Fuel Evaporation Leakage Detection System and Detection Method for Engines

Abstract

This invention provides a fuel evaporative emission leakage detection system and method for engines. The detection system includes a fuel tank, a carbon canister, a diagnostic tool, and a pressure detection device. The carbon canister is fluidly connected to both the fuel tank and the engine's intake system. The diagnostic tool includes an inlet and an outlet, and forms a first ventilation path and a second ventilation path within it. The first ventilation path directly connects the inlet and outlet, while the second ventilation path sequentially connects the inlet to a pressurization assembly, a one-way valve, and the outlet. A pipeline switching assembly switches between the first and second ventilation paths within the diagnostic tool based on detection requirements to achieve airflow connection between the inlet and outlet. This allows for pressurization or pressure maintenance of the carbon canister as needed, facilitating the acquisition of system pressure information and determining the system's operating status based on this pressure information. It also reduces the reliability requirements of the diagnostic pump, minimizes susceptibility to external interference, and provides accurate detection results.

Description

Technical Field

[0001] This invention relates to the field of vehicle technology, and more particularly to the field of vehicle system testing technology. Specifically, it relates to a fuel evaporation emission leakage detection system and method for engines. Background Technology

[0002] The existing method for leak detection in fuel evaporative emission systems involves installing a DMTL (Digital Deposition and Transmission) module within the system. This module consists of a motor-driven rotary vane pump and a solenoid valve. The module's internal flow channels include a main chamber open to the atmosphere and a high-pressure chamber. The high-pressure chamber has a reference orifice for calibration. The DMTL leak diagnosis module operates in two modes: reference mode and diagnostic mode, switched using a solenoid valve. By energizing the solenoid coil within the valve, the electromagnetic force drives the iron core and valve together, opening and closing the valve. Switching the solenoid valve allows for two operating conditions: either the rotary vane pump pumps air through the reference orifice, or the pumps air through the entire evaporative emission system. The motor current of the rotary vane pump is compared between these two conditions to determine if a leak larger than 0.5 mm is present. However, since the diagnostic current of the rotary vane pump is relatively small, ranging from 20 to 50 mA, the diagnostic results are greatly affected by the environment, especially factors such as air humidity, the friction of the rotary vane pump, wear, and foreign object jamming. Based on actual market feedback, the probability of misdiagnosis is relatively high.

[0003] Therefore, existing technologies suffer from the technical problems of being highly susceptible to environmental influences and having a high rate of misdiagnosis. Summary of the Invention

[0004] The main objective of this invention is to provide a fuel evaporation emission leakage detection system for engines, in order to solve the technical problems of existing diagnostic methods being greatly affected by the environment and having a high misdiagnosis rate.

[0005] To achieve the above objectives, according to one aspect of the present invention, a fuel evaporative emission leak detection system for an engine is provided, comprising a fuel tank, a carbon canister, a diagnostic tool, and a pressure detection device, wherein the carbon canister is in fluid communication with both the fuel tank and the engine's intake system; a fuel tank isolation valve is provided between the carbon canister and the fuel tank; a carbon canister control valve is provided between the carbon canister and the engine, the carbon canister control valve being used to control the fluid communication between the carbon canister and the engine; the diagnostic tool includes an intake port and an outlet port, the intake port being open to the atmosphere. The air outlet is connected to the carbon canister. The diagnostic tool is equipped with a pressurization component, a one-way valve component, and a pipeline switching component. The diagnostic tool forms a first ventilation path and a second ventilation path connecting the air inlet and the air outlet. The first ventilation path directly connects the air inlet and the air outlet. The second ventilation path sequentially connects the air inlet to the pressurization component, the one-way valve, and the air outlet. The pipeline switching component switches the first ventilation path and the second ventilation path in the diagnostic tool based on the testing requirements to achieve airflow connection between the air inlet and the air outlet.

[0006] Furthermore, the pressure detection device is located inside the oil tank, in the pipeline between the oil tank isolation valve and the oil tank, or in the diagnostic tool.

[0007] Furthermore, the diagnostic device further includes: a housing, with an air inlet and an air outlet disposed on the housing; a first chamber and a second chamber formed within the housing; the first chamber and the second chamber respectively communicating with the air inlet; the air outlet communicating with the second chamber; and the first chamber communicating with the second chamber and the air outlet via a first pipeline; a pressurizing assembly fixedly connected to the housing, disposed on the side of the first chamber away from the first pipeline; a one-way valve assembly connected to the housing, disposed within the first chamber and located between the pressurizing assembly and the first pipeline; and a pipeline switching assembly located within the second chamber, used to control the fluid communication between the first pipeline and the second chamber, so that when the first pipeline is connected to the second chamber, the gas pressurized by the pressurizing assembly can sequentially pass through the one-way valve, the first pipeline, and the second chamber, finally leaving the housing from the air outlet and entering the carbon canister.

[0008] Furthermore, the pipeline switching assembly includes a solenoid valve, a sealing valve, and a return spring. One end of the return spring abuts against the elastic sealing part, and the other end of the return spring abuts against the first valve seat. The solenoid valve includes a fixed iron core and an armature. A through hole is provided in the center of the fixed iron core. At least a part of the sealing valve passes through the central through hole of the fixed iron core. Under the drive of electromagnetic force and the action of the return spring, the sealing valve reciprocates in the second chamber.

[0009] Furthermore, the sealing valve includes a valve stem, a sealing valve skeleton, and an elastic sealing part. One end of the valve stem passes through the central through hole of the fixed iron core, and the other end of the valve stem is detachably connected to the sealing valve skeleton. The elastic sealing part is connected to the sealing skeleton and can abut against the first valve seat under the action of the solenoid valve.

[0010] Furthermore, the one-way valve assembly includes a second valve seat, at least a portion of which is sealed and fixedly connected to the housing, the second valve seat having a mounting hole located at the center of the second valve seat and at least one vent hole located around the mounting hole; and an umbrella valve, the umbrella valve being fixedly connected to the second valve seat through the mounting hole, at least a portion of which is made of an elastic material, the elastic material covering the vent hole.

[0011] Furthermore, the second valve seat includes a body and a connecting portion. The connecting portion is a cylindrical shape with one end open, extending from the body toward the first pipeline. The outer wall of the connecting portion abuts and is fixed to the inner wall of the first pipeline.

[0012] According to another aspect of the present invention, a fuel evaporative emission leakage detection system for an engine is also provided, comprising a fuel tank, a carbon canister, a pressurizing device, a one-way valve, and a pressure detection device, wherein the carbon canister is connected to the fuel tank and the engine pipeline respectively, a fuel tank isolation valve is provided between the carbon canister and the fuel tank, the fuel tank isolation valve is used to control the pipeline connection between the fuel tank and the carbon canister, a first carbon canister control valve is provided between the carbon canister and the engine, the first carbon canister control valve is used to control the pipeline connection between the carbon canister and the engine, the pressure detection device is used to detect the internal pressure of the fuel tank, the carbon canister is connected to the pressurizing device through the one-way valve, the carbon canister is connected to the external air pipeline, and a second carbon canister control valve is provided between the carbon canister and the external air, the second carbon canister control valve is used to control the air path connection between the carbon canister and the external control.

[0013] According to another aspect of the present invention, the present invention also provides a method for detecting fuel evaporative emission leaks in an engine, the method employing the aforementioned detection system, the method comprising the following steps:

[0014] Close the air passage between the carbon canister and the outside air, and open the fuel tank isolation valve. Pressurize the internal pressure of the fuel tank to the first threshold P1 using the pressurization device. Record the time difference ∆t between the fuel tank pressure decreasing to the second threshold P2 and the third threshold P3. Compare the time difference ∆t with the system preset time. If the time difference ∆t is less than the system preset time, the system has a leak.

[0015] According to another aspect of the present invention, the present invention also provides a method for detecting fuel evaporative emission leaks in an engine, the method employing the aforementioned detection system and comprising the following steps:

[0016] Close the air passage between the carbon canister and the outside air, and open the fuel tank isolation valve. Use the pressurization device to pressurize the internal pressure of the fuel tank to the first threshold P1; calculate the integral value S of the fuel tank pressure P from the moment it reaches the second threshold P2 to the moment it reaches the third threshold P3, i.e. The integral value S is compared with a system preset value. If the integral value S is less than the system preset value, the system has a leakage.

[0017] The fuel evaporative emission leakage detection system for engines provided in this application can control the carbon canister system pipeline by controlling the carbon canister control valve and the fuel tank isolation valve. The pipeline switching component can connect different air paths between the inlet and outlet of the diagnostic tool, so that the carbon canister can be pressurized or maintained as needed. This facilitates the acquisition of system pressure information and the determination of system operating status information based on the pressure information. This detection method reduces the reliability requirements of the diagnostic pump, is less affected by external interference, and provides accurate detection results. Attached Figure Description

[0018] The accompanying drawings, which form part of this application, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings:

[0019] Figure 1 A schematic diagram of the fuel evaporative emission leakage detection system for an engine provided by the present invention is shown.

[0020] Figure 2 A schematic diagram of the structure of the diagnostic device provided by the present invention is shown;

[0021] Figure 3 A cross-sectional view of the diagnostic device provided by the present invention is shown in the solenoid valve closed state;

[0022] Figure 4 A cross-sectional view of the diagnostic tool provided by the present invention is shown in the solenoid valve open state;

[0023] Figure 5 A cross-sectional view of the pressurization assembly provided by the present invention is shown;

[0024] Figure 6 A cross-sectional view of the solenoid valve provided by the present invention is shown;

[0025] Figure 7 A cross-sectional view of the lower housing provided by the present invention is shown;

[0026] Figure 8 The diagram shows the gas flow path of the fuel evaporation emission leak detection system provided by the present invention when the diagnostic tool is not working;

[0027] Figure 9 The diagram shows the gas flow path of the fuel evaporation emission leak detection system provided by the present invention when the diagnostic tool is working.

[0028] The above figures include the following reference numerals:

[0029] 10. Fuel tank; 20. Carbon canister; 30. Diagnostic device; 31. Housing; 311. Air inlet; 312. Air outlet; 313. First chamber; 314. Second chamber; 3141. First valve seat; 3142. First vent; 315. First pipeline; 316. Upper housing; 317. Lower housing; 32. Pressurization assembly; 33. One-way valve assembly; 331. Second valve seat; 3311. Body; 3312. Connecting part; 332. Umbrella valve; 3321 3322. Connecting rod; 34. Umbrella-shaped seal; 35. Pipeline switching assembly; 36. Solenoid valve; 3411. Fixed iron core; 3412. Armature; 342. Sealing valve; 3421. Valve stem; 3422. Sealing valve skeleton; 3423. Elastic seal; 343. Return spring; 344. Bracket; 3441. Rib; 3442. Limiting ring; 40. Pressure detection device; 50. Fuel tank isolation valve; 60. Carbon canister control valve; 70. Engine intake system. Detailed Implementation

[0030] The specific embodiments of this disclosure will now be described in detail with reference to the accompanying drawings, but these are not intended to limit the scope of this disclosure.

[0031] It should be understood that various modifications can be made to the embodiments disclosed herein. Therefore, the above description should not be considered as limiting, but merely as an example of embodiments. Other modifications within the scope and spirit of this disclosure will be apparent to those skilled in the art.

[0032] The accompanying drawings, which are included in and form part of this specification, illustrate embodiments of the present disclosure and, together with the general description of the disclosure given above and the detailed description of the embodiments given below, serve to explain the principles of the disclosure.

[0033] These and other features of this disclosure will become apparent from the following description of preferred forms of embodiments given as non-limiting examples, with reference to the accompanying drawings.

[0034] It should also be understood that although this disclosure has been described with reference to some specific examples, those skilled in the art can certainly implement many other equivalent forms of this disclosure, which have the features described in the claims and are therefore all within the scope of protection defined herein.

[0035] The above and other aspects, features and advantages of this disclosure will become more apparent when taken in conjunction with the accompanying drawings and in view of the following detailed description.

[0036] Specific embodiments of the present disclosure are described thereafter with reference to the accompanying drawings; however, it should be understood that the disclosed embodiments are merely examples of the present disclosure and can be implemented in various ways. Well-known and / or repeated functions and structures are not described in detail to avoid unnecessary or redundant details that could obscure the present disclosure. Therefore, the specific structural and functional details disclosed herein are not intended to be limiting, but merely to serve as the basis and representative basis for the claims to teach those skilled in the art to use the present disclosure in a variety of substantially any suitable detailed structures.

[0037] It should be noted that the terms "first," "second," etc., used in this disclosure are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of this disclosure described herein can be implemented in orders other than those illustrated or described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0038] This specification may use the phrases “in one embodiment,” “in another embodiment,” “in yet another embodiment,” or “in other embodiments,” all of which may refer to one or more of the same or different embodiments according to this disclosure.

[0039] The present disclosure will be further described below with reference to the accompanying drawings and specific embodiments.

[0040] To address the technical problems of existing diagnostic methods being greatly affected by the environment and having a high misdiagnosis rate, this disclosure provides a fuel evaporation emission leakage detection system for engines.

[0041] like Figures 1 to 9As shown, this disclosure provides a fuel vapor emission leakage detection system for an engine. The system includes a fuel tank 10, a carbon canister 20, a diagnostic tool 30, and a pressure detection device 40. The carbon canister 20 is fluidly connected to both the fuel tank 10 and the engine intake system 70 via pipelines, thereby adsorbing fuel vapors within the fuel tank 10 and preventing them from being directly released into the atmosphere. A fuel tank isolation valve 50 is installed between the carbon canister 20 and the fuel tank 10 to control the pipeline connection between them. A carbon canister control valve 60 is installed between the carbon canister 20 and the engine intake system 70 to control the fluid connection between them. The pressure detection device 40 is used to detect internal pressure parameters of the system. The diagnostic tool 30 includes an air inlet 3. The system includes an intake port 311 connected to the atmosphere, allowing fresh air from the outside to enter the fuel evaporative emission system. The exhaust port 312 is connected to the carbon canister 20. The diagnostic tool 30 is equipped with a pressurization assembly 32, a one-way valve assembly 33, and a pipeline switching assembly 34. The diagnostic tool 30 has a first ventilation path and a second ventilation path connecting the intake port 311 and the exhaust port 312. The first ventilation path directly connects the intake port 311 and the exhaust port 312, allowing the carbon canister 20 to be directly connected to the outside atmosphere through the intake port 311. The second ventilation path connects the intake port 311 to the pressurization assembly 32, the one-way valve assembly 33, and the exhaust port 312 in sequence. The pipeline switching assembly 34 switches the first and second ventilation paths within the diagnostic tool 30 based on testing requirements to achieve airflow connection between the intake port 311 and the exhaust port 312.

[0042] By applying the fuel evaporative emission leakage detection system for engines provided in this application, the carbon canister 20 system pipeline can be controlled by controlling the carbon canister control valve 60 and the fuel tank isolation valve 50. The pipeline switching component 34 can realize different air path connections between the inlet 311 and outlet 312 of the diagnostic tool 30, so that the carbon canister 20 can be pressurized or pressure maintained as needed. This is beneficial for obtaining the system pressure information and determining the system's operating status information based on the pressure information. This detection method reduces the reliability requirements of the diagnostic pump, is less affected by external interference, and provides accurate detection results.

[0043] Furthermore, the pressure detection device 40 is installed inside the fuel tank 10, in the pipeline between the fuel tank isolation valve 50 and the fuel tank 10, or in the diagnostic device 30, to collect pressure parameters at different locations in the fuel evaporative emission system to characterize the pressure information in the fuel evaporative emission system; wherein, the pressure detection device 40 may be a pressure sensor, and the type of pressure sensor is not further limited in this application.

[0044] When the pressure detection device 40 is installed inside the fuel tank 10, the pressure detection device 40 can be the pressure sensor built into the fuel tank 10. Thus, the system pressure data can be obtained without modifying the system hardware during the assembly process. This setting method can avoid adding extra equipment, which is conducive to reducing costs and improving the integration of the whole vehicle.

[0045] Among them, such as Figure 2 As shown, the diagnostic device 30 includes a housing 31, with an air inlet 311 and an air outlet 312 disposed on the housing 31. The housing 31 has a first chamber 313 and a second chamber 314 formed inside. The air inlet 311 is connected to the outside air to provide fresh air to the system. The air outlet 312 is connected to the carbon canister 20, so that high-pressure air or fresh air can be selectively introduced into the oil tank 10 through the carbon canister 20. The first chamber 313 and the second chamber 314 are respectively connected to the air inlet 311, and the air outlet 312 is connected to the second chamber 314. The first chamber 313 is connected to the second chamber 314 and the air outlet 312 through a first pipe 315, so that the first chamber 313 has two air passages that can achieve fluid communication with the outside atmosphere and the air outlet 312, namely the first air passage and the second air passage.

[0046] Specifically, such as Figure 2 As shown, the air inlet 311 can be located in the middle of the housing, between the axes of the first chamber 313 and the second chamber 314. This arrangement facilitates the air passage connection between the first chamber 313, the second chamber 314 and the air inlet 311.

[0047] For example, the first chamber 313 can be connected to the air inlet 311 through a first opening formed on the side wall, and the second chamber 314 can be connected to the air inlet 311 through a second opening formed on the side wall. The first opening and the second opening are both located on the pipe wall of the air inlet 311, so that the first chamber 313 is directly connected to the air inlet 311, and the second chamber 314 is also directly connected to the air inlet 311. This arrangement is beneficial to speed up the interaction between fluids and reduce processing costs. Preferably, the flow area of ​​the second opening is larger than the flow area of ​​the first opening.

[0048] Furthermore, the housing 31 includes an upper housing 316 and a lower housing 317, which are sealed together. The air inlet 311, the air outlet 312, and the first pipeline 315 are all located on the lower housing 317. An electrical connector for electrical connection with the vehicle is provided on the upper housing 316. The first chamber 313 and the second chamber 314 are jointly enclosed by the upper housing 316 and the lower housing 317.

[0049] Optionally, the upper housing 316 and the lower housing 317 are snap-fitted together or laser-welded; both the upper housing 316 and the lower housing 317 are integrally formed, which can reduce costs and further improve the airtightness of the housing.

[0050] The pressurizing assembly 32 is fixedly connected to the housing 31. The pressurizing assembly 32 is located on the side of the first chamber 313 away from the first pipeline 315. The pressurizing assembly 32 can pressurize the air entering the first chamber 313 and transmit the pressurized high-pressure air to the one-way valve assembly 33. The one-way valve assembly 33 is connected to the housing and is located in the first chamber 313, between the pressurizing assembly 32 and the first pipeline 315. Thus, the high-pressure gas transmitted from the pressurizing assembly 32 can enter the first pipeline 315 through the one-way valve assembly 33. By arranging the one-way valve assembly 33, the one-way transmission path from the first chamber 313 to the second chamber 314 can be limited, so that high-pressure gas can be transmitted to the carbon canister 20 and the oil tank 10 through the second chamber 314.

[0051] like Figures 3 to 5 As shown, the pressurization assembly 32 includes an air pump located in the first chamber 313. The air inlet 311 of the housing 31 is connected to the chamber at the air pump end. Gas enters the chamber at the air pump end through the inlet. The air pump inlet is connected to the interior of the chamber. The air pump outlet is connected to the one-way valve assembly 33. After passing through the air pump, the gas passes through the one-way valve assembly 33, the second chamber 314, the air outlet 312, and enters the carbon canister 20 in sequence, thereby establishing pressure for the evaporation system.

[0052] The air pump can be, for example, a diaphragm pump. A diaphragm pump consists of a pump head and a brushed motor. The pump head comprises a pump housing, two side covers, a pumping diaphragm arranged inside the pump body, and an eccentric wheel in the center of the pump housing that cooperates with the brushed motor. The air pump is driven by the brushed motor. Each diaphragm is equipped with two pumping check valves, which are elastic valve plate structures. One is a diaphragm pump inlet check valve, and the other is a diaphragm pump outlet check valve, working in conjunction with the diaphragm to achieve the functions of air intake and exhaust during the pumping process. The specific type and structure of the air pump in this application are not limited; common air pumps in the prior art can be used in this application, as long as they can achieve gas compression and transmission.

[0053] To prevent external impurities from entering the system and causing pipe blockage during use, the second pipe and the air pump's air inlet are also connected to air filters. The second pipe and the air pump's air inlet can be connected to the same air filter through the same pipe, or they can be connected to different air filters through different pipes.

[0054] The pipeline switching assembly 34 is located in the second chamber 314. The pipeline switching assembly 34 includes a solenoid valve 341, a sealing valve 342, and a return spring 343. The sealing valve 342 is connected to the solenoid valve 341. Under the action of the solenoid valve 341, the sealing valve 342 controls the fluid communication between the first pipeline 315 and the second chamber 314. Thus, when the first pipeline 315 is connected to the second chamber 314, the gas pressurized by the pressurizing assembly 32 can pass through the one-way valve, the first pipeline 315, and the second chamber 314 in sequence, and finally leave the housing from the outlet 312 and enter the oil tank 10 through the carbon canister 20.

[0055] Furthermore, a first valve seat 3141 is provided on the side of the second chamber 314 near the first pipeline 315. The first valve seat 3141 has a cylindrical structure with one end open. The bottom surface and / or side surface of the valve seat are connected to the air outlet 312. The sealing valve 342 can abut against the first valve seat 3141 under the drive of the solenoid valve 341 to close or open the ventilation path between the second chamber 314 and the air outlet 312. A first vent hole 3142 is provided at the bottom of the first valve seat 3141. The first vent hole 3142 is connected to the first pipeline 315. Thus, when the sealing valve 342 abuts against the first valve seat 3141, the sealing valve 342 simultaneously cuts off the communication path between the second chamber 314 and the first chamber 313, as well as between the second chamber 314 and the outside. At this time, the first chamber 313 is directly connected to the carbon canister 20 only through the first pipeline 315.

[0056] Preferably, a spring abutment portion is formed inside the first valve seat 3141, and a first vent hole 3142 is formed at the center of the spring abutment portion. The outer diameter of the spring abutment portion matches the inner diameter of the return spring 343 to achieve quick assembly and positioning of the return spring 343.

[0057] The solenoid valve 341 includes a fixed iron core 3411 and an armature 3412. At least a part of the sealing valve 342 passes through the central through hole of the fixed iron core 3411 and is axially positioned. Under the drive of electromagnetic force and the action of the return spring 343, the sealing valve 342 reciprocates in the second chamber 314.

[0058] Specifically, the sealing valve 342 includes a valve stem 3421, a sealing valve frame 3422, and an elastic sealing part 3423. One end of the valve stem 3421 passes through the central through hole of the fixed iron core 3411, and the other end of the valve stem 3421 is detachably connected to the sealing valve frame 3422. The elastic sealing part 3423 is connected to the sealing frame and can abut against the first valve seat 3141 under the action of the solenoid valve 341, thereby achieving the sealing of the first valve seat 3141.

[0059] Preferably, the elastic sealing part 3423 is made of rubber and can be fixed to the sealing skeleton by vulcanization; the valve stem 3421 is provided with a first positioning ring and a second positioning ring, the sealing skeleton is provided with an installation part and an avoidance opening, the valve stem 3421 is fixedly connected to the installation part through the avoidance opening, and the installation positioning of the installation part is achieved by the first positioning ring and the second positioning ring.

[0060] To ensure smooth opening of the passage, one end of the return spring 343 abuts against the elastic sealing part 3423, and the other end of the return spring 343 abuts against the spring abutment part in the first valve seat 3141. After the solenoid valve 341 is de-energized, the return spring 343 pushes the sealing valve 342 upward to open the air passage between the second chamber 314 and the first pipeline 315 and the air outlet 312. At the same time, under the force of the return spring 343, the sealing valve frame 3422 abuts against the step of the first positioning ring of the valve stem 3421, thereby improving the stability of the connection between the valve stem 3421 and the sealing frame.

[0061] Furthermore, the pipeline switching assembly 34 also includes a bracket 344, with a connecting hole in the middle of the bracket 344. The sealing valve 342 passes through the connecting hole and is connected to the solenoid valve 341. The bracket 344 is provided with a rib plate 3441 for limiting the movement path of the sealing valve 342. The sealing valve frame 3422 and the rib plate 3441 are in clearance fit in the circumferential direction, thereby ensuring circumferential positioning.

[0062] Among them, three ribs 3441 can be provided, and the three ribs 3441 are evenly distributed around the sealing frame. A limiting ring 3442 can also be provided at the front end of the rib 3441. The limiting ring 3442 can further ensure the centering of the sealing frame during the movement.

[0063] In another embodiment of this application, the one-way valve assembly 33 includes a second valve seat 331 and an umbrella valve 332. At least a portion of the second valve seat 331 is sealed and fixedly connected to the housing. The second valve seat 331 has a mounting hole located at the center of the second valve seat 331 and at least one vent hole located around the mounting hole. When there are two or more vent holes, the vent holes are evenly distributed around the mounting hole. The umbrella valve 332 is fixedly connected to the second valve seat 331 through the mounting hole. At least a portion of the umbrella valve 332 is made of elastic material, and the elastic material covers the vent holes, thereby achieving a seal on the vent holes. When the pressure in the first pipeline 315 is large, the pressure in the first pipeline 315 acts on the surface of the umbrella valve 332, causing the umbrella valve 332 to abut against the vent holes, thereby achieving a seal on the vent holes.

[0064] Furthermore, the second valve seat 331 includes a body 3311 and a connecting part 3312. The connecting part 3312 is a cylindrical shape with one end open, extending from the body 3311 toward the first pipeline 315. The outer wall of the connecting part 3312 abuts and is fixed to the inner wall of the first pipeline 315.

[0065] To improve the airtightness of the system, an elastic sealing ring is provided between the outer wall of the connecting part 3312 and the inner wall of the first pipeline 315, and an installation groove for installing the elastic sealing ring is provided on the outer periphery of the second valve seat 331; the installation groove facilitates the installation and positioning of the elastic sealing ring; preferably, the elastic sealing ring can be, for example, an O-ring.

[0066] The umbrella valve 332 includes a connecting rod 3321 and an umbrella-shaped sealing part 3322. The valve stem 3421 and the umbrella-shaped sealing part 3322 are integrally formed. The connecting rod 3321 is connected to the mounting hole. The outer diameter of the valve stem 3421 gradually decreases from the end connected to the umbrella-shaped sealing part 3322 to the end away from the umbrella-shaped sealing part 3322. A positioning part is provided on the connecting rod 3321. The positioning part can abut against the side of the second valve seat 331 away from the first pipeline 315. This arrangement is beneficial to the assembly and fixation between the valve stem 3421 and the second valve seat 331.

[0067] The umbrella-shaped sealing part 3322 is made of rubber and can cover the vent hole, thereby achieving a one-way seal on the vent hole.

[0068] In another embodiment of this application, the housing may also be provided with a third chamber, which is connected to the first pipeline 315. The axes of the first chamber 313, the second chamber 314 and the third chamber are arranged in parallel. The third chamber is used to connect to a pressure sensor, so that the pressure sensor can collect pressure information in the system through the third chamber.

[0069] Solenoid valve 341 is a normally open solenoid valve. During use, when the engine is running and the diagnostic tool is not working, the fuel tank isolation valve 40 is de-energized and closed, the carbon canister control valve 60 is energized and opened, solenoid valve 341 is de-energized and opened, and the air inlet 311 and air outlet 312 of the housing are directly connected in the second chamber 314. Figure 8 As shown by the middle arrow, external air enters the diagnostic device through the air inlet 311 and directly enters the carbon canister 20 from the air outlet 312, thus ensuring low airflow resistance during desorption of the carbon canister 20. When the solenoid valve 341 is energized, the solenoid valve 341 closes, closing the channel connecting the air inlet 311 and the air outlet 312 inside the housing. The gas must be pumped from the air inlet 311 inside the housing to the one-way valve assembly 33 inside the housing via the air pump, and then enter the carbon canister 20 through the first pipeline 315, forming a stable pressure for monitoring whether there is a leak in the system.

[0070] According to another aspect of this application, this application also provides a fuel evaporative emission leakage detection system for an engine, including a fuel tank 10, a carbon canister 20, a pressurization assembly 32, a one-way valve assembly 33, and a pressure detection device 40. The carbon canister 20 is connected to the fuel tank 10 and the engine intake system 70 via pipelines. A fuel tank isolation valve 50 is provided between the carbon canister 20 and the fuel tank 10 to control the pipeline connection between the fuel tank and the carbon canister. A first carbon canister control valve is provided between the carbon canister 10 and the engine intake system 70 to control the pipeline connection between the carbon canister 20 and the engine intake system 70. The pressure detection device 40 is used to detect the internal pressure of the fuel tank. The carbon canister 20 is connected to the pressurization assembly 32 via the one-way valve assembly 33. The carbon canister 20 is connected to an external air pipeline. A second carbon canister control valve is provided between the carbon canister 20 and the external air to control the airflow connection between the carbon canister and the external control system.

[0071] The first carbon canister control valve and the second carbon canister control valve can be solenoid valves. By opening and closing the first carbon canister control valve and the second carbon canister control valve, the carbon canister can be directly connected to the outside atmosphere, or the carbon canister can be connected to the one-way valve assembly.

[0072] According to another aspect of this application, this application also provides a method for detecting fuel evaporative emission leaks in an engine, the method employing the aforementioned detection system, the method comprising the following steps:

[0073] During the operation of the diagnostic tool, such as Figure 9 As shown, Figure 9 The middle arrow indicates the airflow direction. When the solenoid valve 341 is energized, the sealing valve 342 abuts against the first valve seat 3141, closing the communication channel between the air outlet 312 and the air inlet 311, thereby closing the air path connection between the carbon canister 20 and the external air. At this time, the oil tank isolation valve 50 is opened, and the air connection between the oil tank 10 and the carbon canister 20 is established. The pressurization component 32 is activated to pressurize the fresh air entering from the air inlet 311. The pressurized gas passes through the one-way valve component 33, through the first pipeline 315, and enters the carbon canister 20 from the air outlet 312, and finally enters the oil tank 10, pressurizing the internal pressure of the oil tank 10 to the first threshold P1. The time difference ∆t between the oil tank 10 pressure decreasing to the second threshold P2 and the third threshold P3 is recorded. The time difference ∆t is compared with the system preset time. When the time difference ∆t is less than the system preset time, there is a leak in the system.

[0074] According to another aspect of this application, this application also provides a method for detecting fuel evaporative emission leaks in an engine, the method employing the aforementioned detection system and including the following steps:

[0075] When solenoid valve 341 is energized, sealing valve 342 abuts against first valve seat 3141, closing the communication channel between air outlet 312 and air inlet 311, thereby shutting off the air passage between carbon canister 20 and external air; oil tank isolation valve 50 is opened, and pressurization device is activated to pressurize the fresh air entering from air inlet 311. The pressurized gas passes through a one-way valve, through the first pipeline 315, and enters carbon canister 20 from air outlet 312, and finally enters oil tank 10, pressurizing the internal pressure of oil tank 10 to the first threshold P1; the integral value S of oil tank 10 pressure P from the moment it reaches the second threshold P2 to the moment it reaches the third threshold P3 is calculated, i.e. The integral value S is compared with the system preset value. If the integral value S is less than the system preset value, the system has a leakage.

[0076] In the description of this invention, it should be understood that directional terms such as "front, back, up, down, left, right", "horizontal, vertical, horizontal" and "top, bottom" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this invention and simplifying the description. Unless otherwise stated, these directional terms do not indicate or imply that the device or element referred to must have a specific orientation or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation on the scope of protection of this invention. The directional terms "inner" and "outer" refer to the inner and outer contours of each component itself.

[0077] For ease of description, spatial relative terms such as "above," "on top of," "on the upper surface of," "above," etc., are used herein to describe the spatial positional relationship of a device or feature as shown in the figures to other devices or features. It should be understood that spatial relative terms are intended to encompass different orientations in use or operation beyond the orientation of the device as described in the figures. For example, if the device in the figures were inverted, a device described as "above" or "on top of" other devices or structures would subsequently be positioned as "below" or "under" other devices or structures. Thus, the exemplary term "above" can include both "above" and "below." The device may also be positioned in other different ways (rotated 90 degrees or in other orientations), and the spatial relative descriptions used herein will be interpreted accordingly.

[0078] Furthermore, it should be noted that the use of terms such as "first" and "second" to define components is merely for the purpose of distinguishing the corresponding components. Unless otherwise stated, the above terms have no special meaning and therefore should not be construed as limiting the scope of protection of this invention.

[0079] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A fuel evaporative emission leak detection system for an engine, characterized in that, The system includes a fuel tank, a carbon canister, a diagnostic tool, and a pressure detection device. The carbon canister is fluidly connected to both the fuel tank and the engine's intake system. A fuel tank isolation valve is installed between the carbon canister and the fuel tank, and a carbon canister control valve is installed between the carbon canister and the engine to control the fluid communication between them. The diagnostic tool includes an inlet and an outlet. The inlet is open to the atmosphere, and the outlet is connected to the carbon canister. The diagnostic tool contains a pressurization assembly, a one-way valve assembly, and a pipeline switching assembly. A first ventilation path and a second ventilation path are formed within the diagnostic tool, connecting the inlet and outlet. The first ventilation path directly connects the inlet and outlet, while the second ventilation path sequentially connects the inlet to the pressurization assembly, the one-way valve, and the outlet. The pipeline switching assembly switches between the first and second ventilation paths within the diagnostic tool based on testing requirements to maintain airflow communication between the inlet and outlet. The diagnostic device further includes: a housing, comprising an air inlet, an air outlet, a first chamber, and a second chamber, wherein the first chamber and the second chamber are respectively connected to the air inlet, the air outlet is connected to the second chamber, and the first chamber is connected to the second chamber and the air outlet via a first pipeline; a pressurizing assembly is fixedly connected to the housing and disposed on the side of the first chamber away from the first pipeline; a one-way valve assembly is connected to the housing and disposed within the first chamber, located between the pressurizing assembly and the first pipeline; and a pipeline switching assembly is located within the second chamber and is used to control the fluid communication between the first pipeline and the second chamber, so that when the first pipeline is connected to the second chamber, the gas pressurized by the pressurizing assembly can sequentially pass through the one-way valve, the first pipeline, and the second chamber, and finally leave the housing from the air outlet.

2. The fuel evaporation emission leakage detection system for an engine according to claim 1, characterized in that, The pressure detection device is installed inside the oil tank, in the pipeline between the oil tank isolation valve and the oil tank, or in the diagnostic tool.

3. The fuel evaporation emission leakage detection system for an engine according to claim 1, characterized in that, The pipeline switching assembly includes a solenoid valve, a sealing valve, and a return spring. One end of the return spring abuts against the elastic sealing part, and the other end of the return spring abuts against the first valve seat. The solenoid valve includes a fixed iron core and an armature. A through hole is provided in the center of the fixed iron core. At least a part of the sealing valve passes through the central through hole of the fixed iron core. Under the drive of electromagnetic force and the action of the return spring, the sealing valve reciprocates in the second chamber.

4. The fuel evaporation emission leakage detection system for an engine according to claim 3, characterized in that, The sealing valve includes a valve stem, a sealing valve frame, and an elastic sealing part. One end of the valve stem passes through the central through hole of the fixed iron core, and the other end of the valve stem is detachably connected to the sealing valve frame. The elastic sealing part is connected to the sealing valve frame and can abut against the first valve seat under the action of the solenoid valve.

5. The fuel evaporation emission leakage detection system for an engine according to claim 1, characterized in that, The one-way valve assembly includes: A second valve seat, at least a portion of which is sealed and fixedly connected to the housing, the second valve seat having a mounting hole located at the center of the second valve seat and at least one vent hole located around the mounting hole; An umbrella-shaped valve is fixedly connected to the second valve seat through the mounting hole. At least a portion of the umbrella-shaped valve is made of an elastic material, which covers the vent hole.

6. The fuel evaporation emission leakage detection system for an engine according to claim 5, characterized in that, The second valve seat includes a body and a connecting part. The connecting part is a cylindrical shape with one end open and extends from the body toward the first pipeline. The outer wall of the connecting part abuts and is fixed to the inner wall of the first pipeline.

7. A method for detecting fuel evaporative emission leaks in an engine, the method employing the detection system according to any one of claims 1-6, the method comprising the following steps: Close the air passage between the carbon canister and the outside air, and open the fuel tank isolation valve. Use the pressurization device to pressurize the internal pressure of the fuel tank to the first threshold P1. Record the time difference Δt between the tank pressure decreasing to the second threshold P2 and the third threshold P3; The time difference Δt is compared with the system preset time. If the time difference Δt is less than the system preset time, the system has a leak.

8. A method for detecting fuel evaporative emission leaks in an engine, the method employing the detection system according to any one of claims 1-6, the method comprising the following steps: Close the air passage between the carbon canister and the outside air, and open the fuel tank isolation valve. Use the pressurization device to pressurize the internal pressure of the fuel tank to the first threshold P1. Calculate the integral value S of the oil tank pressure P from the moment it reaches the second threshold P2 to the moment it reaches the third threshold P3; The integral value S is compared with the system preset value. If the integral value S is less than the system preset value, the system has a leakage.

Images