Fuel Injection Device and Control Method

Abstract

This invention belongs to the field of valve technology and discloses a fuel injection device and control method. The fuel injection device and control method include a housing, an end cover, a valve seat, a piston, a valve core, a needle valve assembly, and a limiting mechanism. The fuel injection device can inject alternative fuels or diesel fuel. First, the fuel supply in the current operating mode is cut off and inerted. After the previous injection cycle is completed, the fuel supply is shut off, and inert gas nitrogen is introduced and mixed with the fuel to gradually reduce the fuel concentration in the fuel injection device to below the explosion limit, thereby achieving fuel inerting. Under the action of the drive component, the limiting rod is pushed down, thereby pushing the piston down, reducing the volume of the fuel chamber, thereby reducing the volume that needs to be inerted, accelerating the inerting process, and basically removing the residual fuel in the pipeline. Second, under the action of the drive component, the limiting rod is raised to a designated position, and the piston stroke is adjusted to a value corresponding to the injection quantity.

Description

Technical Field

[0001] This invention relates to the field of valve technology, and more particularly to fuel injection devices and control methods. Background Technology

[0002] With increasingly stringent emission standards for marine engines, low-carbon fuel methanol and zero-carbon fuel ammonia, as clean energy sources, can effectively reduce emissions from marine engines. Their preparation technology is relatively mature, the refining process is clean and environmentally friendly, and the market prospects are broad.

[0003] Developing a diesel / alternative fuel dual-fuel injection system based on traditional diesel engine injection devices is an important approach to the green and environmentally friendly transformation of marine engines. Alternative fuels include, but are not limited to, methanol, ethanol, ammonia, natural gas, and dimethyl ether. However, due to space limitations in the engine cylinder head, it is not feasible to arrange one or more alternative fuel injectors next to the traditional diesel injection system. Therefore, a single injection device can be used to switch between diesel and alternative fuel injection. However, during fuel mode switching, diesel and alternative fuels mix, making it impossible to accurately determine the mixing ratio. The fuel composition injected during switching is complex, and the fuel composition injected in each cycle is uneven and inconsistent, making it difficult to predict the in-cylinder combustion conditions and resulting in poor stability during switching, thus leading to difficulties in engine speed regulation.

[0004] Therefore, there is an urgent need for fuel injection devices and control methods to solve the above problems. Summary of the Invention

[0005] According to one aspect of the present invention, a fuel injection device is provided that can inject alternative fuels or diesel fuel, and the fuel switching process is smooth, reliable and safe.

[0006] To address the aforementioned problems in the existing technology, the present invention adopts the following technical solution:

[0007] Fuel injection device, including:

[0008] The housing is provided with a first oil passage and a second oil passage, and the housing has a receiving cavity;

[0009] An end cap is provided at the upper opening of the housing. The end cap is provided with a fuel inlet and a servo oil inlet. The fuel inlet is connected to the first oil passage.

[0010] A valve seat is disposed within the receiving cavity, the valve seat having a valve chamber that is connected to the second oil circuit;

[0011] A piston is disposed within the receiving cavity, the piston is sleeved on the valve seat and can slide along a first direction, the piston divides the receiving cavity into a drive cavity and a fuel cavity, the fuel cavity is connected to the valve cavity, and the drive cavity is connected to the servo oil inlet;

[0012] A valve core is located inside the valve cavity. The valve core has an oil inlet and an oil outlet. The oil inlet is connected to the first oil passage, and the oil outlet is connected to the fuel chamber.

[0013] A needle valve assembly is disposed in the lower part of the housing, and the needle valve assembly has a pressure chamber that is connected to the second oil passage;

[0014] The limiting mechanism includes a driving component and a limiting rod. The limiting rod is slidably disposed inside the end cover. The two ends of the limiting rod abut against the driving component and the piston, respectively. The driving component is disposed on the end cover and is used to drive the limiting rod to move so that the piston slides relative to the housing.

[0015] Preferably, the valve core includes a sliding portion and a cutting portion, and a throttling orifice is formed between the cutting portion and the valve seat. The sliding portion is capable of sliding along the first direction so that the cutting portion contacts or separates from the valve seat. When the cutting portion contacts the valve seat, the fuel chamber is connected to the first oil passage through the throttling orifice and to the second oil passage through the throttling orifice. When the cutting portion separates from the valve seat, the oil inlet is disconnected from the second oil passage, and the second oil passage is connected to the fuel chamber.

[0016] Preferably, the fuel injection device further includes a transfer valve, which is disposed at the fuel inlet of the end cap. The transfer valve is used to open and close the fuel inlet, and the fuel inlet is selectively connected to alternative fuel, diesel fuel, and inert gas through the transfer valve.

[0017] Preferably, the driving assembly includes a motor and an eccentric disk, the eccentric disk being rotatably disposed on the end cover and abutting against the limiting rod, the motor being disposed on the end cover and used to drive the eccentric disk to rotate relative to the end cover, so that the limiting rod moves along the first direction.

[0018] Preferably, the fuel injection device further includes a first elastic element, which is sleeved on the limiting rod. The outer peripheral wall of the limiting rod is provided with a protrusion. The two ends of the first elastic element abut against the end cap and the protrusion, respectively. The first elastic element is always in a tightened state.

[0019] Preferably, the needle valve assembly includes a second elastic element, a needle valve, and a valve body. The valve body is connected to the housing via a locking nut. One end of the needle valve is slidably disposed on the valve body, and the other end of the needle valve is slidably disposed on the housing. The second elastic element is sleeved on the needle valve, and one end of the second elastic element is connected to the needle valve, while the other end of the second elastic element abuts against the housing. The needle valve is capable of blocking the nozzle under the action of the second elastic element.

[0020] Preferably, the valve seat is provided with an oil return channel, which is connected to the oil tank, and an oil film is provided between the valve seat and the piston, which flows to the oil tank through the oil return channel.

[0021] According to another aspect of the present invention, a fuel injection device control method is provided, wherein, through the implementation of the above-described fuel injection device, the fuel injection device control method includes:

[0022] S100: The supply of diesel and alternative fuel is shut off, inert gas is introduced into the fuel inlet and mixed with the fuel in the housing to inertize the fuel in the housing, and the piston is pushed down by the limiting mechanism to accelerate the inertization of the fuel;

[0023] S200: Under the action of the drive assembly, the limit rod rises to the designated position, driving the piston's stroke to adjust to the value corresponding to the fuel injection quantity;

[0024] S300: The supply of diesel or alternative fuel is turned on, flowing sequentially through the drive chamber, the fuel chamber, the valve chamber and the second oil circuit, and the fuel injection device operates in the target mode.

[0025] Preferably, S300 in the fuel injection device control method specifically includes:

[0026] S301: Diesel fuel or alternative fuel passes sequentially through the fuel inlet, the first oil passage, the oil inlet hole, the oil outlet hole, the valve core, and the fuel chamber, pushing the piston to rise in the first direction until the piston abuts against the limiting rod, thus completing the intake of diesel fuel or alternative fuel;

[0027] S302: Servo oil enters the drive chamber through the servo oil inlet, and the piston moves downward along the first direction to increase the fuel pressure in the fuel chamber. At the same time, diesel fuel and alternative fuel are injected through the needle valve assembly.

[0028] Preferably, the fuel injection device further includes a transfer valve, which is disposed at the fuel inlet of the end cover. The transfer valve is used to open and close the fuel inlet. The fuel inlet is selectively connected to alternative fuel, diesel fuel, and inert gas through the transfer valve. The drive assembly includes a motor and an eccentric disk. The eccentric disk is rotatably disposed on the end cover and abuts against the limiting rod. The motor is disposed on the end cover and is used to drive the eccentric disk to rotate relative to the end cover, so that the limiting rod moves along the first direction.

[0029] S100 in the fuel injection device control method specifically includes:

[0030] S101: The supply of diesel and alternative fuel is shut off by the transfer valve and the inert gas is opened. The inert gas flows sequentially through the fuel inlet, the first oil passage, the oil inlet hole, the oil outlet hole, the valve core and the fuel chamber, and mixes with the fuel in the housing to inertize the fuel in the housing.

[0031] S102: Adjust the rotation angle of the motor, and push the limiting rod downward along the first direction through the eccentric disk, thereby pushing the piston downward, so as to reduce the volume of the fuel chamber and accelerate the inerting of the fuel in the housing.

[0032] The beneficial effects of this invention are as follows:

[0033] The fuel injection device provided by this invention allows fuel to flow sequentially through a fuel inlet, a first oil passage, an inlet hole, and an outlet hole, ultimately entering the fuel chamber. The oil pressure within the fuel chamber gradually increases, pushing the piston upwards until its upper surface abuts against the end cap, completing fuel intake. Upon receiving a control signal, the servo oil solenoid valve switches to the inlet state, allowing servo oil to enter the drive chamber through the servo oil inlet. The piston, subjected to a downward resultant force, moves downwards, reducing the volume of the fuel chamber and thus increasing the fuel pressure, achieving pressurization. Simultaneously, the fuel chamber connects to the second oil passage, thereby connecting to the pressure chamber. The fuel pressure in the pressure chamber acts on the conical pressure-bearing surface of the needle valve assembly, and the upward resultant force causes the needle valve assembly to lift, ejecting fuel from the nozzle, achieving fuel injection. After the piston moves downwards to its lowest position, fuel injection ends, the servo oil switches to a depressurization state, the second oil passage connects to the zero-pressure oil tank, and the servo oil pressure is reset to zero. Under the pressure of the fuel inlet, the piston moves upward, initiating the next fuel intake cycle, repeating this process. This allows for either single injection of diesel fuel or a single injection of alternative fuel. Switching from the current operating mode to the target mode requires low-load conditions. First, the fuel supply to the current operating mode is cut off and inerted. After the previous injection cycle, the fuel supply is shut off, and inert nitrogen gas is introduced and mixed with the fuel to gradually reduce the fuel concentration in the fuel injection device to below the explosion limit, achieving fuel inerting. Under the action of the drive assembly, the limit rod moves downward, thereby pushing the piston downward, reducing the volume of the fuel chamber, thus reducing the volume requiring inerting, accelerating the inerting process, and essentially removing residual fuel from the pipeline. Next, under the action of the drive assembly, the limit rod rises to the designated position, and the piston stroke is adjusted to the value corresponding to the injection quantity. Finally, the fuel supply to the target mode is opened, and fuel fills the valve chamber. The fuel switching process is smooth, reliable, and safe.

[0034] The fuel injection device control method provided by this invention, through the implementation of the fuel injection device, shuts off the supply of diesel and alternative fuels, introduces inert gas and mixes it with the fuel in the housing, thereby achieving and accelerating fuel inerting, essentially removing residual fuel in the pipeline, having minimal impact on combustion uniformity, and allowing for speed adjustment according to fuel demand in the target mode. The speed adjustment process is stable, highly controllable, and safer. The limit lever rises to the designated position under the action of the drive assembly, adjusting the stroke of the drive piston to the value corresponding to the fuel injection quantity, opening the supply of diesel and alternative fuels, and enabling the fuel injection device to operate in the target mode, adapting to different fuel injection quantity requirements. The fuel switching process is smooth, reliable, and safe. Attached Figure Description

[0035] Figure 1 This is a schematic diagram of the fuel injection device in an embodiment of the present invention. Figure 1 ;

[0036] Figure 2This is a schematic diagram of the fuel injection device in an embodiment of the present invention. Figure 2 ;

[0037] Figure 3 This is a schematic diagram of the fuel injection device in an embodiment of the present invention. Figure 3 ;

[0038] Figure 4 This is a schematic diagram of the valve core structure in an embodiment of the present invention;

[0039] Figure 5 This is a flowchart of the fuel injection device control method in an embodiment of the present invention.

[0040] Figure label:

[0041] 1. Housing; 11. First oil passage; 12. Second oil passage; 13. Drive chamber; 14. Fuel chamber;

[0042] 2. End cap; 21. Fuel inlet; 22. Servo oil inlet;

[0043] 3. Valve seat; 31. Oil return passage; 32. Valve chamber; 33. Throttling port;

[0044] 4. Piston;

[0045] 5. Valve core; 51. Oil inlet; 52. Oil outlet; 53. Sliding part; 54. Cutting part;

[0046] 6. Needle valve assembly; 61. Second elastic element; 62. Needle valve; 63. Valve body;

[0047] 7. Limiting mechanism; 71. Drive assembly; 711. Motor; 712. Eccentric disc; 72. Limiting rod;

[0048] 8. Adapter valve;

[0049] 9. First elastic element;

[0050] 10. Nozzle. Detailed Implementation

[0051] The present invention will now be described in further detail with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and not intended to limit it. Furthermore, it should be noted that, for ease of description, the accompanying drawings show only the parts relevant to the present invention, and not all of the structures.

[0052] In the description of this invention, unless otherwise explicitly specified and limited, the terms "connected," "linked," and "fixed" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0053] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can include direct contact between the first and second features, or contact between the first and second features through another feature between them. Furthermore, "above," "over," and "on top" of the second feature includes the first feature directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature includes the first feature directly below or diagonally below the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.

[0054] In the description of this embodiment, the terms "upper," "lower," "left," and "right," etc., refer to the orientation or positional relationship shown in the accompanying drawings. They are used only for ease of description and simplification of operation, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the present invention. In addition, the terms "first" and "second" are used only for distinction in description and have no special meaning.

[0055] Existing diesel / alternative fuel dual-fuel injection systems are an important pathway for the green and environmentally friendly transformation of marine engines. Alternative fuels include, but are not limited to, methanol, ethanol, ammonia, natural gas, and dimethyl ether. However, due to space constraints in the engine cylinder head, it is not feasible to arrange one or more alternative fuel injectors next to a traditional diesel injection system. Therefore, a single injection system can be used to switch between diesel and alternative fuel injection. However, during fuel mode switching, if only the fuel type is changed without special measures, the residual fuel from the previous mode in the pipeline will mix with the target mode fuel. Alternative fuels such as low-carbon methanol and zero-carbon fuels such as ammonia are immiscible with diesel. During switching, the two fuels mix unevenly in the pipeline, and this unevenness worsens with the complexity of the pipeline structure. Therefore, during switching, the proportions of diesel and alternative fuel in the actual injected fuel mixture vary between different cylinders. There may be residual fuel after the first injection after switching, which will continue to mix with the target fuel in the next injection cycle. Thus, the component proportions in different cycles within the same cylinder also change continuously during switching. Therefore, such a switching process can be considered extremely unstable and uncontrollable. This poses a severe challenge to engine speed regulation, and it's even possible that speed regulation may be impossible during this period, posing a safety risk. To address this, this embodiment provides a fuel injection device that can inject both alternative fuels and diesel fuel, ensuring a smooth, reliable, and safe fuel switching process.

[0056] like Figures 1-4As shown, in this embodiment, the fuel injection device includes a housing 1, an end cap 2, a valve seat 3, a piston 4, a valve core 5, a needle valve assembly 6, and a limiting mechanism 7. The housing 1 has a first oil passage 11 and a second oil passage 12, and a receiving cavity. The end cap 2 is located at the upper opening of the housing 1 and has a fuel inlet 21 connected to the first oil passage 11. The valve seat 3 is located within the receiving cavity and has a valve chamber 32 connected to the second oil passage 12. The piston 4 is located within the receiving cavity, fitted onto the valve seat 3, and capable of sliding along a first direction. The piston 4 divides the receiving cavity into a drive chamber 13 and a fuel chamber 14. The fuel chamber 14 is connected to the valve chamber 32 and the servo oil inlet 22, and the drive chamber 13 is connected to the servo oil inlet 22. The valve core 5 is located inside the valve chamber 32. The valve core 5 has an oil inlet 51 and an oil outlet 52. The oil inlet 51 is connected to the first oil passage 11, and the oil outlet 52 is connected to the fuel chamber 14. The needle valve assembly 6 is located at the lower part of the housing 1. The needle valve assembly 6 has a pressure chamber connected to the second oil passage 12. The limiting mechanism 7 includes a drive assembly 71 and a limiting rod 72. The limiting rod 72 is slidably disposed inside the end cover 2. The two ends of the limiting rod 72 abut against the drive assembly 71 and the piston 4, respectively. The drive assembly 71 is disposed on the end cover 2 and is used to drive the limiting rod 72 to move so that the piston 4 slides relative to the housing 1. Specifically, the fuel injection device can inject either alternative fuel or diesel fuel, with the first direction being the AB direction. Fuel flows sequentially through fuel inlet 21, first oil passage 11, inlet hole 51, and outlet hole 52, finally entering fuel chamber 14. The oil pressure in fuel chamber 14 gradually increases, pushing piston 4 upwards until the upper surface of piston 4 abuts against end cap 2, completing fuel intake. Upon receiving a control signal from the host machine, the servo oil solenoid valve switches to the inlet state, and servo oil enters drive chamber 13 along servo oil inlet 22. Piston 4 is subjected to a downward resultant force and moves downwards, reducing the volume of fuel chamber 14 and thus increasing the fuel pressure in fuel chamber 14, achieving pressurization. Fuel chamber 14 is not directly connected to inlet 22, but rather through a very thin gap between parts, yet the throttling effect is significant. Simultaneously, fuel chamber 14 is connected to second oil passage 12, thereby connecting to pressure chamber. The fuel pressure in pressure chamber acts on the conical pressure-bearing surface of needle valve assembly 6, and the upward resultant force causes needle valve assembly 6 to lift, allowing fuel to be ejected from nozzle 10, achieving fuel injection. After piston 4 moves downward to its lowest position, fuel injection ends, the servo oil switches to depressurization mode, the second oil circuit 12 connects to the zero-pressure oil tank, and the servo oil pressure is reset to zero. Under the action of fuel inlet pressure, piston 4 moves upward to begin the next fuel intake cycle, repeating the cycle. It can inject diesel fuel alone or alternative fuel alone.The switch from the current operating mode to the target mode needs to be performed under low-load conditions. First, the fuel supply to the current operating mode is cut off and inerted. After the previous injection cycle is completed, the fuel supply is shut off, and inert nitrogen gas is introduced and mixed with the fuel to gradually reduce the fuel concentration in the fuel injection device to below the explosion limit, thus achieving fuel inerting. Under the action of the drive assembly 71, the limit rod 72 is pushed down, thereby pushing the piston 4 down, reducing the volume of the fuel chamber 14, thereby reducing the volume that needs to be inerted, accelerating the inerting process, and basically removing residual fuel from the pipeline. Second, under the action of the drive assembly 71, the limit rod 72 is raised to the designated position, and the stroke of the piston 4 is adjusted to the value corresponding to the injection volume. Finally, the fuel supply to the target mode is opened, and fuel fills the valve chamber 32. The fuel switching process is smooth, reliable, and safe.

[0057] Preferably, alternative fuels such as low-carbon methanol and zero-carbon ammonia are ignited by a small amount of diesel fuel. Therefore, the engine is equipped with a pilot fuel injector with a smaller injection volume. Power during low-load switching can be provided by the pilot fuel injector, and the switchable load range depends on the load range that the pilot fuel injector can cover. Preferably, the inerting line outlet can be connected to an external fuel concentration detector. If the fuel concentration remains below a set value, the detector stops alarming, the nitrogen supply is cut off, and inerting ends.

[0058] Furthermore, continue to refer to Figures 1-4The valve core 5 includes a sliding part 53 and a cutting part 54. A throttling orifice 33 is formed between the cutting part 54 and the valve seat 3. The sliding part 53 can slide along a first direction so that the cutting part 54 contacts or separates from the valve seat 3. When the cutting part 54 contacts the valve seat 3, the fuel chamber 14 is connected to the first oil passage 11 through the throttling orifice 33 and to the second oil passage 12 through the throttling orifice 33. When the cutting part 54 separates from the valve seat 3, the oil inlet 51 is disconnected from the second oil passage 12, and the second oil passage 12 is connected to the fuel chamber 14. Specifically, the valve core 5 is formed by cutting two bevels into a cylinder. During fuel intake, the valve core 5 is subjected to the fuel inlet pressure, resulting in an upward force. The valve core 5 moves upward and contacts the valve seat 3. When the valve core 5 reaches its highest position, the oil outlet 52 of the valve core 5 is connected to the first oil passage 11. The fuel chamber 14 is connected to the first oil passage 11 through the throttle port 33, and also to the second oil passage 12 through the throttle port 33. Fuel can be pre-filled slowly into the second oil passage 12, creating a certain oil pressure in the second oil passage 12, which can reach the opening pressure more quickly and improve the action response. During the boost injection process, the valve core 5 is subjected to the servo oil drive pressure, resulting in a downward force. The valve core 5 moves downward, the oil outlet 52 disconnects from the first oil passage 11, and the fuel chamber 14 connects to the second oil passage 12. Due to the widening of the gap between the cut part 54 and the valve seat 3, the throttling effect is no longer formed, reducing pressure loss. The pressure in the second oil passage 12 can rise quickly and will not flow back from the fuel inlet 21. By switching the pressure difference between the upper and lower surfaces of valve core 5, the direction of the resultant force is changed, thereby switching the position of valve core 5 and thus opening or closing the oil circuit.

[0059] Furthermore, continue to refer to Figures 1-4 The fuel injection device also includes a transfer valve 8, which is located at the fuel inlet 21 of the end cover 2. The transfer valve 8 is used to open and close the fuel inlet 21, which is selectively connected to alternative fuel, diesel fuel, or inert gas via the transfer valve 8. Specifically, the alternative fuel inlet, diesel fuel inlet, and inert gas inlet are all connected to the transfer valve 8. The transfer valve 8 is used to control the connection and disconnection of the above inlets, that is, the fuel switching is achieved by the transfer valve 8. After the previous injection cycle is completed, the transfer valve 8 closes the supply of diesel fuel and alternative fuel and opens the inert gas inlet to connect the inert gas with the fuel inlet 21. Preferably, this fuel injection device is suitable for low-speed engines with low engine speeds and long injection cycle intervals, injecting within a short injection duration. The time outside the injection duration of this cycle can be used for inerting. Furthermore, it only requires inerting the area between the sealing surfaces from the transfer valve 8 to the needle valve assembly 6, and the motor 711 pushes the piston 4 to the lowest position. The total volume to be inerted is small, and the inerting time is relatively ample, thus achieving a good inerting effect.

[0060] Furthermore, continue to refer to Figures 1-4 The drive assembly 71 includes a motor 711 and an eccentric disk 712. The eccentric disk 712 is rotatably mounted on the end cover 2 and abuts against the limiting rod 72. The motor 711 is mounted on the end cover 2 and drives the eccentric disk 712 to rotate relative to the end cover 2, so that the limiting rod 72 moves along a first direction. Specifically, the adjustment of the injection volume is mainly achieved by the limiting rod 72 restricting the stroke of the piston 4. The input shaft of the eccentric disk 712 is connected to the motor 711 and can be driven to rotate by the latter. However, the disk axis of the eccentric disk 712 does not coincide with the axis of the input shaft, hence the term eccentric. When the input shaft rotates, the distance between the contact point and the axis of the input shaft of the eccentric disk 712 changes continuously. If the motor 711 can stably stop at a certain angle, the limiting rod 72 can remain at the position corresponding to that angle. If the rotation angle of the motor 711 is continuous and arbitrary, the position held by the limiting rod 72 is continuous and arbitrary. In summary, when piston 4 moves to the point where its upper end face contacts the lower end face of limit rod 72, it stops moving upwards. The upward stroke of piston 4 affects the volume of fuel chamber 14, thus affecting the amount of fuel drawn in, and consequently affecting the amount of fuel injected after pressurization. Using motor 711 to adjust the injection amount has the following advantages compared to adjustment methods such as hydraulic servo transmission: 1) Simple structure: The mechanical structure only needs to be connected to motor 711, while hydraulic servo transmission requires a separate matching hydraulic oil system and its control components; 2) Faster response: Hydraulic servo transmission adjusts different limits by establishing different oil pressures, and the pressure building process takes a certain amount of time, making it difficult to ensure that the adjustment is completed within one engine cycle, while motor 711 acts quickly and can quickly adjust the limit block to the designated position; 3) Accurate position and stable holding: When the upper end face of piston 4 hits the lower end face of limit rod 72, the movement stops, completing one fuel intake process. Such an impact occurs during the fuel intake process of each injection cycle. If hydraulic servo transmission or other methods are used to adjust the limit, the servo oil pressure will fluctuate during the impact, resulting in inaccurate fuel intake.

[0061] Preferably, the motor 711 rotation angle corresponding to different fuels and different injection quantities can be obtained through calculation and matching. The appropriate length of the limiting rod 72 and the appropriate stiffness of the first elastic element 9 are then matched according to the injection requirements. If the shape of the eccentric disk 712 is adjusted, the correspondence between the displacement of the limiting rod 72 and the rotation angle of the motor 711 changes accordingly. The shape design of the eccentric disk 712 can be optimized based on the actual fuel injection quantity and speed requirements. In actual use of the injection device, only the rotation angle of the motor 711 needs to be adjusted to regulate the fuel injection quantity.

[0062] Furthermore, continue to refer to Figures 1-4The fuel injection device also includes a first elastic element 9, which is sleeved on the limiting rod 72. The outer peripheral wall of the limiting rod 72 is provided with a protrusion. The two ends of the first elastic element 9 abut against the end cap 2 and the protrusion, respectively, and the first elastic element 9 is always in a tightened state. Specifically, the first elastic element 9 is a compression spring. Under the action of the elastic force of the first elastic element 9, the outer edge of the eccentric disk 712 contacts the top end of the limiting rod 72.

[0063] Furthermore, continue to refer to Figures 1-4 The needle valve assembly 6 includes a second elastic element 61, a needle valve 62, and a valve body 63. The valve body 63 is connected to the housing 1 via a locking nut. One end of the needle valve 62 is slidably disposed on the valve body 63, and the other end of the needle valve 62 is slidably disposed on the housing 1. The second elastic element 61 is sleeved on the needle valve 62, with one end connected to the needle valve 62 and the other end abutting against the housing 1. The needle valve 62 can block the nozzle 10 under the action of the second elastic element 61. Specifically, during the fuel pressurization injection process, the fuel pressure acts on the conical pressure-bearing surface of the needle valve 62, and the resultant force on the needle valve 62 is upward. When this resultant force is sufficient to overcome the downward pressure of the second elastic element 61, the needle valve 62 is lifted, and fuel is ejected from the nozzle 10, thus realizing fuel injection.

[0064] Furthermore, continue to refer to Figures 1-4The valve seat 3 is equipped with an oil return channel 31, which is connected to the oil tank. An oil film is formed between the valve seat 3 and the piston 4, and the oil film flows to the oil tank through the oil return channel 31. Specifically, alternative fuels such as low-carbon fuel methanol and zero-carbon fuel ammonia have lower viscosity than diesel, making it difficult to establish an oil film and resulting in poor lubrication. The lubrication of the moving parts of the fuel injection device needs to be carefully considered to ensure the service life of the fuel injection device. Furthermore, they have a certain corrosive effect on some metals, accelerating wear. When the fuel injection device is used for the injection of natural gas fuel in an engine, the moving parts in the fuel injection device need to perform repeated actions as the engine runs. Wear will affect the accuracy of the action, thus affecting injection performance and shortening the service life of the injection device. The aforementioned diesel and alternative fuels are toxic and corrosive, with low flash points and a risk of explosion. Leakage protection measures for the fuel injection device need to be carefully considered to ensure the safety of life and property at the site. Therefore, establishing effective lubrication is crucial for extending the service life of the fuel injection device. Specifically, this includes the K surface between the piston 4 and the valve seat 3, the L surface between the valve seat 3 and the valve core 5, and the M surface between the needle valve 62 and the valve body 63. In this embodiment, lubrication is achieved by using lubricating oil with a pressure slightly higher than the fuel pressure. The lubricating oil enters the fuel injection device from the fuel inlet 21 and reaches the surfaces K, L, and M respectively. Through proper matching of the movement gaps, a relatively complete oil film can be effectively established, greatly improving the lubrication effect. The lubricating oil at L gradually leaks into the suction port along the gap between the valve seat 3 and the valve core 5, and mixes with methanol or ammonia before being injected into the cylinder. The lubricating oil at M gradually leaks into the spring cavity of the valve body 63 along the gap between the needle valve 62 and the valve body 63. The lubricating oil at K gradually leaks into the lubricating oil return channel 31 along the gap between the piston 4 and the valve seat 3, and flows into the oil tank. The lubricating oil provides a reliable sealing effect, effectively preventing alternative fuel from leaking from the gaps at K, L, and M, ensuring safety.

[0065] This embodiment also provides a fuel injection device control method, such as... Figure 4 As shown, through the implementation of the above-mentioned fuel injection device, the fuel injection device control method includes:

[0066] S100: The supply of diesel and alternative fuel is shut off, and inert gas is introduced into the fuel inlet 21 and mixed with the fuel in the housing 1 to inertize the fuel in the housing 1. The piston 4 is pushed down by the limiting mechanism 7 to accelerate the inertization of the fuel.

[0067] S100 in the fuel injection device control method specifically includes:

[0068] S101: The supply of diesel and alternative fuel is shut off by the transfer valve 8 and the inert gas is opened. The inert gas flows sequentially through the fuel inlet 21, the first oil passage 11, the oil inlet 51, the oil outlet 52, the valve core 5 and the fuel chamber 14, and mixes with the fuel in the housing 1 to inertize the fuel in the housing 1.

[0069] The alternative fuel inlet, diesel fuel inlet, and inert gas inlet are all connected to the transfer valve 8. The transfer valve 8 controls the connection and disconnection of these inlets; that is, fuel switching is achieved by the transfer valve 8. After the previous injection cycle is completed, the transfer valve 8 shuts off the supply of diesel fuel and alternative fuel, and opens the inert gas inlet to connect the inert gas with the fuel inlet 21. The introduced inert gas, nitrogen, mixes with the fuel to gradually reduce the fuel concentration in the fuel injection device to below the explosion limit, thus achieving fuel inerting.

[0070] S102: Adjust the rotation angle of the motor 711, and push the limit rod 72 downward along the first direction through the eccentric disk 712, thereby pushing the piston 4 downward, so as to reduce the volume of the fuel chamber 14 and accelerate the inerting of the fuel in the housing 1.

[0071] Adjusting the rotation angle of motor 711 causes eccentric disk 712 to push limit rod 72 downward, thereby pushing piston 4 downward and reducing the volume of fuel chamber 14, thus reducing the volume requiring inerting and accelerating the inerting process. The injection quantity is mainly adjusted by limiting the stroke of piston 4 by limit rod 72. When the input shaft rotates, the distance between this contact point and the input shaft axis of eccentric disk 712 changes continuously. If motor 711 can stably stop at a certain angle, limit rod 72 can remain at the position corresponding to that angle. If the rotation angle of motor 711 is continuous and arbitrary, the position held by limit rod 72 is continuous and arbitrary. In summary, piston 4 stops moving upward when its upper end face contacts the lower end face of limit rod 72. The upward stroke of piston 4 affects the volume of fuel chamber 14, thus affecting the fuel intake quantity, and consequently affecting the fuel injection quantity after pressurization.

[0072] S200: Under the action of the drive assembly 71, the limit rod 72 rises to the designated position, and the stroke of the drive piston 4 is adjusted to the value corresponding to the fuel injection quantity.

[0073] S300: The supply of diesel or alternative fuel is turned on, flowing sequentially through the drive chamber 13, fuel chamber 14, valve chamber 32 and second oil circuit 12, and the fuel injection device operates in the target mode.

[0074] S300 in the fuel injection device control method specifically includes:

[0075] S301: Diesel fuel or alternative fuel passes sequentially through fuel inlet 21, first oil passage 11, oil inlet 51, oil outlet 52, valve core 5 and fuel chamber 14, pushing piston 4 to rise in the first direction until piston 4 abuts against end cap 2, completing the intake of diesel fuel or alternative fuel.

[0076] S302: Servo oil enters the drive chamber 13 through the servo oil inlet 22, and the piston 4 moves downward in the first direction to increase the fuel pressure in the fuel chamber 14. At the same time, diesel and alternative fuel are injected through the needle valve assembly 6.

[0077] Upon receiving a control signal from the host machine, the servo oil solenoid valve switches to the oil inlet state, and servo oil enters the drive chamber 13 through the servo oil inlet 22. The piston 4 moves downward under the resultant downward force, reducing the volume of the fuel chamber 14 and thus increasing the fuel pressure in the fuel chamber 14, achieving pressurization. Simultaneously, the fuel chamber 14 connects to the second oil passage 12, thereby connecting to the pressure chamber. The fuel pressure in the pressure chamber acts on the conical pressure-bearing surface of the needle valve assembly 6, and the upward resultant force causes the needle valve assembly 6 to lift, allowing fuel to be ejected from the nozzle 10, achieving fuel injection. After the piston 4 moves downward to its lowest position, fuel injection ends, the servo oil switches to the depressurization state, the second oil passage 12 connects to the zero-pressure oil tank, and the servo oil pressure is reset to zero. Under the action of the fuel inlet pressure, the piston 4 moves upward, starting the next fuel intake cycle, repeating the cycle. This allows for either single injection of diesel fuel or single injection of alternative fuel.

[0078] The fuel injection device control method provided in this embodiment, through the implementation of the fuel injection device, shuts off the supply of diesel and alternative fuels, introduces inert gas and mixes it with the fuel in the housing 1, thereby achieving and accelerating the inerting of the fuel, essentially removing residual fuel in the pipeline, having minimal impact on combustion uniformity, and allowing for speed adjustment according to the fuel demand in the target mode. The speed adjustment process is stable, highly controllable, and safer. Under the action of the drive assembly 71, the limit rod 72 rises to the designated position, adjusting the stroke of the drive piston 4 to the value corresponding to the fuel injection quantity, opening the supply of diesel and alternative fuels, and the fuel injection device operates in the target mode, adapting to the different injection quantity requirements of different fuels. The fuel switching process is smooth, reliable, and safe.

[0079] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the implementation of the present invention. Those skilled in the art will be able to make various obvious changes, readjustments, and substitutions without departing from the scope of protection of the present invention. It is neither necessary nor possible to exhaustively describe all embodiments here. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the claims of the present invention.

Claims

1. A fuel injection device, characterized in that, include: The housing (1) is provided with a first oil passage (11) and a second oil passage (12), and the housing (1) has a receiving cavity; End cap (2) is provided at the upper opening of the housing (1). The end cap (2) is provided with a fuel inlet (21) and a servo oil inlet (22). The fuel inlet (21) is connected to the first oil passage (11). A valve seat (3) is disposed in the receiving cavity, the valve seat (3) having a valve cavity (32) connected to the second oil passage (12); A piston (4) is disposed in the receiving cavity. The piston (4) is sleeved on the valve seat (3) and can slide along the first direction. The piston (4) divides the receiving cavity into a drive cavity (13) and a fuel cavity (14). The fuel cavity (14) is connected to the valve cavity (32). The drive cavity (13) is connected to the servo oil inlet (22). The valve core (5) is located in the valve cavity (32). The valve core (5) has an oil inlet hole (51) and an oil outlet hole (52). The oil inlet hole (51) is connected to the first oil passage (11), and the oil outlet hole (52) is connected to the fuel cavity (14). A needle valve assembly (6) is disposed at the lower part of the housing (1). The needle valve assembly (6) has a pressure chamber that is connected to the second oil passage (12). The limiting mechanism (7) includes a driving component (71) and a limiting rod (72). The limiting rod (72) is slidably disposed inside the end cover (2). The two ends of the limiting rod (72) abut against the driving component (71) and the piston (4) respectively. The driving component (71) is disposed on the end cover (2) and is used to drive the limiting rod (72) to move so that the piston (4) slides relative to the housing (1).

2. The fuel injection device according to claim 1, characterized in that, The valve core (5) includes a sliding part (53) and a cutting part (54). The cutting part (54) forms a throttle port (33) between itself and the valve seat (3). The sliding part (53) can slide along the first direction so that the cutting part (54) contacts or separates from the valve seat (3). When the cutting part (54) contacts the valve seat (3), the fuel chamber (14) is connected to the first oil passage (11) through the throttle port (33) and is also connected to the second oil passage (12) through the throttle port (33). When the cutting part (54) separates from the valve seat (3), the oil inlet (51) is disconnected from the second oil passage (12), and the second oil passage (12) is connected to the fuel chamber (14).

3. The fuel injection device according to claim 1, characterized in that, The fuel injection device also includes a transfer valve (8), which is disposed at the fuel inlet (21) of the end cap (2). The transfer valve (8) is used to open and close the fuel inlet (21). The fuel inlet (21) is connected to alternative fuel, diesel fuel, or inert gas through the transfer valve (8).

4. The fuel injection device according to claim 1, characterized in that, The drive assembly (71) includes a motor (711) and an eccentric disk (712). The eccentric disk (712) is rotatably disposed on the end cover (2) and abuts against the limiting rod (72). The motor (711) is disposed on the end cover (2) and is used to drive the eccentric disk (712) to rotate relative to the end cover (2) so that the limiting rod (72) moves along the first direction.

5. The fuel injection device according to claim 1, characterized in that, The fuel injection device further includes a first elastic element (9), which is sleeved on the limiting rod (72). The outer peripheral wall of the limiting rod (72) is provided with a protrusion. The two ends of the first elastic element (9) abut against the end cap (2) and the protrusion, respectively. The first elastic element (9) is always in a tightened state.

6. The fuel injection device according to claim 1, characterized in that, The needle valve assembly (6) includes a second elastic element (61), a needle valve (62), and a valve body (63). The valve body (63) is connected to the housing (1) by a locking nut. One end of the needle valve (62) is slidably disposed on the valve body (63), and the other end of the needle valve (62) is slidably disposed on the housing (1). The second elastic element (61) is sleeved on the needle valve (62), and one end of the second elastic element (61) is connected to the needle valve (62), while the other end of the second elastic element (61) abuts against the housing (1). The needle valve (62) can block the nozzle (10) under the action of the second elastic element (61).

7. The fuel injection device according to claim 1, characterized in that, The valve seat (3) is provided with an oil return channel (31), which is connected to the oil tank. An oil film is provided between the valve seat (3) and the piston (4), and the oil film flows to the oil tank through the oil return channel (31).

8. A fuel injection device control method, characterized in that, Implemented by the fuel injection device as described in any one of claims 1-7, the fuel injection device control method includes: S100: The supply of diesel and alternative fuel is turned off, and inert gas is introduced into the fuel inlet (21) and mixed with the fuel in the housing (1) to inertize the fuel in the housing (1). The piston (4) is pushed down by the limiting mechanism (7) to accelerate the inertization of the fuel. S200: Under the action of the drive assembly (71), the limit rod (72) rises to the designated position, driving the piston (4) to adjust the stroke to the value corresponding to the fuel injection amount; S300: Diesel or alternative fuel flows through the valve chamber (32), the fuel chamber (14) and the second oil passage (12), and the fuel injection device operates in the target mode.

9. The fuel injection device control method according to claim 8, characterized in that, S300 in the fuel injection device control method specifically includes: S301: Diesel or alternative fuel passes sequentially through the fuel inlet (21), the first oil passage (11), the oil inlet (51), the oil outlet (52), the valve core (5), and the fuel chamber (14), pushing the piston (4) to rise along the first direction until the piston (4) abuts against the limiting rod (72), thus completing the intake of diesel or alternative fuel; S302: Servo oil enters the drive chamber (13) through the servo oil inlet (22), and the piston (4) moves downward along the first direction to increase the fuel pressure in the fuel chamber (14). At the same time, diesel and alternative fuel are injected through the needle valve assembly (6).

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