A high uniformity mixing system for a natural gas engine

Abstract

The utility model discloses a high uniformity mixing system for natural gas engine, including air inlet pipe, mixer and air inlet connector, air inlet pipe includes air inlet pipe body and total air inlet interface, and total air inlet interface is located in the middle part of air inlet pipe body transversely, air inlet connector is located between mixer air outlet and total air inlet interface, and mixer is located below total air inlet interface, and mixer air outlet is located in the right side, total air inlet interface projects on the upper end of air inlet pipe body and is located in the front half of air inlet pipe body longitudinally, and the opening of total air inlet interface faces forward, air inlet connector air outlet interface is opposite to total air inlet interface, and the half of air inlet connector pipe body is 150 with horizontal angle, and the bottom wall of total air inlet interface and air inlet connector air outlet interface inner chamber is respectively first camber and second camber that inwards convex, first camber and second camber are roundly smooth transition, and first camber is inclined downward, the utility model weakens the airflow rotation intensity in air inlet manifold, and makes the airflow movement in air passage more smooth.

Description

Technical Field

[0001] This utility model relates to the field of engine technology, and in particular to a highly uniform mixing system for natural gas engines. Background Technology

[0002] With the rapid development of the natural gas engine market and its expanding application scenarios, the number of related models on the market is increasing, and the industry is placing increasingly stringent requirements on the engine's thermal efficiency, combustion performance, and emission standards. Intake air-fuel mixture uniformity, as a core factor affecting the combustion efficiency of natural gas engines, directly determines the completeness and stability of fuel combustion. A uniform gas-fuel mixture ensures consistent combustion conditions in each cylinder, effectively improving combustion efficiency, reducing pollutant emissions, and further optimizing thermal efficiency. Conversely, if the mixing ratio of fuel gas, air, and exhaust gas in the gas-fuel mixture is unbalanced, or if there are differences in the intake components of each cylinder, it will directly disrupt combustion stability. Currently, natural gas engines commonly employ exhaust gas recirculation (EGR) technology to meet stringent emission requirements, but how to ensure that the recirculated exhaust gas is uniformly mixed with fuel gas and air and evenly distributed to each cylinder has become a key challenge restricting engine performance improvement.

[0003] In the intake system of a natural gas engine, the intake component connecting the mixer and the intake manifold is the core element ensuring uniform mixing. Current technologies still have room for optimization in the design of this component, making it difficult to fully meet the requirements for highly uniform mixing. While existing mixing systems promote thorough mixing of fuel gas, air, and recirculated exhaust gas, they often struggle to maintain airflow stability, easily leading to mixture stratification or localized uneven concentration, affecting combustion completeness. The structural design of the intake path directly impacts airflow conditions, resulting in differences in the composition and turbulence intensity of the mixture obtained by each cylinder, thus causing inconsistent combustion. These problems ultimately lead to fluctuations in engine power output, increased fuel consumption, and even malfunctions such as knocking and misfires, failing to meet the current industry's core requirements for high thermal efficiency, low emissions, and high reliability in natural gas engines.

[0004] The above background information is provided only to aid in understanding the concept and technical solution of this utility model. It does not necessarily belong to the prior art of this patent application. In the absence of clear evidence that the above information was disclosed on the filing date of this patent application, the above background information should not be used to evaluate the novelty and inventiveness of this application. Utility Model Content

[0005] The purpose of this invention is to propose a highly uniform mixing system for natural gas engines, in order to solve the technical problems existing in the prior art, such as difficulty in controlling the rotation intensity of the mixed gas, excessive differences in the swirl ratio and flow coefficient of each cylinder, insufficient mixing uniformity, which in turn leads to unstable combustion, low thermal efficiency, and excessive emissions in the engine.

[0006] Therefore, this utility model proposes a highly uniform mixing system for natural gas engines.

[0007] Preferably, the present invention may also have the following technical features:

[0008] A highly uniform mixing system for a natural gas engine includes an intake pipe, a mixer, and an intake connector; the intake pipe includes an intake pipe body and a main intake port, the main intake port being located in the middle of the transverse direction of the intake pipe body; the intake connector is located between the outlet of the mixer and the main intake port.

[0009] The mixer is located below the main air intake, and the mixer outlet is located on the right side;

[0010] The main air intake interface protrudes from the upper end of the air intake pipe body and is located in the front half of the longitudinal direction of the air intake pipe body, with the opening of the main air intake interface facing forward.

[0011] The air intake pipe outlet is positioned opposite to the main air intake port, and the upper half of the air intake pipe has an angle α of 150° with the horizontal.

[0012] The bottom walls of the inner cavities of the main air intake port and the air intake pipe outlet port are respectively an inwardly convex first arc surface and a second arc surface, with the first arc surface and the second arc surface smoothly transitioning, and the first arc surface tilting downward.

[0013] Preferably, the air intake pipe includes a first bend and a second bend arranged vertically, and the internal cavity at the connection between the first bend and the second bend is provided with a spoiler. The spoiler is arranged at the lower part, at 1 / 3 of the total length of the air intake pipe.

[0014] Preferably, the inner diameters of the first bend and the second bend are the same, and the first bend is sleeved on the outside of the second bend.

[0015] Preferably, a first groove is provided at the top of the first bend near the top of the second bend, and the spoiler is disposed in the first groove.

[0016] Preferably, the air intake pipe outlet is fixed to the main air intake port via a flange connection.

[0017] Preferably, the radius of curvature of the first arc surface is the same as the radius of curvature of the second arc surface.

[0018] Preferably, the mixer is used to mix fuel gas, air and exhaust gas after combustion, and the outlet of the mixer is connected to the inlet of the inlet pipe.

[0019] Preferably, the mixer is a Venturi mixer.

[0020] The beneficial effects of this utility model compared with the prior art include:

[0021] 1. This utility model, by having the main intake port protrude from the upper end of the intake pipe body, located in the longitudinal front half with its opening facing forward, and combined with the 150° inclination of the upper half of the intake pipe to the horizontal, allows the air-fuel mixture to enter the intake pipe from the front at an appropriate angle. After being blocked by the end face of the intake pipe, it naturally disperses and flows downward to the intake ports of each cylinder. This design effectively reduces the airflow rotation intensity in the main intake pipe of traditional intake structures, avoiding mixture stratification caused by excessive rotation. Furthermore, by symmetricalizing the airflow path, it strictly controls the vortex ratio difference between the cylinders on the left and right sides of the main intake port within a reasonable range of ≤10%, while making the airflow movement within the air passage smoother and reducing local turbulence and flow disturbance.

[0022] 2. The first and second arc surfaces of the inner convex shape on the bottom wall of the main air intake interface and the air intake pipe outlet interface of this utility model achieve a seamless and smooth transition. The downward tilt of the first arc surface provides a smooth guide for the airflow, avoids the flow separation phenomenon caused by the structural change at the docking point, and makes the airflow turn more gently.

[0023] 3. By setting the spoiler lower and precisely at 1 / 3 of the length of the intake pipe, this utility model avoids the problems of insufficient mixing path and inadequate mixing caused by a spoiler that is set "higher" and solves the defects of flow attenuation and weakened turbulence effect caused by a spoiler that is set too "lower". This allows the premixed gas to obtain sufficient rotational mixing stroke after flowing through the spoiler, effectively breaking the gas stratification phenomenon, improving the uniformity of mixing of fuel gas, air and combustion exhaust gas, and ensuring that the intake components of each cylinder are consistent. Attached Figure Description

[0024] Figure 1 This is a front view of a specific embodiment of the present utility model.

[0025] Figure 2 This utility model is based on Figure 1 A sectional view cut at point CC.

[0026] Figure 3 This is a left view of a specific embodiment of the present utility model.

[0027] Figure 4 This utility model is based on Figure 3 A sectional view cut at EE.

[0028] Explanation of reference numerals in the attached drawings: 1-Intake pipe; 11-Intake pipe body; 12-Main intake port; 13-First arc surface; 2-Mixer; 21-Mixer outlet; 3-Intake pipe connector; 31-Intake pipe outlet; 32-Intake pipe intake port; 33-Second arc surface; 34-First bend; 35-Second bend; 4-Breaker. Detailed Implementation

[0029] The present invention will now be described in further detail with reference to specific embodiments and the accompanying drawings. It should be emphasized that the following description is merely exemplary and is not intended to limit the scope and application of the present invention.

[0030] Non-limiting and non-exclusive embodiments will be described with reference to the following figures, wherein the same reference numerals denote the same parts unless otherwise specifically stated.

[0031] A highly homogeneous mixing system for natural gas engines, such as Figures 1-4 As shown, it includes an intake pipe 1, a mixer 2, and an intake connector 3. The intake pipe 1 includes an intake pipe body 11 and a main intake port 12. The main intake port 12 is located in the middle of the intake pipe body 11 laterally. The intake connector 3 is located between the mixer outlet 21 and the main intake port 12, forming a gas delivery path of "mixer 2 → intake connector 3 → intake pipe 1 → each cylinder of the engine".

[0032] Specifically, the mixer 2 is located below the main air intake port 12, and the mixer outlet 21 is located on the right side. This layout allows the mixed air output by the mixer 2 to flow to the intake pipe 3 along the shortest path, reducing airflow loss caused by pipe bends. The main air intake port 12 protrudes from the upper end of the intake pipe body 11 and is specifically located in the front half of the longitudinal direction of the intake pipe body 11 (that is, the first 1 / 2 region of the total longitudinal length of the intake pipe body 11). The opening of the main air intake port 12 is horizontally facing forward, ensuring that the mixed air enters directly from the front. The intake pipe outlet 31 is arranged opposite to the main air intake port 12. The upper half of the pipe body is referenced by its central axis (the central axis of the upper half of the pipe body of the air intake pipe 3 in this embodiment is close to a straight line, and is regarded as a straight line here) and the angle α between it and the horizontal plane is precisely set to 150°. This angle avoids the airflow from rushing and becoming turbulent due to the small angle, and also prevents the air intake resistance from increasing due to the large angle. The bottom walls of the inner cavities of the main air intake port 12 and the air intake pipe outlet port 31 are respectively processed into an inwardly convex first arc surface 13 and a second arc surface 33. The first arc surface 13 and the second arc surface 33 are seamlessly and smoothly transitioned along the airflow direction, and the first arc surface 13 is inclined downward at an angle of 30-45°. The protruding design of the main intake port 12, in conjunction with the forward opening direction, provides a clear injection guide for the air-fuel mixture. The 150° pipe angle allows the air-fuel mixture to enter smoothly. Combined with the downward-sloping inward convex first arc surface, a continuous flow channel of "injection-blocking-guiding" is formed. This allows the air-fuel mixture to enter from the front, be blocked by the end face of the intake pipe 1, and naturally disperse to both sides and flow down along the first arc surface 13 to the intake ports of each cylinder. This effectively reduces the airflow rotation intensity in the main intake pipe in the traditional intake structure. It not only makes the airflow movement in the intake channel smoother and reduces local turbulence, but also controls the vortex ratio difference between the cylinders on the left and right sides of the main intake port within a reasonable range of ≤10% through the symmetrical airflow path, ensuring consistent combustion conditions in each cylinder.

[0033] In some examples of this embodiment, such as Figures 2-4As shown, the intake pipe 3 includes a first bend 34 and a second bend 35 arranged vertically. A spoiler 4 is provided in the internal cavity at the connection between the first bend 34 and the second bend 35. The spoiler 4 is positioned lower and precisely at 1 / 3 of the total length of the intake pipe 3 (the total length of the intake pipe 3 is defined as the straight-line distance from the end face of the intake port 32 to the end face of the exhaust port 31). The inner diameters of the first bend 34 and the second bend 35 are the same. The first bend 34 is fitted onto the outside of the second bend 35 with an interference fit, ensuring no steps or abrupt changes in cross-section at the joint. A ring-shaped first groove is formed on the inner wall of the first bend 34 near the top of the second bend 35. The width of the first groove matches the thickness of the spoiler 4 (the groove width is 0.5-1mm larger than the thickness of the spoiler 4). The spoiler 4 is embedded in the first groove and can be fixed by welding or interference fit to prevent displacement when gas flows through it. The first bend 34 and the second bend 35 have the same inner diameter and are fitted together, preventing airflow separation due to cross-sectional changes at the connection point. The diffuser 4 is installed in the first groove for precise positioning. Its lower position at 1 / 3 of the way through multiple tests has been verified to balance mixing effect and flow stability. The diffuser 4 pre-turbulents the mixture at 1 / 3 of the way through the intake pipe 3, breaking the stratification of fuel gas, air, and combustion exhaust gas, allowing the mixture to be further uniformly mixed in the subsequent flow channel. At the same time, it avoids the problems of an excessively short mixing path and insufficient mixing caused by the diffuser 4 being positioned too high, or the flow attenuation caused by the diffuser 4 being positioned too low, thus significantly improving the uniformity of the mixture components.

[0034] Specifically, such as Figures 1-3 The intake manifold outlet 31 and the main intake manifold 12 are fixed together by a flange. A high-temperature resistant sealing gasket is provided on the mating face of the flange. Four to six bolt holes are evenly distributed around the flange circumference, and a sealed connection is achieved by tightening the bolts. This flange connection method allows for easy disassembly. The sealing gasket effectively prevents leakage of the high-pressure mixture, and the even distribution of bolts ensures balanced stress on the mating surface. This solves the problem of gas leakage at the joint, avoids imbalance in the mixture ratio due to leakage, ensures the stability of the connection structure, adapts to the vibration environment during engine operation, and reduces maintenance costs.

[0035] Specifically, the radius of curvature of the first arc surface 13 is the same as that of the second arc surface 33. The radius of curvature can be adjusted according to the inner diameter of the tube. The design of the same radius of curvature makes the transition between the first arc surface 13 and the second arc surface 33 smoother. When the airflow passes through, there is no abrupt turn. It can turn naturally along the arc surface, which minimizes the pressure loss of the airflow at the docking point, avoids the phenomenon of airflow separation, and further optimizes the airflow distribution.

[0036] Specifically, mixer 2 is used to fully premix the fuel gas, air, and exhaust gas after combustion. The mixer outlet 21 is welded or flanged to the air inlet interface 32 of the air inlet pipe to ensure leak-free delivery of the mixed gas. Mixer 2 is a Venturi mixer with a Venturi tube core structure inside. It uses high-speed airflow to generate negative pressure, drawing in the fuel gas and exhaust gas for preliminary mixing. The Venturi mixer achieves efficient premixing based on fluid mechanics principles, requiring no additional power drive. It is suitable for the air intake system requirements of natural gas engines and can quickly premix the three media to form a homogeneous premixed gas, laying the foundation for secondary turbulent mixing in the air inlet pipe. At the same time, the Venturi structure has high mixing efficiency and low resistance, avoiding the problem of excessively high or low local concentrations of mixed gas components, thus improving the completeness of subsequent combustion.

[0037] In this embodiment, the gas flow and mixing process is as follows: Gas fuel, air, and exhaust gas from combustion enter the Venturi mixer. After thorough pre-mixing via the Venturi effect, the mixture flows out from the mixer outlet 21 on the right side of the mixer and enters the second bend 35 of the inlet pipe 3. The mixed gas flows upward along the second bend 35. When it passes the baffle 4 at the connection between the first bend 34 and the second bend 35, it generates a rotating flow pattern under the guidance of the impeller-shaped baffle 4, achieving secondary mixing and breaking the stratification phenomenon. Subsequently, the mixed gas flows upward along the inlet pipe 3. The upper half of the air connector 3, inclined at 150°, flows out from the air outlet 31 of the air inlet connector and enters the air inlet pipe 1 through the flange-connected main air inlet 12. Under the obstruction of the end face of the main air inlet 12, the mixed air flows downward along the smooth transition channel between the second arc surface 33 and the first arc surface 13, and diffuses smoothly towards the middle of the transverse direction of the air inlet pipe body 11. Finally, it is evenly distributed to the air inlets of each cylinder on the left and right sides, ensuring that each cylinder obtains a mixed air with consistent composition, balanced flow, and stable vortex ratio.

[0038] It should be noted that the scope of protection of this utility model is not limited to the above embodiments. For example, the total length of the intake pipe can be flexibly adjusted according to the requirements of the engine model. As long as the spoiler is located at 1 / 3 of its length, the corresponding mixing effect can be achieved. The curvature radius of the first arc and the second arc can be adapted and adjusted according to the inner diameter of the pipe. They do not have to be exactly the same. As long as a smooth transition can be achieved and the rotation intensity of the airflow can be weakened, it is acceptable. The number of impeller blades of the spoiler can be adjusted according to the mixing requirements. 4 to 8 blades can be selected. Its core function is to guide the gas rotation and mixing. The adjustment of the number of blades does not affect the scope of protection of this utility model. The fixing method of the first bend and the second bend can be selected according to the actual assembly requirements, such as welding or bolt connection, as long as the sealing performance and connection stability can be guaranteed.

[0039] Those skilled in the art will recognize that numerous variations are possible with respect to the above description, and the embodiments and figures are merely for describing one or more specific implementations.

[0040] Although exemplary embodiments of the present invention have been described and illustrated, those skilled in the art will understand that various changes and substitutions can be made thereto without departing from the spirit of the present invention. Furthermore, many modifications can be made to adapt specific situations to the doctrine of the present invention without departing from the central concept of the present invention described herein. Therefore, the present invention is not limited to the specific embodiments disclosed herein, but may include all embodiments and equivalents that fall within the scope of the present invention.

Claims

1. A high-uniformity mixing system for a natural gas engine, comprising an intake pipe, a mixer, and an intake connector; the intake pipe includes an intake pipe body and a main intake port, the main intake port being located in the transverse middle of the intake pipe body; the intake connector is located between the outlet of the mixer and the main intake port; characterized in that: The mixer is located below the main air intake, and the mixer outlet is located on the right side; The main air intake interface protrudes from the upper end of the air intake pipe body and is located in the front half of the longitudinal direction of the air intake pipe body, with the opening of the main air intake interface facing forward. The air intake pipe outlet is positioned opposite to the main air intake port, and the upper half of the air intake pipe has an angle α of 150° with the horizontal. The bottom walls of the inner cavities of the main air intake port and the air intake pipe outlet port are respectively an inwardly convex first arc surface and a second arc surface, with the first arc surface and the second arc surface smoothly transitioning, and the first arc surface tilting downward.

2. The highly uniform mixing system for a natural gas engine according to claim 1, characterized in that, The intake pipe includes a first bend and a second bend arranged vertically. The internal cavity at the connection between the first bend and the second bend is provided with a spoiler. The spoiler is located at the lower end, at 1 / 3 of the total length of the intake pipe.

3. The highly uniform mixing system for a natural gas engine according to claim 2, characterized in that, The first bend and the second bend have the same inner diameter, and the first bend is fitted over the second bend.

4. The highly uniform mixing system for a natural gas engine according to claim 3, characterized in that, A first groove is provided at the top of the first bend near the second bend, and the spoiler is disposed in the first groove.

5. The highly uniform mixing system for a natural gas engine according to claim 1, characterized in that, The air intake pipe outlet is fixed to the main air intake port via a flange connection.

6. The highly uniform mixing system for a natural gas engine according to claim 1, characterized in that, The radius of curvature of the first arc surface is the same as the radius of curvature of the second arc surface.

7. The highly uniform mixing system for a natural gas engine according to claim 1, characterized in that, The mixer is used to mix fuel gas, air and exhaust gas after combustion, and the outlet of the mixer is connected to the inlet of the inlet pipe.

8. The highly uniform mixing system for a natural gas engine according to claim 1, characterized in that, The mixer is a Venturi mixer.

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