Leak diagnostor for evaporative emission system

Abstract

The utility model provides a leakage diagnosis device for an evaporative emission system. The leakage diagnosis device comprises a shell, an air pump assembly, a one-way valve assembly and a pipeline switching assembly. The shell comprises an air inlet and an air outlet, a first cavity, a second cavity and a third cavity are formed in the shell, the first cavity and the third cavity are communicated with the air inlet, the air outlet is communicated with the third cavity, the one-way valve assembly is located in the second cavity, and the pipeline switching assembly is located in the third cavity. The pipeline switching assembly is used for controlling communication between the first pipeline and the third cavity; the first chamber, the second chamber and the third pipeline are arranged in the shell, and the pipeline switching assembly is arranged in the third chamber, so that switching of different gas guide passages of the first chamber, the atmosphere outlet and the carbon tank is realized, pressure is favorably established for the evaporation system, the pressure is detected, and the running state of the system is quickly and accurately judged; and judging whether leakage exists in the system.

Description

TECHNICAL FIELD

[0001] The utility model relates to vehicle detection technical field, specifically, relate to a kind of for evaporative emission system's leak diagnostic apparatus. BACKGROUND

[0002] With the increasingly serious automobile exhaust pollution, the increasingly strict constraint of the promulgated automobile exhaust emission regulations to vehicle allowed to atmospheric emission, it is necessary to detect the leakage of evaporative emission system consisting of fuel tank and entire evaporation pipeline during the use of vehicle, and the fuel tank leakage diagnosis module emerges as the times require in this process.

[0003] The leakage diagnosis method of fuel evaporation emission system in prior art is to set DMTL module in evaporative emission system, the module is an integrated motor-driven rotary vane pump and solenoid valve, the internal flow passage of module is designed with main cavity and high-pressure cavity for atmosphere, and a reference hole for calibration is designed on high-pressure cavity. DMTL leakage diagnosis module has two working states during diagnosis, which are reference mode and diagnosis mode, and the switching of the two modes is controlled by solenoid valve. It realizes the opening and closing of valve by energizing the solenoid coil in the valve and driving the iron core and valve together by the electromagnetic force generated by the solenoid coil, and realizes two working conditions of rotary vane pump for reference hole and for entire evaporative emission system by switching of solenoid valve, and compares the motor current of rotary vane pump in two working conditions, to judge whether there is leakage above 0.5mm hole by current comparison. But due to the small diagnosis current of rotary vane pump, the value is 20-50mA, the diagnosis result itself is greatly affected by environment, especially air humidity, friction of rotary vane pump and factors such as wear and foreign matter jamming. From the actual feedback from the market, the probability of misdiagnosis is large, and the reference hole is set between solenoid valve and rotary vane pump, the pipeline is complex, and the accuracy of detection result is low.

[0004] Therefore, the prior art has the technical problems of existing diagnosis method being greatly affected by environment, high misdiagnosis rate and low accuracy of detection result. UTILITY MODEL CONTENT

[0005] The main purpose of the utility model is to provide a kind of for evaporative emission system's leak diagnostic apparatus, to solve the technical problems of existing diagnosis method being greatly affected by environment, high misdiagnosis rate and low accuracy of detection result in relevant technologies.

[0006] In order to achieve the above purpose, according to one aspect of the utility model, a kind of for evaporative emission system's leak diagnostic apparatus is provided, and the leak diagnostic apparatus includes:

[0007] A shell comprising an air inlet, an air outlet, a first chamber, a second chamber and a third chamber formed in the shell, the first chamber and the third chamber being in communication with the air inlet, the air outlet being in communication with the third chamber, the first chamber and the second chamber being in communication through a first pipeline, the second chamber and the third chamber being in communication through a second pipeline;

[0008] A gas pump assembly located in the first chamber, the gas pump assembly having a high-pressure air outlet connected to the first pipeline at a first end of the first chamber;

[0009] A one-way valve assembly arranged in the second chamber and allowing high-pressure gas in the first chamber to be transmitted to the third chamber through the one-way valve in one direction;

[0010] A pipeline switching assembly located in the third chamber, the pipeline switching assembly comprising an electromagnetic valve, a sealing valve and a return spring, the pipeline switching assembly being used to control the fluid communication between the second pipeline and the third chamber, so that when the second pipeline is in communication with the third chamber, the gas pressurized by the gas pump assembly can pass through the first pipeline, the one-way valve assembly, the second pipeline, the third chamber in sequence, and finally leave the shell from the air outlet.

[0011] Further, a first valve seat is arranged on the side of the third chamber close to the second pipeline, the first valve seat being a cylindrical structure with one end open, the bottom surface and / or the side surface of the first valve seat being in communication with the air outlet, at least a part of the pipeline switching assembly being able to abut against the first valve seat to close or open the air passage between the third chamber and the air outlet; the bottom of the first valve seat is provided with a first air passage hole in communication with the second pipeline.

[0012] Further, the electromagnetic valve comprises a fixed core and an armature, a through hole is arranged in the center of the fixed core, at least a part of the sealing valve passes through the through hole in the center of the fixed core, and reciprocates in the third chamber under the driving of electromagnetic force and the action of the return spring.

[0013] Further, the sealing valve comprises a valve rod, a sealing valve skeleton and an elastic sealing part, one end of the valve rod passes through the through hole in the center of the fixed core, the other end of the valve rod is detachably connected with the sealing valve skeleton, the elastic sealing part is connected with the sealing valve skeleton and can abut against the first valve seat under the action of the electromagnetic valve.

[0014] Further, the pipeline switching assembly further comprises a bracket, a communication hole is arranged in the middle part of the bracket, the sealing valve is connected with the electromagnetic valve through the communication hole, and a rib plate for defining the movement path of the sealing valve is arranged on the bracket.

[0015] Further, the one-way valve assembly comprises a second valve seat sealingly and fixedly connected with the second chamber, the second valve seat having a mounting hole at the center of the second valve seat and at least one air passage hole at the periphery of the mounting hole; and an umbrella-shaped valve fixedly connected with the second valve seat through the mounting hole, at least a part of the umbrella-shaped valve being made of elastic material, the elastic material covering the air passage hole.

[0016] Further, an elastic sealing member is arranged between the second valve seat and the second chamber.

[0017] Further, the umbrella-shaped valve comprises a valve rod connected with the mounting hole and an umbrella-shaped sealing part, a positioning part being arranged on the valve rod and capable of abutting against the side of the valve seat close to the first chamber.

[0018] Further, the shell comprises an upper shell, a lower shell and a bottom cover, the upper part of the lower shell being connected with the upper shell, the lower part of the lower shell being connected with the bottom cover, and at least a part of the path of the first pipeline being jointly formed by the lower shell and the bottom cover.

[0019] Further, a positioning groove is arranged on the bottom cover.

[0020] Further, one end of the reset spring abuts against the elastic sealing part, and the other end of the reset spring abuts against the first valve seat.

[0021] The leakage diagnostic device for the evaporative emission system provided by the utility model, by arranging the first chamber, the second chamber, the third chamber, the first pipeline and the second pipeline in the shell and arranging the pipeline switching assembly in the second chamber, a plurality of air guide paths are formed between the first chamber and the carbon canister, different air guide paths of the first chamber, the atmospheric outlet and the carbon canister are realized, and the pressure of the evaporative system is established, so that the running state of the system is judged quickly and accurately by detecting the pressure, whether the system leaks is judged, the structure is simple, and the assembly is convenient. BRIEF DESCRIPTION OF DRAWINGS

[0022] The drawings accompanying the specification of this application form a part hereof, serve to provide further understanding of the utility model, and together with the specification explain the utility model. The utility model is shown in the drawings, and the specific embodiments of the utility model and the description thereof are used to explain the utility model, and do not constitute an improper limitation on the utility model. In the drawings:

[0023] Figure 1 The external structure schematic view of the leakage diagnostic device for the evaporative emission system according to the utility model is shown;

[0024] Figure 2 The sectional view of the electromagnetic valve closed state of the leakage diagnostic device according to the utility model is shown.

[0025] Figure 3 A cross-sectional view of an electromagnetic valve open state of the leakage diagnostic device according to the present application is shown;

[0026] Figure 4 A structural schematic view of a lower shell according to the present application is shown;

[0027] Figure 5 A structural schematic view of a pipeline switching assembly according to the present application is shown;

[0028] Figure 6 A structural schematic view of a sealing valve according to the present application is shown;

[0029] Figure 7 A structural schematic view of an umbrella valve according to the present application is shown;

[0030] Figure 8 A structural schematic view of a bracket according to the present application is shown.

[0031] Among the above drawings, the following reference signs are included:

[0032] 10, shell; 11, air inlet; 12, air outlet; 13, first chamber; 14, second chamber; 15, third chamber; 151, first valve seat; 152, first air hole; 16, first pipeline; 17, second pipeline; 1A, upper shell; 10B, lower shell; 10C, bottom cover; 20, air pump assembly; 30, one-way valve assembly; 31, second valve seat; 311, air hole; 32, umbrella valve; 321, connecting rod; 322, umbrella sealing part; 33, elastic sealing ring; 40, pipeline switching assembly; 41, electromagnetic valve; 411, fixed iron core; 412, armature; 42, sealing valve; 421, valve rod; 422, sealing valve framework; 423, elastic sealing part; 43, return spring; 44, bracket; 441, rib plate; 442, limiting ring. DETAILED DESCRIPTION

[0033] The technical solutions in the embodiments of the present application will be apparently and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. The description of the at least one exemplary embodiment is actually only illustrative, but not as any limitation on the present application and its application or use. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the present application.

[0034] It is to be understood that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of example embodiments in accordance with the present application. As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms "comprises" and / or "comprising," when used in this specification, specify the presence of stated features, steps, operations, elements, components, and / or groups thereof, but do not preclude the presence or addition of one or more other features, steps, operations, elements, components, and / or groups thereof.

[0035] The relative arrangement of parts and steps, numerical expressions, and numerical values set forth in the examples are not intended to limit the scope of the present application unless otherwise specifically stated. It is to be understood that the actual dimensions of the parts shown in the drawings are not necessarily to scale as the dimensions are shown by way of example and illustration. Techniques, methods, and apparatus known to those of ordinary skill in the relevant art can not be discussed in detail, but should be considered as if the disclosed methods, techniques and apparatus were explicitly set forth in this patent. In all examples shown and discussed herein, any specific values are to be interpreted as illustrative only and not limiting. Thus, other examples of example embodiments can have different values. It is to be noted that like numbers and letters refer to like elements throughout the several views of the drawings and, as such, no further discussion with regard thereto is needed.

[0036] With the increasing seriousness of automobile exhaust pollution, the constraints on vehicle emissions into the atmosphere in emission regulations are becoming more and more stringent. Therefore, in the process of using the vehicle, in order to avoid the volatiles in the fuel tank directly into the air, a carbon can is usually arranged between the fuel tank and the atmosphere to absorb the evaporation emissions in the fuel tank. In order to ensure the absorption effect, it is necessary to detect the leakage of the evaporation emission system composed of the fuel tank and the entire evaporation pipeline.

[0037] However, as described above, the existing detection method using the DMTL module has a high probability of misdiagnosis, and the reference hole is arranged between the electromagnetic valve and the rotary vane pump, the pipeline is complex, and the accuracy of the detection result is low.

[0038] In order to solve the technical problems of complex pipeline and complicated installation process in the prior art, the utility model provides a leakage diagnostic device for evaporation emission system.

[0039] As Figures 1 to 6As shown, the utility model provides a kind of for evaporative emission system's leak diagnostic apparatus, and leak diagnostic apparatus includes shell 10, air pump assembly 20, one-way valve assembly 30, pipeline switching assembly 40;Wherein, shell 10 includes air inlet 11, air outlet 12, air inlet 11 is communicated with external air, for providing fresh air for system, air outlet 12 is communicated with carbon tank, so that high-pressure air or fresh air can be selectively introduced into oil tank by carbon tank;First chamber 13, second chamber 14 and third chamber 15 are formed in the shell 10, the first chamber 13 and third chamber 15 are communicated with the air inlet 11 respectively, the air outlet 12 is communicated with the third chamber 15, the first chamber 13 and second chamber 14 are communicated by first pipeline 16, and second chamber 14 and third chamber 15 are communicated by second pipeline 17;So that the first chamber 13 has two air guide paths capable of being communicated with external atmosphere and air outlet 12 respectively.

[0040] Wherein, air inlet 11 is arranged in the middle of shell 10, between first chamber 13 and third chamber 15, and such arrangement facilitates the pipeline arrangement between first chamber 13 and third chamber 15 and air inlet 11.

[0041] Further, the shell 10 includes upper shell 10A, lower shell 10B and bottom cover 10C, the upper part of the lower shell 10B is connected with the lower part of the upper shell 10A, and the lower part of the lower shell 10B is connected with the bottom cover 10C. Optionally, the upper shell 10A and the lower shell 10B can be connected by snap connection or laser welding, and the lower part of the lower shell 10B and the bottom cover 10C are fixed by laser welding. The first chamber 13 and the third chamber 15 are jointly enclosed by the upper shell 10A and the lower shell 10B, the air inlet 11, the air outlet 12, the second chamber 14 and the first pipeline 16 are all arranged on the lower shell 10B, and the upper shell 10A is provided with an electrical connector for electrical connection with the vehicle, and at least a part of the path of the first pipeline 16 is jointly enclosed by the lower shell 10B and the bottom cover 10C.

[0042] Optionally, the upper shell 10A and the lower shell 10B are both integrally formed, so as to reduce the cost and further improve the air tightness of the shell.

[0043] The air pump assembly 20 is fixedly connected with the shell 10, the air pump assembly 20 has a high-pressure exhaust port, the high-pressure exhaust port is connected with the first pipeline 16, the air pump assembly 20 can pressurize the air entering the first chamber 13 and transmit the pressurized high-pressure air to the one-way valve assembly 30. The one-way valve assembly 30 is connected with the shell 10, the one-way valve assembly 30 is arranged in the second chamber 14, and the high-pressure gas in the first chamber 13 can be transmitted to the third chamber 15 in one way through the one-way valve. The pipeline switching assembly 40 is located in the third chamber 15, the pipeline switching assembly 40 includes an electromagnetic valve 41, a sealing valve 42 and a reset spring 43, and the pipeline switching assembly 40 is used for controlling the fluid communication between the second pipeline 17 and the third chamber 15, so that when the second pipeline 17 is communicated with the third chamber 15, the gas pressurized by the air pump assembly can pass through the first pipeline 16, the one-way valve assembly 30, the second pipeline 17, the third chamber 15 in turn, and finally leave the shell 10 from the air outlet 12 and enter the carbon canister.

[0044] The leakage diagnostic device provided by the utility model has the advantages that the first chamber 13, the second chamber 14 and the third chamber 15 are arranged in the shell, the first chamber 13 and the second chamber 14 are connected through the first pipeline 16, the second chamber 14 and the third chamber 15 are connected through the second pipeline 17, and the pipeline switching assembly 40 is arranged in the third chamber 15, so that a plurality of air guide paths are formed between the first chamber 13 and the carbon canister, different air guide paths of the first chamber 13, the air outlet and the carbon canister are realized, and the structure is simple and convenient to assemble.

[0045] Further, the side of the third chamber 15 close to the first pipeline 16 is provided with a first valve seat 151, the first valve seat 151 is in a cylindrical structure with one end being open, the bottom surface and / or the side surface of the first valve seat 151 are communicated with the air outlet 12, the sealing valve 42 can abut against the first valve seat 151 under the drive of the electromagnetic valve 41 to close or open the air passage between the air inlet 11, the third chamber 15 and the air outlet 12; the bottom of the first valve seat 151 is provided with a first air passage hole 152, the first air passage hole 152 is communicated with the second pipeline 17; so that when the sealing valve 42 abuts against the first valve seat 151, the sealing valve 42 simultaneously cuts off the communication paths between the third chamber 15 and the first chamber 13 and between the third chamber 15 and the outside.

[0046] Preferably, the first valve seat 151 further has a spring abutting portion, the center of the spring abutting portion is formed with the first air passage hole 152, and the outer diameter of the spring abutting portion matches the inner diameter of the reset spring 43 to realize the quick assembly and positioning of the reset spring 43.

[0047] The air pump is located in the first chamber 13, the air inlet 11 of the shell 10 is communicated with the chamber away from the first chamber 13 of the air pump, the external fresh air enters the chamber away from the first chamber 13 of the air pump through the air inlet 11, the inlet of the air pump is communicated with the chamber, the outlet of the air pump is communicated with the one-way valve assembly 30, the fresh air is pressurized by the air pump, and then sequentially passes through the first pipeline 16, the one-way valve, the second chamber 14, the third chamber 15, the air outlet 12 and enters the carbon tank, so that the pressure of the evaporation system is established.

[0048] The electromagnetic valve 41 comprises a fixed core 411 and an armature 412, at least a part of the sealing valve 42 passes through the through hole in the center of the fixed core 411 and is axially positioned, and under the driving of the electromagnetic force and the action of the reset spring 43, the sealing valve 42 reciprocates in the third chamber 15.

[0049] Specifically, the sealing valve 42 comprises a valve rod 421, a sealing valve skeleton 422 and an elastic sealing part 423, one end of the valve rod 421 passes through the through hole in the center of the fixed core 411, the other end of the valve rod 421 is detachably connected with the sealing valve skeleton 422, the elastic sealing part 423 is connected with the sealing skeleton and can abut against the first valve seat 151 under the action of the electromagnetic valve 41, so as to realize the sealing of the first valve seat 151.

[0050] Preferably, the elastic sealing part 423 is made of rubber material and can be fixed with the sealing skeleton by vulcanization; the valve rod 421 is provided with a first positioning ring and a second positioning ring, the sealing skeleton is provided with a mounting part and an avoiding opening, the valve rod 421 is fixedly connected with the mounting part through the avoiding opening and is mounted and positioned to the mounting part through the first positioning ring and the second positioning ring.

[0051] In order to ensure the smooth opening of the passage, one end of the reset spring 43 abuts against the elastic sealing part 423, and the other end of the reset spring 43 abuts against the spring abutting part in the first valve seat 151, after the electromagnetic valve 41 is powered off, the reset spring 43 pushes the sealing valve 42 upward to open the air guide passage between the third chamber 15 and the second pipeline 17 and the air outlet 12. At the same time, under the action of the reset spring 43, the sealing valve skeleton 422 abuts against the step of the first positioning ring of the valve rod 421, so as to facilitate the stability of the connection between the valve rod 421 and the sealing skeleton.

[0052] Further, the pipeline switching assembly 40 further comprises a bracket 44, the middle part of the bracket 44 is provided with a communication hole, the sealing valve 42 passes through the communication hole and is connected with the electromagnetic valve 41, the bracket 44 is provided with a rib plate 441 for limiting the movement path of the sealing valve 42, and the sealing valve skeleton 422 and the rib plate 441 are in clearance fit in the circumferential direction, so as to ensure the circumferential positioning.

[0053] Among them, the rib plate 441 can be provided with three, three rib plates 441 are uniformly distributed around the sealing framework, the front end of the rib plate 441 can also be provided with a limiting ring 442, through the limiting ring 442 can further guarantee the centering degree of the sealing framework in the movement process.

[0054] In another embodiment of the present application, the one-way valve assembly 30 comprises a second valve seat 31 and an umbrella-shaped valve 32, at least a part of the second valve seat 31 is sealingly and fixedly connected with the shell, the second valve seat 31 has a mounting hole located at the center of the second valve seat 31 and at least one air hole 311 located around the mounting hole; when the air hole 311 is two or more, the air holes 311 are uniformly distributed around the mounting hole; the umbrella-shaped valve 32 is fixedly connected with the second valve seat 31 through the mounting hole, at least a part of the umbrella-shaped valve 32 is of elastic material, and the elastic material covers the air hole; so as to realize the sealing of the air hole; when the pressure in the first pipeline 16 is larger, the pressure in the first pipeline 16 acts on the surface of the umbrella-shaped valve 32, so that the umbrella-shaped valve 32 abuts against the air hole, thereby realizing the sealing of the air hole.

[0055] The second valve seat 31 is located in the third chamber 15 and connected with the third chamber 15, for example, the second valve seat 31 and the inner wall of the third chamber 15 can be in interference fit, and an elastic sealing ring 33 can be arranged between the second valve seat 31 and the third chamber 15 to ensure the sealing between the one-way valve assembly 30 and the second valve seat 31.

[0056] The inner wall of the third chamber 15 is also provided with a positioning step capable of abutting against the second valve seat 31, when the second valve seat 31 is assembled with the third chamber 15, the end of the second valve seat 31 abuts against the end face of the positioning step, thereby realizing the axial positioning of the second valve seat 31, such arrangement can effectively avoid the movement of the second valve seat 31 in the third chamber 15, and improve the stability during use of the product.

[0057] Among them, the umbrella-shaped valve 32 comprises a connecting rod 321 and an umbrella-shaped sealing part 322, the valve rod 421 and the umbrella-shaped sealing part 322 are integrally formed, the connecting rod 321 is connected with the mounting hole, the outer diameter of the valve rod 421 gradually decreases from the end connected with the umbrella-shaped sealing part 322 to the end away from the umbrella-shaped sealing part 322, the connecting rod 321 is provided with a positioning part capable of abutting against the side of the second valve seat 31 close to the first chamber 13; such arrangement is conducive to the assembly and fixation between the valve rod 421 and the second valve seat 31.

[0058] Among them, the umbrella-shaped sealing part 322 is made of rubber material, and the umbrella-shaped sealing part 322 can cover the air hole, thereby realizing the one-way sealing of the air hole.

[0059] In use, the electromagnetic valve 41 is a normally open electromagnetic valve 41; when the electromagnetic valve 41 is powered off, the electromagnetic valve 41 is opened, the air inlet 11 and the air outlet 12 of the shell are directly communicated in the third chamber 15, and low flow resistance of air during desorption of the carbon tank is ensured; when the electromagnetic valve 41 is powered on, the electromagnetic valve 41 is closed, the channel between the air inlet 11 and the air outlet 12 in the shell is closed, and gas must be pumped from the air inlet 11 of the shell to the one-way valve assembly 30 in the shell through the gas pump, enter the third chamber 15 through the second pipeline 17, and finally enter the carbon tank through the air outlet 12, so that a stable pressure is formed, and whether a leakage exists in the monitoring system is monitored.

[0060] Specifically, whether a leakage exists can be determined by using various pressure detection modes, for example:

[0061] By pressurizing the oil tank, the pressure inside the oil tank is established to 5kPa (a set value), the time for establishing the pressure is compared with the time for establishing the pressure when the oil tank has a standard leakage hole, and the time for decompression is compared with the time for decompression when the oil tank has a standard leakage hole; if the time for decompression is relatively long, it can be considered that a leakage exists in the system, or the diaphragm pump itself has a fault and cannot realize rapid pressure establishment; or,

[0062] After the system is established to 5kPa, whether the oil tank and the evaporative emission system have a leakage is determined by comparing the time for the pressure of the evaporative system to decrease from 4kPa to 3kPa; if the time for decompression is relatively short compared with the set time, or the speed for decompression is faster than the set speed, a leakage exists; or,

[0063] After the system is established to 5kPa, whether the oil tank and the evaporative emission system have a leakage is determined by comparing the time for the pressure of the evaporative system to decrease from 4kPa to 3kPa; if the time for decompression is relatively short compared with the set time, or the speed for decompression is faster than the set speed, a leakage exists; or,

[0064] In the description of the utility model, it is to be understood that the orientation words such as '' front, back, top, bottom, left, right '' '' horizontal, vertical, perpendicular, horizontal '' and '' top, bottom '' and the like indicated orientation or position relation is usually based on the orientation or position relation shown in the drawing, just for the convenience of describing the utility model and simplifying the description, under the condition of not making the opposite statement, these orientation words do not indicate and imply that the indicated device or element must have a particular orientation or be constructed and operated in a particular orientation, therefore, it cannot be understood as the limitation to the protection scope of the utility model; the orientation words '' inside, outside '' refer to the inside and outside relative to the contour of each component.

[0065] For purposes of the description hereinafter, spatial relative terms, such as "above", "below", "upper", "lower", and the like, can be used to describe the relative position of one element or feature to another as illustrated in the figures. It will be understood that the spatial relative terms are intended to encompass different orientations of the device in use or operation in addition to the orientations depicted in the figures. For example, if the device in the figures is turned over, elements described as "above" or "up" other elements or features would then be oriented "below" or "down" the other elements or features. Thus, the exemplary term "above" can encompass both an orientation of above and below. The device can be otherwise oriented (rotated 90 degrees or at other orientations) and the spatial relative descriptors used herein interpreted accordingly.

[0066] In addition, it should be noted that the use of "first", "second", and the like words of distinction do not connote any meaning of importance, but are used solely to differentiate one element from another, and are used in the context of this application without implying any specific order, or order of precedence. Accordingly, a first element that follows an operation can be performed before a second element that precedes the operation.

[0067] The preferred embodiments of the present application are described above in detail. The present application is not limited to the above embodiments, but can be modified in various ways by those skilled in the art without departing from the scope of the present application. Accordingly, the modifications, equivalent replacements, improvements, and the like based on the technical concept of the present application should be included in the scope of the present application.

Claims

1. A leak diagnostic for an evaporative emission system characterized by, The leakage diagnostic device comprises: a housing comprising an air inlet, an air outlet, a first chamber, a second chamber and a third chamber formed in the housing, the first chamber and the third chamber being in communication with the air inlet, the air outlet being in communication with the third chamber, the first chamber and the second chamber being in communication through a first pipeline, the second chamber and the third chamber being in communication through a second pipeline; a gas pump assembly located in the first chamber, the gas pump assembly having a high-pressure air outlet connected with the first pipeline at one end close to the first chamber; a one-way valve assembly arranged in the second chamber and allowing high-pressure gas in the first chamber to be transmitted to the third chamber through the one-way valve in one direction; a pipeline switching assembly located in the third chamber, the pipeline switching assembly comprising an electromagnetic valve, a sealing valve and a return spring, the pipeline switching assembly being used to control the fluid communication between the second pipeline and the third chamber, so that when the second pipeline is in communication with the third chamber, the gas pressurized by the gas pump assembly can pass through the first pipeline, the one-way valve assembly, the second pipeline, the third chamber in sequence and finally leave the housing from the air outlet.

2. A leak diagnostic for an evaporative emission system as in claim 1, wherein, A first valve seat is arranged on one side of the third chamber close to the second pipeline, the first valve seat being in a cylindrical structure with one end open, the bottom surface and / or the side surface of the first valve seat being in communication with the air outlet, at least a part of the pipeline switching assembly being capable of abutting against the first valve seat to close or open the air passage between the third chamber and the air outlet; the bottom of the first valve seat is provided with a first air passage hole in communication with the second pipeline.

3. A leak diagnostic for an evaporative emission system as in claim 2, wherein, The electromagnetic valve comprises a fixed core and an armature, a through hole is arranged in the center of the fixed core, at least a part of the sealing valve passes through the through hole in the center of the fixed core and reciprocates in the third chamber under the driving of electromagnetic force and the action of the return spring.

4. A leak diagnostic for an evaporative emission system as in claim 3, wherein, The sealing valve comprises a valve rod, a sealing valve skeleton and an elastic sealing part, one end of the valve rod passes through the through hole in the center of the fixed core, the other end of the valve rod is detachably connected with the sealing valve skeleton, the elastic sealing part is connected with the sealing valve skeleton and can abut against the first valve seat under the action of the electromagnetic valve.

5. A leak diagnosis device for an evaporative emission system according to claim 3, wherein The pipeline switching assembly further comprises a bracket, a communication hole is arranged in the middle of the bracket, the sealing valve is connected with the electromagnetic valve through the communication hole, and a rib plate for defining the movement path of the sealing valve is arranged on the bracket.

6. A leak diagnostica for an evaporative emission system as set forth in claim 1 wherein, The one-way valve assembly comprises: a second valve seat in sealing and fixed connection with the second chamber, the second valve seat having a mounting hole in the center of the second valve seat and at least one air passage hole around the mounting hole; an umbrella-shaped valve in fixed connection with the second valve seat through the mounting hole, at least a part of the umbrella-shaped valve being made of elastic material, the elastic material covering the air passage hole.

7. A leak diagnosis for evaporative emission systems as set forth in claim 6, characterized in that, An elastic sealing member is arranged between the second valve seat and the second chamber.

8. A leak diagnosis for an evaporative emission system according to claim 6 wherein, The umbrella-shaped valve comprises a valve rod connected with the mounting hole, and an umbrella-shaped sealing part, and a positioning part is arranged on the valve rod and capable of abutting against the side of the valve seat close to the first chamber.

9. A leak diagnosis for evaporative emission systems as set forth in claim 1, characterized in that, The shell comprises an upper shell, a lower shell and a bottom cover, the upper part of the lower shell is connected with the upper shell, the lower part of the lower shell is connected with the bottom cover, and at least a part of the path of the first pipeline is jointly surrounded by the lower shell and the bottom cover.

10. A leak diagnostic for an evaporative emission system as in claim 9, wherein, The bottom cover is provided with a positioning groove.

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