Device for reducing BETP emission of carbon canister

Abstract

The invention discloses a device for reducing BETP emission of a carbon canister. The device comprises a shell and carbon paper arranged in the shell, the inner space of the shell is separated by the carbon paper, and a channel is directly formed between adjacent carbon paper or between the carbon paper and the inner wall of the shell; the multiple sections of channels are communicated to form an internal flow channel with a roundabout structure; one end of the internal flow channel is an air inlet, and the other end is an air outlet. The carbon paper and the shell of a specific structure are adopted for adsorbing and temporarily storing hydrocarbon molecules, the purpose of greatly reducing BETP emission is achieved by reasonably arranging an internal flow channel and prolonging the diffusion path of mixed gas, meanwhile, the cost can be reduced by 30% or above compared with a carbon rod, and the carbon rod can serve as a substitute product of the carbon rod.

Description

Technical Field

[0001] This invention relates to the field of automotive evaporative emission control technology, and in particular to a device for reducing BETP emissions from a carbon canister. Background Technology

[0004] To meet the demands of both international and domestic markets, automotive evaporative emission control systems must incorporate devices to control BETP emissions from the charcoal canister's atmospheric vent.

[0005] In response to this upgrade, the traditional solution is to integrate a honeycomb into the atmospheric vent of the carbon canister. The honeycomb is a component specifically developed to address BETP emissions. It is honeycomb shaped and features low flow resistance, easy desorption, and low residue. It is effective in controlling BETP emissions and can basically meet the requirements.

[0006] However, overall, carbon rods have the following disadvantages in the domestic market: First, the production threshold is high. Only a handful of companies worldwide have the capability to produce carbon rods for automobiles, and only a few, such as Ingenieur in the United States and BASF in Germany, have achieved large-scale application. The former uses a carbon powder mixed with binder extrusion process, while the latter uses a ceramic substrate carbon plating process.

[0007] Second, the shape and specifications are limited. Carbon rods are cylindrical, typically with a diameter of 27mm or 35mm and a length of 50mm or 100mm. Due to manufacturing process limitations, increasing the length significantly increases production difficulty.

[0008] Third, the price is high. Due to the high production difficulty and insufficient competition, the unit price of carbon rods is relatively high. For example, a carbon rod with a specification of 35*100 (diameter*length) costs 50-100 yuan. Adapting to the above new regulations will inevitably increase the manufacturing cost of the whole vehicle.

[0009] IV. Low product qualification rate. Because the carbon rod substrate is activated carbon powder, it is relatively brittle and prone to chipping, cracking, and breakage, resulting in a high scrap rate during production and assembly. Summary of the Invention

[0010] The present invention discovered and primarily solved the following specific problems during its research and development: The FLVV valve at the top of the fuel tank is connected to the adsorption port of the charcoal canister via an adsorption pipe. The charcoal canister's vent is open, allowing the fuel tank to exchange air with the outside environment through the charcoal canister to maintain normal operating pressure. Following emission standards, during the test, the fuel tank is maintained at 40% of its rated volume with gasoline. As the temperature in the evaporative emission sealed chamber rises, the internal pressure of the fuel tank increases. The hydrocarbon mixture is discharged into the charcoal canister through the FLVV valve and adsorption pipe. Under ideal conditions, all hydrocarbon molecules in the mixture are absorbed by the activated carbon inside the charcoal canister under the influence of van der Waals forces, while the air is discharged into the atmosphere through the charcoal canister's vent.

[0011] In reality, due to the maximum ventilation resistance limitation, the adsorption path inside the charcoal canister cannot be designed to be too long. Excessive ventilation resistance would cause a series of problems such as the vehicle refueling nozzle tripping. Therefore, some hydrocarbon molecules in the air-fuel mixture would pass through the charcoal canister with the airflow and escape from the atmospheric vent, resulting in emissions. Furthermore, the test charcoal canister was not brand new, but rather a canister that had undergone a standard aging process. After a specific oil-gas adsorption-desorption pretreatment cycle, due to the microporous characteristics of activated carbon, a certain amount of hydrocarbon residue remained inside the canister. Under the influence of temperature rise and airflow, this residue would also migrate and diffuse to the atmospheric vent. These two parts constitute the BETP emissions from the charcoal canister's atmospheric vent. Under severe conditions, this emission would exceed the limit, and simply increasing or lengthening the original charcoal canister would not solve the problem (as mentioned above, the US standard market uses integrated carbon rods to solve this problem). Under stricter emission limits or BETP requirements, this emission is the target that the device of this invention aims to address.

[0012] Therefore, the present invention aims to provide a device for reducing BETP emissions from a carbon canister, which replaces the carbon rod with carbon paper and connects to the vent of the carbon canister to the atmosphere via a pipeline or direct insertion, in order to reduce BETP emissions from the carbon canister atmosphere, thereby controlling emissions and passing the regulatory tests required for the whole vehicle.

[0013] The technical solution to the above problem is: a device for reducing BETP emissions from carbon canisters, comprising an outer shell and carbon paper arranged inside the outer shell; the device uses carbon paper and a shell with a specific structure as an independent or integrated component to adsorb and temporarily store hydrocarbon molecules, and by rationally arranging the internal flow channels, the diffusion and migration path of the mixed gas is extended, thereby achieving the goal of significantly reducing BETP emissions.

[0014] The further technical solution is as follows: the carbon paper divides the internal space of the outer shell, and channels are formed directly between adjacent carbon papers or between the carbon paper and the inner wall of the outer shell; multiple channels are connected to form an internal flow channel with a meandering structure; one end of the internal flow channel is an air inlet and the other end is an air outlet.

[0015] A further technical solution is that multiple carbon paper sheets are arranged longitudinally inside the shell, forming channels between adjacent carbon paper sheets or between the carbon paper sheets and the inner wall of the shell; the multiple channels are connected end to end to form an internal flow channel with a meandering structure.

[0016] A further technical solution is that the carbon paper is spirally wound inside the outer shell, and the spacing between each spirally wound carbon paper surface is uniform and equal after being wound, forming a spiral internal flow channel.

[0017] The further technical solution is: multiple pieces of carbon paper are spaced apart inside the outer shell, the periphery of the carbon paper is fixedly connected to the inner wall of the outer shell, the carbon paper is provided with ventilation holes, and the multiple pieces of carbon paper form a multi-layer filter internal flow channel through the ventilation holes.

[0018] A further technical solution is that the gap between adjacent carbon paper is set based on the balance between ventilation resistance and adsorption effect. The gap setting should first ensure the size of the ventilation cross section, which should not be smaller than the cross section of the existing bottleneck part of the fuel system ventilation pipeline, so as not to significantly increase the ventilation resistance of the system. Under the premise of ensuring the ventilation cross section conditions, from the perspective of working efficiency, the gap should be designed to be as small as possible, which is conducive to the full contact between carbon paper and hydrocarbon molecules to ensure adsorption efficiency.

[0019] The further technical solution is as follows: the shape and size of the outer shell are determined according to the vehicle installation space, the form of the external interface, and the target area of ​​the carbon paper; the design of the carbon paper area is based on the equivalent calculation of adsorption capacity and should be determined by taking into account the gap between the original BETP emissions of the carbon canister and the regulatory limits.

[0020] A further technical solution is that the gap between adjacent carbon paper sheets is 3-10mm; and the area of ​​the carbon paper sheet is 100-2000 square centimeters.

[0021] A further technical solution is as follows: the carbon paper is installed inside the outer casing through a fixing structure, the fixing structure including a bracket and a slot; the slot is fixedly connected to the inside of the outer casing or integrally formed with the outer casing, and the bracket is spaced apart on the side of the slot; the carbon paper is inserted into the slot for fixing.

[0022] The further technical solution is as follows: the outer shell is provided with two ports, one of which is connected to the atmospheric port of the charcoal canister, and the other port is connected to the dust filter or the charcoal canister shut-off valve at the rear end; the charcoal paper has activated carbon particles on both sides.

[0023] The further technical solution is that the outer shell includes an upper shell and a lower shell, which are welded using hot plate welding or laser welding processes.

[0024] The further technical solution is: the device is connected to the vent of the charcoal canister via a pipeline or direct insertion, or it is integrated into the charcoal canister using a special structure.

[0025] By adopting the above technical solution, the device for reducing BETP emissions from charcoal canisters according to the present invention has the following advantages compared with the prior art: First, the adsorption capacity can be flexibly controlled. This device increases the length of the internal flow channel by adding layers of carbon paper inside the outer shell, which allows for arbitrary increases or decreases in the contact area of ​​the airflow. This contact area is the adsorption area for hydrocarbon molecules, meaning that the adsorption area can be flexibly adjusted according to the vehicle's original basic emission levels and target limits.

[0026] Second, the adsorption time can be flexibly controlled. Similar to the first point, without significantly increasing the ventilation resistance, the passage time of the mixed gas can be adjusted from 1 to 60 minutes by controlling the length of the flow channel to achieve the purpose of full adsorption.

[0027] III. Low Flow Resistance Characteristics of the Flow-by Structure. Due to refueling emission requirements, the exhaust resistance of the fuel system must be controlled below 3 kPa during refueling. At a flow rate of 60 L / min, this device, with its flow-by structure and reasonable internal flow channel design, has fully controllable flow resistance, generally kept below 0.5 kPa, without significantly increasing the system's ventilation resistance.

[0028] IV. Good Adsorption Capacity. The adsorption capacity of this device, according to ASTM D5228, has an initial butane working capacity (BWC) range of 0.1 g / 100 cm³. 2 ~5g / 100cm 2 Between them, hydrocarbon molecules that penetrate the charcoal canister can be effectively captured.

[0029] V. Easy desorption. The desorption rate of this device is greater than 90% (residual less than 10%). A certain amount of airflow can completely desorb the hydrocarbon molecules temporarily stored in the carbon paper, with low residual.

[0030] VI. Flexible shape. The shape of this device can be flexibly designed according to the installation space of the vehicle, ensuring the effective carbon paper area and ventilation cross-sectional dimensions.

[0031] VII. Low cost. The cost of this device is expected to be more than 30% lower than that of carbon rod products, enabling emissions upgrades with only a slight increase in procurement costs.

[0032] In summary, this invention uses carbon paper and a shell with a specific structure to adsorb and temporarily store hydrocarbon molecules. By rationally arranging the internal flow channels, the diffusion path of the mixed gas is extended, thereby achieving a significant reduction in BETP emissions. At the same time, the cost can be reduced by more than 30% compared to carbon rods, making it a viable alternative to carbon rods.

[0033] The working principle of this invention's device is as follows: The adsorption mode of the carbon paper is flow-by. In this mode, the mixed gas evaporating from the fuel tank does not penetrate the carbon paper. Instead, when the gas flow carrying hydrocarbon molecules passes through the side of the carbon paper, the hydrocarbon molecules are captured by the activated carbon particles in the carbon paper due to intermolecular forces (van der Waals forces), thereby reducing the escape of hydrocarbon molecules. According to experimental data, during the evaporation emission test, for a fuel tank with a rated volume of 55L, the exhaust volume per day is approximately 11L, therefore the flow rate is approximately 0.016L / min. At such a slow flow rate, coupled with a relatively long flow channel, the time for hydrocarbon molecules to pass through the filter is approximately 1–60 minutes, ensuring they are fully adsorbed by the carbon paper and achieving a very high capture efficiency.

[0034] Therefore, by making the carbon paper into a reasonable structure and arranging it at the atmospheric vent of the carbon canister, the goal of controlling BETP emissions can be achieved.

[0035] Carbon paper itself has a high desorption rate. When the car engine starts, fresh air enters from the outside, and the hydrocarbon molecules adsorbed on the carbon paper are washed away by the airflow and carried into the engine for combustion, thereby regenerating the adsorption capacity of the carbon paper, which conforms to the principle of recycling and maintenance-free use.

[0036] Activated carbon paper has a very mature production process, and China has a complete production chain. The process involves thoroughly mixing prepared activated carbon with pulp in a specific ratio (some additives, such as dispersants, may be needed during mixing) to ensure the activated carbon is uniformly dispersed in the pulp, resulting in activated carbon paper with uniform adsorption properties. Activated carbon paper is readily available and inexpensive.

[0037] The technical features of a device for reducing BETP emissions from a carbon canister according to the present invention will be further described below with reference to the accompanying drawings and embodiments. Attached Figure Description

[0038] Figure 1-1 This is a schematic diagram of a device for reducing BETP emissions from a carbon canister, as described in Example 1. Figure 1-2 This is a schematic diagram of the internal structure of a device for reducing BETP emissions from a carbon canister, as described in Example 1. Figure 1-3 This is a schematic diagram of the airflow direction path of the internal flow channel in Example 1; Figure 1-4This is a structural side view of an apparatus for reducing BETP emissions from a carbon canister, as described in Example 1. Figure 1-5 for Figure 1-4 Sectional view of AA; Figure 1-6 This is a top view of the structure of a device for reducing BETP emissions from a carbon canister, as described in Example 1. Figure 1-7 for Figure 1-6 Sectional view of BB; Figure 1-8 for Figure 1-7 Enlarged view of C; Figure 2-1 This is a schematic diagram of a device for reducing BETP emissions from a carbon canister, as described in Example 2. Figure 2-2 This is a schematic diagram of the structure of a device for reducing BETP emissions from a carbon canister, as described in Example 2. Figure 2-3 for Figure 2-2 Sectional view of DD; Figure 3-1 This is a schematic diagram of the structure of a device for reducing BETP emissions from a carbon canister, as described in Example 3. Figure 3-2 This is a structural cross-sectional view of a device for reducing BETP emissions from a carbon canister, as described in Example 3. Figure 3-3 This is a schematic diagram of the internal structure of a device for reducing BETP emissions from a carbon canister, as described in Example 3.

[0039] In the picture: 1-Outer shell, 11-Upper shell, 12-Lower shell, 2-Carbon paper, 3-Pipe opening, 4-Fixing structure, 41-Slot, 42-Bracket, 5-Airflow direction of the internal flow channel, 6-Ventilation hole. Detailed Implementation

[0040] The present invention discloses a device for reducing BETP emissions from a carbon canister, which is connected to the atmospheric vent of the carbon canister via a pipeline or direct insertion, or integrated into the interior of the carbon canister using a special structure. The device includes a shell 1 and carbon paper 2 arranged inside the shell 1. The device uses the carbon paper 2 and the shell 1 with a specific structure as an independent or integrated component to adsorb and temporarily store hydrocarbon molecules. By rationally arranging the internal flow channels, the diffusion and migration path of the mixed gas is extended, thereby achieving the goal of significantly reducing BETP emissions.

[0041] The carbon paper 2 divides the internal space of the outer shell 1, forming channels between adjacent carbon paper 2 or directly between carbon paper 2 and the inner wall of the outer shell 1; multiple channels are connected to form an internal flow channel with a meandering structure; one end of the internal flow channel is an air inlet and the other end is an air outlet.

[0042] The gap between adjacent carbon paper 2 is determined based on the balance between ventilation resistance and adsorption effect. To achieve ideal BETP emission control, it is generally designed to be 3-10mm. This gap setting should first ensure the size of the ventilation cross-section, which should not be smaller than the cross-section of the existing bottleneck in the fuel system's ventilation pipeline, to avoid significantly increasing the system's ventilation resistance and causing other performance problems. Under the premise of ensuring the above conditions, from the perspective of working efficiency, the gap should be designed to be as small as possible to facilitate sufficient contact between carbon paper 2 and hydrocarbon molecules and ensure adsorption efficiency.

[0043] The shape and size of the outer shell 1 are determined based on the vehicle installation space, the form of the external interface, and the target area of ​​the carbon paper 2. The design method for the area of ​​the carbon paper 2 is based on the equivalent calculation of adsorption capacity. The design area of ​​the carbon paper 2 is generally 100 to 2000 square centimeters. Its final design should take into account the gap between the original BETP emissions of the carbon canister (without this device) and the regulatory limits.

[0044] The following examples illustrate several layout styles of charcoal paper 2 and shell 1 with specific structures as different embodiments.

[0045] Example 1: Carbon paper 2 is arranged longitudinally inside the outer casing 1 like Figures 1-1 to 1-8 As shown, a device for reducing BETP emissions from a charcoal canister is connected to the vent of the charcoal canister via a pipeline or direct insertion. The device includes a housing 1 and charcoal paper 2 arranged inside the housing 1. The housing 1 is rectangular and has two ports 3. One port 3 is connected to the vent of the charcoal canister (or can be designed as a direct insertion type), and the other port 3 is connected to other accessories at the rear end, such as a dust filter or a charcoal canister shut-off valve (to prevent dust from entering the charcoal canister system and causing blockage during desorption).

[0046] In this embodiment, multiple pieces of carbon paper 2 are arranged longitudinally along the shell 1 inside the outer shell, dividing the internal space of the outer shell 1 and forming channels between adjacent carbon paper 2 or between carbon paper 2 and the inner wall of the outer shell 1. These multiple channels are connected end-to-end to form an internal flow channel with a meandering structure. One end of each internal flow channel is an air inlet, which is connected to a pipe 3 that connects to the atmospheric outlet of the carbon canister; the other end of the internal flow channel is an air outlet, which is connected to another pipe 3. The gap between adjacent carbon paper 2 is 5 mm.

[0047] The carbon paper 2 is mounted inside the housing via a fixing structure 4. The fixing structure 4 includes a slot 41 and a bracket 42 (see...). Figure 1-7The slot 41 is fixedly connected to the inside of the outer shell 1 or integrally formed with the outer shell 1. The bracket 42 is spaced apart on the side of the slot 41 to limit the carbon paper 2. The carbon paper 2 is inserted into the slot 41 for fixation. The bracket 42 is used to prevent the carbon paper 2 from shifting and deforming under airflow and vibration conditions. Another function of the slot 41 is to prevent gaps from forming at the contact points between the carbon paper 2 and the outer shell 1, which could lead to air leakage. By pre-setting multiple fixing structures 4, the carbon paper 2 can be longitudinally arranged inside the outer shell 1 to form a meandering internal flow channel (see...). Figure 1-3 or Figure 1-5 The airflow direction of the internal flow channel is 5 (the arrow points to the airflow direction), ensuring full contact between the airflow and the carbon paper 2 to achieve effective adsorption.

[0048] Example 2: The carbon paper 2 is spirally rolled inside the outer shell 1 like Figures 2-1 to 2-3 As shown, a device for reducing BETP emissions from a charcoal canister is connected to the vent of the charcoal canister via a pipeline or direct insertion. The device includes a housing 1 and charcoal paper 2 built into the housing and arranged inside the housing 1. The housing 1 is cylindrical and has two ports 3. One port 3 is connected to the vent of the charcoal canister (or can be designed as a direct insertion type), and the other port 3 is connected to other accessories at the rear end, such as a dust filter or a charcoal canister shut-off valve (to prevent dust from entering the charcoal canister system and causing blockage during desorption).

[0049] The carbon paper 2 is spirally wound inside the outer shell, dividing the internal space of the outer shell 1. After being rolled up, the spacing between each spirally rolled carbon paper surface is uniform and equal, forming a spiral internal flow channel.

[0050] The carbon paper 2 is fixed to the inner wall of the outer casing 1 by welding or by a slot 41. In this embodiment, the carbon paper 2 is fixed by inserting it into the slot 41. The spiral roll of the carbon paper 2 forms a meandering internal flow channel (see...). Figure 2-3 The airflow direction of the internal flow channel follows path 5 (arrow indicates the airflow direction), ensuring sufficient contact between the airflow and the carbon paper 2 to achieve effective adsorption. One end of the internal flow channel is an air inlet (e.g., the innermost coil of the spiral), which connects to the port 3 connecting to the atmospheric outlet of the carbon canister; the other end of the internal flow channel is an air outlet (e.g., the outermost coil of the spiral), which connects to another port 3. The spacing between the carbon paper surfaces is 3mm.

[0051] Example 3: Carbon paper 2 with ventilation holes 6 is arranged in multiple layers inside the outer shell 1. like Figures 3-1 to 3-3As shown, a device for reducing BETP emissions from a charcoal canister is connected to the vent of the charcoal canister via a pipeline or direct insertion. The device includes a housing 1 and charcoal paper 2 built into the housing 1. The housing 1 is cylindrical and has two ports 3. One port 3 is connected to the vent of the charcoal canister (or can be designed as a direct insertion type), and the other port 3 is connected to other accessories at the rear end, such as a dust filter or a charcoal canister shut-off valve (to prevent dust from entering the charcoal canister system and causing blockage during desorption).

[0052] Multiple pieces of carbon paper 2 are longitudinally arranged inside the outer shell 1. The periphery of each carbon paper 2 is fixedly connected to the interior of the outer shell 1. Each carbon paper 2 has ventilation holes 6, and the multiple pieces of carbon paper 2 form a multi-layered filtration internal flow channel through the ventilation holes 6. The airflow makes full contact with the carbon paper 2 through the ventilation holes 6 (see...). Figure 3-3 The airflow direction of the internal flow channel is via path 5 (arrow points to the airflow direction), achieving effective adsorption. One end of the internal flow channel is an air inlet, which is connected to the pipe 3 connecting to the atmospheric outlet of the carbon canister; the other end of the internal flow channel is an air outlet, which is connected to another pipe 3. The gap between adjacent carbon sheets 2 is 6mm.

[0053] In embodiments 1 to 3 above, the outer shell 1 includes an upper shell 11 and a lower shell 12, which are welded using hot plate welding or laser welding. It should be ensured that there is no leakage at the welded surfaces of the two shell parts, and that there are no obvious gaps between the end face of the carbon paper 2 and the outer shell 1. The shell material of the outer shell 1 is nylon or an equivalent easily weldable material. The carbon paper 2 has activated carbon particles on both sides.

[0054] As another variation of Embodiments 1 to 3, applying the same principle, this device can be integrated into a whole with a special structure and a carbon canister.

[0055] Classic application scenarios: For fuel tanks of China VI emission standard vehicles with a rated capacity of 60L, a charcoal canister with an effective volume of 2 liters is generally used, with an initial butane working capacity of 145g. The emission control effect achieved by using this device is as follows: Whole vehicle desorption capacity at room temperature during China VI emission standard cycle Raw BETP emissions over two days The area of ​​carbon paper used in this device BETP emissions over two days after using this device 200~300L 100-400mg <![CDATA[200~300cm 2 ]]> 30~80mg 200~300L 100-400mg <![CDATA[>300cm 2 ]]> <30mg 150~200L 400~500mg <![CDATA[300~400cm 2 ]]> 30~150mg 150~200L 400~500mg <![CDATA[>400cm 2 ]]> <30mg .

[0056] It should be noted that the original emissions of a vehicle under BETP are determined by many factors. In addition to the rated volume of the fuel tank, the effective volume of the charcoal canister, and the overall vehicle desorption capacity listed above, it is also related to important factors such as the length-to-diameter ratio and shape of the charcoal canister and the type of activated carbon selected. The above data only demonstrates the emission reduction effect after adding this device. The specific type of activated carbon should be selected based on the specific objectives and experimental verification results.

[0057] The above description is merely a preferred embodiment of the present invention and does not limit the patent scope of the present invention. Any equivalent structural transformations made using the content of the present invention specification, or direct or indirect applications in the technical fields of other related products, are similarly included within the patent protection scope of the present invention.

Claims

1. A device for reducing BETP emissions from charcoal canisters, characterized in that: It includes an outer shell and carbon paper arranged inside the shell; the device uses carbon paper and a shell with a specific structure as an independent or integrated component to adsorb and temporarily store hydrocarbon molecules. By rationally arranging the internal flow channels, the diffusion and migration path of the mixed gas is extended, thereby achieving the goal of significantly reducing BETP emissions.

2. The device for reducing BETP emissions from charcoal canisters according to claim 1, characterized in that: The carbon paper divides the internal space of the outer shell, forming channels between adjacent carbon paper or directly between the carbon paper and the inner wall of the outer shell; multiple channels are connected to form an internal flow channel with a meandering structure; one end of the internal flow channel is an air inlet, and the other end is an air outlet.

3. The device for reducing BETP emissions from a carbon canister according to claim 2, characterized in that: Multiple carbon paper sheets are arranged longitudinally inside the outer shell, forming channels between adjacent carbon paper sheets or between the carbon paper sheets and the inner wall of the outer shell; the multiple channels are connected end to end to form an internal flow channel with a meandering structure.

4. The device for reducing BETP emissions from a carbon canister according to claim 2, characterized in that: The carbon paper is spirally wound inside the outer shell. After being rolled up, the spacing between each spirally rolled carbon paper surface is uniform and equal, forming a spiral internal flow channel.

5. The device for reducing BETP emissions from charcoal canisters according to claim 1, characterized in that: Multiple pieces of carbon paper are spaced apart inside the outer shell, and the periphery of the carbon paper is fixedly connected to the inner wall of the outer shell. The carbon paper is provided with ventilation holes, and the multiple pieces of carbon paper form a multi-layer filter internal flow channel through the ventilation holes.

6. The device for reducing BETP emissions from a carbon canister according to any one of claims 3-5, characterized in that: The method for setting the gap between adjacent carbon paper is based on the balance between ventilation resistance and adsorption effect. The setting of this gap should first ensure the size of the ventilation cross section. The ventilation cross section should not be smaller than the cross section of the existing bottleneck part of the fuel system ventilation pipeline, so as not to significantly increase the ventilation resistance of the system. Under the premise of ensuring the ventilation cross section conditions, from the perspective of working efficiency, the gap should be designed to be as small as possible, which is conducive to the full contact between carbon paper and hydrocarbon molecules to ensure adsorption efficiency.

7. The device for reducing BETP emissions from charcoal canisters according to claim 6, characterized in that: The shape and size of the outer shell are determined based on the vehicle installation space, the form of the external interface, and the target area of ​​the carbon paper; the design of the carbon paper area is based on the equivalent calculation of adsorption capacity and should take into account the gap between the original BETP emissions of the carbon canister and the regulatory limits.

8. The device for reducing BETP emissions from a carbon canister according to claim 7, characterized in that: The gap between adjacent carbon sheets is 3-10 mm; the area of ​​the carbon sheet is 100-2000 square centimeters.

9. The device for reducing BETP emissions from charcoal canisters according to claim 1, characterized in that: The carbon paper is installed inside the outer casing by a fixing structure, which includes a bracket and a slot; the slot is fixedly connected to the inside of the outer casing or integrally formed with the outer casing, and the bracket is spaced apart on the side of the slot; the carbon paper is inserted into the slot for fixing.

10. The device for reducing BETP emissions from a carbon canister according to claim 1, characterized in that: The outer shell is provided with two ports, one of which is connected to the vent of the charcoal canister, and the other is connected to the dust filter or the charcoal canister shut-off valve at the rear end; the charcoal paper has activated carbon particles on both sides.

11. The device for reducing BETP emissions from a carbon canister according to claim 1, characterized in that: The outer shell includes an upper shell and a lower shell, which are welded using hot plate welding or laser welding processes.

12. The device for reducing BETP emissions from a carbon canister according to claim 1, characterized in that: This device is connected to the charcoal canister's vent via a pipeline or direct insertion, or, using the same principle, employs a special structure to integrate it into a single unit.

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