A carbon can solenoid valve filter, its design method and fuel vapor emission control system

Abstract

The application discloses a carbon tank electromagnetic valve filter, a design method thereof and a fuel evaporation emission control system, and relates to the technical field of filters, and particularly relates to a filter used for filtering carbon powder particles entrained in steam flowing out of a carbon tank desorption port, characterized in that: a one-way valve is further included, the one-way valve is opened when the internal resistance of the filter exceeds a preset value, and airflow is bypassed through the one-way valve; and the carbon tank electromagnetic valve filter is arranged between a carbon tank and a carbon tank electromagnetic valve. The carbon tank electromagnetic valve filter, the design method thereof and the fuel evaporation emission control system can effectively solve the defects of the prior art, such as the lack of a systematic design method, the increase in resistance after long-term use, and the desorption failure, provide a quantitative design method for filter parameters with a theoretical basis, ensure the rationality and accuracy of engineering design selection, and have strong practicability and good application prospect.

Description

Technical Field

[0001] This invention belongs to the field of automotive fuel evaporation emission control technology, and more specifically, relates to a carbon canister solenoid valve filter, its design method, and a fuel evaporation emission control system. Background Technology

[0002] The fuel system of a gasoline vehicle is divided into the fuel supply system and the evaporative emission control system. The main components of the evaporative emission control system include: the fuel tank, the carbon canister, the carbon canister solenoid valve, and the vapor line. Its working principle is that gasoline vapor evaporated in the fuel tank is transported to the carbon canister for storage through the vapor line. When the engine is running, depending on different operating conditions, the ECU controls the carbon canister solenoid valve to open, using the vacuum in the intake manifold to desorb the gasoline vapor adsorbed in the carbon canister and send it into the engine for combustion. The carbon canister solenoid valve is one of the core components of the evaporative emission control system.

[0003] During use, carbon canisters generate tiny carbon particles smaller than 50μm. These particles can penetrate the canister's barrier layer, flow out from the desorption port, and enter the solenoid valve along the steam line. They gradually accumulate and adhere inside the solenoid valve, easily causing it to jam. If the valve core is stuck in the normally open position, the vehicle will experience increased fuel consumption, engine vibration, and stalling during cold starts due to a lower air-fuel ratio. If the valve core is stuck in the normally closed position, the carbon canister cannot be flushed and regenerated, remaining in a supersaturated state for a long time, ultimately leading to canister failure. Gasoline vapor will then escape from the canister's vent, causing environmental pollution.

[0004] While existing technologies include solenoid valve-based filtration devices, specific design calculation methods for key filter parameters are not provided. This makes the technology impractical in engineering implementation, hindering the accuracy and consistency of design results and affecting its effectiveness. Summary of the Invention

[0005] The purpose of this invention is to solve the technical problem of valve core jamming caused by the inflow of tiny carbon particles into the carbon canister solenoid valve in the prior art, and to overcome the defects of existing filter devices that lack systematic design methods and cause desorption failure due to increased resistance after long-term use. In particular, it provides a quantitative design method for filter parameters with theoretical basis, which ensures the rationality and accuracy of engineering design selection. This invention relates to a carbon canister solenoid valve filter, its design method, and a fuel evaporation emission control system.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows: the provided carbon canister solenoid valve filter includes a filter for filtering carbon powder particles entrained in the steam flowing out of the carbon canister desorption port, characterized in that: it further includes a one-way valve, which opens when the internal resistance of the filter exceeds a preset value, and the airflow bypasses through the one-way valve; the carbon canister solenoid valve filter is arranged between the carbon canister and the carbon canister solenoid valve.

[0007] The opening pressure of the one-way valve is greater than 1.6 kPa and less than 2.5 kPa.

[0008] The filter contains a filter element, which is selected from one of the following: paper filter element, non-woven fabric filter element, metal mesh filter element, ceramic filter element, sintered metal filter element, or composite fiber filter element; the filter element is fixed to the filter housing by snap-fit, threaded, welded, or riveted connection.

[0009] The check valve is one of the following: spring-loaded check valve, diaphragm check valve, gravity check valve, or solenoid check valve.

[0010] A design method for a carbon canister solenoid valve filter includes the following steps: S1, calculating the minimum filter volume V; S2, calculating the minimum flow diameter D of the filter inlet and outlet; S3, selecting a check valve.

[0011] In step S1, given the engine displacement W and the number of engine cylinders N, the minimum filter volume is calculated using the following formula. .

[0012] In step S2, given the engine's maximum intake air volume Q and the system's maximum airflow velocity limit Vmax, the minimum flow diameters of the filter inlet and outlet are calculated using the following formula. ,in This refers to the filter element attenuation rate.

[0013] Step S2 includes the following sub-steps: S21, based on engine bench data, select the maximum intake volume Q; S22, determine the maximum airflow velocity limit Vmax in the system, wherein Vmax does not exceed 30m / s; S23, determine the attenuation rate τ based on the filter element type.

[0014] In step S23, the attenuation rate of the paper filter element is 10%, the attenuation rate of the non-woven filter element is 8.5%, and the attenuation rate of the metal mesh filter element is negligible.

[0015] In step S3, when selecting the check valve, ensure that the valve body opening pressure is greater than 1.6 kPa and less than 2.5 kPa.

[0016] A fuel evaporative emission control system includes a fuel tank and a carbon canister, the carbon canister being connected to the fuel tank via a steam pipe, and also includes a carbon canister solenoid valve filter, one end of which is connected to the carbon canister via a steam pipe, and the other end of which is connected to the carbon canister solenoid valve via a steam pipe.

[0017] The carbon canister solenoid valve is connected to the engine, and the controller is electrically connected to the carbon canister solenoid valve to control the opening and closing of the carbon canister solenoid valve.

[0018] Compared with the prior art, the present invention has the following beneficial effects: The carbon canister solenoid valve filter and its design method and fuel evaporation emission control system of the present invention can effectively solve the defects of existing filter devices that lack systematic design methods and cause desorption failure due to increased resistance after long-term use. It provides a quantitative design method for filter parameters with theoretical basis, ensuring the rationality and accuracy of engineering design selection, and has strong practicality and good application prospects. Attached Figure Description

[0019] The following is a brief explanation of the contents depicted in the accompanying drawings and the markings therein:

[0020] Figure 1 This is a schematic diagram of the evaporation emission control system of the present invention;

[0021] Figure 2 This is a flowchart illustrating the design steps of the carbon canister solenoid valve filter of the present invention.

[0022] The diagram is marked as follows:

[0023] 1. Carbon canister solenoid valve filter; 11. Filter; 12. Check valve;

[0024] 2. Fuel tank; 3. Carbon canister; 4. Carbon canister solenoid valve; 5. Controller; 6. Engine; 7. Steam pipe. Detailed Implementation

[0025] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to specific embodiments.

[0026] It should be noted that, unless otherwise defined, the technical or scientific terms used in this invention should have the ordinary meaning understood by one of ordinary skill in the art to which this invention pertains. The terms "first," "second," and similar terms used in this invention do not indicate any order, quantity, or importance, but are merely used to distinguish different components. Terms such as "comprising" or "including" mean that the element or object preceding the word encompasses the elements or objects listed following the word and their equivalents, without excluding other elements or objects. Terms such as "connected" or "linked" are not limited to physical or mechanical connections, but can include electrical connections, whether direct or indirect. Terms such as "upper," "lower," "left," and "right" are used only to indicate relative positional relationships; when the absolute position of the described object changes, the relative positional relationship may also change accordingly.

[0027] The present invention relates to a carbon canister solenoid valve filter 1, which is arranged between a carbon canister 3 and a carbon canister solenoid valve 4. The filter is connected upstream to the carbon canister 3 via a steam pipe 7, and downstream to the carbon canister solenoid valve 4 via a steam pipe 7. The carbon canister solenoid valve filter 1 includes a filter 11 and a one-way valve 12, which are connected in parallel. Figure 1 As shown in the image.

[0028] Filter 11 is used to filter carbon particles entrained in the steam flowing from the carbon canister desorption port. Filter 11 contains a filter element, which is selected from one of the following: paper filter element, non-woven fabric filter element, metal mesh filter element, ceramic filter element, sintered metal filter element, or composite fiber filter element. The filter element is fixed to the filter housing by snap-fit, threaded, welded, or riveted connection.

[0029] The check valve 12 is used to open when the internal resistance of the filter exceeds a preset value, allowing airflow to bypass through the check valve. The opening pressure of the check valve 12 is greater than 1.6 kPa and less than 2.5 kPa. The check valve 12 is selected from one of the following: spring-loaded check valve, diaphragm check valve, gravity check valve, or solenoid check valve.

[0030] When the filter 11 is working normally, the airflow mainly enters the carbon canister solenoid valve 4 after being filtered by the filter 11. When the internal resistance of the filter 11 becomes too high due to long-term use, the one-way valve 12 opens to bypass the filter and prevent the carbon canister from desorbing and failing.

[0031] This invention discloses a design method for a carbon canister solenoid valve filter. For example... Figure 2 As shown, the present invention provides a design method for a carbon canister solenoid valve filter, comprising the following steps:

[0032] S1. Calculate the minimum filter volume.

[0033] Given the engine displacement W (in liters) and the number of engine cylinders N, calculate the minimum filter volume V using the following formula:

[0034]

[0035] In the formula: V—minimum filter volume, unit: L;

[0036] W – Engine displacement, unit: L;

[0037] N – Number of engine cylinders, unit: cylinders.

[0038] The derivation of this formula is based on the following:

[0039] Gasoline engines use a four-stroke working cycle. The crankshaft rotates twice to complete a complete working cycle (intake, compression, power, exhaust). Each cylinder completes only one intake stroke every two weeks. Theoretically, the volume of gas drawn in during the intake stroke is equal to the cylinder's working volume (i.e., displacement divided by the number of cylinders).

[0040] The carbon canister desorption process utilizes the intake manifold vacuum generated during the engine's intake stroke to draw gasoline vapor stored in the carbon canister into the engine. Therefore, the desorption gas flow rate is directly related to the engine's intake volume.

[0041] In multi-cylinder engines, the intake strokes of each cylinder are staggered. Taking a four-cylinder engine as an example, each cylinder completes one intake stroke every two weeks. The total amount of desorbed gas entering the engine per unit time is theoretically the sum of the intake volumes of all cylinders divided by the cycle time. To ensure that the filter has sufficient volume to accommodate carbon particles, while also considering vehicle layout space and cost, this invention defines the minimum filter volume as being directly proportional to the engine displacement and inversely proportional to twice the number of cylinders.

[0042] The theoretical basis for the formula is as follows:

[0043] (1) Intake Volume Standard for Four-Stroke Engines: A four-stroke gasoline engine requires two crankshaft rotations to complete one full working cycle. In each working cycle, each cylinder completes only one intake stroke, and the theoretical volume of fresh air drawn in during the intake stroke is equal to the working volume of that cylinder (i.e., displacement divided by the number of cylinders). Therefore, the intake volume per cylinder in a single stroke is... .

[0044] (2) Intermittent nature and volume requirements of the desorption process: To ensure that the airflow entering the filter is adequately buffered and that the carbon particles have sufficient settling and containment space, the filter volume must be related to the intake volume of a single cylinder. Considering the overlapping effect of the intake strokes of each cylinder and for engineering simplification, half of the intake volume of a single cylinder is taken as the volume calculation benchmark, i.e. .

[0045] (3) Carbon powder holding space requirement: The volume calculated by the above formula not only takes into account the volume requirement of the desorbed gas, but more importantly, it provides sufficient internal space for the filter to hold the intercepted carbon powder particles. The amount of tiny carbon powder particles generated by the carbon canister during long-term use is about 0.5%-1.0% of the total carbon powder mass of the carbon canister. Based on this ratio, the above volume can ensure that the filter will not be blocked by carbon powder accumulation within a service life of 150,000 kilometers.

[0046] (4) Engineering verification basis: This formula is derived from bench test data of multiple engine platforms (displacement 1.0L-3.0L, number of cylinders 3-6). Durability tests have verified that the volume calculated using this formula can meet the service life requirement of 150,000 kilometers.

[0047] After rounding the calculation results, a filter model is made based on the vehicle layout boundary. The actual volume should be greater than or equal to the minimum filter volume V.

[0048] S2. Calculate the minimum flow diameter at the filter inlet and outlet.

[0049] Given the engine's maximum intake air volume Q (unit: ) and the maximum airflow velocity limit Vmax within the system (unit: ), calculate the minimum flow diameter D of the filter inlet and outlet according to the following formula:

[0050]

[0051] Where: D—minimum flow diameter of the filter inlet and outlet, unit: m;

[0052] Q – Maximum engine intake air volume, unit: (When calculating, it is necessary to include) Converted to );

[0053] Vmax — Maximum airflow velocity within the system, unit: ;

[0054] —Filter element attenuation rate, dimensionless.

[0055] The derivation of this formula is based on the following:

[0056] According to the continuity equation (law of conservation of mass) for one-dimensional steady flow in fluid mechanics, the volumetric flow rate through any cross-section of a pipe is equal to the product of the flow velocity and the cross-sectional area:

[0057] (1)

[0058] In the formula, Q is the volumetric flow rate ( A is the cross-sectional area of ​​the pipeline ( V is the average flow velocity across the cross section. ).

[0059] The formula for the area of ​​a circular cross-section is:

[0060] (2)

[0061] Substituting equation (2) into equation (1), we get:

[0062] (3)

[0063] Considering the impact of filter element resistance on the flow cross-section, the attenuation rate is introduced. (i.e., effective flow area coefficient), the corrected equivalent flow diameter is:

[0064] (4)

[0065] Right now (5)

[0066] Substituting equation (5) into equation (3), we get:

[0067] (6)

[0068] After sorting, we get:

[0069] (7)

[0070] The maximum airflow velocity within the system must not exceed the limit Vmax, therefore:

[0071] (8)

[0072] The parameters in the formula are determined based on the following:

[0073] (1) Maximum intake volume of engine Q: Based on the engine bench test data, the maximum intake volume under each speed condition is selected.

[0074] (2) Maximum airflow velocity Vmax in the system: should not exceed 30 m / s. According to the Darcy-Weisbach formula, the friction loss along the pipeline is proportional to the square of the velocity, and the local friction loss is also proportional to the square of the velocity. When the velocity exceeds 30 m / s, the system flow resistance will increase sharply, resulting in a significant decrease in the carbon canister desorption flow rate and affecting the desorption efficiency. At the same time, the sound power of airflow noise is proportional to the sixth to eighth power of the velocity. When the velocity exceeds 30 m / s, the noise increases sharply, affecting the overall NVH performance of the vehicle. Through experimental verification, this limit can ensure that the increase in system flow resistance does not exceed 0.5 kPa and the reduction in desorption efficiency does not exceed 5%.

[0075] (3) Filter element attenuation rate τ: Considering the resistance effect of the filter element itself on the airflow, the attenuation rate of different types of filter elements is determined by the filter element unit pressure drop flow characteristic test:

[0076] The paper filter cartridge has a decay rate of 10% ( (0.90), the flow resistance effect of paper filter material with interwoven fiber structure on airflow;

[0077] The attenuation rate of the non-woven filter element is 8.5% ( The resistance is 0.915, because its fiber arrangement is more uniform and its porosity is higher, resulting in slightly lower resistance than paper filter cartridges;

[0078] The attenuation rate of the metal mesh filter element is negligible. Approximately 1), due to the use of a woven mesh structure, the pores are regular and the porosity is high.

[0079] After rounding the calculation results, the actual inlet and outlet flow diameters of the filter should be greater than or equal to the calculated minimum flow diameter D.

[0080] Step S2 includes the following sub-steps:

[0081] S21. Based on the engine bench data, select the maximum intake volume Q;

[0082] S22. Determine the maximum limit value of airflow velocity Vmax in the system, preferably not exceeding 30m / s;

[0083] S23. Determine the attenuation rate τ based on the filter element type.

[0084] S3, Check Valve Selection

[0085] The one-way valve is a bypass safety valve. In extreme cases, when the carbon canister solenoid valve filter becomes clogged and fails, the desorption airflow overcomes the spring pressure of the one-way valve, opens the valve body, and ensures the basic desorption function of the carbon canister.

[0086] Ventilation resistance is typically evaluated using a flow rate of 60 L / min. Generally, when the resistance of the carbon canister solenoid valve filter exceeds 1.6 kPa, the desorption efficiency is considered low. Therefore, when selecting a check valve, it should open at a desorption pressure of 1.6 kPa to ensure basic desorption functionality. When the ventilation resistance exceeds 2.5 kPa, desorption essentially fails due to the limited vacuum in the intake manifold. Therefore, when selecting a check valve, the valve opening pressure should be greater than 1.6 kPa and less than 2.5 kPa.

[0087] The selection of the opening pressure range is based on the following: During the carbon canister desorption process, the normal operating pressure of the pipeline system is usually in the range of 1.0-1.5 kPa. When the opening pressure of the check valve is lower than 1.6 kPa, it may be opened erroneously under normal desorption conditions, causing unfiltered gas to directly enter the carbon canister solenoid valve. When the opening pressure is higher than 2.5 kPa, when the filter resistance increases to the point where bypass is required, the check valve cannot open in time and loses its protective function.

[0088] like Figure 1 As shown, the present invention also provides a fuel evaporation emission control system, comprising:

[0089] Fuel tank 2 is connected to carbon canister 3 via steam pipe 7; carbon canister 3 is connected to carbon canister solenoid valve filter 1 via steam pipe 7; carbon canister solenoid valve filter 1 is connected to carbon canister solenoid valve 4 via steam pipe 7; carbon canister solenoid valve 4 is connected to engine 6 via steam pipe 7; controller 5 (ECU) is electrically connected to carbon canister solenoid valve 4 and is used to control the opening and closing of carbon canister solenoid valve 4.

[0090] Optionally, the filter 11 of the carbon canister solenoid valve filter 1 is equipped with a filter element, the filter element having a filtration accuracy of 30-40μm.

[0091] This invention adds a carbon canister solenoid valve filter between the carbon canister and the solenoid valve. The filter element effectively intercepts tiny carbon particles entrained in the steam (filtration accuracy up to 30-40μm), preventing them from entering the solenoid valve and fundamentally eliminating the risk of carbon powder accumulation and adhesion causing the solenoid valve to jam. When the vehicle's mileage exceeds 40,000 kilometers, disassembling the solenoid valve reveals no carbon powder accumulation or adhesion inside the valve core, eliminating the risk of short-mileage jamming.

[0092] The carbon canister solenoid valve filter of the present invention adopts a layout structure in which the filter and the one-way valve are connected in parallel. When the internal resistance of the filter increases after long-term use, the one-way valve can automatically open to bypass the filter, ensuring smooth airflow for carbon canister desorption, preventing carbon canister desorption failure under extreme conditions, and improving the reliability and service life of the system.

[0093] This invention provides a complete design and selection method for carbon canister solenoid valve filters, including formulas for calculating the minimum filter volume, the minimum flow diameter of the filter inlet and outlet, and the selection range for the opening pressure of the check valve. These design formulas are based on the working cycle principle of a four-stroke engine and the fluid dynamics continuity equation, enabling reasonable and accurate selection of filters and check valves in the early design stage, thus changing the extensive design mode that relies on experience estimation in the prior art.

[0094] This invention effectively reduces the system flow resistance and airflow noise introduced by the filter by optimizing the airflow velocity within the system (not exceeding 30m / s), ensuring that the working performance and NVH performance of the evaporative emission control system are not affected.

[0095] This invention reduces the risks of increased vehicle fuel consumption, engine vibration, cold start stalling, and environmental pollution caused by stuck carbon canister solenoid valves. At the same time, it improves the service life of carbon canister solenoid valves and reduces after-sales maintenance and replacement costs.

[0096] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0097] Example 1: Design of Carbon Canister Solenoid Valve Filter and Fuel Evaporation Emission Control System for a 1.6L Four-Cylinder Engine

[0098] This embodiment takes a 1.6L gasoline engine with 4 cylinders as an example to design and select a carbon canister solenoid valve filter and build a fuel evaporation emission control system.

[0099] like Figure 1 As shown, in the fuel evaporative emission control system with the carbon canister solenoid valve filter described in this invention, the fuel tank 2 is connected to the carbon canister 3 via a steam pipe 7; the carbon canister 3 is connected to the carbon canister solenoid valve filter 1 via a steam pipe 7; the carbon canister solenoid valve filter 1 is connected to the carbon canister solenoid valve 4 via a steam pipe 7; the carbon canister solenoid valve 4 is connected to the engine 6 via a steam pipe 7; and the controller 5 is electrically connected to the carbon canister solenoid valve 4.

[0100] The carbon canister solenoid valve filter 1 includes a filter 11 and a one-way valve 12, which are connected in parallel. The filter 11 is filled with a paper pleated filter element with a filtration accuracy of 30-40μm, used to filter out small carbon particles entrained in the steam. The one-way valve 12 is a spring-loaded one-way valve with an opening pressure set at 2.0kPa.

[0101] Design calculation process:

[0102] (1) Calculation of minimum filter volume

[0103] Given that the engine displacement W = 1.6L and the number of cylinders N = 4.

[0104] According to the formula V=W / (2×N)=1.6 / (2×4)=0.2L

[0105] The calculated result is rounded to 0.2L. Based on the overall vehicle layout boundary, the designed internal volume of the filter housing is 0.25L (the actual volume is greater than the minimum volume of 0.2L).

[0106] (2) Calculation of minimum flow diameter at filter inlet and outlet

[0107] Based on engine bench test data, the intake air volume at each speed is selected as follows:

[0108] 1000 17.328 1250 27.024 1500 60.768 1750 75.632 2000 87.152 2250 94.96 2500 104.272 3000 109.856 3500 134.496 4000 151.328 4500 169.696 5000 190.4 5600 217.024 6000 240.5

[0109] The maximum intake volume was selected as Q=240.5. =0.067 .

[0110] The maximum airflow velocity within the system is determined to be Vmax = 30 m / s.

[0111] This embodiment uses a paper filter element with an attenuation rate τ=0.90.

[0112] According to the formula :

[0113]

[0114] The calculated value is D≈9.60mm. After rounding, the inlet and outlet flow diameter of the filter is determined to be 10mm (greater than the minimum diameter of 9.60mm).

[0115] (3) Selection of one-way valve

[0116] Based on the opening pressure range of 1.6kPa-2.5kPa, a spring-loaded check valve with an opening pressure of 2.0kPa is selected.

[0117] The working process of a fuel evaporative emission control system with a carbon canister solenoid valve filter is as follows:

[0118] Gasoline vapor in fuel tank 2 enters carbon canister 3 for temporary storage via vapor pipe 7. Under suitable operating conditions, controller 5 controls carbon canister solenoid valve 4 to open, and under the negative pressure generated during the intake stroke of engine 6, the gasoline vapor stored in carbon canister 3 is delivered to engine 6 for combustion. During this desorption process, the gasoline vapor first passes through filter 11 along vapor pipe 7. Tiny carbon particles entrained in the vapor are effectively intercepted by the paper pleated filter element (filtration accuracy can reach 30-40μm), and the clean gasoline vapor flows through carbon canister solenoid valve 4 into the engine for combustion.

[0119] After a vehicle has been used for more than 10 years or 150,000 kilometers, the carbon powder accumulated inside the filter 11 may increase the airflow resistance. When the pressure drop caused by the filter resistance exceeds the opening pressure (2.0 kPa) of the one-way valve 12, the one-way valve 12 automatically opens, and part of the airflow bypasses the one-way valve, ensuring that the carbon canister desorption process does not fail due to filter blockage. At this time, because the filter and the one-way valve are connected in parallel, some airflow still passes through the filter, and the system can still maintain a certain filtration function.

[0120] Bench tests verified that, after adopting the filter device designed in this embodiment, the amount of carbon powder accumulated inside the carbon canister solenoid valve after a simulated life test of 150,000 kilometers was reduced by more than 95% compared to when no filter was installed. Simultaneously, throughout the entire test cycle, no desorption failure due to excessive filter resistance occurred, and the one-way valve reliably opened when the filter pressure drop rose to 2.0 kPa, indicating normal system operation.

[0121] Example 2: Design of Carbon Canister Solenoid Valve Filter and Fuel Evaporation Emission Control System for a 2.0L Four-Cylinder Engine

[0122] This embodiment takes a 2.0L gasoline engine with 4 cylinders as an example to design and select a carbon canister solenoid valve filter.

[0123] Design calculation process:

[0124] (1) Calculation of minimum filter volume

[0125] Given that the engine displacement W = 2.0L and the number of cylinders N = 4.

[0126] According to the formula V = W / (2×N)=2.0 / (2×4)=0.25L

[0127] The calculated result is rounded to 0.25L. Based on the overall vehicle layout boundaries, the designed internal volume of the filter housing is 0.30L.

[0128] (2) Calculation of minimum flow diameter at filter inlet and outlet

[0129] Based on engine bench data, the maximum intake air volume Q=300 was selected. =0.0833 .

[0130] The maximum airflow velocity within the system is determined to be Vmax = 30 m / s.

[0131] This embodiment uses a non-woven fabric filter element with an attenuation rate τ=0.915.

[0132] According to the formula :

[0133] The calculated value is D≈10.88mm. After rounding, the inlet and outlet flow diameter of the filter is determined to be 11mm.

[0134] (3) Selection of one-way valve

[0135] A spring-loaded check valve with an opening pressure of 1.8 kPa was selected.

[0136] In this embodiment, the housing of filter 11 can adopt a split structure, consisting of an upper housing and a lower housing connected by threads or snaps, and the internal filter element can be removed and replaced. This structural design facilitates filter element replacement during vehicle maintenance, extending the overall service life of the filter. The one-way valve 12 is a diaphragm-type one-way valve, characterized by fast response and stable opening pressure.

[0137] Example 3: Design of Carbon Canister Solenoid Valve Filter and Fuel Evaporation Emission Control System for a 1.5L Three-Cylinder Engine

[0138] This embodiment takes a 1.5L gasoline engine with 3 cylinders as an example to design and select a carbon canister solenoid valve filter.

[0139] Design calculation process:

[0140] (1) Calculation of minimum filter volume

[0141] Given that the engine displacement W = 1.5L and the number of cylinders N = 3.

[0142] According to the formula V=W / (2×N)=1.5 / (2×3)=0.25L

[0143] The calculated result is rounded to 0.25L. Based on the overall vehicle layout boundaries, the designed internal volume of the filter housing is 0.28L.

[0144] (2) Calculation of minimum flow diameter at filter inlet and outlet

[0145] Based on engine bench data, the maximum intake air volume Q = 200.0 was selected. =0.0556 .

[0146] The maximum airflow velocity limit within the system is determined to be Vmax = 25 m / s (in this embodiment, the velocity limit is set to be below 30 m / s to optimize NVH performance).

[0147] This embodiment uses a metal mesh filter element (stainless steel woven mesh) with an attenuation rate τ≈1.0.

[0148] According to the formula :

[0149] The calculated value is D≈10.64mm. After rounding, the inlet and outlet flow diameter of the filter is determined to be 11mm.

[0150] (3) Selection of one-way valve

[0151] A spring-loaded check valve with an opening pressure of 2.2 kPa was selected.

[0152] This embodiment uses a metal mesh filter element instead of a paper or non-woven fabric filter element. Metal mesh filters offer the following advantages: they are washable and reusable, with a long service life; they have a very low attenuation rate, barely increasing system flow resistance; and their filtration accuracy can be adjusted via the mesh size (this embodiment uses a 200-mesh stainless steel woven mesh, with a filtration accuracy of approximately 74μm, effectively intercepting most carbon particles). Metal mesh filters can serve as an effective alternative to paper and non-woven fabric filter elements.

[0153] Comparative Example 1: Lifespan Comparison of Carbon Canister Solenoid Valves Without Filters

[0154] This comparative example is based on the 1.6L four-cylinder engine described in Example 1, without any filter device installed, and the carbon canister solenoid valve is directly connected to the carbon canister desorption port through a steam pipe.

[0155] Under the same bench test conditions, after simulating 40,000 kilometers of vehicle driving, the carbon canister solenoid valve was disassembled to inspect the valve core condition. The results showed that a large amount of black carbon powder particles had accumulated in the internal cavity of the carbon canister solenoid valve, with a carbon powder layer thickness of approximately 0.5~1.0 mm. There were obvious carbon powder adhesion marks on the valve core surface, and the valve core's movement resistance increased by approximately 40% compared to its initial state. Continuing to operate for 60,000 kilometers, the carbon canister solenoid valve exhibited intermittent jamming; the valve core could not open normally in the normally closed position, resulting in ineffective carbon canister desorption and the engine malfunction indicator lamp illuminating.

[0156] This comparative example shows that without a filter, toner particles can directly enter the solenoid valve of the toner canister, and significant accumulation begins around 40,000 kilometers, leading to solenoid valve jamming around 60,000 kilometers, which is consistent with the failure mileage range reported in the market.

[0157] Comparative Example 2: Scheme using a single filter (without parallel check valves)

[0158] This comparative example is based on the 1.6L four-cylinder engine described in Example 1. Only a filter (without a parallel check valve) is installed between the carbon canister and the carbon canister solenoid valve. The volume and inlet / outlet diameter of the filter are determined according to the design parameters of Example 1.

[0159] In the initial stage of bench testing (simulated mileage of 0-100,000 km), the filter operated normally, effectively intercepting carbon particles, and the internal structure of the carbon canister solenoid valve remained clean and without abnormalities. However, after 120,000 km of simulated mileage, the amount of carbon powder accumulated inside the filter gradually increased, leading to increased venting resistance. At 150,000 km, the pressure difference between the filter inlet and outlet reached 2.8 kPa, exceeding the normal operating pressure difference range of the carbon canister desorption system. This resulted in a significant decrease in the carbon canister desorption flow rate and a reduction in desorption efficiency of approximately 25%. Continuing operation to 160,000 km, the desorption flow rate continued to decrease, the carbon canister showed signs of saturation, and the risk of gasoline vapor escaping from the carbon canister vent increased significantly.

[0160] This comparative example illustrates that while a single filter structure can effectively protect the carbon canister solenoid valve, increased filter resistance over long-term use may lead to desorption failure, and the system lacks a failure protection mechanism. In contrast, this invention employs a parallel structure of a filter and a check valve. When the filter resistance increases to the point exceeding the check valve's opening pressure, the check valve automatically opens to bypass, ensuring uninterrupted desorption and resulting in higher system reliability.

[0161] Comparative Example 3: A solution where the opening pressure of the one-way valve exceeds the scope of this invention.

[0162] This comparative example is based on the 1.6L four-cylinder engine described in Example 1. In the structure of the filter and the one-way valve connected in parallel, the opening pressure of the selected one-way valve is 3.5kPa (higher than the upper limit of 2.5kPa recommended by this invention).

[0163] In bench tests, when the simulated mileage exceeded 120,000 kilometers and the filter differential pressure rose to approximately 3.0 kPa, the desorption flow rate began to decrease because the check valve opening pressure was 3.5 kPa and it had not yet opened, resulting in reduced system efficiency. Continuing operation to approximately 140,000 kilometers, the filter differential pressure reached 3.5 kPa, and the check valve opened. However, the desorption efficiency was already somewhat affected, and the filter element may have suffered partial damage due to prolonged operation under high differential pressure, leading to partial failure of the filtration function.

[0164] This comparative example illustrates that excessively high check valve opening pressure can cause delayed intervention of the bypass protection function. Even when filter resistance significantly impacts system efficiency, the check valve may still fail to open in time, thus negating its intended bypass protection function. This invention limits the check valve opening pressure to no more than 2.5 kPa, ensuring the timeliness and effectiveness of the bypass protection function.

[0165] Comparative Example 4: A scheme where the filter volume is smaller than the calculated value of this invention.

[0166] This comparative example is based on the 1.6L four-cylinder engine described in Example 1, with the filter volume reduced to 0.10L (approximately 50% of the calculated value of 0.2L in this invention), while the inlet and outlet flow diameters remain unchanged.

[0167] In bench tests, the filter operated normally initially (0-80,000 km). However, due to its small volume and insufficient internal effective filtration area and toner capacity, the toner buildup inside the filter approached saturation between 80,000 and 100,000 km, forming a thick layer of toner on the filter element surface, causing a rapid increase in airflow resistance. By 100,000 km, the filter pressure differential had reached 2.5 kPa, and the check valve began to open. By 120,000 km, the filter essentially failed, with most airflow bypassing through the check valve, resulting in a significant decrease in filtration function.

[0168] This comparative example illustrates that insufficient filter volume significantly shortens the effective lifespan of the filter, causing it to reach saturation prematurely, leading to frequent opening of the check valve and a decline in overall filtration efficiency. This invention calculates the minimum filter volume using the formula V=W / (2N), ensuring the filter has sufficient space to hold toner and a reasonable lifespan.

[0169] The technical solution of the present invention can be modified and substituted in various ways without departing from the inventive concept. Some alternative solutions are listed below.

[0170] Filter type alternatives:

[0171] (1) In addition to paper filter elements, non-woven filter elements and metal mesh filter elements, ceramic filter elements, sintered metal filter elements or composite fiber filter elements can also be used as filter media. Ceramic filter elements have the characteristics of high temperature resistance and corrosion resistance, and are suitable for filtration needs in high temperature environments; sintered metal filter elements have the advantages of high strength and can be washed and reused, and are suitable for occasions that require long service life design; composite fiber filter elements have the characteristics of high filtration accuracy and low resistance, and are the preferred solution for high performance applications.

[0172] (2) The filter element can be fixed by snap-fit, threaded, welded or riveted. Snap-fit ​​is convenient for filter element replacement, threaded connection is reliable, and welded and riveted are suitable for filter designs that require one-time replacement.

[0173] Alternatives to filter structure:

[0174] (1) The filter housing can be an integrated structure or a split structure. The integrated structure has good sealing performance and low cost, and is suitable for the design of replacing the filter element and the housing as a whole; the split structure consists of an upper housing and a lower housing, which are connected by threaded connection, snap connection or flange connection, which facilitates the individual replacement of the internal filter element and the reuse of the housing.

[0175] (2) The filter inlet and outlet can be arranged on the same side, opposite side, or vertically. The same side arrangement is suitable for the arrangement space where the pipeline direction is limited; the opposite side arrangement is conducive to the uniform distribution of airflow and reduces local resistance; the vertical arrangement is suitable for specific installation direction requirements.

[0176] One-way valve alternatives:

[0177] (1) Check valves can be spring-loaded, diaphragm-loaded, gravity-loaded, or electromagnetic. Spring-loaded check valves are simple in structure and low in cost, and are suitable for general applications; diaphragm-loaded check valves have fast response speed and good sealing performance; gravity-loaded check valves rely on the weight of the valve disc to achieve closure, and have high reliability; electromagnetic check valves can be actively controlled by electrical control, and are suitable for systems with a high degree of intelligence.

[0178] (2) The one-way valve can be installed either as a built-in type (integrated into the filter housing) or an external type (independently installed on the external pipeline of the filter). The built-in type has a high degree of integration and occupies little space; the external type is convenient for individual maintenance and replacement.

[0179] Alternative design parameters:

[0180] (1) The maximum airflow velocity Vmax in the system can be adjusted according to the NVH requirements and system flow resistance requirements of the specific vehicle model. The typical range is 20 to 30 m / s. For vehicles with high NVH requirements, a lower velocity value can be selected; for vehicles with limited layout space, a higher velocity value can be selected on the premise of meeting the flow resistance requirements.

[0181] (2) The filter element attenuation rate τ should be determined by testing based on the actual filter element material selected. There may be differences between filter element materials from different suppliers and different batches. It is recommended to reserve a certain margin in the design.

[0182] This invention relates to a carbon canister solenoid valve filter, its design method, and a fuel evaporative emission control system, which can be widely applied to fuel evaporative emission control systems in various gasoline vehicles. The design method provided by this invention has clear engineering calculation basis, is applicable to engine platforms with different displacements and cylinder numbers, and has good versatility and portability. The filter device described in this invention has a simple structure, controllable cost, and high reliability. It can be directly installed without changing the overall architecture of the original evaporative emission control system, and has good industrial application prospects and market promotion value.

[0183] This invention relates to a carbon canister solenoid valve filter, its design method, and a fuel evaporation emission control system. It can effectively solve the defects of existing filter devices, such as the lack of a systematic design method and the increase in resistance leading to desorption failure after long-term use. It provides a quantitative design method for filter parameters with theoretical basis, ensuring the rationality and accuracy of engineering design selection, and has strong practicality and good application prospects.

[0184] Those skilled in the art should understand that the discussion of any of the above embodiments is merely exemplary and is not intended to imply that the scope of the invention (including the claims) is limited to these examples; within the framework of the invention, the technical features of the above embodiments or different embodiments can also be combined, the steps can be implemented in any order, and there are many other variations of the different aspects of the invention as described above, which are not provided in detail for the sake of brevity.

[0185] This invention is intended to cover all such substitutions, modifications, and variations that fall within the broad scope of the appended claims. Therefore, any omissions, modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this invention should be included within the scope of protection of this invention.

[0186] The present invention has been described above by way of example with reference to the accompanying drawings. However, the present invention is not limited to the above-described manner. Any non-substantial improvements made using the inventive concept and technical solution of the present invention or any direct application to other situations shall fall within the protection scope of the present invention.

Claims

1. A carbon canister solenoid valve filter, comprising a filter for filtering carbon powder particles entrained in steam flowing from the carbon canister desorption port, characterized in that: It also includes a one-way valve, which opens when the internal resistance of the filter exceeds a preset value, allowing airflow to bypass through the one-way valve; the carbon canister solenoid valve filter is arranged between the carbon canister and the carbon canister solenoid valve.

2. The carbon canister solenoid valve filter according to claim 1, characterized in that: The opening pressure of the one-way valve is greater than 1.6 kPa and less than 2.5 kPa.

3. The carbon canister solenoid valve filter according to claim 1, characterized in that: The filter contains a filter element, which is selected from one of the following: paper filter element, non-woven fabric filter element, metal mesh filter element, ceramic filter element, sintered metal filter element, or composite fiber filter element; the filter element is fixed to the filter housing by snap-fit, threaded, welded, or riveted connection.

4. The carbon canister solenoid valve filter according to claim 1, characterized in that: The check valve is one of the following: spring-loaded check valve, diaphragm check valve, gravity check valve, or solenoid check valve.

5. A design method for a carbon canister solenoid valve filter as described in any one of claims 1 to 4, characterized in that, The process includes the following steps: S1, calculate the minimum filter volume V; S2, calculate the minimum flow diameter D of the filter inlet and outlet; S3, select a check valve.

6. The design method of the carbon canister solenoid valve filter according to claim 5, characterized in that: In step S1, given the engine displacement W and the number of engine cylinders N, the minimum filter volume is calculated using the following formula. .

7. The design method of the carbon canister solenoid valve filter according to claim 5, characterized in that: In step S2, given the engine's maximum intake air volume Q and the system's maximum airflow velocity limit Vmax, the minimum flow diameters of the filter inlet and outlet are calculated using the following formula. ,in This refers to the filter element attenuation rate.

8. The design method of the carbon canister solenoid valve filter according to claim 5, characterized in that, Step S2 includes the following sub-steps: S21, based on engine bench data, select the maximum intake volume Q; S22, determine the maximum airflow velocity limit Vmax in the system, wherein Vmax does not exceed 30m / s; S23, determine the attenuation rate τ based on the filter element type.

9. The design method of the carbon canister solenoid valve filter according to claim 8, characterized in that: In step S23, the attenuation rate of the paper filter element is 10%, the attenuation rate of the non-woven filter element is 8.5%, and the attenuation rate of the metal mesh filter element is negligible.

10. The design method of the carbon canister solenoid valve filter according to claim 5, characterized in that: In step S3, when selecting the check valve, ensure that the valve body opening pressure is greater than 1.6 kPa and less than 2.5 kPa.

11. A fuel evaporative emission control system, comprising a fuel tank and a carbon canister, wherein the carbon canister is connected to the fuel tank via a steam pipe, characterized in that: It also includes a carbon canister solenoid valve filter as described in any one of claims 1 to 4, wherein one end of the carbon canister solenoid valve filter is connected to the carbon canister via a steam pipe, and the other end is connected to the carbon canister solenoid valve via a steam pipe.

12. The fuel evaporation emission control system according to claim 11, characterized in that: The carbon canister solenoid valve is connected to the engine, and the controller is electrically connected to the carbon canister solenoid valve to control the opening and closing of the carbon canister solenoid valve.

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