CN110671224B - Low-speed machine high-pressure common rail system with multiple security functions - Google Patents

Abstract

This solution provides a low-speed engine high-pressure common rail system with multiple security functions to realize the multiple security functions of the high-pressure common rail system. The system includes: an ECU, an electronically controlled high-pressure oil pump, in which an electronically controlled proportional valve is arranged, and the electronically controlled proportional valve is used to adjust the oil intake ratio of the low-pressure heavy oil entering the electronically controlled high-pressure oil pump from the oil tank of the low-speed engine according to the first instruction of the ECU; a first distribution block connected to the electronically controlled high-pressure oil pump through a first high-pressure oil pipe; a second distribution block connected to the first distribution block through a second high-pressure oil pipe; a common rail pipe connected to the second distribution block through a third high-pressure oil pipe; a sensor is installed on the common rail pipe, and the sensor is connected to the ECU; a plurality of flow limiting valve assemblies are installed on the common rail pipe, and each flow limiting valve assembly is connected to an electronically controlled fuel injector through a fourth high-pressure oil pipe; a pressure limiting valve assembly is also installed on the common rail pipe; a cut-off valve assembly and a safety valve assembly are installed on the first distribution block; a circulation valve assembly is also installed on the common rail pipe and each electronically controlled fuel injector.

Description

A low-speed engine high-pressure common rail system with multiple safety functions

Technical Field

The invention relates to the field of high-pressure common rail systems, in particular to a low-speed engine high-pressure common rail system with multiple safety functions.

Background Art

With the increasingly stringent emission regulations and the increasingly intensified energy crisis, diesel engine fuel systems have increasingly adopted high-pressure common rail systems. The high-pressure common rail system, with its high injection pressure, high response speed, flexible control and other characteristics, can meet the increasingly stringent emission regulations and users' requirements for fuel economy and emissions. The high-pressure common rail system is different from the traditional mechanical fuel injection system. The high-pressure common rail system is always in a high-pressure state. At this time, the high-pressure common rail system has very strict requirements on the reliability and safety of components.

Summary of the invention

The object of the present invention is to provide a low-speed engine high-pressure common rail system with multiple safety functions, so as to realize the multiple safety functions of the high-pressure common rail system.

The present invention provides a low-speed engine high-pressure common rail system with multiple safety functions, comprising: an ECU,

An electronically controlled high-pressure oil pump is provided with an electronically controlled proportional valve, the electronically controlled proportional valve is used to adjust the oil inlet ratio of the low-pressure heavy oil entering the electronically controlled high-pressure oil pump from the oil tank of the low-speed engine according to the first instruction of the ECU; a first distribution block connected to the electronically controlled high-pressure oil pump through a first high-pressure oil pipe; a second distribution block connected to the first distribution block through a second high-pressure oil pipe; a common rail pipe connected to the second distribution block through a third high-pressure oil pipe; a sensor for detecting the fuel pressure of the high-pressure heavy oil in the common rail pipe is installed on the common rail pipe, and the sensor is connected to the ECU; a plurality of flow limiting valve assemblies are installed on the common rail pipe, each of the flow limiting valve assemblies is connected to an electronically controlled injector through a fourth high-pressure oil pipe; the flow limiting valve assembly is used between the fourth high-pressure oil pipe and the common rail pipe The common rail pipe is closed when the fuel pressure difference exceeds the set pressure difference value; a pressure limiting valve assembly is also installed on the common rail pipe, and the pressure limiting valve assembly is used to open when the fuel pressure in the common rail pipe exceeds a first set pressure value, so that the fuel pressure in the common rail pipe is stabilized to a target pressure value; a cut-off valve assembly and a safety valve assembly are assembled on the first distribution block; the cut-off valve assembly is used to perform pressure relief processing according to the second instruction of the ECU; the safety valve assembly is used to open when the cut-off valve assembly and the pressure limiting valve assembly fail and the fuel pressure in the common rail pipe exceeds the second set pressure value; a circulation valve assembly is also installed on the common rail pipe and the electronically controlled fuel injector, and the circulation valve assembly is used to open when the low-speed engine is shut down, so that a circulation loop is formed between the common rail pipe, the electronically controlled fuel injector and the fuel tank of the low-speed engine respectively.

Preferably, the electronically controlled high-pressure oil pump comprises: a pump body, the pump body is provided with a center hole along the axial direction; a pump cover, the pump cover is mounted on the upper end surface of the pump body; the inlet and outlet valve assembly, the plunger pair, the plunger spring, the lower spring seat assembly and the guide piston assembly are all assembled in the center hole of the pump body; the electronically controlled proportional valve is assembled on the side of the pump body; the inlet and outlet valve assembly comprises: an inlet valve assembly and an outlet valve assembly; the inlet valve assembly comprises: an inlet valve seat, an inlet valve and an inlet valve spring; the inlet valve is mounted in the center hole of the inlet valve seat; the inlet valve spring is limited between the inlet valve and the hole wall of the inlet valve seat; under the compression of the inlet valve spring, the inlet valve forms a conical seal with the inlet valve seat; the outlet valve assembly comprises: an outlet valve seat, an outlet valve, an outlet valve spring and an outlet valve spring seat; the outlet The valve spring seat is installed at the upper end of the oil outlet valve seat; the oil outlet valve is installed in the middle hole of the oil outlet valve seat; the oil outlet valve spring is limited between the oil outlet valve and the oil outlet valve spring seat; under the compression of the oil outlet valve spring, the oil outlet valve and the oil outlet valve seat form a conical seal; a high-pressure oil outlet chamber is formed between the oil outlet valve seat and the oil inlet valve seat; a high-pressure oil chamber is formed in the plunger pair, and the high-pressure oil chamber is connected to the high-pressure oil outlet chamber through the oil hole on the oil inlet valve seat; the electrically controlled proportional valve is connected to the oil inlet hole of the oil inlet valve seat through the oil hole on the pump body, and the oil inlet hole is connected or disconnected from the high-pressure oil chamber; a cooling circulation oil channel is provided on the electrically controlled proportional valve, and the cooling oil in the cooling oil channel of the pump body flows back to the cooling oil channel of the pump body after being injected into the cooling circulation oil channel.

Preferably, the plunger pair includes: a plunger sleeve, which is arranged at the lower end of the oil inlet valve seat; a plunger, which can be slidably inserted into the center hole of the plunger sleeve, and the plunger sleeve, the plunger and the oil inlet valve seat together form the high-pressure oil chamber; the inner wall of the plunger sleeve is provided with a first annular groove and a second annular groove; the pump body is provided with a mixed oil outlet channel and a lubricating oil channel, the mixed oil outlet channel is connected to the first annular groove through the mixed oil channel on the plunger sleeve, and the lubricating oil channel is connected to the second annular groove through the lubricating oil channel on the plunger sleeve; the first annular groove is located above the second annular groove.

Preferably, the lower spring seat assembly is arranged below the plunger pair, and the lower spring seat assembly comprises: an outer spring seat, which is a boss-type structure with a thin outer side and a thick middle, and the upper end surface of the outer spring seat is provided with a third countersunk hole with a concave spherical surface; an upper sphere, the lower part of which is installed in the third countersunk hole, and the lower end surface of the upper sphere is provided with a convex spherical surface matching the concave spherical surface; an inner spring seat, which is sleeved on the upper part of the upper sphere, and the inner spring seat has a first axial through hole that penetrates the upper and lower end surfaces; the lower cylindrical head of the plunger is limited in the first axial through hole, and the lower end surface of the lower cylindrical head of the plunger abuts against the upper end surface of the upper sphere.

Preferably, a spherical hole is provided at the center of the third countersunk hole, and a third annular groove is provided on the lower end surface of the outer spring seat, and the spherical hole and the third annular groove are connected through a lubricating oil inlet pipe; the outer surface of the outer spring seat forms a conical surface, and the conical surface is provided with a lubricating oil outlet channel, and the lubricating oil outlet channel is connected to the lower end surface of the outer spring seat; the lubricating oil outlet channel is arranged obliquely; a circumferential annular groove is provided in the circumferential direction of the upper sphere; the positioning pin is installed in the circumferential annular groove after passing through the positioning pin hole of the outer spring seat; the spacing between the upper and lower surfaces of the circumferential annular groove is greater than the cylindrical diameter of the portion of the positioning pin located in the circumferential annular groove.

Preferably, the first axial through hole arranged inside the inner spring seat includes: a seventh hole, an eighth hole and a ninth hole whose diameters gradually increase from top to bottom; a first guide hole with a gradually increasing diameter is arranged between the eighth hole and the ninth hole; a second guide hole with a gradually increasing diameter is arranged on the side of the ninth hole facing the upper sphere; the hole walls of the first guide hole and the second guide hole are formed as guide cones; the upper part of the upper sphere passes through the second guide hole and is partially located in the ninth hole; there is a gap greater than or equal to 1 mm between the upper sphere and the ninth hole; there is a gap greater than or equal to 1 mm between the third countersunk hole and the upper sphere.

Preferably, the electronically controlled high-pressure oil pump further comprises: an upper spring seat, the sleeve of which is arranged on the plunger sleeve and is located at the upper end of the inner spring seat; the plunger spring comprises: a first plunger spring, which is pressed between the upper spring seat and the outer spring seat; and a second plunger spring, which is pressed between the upper spring seat and the inner spring seat.

Preferably, the diameters of the concave spherical surface in the outer spring seat and the convex spherical surface of the upper sphere are 20 to 100 times the diameter of the plunger.

Preferably, the guide piston assembly comprises: a guide piston, a first mounting hole is provided at the center of the upper end surface of the guide piston; a second mounting hole is provided at the lower end surface of the guide piston, the first mounting hole and the second mounting hole are connected through a connecting hole, and the lower spring seat assembly is installed in the first mounting hole; a roller assembly comprises: a roller installed in the second mounting hole, a roller bushing interference-fitted in the roller, and thrust bearings interference-fitted at both axial ends of the roller; an annular groove is provided in the axial direction of the roller, and a circular arc transition connection is formed between the groove bottom of the annular groove and the axial end surface of the roller; a roller pin, the gap of which is installed in the roller bushing; a boss is protruding from the hole wall of the second mounting hole, and the boss contacts the thrust bearing;

The boss is evenly arranged with a plurality of first radial oil grooves in the radial direction, and the first radial oil grooves are arranged relative to the thrust bearing. Preferably, the outer surface of the roller pin is set as a cylindrical surface, and two steps of waist grooves are respectively arranged at two positions on the cylindrical surface, and the waist grooves are arranged in the middle position of the roller pin; a small angle wedge groove with an angle of 5 to 20° is formed between the waist grooves located in the outer layer and the outer surface of the roller bushing, and an oil hole is arranged in the waist groove located in the inner layer; the two oil holes at the two positions are connected through the lubricating oil outlet channel, and the two oil holes are arranged at 70 to 120°.

Preferably, the outer surface of the guide piston is set as a cylindrical surface, and a plurality of circumferential oil grooves, a first axial oil groove and a vertical groove are arranged on the cylindrical surface, and the vertical groove is opened in the circumferential oil groove, and the vertical groove is connected to the circumferential oil groove through the first axial oil groove; an inclined hole is also arranged on the cylindrical surface, and the two ends of the inclined hole are respectively connected to the circumferential oil groove and the inner wall of the second mounting hole; a second axial oil groove connected to the circumferential oil groove is also arranged on the cylindrical surface; a first straight hole and a second straight hole connected to each other are also arranged on the cylindrical surface, and the first straight hole is connected to the first axial oil groove, and the second straight hole is connected to the first mounting hole; a lubricating oil inlet channel is arranged on the outer circumferential surface of the roller pin, and the lubricating oil inlet channel is arranged relative to the inclined hole, and the lubricating oil inlet channel is connected to the lubricating oil outlet channel.

Preferably, a DLC coating is provided on the outer circumferential surface of the roller pin; the roller bushing is made of copper alloy; the thrust bearing is made of copper alloy; forced lubrication is adopted between the roller pin and the roller bushing; and forced lubrication is adopted between the thrust bearing and the boss.

Preferably, the common rail pipe has an oil inlet pipe and an oil return pipe running through both ends; an oil inlet end cover is fixed at one end of the common rail pipe, and an oil inlet port connected to the oil inlet pipe is provided on the oil inlet end cover; an end cover is fixed at the other end of the common rail pipe, and an oil outlet connected to the oil inlet pipe is provided on the end cover, and the circulating valve assembly is fixed on the end cover; the pressure limiting valve assembly and multiple flow limiting valve assemblies are respectively connected to the oil inlet pipe, and the pressure limiting valve assembly and multiple flow limiting valve assemblies are respectively connected to the oil return pipe.

Preferably, the circulation valve assembly comprises: a first valve body fixed on the end cover, a first center hole connected to the oil outlet is formed on the lower end surface of the first valve body, and a second center hole is formed on the upper end surface, the first center hole is connected to the second center hole; a first valve core, which can be slidably inserted into the first center hole from the lower end surface of the first valve body and is partially located in the second center hole; a lower spring seat, which is sleeved on the part of the first valve core located in the second center hole and is fixedly connected to the first valve core; a first cavity is formed between the lower spring seat and the bottom of the second center hole; a pressure cover, which is fixed on the upper end surface of the first valve body, and a threaded hole is formed on the upper end surface of the pressure cover; an oil return joint, which is partially fixed in the threaded hole; a first pressure regulating spring, which is limited between the lower spring seat and the pressure cover; a pressure regulating spring is provided on the first valve body There is a first oil return passage connected to the first center hole, a second oil return passage connected to the first oil return passage is arranged on the pressure cover, and a third oil return passage connected to the second oil return passage is arranged on the oil return joint, and the first oil return passage, the second oil return passage and the third oil return passage form a circulating oil passage; a first air inlet passage connected to the first cavity is arranged on the first valve body, a second air inlet passage connected to the first air inlet passage and an air inlet connected to the second air inlet passage are arranged on the pressure cover; when the spring force of the first pressure regulating spring is less than or equal to the sum of the pressure of the gas introduced into the first cavity and the oil inlet pressure at the oil inlet end of the first center hole, a conical surface seal is formed between the first valve core and the first center hole, and the position where the conical surface seal is formed is below the connection position of the first oil return passage and the first center hole.

Preferably, a first sealing cone surface and an external thread are provided at the top of the portion of the first valve core located in the second center hole, and the external thread is located at the upper end of the first sealing cone surface; the lower spring seat passes through the external thread and is sleeved on the first sealing cone surface, and the lower spring seat has a second sealing cone surface that forms a cone surface seal with the first sealing cone surface; the lower spring seat is tightened by a nut sleeved on the periphery of the external thread; the first pressure-adjusting spring is sleeved on the nut and fixed on the lower spring seat.

Preferably, the oil return joint is threadedly fixed in the threaded hole; a first sealing plane is provided on the upper end surface of the gland at the opening of the threaded hole; and a second sealing plane is provided on the oil return joint to form a planar seal with the first sealing plane.

Preferably, a third cavity is formed between the lower end surface of the oil return joint and the bottom of the threaded hole, and the third cavity is connected to the second oil return channel and the third oil return channel respectively, and the maximum flow area of the third cavity is greater than the maximum flow area of the second oil return channel.

Preferably, when the first valve core moves upward to the top dead center position in the first valve body, a distance H2 between the first valve body and the lower end surface of the first valve core is smaller than a distance H1 between the lower end surface of the lower spring seat and the bottom of the second center hole.

Preferably, the lower spring seat includes: a third center hole for limiting the first pressure-adjusting spring and a fourth center hole for cooperating with the first valve core, the aperture of the fourth center hole is larger than the diameter of the external thread; the outer diameter of the lower spring seat is the same as the aperture of the second center hole.

Preferably, the flow limiting valve assembly comprises: a valve seat connected to the high-pressure common rail, a second valve body, a second valve core and a second pressure regulating spring, wherein the valve seat has a first oil inlet hole communicating with the high-pressure common rail;

The second valve body has a second axial through hole running through its upper and lower end faces, and the valve seat is press-fitted into the second axial through hole from the lower end face of the second valve body; the second valve core is installed in the second axial through hole and is arranged above the valve seat; the second valve core has an axial blind hole connected to the first oil inlet hole, and a cavity is formed between the upper end of the second valve core and the second axial through hole; a transverse throttling hole connecting the axial blind hole and the cavity is arranged in the second valve core; the second pressure-regulating spring is sleeved on the second valve core and is limited in the cavity; the head of the upper end of the second valve core has a third sealing cone surface and a fourth sealing cone surface connected to each other; the hole wall of the second axial through hole is formed with a first sealing seat surface which can form a cone seal with the third sealing cone surface, and the first sealing seat surface can form a gap with the fourth sealing cone surface.

Preferably, the second axial through hole includes a first hole, a second hole, a third hole, a fourth hole, a fifth hole and a sixth hole which are sequentially connected from top to bottom; the valve seat portion is press-fitted into the first hole; the second valve core is assembled into the second hole, and the upper part of the second valve core and the upper part of the second hole form a cavity; the hole wall of the third hole forms the first sealing seat surface; the hole wall of the fifth hole is formed with a second sealing seat surface for forming a seal with the oil inlet end of the injector oil pipe; the aperture of the sixth hole is larger than the apertures of the first hole, the second hole, the third hole, the fourth hole and the fifth hole.

Preferably, a fourth oil return passage is also provided on the second valve body, one end of the fourth oil return passage is connected to the sixth hole, and the other end is connected to the lower end surface of the second valve body; the maximum cross-sectional flow area of the fourth oil return passage is smaller than the maximum cross-sectional flow area of the gap formed between the fourth sealing cone surface and the first sealing seat surface; the maximum cross-sectional flow area of the fourth oil return passage is smaller than the maximum cross-sectional flow area of the second axial through hole and the maximum cross-sectional flow area of the fourth hole.

Preferably, the head portion of the lower end of the valve seat is formed with a fifth sealing cone surface for forming a cone seal with the high-pressure common rail; the large outer circle of the lower end of the valve seat is milled with a first flat, and the first flat is connected to the fourth oil return channel.

Preferably, the pressure-limiting valve assembly comprises: a third valve body, a third valve core, a third pressure-adjusting spring and an oil pipe joint, wherein the third valve body is provided with a first-stage hole, a second-stage hole, a third-stage hole and a fourth-stage hole which are connected in sequence from bottom to top; the head of the third valve core can be slidably inserted from the fourth-stage hole and partially located in the second-stage hole after passing through the third-stage hole, and the third valve core can form a conical surface seal with the second-stage hole; a first gap for fuel to pass through is formed between the third valve core and the third-stage hole, and a second gap for fuel to pass through is formed between the third valve core and the fourth-stage hole; the oil pipe joint is fixed to the upper end of the third valve body, and a first countersunk hole, a second countersunk hole and an oil outlet hole which are connected in sequence are provided in the oil pipe joint from bottom to top, and the third pressure-adjusting spring is limited between the third valve core and the second countersunk hole.

Preferably, the aperture of the first-level hole is larger than the aperture of the second-level hole, and the aperture of the third-level hole is larger than the apertures of the second-level hole and the fourth-level hole.

Preferably, the head of the third valve core is arranged to form a first cone angle and a second cone angle connected in sequence, the angle of the first cone angle is 120°, and the angle of the second cone angle is 60°; a symmetrically arranged second flat is milled on the outer circle of the middle part of the third valve core, and a second gap for fuel to pass through is formed between the second flat and the hole wall of the fourth-level hole of the third valve body, and the maximum fuel area that can flow in the gap is larger than the maximum fuel area that can flow in the second-level hole; a plurality of grooves arranged at intervals are provided on the outer circle of the middle and upper part of the third valve core, and a third gap for fuel to pass through is formed between the grooves and the first countersunk hole; the third pressure regulating spring is sleeved on the second small outer circle of the upper part of the third valve core.

Preferably, a sealing seat surface for forming a conical seal with the second cone angle is formed at the connecting portion of the second-stage hole and the third-stage hole, and the angle deviation between the sealing seat surface and the second cone angle is less than 1°; the aperture of the fourth-stage hole of the third valve body is

Preferably, a limit range h1 for the movement of the third valve core is provided between the third valve core and the bottom of the first counterbore of the oil pipe joint; and an overlapping area h is provided between the third valve core and the third valve body.

The beneficial effects of the present invention are as follows: multiple valves such as a circulation valve assembly, a pressure limiting valve assembly, a cut-off valve assembly and a safety valve assembly are involved in the common rail system, and each type of valve is started under specific working conditions to achieve multiple security of the common rail system.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic diagram of the structure of the system of the present invention; FIG. 2 is a schematic diagram of the structure of the electronically controlled high-pressure oil pump of the present invention; FIG. 3 is a schematic diagram of the structure of the inlet and outlet valve assembly; FIG. 4 is a schematic diagram of the structure of the plunger pair of the prior art; FIG. 5 is a schematic diagram of the cooperation between the plunger pair and the pump body, the oil inlet valve seat and the upper spring seat; FIG. 6 is a schematic diagram of the structure of the angle formed between the plunger unevenness and the upper sphere; FIG. 7 is a schematic diagram of the structure of the cooperation between the plunger and the upper sphere after spherical adjustment; FIG. 8 is a schematic diagram of the structure of the cooperation between the lower spring seat assembly and the plunger; FIG. 9 is a schematic diagram of the cross-section of the lower spring seat assembly; FIG. 10 is a schematic diagram of the cross-section of the lower spring seat assembly; FIG. 11 is a schematic diagram of the structure of the inner spring seat; FIG. 12 is a schematic diagram of the structure of the upper sphere; FIG. 13 is a schematic diagram of the cross-section of the outer spring seat; FIG. 14 is a schematic diagram of the cross-section of the outer spring seat; FIG. 15 is a schematic diagram of the cross-section of the guide piston assembly; FIG. 16 is a schematic diagram of the cross-section of the guide piston; FIG. 17 is a schematic diagram of the structure of the guide piston FIG. 18 is a cross-sectional schematic diagram of a guide piston; FIG. 19 is a structural schematic diagram of a roller pin; FIG. 20 is an axial cross-sectional schematic diagram of a roller pin; FIG. 21 is a radial cross-sectional schematic diagram of a roller pin; FIG. 22 is a force distribution schematic diagram of a roller assembly without an annular groove; FIG. 23 is a force distribution schematic diagram of a roller assembly with an annular groove; FIG. 24 is a structural schematic diagram of a common rail of the present invention; FIG. 25 is a structural schematic diagram of a common rail of the present invention; FIG. 26 is a structural schematic diagram of a common rail of the present invention; FIG. 27 is a structural schematic diagram of a flow limiting valve of the present invention; FIG. 28 is a structural schematic diagram of a flow limiting valve of the present invention; FIG. 29 is a structural schematic diagram of a flow limiting valve of the present invention; FIG. 30 is a structural schematic diagram of a pressure limiting valve of the present invention; FIG. 31 is a structural schematic diagram of a pressure limiting valve of the present invention; FIG. 32 is a structural schematic diagram of a circulating valve of the present invention; FIG. 33 is a structural schematic diagram of a circulating valve of the present invention; FIG. 34 is a structural schematic diagram of a guide piston;

Description of the accompanying drawings: 1—electronically controlled high-pressure oil pump; 101—pump body; 1012—lubricating oil channel; 102—pump cover; 103—inlet and outlet oil valve assembly; 1031—inlet valve assembly; 10311—inlet valve seat; 10312—inlet valve; 10313—inlet valve spring; 1032—outlet valve assembly; 10321—outlet valve seat; 10322—outlet valve; 10323—outlet valve spring; 10324—outlet valve spring seat; 1033—high-pressure oil outlet chamber; 104—plunger pair; 1041—high-pressure oil chamber; 1042—plunger sleeve; 10421—first annular groove; 10422—second annular groove; 10423—mixing oil channel; 10424—lubricating oil channel; 1043—plunger; 10431—lower cylindrical head ; 105— plunger spring; 1051— first plunger spring; 1052— second plunger spring; 106— lower spring seat assembly; 1061— outer spring seat; 10611— third countersunk hole; 10612— spherical hole; 10613— third annular groove; 10614— lubricating oil inlet pipeline: 10615— lubricating oil outlet channel; 10616— positioning pin hole; 1062— upper sphere; 10621— circumferential annular groove: 1063— inner spring seat; 10631— first axial through hole; 10632— seventh hole; 10633— eighth hole; 10634— ninth hole; 10635— first guide hole; 10636— second guide hole; 10637— guide cone surface; 10638— back cutter groove; 10639— weight reduction annular groove ; 1064—positioning pin; 107—piston guide assembly; 1071—piston guide; 10711—first mounting hole; 10726—second chamfer; 10712—second mounting hole; 10713—connecting hole; 10714—boss; 10715—first radial oil groove; 10727—tenth hole; 10713—connecting hole; 10729, 10725—circumferential oil groove; 10716—first axial oil groove; 10717—vertical groove; 10718—oblique hole; 10719—second axial oil groove; 10720—first straight hole; 10721—second straight hole; 10741—first chamfer; 1072—roller assembly; 10728—roller; 10724—ring groove; 10722—roller bushing; 10 723—thrust bearing; 1073—roller pin; 10731, 10732—waist-shaped groove; 10733, 10734—oil hole; 10735—lubricating oil inlet passage; 10739—third radial oil passage; 10740—axial oil passage; 10736—eleventh hole; 10737—spring; 10738—stop pin; 2—electrically controlled proportional valve; 109—upper spring seat; 3—first high-pressure oil pipe; 5—cut-off valve assembly; 6—first distribution block; 7—safety valve assembly; 8—second high-pressure oil pipe; 9—second distribution block; 10—third high-pressure oil pipe; 14—fourth high-pressure oil pipe; 15—electronically controlled injector; 12—common rail pipe; 1201—oil inlet pipe; 1202—oil return pipe; 1203—first incision; 1204—first Two incisions; 121—oil inlet cover; 122—end cover; 123—pressure limiting valve mounting seat; 124—sensor; 125—flow limiting valve mounting seat; 126—bracket; 127—sensor mounting seat; 128—bolt; 129—screw; 16—circulation valve assembly; 161—first valve body; 1601—first center hole; 1602—second center hole; 1605—first oil return passage; 163—third sealing ring groove; 1602—second center hole; 1619—guide; 1620—first sealing ring groove; 1622—second sealing ring groove; 1608—first air inlet passage; 1623—air outlet passage; 162—first valve core; 1611—first sealing cone surface; 1612—external thread; 1624—third sealing ring; 164—lower spring seat ;1617—third center hole;1618—fourth center hole;1613—second sealing cone surface;1625—fourth sealing ring groove;1626—matching portion;1627—fourth sealing ring;1628—first sealing ring;167—pressure cover;1606—second oil return passage;1603—threaded hole;1629—second air inlet passage;1630—air inlet;1615—first sealing plane;168—oil return joint;1616—second sealing plane;1607—third oil return passage;169—first pressure regulating spring;1614—nut;1631—second sealing ring;1632—screw;18—pressure limiting valve assembly;181—third valve body;182—third valve core;183—second O-ring;184—bolt;185 —third pressure regulating spring; 186—oil pipe joint; 187—pressure regulating gasket; 18101—first stage hole; 18102—second stage hole; 18103—sealing seat surface; 18104—third stage hole; 18105—fourth stage hole; 18601—first countersunk hole; 18602—second countersunk hole; 18603—oil outlet hole; 18201—first cone angle; 18202—second cone angle; 18203—second flat; 18204—third outer circle; 18205—groove; 18206—second small outer circle; h—overlapping area; h1—limiting stroke; 13—flow limiting valve assembly; 131—valve seat; 132—second valve body; 133—second valve core; 136—first O-ring; 135—second pressure regulating spring; 13101—first inlet Oil hole; 13102—fifth sealing cone surface; 13103—sunk groove; 13104—first flat; 13105—large end surface; 13106—first small outer circle; 13201—small end surface; 13202—large bevel; 13203—first matching part; 13204—second matching part; 13205—third hole; 13206—first sealing seat surface; 13207—fourth hole; 13208—second sealing seat surface; 13209—second axial through hole; 13210—fourth oil return channel; 13211—screw mounting hole; 13301—first outer circle; 13302—axial blind hole; 13303—second outer circle; 13304—lateral throttling hole; 13305—third sealing cone surface; 13306—fourth sealing cone surface.

DETAILED DESCRIPTION

1 , the present invention provides a low-speed engine high-pressure common rail system with multiple security functions, including: an ECU, an electronically controlled high-pressure oil pump 1, in which an electronically controlled proportional valve 2 is arranged, and the electronically controlled proportional valve 2 is used to adjust the oil inlet ratio of the low-pressure heavy oil entering the electronically controlled high-pressure oil pump 1 from the oil tank of the low-speed engine according to the first instruction of the ECU; the electronically controlled high-pressure oil pump 1 adopts a single-plunger structure, and the system is provided with three electronically controlled high-pressure oil pumps 1 as backup to prevent the system from failing due to a failure of the high-pressure oil pump. A first distribution block 6 connected to the electronically controlled high-pressure oil pump 1 through a first high-pressure oil pipe 3; a second distribution block 9 connected to the first distribution block 6 through a second high-pressure oil pipe 8; a common rail pipe 12 connected to the second distribution block 9 through a third high-pressure oil pipe 10; a sensor 17 for detecting the fuel pressure of the high-pressure heavy oil in the common rail pipe 12 is installed on the common rail pipe 12, and the sensor 17 is connected to the ECU; a plurality of flow limiting valve assemblies 13 are installed on the common rail pipe 12, and each flow limiting valve assembly 13 is connected to an electronically controlled fuel injector 15 through a fourth high-pressure oil pipe 14; the flow limiting valve assembly 13 is used to close when the fuel pressure difference between the fourth high-pressure oil pipe 14 and the common rail pipe 12 exceeds a set pressure difference value; the flow limiting valve assembly 13 is installed on the common rail pipe 12, and its outlet is connected to the electronically controlled fuel injector 15 through the fourth high-pressure oil pipe 14. Multiple fuel injectors are installed per cylinder, and each fuel injector is provided with an independent flow limiting valve assembly 13. When the fourth high-pressure oil pipe 14 ruptures or the electronically controlled fuel injector 15 sprays abnormally, the flow limiting valve assembly 13 cuts off the high-pressure fuel from entering the electronically controlled fuel injector 15, protecting the safety of the low-speed engine. The fourth high-pressure oil pipe 14 adopts a double-wall design, and all double-walled fourth high-pressure oil pipes 14 low-pressure abnormal leakages are fully connected with the low-pressure abnormal leakages of the connected components, forming a system low-pressure abnormal leakage oil return system.

The common rail pipe 12 is also equipped with a pressure limiting valve assembly 18, which is used to open when the fuel pressure in the common rail pipe 12 exceeds the first set pressure value, so that the fuel pressure in the common rail pipe 12 is stabilized to the target pressure value; the pressure limiting valve assembly 18 is installed on the common rail pipe 12, and the pressure limiting valve assembly 18 adopts a mechanical structure, and has the ability to maintain the fault pressure after opening at a fixed pressure. When the system pressure exceeds 125MPa, the pressure limiting valve assembly 18 automatically opens and enters the fault mode, keeping the system running safely at the pressure required by the fault mode.

The first distribution block 6 is equipped with a cut-off valve assembly 5 and a safety valve assembly 7; the cut-off valve assembly 5 is used to perform pressure relief processing according to the second instruction of the ECU; the safety valve assembly 7 is used to open when the cut-off valve assembly 5 and the pressure limiting valve assembly 18 fail and the fuel pressure in the common rail pipe 12 exceeds the second set pressure value; the cut-off valve assembly 5 adopts a pneumatic control structure and is installed on the first distribution block 6, which is convenient for quickly releasing the system pressure. When an emergency occurs in the low-speed engine or the fuel system and an emergency stop is required, the cut-off valve assembly 5 is quickly opened as a second pressure protection measure to quickly release the system pressure. The cut-off valve assembly 5 adopts an independent oil return system, which is separated from the static abnormal leakage oil return system of the system. The safety valve assembly 7 adopts a mechanical structure and is installed on the first distribution block 6, and its opening pressure is 150MPa. When the system is out of control and the cut-off valve assembly 5 and the pressure limiting valve assembly 28 also fail, the safety valve assembly 7 is opened as the second protection to ensure the safety of the entire system.

A circulation valve assembly 16 is also installed on the common rail pipe 12 and the electronic fuel injector 15. The circulation valve assembly 16 is used to open when the low-speed machine is shut down, so that a circulation loop is formed between the common rail pipe 12, the electronic fuel injector 15 and the fuel tank of the low-speed machine. The circulation valve assembly 16 is installed on the end cover 122 and each electronic fuel injector 15. When the machine is started, there is no fuel in the common rail pipe 12 and the electronic fuel injector 15. At this time, the valve core in the circulation valve assembly is at the bottom dead center position, and the circulation valve assembly 16 is in an open circulation state. In order to make the common rail system quickly build pressure, compressed air is introduced into the circulation valve assembly 16, so that the circulation valve assembly 16 quickly closes the system and starts to build pressure. When the pressure exceeds the spring preload of the circulation valve assembly 16, the closing of the circulation valve mainly depends on the fuel pressure; when the machine is shut down, after the system pressure is reduced by the cut-off valve assembly 5, the circulation valve assembly 16 automatically opens to realize the low-pressure automatic circulation function to ensure the safety of the system heavy oil. After the diesel engine is shut down and depressurized, the circulation valve assembly 16 is opened. Considering that the heavy oil in the system cools and solidifies, it corrodes the components and reduces the life of the components. At this time, the system enters the low-pressure circulation mode, and the low-pressure fuel enters the common rail pipe 12 after passing through the high-pressure oil pipe, and then the fuel is divided into two branches. One branch flows out to the fuel tank from the circulation valve assembly 16 installed on the oil inlet cover 121; the other branch enters the electronically controlled fuel injector 15 after passing through the limiting valve assembly 16, and flows out to the fuel tank through the circulation valve assembly 16 installed on the electronically controlled fuel injector 15. The circulation area set by the circulation valve assembly 16 on the oil inlet cover 121 must be smaller than the circulation area of the circulation valve assembly 16 on the electronically controlled fuel injector 15. If the circulation area of the circulation valve assembly 16 does not match the circulation area of the electronically controlled fuel injector 15, the low-pressure fuel will flow out from the circulation valve assembly 16 at the oil inlet cover 121, and no fuel will flow out of the circulation valve assembly 16 of the electronically controlled fuel injector 15, and the fuel circulation here cannot be realized. Therefore, it is important to match the flow area sizes of the two circulation valve assemblies 16, and the flow area of the circulation valve assembly 16 is determined by the lift of the valve core.

The entire common rail system static seal abnormal leakage oil return system connects the electronically controlled injector 15, the fourth high-pressure oil pipe 14, the limiting valve assembly 13, the common rail pipe 12, the oil inlet end cover 121, the third high-pressure oil pipe 10, the second distribution block 9, the second high-pressure oil pipe 8, the first distribution block 6, the first high-pressure oil pipe 3, and the electronically controlled high-pressure oil pump 1, and returns the oil from the lowest leakage outlet of the electronically controlled high-pressure oil pump 1.

The electronically controlled high-pressure oil pump 1 is a marine monolithic high-pressure oil pump, which specifically includes: a pump body 101, which is provided with a central hole along the axial direction. A pump cover 102, which is installed on the upper end surface of the pump body 101. An inlet and outlet oil valve assembly 103, a plunger pair 104, a plunger spring 105, a lower spring seat assembly 106 and a guide piston assembly 107 are all assembled in the central hole of the pump body 101. An electronically controlled proportional valve 2 is assembled on the side of the pump body 101. The inlet and outlet oil valve assembly 103 includes: an oil inlet valve assembly 1031 and an oil outlet valve assembly 1032. The oil inlet valve assembly 1031 includes: an oil inlet valve seat 10311, an oil inlet valve 10312 and an oil inlet valve spring 10313. The oil inlet valve 10312 is installed in the middle hole of the oil inlet valve seat 10311; the oil inlet valve spring 10313 is limited between the oil inlet valve 10312 and the hole wall of the oil inlet valve seat 10311; under the compression of the oil inlet valve spring 10313, the oil inlet valve 10312 forms a conical seal with the oil inlet valve seat 10311. The oil outlet valve assembly 1032 includes: an oil outlet valve seat 10321, an oil outlet valve 10322, an oil outlet valve spring 10323 and an oil outlet valve spring seat 10324. The oil outlet valve spring seat 10324 is installed at the upper end of the oil outlet valve seat 10321; the oil outlet valve 10322 is installed in the middle hole of the oil outlet valve seat 10321; the oil outlet valve spring 10323 is limited between the oil outlet valve 10322 and the oil outlet valve spring seat 10324; under the compression of the oil outlet valve spring 10323, the oil outlet valve 10322 forms a conical seal with the oil outlet valve seat 10321. A high-pressure oil outlet chamber 1033 is formed between the oil outlet valve seat 10321 and the oil inlet valve seat 10311. A high-pressure oil chamber 1041 is formed in the plunger pair 104, and the high-pressure oil chamber 1041 is connected to the high-pressure oil outlet chamber 1033 through the oil hole on the oil inlet valve seat 10311. The electric control proportional valve 2 is connected to the oil inlet hole of the oil inlet valve seat 10311 through the oil hole on the pump body 101, and the oil inlet hole is connected or disconnected with the high-pressure oil chamber 1041. A cooling oil circulation passage is provided on the electronically controlled proportional valve 2 . The cooling oil from the cooling oil passage of the pump body 101 is injected into the cooling oil circulation passage and then flows back into the cooling oil passage of the pump body 101 .

As shown in FIG2 , the middle hole provided in the pump body 101 is a through hole that penetrates the upper and lower end faces of the pump body 101. The pump cover 102 is fixed to the upper end face of the pump body 101, and a mounting hole opposite to the middle hole of the pump body 101 is provided in the direction of the pump cover 102 toward the main body 1, and the oil outlet valve seat 10321 is installed in the middle hole of the pump body 101 and the mounting hole of the pump body 101. As can be seen from FIG2 , the oil outlet valve assembly 1032 is installed above the oil inlet valve assembly 1031, and there is an oil passage connected to the oil outlet valve assembly 1032 above the pump cover 102. Finally, the high-pressure heavy oil pumped out by the high-pressure oil pump of the present application is discharged through the oil passage on the pump cover 102.

As a hydraulic control device, the electronically controlled proportional valve 2 has the effect of oil inlet throttling. The electronically controlled proportional valve 2 is mainly used for oil inlet regulation of light oil (such as gasoline, diesel), etc. In the prior art, there is no solution to apply the electronically controlled proportional valve 2 to the oil inlet regulation of heavy oil. The reason is that when heavy oil is working, its temperature can be as high as 160°C, which has exceeded the limit working temperature of the armature, coil and other electronic control components of the existing electronically controlled proportional valve 2. In the prior art, for the oil inlet throttling regulation of the high-pressure oil pump using heavy oil, a mechanical design of transmission is adopted, that is, the oil volume is controlled by the spiral groove above the speed regulator and the plunger. The defects of this oil inlet regulation method are low oil volume regulation accuracy, slow response, and the oil volume depends on the speed of the speed regulator.

In the embodiment of the present application, the electric control proportional valve 2 is used to adjust the oil inlet of the heavy oil, which can solve the problems of low flexibility and high temperature of the existing mechanical adjustment method. Targetedly, a cooling circulation oil channel is set inside the electric control proportional valve 2 to allow the cooling oil flowing in the pump body 101 to enter the electric control proportional valve 2, and to cool the electric control components in the electric control proportional valve 2 in a targeted manner, so that the electric control components of the electric control proportional valve 2 are kept within the normal temperature range. The cooling circulation oil channel designed in the electric control proportional valve 2 should meet the following requirements: (1) as close as possible to the electric control components such as the coil and armature of the electric control proportional valve; (2) the cooling oil flow rate introduced into the cooling circulation oil channel should be able to reduce the temperature of the electric control components such as the coil and armature to within the working temperature range. In order to make the cooling circulation oil channel meet the requirements, it is necessary to perform simulation calculations and experiments on different types of armatures in advance to determine the specific parameter information such as the spatial layout and size of the cooling circulation oil channel in each type. The advantage of the above design is that a cooling circulation oil channel is provided inside the electronically controlled proportional valve 2, which reduces the temperature of the armature and coil of the electronically controlled proportional valve 2, and makes the electronically controlled components work within the normal temperature range, thereby allowing the electronically controlled proportional valve 2 to be used to throttle the oil inlet of the pump. The electronically controlled proportional valve 2 overcomes the shortcomings of mechanical oil volume adjustment, improves the accuracy, flexibility and response speed of oil flow regulation, and thus achieves a more accurate match between the pump oil volume and the diesel engine operating conditions, avoids performance degradation due to insufficient oil supply, and also reduces the surplus flow during operation, thereby reducing the actual load of the pump.

As shown in FIG3 , in the oil filling stage, the oil inlet valve 10312 opens under the oil inlet pressure of the electric control proportional valve 2, and the oil outlet valve 10322 is sealed with the oil outlet valve seat 10321 under the back pressure, and the low-pressure heavy oil oil inlet electric control proportional valve 2 enters the high-pressure oil chamber 1041 from the oil inlet port to start oil filling. By adjusting the opening of the electric control proportional valve 2, the oil inlet amount is controlled to meet different working conditions. In the oil pumping stage: the guide piston assembly 107 moves upward, and the column The plug 1043 compresses the heavy oil in the high-pressure oil chamber 1041, and the heavy oil pressure gradually increases. When the fuel pressure in the high-pressure oil chamber 1041 is greater than the oil inlet pressure, the oil inlet valve 10312 is closed. Since the high-pressure oil outlet chamber 1033 is connected to the high-pressure oil chamber 1041, when the fuel pressure in the high-pressure oil chamber 1041 exceeds the back pressure and the oil outlet valve spring force, the oil outlet valve 10322 opens, and the high-pressure fuel is discharged from the middle hole of the pump cover 102 through the oil outlet valve spring seat 10324. As shown in Figure 4, the previous high-pressure common rail heavy oil pump adopts a mechanical design, the oil inlet pipeline 505 is arranged on the plunger sleeve 6, the plunger 5 can be slidably inserted in the plunger sleeve 6, and no oil inlet valve assembly is provided. During operation, when the oil is sucked and compressed alternately, part of the pressurized fuel will flow back from the oil inlet pipeline 505 to the low-pressure oil inlet channel, which will cause a large pressure change in the oil inlet pipeline 505, so that the relevant parts of the oil inlet pipeline 505 are prone to cavitation. This is also one of the main forms of damage to the plunger pair in actual ship experiments. Compared with the prior art, the present application adds an oil inlet valve assembly 1031, and the high-pressure oil chamber of the plunger sleeve 1042 is quickly closed when the oil suction changes to the compression, thereby ensuring the pressure stability of the relevant position in the oil inlet passage of the oil inlet valve seat 10311, and effectively preventing cavitation.

5 , the plunger pair 104 includes: a plunger sleeve 1042, which is arranged at the lower end of the oil inlet valve seat 10311. A plunger 1043, which is slidably inserted into the middle hole of the plunger sleeve 1042, and the plunger sleeve 1042, the plunger 1043 and the oil inlet valve seat 10311 together form a high-pressure oil chamber 1041. The inner wall of the plunger sleeve 1042 is provided with a first annular groove 10421 and a second annular groove 10422. The pump body 101 is provided with a mixed oil outlet passage and a lubricating oil passage 1012. The mixed oil outlet passage is connected to the first annular groove 10421 through a mixed oil passage 10423 on the plunger sleeve 1042. The mixed oil formed at the first annular groove 422 flows out to the waste oil tank through the mixed oil outlet passage and the mixed oil passage 10423. The lubricating oil passage 1012 is connected to the second annular groove 10422 through a lubricating oil passage 10424 on the plunger sleeve 1042. The first annular groove 10421 is located above the second annular groove 10422. The lubricating oil entering the second annular groove 10422 has two functions: 1. It seals the fuel entering the gap between the plunger 1043 and the plunger sleeve 1042 from the high-pressure oil chamber 1041 above the plunger 1043, preventing the fuel from flowing into the transmission parts below the plunger 1043 and preventing the fuel from invading the transmission parts below the plunger 1043 and contaminating the lubricating oil system of the whole machine; 2. It makes the friction surface below the plunger 1043 in a state of clean lubricating oil lubrication, improving the friction state of the plunger 1043. Compared with the heavy oil above, the lubricating oil has a higher cleanliness, contains additives to improve friction, and can form a better oil film than lubricating with heavy oil.

Since the traditional low-speed engine allows heavy oil to leak to the bottom of the plunger 1043, the leaked heavy oil is collected separately. However, the leaked heavy oil has the risk of corroding the plunger spring 105 and other components under the plunger 1043. In this application, a small amount of lubricating oil in the second annular groove 10422 of the plunger pair 104 can completely prevent the leakage of heavy oil, and prevent the leaked heavy oil from corroding important components such as the plunger spring 105 under the plunger sleeve 1042. In addition, due to the complex dynamic sealing mechanism provided on the guide piston under the plunger of the traditional low-speed engine, the overall vertical height of the high-pressure oil pump is large and the cost is high. This application uses a small amount of lubricating oil to seal the heavy oil, which can effectively reduce the vertical height of the guide piston 1071 (the traditional heavy oil guide piston is provided with a long heavy oil sealing section), thereby reducing the vertical height of the high-pressure oil pump and reducing the overall weight of the high-pressure oil pump. According to the test, the scheme of this application reduces the vertical height of the high-pressure oil pump by 1/3.

7 to 14, the lower spring seat assembly 106 is arranged below the plunger coupler 104, and the lower spring seat assembly 106 includes: an outer spring seat 1061, which is a boss-type structure with a thin outer side and a thick middle. During operation, the outer spring seat 1061 mainly bears the pressure transmitted to the upper sphere by the plunger 1043, and the stress field caused by the pressure is distributed in a conical shape in the outer spring seat 1061. The outer spring seat 1061 is set to a corresponding boss shape, which can reduce the mass of the outer spring seat 1061 while meeting the strength requirement, thereby reducing the motion mass, and the thicker part between the bosses also provides design space for the intermediate spherical surface and the oil channel.

The upper end surface of the outer spring seat 1061 is provided with a third countersunk hole 10611 with a concave spherical surface; the lower part of the upper sphere 1062 is installed in the third countersunk hole 10611, and the lower end surface of the upper sphere 1062 is provided with a convex spherical surface matching the concave spherical surface. The inner spring seat 1063 is sleeved on the upper part of the upper sphere 1062, and the inner spring seat 1063 has a first axial through hole 10631 that penetrates the upper and lower end surfaces.

The lower cylindrical head 431 of the plunger 1043 is limited in the first axial through hole 10631, and the lower end surface of the lower cylindrical head 431 of the plunger 1043 abuts against the upper end surface of the upper sphere 1062. According to experiments, when the plunger is working, because there is a parallelism error between the tail plane and the corresponding pressing surface (guide piston or spring seat surface), the tail plane of the plunger 1043 may be locally overstressed during pressing (in FIG. 6, an angle of β is formed between the upper sphere 1062 and the plunger 1043), and the uneven force distribution will generate additional torque about the center plane of the plunger 1043, which will bring additional load and energy loss to the system, affecting the dynamic characteristics of the system. When the lower spring seat assembly 106 with a spherical surface is arranged between the plunger 1043 and the guide piston 1071, even if there is a large parallelism error between the upper end surface of the guide piston 1071 and the end surface of the tail of the plunger 1043, the spherical surface can automatically adjust the angle so that the contact surface between the upper sphere 1062 and the outer spring seat 1061 maintains full contact (from the state of FIG. 6 to the state of FIG. 7, in FIG. 7, the two contact surfaces of the upper sphere 1062 and the plunger 1043 fit together), eliminating local contact, balancing the overall force, and relieving the tendency of excessive local stress. At the same time, the combined force passes through the center of the spherical surface, eliminating the bending moment of the attachment, thereby optimizing the dynamic characteristics and improving the bearing capacity of the system.

9 to 14 , a spherical hole 10612 is provided at the center of the third counterbore 10611, and a third annular groove 10613 is provided on the lower end surface of the outer spring seat 1061. The spherical hole 10612 and the third annular groove 10613 are communicated with each other through a lubricating oil inlet pipe 10614, and the lubricating oil inlet pipe 10614 is communicated with the oil channel on the guide piston 7. The lubricating oil forms an oil film on the convex spherical surface of the outer spring seat 1061 through the lubricating oil inlet pipe 10614, which can effectively prevent the fretting wear and damage between the convex spherical surface of the upper sphere 1062 and the concave spherical surface of the outer spring seat 1061; the spherical hole 10612 provides lubricating oil to lubricate the spherical surface, and uses the lubricating oil to form an elastohydrodynamic lubrication effect on the spherical surface, thereby reducing the wear rate, contact stress, fretting damage, and improving the bearing capacity and fatigue strength of the spherical surface.

The outer surface of the outer spring seat 1061 forms a conical surface, and a lubricating oil outlet passage 10615 is provided on the conical surface. The lubricating oil outlet passage 10615 is connected to the lower end surface of the outer spring seat 1061; the lubricating oil outlet passage 10615 is arranged obliquely; the main purpose of the lubricating oil outlet passage 10615 is to connect the upper and lower areas of the outer spring seat 1061, so that the lubricating oil above the outer spring seat 1061 can flow smoothly to the lower area, and prevent the lubricating oil cavity above the outer spring seat 1061 from being filled up, thereby compressing the additional load caused by the lubricating oil. The lubricating oil outlet passage 10615 is provided on the outer conical surface of the outer spring seat 1061, so as to prevent the plunger spring 105 from covering the flow area of the lubricating oil outlet passage 10615, so that the flow area is not affected by the position of the plunger spring 105.

There are 8 lubricating oil outlet passages 10615; the multiple lubricating oil outlet passages 10615 are connected to the bottom end surface of the outer spring seat 1061 respectively. It can ensure that the lubricating oil in the upper space of the outer spring seat 1061 can flow out smoothly, avoiding the additional load caused by the accumulation of lubricating oil; at the same time, the lubricating oil outlet passages 10615 are obliquely arranged on the conical surface of the outer spring seat 1061, which also prevents the plunger spring 105 from blocking the lubricating oil outlet passages 10615 and causing the lubricating oil to flow unsmoothly and accumulate. A circumferential annular groove 10621 is opened in the circumferential direction of the upper sphere 1062. The positioning pin 1064 is installed in the circumferential annular groove 10621 after passing through the positioning pin hole 10616 of the outer spring seat 1061. The upper and lower surface spacing of the circumferential annular groove 10621 is greater than the cylindrical diameter of the portion of the positioning pin 1064 located in the circumferential annular groove 10621. The upper sphere 1062 and the outer spring seat 1061 are connected by a threaded positioning pin 1064, which is fixed on the outer spring seat 1061 by threads. The head of the positioning pin 1064 is set as a cylindrical surface, which is a positioning part. The upper sphere 1062 is provided with a corresponding circumferential annular groove 10621 for installing the pin head. The circumferential annular groove 10621 on the upper sphere 1062 can also be a circular hole. The positioning pin 1064 can roughly position the upper sphere 1062 and the outer spring seat 1061 to prevent the upper sphere 1062 from falling off from the outer spring seat 1061 during the reciprocating motion when the plunger 1043 and the upper sphere 1062 are separated.

As shown in FIG. 11 , the first axial through hole 10631 provided inside the inner spring seat 1063 includes: the seventh hole 10632, the eighth hole 10633 and the ninth hole 10634, whose diameters gradually increase from top to bottom; a first guide 10635 with a gradually increasing diameter is provided between the second hole 632 and the ninth hole 10634; a second guide hole 10636 with a gradually increasing diameter is provided on the side of the ninth hole 10634 facing the upper sphere 1062; the hole walls of the first guide hole 10635 and the second guide hole 10636 are formed into a guide cone 10637; the upper part of the upper sphere 1062 passes through the second guide hole 10636 and is located in the ninth hole 10634. Among them, the upper end surface of the lower cylindrical head 431 of the plunger 1043 abuts against the upper end surface of the eighth hole 10633; the hole wall of the eighth hole 10633 and the annular surface of the lower cylindrical head 10431 of the plunger 1043 fit together. Since the hole walls of the first guide hole 10635 and the second guide hole 10636 are formed as the guide cone surface 10637, if the plunger 1043 and the upper sphere 1062 are separated or the inner spring seat 1063 and the plunger 1043 are separated, when the plunger 1043 hits the upper sphere 1062 again, the guide cone surface 10637 will automatically align the plunger 1043 and the upper sphere 1062, the plunger 1043 and the inner spring seat 1063, and the inner spring seat 1063 and the upper sphere 1062, to prevent large angular deviations and radial displacements between the plunger 1043 and the inner spring seat 1063, and the inner spring seat 1063 and the upper sphere 1062, thereby ensuring that the system is in a suitable position even during a collision and balancing the overall force. Specifically, when the plunger 1043 is stuck, the inner spring seat 1063 is relatively still (i.e., stuck at the top dead center), and the outer spring seat 1061 and the upper sphere 1062 will collide back and forth. During the collision, the inner spring seat 1063 and the plunger 1043 may not be centered with the upper sphere 1062, which may cause local force during the collision. The inner spring seat 1063 is provided with a guide cone 10637, which can improve the centering property, and even during the collision, the inner spring seat 1063 and the upper sphere 1062 can be automatically aligned to improve the tendency of uneven force.

There is a gap greater than or equal to 1 mm between the upper sphere 1062 and the ninth hole 10634, specifically, there is a gap of 1 mm between the outer cylindrical surface of the upper sphere 1062 and the hole wall of the ninth hole 10634. Since the outer spring seat 1061 and the upper sphere 1062 are spherically matched and have a large (millimeter level) gap, the two can slide freely relative to each other. Therefore, during the operation of the plunger, if there is an angular error between the lower end surface of the lower cylindrical head 431 of the plunger 1043 and the upper end surface of the upper sphere 1062, when the plunger 1043 moves downward and hits the upper sphere 1062, the upper sphere 1062 will slide relative to the outer spring seat 1061 and automatically make up for the angular error, so that when the additional load is applied, the lower end surface of the lower cylindrical head 431 of the plunger and the upper end surface of the guide piston 1071 are evenly stressed, which can effectively prevent excessive local stress.

There is a gap greater than or equal to 1 mm between the third counterbore 10611 and the upper sphere 1062, specifically, there is a gap of 1 mm between the outer cylindrical surface of the upper sphere 1062 and the cylindrical surface of the third counterbore 10611, that is, there is a large gap (1 mm) between the upper sphere 1062 and the inner spring seat 1063, and there is a large gap (1 mm) between the positioning pin 1064 and the upper sphere 1062, between the positioning pin 1062 and the outer spring seat 1061, and between the upper sphere 1062 and the inner spring seat 1063, thereby ensuring that the effective rotational freedom of the upper sphere 1062 during radial movement will not be restricted by the positioning pin 1064, and the effective rotational freedom of the plunger 1043 and the upper sphere 1062 during radial movement will not be restricted by the inner spring seat 1063, thereby preventing radial additional load on the plunger 1043.

There are millimeter-level gaps between the upper sphere 1062 and the ninth hole 10634, and between the third counterbore 10611 and the upper sphere 1062, allowing the upper sphere 1062 to have a macroscopic angle error relative to the outer spring seat 1061, preventing the spherical surface from getting stuck, and achieving the above-mentioned effect of eliminating local contact, balancing the overall force, and alleviating the tendency of local excessive stress. In addition, as shown in FIG11 , the outer cylindrical surface of the inner spring seat 1063 and the hole wall of the second blind hole 6312 are both formed with a backing groove 10638; the upper end surface of the inner spring seat 1063 is provided with a weight-reducing annular groove 10639 around the central axis.

Referring to Fig. 2, it also includes: an upper spring seat 109, which is sleeved on the plunger sleeve 1042 and located at the upper end of the inner spring seat 9; the plunger spring 105 includes: a first plunger spring 1051, which is pressed between the upper spring seat 109 and the outer spring seat 1061; and a second plunger spring 1052, which is pressed between the upper spring seat 109 and the inner spring seat 1063. The diameter of the concave spherical surface in the outer spring seat 1061 and the convex spherical surface of the upper sphere 1062 is 20 to 100 times the diameter of the plunger 1043. The parallelism error of the tail of the plunger 1043 and the upper end surface of the guide piston 1071 is low in magnitude, generally in the order of 0.01, and there is no requirement for the spherical angle adjustment ability, so the small angle spherical adjustment can also meet the angle adjustment requirements. When the spherical surface is larger, only a small part of the force between the two surfaces is converted into tensile stress when under pressure. For metal materials, the compressive strength is generally higher than the tensile strength, and compressive stress is not easy to cause fatigue. Therefore, choosing a large spherical surface can reduce the proportion of tensile stress, thereby improving the material's bearing capacity and fatigue strength.

15 to 21, the guide piston assembly 107 comprises: a guide piston 1071, a first mounting hole 10711 is provided at the center of the upper end surface of the guide piston 1071; a second mounting hole 10712 is provided at the lower end surface of the guide piston 1071, the first mounting hole 10711 and the second mounting hole 10712 are connected through a connecting hole 10713, and the lower spring seat assembly 106 is installed in the first mounting hole 10711. The roller assembly 1072 comprises: a roller 10728 installed in the second mounting hole 10712, a roller bushing 10722 interference-fitted in the roller 10728, and thrust bearings 10723 interference-fitted at both axial ends of the roller 10728; an annular groove 10724 is provided in the axial direction of the roller 10728, and a circular arc transition connection is formed between the groove bottom of the annular groove 10724 and the axial end surface of the roller 10728. The roller pin 1073 is installed in the roller bushing 10722. The hole wall of the second mounting hole 10712 is protrudingly provided with a boss 10714, and the boss 10714 contacts the thrust bearing 10723. The boss 10714 is evenly arranged with a plurality of first radial oil grooves 10715 in the radial direction, and the first radial oil grooves 10715 are arranged relative to the thrust bearing 10723.

The roller bushing 10722, the thrust bearing 10723 and the roller 10728 all adopt interference fit to reduce the moving surface and increase the moving speed of the friction surface. In the theory of dynamic pressure lubrication, within a certain range, the friction coefficient decreases as the relative moving speed of the friction surface increases. Therefore, increasing the relative moving speed strengthens the dynamic pressure lubrication effect, thereby forming a thicker dynamic pressure oil film on the corresponding friction surface to avoid solid contact, thereby reducing the friction coefficient and wear.

The provision of the connecting hole has the following effects: (1) When the lubricating oil above the guide piston 1071 flows down from the connecting hole 10713, it is evenly distributed in the middle just above the second mounting hole 10712 of the roller 10728, and the lubricating oil is evenly distributed on the busbar of the roller 10728. The distribution of the lubricating oil on the surface of the roller 10728 is not affected by the forward and reverse rotation (it can be evenly distributed); (2) The vertical force distribution of the guide piston 1071 is improved, that is, the pressure of the plunger 1043 is distributed to the thicker position around the connecting hole 10713, so that the overall force is balanced, the maximum stress is reduced, and the reliability of the system's bearing capacity is improved. (In the conventional guide piston, the connecting hole is opened around the center, and the connecting hole position is solid. It is thinner at this position and has greater stress). (3) In the pump assembly, when the guide piston 1071 and the outer spring seat 1061 cooperate, the lubricating oil outlet oil passage 10615 of the outer spring seat 1061 is connected to the lubricating oil leaked above the plunger pair 104, which can avoid the spring from clogging the oil hole and increase the actual flow area of the lubricating oil.

The annular groove 10724 is formed by machining after finishing the inner hole and outer circle of the roller 10728, as shown in Figures 22 and 23. The setting of the annular groove 10724 reduces the rigidity of the two ends of the roller 10728. When the surface of the roller 10728 is subjected to radial pressure, the roller 10728 near the annular groove 10724 can be automatically deformed. At the same time, after machining the annular groove 10724, the outer circle and inner hole of the roller 10728 automatically collapse, forming micro-arc surfaces at both ends of the inner hole and outer circle of the roller 10728, reducing the geometric stress concentration at both ends of the roller 10728, and thus making the surface of the roller 10728 balanced. (Geometric stress concentration: when the surface of the roller 10728 is subjected to force, the contact stress at both ends of the generatrix of the roller 10728 is significantly greater than that in the middle). The groove wall of the annular groove 10724 is formed in an arc shape, which can effectively weaken the collective stress concentration on the outer cylindrical surface of the roller 10728 and the lateral pressure effect of the inner hole of the roller 10728 during the rotation of the roller 10728, so that the stress distribution on the inner and outer working surfaces of the roller assembly 1072 is balanced, thereby reducing the probability of biting between the roller assembly 1072 and the roller pin 1073.

The boss 10714 forms a thrust bearing model with the corresponding friction surface (end surface of the roller assembly). That is, the first radial oil groove 10715 is filled with lubricating oil, providing sufficient lubricating oil for the moving surface (end surface of the roller assembly), and using the end surface movement speed of the roller 10728 to form a dynamic pressure oil film on the end surface of the roller 10728, the boss 10714 of the guide piston 1071 and the end surface of the roller assembly 1072 are separated, thereby reducing wear and reducing the friction coefficient. The first radial oil groove 10715 is opened on the boss 10714 of the guide piston 1071, compared with opening it on the roller assembly 1072. The guide piston 1071 will not rotate relatively, and the distribution of high and low pressure oil film areas on the friction surface is relatively static, so the roller assembly 1072 is relatively static in the axial direction. If the first radial oil groove is opened on the moving part (the end face of the roller assembly 1072), the first radial oil groove will move relative to the guide piston 1071, causing relative movement of the oil film distribution, which will lead to unnecessary additional axial vibration of the roller 10728 and reduce the overall dynamic performance.

For roller 10728, roller 10728 adopts end groove deformation design to reduce boundary stress; specifically, for roller 10728, during processing, the outer circle of roller 10728 and the inner hole of the roller are first ground, and then the annular groove 10724 at the two axial end faces is grooved. After the groove cutting is completed, the outer circle and inner hole generatrix of roller 10728 are naturally deformed into arcs, which can effectively reduce the geometric stress concentration on the outer cylindrical surface of the roller and the lateral pressure effect of the inner hole of roller 10728 during the rotation of roller 10728, so that the stress distribution on the inner and outer working surfaces of roller assembly 1072 is balanced, thereby reducing the probability of biting between roller assembly 1072 and roller pin 1073. The roller bushing 10722 and the roller 10728 are fitted by interference, which increases the relative speed between the moving surface of the roller bushing 10722 and the roller pin 1073. The end surface of the roller bushing 10722 moves at a high speed and forms an effective dynamic pressure oil film with the roller pin 1073, thereby improving the dynamic pressure lubrication effect and reducing the probability of biting between the roller bushing 10722 and the roller pin 1073. The roller 10728 and the thrust bearing 10723 are fitted by interference. The relative speed between the moving surface of the thrust bearing 10723 and the boss 10714 is increased, and the end face of the thrust bearing 10723 moves at a high speed to form an effective dynamic pressure oil film between the boss 10714, which can prevent the boss 10714 and the thrust bearing 10723 from sticking tightly, and avoid excessive wear of the end face of the thrust bearing 10723 caused by insufficient oil supply. The formation of the dynamic pressure oil film can improve the dynamic pressure lubrication effect and reduce the possibility of biting between the thrust bearing 10723 and the boss 10714.

As shown in Figure 19, the outer surface of the roller pin 1073 is set as a cylindrical surface, and two-step waist-shaped grooves 10731 and 10732 are respectively set at two positions on the cylindrical surface. The waist-shaped grooves 10731 and 10732 are set in the middle position of the roller pin 1073; the setting of the slender waist-shaped grooves allows the lubricating oil in the waist-shaped grooves 10731 and 10732 to have a larger contact area with the corresponding friction surface, making full use of the movement speed of the corresponding moving surface, bringing more lubricating oil into the bearing surface to form a dynamic pressure oil film, and then forming a thicker lubricating oil film. The two sides of the waist-shaped groove 10731 are set as waist shapes to reduce the stress concentration caused by the grooves on the surface of the roller pin 1073. The two-step waist oil grooves 10731 and 10732 can increase the surface lubricating oil flow. A small-angle wedge-shaped groove with an angle of 5 to 10° is formed between the waist-shaped groove 10731 located on the outer layer and the outer surface of the roller bushing 10722, and oil holes 10733 and 10734 are arranged in the waist-shaped groove 10732 located on the inner layer; the angle between the two waist-shaped grooves is 70 to 120° (the actual value can be determined according to the simulation calculation results, and 90° can be selected in the example), and they are located directly above the pressure-bearing area, which ensures that the friction surface is fully supplied with oil, reduces the influence of the waist-shaped groove on the surface on the area of the pressure-bearing area, and thus makes the angle of the pressure-bearing area larger, and the pressure-bearing area The average pressure of the oil film is smaller; the outer waist-shaped groove 10731 and the corresponding friction surface form a small-angle convergent wedge to enhance the squeezing effect in dynamic pressure lubrication; the inner waist-shaped groove 10732 is mainly used to store more lubricating oil to ensure sufficient oil supply to the friction surface, and even if the oil supply is poor for a short time, it will not affect the lubrication of the roller pin surface. When the lubrication system has problems, the probability of system jamming is reduced; the two oil holes 10733 and 10734 at two positions are connected by a lubricating oil outlet channel, and the two oil holes 10733 and 10734 are set at 90°.

As shown in Figures 17, 18 and 34, the outer surface of the guide piston 1071 is set as a cylindrical surface, and a plurality of circumferential oil grooves 10729 and 10725, a first axial oil groove 10716 and a vertical groove 10717 are set on the cylindrical surface. The vertical groove 10717 is opened in the circumferential oil groove 10725, and the vertical groove 10717 is connected to the circumferential oil groove 10729 through the first axial oil groove 10716; 1-10° chamfers are set between the two sides of the circumferential oil groove 10725 and the upper and lower ends of the guide piston 1071. When moving, the chamfers and the corresponding moving surfaces form a small-angle convergent wedge to enhance the squeezing effect in dynamic pressure lubrication. Improve the surface lubrication state of the guide piston 1071, establish a thicker dynamic pressure oil film, reduce friction, and reduce the probability of sticking. According to relevant data and experiments, when the chamfer is too large (such as 45° or 90°), the chamfer cannot enhance lubrication, but has a scraping effect on the corresponding friction surface, scraping off the surface lubricating oil and reducing the lubrication effect. An inclined hole 10718 is also provided on the cylindrical surface, and the two ends of the inclined hole 10718 are respectively connected to the inner wall of the circumferential oil groove 10725 and the second mounting hole 10712. A second axial oil groove 10719 connected to the circumferential oil groove 10725 is also provided on the cylindrical surface. A first straight hole 10720 and a second straight hole 10721 connected to each other are also provided on the cylindrical surface. The first straight hole 10720 is connected to the first axial oil groove 10716, and the second straight hole 10721 is connected to the first mounting hole 10711; the first straight hole 10720 and the second straight hole 10721 supply lubricating oil to the lower spring seat assembly 106 inside the guide piston 1071, reducing the wear of the corresponding moving surface. A lubricating oil inlet passage 10735 is provided on the outer circumferential surface of the roller pin 1073 . The lubricating oil inlet passage 10735 is arranged relative to the inclined hole 10718 , and the lubricating oil inlet passage 10735 is connected to the lubricating oil outlet passage.

The outer surface of the roller pin 1073 is provided with a DLC coating; the DLC coating has high hardness, low friction coefficient, wear resistance, and high temperature resistance. When the lubrication between the roller bushing 10722 and the roller pin 1073 is poor, the friction pair composed of the DLC coating and the roller bushing 10722 of the copper alloy bearing can still operate well, which can further reduce the probability of biting between the roller pin 1073 and the roller bushing 10722; the roller bushing 10722 is made of copper alloy. The thrust bearing 10723 is made of copper alloy. Forced lubrication is adopted between the roller pin 723 and the roller bushing 10722. Forced lubrication is adopted between the thrust bearing 10723 and the boss 10714. The roller bushing 10722 and the thrust bearing 10723 are made of bronze alloy, which utilizes the low friction coefficient, good wear resistance, self-lubrication and impact resistance of the bronze alloy to improve the friction characteristics when there is solid friction between the inner hole and end face of the roller assembly 1072 and the corresponding moving surface, reduce the friction coefficient, improve impact resistance, and improve the load-bearing capacity.

As shown in Figures 15, 16 and 20, the outer circle of the upper end surface, the outer circle of the lower end surface and the circumferential ring groove 1025 of the guide piston 1071 are all provided with a first chamfer 10741; the hole wall of the first mounting hole 10711 is provided with a second chamfer 10726. The hole wall of the second mounting hole 10712 is provided with a tenth hole 10727; the outer circle surface of the roller pin 1073 is provided with an eleventh hole 10736; the spring 10737 and the stop pin 10738 are placed in the eleventh hole 10736 in sequence, and the stop pin 10738 partially extends into the tenth hole 10727. The eleventh hole 10736 is provided for installing the stop pin 10738, so that the roller pin 1073 and the guide piston 1071 are relatively stationary, reducing the number of relative motion surfaces between the roller pin 1073 and the roller 10728, thereby increasing the speed of the relative motion surfaces, and further enhancing the dynamic pressure lubrication effect (the principle is the same as the interference fit between the roller and the bushing). Specifically, when assembling the roller assembly 1072 and the roller pin 1073 onto the guide piston 1071, firstly, the roller bushing 10722 and the thrust bearing 10723 are installed onto the roller 10728 by cold installation; then, the spring 10737 and the stop pin 10738 are sequentially placed into the eleventh hole 10736 of the roller pin 1073; then, the roller assembly 1072 is placed at the lower part of the guide piston 1071, and the roller pin 1073 is sequentially passed through one side of the fourth hole at the lower end of the guide piston 1071, the inner hole of the roller assembly (specifically, the inner hole of the roller bushing), and the other side of the fourth hole at the lower end of the guide piston; then, the stop pin 10738 is pressed by hand to make its height lower than the second mounting hole 10712, and at the same time, the roller pin 1073 is pushed until the stop pin 10738 is bounced into the tenth hole 10727 of the guide piston 1071 under the action of the spring 10737. That is to say, the lubricating oil flowing out of the fuel injection pump body 101 flows into the circumferential oil groove 10725 through the second axial oil groove 10719, and then flows into the circumferential oil groove 10729 through the vertical groove 10717 and the first axial oil groove 10716, thereby realizing the lubrication between the guide piston 1071 and the fuel injection pump body 101. In addition, because the gap between the guide piston 1071 and the center hole of the pump body 101 matched therewith is very small, the lubricating oil entering the second axial oil groove 10719 and the circumferential oil groove 10725 of the guide piston 1071 is The oil maintains a certain pressure, and a lubricating oil film can be formed between the outer circle of the guide piston 1071 and the center hole of the pump body 101; at the same time, part of the lubricating oil in the second axial oil groove 10719 flows into the lubricating oil inlet pipe 735 through the inclined hole 10718, so as to penetrate into the roller pin 1073, and then flows out through the oil holes 10733 and 10734 to the outer circle surface of the roller pin 1073, deeply lubricating the roller pin 1073 and the rolling bushing 722, and forming a lubricating oil film between the roller pin 1073 and the rolling bushing 722.

The angle range of the first chamfer 10741 and the second chamfer 7100 is between 1 and 10 degrees. When the guide piston 1071 and the center hole on the pump body 101 cooperate, a small-angle convergent wedge can be formed, which enhances the extrusion effect in dynamic pressure lubrication and increases the oil film thickness on the surface of the guide piston 1071 during operation, thereby reducing the probability of biting between the guide piston 1071 and the pump body 101.

As shown in Figures 20 and 21, the lubricating oil inlet channel 10735 includes: a third radial oil channel 10739 arranged along the radial direction of the roller pin 1073 and an axial oil channel 10740 arranged along the axial direction of the roller pin 1073, the third radial oil channel 10739 is connected to the axial oil channel 10740; the axial oil channel 10740 is connected to the oil holes 10733 and 10734 in the waist-shaped groove 10732.

The above-mentioned high-pressure oil pump has the following effects:

(1) The temperature problem of the existing mechanical adjustment method can be solved by using the electronically controlled proportional valve 2 to adjust the oil inlet of heavy oil. Targetedly, a cooling circulation oil channel is set inside the electronically controlled proportional valve 2 to allow the cooling oil flowing in the pump body 101 to enter the electronically controlled proportional valve 2, and to cool the electronically controlled components in the electronically controlled proportional valve 2 in a targeted manner, so that the electronically controlled components of the electronically controlled proportional valve 2 are kept within the normal temperature range, thereby allowing the electronically controlled proportional valve 2 to be used to throttle the oil inlet of the pump. The electronically controlled proportional valve 2 overcomes the shortcomings of mechanical oil quantity adjustment, improves the accuracy, flexibility, and response speed of oil supply flow regulation, and thereby achieves a more accurate match between the pump oil supply and the diesel engine operating conditions, avoiding performance degradation due to insufficient oil supply, and also reduces excess flow during operation, thereby reducing the actual load of the pump;

(2) By adding the oil inlet valve assembly 1031, the high-pressure oil chamber 1041 of the plunger sleeve 1042 is quickly closed when the oil is switched from suction to compression, thereby ensuring the pressure stability of the relevant position in the oil inlet passage of the oil inlet valve seat 10311, and effectively preventing cavitation;

(3) A small amount of lubricating oil in the second annular groove 10422 of the plunger pair 104 can completely prevent the leakage of heavy oil, and prevent the leaked heavy oil from corroding important components such as the plunger spring 105 below the plunger sleeve 1042. In addition, the present application can effectively reduce the vertical height of the guide piston 1071 by sealing the heavy oil with a small amount of lubricating oil (no need for the longer sealing section set on the guide piston 1071 of the traditional low-speed engine), thereby reducing the vertical height of the high-pressure oil pump and reducing the overall weight of the high-pressure oil pump. According to the test, the solution of the present application reduces the vertical height of the high-pressure oil pump by 1/3.

(4) The outer spring seat 1061 is a boss-type structure that is thin on the outside and thick in the middle. During operation, the outer spring seat 1061 mainly bears the pressure transmitted from the plunger 1043 to the upper sphere 1062. The stress field caused by the pressure is distributed in a conical shape in the outer spring seat 1061. The outer spring seat 1061 is set to a corresponding boss shape, which can reduce the mass of the outer spring seat 1061 while meeting the strength requirement, thereby reducing the moving mass. The thicker part between the bosses also provides design space for the intermediate sphere and the oil channel;

(4) A spherical fit is formed between the outer spring seat 1061 and the upper sphere 1062. When a lower spring seat assembly 106 with a spherical surface is provided between the plunger 1043 and the guide piston 1071, even if there is a large parallelism error between the upper end face of the guide piston 1071 and the end face of the tail of the plunger 1043, the spherical surface can automatically adjust the angle so that the contact surface between the upper sphere 1062 and the outer spring seat 1061 maintains full contact, eliminates local contact, balances the overall force, and alleviates the tendency of excessive local stress. At the same time, the combined force passes through the center of the spherical surface, eliminates the bending moment of the attachment, thereby optimizing the dynamic characteristics and improving the bearing capacity of the system.

(5) The spherical hole 10612 provides lubricating oil to the spherical surface, lubricates the spherical surface, and uses the lubricating oil to form an elastohydrodynamic lubrication effect on the spherical surface, thereby reducing the wear rate, reducing the contact stress, reducing the micro-motion damage, and improving the bearing capacity and fatigue strength of the spherical surface;

(5) The outer surface of the outer spring seat 1061 forms a conical surface, and the lubricating oil outlet passage 10615 is opened on the outer conical surface of the outer spring seat 1061, which can prevent the plunger spring 105 from covering the flow area of the lubricating oil outlet passage 10615, so that the flow area is not affected by the position of the plunger spring 105;

(6) The inner spring seat 1063 is provided with a guide cone 10637, which can improve the centering property. Even in the event of a collision, the inner spring seat 1063 and the upper sphere 1062 can be automatically aligned, thereby improving the tendency of uneven force.

(7) The connecting hole 10713 is arranged inside the guide piston 1071, so that the lubricating oil above the guide piston 1071 is evenly distributed in the middle above the second mounting hole 10712 of the roller 10728 when it flows down from the connecting hole 10713, and the lubricating oil is evenly distributed on the roller generatrix, and the distribution of the lubricating oil on the surface of the roller 10728 is not affected by the positive and negative rotation (it can be evenly distributed); the vertical force distribution of the guide piston is improved, that is, the pressure of the plunger 1043 is distributed to the thicker position around the connecting hole 10713, so that the overall force is balanced, the maximum stress is reduced, and the reliability of the system bearing capacity is improved; when the pump is assembled, when the guide piston 1071 and the outer spring seat 1061 are matched, the lubricating oil outlet oil channel 10615 of the outer spring seat 1061 is connected to the lubricating oil leaked from the top of the plunger pair 104, which can avoid the spring blocking the oil hole and increase the lubricating oil flow area;

(8) The first radial oil groove 10715 opened on the boss 10714 is filled with lubricating oil to provide sufficient lubricating oil for the moving surface (end face of the roller assembly). The end face movement speed of the roller 10728 is used to form a dynamic pressure oil film on the end face of the roller 10728, which separates the boss 10714 of the guide piston 1071 and the end face of the roller assembly 1072, thereby reducing wear and lowering the friction coefficient. The first radial oil groove 10715 is opened on the boss 10714 of the guide piston 1071, which is different from the first radial oil groove 10715 opened on the roller assembly 1072. The guide piston 1071 will not rotate relatively, and the high and low pressure oil film areas on the friction surface are relatively static, so the roller assembly 1072 is relatively static in the axial direction;

(9) The two-step waist-shaped grooves 10731 and 10732 provided in the roller pin 1073 have an included angle of 70 to 120° and are located directly above the pressure-bearing area. This reduces the effect of the waist-shaped grooves on the pressure-bearing area while ensuring sufficient oil supply to the friction surface, thereby making the angle of the pressure-bearing area larger and the average oil film pressure in the pressure-bearing area smaller. The outer waist-shaped groove 10731 and the corresponding friction surface form a small-angle convergent wedge to enhance the squeezing effect in dynamic lubrication. The inner waist-shaped groove 10732 is mainly used to store more lubricating oil to ensure sufficient oil supply to the friction surface. Even if the oil supply is poor for a short period of time, it will not affect the lubrication of the roller pin surface. When there is a problem with the lubrication system, the probability of system jamming is reduced.

24 and 25, the low-speed engine integral common rail of the present invention is suitable for working at a temperature of 200°C and a pressure of 150MPa, and has low-pressure circulation function as well as pressure limiting and pressure maintaining functions. It mainly includes common rail pipe 12, flow limiting valve assembly 13, oil inlet end cover 121, end cover 122, circulation valve assembly 16, pressure limiting valve assembly 18, sensor mounting seat 127, sensor 124, flow limiting valve mounting seat 125, bracket 126 and other parts. The common rail pipe 12 adopts a cylindrical structure, and a plurality of first cutouts 1203 are arranged on one side of the outer circle of the common rail pipe 12, and the plurality of first cutouts 1203 are respectively used to install the flow limiting valve assembly 13, the sensor mounting seat 127, and the pressure limiting valve assembly 18. On the common rail pipe 12, a second cutout 1204 is arranged on the other side opposite to the first cutout 1203, and the second cutout 1204 is used to install the bracket 126. At the same time, end covers 122 and an oil inlet end cover 121 are installed on both sides of the common rail pipe 12 .

First, the low-speed engine integral common rail uses two waist-shaped holes set on the bracket 126 to install the bolt 128. The bolt 128 is fixed to the whole machine by passing through the waist-shaped holes to achieve the installation of the low-speed engine integral common rail. In addition, considering that the number of engine cylinders of the low-speed diesel engine is large, the number of corresponding brackets 126 is large, and waist-shaped holes are set on each bracket 126 to facilitate the installation and adjustment between the brackets 126 to prevent interference. At the same time, the bracket 126 is fixed to the common rail pipe 12 by four screws 129, and cylindrical pins are installed on them to facilitate the positioning of the common rail pipe 1.

The common rail pipe 12 in this embodiment adopts an integral structure, and an oil inlet pipe 1201 running through both ends is arranged inside the common rail pipe 12, which is convenient for processing on both sides of the common rail pipe 12, reducing the processing difficulty, and the end cover 122 and the oil inlet end cover 121 for sealing the common rail pipe 12 are installed on both sides. At the same time, the end cover 122 and the oil inlet end cover 121 are respectively sealed with the common rail pipe 12 in the form of a cone surface, and bolts are used to fix the end cover 122 and the common rail pipe 12, and the oil inlet end cover 121 and the common rail pipe 12, which can improve the sealing performance.

The low-speed engine integral common rail of the present invention has the functions of limiting pressure and maintaining pressure. A pressure limiting valve assembly 18 is installed on the first cutout 1203 provided in the common rail pipe 12. When the pressure in the oil inlet pipeline 1201 of the common rail pipe 12 exceeds the limiting pressure of the pressure limiting valve assembly 18, the pressure limiting valve assembly 18 overcomes the preload force of the second pressure regulating spring 185 inside and opens. Through the self-adjusting function, when the pressure limiting valve assembly 185 is stable, the rail pressure is maintained at a certain pressure value. It can ensure that the diesel engine runs at a low speed and low torque state.

Furthermore, considering that the low-speed engine integrated common rail fuel medium of the present invention uses low-quality fuel, in order to prevent the fuel in the low-speed engine common rail from solidifying after the diesel engine is stopped, a gas-controlled circulating valve assembly 16 is installed on the end cover 122. The circulating valve assembly 16 includes a first valve core 161, a first valve body 162, a gland 167, and a first pressure regulating spring 169 and other parts. The gland 167 is fixed to the first valve body 162 by a screw 1632. After the engine is stopped, the oil inlet pipe of the common rail pipe 12 is The rail pressure in the circulation valve assembly 1201 is reduced to a value lower than the spring force of the first pressure regulating spring 169, and the spring force pushes the first valve core 161 to move downward. When the first valve core 161 moves to the lower dead center, the conical seal between the first valve core 161 and the first valve body 162 in the circulation valve assembly 16 is released, and the heavy oil in the oil inlet pipeline 1201 of the common rail pipe 12 can flow back to the fuel tank through the first oil return channel 1605, the second oil return channel 1606 and the third oil return channel 1607, so as to realize fuel circulation. When the engine is just started, the air inlet 1630 on the circulation valve assembly 16 is introduced with compressed air. After the compressed air enters the first cavity, the first valve core 162 is pushed to move toward the upper dead center under the action of the compressed air. When the first valve core 162 moves upward to the upper dead center, a conical seal is formed between the first valve core 162 and the first valve body 161, so that the rail pressure in the common rail pipe 12 can be established.

The low-speed engine integral common rail of the present invention is used in the high-pressure common rail system of the diesel engine. During operation, the common rail pipe 12 is always in a high-pressure state. In order to ensure the safety of personnel and the diesel engine, a sensor 124 is installed on the common rail pipe 12 to detect the pressure in the oil inlet pipe 1201 in the common rail pipe 12 for real-time monitoring. In order to ensure its accuracy, two sensors 124 are set to back up each other.

In addition, a flow limiting valve assembly 13 is arranged between the common rail pipe 12 and the electronically controlled fuel injector 15. The flow limiting valve assembly 13 mainly includes parts such as a second valve core 133, a valve seat 131, a second valve body 132, and a second pressure regulating spring 135. When the high-pressure oil pipe between the flow limiting valve assembly 13 and the electronically controlled fuel injector 15 is broken or the electronically controlled fuel injector 15 sprays excessive fuel, the second valve core 133 in the flow limiting valve assembly 13 overcomes the spring force of the second pressure regulating spring 135 through the pressure difference and fits into the second valve body 132, thereby blocking the high-pressure fuel in the oil inlet pipe 1201 of the common rail pipe 12 from flowing into the electronically controlled fuel injector 15.

In addition, since the common rail of the present application works under high temperature, high pressure and low quality fuel conditions, considering that high pressure fuel may leak from the high pressure sealing surfaces of the common rail pipe 12 and various components, causing environmental pollution and endangering the personal safety of workers, an oil return hole is provided at each high pressure seal to collect the return oil. Specifically, an oil return pipe 1202 is provided in the common rail pipe 12, and the oil return pipe 1202 is connected to the first incision 1203, and is used to collect the return oil leaked from the high pressure seal of the common rail pipe 12, the flow limiting valve assembly 13 and the pressure limiting valve assembly 18.

Furthermore, the flow limiting valve assembly 13 is installed at one of the first cutouts 1203 through the flow limiting valve mounting seat 125, the pressure limiting valve assembly 18 is installed at one of the first cutouts 1203 through the pressure limiting valve mounting seat 123, and the sensor 124 is installed at one of the first cutouts 1203 through the sensor mounting seat 127. A sealing ring is provided on each of the flow limiting valve mounting seat 125, the pressure limiting valve mounting seat 123 and the sensor mounting seat 127 to prevent fuel leakage. Similar to the installation principle of the pressure limiting valve assembly 18, the sensor mounting seat 127 and the flow limiting valve mounting seat 125 are first fixed on the common rail pipe 1 by screw fixing, and then the sensor 124 and the flow limiting valve assembly 13 are installed by screw fixing.

Specifically, referring to Figures 26, 27 and 28, the circulation valve assembly 16 includes: a first valve body 161 fixed on the end cover 122, a first valve core 162, a nut 1614, a lower spring seat 164, a sealing ring, a gland 167 and an oil return joint 168. The first valve body 161 is provided with an axial center hole and two first oil return passages 1605, the axial center hole is communicated with the oil inlet pipeline 1201 in the common rail pipe 12, and the high-pressure fuel in the oil inlet pipeline 1201 in the common rail pipe 12 can enter the axial through hole of the circulation valve assembly 16, two first sealing ring grooves 1620 are provided at the position where the two first oil return passages 1605 are provided on the top of the first valve body 161, and the first valve body 161 is also provided with a first air inlet passage 1608 communicated with the axial center hole, a second sealing ring groove 1622 is provided in the circumference of the first air inlet passage 1608, and a second sealing ring 1631 for improving the sealing effect is installed in the second sealing ring groove 1622. The first valve core 162 is arranged in the axial center hole of the first valve body 161, and a first sealing cone surface 1611 is arranged on the top of the first valve core 162, and an external thread 1612 is also arranged on the upper part of the first sealing cone surface 1611; the lower spring seat 164 passes through the external thread 1612 and is sleeved on the first sealing cone surface 1611, and a second sealing cone surface 1613 matching the first sealing cone surface 1611 is arranged on the lower part of the lower spring seat 164. The nut 1614 is sleeved on the external thread 1612 and presses the lower spring seat 164. The first pressure regulating spring 169 is sleeved on the nut 1614 and fixed on the lower spring seat 164. The gland 167 is arranged on the top of the first valve body 161, and is provided with two second oil return passages 1606 connected with the two first oil return passages 1605, and is also provided with a threaded hole 1603 for installing the oil return joint 168 in the middle thereof, and a first sealing plane 1615 is provided at the orifice of the threaded hole 1603, and a second air inlet 1629 connected with the first air inlet 1608 is provided on the bottom surface of the gland 167, and an air inlet 1630 is arranged in the circumference thereof, and the air inlet 1630 is connected with the second air inlet 1629. The oil return joint 168 is arranged in the threaded hole 1603, and is provided with a second sealing plane 1616 matched with the first sealing plane 1615.

As shown in Figures 28 and 29, when compressed air is initially introduced into the air inlet 1630, the first valve core 162 moves upward, and the lift H2 of the bottom end surface of the first valve body 161 and the bottom end surface of the first valve core 162 is at the maximum lift. At this time, there is no return oil in the first oil return channel 1605. When the oil inlet pressure at the bottom of the first valve core 162 is lower than the opening pressure of the first pressure regulating spring 169, the first valve core 162 moves downward under the spring force of the first pressure regulating spring 169. At this time, the lift H2 of the bottom end surface of the first valve body 161 and the bottom end surface of the first valve core 162 is 0, and the first oil return channel 1605 starts to return oil, realizing the circulation of low-pressure fuel, and the high-pressure heavy oil in the common rail pipe 12 flows back to the fuel tank through the first oil return channel 1605, the second oil return channel 1606 and the third oil return channel 1607.

Specifically, the axial center hole of the first valve body 161 includes: a first center hole 1601 matched with the outer circle of the first valve core 162, and a third sealing ring groove 163 is provided on the hole wall of the first center hole 1601 for installing the third sealing ring 1624. In the present application, based on the above principle, it can be determined that before the air is introduced into the circulation valve assembly 16, the first valve core 162 moves downward to the lower dead center position under the action of the first pressure regulating spring 169, at which time, no sealing relationship is established between the first valve core 162 and the first valve body 161; at the initial moment when the engine is just started, the speed of the high-pressure oil pump is low, and the flow rate of the high-pressure fuel pumped out by the high-pressure oil pump into the common rail pipe 1 is small. The reason why no conical seal is formed between the first valve core 162 and the first valve body 161 will cause the pressure in the oil inlet pipe 1201 of the common rail pipe 1 to fail to be quickly established. Therefore, in order to quickly build up the pressure in the common rail pipe 12, it is necessary to form a conical seal between the first valve core 162 and the first valve body 161, that is, it is necessary to realize the positive (upward) movement of the first valve core 162. At this time, the first valve core 162 needs to be subjected to an external positive force. In this example, compressed air is used as the power source of the external positive force. Specifically, a closed volume chamber (first cavity) needs to be designed on the first valve body 161 to carry compressed air. As shown in Figure 29, a first sealing cone surface 1611 and an external thread 1612 are provided on the first valve core 162, on which a lower spring seat 164, a nut 1614 and a first pressure regulating spring 169 are installed in sequence. The lower spring seat 164 and the first center hole 1601 of the first valve body 161 form a first cavity for carrying compressed air. When the compressed air pressure is sufficiently greater than the preload of the first pressure-regulating spring 169, the first valve core 162 moves upward. At this time, the lift H2 of the bottom end surface of the first valve body 161 and the bottom end surface of the first valve core 162 are at the maximum value, and there is no return oil in the first oil return channel 1605. When the fuel pressure at the bottom of the first valve core 162 is large enough, the compressed air is stopped from being introduced. At this time, the lift H2 of the first valve core 162 is mainly maintained by the oil inlet pressure.

In order to enable the first cavity to form a closed volume cavity, a third sealing ring 1624 is installed on the third sealing ring groove 163 provided on the first central hole 1601 matched with the outer circle of the first valve core 162 to prevent the compressed air from leaking to the first oil return passage 1605. Similarly, a fourth sealing ring groove 1625 for installing a fourth sealing ring 1627 is provided on the matching wall of the lower spring seat 164 and the axial central hole. In addition, a second sealing cone surface 1613 is provided at the lower part of the lower spring seat 164 to match the first sealing cone surface 1611 to prevent the compressed air from leaking.

In the present application, compressed air enters the first cavity through the air inlet 1630 , the second air inlet duct 1629 , and the first air inlet duct 1608 . In order to prevent air leakage, a first sealing ring 1628 is provided at the junction of the first air inlet duct 1608 and the second air inlet duct 1629 .

As shown in Figures 28 and 29, after compressed air is introduced into the first cavity, the lower spring seat 164 moves forward. In order to ensure that the lower spring seat 164 moves forward together with the first valve core 162, the lower spring seat 164 is pressed against the first valve core 162 by the nut 1614 to form a whole. In addition, when the lower spring seat 164 passes through the external thread 1612 of the first valve core 162, the second sealing cone surface 1613 on the lower spring seat 164 is prevented from colliding with the external thread 1612. The diameter of the fourth center hole 1618 on the lower spring seat 164 must be larger than the outer diameter of the external thread 1612.

The first valve core 162 reduces movement resistance during forward movement, and the air outlet 1623 and the third center hole 1617 on the lower spring seat 164 are connected to the second cavity formed by the second center hole 1602 on the first valve body 161 for exhausting air in the second cavity.

In addition, considering that the matching portion 1626 of the lower spring seat 164 is installed with the fourth sealing ring 1627, the lower spring seat 164 is easy to install when it is installed into the second center hole 1602 of the valve body 1 without damaging the fourth sealing ring 1627. A guide portion 1619 is provided at the orifice of the second center hole 1602, and the full angle of the guide portion 1619 is generally set to 30°~40°.

As shown in Figure 25, a first sealing ring groove 1620 is set at the junction of the first oil return channel 1605 and the second oil return channel 1606 for installing the first sealing ring 1628 to prevent leakage of low-pressure fuel. Similarly, in order to prevent leakage of fuel between the return oil joint 168 and the pressure cover 167, a second sealing plane 1616 is set on the return oil joint 168 to cooperate with the first sealing plane 1615 on the pressure cover 167.

The threaded hole 1603 provided on the pressure cap 167 and the bottom surface of the oil return joint 168 form a third cavity. The third cavity is connected to the third oil return passage 1607 (the third oil return passage 1607 is connected to the fuel tank through a pipeline) and the second oil return passage 1606 provided on the oil return joint 168. The flow area of the third cavity is greater than the flow area of the second oil return passage 1606, so that the fuel can be discharged in time.

When the engine is stopped, when the fuel pressure at the bottom of the first valve core 162 (i.e., the fuel pressure in the oil inlet pipe 1201 of the common rail pipe 12) drops to the opening pressure of the first pressure regulating spring 169, the first valve core 162 moves in the opposite direction. At this time, H2 is 0. Since H1 is set greater than H2, the lower spring seat 164 will not collide with the second center hole 1602. At this time, the first cavity has a certain volume, so that when compressed air is introduced into the first cavity when the engine is started, the first valve core 162 can move forward quickly, and the fuel pressure at the bottom of the first valve core 162 can be quickly built up.

The circulation valve assembly 16 is used in a low-speed diesel engine high-pressure common rail system, and its fuel medium is low-quality fuel. In order to ensure the life and functional reliability of the flow limiting valve, the first valve core 162 is made of high-speed tool steel material, with DLC plating, and the first valve body 161 is made of high-strength structural steel, nitriding treatment, and the use of such materials and heat treatment methods ensures that the circulation valve can withstand high temperatures and corrosion.

The circulation valve assembly 16 used for the common rail pipe 12 is installed on the high-pressure common rail pipe 12. Its principle mainly utilizes the elastic force of compressed air and the first pressure-adjusting spring 169 to realize the upward and downward pushing of the first valve core 162. When compressed air is introduced into the air inlet 1630, the first valve core 162 and the lower spring seat 164 are connected as a whole through the nut 1614 under the action of air pressure and move upward. At this time, H2 is at its maximum value, and there is no return oil in the first oil return channel 1605. The fuel at the bottom of the first valve core 162 builds pressure during the movement of the high-pressure oil pump. When the fuel pressure reaches a certain level, the compressed air is cut off. At this time, H2 is at its maximum value mainly maintained by the pressure on the common rail pipe 12. When the engine is stopped and the pressure in the common rail pipe 12 drops to a level lower than the spring force of the first pressure regulating spring 169, the first valve core 162 is pushed in the opposite direction. At this time, the low-pressure fuel enters the first oil return channel 1605, and then flows into the fuel tank from the second oil return channel 1606 and the third oil return channel 1607 in sequence, thus achieving a fuel circulation effect, avoiding fuel solidification, and preventing parts from being corroded.

Specifically, referring to FIG. 32 and FIG. 33 , the pressure limiting valve assembly 18 in this embodiment includes: a third valve body 181, a third valve core 182, a second O-ring 183, a bolt 184, a third pressure regulating spring 185, a fuel pipe joint 186, and a pressure regulating gasket 187. The third valve core 182 is installed in the fourth-level hole 18105 in the third valve body 181, and the second cone angle 202 of the third valve core 182 is pressed against the sealing seat surface 18103 (referring to the hole wall of the second-level hole 18102) of the third valve body 181. The third valve core 182 is pressed by the fuel pipe joint 186 and the third pressure regulating spring 185. A sealing ring groove is provided at the lower part of the fuel pipe joint 186, and a second O-ring 183 is installed in the sealing ring groove to improve the sealing effect and prevent fuel leakage. The middle of the oil pipe joint 186 is provided with multi-stage countersunk holes 18601 (first countersunk hole) and 28602 (second countersunk hole) and an oil outlet hole 18603, and the upper outer circle is provided with threads. The oil pipe joint 186 is installed on the third valve body 181 by bolts 184. The pressure regulating gasket 187 and the third pressure regulating spring 185 are installed in the second countersunk hole 18602 in the middle of the oil pipe joint 186.

Furthermore, the hole in the third valve body 181 is designed with multiple holes 18101 (first-level hole), 18102 (second-level hole), 18104 (third-level hole) and 18105 (fourth-level hole), wherein the second-level hole 18102 is a throttling hole, and the first-level hole 18101 is larger than the second-level hole 18102, so as to reduce the depth of the throttling hole and reduce the difficulty of processing. The angle between the second-level hole 18102 and the first-level hole 18101 (or the third-level hole 18104) of the third valve body 181 is set to 59° (equivalent to the sealing seat surface 18103 of the third valve body being set to 59°), so as to ensure that it is sealed within a deviation of 1° with the second cone angle 18202 of the third valve core 182, and the sealing performance is good. The aperture of the third-level hole 18104 of the third valve body 181 is set larger than the apertures of the second-level hole 18102 and the fourth-level hole 18105, and is used to store fuel pressure. The aperture of the fourth-stage hole 18105 of the third valve body 181 is set to If the aperture of the fourth-stage hole 18105 is too small, the processing is difficult and the accuracy cannot be guaranteed; if the aperture of the fourth-stage hole 18105 is too large, the depth of the fourth-stage hole 18105 will increase due to the length required for mutual coordination with the third valve core 182, which will increase the processing difficulty of the sealing seat surface 18103, making its accuracy unable to be guaranteed, and will also cause measurement difficulties. The third valve body 181 is made of high-strength structural steel material and is nitrided. By selecting high-strength materials, the third valve body 181 is ensured to be resistant to high pressure. Through nitriding, the third valve body 181 can work in a low-speed engine heavy oil environment and is corrosion-resistant.

Referring to FIG. 33 , the head of the third valve core 182 is set to two cone angles (a first cone angle 18201 and a second cone angle 18202). The first cone angle 18201 is set to an obtuse angle of 120°, which increases the reliability of the third valve core 182 on the one hand, and increases the flow area of the head of the third valve core 182 on the other hand, thereby reducing the generation of cavitation. The second cone angle 18202 of the third valve core 182 is set to an acute angle of 60°. In order to ensure good sealing performance, the cone angle of the third valve core 182 is generally set to 60° and 90°. Considering that under the same flow area, the needle valve has a smaller lift at 60° than at 90°, which reduces the design difficulty of the third pressure regulating spring 185.

Referring to Fig. 33, two symmetrical second flats 18203 are milled on the third outer circle 18204 in the middle of the third valve core 182. The flow area of the second flats 18203 is slightly larger than the flow area of the second-stage hole 18102 on the third valve body 181. A second gap for fuel to pass through is formed between the second flats 18203 of the third valve core 182 and the fourth-stage hole 18105. The area of fuel that can flow in the second gap is larger than the fuel flow area in the second-stage hole 18102. As shown in Fig. 33, the second small outer circle 18206 on the upper part of the third valve core 182 is used to position the third pressure regulating spring 185. The third pressure regulating spring 185 is sleeved on the small second outer circle 18206.

The third valve core 182 is made of high-speed tool steel. The third outer circle 18204 on the third valve core 182 that matches the fourth-level hole 18105 of the third valve body 1 is plated with a DLC layer to ensure the strength requirements of the third valve core 182 and corrosion resistance in a heavy oil environment. The plating can also make the third valve core 182 more wear-resistant.

Further, referring to FIG. 32 , the third valve core 182 and the third valve body 181 are provided with a travel limit h1 to ensure that the third valve core 182 moves within a certain range, otherwise the third pressure regulating spring 185 will be compressed and unable to be reset.

Further, referring to Figure 32, an overlapping area h is set between the third valve core 182 and the third valve body 181. In the process from opening to closing of the third valve core 182, at the moment when the third valve core 182 and the third valve body 181 generate the overlapping area h, the fuel cannot flow out through the second flat 18203, and pressure is formed in the third-level hole 18104, which generates a force opposite to the direction of movement on the third valve core 182, thereby reducing the impact force of the third valve core 182 on the sealing seat surface 18103 of the third valve body 181, thereby ensuring the service life of the third valve body 181 and the third valve core 182.

As for the flow limiting valve 18, its working principle is as follows: the pressure limiting valve assembly 18 is used in the high-pressure common rail fuel injection system of a low-speed marine diesel engine, and can work under a high pressure of 150 MPa and a high temperature of 200°C. As a security component of the common rail system, the pressure limiting valve assembly 18 is usually in a non-working state, so it is also called a pressure safety valve. When the rail pressure control of the oil inlet pipeline 1201 of the common rail pipe 12 is abnormal and causes the pressure to exceed the opening pressure _PL of the pressure limiting valve assembly 18, the pressure limiting valve assembly 18 opens to release the pressure. Specifically, the third valve core 182 enters the first-stage hole 18101 under the oil pressure of the high-pressure fuel provided in the oil inlet pipeline 1201 of the common rail pipe 12, and then enters the second-stage hole 18102, further pushing the third valve core 182 to move upward to release the seal between the third valve core 182 and the third valve body 181. The third valve core 182 moves upward under the action of oil pressure until the conical surface seal between the second cone angle 18202 and the sealing seat surface 18103 is released, and the high-pressure fuel part in the oil inlet pipe 1201 of the common rail pipe 12 passes through the first-stage hole 18101, the second-stage hole 18102, the third-stage hole 18104, the fourth-stage hole 18105, the groove 18205, the first counterbore 18601 and the second counterbore 18602, and finally enters the oil return pipe from the oil outlet hole 18603, and finally returns to the fuel tank, so that the pressure in the oil inlet pipe 1201 of the common rail pipe 12 is reduced. After the third valve core 182 is opened, the pressure in the oil inlet pipe 1201 of the common rail pipe 12 is reduced, so that the oil inlet amount of the fuel system (the amount of oil pumped into the common rail pipe 12 by the high-pressure oil pump) and the oil outlet amount through the pressure limiting valve assembly 18 gradually reach a stable state, and the system pressure gradually approaches the stable pressure Ps, ensuring that the diesel engine limps back to the port in a fault mode under the stable pressure Ps. Only when the common rail pressure drops to a certain level, the pressure limiting valve assembly 18 is closed (lower than the opening pressure).

In this embodiment, the limiting valve assembly 13 is installed between the common rail pipe 12 and the electronic fuel injector 15. When the high-pressure oil pipe leaks or the electronic fuel injector 15 leaks and sprays abnormally, it can cut off the fuel supply to the electronic fuel injector 15 to prevent fire, explosion and personnel safety problems.

As shown in Figures 30 and 31, the flow limiting valve assembly 13 specifically includes: a valve seat 131, a first flat 13104 for returning oil is arranged on its large outer circle, a first oil inlet hole 13101 is arranged in the middle, the first oil inlet hole 13101 is communicated with the oil inlet pipeline 1201 of the common rail pipe 12, and a fifth sealing cone surface 13102 is arranged at the bottom; a second valve body 132, a small end surface 13201 of which is fixed to the large end surface 13105 of the valve seat 131, and a second axial through hole 13101 is arranged in the axial direction. 3209, a second axial through hole 13209 passes through the upper and lower end surfaces thereof, and the valve seat 131 is partially press-fitted into the second axial through hole 13209 by press-fitting; a second valve core 133 passes through the second axial through hole 13209 and is fixed to the upper end surface of the first small outer circle 13106 of the valve seat 131, and the second valve core 133 is provided with an axial blind hole 13302 communicating with the first oil inlet hole 13101 and four transverse throttle holes 13302 communicating with the axial blind hole 13302. 04, the upper part of the second valve core 133 is provided with a third sealing cone surface 13305 and a fourth sealing cone surface 13306; the second valve body 132 has four fourth oil return passages 13210 connected with the first flat 13104, the second valve body 132 is provided with a first sealing seat surface 13206 matched with the third sealing cone surface 13305, and the position near the fifth sealing seat surface 6206 is provided with an oil outlet hole 6207 and a second sealing seat surface 13208 in sequence; the second valve body 132 has A first matching portion 13203 matching with the first small outer circle 13106 of the valve seat 131 and a second matching portion 13204 matching with the first outer circle 13301 of the second valve core 133; a cavity is formed between the second matching portion 13204 and the second valve core 133, and the cavity connects the transverse throttling hole 13304 with the axial blind hole 13302; a second pressure regulating spring 135 is inserted into the cavity and fixed to the upper end surface of the first outer circle 13301 of the second valve core 133.

In this embodiment, the second axial through hole 13209 includes a first hole, a second hole, a third hole 13205, a fourth hole 13207, a fifth hole and a sixth hole which are connected in sequence from top to bottom; the valve seat 131 is partially pressed into the first hole; the second valve core 133 is assembled in the second hole, and the upper part of the second valve core 133 and the upper part of the second hole form a cavity; the hole wall of the third hole 13205 forms a third sealing cone surface 13305; the hole wall of the fifth hole is formed with a second sealing seat surface 13208 for forming a seal with the oil inlet end of the oil pipe of the electronically controlled injector 15; the aperture of the sixth hole is larger than the apertures of the first hole, the second hole, the third hole 13205, the fourth hole 13207 and the fifth hole.

The fourth hole 13207 serves as an oil outlet hole. When the first sealing seat surface 13206 and the third sealing cone surface 13305 are released from sealing, the fuel in the first oil inlet hole 13101 flows out to the fourth hole 13207 and further flows out.

When the oil inlet pressure of the transverse throttle hole 13304 on the side of the axial blind hole 13302 exceeds a certain value of the cavity pressure, the second valve core 133 moves upward under the action of the oil inlet pressure, and the third sealing cone surface 13305 contacts the first sealing seat surface 13206 to form a cone seal, thereby blocking the fuel from entering the oil outlet hole.

Specifically, as shown in Figure 29, the second valve core 133 has a third sealing cone surface 13305, and the second valve body 132 has a first sealing seat surface 13206 that can form a cone surface seal with the third sealing cone surface 13305. When the oil inlet pressure of the transverse throttle hole 13304 on the side of the axial blind hole 13302 exceeds a certain value of the cavity pressure, the third sealing cone surface 13305 and the first sealing seat surface 13206 form a cone surface sealing relationship to block the fuel from entering the oil outlet hole 6207; conversely, when the oil inlet pressure of the transverse throttle hole 136304 on the side of the axial blind hole 13302 does not exceed a certain value of the cavity pressure, the third sealing cone surface 13305 and the first sealing seat surface 13206 release the cone surface seal. For the fourth sealing cone surface 13306, when the second valve core 133 moves upward under the oil pressure of the oil inlet pressure, the fourth sealing cone surface 13306 first contacts the first sealing seat surface 13206, but there is a gap between the fifth sealing seat surface 6305 and the first sealing seat surface 13206, and a certain amount of fuel can be filled in the gap to form a moving buffer for the rapid movement of the second valve core 133, thereby preventing the second valve core 133 from moving too fast and causing a large impact with the second valve body 132.

As shown in FIG. 25 , the flow limiting valve assembly 13 is installed on the common rail pipe 12 through the flow limiting valve mounting seat 125, and the flow limiting valve mounting seat 125 is fixed on the common rail pipe 12 by screws; a screw mounting hole 13211 is designed on the second valve body 132, and the second valve body 132 of the flow limiting valve assembly 13 is fixed on the flow limiting valve mounting seat 125 by screws passing through the screw mounting hole 13211, and an oil hole connected to the first oil inlet hole 13101 is provided on the flow limiting valve mounting seat 125, so that the high-pressure fuel in the oil inlet pipeline 1201 of the high-pressure common rail pipe 12 can enter the first oil inlet hole 13101. A fifth sealing cone surface 13102 is designed on the valve seat 131, which is used for the high-pressure fuel sealing between the flow limiting valve assembly 13 and the high-pressure common rail pipe 12. A second sealing seat surface 13208 is designed on the second valve body 132, which is used for the cone surface sealing connection between the flow limiting valve assembly 13 and the oil pipe of the electronically controlled fuel injector 15.

As shown in Figure 30, a sealing ring groove is provided on the outer surface of the second valve body 132 for installing the first O-ring 136, wherein the first O-ring 136 arranged on the outer surface of the second valve body 132 is to enhance the sealing performance between the second valve body 132 and the external component when the second valve body 132 is assembled into the external component.

As shown in Figure 30, a first flat 13104 is provided on the valve seat 131, and the first flat 13104 is connected to the four fourth oil return channels 13210, and is used to collect fuel leaked from the fifth sealing cone surface 13102, the large end surface 13105 and the small end surface 6202 of the valve seat 131, and the second sealing seat surface 13208 of the second valve body 132.

As shown in FIG. 30 , in order to ensure the seal between the small end face 13201 of the second valve body 132 and the large end face 13105 of the valve seat 131 , a large bevel 13202 is provided to reduce the contact area between the large end face 13105 and the small end face 13201 and enhance the sealing performance.

To facilitate the installation of the limiting valve assembly 13 on the high pressure common rail, the diameter of the first small outer circle 13106 of the valve seat 131 is the same as the diameter of the first matching portion 13203 of the second valve body 132, and a transitional matching method is adopted. A sink groove 13103 is provided at the intersection of the large end surface 13105 and the first small outer circle 13106.

As shown in Figure 30, in order to realize the function of the flow limiting valve, four transverse throttling holes 13304 are set on the second valve core 133, and the area of the four throttling holes is smaller than the area of the axial blind hole 13302, the area of the fourth hole (oil outlet hole) 6207, and the flow area formed by the fourth sealing cone surface 13306 and the first sealing seat surface 13206.

As shown in Figure 30, the fourth sealing cone surface 13306 of the second valve core 133 is arranged at the tail of the second valve core 133, close to the third sealing cone surface 13305, and the angle of the fourth sealing cone surface 13306 is greater than that of the third sealing cone surface 13305, thereby increasing the flow area between the fourth sealing cone surface 13306 and the first sealing seat surface 13206.

In order to prevent the fuel from leaking from the cavity formed between the second valve core 133 and the second matching part 13204 to the first matching part 13203, the gap between the first outer circle 13301 and the second matching part 13204 is as small as possible, but not too small, which will cause the operation of the second valve core 133 to be blocked and the flow limiting valve function to fail.

The flow limiting valve assembly 13 is used in a low-speed diesel engine high-pressure common rail system, and its combustion medium is low-quality fuel. In order to ensure the life and functional reliability of the flow limiting valve, the second valve core 133 is made of high-speed tool steel, and the matching section (the first outer circle 13301, the second outer circle 13303, the third sealing cone surface 13305 and the fourth sealing cone surface 13306) with the second valve body 132 is plated with DLC. The second valve body 132 is made of high-strength structural steel and nitrided. The use of such materials and heat treatment methods ensures that the flow limiting valve can withstand high temperatures and corrosion.

The fuel inlet pressure and the elastic force of the second pressure-adjusting spring 135 are used to realize the positive push on the second valve core 133. When the second valve core 133 is pushed positively, the second valve core 133 will seal the fourth hole 13207 serving as the oil outlet to block the entry of fuel. This realizes the fuel cut-off, avoids overspray of the electronically controlled injector 15, or leakage of the high-pressure oil pipe, prevents injuries to the diesel engine or personnel, and prevents environmental pollution.

Claims (24)

1. The utility model provides a low-speed machine high pressure common rail system with multiple security function which characterized in that includes: the ECU has a function of controlling the operation of the electronic device,

The electronic control high-pressure oil pump (1) is internally provided with an electronic control proportional valve (2), and the electronic control proportional valve (2) is used for adjusting the oil inlet proportion of low-pressure heavy oil entering the electronic control high-pressure oil pump (1) from an oil tank of a low-speed machine according to a first instruction of an ECU;

A first distribution block (6) connected with the electric control high-pressure oil pump (1) through a first high-pressure oil pipe (3);

a second distribution block (9) connected to the first distribution block (6) by a second high-pressure oil pipe (8);

A common rail pipe (12) connected to the second distribution block (9) through a third high-pressure oil pipe (10);

the common rail pipe (12) is provided with a sensor (17) for detecting the fuel pressure of high-pressure heavy oil of the common rail pipe (12), and the sensor (17) is connected with the ECU;

a plurality of flow limiting valve assemblies (13) are arranged on the common rail pipe (12), and each flow limiting valve assembly (13) is connected with an electric control fuel injector (15) through a fourth high-pressure fuel pipe (14); -said restrictor valve assembly (13) being adapted to close when the fuel pressure difference between said fourth high pressure conduit (14) and said common rail conduit (12) exceeds a set pressure difference;

The pressure limiting valve assembly (18) is further arranged on the common rail pipe (12), and the pressure limiting valve assembly (18) is used for opening when the fuel pressure in the common rail pipe (12) exceeds a first set pressure value, so that the fuel pressure in the common rail pipe (12) is stabilized to a target pressure value;

The first distribution block (6) is provided with a shut-off valve assembly (5) and a safety valve assembly (7); the cut-off valve assembly (5) is used for performing pressure relief treatment according to a second instruction of the ECU; the safety valve assembly (7) is used for opening when the shut-off valve assembly (5) and the pressure limiting valve assembly (18) fail and the fuel pressure in the common rail pipe (12) exceeds a second set pressure value;

And the common rail pipe (12) and the electric control oil injector (15) are also provided with a circulating valve assembly (16), and the circulating valve assembly (16) is used for being opened when the low-speed engine is stopped, so that a circulating loop is formed between the common rail pipe (12) and the electric control oil injector (15) and an oil tank of the low-speed engine respectively.

2. The system according to claim 1, characterized in that the electrically controlled high pressure oil pump (1) comprises:

The pump comprises a pump body (101), wherein a middle hole is formed in the pump body (101) along the axial direction;

a pump cover (102), wherein the pump cover (102) is arranged on the upper end surface of the pump body (101);

The oil inlet and outlet valve assembly (103), the plunger coupling part (104), the plunger spring (105), the lower spring seat assembly (106) and the guide piston assembly (107) are all assembled in a middle hole of the pump body (101);

the electric control proportional valve (2) is assembled on the side surface of the pump body (101);

The oil inlet and outlet valve assembly (103) includes: an inlet valve assembly (1031) and an outlet valve assembly (1032);

the oil feed valve assembly (1031) includes: an oil inlet valve seat (10311), an oil inlet valve (10312) and an oil inlet valve spring (10313);

The oil inlet valve (10312) is arranged in a middle hole of the oil inlet valve seat (10311); the oil inlet valve spring (10313) is limited between the oil inlet valve (10312) and the hole wall of the oil inlet valve seat (10311); under the compression of the oil inlet valve spring (10313), the oil inlet valve (10312) and the oil inlet valve seat (10311) form conical surface sealing;

The outlet valve assembly (1032) includes: an oil outlet valve seat (10321), an oil outlet valve (10322), an oil outlet valve spring (10323) and an oil outlet valve spring seat (10324);

The oil outlet valve spring seat (10324) is arranged at the upper end of the oil outlet valve seat (10321); the oil outlet valve (10322) is arranged in a middle hole of the oil outlet valve seat (10321); the outlet valve spring (10323) is limited between the outlet valve (10322) and the outlet valve spring seat (10324); under the compression of the oil outlet valve spring (10323), the oil outlet valve (10322) and the oil outlet valve seat (10321) form conical surface sealing;

a high-pressure oil outlet cavity (1033) is formed between the oil outlet valve seat (10321) and the oil inlet valve seat (10311);

a high-pressure oil cavity (1041) is formed in the plunger coupling (104), and the high-pressure oil cavity (1041) is communicated with the high-pressure oil outlet cavity (1033) through an oil hole on the oil inlet valve seat (10311);

The electric control proportional valve (2) is communicated with an oil inlet hole of the oil inlet valve seat (10311) through an oil hole on the pump body (101), and the oil inlet hole is communicated with or disconnected from the high-pressure oil cavity (1041);

The electric control proportional valve (2) is provided with a cooling circulation oil duct, and cooling oil in the cooling oil duct from the pump body (101) flows back to the cooling oil duct of the pump body (101) after being injected into the cooling circulation oil duct.

3. The system of claim 2, wherein the plunger-coupling element (104) comprises:

a plunger sleeve (1042) provided at the lower end of the oil inlet valve seat (10311);

a plunger (1043) slidably inserted into a middle hole of the plunger housing (1042), the plunger (1043) and the oil inlet valve seat (10311) together forming the high-pressure oil chamber (1041);

The inner wall of the plunger sleeve (1042) is provided with a first annular groove (10421) and a second annular groove (10422);

The pump body (101) is provided with a mixed oil outlet passage and a lubricating oil passage (1012), the mixed oil outlet passage is communicated with the first annular groove (10421) through a mixed oil passage (10423) on the plunger sleeve (1042), and the lubricating oil passage (1012) is communicated with the second annular groove (10422) through a lubricating oil passage (10424) on the plunger sleeve (1042);

The first ring groove (10421) is located above the second ring groove (10422); the lower spring seat assembly (106) is disposed below the plunger coupling (104), the lower spring seat assembly (106) comprising:

The outer spring seat (1061) is integrally of a boss structure with a thin outer side and a thick middle, and a third counter bore (10611) with a concave spherical surface is formed in the upper end face of the outer spring seat (1061);

An upper sphere (1062) with the lower part mounted in the third counter bore (10611), and the lower end surface of the upper sphere (1062) is provided with a convex sphere matched with the concave sphere;

an inner spring seat (1063) sleeved on the upper part of the upper sphere (1062), wherein the inner spring seat (1063) is provided with a first axial through hole (10631) penetrating through the upper end face and the lower end face;

The lower cylindrical head (10431) of the plunger (1043) is limited in the first axial through hole (10631), and the lower end face of the lower cylindrical head (10431) of the plunger (1043) is abutted with the upper end face of the upper sphere (1062).

4. The system of claim 3, wherein the system further comprises a controller configured to control the controller,

A spherical hole (10612) is formed in the center of the third counter bore (10611), a third annular groove (10613) is formed in the lower end face of the outer spring seat (1061), and the spherical hole (10612) and the third annular groove (10613) are communicated through a lubricating oil inlet pipeline (10614);

The outer surface of the outer spring seat (1061) forms a conical surface, a lubricating oil outlet oil duct (10615) is formed in the conical surface, and the lubricating oil outlet oil duct (10615) is communicated with the lower end face of the outer spring seat (1061); the lubricating oil outlet oil duct (10615) is obliquely arranged;

A circumferential annular groove (10621) is formed in the circumferential direction of the upper sphere (1062);

the locating pin (1064) is installed in the circumferential ring groove (10621) after passing through the locating pin hole (10616) of the outer spring seat (1061);

The distance between the upper surface and the lower surface of the circumferential annular groove (10621) is larger than the cylindrical diameter of the part of the locating pin (1064) positioned in the circumferential annular groove (10621);

The first axial through hole (10631) provided inside the inner spring seat (1063) includes:

A seventh hole (10632), an eighth hole (10633) and a ninth hole (10634) that gradually increase in diameter from top to bottom;

a first guide hole (10635) with gradually increased diameter is arranged between the eighth hole (10633) and the ninth hole (10634);

A second guide hole (10636) with gradually increased diameter is formed in one side of the ninth hole (10634) facing the upper sphere (1062);

The walls of the first guide hole (10635) and the second guide hole (10636) are formed into guide conical surfaces (10637);

the upper part of the upper sphere (1062) passing through the second guide hole (10636) is partially positioned in the ninth hole (10634);

A gap of greater than or equal to 1mm is provided between the upper sphere (1062) and the ninth hole (10634);

a gap of greater than or equal to 1mm is provided between the third counterbore (10611) and the upper sphere (1062).

5. The system of claim 2, wherein the pilot piston assembly (107) comprises:

A first mounting hole (10711) is formed in the center position of the upper end surface of the guide piston (1071); a second mounting hole (10712) is formed in the lower end face of the lower spring seat assembly, the first mounting hole (10711) is communicated with the second mounting hole (10712) through a communication hole (10713), and the lower spring seat assembly (106) is mounted in the first mounting hole (10711);

a roller assembly (1072), comprising: a roller 10728 mounted in the second mounting hole 10712, a roller bushing 10722 interference-fitted in the roller 10728, and thrust bearings 10723 interference-fitted at both axial ends of the roller 10728; a ring groove (10724) is formed in the axial direction of the roller (10728), and the bottom of the ring groove (10724) is in arc transition connection with the axial end surface of the roller (10728);

a roller pin (1073) that fits with clearance within the roller bushing (10722);

a boss (10714) is arranged on the hole wall of the second mounting hole (10712) in a protruding mode, and the boss (10714) is in contact with the thrust bearing (10723);

the boss (10714) is uniformly arranged with a plurality of first radial oil grooves (10715) in a radial direction, the first radial oil grooves (10715) being provided with respect to the thrust bearing (10723).

6. The system of claim 5, wherein the system further comprises a controller configured to control the controller,

The outer surface of the roller pin (1073) is arranged to be a cylindrical surface, two positions on the cylindrical surface are respectively provided with two-step kidney-shaped grooves (10731, 10732), and the kidney-shaped grooves (10731, 10732) are arranged in the middle of the roller pin (1073);

A small-angle wedge-shaped groove with an angle of 5-20 degrees is formed between the waist-shaped groove (10731) positioned on the outer layer and the outer surface of the roller bushing (10722), and oil holes (10733, 10734) are formed in the waist-shaped groove (10732) positioned on the inner layer;

the two oil holes (10733, 10734) at the two positions are communicated through a lubricating oil outlet channel, and the two oil holes (10733, 10734) are arranged at 70-120 degrees;

The outer surface of the guide piston (1071) is arranged to be a cylindrical surface, a plurality of circumferential oil grooves (10729, 10725), a first axial oil groove (10716) and a vertical groove (10717) are formed in the cylindrical surface, the vertical groove (10717) is formed in the circumferential oil groove (10725), and the vertical groove (10717) is communicated with the circumferential oil groove (10729) through the first axial oil groove (10716);

The cylindrical surface is also provided with an inclined hole (10718), and two ends of the inclined hole (10718) are respectively communicated with the circumferential oil groove (10725) and the inner wall of the second mounting hole (10712);

a second axial oil groove (10719) communicated with the circumferential oil groove (10725) is further formed in the cylindrical surface;

The cylindrical surface is also provided with a first straight hole (10720) and a second straight hole (10721) which are connected, the first straight hole (10720) is communicated with the first axial oil groove (10716), and the second straight hole (10721) is communicated with the first mounting hole (10711);

The outer circular surface of the roller pin (1073) is provided with a lubricating oil inlet passage (10735), the lubricating oil inlet passage (10735) is opposite to the inclined hole (10718), and the lubricating oil inlet passage (10735) is communicated with the lubricating oil outlet passage.

7. The system of claim 1, wherein the system further comprises a controller configured to control the controller,

The common rail pipe (12) is provided with an oil inlet pipeline (1201) and an oil return pipeline (1202) which penetrate through two ends;

an oil inlet end cover (121) is fixed at one end of the common rail pipe (12), and an oil inlet communicated with the oil inlet pipeline (1201) is arranged on the oil inlet end cover (121);

An end cover (122) is fixed at the other end of the common rail pipe (12), an oil outlet communicated with the oil inlet pipeline (1201) is arranged on the end cover (122), and the circulating valve assembly (16) is fixed on the end cover (122);

the pressure limiting valve assembly (18) and the plurality of flow limiting valve assemblies (13) are respectively communicated with the oil inlet pipeline (1201), and the pressure limiting valve assembly (18) and the plurality of flow limiting valve assemblies (13) are respectively communicated with the oil return pipeline (1202).

8. The system of claim 7, wherein the recirculation valve assembly (16) comprises:

a first valve body (161) fixed on the end cover (122), a first middle hole (1601) communicated with the oil outlet is formed in the lower end surface of the first valve body, a second middle hole (1602) is formed in the upper end surface of the first valve body, and the first middle hole (1601) is communicated with the second middle hole (1602);

A first valve element (162) slidably inserted into the first middle hole (1601) from a lower end surface of the first valve body (161) and partially positioned in the second middle hole (1602);

the lower spring seat (164) is sleeved on the part of the first valve core (162) positioned in the second middle hole (1602) and is fixedly connected with the first valve core (162); a first cavity is formed between the lower spring seat (164) and the bottom of the second middle hole (1602);

A gland (167) fixed on the upper end surface of the first valve body (161), wherein a threaded hole (1603) is formed in the upper end surface of the gland (167);

An oil return joint (168) partially secured within the threaded bore (1603);

a first pressure regulating spring (169) that is retained between the lower spring seat (164) and the gland (167);

A first oil return channel (1605) communicated with the first middle hole (1601) is arranged on the first valve body (161), a second oil return channel (1606) communicated with the first oil return channel (1605) is arranged on the gland (167), a third oil return channel (1607) communicated with the second oil return channel (1606) is arranged on the oil return joint (168), and the first oil return channel (1605), the second oil return channel (1606) and the third oil return channel (1607) form a circulating oil channel;

A first air inlet channel (1608) communicated with the first cavity is arranged on the first valve body (161), a second air inlet channel (1629) communicated with the first air inlet channel (1608) and an air inlet (1630) communicated with the second air inlet channel (1629) are arranged on the gland (167);

When the spring force of the first pressure regulating spring (169) is smaller than or equal to the sum of the pressure of the gas introduced into the first cavity and the pressure of the oil inlet end of the first middle hole (1601), conical surface seal is formed between the first valve core (162) and the first middle hole (1601), and the position for forming the conical surface seal is located below the connecting position of the first oil return duct (1605) and the first middle hole (1601).

9. The system according to claim 1, wherein the restrictor valve assembly (13) comprises: a valve seat (131), a second valve body (132), a second valve core (133) and a second pressure regulating spring (135) which are used for being connected with the high-pressure common rail,

The valve seat (131) is provided with a first oil inlet hole (13101) communicated with the high-pressure common rail;

the second valve body (132) has a second axial through hole (13209) penetrating both upper and lower end surfaces thereof, and the valve seat (131) is press-fitted into the second axial through hole (13209) from a lower end portion of the second valve body (132);

The second valve core (133) is installed in the second axial through hole (13209) and is arranged above the valve seat (131);

the second valve core (133) is provided with an axial blind hole (13302) communicated with the first oil inlet hole (13101), and a cavity is formed between the upper end of the second valve core (133) and the second axial through hole (13209);

a transverse orifice (13304) which is communicated with the axial blind hole (13302) and the cavity is arranged in the second valve core (133);

The second pressure regulating spring (135) is sleeved on the second valve core (133) and is limited in the cavity;

The head part of the upper end of the second valve core (133) is provided with a third sealing conical surface (13305) and a fourth sealing conical surface (13306) which are connected;

The hole wall of the second axial through hole (13209) is provided with a first sealing seat surface (13206) which can form conical surface sealing with the third sealing conical surface (13305), and the first sealing seat surface (13206) can form a gap with the fourth sealing conical surface (13306).

10. The system of claim 1, wherein the pressure limiting valve assembly (18) comprises: a third valve body (181), a third valve core (182), a third pressure regulating spring (185) and an oil pipe joint (186),

A first-stage hole (18101), a second-stage hole (18102), a third-stage hole (18104) and a fourth-stage hole (18105) which are sequentially communicated are formed in the third valve body (181) from bottom to top;

The head of the third valve core (182) is slidably inserted from the fourth-stage hole (18105) into the second-stage hole (18102) through the third-stage hole (18104), and the third valve core (182) can form a conical surface seal with the second-stage hole (18102);

a first gap for fuel to pass through is formed between the third valve core (182) and the third-stage hole (18104), and a second gap for fuel to pass through is formed between the third valve core (182) and the fourth-stage hole (18105);

the oil pipe joint (186) is fixed at the upper end of the third valve body (181), a first counter bore (18601), a second counter bore (18602) and an oil outlet (18603) which are sequentially communicated are arranged in the oil pipe joint (186) from bottom to top, and the third pressure regulating spring (185) is limited between the third valve core (182) and the second counter bore (18602).

11. A system according to claim 3, characterized in that the electrically controlled high pressure oil pump (1) further comprises:

an upper spring seat (109) which is sleeved on the plunger sleeve (1042) and is positioned at the upper end of the inner spring seat (1063);

the plunger spring (105) comprises:

A first plunger spring (1051) that is press-fitted between the upper spring seat (109) and the outer spring seat (1061);

A second plunger spring (1052) that is press-fitted between the upper spring seat (109) and the inner spring seat (1063).

12. The system of claim 4, wherein the concave spherical surface within the outer spring seat (1061) and the convex spherical surface of the upper sphere (1062) have diameters that are 20 to 100 times the diameter of the plunger (1043).

13. The system of claim 6, wherein the system further comprises a controller configured to control the controller,

The outer circle surface of the roller pin (1073) is provided with a DLC coating;

The roller bushing (10722) is made of copper alloy;

the thrust bearing (10723) is made of copper alloy;

forced lubrication is adopted between the roller pin (1073) and the roller bushing (10722);

Forced lubrication is adopted between the thrust bearing (10723) and the boss (10714).

14. The system of claim 8, wherein a top of the portion of the first spool (162) within the second middle bore (1602) is provided with a first sealing cone (1611) and an external thread (1612), the external thread (1612) being located at an upper end of the first sealing cone (1611);

The lower spring seat (164) is sleeved on the first sealing conical surface (1611) after penetrating through the external thread (1612), and the lower spring seat (164) is provided with a second sealing conical surface (1613) which forms conical surface sealing with the first sealing conical surface (1611);

the lower spring seat (164) is tightly pressed by a nut (1614) sleeved on the periphery of the external thread (1612);

The first pressure regulating spring (169) is sleeved on the nut (1614) and is fixed on the lower spring seat (164).

15. The system of claim 8, wherein the system further comprises a controller configured to control the controller,

The oil return joint (168) is fixedly connected in the threaded hole (1603) in a threaded manner;

A first sealing plane (1615) is arranged on the upper end surface of the gland (167) at the opening of the threaded hole (1603);

The oil return joint (168) is provided with a second sealing plane (1616) which forms a plane seal with the first sealing plane (1615).

16. The system of claim 8, wherein the system further comprises a controller configured to control the controller,

A third cavity is formed between the lower end face of the oil return joint (168) and the hole bottom of the threaded hole (1603), the third cavity is respectively communicated with the second oil return passage (1606) and the third oil return passage (1607), and the maximum flow area of the third cavity is larger than that of the second oil return passage (1606).

17. The system of claim 8, wherein a distance H2 between the first valve body (161) and a lower end surface of the first valve body (162) is less than a distance H1 between a lower end surface of the lower spring seat (164) and a bottom of the second middle bore (1602) when the first valve body (162) moves upward within the first valve body (161) to a top dead center position.

18. The system of claim 14, wherein the lower spring seat (164) comprises: a third central hole (1617) for limiting the first pressure regulating spring (169) and a fourth central hole (1618) for cooperating with the first spool (162), the aperture of the fourth central hole (1618) being larger than the diameter of the external thread (1612);

The outer diameter of the lower spring seat (164) is the same as the aperture of the second middle hole (1602).

19. The system of claim 9, wherein the second axial through hole (13209) comprises a first hole, a second hole, a third hole (13205), a fourth hole (13207), a fifth hole, and a sixth hole connected in sequence from top to bottom;

The valve seat (131) is partially press-fitted into the first hole;

the second valve core (133) is assembled in the second hole, and a cavity is formed between the upper part of the second valve core (133) and the upper part of the second hole;

the bore wall of the third bore (13205) forms the first sealing seating surface (13206);

The hole wall of the fifth hole is provided with a second sealing seat surface (13208) for forming a seal with the oil inlet end of the oil pipe of the oil injector;

The sixth aperture has a larger aperture than the first aperture, the second aperture, the third aperture (13205), the fourth aperture (13207) and the fifth aperture.

20. The system according to claim 19, wherein a fourth oil return passage (13210) is further provided on the second valve body (132), one end of the fourth oil return passage (13210) communicates with the sixth hole, and the other end communicates with a lower end face of the second valve body (132);

The maximum cross-sectional flow area of the fourth oil return passage (13210) is smaller than the maximum cross-sectional flow area of a gap formed between the fourth sealing cone surface (13306) and the first sealing seat surface (13206);

the maximum cross-sectional flow area of the fourth oil return passage (13210) is smaller than the maximum cross-sectional flow area of the second axial through hole (13209) and the maximum cross-sectional flow area of the fourth hole (13207).

21. The system of claim 20, wherein a head of a lower end of the valve seat (131) is formed with a fifth sealing cone (13102) for forming a cone seal with the high pressure common rail;

the big outer circle of disk seat (131) lower extreme mills has first flat (13104), first flat (13104) intercommunication fourth oil return duct (13210).

22. The system of claim 10, wherein the system further comprises a controller configured to control the controller,

The first stage holes (18101) have a larger pore diameter than the second stage holes (18102), and the third stage holes (18104) have a larger pore diameter than the second stage holes (18102) and the fourth stage holes (18105).

23. The system of claim 10, wherein the system further comprises a controller configured to control the controller,

The head of the third valve core (182) is provided with a first taper angle (18201) and a second taper angle (18202) which are connected in sequence, the angle of the first taper angle (18201) is 120 degrees, and the angle of the second taper angle (18202) is 60 degrees;

a second flat (18203) which is symmetrically arranged is milled on a third outer circle (18204) in the middle of the third valve core (182), a second gap for fuel to pass through is formed between the second flat (18203) and the hole wall of a fourth-stage hole (18105) of the third valve body (181), and the maximum fuel area which can flow in the second gap is larger than the maximum fuel area which can flow in the second-stage hole (18102);

a plurality of grooves are formed in the outer circle of the middle upper part of the third valve core (182) at intervals, and a third gap for fuel oil to pass through is formed between the grooves and the first counter bore (18601);

the third pressure regulating spring (185) is sleeved on a second small outer circle (18206) at the upper part of the third valve core (182).

24. The system of claim 23, wherein a location where the second stage orifice (18102) and the third stage orifice (18104) are connected is formed with a sealing seat surface for forming a cone seal with the second cone angle (18202), the sealing seat surface having an angular deviation from the second cone angle (18202) of less than 1 °;

The aperture of the fourth-stage hole (18105) of the third valve body (181) is phi 5mm.