An outward opening high pressure direct injection injector

Abstract

The present application relates to low boiling point (or high saturated vapor pressure), at room temperature and normal pressure and when injected into the engine cylinder, the technical field of liquid fuel injection system of fast vaporization, specifically disclose a kind of high-pressure direct injection injector of outer opening, including: control valve, injector, with nozzle, injector includes injector upper body and injector lower body, the injector upper body is located in the top of injector lower body, the control valve is located above the injector upper body, the nozzle is located in the bottom of injector lower body;Injector is equipped with diesel passage and fuel passage, by controlling diesel control needle valve opening, the way of improving the second controller pressure realizes fuel outer opening injection mode, effectively reduces the processing difficulty of nozzle head injection sealing surface, solves the low boiling point fuel nozzle vaporization cavity problem, by control valve control first control cavity, by control needle valve control second control cavity, and realize the isolation of fuel and diesel, solve the problem of low boiling point fuel sealing difficulty.

Description

Technical Field

[0001] This invention belongs to the technical field of liquid fuel injection systems that rapidly vaporize at low boiling point (or high saturated vapor pressure) when injected into engine cylinders at normal temperature and pressure, and specifically relates to an externally open high-pressure direct injection injector. Background Technology

[0002] Existing direct injection systems for high-pressure (above 200 bar) liquid ammonia and high-pressure dimethyl ether fuels mainly follow the technical approach of diesel common rail systems. Based on the diesel common rail injector, the injection flow rate is increased, and the corrosion resistance of materials to fuels such as ammonia and dimethyl ether is improved. At the control chamber end, diesel is used as the control oil to avoid cavitation erosion of the oil outlet and seat seal of the control chamber leading to the low-pressure oil circuit. However, at the nozzle end, ammonia and dimethyl ether rapidly vaporize when the pressure changes drastically, leading to prominent reliability issues at the nozzle end. These issues are mainly manifested in cavitation erosion leakage of the sealing cone surface and changes in the flow rate of the nozzle orifice after a period of operation. Summary of the Invention

[0003] The purpose of this invention is to provide an externally opening high-pressure direct injection injector to solve the problems mentioned in the background art.

[0004] To achieve the above objectives, the present invention provides the following technical solution: An externally opening high-pressure direct injection injector, comprising: The system includes a control valve, an injector, and a nozzle. The injector comprises an upper body and a lower body, with the upper body located at the top of the lower body, the control valve located above the upper body, and the nozzle located at the bottom of the lower body. The injector is equipped with a diesel fuel passage and a fuel oil passage; The diesel fuel passage includes a valve sleeve, a control needle valve, a second control chamber, and a high-pressure control oil chamber. The control needle valve is located in the upper body and lower body of the injector. The bottom of the valve sleeve is fitted onto the outer wall of the tail of the control needle valve, and the top of the valve sleeve is located between the control valve and the upper body of the injector. The high-pressure control oil chamber is located in the upper body of the injector. The tail of the control needle valve and the bottom of the valve sleeve are both located in the high-pressure control oil chamber. The second control chamber is located in the lower body of the injector. The fuel passage includes an injection needle valve, which is located on the lower body of the injector; Diesel fuel is used as control oil. Diesel fuel is injected into the high-pressure control oil chamber. After the control needle valve is opened, the pressure in the second control chamber is increased, which pushes open the injection needle valve, and the injector opens to inject fuel.

[0005] Preferably, the diesel passage further includes a diesel inlet, which is located on the outer wall of the upper part of the injector. The high-pressure control oil chamber is connected to the diesel inlet. The tail of the control needle valve and the bottom of the valve sleeve are both located in the high-pressure control oil chamber. Diesel enters from the diesel inlet and reaches the high-pressure control oil chamber, where it is divided into upper and lower paths.

[0006] Preferably, the diesel passage further includes a sealing surface, a flow hole, and an oil outlet of the second control chamber. The control needle valve head and the lower body of the injector form a sealing surface. The flow hole and the oil outlet of the second control chamber are both located in the lower body of the injector. The flow hole is connected to the second control chamber and the high-pressure control oil chamber, respectively. The second control chamber is opened or closed by the control needle valve. When the sealing surface is open, diesel flows downward through the flow hole into the second control chamber.

[0007] Preferably, the diesel fuel passage further includes a valve sleeve inlet, a valve sleeve outlet, and a first control chamber. The valve sleeve inlet, valve sleeve outlet, and first control chamber are all located on the valve sleeve. The first control chamber is connected to the valve sleeve outlet and the high-pressure control oil chamber, respectively. When the control valve is open, the valve sleeve outlet is opened. When the control valve is closed, the valve sleeve outlet is closed. The control valve controls the pressure of the first control chamber. Diesel fuel is the control oil, but other controllable liquids such as hydraulic oil, engine oil, or water can also be used. During operation, some control oil may leak into the fuel through the coupling. The control oil in the system needs to be replenished periodically.

[0008] Preferably, a control spring is provided in the high-pressure control oil chamber. The control spring is sleeved on the outside of the control needle valve, and both ends of the control spring are connected to the valve sleeve and the control needle valve, respectively. When the control valve opens, the oil outlet of the valve sleeve opens. The pressure in the first control chamber is controlled by the oil inlet and outlet of the valve sleeve. The flow area of ​​the oil outlet of the valve sleeve is larger than that of the oil inlet of the valve sleeve. The pressure in the first control chamber decreases and becomes lower than that in the high-pressure control oil chamber, forming an upward pressure on the control needle valve, overcoming the spring force of the control spring. The oil outlet of the sealing surface opens, and diesel flows downward through the flow hole into the second control chamber. The flow area of ​​the flow hole in the second control chamber is larger than that of the oil outlet of the second control chamber. The pressure in the second control chamber increases, and the pressure acts on the upper part of the injection needle valve, pushing the injection needle valve to move downward. The injector injects fuel in an outward-opening manner. The forces on the control needle valve include: the downward spring force of the control spring, the downward hydraulic pressure acting on the top of the control needle valve from the first control chamber, and the upward hydraulic pressure acting on the control needle valve from the high-pressure control oil chamber.

[0009] Preferably, the fuel passage further includes a fuel inlet, a flow channel, a high-pressure fuel chamber, a bottom flow channel, a nozzle head pressure chamber, and an injection sealing surface. The fuel inlet is located on the upper outer wall of the injector body, and the flow channel and the high-pressure fuel chamber are both located in the lower body of the injector body. The flow channel is connected to the high-pressure fuel chamber and the fuel inlet, respectively. The bottom flow channel and the nozzle head pressure chamber are both located inside the nozzle, and the bottom flow channel is connected to both the high-pressure fuel chamber and the nozzle head pressure chamber, respectively. The bottom end of the injection needle valve penetrates the nozzle and forms an injection sealing surface with the bottom end face of the nozzle. High-pressure diesel isolates the fuel leakage path. The high-pressure diesel pressure is higher than that of fuel, and a high-pressure diesel sealing isolation strip is set in the path where fuel may leak to isolate diesel and fuel. The fuel is a liquid with a low boiling point or high saturated vapor pressure that rapidly vaporizes at normal temperature and pressure and when injected into the engine cylinder. It is usually a new energy low-carbon, zero-carbon, or carbon cycle fuel.

[0010] Preferably, the high-pressure fuel chamber is provided with a spring seat, a needle valve limiter, and an injection spring. The spring seat, needle valve limiter, and injection spring are all sleeved on the outer wall of the needle valve, and the inner wall of the spring seat and the inner wall of the needle valve limiter are connected to the needle valve. The two ends of the injection spring are respectively connected to the spring seat and the needle valve limiter. The forces on the needle valve include: the upward spring force of the injection spring acting on the spring seat, the downward hydraulic pressure of the second control chamber acting on the top of the needle valve, and the downward hydraulic pressure of the nozzle head pressure chamber acting on the control needle valve.

[0011] Compared with the prior art, the beneficial effects of the present invention are: This invention uses diesel oil as the control oil, injecting it into the high-pressure chamber of the control oil to increase its pressure. This pressure pushes open the injection needle valve, thus opening the injector for external injection. This effectively reduces the machining difficulty of the nozzle head's injection sealing surface. High-pressure control oil (diesel oil) is used to isolate fuel (ammonia / dimethyl ether) leakage paths. The high-pressure diesel oil has a higher pressure than the fuel oil, and a high-pressure diesel oil sealing isolation zone is set in the fuel oil leakage path to improve system reliability and achieve control oil and fuel oil isolation. Attached Figure Description

[0012] Figure 1 This is a diagram of the internal structure of the present invention; In the diagram: 1. Control valve; 2. Injector upper body; 2a. Fuel inlet; 2b. Diesel inlet; 2c. Control oil high-pressure chamber; 3. Lower part of the injector; 3a. Sealing surface; 3b. Flow hole; 3c. Second control chamber; 3d. Oil outlet of the second control chamber; 3e. Flow channel; 3f. High-pressure fuel chamber; 4. Nozzle; 4a. Bottom flow channel; 4b. Nozzle head pressure chamber; 4c. Spray sealing surface; 5. Valve sleeve; 5a. Valve sleeve oil inlet; 5b. Valve sleeve oil outlet; 5c. First control chamber; 6. Control spring; 7. Control needle valve; 8. Injection needle valve; 8a. Spring seat; 8b. Injection needle valve limit switch; 9. Jet spring. Detailed Implementation

[0013] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0014] Example: Please see Figure 1 As shown, an externally opening high-pressure direct injection injector includes: The control valve 1, the injector, and the nozzle 4 are provided. The injector includes an upper body 2 and a lower body 3. The upper body 2 is located at the top of the lower body 3. The control valve 1 is located above the upper body 2. The nozzle 4 is located at the bottom of the lower body 3. The injector is equipped with a diesel fuel passage and a fuel oil passage; The diesel passage includes a valve sleeve 5, a control needle valve 7, a second control chamber 3c, and a high-pressure control oil chamber 2c. The control needle valve 7 is located inside the upper body 2 and the lower body 3 of the injector. The bottom of the valve sleeve 5 is fitted onto the outer wall of the tail of the control needle valve 7. The top of the valve sleeve 5 is located between the control valve 1 and the upper body 2 of the injector. The high-pressure control oil chamber 2c is located inside the upper body 2 of the injector. The tail of the control needle valve 7 and the bottom of the valve sleeve 5 are both located inside the high-pressure control oil chamber 2c. The second control chamber 3c is located inside the lower body 3 of the injector. The fuel passage includes an injection needle valve 8, which is located on the lower body 3 of the injector. Diesel fuel is used as control oil. Diesel fuel is injected into the high-pressure control oil chamber 2c. After the control needle valve 7 is opened, the pressure in the second control chamber 3c is increased, pushing open the injection needle valve 8, and the injector opens to inject fuel.

[0015] refer to Figure 1 As shown, the diesel passage also includes a diesel inlet 2b, which is located on the outer wall of the upper body 2 of the injector. The high-pressure control oil chamber 2c is connected to the diesel inlet 2b. Diesel enters from the diesel inlet 2b and reaches the high-pressure control oil chamber 2c, which is divided into upper and lower paths.

[0016] refer to Figure 1As shown, the diesel passage also includes a sealing surface 3a, a flow hole 3b, and a second control chamber outlet 3d. The head of the control needle valve 7 and the lower body 3 of the injector form a sealing surface 3a. The flow hole 3b and the second control chamber outlet 3d are both located inside the lower body 3 of the injector. The flow hole 3b is connected to the second control chamber 3c and the high-pressure control oil chamber 2c, respectively. The second control chamber 3c is opened or closed by the control needle valve 7. When the sealing surface 3a is open, diesel flows downward through the flow hole 3b into the second control chamber 3c.

[0017] refer to Figure 1 As shown, the diesel passage also includes a valve sleeve inlet 5a, a valve sleeve outlet 5b, and a first control chamber 5c. The valve sleeve inlet 5a, valve sleeve outlet 5b, and first control chamber 5c are all located on the valve sleeve 5. The first control chamber 5c is connected to the valve sleeve outlet 5b and the high-pressure control oil chamber 2c, respectively. When the control valve 1 is open, the valve sleeve outlet 5b is opened. When the control valve 1 is closed, the valve sleeve outlet 5b is closed. The control valve 1 controls the pressure of the first control chamber 5c. Diesel oil is the control oil, but other controllable liquids such as hydraulic oil, engine oil, and water can also be used. During operation, some control oil will leak into the fuel through the coupling. The control oil in the system needs to be replenished periodically.

[0018] refer to Figure 1 As shown, a control spring 6 is installed inside the high-pressure control oil chamber 2c. The control spring 6 is sleeved on the outside of the control needle valve 7, and its two ends are connected to the valve sleeve 5 and the control needle valve 7, respectively. When the control valve 1 is opened, the oil outlet 5b of the valve sleeve is opened. The pressure in the first control chamber 5c is controlled by the oil inlet 5a and the oil outlet 5b of the valve sleeve. The flow area of ​​the oil outlet 5b of the valve sleeve is larger than that of the oil inlet 5a of the valve sleeve, so the pressure in the first control chamber 5c decreases and falls below that in the high-pressure control oil chamber 2c, forming an upward pressure on the control needle valve 7, which overcomes the spring force of the control spring 6 and seals the surface. When oil outlet 3a is opened, diesel fuel flows downward through flow hole 3b into the second control chamber 3c. The flow area of ​​flow hole 3b in the second control chamber 3c is larger than that of oil outlet 3d in the second control chamber, and the pressure in the second control chamber 3c increases. The pressure acts on the upper part of injection needle valve 8, pushing injection needle valve 8 to move downward. The injector injects fuel in an outward-opening manner. The forces on control needle valve 7 include: the downward spring force of control spring 6, the downward hydraulic pressure acting on the top of control needle valve 7 by the first control chamber 5c, and the upward hydraulic pressure acting on control needle valve 7 by the high-pressure control oil chamber 2c.

[0019] refer to Figure 1As shown, the fuel passage also includes a fuel inlet 2a, a flow channel 3e, a fuel high-pressure chamber 3f, a bottom flow channel 4a, a nozzle head pressure chamber 4b, and an injection sealing surface 4c. The fuel inlet 2a is located on the outer wall of the upper body 2 of the injector. The flow channel 3e and the fuel high-pressure chamber 3f are both located inside the lower body 3 of the injector, and the flow channel 3e is connected to the fuel high-pressure chamber 3f and the fuel inlet 2a respectively. The bottom flow channel 3e and the nozzle head pressure chamber 4b are both located inside the nozzle 4, and the bottom flow channel 3e is connected to the fuel high-pressure chamber 3f and the nozzle head pressure chamber 4b respectively. The bottom end of the injection needle valve 8 penetrates the nozzle 4 and forms an injection sealing surface 4c with the bottom end face of the nozzle 4. High-pressure diesel isolates the fuel leakage path. The pressure of high-pressure diesel is higher than that of fuel, and a high-pressure diesel sealing isolation strip is set in the path where fuel may leak to isolate diesel and fuel. The fuel is a liquid with a low boiling point or high saturated vapor pressure that vaporizes rapidly at normal temperature and pressure and when injected into the engine cylinder. It is usually a new energy low-carbon, zero-carbon, or carbon cycle fuel.

[0020] refer to Figure 1 As shown, the fuel high-pressure chamber 3f is equipped with a spring seat 8a, an injection needle valve limiter 8b, and an injection spring 9. The spring seat 8a, the injection needle valve limiter 8b, and the injection spring 9 are all sleeved on the outer wall of the injection needle valve 8, and the inner walls of the spring seat 8a and the injection needle valve limiter 8b are connected to the injection needle valve 8. The two ends of the injection spring 9 are connected to the spring seat 8a and the injection needle valve limiter 8b, respectively. The forces on the injection needle valve 8 include: the upward spring force of the injection spring 9 acting on the spring seat 8a, the downward hydraulic pressure of the second control chamber 3c acting on the top of the injection needle valve 8, and the downward hydraulic pressure of the fuel nozzle head pressure chamber 4b acting on the control needle valve 7.

[0021] Working principle of this invention: The diesel fuel passage enters from the diesel fuel inlet 2b and reaches the high-pressure control oil chamber 2c, which is divided into two paths: the upward oil path enters the first control chamber 5c through the valve sleeve inlet 5a of the valve sleeve 5, and then exits through the valve sleeve outlet 5b to the low-pressure return oil. The valve sleeve outlet 5b is controlled by the control valve 1; the downward oil path forms a sealing surface 3a between the head of the control needle valve 7 and the lower body 3 of the injector. When the sealing surface 3a is open, the diesel fuel flows downward through the flow hole 3b into the second control chamber 3c, and then flows through the outlet 3d of the second control chamber to the low-pressure return oil. The fuel passage allows the fuel to be either ammonia or dimethyl ether, which are easily vaporized at room temperature and pressure and enter the engine cylinder. The fuel enters the injector through the fuel inlet 2a, enters the fuel high-pressure chamber 3f through the flow channel 3e, and then enters the fuel nozzle head pressure chamber 4b through the bottom flow channel 4a, reaching the injection sealing surface 4c. When the injection needle valve 8 moves downward, the injection sealing surface 4c opens, and the fuel enters the engine cylinder through the injection sealing surface 4c. To prevent fuel oil from entering the diesel fuel passage and causing failure, the diesel fuel pressure should ideally be 30-100 bar higher than the fuel oil pressure. This way, when the components leak, only the higher-pressure diesel fuel will leak into the fuel oil, which will then be injected and burned, preventing fuel oil contamination. A small amount of diesel fuel consumption and a small amount of carbon emissions are acceptable. Work is divided into two states: State 1: Control valve 1 is in the closed state, the oil outlet 5b of the valve sleeve is closed, the first control chamber 5c is under high pressure, the high pressure acts on the upper part of the control needle valve 7, forming a downward pressure on the control needle valve 7, and under the combined action of the control spring 6, the oil outlet of the sealing surface 3a is closed. At this time, the second control chamber 3c is in the low pressure state, the injection spring 9 forms an upward spring force on the injection needle valve 8 through the spring seat 8a, at this time the injection sealing surface 4c is in the closed state, and the injector does not spray oil; State 2: Control valve 1 is open, valve sleeve oil outlet 5b is open, the pressure of the first control chamber 5c is controlled by valve sleeve oil inlet 5a and valve sleeve oil outlet 5b. The flow area of ​​valve sleeve oil outlet 5b is larger than that of valve sleeve oil inlet 5a, the pressure of the first control chamber 5c decreases, and is lower than that of the high-pressure control oil chamber 2c, forming an upward pressure on the control needle valve 7, overcoming the spring force of control spring 6, the oil outlet of sealing surface 3a opens, diesel flows downward through flow hole 3b into the second control chamber 3c, the flow area of ​​flow hole 3b of the second control chamber 3c is larger than that of oil outlet 3d of the second control chamber, the pressure of the second control chamber 3c increases, this pressure acts on the upper part of injection needle valve 8, overcomes the spring force of injection spring 9, pushes injection needle valve 8 to move downward, at this time the injection sealing surface 4c opens, and the injector injects fuel; Returning to state one, the injector stops injecting fuel, and the fuel injection of the injector is controlled by opening and closing control valve 1; When the injector is in state two, the injection capacity is controlled by the downward movement of the injection needle valve 8. The stroke control of this displacement is determined by the injection needle valve limit 8b located in the middle of the injection needle valve 8. By implementing the external injection mode, the machining difficulty of the nozzle head injection sealing surface 4c can be effectively reduced, and the resistance to cavitation corrosion of the injector can be improved by using high-entropy alloys and other high-entropy materials.

[0022] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. An externally opening high-pressure direct injection injector, characterized in that, include: The control valve (1), the injector, and the nozzle (4) are provided. The injector includes an upper body (2) and a lower body (3). The upper body (2) is located at the top of the lower body (3). The control valve (1) is located above the upper body (2). The nozzle (4) is located at the bottom of the lower body (3). The injector is equipped with a diesel fuel passage and a fuel oil passage; The diesel passage includes a valve sleeve (5), a control needle valve (7), a second control chamber (3c), and a control oil high-pressure chamber (2c). The control needle valve (7) is located inside the upper body (2) and the lower body (3) of the injector. The bottom of the valve sleeve (5) is fitted onto the outer wall of the tail of the control needle valve (7). The top of the valve sleeve (5) is located between the control valve (1) and the upper body (2) of the injector. The control oil high-pressure chamber (2c) is located inside the upper body (2) of the injector. The tail of the control needle valve (7) and the bottom of the valve sleeve (5) are both located inside the control oil high-pressure chamber (2c). The second control chamber (3c) is located inside the lower body (3) of the injector. The fuel passage includes an injection needle valve (8), which is located on the lower body (3) of the injector; Diesel fuel is used as control oil. Diesel fuel is injected into the high-pressure control oil chamber (2c). After the control needle valve (7) is opened, the pressure of the second control chamber (3c) is increased, and the injection needle valve (8) is pushed open, and the injector opens to inject.

2. The externally opening high-pressure direct injection injector according to claim 1, characterized in that: The diesel passage also includes a diesel inlet (2b), which is located on the outer wall of the injector upper body (2), and the control oil high-pressure chamber (2c) is connected to the diesel inlet (2b).

3. The externally opening high-pressure direct injection injector according to claim 2, characterized in that: The diesel passage also includes a sealing surface (3a), a flow hole (3b), and a second control chamber outlet (3d). The head of the control needle valve (7) and the lower body of the injector (3) form a sealing surface (3a). The flow hole (3b) and the second control chamber outlet (3d) are both located inside the lower body of the injector (3). The flow hole (3b) is connected to the second control chamber (3c) and the high-pressure control oil chamber (2c), respectively. The second control chamber (3c) is opened or closed by the control needle valve (7). When the sealing surface (3a) is open, diesel flows downward through the flow hole (3b) into the second control chamber (3c).

4. The externally opening high-pressure direct injection injector according to claim 3, characterized in that: The diesel passage also includes a valve sleeve inlet (5a), a valve sleeve outlet (5b), and a first control chamber (5c). The valve sleeve inlet (5a), valve sleeve outlet (5b), and first control chamber (5c) are all located on the valve sleeve (5). The first control chamber (5c) is connected to the valve sleeve outlet (5b) and the high-pressure control oil chamber (2c), respectively. When the control valve (1) is open, the valve sleeve outlet (5b) is opened. When the control valve (1) is closed, the valve sleeve outlet (5b) is closed. The control valve (1) controls the pressure of the first control chamber (5c).

5. An externally opening high-pressure direct injection injector according to claim 4, characterized in that: A control spring (6) is provided inside the high-pressure chamber (2c) of the control oil. The control spring (6) is sleeved on the outside of the control needle valve (7), and both ends of the control spring (6) are connected to the valve sleeve (5) and the control needle valve (7) respectively. When the control valve (1) is opened, the oil outlet (5b) of the valve sleeve is opened. The pressure in the first control chamber (5c) is controlled by the oil inlet (5a) and the oil outlet (5b) of the valve sleeve. The flow area of ​​the oil outlet (5b) of the valve sleeve is larger than that of the oil inlet (5a) of the valve sleeve, and the pressure in the first control chamber (5c) drops. The pressure is low, below the high pressure chamber (2c) of the control oil, forming an upward pressure on the control needle valve (7), overcoming the spring force of the control spring (6), the oil outlet of the sealing surface (3a) opens, and diesel flows downward through the flow hole (3b) into the second control chamber (3c). The flow area of ​​the flow hole (3b) of the second control chamber (3c) is larger than the oil outlet (3d) of the second control chamber, the pressure of the second control chamber (3c) increases, the pressure acts on the upper part of the injection needle valve (8), pushing the injection needle valve (8) to move downward, and the injector injects fuel in an outward-opening manner.

6. The externally opening high-pressure direct injection injector according to claim 5, characterized in that: The fuel passage also includes a fuel inlet (2a), a flow channel (3e), a fuel high-pressure chamber (3f), a bottom flow channel (4a), a fuel nozzle head pressure chamber (4b), and an injection sealing surface (4c). The fuel inlet (2a) is located on the outer wall of the upper body (2) of the injector. The flow channel (3e) and the fuel high-pressure chamber (3f) are both located in the lower body (3) of the injector. The flow channel (3e) is connected to the fuel high-pressure chamber (3f) and the fuel inlet (2a) respectively. The bottom flow channel (3e) and the fuel nozzle head pressure chamber (4b) are both located in the nozzle (4). The bottom flow channel (3e) is connected to the fuel high-pressure chamber (3f) and the fuel nozzle head pressure chamber (4b) respectively. The bottom end of the injection needle valve (8) penetrates the nozzle (4) and forms an injection sealing surface (4c) with the bottom end face of the nozzle (4). High-pressure diesel isolates the fuel leakage path. The pressure of high-pressure diesel is higher than that of fuel. A high-pressure diesel sealing isolation strip is set in the path where fuel may leak to isolate diesel and fuel.

7. An externally opening high-pressure direct injection injector according to claim 6, characterized in that: The fuel high-pressure chamber (3f) is provided with a spring seat (8a), an injection needle valve limiter (8b) and an injection spring (9). The spring seat (8a), the injection needle valve limiter (8b) and the injection spring (9) are all sleeved on the outer wall of the injection needle valve (8). The inner wall of the spring seat (8a) and the inner wall of the injection needle valve limiter (8b) are connected to the injection needle valve (8). The two ends of the injection spring (9) are connected to the spring seat (8a) and the injection needle valve limiter (8b) respectively.

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