FI130836B1

FI130836B1 - Electronically controlled common-rail heavy fuel injector

Info

Publication number: FI130836B1
Application number: FI20215086A
Authority: FI
Inventors: Xiaoxue Lin; Chao Chen; Qiang Xu; Yang Liu; Chaolei Zhang; Huie Liu; Lang Gao; Dongmin Li
Original assignee: Chongqing hongjiang machinery co ltd
Priority date: 2019-09-26
Filing date: 2020-04-23
Publication date: 2024-04-16
Also published as: GB2596882B8; FI130836B8; FI20215086A1; GB2596882A8; GB202018634D0; DE112020000639T5; CN110594061A; WO2021057018A1; GB2596882B; CN110594061B; GB2596882A

Abstract

The electronically controlled common-rail heavy fuel injector comprises: an injector body (1), an electro-hydraulic control component, and a nozzle component. In the electro-hydraulic control component, a ring groove (110) is opened in the middle of the outer side of a guide sleeve (8), a horizontal through hole leading to the middle hole of the guide sleeve (8) is provided in the middle of the ring groove (110), and sealing rings (10) are provided on both sides of the ring groove (110) to divide the interior of the injector body (1) into three chambers. Three ring grooves (111) are opened on the guide section of a control valve core (9), and the second ring groove (111) is communicated with the horizontal through hole in the middle of the guide sleeve (8). An electromagnetic element is in contact with the cooling fuel, and a cooling fuel circuit is isolated from a fuel oil circuit in a manner of dynamic sealing, static sealing, and drainage, which can effectively avoid the corrosion and thermal damage of the heavy fuel to the electromagnetic elements; a sink groove is opened in the middle of the top of an orifice plate (14), a ball valve seat guide sleeve (11) is capable of being inserted into the sink groove of the orifice plate (14) and is in clearance fit with the ball valve seat (12), which has a certain guiding ability for the axial movement of the ball valve seat (12).

Description

ELECTRONICALLY CONTROLLED COMMON-RAIL HEAVY FUEL

INJECTOR

TECHNICAL FIELD

The disclosure relates to a high-pressure common-rail engine, in particu- lar to an electronically controlled common-rail injector.

BACKGROUND

With the rising transportation costs of shipping companies, engines that use heavy fuel (combustible low-quality fuel) as fuel have unique advantages in cost reduction. Due to its many impurities, heavy fuel is corrosive to parts, prone to stickiness, and also corrosive to electronic elements. At the same time, heavy fuel is highly viscous and requires high temperature heating dur- ing use. Excessively high oil temperature will shorten the life of electronic el- ements. How to improve this problem is an important hot spot to improve the service life of heavy fuel diesel engines.

The prior art low-speed diesel engine needs to be driven hydraulically for exhaust valve control, and is designed with a dedicated servo oil channel for driving oil. Therefore, heavy fuel injection relies on adding a servo oil driver outside the injector to perform remote hydraulic control of the injector.

The application of servo oil prevents heavy fuel and electronic elements from contacting each other. However, the pressure of servo oil is much lower than

N that of fuel. The volume of the booster structure in the servo oil driver is

N large, so that the external servo oil driver occupies a large space and it is dif- > 25 ficult to arrange space. Therefore, multiple injectors on the same cylinder can

N often only share one servo oil driver, so that the fuel injection between the in-

E jectors 1s unable to be independent of each other, and there is interference. At = the same time, the movement of the exhaust valve causes the servo oil pres-

D sure to fluctuate, which affects the operating response of the servo oil driver

ES 30 and indirectly affects the consistency of each injection of the injector.

Furthermore, the servo oil driver needs to be arranged farther away from the injector due to its large size, which causes a large delay in control.

The electronically controlled common-rail fuel system is a fuel injection system based on mechanical, hydraulic and electrical technologies. This sys- tem uses a common-rail pipe with a certain volume between the fuel supply pump and the injector to accumulate fuel to suppress pressure fluctuations, and then to deliver fuel to each injector through the fuel pipe. The injector is controlled to be on/off by the action of the solenoid valve of the injector. This system has the advantages of stable fuel injection pressure, controllable fuel injection pressure and fuel injection process. Therefore, it is of great signifi- cance to study a new electronically controlled common-rail heavy fuel injec- tor that can place electromagnetic components inside the injector and reduce high temperature and heavy fuel pollution.

SUMMARY

The disclosure proposes an electronically controlled common-rail heavy fuel injector. The electromagnetic element is placed inside the injector. The forced cooling structure is designed to effectively avoid thermal damage to the electromagnetic element, and the oil sealing structure is designed to pre- vent the cooling fuel from being polluted by heavy fuel, prevent heavy fuel from corroding electromagnetic components, and save installation space.

The technical solution of the disclosure is as follows.

N An electronically controlled common-rail heavy fuel injector comprises

ÖN an injector body, an electro-hydraulic control component and a nozzle com- 3 25 ponent.

E An electronic interface is provided in the middle of the top of the injec- © tor body, the top is circumferentially provided with an oil inlet interface, a 3 circulating oil interface, a cooling oil inlet interface, a cooling oil outlet inter-

N face, a fuel return interface and a mixed oil interface, which are connected to

N 30 a wire end of an electromagnet, an oil inlet channel, a circulating oil channel,

a cooling oil inlet channel, a cooling fuel return channel, a fuel return channel and a mixed oil discharging channel, respectively.

The electro-hydraulic control component comprises an electromagnet, a control valve return spring, an armature, a sleeve, a guide sleeve, a control valve core, a ball valve seat guide sleeve, a ball valve seat, a steel ball and an orifice plate; the orifice plate is provided between the injector body and the nozzle component, an oil inlet orifice and an oil outlet orifice are provided in- side the orifice plate; the control valve core and the guide sleeve are cooper- ated through a coupling, the middle hole of the guide sleeve is capable of guiding the control valve core for axial sliding; the ball valve seat is provided in the ball valve seat guide sleeve; the electromagnet, the sleeve, the guide sleeve and the ball valve seat guide sleeve are assembled in the middle hole of the injector body from top to bottom, and are pressed on the orifice plate by a compression nut; the control valve core, the ball valve seat, and the steel ball are in contact in sequence, and are pressed against the sealing conical surface of the orifice plate by the control valve return spring located in the middle hole of the electromagnet to block the oil outlet orifice; the guide sleeve is sealed by installing the sealing ring through two outer sealing ring grooves.

A sink groove is provided in the middle of the top of the orifice plate, the ball valve seat guide sleeve is sleeved in the sink groove; the upper half of the middle hole of the ball valve seat guide sleeve has a larger opening than _ that of the lower half, and the lower half thereof is in clearance fit with the

O ball valve seat, which has a certain guiding ability for the axial movement of 5 25 the ball valve seat. A cross milling groove is provided at the top of the ball

N valve seat guide sleeve, and three milling grooves are evenly distributed on

I the guide surface of the ball valve seat. The chamber above the steel ball is o communicated with the fuel return channel through the ball valve seat and the

O milling grooves on the ball valve seat guide sleeve. 3 30 The circulating oil channel and the oil inlet channel lead into the nozzle component through the injector body and the orifice plate.

Further, the nozzle component comprises a needle valve guide sleeve, a needle valve, a needle valve return spring, a pressure regulating gasket, a body locking nut, a needle valve body, a nozzle locking nut and a nozzle; the needle valve guide sleeve and the needle valve are both cooperated with the needle valve body through a coupling, the upper and lower sliding surfaces of the needle valve are slidable axially in the middle hole of the needle valve body and the middle hole of the needle valve guide sleeve, respectively; both ends of the needle valve return spring press the needle valve guide sleeve and the needle valve, respectively, so that the top of the needle valve guide sleeve is pressed against the lower plane of the orifice plate, the conical surface of the lower end of the needle valve is pressed against the conical surface of the middle hole of the needle valve body; the cylindrical surface of the bottom end of the needle valve body is in interference fit with the counterbore of the nozzle, the nozzle is provided with a nozzle hole for injecting fuel; the body locking nut connects the nozzle component to the injector body, and presses the top end surface of the needle valve body against the bottom end of the ori- fice plate; and the circulating oil channel and the oil inlet channel lead to the middle hole of the needle valve body via the injector body and the orifice plate.

Further, the orifice plate, the needle valve guide sleeve, and the needle valve surround and form a pressure control chamber, which communicates with the outside through the oil inlet orifice and the oil outlet orifice; the fuel return channel is separated from the oil outlet orifice by a steel ball on the in-

N jector body; the mixed oil discharging channel is communicated with the ring = 25 chamber enclosed by the ring groove in the middle of the guide sleeve and the 7 sealing ring; the cooling oil inlet channel and the cooling fuel return channel - are communicated with the oil chamber enclosed by the electromagnet, the

E guide sleeve and the sealing ring, and are communicated with each other 8 through the groove hole on the sleeve. 5 30 Further, the nozzle comprises a nozzle body and an ejector rod cooper-

N ated therewith; the nozzle body is interference installed on the needle valve body, the ejector rod is rigidly connected to the head of the needle valve or is processed as a whole with the head of the needle valve; there are two fitting surfaces between the nozzle body and the ejector rod cooperated therewith, the oil chamber between the nozzle body and the ejector rod is divided into 5 three parts: the nozzle upper chamber, the nozzle middle chamber and the nozzle lower chamber, the ejector rod is provided with a central longitudinal hole and a horizontal hole to connect the nozzle upper chamber and the noz- zle lower chamber, the nozzle hole on the nozzle body is located within the width of the nozzle middle chamber; when the injector is in the spraying state, the nozzle body is staggered with the lower fitting surface of the ejector rod, so that the nozzle lower chamber is connected with the nozzle middle chamber, and when the injector is in the stopping state, the nozzle body and the lower fitting surface of the ejector rod are attached to each other to dis- connect the nozzle lower chamber from the nozzle middle chamber.

The length of the nozzle is greater than or equal to 19 mm.

A nozzle locking nut is sleeved at the part where the needle valve body and the nozzle body are combined, the upper end of the nozzle locking nut is in threaded connection with the needle valve body, the inner wall of the lock- ing nut tightly sleeves the needle valve body and the nozzle body, and the cone angle and the thickness of the lower end of the locking nut are designed to match the cone angle of the installation seat surface required by the injec- tor and the length of the nozzle extending into the cylinder. — Further, a ring groove is provided on the outside of the middle of the

S guide sleeve, a horizontal through hole is provided in the middle of the ring 5 25 groove leading to the middle hole in the guide sleeve; a sealing ring groove is

N provided on both sides of the ring groove; the diameter of the bottom end of

E the control valve core is larger than the guide section, the guide section is

O provided with three ring grooves and the second ring groove is communicated

D with the horizontal through hole in the middle of the guide sleeve. The con-

S 30 trol valve core, the guide sleeve and the sealing ring divide the middle hole of the injector body into three chambers.

The beneficial technical effects of the disclosure are as follows. 1) The electromagnetic element is directly designed into the injector, and the servo oil driver of the old heavy fuel system is eliminated, which saves space. The electronic control system can change the working law of a single injector at any time, and different injectors are not affected by each other. 2) The internal part of the injector is divided into three chambers by the electro-hydraulic control component, and an electromagnetic element is in di- rect contact with the cooling fuel. A cooling fuel circuit is isolated from a fuel oil circuit in a manner of dynamic sealing, static sealing, and drainage. The technical solution disclosed in the disclosure can be applied to a high-pres- sure common-rail system using heavy fuel as fuel, which can effectively avoid the corrosion and thermal damage of the heavy fuel to the electromag- netic element. 3) The electro-hydraulic control component adopts the ball valve as the control valve, which has good self-alignment. A sink groove is provided in the middle of the top of the orifice plate for installing the ball valve seat guide sleeve to install the ball valve seat guide sleeve. The guide sleeve has a cer- tain guiding ability for the axial movement of the ball valve seat to prevent the steel ball from lateral deviation due to the inclined installation angle of the injector, and further improve the working stability. At the same time, the ball valve seat guide sleeve and the ball valve seat can be directly removed from the orifice plate as a single piece, which facilitates the replacement after = wear and damage due to the reguirement of lift adjustment of the injector

N control valve. > 25 4) The improved nozzle structure can keep the injector needle valve

N sealing seat surface away from gas and high temperature environment, which z can effectively reduce the damage to the injector needle valve sealing seat 8 surface caused by high temperature environment and inferior fuel and save = installation space. At the same time, the two fitting surfaces of the nozzle and the ejector rod divide the nozzle into three chambers. This cooperation re- duces the chamber volume in the nozzle, thereby reducing the phenomenon of oil dripping, and further reducing the impact of insufficient combustion on the life of low-speed diesel engines. Because of the design of the upper, mid- dle and lower chambers of the injector nozzle, the nozzle hole on the nozzle body can be located within the width of the nozzle middle chamber, so that the design position space of the nozzle hole is larger. For the manufacturer and designer, it has a certain modification potential, so that the nozzle is eas- ily modified and applied to other forms of low-speed diesel injectors.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic diagram of the structure of the disclosure;

FIG. 2 is a schematic diagram of an electrical interface and a hydraulic interface of the disclosure;

FIGS. 3 and 3a are enlarged diagrams of a ball valve seat and a ball valve guide sleeve of the disclosure;

FIG. 4 is a schematic diagram of a nozzle component of the disclosure;

FIGS. 5 and 5a are schematic diagrams of an electro-hydraulic control component of the disclosure;

FIG. 6 is a schematic diagram of a cooling structure of the disclosure;

FIG. 7 is a schematic diagram of a cooling fuel pollution prevention structure of the disclosure;

FIG. 8 is a schematic diagram of the structure of a nozzle part of the dis-

S closure.

N

O In the figures, 1-injector body, 2-compression nut, 3-electromagnet, 4-

N control valve return spring, 5-nut, 6-armature, 7-sleeve, 8-guide sleeve, 9-

E 25 control valve core, 10-sealing ring, 11-ball valve seat guide sleeve, 12-ball

O valve seat, 13-steel ball, 14-orifice plate, 15-needle valve guide sleeve, 16-

D needle valve, 17-needle valve return spring, 18-pressure regulating gasket,

O 19-body locking nut, 20-needle valve body, 21-nozzle locking nut, 22-nozzle, 23-electronic interface, 24-oil inlet interface, 25-circulating oil interface, 26-

cooling oil inlet interface, 27-cooling oil outlet interface, 28-fuel return inter- face, 29-mixed oil interface, 101-circulating oil channel, 102-oil inlet chan- nel, 103-oil inlet orifice, 104-pressure control chamber, 105-oil outlet orifice, 106-fuel return channel, 107-mixed oil discharging channel, 108-cooling oil inlet channel, 109-cooling fuel return channel, 110-guide sleeve ring groove, 111-valve core ring groove, 221-ejector rod, 222-nozzle body.

DESCRIPTION OF THE EMBODIMENTS

The disclosure will be described in detail hereinafter with reference to the drawings.

FIG. 1 shows an electronically controlled common-rail heavy fuel injec- tor with a specific structure, which comprises three parts: an injector body, an electro-hydraulic control component, and a nozzle component.

It can be seen from FIG. 1 and FIG. 2 that an electronic interface (23) is provided in the middle of the top of the injector body (1), the top is circum- ferentially provided with an oil inlet interface (24), a circulating oil interface (25), a cooling oil inlet interface (26), a cooling oil outlet interface (27), a fuel return interface (28) and a mixed oil interface (29), which are connected to a wire end of an electromagnet (3), an oil inlet channel (102), a circulating oil channel (101), a cooling oil inlet channel (107), a cooling fuel return chan- nel (108), a fuel return channel (105) and a mixed oil discharging channel (106), respectively;

N The structure of the electro-hydraulic control component can be seen in eI conjunction with FIG. 1, FIG. 5, FIG. 6 and FIG. 7, which comprises a com- 7 25 pression nut (2), an electromagnet (3), a control valve return spring (4), a nut - (5), an armature (6), a sleeve (7), a guide sleeve (8), a control valve core (9),

S a sealing ring (10), a ball valve seat guide sleeve (11), a ball valve seat (12), a 3 steel ball (13) and an orifice plate (14). The orifice plate (14) is provided be- = tween the injector body (1) and the nozzle component, an oil inlet orifice

N 30 (103) and an oil outlet orifice (105) are provided inside the orifice plate (14),

and the lower end is in contact with the nozzle component. The control valve core (9) and the guide sleeve (8) are cooperated through a coupling, and the middle hole of the guide sleeve (8) is capable of guiding the control valve core (9) for axial sliding. The ball valve seat (12) is provided in the ball valve seat guide sleeve (11). The electromagnet (3), the sleeve (7), the guide sleeve (8) and the ball valve seat guide sleeve (11) are assembled in the middle hole of the injector body (1), and are pressed on the orifice plate (14) by a com- pression nut (2). The armature (6) and the top thread of the control valve core (9) are fixed by a nut (5). The control valve core (9), the ball valve seat (12), and the steel ball (13) are in contact in sequence, and are pressed against the sealing conical surface of the orifice plate (14) by the control valve return spring (4) located in the middle hole of the electromagnet (3) to block the oil outlet orifice (105); the sealing ring (10) is sleeved in the outer sealing ring groove of the guide sleeve (8).

In conjunction with FIGS. 1 and 4, the nozzle component comprises a needle valve guide sleeve (15), a needle valve (16), a needle valve return spring (17), a pressure regulating gasket (18), a body locking nut (19), a nee- dle valve body (20), a nozzle locking nut (21), and a nozzle (22). The needle valve guide sleeve (15) and the needle valve (16) are both cooperated with the needle valve body (20) through a coupling, two sliding surfaces of the needle valve (16) are slidable axially in the middle hole of the needle valve body (20) and the middle hole of the needle valve guide sleeve (15), respec- tively; both ends of the needle valve return spring (17) press the needle valve

N guide sleeve (15) and the needle valve (16), respectively, so that the top of the = 25 needle valve guide sleeve (15) is pressed against the lower plane of the orifice 7 plate (14), the conical surface of the lower end of the needle valve (16) is - pressed against the conical surface of the middle hole of the needle valve

E body (20). The pressure regulating gasket (18) adjusts the pressing force; the 8 cylindrical surface of the bottom end of the needle valve body (20) is in inter- = 30 ference fit with the counterbore of the nozzle (22), which is further fixed by

N the nozzle locking nut (21), and the nozzle (22) is provided with a nozzle hole for injecting fuel. The body locking nut (19) connects the nozzle component to the injector body (1), and presses the top end surface of the needle valve body (20) against the bottom end of the orifice plate (14).

In the above structure, the circulating oil channel (101) and the oil inlet channel (102) lead to the middle hole of the needle valve body (20) via the in- jector body (1) and the orifice plate (14). The orifice plate (14), the needle valve guide sleeve (15), and the needle valve (16) surround and form a pres- sure control chamber (104), which communicates with the outside through the oil inlet orifice (103) and the oil outlet orifice (105). The fuel return chan- nel (106) is separated from the oil outlet orifice (105) by a steel ball (13) on the injector body (1). The mixed oil discharging channel (107) is communi- cated with the ring chamber enclosed by the ring groove in the middle of the guide sleeve (8) and the sealing ring (10). The cooling oil inlet channel (108) and the cooling fuel return channel (109) are communicated with the oil chamber enclosed by the electromagnet (3), the guide sleeve (8) and the seal- ing ring (10), and are communicated with each other through the groove hole on the sleeve (7).

Referring to FIGS. 5 and Sa, a ring groove (110) is provided on the out- side of the middle of the guide sleeve (8), a horizontal through hole is pro- vided in the middle of the ring groove leading to the middle hole in the guide sleeve (8); and a sealing ring groove is provided on both sides of the ring groove. The diameter of the bottom end of the control valve core (9) is larger than the guide section, the guide section is provided with three ring grooves (111) and the second ring groove is communicated with the horizontal

S through hole in the middle of the guide sleeve (8). The control valve core (9), 5 25 the guide sleeve (8) and the sealing ring (10) divide the middle hole of the in-

N jector body (1) into three chambers.

E In conjunction with FIG. 3 and FIG. 3a, it can be seen that a sink groove

O is provided in the middle of the top of the orifice plate (14). The ball valve

D seat guide sleeve (11) is capable of being sleeved in the sink groove of the or-

O 30 ifice plate (14); the upper half of the middle hole of the ball valve seat guide sleeve (11) has a larger opening than that of the lower half, and the lower half thereof is in clearance fit with the ball valve seat (12), the lower half of the middle hole of the guide sleeve (11) has a certain guiding ability for the axial movement of the ball valve seat (12); a cross milling groove is provided at the top, and three milling grooves are evenly distributed on the guide surface of the ball valve seat (12). The chamber above the steel ball (13) is communi- cated with the fuel return channel (105) through the ball valve seat (12) and the milling grooves on the ball valve seat guide sleeve (11).

As shown in FIG. 8, the nozzle (22) used in this embodiment comprises a nozzle body (222) and an ejector rod (221) cooperated therewith; the nozzle body (222) and the needle valve body are interference installed through the nozzle interference assembly surface (223), the ejector rod is rigidly con- nected to the head of the needle valve of the injector to which the nozzle is applied or is processed as a whole with the head of the needle valve. The length of the nozzle is greater than 19 mm. The nozzle body (222) and the ejector rod (221) are both provided below the sealing seat surface of the nee- dle valve coupling.

The two small-diameter surfaces in the middle of the nozzle body (222) are radially matched with the ejector rod (221) to form two fitting surfaces, namely the nozzle upper fitting surface (225) and the nozzle lower fitting sur- face (227). The clearance between the ejector rod (221) and the nozzle body (222) is very small on the fitting surface, which has a guiding effect on the ejector rod and has a better sealing ability. The nozzle upper fitting surface _ (225) and the nozzle lower fitting surface (226) divide the oil chamber be-

O tween the nozzle body (222) and the ejector rod (221) into three parts: the 5 25 nozzle upper chamber (224), the nozzle middle chamber (226) and the nozzle

N lower chamber (228). The ejector rod (221) is provided with a central longitu-

I dinal hole (2210) and a horizontal hole (2211) to connect the nozzle upper a © chamber (224) and the nozzle lower chamber (228). The nozzle holes (229) 3 are all provided in the nozzle middle chamber (226).

S 30 The working principle of the nozzle is as follows.

In the initial state, the conical surface on the needle valve and the seat surface on the needle valve body form a sealing effect, and the high-pressure fuel to be injected accumulates above the sealing seat surface.

In the injection state, the needle valve is lifted by the mechanical force or hydraulic pressure provided by the control end of the injector, and the seal- ing seat surface is opened. At the same time, the needle valve drives the ejec- tor rod (221). The nozzle body (222) is staggered with the lower fitting sur- face (227) of the ejector rod (221) so that the nozzle lower chamber (228) is communicated with the nozzle middle chamber (226). At this time, the high- pressure fuel above the sealing seat surface flows into the nozzle middle chamber (226) through the sealing seat surface, the nozzle upper chamber (224), the horizontal hole (2211), the longitudinal hole (2210) and the nozzle lower chamber (228), and is finally injected from the nozzle hole (229) pro- vided in the nozzle middle chamber (226) into the cylinder to participate in combustion.

In the stopping state, the control end of the injector does not provide force. The needle valve falls under the action of spring force or other kinds of restoring force, and is re-pressed on the sealing seat surface. The high-pres- sure fuel is sealed on the sealing seat surface. At this time, the nozzle body (222) and the lower fitting surface (227) of the ejector rod (221) are reat- tached to each other, so that the lower nozzle chamber (228) is disconnected from the nozzle middle chamber (226). The nozzle upper fitting surface (225) _ and the nozzle lower fitting surface (227) separate the nozzle upper chamber

O (224) and the nozzle lower chamber (228) from the nozzle middle chamber 5 25 (226), respectively. The residual oil is located in the nozzle upper chamber

N (224) and the nozzle lower chamber (228) cannot flow to the nozzle hole

I (229), and the fuel injection stops. At this time, the exhaust gas after combus- o tion in the cylinder can only contact the nozzle middle chamber (226) through

O the nozzle hole (229), which will not corrode the sealing seat surface of the

N 30 needle valve coupling. At the same time, because the nozzle itself is relatively

N long, the needle valve coupling can be provided in a cylinder head that is far away from the cylinder and has a relatively good cooling condition, which can effectively reduce the damage to the injector needle valve sealing seat surface caused by high temperature environment and inferior fuel. Since the diameter of the nozzle is smaller than the diameter of the needle valve body, the required installation hole can be appropriately reduced, saving installation space of the cylinder wall side, and providing a margin for arranging other devices that need to be installed on the cylinder wall side such as air valves.

For this nozzle, the nozzle body is made of corrosion-resistant and heat- resistant materials with a small thermal expansion coefficient, which can re- duce the thermal deformation due to the nozzle body being heated, indirectly stabilize the gap width between the nozzle body and the ejector rod, and en- sure stable operation.

The working principle of the electronically controlled common-rail heavy fuel injector of the above structure is as follows.

When the electromagnet (3) is not energized, the heavy fuel flows into the middle hole of the needle valve body (20) through the oil inlet interface (24) and the oil inlet channel (103), and then flows into the pressure control chamber (104) through the oil inlet orifice (103). At this time, the control valve core (9) is pressed against the ball valve seat (12) so that the steel ball (13) is pressed against the oil outlet orifice (105). The fuel pressure in the pressure control chamber (104) is equal to the pressure in the middle hole of the needle valve body (20). Both ends of the needle valve (16) are subjected — to the fuel pressure and the spring force transmitted by the needle valve return

S spring (17). The resultant force direction of the needle valve (16) is down- 5 25 ward to maintain the seated state, and the lower end conical surface of the

N needle valve (16) can be pressed against the fuel injection end of the needle

E valve body (20). = After the electromagnet (3) is energized, an electromagnetic force is 3 generated, and the armature (6) is affected by the attraction force. When the

N 30 electromagnetic force is greater than the spring force of the control valve re- turn spring (4), the control valve core (9) is affected by the resultant force and move upward along with the armature (6) until the large-diameter position of the bottom end thereof is in contact with the bottom end of the guide sleeve (8). The steel ball (13) leaves the original position. At this time, the oil outlet orifice (105) is opened. The high-pressure oil in the pressure control chamber (104) flows upward through the oil outlet orifice (105), passes through the three milling grooves evenly distributed on the guide surface of the ball valve seat (12), the opening of the upper half of the middle hole of the ball valve seat guide sleeve (11), and the top through groove, and finally flows out of the injector from the fuel return channel (106) and the fuel return interface (28). At this time, the hydraulic pressure in the pressure control chamber (104) gradually decreases, and the hydraulic pressure difference between both sides of the needle valve (16) increases. The needle valve (16) moves upward and opens the seal with the needle valve body (20). The high-pressure fuel is sprayed out of the nozzle (22) and the fuel injection process starts.

When the electromagnet (3) is de-energized, the control valve return spring (4) drops the control valve core (9) again, the steel ball is re-pressed against the oil outlet orifice (105), and the oil inlet orifice (103) replenishes oil to the pressure control chamber (104). The hydraulic pressure increases.

The needle valve (16) moves downward under the combined action of the hy- draulic pressure and the needle valve return spring (17), and the lower end conical surface of the needle valve (16) is again pressed against the oil nozzle of the needle valve body (20), and the injection process ends. _ The high-pressure oil part of the injector is communicated with the cir-

O culating oil channel (101) and the circulating oil interface (25) to provide an 5 25 oil circuit for installing an external circulating fuel valve. The function of the

N circulating fuel valve is that when the injector is operating normally, the cir-

I culating fuel valve is closed and does not affect the normal operation of the o injector; when the fuel system is about to shut down, the system uses clea fuel

O with a certain low pressure to flow into the injector. At this time, the circulat-

N 30 ing fuel valve is opened due to low pressure. The fuel can flow in the injector

N at a certain speed to clean the residual heavy fuel, and prevent the residual heavy fuel with many impurities from making the mating parts sticky and clogging the pores after being cooled.

The cooling oil inlet channel (108) and the cooling fuel return channel (109) are connected to the oil chamber enclosed by the electromagnet (3), the guide sleeve (8) and the sealing ring (10), and are communicated with each other through the groove hole on the sleeve (7). The flow of cooling fuel is subjected to the forced cooling and takes away heat, avoiding thermal damage to electronic elements resulted from high temperature caused by heavy fuel.

The control valve core (9), the guide sleeve (8) and the sealing ring (10) divide the middle hole of the injector body (1) into three chambers. The upper chamber is a cooling fuel chamber, the lower chamber is a heavy fuel return chamber, and the middle chamber is pressed and statically sealed by the seal- ing ring (10) and the plane of each part. The guide section of the control valve core (9) is provided with three ring grooves (111) to strengthen the dynamic sealing with the guide sleeve (8). In order to prevent the slight leakage after long-term use from contaminating the cooling fuel circuit, the second ring groove on the guide section of the control valve core (9) is connected with the horizontal through hole in the middle of the guide sleeve (8). After leaking into the second ring groove from the first and third ring grooves, the heavy fuel and the cooling fuel pass through the ring groove (110) in the middle of the guide sleeve (8) and flow into the mixed oil discharging channel (107), and are finally led from the mixed oil interface (29) to further reduce the hy- _ draulic pressure at the second ring groove of the guide section of the control

O valve core (9). The cooling fuel pressure in the above third ring groove and 5 25 the lower mixed oil hydraulic pressure at the second ring groove form a

N downward pressure difference, which prevents heavy fuel from being

I squeezed by the guide surface and leaking upward. The cooling fuel circuit is a © isolated from the fuel oil circuit in a manner of static sealing, dynamic seal- 3 ing, and drainage. This technical solution can effectively avoid the pollution

N 30 of the heavy fuel to the cooling fuel, and further avoid the corrosion of the

N electromagnetic components.

The electro-hydraulic control component adopts the ball valve as the control valve, and the ball valve has good self-alignment. At the same time, the guide sleeve has a certain guiding ability for the axial movement of the ball valve seat to prevent the steel ball (13) from lateral deviation due to the inclined installation angle of the injector, and further improve the working stability. At the same time, the ball valve seat guide sleeve and the ball valve seat can be directly removed from the orifice plate as a single piece, which fa- cilitates the replacement after wear and damage due to the requirement of lift adjustment of the injector control valve.

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Claims

1. An electronically controlled common-rail heavy fuel injector, comprising: an injector body (1), an electro-hydraulic control component and a nozzle compo- nent; wherein: an electronic interface (23) is provided in the middle of the top of the injector body (1), the top is circumferentially provided with an oil inlet inter- face (24), a circulating oil interface (25), a cooling oil inlet interface (26), a cool- ing oil outlet interface (27), a fuel return interface (28) and a mixed oil interface (29), which are connected to a wire end of an electromagnet (3), an oil inlet channel (102), a circulating oil channel (101), a cooling oil inlet channel (107), a cooling fuel return channel (108), a fuel return channel (105) and a mixed oil discharging channel (106), respectively; the electro-hydraulic control component comprises an electromagnet (3), a control valve return spring (4), an armature (6), a sleeve (7), a guide sleeve (8), a control valve core (9), a ball valve seat — guide sleeve (11), a ball valve seat (12), a steel ball (13) and an orifice plate (14); the orifice plate (14) is provided between the injector body (1) and the noz- zle component, an oil inlet orifice (103) and an oil outlet orifice (105) are pro- vided inside the orifice plate (14); the control valve core (9) and the guide sleeve (8) are cooperated through a coupling, the middle hole of the guide sleeve (8) is — capable of guiding the control valve core (9) for axial sliding; the ball valve seat (12) is provided in the ball valve seat guide sleeve (11); the electromagnet (3), the sleeve (7), the guide sleeve (8) and the ball valve seat guide sleeve (11) are assembled in the middle hole of the injector body (1) from top to bottom, and are & pressed on the orifice plate (14) by a compression nut (2); the control valve core = 25 — (9), the ball valve seat (12), and the steel ball (13) are in contact in sequence, and = are pressed against the sealing conical surface of the orifice plate (14) by the > control valve return spring (4) located in the middle hole of the electromagnet E (3) to block the oil outlet orifice (105); the guide sleeve (8) is sealed by in- 8 stalling the sealing ring (10) through two outer sealing ring grooves; a sink = 30 groove is provided in the middle of the top of the orifice plate (14), the ball S valve seat guide sleeve (11) is sleeved in the sink groove; the upper half of the middle hole of the ball valve seat guide sleeve (11) has a larger opening than that of the lower half, and the lower half thereof is in clearance fit with the ball valve seat (12), which has a certain guiding ability for the axial movement of the ball valve seat (12); a cross milling groove is provided at the top of the ball valve seat guide sleeve (11), three milling grooves are evenly distributed on the guide surface of the ball valve seat (12), and the chamber above the steel ball (13) is communicated with the fuel return channel (105) through the ball valve seat (12) and the milling grooves on the ball valve seat guide sleeve (11); the circulating oil channel (101) and the oil inlet channel (102) lead into the nozzle component through the injector body (1) and the orifice plate (14).

2 The electronically controlled common-rail heavy fuel injector according to claim 1, wherein the nozzle component comprises a needle valve guide sleeve (15), a needle valve (16), a needle valve return spring (17), a pressure regulating gasket (18), a body locking nut (19), a needle valve body (20) and a nozzle (22); the needle valve guide sleeve (15) and the needle valve (16) are both cooperated — with the needle valve body (20) through a coupling, the upper and lower sliding surfaces of the needle valve (16) are slidable axially in the middle hole of the needle valve body (20) and the middle hole of the needle valve guide sleeve (15), respectively; both ends of the needle valve return spring (17) press the nee- dle valve guide sleeve (15) and the needle valve (16), respectively, so that the top of the needle valve guide sleeve (15) is pressed against the lower plane of the orifice plate (14), the conical surface of the lower end of the needle valve (16) is pressed against the conical surface of the middle hole of the needle valve body (20); the cylindrical surface of the bottom end of the needle valve body (20) is in & interference fit with the counterbore of the nozzle (22), the nozzle (22) is pro- = 25 vided with a nozzle hole for injecting fuel; the body locking nut (19) connects = the nozzle component to the injector body (1), and presses the top end surface of > the needle valve body (20) against the bottom end of the orifice plate (14); and E the circulating oil channel (101) and the oil inlet channel (102) lead to the mid- 8 dle hole of the needle valve body (20) via the injector body (1) and the orifice LO 3 30 plate (14).

3. The electronically controlled common-rail heavy fuel injector according to claim 2, wherein: the nozzle (22) comprises a nozzle body (222) and an ejector rod (221) cooperated therewith; the nozzle body is interference installed on the needle valve body, the ejector rod is rigidly connected to the head of the needle valve or is processed as a whole with the head of the needle valve; there are two fitting surfaces between the nozzle body and the ejector rod cooperated there- with, the oil chamber between the nozzle body and the ejector rod is divided into three parts: the nozzle upper chamber, the nozzle middle chamber and the nozzle lower chamber, the ejector rod is provided with a central longitudinal hole and a horizontal hole to connect the nozzle upper chamber and the nozzle lower cham- ber, the nozzle hole on the nozzle body is located within the width of the nozzle middle chamber; when the injector is in the spraying state, the nozzle body is staggered with the lower fitting surface of the ejector rod, so that the nozzle lower chamber is connected with the nozzle middle chamber, and when the in- — jectorisin the stopping state, the nozzle body and the lower fitting surface of the ejector rod are attached to each other to disconnect the nozzle lower chamber from the nozzle middle chamber.

4. The electronically controlled common-rail heavy fuel injector according to claim 2 or 3, wherein the length of the nozzle is greater than or egual to 19 mm.

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5. The electronically controlled common-rail heavy fuel injector according to claim 3, wherein: a nozzle locking nut (21) is sleeved at the part where the nee- dle valve body and the nozzle body are combined, the upper end of the nozzle n locking nut (21) is in threaded connection with the needle valve body, the inner O wall of the locking nut tightly sleeves the needle valve body and the nozzle 5 25 — body, and the cone angle and the thickness of the lower end of the locking nut © are designed to match the cone angle of the installation seat surface required by I the injector and the length of the nozzle extending into the cylinder. a

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6. The electronically controlled common-rail heavy fuel injector according to D claim 1, 2 or 3, wherein: the orifice plate (14), the needle valve guide sleeve S 30 — (15), and the needle valve (16) surround and form a pressure control chamber (104), which communicates with the outside through the oil inlet orifice (103)

and the oil outlet orifice (105); the fuel return channel (106) is separated from the oil outlet orifice (105) by a steel ball (13) on the injector body (1); the mixed oil discharging channel (107) is communicated with the ring chamber (110) en- closed by the ring groove (110) on the outside of the middle of the guide sleeve (8) and the sealing ring (10); the cooling oil inlet channel (108) and the cooling fuel return channel (109) are communicated with the oil chamber enclosed by the electromagnet (3), the guide sleeve (8) and the sealing ring (10), and are communicated with each other through the groove hole on the sleeve (7).

7. The electronically controlled common-rail heavy fuel injector according to claim 1, 2 or 3, wherein: a ring groove (110) is provided on the outside of the middle of the guide sleeve (8), a horizontal through hole is provided in the mid- dle of the ring groove leading to the middle hole in the guide sleeve (8); a seal- ing ring groove is provided on both sides of the ring groove; the diameter of the bottom end of the control valve core (9) is larger than the guide section, the — guide section is provided with three ring grooves (111) and the second ring groove is communicated with the horizontal through hole in the middle of the guide sleeve (8); and the control valve core (9), the guide sleeve (8) and the seal- ing ring (10) divide the middle hole of the injector body (1) into three chambers.

8. The electronically controlled common-rail heavy fuel injector according to claim 1, 2 or 3, wherein: the armature (6) and the top thread of the control valve core (9) are fixed by a nut (5). 0 N O N 5 ™ I a a © co O LO N O N