Mixed arrangement type air port structure for large-cylinder-diameter opposed-piston two-stroke diesel engine

Abstract

The mixed arrangement type air port structure comprises a plurality of air ports annularly and evenly arranged on the wall face of an air cylinder along the central axis of the air cylinder, the air ports comprise direct flow air ports and vortex air ports which are arranged in a staggered mode, and the diameter heights of the direct flow air ports and the vortex air ports are the same; the direct flow air port is communicated with the direct flow air channel, the vortex air port is communicated with the vortex air channel, the direct flow air channel and the vortex air channel are communicated to the air inlet channels on the two sides nearby in a side-by-side mode, the air inlet channels are asymmetric air channels, and the vortex air channel is a double-layer vortex air channel which is vertically stacked and communicated, namely the vortex air channel is equally divided into an upper vortex air channel and a lower vortex air channel along the XY section. The upper vortex inclination angle S1 of the upper vortex air channel is different from the lower vortex inclination angle S2 of the lower vortex air channel; according to the mixed arrangement type air port structure, on the premise that scavenging efficiency and capture quality are guaranteed, the TKE in an air cylinder in each stage of combustion is always kept at a high level, and compared with a combined arrangement type air port structure, the total heat release amount is increased by 9.95%, and the IMEP is increased by 4.91%.

Description

Technical Field

[0001] The invention relates to the technical field of two-stroke diesel engines, and in particular to a mixed arrangement type air port structure for a large-cylinder-diameter opposed-piston two-stroke diesel engine. Background Art

[0002] Since the ventilation process of the opposed piston two-stroke engine (OP2S) is short, the ventilation process is a key link that restricts its performance improvement; different from the previous small and medium-sized opposed piston two-stroke diesel engines, the large-bore opposed piston two-stroke diesel engine has a larger cylinder diameter, and its spray oil-gas mixing effect is insufficient, and the requirements for various scavenging performance evaluation parameters are more stringent. For large-bore opposed piston two-stroke diesel engines, the idea of ​​simply pursuing high capture quality and scavenging efficiency may not be able to achieve a good oil-gas mixing effect, and the high TKE in the cylinder at the time of spray combustion is conducive to oil-gas mixing. Therefore, in order to further optimize spray combustion, it is necessary to comprehensively consider scavenging efficiency, capture quality and TKE in the cylinder at the time of spray combustion.

[0003] The traditional single-layer vortex port, straight flow port or tumble port can no longer form a complete scavenging surface during the scavenging process, and it is even more impossible to simultaneously achieve scavenging, vortex and tumble, and achieve a comprehensive improvement of the three at the same time; therefore, a complex air port structure needs to be designed for a large-bore opposed-piston two-stroke diesel engine. The complex air port structure seen in the prior art is a combined air port structure. Referring to the patent CN201410415536.X, a two-stroke diesel engine intake duct, the simplified structure is obtained as follows Figure 1 As shown in the structure, the combined air port cannot take into account both the scavenging performance (scavenging efficiency and captured mass) and the TKE in the cylinder at the middle and late stages of combustion, and is not suitable for large-bore opposed-piston two-stroke diesel engines. Summary of the invention

[0004] The purpose of the present invention is to overcome the defects in the prior art and provide a hybrid arrangement air port structure for a large-cylinder opposed-piston two-stroke diesel engine, so as to overcome one or more problems caused by the limitations and defects of the relevant technology to a certain extent.

[0005] In order to achieve the above object, the technical solution of the present invention is as follows:

[0006] A mixed arrangement air port structure for a large-bore opposed-piston two-stroke diesel engine comprises a plurality of air ports uniformly arranged in a ring on the wall of the cylinder along the central axis thereof, the air ports comprising staggered straight flow ports and vortex ports, the straight flow ports and the vortex ports having the same aperture height; the straight flow ports are connected to straight flow passages, the vortex ports are connected to vortex passages, the straight flow passages and the vortex passages are connected to intake passages on both sides at the nearest side, the intake passages matched with the mixed arrangement air port structure are asymmetric air passages, the vortex passages are double-layer vortex passages connected in upper and lower layers, that is, the vortex passages are equally divided into an upper vortex passage and a lower vortex passage along an XY section, the upper vortex inclination angle S1 of the upper vortex passage is different from the lower vortex inclination angle S2 of the lower vortex passage.

[0007] Further, the angular difference between the upper vortex inclination angle S1 and the lower vortex inclination angle S2 is within 0-10°, and the upper vortex inclination angle S1 and the lower vortex inclination angle S2 are both within 20°-30°.

[0008] Furthermore, both the upper vortex airway and the lower vortex airway are gradually diverging airways, and the gradually diverging angles thereof are 0°-10°.

[0009] Furthermore, the straight flow airway is a tapered airway, and its tapering angle is 3°-15°.

[0010] Furthermore, the lower channel surface of the straight airway has an upward inclination angle for further guiding the tumble flow, and the upward inclination angle is 0-8°.

[0011] Further, the direct current air port and the vortex air port are staggered along the Z axis, that is, there is an early opening amount D between the lower end edge of the direct current air port and the lower end edge of the vortex air port.

[0012] Furthermore, the vortex air port is located at the front end of the direct air port, and is used to open the vortex airflow in advance to improve the scavenging quality, and the advance opening amount D is 0-2.5mm.

[0013] Furthermore, the direct current air port is located at the front end of the vortex air port, and is used to open the direct current airflow in advance to improve the insufficient central scavenging, and the advance opening amount D is 0-2.5mm.

[0014] Furthermore, the straight flow airway and the vortex airway are connected to the air intake ducts on both sides at the nearest side, and the air intake duct matched with the mixed arrangement air port structure is an asymmetric air duct.

[0015] Furthermore, transition fillets are provided on both sides of one end of the straight airway and the vortex airway connected to the air inlet, and a guide fillet is provided on one side of the other end of the vortex airway along the vortex direction.

[0016] Compared with the prior art, the hybrid arrangement type air port structure for a large-diameter opposed-piston two-stroke diesel engine of the present invention has the following beneficial effects:

[0017] The mixed arrangement air port structure includes direct current air ports and vortex air ports in the same layer and staggered annular distribution with equal interval angles. The rear end of the vortex air port is a double-layer vortex air passage with unequal vortex inclination angles. The direct current port is responsible for sweeping the exhaust gas in the center of the cylinder, and the vortex port is responsible for sweeping the exhaust gas on the side of the cylinder wall. The two vortex airflows cooperate with each other to supplement the scavenging, so that the engine can form a relatively complete scavenging surface in the entire scavenging process as much as possible, thereby improving the capture quality and scavenging efficiency; the mixed arrangement air port structure matches the asymmetric air passage, so that the intake resistance of the vortex air ports on both sides is different, and there is an intake resistance difference between the vortex air port and the direct current air port. Multiple airflows with different air resistance and air volume affect each other, and a strong tumble effect in the cylinder can be achieved without adding any tumble-guided upward inclination angle;

[0018] In summary, compared with the single air port structure and the combined air port structure, the mixed air port structure can use the difference in axial displacement between the high-speed airflow and the low-speed airflow to achieve a controllable tumble effect. Under the premise of ensuring the scavenging efficiency and capture quality, it can effectively improve the TKE of the spray combustion stage. The simulation results show that the mixed air port structure keeps the TKE in the cylinder at a high level at all stages of combustion. Compared with the combined air port structure, the total heat release of the mixed air port structure is increased by 9.95%, and the IMEP is increased by 4.91%. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 It is a simplified schematic diagram of the combined arrangement type air port structure in the background technology;

[0020] Figure 2 It is a simplified structural schematic diagram of a two-stroke engine having a mixed arrangement air port structure disclosed in the present invention;

[0021] Figure 3 It is a simplified structural schematic diagram of the mixed arrangement type air port structure disclosed in the present invention;

[0022] Figure 4 for Figure 3 A schematic plan view of the mixed arrangement gas port structure along the -Z direction;

[0023] Figure 5 for Figure 3 A schematic plan view of the mixed arrangement gas port structure along the Z direction;

[0024] Figure 6 It is a structural schematic diagram of a mixed arrangement gas port structure with an advance opening amount;

[0025] Figure 7 It is a schematic diagram of the spray arrangement and the direction of the eddy flow field;

[0026] Figure 8It is a tumble flow field diagram of the mixed arrangement air port structure disclosed in the present invention;

[0027] Fig. 9 is the tumble ratio of the mixed arrangement air port structure disclosed in the present invention;

[0028] Fig.10 A comparison diagram of the crankshaft angle-tumble ratio around the X-axis of the mixed arrangement type air port structure and the combined arrangement type air port structure disclosed in the present invention;

[0029] Fig.11 A comparison diagram of the crankshaft angle-tumble ratio around the Y axis of the mixed arrangement type air port structure and the combined arrangement type air port structure disclosed in the present invention;

[0030] Fig.12 A crankshaft angle-cylinder pressure comparison diagram of the air port structure and the combined arrangement type air port structure disclosed in the present invention;

[0031] Fig.13 A comparison diagram of crankshaft angle-turbulent kinetic energy of the air port structure and the combined arrangement type air port structure disclosed in the present invention;

[0032] Fig.14 A comparison diagram of the crankshaft angle and the total heat release of the air port structure and the combined arrangement type air port structure disclosed in the present invention;

[0033] Fig.15 A comparison diagram of crankshaft angle-heat release rate of the air port structure and the combined arrangement air port structure disclosed in the present invention;

[0034] Fig.16 It is a comparison diagram of the crankshaft angle-air utilization rate of the air port structure and the combined arrangement type air port structure disclosed in the present invention.

[0035] In the figure: 1. Intake piston; 2. Intake system; 21. Forward intake duct; 22. Reverse intake duct; 23. Vortex air port; 24. Straight air port; 25. Upper vortex air duct; 26. Lower vortex air duct; 27. Straight air duct; 3. Cylinder; 4. Exhaust system; 5. Exhaust piston; Gradient expansion angle a; Gradient contraction angle b; S1 upper vortex inclination angle; S2 lower vortex inclination angle; D advance opening amount. DETAILED DESCRIPTION

[0036] The following will be combined with the accompanying drawings of the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only the best embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention;

[0037] It should be noted that the coordinate axes involved in this article take the center of the cylinder as the origin, and the direction along the center axis of the cylinder and toward the intake piston 1 is defined as the Z axis, the X axis is the direction parallel to the intake duct, and the Y axis is perpendicular to the intake duct. The up, down and height directions are described by the orientation or position relationship shown by the Z axis, and the front and rear ends are described by the airflow direction or the opening sequence of the intake piston 1. These terms are mainly used to better describe the present invention and its embodiments, and are not used to limit the indicated devices, elements or components to have a specific orientation, or to be constructed and operated in a specific orientation;

[0038] In addition, some of the above terms may be used to express other meanings in addition to indicating orientation or positional relationship. For example, the terms "on" and "inside" may also be used to express a certain dependency or connection relationship in some cases. For those skilled in the art, the specific meanings of these terms in the present invention can be understood according to specific circumstances.

[0039] This embodiment provides a hybrid arrangement type air port structure for a large-cylinder opposed-piston two-stroke diesel engine, wherein the structure of the large-cylinder opposed-piston two-stroke diesel engine is as follows: Figure 1 As shown, the intake piston 1 and the exhaust piston 5 are arranged opposite to each other at the two end sides of the cylinder 3. The two ends of the cylinder 3 are provided with an intake system 2 and an exhaust system 4. The intake system 2 includes an air port structure and an intake passage. The matching intake passage of the air port structure is an asymmetric air passage. The air port structure is the intake end structure of the intake system 2. Figure 2-Figure 6 As shown, the mixed arrangement air port structure includes a plurality of rectangular air ports arranged on the circumferential wall of the cylinder 3, the plurality of air ports are arranged at equal circumferential angles with the central axis of the cylinder as the center of the array, and the air port height and the coordinates along the lower end of the air port are determined according to the preset intake phase; the air port includes staggered straight flow air ports 24 and vortex air ports 23, the straight flow air ports 24 and the vortex air ports 23 are arranged in the same layer, and the caliber height of the two is the same, so as to ensure a consistent intake time angle;

[0040] The rear end of the direct current air port 24 is connected to the direct current air passage 27. The direct current airflow enters the cylinder 3 to scavenge the center of the cylinder. The direct current air passage 27 adopts a symmetrical tapered air passage, which is conducive to increasing the direct current airflow speed. On the one hand, it ensures the center scavenging effect under the premise of a large inclination angle of the vortex port. On the other hand, it further increases the speed difference in the Z-axis direction after the direct current port and the vortex port enter the cylinder 3, thereby producing a more ideal tumble effect. The tapered angle b is 3°-15°, which is matched and adjusted according to the actual situation of the flow field in the cylinder 3.

[0041] The rear end of the vortex air port 23 is connected to a vortex airway with a rotation direction opposite to the spray injection direction. The vortex airflow generates a scavenging airflow around the Z axis and in the opposite direction to the spray injection direction, which can be scavenged along the outer edge of the cylinder wall of the cylinder 3. In the early stage of combustion, the spray collides with the gas in the cylinder, and the vortex quickly breaks up the oil droplets. At this time, the spray mixing effect is jointly dominated by the vortex and tumble flow breakage. The formation mechanism of the tumble flow is described in detail below; in order to form a wider range of scavenging surfaces on the vortex air port 23, the vortex airway is divided into two layers of double-layer vortex airways with different inclination angles, which are defined from top to bottom as an upper vortex airway 25 and a lower vortex airway 26 according to the direction indicated by the Z axis. The upper vortex airway 25 and the lower vortex airway 26 are evenly distributed through a central section parallel to the XY section, and the height difference between the two is controlled within ±1mm. The upper vortex airway 25 and the lower vortex airway 26 are stacked and connected up and down, share the same vortex air port 23, and the vortex direction is consistent, such as Figure 4 and Figure 5 As shown, the upper vortex inclination angle S1 of the upper vortex airway 25 and the lower vortex inclination angle S2 of the lower vortex airway 26, the vortex inclination angle refers to the angle between the symmetric center plane of the airflow and the radial plane of the center of the air port, the large vortex inclination angle airflow can improve the airflow path, prolong the airflow movement time in the cylinder and thus improve the capture quality, and can improve the intake resistance difference with the direct current port, providing more favorable driving conditions for forming a tumble effect, therefore, the upper vortex inclination angle S1 and the lower vortex inclination angle S2 are both within 20°-30°, the two different inclination angles cooperate with each other up and down to make the scavenging surfaces complement each other, improve the scavenging efficiency and optimize the scavenging effect, but if the angle difference between the two inclination angles is too large, it will produce the entrainment effect of the large inclination layer on the small inclination layer, disturbing the flow field in the cylinder, therefore, the angle difference between the upper vortex inclination angle S1 and the lower vortex inclination angle S2 should be controlled within 0-10°; in addition, the angle size sequence of S1 and S2 has little effect on the scavenging performance and TKE in the cylinder, and is not limited to this;

[0042] like Figure 4 As shown, the upper vortex airway 25 and the lower vortex airway 26 are both gradually expanding airways. The angle between the two sides of the intake duct, i.e., the gradually expanding angle a, makes the airflow more evenly distributed in the radial direction of the cylinder 3, which is beneficial to expand the scavenging surface. At the same time, it can also increase the speed difference of the airflow along the Z axis after entering the cylinder 3 between the straight port and the vortex port, thereby producing a more ideal tumble effect. However, the existence of the gradually expanding angle a will weaken the vortex effect to a certain extent. Therefore, the gradually expanding angle a should be designed to be controlled within the range of 0°-10°.

[0043] The mixed arrangement air port can achieve a higher tumble effect in the cylinder without adding any tumble guide upward angle structure in the straight air passage 27, thereby improving the TKE in the spray combustion stage. This is because there is an intake resistance difference between the intake straight air passage 24 and the vortex air passage 23, resulting in differences in the speed and quality of the airflow coming out of the two different air passages, and then there is a difference in the axial speed of the airflow coming out of different air passages. The high-speed airflow and the low-speed airflow then have differences in axial displacement, and finally a controllable tumble effect is achieved. The cooperation of the gradually contracting straight air passage 27 and the gradually expanding vortex air passage further increases the speed difference between the two, which is conducive to further promoting the formation of strong tumble.

[0044] In addition, in order to further improve the tumble effect, the lower channel surface of the straight air channel 27 has an upward inclination angle to form a straight airflow toward the intake piston 1, that is, an upward airflow toward the Z direction, further increasing the speed difference between the straight airflow and the vortex airflow, and the upward inclination angle is 0-8°;

[0045] A certain advance opening amount D can be set between the vortex air port 23 and the direct current air port 24 to utilize the different characteristics of the two airflows to improve the corresponding performance. The advance opening amount D is the Z-direction distance between the lower edge of the vortex air port 23 and the lower edge of the direct current air port 24.

[0046] Generally, the main purpose is to improve the scavenging quality. During the ventilation process, the vortex air port 23 can be opened in advance to introduce the vortex airflow in advance, so that the combustion exhaust gas near the vortex center is not easy to mix with the fresh air, and at the same time it is conducive to capturing the edge exhaust gas and converging it; therefore, the direct current air port 24 and the vortex air port 23 are staggered along the Z axis, and the vortex air port 23 is located at the front end of the direct current air port 24, and an appropriate advance opening amount D is set between the lower end edge of the vortex air port 23 and the lower end edge of the direct current air port 24, and the advance opening amount D is 0-2.5mm, ensuring the overlap time of the opening of the vortex air port 23 and the direct current air port 24;

[0047] Based on the above structural design, if the central scavenging is insufficient, the improvement of the central scavenging performance should be the primary solution. The central scavenging performance can be alleviated by opening the direct current air port 24 in advance, that is, the direct current air port 24 is offset downward as a whole and arranged at the front end of the vortex air port 23. Similarly, the advance opening amount D is 0-2.5mm. Since the flow path of the direct current in the cylinder is short, too large an advance opening amount D will lead to serious loss of fresh gas.

[0048] In order to reduce the flow resistance of the airway and increase the intake volume, transition fillets are set at the intersections on both sides of the straight airway 27 and the vortex airway connected to the intake duct. The other end of the vortex airway, i.e., the air port end, is only provided with a guide fillet along the vortex direction on the side of the other end along the direction of the vortex airflow to enhance the guide effect of the vortex air port 23, thereby further enhancing the vortex effect. Both the transition fillet and the guide fillet should not be too large, as excessive size will increase the ineffective load of the supercharger and cause pumping air loss. The radius of the transition fillet and the guide fillet is between 0-4mm.

[0049] The air inlet matched with the air port structure of this embodiment is an asymmetric air inlet. Figure 3 In the intake duct structure shown in the figure, the straight air duct 27 and the vortex air duct are connected to the intake ducts on both sides at the nearest side. Since the airflow directions in the intake ducts on both sides are the same, when entering the vortex air ducts with the same rotation direction on both sides, the intake duct with the rotation direction of the vortex is the forward intake duct 21, and the intake duct with the reverse direction of the vortex airflow in the cylinder 3 is the reverse intake duct 22. The intake resistance of the vortex air port 23 connected to the forward intake duct 21 is smaller than that of the vortex air port 23 connected to the reverse intake duct 22. Therefore, there are significant differences in the intake speed and intake amount of the vortex airflow on both sides, which provides more favorable conditions for the formation of the tumble effect, such as Figure 8 As shown, the fresh air flow entering the cylinder 3 is concentrated on the high resistance side. The air flow on the high resistance side flows downward, and interferes with the air flow on the low resistance side to cause tumble flow.

[0050] In order to further demonstrate the technical effect of the mixed arrangement type air outlet of the best embodiment of this invention, the following will be combined with Figure 9-Figure 15 The simulation result graph is described, wherein, in order to facilitate intuitive understanding of the tumble effect of the mixed arrangement air inlet structure, the combined arrangement air inlet structure is used as a comparison model in the simulation, and the calibers of the direct current air inlet 24 and the vortex air inlet 23 of the simulated combined arrangement air inlet structure are respectively consistent with the calibers of the mixed arrangement air inlet, and both adopt asymmetric air ducts, the direct current air inlet 24 of the mixed arrangement air inlet is set with a certain advance opening amount D, and the direct current air duct 27 is not set with an upper inclination angle, the direct current air duct 27 of the combined arrangement air inlet structure is a conventional air duct, and the vortex air duct is consistent with the larger of the upper vortex inclination angle S1 and the lower vortex inclination angle S2;

[0051] Scavenging performance and oil-gas mixing effect are both important indicators of large-bore opposed piston two-stroke engines. Among them, the oil-gas mixing effect is the main factor that directly affects the combustion performance of OP2S. The high TKE in cylinder 3 at the time of spray combustion is conducive to oil-gas mixing. Compared with swirl, increasing the tumble flow in the cylinder is more effective in improving TKE. Figure 9-11It can be seen that during the ventilation process, the tumble ratio of the mixed arrangement air port structure is at a higher level, and the absolute value of the tumble ratio around the X-axis is similar to that of the combined arrangement air port structure, but the absolute value of the tumble ratio around the Y-axis is much higher than that of the combined arrangement air port structure;

[0052] like Figure 12-Figure 15 As shown, in the early stage of combustion, the spray collides with the gas in the cylinder, and the vortex breaks up quickly. At this time, the spray mixing effect is dominated by the vortex and tumble breakup. Therefore, the combustion rate of the combined arrangement air port structure with a larger vortex in the early stage of combustion is slightly higher than that of the mixed arrangement air port structure; in the middle and late stages of combustion, the vortex ratio is greatly reduced due to the vortex breakup. At this time, the tumble ratio is still at a high level and continues to break up to increase the TKE in the cylinder. The spray mixing effect in the middle and late stages of combustion is mainly dominated by the tumble effect. Therefore, the heat release rate of the mixed arrangement air port structure in the middle and late stages of combustion is significantly higher than that of the combined arrangement air port structure.

[0053] In summary, the strong tumble effect produced by the mixed arrangement air port structure enables the TKE in the middle and late stages of combustion to be replenished in time, so that a relatively high heat release rate is still maintained in the middle and late stages of combustion; in general, the total heat release of the mixed arrangement air port structure is significantly higher than that of the combined arrangement air port structure;

[0054] Air utilization is an intuitive parameter that reflects the oil-gas mixing effect. In the simulation, the larger its value is, the greater the percentage of the combustible equivalence ratio area in the total area. The definition of air utilization is: at a certain crankshaft angle, the percentage of the volume of the combustion chamber space with excess air coefficient λ between [0.5,1.5] (i.e., the potential combustible range) in the current cylinder total volume.

[0055]

[0056] Among them, V i is the volume of the grid with 0.5≤λ≤1.5;

[0057] V total is the total volume of gas in the cylinder;

[0058] like Fig.16 As shown, the air utilization rates of the mixed arrangement air port structure and the combined arrangement air port structure are similar in the early stage of combustion. However, due to the weak tumble effect formed by the combined arrangement air port structure, the TKE in the cylinder cannot be replenished in time in the middle and late stages of combustion. At around 385°CA, the air utilization rate of the mixed arrangement air port structure begins to be higher than that of the combined arrangement air port structure, and the gap gradually widens afterwards.

[0059] Therefore, in summary, the hybrid arrangement air inlet structure produces an unexpectedly strong tumble effect, which keeps the TKE at a high level at all stages of combustion. Compared with the combined arrangement air inlet structure, the total heat release of the hybrid arrangement air inlet structure is increased by 9.95%, and the IMEP is increased by 4.91%.

[0060] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A hybrid arrangement type air port structure for a large-diameter opposed-piston two-stroke diesel engine, characterized in that: It comprises a plurality of air ports which are uniformly arranged in a ring shape on the wall surface of the cylinder along the central axis thereof, wherein the air ports comprise staggered straight flow ports and vortex ports, the straight flow ports and the vortex ports have the same aperture height; the straight flow ports are connected to straight flow passages, the vortex ports are connected to vortex passages, the straight flow passages and the vortex passages are connected to the intake passages on both sides on the nearest sides, and the intake passages matched with the mixed arrangement air port structure are asymmetric air passages; the vortex air passages are double-layer vortex air passages which are connected in an upper and lower stacked manner, that is, the vortex air passages are equally divided into an upper vortex air passage and a lower vortex air passage along the XY section, and the upper vortex inclination angle S1 of the upper vortex air passage is different from the lower vortex inclination angle S2 of the lower vortex air passage.

2. The hybrid arrangement type air port structure for a large cylinder diameter opposed piston two-stroke diesel engine according to claim 1, characterized in that: The angular difference between the upper vortex inclination angle S1 and the lower vortex inclination angle S2 is within 0-10°, and the upper vortex inclination angle S1 and the lower vortex inclination angle S2 are both within 20°-30°.

3. The hybrid arrangement gas port structure for a large-diameter opposed-piston two-stroke diesel engine according to claim 2, characterized in that: The upper vortex airway and the lower vortex airway are both gradually expanding airways, and the gradually expanding angles thereof are 0°-10°.

4. The hybrid arrangement type air port structure for a large cylinder diameter opposed piston two-stroke diesel engine according to claim 1, characterized in that: The straight flow airway is a tapered airway with a tapering angle of 3°-15°.

5. The hybrid arrangement type air port structure for a large cylinder diameter opposed piston two-stroke diesel engine according to claim 4, characterized in that: The lower channel surface of the straight air channel has an upward inclination angle for further guiding the tumble flow, and the upward inclination angle is 0-8°.

6. The hybrid arrangement gas port structure for a large-diameter opposed-piston two-stroke diesel engine according to claim 1, characterized in that: The direct current air port and the vortex air port are staggered along the Z axis, that is, there is an early opening amount D between the lower end edge of the direct current air port and the lower end edge of the vortex air port.

7. The hybrid arrangement type air port structure for a large cylinder diameter opposed piston two-stroke diesel engine according to claim 6, characterized in that: The vortex air port is located at the front end of the straight air port, and is used to open the vortex airflow in advance to improve the scavenging quality. The advance opening amount D is 0-2.5mm.

8. The hybrid arrangement type air port structure for a large-diameter opposed-piston two-stroke diesel engine according to claim 6, characterized in that: The direct current air port is located at the front end of the vortex air port, and is used to open the direct current airflow in advance to improve the insufficient central scavenging, and the advance opening amount D is 0-2.5mm.

9. The hybrid arrangement type air port structure for a large-diameter opposed-piston two-stroke diesel engine according to claim 8, characterized in that: Transition fillets are arranged on both sides of one end of the straight airway and the vortex airway connected to the air inlet, and a guide fillet is arranged on one side of the other end of the vortex airway along the vortex direction.

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