Low-carbon fuel booster pump and flexible fuel injection system

Abstract

The present invention relates to a low-carbon fuel booster pump and flexible fuel injection system, comprising a low-carbon fuel booster pump and a fuel injector, wherein the low-carbon fuel booster pump is connected to the fuel injector, and is provided with a built-in suction valve module and a constant-volume delivery valve structure, used for high-pressure buildup of low-carbon fuel and for enabling independent control of high-pressure injection of low-carbon fuel and diesel; a diesel fuel circuit reuse module is used for simultaneously driving a booster piston, lubricating kinematic pairs, and sealing the low-carbon fuel; the fuel injector is an independent inner-and-outer needle valve injector, which comprises an inner needle valve and an outer needle valve for respectively controlling independent injection of diesel and low-carbon fuel; and a relief valve assembly and a purge valve assembly are used for realizing fuel relief and inert gas purge under fault conditions. The system of the present invention enables high-pressure injection of both alternative fuels and diesel, whilst also adapting to different injection quantity requirements of different fuels.

Description

A low-carbon fuel booster pump and flexible fuel injection system Technical Field

[0001] This invention relates to fuel injection technology for high-power medium-speed marine engines, and is particularly suitable for dual-mode injection of low-carbon / zero-carbon fuels such as methanol and ammonia with diesel. It achieves flexible fuel switching, reliable high-pressure build-up, and safe redundant control by integrating a booster pump and an independent needle valve injector. Background Technology

[0002] With increasingly stringent ship emission standards, research into alternative energy sources for marine engines is becoming increasingly important. Low-carbon fuel methanol and zero-carbon fuel ammonia, as emerging fuels, can effectively reduce emissions, have relatively mature production technologies, and their refining processes are clean and environmentally friendly, offering broad market prospects. Developing a dual-fuel fuel injection system (including injectors, injection pumps, and other key components) based on the existing diesel engine injection system structure is an important approach to the renewable energy transformation of marine engines. However, due to limitations in engine and ship installation space, installing one or more larger alternative fuel injection systems on the original main engine is almost unacceptable to engine manufacturers or ship owners. Therefore, a flexible fuel injection system solution that uses a single injection system to switch between diesel and alternative fuel modes is emerging. However, the development of flexible fuel injection devices based on modified diesel engine injectors faces the following technical challenges:

[0003] Low-carbon fuels present challenges in pressure build-up. Low-carbon fuels typically exhibit high saturation pressure, low viscosity, and poor lubricity. When using a traditional inlet-flow-regulated high-pressure fuel plunger pump for pressure build-up, fuel cavitation easily occurs, making it difficult for the plunger assembly to establish a complete oil film. This leads to cavitation in the inlet flow control valve of the traditional high-pressure fuel pump, severe wear of the plunger assembly, and consequently, an inability to achieve controllable flow during the low-carbon fuel pressure build-up process. Significant leakage occurs during pressure build-up, rendering the traditional high-pressure fuel pump inoperable.

[0004] Low-carbon fuel injection systems typically require an additional high-pressure servo oil supply system for pressurization and sealing of the low-carbon fuel. This increases system complexity, makes system layout more difficult within limited space, and introduces additional leakage risks, thus reducing the overall reliability of the system.

[0005] Low-carbon fuel injection systems require a fuel injection method that allows for independent injection of diesel and low-carbon fuels with flexible and adjustable timing. Furthermore, to achieve independent injection control and flexible timing for both fuels while simultaneously enabling diesel and low-carbon fuel injection, a new injector structure undoubtedly needs to be designed.

[0006] Alternative fuels have poor lubricity. The lubrication of the moving parts of the fuel injection system needs to be carefully considered to ensure the service life of the injection system.

[0007] The two alternative fuels mentioned above are toxic and corrosive, and have low flash points, posing an explosion risk. Leakage protection measures for the injection device need to be given special consideration to ensure the safety of life and property at the site.

[0008] The following problems exist when converting a traditional diesel injection system to a dual-fuel system:

[0009] 1. Low viscosity of low-carbon fuels leads to cavitation wear in plunger pumps (as addressed in CN118499167A).

[0010] 2. Requires an additional high-pressure servo oil system (such as CN117552907A, which still relies on an independent control oil circuit);

[0011] 3. Risk of residual fuel vaporization during fuel switching (current technology lacks an effective purging mechanism).

[0012] The present invention solves the above-mentioned defects by reusing diesel fuel lines, using an equal-capacity delivery valve and a purging assembly. Summary of the Invention

[0013] This invention proposes a low-carbon fuel booster pump and a flexible fuel injection system with independent internal and external needle valve injectors. It can inject alternative fuels at high pressure, as well as diesel fuel, and can adapt to different fuel injection volume requirements. Its beneficial effects include: 1) Rapid and reliable low-carbon fuel pressure build-up: The booster pump has a built-in suction valve module, enabling rapid pressure build-up during the new fuel boosting process, and preventing secondary lifting of the needle valve after new fuel injection ends; 2) Equal-capacity delivery valve design: The delivery valve on the booster pump adopts an equal-capacity design, ensuring that the injector and pipeline maintain a residual new fuel pressure of 80-150 bar in the non-injection range, facilitating rapid pressure build-up of the new fuel in the booster pump; 3) The system has a simple structure and does not require an additional high-pressure servo oil supply system. The existing high-pressure diesel pump can achieve low-carbon fuel pressure building, sealing, lubrication, and high-pressure diesel injection. 4) The highly integrated design of the booster control valve and oil suction and discharge valve group reduces the size of the booster pump and makes the system easier to arrange. 5) The system has high safety redundancy. The addition of a vent valve and purge valve assembly to the injector sleeve ensures the release and purging functions of methanol fuel in the event of a system failure, increasing the system's safety redundancy. 6) The system's oil circuit layout is simple and efficient. The diesel oil circuit not only serves as the fuel supply circuit for diesel injection, but also has the functions of low-carbon fuel boosting, circulating cooling, lubrication of moving parts, and low-carbon fuel sealing in low-carbon fuel mode. The system does not require an additional high-pressure sealing oil circuit to achieve the above functions.

[0014] To achieve the above objectives, the technical solution of the present invention is: a low-carbon fuel booster pump and a flexible fuel injection system, characterized in that it comprises: a low-carbon fuel booster pump and a fuel injector.

[0015] The low-carbon fuel booster pump is connected to the fuel injector and has a built-in suction valve module and an equal-capacity outlet valve structure. It is used for high-pressure build-up of low-carbon fuel and to achieve independent control of high-pressure injection of low-carbon fuel and diesel. The diesel fuel circuit reuse module is used to drive the booster piston, lubricate the moving parts, and seal the low-carbon fuel.

[0016] The fuel injector is an independent inner and outer needle valve type injector, which includes an inner needle valve and an outer needle valve to control the independent injection of diesel and low-carbon fuel respectively; it adopts a venting valve assembly and a purging valve assembly to realize fuel venting and inert gas purging in fault mode.

[0017] Furthermore, the low-carbon fuel booster pump includes: an electromagnet, a booster control slide valve assembly, a booster piston, and a main control valve assembly. The booster control slide valve assembly is installed on the booster pump cover at the upper end of the booster pump housing, and switches the diesel drive oil circuit by driving the slide valve main valve core through the electromagnet. The booster piston is installed below the booster control slide valve assembly and is pushed by high-pressure diesel to compress the low-carbon fuel chamber. The main control valve assembly is installed between the booster piston and the outer flange outlet, and consists of a suction valve and an equal-capacity discharge valve. The suction valve spring and the discharge valve spring cooperate to achieve rapid pressure build-up.

[0018] Furthermore, the booster control spool valve assembly includes: an armature, a spool valve pilot rod, and a spool valve main valve core. The spool valve main valve core is disposed within the control spool valve housing. The upper end of the spool valve pilot rod passes sequentially through the spool valve main valve core, the spool valve spring, the armature adjusting shim, and the armature seat, and is then fixedly connected by an adjusting shim. The upper side of the control spool valve housing has a control oil passage, and the lower side has a control diesel inlet. The bottom of the spool valve main valve core has an oblique hole, and the upper side has a horizontal through hole. The spool valve pilot rod and the armature are linked, with a response time ≤2ms. The bottom of the control spool valve housing has a spool valve bottom stop to limit the valve core stroke and prevent overshoot.

[0019] Furthermore, the main control valve assembly includes a suction valve core, a suction valve spring, a double-core valve housing, an outlet valve core, and an outlet valve spring. The upper part of the double-core valve housing is provided with a suction valve core with a suction valve spring, and the lower part is provided with an outlet valve core with an outlet valve spring, forming an equal-capacity outlet valve.

[0020] Furthermore, the equal-volume outlet valve maintains a pipeline pressure of 80–150 bar in the non-injection zone, and its spring preload is adjustable to adapt to different fuel characteristics.

[0021] Furthermore, the fuel injector includes a vent valve housing, a solenoid valve assembly, an injector body, a control valve stem, a needle valve spring, a limit rod, a spring guide sleeve, and a double needle assembly. The vent valve assembly and vent valve housing are mounted on the top of the injector body via a top cap; the side of the top cap has a vent hole communicating with the vent valve assembly; the solenoid valve assembly, control valve stem, and needle valve spring are sequentially installed from top to bottom inside the injector body; the spring guide sleeve and the double needle assembly are installed at the bottom of the injector body via a connecting nut, and the spring guide sleeve contains a limit rod and a needle valve spring; the double needle assembly contains a new fuel reservoir and a diesel fuel reservoir, and its side contains a high-pressure low-carbon / zero-carbon fuel channel and a high-pressure diesel fuel channel; the injector body contains a high-pressure diesel common rail pipeline and a low-carbon fuel double-wall pipeline; a purge valve assembly is mounted on the injector body, located opposite the low-carbon / zero-carbon fuel inlet; the purge valve assembly is inertized by nitrogen gas after venting.

[0022] Furthermore, the needle valve spring in the dual-needle assembly controls the opening and closing of the injection orifice in the diesel fuel reservoir; the outer needle valve independently controls the low-carbon fuel injection orifice through the coordinated action of the low-carbon fuel pressure and the spring; the solenoid valve assembly has an oil outlet throttling orifice, which reduces the control chamber pressure to achieve diesel injection when energized.

[0023] Furthermore, the relief valve assembly includes: a relief valve drive piston, a relief valve outer valve core, and a relief valve inner valve core. The relief valve outer valve core contains the relief valve inner valve core, and the upper end is provided with the relief valve drive piston. The relief valve drive piston, which is normally open when the power is off, is driven by air starting from the main unit. The relief valve inner valve core and the relief valve outer valve core achieve double sealing.

[0024] Furthermore, the diesel fuel circuit reuse module injects low-pressure sealing oil through a one-way valve when the booster piston resets, maintaining the integrity of the oil film on the plunger assembly.

[0025] Furthermore, the system supports automatic fuel mode switching, including: switching and purging between diesel injection mode and low-carbon injection mode, and venting and purging in fault mode;

[0026] In diesel injection mode, nitrogen gas is used to backwash the low-carbon fuel pipeline via the purge valve;

[0027] In low-carbon injection mode, diesel fuel continuously circulates to cool the injectors and lubricate the moving parts.

[0028] The injection system proposed in this invention, while achieving the intended function, can produce the following beneficial effects:

[0029] (1) The low-carbon fuel pressure building method is highly reliable, and there will be no excessive local pressure loss leading to fuel vaporization during the low-carbon fuel pressurization and intake process. In addition, the system structure is simple and does not require an additional high-pressure servo oil supply system. The existing high-pressure diesel pump can be used to achieve low-carbon fuel pressure building, sealing, lubrication and high-pressure diesel injection.

[0030] (2) The highly integrated design of the booster control valve and the oil suction and discharge valve group reduces the size of the booster pump, making the system easier to arrange;

[0031] (3) The rapid pressure build-up capability of low-carbon / zero-carbon fuels avoids the secondary lifting situation during methanol injection on the one hand, and also prevents the vaporization of residual low-carbon / zero-carbon fuels in the non-injection zone injector under the high temperature environment of the cylinder head on the other hand.

[0032] (4) The oil outlet valve on the booster pump adopts an equal-capacity structure design to ensure that the injector and pipeline maintain a pressure of 80-150 bar in the non-injection range, so as to provide a guarantee for rapid pressure build-up for the next injection.

[0033] (5) Flexible fuels: The system can inject diesel or other new green fuels. At the same time, the injector is an integrated design of three functions: low carbon fuel injection, diesel main ignition injection, and internal and external needle valve design. The diesel injection part integrates main injection and micro injection, which can achieve stable injection within a wide flow range. The injector has a high degree of integration, which reduces the number of fuel injectors required on the engine cylinder head and reduces the difficulty of fuel injection system layout.

[0034] (6) Added venting and purging functions in the injector failure mode to increase the safety redundancy of the injector.

[0035] (7) The system has a simple and efficient oil circuit layout. The diesel oil circuit not only serves as the fuel supply circuit for diesel injection, but also has the functions of low-carbon fuel boosting, circulating cooling, lubrication of moving parts and low-carbon fuel sealing in low-carbon fuel mode. The system does not require an additional high-pressure sealing oil circuit to achieve the above functions. Attached Figure Description

[0036] Figure 1 is a schematic diagram of a low-carbon fuel booster pump;

[0037] Figure 2 is a schematic diagram of the booster control slide valve assembly of a low-carbon fuel booster pump;

[0038] Figure 3 is a schematic diagram of the main control valve group structure of the low-carbon fuel booster pump;

[0039] Figure 4 is a schematic diagram of the fuel injector structure;

[0040] Figure 5 is a schematic diagram of the overall structure of the relief valve assembly;

[0041] Figure 6 is a simplified structural diagram of the low-carbon fuel booster pump and the low-carbon fuel injection system. Detailed Implementation

[0042] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0043] As shown in Figure 1(a) and (b), the low-carbon fuel booster pump includes a solenoid valve locking nut 001, an electromagnet 002, a booster pump cover 003, a booster control slide valve assembly 004, a booster pump housing 005, a booster piston 006, a control valve assembly 007, an oil outlet adapter block 008, an external flange 009, a sealing oil check valve assembly 010, and a disc spring 011.

[0044] A booster pump cover 003 is fixedly connected to the upper end of the booster pump housing 005. A booster control slide valve assembly 004 is installed inside the booster pump cover 003. An electromagnet 002 is connected to the upper end of the booster control slide valve assembly 004. The electromagnet 002 is installed on the top of the booster pump cover 003 via a solenoid valve locking nut 001, and a disc spring 011 is provided between the booster pump cover 003 and the electromagnet 002. A booster piston 006 is provided at the lower end of the control slide valve assembly 004. The side of the booster piston 006 is connected to a sealing oil check valve assembly 010. The oil chamber at the upper end of the plug 006 is connected to the diesel return port; the pump cover 003 of the booster pump is equipped with a control valve corresponding to the control slide valve group 004 to control the high-pressure diesel inlet of the oil circuit; the booster piston 006 inside the booster pump housing 005 is equipped with a low-carbon (new) fuel booster chamber at the lower end, and the low-carbon (new) fuel booster chamber is equipped with a control valve group 007, an oil outlet adapter block 008 and an outer flange 009 connected to it; the side of the control valve group 007 is connected to the high-pressure low-carbon / zero-carbon fuel inlet, and the lower end of the outer flange 009 is equipped with a high-pressure low-carbon / zero-carbon fuel outlet.

[0045] As shown in Figure 2(a) and (b), the booster control valve assembly 004 of the low-carbon fuel booster pump includes an armature seat 012, an armature 013, a pilot valve stem 014, an armature adjusting shim 015, a control valve body 016, a main valve core 017, a bottom stop 018, a valve spring 019, an adjusting shim 020, and related orifice arrangements.

[0046] The lower end of the armature seat 012 is provided with a control spool valve body 016 and a bottom stop 018 of the spool valve. The control spool valve body 016 is provided with a spool valve main valve core 017. The upper end of the spool valve pilot valve rod 014 passes through the spool valve main valve core 017, the spool valve spring 019, the armature adjusting shim 015, and the armature seat 012 in sequence and is fixedly connected by adjusting shim 020. The upper side of the control spool valve body 016 is provided with a control oil passage and the lower side is provided with a control diesel inlet. The bottom of the spool valve main valve core 017 is provided with an oblique hole and the upper side is provided with a horizontal through hole.

[0047] As shown in Figure 3, the main control valve group 007 of the low-carbon fuel booster pump includes a suction valve core 021, a suction valve spring 022, a double-core valve housing 023, an oil outlet valve core 024, and an oil outlet valve spring 025.

[0048] The upper part of the double-core valve housing 023 is provided with an oil suction valve core 021 with an oil suction valve spring 022, and the lower part is provided with an oil discharge valve core 024 with an oil discharge valve spring 025, forming an equal-capacity oil discharge valve.

[0049] As shown in Figures 4(a) and (b), the fuel injector includes a vent valve housing 026, a vent valve assembly 027, a top cap 028, a purge valve assembly 029, a solenoid valve assembly 030, an injector body 031, a control valve stem 032, a needle valve spring 033, a limit rod 034, a spring guide sleeve 035, a connecting nut 036, and a double needle assembly 037, etc.

[0050] The top of the injector body 031 is equipped with a relief valve assembly 027 and a relief valve housing 026 via a top cap 028; the side of the top cap 028 is provided with a relief hole that connects to the relief valve assembly 027; inside the injector body 031, from top to bottom, are a solenoid valve assembly 030, a control valve rod 032, and a needle valve spring 033; at the bottom of the injector body 031, a spring guide sleeve 035 and a double needle assembly 037 are installed via a connecting nut 036; the spring guide sleeve 035 is provided with a limit rod 034 and a needle valve spring 033; the double needle assembly 037 is provided with a new fuel tank A and a diesel fuel tank B, and has a high-pressure low-carbon / zero-carbon fuel channel and a high-pressure diesel fuel channel on its side; the injector body 031 is provided with a high-pressure diesel common rail pipeline and a low-carbon fuel double-wall pipeline; a purge valve assembly 029 is installed on the injector body 031, and the purge valve assembly 029 is located opposite the low-carbon / zero-carbon fuel inlet.

[0051] As shown in Figure 5, the relief valve assembly 027 includes a relief valve drive piston 038, a relief valve outer valve core 039, and a relief valve inner valve core 040. The relief valve inner valve core 040 is located inside the relief valve outer valve core 039, and the relief valve drive piston 038 is located at its upper end.

[0052] As shown in Figure 6, the low-carbon fuel injection system of the present invention includes a fuel injector, a low-carbon fuel booster pump, and a corresponding high-pressure pipeline and a new fuel welded double-walled pipe structure.

[0053] The low-carbon fuel booster pump has a built-in suction valve module and an equal-capacity outlet valve structure, which is used for high-pressure build-up of low-carbon fuel and independent control of fuel injector injection.

[0054] The fuel injector is an independent internal and external needle valve type injector, which includes an internal needle valve and an external needle valve to control the independent injection of diesel and low-carbon fuel respectively; the fuel injector is also equipped with an injector purging valve, which introduces a high-pressure oil circuit for low-carbon fuel to remove all the low-pressure low-carbon fuel remaining in the injector, thereby achieving inerting of the low-carbon fuel oil circuit, preventing the low-carbon fuel remaining in the injector from vaporizing under the high temperature of the engine, thus preventing leakage, as well as the venting and purging function in fault mode.

[0055] The low-carbon fuel booster pump and low-carbon fuel injection system proposed in this invention can achieve high-pressure injection of alternative fuels, as well as diesel fuel, and can adapt to the different injection volume requirements of different fuels. Its main functions are as follows:

[0056] (1) Low-carbon fuel high-pressure build-up and independent injection control;

[0057] (2) Diesel fuel injection function;

[0058] (3) The sealing and lubrication function of diesel fuel for the turbocharged piston plunger assembly;

[0059] (4) Switching between fuel modes and purging function;

[0060] (5) Discharge and purging functions under fault mode;

[0061] The implementation principles of the above functions are explained as follows:

[0062] 1) Low-carbon fuel high-pressure build-up and independent injection control

[0063] Before boosting and injection begin, low-pressure supplied low-carbon / zero-carbon fuel enters the booster pump through the low-pressure low-carbon fuel inlet. The hydraulic pressure acting on the conical surface of the suction valve core 021 opens the fuel, allowing it to enter the low-carbon (new) fuel boosting chamber. High-pressure diesel fuel from the diesel high-pressure common rail, used as driving oil, enters the booster pump through the high-pressure diesel interface and waits for the boost control spool valve assembly 004 to open at the high-pressure diesel inlet of the control valve.

[0064] When the electromagnet assembly 002 of the booster control spool valve 004 is not energized, the main valve core 017 of the control spool valve is in the initial position. At this time, the high-pressure diesel inlet of the control valve is disconnected from the control oil circuit of the control valve, and the control oil circuit of the control valve is connected to the horizontal through hole. At this time, the diesel control chamber is connected through the high-pressure diesel oil passage → control oil circuit of the control valve → oblique hole → diesel return port. The low-pressure fuel is maintained at the low-pressure supply pressure, and the independent internal and external needle-type low-carbon fuel injectors do not operate.

[0065] When the electromagnet assembly 002 of the booster control spool valve 004 is energized, the armature 013 of the solenoid valve drives the pilot valve stem 014 of the spool valve, thereby overcoming the preload force of the spool valve spring 019 and pulling the main valve core 017 of the control spool valve to the second position. At this time, the high-pressure diesel inlet of the control valve is directly connected to the control oil passage of the control valve, while the control oil passage of the control valve is disconnected from the low-pressure diesel return port. At this time, the high-pressure diesel from the high-pressure diesel inlet of the control valve enters the diesel drive control chamber through the control oil passage → high-pressure diesel oil passage of the control valve. The high pressure pushes the booster piston 006 downward, and the low-carbon fuel in the low-carbon (new) fuel booster chamber is compressed, thereby increasing the pressure. This pressure then acts on the outlet valve core 024 through the channel in the middle of the suction valve core 021, thereby overcoming the preload force of the spring 025 and opening the outlet valve. High-pressure low-carbon fuel then reaches the independent internal and external needle-type low-carbon fuel injector through the high-pressure oil pipe. After passing through the low-carbon fuel double-wall pipe, the low-carbon fuel pressurized by the booster pump is delivered to the injector shown in Figure 4. After being pressurized in the injector shown in Figure 4, the new fuel inlet enters the injector and enters the low-carbon fuel reservoir in the double needle assembly 037 through the high-pressure new fuel channel, waiting for injection. When the pressure of the new fuel in the reservoir overcomes the spring preload of the needle valve spring 033, the needle valve is lifted, realizing the injection of low-carbon fuel.

[0066] When the required injection volume and injection timing are met, the control valve is de-energized, and the high-pressure diesel in the diesel booster drive chamber is connected to the diesel return port through the control valve. The low-carbon fuel pressure decreases, the injector needle valve and the booster pump outlet valve are closed, and the booster piston 006 is reset under the push of the low-carbon fuel.

[0067] 2) Diesel fuel injection function

[0068] In diesel injection mode, high-pressure diesel fuel enters the injector through the high-pressure diesel inlet in the injector assembly shown in Figure 4. Fuel injection is controlled by energizing the solenoid valve assembly 030. The specific working principle is as follows: After entering the injector through the high-pressure diesel inlet, diesel fuel enters the diesel fuel reservoir of the double needle assembly 037 through the high-pressure diesel fuel circuit, and enters the control chamber of the solenoid valve assembly 030 through the control valve inlet throttle orifice. When the solenoid is not energized, the control valve sleeve is pressed against the control valve stem by the spring force, and the control chamber is filled with high-pressure diesel fuel, maintaining a complete seal. At this time, the control chamber is full of high-pressure diesel fuel, the needle valve is not raised, and diesel fuel is not injected. When the solenoid is energized, the control valve is raised, and the high-pressure diesel fuel in the control chamber flows out through the control valve outlet throttle orifice. Therefore, the pressure in the control chamber decreases, and the high-pressure diesel fuel acts on the hydraulic pressure on the inner needle valve stem, overcoming the spring preload of the inner needle valve, causing the inner needle valve to open, and diesel fuel is injected through the diesel injection orifice in the inner ring.

[0069] 3) The sealing and lubrication function of diesel fuel for the turbocharged piston plunger assembly.

[0070] During the boosting process, due to the area ratio of the boosting piston 006, the pressure in the diesel boosting drive chamber 14 is greater than the pressure after boosting with low-carbon fuel. Therefore, during boosting, high-pressure diesel fuel leaks into the low-carbon fuel boosting chamber through the boosting plunger gap, preventing the risk of high-pressure low-carbon fuel leakage to the outside and simultaneously lubricating the movement of the boosting piston. During the boosting piston reset process, low-pressure low-carbon fuel pushes the boosting piston to reset, and low-pressure sealing oil seals and lubricates the piston gap through the sealing oil check valve 010. At this time, although the low-carbon fuel pressure is greater than the pressure in the diesel drive chamber, low-carbon fuel will not leak. There is always a diesel or sealing oil film in the boosting plunger gap, ensuring the lubrication of the piston assembly.

[0071] 4) Fuel mode switching function and purging function

[0072] When the system switches to diesel fuel mode, high-pressure nitrogen gas is introduced into the low-carbon / zero-carbon fuel inlet of the booster pump as shown in Figure 1 to purge the low-carbon fuel booster chamber, high-pressure oil pipe, and low-carbon fuel high-pressure oil passage inside the independent internal and external needle valve injector.

[0073] When the high-pressure low-carbon fuel outside the injector stops flowing in, high-pressure nitrogen gas is introduced into the high-pressure low-carbon fuel oil circuit through the injector purge valve 029, carrying away all the remaining low-pressure low-carbon fuel inside the injector. This inertizes the low-carbon fuel oil circuit and prevents the remaining low-carbon fuel inside the injector from vaporizing under the high temperature of the engine, thus preventing leakage.

[0074] 5) Discharge and purging functions in fault mode

[0075] The vent valve is located on top of the injector and adopts a control strategy of being normally open when power is off. The vent valve is driven by the main engine starting air. The purge valve is located opposite the methanol channel inlet. When the top vent valve is opened and the methanol pressure in the methanol channel is released to below 5 bar, N2 enters the adjacent methanol channel through the purge valve, circulates from the methanol reservoir to the far methanol channel, and is finally discharged from the top vent valve. This allows for a simple, convenient, efficient and reliable switch from methanol to diesel mode.

[0076] Example 1, when the booster pump is working:

[0077] (1) When electromagnet 002 is energized, the main valve core 017 of the slide valve moves to the right, and high-pressure diesel enters the drive chamber through passage P→A, pushing piston 006 to press down low-carbon fuel.

[0078] (2) The suction valve 021 opens under hydraulic pressure, and the equal-capacity discharge valve 024 opens at a pressure of 150 bar.

[0079] (3) When the pressure is released, the piston 006 is reset under the action of the disc spring 011, and the sealing oil check valve 010 injects lubricant.

[0080] Results: Pressure build-up efficiency increased by 30%, and plunger life extended to 8000 hours.

[0081] Example 2, Fault Discharge Process:

[0082] (1) The relief valve 027 is de-energized and opened, and the starting air pushes the piston 038 to move down, opening the inner valve core 040;

[0083] (2) After the low-carbon fuel pressure drops to 5 bar, nitrogen is injected from the purge valve 029 and flushed in reverse through the outer layer of the double-walled pipe;

[0084] (3) The residual liquid is discharged from the drain valve to the recovery device.

[0085] Results: Pipeline inerting is completed within 3 minutes, and safety meets IMO Tier III requirements.

[0086] Example 3, Diesel Injection Control:

[0087] (1) When the solenoid valve assembly 030 is energized, the oil pressure in the control chamber is released through the throttling orifice;

[0088] (2) The inner needle valve rises under diesel pressure, and the nozzle diameter (0.12mm) achieves micro-injection (2ml / cycle);

[0089] (3) When the power is turned on for the second time, the main nozzle (0.25mm) opens and the flow rate reaches 20ml / cycle.

[0090] Effect: The flow rate adjustment ratio reaches 10:1, covering all operating conditions from ignition to main injection.

[0091] The core innovation of this invention lies in:

[0092] 1. Integrated booster pump: The suction valve assembly 021, the discharge valve 024 and the booster slide valve 004 are integrated into a single pump body 005, reducing the volume by 40%;

[0093] 2. Multi-functional diesel fuel system: Diesel fuel serves as the driving force, sealant, and coolant simultaneously, eliminating the need for a separate servo system;

[0094] 3. Independent control of dual needle valves: Mechanical decoupling of inner and outer needle valves enables precise timing control of diesel ignition and low-carbon main injection.

[0095] The technical effects of this invention are as follows:

[0096] 1. Pressure build-up time for low-carbon fuels is reduced to 15ms;

[0097] 2. System leakage rate < 0.1% (traditional systems > 1%);

[0098] 3. Mode switching can be completed within one work cycle.

[0099] This is merely one embodiment of the present invention and does not cover all aspects of protection. Simple modifications made based on the core structure of the present invention, such as hydraulically driven pistons that achieve the same function, are all within the scope of protection of the present invention.

Claims

1. A low-carbon fuel booster pump and a flexible fuel injection system, characterized in that, include: Low-carbon fuel booster pump, fuel injector The low-carbon fuel booster pump is connected to the fuel injector and has a built-in suction valve module and an equal-capacity outlet valve structure. It is used for high-pressure build-up of low-carbon fuel and to achieve independent control of high-pressure injection of low-carbon fuel and diesel. The diesel fuel circuit reuse module is used to drive the booster piston, lubricate the moving parts, and seal the low-carbon fuel. The fuel injector is an independent inner and outer needle valve type injector, which includes an inner needle valve and an outer needle valve to control the independent injection of diesel and low-carbon fuel respectively; it adopts a venting valve assembly and a purging valve assembly to realize fuel venting and inert gas purging in fault mode.

2. The low-carbon fuel booster pump and flexible fuel injection system according to claim 1, characterized in that, The low-carbon fuel booster pump includes: an electromagnet, a booster control slide valve assembly, a booster piston, and a main control valve assembly. The booster control slide valve assembly is installed on the booster pump cover at the upper end of the booster pump housing, and switches the diesel drive oil circuit by driving the slide valve main valve core through the electromagnet. The booster piston is installed below the booster control slide valve assembly and is pushed by high-pressure diesel to compress the low-carbon fuel chamber. The main control valve assembly is installed between the booster piston and the outer flange outlet, and consists of a suction valve and an equal-capacity discharge valve. The suction valve spring and the discharge valve spring cooperate to achieve rapid pressure build-up.

3. The low-carbon fuel booster pump and flexible fuel injection system according to claim 2, characterized in that, The booster control spool valve assembly includes: an armature, a spool valve pilot rod, and a spool valve main valve core. The spool valve main valve core is housed within the control spool valve body. The upper end of the spool valve pilot rod passes sequentially through the spool valve main valve core, the spool valve spring, the armature adjusting shim, and the armature seat, and is then fixedly connected by an adjusting shim. The upper side of the control spool valve body has a control oil passage, and the lower side has a control diesel inlet. The bottom of the spool valve main valve core has an oblique hole, and the upper side has a horizontal through hole. The spool valve pilot rod and armature are linked, with a response time ≤2ms. The bottom of the control spool valve body has a spool valve bottom stop to limit the valve core stroke and prevent overshoot.

4. The low-carbon fuel booster pump and flexible fuel injection system according to claim 2, characterized in that, The main control valve assembly includes a suction valve core, a suction valve spring, a double-core valve housing, an outlet valve core, and an outlet valve spring. The upper part of the double-core valve housing is provided with a suction valve core with a suction valve spring, and the lower part is provided with an outlet valve core with an outlet valve spring, forming an equal-capacity outlet valve.

5. The low-carbon fuel booster pump and flexible fuel injection system according to claim 1, characterized in that, The equal-volume delivery valve maintains a pipeline pressure of 80–150 bar in the non-injection zone, and its spring preload is adjustable to adapt to different fuel characteristics.

6. The low-carbon fuel booster pump and flexible fuel injection system according to claim 1, characterized in that, The fuel injector includes a vent valve housing, a solenoid valve assembly, an injector body, a control valve stem, a needle valve spring, a limit rod, a spring guide sleeve, and a double needle assembly. The vent valve assembly and vent valve housing are mounted on the top of the injector body via a top cap; the side of the top cap has a vent hole connecting to the vent valve assembly; the solenoid valve assembly, control valve stem, and needle valve spring are sequentially installed from top to bottom inside the injector body; the spring guide sleeve and the double needle assembly are mounted on the bottom of the injector body via a connecting nut, and the spring guide sleeve contains a limit rod and a needle valve spring; the double needle assembly contains a new fuel reservoir and a diesel fuel reservoir, and its side contains a high-pressure low-carbon / zero-carbon fuel channel and a high-pressure diesel fuel channel; the injector body contains a high-pressure diesel common rail pipeline and a low-carbon fuel double-wall pipeline; a purge valve assembly is mounted on the injector body, located opposite the low-carbon / zero-carbon fuel inlet; the purge valve assembly is inertized by nitrogen gas after venting.

7. The low-carbon fuel booster pump and flexible fuel injection system according to claim 6, characterized in that, The needle valve spring in the dual-needle assembly controls the opening and closing of the injection orifice in the diesel fuel tank; the outer needle valve independently controls the low-carbon fuel injection orifice through the coordinated action of the low-carbon fuel pressure and the spring; the solenoid valve assembly has an oil outlet throttling orifice, which reduces the pressure in the control chamber to achieve diesel injection when energized.

8. The low-carbon fuel booster pump and flexible fuel injection system according to claim 6, characterized in that, The relief valve assembly includes: a relief valve drive piston, a relief valve outer valve core, and a relief valve inner valve core. The relief valve outer valve core contains the relief valve inner valve core, and the upper end is equipped with the relief valve drive piston. The relief valve drive piston, which is normally open when the power is off, is driven by air starting from the main unit. The relief valve inner valve core and the relief valve outer valve core achieve double sealing.

9. The low-carbon fuel booster pump and flexible fuel injection system according to claim 1, characterized in that, The diesel fuel circuit reuse module injects low-pressure sealing oil through a one-way valve when the booster piston resets, maintaining the integrity of the oil film on the plunger assembly.

10. The low-carbon fuel booster pump and flexible fuel injection system according to claim 1, characterized in that, The system supports automatic fuel mode switching, including switching and purging between diesel injection mode and low carbon injection mode, and venting and purging in fault mode. In diesel injection mode, nitrogen gas is used to backwash the low-carbon fuel pipeline via the purge valve; In low-carbon injection mode, diesel fuel continuously circulates to cool the injectors and lubricate the moving parts.

Images