Fuel evaporative emission leakage detection system and detection method for engine

Abstract

The invention provides a fuel evaporative emission leakage detection system and method for an engine, the detection system comprises a fuel tank, a carbon tank, a diagnostor and a pressure detection device, the carbon tank is in fluid communication with the fuel tank and an air inlet system of the engine, and the diagnostor comprises an air inlet and an air outlet; a first ventilation path and a second ventilation path are formed in the diagnosis device, the air inlet is directly communicated with the air outlet through the first ventilation path, and the air inlet is sequentially communicated with the pressurizing assembly, the one-way valve and the air outlet through the second ventilation path. The pipeline switching assembly is used for switching a first ventilation path and a second ventilation path in the diagnosis device based on a detection requirement so as to realize gas path communication between the gas inlet and the gas outlet; therefore, pressurization operation or pressure maintaining operation can be carried out on the carbon tank according to requirements, pressure information of the system can be obtained, operation state information of the system is determined based on the pressure information, the requirement for diagnosing the reliability of the pump is lowered, external interference is small, and the detection result is accurate.

Description

Technical Field

[0001] The present invention relates to the field of vehicle technology, in particular to the field of vehicle system detection technology, and specifically to a fuel evaporative emission leakage detection system and a detection method for an engine. Background Art

[0003] The leakage detection method of the fuel evaporative emission system in the prior art is to set a DMTL module in the evaporative emission system. The module is composed of a motor-driven vane pump and a solenoid valve. The internal flow channel of the module includes a main cavity connected to the atmosphere and a high-pressure cavity, wherein a reference hole for calibration is designed on the high-pressure cavity. The DMTL leakage diagnosis module has two working states during diagnosis, namely, reference mode and diagnosis mode, and these two modes are switched by solenoid valve control. By energizing the electromagnetic coil in the solenoid valve, the electromagnetic force generated by the electromagnetic coil drives the iron core and the valve to move together, thereby realizing the opening and closing of the valve. The two working conditions of the vane pump to pump air to the reference hole or to the entire evaporative emission system are realized by switching the solenoid valve, and the motor current of the vane pump under the two working conditions is compared for detection. By comparing the detected current, it is determined whether there is a leakage of more than 0.5mm hole. However, since the diagnostic current of the rotary vane pump is relatively small, at 20-50mA, the diagnostic result itself will be greatly affected by the environment, especially the air humidity, friction of the rotary vane pump, wear and foreign matter jamming and other factors. Judging from the actual feedback from the market, the probability of misdiagnosis is relatively high.

[0004] Therefore, there are technical problems in the prior art that the existing diagnostic methods are greatly affected by the environment and have a high misdiagnosis rate. Summary of the invention

[0005] The main purpose of the present invention is to provide a fuel evaporative emission leakage detection system for an engine, so as to solve the technical problems existing in the related art that the existing diagnosis method is greatly affected by the environment and has a high misdiagnosis rate.

[0006] In order to achieve the above-mentioned object, according to one aspect of the present invention, a fuel evaporative emission leakage detection system for an engine is provided, comprising a fuel tank, a carbon canister, a diagnostic device and a pressure detection device, wherein the carbon canister is respectively in fluid communication with the fuel tank and the intake system of the engine, 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, and the carbon canister control valve is used to control the fluid communication between the carbon canister and the engine, and the diagnostic device comprises an air inlet and an air outlet, and the air inlet is connected to the atmosphere. The air outlet is connected with the carbon canister, a pressurizing component, a one-way valve component and a pipeline switching component are arranged in the diagnostic device, a first ventilation path and a second ventilation path connecting the air inlet and the air outlet are formed in the diagnostic device, wherein the first ventilation path directly connects the air inlet with the air outlet, and the second ventilation path connects the air inlet with the pressurizing component, the one-way valve and the air outlet in sequence, and the pipeline switching component switches the first ventilation path and the second ventilation path in the diagnostic device based on the detection requirements to realize the air path connection between the air inlet and the air outlet.

[0007] Furthermore, the pressure detection device is arranged in the oil tank or in a pipeline between the oil tank isolation valve and the oil tank or in the diagnostic device.

[0008] Furthermore, the diagnostic device also includes: a shell, the air inlet and the air outlet are arranged on the shell, a first chamber and a second chamber are formed in the shell, 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 through a first pipeline; the pressurizing component is fixedly connected to the shell, and the pressurizing component is arranged on the side of the first chamber away from the first pipeline; the one-way valve component is connected to the shell, the one-way valve component is arranged in the first chamber and is located between the pressurizing component and the first pipeline; the pipeline switching component is located in the second chamber, and the pipeline switching component is used to control the fluid connection 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 component can pass through the one-way valve, the first pipeline, and the second chamber in sequence, and finally leave the shell from the air outlet and enter the carbon canister.

[0009] 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 portion, 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 at the center of the fixed iron core, at least a part of the sealing valve passes through the center through hole of the fixed iron core, and under the drive of electromagnetic force and the action of the return spring, the sealing valve reciprocates in the second chamber.

[0010] Furthermore, the sealing valve includes a valve stem, a sealing valve frame and an elastic sealing portion, 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 portion is connected to the sealing frame, and can abut against the first valve seat under the action of the solenoid valve.

[0011] Further, the one-way valve assembly includes a second valve seat, at least a portion of the second valve seat is sealed and fixedly connected to the shell, the second valve seat has a mounting hole located at the center of the second valve seat and at least one air vent located around the mounting hole; an umbrella valve, the umbrella valve is fixedly connected to the second valve seat through the mounting hole, at least a portion of the umbrella valve is made of elastic material, and the elastic material covers the air vent.

[0012] Furthermore, the second valve seat includes a body and a connecting portion, wherein the connecting portion is in a cylindrical shape with one end open and extends from the body toward the first pipeline, and an outer wall of the connecting portion is abutted and fixed to an inner wall of the first pipeline.

[0013] According to another aspect of the present invention, the present invention also provides a fuel evaporation emission leakage detection system for an engine, 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 pipelines respectively, a fuel tank isolation valve is arranged 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 arranged 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 a one-way valve, the carbon canister is connected to the external air pipeline, a second carbon canister control valve is arranged between the carbon canister and the external air, and the second carbon canister control valve is used to control the air path connection between the carbon canister and the external control.

[0014] According to another aspect of the present invention, the present invention also provides a method for detecting fuel evaporative emission leakage of an engine, the method adopting the above-mentioned detection system, the method comprising the following steps: Close the air path connection between the carbon canister and the outside air, open the fuel tank isolation valve, and pressurize the internal pressure of the fuel tank to the first threshold value P1 through the pressurizing device; record the time difference ∆t when the fuel tank pressure drops to the second threshold value P2 and the third threshold value P3; compare the time difference ∆t with the system preset time. When the time difference ∆t is less than the system preset time, there is a leak in the system.

[0015] According to another aspect of the present invention, the present invention also provides a method for detecting fuel evaporative emission leakage of an engine, the method using the aforementioned detection system, comprising the following steps: Close the gas path between the carbon canister and the outside air, open the fuel tank isolation valve, and pressurize the internal pressure of the fuel tank to the first threshold value P1 through the pressurizing device; calculate the integral value S of the fuel tank pressure P from the moment it reaches the second threshold value P2 to the moment it reaches the third threshold value P3, that is, ; Compare the integral value S with the system preset value. When the integral value S is less than the system preset value, there is a leak in the system.

[0016] By using the fuel evaporative emission leak detection system for the engine provided by the present application, the carbon canister system pipeline can be controlled by controlling the carbon canister control valve and the fuel tank isolation valve. Different air path connections between the diagnostic device air inlet and air outlet can be achieved through the pipeline switching component, so that the carbon canister can be pressurized or pressure-maintained as required, which is conducive to obtaining the system pressure information and determining the 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 has accurate detection results. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] The drawings constituting a part of the present application are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the drawings: Figure 1 A system schematic diagram of a fuel evaporative emission leakage detection system for an engine provided by the present invention is shown; Figure 2 The structure diagram of the diagnostic device provided by the present invention is shown; Figure 3 A cross-sectional view of the diagnostic device provided by the present invention is shown in a state where the solenoid valve is closed; Figure 4 A cross-sectional view of the diagnostic device provided by the present invention is shown in a state where the solenoid valve is opened; Figure 5 A cross-sectional view of a pressurizing assembly provided by the present invention is shown; Figure 6 A cross-sectional view of the solenoid valve provided by the present invention is shown; Figure 7 A cross-sectional view of the lower housing provided by the present invention is shown; Figure 8 The diagram shows the gas flow path of the fuel evaporative emission leakage detection system provided by the present invention when the diagnostic device is not working; Fig. 9The diagram shows the gas flow path of the fuel evaporative emission leakage detection system provided by the present invention when the diagnostic device is working.

[0018] The above drawings include the following reference numerals: 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 hole; 315. first pipeline; 316. upper housing; 317. lower housing; 32. pressurizing assembly; 33. one-way valve assembly; 331. second valve seat; 3311. body; 3312. connecting part; 332. umbrella valve; 3321 , connecting rod; 3322, umbrella-shaped sealing part; 34, pipeline switching assembly; 341, solenoid valve; 3411, fixed iron core; 3412, armature; 342, sealing valve; 3421, valve stem; 3422, sealing valve skeleton; 3423, elastic sealing part; 343, return spring; 344, bracket; 3441, rib plate; 3442, limit ring; 40, pressure detection device; 50, fuel tank isolation valve; 60, carbon canister control valve; 70, engine intake system. DETAILED DESCRIPTION

[0019] The specific embodiments of the present disclosure are described in detail below with reference to the accompanying drawings, but are not intended to limit the present disclosure.

[0020] It should be understood that various modifications may be made to the embodiments disclosed herein. Therefore, the above description should not be considered as limiting, but merely as an example of an embodiment. Other modifications within the scope and spirit of the present disclosure will occur to those skilled in the art.

[0021] The accompanying drawings, which are incorporated in and constitute a part of the specification, illustrate embodiments of the present disclosure and, together with the general description of the present disclosure given above and the detailed description of the embodiments given below, serve to explain the principles of the present disclosure.

[0022] These and other characteristics of the present disclosure will become apparent from the following description of a preferred form of embodiment given as a non-limiting example, with reference to the attached drawings.

[0023] It should also be understood that, although the present disclosure has been described with reference to some specific examples, those skilled in the art will be able to realize many other equivalent forms of the present disclosure that have the features described in the claims and are therefore within the scope of protection defined thereby.

[0024] The above and other aspects, features and advantages of the present disclosure will become more apparent from the following detailed description when taken in conjunction with the accompanying drawings.

[0025] Specific embodiments of the present disclosure are described hereinafter with reference to the accompanying drawings; however, it should be understood that the disclosed embodiments are merely examples of the present disclosure, which may be implemented in a variety of ways. Well-known and / or repeated functions and structures are not described in detail to avoid obscuring the present disclosure with unnecessary or redundant details. Therefore, the specific structural and functional details disclosed herein are not intended to be limiting, but merely serve as a basis and representative basis for the claims to teach those skilled in the art to use the present disclosure in a variety of ways with substantially any suitable detailed structure.

[0026] It should be noted that the terms "first", "second", etc. in the specification of the present disclosure are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the data used in this way can be interchangeable where appropriate, so that the embodiments of the present disclosure described herein can be implemented in an order other than those illustrated or described herein. In addition, the terms "including" and "having" and any of their variations are intended to cover non-exclusive inclusions, for example, a process, method, system, product or device that includes a series of steps or units is not necessarily limited to those steps or units that are clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

[0027] This specification may use the phrases "in one embodiment," "in another embodiment," "in a further embodiment," or "in other embodiments," all of which may refer to one or more of the same or different embodiments according to the present disclosure.

[0028] The present disclosure is further described below in conjunction with the accompanying drawings and specific embodiments.

[0029] In order to solve the technical problems in the prior art that the existing diagnosis method is greatly affected by the environment and has a high misdiagnosis rate, the present disclosure provides a fuel evaporative emission leakage detection system for an engine.

[0030] like Figures 1 to 9As shown, the present disclosure provides a fuel evaporative emission leakage detection system for an engine, the fuel evaporative emission leakage detection system includes a fuel tank 10, a carbon canister 20, a diagnostic device 30 and a pressure detection device 40, wherein the carbon canister 20 is respectively connected to the fuel tank 10 and the engine intake system 70 through pipelines, so that the fuel vapor in the fuel tank 10 is adsorbed by the carbon canister 20 to prevent the fuel vapor in the fuel tank 10 from being directly discharged into the atmosphere, a fuel tank isolation valve 50 is arranged between the carbon canister 20 and the fuel tank 10, and the fuel tank isolation valve 50 is used to control the pipeline connection between the fuel tank 10 and the carbon canister 20, a carbon canister control valve 60 is arranged between the carbon canister 20 and the engine intake system 70, and the carbon canister control valve 60 is used to control the fluid connection between the carbon canister 20 and the engine intake system 70, the pressure detection device 40 is used to detect the pressure parameters inside the system, and the diagnostic device 30 includes an intake port 30. 11 and the air outlet 312, the air inlet 311 is connected to the atmosphere, and the outside fresh air can enter the fuel evaporation emission system through the air inlet 311, and the air outlet 312 is connected to the carbon canister 20. The diagnostic device 30 is provided with a pressurizing component 32, a one-way valve component 33 and a pipeline switching component 34, and a first ventilation path and a second ventilation path connected between the air inlet 311 and the air outlet 312 are formed in the diagnostic device 30, wherein the first ventilation path directly connects the air inlet 311 with the air outlet 312, so that the carbon canister 20 can be directly connected to the external atmosphere through the air inlet 311; the second ventilation path connects the air inlet 311 with the pressurizing component 32, the one-way valve component 33 and the air outlet 312 in sequence, and the pipeline switching component 34 switches the first ventilation path and the second ventilation path in the diagnostic device 30 based on the detection requirements to realize the air path connection between the air inlet 311 and the air outlet 312.

[0031] By using the fuel evaporative emission leakage detection system for the engine provided by the present 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. Different gas circuits can be connected between the air inlet 311 and the air outlet 312 of the diagnostic device 30 through the pipeline switching component 34, so that the carbon canister 20 can be pressurized or maintained as needed, which is conducive to obtaining the system pressure information and determining the system operation status information based on the pressure information. This detection method reduces the requirements for the reliability of the diagnostic pump, is less affected by external interference, and has accurate detection results.

[0032] Furthermore, the pressure detection device 40 is disposed in the fuel tank 10 or in the pipeline between the fuel tank isolation valve 50 and the fuel tank 10 or in the diagnostic device 30, so as to collect pressure parameters at different positions in the fuel evaporative emission system to characterize the pressure information in the fuel evaporative emission system; wherein, the pressure detection device 40 can adopt a pressure sensor, and the type of the pressure sensor is not further limited in the present application.

[0033] When the pressure detection device 40 is disposed inside the fuel tank 10, the pressure detection device 40 can be a pressure sensor provided by the fuel tank 10, so that the pressure data of the system can be obtained without modifying the hardware equipment of the system during the assembly process. Such a setting method can avoid adding additional equipment, which is conducive to reducing costs and improving the integration of the entire vehicle.

[0034] Among them, Figure 2 As shown, the diagnostic device 30 includes a shell 31, an air inlet 311 and an air outlet 312 are arranged on the shell 31, and a first chamber 313 and a second chamber 314 are formed inside the shell 31. The air inlet 311 is connected to the outside air to provide fresh air for the system, and 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 fuel 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 pipeline 315, so that the first chamber 313 has two air-conducting paths that can realize fluid communication with the outside atmosphere and the air outlet 312 respectively, namely the first ventilation path and the second ventilation path.

[0035] Specifically, Figure 2 As shown in , the air inlet 311 can be arranged in the middle of the shell, between the axes of the first chamber 313 and the second chamber 314. Such an arrangement is conducive to the air path communication between the first chamber 313 and the second chamber 314 and the air inlet 311.

[0036] 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, wherein the first opening and the second opening are simultaneously located on the tube 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. Such an arrangement is conducive to speeding up the interaction speed between fluids and reducing processing costs. Preferably, the flow area of ​​the second opening is larger than the flow area of ​​the first opening.

[0037] Furthermore, the shell 31 includes an upper shell 316 and a lower shell 317, the upper shell 316 and the lower shell 317 are tightly connected, the air inlet 311, the air outlet 312 and the first pipeline 315 are all arranged on the lower shell 317, the upper shell 316 is provided with an electrical connector for electrical connection with the vehicle, and the first chamber 313 and the second chamber 314 are jointly surrounded by the upper shell 316 and the lower shell 317.

[0038] Optionally, the upper shell 316 and the lower shell 317 are snap-connected or laser welded; the upper shell 316 and the lower shell 317 are both integrally formed, which can reduce costs while further improving the airtightness of the shell.

[0039] The pressurizing assembly 32 is fixedly connected to the housing 31. The pressurizing assembly 32 is arranged on a 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. The one-way valve assembly 33 is arranged in the first chamber 313 and is located 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, a one-way transmission path from the first chamber 313 to the second chamber 314 can be defined, so that the high-pressure gas can be transmitted to the carbon canister 20 and the fuel tank 10 through the second chamber 314.

[0040] like Figures 3 to 5 As shown, the pressurizing component 32 includes an air pump, which is located in the first chamber 313. The air inlet 311 of the shell 31 is connected to the chamber at the air pump end. The gas enters the chamber at the air pump end from the inlet. The inlet of the air pump is connected to the inside of the chamber. The outlet of the air pump is connected to the one-way valve component 33. After passing through the air pump, the gas passes through the one-way valve component 33, the second chamber 314, the air outlet 312, and enters the carbon canister 20 in sequence, thereby building up pressure for the evaporation system.

[0041] Among them, the air pump can be, for example, a diaphragm pump, which includes a pump head and a brush motor. The pump head consists of a pump housing, covers on both sides, a pump air diaphragm arranged inside the pump body, and an eccentric wheel in the center of the pump housing that cooperates with the brush motor. The air pump is driven by a brush motor, and each diaphragm is equipped with two pump air check valves, which are elastic valve plate structures, one is the diaphragm pump air inlet check valve, and the other is the diaphragm pump air outlet check valve, which cooperate with the diaphragm to realize the function of air intake and exhaust during the pumping process; the specific type and structure of the air pump are not limited in the present application, and common air pumps in the prior art can be applied to the present application as long as they can achieve compression and transmission of gas.

[0042] In order to prevent external impurities from entering the system and causing pipeline blockage during use, the second pipeline and the air intake end of the air pump are respectively connected to air filters, wherein the second pipeline and the air intake end of the air pump can be connected to the same air filter through the same pipeline, or can be connected to different air filters through different pipelines.

[0043] 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 connection between the first pipeline 315 and the second chamber 314. 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 shell from the outlet 312 and enter the fuel tank 10 through the carbon canister 20.

[0044] Furthermore, a first valve seat 3141 is provided on one side of the second chamber 314 close to the first pipeline 315. The first valve seat 3141 is a cylindrical structure with one end open, and the bottom surface and / or the 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 ventilation hole 3142 is provided at the bottom of the first valve seat 3141, and the first ventilation hole 3142 is connected to the first pipeline 315; so that 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 and the second chamber 314 and the outside world. At this time, the first chamber 313 is directly connected to the carbon canister 20 only through the first pipeline 315.

[0045] Preferably, a spring abutment is formed in the first valve seat 3141 , a first vent hole 3142 is formed at the center of the spring abutment, and an outer diameter of the spring abutment matches an inner diameter of the return spring 343 to achieve rapid assembly and positioning of the return spring 343 .

[0046] The solenoid valve 341 includes a fixed iron core 3411 and an armature 3412. At least a portion of the sealing valve 342 passes through the central through hole of the fixed iron core 3411 and realizes axial positioning. Driven by the electromagnetic force and under the action of the return spring 343, the sealing valve 342 reciprocates in the second chamber 314.

[0047] Specifically, the sealing valve 342 includes a valve stem 3421, a sealing valve skeleton 3422 and an elastic sealing portion 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 skeleton 3422. The elastic sealing portion 3423 is connected to the sealing skeleton and can abut against the first valve seat 3141 under the action of the solenoid valve 341, thereby achieving sealing of the first valve seat 3141.

[0048] Preferably, the elastic sealing part 3423 is made of rubber material and can be fixed to the sealing frame by vulcanization; the valve stem 3421 is provided with a first positioning ring and a second positioning ring, and the sealing frame is provided with a mounting part and an avoidance opening; the valve stem 3421 is fixedly connected to the mounting part through the avoidance opening, and the installation positioning of the mounting part is achieved by the first positioning ring and the second positioning ring.

[0049] In order to ensure smooth opening of the passage, one end of the return spring 343 abuts against the elastic sealing portion 3423, and the other end of the return spring 343 abuts against the spring abutment portion in the first valve seat 3141. After the solenoid valve 341 is powered off, the return spring 343 pushes the sealing valve 342 upward to open the air-guiding passage between the second chamber 314 and the first pipeline 315 and the air outlet 312. At the same time, under the action of the return spring 343, the sealing valve skeleton 3422 abuts against the step of the first positioning ring of the valve stem 3421, which is conducive to improving the stability of the connection between the valve stem 3421 and the sealing skeleton.

[0050] Furthermore, the pipeline switching assembly 34 also includes a bracket 344, a connecting hole is set in the middle of the bracket 344, the sealing valve 342 is connected to the solenoid valve 341 through the connecting hole, and a rib 3441 is set on the bracket 344 for limiting the movement path of the sealing valve 342. The sealing valve skeleton 3422 and the rib 3441 are clearance-matched in the circumferential direction, thereby ensuring the circumferential positioning.

[0051] 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, and the limiting ring 3442 can further ensure the centering degree of the sealing frame during the movement.

[0052] In another embodiment of the present 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 shell, and the second valve seat 331 has a mounting hole located at the center of the second valve seat 331 and at least one air hole located around the mounting hole; when there are two or more air holes, the air holes are evenly distributed around the mounting holes; 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 air holes; thereby achieving sealing of the air holes; when the pressure in the first pipeline 315 is relatively large, the pressure in the first pipeline 315 acts on the surface of the umbrella valve 332, so that the umbrella valve 332 rests on the air holes, thereby achieving sealing of the air holes.

[0053] Furthermore, the second valve seat 331 includes a main body 3311 and a connecting portion 3312 . The connecting portion 3312 is cylindrical with one end open and extends from the main body 3311 toward the first pipeline 315 . The outer wall of the connecting portion 3312 is abutted and fixed to the inner wall of the first pipeline 315 .

[0054] In order to improve the air tightness of the system, an elastic sealing ring is arranged 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 arranged 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.

[0055] Among them, the umbrella valve 332 includes a connecting rod 3321 and an umbrella-shaped sealing portion 3322, the valve stem 3421 and the umbrella-shaped sealing portion 3322 are integrally formed, the connecting rod 3321 is connected to the mounting hole, and the outer diameter of the valve stem 3421 gradually decreases from the end connected to the umbrella-shaped sealing portion 3322 to the end away from the umbrella-shaped sealing portion 3322, and a positioning portion is provided on the connecting rod 3321, and the positioning portion can abut against the side of the second valve seat 331 away from the first pipeline 315; such a setting method is conducive to the assembly and fixation between the valve stem 3421 and the second valve seat 331.

[0056] The umbrella-shaped sealing portion 3322 is made of rubber material, and the umbrella-shaped sealing portion 3322 can cover the air hole, thereby achieving one-way sealing of the air hole.

[0057] In another embodiment of the present application, a third chamber may be provided in the shell, and the third chamber 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 the pressure sensor, so that the pressure information in the system can be collected through the third chamber through the pressure sensor.

[0058] The solenoid valve 341 is a normally open solenoid valve 341; during use, when the engine is working and the diagnostic device is not working, the fuel tank isolation valve 40 is powered off and closed, the carbon canister control valve 60 is powered on and opened, the solenoid valve 341 is powered off and opened, and the air inlet 311 and the air outlet 312 of the housing are directly connected in the second chamber 314, such as 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, thereby ensuring low flow resistance of air when the carbon canister 20 is desorbed; when the solenoid valve 341 is energized, the solenoid valve 341 is closed, closing the passage connecting the air inlet 311 and the air outlet 312 inside the shell. The gas must be pumped from the air inlet 311 of the shell to the one-way valve assembly 33 inside the shell via an air pump, and pass through the first pipeline 315 to enter the carbon canister 20, forming a stable pressure for monitoring whether there is a leak in the system.

[0059] According to another aspect of the present application, the present application also provides a fuel evaporative emission leakage detection system for an engine, comprising a fuel tank 10, a carbon canister 20, a pressurizing assembly 32, a one-way valve assembly 33 and a pressure detection device 40, wherein the carbon canister 20 is connected to the fuel tank 10 and the engine intake system 70 respectively through pipelines, a fuel tank isolation valve is provided between the carbon canister 20 and the fuel tank 10, and the fuel tank isolation valve 50 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 10 and the engine intake system 70, and the first carbon canister control valve is used to control the pipeline connection between the carbon canister 20 and the engine intake system 70, and the pressure detection device 40 is used to detect the internal pressure of the fuel tank, the carbon canister 20 is connected to the pressurizing assembly 32 through the one-way valve assembly 33, the carbon canister 20 is connected to the external air pipeline, and a second carbon canister control valve is provided between the carbon canister 20 and the external air, and the second carbon canister control valve is used to control the air path connection between the carbon canister and the external control.

[0060] Among them, the first carbon canister control valve and the second carbon canister control valve can be solenoid valves. Through the opening and closing of the first carbon canister control valve and the second carbon canister control valve, direct connection between the carbon canister and the external atmosphere, or connection between the carbon canister and the one-way valve assembly can be achieved.

[0061] According to another aspect of the present application, the present application also provides a method for detecting fuel evaporative emission leakage of an engine, the method adopting the aforementioned detection system, the method comprising the following steps: During the diagnostic process, Fig. 9 As shown, Fig. 9 The middle arrow indicates the direction of air flow. The solenoid valve 341 is energized, and 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 fuel tank isolation valve 50 is opened, and the air between the fuel tank 10 and the carbon canister 20 is connected. The pressurizing component 32 is started to pressurize the fresh air entering from the air inlet 311. The pressurized gas passes through the one-way valve component 33, passes through the first pipeline 315, enters the carbon canister 20 from the air outlet 312, and finally enters the fuel tank 10, pressurizing the internal pressure of the fuel tank 10 to the first threshold value P1. The time difference ∆t between the pressure of the fuel tank 10 dropping to the second threshold value P2 and the third threshold value 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.

[0062] According to another aspect of the present application, the present application also provides a method for detecting fuel evaporative emission leakage of an engine, the method adopting the aforementioned detection system, comprising the following steps: The solenoid valve 341 is energized, and 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; the fuel tank isolation valve 50 is opened, and the pressurizing device is started to pressurize the fresh air entering from the air inlet 311. The pressurized gas passes through the one-way valve, passes through the first pipeline 315, enters the carbon canister 20 from the air outlet 312, and finally enters the fuel tank 10, pressurizing the internal pressure of the fuel tank 10 to the first threshold value P1; the integral value S of the fuel tank 10 pressure P from the moment when the second threshold value P2 is reached to the moment when the third threshold value P3 is reached is calculated, that is, ; Compare the integral value S with the system preset value. When the integral value S is less than the system preset value, there is a leak in the system.

[0063] In the description of the present invention, it should be understood that the directions or positional relationships indicated by directional words such as "front, back, up, down, left, right", "lateral, vertical, perpendicular, horizontal" and "top, bottom" are usually based on the directions or positional relationships shown in the drawings. They are only for the convenience of describing the present invention and simplifying the description. Unless otherwise specified, these directional words do not indicate or imply that the devices or elements referred to must have a specific direction or be constructed and operated in a specific direction. Therefore, they cannot be understood as limiting the scope of protection of the present invention. The directional words "inside and outside" refer to the inside and outside relative to the contours of each component itself.

[0064] For ease of description, spatially relative terms such as "above", "above", "on the upper surface of", "above", etc. may be used herein to describe the spatial positional relationship between a device or feature and other devices or features as shown in the figure. It should be understood that spatially relative terms are intended to include different orientations of the device in use or operation in addition to the orientation described in the figure. For example, if the device in the accompanying drawings is inverted, the device described as "above other devices or structures" or "above other devices or structures" will be positioned as "below other devices or structures" or "below other devices or structures". Thus, the exemplary term "above" may include both "above" and "below". The device may also be positioned in other different ways (rotated 90 degrees or in other orientations), and the spatially relative descriptions used herein are interpreted accordingly.

[0065] In addition, it should be noted that the use of terms such as "first" and "second" to limit components is only for the convenience of distinguishing the corresponding components. If not otherwise stated, the above terms have no special meaning and therefore cannot be understood as limiting the scope of protection of the present invention.

[0066] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A fuel evaporative emission leakage detection system for an engine, characterized in that: The invention comprises a fuel tank, a carbon canister, a diagnostic device and a pressure detection device, wherein the carbon canister is respectively connected to the fuel tank and the intake system fluid of the engine, a fuel tank isolation valve is arranged between the carbon canister and the fuel tank, a carbon canister control valve is arranged between the carbon canister and the engine, and the carbon canister control valve is used to control the fluid connection between the carbon canister and the engine, the diagnostic device comprises an air inlet and an air outlet, the air inlet is connected to the atmosphere, and the air outlet is connected to the carbon canister, a pressurizing component, a one-way valve component and a pipeline switching component are arranged in the diagnostic device, a first ventilation path and a second ventilation path connecting the air inlet and the air outlet are formed in the diagnostic device, wherein the first ventilation path directly connects the air inlet with the air outlet, and the second ventilation path connects the air inlet with the pressurizing component, the one-way valve and the air outlet in sequence, and the pipeline switching component switches the first ventilation path and the second ventilation path in the diagnostic device based on the detection demand to realize the air path connection between the air inlet and the air outlet.

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

3. The fuel evaporative emission leakage detection system for an engine according to claim 1, characterized in that: The diagnostic device also includes: a shell, the shell includes an air inlet, an air outlet, a first chamber and a second chamber, 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 through a first pipeline; the pressurizing component is fixedly connected to the shell, and the pressurizing component is arranged on a side of the first chamber away from the first pipeline; the one-way valve component is connected to the shell, the one-way valve component is arranged in the first chamber and is located between the pressurizing component and the first pipeline; the pipeline switching component is located in the second chamber, and the pipeline switching component is used to control the fluid connection 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 component can pass through the one-way valve, the first pipeline, and the second chamber in sequence, and finally leave the shell from the air outlet.

4. The fuel evaporative emission leakage detection system for an engine according to claim 3, 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 portion, 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 at 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. Driven by electromagnetic force and under the action of the return spring, the sealing valve reciprocates in the second chamber.

5. The fuel evaporative emission leakage detection system for an engine according to claim 4, characterized in that: The sealing valve includes a valve stem, a sealing valve frame and an elastic sealing portion. 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 portion is connected to the sealing frame and can abut against the first valve seat under the action of the solenoid valve.

6. The fuel evaporative emission leakage detection system for an engine according to claim 3, characterized in that: The one-way valve assembly comprises: A second valve seat, at least a portion of which is sealed and fixedly connected to the housing, and the second valve seat has a mounting hole located at the center of the second valve seat and at least one air-permeable 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 elastic material, and the elastic material covers the air hole.

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

8. A fuel evaporative emission leakage detection system for an engine, characterized in that: It includes a fuel tank, a carbon canister, a pressurizing device, a one-way valve and a pressure detecting device, wherein the carbon canister is connected to the fuel tank and the engine respectively through pipelines, a fuel tank isolation valve is arranged 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 arranged 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 detecting device is used to detect the internal pressure of the fuel tank, the carbon canister is connected to the pressurizing device through a one-way valve, the carbon canister is connected to the external air pipeline, a second carbon canister control valve is arranged 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.

9. A method for detecting fuel evaporative emission leakage of an engine, the method using the detection system according to any one of claims 1 to 8, the method comprising the following steps: The gas path between the carbon canister and the outside air is closed, and the fuel tank isolation valve is opened, and the internal pressure of the fuel tank is pressurized to a first threshold value P1 by the pressurizing device; Record the time difference ∆t between when the fuel tank pressure drops to the second threshold value P2 and the third threshold value P3; The time difference ∆t is compared with a system preset time. When the time difference ∆t is less than the system preset time, there is a leak in the system.

10. A method for detecting fuel evaporative emission leakage of an engine, the method using the detection system according to any one of claims 1 to 8, the method comprising the following steps: The gas path between the carbon canister and the outside air is closed, and the fuel tank isolation valve is opened, and the internal pressure of the fuel tank is pressurized to a first threshold value P1 by the pressurizing device; Calculate the integral value S of the tank pressure P from the time when it reaches the second threshold value P2 to the time when the third threshold value P3 is reached, that is, ; The integral value S is compared with a system preset value. When the integral value S is smaller than the system preset value, there is a leak in the system.

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