CN116263136A

CN116263136A - Gas mixer

Info

Publication number: CN116263136A
Application number: CN202111516833.XA
Authority: CN
Inventors: 胡志权; 张文博; 张潇; 樊于朝; 宋莎莎; 董铭
Original assignee: Shaanxi Heavy Duty Automobile Co Ltd
Current assignee: Shaanxi Heavy Duty Automobile Co Ltd
Priority date: 2021-12-13
Filing date: 2021-12-13
Publication date: 2023-06-16

Abstract

The present invention provides a gas mixer comprising: the venturi tube is arranged in the outer shell, a pressure stabilizing cavity is formed between the venturi tube and the outer shell, an air inlet is further formed in the outer shell and communicated with the pressure stabilizing cavity, a plurality of air nozzles with the same size are formed in the wall of the venturi tube and communicated with the pressure stabilizing cavity, the geometric centers of the air nozzles are on the same circle, and the intervals among the air nozzles are equal. The invention effectively solves the problem that the natural gas mixer in the prior art can not effectively mix air and natural gas.

Description

Gas mixer

Technical Field

The invention relates to the technical field of natural gas engines of commercial vehicles, in particular to a gas mixer.

Technical Field

At present, the development of clean energy source has become a national strategy, and natural gas is increasingly applied to the field of engines with the characteristics of cleanness, safety, high efficiency, large storage capacity and excellent emission performance. In natural gas engine systems, the natural gas mixer is used as a core component, which determines the performance of the engine to a large extent. The traditional natural gas engine is characterized in that natural gas is directly injected into an air inlet pipe of the engine, or the natural gas is injected into an air inlet pipeline by using a static mixer, so that the natural gas and air are mixed in the air inlet pipeline to form mixed gas, and the mixed gas enters each cylinder through an air inlet manifold. When natural gas and air are well mixed, the natural gas concentration in each cylinder is almost the same, although there is a difference in the charge efficiency of each cylinder that is large and small. Because the ignition advance angle of each cylinder is calibrated to be the same by the engine ECU, under the determined working condition, the ignition time of each cylinder spark plug is the same. If the natural gas and the air are unevenly mixed, the natural gas of some cylinders is thicker, and the natural gas of some cylinders is thinner. For a cylinder with thicker natural gas, on the premise that the ignition advance angle is not changed, the knocking tendency of the cylinder is increased, the risk of piston top melting is increased, and particularly, when the engine runs for a long time under a heavy-load working condition. At present, the gas inlet way adopts the gas inlet way mixing, and the uniform mixing is difficult to realize because of the shorter gas passage, and the mixing uniformity is difficult to ensure. The research shows that the combustion effect of the natural gas engine mainly depends on the uniformity of the mixed gas formed by air and natural gas, and the higher the uniformity of the mixed gas is, the more stable the engine is combusted, and the better the dynamic property, economy and pollutant emission effect are. Therefore, in order to improve the mixing effect of natural gas and air, improve the mixing uniformity of natural gas and air, reduce the risk of knocking of an engine, and improve the reliability of the engine, it is necessary to design a mixer having good mixing performance.

The mixer is a device for mixing natural gas with air, and has the main function of well mixing the natural gas with the air, providing uniformly mixed combustion gas for an engine and well organizing combustion in the engine. At present, natural gas engine mixers are divided into two types, namely a proportional mixer and a venturi mixer. The diaphragm and the spring are arranged in the proportional mixer, so that the air inflow of the natural gas can be automatically regulated according to the pressure and the flow of the air, and the proportional mixer has a complex structure, high cost and high price. The venturi mixer has a simple structure and low price, and is increasingly applied to a natural gas engine of a closed-loop control system, and the structure of the venturi mixer is shown in fig. 1. As shown in fig. 2, which is a schematic diagram of the installation position of the natural gas mixer, the natural gas mixer is currently installed on the air inlet pipeline of the engine, after the throttle valve and before the air inlet manifold, and the length of the air inlet pipeline is limited by space arrangement, so that the natural gas mixer cannot be designed to be long enough for effectively mixing air and natural gas.

Disclosure of Invention

The invention aims at overcoming the defects of the prior art, thereby providing a gas mixer, and solving the problem that the natural gas mixer in the prior art can not effectively mix air and natural gas.

The invention is realized by adopting the following technical scheme:

a gas mixer, comprising: the venturi tube is arranged in the outer shell, a pressure stabilizing cavity is formed between the venturi tube and the outer shell, an air inlet is further formed in the outer shell and communicated with the pressure stabilizing cavity, a plurality of air nozzles with the same size are formed in the wall of the venturi tube and communicated with the pressure stabilizing cavity, the geometric centers of the air nozzles are on the same circle, and the intervals among the air nozzles are equal.

Further, the air nozzle is arranged on the contraction section of the air inlet end of the venturi tube.

Further, the air nozzle is arranged on the throat section of the venturi tube.

Further, the opening direction of the air nozzle and the normal line of the inner wall of the venturi tube, which passes through the geometric center of the air nozzle, form a certain included angle.

Furthermore, connecting flanges are arranged at two ends of the outer shell.

Further, the included angle is 30 °.

Compared with the prior art, the invention has the following beneficial technical effects:

according to the invention, the interior of the mixer is provided with the venturi tube, the pressure stabilizing cavity is arranged between the venturi tube and the outer shell, and the air jet opening is formed in the tube wall of the air inlet section of the venturi tube, so that when air flows from the air inlet end of the venturi tube to the throat, the air flow speed is increased, the air pressure is reduced, and a larger pressure difference is formed between the air flow speed and the natural gas in the pressure stabilizing cavity, so that the natural gas jetted from the air jet opening is driven to be fully mixed, and the uniformity and the fusion degree of the air flow speed are improved; the jet direction of natural gas can be changed by setting the jet orifice to a certain deflection angle, so that the high-pressure natural gas flow is continuously mixed with air in the process of penetrating through the air, the energy of the high-pressure natural gas flow is transferred to the air, the air is driven to move together, the radial speed of the air flow is greatly improved after the natural gas and the air are mixed, the mixed gas flow rotates around the axis of the Venturi tube, and meanwhile, the mixed gas flow has a larger axial speed, so that the gas flow has a spiral advancing state, and the mixing uniformity of the natural gas and the air is greatly promoted by adopting the radial and axial compound mixing mode.

Drawings

FIG. 1 is a schematic perspective view of a first embodiment of the present invention;

FIG. 2 is a schematic perspective sectional view of a first embodiment of the present invention;

FIG. 3 is a schematic cross-sectional view of a first embodiment of the present invention;

FIG. 4 is a schematic perspective view of a second embodiment of the present invention;

FIG. 5 is a schematic perspective sectional view of a second embodiment of the present invention;

FIG. 6 is a schematic cross-sectional view of a second embodiment of the present invention;

FIG. 7 is a schematic diagram of the natural gas and mixed gas flow direction according to the present invention;

FIG. 8 is an abstract view of the direction of opening of the gas nozzle according to the present invention;

fig. 9 is a schematic view of the installation position of the present invention.

Reference numerals illustrate:

1-shell, 2-air inlet, 3-venturi, 301-air jet, 4-steady voltage cavity, 5-ring flange.

Detailed Description

In order that the above-recited objects, features and advantages of the present invention will be more clearly understood, a more particular description of the invention will be rendered by reference to specific embodiments thereof which are illustrated in the appended drawings. It should be noted that, in the case of no conflict, the embodiments of the present application and the features in the embodiments may be combined with each other. In the description of the present invention, it should also be noted that, unless explicitly specified and limited otherwise, the terms "disposed," "mounted," and "connected" are to be construed broadly, and may be, for example, fixedly connected, detachably connected, or integrally connected; can be mechanically or electrically connected; can be directly connected or indirectly connected through an intermediate medium, and can be communication between two elements. The specific meaning of the above terms in the present invention can be understood by those of ordinary skill in the art according to the specific circumstances.

Example 1:

FIG. 1 is a schematic perspective view of a first embodiment of the present invention; FIG. 2 is a schematic perspective sectional view of a first embodiment of the present invention; FIG. 3 is a schematic cross-sectional view of a first embodiment of the present invention; as shown in fig. 1-3, a gas mixer comprising: the venturi tube is arranged in the outer shell, an annular pressure stabilizing cavity 4 is formed between the venturi tube and the outer shell, an air inlet 2 is further formed in the outer shell and is communicated with the pressure stabilizing cavity, a plurality of air nozzles 301 with the same size are formed in the wall of the venturi tube and are communicated with the pressure stabilizing cavity, the geometric centers of the air nozzles are arranged on the same inner wall circle, the space between the air nozzles is equal, in the embodiment, the number of the air nozzles is 12 in total, the air nozzles are arranged at equal intervals in the circumferential direction, in the embodiment, the air nozzles are formed in the contraction section of the air inlet end of the venturi tube, the forming direction of the air nozzles, namely the forming direction of the air nozzles is 30 degrees with the normal line of the geometric center of the air nozzle, which is rounded on the inner wall of the venturi tube. FIG. 8 is an abstract view of the direction of opening of the gas nozzle according to the present invention; as shown in FIG. 8, a circleO represents the circle of the inner wall of the venturi tube, the point c represents the geometric center of an air nozzle, and the straight line N represents the normal line of the point c on the original O, so the vector is

Is the injection direction of the injection ports 301, in this case, +.>

The angle with the normal N is 30 °, i.e. angle a=30°.

The flange plates 5 are arranged at the two ends of the outer shell and are used for being connected with the air inlet pipe and the air outlet pipe, and the mixer and the throttle valve can be directly integrated in the actual manufacturing process, so that the complexity of the system is effectively reduced.

The engine air inlet enters from the left side of the mixer, passes through the venturi tube of the mixer, and because the mixer adopts a venturi tube structure, the flow velocity increases and the pressure decreases when the air flows through the throat, and the flow velocity decreases and the pressure increases after the air passes through the throat at the necking position. The high-pressure natural gas enters the pressure-stabilizing cavity through the gas inlet, the pressure-stabilizing cavity is formed by the outer shell of the mixer and the venturi wall, the natural gas pressure-stabilizing cavity has a larger space, the entering natural gas can form stable natural gas pressure, the annular internal surface structure of the pressure-stabilizing cavity enables the natural gas to be distributed more uniformly along the wall surface of the inner cavity, the pressure uniformity of the inner part of the cavity is effectively ensured, the flow speed uniformity of the flowing natural gas spraying port is ensured, and the mixing uniformity of the natural gas and the air is improved. The air nozzles are uniformly distributed along the circumferential direction of the Venturi tube, the size specifications of the air nozzles are the same, and according to the different use amount of natural gas and the different injection pressure of the natural gas, the actual requirements can be met by designing the number of different air nozzles.

The natural gas forms stable pressure in the natural gas pressure-stabilizing cavity, and the air flow pressure is reduced when the air passes through the venturi tube, so that the jet pressure of the natural gas and the air pressure difference are increased, the penetrating power of the natural gas jet air flow is improved, the natural gas jet air flow can be jetted to the deep part of the air flow, the mixing of the natural gas and the air is promoted, and the mixing uniformity of the natural gas and the air is improved.

Because the incidence angle of the natural gas jet port and the circumference normal line of the inner wall of the venturi tube have a certain included angle, when the natural gas jet flow is jetted into the air from the natural gas jet port, the high-pressure natural gas flow is continuously mixed with the air in the process of penetrating the air, and the energy of the high-pressure natural gas flow is transferred to the air, so that the air is driven to move together, and after the natural gas and the air are mixed, the radial speed of the mixed gas flow is greatly improved, so that the mixed gas flow rotates around the axis of the churn tube. The mixing air flow has a larger axial speed, and has a certain radial speed under the action of the mixer, so that the air flow has a spiral advancing state, and the radial and axial compound mixing mode greatly promotes the mixing uniformity of the natural gas and the air. After better mixing is formed at the front end of the air inlet of the throat, a longer mixing cavity is also needed at the rear end of the air outlet of the throat to fully develop the rotary air flow formed before the throat, so that the mixing of the air flow is promoted, and the uniformity of the mixed air flow is improved. The mixing chamber is also referred to as the exit expansion end of the venturi.

Example 2:

FIG. 4 is a schematic perspective view of a second embodiment of the present invention; FIG. 5 is a schematic perspective sectional view of a second embodiment of the present invention; FIG. 6 is a schematic cross-sectional view of a second embodiment of the present invention; as shown in fig. 4-6, based on the technical scheme in embodiment 1, the air jet 301 is opened at the throat of the venturi tube, the air inlet 2 is arranged right above the air jet 301 and is communicated with the pressure stabilizing cavity 4, in this embodiment, the front cavity and the rear cavity of the throat are completely symmetrical, the pressure stabilizing cavity 4 adopts a symmetrical structure, so that the effect of stabilizing air flow is better, the flow uniformity of natural gas passing through each natural gas jet 301 is improved, and the mixture of natural gas and air is more uniform.

On the premise of ensuring that the whole length of the mixer is unchanged, the length of the mixing cavity in the embodiment is shortened, namely the space of the rear cavity is reduced, and the mixing in the rear section is somewhat disadvantageous. In order to compensate for the adverse factors of uneven mixing caused by the shortness of the mixing cavity, the injection angle of the natural gas injection port is properly reduced, and the overall mixing uniformity of the mixer is not reduced by improving the mixing uniformity of the natural gas at the throat.

The above embodiments are only for illustrating the technical solution of the present invention, and not for limiting the same; although the present invention has been described in detail with reference to the above embodiments, it should be understood by those of ordinary skill in the art that: the technical scheme described in the above embodiments can be modified or some technical features thereof can be replaced equivalently; such modifications and substitutions do not depart from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A gas mixer, comprising: the venturi tube is arranged in the outer shell, a pressure stabilizing cavity is formed between the venturi tube and the outer shell, an air inlet is further formed in the outer shell and communicated with the pressure stabilizing cavity, a plurality of air nozzles with the same size are formed in the wall of the venturi tube and communicated with the pressure stabilizing cavity, the geometric centers of the air nozzles are on the same circle, and the intervals among the air nozzles are equal.

2. A gas mixer according to claim 1, wherein the gas jet is provided in a converging section of the gas inlet end of the venturi.

3. A gas mixer according to claim 1, wherein the gas jet is provided in the throat section of the venturi.

4. A gas mixer according to claim 1, wherein the gas jet is arranged in a direction which forms an angle with the normal line of the inner wall of the venturi tube which extends through the geometrical centre of the gas jet.

5. A gas mixer according to claim 1, wherein connecting flanges are further provided at both ends of the outer housing.

6. A gas mixer according to claim 4, wherein the included angle is 30 °.