High-pressure methanol-diesel injector for realizing internal and external opening coupling of needle valve based on pilot control

Abstract

The invention aims at providing a high-pressure methanol-diesel injector capable of achieving internal and external open coupling of a needle valve based on pilot control, and belongs to the field of engines. A methanol control electromagnetic valve assembly is installed in an injector connector body, and a diesel control electromagnetic valve assembly is installed in an injector intermediate body; a hydraulic servo control inner and outer double-opening valve assembly is installed in the nozzle body, and a high-pressure diesel oil connector and a high-pressure methanol connector are installed on the side of the ejector connector body. Integrated independent injection of methanol and diesel oil is achieved through combination of the hydraulic servo control inner and outer double-opening valve assembly, the methanol control electromagnetic valve assembly and the diesel oil control electromagnetic valve assembly, methanol fuel is subjected to large-flow injection through an outward-opening needle valve structure, and meanwhile higher methanol injection pressure is achieved through combination of pilot hydraulic control; diesel is controlled by an inward-opening needle valve to conduct trace injection, the methanol and diesel injection processes are mutually independent, the cold start characteristic of the methanol engine is effectively improved, and the methanol engine has the advantages of being compact in structure, high in injection pressure, large in flow, high in response speed and the like.

Description

Technical Field

[0001] The present invention relates to an engine, specifically a fuel injector. Background Technology

[0002] Methanol fuel, synthesized from green hydrogen produced by renewable energy sources such as wind and solar power and captured carbon dioxide, can be combined with methanol engines for efficient utilization. This can reduce carbon dioxide emissions by more than 95% over its entire life cycle, making it one of the best carriers for the large-scale application of renewable energy under the current "dual-carbon" context. Vigorously promoting the development of a new generation of high-performance methanol fuel engines can achieve large-scale green methanol consumption on the energy demand side and a rapid low-carbon transformation in the internal combustion engine sector. Furthermore, compared to alternative fuels such as hydrogen and ammonia, methanol is more adaptable to the structure of existing diesel engines, allowing for low-cost transformation without large-scale modifications. Methanol's inherent fuel properties, energy endowment, and advantages in production capacity and output fully align with my country's requirements for the integrated development of transportation and green energy. Methanol engines are one of the inevitable directions for future technological development in the internal combustion engine field.

[0003] As a key actuator in the engine fuel injection system, the methanol injector's function is to provide efficiently atomized methanol spray into the engine cylinder for complete combustion. Currently, conventional electromagnetic direct-drive methanol injectors drive the needle valve by directly overcoming hydraulic pressure with electromagnetic force. This structural design results in a deep coupling between methanol injection pressure and electromagnetic force. Especially in applications where the injector's boundary dimensions are strictly limited, the electromagnetic force generated by the built-in solenoid valve is relatively limited. This physical constraint severely restricts further increases in methanol injection pressure. Furthermore, due to methanol's low calorific value, low cetane number, and high latent heat of vaporization, liquid methanol is difficult to evaporate and has poor spontaneous ignition capability, making compression ignition difficult. Micro-fuel diesel injection ignition technology is currently key to solving the cold start problem of methanol engines, but it is often difficult to install multiple injectors in the engine cylinder head. Summary of the Invention

[0004] The purpose of this invention is to provide a high-pressure methanol-diesel injector based on pilot control to achieve coupling between the inner and outer opening of the needle valve, which can realize high-pressure, high-flow methanol fuel injection and low-volume diesel fuel injection.

[0005] The objective of this invention is achieved as follows: This invention discloses a high-pressure methanol-diesel injector based on pilot control to achieve needle valve internal and external opening coupling. Its features include: an injector connector body, an injector intermediate body, a multi-port body, and a nozzle body arranged from top to bottom; a methanol control solenoid valve assembly installed in the injector connector body; a diesel control solenoid valve assembly installed in the injector intermediate body; a hydraulic servo-controlled internal and external double-opening valve assembly installed in the nozzle body; a high-pressure diesel connector and a high-pressure methanol connector installed on the side of the injector connector body; a high-pressure diesel circuit opened in the high-pressure diesel connector; a high-pressure methanol circuit opened in the high-pressure methanol connector; a methanol control outlet throttle orifice opened in the methanol control solenoid valve assembly; and a diesel control outlet throttle orifice opened in the diesel control solenoid valve assembly.

[0006] The present invention may also include: 1. The hydraulic servo-controlled double-opening valve assembly includes an internally opening needle valve, an externally opening sleeve needle valve, a valve seat body, and an internal needle valve sleeve. The internally opening needle valve is fitted with an internal needle valve sleeve on top. The internally opening needle valve has a needle valve protrusion and is fitted with an internal needle valve return spring. The internal needle valve return spring is located between the internal needle valve sleeve and the needle valve protrusion. The internally opening needle valve, the internal needle valve sleeve, and the multi-port body form a first control chamber. A diesel fuel tank is formed between the internally opening needle valve and its external nozzle body. The nozzle body below the diesel fuel tank has a spray hole. The nozzle body outside the internally opening needle valve is located within the externally opening sleeve needle valve. Inside, the externally opening sleeve needle valve includes a vertical part and an annular part. The annular part is fixed to the outside of the vertical part, and the two are an integral structure. The outer side of the lower part of the annular part is fitted with a first sleeve of the external needle valve, and the inner side of the lower part of the annular part is fitted with a second sleeve of the external needle valve. The valve seat body is located outside the vertical part and fixed to the nozzle body. The annular part, the first sleeve of the external needle valve, and the second sleeve of the external needle valve are all located above the valve seat body, forming a second control chamber between them. The inner wall of the annular part is fitted with an external needle valve return spring, and the two ends of the external needle valve return spring are located on the second sleeve of the external needle valve. Between the annular section and the inner wall of the lower part of the valve seat body, a multi-groove valve block is fixed, and the multi-groove valve block and the externally opening sleeve needle valve form a methanol groove; a high-pressure methanol chamber is formed between the externally opening sleeve needle valve and the nozzle body outside it, and an alcohol inlet is opened on the externally opening sleeve needle valve. The high-pressure methanol chamber is connected to the alcohol inlet and the high-pressure methanol path respectively. A methanol loop is formed between the valve seat body and the externally opening sleeve needle valve, and the methanol loop is connected to the alcohol inlet and the methanol groove respectively. The multi-channel body is provided with a first control chamber oil inlet path, a first control chamber oil return path and a first oil inlet throttling orifice. The first control chamber oil inlet path is connected to the first oil inlet throttling orifice. The high-pressure diesel circuit is connected to the first control chamber return oil circuit, which is connected to the diesel control outlet throttle orifice. The nozzle body is equipped with a first high-pressure diesel branch and a second high-pressure diesel branch. The first high-pressure diesel branch is connected to the high-pressure diesel circuit and the diesel tank respectively. The valve seat body is equipped with a second control chamber inlet oil circuit, a second inlet throttle orifice, and a second control chamber outlet oil circuit. The second inlet throttle orifice is connected to the second control chamber inlet oil circuit and the second control chamber respectively. The second high-pressure diesel branch is connected to the high-pressure diesel circuit and the second control chamber inlet oil circuit respectively. The second control chamber outlet oil circuit is connected to the second control chamber and the methanol control outlet throttle orifice respectively.

[0007] 2. The second control chamber is inverted. Under the action of the preload of the vertically upward external needle valve reset spring and the hydraulic pressure of the second control chamber, the bottom end of the externally opening sleeve needle valve and the multi-groove valve block are tightly fitted to form a sealing ring.

[0008] 3. In diesel micro-injection mode, current is applied to the diesel control solenoid valve assembly, and the diesel control outlet throttle orifice opens. The high-pressure diesel in the first control chamber flows back to the low-pressure source through the first control chamber return oil circuit and the diesel control outlet throttle orifice. The hydraulic pressure at the upper end of the internally opened needle valve decreases accordingly. The internally opened needle valve overcomes the preload force of the internally opened needle valve reset spring and lifts upward. The high-pressure diesel passes through the high-pressure diesel circuit, the first high-pressure diesel branch circuit, and the gap between the internally opened needle valve and the nozzle body in sequence, and is sprayed out from the nozzle.

[0009] 4. In high-flow-rate methanol injection mode, current is applied to the methanol control solenoid valve assembly, and the methanol control outlet throttle orifice opens. High-pressure diesel fuel in the second control chamber flows back to the low-pressure source sequentially through the second control chamber outlet circuit, the second control chamber return circuit, and the methanol control outlet throttle orifice. The hydraulic pressure in the second control chamber decreases, and the bottom of the annular portion of the externally opening sleeve needle valve experiences a decrease in upward hydraulic pressure. Under the overall downward hydraulic pressure, the externally opening sleeve needle valve overcomes the preload of the external needle valve return spring and opens downwards. Methanol then flows sequentially through the high-pressure methanol circuit, the high-pressure methanol chamber, the methanol inlet orifice, and the methanol loop. The methanol is ejected from the gap between the bottom of the externally opened sleeve needle valve and the multi-groove valve block. After the methanol injection is completed, the methanol control solenoid valve assembly is de-energized, the methanol control oil outlet throttle orifice is closed, and the high-pressure diesel fuel flows into the second control chamber through the second high-pressure diesel fuel branch, the second control chamber oil inlet line, and the second oil inlet throttle orifice. The pressure in the second control chamber rises, and the bottom of the annular part of the externally opened sleeve needle valve is subjected to an upward increase in hydraulic pressure. Under the combined action of the hydraulic pressure in the second control chamber and the force of the external needle valve reset spring, the externally opened sleeve needle valve closes upward, and the bottom of the externally opened sleeve needle valve and the multi-groove valve block re-form a sealing ring.

[0010] The advantages of this invention are as follows: This invention achieves integrated independent injection of methanol and diesel by combining a hydraulic servo-controlled internal and external double-opening valve assembly with a methanol control solenoid valve assembly and a diesel control solenoid valve assembly. The methanol fuel adopts an externally open needle valve structure to achieve high-flow injection, and at the same time, it combines pilot hydraulic control to achieve higher methanol injection pressure. The diesel fuel adopts an internally open needle valve control for micro-injection. The methanol and diesel injection processes are independent of each other, which effectively improves the cold start characteristics of methanol engines. It has advantages such as compact structure, high injection pressure, large flow, and fast response speed. Attached Figure Description

[0011] Figure 1 This is a schematic diagram of the structure of the present invention; Figure 2 This is a schematic diagram of the structure of a hydraulic servo control double-opening valve assembly.

[0012] Figure reference numerals: 1: Injector connector body; 2: High-pressure diesel circuit; 3: Methanol control solenoid valve assembly; 4: Intermediate body locking nut; 5: Injector intermediate body; 6: Diesel control solenoid valve assembly; 7: First inlet throttle orifice; 8: Multi-port body; 9: Nozzle locking nut; 10: Hydraulic servo control internal and external double-opening valve assembly; 11: Second control chamber return oil circuit; 12: High-pressure methanol circuit; 13: High-pressure methanol connector; 14: High-pressure diesel connector.

[0013] 1001: First control chamber oil inlet; 1002: First control chamber; 1003: Inner needle valve sleeve; 1004: First high-pressure diesel branch; 1005: Nozzle body; 1006: High-pressure methanol chamber; 1007: Second high-pressure diesel branch; 1008: Outer needle valve first sleeve; 1009: Second oil inlet throttle orifice; 1010: Second control chamber oil inlet; 1011: Valve seat body; 1012: Multi-groove Valve block; 1013: Injection hole; 1014: Methanol tank; 1015: Internally opening needle valve; 1016: Externally opening sleeve needle valve; 1017: Oil outlet of the second control chamber; 1018: Methanol loop; 1019: Second control chamber; 1020: Second sleeve of the external needle valve; 1021: Return spring of the external needle valve; 1022: Methanol inlet; 1023: Return spring of the internal needle valve; 1024: Oil return line of the first control chamber. Detailed Implementation

[0014] The invention will now be described in more detail with reference to the accompanying drawings: Implementation method 1, combined with Figure 1-2 This embodiment comprises an injector connector body 1, a methanol control solenoid valve assembly 3, an intermediate body locking nut 4, an injector intermediate body 5, a diesel control solenoid valve assembly 6, a multi-port valve 8, a nozzle locking nut 9, a hydraulic servo control internal and external double-opening valve assembly 10, a high-pressure methanol connector 13, and a high-pressure diesel connector 14. The methanol control solenoid valve assembly 3 is installed inside the injector connector body 1, and the diesel control solenoid valve assembly 6 is installed inside the injector intermediate body 5. The injector connector body 1, the injector intermediate body 5, the multi-port valve 8, and the hydraulic servo control solenoid valve 9 are installed sequentially from top to bottom inside the intermediate body locking nut 4 and the nozzle locking nut 9. The internal and external double-opening valve assembly 10 includes a high-pressure diesel circuit 2 and a high-pressure methanol circuit 12 inside the injector connector body 1, the injector intermediate body 5, and the multi-pass body 8. The multi-pass body 8 has a first oil inlet throttle hole 7, which is connected to the high-pressure diesel circuit 2. The hydraulic servo-controlled internal and external double-opening valve assembly 10 includes a nozzle body 1005. The nozzle body 1005, the multi-pass body 8, and the injector intermediate body 5 have a second control chamber return oil circuit 11 inside. The second control chamber return oil circuit 11 is connected to the methanol control solenoid valve assembly 3. The methanol control solenoid valve assembly 3 and the diesel control solenoid valve assembly 6 both have an oil outlet throttle hole inside.

[0015] In embodiment 2, based on embodiment 1, the hydraulic servo-controlled double-opening valve assembly 10 includes a first control chamber oil inlet 1001, an inner needle valve sleeve 1003, a nozzle body 1005, an outer needle valve first sleeve 1008, a valve seat body 1011, a multi-groove valve block 1012, an inner-opening needle valve 1015, an outer-opening sleeve needle valve 1016, an outer needle valve second sleeve 1020, an outer needle valve return spring 1021, an inner needle valve return spring 1023, and a first control chamber oil return 1024. The nozzle body 1005 has a first high-pressure diesel branch 1004 and a second high-pressure diesel branch 1007, which are connected to the high-pressure diesel circuit 2. The valve seat body 1011 has a first... The second oil inlet throttle orifice 1009, the second control room oil inlet passage 1010, and the second control room oil outlet passage 1017 are connected. The second control room oil outlet passage 1017 is connected to the second control room return passage 11. The second control room oil inlet passage 1010 is connected to the second high-pressure diesel branch passage 1007. The inner needle valve sleeve 1003 is fitted on top of the inner-opening needle valve 1015. The inner needle valve sleeve 1003, the inner-opening needle valve 1015, and the multi-port body 8 together form the first control room 1002. The first control room oil inlet passage 1001 and the first control room return passage 1024 are both located inside the multi-port body 8. The first control room return passage 1024 is connected to the oil outlet throttle orifice located inside the diesel control solenoid valve assembly 6. The outer needle valve first sleeve 1008 is fitted on the outer-opening sleeve needle valve 1002. On the outside of 16, the second sleeve 1020 of the outer needle valve is installed inside the outer-opening sleeve needle valve 1016. The valve seat body 1011, the first sleeve 1008 of the outer needle valve, the second sleeve 1020 of the outer needle valve, and the outer-opening sleeve needle valve 1016 together form the second control chamber 1019. The second control chamber 1019 is connected to the second oil inlet throttle hole 1009, the second control chamber oil inlet passage 1010, and the second control chamber oil outlet passage 1017. The nozzle body 1005 and the outer-opening sleeve needle valve 1016 cooperate to form the high-pressure methanol chamber 1006. The high-pressure methanol chamber 1006 is connected to the high-pressure methanol passage 12. The multi-groove valve block 1012 is fixedly connected to the valve seat body 1011, and the valve seat body 1011 is fixedly connected to the nozzle body 1005. The inner side of the multi-groove valve block 1012 is provided with Multiple annularly distributed grooves are provided. The multi-groove valve block 1012 cooperates with the externally opening sleeve needle valve 1016 to form a methanol groove 1014. The valve seat body 1011 and the externally opening sleeve needle valve 1016 cooperate to form a methanol loop 1018. The externally opening sleeve needle valve 1016 has a methanol inlet hole 1022 at its top. The high-pressure methanol chamber 1006 is connected to the methanol loop 1018 through the methanol inlet hole 1022. The external needle valve return spring 1021 is installed between the external needle valve second sleeve 1020 and the externally opening sleeve needle valve 1016. The internal needle valve return spring 1023 is installed between the internal needle valve sleeve 1003 and the internally opening needle valve 1015. Under the preload force of the internal needle valve return spring 1023 and the hydraulic pressure, the internally opening needle valve 1015 sits on the nozzle body 1005.The nozzle body 1005 has a spray hole 1013 at its bottom.

[0016] In embodiment 3, based on embodiment 2, the second control chamber 1019 is inverted. Under the preload of the vertically upward external needle valve reset spring 1021 and the hydraulic pressure of the second control chamber 1019, the bottom end of the externally opening sleeve needle valve 1016 and the multi-groove valve block 1012 are tightly fitted to form a sealing ring.

[0017] In implementation method 4, based on implementation method 1, in diesel micro-injection mode, current is applied to the diesel control solenoid valve assembly 6, opening the internal oil outlet throttling orifice. High-pressure diesel in the first control chamber 1002 flows back to the low-pressure source through the first control chamber return oil circuit 1024 and the internal oil outlet throttling orifice of the diesel control solenoid valve assembly 6, reducing the diesel pressure in the first control chamber 1002. Consequently, the hydraulic pressure at the upper end of the internally opened needle valve 1015 decreases. Under the action of its lower end hydraulic pressure, the internally opened needle valve 1015 overcomes the preload force of the internal needle valve return spring 1023 and lifts upwards. High-pressure diesel fuel sequentially passes through high-pressure diesel fuel line 2, first high-pressure diesel fuel branch line 1004, and the gap between the internally open needle valve 1015 and the nozzle body 1005, and is finally sprayed out from the nozzle 1013 to perform diesel micro-injection. After the injection is completed, the diesel control solenoid valve assembly 6 is de-energized, and the oil outlet throttling orifice inside the diesel control solenoid valve assembly 6 is closed. High-pressure diesel fuel flows into the first control chamber 1002 through the first oil inlet throttling orifice 7 and the first control chamber oil inlet line 1001. After the first control chamber 1002 is pressurized, the internally open needle valve 1015 quickly sits down under hydraulic pressure, ending the diesel injection.

[0018] In Implementation 5, based on Implementation 1, under the high-flow methanol injection mode, current is applied to the methanol control solenoid valve assembly 3, and the internal oil outlet throttle orifice of the methanol control solenoid valve assembly 3 opens. The high-pressure diesel fuel in the second control chamber 1019 flows back to the low-pressure source through the second control chamber oil outlet path 1017, the second control chamber return path 11, and the internal oil outlet throttle orifice of the methanol control solenoid valve assembly 3. The hydraulic pressure in the second control chamber 1019 decreases rapidly, and the upward force of the fuel fuel in the second control chamber 1019 on the bottom of the side wing of the externally open sleeve needle valve 1016 decreases. Under the action of the overall downward hydraulic pressure, the externally open sleeve needle valve 1016 overcomes the preload force of the external needle valve return spring 1021 and opens downward. Methanol flows through the high-pressure methanol path 12, the high-pressure methanol chamber 1006, the methanol inlet 1022, the methanol loop 1018, and the methanol tank 1014 in sequence, and is finally ejected from the gap between the bottom of the externally open sleeve needle valve 1016 and the multi-groove valve block 1012, performing high-flow methanol injection. Due to the externally open... The actuation of the sleeve needle valve 1016 is pilot-controlled by the high-pressure diesel fuel in the second control chamber 1019. Therefore, there is no coupling relationship between the methanol end liquid pressure and the electromagnetic force of the methanol control solenoid valve assembly 3. Even a small electromagnetic force can achieve methanol externally open high-pressure and high-flow injection. After the methanol injection is completed, the methanol control solenoid valve assembly 3 is de-energized, and the oil outlet throttle orifice inside the methanol control solenoid valve assembly 3 is closed. The high-pressure diesel fuel flows into the second control chamber 1019 through the second high-pressure diesel branch 1007, the second control chamber oil inlet 1010, and the second oil inlet throttle orifice 1009. The pressure in the second control chamber 1019 rises, and the upward force of the fuel in the second control chamber 1019 on the bottom of the externally open sleeve needle valve 1016 increases. Under the combined force of the liquid pressure in the second control chamber 1019 and the force of the external needle valve return spring 1021, the externally open sleeve needle valve 1016 closes upward. The bottom of the externally open sleeve needle valve 1016 and the multi-groove valve block 1012 re-form a sealing ring, ending the methanol injection.

[0019] This invention achieves integrated independent injection of methanol and diesel fuel by coordinating a hydraulic servo-controlled double-opening valve assembly 10, a methanol control solenoid valve assembly 3, and a diesel control solenoid valve assembly 6. The methanol fuel is controlled by an externally opening sleeve needle valve 1016 to achieve high-flow injection, while pilot hydraulic control is combined to achieve higher methanol injection pressure. The diesel fuel is controlled by an internally opening needle valve 1015 for micro-injection. It has the advantages of compact structure, high injection pressure, large flow rate, and fast response speed.

Claims

1. A high-pressure methanol-diesel injector based on pilot control to achieve internal and external coupling of the needle valve, characterized in that: The system includes, from top to bottom, an injector connector body, an injector intermediate body, a multi-pass body, and a nozzle body. The injector connector body houses a methanol control solenoid valve assembly, the injector intermediate body houses a diesel control solenoid valve assembly, and the nozzle body houses a hydraulic servo-controlled internal and external double-opening valve assembly. A high-pressure diesel connector and a high-pressure methanol connector are installed on the side of the injector connector body. A high-pressure diesel circuit is provided in the high-pressure diesel connector, and a high-pressure methanol circuit is provided in the high-pressure methanol connector. The methanol control solenoid valve assembly has a methanol control outlet throttle orifice, and the diesel control solenoid valve assembly has a diesel control outlet throttle orifice.

2. A high-pressure methanol-diesel injector based on pilot control to achieve internal and external coupling of the needle valve, as described in claim 1, is characterized in that: The hydraulic servo-controlled double-opening valve assembly includes an inward-opening needle valve, an outward-opening sleeve needle valve, a valve seat, and an inward-opening needle valve sleeve. The inward-opening needle valve is fitted with the inward-opening needle valve sleeve on top, and has a needle valve protrusion. An inward-opening needle valve return spring is fitted onto the inward-opening needle valve and is located between the inward-opening needle valve sleeve and the needle valve protrusion. The inward-opening needle valve, the inward-opening needle valve sleeve, and the multi-port body form a first control chamber. A diesel fuel tank is formed between the inward-opening needle valve and its external nozzle body. A nozzle orifice is opened on the nozzle body below the diesel fuel tank. The nozzle body outside the inward-opening needle valve is located within the outer sleeve needle valve... Internally, the outward-opening sleeve needle valve includes a vertical part and an annular part. The annular part is fixed to the outside of the vertical part, and the two are an integral structure. A first sleeve of the outer needle valve is fitted onto the outer side of the lower part of the annular part, and a second sleeve of the outer needle valve is fitted onto the inner side of the lower part of the annular part. The valve seat body is located outside the vertical part and fixed to the nozzle body. The annular part, the first sleeve of the outer needle valve, and the second sleeve of the outer needle valve are all located above the valve seat body, forming a second control chamber between them. An outer needle valve return spring is fitted onto the inner wall of the annular part, and the two ends of the outer needle valve return spring are located between the second sleeve of the outer needle valve and... Between the annular sections, a multi-groove valve block is fixed to the inner wall of the lower part of the valve seat body. The multi-groove valve block and the outward-opening sleeve needle valve form a methanol tank. A high-pressure methanol chamber is formed between the outward-opening sleeve needle valve and its external nozzle body. An inlet port is opened on the outward-opening sleeve needle valve. The high-pressure methanol chamber is connected to the inlet port and the high-pressure methanol path respectively. A methanol loop is formed between the valve seat body and the outward-opening sleeve needle valve. The methanol loop is connected to the inlet port and the methanol tank respectively. A first control chamber oil inlet path, a first control chamber oil return path, and a first oil inlet throttling orifice are provided in the multi-channel body. The first control chamber oil inlet path is connected to the first oil inlet throttling orifice. The high-pressure diesel circuit is connected to the first control chamber return oil circuit, which is connected to the diesel control outlet throttle orifice. The nozzle body is equipped with a first high-pressure diesel branch and a second high-pressure diesel branch. The first high-pressure diesel branch is connected to the high-pressure diesel circuit and the diesel tank respectively. The valve seat body is equipped with a second control chamber inlet oil circuit, a second inlet throttle orifice, and a second control chamber outlet oil circuit. The second inlet throttle orifice is connected to the second control chamber inlet oil circuit and the second control chamber respectively. The second high-pressure diesel branch is connected to the high-pressure diesel circuit and the second control chamber inlet oil circuit respectively. The second control chamber outlet oil circuit is connected to the second control chamber and the methanol control outlet throttle orifice respectively.

3. A high-pressure methanol-diesel injector based on pilot control to achieve internal and external coupling of the needle valve, as described in claim 2, is characterized in that: The second control chamber is inverted. Under the action of the preload of the vertically upward external needle valve reset spring and the hydraulic pressure of the second control chamber, the bottom end of the externally opening sleeve needle valve and the multi-groove valve block are tightly fitted to form a sealing ring.

4. A high-pressure methanol-diesel injector based on pilot control to achieve internal and external coupling of the needle valve, as described in claim 1, is characterized in that: In diesel micro-injection mode, current is applied to the diesel control solenoid valve assembly, and the diesel control outlet throttle orifice opens. The high-pressure diesel in the first control chamber flows back to the low-pressure source through the first control chamber return oil circuit and the diesel control outlet throttle orifice. The hydraulic pressure at the upper end of the internally opened needle valve decreases accordingly. The internally opened needle valve overcomes the preload force of the internally opened needle valve reset spring and lifts upward. The high-pressure diesel passes through the high-pressure diesel circuit, the first high-pressure diesel branch circuit, and the gap between the internally opened needle valve and the nozzle body in sequence, and is sprayed out from the nozzle.

5. A high-pressure methanol-diesel injector based on pilot control to achieve internal and external coupling of the needle valve, as described in claim 1, is characterized in that: In high-flow-rate methanol injection mode, current is applied to the methanol control solenoid valve assembly, opening the methanol control outlet throttle orifice. High-pressure diesel fuel in the second control chamber flows back to the low-pressure source sequentially through the second control chamber outlet circuit, the second control chamber return circuit, and the methanol control outlet throttle orifice. This reduces the hydraulic pressure in the second control chamber, causing an upward hydraulic pressure reduction at the bottom of the annular portion of the externally opening sleeve needle valve. Under the overall downward hydraulic pressure, the externally opening sleeve needle valve overcomes the preload of the external needle valve return spring and opens downwards. Methanol then flows sequentially through the high-pressure methanol circuit, the high-pressure methanol chamber, the methanol inlet, the methanol loop, and the methanol tank. Methanol is ejected from the gap between the bottom of the outward-opening sleeve needle valve and the multi-groove valve block. After the methanol injection is completed, the methanol control solenoid valve assembly is de-energized, the methanol control oil outlet throttle orifice is closed, and high-pressure diesel flows into the second control chamber through the second high-pressure diesel branch, the second control chamber oil inlet, and the second oil inlet throttle orifice. The pressure in the second control chamber rises, and the bottom of the annular part of the outward-opening sleeve needle valve is subjected to an upward increase in hydraulic pressure. Under the combined force of the hydraulic pressure in the second control chamber and the force of the needle valve reset spring, the outward-opening sleeve needle valve closes upward, and the bottom of the outward-opening sleeve needle valve and the multi-groove valve block re-form a sealing ring.

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