Variable swirl ratio air inlet channel based on double-valve cooperative control and control method

Abstract

The invention discloses a variable swirl ratio air inlet channel based on double-valve cooperative control and a control method. The air inlet channel comprises an air inlet, a first branch air channel and a second branch air channel, and the first branch air channel and the second branch air channel are arranged and adopted in a non-cross-deviation series connection mode; the second branch air passage is used for generating a main vortex, and the inner wall of the air passage is provided with a flow guide bulge or a bent shape; the inner wall face of the first branch air channel is a smooth wall face and is similar to a straight opening air channel. The outlet of the first branch air channel is close to the air inlet; an outlet of the second branch air channel is far away from the air inlet; a boss is further arranged on the upper wall face of the bent position of the first branch air channel and the second branch air channel, and the boss is communicated with the inner wall of the first branch air channel or the inner wall of the second branch air channel. The airflow flowing out of the first branch air channel is coordinated with the airflow flowing out of the second branch air channel in direction, so that the airflow from the first branch air channel flows in the direction of the lower piston, and the airflow from the second branch air channel flows in the radial direction of the cylinder sleeve.

Description

Technical Field

[0001] The present invention relates to the field of engine air intake, and in particular to a variable swirl ratio intake duct structure and a control method based on dual-valve coordinated control. Background Art

[0002] During engine operation, in-cylinder swirl has a significant impact on mixture formation and the combustion process. A suitable swirl ratio promotes thorough mixing of fuel and air, accelerating combustion, improving combustion efficiency, and reducing fuel consumption and harmful emissions. Conventional intake manifold structures make it difficult to flexibly adjust the in-cylinder swirl ratio according to varying engine operating conditions. This affects the degree of fuel-air mixing, leading to incomplete combustion and reduced engine power, fuel efficiency, and emissions. While some technical solutions for variable swirl ratios exist, most are complex, costly, and have limited control accuracy. For example, some approaches that modify the intake manifold shape or incorporate additional swirl-generating devices not only increase engine complexity and manufacturing costs but may also affect intake efficiency to a certain extent. Furthermore, conventional single-intake manifold, single-valve control methods struggle to precisely adjust the swirl ratio according to varying engine operating conditions, failing to fully meet the requirements for optimizing the combustion process under varying engine loads and speeds. Therefore, developing an intake technology with a simple structure, low cost, and the ability to effectively achieve a variable swirl ratio is of great practical significance.

[0003] In the prior art, to achieve a variable swirl ratio, complex devices such as throttle butterfly valves are typically installed at the intake duct entrance to adjust the in-cylinder swirl by changing the effective flow area of ​​the intake duct. Patent CN104033237B discloses a variable swirl intake duct for a multi-valve engine. This patent provides a first intake duct, a second intake duct, an intake adjustment channel, a swirl adjustment valve, and a swirl adjustment valve shaft on the intake manifold. The swirl adjustment valve's opening varies with engine operating conditions, thereby reducing the throttling effect of the valve on the airflow within the duct during variable swirl adjustment and alleviating the problem of decreased duct flow capacity. However, this approach has drawbacks such as being prone to insufficient intake volume and increased localized air resistance losses, which can affect engine performance. Summary of the Invention

[0004] To address the shortcomings of the prior art, the present invention provides a variable swirl ratio intake duct structure and control method based on dual-valve coordinated control. By designing the intake duct structure of a two-valve engine and adjusting the valve opening speed and duration, the variable swirl ratio intake duct structure achieves flexible control of the in-cylinder swirl ratio, adapting to combustion requirements under different engine operating conditions and improving overall engine performance.

[0005] The first object of the present invention is achieved through the following technical solutions:

[0006] A variable swirl ratio intake duct based on dual-valve coordinated control, the intake duct comprising an air inlet, a first air branch, and a second air branch, wherein the first air branch and the second air branch are arranged in a non-crossing, offset series manner; the second air branch is used to generate a main vortex, and the inner wall of the air branch has a flow-guiding protrusion or a curved shape; the inner wall of the first air branch is a smooth wall surface, similar to a straight air duct form;

[0007] Moreover, the outlet of the first airway is close to the air inlet; the outlet of the second airway is far away from the air inlet; and a boss is further provided on the upper wall surface at the bend of the first airway and the second airway, the boss being connected to the inner wall of the first airway / the second airway;

[0008] The directions of the airflow out of the first air channel and the airflow out of the second air channel are coordinated, so that the airflow from the first air channel flows toward the piston below, and the airflow from the second air channel flows along the radial direction of the cylinder liner.

[0009] Furthermore, the distance between the central axes of the first airway outlet and the second airway outlet is 40-80 mm.

[0010] Furthermore, the structural parameters of the second air passage are set so that the fluid generates a rotational motion around the valve axis in the second air passage before entering the cylinder.

[0011] Furthermore, the structural parameters of the second air duct include: the angle Av between the upper wall of the second air duct outlet and the bottom plane of the cylinder head, the angle Ab between the lower wall of the second air duct outlet and the bottom plane of the cylinder head, the intake duct bending radius R, the horizontal angle Ah between the line connecting the cylinder and the valve center and the center line of the air duct outlet, the vertical section height Hv of the upper wall of the second air duct outlet, the boss diameter D, and the boss height-to-diameter ratio H / B;

[0012] The structural parameters of the first air duct include: the angle Av between the wall above the air duct outlet and the bottom plane of the cylinder head, the angle Ab between the wall below the air duct outlet and the bottom plane of the cylinder head, the angle Ar of the air duct from the horizontal direction of the inlet to the horizontal direction of the outlet, the air duct bending radius R, the vertical section height Hv of the wall above the air duct outlet, the shape of the first air duct, the vertical section height of the wall above the first air duct outlet and the opening direction.

[0013] Furthermore, the structural parameters of the first airway and the second airway are optimized using an orthogonal experimental design and a multi-objective particle swarm optimization algorithm (MOPSO).

[0014] A second aspect of the present invention is to disclose a control method for a variable swirl ratio intake duct based on dual-valve coordinated control, comprising:

[0015] When the engine is under high load and high speed conditions and a stronger swirl ratio is required to promote combustion, the ECU controls the variable valve timing (VVT) / variable valve lift (VVL) to adjust the opening speed of the valves of the two branches, accelerating the valve drop process of the second branch away from the intake port, shortening the valve drop and opening time to 10-30ms; at the same time, the valve drop process of the first branch close to the intake port is slowed down, extending the valve drop and opening time to 40-80ms. That is, the valve of the second branch opens faster than the valve of the first branch, which can increase the airflow velocity and flow rate of the airflow from the outlet of the first branch into the cylinder, and reduce the interference of the airflow from the outlet of the second branch with the main swirl, thereby achieving an enhancement of the swirl ratio in the cylinder;

[0016] When the engine is idling or at low load, the valve opening speed of the two branches is adjusted by adjusting the valve lift to achieve a low swirl ratio intake condition of less than 0.8;

[0017] When it is necessary to maintain a low swirl ratio intake condition with a swirl ratio of less than 0.8 in the engine, the cam profile / camshaft speed is adjusted. The first branch adopts the method of rapid valve lifting and slow valve seating to adjust the valve lift, and the second branch adopts the method of slow valve lifting and rapid valve seating to adjust the valve lift. At this time, the swirl in the cylinder is smaller but the intake is faster; conversely, the first branch adopts the method of slow valve lifting and rapid valve seating to adjust the valve lift, and the second branch adopts the method of rapid valve lifting and slow valve seating to adjust the valve lift. The swirl in the cylinder is larger but the intake is slower.

[0018] Preferably, when it is necessary to maintain a low swirl ratio intake condition with a swirl ratio of less than 0.8 in the engine, the valve opening time of the first air duct is 10-30ms, the valve drop time is extended to 40-80ms, and the valve opening time of the second air duct is 40-80ms, and the valve drop time is shortened to 10-30ms; conversely, the valve opening time of the first air duct is 40-80ms, the valve drop time is shortened to 10-30ms, the valve opening time of the second air duct is 10-30ms, and the valve drop time is extended to 40-80ms.

[0019] Furthermore, the control method also includes: pre-designing the structural parameters, shape and opening direction of the first air duct and designing the structural parameters of the second air duct, so that the airflow from the first air duct flows toward the lower piston direction, and the airflow from the second air duct flows along the radial direction of the cylinder liner.

[0020] Furthermore, adjusting the valve lift by adjusting the valve lift curve of the cam profile includes:

[0021] The static lift formula is:

[0022] S(θ)=R(θ)-R0

[0023] Assume that the static lift is S(θ), where θ is the cam rotation angle; R0 is the cam base circle radius; and R(θ) is the radial coordinate function of the cam profile with respect to the rotation angle.

[0024] Furthermore, adjusting the valve lift by adjusting the camshaft speed includes:

[0025] If the camshaft speed is N rpm, then the angular velocity is:

[0026]

[0027] The velocity and acceleration of the static lift over time are:

[0028]

[0029] in and It can be directly calculated from the profile design curve; where s is the valve lift.

[0030] The third aspect of the present invention is to disclose a direct injection engine, including a variable swirl ratio intake duct and a control module based on dual-valve collaborative control; the control module is used to perform variable valve timing (VVT) control or variable valve lift (VVL) to control the opening and closing and opening speed of the first branch air duct and the second branch air duct.

[0031] Compared with the prior art, the variable swirl ratio intake duct structure and control method based on dual-valve coordinated control provided by the present invention has the following beneficial effects:

[0032] 1. The intake duct optimizes the shape and position of the two independent branch ducts, so that one outlet generates a strong swirling airflow, while the other outlet reduces interference with the main vortex. This effectively avoids the problem of turbulence caused by the mixing of the two airflows in the cylinder when the tangential air duct and the spiral air duct are combined.

[0033] 2. By utilizing variable valve timing or variable valve lift technology, the opening speed of the two intake valves can be precisely controlled. The in-cylinder swirl ratio can be flexibly adjusted according to the requirements of different engine operating conditions, thereby achieving precise optimization of the combustion process and improving the engine's power, economy and emission performance under various operating conditions. This solves the problem that traditional intake duct structures are difficult to flexibly adjust the in-cylinder swirl ratio. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 Schematic diagram of a variable swirl ratio intake duct based on dual-valve coordinated control of a direct injection engine according to an embodiment;

[0035] Figure 2 yes Figure 1 A top perspective view of the air intake is shown;

[0036] Figure 3 Schematic diagram of the structure for extracting the dominant influencing vortex in a single airway (regardless of the first or second airway) of the variable swirl ratio intake duct based on dual-valve coordinated control;

[0037] Figure 4 Schematic diagram of the horizontal angle Ah (the horizontal angle between the line connecting the cylinder and valve centers and the centerline of the intake duct outlet) of a single air duct of the variable swirl ratio intake duct based on dual-valve coordinated control;

[0038] Figure 5 It is a comparison of the lift schemes of the first valve lift scheme of adjusting the cam profile or the second valve lift scheme of adjusting the camshaft speed.

[0039] in,

[0040] 1: First airway; 2: First airway outlet; 3: Second airway; 4: Second airway outlet; 5: Boss. DETAILED DESCRIPTION

[0041] In order to make the purpose, technical solutions, beneficial effects and significant improvements of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in combination with the drawings provided in the examples of the present invention. Obviously, all the described embodiments are only partial embodiments of the present invention, rather than all embodiments; based on the demonstrations made in the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field based on the content, implementation methods and drawings of the present invention without making any creative work shall fall within the scope of protection of the present invention.

[0042] It should be noted that the terms "first", "second", "third", etc. in the description and claims of the present invention are only used to distinguish different objects, rather than to describe a specific order.

[0043] It should also be noted that the following specific embodiments may be combined with each other, and the same or similar concepts or processes therein may not be repeated in some embodiments.

[0044] like Figure 1-2As shown, a direct injection diesel engine includes a variable swirl ratio intake duct and a control module based on dual-valve coordinated control; the intake duct is a double tangential straight port duct, arranged in a non-crossing biased series manner, including an intake port and two branch ducts, namely a first branch duct 1 and a second branch duct 3. The second branch duct 3 is used to generate a main vortex, and its inner wall adopts a curved shape to guide the airflow into the cylinder at a specific angle and speed, thereby generating a strong rotating airflow; the inner wall surface of the first branch duct 1 is a smooth wall surface, similar to the form of a straight port duct, which is used to achieve minimal interference with the main vortex. The outlet of the first branch duct 1 is the first duct outlet 2, which is close to the intake port; the outlet of the second branch duct 3 is the second duct outlet 4; the second duct outlet 4 is away from the intake port. The intake port is located at the end of the intake duct away from the duct outlet; the first duct outlet 2 and the second duct outlet 4 are both connected to the cylinder and the intake duct. Moreover, a boss 5 is provided on the upper wall surface of the bending portion of the first airway and the second airway, and the boss 5 is communicated with the inner wall of the first airway / the second airway.

[0045] Moreover, the intake duct is manufactured using a high-precision mold forming process, such as precision casting or precision machining. The center axis spacing between the first air duct outlet 2 and the second air duct outlet 4 is 50.6 mm. The control module is used to perform variable valve timing (hereinafter referred to as VVT) control or variable valve lift (hereinafter referred to as VVL) control. The VVT ​​is a device that uses an ECU to control valve timing, and the VVL is a device that uses an ECU to control valve lift. The control module can be directly obtained by technicians in the relevant field based on existing technology.

[0046] like Figure 3-4 As shown, the second air branch 3 is a tangential straight air channel with a flow-guiding protrusion or curved shape within the air channel. Furthermore, the guide angle (the angle Av between the wall above the second air channel outlet 4 and the bottom plane of the cylinder head, and the angle AB between the wall below the second air channel outlet 4 and the bottom plane of the cylinder head), the horizontal angle Ah (the horizontal angle between the line connecting the cylinder and valve centers and the centerline of the intake duct outlet), the vertical section height Hv of the wall above the second air channel outlet 4, and the boss height-to-diameter ratio H / B of the second air channel 3 can be controlled by the control module, thereby designing the second air channel 3 into a special shape and direction that facilitates high-speed horizontal airflow movement. This causes the fluid to rotate around the valve axis within the second air channel 3 before entering the cylinder, ensuring that the airflow exiting this outlet forms a stable and strong vortex within the cylinder.

[0047] The first air duct 1 adopts a smooth inner wall design, and its shape and the position of the first air duct are optimized and designed to be approximately a straight air duct form. Its opening direction and shape are strictly processed and manufactured according to the optimized parameters, so that the airflow out of the first air duct outlet 2 is coordinated with the airflow direction out of the second air duct outlet 4, so that the airflow discharged from the first air duct 1 flows toward the lower piston, and the airflow from the second air duct flows along the radial direction of the cylinder liner, avoiding the generation of conflicting airflows and reducing the influence of the airflow out of the first air duct on the airflow out of the second air duct to form a large vortex, thereby achieving minimum interference with the main vortex.

[0048] The first air duct 1 is mainly used to reduce the interference of the airflow coming out of the second air duct outlet 4 far away from the air inlet, ensure the continuity of the curvature of the guide surface of the first air duct 1, and strictly control the air duct flow section contraction coefficient to ensure that the air intake volume is not affected.

[0049] The opening direction and shape parameters of the first and second air ducts are optimized using an orthogonal experimental design and multi-objective particle swarm optimization (MOPSO) algorithm. Since the geometric structure of an engine's air ducts has a decisive influence on their flow properties and airflow intensity, optimizing air duct structural parameters is an important means of improving combustion efficiency, reducing fuel consumption, and reducing emissions. This invention uses an orthogonal experimental design and multi-objective particle swarm optimization (MOPSO) algorithm to perform multi-factor parameter optimization and global sensitivity analysis on the intake ducts, aiming to find the optimal parameter combination that improves the intake duct's flow characteristics and airflow organization capabilities, thereby determining the opening direction and shape of the first and second air ducts.

[0050] Six key parameters control intake duct performance: the boss diameter D, the angle Av between the upper wall of the intake duct outlet and the cylinder head bottom plane, the angle Ab between the lower wall of the intake duct outlet and the cylinder head bottom plane, the angle Ar between the horizontal inlet and outlet, the intake duct bend radius R, and the vertical height Hv of the upper wall of the intake duct outlet. A rounded transition is designed at the junction of the boss and the intake duct body, and all transition radii meet typical casting specifications.

[0051] A global sensitivity analysis (GSA) of key parameters was performed based on orthogonal experimental design. Taking into account the multi-factor interaction effect and the wide range of parameters, this embodiment adopts an orthogonal experimental design method with 6 factors and 3 levels. By selecting appropriate orthogonal tables and interaction tables, the number of experiments can be greatly reduced and the experimental efficiency can be improved while ensuring the representativeness and coverage of the experiment. Hv, R and D were dimensionlessly processed by dividing by the outer diameter P of the airway outlet. Considering that there are no other special angles in the tangential airway template, Av, Ab and Ar were not dimensionlessly processed. The default values ​​of other structural parameters are basically the same as those of the original airway model.

[0052] Based on the identified key variables, a response surface methodology (RSM) was used to develop an airway performance prediction model. By fitting the test results, a performance prediction formula was constructed, providing a functional foundation for the optimization algorithm and improving optimization efficiency and accuracy.

[0053] Through orthogonal design analysis, three structural parameters (Av:x\Hv:y\Ar:z, x, y, z represent three unknowns) that have a greater impact on flow performance and airflow motion intensity are obtained. A response surface experiment is designed to build a prediction model for prediction. Then, an improved multi-objective particle swarm optimization algorithm (MOPSO) is used to search for the Pareto optimal solution set in parallel based on the traditional particle swarm optimization algorithm (PSO) to achieve multi-objective collaborative optimization.

[0054] The MOPSO multi-objective particle swarm optimization algorithm is based on the particle swarm optimization algorithm and searches for the Pareto optimal solution set in parallel. The MOPSO algorithm is written in Python to optimize airway flow characteristics. When optimizing airway parameters, the objective function is set to maximize the performance coefficient Cp. The objective function can be expressed as:

[0055]

[0056] Where: B is the cylinder diameter; D is the valve seat diameter; n is the number of valves opened; L is the valve lift; N A is the eddy current intensity, G f is the flow coefficient. Both evaluation indicators are determined by the inlet performance parameters. The Pareto optimal solution set is used to find the structural parameter combination that has the greatest impact on the flow performance and the airflow motion intensity.

[0057] N A =6.21-0.0874*x-0.0235*y-14.48*z+0.000229*x*x+0.000232*y*y+12.15*z*z+

[0058] 0.000660*x*y+0.1011*x*z-0.0308*y*z

[0059] G f =0.5727+0.00433*x+0.003530*y-0.1193*z-0.000027*x*x-0.000182*y*y+0.408*z*z

[0060] +0.000025*x*y-0.000552*x*z+0.005073*y*z

[0061] The control method of the variable swirl ratio intake duct based on dual-valve coordinated control includes:

[0062] Step 1: Use SOLIDWORKS software to design the shape of the first branch airway 1, the vertical section height of the wall above the first airway outlet 1 (approximately a straight airway), and the opening direction based on the angle Av between the wall above the intake duct outlet and the bottom plane of the cylinder head, the angle Ab between the wall below the intake duct outlet and the bottom plane of the cylinder head, the angle Ar from the horizontal direction of the airway inlet to the horizontal direction of the outlet, the intake duct bending radius R, and the vertical section height Hv of the wall above the intake duct outlet.

[0063] Using SOLIDWORKS software, the inner wall of the second air duct 3 was designed with a flow-guiding protrusion or curved shape. This included designing the angle Av between the upper wall of the second air duct outlet 4 and the cylinder head bottom plane, the angle AB between the lower wall of the second air duct outlet 4 and the cylinder head bottom plane, the horizontal angle Ah, the vertical height Hv of the upper wall of the second air duct outlet 4, and the protrusion height-to-diameter ratio H / B. This guides airflow into the cylinder at a specific angle and speed, generating a strong swirling airflow. Table 1 shows the structural parameters of the designed first and second air ducts.

[0064] Table 1: Structural parameters of the first and second bronchial airways after design

[0065]

[0066]

[0067] Step 2: When the engine is in a high-load, high-speed operating condition and a stronger swirl ratio is required to promote combustion, the control module is used to enable the ECU to control the variable valve timing (VVT), adjust the opening speed of the valves of the two branches, accelerate the valve drop process of the second branch 3 away from the air intake, and shorten the valve drop opening time to 10-30ms; at the same time, slow down the valve drop process of the first branch 1 close to the air intake, and extend the valve drop opening time to 40-80ms, that is, the valve of the second branch 3 opens faster than the valve of the first branch 1, which can increase the airflow velocity and flow of the airflow from the first airway outlet 2 into the cylinder, and reduce the interference of the airflow from the second airway outlet 4 with the main vortex, thereby achieving an enhancement of the swirl ratio in the cylinder;

[0068] When the engine is idling or in low-load condition, the control module is used to adjust the opening speed of the valves of the two air ducts so that the time for the two valves to fall and open is adjusted so that the two valves can reach the intake condition of maintaining the swirl ratio in the cylinder at the top dead center at 0.4-0.8 by adjusting the valve lift, so as to ensure the stable operation of the engine and fuel economy.

[0069] The first solution for setting the valve lift (i.e., the valve lifting speed) of the present invention is to realize the valve lift curve by adjusting the cam profile, which corresponds to the static lift formula.

[0070] Assume the static lift (ignoring inertia and deformation) is S(θ), where

[0071] Among them, θ is the cam angle (rad or deg); R0 is the cam base circle radius; other geometric parameters (eccentricity, swing arm length, etc.) can be determined by design; then

[0072] S(θ)=R(θ)-R0

[0073] Where R(θ) is the radial coordinate function of the cam profile with respect to the rotation angle.

[0074] The second valve lift scheme (i.e., valve lifting speed) is to achieve the valve lift curves of the two schemes by adjusting the camshaft speed, corresponding to the angular velocity formula.

[0075] If the camshaft speed is N rpm, then the angular velocity is:

[0076]

[0077] The velocity and acceleration of the static lift over time are:

[0078]

[0079] in and It can be directly calculated from the profile design curve.

[0080] When the first air duct with good flow performance adopts solution one and the second air duct that is easy to form a larger vortex adopts solution two, the vortex in the cylinder is smaller but the air intake is faster. Conversely, when the first air duct adopts solution two and the second air duct adopts solution one, the vortex in the cylinder is larger but the air intake is slower.

[0081] Figure 5 A comparison of two lift schemes, Scheme 1 and Scheme 2, is shown. It can be clearly seen that the valve of Scheme 2 can be lifted up quickly and seated slowly compared to Scheme 1.

[0082] Through the above steps, the present invention realizes the flexible adjustment of the swirl ratio in the cylinder, and meets the performance requirements of the engine under different working conditions.

[0083] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents, and these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention. Non-essential improvements, adjustments or replacements made by those skilled in the art based on the contents of this specification are all within the scope of protection required by the present invention.

Claims

1. A variable swirl ratio intake duct based on dual valve coordinated control, characterized in that: The air inlet comprises an air inlet, a first air branch (1), and a second air branch (3), wherein the first air branch (1) and the second air branch (3) are arranged in a non-crossing, biased series manner; the second air branch (3) is used to generate a main vortex, and the inner wall of the air channel has a flow-guiding bulge or a curved shape; the inner wall of the first air branch (1) is a smooth wall surface, which is similar to a straight air channel form; Moreover, the outlet of the first airway (1) is close to the air inlet; the outlet of the second airway (3) is far away from the air inlet; and a boss (5) is further included on the upper wall surface at the bend of the first airway and the second airway, wherein the inner wall of the boss (5) is in communication with the inner wall of the first airway / the inner wall of the second airway; The fluid flowing through the second air passage (3) generates a rotational motion around the valve axis in the second air passage (3) before entering the cylinder; The directions of the airflow out of the first air channel (1) and the airflow out of the second air channel (3) are coordinated, so that the airflow from the first air channel (1) flows toward the piston below, and the airflow from the second air channel flows along the radial direction of the cylinder liner.

2. The variable swirl ratio intake port based on dual valve coordinated control according to claim 1, characterized in that: The structural parameters of the second air duct (3) include: the angle Av between the upper wall of the second air duct outlet (4) and the bottom plane of the cylinder head, the angle Ab between the lower wall of the second air duct outlet (4) and the bottom plane of the cylinder head, the inlet duct bending radius R, the horizontal angle Ah between the cylinder and valve center line and the air duct outlet center line, the vertical section height Hv of the upper wall of the second air duct outlet (4), the boss diameter D and the boss height-to-diameter ratio H / B; The structural parameters of the first air duct (1) include: the angle Av between the upper wall surface of the first air duct outlet (2) and the bottom plane of the cylinder head, the angle Ab between the lower wall surface of the first air duct outlet (2) and the bottom plane of the cylinder head, the angle Ar of the first air duct from the horizontal direction of the inlet to the horizontal direction of the outlet, the bending radius R of the first air duct, the vertical section height Hv of the upper wall surface of the first air duct outlet, the shape of the first air duct (1), the vertical section height of the upper wall surface of the first air duct outlet (2) and the opening direction.

3. The variable swirl ratio intake port based on dual valve coordinated control according to claim 1, characterized in that: The structural parameters of the first airway (1) and the second airway (3) are optimized by using an orthogonal experimental design and a multi-objective particle swarm optimization algorithm.

4. A control method for a variable swirl ratio intake duct with dual valve coordinated control according to any one of claims 1 to 3, comprising: When the engine is in a high-load, high-speed operating condition and a stronger swirl ratio is required to promote combustion, the ECU controls the variable valve timing / variable valve lift to adjust the opening speed of the valves of the two branches, so that the valve of the second branch (3) opens faster than the valve of the first branch (1), increases the airflow speed and flow rate of the airflow from the first airway outlet (2) into the cylinder, and reduces the interference of the airflow from the second airway outlet (4) with the main swirl, thereby achieving an enhancement of the swirl ratio in the cylinder; When the engine is idling or at low load, the valve opening speed of the two branches is adjusted by adjusting the valve lift to achieve a low swirl ratio intake condition of less than 0.8; When it is necessary to maintain a low swirl ratio intake condition with a swirl ratio of less than 0.8 in the engine, the cam profile / camshaft speed is adjusted. The first branch adopts the method of rapid valve lifting and slow valve seating to adjust the valve lift, and the second branch adopts the method of slow valve lifting and rapid valve seating to adjust the valve lift. At this time, the swirl in the cylinder is smaller but the intake is faster; conversely, the first branch adopts the method of slow valve lifting and rapid valve seating to adjust the valve lift, and the second branch adopts the method of rapid valve lifting and slow valve seating to adjust the valve lift. The swirl in the cylinder is larger but the intake is slower.

5. The control method of the variable swirl ratio intake port based on the dual valve coordinated control according to claim 4 is characterized in that: When the engine is in a high-load, high-speed operating condition, the valve drop process of the second air duct (3) away from the air inlet is accelerated, so that the time for the valve to drop and open is shortened to 10-30ms; at the same time, the valve drop process of the first air duct (1) close to the air inlet is slowed down, so that the time for the valve to drop and open is extended to 40-80ms.

6. The control method of the variable swirl ratio intake port based on the dual valve coordinated control according to claim 4 is characterized in that: The control method further comprises: pre-designing the structural parameters, shape and opening direction of the first air duct (1) and designing the structural parameters of the second air duct (3), so that the airflow from the first air duct (1) flows toward the piston below, and the airflow from the second air duct flows along the radial direction of the cylinder liner.

7. The control method of the variable swirl ratio intake port based on the dual valve coordinated control according to claim 4 is characterized in that: Adjusting the valve lift by adjusting the valve lift curve of the cam profile includes: The static lift formula is: S(θ)=R(θ)-R0 Assume that the static lift is s(θ), where θ is the cam rotation angle; R0 is the cam base circle radius; and R(θ) is the radial coordinate function of the cam profile with respect to the rotation angle.

8. The control method of the variable swirl ratio intake port based on the dual valve coordinated control according to claim 4 is characterized in that: Adjusting the valve lift by adjusting the camshaft speed includes: If the camshaft speed is N rpm, then the angular velocity is: The velocity and acceleration of the static lift over time are: in and It can be directly calculated from the profile design curve; where s is the valve lift.

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