A passive working condition adaptive flow guide structure of a three-way catalyst

Abstract

A passive adaptive flow guiding structure for a three-way catalytic converter includes an intake pipe, a catalyst carrier, a flow guide, and an intake end cap. The intake end cap includes an intake airway. The flow guide forms a converging flow channel and a uniform flow channel within the intake airway. The flow guide includes a converging section and several expanding sections. The expanding sections cause the converging section to form several first guiding sections. The catalyst carrier includes a converging section and a uniform flow section. When the airflow rate is low, most of the airflow is concentrated through the converging section. When the airflow rate is high, the airflow passes relatively evenly through the converging section and the uniform flow section. This invention, through the flow guide located in the airflow channel, can adaptively adjust the flow guidance distribution of the exhaust gas according to different exhaust gas flow conditions. When the exhaust gas flow rate is low, the exhaust gas is concentrated on a small portion of the catalyst carrier, utilizing the low exhaust gas velocity to achieve rapid ignition temperature of the catalyst. When the exhaust gas flow rate is high, the expanding sections allow the exhaust gas to pass evenly through the catalyst, improving catalytic conversion efficiency.

Description

Technical Field

[0001] This invention belongs to the technical field of three-way catalytic converter structure, specifically relating to a passive adaptive flow guiding structure for a three-way catalytic converter. Background Technology

[0002] A three-way catalytic converter is an important exhaust gas purification device in a vehicle's exhaust emission system. It is mainly used to catalytically convert toxic and harmful carbon monoxide, hydrocarbons, and nitrogen oxides in exhaust gases into non-toxic carbon dioxide, water, and nitrogen. In existing three-way catalytic converters, to make the exhaust gas flow through the catalyst more uniform, a guide structure is usually set, such as the three-way catalytic converter intake end cover with a spiral guide plate disclosed in announcement number CN223739503U. This includes a three-way catalytic converter intake end cover body, which has a reaction chamber inside, and an inlet and an outlet at both ends communicating with the reaction chamber. The three-way catalytic converter intake end cover body is provided with an air guiding structure communicating with the air intake. The air guiding structure includes a guide column, a spiral guide plate and an air distribution plate coaxially fixed to the guide column along the air intake direction. The outer walls of the spiral guide plate and the air distribution plate are closely fitted with the inner wall of the three-way catalytic converter intake end cover body, and the air distribution plate has a number of guide grooves. The guide grooves in this technical solution are specifically guide ring grooves with an isosceles trapezoidal cross section. When the high-speed airflow passes through the guide ring groove with varying size, the flow velocity will be slowed down and further homogenized. Through further homogenization, the contact between the vehicle exhaust gas and the catalyst carrier can be more complete.

[0003] However, before the three-way catalytic converter reaches its ignition temperature when the car is first started, even if the exhaust gas is evenly distributed, it is difficult to achieve catalytic conversion. The main function of the above-mentioned technical solutions and most existing flow guiding structures is to improve the uniformity of airflow, which is relatively simple. As the requirements for automobile exhaust emissions become increasingly stringent, the performance requirements for three-way catalytic converters are also gradually increasing. The existing single-function three-way catalytic converter flow guiding structures are gradually unable to meet the needs. Summary of the Invention

[0004] This invention uses a flow guide located in the airflow channel to adaptively adjust the flow direction distribution of the exhaust gas according to different exhaust gas flow conditions. When the exhaust gas flow is small, the flow guide leads the exhaust gas to concentrate on a small part of the catalyst carrier, and the catalyst can quickly reach the ignition temperature by utilizing the low flow velocity of the exhaust gas. When the exhaust gas flow is large, the flow guide uses a gradually expanding section to make the exhaust gas pass through the catalyst evenly, thereby improving the catalytic conversion efficiency of the exhaust gas.

[0005] The technical problem solved by this invention can be achieved by the following technical solution: a passive adaptive flow guiding structure for a three-way catalytic converter, comprising an intake pipe, a catalyst carrier, and an intake end cap. The intake end cap is used to connect the intake pipe and the catalyst carrier, and also includes a flow guide. The intake end cap includes an intake flow channel, and the flow guide is fixedly connected to the intake end cap. The flow guide causes the intake flow channel to form a converging flow channel and a uniform flow channel. The flow guide includes a converging portion and several expanding portions. One end of the expanding portion is fixedly connected to the converging portion, and the other end extends obliquely towards the uniform flow channel, causing the converging portion to form several first guiding portions. The first guiding portions connect the converging flow channel and the uniform flow channel. The catalyst carrier includes a converging portion and a uniform flow portion. When the airflow rate in the intake flow channel is small, the converging portion causes most of the airflow to concentrate from the converging flow channel through the converging portion. When the airflow rate in the intake flow channel is large, the converging portion, the expanding portion, and the first guiding portions cause the airflow to uniformly pass from the converging flow channel and the uniform flow channel through the converging portion and the uniform flow portion.

[0006] The centerline length of the air intake end cap is L1, and the centerline length of the air guide is L2, with 0.4 ≤ L2 / L1 ≤ 0.8.

[0007] The thickness of the flow guide is 1.5-2.0mm. The flow guide includes an inner layer, a middle layer and an outer layer. The thickness of the inner layer is 0.5-1.0mm and the thickness of the outer layer is 0.5-1.0mm. The inner and outer layers are made of high-temperature resistant materials, while the middle layer is made of fiber material to reduce heat conduction.

[0008] The constriction section includes the starting end near the intake pipe, the inner diameter of which is D. p The distance between the starting end and the central axis of the intake pipe is L. p L p / D p ≤0.4, the distance between the starting end and the inlet port is not less than 5.0mm, in order to reduce gas pressure.

[0009] The contraction section is arc-shaped with a radius of R1, where 0.4 ≤ R1 / D. p ≤0.7, used to prevent airflow separation at low flow rates and to prevent airflow accumulation at medium and high flow rates.

[0010] The diffuser section is arc-shaped, and the radius of the catalyst support is R. t The radius of the expanding part is R2, R2 = R t The gradually expanding section and the first guiding section form a gradually expanding angle α, 10°≤α≤40°, which is used to make the airflow diffuse evenly at medium or high flow rates.

[0011] The maximum flow rate of the intake duct is Q Max The actual flow rate in the inlet channel is Q, the flow rate through the convergent section is Q1, and the flow rate through the equalizing section is Q2; when Q / Q Max When Q / Q is ≤0.3, 2.0≤Q1 / Q2≤2.5 is achieved.Max When the value is greater than 0.3, 0.35≤Q1 / Q2≤0.70 is achieved.

[0012] The flow-converging section is located at the end of the catalyst support closest to the intake pipe, and the flow-equalizing section is located at the end of the catalyst support furthest from the intake pipe. The cross-sectional area of ​​the flow-converging section is S1, the cross-sectional area of ​​the flow-equalizing section is S2, and the cross-sectional area of ​​the catalyst support is S. t 0.35≤S1 / S t ≤0.45, 0.55≤S² / S t ≤0.65.

[0013] The guide component also includes a first fixing part and a second fixing part, which are fixedly connected to the air intake end cover. A second flow guide is formed between the first fixing part and the second fixing part, and the second flow guide connects the flow convergence channel and the flow equalization channel.

[0014] The air intake end cap has a concave section in the middle, which allows the airflow in the uniform flow channel to diffuse when it passes through the concave section.

[0015] Compared with the prior art, the present invention has the following advantages: The present invention uses a guide component located in the airflow channel to adaptively adjust the flow direction distribution of the exhaust gas according to different exhaust gas flow conditions. When the exhaust gas flow is small, the guide component guides the exhaust gas to mainly concentrate on a small part of the catalyst carrier, and the catalyst can quickly reach the ignition temperature by utilizing the low flow velocity of the exhaust gas. When the exhaust gas flow is large, the guide component uses a gradually expanding section to make the exhaust gas pass through the catalyst evenly, thereby improving the catalytic conversion efficiency of the exhaust gas. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the structure of the present invention; Figure 2 This is a cross-sectional view of the present invention; Figure 3 yes Figure 2 Airflow path diagram; Figure 4 This is a graph showing the temperature change at the inlet of catalyst support 2 over time.

[0017] In the figure: 1-Inlet pipe, 2-Catalyst carrier, 21-Flow gathering section, 22-Flow equalization section, 23-Cylinder body, 24-Pad section, 3-Inlet end cap, 31-Inlet flow channel, 311-Flow gathering channel, 312-Flow equalization channel, 32-Concave section, 4-Guide component, 41-Contraction section, 411-Starting end, 42-Expanding section, 43-First flow guide section, 44-First fixing section, 45-Second fixing section, 46-Second flow guide section. Detailed Implementation

[0018] To make the technical means, creative features, objectives and effects of this invention easier to understand, the invention will be further described below with reference to specific illustrations.

[0019] In the description of this invention, it should be understood that the terms "one end", "the other end", "outer side", "upper", "inner side", "horizontal", "coaxial", "center", "end", "length", "outer end", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing this invention and simplifying the description, and are not intended to 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.

[0020] Combined with appendix Figure 1 To be continued Figure 4 As shown, this embodiment discloses a passive adaptive flow guiding structure for a three-way catalytic converter, including an intake pipe 1, a catalyst carrier 2, and an intake end cap 3. The intake end cap 3 connects the intake pipe 1 and the catalyst carrier 2. It also includes a flow guide 4. The intake end cap 3 includes an intake flow channel 31. The flow guide 4 is fixedly connected to the intake end cap 3. The flow guide 4 causes the intake flow channel 31 to form a convergent flow channel 311 and a uniform flow channel 312. The flow guide 4 includes a converging portion 41 and several expanding portions 42. One end of the expanding portion 42 is fixedly connected to the converging portion 41, and the other end extends obliquely toward the uniform flow channel 312, so that the converging portion 41 forms several first guide portions 43. The first guide section 43 connects the convergence channel 311 and the uniform flow channel 312. The catalyst carrier 2 includes a convergence section 21 and a uniform flow section 22. The convergence section 21 is located at the end of the catalyst carrier 2 near the intake pipe 1, and the uniform flow section 22 is located at the end of the catalyst carrier 2 away from the intake pipe 1. When the airflow in the intake channel 31 is small, the contraction section 41 causes most of the airflow to concentrate from the convergence channel 311 through the convergence section 21. When the airflow in the intake channel 31 is large, the contraction section 41, the expansion section 42 and the first guide section 43 cause the airflow to pass relatively evenly from the convergence channel 311 and the uniform flow channel 312 through the convergence section 21 and the uniform flow section 22.

[0021] In combination with the above, preferably, in this embodiment, the intake pipe 1 is horizontally arranged, one end of the intake pipe 1 is sealed and connected to the engine exhaust outlet, and the other end is coaxially fixedly connected to the intake end cover 3. The other end of the intake end cover 3 is fixedly connected to the catalyst carrier 2, preferably welded to the outer wall of the catalyst carrier 2. The catalyst carrier 2 adopts a cylindrical structure, and the catalyst carrier 2 is uniformly filled with a three-way catalyst. The catalyst carrier 2 includes an outer cylinder 23 and a liner 24 located between the cylinder 23 and the three-way catalyst. The liner 24 preferably adopts a low thermal conductivity composite liner, so that the overall structure of the three-way catalyst is compact and does not increase the axial length, which is suitable for the narrow installation space of the engine compartment of the range-extended hybrid passenger vehicle.

[0022] In combination with the above installation structure, preferably, in this embodiment, the flow guide 4 further includes a first fixing part 44 and a second fixing part 45. The first fixing part 44 and the second fixing part 45 are respectively provided on the left and right sides of the flow guide 4. The first fixing part 44 and the second fixing part 45 are fixedly connected to the air inlet end cover 3. A second flow guide 46 is formed between the first fixing part 44 and the second fixing part 45. The second flow guide 46 connects the flow convergence channel 311 and the flow equalization channel 312. The first flow guide 43 is located in the middle of the flow guide. A plurality of first flow guides 43 form a regular multi-row arrangement structure. The first flow guides 43 in each row are evenly spaced from each other.

[0023] Combined with the above installation structure, the ratio of the airflow velocity v1 in the convergent flow channel 311 to the airflow velocity v2 in the uniform flow channel 312, v1 / v2, is no greater than 1.3.

[0024] Based on the above, the centerline length of the air intake end cap 3 is L1, the centerline length of the air guide 4 is L2, and 0.4≤L2 / L1≤0.8.

[0025] In combination with the above, preferably, in this embodiment, the thickness of the flow guide 4 is 1.5-2.0 mm; when the flow guide 4 has high requirements for thermal management temperature, in another preferred embodiment, the flow guide 4 includes an inner layer, a middle layer and an outer layer. The thickness of the inner layer is 0.5-1.0 mm, the thickness of the outer layer is 0.5-1.0 mm, the inner layer and the outer layer are made of high-temperature resistant materials, preferably 022Cr18NbTi or 019Cr19Mo2NbTi, wherein the high-temperature resistant operating temperature range is 800 degrees Celsius to 950 degrees Celsius, the middle layer is made of fiber material, preferably glass fiber or ceramic fiber material, to reduce thermal conductivity.

[0026] In conjunction with the above, the contraction section 41 includes a starting end 411 near the intake pipe 1, and the inner diameter of the intake pipe 1 is D. p Preferably, in this embodiment, the starting end 411 is located at the upper part of the central axis of the intake pipe 1; in another embodiment, the starting end 411 is located at the lower part of the central axis of the intake pipe 1; the distance between the starting end 411 and the central axis of the intake pipe 1 is L. p L p / D p ≤0.4, the distance between the starting end 411 and the port of the air inlet pipe 1 is not less than 5mm. The airflow pressure can be reduced by increasing the distance between the starting end 411 and the port of the air inlet pipe 1.

[0027] In summary, the contraction section 41 adopts an arc shape, and the radius of the contraction section 41 is R1, where 0.4 ≤ R1 / D. p≤0.7 is used to avoid airflow separation, thereby ensuring that when the airflow flow rate is small, the low-velocity airflow can be mostly concentrated through the convergence section 21, and when the airflow flow rate is large, the medium- and high-velocity airflow can diffuse through the convergence section 21 and the uniform flow section 22 respectively.

[0028] In summary, the diffuser 42 is arc-shaped, and the catalyst support 2 has a radius of R. t R t The preferred range is 50mm to 80mm, and the radius of the expanding portion 42 is R2, where R2 = R t The expanding section 42 and the first guiding section 43 form a gradually expanding angle α, 10°≤α≤40°, so that when the airflow is large, the airflow at medium or high velocity is uniformly diffused.

[0029] Based on the above, the maximum flow rate of the intake channel 31 is Q. Max The actual flow rate of the inlet channel 31 is Q, the flow rate through the convergence section 21 is Q1, and the flow rate through the equalization section 22 is Q2; when Q / Q Max When Q1 / Q2 is ≤ 0.3, we achieve 2.0 ≤ Q1 / Q2 ≤ 2.5. Preferably, in this embodiment, Q1 / Q2 = 7 / 3; when Q / Q Max When the value is greater than 0.3, 0.35 ≤ Q1 / Q2 ≤ 0.70 is achieved, making the flow field homogeneity index η ≥ 0.9, where , where u i Let u0 be the airflow velocity on each grid surface of the cross-section of catalyst support 2, and u0 be the average airflow velocity on all grid surfaces of the cross-section of catalyst support 2. i Let A be the area of ​​the i-th grid surface on the cross section of catalyst support 2, and let A be the total area of ​​the cross section of catalyst support 2.

[0030] Based on the above, the cross-sectional area of ​​the flow-gathering section 21 is S1, the cross-sectional area of ​​the flow-uniforming section 22 is S2, and the cross-sectional area of ​​the catalyst support 2 is S... t 0.35≤S1 / S t ≤0.45, 0.55≤S² / S t ≤0.65; preferably, in this embodiment, S1 / S t The preferred value is 0.4, S² / S t The preferred value is 0.6.

[0031] In combination with the above, a concave portion 32 is formed in the middle of the air intake end cover 3, so that the airflow in the uniform flow channel 312 diffuses when it passes through the concave portion 32.

[0032] Combining the above installation structure, and combining Figure 4 As shown, Figure 4The vertical axis represents the temperature at the inlet of catalyst support 2, in °C; the horizontal axis represents time, in 0.1 s; Curve A is the temperature change at the inlet of catalyst support 2 with the flow guide 4 installed over time, and curve B is the temperature change at the inlet of catalyst support 2 without the flow guide 4 installed over time; t A and t B These represent the time required for curves A and B to reach their ignition temperatures, respectively.

[0033] Specifically, the working process of this invention is as follows: When the car starts, the temperature of the three-way catalyst in the catalyst carrier 2 is relatively low, not reaching the ignition temperature of approximately 300°C, and at this time the exhaust gas flow rate and airflow velocity are also low. When Q / Q Max When the velocity is ≤0.3, most of the low-velocity exhaust gas directly enters the convergence channel 311 or is guided to the convergence channel 311 through the contraction section 41. A small portion of the exhaust gas enters the equalization channel 312 directly from the upper part of the guide member 4 or from the first guide section 43 or the second guide section 46, making Q1 / Q2=7 / 3. At this time, most of the airflow passes through the smaller convergence section 21, thereby rapidly raising the catalyst temperature to the ignition temperature of the catalyst. Without the guide member 4 installed, the inlet temperature of the catalyst carrier 2 takes about 85 seconds to reach the ignition temperature. After the guide member 4 is installed, the inlet temperature of the catalyst carrier 2 takes about 22 seconds to reach the ignition temperature. After the car has been running for a period of time, the exhaust gas flow rate gradually increases, and the airflow velocity also increases accordingly. When Q / Q Max When the value is >0.3, the gas flow rate through the first guide section 43 and the second guide section 46 also increases accordingly, thereby making the gas flow rate and velocity in the convergence channel 311 and the uniform flow channel 312 relatively average, and then uniformly passing through the catalyst carrier 2, so that the exhaust gas flow can fully contact and react with the catalyst that has reached the ignition temperature, thereby improving the catalytic conversion rate of the exhaust gas.

[0034] This invention uses a flow guide located in the airflow channel to adaptively adjust the flow direction distribution of the exhaust gas according to different exhaust gas flow conditions. When the exhaust gas flow is small, the flow guide leads the exhaust gas to concentrate on a small part of the catalyst carrier, and the catalyst can quickly reach the ignition temperature by utilizing the low flow velocity of the exhaust gas. When the exhaust gas flow is large, the flow guide uses a gradually expanding section to make the exhaust gas pass through the catalyst evenly, thereby improving the catalytic conversion efficiency of the exhaust gas.

[0035] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention in any way. Any simple modifications, equivalent changes, or alterations made to the above embodiments based on the technical principles of the present invention shall still fall within the scope of the technical solution of the present invention.

Claims

1. A passive working condition adaptive flow guide structure of a three-way catalyst, comprising an inlet pipe (1), a catalytic carrier (2) and an inlet end cover (3), the inlet end cover (3) being used to connect the inlet pipe (1) and the catalytic carrier (2), characterized in that: It also includes a flow guide (4). The air intake end cap (3) includes an air intake channel (31). The flow guide (4) is fixedly connected to the air intake end cap (3). The flow guide (4) causes the air intake channel (31) to form a converging flow channel (311) and a uniform flow channel (312). The flow guide (4) includes a constriction section (41) and several expanding sections (42). One end of the expanding section (42) is fixedly connected to the constriction section (41), and the other end extends obliquely toward the uniform flow channel (312), so that the constriction section (41) forms several first guide sections (43). The first guide sections (43) are connected to the air intake channel (312). The catalyst carrier (2) includes a flow-gathering channel (311) and a flow-uniforming channel (312). When the flow rate in the inlet channel (31) is small, the contraction section (41) causes most of the flow to concentrate from the flow-gathering channel (311) through the flow-gathering section (21). When the flow rate in the inlet channel (31) is large, the contraction section (41), the expansion section (42), and the first guide section (43) cause the flow to pass relatively evenly from the flow-gathering channel (311) and the flow-uniforming channel (312) through the flow-gathering section (21) and the flow-uniforming section (22).

2. The passive operating condition adaptive flow guiding structure of a three-way catalyst according to claim 1, characterized in that: The centerline length of the air intake end cap (3) is L1, and the centerline length of the air guide (4) is L2, 0.4≤L2 / L1≤0.

8.

3. The passive operating condition adaptive flow guiding structure of a three-way catalyst according to claim 2, characterized in that: The thickness of the flow guide (4) is 1.5-2.0 mm. The flow guide (4) includes an inner layer, a middle layer and an outer layer. The thickness of the inner layer is 0.5-1.0 mm and the thickness of the outer layer is 0.5-1.0 mm.

4. The passive operating condition adaptive flow guiding structure of a three-way catalyst according to claim 3, characterized in that: The contraction section (41) includes a starting end (411) near the intake pipe (1), the inner diameter of which is D. p The distance between the starting end (411) and the central axis of the intake pipe (1) is L. p L p / D p ≤0.4, the distance between the starting end (411) and the port of the air inlet pipe (1) is not less than 5.0 mm, in order to reduce the airflow pressure.

5. The passive operating condition adaptive flow guiding structure of a three-way catalyst according to claim 4, characterized in that: The contraction portion (41) is in a circular arc shape, and has a radius R1, 0.4≤R1 / D p ≤0.7 to prevent airflow separation at low flow rates and to prevent airflow concentration at medium to high flow rates.

6. The passive operating condition adaptive flow guiding structure of a three-way catalyst according to claim 5, characterized in that: The diffuser (42) is arc-shaped, and the catalyst support (2) has a radius of R. t The radius of the expanding part (42) is R2, R2=R t The expanding section (42) and the first diverting section (43) form a gradually expanding angle α, 10°≤α≤40°, which is used to make the airflow diffuse evenly at medium or high flow rates.

7. The passive operating condition adaptive flow guiding structure of a three-way catalyst according to claim 1, characterized in that: The maximum flow rate of the intake duct (31) is Q. Max The actual flow rate of the inlet channel (31) is Q, the flow rate through the convergence section (21) is Q1, and the flow rate through the equalization section (22) is Q2; when Q / Q Max When Q / Q is ≤0.3, 2.0≤Q1 / Q2≤2.5 is achieved. Max When the value is greater than 0.3, 0.35≤Q1 / Q2≤0.70 is achieved.

8. The passive operating condition adaptive flow guiding structure of a three-way catalyst according to claim 7, characterized in that: The flow-gathering section (21) is located at one end of the catalyst carrier (2) near the intake pipe (1), and the flow-equalizing section (22) is located at one end of the catalyst carrier (2) away from the intake pipe (1). The cross-sectional area of ​​the flow-gathering section (21) is S1, the cross-sectional area of ​​the flow-equalizing section (22) is S2, and the cross-sectional area of ​​the catalyst carrier (2) is S... t 0.35≤S1 / S t ≤0.45, 0.55≤S² / S t ≤0.

65.

9. The passive condition adaptive flow guiding structure of a three-way catalyst according to any one of claims 1 to 8, characterized in that: The guide (4) also includes a first fixing part (44) and a second fixing part (45), the first fixing part (44) and the second fixing part (45) are fixedly connected to the air inlet end cap (3), and a second flow guide (46) is formed between the first fixing part (44) and the second fixing part (45), the second flow guide (46) is connected to the flow convergence channel (311) and the flow equalization channel (312).

10. The passive operating condition adaptive flow guiding structure of a three-way catalyst according to claim 9, characterized in that: An indentation (32) is formed in the middle of the air intake end cap (3), so that the airflow in the uniform flow channel (312) diffuses when it passes through the indentation (32).

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