Multi-fuel engine

Abstract

The invention discloses a multi-fuel engine, which belongs to the technical field of internal combustion engines and comprises a two-stage progressive efficient mixing system. The system comprises a pre-mixing system arranged in an intake manifold, wherein the pre-mixing system is used for primarily atomizing and dispersing fuel through a rotatable vortex type intake valve with a special structure; and the in-cylinder vortex ultimate mixing system is used for carrying out final refined mixing on mixed gas through a combined piston. The combined piston is composed of a piston base body and a detachable vortex enhancing assembly. Through staged mixing treatment and modular structural design, the fuel adaptability and combustion efficiency of the engine are remarkably improved, and meanwhile design flexibility and reliability are improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of internal combustion engines, in particular to a multi-fuel engine. BACKGROUND

[0002] As the main power source, the fuel adaptability of internal combustion engines has always been an important direction of technological development. Multi-fuel engines aim to be compatible with gasoline, diesel, alcohol fuel or natural gas and other fuels with different physical and chemical properties, in order to improve the flexibility and economy of energy use. However, different fuels have significant differences in volatility, viscosity, self-ignition point, etc., and the combustion efficiency of the engine under different fuel modes also needs to be considered.

[0003] Currently, how to ensure that different fuels can form uniform and suitable ignition mixture with air after being injected into the cylinder is a difficulty in achieving efficient combustion. In the prior art, methods such as optimizing the intake port structure, designing the shape of the piston top, and increasing the fuel injection pressure are usually used to promote the formation of the mixture. However, by designing an intake port with a specific geometric shape, such as a spiral or tangential intake port, the airflow movement pattern produced by this fixed geometry intake port is single. For difficult-to-atomize diesel or alcohol fuels, simple macro-vortex flow cannot achieve uniform mixing at the micro level, and the fixed structure cannot adapt to the optimal mixing requirements of the engine under different speeds and loads. By designing a recess on the top of the piston, similar problems as optimizing the intake port exist, that is, once the shape of the recess on the top of the piston is determined, the turbulence pattern and intensity it produces are relatively fixed and cannot adapt to the mixing requirements of different fuels. For example, a deep recess piston designed for diesel compression ignition is not completely suitable for the ignition of gasoline homogeneous mixture.

[0004] In addition, by using high-pressure common rail technology, the fuel is physically atomized when it is injected at extremely high pressure, which can improve the initial atomization effect to some extent. However, whether the fuel droplets can be fully mixed with the air in the cylinder within a very short time still depends heavily on the airflow organization in the cylinder. If the airflow movement and the oil beam shape do not match, it will still cause problems such as local over-concentration or over-dilution, fuel wetting, carbon deposition, and increased harmful emissions. SUMMARY

[0005] The purpose of the present application is to solve the problems existing in the prior art and to provide a multi-fuel engine.

[0006] In order to achieve the above purpose, the present application adopts the following technical scheme: A multi-fuel engine, comprising a cylinder, a piston installed in the cylinder, and an intake manifold communicating with the cylinder, comprising a multi-injection system and a high-efficiency mixing system arranged in a two-stage progressive manner. The multi-injection system comprises: a first nozzle arranged on the cylinder head and used for directly injecting fuel into the cylinder; a second nozzle arranged on the cylinder head and used for directly injecting fuel into the cylinder; a third nozzle arranged in the intake manifold; a fourth nozzle arranged in the intake manifold; a two-stage progressive high-efficiency mixing system for mixing fuel or working medium injected by the multi-injection system, the two-stage progressive high-efficiency mixing system comprising a premixing system arranged in the intake manifold, the premixing system comprising a rotating vortex intake valve, a head portion of the rotating vortex intake valve being provided with an impact surface, the impact surface being provided with a turbine blade structure, the turbine blade structure comprising a plurality of helical guide vanes arranged in a circumferential direction of the impact surface, a curved surface of each helical guide vane being arranged to convert an axial impact force of airflow into a tangential force for driving rotation of the head portion; and an in-cylinder vortex mixing system comprising a combined piston installed in the cylinder, the combined piston comprising: a piston base body provided at a top portion thereof with a mounting base for accommodating functional components; and a modular vortex component made of a low-thermal-conductivity material and mounted in the mounting base, an upper surface of the modular vortex component having a preset three-dimensional curved surface for mixing the preliminarily atomized and dispersed mixed gas at a late compression stroke.

[0007] Further, the head portion of the rotating vortex intake valve is connected to the valve stem through a connecting mechanism, the connecting mechanism allowing relative rotation between the head portion and the valve stem.

[0008] Further, the connecting mechanism is a two-stage lift floating connecting mechanism, the connecting mechanism reserving an axial matching gap between a limiting structure of the head portion and the sleeve, a distance of the axial matching gap being the floating stroke; at an initial stage of lift of the valve stem, the head portion can float in the axial matching gap to form a preliminary opening gap, high-speed airflow generated through the preliminary opening gap achieving early driving rotation of the head portion; after the floating stroke, the connecting mechanism is arranged to rigidly transmit subsequent lift actions of the valve stem to the head portion to complete the whole opening stroke.

[0009] Further, the two-stage lift floating connecting mechanism comprises: a floating connecting sleeve connected to the valve stem; a pre-tightening spring installed inside the sleeve for realizing floating stroke of the head; and a limiting structure arranged inside the sleeve for locking relative axial position of the head and valve stem after the floating stroke ends.

[0010] Further, the upper surface of the vortex-enhanced component, i.e. the preset three-dimensional curved surface, comprises: at least one spray-guiding groove, the curvature and orientation of which are characterized in that they are arranged to match the spray cone angle of the oil injector, so as to receive and guide the oil jet along the trajectory of the groove during injection; and a buttressing area, which comprises a central boss arranged in the center of the vortex-enhanced component and located between the end points of the plurality of spray-guiding grooves, the sidewall of the central boss being arranged as a flow-guiding slope for forcibly changing and intercepting the high-speed airflow out of the guiding grooves, so that the airflow collides and swirls around the boss, thereby forming high-intensity turbulent flow.

[0011] Further, the preset three-dimensional curved surface further comprises a secondary breaking structure; the secondary breaking structure is a raised ridge arranged at the end of the trajectory of the spray-guiding groove, the cross section of the raised ridge is an acute angle, and the extension direction of the raised ridge is perpendicular to the main flow direction of the spray-guiding groove, the sharp edge of the raised ridge and its layout perpendicular to the fluid are arranged to be able to perform scraping and impact actions on the high-speed moving liquid oil film, thereby realizing mechanical breaking.

[0012] Further, the lower surface of the vortex-enhanced component is provided with a plurality of support bosses arranged in an annular array along the outer peripheral edge thereof; the support bosses are used to define an air insulation layer between the vortex-enhanced component and the piston base, and the air insulation layer maintains a higher temperature on the upper surface of the component by blocking heat conduction to promote fuel evaporation.

[0013] Further, the vortex-enhanced component is made of engineering ceramic material.

[0014] Further, the preset three-dimensional curved surface comprises a bowl-shaped pit arranged in the central area, the depth and volume of the bowl-shaped pit are arranged to be able to receive and accommodate the main oil jet sprayed by the oil injector, so as to form a local rich mixture core; and a flow extrusion area around the bowl-shaped pit, the opening edge of the bowl-shaped pit is designed as a smooth chamfer transition, and the edge of the smooth transition is arranged to be able to guide and swirl the gas extruded at high speed from the flow extrusion area, so as to promote the orderly mixing of the rich mixture core and the surrounding air.

[0015] Further, the preset three-dimensional curved surface comprises a convex ridge of M type across the central region, and a cross-sectional shape of the convex ridge is arranged to be capable of interacting with the pre-formed tumble flow in the cylinder; By splitting the tumble flow into two vortexes with opposite directions at the end of the compression stroke, a large range of turbulence is generated in the combustion chamber.

[0016] Compared with the prior art, the present application has the beneficial effects that: By the cooperation of the premixing system arranged in the intake manifold and the in-cylinder vortex ultimate mixing system, the rotatable tumble intake valve in the premixing system can preliminarily atomize and disperse the entering fuel, and the combined piston in the in-cylinder vortex ultimate mixing system can finally finely mix, so that the problem of single mixing mode caused by the fixed geometry of the intake port or the piston top recess and the difficulty in adapting to different fuel characteristics can be overcome by the stage processing mode. By the secondary lift floating connection structure, the rotatable tumble intake valve can be driven to rotate at a high speed at the initial stage of intake, so that efficient turbulence is achieved during the whole intake stroke. In addition, the spray guide groove, the central boss and the convex ridge on the upper surface of the detachable vortex enhancement assembly can generate high-intensity turbulence and secondary breaking effect at the end of compression. Furthermore, the micro air insulation layer formed by the support boss on the lower surface can maintain the high temperature of the assembly, promote fuel evaporation, and thus ensure the uniformity and dynamics of the mixture before ignition, so that faster and more complete combustion is achieved, and the problems of combustion deterioration and carbon deposition caused by uneven mixing are avoided. By replacing the vortex enhancement assembly with different preset three-dimensional curved surfaces, such as the bowl-shaped recess for stratified combustion or the convex ridge of M type for high tumble speed combustion, the combustion strategy can be flexibly adjusted to adapt to different application requirements without changing the engine body design. In addition, since the vortex enhancement assembly that bears the maximum thermal load is made of durable materials such as engineering ceramics and can be replaced individually, the overall reliability of the piston is significantly improved, and the long-term maintenance cost is reduced. BRIEF DESCRIPTION OF DRAWINGS

[0017] The accompanying drawings are included to provide a further understanding of the present application, and constitute a part of the specification, illustrate the present application and are used to explain the present application together with the embodiments of the present application, and do not constitute a limitation on the present application.

[0018] Figure 1 The overall structure schematic diagram of the multi-fuel engine proposed in the present application; Figure 2 The Figure 1 The enlarged view of A in FIG. 6; Figure 3 The partial enlarged view of the piston of the multi-fuel engine proposed in the present application; Figure 4This is a top view of the upper surface of the module eddy current assembly in Embodiment 1 of the present invention; Figure 5 This is a top view of the upper surface of the modular eddy current assembly in Embodiment 2 of the present invention; Figure 6 This is a top view of the upper surface of the module eddy current assembly in Embodiment 3 of the present invention; Figure 7 This is a logic block diagram of the multi-fuel injection control system in an embodiment of the present invention.

[0019] In the diagram: 1. Intake manifold; 2. Cylinder; 3. Piston; 4. First nozzle; 5. Second nozzle; 6. Third nozzle; 7. Fourth nozzle; 8. Spark plug; 100. Rotating vortex intake valve; 110. Valve stem; 120. Head; 121. Impact surface; 122. Turbine blade structure; 123. Spiral guide vane; 130. Connecting mechanism; 141. Floating connecting sleeve; 142. Preload spring; 143. Limiting structure; 144. Axial fit clearance; 210. Piston base; 211. Mounting base; 220. Modular vortex assembly; 221. Support boss; 222. Air insulation layer; 310. Spray guide groove; 320. Counter-current area; 321. Central boss; 330. Secondary crushing structure; 410. Bowl-shaped pit; 420. Squeezing zone; 510. M-shaped raised ridge. Detailed Implementation

[0020] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments.

[0021] like Figures 1-6 As shown, the multi-fuel engine of the present invention includes a multi-injection system working in concert and a two-stage progressive high-efficiency mixing system; It should be noted that the multi-fuel engine of this invention utilizes an engine control unit (ECU) that receives input signals from a series of sensors and sends control commands to each actuator to implement the complex control strategy. The sensors include at least: a crankshaft position sensor, a throttle opening sensor, a knock sensor, an oxygen sensor, and a fuel composition sensor for identifying fuel type. The actuators include at least: an ignition module consisting of a first nozzle 4, a second nozzle 5, a third nozzle 6, a fourth nozzle 7, and a spark plug 8. In this application, the multi-injection system refers to a dual direct injection / dual manifold injection (2DI + 2PFI) system intelligently controlled by the engine control unit (ECU). This system can flexibly employ different or multiple injectors based on fuel type, engine operating conditions, and driver requirements, achieving intelligent switching of combustion modes. The multi-injection system includes: First nozzle 4: its functional orientation is a direct injection of main fuel nozzle. The nozzle is arranged on the cylinder head, for high-pressure injection of main fuel with high energy density but difficult to atomize and ignite, such as diesel, biodiesel or heavy alcohol fuel, into the cylinder 2.

[0022] Second nozzle 5: its functional orientation is a direct injection of combustion-supporting / performance-enhancing nozzle. The nozzle is also arranged on the cylinder head, with its nozzle directly extending into the cylinder 2. It is mainly used to spray a small amount of active and high latent heat of vaporization combustion-supporting or performance-enhancing fuel, such as methanol, ethanol or gasoline, as needed and accurately, to achieve in-cylinder cooling, suppress knock, and assist main fuel to achieve stable ignition and efficient and clean combustion.

[0023] Third nozzle 6: the nozzle is arranged in the intake manifold 1. Its functional orientation is a gas fuel or premixed fuel manifold nozzle, which is specially used to spray natural gas CNG or liquefied petroleum gas LPG and other gas fuels, or to spray gasoline or alcohol fuel to form homogeneous lean premixed gas under certain working conditions.

[0024] Fourth nozzle 7: the nozzle is also arranged in the intake manifold 1. Its functional orientation is an auxiliary cooling nozzle, which is specially used to spray water or water / ethanol mixture as needed under extreme conditions such as ultra-high load of the engine, to further cool the intake air and control the combustion temperature through its evaporative cooling effect, as a supplement to direct injection cooling.

[0025] In addition, in order to be able to mix the fuel or working medium supplied by the above-mentioned multi-injection system efficiently, a two-stage progressive high-efficiency mixing system is also provided, which includes an intake manifold premixing system and an in-cylinder vortex ultimate mixing system, wherein: The main part of the intake manifold premixing system is a rotatable vortex intake valve 100, which is responsible for the first-stage premixing and atomizing dispersion of the fuel or working medium injected into the intake manifold 1 by the first nozzle 4, the third nozzle 6 or the fourth nozzle 7. The head 120 of the rotatable vortex intake valve 100 is connected with the valve stem 110 through a two-stage lift floating connection structure 140, which can activate the turbine blade structure 122 of the head 120 at a high speed in the opening moment, so as to rotate at a high speed and disperse the fuel by centrifugal force; It is also necessary to further illustrate that the head 120 of the rotatable vortex intake valve 100 is connected with the valve stem 110 through a connecting mechanism 130. In the preferred embodiment of the present application, the connecting mechanism 130 is the two-stage lift floating connecting structure 140. The structure includes a floating connecting sleeve 141 fixedly connected with the valve stem 110, and the valve stem part of the head 120 is rotatably inserted into the inside of the floating connecting sleeve 141. Inside the sleeve, a pre-tightening spring 142 is installed, and a limiting structure 143 is arranged. In the assembled state, there is a pre-set axial matching gap 144 between the valve stem top end of the head 120 and the limiting structure 143, and the distance of the gap is the floating stroke.

[0026] The premixing system includes the rotatable vortex intake valve 100, the head 120 of the rotatable vortex intake valve 100 has an impact surface 121, the impact surface 121 is provided with a turbine blade structure 122, The turbine blade structure 122 includes a plurality of helical guide vanes 123 arranged in a circumferential direction of the impact surface 121, and the curved surface of each helical guide vane 123 is arranged to be able to convert the axial impact force of the airflow into a tangential force to drive the rotation of the head 120; In order to realize high-efficiency rotation while ensuring lightweight and high strength, the head 120 of the rotatable vortex intake valve 100 is preferably made of titanium alloy or high-temperature reinforced composite material in the embodiment, so that the response to airflow is more sensitive through lower mass and moment of inertia, and it is ensured that the high-speed airflow generated in the small opening gap in the floating stroke stage is sufficient to drive it to start rotating rapidly. The turbine blade structure 122 on the impact surface 121 of the head 120 of the rotatable vortex intake valve 100 is specifically composed of a plurality of helical guide vanes 123, and the cross section of each vane can be designed as a wing-shaped cross section with a certain curvature to efficiently convert the axial kinetic energy of the airflow into torque to drive the rotation of the head 120 with optimal aerodynamic performance. The arrangement of the vanes has a specific angle of attack, which is designed not only to drive rotation, but also to add a strong circumferential velocity component to the airflow passing through the vane channel, that is, the airflow itself carries a strong spiral motion vortex when entering the cylinder, which constitutes an important part of the "premixing" in the two-stage progressive mixing. Therefore, the head 120 structure of the rotatable vortex intake valve 100 can realize both centrifugal atomization of its own rotation and guiding airflow to generate macroscopic vortex.

[0027] The core component of the in-cylinder vortex mixing system of the present invention is a combined piston 200. This combined piston 200 consists of a piston base 210 and a detachable vortex enhancement assembly 220. The piston base 210, made of conventional metal materials, is the main body of the piston. Its top is machined with a mounting base 211 for precision mounting of functional components. This mounting base 211 is a groove that matches the shape of the detachable vortex enhancement assembly 220, and its sidewalls and bottom surface provide stable support and positioning for the detachable vortex enhancement assembly 220. The main difference between the following embodiments lies in the different upper surface structures of the detachable vortex enhancement assembly 220 mounted within the mounting base 211.

[0028] Example 1: like Figures 1-4 As shown in this embodiment, for efficient combustion of various fuels, especially difficult-to-atomize fuels, the vortex enhancement component 220 uses a modular vortex component 220, whose upper surface is provided with at least one spray guide groove 310, a counter-current region 320, and a secondary crushing structure 330, wherein: The curvature and orientation of the spray guide groove 310 are matched with the spray pattern of the fuel injector to guide the fuel jet; The counter-current region 320 includes a central boss 321 located at the center of the component and between the endpoints of multiple spray guide channels 310. The guide slope of its sidewall can force multiple airflows to collide with each other, forming extremely strong turbulence. A secondary crushing structure 330 is provided at the end of the spray guide channel 310. Specifically, it is a raised ridge with an acute angle in cross-section and its extension direction is perpendicular to the mainstream direction. It is used to mechanically scrape and crush the high-speed moving liquid oil film.

[0029] In practical implementation, intake premixing: First, the fuel mixture is processed by the aforementioned common intake manifold 1 premixing system, and after being initially atomized, it is drawn into the cylinder.

[0030] During the compression stroke, the direct injection system is activated, and the fuel jet is precisely injected into the spray guide 310, forming a high-speed rotating fuel flow under the guidance of its curved surface. As the piston approaches top dead center, the high-speed liquid oil film moving within the guide groove impacts the raised ridges at the end of its trajectory. The sharp ridges mechanically scrape and impact the oil film, shattering it into even smaller droplets.

[0031] The oil-gas mixture, which has been broken up in the second stage, is compressed at high speed along with gas from other regions toward the central opposing region 320. Under the action of the guiding slope of the central boss 321, they collide violently and are entrained, instantly forming a micro-turbulent flow with extremely high energy, which allows the oil droplets and air molecules to achieve the most complete mixing.

[0032] Finally, spark plug 8 ignites this extremely homogenized air-fuel mixture, achieving rapid and complete combustion. Throughout the process, the air insulation layer 222 reduces heat loss, maintains the high temperature of the component surface, and further promotes fuel evaporation.

[0033] Example 2: Stratified Lean Combustion Implementation Scheme like Figures 1-5 As shown, in this embodiment, a bowl-shaped recess 410 is provided in the central region of the upper surface of the modular vortex assembly 220, and a flat extrusion zone 420 is surrounded by the bowl-shaped recess 410. The opening edge of the bowl-shaped recess 410 is designed with a smooth chamfer transition.

[0034] In practice, the engine mainly draws in air or an extremely lean mixture; At the end of the compression stroke, the injector injects a small, precisely metered stream of fuel directly into the bowl-shaped recess 410 on the top of the piston. Under the constraint of the pit, the fuel forms a locally thick and easily ignitable air-fuel mixture core near spark plug 8, while the vast area outside the pit remains lean. At the moment the piston reaches top dead center, the air in the squeeze zone 420 is squeezed towards the center at high speed. The smooth chamfer transition structure of the edge of the bowl-shaped pit 410 can guide this squeezed air to smoothly entrain and scour the edge of the rich mixture core, forming a stable combustion flame front. Spark plug 8 ignites this stable rich mixture core, and the flame then spreads to the surrounding lean mixture, achieving overall lean combustion and thus completing work with minimal fuel consumption.

[0035] Example 3: like Figures 1-6 As shown, in this embodiment, the modular vortex assembly 220 is used in a high-speed, high-power gasoline engine, and the upper surface of the modular vortex assembly 220 has an M-shaped raised ridge 510 spanning the central region.

[0036] In practice, during the intake stroke, the engine intake port is designed to make the air-fuel mixture entering the cylinder form a powerful airflow that tumbles around the horizontal axis, creating a tumble flow. During the compression stroke, the tumble stream is continuously squeezed as the piston moves upward, and its energy and shape are maintained. As the piston approaches top dead center, the massive tumble stream directly impacts the M-shaped raised ridge 510 on the piston top. The raised ridge 510 structure acts like a wedge, breaking the tumble stream into two or more vortices that rotate in opposite directions, move faster, and are smaller in scale. The energy conversion from macroscopic ordered motion to microscopic disordered motion generates high-intensity turbulence over a large area throughout the combustion chamber; Spark plug 8 ignites the air-fuel mixture in a state of intense turbulence. With the help of countless tiny eddies, the flame propagates at extremely high speeds, ensuring that the fuel can be completely burned before the piston descends during extremely short high-speed operation, thereby releasing maximum power.

[0037] The above-described embodiments one, two, and three illustrate three different but preferred design schemes for the modular vortex component 220 of the present invention. In practical applications, those skilled in the art can select the appropriate implementation scheme according to the specific design goals of the engine, or, under the guidance of the core idea of ​​the present invention, perform other deformation designs on the three-dimensional curved surface of the component's upper surface to achieve a specific combustion effect. Furthermore, the detachable vortex enhancement component 220, when made of engineering ceramic material, can be manufactured using ceramic powder injection molding, followed by sintering and precision grinding to obtain a precise three-dimensional curved surface on its upper surface. The mounting base 211 on top of the piston base 210 can be machined using a high-precision CNC machine tool. During assembly, an interference fit method based on thermal expansion and contraction can be used, i.e., heating the piston base 210 to expand its mounting base 211, then placing the room-temperature vortex enhancement component 220 inside, and forming a strong connection after cooling.

[0038] For example, in a preferred embodiment, the counter-flush region 320 of Embodiment 1 is combined with the M-shaped raised ridge 510 of Embodiment 3 to form a novel structure that combines counter-flush and tumble-breaking capabilities. Similarly, the number, depth, and curvature of the spray guide grooves 310, as well as the position and shape of the secondary breaking structure 330, can be adaptively adjusted according to the characteristics of the matched injector and the cylinder structure.

[0039] It should be noted that, regardless of how the upper surface structure changes, the modular design concept of the combined piston 3 and the structure of forming an air insulation layer 222 using the support boss 221 on the lower surface of the component are universal technical features that are applicable to all implementation methods.

[0040] Example 4: like Figures 1-6 As shown, based on embodiments 1-3, in this embodiment, the modular eddy current assembly 220 has a composite three-dimensional curved surface on its upper surface, including: A bowl-shaped depression 410 is set in the central area, and multiple shallow spray guide grooves 310 are arranged radially outward from the edge of the bowl-shaped depression 410. The flat or slightly convex areas between the guide grooves together constitute the squeezing zone 420.

[0041] The lower surface of the modular eddy current assembly 220 in this design also adopts a structure of support boss 221 and air insulation layer 222.

[0042] In specific implementation: Mode one: ECU instructs the injector to adopt the mode of small injection amount and narrow cone angle spray at the end of compression stroke.

[0043] Implementation process: A small amount of highly concentrated fuel is precisely injected and contained in the central bowl-shaped pit 410 to form a local rich mixture core. At this time, the outer shallow spray guide groove 310 does not participate in the guidance of the oil beam. When the piston reaches the top dead center, the air in the squish area 420 is squeezed to the center to orderly entrain and mix the rich mixture core, realize stable lean combustion, and achieve the purpose of saving fuel.

[0044] Mode two: ECU instructs the injector to adopt the mode of large injection amount and wide cone angle spray at the intake stroke or early compression stroke.

[0045] Implementation process: A wider range of oil beams fall into the bowl-shaped pit 410 after entering the cylinder, and the peripheral part is captured and guided by multiple shallow spray guide grooves 310. During the compression process, the airflow in the guide groove interacts with the airflow in the squish area 420, and the central pit also plays a role as a counter area 320, together exciting high-intensity turbulence in the entire combustion chamber. Finally, form a uniform homogeneous mixture suitable for high-power output, realize strong power performance.

[0046] Example 5: As Figures 1-7 On the basis of the above examples, this embodiment further illustrates how to combine heavy fuel (such as diesel) with combustion / performance enhancing fuel (such as methanol) through the coordinated control of the double direct injection system to achieve efficient, clean, and knock-free combustion under high load conditions.

[0047] This embodiment takes the use of diesel as the main fuel and methanol as the combustion / performance enhancing fuel as an example for illustration, but the control method of the present application is not limited thereto.

[0048] When the engine is in a high load operating state, the control target is to efficiently and cleanly burn diesel while outputting strong power and completely suppressing knock.

[0049] Specific implementation and mixing process: The engine normally inhales air. According to the need, the fourth nozzle 7 (auxiliary cooling nozzle) can spray water mist for preliminary intake air cooling.

[0050] In the middle and late compression stroke, ECU instructs the two direct injection nozzles to work in time sequence according to the required power and combustion state: The ECU first instructs the second nozzle 5 (combustion-supporting / performance-enhancing direct-injection nozzle) to inject a predetermined amount of methanol directly into the cylinder. The high-pressure injected methanol is atomized and rapidly vaporized in the high-temperature environment in the cylinder, instantaneously absorbing a large amount of heat, achieving strong in-cylinder cooling, and greatly improving the anti-knock margin of the engine.

[0051] Subsequently, the ECU instructs the first nozzle 4 (main fuel direct-injection nozzle) to inject the main fuel diesel directly into the in-cylinder environment that has been pre-cooled and diluted by the methanol vapor. The diesel jet is directly shot at the vortex-enhancing assembly 220 on the top of the combined piston 3, which is forced to break up and atomize under the action of its complex three-dimensional surface, and to undergo violent secondary mixing with the air-methanol mixture in the cylinder.

[0052] The flexibility of ignition and combustion can be compatible with multiple modes of use, including: Spark plug-assisted ignition mode: The ECU can control the methanol jet injected by the second nozzle 5 to form a mixture area around the electrodes of the spark plug 8 that is easy to ignite. The spark plug reliably ignites this core of methanol-air mixture, and the high-energy flame front formed quickly and stably ignites the surrounding diesel-air mixture that is more difficult to ignite, achieving overall combustion.

[0053] Compression ignition mode: Under high compression ratio conditions, the activity difference between the two fuels can be utilized. The pre-cooled in-cylinder environment effectively delays the self-ignition of diesel, avoiding knocking; and near the compression top dead center, the highly atomized diesel reaches the ignition point with the methanol-air mixture under high temperature and high pressure, achieving a smooth and controlled compression ignition process. The oxygen atoms in the methanol molecules also promote the combustion of diesel in this process, effectively reducing the formation of soot.

[0054] As can be seen from the above, by using high-performance fuels such as methanol for in-cylinder direct injection, the advantages of direct injection technology can be effectively utilized, not just by simply introducing a combustion-supporting agent, but by the synergistic effect of "pre-injection cooling" and "oxygen-containing combustion", the core pain points of heavy fuel knocking and black smoke under high load are fundamentally solved. This strategy allows the engine to use more economical heavy fuel without sacrificing power, while also meeting stringent emission regulations, making the present scheme have multi-fuel adaptability and multi-scene application performance.

[0055] The above is only the preferred specific embodiment of the present application, but the protection scope of the present application is not limited thereto, any person skilled in the art can make equivalent substitutions or changes within the technical scope disclosed by the present application according to the technical solution and inventive concept of the present application, which should be covered within the protection scope of the present application.

Claims

1. A multi-fuel engine comprising a cylinder (2), a piston (3) installed in the cylinder (2), an intake manifold (1) communicating with the cylinder (2), and a spark plug (8) provided at the top of the cylinder (2) to ignite a mixture, characterized in that, The multi-injection system and the high-efficiency mixing system arranged in a two-stage progressive manner are included; The multi-injection system includes: a first nozzle (4) arranged on the cylinder head and used for directly injecting fuel into the cylinder (2); a second nozzle (5) arranged on the cylinder head and used for directly injecting fuel into the cylinder (2); a third nozzle (6) arranged in the intake manifold (1); a fourth nozzle (7) arranged in the intake manifold (1); The high-efficiency mixing system in a two-stage progressive manner is used for mixing fuel or working medium injected by the multi-injection system, and includes a premixing system arranged in the intake manifold (1), the premixing system including a rotating vortex intake valve (100), a head (120) of the rotating vortex intake valve (100) being provided with an impact surface (121), the impact surface (121) being provided with a turbine blade structure (122), The turbine blade structure (122) includes a plurality of helical guide vanes (123) arranged in a circumferential direction of the impact surface (121), a curve surface of each of the helical guide vanes (123) being arranged to be capable of converting an axial impact force of air flow into a tangential force for driving the head (120) to rotate; and an in-cylinder vortex mixing system including a piston (3), the piston (3) being a combined structure piston, the piston (3) including: a piston base body (210) provided at a top portion thereof with a mounting base (211) for accommodating functional components; and a module vortex component (220) made of a low-thermal-conductivity material and mounted in the mounting base (211), an upper surface of the module vortex component (220) having a preset three-dimensional curve surface for mixing mixed gas preliminarily atomized and dispersed at an end of a compression stroke.

2. The multi-fuel engine of claim 1, wherein The head (120) is connected with a valve stem (110) through a connecting mechanism (130), the connecting mechanism (130) allowing relative rotation between the head (120) and the valve stem (110); and the connecting mechanism (130) is a two-stage-lift floating connecting structure, the two-stage-lift floating connecting structure including: a floating connecting sleeve (141) connected with the valve stem (110); a pre-tightening spring (142) mounted in the sleeve and used for realizing floating stroke of the head (120); and a limiting structure (143) arranged in the floating connecting sleeve (141) and used for locking relative axial positions of the head (120) and the valve stem (110) after the floating stroke ends; wherein the connecting mechanism (130) is provided with an axial matching gap (144) between the head (120) and the limiting structure (143), and a distance of the axial matching gap (144) is the floating stroke. At the initial stage of the valve stem (110) lift, the head (120) is able to float within the axial fit clearance (144) for forming a preliminary opening gap, through which high speed airflow is generated for driving the head (120) to rotate in advance; After the floating stroke, the connecting structure (130) is arranged to rigidly transmit the subsequent lift action of the valve stem (110) to the head (120) to complete the full opening stroke.

3. The multi-fuel engine of claim 1, wherein The upper surface of the vortex enhancement assembly, i.e. the preset three-dimensional curved surface, comprises: at least one spray guide groove (310), the curvature and the running direction of the spray guide groove (310) are characterized in that they are arranged to be able to match the spray cone angle of the oil injector, so as to receive and guide the oil jet along the trajectory of the groove during oil injection; and a buttressing area (320) comprising a central boss (321) arranged at the center of the vortex enhancement assembly and located between the endpoints of the plurality of spray guide grooves (310), the sidewall of the central boss (321) is arranged as a flow guide slope for forcibly changing and intercepting the high-speed airflow flowing out of the guide groove, so that multiple airflows collide and swirl around the central boss (321); and the preset three-dimensional curved surface further comprises a secondary crushing structure (330); the secondary crushing structure (330) is a raised ridge arranged at the end of the trajectory of the spray guide groove (310), the cross section of the raised ridge is an acute angle, and the extension direction of the raised ridge is perpendicular to the main flow direction of the spray guide groove (310), the sharp edge of the raised ridge and its layout perpendicular to the fluid are arranged to be able to perform scraping and impact actions on the high-speed moving liquid oil film.

4. The multi-fuel engine according to any one of claims 1 to 3, characterized by, The lower surface of the vortex enhancement assembly is provided with a plurality of support bosses (221) arranged in a ring array along the outer peripheral edge, for defining an air insulation layer (222) between the vortex enhancement assembly and the piston base (210); and the vortex enhancement assembly is made of any engineering ceramic material.

5. The multi-fuel engine of claim 1, wherein, The preset three-dimensional curved surface comprises a bowl-shaped pit (410) arranged in the central area, the depth and volume of the bowl-shaped pit (410) are arranged to be able to receive and accommodate the main oil jet ejected by the oil injector, so as to form a local rich mixture core; and a flow extrusion area (420) surrounding the bowl-shaped pit (410), the opening edge of the bowl-shaped pit (410) is designed as a smooth chamfer transition for guiding and swirling the high-speed extruded gas from the flow extrusion area (420).

6. The multi-fuel engine of claim 1, wherein, The preset three-dimensional curved surface comprises an M-shaped raised ridge (510) across the central area, the cross-sectional shape of the raised ridge (510) is arranged to be able to interact with the tumble flow previously formed in the cylinder, so as to split the tumble flow into two vortexes with opposite directions at the end of the compression stroke.

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