CN116857096A - A low oil return electronically controlled injector with variable injection pattern - Google Patents

Abstract

The invention belongs to the technical field of diesel engines, and discloses a low-oil return electric control oil injector with a variable oil injection rule, which comprises an electromagnetic valve body, an electromagnetic control valve assembly, a control valve body and a needle valve injection assembly; the outer wall of the control valve of the electromagnetic control valve assembly is propped against the inner wall of the control valve body to form cylindrical surface sealing, and a certain gap exists between the outer wall of the needle valve injection assembly and the inner wall of the nozzle. According to the invention, under the rectangular oil injection rule, when a small current is introduced into the electromagnetic control valve assembly, high-pressure fuel flows through the primary control fuel flow path and the oil injection flow path of the needle valve injection assembly; when large current is introduced, high-pressure fuel flows through the primary control fuel flow path, the secondary control fuel flow path and the fuel injection flow path of the needle valve injection assembly; when the boot-shaped fuel injection is performed in a regular injection mode, when small current is introduced, high-pressure fuel flows through a primary control fuel flow path and a fuel injection flow path of a needle valve injection assembly; when a large current is supplied, high-pressure fuel flows through the secondary control fuel flow path and the needle valve injection assembly fuel injection flow path.

Description

A low oil return electronically controlled injector with variable injection pattern

Technical field

The invention belongs to the technical field of diesel engines, and specifically relates to a low-oil-return electronically controlled injector with a variable injection pattern.

Background technique

As an important component of the high-pressure common rail fuel injection system, the electronically controlled injector has the advantages of high control accuracy, strong adjustability, and high energy efficiency. Its injection characteristics directly affect the economy and emission performance of the diesel engine.

In order to achieve ultra-high combustion and ultra-low emissions, people have conducted extensive research on rectangular, slope-shaped, shoe-shaped and other injection regular curves. The study found that the shoe-shaped fuel injection pattern of slow in the early stage, rapid in the mid-term, and fast in the later stage can reduce nitrogen oxide emissions, curb the generation of large amounts of soot and the deterioration of thermal efficiency, and effectively reduce the emissions of diesel engines. However, the existing electronically controlled injector can only achieve a rectangular injection pattern due to its fixed structure. At the same time, it cannot accurately control the needle valve lift during small flow injection, resulting in unstable fuel injection volume, fuel waste, and reduced emission performance.

CN 115387944A discloses a low oil return variable needle valve opening rate electronically controlled injector. The electromagnetic control valve assembly of the electronically controlled injector includes an external control valve and an internal control valve. Different control valves are connected through a solenoid valve. The potential determines the oil return rate of the control chamber above the needle valve and changes the opening speed of the needle valve. However, this patent cannot accurately control the needle valve lift under small flow injection.

In order to improve the performance and efficiency of diesel engines and meet the changes in fuel demand of diesel engines under different working conditions, electronically controlled injectors must adopt more flexible and efficient fuel injection rules.

Contents of the invention

The object of the present invention is to overcome the shortcomings of the prior art and provide a low-oil-return electronically controlled injector with a variable injection pattern that can reduce the amount of oil return and realize flexible and adjustable fuel injection pattern.

The purpose of the present invention is achieved through the following technical solutions:

A low-oil return electronically controlled injector with a variable injection pattern, including from top to bottom a fastening cap, a pressure accumulation chamber, a solenoid valve body, an electromagnetic control valve assembly, a control valve body, and a secondary control chamber , the first-level control cavity and the needle valve injection assembly; the outer wall of the electronically controlled injector is limited and fixed by fastening sleeves and sleeves;

The fastening cap cooperates with the pressure accumulation chamber to form a pressure accumulation chamber for placing high-pressure fuel; the fastening cap is axially provided with a high-pressure oil interface, and the high-pressure oil interface is connected to the pressure accumulation chamber; one end of a high-pressure oil circuit It is connected to the bottom of the pressure accumulation chamber, and the other end is connected to the needle valve injection assembly;

The electromagnetic control valve assembly is located inside the pressure accumulation chamber, the electromagnetic valve body and the control valve body;

The surfaces of the pressure accumulation cavity and the solenoid valve body in contact are respectively provided with grooves inward to form a first cavity; the surface of the solenoid valve body facing the control valve body is provided with grooves inward to form a second cavity; A groove is opened inward on the surface of the secondary control cavity toward the primary control cavity to form a fourth cavity;

The electromagnetic control valve assembly includes an electromagnet, an armature, a limit valve and a control valve in order from top to bottom; the needle valve injection assembly includes a slider, a needle valve, a nozzle, and a nozzle hole in order from top to bottom; the control The outer wall of the valve abuts the inner wall of the control valve to form a cylindrical seal, the outer wall of the needle valve contacts the inner wall of the primary control chamber and forms a cylindrical seal, and there is a certain gap between the outer wall of the needle valve and the inner wall of the nozzle;

Further, the electromagnet and the armature are installed in the first cavity, the control valve return spring penetrates the inside of the electromagnet, the limit valve is located in the second cavity, and the limit valve return spring is sleeved on its outer wall; The control valve is located in the control valve body and includes an upward protruding cylinder and a flange located on the bottom layer that protrudes from the upper cylinder along the circumferential direction. Its protruding cylinder passes through the limit valve and is threadedly connected to the armature; the control valve is controlled by the control valve The limit valve is in the lower limit position due to the elastic force of the return spring, and the limit valve is seated on the control valve body due to the elastic force of the return spring of the limit valve;

The needle valve injection assembly includes a slider, a needle valve, a nozzle, and a nozzle hole in order from top to bottom; the slider is located in the fourth cavity, and its outer wall is covered with a slider return spring; the inner wall of the fourth cavity and the slider The space formed by the cooperation serves as the secondary control cavity; the slider is seated on the primary control cavity under the combined action of hydraulic pressure and the elastic force of the slider return spring. The bottom of the primary control cavity is connected to the top wall of the nozzle, and a plurality of nozzle holes are opened at the bottom of the nozzle;

The outer wall of the needle valve contacts the inner wall of the primary control cavity and forms a cylindrical seal. There is a certain gap between the outer wall of the needle valve and the inner wall of the nozzle; the needle valve return spring is sleeved and raised on the top of the needle valve; The space formed by the cooperation between the inner wall of the primary control cavity, the bottom wall of the slider and the needle valve serves as the primary control cavity; the needle valve is seated on the valve seat processed by the nozzle due to the combined action of hydraulic pressure and the elastic force of the needle valve return spring;

There is also a needle valve annular cavity between the inner wall of the nozzle and the outer wall of the needle valve, and the needle valve annular cavity is connected with the high-pressure oil circuit; there is a certain gap between the lower end of the needle valve and the nozzle to form a pressure chamber, and the pressure chamber is The chamber is connected to the nozzle hole;

Along the circumferential direction of the control valve, there are 4 annular grooves on the outer wall of the control valve. Each annular groove cooperates with the inner wall of the control valve to form a high-pressure chamber, a primary annular chamber, a secondary annular chamber and a low-pressure chamber respectively;

The control valve body is equipped with a low-pressure oil line, one end of the low-pressure oil line is connected to the low-pressure chamber, and the other end is connected to the external low-pressure oil tank; the control valve is equipped with a control valve oil line, a two-way hole in the high-pressure chamber, a two-way hole in the primary annular cavity, and a two-way hole in the secondary annular cavity. , the control valve oil circuit is connected to the high-pressure chamber, the primary annular cavity and the secondary annular cavity respectively through the two-way hole of the high-pressure chamber, the two-way hole of the primary annular cavity, and the two-way hole of the secondary annular cavity; the control valve cavity is also equipped with a high-pressure angle at an angle The oil inlet orifice of the chamber, the two-way orifice of the first-level control chamber, the two-way orifice of the second-level control chamber, one end of the oil inlet orifice of the high-pressure chamber is connected to the high-pressure oil circuit, and the other end is connected to the high-pressure chamber. The first-level control chamber One end of the bidirectional orifice (i.e., the inlet) is connected to the primary annular cavity, and the other end is connected to the primary control cavity after passing through the interior of the secondary control cavity. One end (i.e., the inlet) of the bidirectional orifice of the secondary control cavity is connected to the secondary annular ring. cavity, and the other end is connected to the secondary control cavity.

Among them, the primary control fuel flow path: enters the low pressure through the bidirectional orifice of the primary control chamber, the primary annular chamber, the bidirectional hole of the primary annular chamber, the control valve oil path, and the gap between the control valve and the secondary control chamber. Oil line;

Secondary control fuel flow path: enters the low-pressure oil path through the bidirectional orifice of the secondary control chamber and the low-pressure chamber;

The fuel injection flow path of the needle valve injection assembly: enters the pressure chamber through the gap between the needle valve annular cavity, the outer wall of the needle valve and the inner wall of the nozzle.

The low oil return electronically controlled injector has the following two injection modes when injecting regularly:

Low current fuel injection mode:

When a small current is supplied to the solenoid control valve assembly, the control valve is raised to the limit position, the plane seal between the lower end of the control valve and the upper end surface of the secondary control cavity is opened, and the needle valve of the needle valve injection assembly is raised to the limit position. At this position, high-pressure fuel flows through the primary control fuel flow path and the needle valve injection assembly fuel injection flow path;

High current fuel injection mode:

When a large current is supplied to the solenoid control valve assembly, the control valve drives the limit valve to lift to the upper limit position of the limit valve. The needle valve of the needle valve injection assembly drives the slider to lift to the upper limit position. High-pressure fuel flows through the first stage. Control fuel flow path, secondary control fuel flow path and needle valve injection assembly fuel injection flow path;

When the low oil return electronically controlled injector injects regularly with shoe-shaped injection:

First, apply a small current to the solenoid control valve assembly in the low current fuel injection mode, and high-pressure fuel flows through the primary control fuel flow path and the injection flow path of the needle valve injection assembly; during the fuel injection process, pass a large current to the solenoid control valve assembly. Current, the control valve drives the limit valve to lift to the upper limit position of the limit valve. The needle valve of the needle valve injection assembly drives the slider to lift to the upper limit position. High-pressure fuel flows through the secondary control fuel flow path and the needle valve injection assembly. Oil flow path.

Furthermore, the low oil return electronically controlled injector has the following two injection modes during regular rectangular injection:

Low current fuel injection mode:

When a small current is supplied to the solenoid control valve assembly, the control valve is lifted to the limit due to hydraulic pressure, electromagnetic force and elastic force. The control valve no longer rises, and the high-pressure fuel in the first-level control chamber is controlled to flow through the first-level control fuel flow path, and then the needle valve that controls the needle valve injection assembly is lifted to the limit position, and the high-pressure fuel enters the pressure chamber through the injection flow path of the needle valve injection assembly, and then sprays out from the nozzle hole, forming a rectangular fuel injection regular curve;

High current fuel injection mode:

When a large current is passed through the solenoid control valve assembly, the control valve is lifted to the limit position due to hydraulic pressure, electromagnetic force and elastic force, and then drives the limit valve to continue to rise until it reaches the upper limit position of the limit valve, controlling the first-level control chamber. The high-pressure fuel in the injection chamber flows through the primary control fuel flow path and the high-pressure fuel in the secondary control chamber flows through the secondary control fuel flow path. Then the needle valve that controls the needle valve injection assembly is lifted to the limit position, and then the needle valve drives The slider rises together until the slider reaches its upper limit position. High-pressure fuel enters the pressure chamber through the injection flow path of the needle valve injection assembly, and then sprays out from the nozzle hole, forming a rectangular injection regular curve;

When the low oil return electronically controlled injector injects regularly with shoe-shaped injection:

First, according to the low current fuel injection mode, a small current is passed to the solenoid control valve assembly to cause high-pressure fuel to be sprayed from the nozzle hole;

During the fuel injection process, a large current is passed through the solenoid control valve assembly. The control valve is lifted to the limit due to the action of hydraulic pressure, electromagnetic force and elastic force, and then the limit valve is driven to continue to rise until it reaches the upper limit position of the limit valve. Control the second The high-pressure fuel in the first-stage control chamber flows through the second-stage control fuel flow path, and the needle valve that controls the needle valve injection assembly is lifted to the limit position. Then the needle valve drives the slider to rise together until the slider reaches its upper limit position, and the high-pressure fuel The fuel injection flow path enters the pressure chamber through the needle valve injection assembly, and then sprays out from the injection hole.

Further, the upper limit position of the needle valve is the lower end surface of the slider; the upper limit position of the control valve is the lower end surface of the limit valve, and the upper limit position of the limit valve is the second cavity. Top surface; the upper limit position of the slider is the top surface of the fourth cavity.

Further, the lower edge of the outlet of the high-pressure chamber oil inlet throttle hole is flush with the lower edge of the high-pressure chamber, and the outlet diameter of the high-pressure chamber oil inlet throttle hole is equal to the distance between the flange of the control valve and the lower end face of the limit valve. The distance from the upper edge of the chamber to the lower edge of the high-pressure chamber is greater than the outlet diameter of the oil inlet orifice of the high-pressure chamber, and the diameter of the two-way hole in the high-pressure chamber is equal to the distance from the upper edge of the high-pressure chamber to the lower edge of the high-pressure chamber.

Further, the upper edge of the two-way orifice inlet of the first-level control chamber is flush with the upper edge of the first-level annular cavity, and the distance between the lower edge of the two-way orifice inlet of the first-level control chamber and the lower edge of the first-level annular cavity is greater than the control The maximum lift distance of the valve, the diameter of the two-way orifice inlet of the primary control chamber is equal to the distance between the flange of the control valve and the lower end face of the limit valve; the diameter of the two-way orifice of the primary annular cavity is larger than the inlet of the two-way orifice of the primary control chamber diameter, the distance from the upper edge of the primary ring chamber to the lower edge of the high-pressure chamber is greater than the maximum lift distance of the control valve.

Further, the lower edge of the two-way orifice entrance of the secondary control chamber is flush with the lower edge of the secondary annular cavity, and the diameter of the two-way orifice entrance of the secondary control chamber is equal to the distance between the flange of the control valve and the lower end surface of the limit valve. The distance between the lower edge of the two-way orifice inlet of the secondary control chamber and the upper edge of the low-pressure chamber is equal to the distance between the flange of the control valve and the lower end face of the limit valve; the upper edge of the secondary ring cavity to the secondary ring The distance between the lower edges of the chamber is greater than the inlet diameter of the two-way throttle hole in the secondary control chamber, and the diameter of the two-way hole in the secondary annular chamber is equal to the distance between the upper edge of the secondary annular chamber and the lower edge of the secondary annular chamber.

Furthermore, the distance between the upper edge of the low-pressure chamber and the lower edge of the secondary ring chamber is equal to the distance between the flange of the control valve and the lower end face of the limit valve, and the distance between the lower end face of the electromagnet and the upper end face of the armature is greater than that of the control valve. The maximum lift distance and the cross-sectional area of the control valve oil circuit are greater than the sum of the cross-sectional area of the two-way orifice inlet of the secondary control chamber and the cross-sectional area of the two-way orifice inlet of the primary control chamber.

Compared with the existing technology, the beneficial effects brought by the technical solution of the present invention are:

1. The present invention uses a two-way oil circuit in the control chamber to supply and return oil to the control chamber. The structure is simple and easy to process and maintain. After the electromagnetic control valve is energized, the oil inlet throttle hole of the high-pressure chamber is disconnected from the high-pressure chamber, reducing the amount of oil return. , improve the overall machine efficiency and economy.

2. Adjust the needle valve lift by adjusting the solenoid control valve and needle valve injection assembly to change the flow cross-sectional area inside the injector, thereby changing the amount of fuel injected into the cylinder per unit time by the injector, achieving a flexible and variable injection regular curve. It meets the needs of different working conditions of diesel engines, helps improve the combustion effect in the diesel engine cylinder, and reduces pollutant emissions.

Description of the drawings

Figure 1 is a schematic structural diagram of the low oil return electronically controlled fuel injector according to the present invention;

Figure 2 is a schematic structural diagram of the solenoid control valve assembly in Figure 1;

Figure 3 is a schematic structural diagram of the needle valve injection assembly in Figure 1;

4 is a cross-sectional view of the low oil return electronically controlled injector without showing the solenoid control valve assembly and the needle valve injection assembly.

In the picture:

1: High-pressure oil interface; 2: Fastening cap; 3: Pressure accumulation chamber; 4: Solenoid valve body; 5: Solenoid control valve assembly; 6: Control valve body; 7: Secondary control chamber; 8: Needle valve Injection assembly; 9: Pressure accumulator chamber; 10: Fastening sleeve; 11: High-pressure oil circuit; 12: Sleeve; 13: Primary control chamber; 101: First chamber; 102: Second chamber; 103: The third cavity; 104: the fourth cavity; 105: the fifth cavity; 106: the sixth cavity; 501: electromagnet; 502: armature; 503: limit valve; 504: control valve; 505: high pressure chamber ;506: Two-way orifice in the primary annular cavity; 507: Two-way orifice in the primary control cavity; 508: Two-way orifice in the secondary annular cavity; 509: Two-way orifice in the secondary control cavity; 510: Low pressure chamber; 511: Control valve Return spring; 512: limit valve return spring; 513: two-way hole in high-pressure chamber; 514: oil inlet orifice in high-pressure chamber; 515: primary annular chamber; 516: control valve oil circuit; 517: secondary annular chamber; 518 : Low-pressure oil circuit; 801: Secondary control chamber; 802: First-level control chamber; 803: Needle valve; 804: Nozzle; 805: Needle valve ring chamber; 806: Nozzle hole; 807: Slider return spring; 808: Slider Block; 809: needle valve return spring; 810: pressure chamber.

Detailed ways

In order to make the purpose, technical solutions, beneficial effects and significant progress of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention are clearly and completely described below in conjunction with the drawings provided in the examples of the present invention. Obviously, all These described embodiments are only some of the embodiments of the present invention, not all of them; based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without making creative efforts, All belong to the protection scope of the present invention.

In the description of this application, unless otherwise expressly stated and limited, the terms "first", "second" and "third" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance; terms "Multiple" refers to two or more; unless otherwise specified or stated, the terms "connection", "fixed", etc. should be understood in a broad sense. For example, "connection" can be a fixed connection or a detachable connection. Connection, or integral connection, or electrical connection; "connection" can be directly connected, or indirectly connected through an intermediary. For those of ordinary skill in the art, the specific meanings of the above terms in this application can be understood according to specific circumstances.

As shown in Figure 1, a low-oil return electronically controlled injector with a variable injection pattern consists of a fastening cap 2, a pressure accumulation chamber 3, a solenoid valve body 4, and an solenoid control valve assembly 5 from top to bottom. , control valve body 6, secondary control cavity 7, primary control cavity 13 and needle valve injection assembly 8.

The fastening cap 2 is tightly engaged with the top end of the pressure accumulation chamber 3 and the outer wall located at the upper part, and the inner wall of the fastening cap 2 is threadedly connected to the outer surface of the upper part of the pressure accumulation chamber 3, and in A sealing gasket is provided between the contact surface of the fastening cap 2 and the pressure accumulation chamber 3 to increase sealing; the pressure accumulation chamber 3 has a hollow cylindrical space, and the fastening cap 2 and the pressure accumulation chamber The bodies 3 cooperate to form a pressure accumulation chamber 9 . The fastening cap 2 is axially provided with a high-pressure oil interface 1, and the high-pressure oil interface 1 is connected to the pressure accumulation chamber 9. A high-pressure oil path 11 is provided in the pressure accumulation chamber 3. One end of the high-pressure oil path 11 is located at the bottom of the pressure accumulation chamber 9 and is connected to the pressure accumulation chamber 9. The high-pressure oil path 11 passes through the solenoid valve body in turn. 4. The control valve body 6, the secondary control cavity 7, the primary control cavity 13, and the nozzle 804 arrive at the needle valve annular cavity 805. A fastening sleeve 10 tightly fits around part of the outer wall of the pressure accumulation chamber 3, the outer wall of the solenoid valve body 4, and part of the outer wall of the control valve body 6. A sleeve 12 tightly fits around part of the outer wall of the control valve body 6. , the outer wall of the secondary control chamber 7 , the outer wall of the primary control chamber 13 and the outer wall of the needle valve injection assembly 8 .

As shown in Figure 4, the surfaces where the pressure accumulation chamber 3 and the solenoid valve body 4 abut are respectively provided with grooves inward, thereby forming a first cavity inside the pressure accumulation chamber 3 and the solenoid valve body 4. Body 101. The solenoid valve body 4 has an inward groove on the surface that contacts the control valve body 6 to form a second cavity 102 . The control valve body 6 has a through hole penetrating along its central axis to form a third cavity 103 (Through the control valve body 6). The secondary control cavity 7 has a groove formed inward on the surface that contacts the primary control cavity 13 to form a fourth cavity 104. The primary control cavity 13 has a through hole passing through it along its central axis as a through hole. As for the fifth cavity 105, the nozzle 804 of the needle valve injection assembly 8 has a funnel-shaped groove along its central axis as the sixth cavity 106. Among them, the first and second cavities are connected through a through hole, the second and third cavities are connected through, and the fourth and fifth cavities are connected through. The diameter of the second cavity is larger than the diameter of the third cavity so that the limit valve 503 can be seated. on the upper surface of the control valve body 6.

The solenoid control valve assembly 5 (see the upper circle part in Figure 1) is vertically installed in the pressure accumulation chamber 3, the solenoid valve body 4 and the control valve along the central axis of the low oil return electronically controlled injector. The interior of the valve body 6, as shown in Figure 2, includes an electromagnet 501, an armature 502, a limit valve 503 and a control valve 504 from top to bottom. The limit valve return spring 512 and the control valve return spring 511 are centrally arranged in the Inside the solenoid control valve assembly 5. The control valve 504 is located in the third cavity. The outer wall of the control valve 504 is against the inner wall of the third cavity (ie, the inner wall of the control valve body 6) to form a cylindrical seal. The lower end surface of the control valve 504 is in contact with the secondary control valve. The upper end surface of the cavity 7 is in close contact, forming a plane seal to block the communication between the control valve oil path 516 and the low-pressure oil path 518 .

The electromagnet 501 and the armature 502 are installed in the first cavity, wherein the outer surface of the electromagnet 501 is against the groove formed at the bottom of the pressure accumulation cavity 3 , and the armature 502 is located in the groove formed by the solenoid valve body 4 inside the groove. And the electromagnet 501 penetrates a cylindrical cavity along its central axis for placing the control valve return spring 511. One end of the control valve return spring 511 is pressed against the bottom of the pressure accumulation chamber 3 , and the other end is pressed against the upper surface of the armature 502 .

The limit valve 503 is located in the second cavity. Both the limit valve 503 and the armature 502 have through holes penetrating along their central axial directions, and the inner wall of the through hole of the armature 502 has threads. The control valve 504 is a two-layer boss structure, including an upwardly protruding cylinder and a flange on the bottom layer that protrudes from the upper cylinder in the circumferential direction. The upper surface of the flange is opposite to the lower end surface of the limit valve 503, and its top is The upward protruding cylinder passes through the through hole of the limit valve 503 and is threadedly connected to the through hole of the armature 502. The control valve 504 is in the lower limit position due to the elastic force of the control valve return spring 511. The size of the through holes of the limit valve 503 and the armature 502 are adapted to the size of the upwardly protruding cylinder of the control valve 504 .

The limit valve 503 has a two-layer boss structure, and a limit valve return spring 512 is set on the outer wall of the uppermost boss. The lower end of the limit valve return spring 512 is against the lower boss of the limit valve 503. , the upper end is against the top wall of the second cavity, and the lower end surface of the limit valve 503 reaches the upper end surface of the control valve body 6 , so that it is seated on the control valve body 6 due to the elastic force of the limit valve return spring 512 .

As shown in Figure 3, the needle valve injection assembly 8 includes a slider 808, a needle valve 803, a nozzle 804, and a nozzle hole 806 in order from top to bottom. The slider 808 is located in the fourth cavity, and a slider return spring 807 is set on its outer wall. The lower end of the slider return spring 807 abuts the lower boss of the slider 808, and the upper end abuts the fourth cavity. Top wall; the space formed by the cooperation between the inner wall of the fourth cavity and the slider 808 serves as the secondary control chamber 801; the lower end of the slider 808 is against the upper end surface of the primary control chamber 13, so that the slider 808 is subject to hydraulic pressure and the slider return spring 807 elastic force and sits on the first-level control cavity 13. The bottom of the primary control cavity 13 is connected to the top wall of the nozzle 804 , and a plurality of nozzle holes 806 are opened at the bottom of the nozzle 804 . The needle valve 803 penetrates the fifth and sixth cavities in sequence. The outer wall of the needle valve 803 contacts the inner wall of the fifth cavity (that is, the inner wall of the secondary control cavity 7) and forms a cylindrical seal. There is a certain gap between the outer wall of the valve 803 and the inner wall of the nozzle 804 for flowing liquid. The top of the needle valve 803 has a columnar protrusion, and a needle valve return spring 809 is set on the outer surface of the columnar protrusion. The lower end of the needle valve return spring 809 is against the top of the needle valve 803, and the other end is against the first level. The control cavity 13 is a platform extending from its top end toward the central axis. The space formed by the cooperation between the inner wall of the primary control cavity 13, the bottom wall of the slider 808 and the needle valve 803 serves as the primary control cavity 802. The needle valve 803 is seated on the valve seat processed by the nozzle 804 due to the combined action of the hydraulic pressure and the elastic force of the needle valve return spring 809.

In the sixth cavity, an annular cavity is provided between the inner wall of the nozzle 804 and the outer wall of the needle valve 803 as the needle valve annular cavity 805 , and the needle valve annular cavity 805 is connected to the high-pressure oil circuit 11 . There is a certain gap between the lower end of the needle valve 803 and the nozzle 804 to form a pressure chamber 810, and the pressure chamber 810 is connected to the nozzle hole 806.

During installation, the pressure accumulation chamber 3, solenoid valve body 4, control valve body 6, secondary control chamber 7, primary control chamber 13 and nozzle 804 are installed from top to bottom, through the fastening sleeve 10 and the sleeve 12 Limit and fix.

Along the circumferential direction of the control valve 504, there are 4 annular grooves on the outer wall of the control valve 504. Each annular groove cooperates with the inner wall of the control valve body 6 to respectively form a high-pressure chamber 505, a primary annular chamber 515, and a secondary annular chamber. 517 and low pressure chamber 510. A low-pressure oil path 518 is provided in the control valve body 6. One end of the low-pressure oil path 518 is connected to the low-pressure chamber 510, and the other end is connected to an external low-pressure oil tank. The control valve 504 is provided with a control valve oil path 516, a high-pressure chamber bidirectional hole 513, and a first-level annular chamber. The two-way hole 506 and the two-way hole 508 of the secondary annular cavity. The control valve oil path 516 communicates with the high-pressure chamber 505 and the first-level annular cavity respectively through the two-way hole 513 of the high-pressure cavity, the two-way hole 506 of the primary annular cavity and the two-way hole 508 of the secondary annular cavity. cavity 515 and secondary ring cavity 517. The cavity of the control valve 504 is also provided with a high-pressure chamber oil inlet orifice 514, a first-level control chamber two-way orifice 507, and a second-level control chamber two-way orifice 509. One end of the high-pressure chamber oil inlet orifice 514 is connected to the high-pressure oil. Road 11, the other end is connected to the high-pressure chamber 505. The lower edge of the outlet of the high-pressure chamber oil inlet throttle hole 514 is flush with the lower edge of the high-pressure chamber 505. The outlet diameter of the high-pressure chamber oil inlet throttle hole 514 is equal to the flange of the control valve 504 and The distance between the lower end faces of the limit valve 503 and the distance from the upper edge of the high-pressure chamber 505 to the lower edge of the high-pressure chamber 505 is greater than the outlet diameter of the oil inlet throttle hole 514 of the high-pressure chamber, and the diameter of the two-way hole 513 of the high-pressure chamber is equal to the distance from the upper edge of the high-pressure chamber 505 to The distance from the lower edge of the high-pressure chamber 505; one end (i.e., the inlet) of the first-level control cavity two-way throttle hole 507 is connected to the first-level annular cavity 515, and the other end is connected to the first-level control cavity 802 after passing through the interior of the second-level control cavity 7. The upper edge of the inlet of the two-way orifice 507 of the first-level control chamber is flush with the upper edge of the first-level annular cavity 515. The distance between the lower edge of the inlet of the two-way orifice 507 of the first-level control chamber and the lower edge of the first-level annular cavity 515 is greater than the control The maximum lift distance of the valve 504, the inlet diameter of the two-way throttle hole 507 of the first-level control chamber is equal to the distance between the flange of the control valve 504 and the lower end surface of the limit valve 503; the diameter of the two-way hole 506 of the first-level annular cavity is larger than that of the first-level control cavity The inlet diameter of the two-way throttle hole 507 and the distance from the upper edge of the primary ring chamber 515 to the lower edge of the high-pressure chamber 505 are greater than the maximum lift distance of the control valve 504. One end (i.e., the inlet) of the two-way throttle hole 509 of the secondary control chamber is connected to the secondary annular chamber 517, and the other end is connected to the secondary control chamber 801. Wherein, the lower edge of the inlet of the two-way throttling hole 509 of the secondary control chamber is flush with the lower edge of the secondary annular cavity 517, and the diameter of the inlet of the two-way throttling hole 509 of the secondary control chamber is equal to the flange of the control valve 504 and the limit valve 503 The distance between the lower end surfaces; the distance between the lower edge of the inlet of the two-way throttle hole 509 of the secondary control chamber and the upper edge of the low pressure chamber 510 is equal to the distance between the flange of the control valve 504 and the lower end surface of the limit valve 503; The distance between the upper edge of the annular cavity 517 and the lower edge of the secondary annular cavity 517 is greater than the inlet diameter of the two-way throttle hole 509 of the secondary control cavity, and the diameter of the two-way orifice 508 of the secondary annular cavity is equal to the upper edge of the secondary annular cavity 517 to the secondary annulus. The distance between the lower edges of cavity 517.

The distance between the upper edge of the low-pressure chamber 510 and the lower edge of the secondary ring chamber 517 is equal to the distance between the flange of the control valve 504 and the lower end surface of the limit valve 503, and the distance between the lower end surface of the electromagnet 501 and the upper end surface of the armature 502 It is greater than the maximum lift distance of the control valve 504, and the cross-sectional area of the control valve oil passage 516 is greater than the sum of the inlet cross-sectional area of the two-way orifice 509 of the secondary control chamber and the inlet cross-sectional area of the two-way orifice 507 of the primary control chamber.

The low oil return electronically controlled injector can realize two fuel injection modes of rectangular and shoe-shaped injection regular curve shapes. When performing injection with a rectangular fuel injection pattern, there are two situations: one is to pass a small current to the solenoid control valve assembly 5, and the other is to pass a large current to the solenoid control valve assembly 5. When performing shoe-shaped fuel injection regular injection, first pass a small current to the solenoid control valve assembly 5, and then pass a large current to the solenoid control valve assembly 5.

Fuel injection pattern of rectangular fuel injection pattern with small current:

When a small current is passed through the electromagnetic control valve assembly 5, the sum of the electromagnetic force on the armature 502 and the hydraulic force on the control valve 504 is greater than the elastic force of the control valve return spring 511 located on the upper surface of the armature, and is less than the elastic force of the control valve return spring 511 and The control valve 504 is lifted upward by the combined action of the hydraulic pressure, the electromagnetic force of the armature 502 and the elastic force of the control valve return spring 511, until the flange of the control valve 504 reaches the bottom of the limit valve 503. end face, the control valve 504 no longer rises, and the plane seal between the lower end of the control valve 504 and the upper end face of the secondary control chamber 7 is opened. At this time, the control valve 504 moves upward, causing the high-pressure chamber oil inlet throttle hole 514 to connect with the high-pressure chamber 505 Staggered, so that the side wall of the control valve 504 and the control valve body 6 form a cylindrical seal to prevent high-pressure fuel from entering the control valve oil circuit 516 through the high-pressure chamber 505 and the two-way hole 513 of the high-pressure chamber; the high-pressure fuel in the first-level control chamber 802 passes through the first-level control chamber 802. The two-way throttle hole 507 of the control chamber, the first-level annular cavity 515, the two-way hole 506 of the first-level annular cavity, the control valve oil path 516, the gap between the control valve 504 and the second-level control chamber 7 enter the low-pressure oil path 518; at this time , the fuel pressure in the first-level control chamber 802 continues to decrease until the hydraulic pressure at the lower end of the needle valve 803 is greater than the sum of the hydraulic pressure at the upper end of the needle valve 803 and the elastic force of the needle valve return spring 809, and the needle valve 803 begins to lift until the upper end of the needle valve 803 When it reaches the lower end of the slider 808, that is, the needle valve 803 is limited to the lower end surface of the slider and no longer rises, the high-pressure fuel enters the pressure chamber 810 through the needle valve annular cavity 805, the gap between the outer wall of the needle valve 803 and the inner wall of the nozzle 804, and then passes from The nozzle hole 806 ejects.

Fuel injection pattern with large current rectangular fuel injection pattern:

When a large current is supplied to the electromagnetic control valve assembly 5, the sum of the electromagnetic force on the armature 502 and the hydraulic force on the control valve 504 is greater than the sum of the elastic force of the control valve return spring 511 and the limit valve return spring 512, and the control valve 504 It is lifted upward due to the combined action of the hydraulic pressure, the electromagnetic force of the armature 502 and the elastic force of the control valve return spring 511. The flange of the control valve 504 contacts the lower end of the limit valve 503 and drives the limit valve 503 to rise together until the limit valve 503 reaches its upper limit position (that is, the upper end surface of the limit valve 503 reaches the top surface of the second cavity), both the control valve 504 and the limit valve 503 no longer rise. The plane seal is opened. At this time, the control valve 504 moves upward, causing the high-pressure chamber oil inlet throttle hole 514 and the high-pressure chamber 505 to be staggered. At the same time, the side wall of the control valve 504 and the control valve body 6 form a cylindrical seal. In the first-level control chamber 802 The high-pressure fuel enters the low pressure through the first-level control cavity bidirectional orifice 507, the first-level annular cavity 515, the first-level annular cavity two-way hole 506, the control valve oil line 516, the gap between the control valve 504 and the second-level control cavity 7 In the oil circuit 518, the high-pressure fuel in the secondary control chamber 801 enters the low-pressure oil circuit 518 through the two-way orifice 509 and the low-pressure chamber 510 of the secondary control chamber. The fuel pressure in the primary control chamber 802 and the secondary control chamber 801 continues to decrease. Until the hydraulic pressure at the lower end of the needle valve 803 is greater than the sum of the hydraulic pressure at the upper end of the needle valve 803 and the elastic force of the needle valve return spring 809, the needle valve 803 begins to lift until the upper end of the needle valve 803 reaches the lower end of the slider 808, and the needle valve 803 stops rising. , until the sum of the hydraulic pressure at the lower end of the needle valve 803 and the hydraulic pressure at the lower end of the slider 808 is greater than the hydraulic pressure at the upper end of the needle valve 803, the hydraulic pressure at the upper end of the slider 808, the elastic force of the needle valve return spring 809 and the elastic force of the slider return spring 807. And, the needle valve 803 drives the slider 808 to rise together, until the slider 808 reaches its upper limit position (that is, the upper end surface of the slider 808 contacts the top surface of the fourth cavity), the needle valve 803 and the slider 808 no longer rise, and the high-pressure fuel It enters the pressure chamber 810 through the needle valve annular cavity 805 and the gap between the needle valve 803 and the nozzle 804, and is ejected from the nozzle hole 806.

Fuel injection pattern of shoe-shaped injection pattern:

First, a small current is passed through the electromagnetic control valve assembly 5. The sum of the electromagnetic force on the armature 502 and the hydraulic force on the control valve 504 is greater than the elastic force of the control valve return spring 511, but less than the elastic force of the control valve return spring 511 and the limit valve return spring 512. The control valve 504 is lifted upward by the combined action of the hydraulic pressure, the electromagnetic force of the armature 502 and the elastic force of the control valve return spring 511 until the upper surface of the flange of the control valve 504 contacts the lower end of the limit valve 503. 504 no longer rises, the plane seal between the lower end of the control valve 504 and the upper end surface of the secondary control chamber 7 is opened, and at the same time, the side wall of the control valve 504 and the control valve body 6 form a cylindrical seal, resulting in the high pressure chamber oil inlet throttle hole 514 It is staggered with the high-pressure chamber 505 so that the side wall of the control valve 504 and the control valve body 6 form a cylindrical seal to prevent high-pressure fuel from entering the control valve oil circuit 516 through the high-pressure chamber 505 and the two-way hole 513 of the high-pressure chamber. The fuel enters the low-pressure oil circuit through the bidirectional orifice 507 of the primary control chamber, the primary annular cavity 515, the bidirectional hole 506 of the primary annular cavity, the control valve oil circuit 516, and the gap between the control valve 504 and the secondary control cavity 7 518. The fuel pressure in the first-level control chamber 802 continues to decrease until the hydraulic pressure at the lower end of the needle valve 803 is greater than the sum of the hydraulic pressure at the upper end of the needle valve 803 and the elastic force of the needle valve return spring 809. The needle valve 803 begins to lift until the needle valve 803 The upper end reaches the lower end of the slider 808, the needle valve 803 no longer rises, and the high-pressure fuel enters the pressure chamber 810 through the needle valve annular cavity 805, the gap between the needle valve 803 and the nozzle 804, and is sprayed out from the nozzle hole 806;

As the fuel injection process proceeds, a large current is passed through the electromagnetic control valve assembly 5. The sum of the electromagnetic force of the armature 502 and the hydraulic force on the control valve 504 is greater than the sum of the elastic force of the control valve return spring 511 and the limit valve return spring 512. , the control valve 504 drives the limit valve 503 to rise together, until the limit valve 503 reaches its upper limit position, both the control valve 504 and the limit valve 503 no longer rise. At this time, the two-way orifice 509 entrance of the secondary control chamber (i.e. connected The seal at one end of the secondary annular cavity 517 opens as the control valve 504 rises. The high-pressure fuel in the secondary control cavity 801 enters the low-pressure oil circuit 518 through the bidirectional orifice 509 and the low-pressure cavity 510 of the secondary control cavity. The fuel pressure in the control chamber 801 continues to decrease until the sum of the hydraulic pressure at the lower end of the needle valve 803 and the hydraulic pressure at the lower end of the slider 808 is greater than the hydraulic pressure at the upper end of the needle valve 803, the hydraulic pressure at the upper end of the slider 808, and the elastic force of the needle valve return spring 809. Together with the elastic force of the slider return spring 807, the needle valve 803 drives the slider 808 to rise together, until the slider 808 reaches its upper limit position, the needle valve 803 and the slider 808 no longer rise, and high-pressure fuel is sprayed from the nozzle hole 806.

After the injection mode ends, the solenoid control valve assembly 5 stops energizing, and the limit valve 503 is seated on the control valve body 6 due to the elastic force of the limit valve return spring 512 (that is, the lower end of the limit valve 503 reaches the upper end surface of the control valve body 6 ), the control valve 504 is seated on the secondary control chamber 7 due to the combined action of hydraulic pressure and the elastic force of the control valve return spring 511. The high-pressure chamber oil inlet throttle hole 514 is connected to the high-pressure chamber 505, and the primary control chamber bidirectional throttle hole 507 is connected to the primary annular cavity 515, and the two-way orifice 509 of the secondary control cavity is connected to the secondary annular cavity 517. The lower end of the control valve 504 and the upper end surface of the secondary control cavity 7 form a plane seal to block the control valve oil path 516 and the low-pressure oil. The high-pressure fuel in the pressure accumulation chamber 9 enters the control valve oil line 516 through the high-pressure oil line 11, the high-pressure chamber oil inlet orifice 514, the high-pressure chamber 505, and the high-pressure chamber two-way hole 513. The high-pressure fuel in the control valve oil line 516 The fuel passes through the two-way hole 506 of the primary annular cavity, the primary annular cavity 515, and the two-way throttle hole 507 of the primary control cavity to supplement the high-pressure fuel in the primary control cavity 802. 517. The two-way orifice 509 of the secondary control chamber replenishes the high-pressure fuel in the secondary control chamber 801. The fuel pressure in the primary control chamber 802 and the secondary control chamber 801 increases. The slider 808 is affected by the hydraulic pressure and the slider return spring. The needle valve 803 is seated on the valve seat processed by the nozzle 804 due to the combined action of the hydraulic pressure and the elastic force of the needle valve return spring 809, and the fuel injection is completed.

In addition, it should be understood that although this specification is described in terms of implementations, not each implementation only contains an independent technical solution. This description is only for the sake of clarity. Those skilled in the art should take the description as a whole. The technical solutions in the embodiments can also be appropriately combined to form other implementations that can be understood by those skilled in the art.

Claims (6)

1. A low-oil return electronically controlled injector with a variable injection pattern, which is characterized in that it includes a fastening cap (2), a pressure accumulation chamber (3), and a solenoid valve body (4) from top to bottom. , solenoid control valve assembly (5), control valve body (6), secondary control cavity (7), primary control cavity (13) and needle valve injection assembly (8); the outer wall of the electronically controlled injector Limit and fix through fastening sleeve (10) and sleeve (12); The fastening cap (2) cooperates with the pressure accumulation chamber (3) to form a pressure accumulation chamber (9) for placing high-pressure fuel; the fastening cap (2) has a high-pressure oil interface (1) axially opened, The high-pressure oil interface is connected to the pressure accumulation chamber (9); one end of the high-pressure oil line (11) is connected to the bottom of the pressure accumulation chamber (9), and the other end is connected to the needle valve injection assembly (8); The solenoid control valve assembly (5) is located inside the pressure accumulation chamber (3), the solenoid valve body (4) and the control valve body (6); The contact surfaces of the pressure accumulation cavity (3) and the solenoid valve body (4) are respectively opened with grooves inward to form a first cavity (101); the solenoid valve body (4) faces the control valve body (6) The surface of the secondary control cavity (7) is provided with a groove inward to form a second cavity (102); the surface of the secondary control cavity (7) facing the primary control cavity (13) is provided with a groove inward to form a fourth cavity ( 104); The electromagnetic control valve assembly (5) includes an electromagnet (501), an armature (502), a limit valve (503) and a control valve (504) from top to bottom; the needle valve injection assembly (8) starts from top to bottom. It includes the slider (808), needle valve (803), nozzle (804), and nozzle hole (806) in order from the bottom; the outer wall of the control valve (504) is pressed against the inner wall of the control valve body (6) to form a cylindrical seal. The outer wall of the needle valve (803) contacts the inner wall of the primary control cavity (13) and forms a cylindrical seal, and there is a certain gap between the outer wall of the needle valve (803) and the inner wall of the nozzle (804); The electromagnet (501) and armature (502) in the electromagnetic control valve assembly (5) are installed in the first cavity (101), and the control valve return spring (511) penetrates the inside of the electromagnet (501) , the limit valve (503) is located in the second cavity (102), and the limit valve return spring (512) is set on its outer wall; the control valve (504) is located in the control valve body (6), including The upward protruding cylinder and the flange of the bottom layer protruding from the upper cylinder along the circumferential direction, the protruding cylinder passes through the limit valve (503) and is threadedly connected with the armature (502); the control valve (504) is controlled by the control valve The limit valve (503) is in the lower limit position due to the elastic force of the return spring (511), and the limit valve (503) is seated on the control valve body (6) due to the elastic force of the limit valve return spring (512); The slider (808) of the needle valve injection assembly (8) is located in the fourth cavity, and its outer wall is set with a slider return spring (807); the inner wall of the fourth cavity cooperates with the slider (808) to form a space As a secondary control cavity (801); the slider (808) is seated on the primary control cavity (13) due to the joint action of hydraulic pressure and the elastic force of the slider return spring (807); the primary control cavity (13) 13) The bottom is connected to the top wall of the nozzle (804), and the bottom of the nozzle (804) has multiple nozzle holes (806); The needle valve return spring (809) is sleeved and raised on the top of the needle valve (803); the space formed by the inner wall of the primary control cavity (13), the bottom wall of the slider (808) and the needle valve (803) serves as a stage control cavity (802); the needle valve (803) is seated on the valve seat processed by the nozzle (804) due to the combined action of hydraulic pressure and the elastic force of the needle valve return spring (809); A needle valve annular cavity (805) is also provided between the inner wall of the nozzle (804) and the outer wall of the needle valve (803), and the needle valve annular cavity (805) is connected with the high-pressure oil circuit (11); the needle valve (805) There is a certain gap between the lower end of 803) and the nozzle (804) to form a pressure chamber (810), and the pressure chamber (810) is connected to the nozzle hole (806); Along the circumferential direction of the control valve (504), there are 4 annular grooves on the outer wall of the control valve (504). Each annular groove cooperates with the inner wall of the control valve body (6) to form a high-pressure chamber (505) and a first-level chamber respectively. Ring chamber (515), secondary ring chamber (517) and low pressure chamber (510); A low-pressure oil circuit (518) is provided in the control valve body (6). One end of the low-pressure oil circuit (518) is connected to the low-pressure chamber (510), and the other end is connected to the external low-pressure oil tank; a control valve oil circuit (516) is provided inside the control valve (504). , the two-way hole (513) of the high-pressure chamber, the two-way hole (506) of the first-level annular cavity, the two-way hole (508) of the second-level annular cavity, the control valve oil circuit (516) passes through the two-way hole (513) of the high-pressure cavity, the first-level ring cavity The two-way hole (506) in the cavity and the two-way hole (508) in the secondary annular cavity are connected to the high-pressure cavity (505), the primary annular cavity (515) and the secondary annular cavity (517) respectively; the control valve (504) is also tilted in the cavity. Set up a high-pressure chamber oil inlet throttle hole (514), a first-level control chamber two-way throttle hole (507), and a second-level control chamber two-way throttle hole (509). One end of the high-pressure chamber oil inlet throttle hole (514) is connected to the high-pressure oil Road (11), the other end is connected to the high-pressure chamber (505), the entrance of the two-way throttle hole (507) of the primary control chamber is connected to the primary annular chamber (515), and the other end passes through the interior of the secondary control chamber (7) The second end is connected to the primary control chamber (802), the entrance of the two-way throttle hole (509) of the secondary control chamber is connected to the secondary annular cavity (517), and the other end is connected to the secondary control chamber (801); The primary control fuel flow path is: through the primary control chamber bidirectional orifice (507), the primary annular chamber (515), the primary annular chamber bidirectional hole (506), the control valve oil path (516), the control valve ( The gap between 504) and the secondary control cavity (7) enters the low-pressure oil circuit (518); Secondary control fuel flow path: enters the low-pressure oil circuit (518) through the two-way orifice (509) of the secondary control chamber and the low-pressure chamber (510); The injection flow path of the needle valve injection assembly: enters the pressure chamber (810) through the gap between the needle valve annular cavity (805), the outer wall of the needle valve (803) and the inner wall of the nozzle (804), and then sprays out from the injection hole (806) ; The low oil return electronically controlled injector has the following two injection modes when injecting regularly: Low current fuel injection mode: When a small current is supplied to the solenoid control valve assembly (5), the control valve (504) is lifted to the limit due to the hydraulic pressure, electromagnetic force and elastic force. The control valve (504) no longer rises and controls the first-level control chamber. The high-pressure fuel inside flows through the first-level control fuel flow path, and then the needle valve (803) that controls the needle valve injection assembly (8) is lifted to the limit position. The high-pressure fuel enters the pressure chamber through the injection flow path of the needle valve injection assembly. Then it sprays out from the nozzle hole, forming a rectangular injection regular curve; High current fuel injection mode: When a large current is supplied to the solenoid control valve assembly (5), the control valve (504) is lifted to the limit due to hydraulic pressure, electromagnetic force and elastic force, and then drives the limit valve (503) to be lifted to the limit valve ( 503), controls the high-pressure fuel in the primary control chamber to flow through the primary control fuel flow path and the high-pressure fuel in the secondary control chamber to flow through the secondary control fuel flow path, and then controls the needle valve injection assembly (8) The needle valve (803) is lifted to the limit position, and then the needle valve drives the slider (808) to rise together until the slider reaches its upper limit position. High-pressure fuel enters the pressure chamber through the injection flow path of the needle valve injection assembly, and then flows from The nozzle hole sprays out to form a rectangular fuel injection regular curve; When the low oil return electronically controlled injector injects regularly with shoe-shaped injection: First, apply a small current to the electromagnetic control valve assembly (5) in the low current fuel injection mode. The high-pressure fuel flows through the primary control fuel flow path and the injection flow path of the needle valve injection assembly and then sprays out from the nozzle hole; during the fuel injection process A large current is passed through the middle pair of the electromagnetic control valve assembly (5). The control valve (504) is lifted to the limit due to the hydraulic pressure, electromagnetic force and elastic force, and then drives the limit valve (503) to continue to rise until it reaches the limit valve (503). 503), controls the high-pressure fuel in the secondary control chamber to flow through the secondary control fuel flow path, controls the needle valve of the needle valve injection assembly (8) to lift to the limit position, and then the needle valve (803) drives the slide The blocks rise together until the slider (808) reaches its upper limit position, and the high-pressure fuel enters the pressure chamber through the injection flow path of the needle valve injection assembly, and is then sprayed out from the injection hole. 2. The low-return electronically controlled injector with variable injection pattern according to claim 1, characterized in that the lifting limit of the needle valve (803) is the lower end surface of the slider (808); The upper limit of the control valve (504) is the lower end surface of the limit valve (503), and the upper limit position of the limit valve (503) is the top surface of the second cavity; the slider (808) The upper limit position of is the top surface of the fourth cavity. 3. The low oil return electronically controlled injector with variable injection pattern according to claim 1, characterized in that the lower edge of the outlet of the high-pressure chamber oil inlet throttle hole (514) and the lower edge of the high-pressure chamber (505) Flush, the outlet diameter of the high-pressure chamber oil inlet orifice (514) is equal to the distance between the flange of the control valve (504) and the lower end surface of the limit valve (503), from the upper edge of the high-pressure chamber (505) to the high-pressure chamber (505 ) is greater than the outlet diameter of the high-pressure chamber oil inlet orifice (514), and the diameter of the high-pressure chamber bidirectional hole (513) is equal to the distance from the upper edge of the high-pressure chamber (505) to the lower edge of the high-pressure chamber (505). 4. The low oil return electronically controlled injector with variable injection pattern according to claim 1, characterized in that the upper edge of the inlet of the two-way throttle hole (507) of the first-level control chamber is in contact with the first-level annular cavity (515). ) The upper edge is flush, the distance between the lower edge of the inlet of the first-level control cavity bidirectional throttle hole (507) and the lower edge of the first-level annular cavity (515) is greater than the maximum lift distance of the control valve (504), and the first-level control cavity is bidirectional The inlet diameter of the throttle hole (507) is equal to the distance between the flange of the control valve (504) and the lower end surface of the limit valve (503); the diameter of the two-way hole (506) of the primary annular cavity is larger than the two-way throttle hole of the primary control cavity (507) Inlet diameter, the distance from the upper edge of the primary ring chamber (515) to the lower edge of the high pressure chamber (505) is greater than the maximum lift distance of the control valve (504). 5. The low oil return electronically controlled injector with variable injection pattern according to claim 1, characterized in that the lower edge of the inlet of the two-way throttle hole (509) of the secondary control chamber is in contact with the secondary annular cavity (517). ) The lower edge is flush, and the inlet diameter of the two-way orifice (509) of the secondary control chamber is equal to the distance between the flange of the control valve (504) and the lower end surface of the limit valve (503); the two-way orifice of the secondary control chamber The distance between the lower edge of the inlet (509) and the upper edge of the low-pressure chamber (510) is equal to the distance between the flange of the control valve (504) and the lower end face of the limit valve (503); the upper edge of the secondary annular cavity (517) The distance to the lower edge of the secondary annular cavity (517) is greater than the inlet diameter of the two-way throttle hole (509) of the secondary control cavity, and the diameter of the two-way orifice (508) of the secondary annular cavity is equal to the upper edge of the secondary annular cavity (517). The distance between the lower edges of the secondary annulus (517). 6. The low-oil return electronically controlled injector with variable injection pattern according to claim 1, characterized in that the distance between the upper edge of the low-pressure chamber (510) and the lower edge of the secondary ring chamber (517) is equal to the control The distance between the flange of the valve (504) and the lower end surface of the limit valve (503), and the distance between the lower end surface of the electromagnet (501) and the upper end surface of the armature (502) are greater than the maximum lift distance of the control valve (504). The cross-sectional area of the control valve oil passage (516) is greater than the sum of the inlet cross-sectional area of the two-way orifice (509) of the secondary control chamber and the inlet cross-sectional area of the two-way orifice (507) of the primary control chamber.