CN111237108B - High-pressure common rail oil sprayer capable of directly controlling oil spray nozzle switch - Google Patents

Abstract

The invention relates to a high-pressure common rail oil sprayer capable of directly controlling an oil spray nozzle switch; the oil sprayer mainly comprises a binding post assembly, an oil sprayer body, an electromagnet component, an intermediate body and a pressure balance oil sprayer, wherein the binding post assembly is connected above the oil sprayer body through a screw sleeve, and the intermediate body and the pressure balance oil sprayer are connected below the oil sprayer body through the screw sleeve of the oil sprayer; the electromagnet component is arranged in the oil sprayer body and is connected with the control pressure balance oil sprayer so as to realize the direct control of the on and off of the pressure balance oil sprayer. The beneficial effects of the invention are as follows: the electromagnet is used for directly controlling the pressure balance type oil nozzle, so that the oil injection response time can be improved, the structure of the oil injector is greatly simplified, a plurality of slender high-pressure and low-pressure oil return holes are not provided, the processing difficulty of the oil injector body is greatly simplified, and the cost of the common rail oil injector is reduced. 2. The invention is also used in the fuel spray nozzle of gasoline injection, and can improve the fuel pressure of direct injection gasoline injection so as to improve the performance of the gasoline engine.

Description

High-pressure common rail injector with direct control of the injector nozzle switch

Technical Field

The invention relates to a common rail fuel injector for a diesel engine, in particular to a common rail fuel injector for directly controlling a fuel injection nozzle switch, and belongs to the field of fuel systems for internal combustion engines.

Background Art

Existing diesel engine common rail injectors have two ways of controlling the switch of the injector nozzle: electromagnet and piezoelectric crystal. They mainly control the switch of the injector nozzle indirectly through a hydraulic servo valve. They have a complex structure, high processing precision, and slow response speed. At present, foreign countries do not use hydraulic servo valves, but use piezoelectric crystals to directly control the switch of the injector nozzle. Common rail injectors have become products. For example, Delphi Corporation of the United States and Continental AG of Germany have used common rail injectors that directly control the switch of the injector nozzle on diesel engines.

As for the common rail fuel injector controlled by electromagnet, the high-speed electromagnet of the common rail fuel injector is small in size and has a force of only more than 100 Newtons, which is much smaller than the several thousand Newtons of the piezoelectric crystal control force. The currently commonly used closed fuel injector is shown in Figure 7. The needle valve guide seal diameter d1=4mm, the cone seal diameter d2=2mm, when the electromagnet is in the low-pressure area, the high-pressure fuel acting on the nozzle needle valve will generate an upward unbalanced liquid pressure. When the fuel injection pressure is 200Mpa, the upward unbalanced liquid pressure acting on the nozzle needle valve is as high as more than 1800 Newtons. The electromagnetic force of the electromagnet is much smaller than the unbalanced liquid pressure. The electromagnet cannot directly pull the needle valve to control the switch of the fuel injector. The electromagnetic force must be converted into a strong liquid pressure through a hydraulic servo valve to pull the needle valve and control the switch of the fuel injector. Therefore, there is no high-pressure common rail fuel injector in which the switch of the fuel injector is directly controlled by an electromagnet at home and abroad.

Fig. 7 shows the typical structure of the common rail fuel injector for diesel engines produced by BOSCH in Germany. The upper end of the injector is equipped with an electromagnet 21, an armature 22, and the middle part is equipped with a spherical two-position two-way servo valve 23, which allows the high-pressure hydraulic pressure on the hydraulic piston 24 to quickly turn to low pressure, or quickly turn from low pressure to high pressure, so as to control the switch of the fuel injection nozzle 25. In this common rail fuel injector, on the one hand, the electromagnet must switch the fuel injection nozzle through the servo valve, and the response speed is slower than that of directly controlling the fuel injection nozzle. In addition, the hydraulic impact force of up to 180-200Mpa acting on the hydraulic piston causes the needle valve and the precise sealing cone surface of the valve seat to wear quickly, reducing the life of the fuel injection nozzle and the working reliability.

Our company's patent 20081004087 proposes a high-pressure common rail injector that directly controls the injector nozzle switch. It places a two-position two-way servo control valve at the top of the injector nozzle, but the injector nozzle switch is still controlled by the servo valve. It is not a real high-pressure common rail injector that directly controls the injector nozzle switch with an electromagnet.

Summary of the invention

The purpose of the present invention is to provide a high-pressure common rail fuel injector that directly controls the switch of the fuel injector nozzle; it adopts the equal sealing line principle to make the high-pressure fuel pressure force acting on the fuel injector needle valve zero, that is, a closed fuel injector nozzle with pressure balance, and a diesel engine high-pressure common rail fuel injector that directly switches the fuel injector nozzle with an electromagnet. It keeps the fuel injector nozzle spray hole angle and the direction of the fuel injection line basically unchanged from the original oil nozzle, and the liquid pressure acting on the needle valve is balanced, so that the solenoid valve has enough electromagnetic force to directly control the switch of the fuel injector nozzle.

The present invention is achieved through the following technical scheme: a common rail injector that directly controls the switch of the injector nozzle, which is mainly composed of a terminal assembly 1, an injector body 2, an electromagnet component, an intermediate body 7 and a pressure-balanced injector nozzle 6. The terminal assembly 1 is connected to the top of the injector body 2 through a screw sleeve 19, and the intermediate body 7 and the pressure-balanced injector nozzle 6 are connected to the bottom of the injector body 2 through an injector nozzle screw sleeve 9; the electromagnet component is installed in the injector body 2 and is connected to the pressure-balanced injector nozzle 6 to directly control the opening and closing of the pressure-balanced injector nozzle 6.

Compared with the previous technology, the beneficial effects of the present invention are:

1. The present invention uses an electromagnet to directly control the pressure-balanced fuel injector, which can improve the injection response time and greatly simplify the structure of the fuel injector. At the same time, there are no many slender high-pressure and low-pressure oil return holes, which greatly simplifies the processing difficulty of the fuel injector body 2 and reduces the cost of the common rail fuel injector.

2. The present invention is also used in gasoline injection nozzles to increase the fuel pressure of direct gasoline injection to improve the performance of gasoline engines.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG1 is a first embodiment of the present invention for directly controlling the fuel injection nozzle switch;

Figure 2 is a structural diagram of a pressure-balanced closed fuel injection nozzle;

FIG3 is a structural diagram for eliminating the dead volume of the oil nozzle;

FIG4 is a second embodiment of the present invention;

Fig. 5 is a cross-sectional view of the F-F section in Fig. 4;

Figure 6 is a structural diagram of the tail of the needle valve, where a is the overall structure and b is the split structure;

FIG7 is a common rail injector with a servo ball valve;

Reference numerals 1 terminal assembly, 10 guide sleeve, 11 valve seat, 12 needle valve, 13 sealing sleeve, 14 gap, 15 spring seat, 16 lever, 17 pin shaft, 18 return spring, 19 screw sleeve, 20 low-pressure oil return hole, 101 terminal, 1101 high-pressure oil inlet hole, 1102 oil tank, 1103 sealing cone surface A, 1104 oil injection hole, 1105 cylindrical hole, 1106 valve seat outer circle, 1107 inner channel, 1201 central oil return hole, 12 02 sealing cone surface B, 1203 needle valve cylinder, 1204 small lubrication groove, 1205 cylindrical ring groove, 1206 inclined hole A, 1207 upper groove edge, 1208 lower groove edge, 1209 lower ring groove, 1210 extended inclined hole B, 1211 low pressure oil return hole, 1212 hinge seat, 1213 outer wall, 1214 cap, 1215 limit hole, 1216 slot, 2 injector body, 26 ring, 201 high pressure oil inlet hole A, 202 low pressure oil return hole A , 203 adjusting gasket, 204 electromagnet coil wire hole A, 205 internal oil return hole A, 206 high-pressure oil inlet hole A, 3 return spring, 4 electromagnet component, 401 coil, 5 armature, 501 armature rod, 502 armature head, 701 horizontal groove, 6 pressure balance fuel injection nozzle, 7 intermediate body, 701 horizontal groove, 702 straight groove, 8 return spring, 9 fuel injection nozzle screw sleeve.

DETAILED DESCRIPTION

The present invention is described in detail below in conjunction with the accompanying drawings:

As shown in Figures 1-6: The present invention is a common rail injector that directly controls the switch of the injector nozzle, which is mainly composed of a terminal assembly 1, an injector body 2, an electromagnet component, an intermediate body 7 and a pressure-balanced injector nozzle 6. The terminal assembly 1 is connected to the top of the injector body 2 through a screw sleeve 19, and the intermediate body 7 and the pressure-balanced injector nozzle 6 are connected to the bottom of the injector body 2 through an injector nozzle screw sleeve 9; the electromagnet component is installed in the injector body 2 and connected to the pressure-balanced injector nozzle 6 to directly control the opening and closing of the pressure-balanced injector nozzle 6.

The basic structure of the terminal assembly 1 and the injector body 2 here is not much different from the existing terminal assembly 1 and the injector body 2. The terminal assembly 1 is provided with a terminal 101; the injector body 2 is processed with high-pressure oil inlet holes A201, 206, a low-pressure oil return hole A202, an electromagnet coil wire hole A204, an internal oil return hole A205, etc.

According to the connection mode between the electromagnet component and the pressure-balanced fuel injection nozzle 6, the present invention can be divided into the following two embodiments:

Example 1

As shown in FIG1-2 : the pressure-balanced fuel injection nozzle comprises a valve seat 11 , a needle valve 12 , a guide sleeve 10 , a sealing sleeve 13 , and a reset structure;

The valve seat 11 is provided with an inner valve seat channel 1107 coaxially arranged with the valve seat 11 in the middle, an oil storage groove 1102 is arranged around the upper part of the inner valve seat channel 1107, a high-pressure oil inlet hole 1101 connected with the oil storage groove 1102 is opened on the side wall of the valve seat 11, a sealing cone surface A1103 is arranged around the lower part of the inner valve seat channel 1107 so that the inner valve seat channel 1107 is located below the sealing cone surface A1103 to form a cylindrical hole 1105, and a plurality of oil injection holes 1104 connected with the cylindrical hole 1105 are arranged around the lower side wall of the valve seat 11;

The needle valve 12 extends into the inner channel 1107 of the valve seat 11 and can move up and down in the inner channel 1107. The needle valve 12 is provided with a central oil return hole 1201 extending along the axial direction of the needle valve 12; the upper side wall of the needle valve 12 is provided with a low-pressure oil return hole 1211 connected with the central oil return hole 1201, and the lower side wall of the needle valve 12 is provided with a sealing cone surface B1202 so that the needle valve 12 is located below the sealing cone surface B1202 to form a needle valve cylinder 1203; a cylindrical ring groove 1205 is provided on the outer periphery of the needle valve cylinder 1203 and at the junction with the sealing cone surface B1202; a plurality of small lubrication grooves 1204 are provided on the outer periphery of the needle valve cylinder 1203 below the cylindrical ring groove 1205;

The sealing sleeve 13 is sealed at the bottom of the inner channel 1107; the sealing sleeve 13 is mainly used after the needle valve 12 is lifted, and the high-pressure fuel in the cylindrical annular groove 1205 will seep out through the gap between the needle valve cylinder 1203 of the needle valve 12 and the cylindrical hole 1105 of the valve seat 11, and become low-pressure fuel, and pass through the gap 14 between the needle valve cylinder 1203 and the sealing sleeve 13, through the central oil return hole 1201 of the needle valve 12, the low-pressure oil return hole 1211 and the internal oil return hole A205, and return to the fuel tank from the low-pressure oil return hole A202.

The inner hole of the sealing sleeve 13 is tightly matched with the outer circle 1106 of the valve seat and is laser welded to the outer circle 1106 of the valve seat. During use, low-pressure fuel can be sealed and will not fall from the nozzle valve seat 11 into the combustion chamber of the diesel engine.

The guide sleeve 10 is sleeved on the upper part of the needle valve 12, and the outer periphery is interference fit with the inner hole 1108 of the valve seat;

The reset structure is arranged on the top of the needle valve 12 and cooperates with the electromagnet component.

The cone angle of the sealing cone surface B1202 is B, and the cone angle of the sealing cone surface A1103 is A. The cone angle A is 0.5-3 degrees larger than the cone angle B.

The needle valve 12 is a cylinder with a gradually changing diameter. The diameter of the area where the upper part of the needle valve 12 cooperates with the guide sleeve 10 is d1, the diameter of the needle valve cylinder 1203 is d2, and the diameter of the middle area of the needle valve 12 is d3, wherein d1=d2, and d3 is 0.5-1 mm larger than d2.

Because the diameter of the sealing ring formed by the contact between the sealing cone surface A1103 and the sealing cone surfaces A1205 and B1202 is d2, which is smaller than d3, and because d1=d2, in order to facilitate assembly and disassembly, a guide sleeve 10 must be put on the needle valve 12, and the inner hole diameter of the guide sleeve 10 is d1, so the static hydraulic pressure acting on the needle valve 12 is zero; after the needle valve 12 rises, due to the precise fit between the sealing cone surface A1103 and the sealing cone surface B1202, the hydraulic force of the sealing fuel on the needle valve 11 is also zero, so the electromagnet only needs to use a very small force to make the sealing cone surface B1202 of the needle valve 11 rise or press the sealing cone surface A1103 of the valve seat 11, so that the injector can switch the high-pressure fuel, and the gap between the inner channel 1107 in the valve seat 11 and the outer side wall 1213 of the needle valve 12 forms a ring channel 26.

The reset structure includes a cap 1214 and a return spring 8;

The cover cap 1214 is fixedly connected to the top of the needle valve 12 , and the return spring 8 is located between the cover cap 1214 and the top of the valve seat 11 .

After the sealing cone surface B1202 and the sealing cone surface A1103 are connected, the high-pressure fuel is cut off, but the spray hole 1104 is still connected to the cylindrical ring groove 1205. The dead volume of the cylindrical ring groove 1205 is large, which increases the harmful emissions of the diesel engine. Therefore, the dead volume must be reduced as much as possible. Therefore, the following changes are made.

As shown in FIG3 : below the cylindrical annular groove 1205, the needle valve cylinder 1203 is also provided with a lower annular groove 1209, the cylindrical annular groove 1205 is provided with an inwardly extending oblique hole A1206, and the lower annular groove 1209 is provided with an inwardly extending oblique hole B1210, and the oblique hole A1206 and the oblique hole B1210 are connected to each other; the relationship between the lower annular groove 1209 and the cylindrical annular groove 1205 satisfies the following conditions: the lower groove edge 1208 of the cylindrical annular groove 1205 is not connected to the oil injection hole 1104; after the needle valve 12 is lowered, the upper groove edge 1207 of the lower annular groove 1209 is at a distance H from the oil injection hole 1104; when the needle valve 12 is lifted, the lower annular groove 1209 is connected to the oil injection hole 1104. The sharp edge burrs should be removed at the intersection of the oblique hole A1206 and the oblique hole B1210 to prevent stress concentration. After the high-pressure fuel is cut off, the spray hole 1104 and the cylindrical annular groove 1205 are no longer connected, and the dead volume is zero.

When the needle valve 12 rises, its cone surface 1202 leaves the cone surface 1103 of the valve seat, and the high-pressure fuel in the annular groove 26 passes through the cylindrical annular groove 1205, the inclined hole A 1206, and the extended inclined hole B 1210 to reach the lower annular groove. After the needle valve 12 lifts more than H, the upper groove edge 1207 connects to the injection hole 1104, and the high-pressure fuel is sprayed into the diesel engine combustion chamber. The size of H and the lift of the needle valve 12 affect the cross-sectional area of the injection hole 1104. At full load, the needle valve 12 has a large lift and can fully open the cross-sectional area of the injection hole. At low load and idling, the cross-sectional area of the injection hole 1104 is only partially open. Therefore, controlling the size of H can change the injection rate of the injection hole, thereby improving diesel engine combustion.

The electromagnet component includes an adjusting gasket 203, a return spring 3, a spring seat 15, an armature rod 501, and an armature 5, which are arranged in order from top to bottom in the injector body 2. An electromagnet component 41 for controlling the lifting of the armature is arranged above the armature 5 and on the outer periphery of the armature rod 501. A coil 401 is arranged in the electromagnet component 4.

The armature head 502 of the armature rod 501 is pressed against the upper surface of the cover cap 1214 .

The working process of Example 1 is as follows:

The high-pressure fuel flows from the high-pressure oil inlet holes A201 and 206 on the injector body 2, through the high-pressure oil inlet hole 1101 of the valve seat 11, to the oil receiving groove 1102, and then through the annular channel 26 to the sealing cone surface B1202. When the coil 401 of the electromagnet 4 is energized, an electromagnetic suction force is generated, which attracts the armature assembly 5 and the armature rod 501, overcomes the preload force of the return spring 3 and rises. The needle valve 12 rises under the action of the return spring 8, and the sealing cone surface B1202 separates from the sealing cone surface A1103. The high-pressure fuel flows from the gap between the two cone surfaces into the cylindrical annular groove 1205, and then is sprayed from multiple injection holes 1104 into the diesel engine combustion chamber for combustion.

The high-pressure fuel seal in the cylindrical ring groove 1205 is above the needle valve cylinder 1203. A small amount of fuel leaking from the gap between the cylindrical hole 1105 and the needle valve cylinder 1203 flows back to the fuel tank through the central oil return hole 1201, the low-pressure oil return hole 1211, the internal oil return hole A205 to the low-pressure oil return hole A202.

When the line 401 of the electromagnet 4 is powered off, the electromagnetic force is lost. Since the pressure of the return spring 8 is much lower than the stiffness of the return spring 3, the return spring 3 can press the sealing cone surface B1202 of the needle valve 12 tightly against the sealing cone surface A1103, cutting off the high-pressure fuel, and the injection hole 1104 stops injecting fuel.

Example 2

As shown in Fig. 4-6: the pressure-balanced fuel injector comprises a valve seat 11, a needle valve 12, a guide sleeve 10, and a reset structure;

The valve seat 11 is provided with an inner valve seat channel 1107 coaxially arranged with the valve seat 11 in the middle, an oil storage groove 1102 is arranged around the upper part of the inner valve seat 11 channel 1107, a high-pressure oil inlet hole 1101 connected with the oil storage groove 1102 is opened on the side wall of the valve seat 11, a sealing cone surface A1103 is arranged around the lower part of the inner valve seat 1107 so that the inner valve seat 1107 is located below the sealing cone surface A1103 to form a cylindrical hole 1105, and a plurality of oil injection holes 1104 connected with the cylindrical hole 1105 are arranged around the lower side wall of the valve seat 11;

The needle valve 12 extends into the inner channel 1107 of the valve seat 11 and can move up and down in the inner channel 1107. The needle valve 12 is provided with a central oil return hole 1201 extending along the axial direction of the needle valve 12; the upper side wall of the needle valve 12 is provided with a low-pressure oil return hole 1211 connected with the central oil return hole 1201, and the lower side wall of the needle valve 12 is provided with a sealing cone surface B1202 so that the needle valve 12 is located below the sealing cone surface B1202 to form a needle valve cylinder 1203; a cylindrical ring groove 1205 is provided on the outer periphery of the needle valve cylinder 1203 and at the junction with the sealing cone surface B1202; a plurality of small lubrication grooves 1204 are provided on the outer periphery of the needle valve cylinder 1203 below the cylindrical ring groove 1205;

The guide sleeve 10 is sleeved on the outer periphery of the upper part of the needle valve 12 and is interference fit with the inner hole 1108 of the valve seat;

The reset structure is arranged on the top of the needle valve 12 and cooperates with the electromagnet component.

The cone angle of the sealing cone surface B1202 is B, and the cone angle of the sealing cone surface A1103 is A. The cone angle A is 0.5-3 degrees larger than the cone angle B.

The needle valve 12 is a cylinder with a gradually changing diameter. The diameter of the area where the upper part of the needle valve 12 cooperates with the guide sleeve 10 is d1, the diameter of the needle valve cylinder 1203 is d2, and the diameter of the middle area of the needle valve 12 is d3, wherein d1=d2, and d3 is 0.5-1 mm larger than d2.

The reset structure includes an articulated seat 1212, a lever 16, and a reset spring 18 located at the upper end of the needle valve 12; a slot 1216 is provided on the articulated seat 1212, and a limiting hole 1215 is provided on both side walls of the slot 1216. One end of the lever 16 is embedded in the slot 1216 and is hinged to the articulated seat 1212 through a pin 17 passing through the limiting hole 1215 and the lever 16. As can be seen from FIG5, a transverse slot 701 and a straight slot 702 of the reset spring 18 are provided in the intermediate body 7, so that the lever 16 can rotate in the transverse slot 701, and 20 is a low-pressure oil return hole.

The electromagnet component includes an adjusting gasket 203, a return spring 3, a spring seat 15, an armature rod 501, and an armature 5, which are arranged in order from top to bottom in the injector body 2. An electromagnet component 41 for controlling the lifting of the armature is arranged above the armature 5 and on the outer periphery of the armature rod 501. A coil 401 is arranged in the electromagnet component 4.

As shown in Figure 4: the armature head 502 of the armature rod 501 presses against the upper surface of the lever 16 to form a fulcrum a, and the lower surface of the lever 16 contacts the upper surface of the valve seat 11 to form a contact point b. J is the distance from the center of the pin to the contact point b, K is the distance from the fulcrum a to the contact point b, and the needle valve lift magnification ratio is J/K

The working process of Example 2 is as follows:

Because of the existence of the high-pressure fuel inlet hole A206 in the injector body 2, when the electromagnet is installed in the middle of the injector, the electromagnet diameter that can be selected is smaller and the maximum electromagnetic force of the electromagnet is smaller. In order to increase the electromagnetic force and speed up the needle valve switching speed, increasing the electromagnet diameter is the best option. For this purpose, the electromagnet is deviated from the center by a distance, thereby increasing the diameter of the electromagnet.

Because the electromagnetic force is larger when the stroke of the flat electromagnet is small (generally about 0.1), and the stroke of the needle valve 12 is 0.2-0.3 mm, a lever 16 is designed between the needle valve and the electromagnet, and the lever 16 is used to increase the lift of the needle valve 12. When the lift of the electromagnet armature is smaller, a larger lift of the needle valve 12 can be obtained. This structure can increase the lift of the needle valve by 1-2 times.

During specific use, when the coil 401 of the electromagnet 4 is energized, the return spring 3 presses the head 502 of the armature rod 501 against point a of the lever 16. The lever 16 uses point b as a fulcrum to overcome the elastic force of the return spring 18, and presses the sealing cone surface B1202 against the sealing cone surface A1103 through the pin shaft 17, cutting off the channel of the high-pressure fuel to the spray hole 1104, and the fuel injector does not spray.

After the coil 401 of the electromagnet 4 is energized, the electromagnetic attraction causes the armature rod 501 to rise through the armature 5. Under the action of the return spring 18, the lever 16 rises with b as the fulcrum, and the pin 17 rises, thereby lifting the needle valve 12, and the sealing cone surface B1202 separates from the sealing cone surface A1103. The high-pressure fuel is sprayed into the combustion chamber from the cone surface gap through the cylindrical ring groove 1205 and the injection hole 1104.

Due to the use of the biased electromagnet and the lever 16, the electromagnet lift is reduced, the suction force is greatly increased, and the needle valve lift is also increased, and the switching speed of the needle valve 12 is increased by 1-2 times.

The present invention proposes an equal sealing line method, which makes the resultant force of high-pressure fuel pressure acting on the nozzle needle valve zero, that is, a closed fuel injector with pressure balance, and a diesel engine high-pressure common rail injector that uses an electromagnet to directly switch the fuel injector. It keeps the nozzle hole angle and the direction of the fuel injection line of the fuel injector basically unchanged from the original nozzle, and the liquid pressure acting on the needle valve is balanced, so that the solenoid valve has enough electromagnetic force to directly control the switch of the fuel injector.

The above-mentioned equal sealing line method makes the high-pressure hydraulic pressure acting on the needle valve balance each other. The basic idea is as follows: the intersection line of the conical surface of the valve seat and the inner hole with a diameter of d2 is the sealing line, which contacts the conical surface of the needle valve to seal the high-pressure oil, and increases the diameter of the sealing line d2, which is the same as the inner diameter d1 of the outer circle of the needle valve and the guide sleeve in the valve seat, so that the static hydraulic pressure force acting on the needle valve is zero. The pressure balance control valve of the common rail injector and the single pump is to release the high-pressure fuel to low pressure. The pressure-balanced fuel injector controls the high-pressure fuel in the common rail to be sent to the front of the injection hole. Since the injection hole is small, the original high pressure is maintained in front of the injection hole, and the two-position two-way control valve is generally unable to control it. In order to balance the hydraulic pressure acting on the needle valve during the lifting and closing process of the needle valve, a cylinder with a diameter of d2 on the conical sealing line must be added to the top of the needle valve. It is sealed with the inner hole with a diameter of d2 at the lower end of the valve seat, so that the high-pressure fuel in front of the injection hole will not flow to the bottom of the needle valve and destroy the balance of hydraulic pressure.

Although the present invention is illustrated and described by specific embodiments and their alternatives, it should be understood that various changes and modifications within the spirit and scope of the present invention can be implemented. Therefore, it should be understood that the present invention is not limited in any sense except by the limitations of the attached claims and their equivalents.

Claims (7)

1. A common rail fuel injector for directly controlling a fuel injection nozzle switch, the common rail fuel injector mainly comprising a terminal assembly (1), a fuel injector body (2), an electromagnet component, an intermediate body (7) and a pressure-balanced fuel injection nozzle (6), wherein the terminal assembly (1) is connected to the upper part of the fuel injector body (2) via a screw sleeve (19), and the intermediate body (7) and the pressure-balanced fuel injection nozzle (6) are connected to the lower part of the fuel injector body (2) via a fuel injection nozzle screw sleeve (9); the common rail fuel injector is characterized in that the electromagnet component is installed in the fuel injector body (2) and connected to the pressure-balanced fuel injection nozzle (6) to realize the direct control of the opening and closing of the pressure-balanced fuel injection nozzle (6); The pressure-balanced fuel injection nozzle comprises a valve seat (11), a needle valve (12), a guide sleeve (10), a sealing sleeve (13), and a reset structure; The valve seat (11) has an inner channel (1107) coaxially arranged with the valve seat (11) in the middle, an oil storage groove (1102) is arranged around the upper part of the inner channel (1107) of the valve seat (11), a high-pressure oil inlet hole (1101) in communication with the oil storage groove (1102) is provided on the side wall of the valve seat (11), a sealing cone surface A (1103) is arranged around the lower part of the inner channel (1107) so that a cylindrical hole (1105) is formed at the portion of the inner channel (1107) below the sealing cone surface A (1103), and a plurality of oil injection holes (1104) in communication with the cylindrical hole (1105) are arranged around the lower side wall of the valve seat (11); The needle valve (12) extends into the inner channel (1107) of the valve seat (11) and can move up and down in the inner channel (1107); the needle valve (12) is provided with a central oil return hole (1201) extending along the axial direction of the needle valve (12); the upper side wall of the needle valve (12) is provided with a low-pressure oil return hole (1211) communicating with the central oil return hole (1201); the lower side wall of the needle valve (12) is provided with a sealing cone surface B (1202) so that the needle valve (12) is located below the sealing cone surface B (1202) to form a needle valve cylinder (1203); a cylindrical ring groove (1205) is provided on the outer periphery of the needle valve cylinder (1203) and at the junction with the sealing cone surface B (1202); and a plurality of small lubrication grooves (1204) are provided on the outer periphery of the needle valve cylinder (1203) below the cylindrical ring groove (1205); The sealing sleeve (13) is sealed at the bottom of the inner channel (1107); The guide sleeve (10) is sleeved on the outer periphery of the upper portion of the needle valve (12) and is interference fit with the inner hole (1108) of the valve seat; The reset structure is arranged on the top of the needle valve (12) and cooperates with the electromagnet component. 2. The common rail injector for directly controlling the injector nozzle switch according to claim 1, characterized in that: The cone angle of the sealing cone surface B (1202) is B, the cone angle of the sealing cone surface A (1103) is A, and the cone angle A is 0.5-3 degrees greater than the cone angle B; The needle valve (12) is a cylinder with a gradually changing diameter. The diameter of the area where the upper part of the needle valve (12) cooperates with the guide sleeve (10) is d1, the diameter of the needle valve cylinder (1203) is d2, and the diameter of the middle area of the needle valve (12) is d3, wherein d1=d2, and d3 is 0.5-1 mm larger than d2. 3. The common rail injector for directly controlling the injector nozzle switch according to claim 2, characterized in that: The reset structure comprises a cover cap (1214) and a return spring (8); The cover cap (1214) is fixedly connected to the top of the needle valve (12), and the return spring (8) is located between the cover cap (1214) and the top of the valve seat (11). 4. The common rail fuel injector for directly controlling the fuel injection nozzle switch according to claim 3 is characterized in that: below the cylindrical annular groove (1205), the needle valve cylinder (1203) is further provided with a lower annular groove (1209), the cylindrical annular groove (1205) is provided with an inwardly extending inclined hole A (1206), the lower annular groove (1209) is provided with an inwardly extending inclined hole B (1210), the inclined hole A (1206) and the inclined hole B (1210) are parallel to each other. The lower annular groove (1209) and the cylindrical annular groove (1205) are interconnected; the relationship between the lower annular groove (1209) and the cylindrical annular groove (1205) satisfies the following conditions: the lower groove edge (1208) of the cylindrical annular groove (1205) is not in communication with the oil injection hole (1104); after the needle valve (12) descends, there is a distance H between the upper groove edge (1207) of the lower annular groove (1209) and the oil injection hole (1104); when the needle valve (12) is lifted, the lower annular groove (1209) is in communication with the oil injection hole (1104). 5. The common rail injector for directly controlling the injector nozzle switch according to claim 3 or 4, characterized in that: the electromagnet component comprises an adjusting gasket (203), a return spring (3), a spring seat (15), an armature rod (501), and an armature (5) arranged in order from top to bottom in the injector body (2); an electromagnet component (41) for controlling the lifting and lowering of the armature is arranged above the armature (5) and on the outer periphery of the armature rod (501); and a coil (401) is arranged inside the electromagnet component (41); The armature head (502) of the armature rod (501) is pressed against the upper surface of the cover cap (1214). 6. The common rail injector for directly controlling the injector nozzle switch according to claim 2, characterized in that: The reset structure comprises a hinge seat (1212) located at the upper end of the needle valve (12), a lever (16), and a reset spring (18); a slot (1216) is provided on the hinge seat (1212), and limiting holes (1215) are provided on both side walls of the slot (1216); one end of the lever (16) is embedded in the slot (1216) and is hinged to the hinge seat (1212) via a pin (17) passing through the limiting hole (1215) and the lever (16). 7. The common rail fuel injector for directly controlling the fuel injection nozzle switch according to claim 6, characterized in that: the electromagnet component comprises an adjusting gasket (203), a return spring (3), a spring seat (15), an armature rod (501), and an armature (5) arranged in order from top to bottom in the fuel injector body (2); an electromagnet component (41) for controlling the lifting and lowering of the armature is arranged above the armature (5) and on the outer periphery of the armature rod (501); and a coil (401) is arranged in the electromagnet component (41); The armature head (502) of the armature rod (501) presses against the upper surface of the lever (16) to form a fulcrum a, and the lower surface of the lever (16) contacts the upper surface of the valve seat (11) to form a contact point b.