A back pressure reducing natural gas engine pre-processor

Abstract

The application relates to a back-pressure-reducing natural gas engine pre-treater, which comprises an outer shell and a pre-treater carrier, the outer shell is sequentially divided into an air inlet part, an air inlet expansion part, a carrier part, an exhaust contraction part and an exhaust part along an air flow direction; the air inlet part, the carrier part and the exhaust part are circular cylinders, the air inlet expansion part and the exhaust contraction part are uniformly-diameter-changing circular cylinders, the pre-treater carrier is a cylindrical honeycomb structure, a carrier support is fixedly connected in the carrier part, the pre-treater carrier is fixed in the carrier part through the carrier support, and a cavity is formed between the side wall of the pre-treater carrier and the inner wall of the carrier part. The cavity structure is added between the pre-treater carrier and the carrier part, and a flow guide pipe is arranged in the air inlet expansion part, so that the engine emission performance under the cold engine idling condition is ensured, the high-speed high-load exhaust resistance is greatly reduced, and the engine economic performance is further improved.

Description

Technical Field

[0001] This invention relates to the field of natural gas engine technology for commercial vehicles, and more particularly to a pre-processor for a natural gas engine with reduced back pressure. Background Technology

[0002] In recent years, my country's rapid economic development has led to a surge in demand for oil, resulting in energy shortages and environmental pollution. To alleviate these problems and improve atmospheric conditions, developing clean fuels has become a national strategy. Natural gas, with its clean, safe, efficient, and abundant reserves, along with its excellent emission performance, is increasingly being used in the engine industry.

[0003] In natural gas engine systems, the natural gas aftertreatment system, as a core component, largely determines the engine's emissions and economic performance.

[0004] Considering the development costs and overall vehicle layout of heavy-duty commercial vehicles, traditional natural gas engines employ a single aftertreatment technology. Since efficient operation of the aftertreatment unit requires a certain catalytic conversion temperature (>350℃), single aftertreatment solutions typically employ optimized layout (the aftertreatment unit is located on the same side as the engine exhaust to shorten connecting pipes) and insulation materials around the connecting pipes to reduce exhaust energy loss, thereby ensuring the aftertreatment unit reaches the system's efficient operating temperature in a short time. However, under cold start conditions, the low exhaust temperature leads to slow heating of the aftertreatment unit, resulting in low catalytic conversion efficiency and a risk of exceeding emission standards. To address this issue, engines employ a two-stage aftertreatment system. A pre-treatment aftertreatment unit is located at the turbocharger exhaust port. Directly connected to the turbocharger exhaust port, it heats up quickly but has a small size and limited processing capacity. To ensure high-load processing efficiency, a main aftertreatment unit is located downstream of the pre-treatment unit. When the engine starts cold, the exhaust volume is small. After passing through the turbocharger, the exhaust gas goes directly to the pre-treatment system (without pipeline energy loss), which can raise the temperature of the pre-treatment system in the shortest possible time. This ensures that the exhaust gas is catalytically reduced into harmless CO2 and N2 by the pre-treatment system, and then passes through the main aftertreatment system to reduce pollutants emitted during cold starts. When the engine warms up, the increased exhaust temperature causes the main aftertreatment system to reach its operating temperature. The exhaust gas then passes through both the pre-treatment system and the main aftertreatment system to ensure that emissions meet standards. Although the two-stage aftertreatment system can significantly reduce pollutants emitted during cold starts, it also increases the exhaust resistance of the entire exhaust system, resulting in a significant loss of power and fuel economy under high-speed, high-load engine conditions. Summary of the Invention

[0005] This invention proposes a pre-post processor for a natural gas engine with reduced back pressure, which is used as a pre-post processor in a two-stage post-processor and effectively solves the problem of high exhaust back pressure in existing natural gas two-stage post-processors.

[0006] To address the problems mentioned above in the background section, the present invention is achieved through the following technical solution:

[0007] A back pressure reduced natural gas engine pre-processor includes an outer casing and a pre-processor carrier. The outer casing is divided into an intake section, an intake expansion section, a carrier section, an exhaust contraction section, and an exhaust section in sequence along the airflow direction.

[0008] The air intake, carrier, and exhaust sections are all cylindrical, the air intake expansion section and the exhaust contraction section are both uniformly variable diameter cylindrical sections, and the pre-processor carrier is a cylindrical honeycomb structure.

[0009] A carrier support is fixedly connected to the carrier section. The carrier support includes several identical plate-shaped structures, all perpendicular to the inner wall of the carrier section and evenly distributed along the outer periphery of the pre-processor carrier. The pre-processor carrier is fixed inside the carrier section by the carrier support, and a cavity is formed between the side wall of the pre-processor carrier and the inner wall of the carrier section.

[0010] As a further explanation of the invention: the intake expansion section is provided with a guide pipe, which is a uniformly variable diameter circular pipe with the pipe diameter decreasing uniformly along the airflow direction; the large-diameter pipe opening is fixedly connected to the inlet end of the intake expansion section, and the small-diameter pipe opening is suspended; the guide pipe is coaxial with the pre-processor carrier.

[0011] As a further explanation of the invention: the angle between the wall of the guide tube and the axis of the air intake is 20° to 30°.

[0012] As a further explanation of the invention: both the intake and exhaust sections are provided with annular oxygen sensor mounts on their outer surfaces.

[0013] As a further explanation of the invention: when the engine is cold-started and idling, the engine speed is low and the exhaust gas volume is small. The exhaust gas passes directly through the pre-processor carrier under the guidance of the guide pipe.

[0014] When the engine enters high-speed, high-load operation, the exhaust gas simultaneously passes through the pre-processor carrier and the cavity between the pre-processor carrier and the carrier section.

[0015] As a further explanation of the invention: the inlet end of the air intake section is provided with an air intake flange, which is connected to the exhaust port flange of the engine turbocharger; the outlet end of the exhaust section is provided with an exhaust flange, which is connected to the inlet flange of the main after-processor.

[0016] As a further explanation of the invention: a two-stage post-processing scheme is adopted, in which the pre-post-processor of the reduced back pressure natural gas engine is used in series with the main post-processor, the front stage being the pre-post-processor and the rear stage being the main post-processor.

[0017] Compared with the prior art, the present invention has the following beneficial technical effects:

[0018] This invention adds a cavity structure between the pre-processor carrier and the carrier section, and sets up a guide pipe in the intake expansion section. When the engine is cold-started and idling, the engine speed is low and the exhaust gas volume is small. Under the guidance of the guide pipe, the exhaust gas directly passes through the pre-processor carrier, ensuring that the pre-processor reaches its operating temperature in the shortest time, thereby reducing pollutants emitted during cold start. Finally, it flows through the main aftertreatment system for catalytic conversion. When the engine enters high-speed, high-load operation, the temperatures of both the pre-processor and the main aftertreatment carrier have risen to their optimal operating temperatures. At this time, the exhaust gas simultaneously passes through the pre-processor carrier and the cavity structure between the pre-processor carrier and the carrier section, and finally flows through the main aftertreatment system for catalytic conversion. This solution ensures the emission performance of the engine during cold-start idling while significantly reducing exhaust resistance during high-speed, high-load operation, thereby further improving the engine's economic performance. Attached Figure Description

[0019] Figure 1 This is a three-dimensional structural diagram of the present invention;

[0020] Figure 2 This is a schematic diagram of the structure of the present invention;

[0021] Figure 3 This is a schematic diagram of the three-dimensional cross-sectional structure of the present invention;

[0022] Figure 4 This is a schematic diagram of the cross-sectional structure of the present invention;

[0023] Figure 5 This is a schematic diagram of the cross-sectional structure of the present invention;

[0024] Figure 6 This is a schematic diagram of the exhaust gas flow at idle speed during cold start of the engine according to the present invention;

[0025] Figure 7 This is a schematic diagram of the high-speed, high-load exhaust gas flow of the engine of the present invention;

[0026] Figure 8 This is a schematic diagram of the installation location of the present invention.

[0027] Explanation of reference numerals in the attached figures

[0028] 1. Outer shell; 2. Carrier support; 3. Guide tube; 4. Post-processor carrier; 5. Inlet flange; 6. Oxygen sensor mount; 7. Cavity; 8. Exhaust flange; A. Inlet section; B. Inlet expansion section; C. Carrier section; D. Exhaust contraction section; E. Exhaust section. Detailed Implementation

[0029] To better understand the above-mentioned objectives, features, and advantages of the present invention, the present invention will be described in detail below with reference to the accompanying drawings and specific embodiments. It should be noted that, unless otherwise specified, the embodiments and features described in these embodiments can be combined with each other.

[0030] In the description of this invention, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship commonly used when the product of this invention is in use. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this invention. In addition, the terms "first," "second," "third," etc., are only used to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0031] Furthermore, terms such as "horizontal" and "vertical" do not imply that components must be absolutely horizontal or suspended, but rather that they can be slightly tilted. For example, "horizontal" simply means that its direction is more horizontal than "vertical," and does not mean that the structure must be completely horizontal, but can be slightly tilted.

[0032] In the description of this invention, it should also be noted that, unless otherwise explicitly specified and limited, the terms "set," "install," "connect," and "link" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0033] Figure 1 This is a three-dimensional structural diagram of the first embodiment of the present invention; Figure 2 This is a schematic diagram of the structure of the first embodiment of the present invention;

[0034] Figure 3 , Figure 4 , Figure 5 This is a cross-sectional structural diagram of the first embodiment of the present invention.

[0035] like Figures 1 to 5 As shown, a back pressure reduced natural gas engine pre-processor includes an outer casing 1 and a pre-processor carrier 4. The outer casing 1 is divided into an intake section A, an intake expansion section B, a carrier section C, an exhaust contraction section D, and an exhaust section E in sequence along the airflow direction. The intake section A, intake expansion section B, carrier section C, exhaust contraction section D, and exhaust section E are integrally connected.

[0036] The air intake section A, the carrier section C, and the exhaust section E are all cylindrical, the air intake expansion section B and the exhaust contraction section D are both uniformly variable diameter cylindrical, and the pre-processor carrier 4 is a cylindrical honeycomb structure.

[0037] A carrier support 2 is fixedly connected to the carrier section C. The carrier support 2 includes several identical plate-shaped structures, all perpendicular to the inner wall of the carrier section C and evenly distributed along the outer periphery of the pre-processor carrier 4. The pre-processor carrier 4 is fixed inside the carrier section C by the carrier support 2, and a cavity 7 is formed between the side wall of the pre-processor carrier 4 and the inner wall of the carrier section C.

[0038] In this embodiment, the carrier support 2 includes six rectangular plate-like structures, the long side of which is the same as the axial length of the pre-processor carrier 4, and the short side is perpendicular to the carrier sidewall. The carrier support 2 is evenly distributed along the outer periphery of the pre-processor carrier 4, and firmly fixes the pre-processor carrier 4 inside the outer shell 1.

[0039] In this example, both the main post-processor and the pre-post-processor use three-way catalytic converters, but they differ in size. The pre-post-processor is smaller and has a limited processing capacity due to space constraints.

[0040] When the engine enters high-speed, high-load operation, cavity 7 adds an exhaust path for exhaust gas emissions, effectively reducing the back pressure of the aftertreatment system.

[0041] The intake expansion section B is provided with a guide pipe 3, which is a uniformly variable diameter circular pipe with the diameter decreasing uniformly along the airflow direction; the large diameter pipe opening is fixedly connected to the inlet end of the intake expansion section B, and the guide pipe 3 is coaxial with the pre-processor carrier 4.

[0042] The small-diameter pipe opening is suspended, and there is a gap between the suspended pipe opening and the inlet end of the pre-processor carrier 4; the small pipe diameter is smaller than the diameter of the pre-processor carrier 4.

[0043] The angle between the wall of the guide pipe 3 and the axis of the air intake A is 20° to 30°.

[0044] The guide pipe 3 has a guiding function. When the engine is cold-started and idling, the engine speed is low and the exhaust gas volume is small. The exhaust gas passes directly through the pre-processor carrier 4 under the guidance of the guide pipe 3.

[0045] like Figure 8 The image shows the installation location of the present invention.

[0046] A two-stage post-processing scheme is adopted, in which the pre-post-processor and the main post-processor of the reduced back pressure natural gas engine are used in series, with the pre-post-processor being the first stage and the main post-processor being the second stage.

[0047] The intake section A has an intake flange 5 at its inlet end, which is connected to the exhaust port flange of the engine turbocharger; the exhaust section E has an exhaust flange 8 at its outlet end, which is connected to the inlet flange of the main after-processor. A pipeline connects the outlet end of the exhaust section E to the inlet end of the main after-processor.

[0048] In actual manufacturing, the intake flange 5 and exhaust flange 8 can be changed according to the form of the engine turbocharger exhaust port flange and the main after-processor inlet flange.

[0049] Both the intake section A and the exhaust section E have annular oxygen sensor holders 6 on their outer surfaces. The opening of the oxygen sensor holder 6 communicates with the interior of the outer casing 1, and the oxygen sensor holder 6 is integrally connected to the outer casing 1. The oxygen sensor holder 6 is used to install the oxygen sensor.

[0050] The working principle is as follows:

[0051] When the engine is cold-started and idling, the engine speed is low and the exhaust gas volume is small. The exhaust gas enters from the intake section A, passes through the intake expansion section B, and is directly passed through the pre-processor carrier 4 under the guidance of the guide pipe 3. It then passes through the exhaust contraction section D and is discharged to the exhaust section E, and finally flows through the main after-processor for catalytic conversion.

[0052] When the engine enters high-speed, high-load operation, the exhaust gas enters from the intake section A, passes through the intake expansion section B, and simultaneously passes through the pre-processor carrier 4 and the cavity 7 between the pre-processor carrier 4 and the carrier section C via the guide pipe 3. It then passes through the exhaust contraction section D and is discharged to the exhaust section E, and finally flows through the main after-processor for catalytic conversion.

[0053] Figure 6 This is a schematic diagram of the exhaust gas flow during cold start idling of an engine. When the engine is cold start idling, the engine speed is low and the exhaust gas volume is small. The exhaust gas passes directly through the guide pipe 3 and the pre-processor carrier 4 to ensure that the post-processor reaches the working temperature in the shortest time, thereby reducing pollutants emitted during cold start.

[0054] Figure 7 This diagram illustrates the exhaust gas flow when the engine is operating at high speed and high load. When the engine enters high-speed and high-load operation, the exhaust gas simultaneously passes through the pre-processor carrier 4 and the cavity structure between the pre-processor carrier 4 and the outer shell 1, and then flows through the main aftertreatment system for processing. This significantly reduces the exhaust resistance at high speed and high load while ensuring the engine's emission performance, thereby further improving the engine's economic performance.

[0055] The exhaust back pressure of a typical two-stage aftertreatment system is around 23 kPa, while that of a single-stage aftertreatment system is around 12 kPa. The exhaust back pressure of this invention is around 15 kPa.

[0056] This invention is not limited to the above-described optional embodiments. Anyone can derive other various forms of products under the guidance of this invention. However, regardless of any changes made in their shape or structure, any technical solution that falls within the scope of the claims of this invention shall be protected by this invention.

Claims

1. A pre-processor for a natural gas engine with reduced back pressure, characterized in that: It includes an outer shell (1) and a pre-processor carrier (4), wherein the outer shell (1) is divided into an air intake section (A), an air intake expansion section (B), a carrier section (C), an exhaust contraction section (D), and an exhaust section (E) in sequence along the airflow direction; The air intake (A), carrier (B) and exhaust (E) are all cylindrical, the air intake expansion (B) and exhaust contraction (D) are both uniformly variable diameter cylindrical, and the pre-processor carrier (4) is a cylindrical honeycomb structure. A carrier support (2) is fixedly connected to the carrier section (C). The carrier support (2) includes several identical plate-shaped structures, all perpendicular to the inner wall of the carrier section (C) and evenly distributed along the outer periphery of the pre-processor carrier (4). The pre-processor carrier (4) is fixed in the carrier section (C) by the carrier support (2). A cavity (7) is formed between the side wall of the pre-processor carrier (4) and the inner wall of the carrier section (C). The intake expansion section (B) is provided with a guide pipe (3), which is a uniformly variable diameter circular pipe with the pipe diameter decreasing uniformly along the airflow direction; the large diameter pipe opening is fixedly connected to the inlet end of the intake expansion section (B), and the small diameter pipe opening is suspended; the guide pipe (3) is coaxial with the pre-processor carrier (4); A two-stage post-processing scheme is adopted, in which the pre-post-processor and the main post-processor of the reduced back pressure natural gas engine are used in series, with the pre-post-processor being the first stage and the main post-processor being the second stage. When the engine is cold-started and idling, the engine speed is low and the exhaust gas volume is small. The exhaust gas passes directly through the pre-processor carrier (4) under the guidance of the guide pipe (3). When the engine enters high-speed, high-load operation, the exhaust gas passes through the pre-processor carrier (4) and the cavity (7) between the pre-processor carrier (4) and the carrier part (C).

2. The back pressure reduced natural gas engine post-processor according to claim 1, characterized in that: The angle between the wall of the guide pipe (3) and the axis of the air intake (A) is 20° to 30°.

3. The back pressure reduced natural gas engine pre-processor according to claim 1, characterized in that: Both the intake section (A) and the exhaust section (E) are provided with annular oxygen sensor seats (6) on their outer surfaces.

4. The back pressure reduced natural gas engine pre-processor according to claim 1, characterized in that: The intake section (A) is provided with an intake flange (5) at its inlet end, which is connected to the exhaust port flange of the engine turbocharger; the exhaust section (E) is provided with an exhaust flange (8) at its outlet end, which is connected to the inlet flange of the main after-processor.

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