 36. a lower spring; 37. a limiting seat; 371. mounting grooves; 38. an O-shaped sealing ring; 4. a drive mechanism; 41. an iron core; 42. a coil; 43. an armature; 44. a nut; 5. installing a cap; 51. a screw; 6. and locking the nut.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

The invention provides a common rail fuel injector 100 of a marine diesel engine, which comprises a needle valve matching part 1, a control valve matching part 3, a fuel injector body 2, an installation cap 5 and a locking nut 6, and is shown in the figures 1 to 9.

Specifically, referring to fig. 2 and 3, a first channel 11 communicated with a first inner cavity 13 for accommodating a needle 12 is formed inside the needle coupling 1, that is, the first channel 11 is communicated with the first inner cavity 13, a pressure chamber 14 is formed at the bottom end of the needle coupling 1, and a plurality of spray holes 141 are formed in a peripheral wall of the pressure chamber 14; referring to fig. 4, 8 and 9, the fuel injector body 2 has a second passage 21, a third passage 22, a cooling passage 23, and a second inner cavity 24 for accommodating the control valve assembly 3 and the driving mechanism 4, and the second passage 21, the first passage 11 and a part of the first inner cavity 13 are communicated to form a fuel inlet passage (in some embodiments, an input end of the fuel inlet passage is communicated with an external fuel source to provide high-pressure fuel); referring to fig. 5, the control valve assembly 3 has a fourth passage capable of communicating with the second passage 21 and the second inner cavity 24, and the third passage 22 can sequentially communicate with the second inner cavity 24 and the first inner cavity 13 to form a return passage (in some embodiments, the output end of the return passage communicates with an external return tank to recover fuel); referring to fig. 7, the mounting cap 5 is fixedly arranged at the top end of the second inner cavity 24, and the mounting cap 5, the first inner cavity 13 and the second inner cavity 24 can enclose a mounting cavity for the needle valve 12, the control valve coupler 3 and the driving mechanism 4 to be sequentially arranged from bottom to top; referring to fig. 1 and 2, a locking nut 6 is sleeved on the outer surfaces of the needle valve matching part 1 and the oil injector body 2 to connect the two into a whole, that is, the inner surface of the locking nut 6 is provided with an internal thread, the outer surface of the top of the needle valve matching part 1 and the outer surface of the bottom end of the oil injector body 2 are both provided with an external thread, and the locking nut 6 is respectively connected with the needle valve matching part 1 and the oil injector body 2 into a whole in a threaded connection mode; under the state that the driving mechanism 4 drives the control valve matching part 3 to drive the needle valve 12 to move upwards, part of high-pressure fuel can flow from the oil inlet channel to the fourth channel and then flows out from the oil return channel, and the other part of high-pressure fuel can flow from the oil inlet channel to the pressure chamber 14 after flowing through part of the first inner cavity 13 and is sprayed out from the plurality of spray holes 141.

It should be understood by those skilled in the art that, because the cooling channel 23 is provided, a cooling inlet and a cooling outlet are correspondingly formed on the injector body 2 for renewing the cooling medium, wherein the cooling medium may be water or oil, and is not limited herein.

In some embodiments, referring to fig. 7, the mounting cap 5 has a hexagonal structure having a central through hole, two threaded holes for receiving the socket cap screws 51 for connecting the driving mechanism 4 and the mounting cap 5, and two wire holes for receiving wires electrically connected to the driving mechanism 4.

It will be understood by those skilled in the art that the shape of the mounting cap 5, the shape of the threaded hole, and the shape of the wiring hole can be adjusted and designed according to actual requirements, and are not limited herein. It is within the scope of the present invention to provide electrical connections for the drive mechanism 4, as long as it secures the drive mechanism 4 in the second interior cavity 24.

In some embodiments, referring to fig. 2, fig. 3, fig. 8 and fig. 9, the second passage 21 and the third passage 22 are symmetrically disposed in the injector body 2, the cooling passage 23 is sandwiched between the second passage 21 and the third passage 22, and a variable included angle is designed between the cooling oil passage and the oil inlet passage and between the cooling oil passage and the oil return passage according to a preset rule, and the cooling medium flows through the injector body 2 to achieve a cooling effect.

In some embodiments, referring to fig. 2 and 3, an oil receiving groove 131 is disposed at a junction of the first passage 11 and the first inner cavity 13, an oil receiving gap 132 communicating with the pressure chamber 14 is formed between the first inner cavity 13 and the needle 12 below the oil receiving groove 131, and a bottom of the needle 12 can abut against a top end of the pressure chamber 14 to cut off the oil receiving gap 132.

By adopting the design, the invention reduces the lateral impact force on the needle valve 12 after the high-pressure fuel oil flows into the oil containing groove 131 on one hand, and increases the volume after the high-pressure fuel oil flows into the oil containing groove 131 on the other hand, thereby ensuring the stability of large-cycle fuel injection quantity and being beneficial to reducing the pressure fluctuation of the high-pressure fuel oil inflow.

In order to ensure that the positions of the first inner cavity 13 of the needle valve matching part 1 and the second inner cavity 24 of the injector body 2 meet the design and use requirements (i.e. ensure that the coaxiality of the needle valve matching part 1 and the injector body 2 meets the design requirements), in some embodiments, a plurality of positioning pins (not shown in the figure) are further arranged on the connecting surfaces of the needle valve matching part 1 and the injector body 2, and the positioning pins are cylindrical structures and can be respectively inserted into corresponding pin holes.

In some embodiments, referring to fig. 1 to fig. 3, the common rail injector 100 for a marine diesel engine further includes a cooling jacket 15 disposed at the bottom end of the needle coupling 1, a cooling cavity 151 is defined between the cooling jacket 15 and the bottom end of the needle coupling 1, and the pressure chamber 14 protrudes downward from the cooling jacket 15 to inject high-pressure fuel through the plurality of injection holes 141. Specifically, the cooling jacket 15 is connected to the needle valve coupling 1 along its circumferential direction at the top thereof by electric welding (in some embodiments, the electric welding is spot welding), and is not welded to the needle valve coupling 1 at the bottom of the cooling jacket 15. In some preferred embodiments, the cooling cavity 151 is communicated with the cooling channel 23, so that the cooling effect is increased by increasing the length of the cooling channel 23, and in this way, the step of additionally adding a cooling medium to the cooling cavity 151 is avoided, so that the cooling efficiency is improved while the cooling effect is ensured.

In some embodiments, referring to fig. 3, the needle valve couple 1 is a structure having a central through hole, a top end of the structure is formed with a fitting groove for the needle valve 12 to be clamped, a bottom end of the structure protrudes downward to form the pressure chamber 14, a plurality of injection holes 141 are circumferentially arranged in the pressure chamber 14, and an arrangement manner and an arrangement number of the injection holes 141 can be designed and adjusted according to actual requirements, which is not explained and illustrated herein.

Further, referring to fig. 2 and 3, the bottom end of the needle 12 is designed to be tapered so as to facilitate its insertion into the first cavity 13 and further facilitate its coupling with the surrounding wall of the first cavity 13 to form a tapered high-pressure sealing surface, thereby enabling communication or cutoff of the high-pressure fuel in the pressure chamber 14 as the needle 12 moves up and down. By adopting the structural design of the needle valve 12, the invention is beneficial to reducing the mass of the needle valve 12, thereby reducing the impact force of the needle valve 12 on a sealing surface after being seated; the seat surface of the needle valve 12 is designed to be a conical structure (namely, the bottom end of the needle valve 12 adopts a conical structure), and the needle valve 12 is matched with the seat surface to form a linear sealing surface structure, so that the sealing effect of a sealing surface is improved.

Further, referring to fig. 2, the control valve matching part 3 includes an upper spring 32, an upper spring seat 33, a lower spring seat 34 and a lower spring 36. Wherein the upper spring 32 and the lower spring 36 are both pre-compressed springs.

Specifically, the upper spring seat 33 includes a first body 331 having a first insertion cavity 3311 at a bottom thereof, and a center rod 332 disposed at a top end of the first body 331, a top end of the center rod 332 is fixedly connected to the driving mechanism 4, a shoulder seat 3321 for mounting the upper spring 32 is formed at a connection portion of the center rod 332 and the first body 331, the upper spring 32 can be sleeved on the center rod 332, and two ends of the upper spring 32 are respectively abutted between the shoulder seat 3321 and the driving mechanism 4; the lower spring seat 34 includes a second body 341 having a second insertion cavity 3411 at a bottom thereof for receiving the rod 35, and an insertion portion 342 capable of abutting on a top end of the second body 341, that is, the second body 341 has a second insertion cavity 3411, the second insertion cavity 3411 is for receiving the rod 35, the insertion portion 342 is received in the first insertion cavity 3311 and fixedly connected to the first body 331, a top end of the second body 341 is opened with a return flow orifice 3412 capable of communicating the second insertion cavity 3411 with the second inner cavity 24, a top end of the second insertion cavity 3411 is opened at a peripheral surface thereof with an oil inlet flow orifice 3413 capable of communicating the second passage 21 with the second insertion cavity 3411, and a top end of the rod 35 and the second insertion cavity 3411 enclose a variable volume control cavity 343, in a state that the driving mechanism 4 drives the control valve coupling member 3 to drive the needle valve 12 to move upwards, the return orifice 3412, the oil inlet orifice 3413 and the control chamber 343 form the aforementioned fourth passage; the lower spring 36 is sleeved on the top rod 35, and two ends of the lower spring 36 respectively abut against the bottom end of the second body 341 and the top end of the needle valve 12.

According to the invention, the fourth channel is communicated with the oil return channel, so that high-pressure fuel stored in the control cavity 343 can be discharged, the pressure of the high-pressure fuel in the control cavity 343 is reduced, the driving mechanism 4 drives the control valve coupling member 3 to drive the needle valve 12 to move upwards, and the fuel injection function is further realized.

In some embodiments, the first body 331 and the center rod 332 are integrally formed; in other embodiments, the first body 331 and the center rod 332 are detachably connected.

Further, referring to fig. 2, the control valve assembly 3 further includes a limit seat 37 and an O-ring 38. Specifically, two ends of the limiting seat 37 are respectively abutted against the driving mechanism 4 and the upper spring 32, and an installation groove 371 is formed in the circumferential direction of the limiting seat 37; a portion of the O-ring 38 is received in the groove 371 to prevent the high pressure fuel from continuing to move upward. Further, the limiting seat 37 is provided with a central through hole, a boss structure is further arranged on the limiting seat 37 along the radial direction of the limiting seat, and the boss structure is utilized to realize the matching limiting with the oil injector body 2, so that the function of abutting against the driving mechanism 4 and the upper spring 32 is realized.

In some embodiments, referring to FIG. 2, the top end of the stem 35 is cut along its circumference to increase the volume of the control chamber 343, thereby ensuring that the pressure of the high pressure fuel at that location meets the operating requirements.

Further, referring to fig. 2 and fig. 6, the driving mechanism 4 includes an iron core 41 and an armature 43, specifically, a predetermined number of coils 42 are wound on the iron core 41 (i.e., the two are matched to form an electromagnet); the armature 43 is arranged at the lower end of the iron core 41 and is connected with the central rod 332 into a whole through a nut 44; wherein, the iron core 41 and the armature 43 are both made of soft magnetic materials. Preferably, the nut 44 is a thin nut made to international standards.

It will be understood by those skilled in the art that the driving mechanism 4 is of a normally closed type, i.e. when the electromagnet is not energized, the moving member (including the integrated structure of the control valve couple 3 and the armature 43) is fixed on the upper spring seat 33 by the initial pre-load force of the upper spring 32 located between the limit seat 37 and the upper spring seat 33.

In some embodiments, referring to fig. 2 and 5, the length of the insert portion 342 is less than the depth of the first insert cavity 3311; the present invention is designed in such a manner as to ensure the reciprocating movement of the insertion part 342 in the first insertion chamber 3311, and preferably, the insertion part 342 is in the form of a long rod. In other embodiments, referring to fig. 2 and 5, the diameter of the oil inlet orifice 3413 is not greater than the diameter of the oil return orifice 3412.

In some embodiments, referring to fig. 1 and 2, the injector body 2 further has a plurality of oil return ports 25, and each oil return port 25 is communicated with the oil return passage. The invention adopts the design, can deal with internal leakage oil return, and two lateral leakage oil return ports 25 are added on the side edges for discharging the oil return at the internal leakage position.

The invention has at least the following characteristics and advantages:

1. the invention adopts the design of static leakage, reduces the high-pressure bearing area of the needle valve 12, and avoids overlarge stress borne by the needle valve 12, thereby reducing the strength requirement of the needle valve 12;

2. the control valve matching part 3 adopts a sleeve-like structure, the opening and closing of the oil return hole are controlled by the up-and-down sliding of the sleeve, and no matter whether the control valve matching part is in a working state or not, the control valve matching part 3 is not influenced by the axial force of high-pressure fuel oil, so that the electromagnetic force requirement on the electromagnetic valve is reduced, the response speed of the electromagnetic valve is improved, and the design difficulty of the electromagnetic valve is reduced;

3. the structure of the sleeve type control valve matching part 3 ensures that the stress of each component is not restricted by the diameter of the oil return hole, so that the diameter of the oil return orifice 3412 is larger, the pressure relief speed of the control cavity 343 is greatly increased after the electromagnetic valve is electrified, and the response characteristic of the oil injector is improved;

4. the invention designs the large oil containing groove 131 structure to meet the requirement of large circulating oil injection quantity of the whole diesel engine and ensure the stability of oil injection.

The working principle of the present invention will be described and explained with reference to fig. 1 to 9:

external high-pressure fuel enters an oil inlet channel through an oil inlet of the marine diesel engine common rail oil injector 100 to be divided into two paths, one path of high-pressure fuel directly enters the oil containing groove 131 in the needle valve matching part 1 through the oil inlet channel, and the other path of high-pressure fuel enters the control cavity 343 through a part of oil inlet channel and an oil inlet throttling hole 3413 in the control valve component. As the high-pressure fuel continuously enters the control chamber 343, the pressure in the control chamber 343 continuously increases, so that the lower spring 36 abuts against the needle valve 12, and the bottom end of the needle valve 12 abuts against the top end periphery of the pressure chamber 14 to cut off the pressure chamber 14 from the oil inlet passage.

When the coil 42 in the driving mechanism 4 is energized, an upward electromagnetic force is generated to act on the armature 43 and the limiting seat 37, when the electromagnetic force is larger than the pretightening force of the upper spring 32, the armature 43 drives the upper spring seat 33 to lift and start to move upwards, the return throttle 3412, the oil inlet throttle 3413 and the control cavity 343 form a fourth channel along with the gradual increase of the lift, and high-pressure fuel in the control cavity 343 enters the return channel through the return throttle 3412 and flows out of the fuel injector through an oil return opening 25 acting on the fuel injector body 2. At this time, although the high-pressure fuel in the control chamber 343 is continuously flowing in through the fuel inlet throttle 3413, the return throttle 3412 is designed to have a diameter larger than that of the fuel inlet throttle 3413, so that the high-pressure fuel flowing out of the control chamber 343 is larger than that of the high-pressure fuel flowing into the control chamber 343, causing the fuel pressure in the control chamber 343 to drop, when the upward fuel pressure acting on the plunger 35-needle valve 12 in the oil reservoir 131 is larger than the sum of the fuel pressure (decreasing) in the control chamber 343 and the biasing force of the lower spring 36, the plunger 35-needle valve 12 is lifted together and starts moving upward, and at the same time, the seal seat surface between the needle valve 12 and the pressure chamber 14 is opened, the high-pressure fuel in the oil reservoir 131 starts to enter the pressure chamber 14, and the fuel is ejected through the ejection hole 141;

when the coil 42 in the driving mechanism 4 is powered off, because the armature 43 and the central rod 332 are connected into an integral structure through the thin nut 44, the integral moving part of the armature 43 and the central rod 332 is pressed on the limiting seat 37 by the upper spring 32, at this time, the upper spring seat 33 seals the fourth channel, the oil return through hole in the control cavity 343 is cut off, the control cavity 343 does not return oil (i.e., does not drain oil outwards), the ejector rod 35 and the needle valve 12 are assembled into an integral moving structure, and the downward area of the high-pressure fuel acting on the ejector rod 35 in the control cavity 343 is larger than the upward area of the high-pressure fuel acting on the needle valve 12 in the oil containing groove 131, so the downward pressure acting on the moving part of the ejector rod 35-needle valve 12 in the control cavity 343 is larger than the upward pressure acting on the ejector rod 35-needle valve 12 in the oil containing groove 131, and therefore, as the high-pressure fuel continuously flows into the control cavity 343, the downward pressure difference of the fuel acting on the moving part of the ejector rod 35-needle valve 12 and the pretightening force of the lower spring 36 act together, the needle valve 12 is pressed on the seat surface of the needle valve 12 by rapid downward movement, the high-pressure fuel oil in the enclosed oil containing groove 131 enters the pressure chamber 14, at the moment, the oil injector does not inject oil, and the common rail oil injector 100 of the marine diesel engine is restored to the initial state, namely, a working cycle is completed.

Although the present invention has been described with reference to the preferred embodiments, it should be understood that various changes, substitutions and alterations can be made herein without departing from the spirit and scope of the invention as defined by the appended claims.

Claims

1. A common rail injector of a marine diesel engine is characterized by comprising:

the needle valve coupling piece is internally provided with a first channel communicated with a first inner cavity for accommodating a needle valve, the bottom end of the needle valve coupling piece is provided with a pressure chamber, and the surrounding wall of the pressure chamber is provided with a plurality of spray holes;

the oil injector body is internally provided with a second channel, a third channel, a cooling channel and a second inner cavity for accommodating a control valve matching part and a driving mechanism, the second channel, the first channel and part of the first inner cavity are communicated to form an oil inlet channel, the control valve matching part is provided with a fourth channel capable of communicating the second channel and the second inner cavity, and the third channel can be sequentially communicated with the second inner cavity and the first inner cavity to form an oil return channel;

the mounting cap is fixedly arranged at the top end of the second inner cavity, and the mounting cap, the first inner cavity and the second inner cavity can enclose a mounting cavity for the needle valve, the control valve matching part and the driving mechanism to be sequentially arranged from bottom to top;

the locking nut is sleeved on the outer surfaces of the needle valve matching part and the oil injector body so as to connect the needle valve matching part and the oil injector body into a whole;

the actuating mechanism drive control valve matching parts drive under the state of needle valve upward movement, part high pressure fuel can be followed oil feed passageway flows through follow behind the fourth passageway oil return passage flows out, another part high pressure fuel can be followed oil feed passageway flows through the part enter behind the first inner chamber the pressure chamber is followed a plurality of orifice spouts.

2. The common rail injector of the marine diesel engine according to claim 1, wherein an oil receiving groove is formed at a joint of the first passage and the first inner cavity, an oil receiving gap communicated with the pressure chamber is formed between the first inner cavity and the needle valve below the oil receiving groove, and a bottom of the needle valve can abut against a top end of the pressure chamber to cut off the oil receiving gap.

3. The common rail injector for the marine diesel engine according to claim 2, further comprising a cooling jacket sleeved at the bottom end of the needle valve matching part, a cooling cavity is formed between the cooling jacket and the bottom end of the needle valve matching part in an enclosing manner, and the pressure chamber protrudes downwards from the cooling jacket so as to inject high-pressure fuel oil through the plurality of injection holes.

4. The common rail injector for the marine diesel engine according to claim 1, wherein the control valve matching part includes:

an upper spring;

the upper spring seat comprises a first body with a first insertion cavity at the bottom and a central rod arranged at the top end of the first body, the top end of the central rod is fixedly connected with the driving mechanism, a shoulder seat part for mounting the upper spring is formed at the joint of the central rod and the first body, the upper spring can be sleeved on the central rod, and two ends of the upper spring are respectively abutted between the shoulder seat part and the driving mechanism;

the lower spring seat comprises a second body and an insertion part, wherein the bottom of the second body is provided with a second insertion cavity used for accommodating a push rod, the insertion part can be abutted to the top end of the second body, the insertion part is accommodated in the first insertion cavity and is fixedly connected with the first body, the top end of the second body is provided with an oil return throttling hole capable of communicating the second insertion cavity with the second inner cavity, the peripheral surface of the top end of the second insertion cavity is provided with an oil inlet throttling hole capable of communicating the second channel with the second insertion cavity, the top end of the push rod and the second insertion cavity are surrounded to form a control cavity with variable volume, and the oil return throttling hole, the oil inlet throttling hole and the control cavity form a fourth channel in the state that the driving mechanism drives the control valve coupling piece to drive the needle valve to move upwards;

and the lower spring is sleeved on the ejector rod, and two ends of the lower spring are respectively abutted against the bottom end of the second body and the top end of the needle valve.

5. The common rail injector for the marine diesel engine according to claim 4, wherein the control valve matching part further includes:

the two ends of the limiting seat are respectively abutted against the driving mechanism and the upper spring, and an installation groove is formed in the circumferential direction of the limiting seat;

and the O-shaped sealing ring is partially accommodated in the mounting groove to prevent the high-pressure fuel from continuously moving upwards.

6. The common rail injector for the marine diesel engine according to claim 5, characterized in that a top end of the carrier rod is provided with a notch along a circumferential direction thereof.

7. The common rail injector for marine diesel engines according to claim 4,

the first body and the center rod are integrally formed; or

The first body and the center rod are detachably connected.

8. The common rail injector for marine diesel engines according to claim 4, characterized in that the drive mechanism includes:

the iron core is wound with a preset number of coils;

the armature is arranged at the lower end of the iron core and is connected with the central rod into a whole through a nut;

the iron core and the armature are both made of soft magnetic materials.

9. The common rail injector for marine diesel engines according to claim 4,

the length of the insertion portion is less than the depth of the first insertion cavity; and/or

10. The common rail injector of the marine diesel engine according to any one of claims 1 to 9, wherein a plurality of oil return ports are further formed in the injector body, and each oil return port is communicated with the oil return channel.