Two-stroke internal combustion engine port injection method

Abstract

This invention discloses a two-stroke internal combustion engine intake manifold injection method, comprising the steps of: acquiring real-time engine operating parameters; based on the real-time operating parameters, controlling at least one injector to inject fuel into the intake manifold with predetermined injection parameters; the injection parameters are set such that the fuel jet ejected by the injector interacts with the airflow entering the intake manifold in the region below the injector, utilizing airflow kinetic energy to promote fuel fragmentation and mixing. This two-stroke internal combustion engine intake manifold injection method of the present invention fragments and mixes the fuel jet within the intake manifold, allowing the fuel to undergo preliminary evaporation and mixing before entering the crankcase, forming a premixed air-fuel mixture with extremely high uniformity. This ensures that most of the fuel is fully atomized and mixed with air before entering the crankcase, significantly reducing the proportion of fuel existing in liquid form; simultaneously, the homogeneous mixture reduces circulation fluctuations, improving fuel atomization and engine combustion efficiency.

Description

Technical Field

[0001] This invention belongs to the field of engine technology. Specifically, this invention relates to an intake manifold injection method for a two-stroke internal combustion engine. Background Technology

[0002] The existing two-stroke gasoline engine uses an intake manifold injection method, where the time window from fuel injection to the air-fuel mixture entering the cylinder is only tens of milliseconds. The mixing process is concentrated in the limited volume of the intake manifold, and fuel molecules cannot fully contact the air. At the same time, the scavenging process of the two-stroke engine is extremely short, and the airflow in the cylinder is in a high-speed, turbulent, and violent complex state, which further hinders the uniform diffusion and atomization of fuel.

[0003] Moreover, the injected fuel droplets are prone to impacting the intake manifold wall and forming an oil film. The presence of the oil film not only leads to an imbalance in the air-fuel mixture ratio, but also causes delayed fuel evaporation, resulting in sluggish engine power response. Furthermore, the insufficiently evaporated fuel droplets will reduce combustion efficiency and increase pollutant emissions.

[0004] Furthermore, fuel viscosity increases and volatility decreases in low-temperature environments, making it difficult for traditional injection methods to achieve efficient fuel atomization and mixture formation. This directly leads to poor engine cold start performance, unstable idling speed, and fluctuations in power output.

[0005] This invention provides a method for intake manifold injection in a two-stroke internal combustion engine, particularly concerning how to improve fuel atomization and engine combustion efficiency. Summary of the Invention

[0006] This invention aims to at least solve one of the technical problems existing in the prior art. To this end, this invention provides an intake manifold injection method for a two-stroke internal combustion engine, with the purpose of improving fuel atomization and engine combustion efficiency.

[0007] To achieve the above objectives, the technical solution adopted by the present invention is: a two-stroke internal combustion engine intake manifold injection method, comprising the following steps: S1. Obtain the engine's real-time operating parameters; S2. Based on the real-time operating parameters, control at least one injector to inject fuel into the intake manifold with predetermined injection parameters. The fuel injection parameters are set such that the fuel jet injected by the injector interacts with the airflow entering the intake manifold in the area below the injector, thereby using the kinetic energy of the airflow to promote the breaking and mixing of the fuel.

[0008] The real-time operating parameters include the intake pressure and intake temperature monitored by the intake pressure and temperature sensor.

[0009] Controlling fuel injection based on the real-time operating parameters includes: Calculate the current intake density or flow rate based on the intake pressure and intake temperature; The target injection quantity of the injector is determined based at least on the current intake air density or flow rate.

[0010] The injection parameters include injection timing, which controls the injector to open during a time window when the intake airflow speed reaches or exceeds a preset threshold.

[0011] Within one working cycle, the injector is controlled to perform multiple injections, including at least one pre-injection and one main injection; the injection timing of the main injection is when the piston is close to the bottom dead center, at which time the intake airflow velocity is relatively high.

[0012] The pre-injection occurs after the intake valve opens and before the piston reaches bottom dead center, at a crankshaft angle of 60° to 90°.

[0013] The intake manifold has a single intake port and two symmetrically arranged branch air passages downstream of it. The fuel injector is located near the upstream end of each branch air passage, so that the incoming airflow can flow evenly to both sides and interact with the fuel jet sprayed by the corresponding fuel injector.

[0014] The fuel system supply pressure is dynamically adjusted based on the real-time operating parameters, including the output pressure of the low-pressure fuel pump or the fuel rail pressure.

[0015] When the intake pressure and intake temperature indicate a low intake flow condition, the injection ratio of the pre-injection is increased or the injection timing of the pre-injection is advanced; when the condition is indicated as a high intake flow condition, the main injection is ensured to be performed during the high intake flow phase.

[0016] The injector is a multi-hole injector, and the number of nozzles in the multi-hole injector is 4 to 8, with the nozzle axis forming a preset angle with the airflow direction of the intake duct.

[0017] The two-stroke internal combustion engine intake manifold injection method of this invention breaks down and mixes the fuel jet within the intake manifold, allowing the fuel to undergo preliminary evaporation and mixing before entering the crankcase. This results in a premixed air-fuel mixture with extremely high homogeneity, ensuring that the vast majority of the fuel is fully atomized and mixed with air before entering the crankcase, significantly reducing the proportion of fuel in liquid form. The highly homogeneous mixture leads to faster and more stable flame propagation during ignition. This makes combustion closer to isochoric combustion, improving heat-to-work conversion efficiency. Simultaneously, the homogeneous mixture reduces circulation fluctuations, resulting in smoother engine operation, more linear power output, and improved fuel atomization and engine combustion efficiency. Attached Figure Description

[0018] This manual includes the following figures, which illustrate the following: Figure 1 This is a schematic diagram of the connection principle of the intake manifold injection system of a two-stroke internal combustion engine; Figure 2 This is a flow field diagram of the intake manifold of a two-stroke internal combustion engine's intake manifold injection system. Figure 3 This is a structural diagram of the intake manifold of a two-stroke internal combustion engine's intake manifold injection system. The following are marked in the diagram: 1. Oil tank; 2. Low-pressure oil pump; 3. Oil filter; 4. Pressure relief valve; 5. Three-way valve; 6. Oil rail; 7. Injector; 8. Intake manifold; 9. Single air inlet; 10. Branch air passage. Detailed Implementation

[0019] The specific embodiments of the present invention will be further described in detail below with reference to the accompanying drawings, in order to help those skilled in the art to have a more complete, accurate and in-depth understanding of the concept and technical solutions of the present invention, and to facilitate its implementation.

[0020] This invention provides an intake manifold injection method for a two-stroke internal combustion engine, comprising the following steps: S1. Obtain the engine's real-time operating parameters; S2. Based on real-time operating parameters, control at least one injector to inject fuel into the intake manifold with predetermined injection parameters. The injection parameters are set so that the fuel jet injected by the injector interacts with the airflow entering the intake manifold in the area below the injector, utilizing the kinetic energy of the airflow to promote fuel breakdown and mixing. Specifically, this invention relates to the technical field of fuel intake manifold injection systems for two-stroke gasoline engines, and a novel intake manifold injection system for improving fuel-air mixing is installed on an internal combustion engine. Figure 1 As shown, this intake manifold injection system consists of an electronic control unit (ECU), a low-pressure fuel pump, fuel injectors, low-pressure fuel lines, and a fuel rail. Its fuel path is arranged as follows: low-pressure fuel pump → fuel filter → pressure relief valve → fuel rail → fuel injector. The ECU is connected to the low-pressure fuel pump and fuel injectors, and sends control commands to adjust injection parameters by receiving sensor signals from the intake manifold. During operation, the low-pressure fuel pump pressurizes and delivers fuel to the fuel rail, which then supplies fuel to the corresponding injectors through independent fuel lines. The ECU acquires engine operating parameters through sensors and adjusts the fuel injection quantity and duration in real time, ultimately ensuring precise fuel injection into the intake manifold of the two-stroke internal combustion engine.

[0021] The intake manifold injection method for a two-stroke internal combustion engine according to this invention operates on the principle of actively using the intake manifold as the site for initial fuel atomization and mixing. Its function is achieved through the following process: First, fuel preparation is performed. The low-pressure fuel pump delivers fuel to the fuel rail and maintains the fuel pressure within the fuel rail at a stable level within a set range.

[0022] Secondly, coordinated injection is performed. The electronic control unit (ECU) calculates and outputs corresponding fuel injection control commands based on real-time collected engine operating parameters. This is mainly reflected in two aspects: first, injection timing control, where the ECU controls the injectors to open and inject fuel during a predetermined time period when the airflow velocity in the intake manifold reaches a high level; second, the utilization of intake kinetic energy, where fuel is injected into the high-speed airflow through the injectors, utilizing the kinetic energy of the intake airflow to shear, carry, and break up the fuel jet, thus completing the initial atomization and partial evaporation of the fuel within the intake manifold. The effective implementation of this process directly benefits from the aforementioned intake manifold structural design. Specifically, the arrangement of the single intake port and the dual-branch air passages, along with their internal profiles, can generate tumble and turbulence with specific shapes and intensities during the intake process, providing optimized airflow organization for fuel-air mixing.

[0023] Finally, a premixed air-fuel mixture is formed. After the premixing in the intake manifold described above, a mixture with significantly improved air-fuel mixture quality is formed. This mixture then enters the crankcase and participates in the subsequent scavenging process.

[0024] In embodiments of the present invention, such as Figure 2 and Figure 3 As shown, the intake manifold has a single intake port and two symmetrically located branch intake ports downstream of it. Each branch intake port has an injector near its upstream end, allowing the incoming airflow to flow evenly to both sides and interact with the fuel jet ejected by the corresponding injector. One end of each branch intake port is connected to the single intake port of the intake manifold, and the other end is connected to the crankcase of the internal combustion engine, allowing the air-fuel mixture to enter the crankcase.

[0025] Through the coordinated layout of the intake manifold structure and the injector mounting position described above, the intake airflow entering from the single intake port can be uniformly guided to the two branch intake channels. During operation, the injector sprays fuel downwards, forming a fuel jet with downward momentum. This fuel jet converges with the horizontally accelerating airflow within the branch intake channels in a specific area directly below the injector. Utilizing the interaction between the two momentum streams, the fuel jet is effectively sheared, collided, and broken up by the high-speed airflow, thereby generating a complex turbulent and tumble flow field with specific morphology and intensity below this area. This enhanced flow field greatly increases the contact area and interaction time between air and fuel particles, significantly promoting fuel evaporation and its mixing with air.

[0026] This organized, intense turbulent flow and tumble motion can continue throughout the subsequent scavenging process and persist until the end of the compression stroke, thus continuously and uniformly entraining the atomized fuel particles in the air, ultimately forming a highly homogeneous mixture in the combustion chamber. This mixture state provides the necessary conditions for rapid and stable flame propagation and complete combustion after ignition.

[0027] In this embodiment of the invention, real-time operating parameters include intake pressure and intake temperature monitored by an intake pressure and temperature sensor. The intake pressure and temperature sensor is located on the intake manifold. The intake pressure and temperature sensor is upgraded from a traditional environmental parameter monitoring unit to the core of adaptive and coordinated control of the entire fuel injection system. By monitoring the pressure and temperature of the intake manifold in real time, the system can accurately calculate the current intake air density and flow rate, and use this as a key input to dynamically and coordinatedly control the injection strategy of the fuel injectors in the fuel system.

[0028] In this embodiment of the invention, in step S2 above, controlling the fuel injector to inject fuel based on real-time operating parameters includes: Calculate the current intake density or flow rate based on the intake pressure and intake temperature; The target injection quantity of the injector in one working cycle is determined based at least on the current intake air density or flow rate, and in combination with other operating parameters.

[0029] In this embodiment of the invention, by implementing timed and quantitative precise fuel injection upstream of the intake manifold, and utilizing the kinetic energy of the intake airflow itself, the initial atomization and premixing of fuel are achieved within the intake manifold, thereby fundamentally solving the problems of high fuel consumption and high emissions caused by fuel scavenging loss and uneven mixing in traditional two-stroke engines.

[0030] In step S2 above, the injection parameters include injection timing, which controls the injector to open during a time window when the intake airflow speed reaches or exceeds a preset threshold.

[0031] In step S2 above, within one working cycle, the injector is controlled to perform multiple injections, including one pre-injection and one main injection. The injection timing of the main injection is when the piston is near bottom dead center, which corresponds to the period of high airflow velocity during the intake process. The pre-injection occurs after the intake valve opens and before the piston reaches bottom dead center, with a crankshaft rotation angle of 60° to 90°. The intake manifold is designed with two symmetrically arranged branch passages that can generate high-energy tumble / vortex with specific shape and intensity. A single intake port is located in the middle of the two branch passages. During the main injection phase, the strong airflow passes precisely through the injector's fuel jet area, "shearing" and "entraining" the fuel spray, thereby achieving a "hyperhomogeneous mixing" process that begins within the manifold, significantly improving the quality of the air-fuel mixture entering the cylinder.

[0032] Furthermore, the system divides the total fuel injection quantity within a single working cycle into multiple injection pulses with different functions. The first injection is a pre-injection, with its timing set as described above. This pre-injection aims to cool the inner walls of the intake manifold and the air flowing through it through the physical effect of fuel evaporation absorbing heat, thereby helping to reduce the thermal load on the intake system. The subsequent main injection, as a precise metered injection, utilizes the strongest intake airflow energy at its set injection timing to achieve more complete secondary atomization and effective delivery to the combustion chamber. This design aims to promote the formation of a highly homogeneous air-fuel mixture with an ideal air-fuel ratio around the spark plug.

[0033] In this embodiment of the invention, the fuel supply pressure is dynamically adjusted based on real-time operating parameters. The supply pressure includes the output pressure of the low-pressure fuel pump or the fuel rail pressure.

[0034] In this embodiment of the invention, when the intake pressure and intake temperature determine that the intake flow condition is low, the injection ratio of pre-injection is increased or the injection timing of pre-injection is advanced; when the condition is determined to be high, the main injection is ensured to be performed during the high intake flow stage.

[0035] Furthermore, the real-time data provided by the intake air pressure and temperature sensor forms the basic input for the system's coordinated control. The electronic control unit not only bases its decisions on engine speed and load, but also on the actual physical state of the intake air to comprehensively determine the required fuel injection quantity and atomization requirements, and accordingly decides on parameters such as the target injection pressure.

[0036] Based on signals from the intake air pressure and temperature sensor, the system can adaptively match fuel supply and injection strategy. This includes dynamically adjusting the output of the low-pressure fuel pump and the fuel pressure in the fuel rail, while also adjusting the injection mode of the injectors (e.g., the timing and quantity distribution of pre-injection and main injection). Under conditions of low intake airflow, the system tends to perform or advance pre-injection. At this time, the airflow velocity in the intake manifold is relatively low, and the fuel injected earlier can obtain a longer physical mixing time, thereby compensating for insufficient mixing kinetic energy caused by low air density and weak turbulence intensity. Under conditions of high intake airflow, the system ensures that the main injection is performed during the stage of high airflow tumble intensity, so that the fuel is quickly broken up and entrained by high-intensity turbulence after injection, thereby improving the mixing speed and uniformity.

[0037] Furthermore, through real-time feedback from the intake air pressure and temperature sensor, the fuel injection process can form a closed-loop feedback control with the actual intake air flow state. This closed-loop system ensures that, under various intake conditions, the fuel injected by the injector can be effectively broken up and mixed by the airflow movement within the intake manifold, thereby optimizing the uniformity and stability of the air-fuel mixture across the entire operating range.

[0038] In this embodiment of the invention, the injector is a multi-hole injector, which has 4 to 8 nozzles, and the nozzle axis forms a preset angle with the airflow direction of the intake duct.

[0039] The present invention has been described above by way of example with reference to the accompanying drawings. Obviously, the specific implementation of the present invention is not limited to the above-described manner. Any non-substantial improvements made using the inventive concept and technical solution; or the direct application of the inventive concept and technical solution to other situations without modification, are all within the protection scope of the present invention.

Claims

1. A two-stroke internal combustion engine intake manifold injection method, characterized in that, Including the following steps: S1. Obtain the engine's real-time operating parameters; S2. Based on the real-time operating parameters, control at least one injector to inject fuel into the intake manifold with predetermined injection parameters. The fuel injection parameters are set such that the fuel jet injected by the injector interacts with the airflow entering the intake manifold in the area below the injector, thereby using the kinetic energy of the airflow to promote the breaking and mixing of the fuel.

2. The two-stroke internal combustion engine intake manifold injection method according to claim 1, characterized in that, The real-time operating parameters include the intake pressure and intake temperature monitored by the intake pressure and temperature sensor.

3. The two-stroke internal combustion engine intake manifold injection method according to claim 2, characterized in that, Controlling fuel injection based on the real-time operating parameters includes: Calculate the current intake density or flow rate based on the intake pressure and intake temperature; The target injection quantity of the injector is determined based at least on the current intake air density or flow rate.

4. The two-stroke internal combustion engine intake manifold injection method according to claim 2 or 3, characterized in that, The injection parameters include injection timing, which controls the injector to open during a time window when the intake airflow speed reaches or exceeds a preset threshold.

5. The two-stroke internal combustion engine intake manifold injection method according to any one of claims 1 to 4, characterized in that, Within one working cycle, the injector is controlled to perform multiple injections, including at least one pre-injection and one main injection; the injection timing of the main injection is when the piston is close to the bottom dead center, at which time the intake airflow velocity is relatively high.

6. The two-stroke internal combustion engine intake manifold injection method according to claim 5, characterized in that, The pre-injection occurs after the intake valve opens and before the piston reaches bottom dead center, at a crankshaft angle of 60° to 90°.

7. The two-stroke internal combustion engine intake manifold injection method according to any one of claims 1 to 6, characterized in that, The intake manifold has a single intake port and two symmetrically arranged branch air passages downstream of it. The fuel injector is located near the upstream end of each branch air passage, so that the incoming airflow can flow evenly to both sides and interact with the fuel jet sprayed by the corresponding fuel injector.

8. The two-stroke internal combustion engine intake manifold injection method according to claim 2, characterized in that, The fuel system supply pressure is dynamically adjusted based on the real-time operating parameters, including the output pressure of the low-pressure fuel pump or the fuel rail pressure.

9. The two-stroke internal combustion engine intake manifold injection method according to claim 8, characterized in that, When the intake pressure and intake temperature indicate a low intake flow condition, the injection ratio of the pre-injection is increased or the injection timing of the pre-injection is advanced; when the condition is indicated as a high intake flow condition, the main injection is ensured to be performed during the high intake flow phase.

10. The two-stroke internal combustion engine intake manifold injection method according to any one of claims 1 to 9, characterized in that, The injector is a multi-hole injector, which has 4 to 8 nozzles, and the nozzle axis forms a preset angle with the airflow direction of the intake duct.

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