A leak diagnosis module and diagnosis method for gasoline vehicle evaporative emission system

Abstract

The present application relates to a kind of gasoline car evaporative emission system leak diagnosis module and diagnosis method, the leak diagnosis module includes shell, gas pump and multiple phase analysis switching component.The first cavity and second cavity with main hole are arranged in the shell, the gas pump is arranged in shell and its outlet is communicated with main hole, it is provided with driving motor and current sensor on driving motor.The multiple phase analysis switching component has conversion valve with multiple reference holes in the first cavity and switching motor for switching with conversion valve outside the second cavity.The leak diagnosis module is set to when gas pump works, by controlling the on-off position of multiple phase analysis switching component, it is switched between different phase reference mode and diagnosis mode corresponding to multiple reference holes, and the leak quantitative analysis of evaporative emission system is carried out to improve the accuracy of leak diagnosis.

Description

Technical Field

[0001] This invention relates to the field of leak diagnosis technology, and specifically to a leak diagnosis module and method for an evaporative emission system for gasoline vehicles. Background Technology

[0002] Currently, leak diagnosis modules for evaporative emission systems consisting of an oil tank and piping typically integrate a motor-driven air pump and a solenoid valve. The module's internal flow channel design includes a main chamber open to the atmosphere and a high-pressure chamber, with a reference port on the high-pressure chamber. During diagnosis, existing leak diagnosis modules operate in two modes: a reference mode and a diagnostic mode. Switching between these modes is controlled by a solenoid valve. Energizing the solenoid coil within the valve generates electromagnetic force, causing the iron core and valve to move together, thus opening and closing the solenoid valve.

[0003] However, solenoid valves can only be fully opened or fully closed, and cannot control the valve opening to control the fluid flow rate. Therefore, existing leak diagnosis modules, in reference mode, can only select a micro-orifice size as a reference orifice during the design phase (the reference orifice size is usually set to 0.5mm), and use the current when gas passes through this reference orifice during pump operation as a reference condition to evaluate the system's leakage. The leak diagnosis module, by comparing and analyzing the pump operating current curve of only one reference orifice, can only perform qualitative analysis to determine whether a leak has occurred; the leak diagnosis analysis is not precise enough and cannot meet future, more stringent evaporative emission requirements. Furthermore, solenoid valves often require significant electromagnetic force to overcome the high pressure within the oil tank to achieve their opening function, resulting in a larger size and weight for the solenoid coil and the valve itself. Summary of the Invention

[0004] The purpose of this invention is to provide a leak diagnosis module and method for evaporative emission systems in gasoline vehicles. This module can switch between reference modes and diagnostic modes corresponding to different phases of multiple reference orifices while the air pump is operating, performing quantitative leak analysis on the evaporative emission system to improve the accuracy of leak diagnosis. Simultaneously, it can reduce workload and decrease product weight and size.

[0005] To achieve the above objectives, according to a first aspect of the present invention, a leak diagnosis module for a gasoline vehicle evaporative emission system is provided, comprising:

[0006] The shell has a first cavity and a second cavity with a main hole inside.

[0007] An air pump is installed inside the housing and its outlet is connected to the main hole. A drive motor and a current sensor are installed on the drive motor.

[0008] The multi-phase analysis switching assembly includes a switching valve disposed in the first cavity and having multiple reference holes, and a switching motor disposed outside the second cavity for switching in conjunction with the switching valve.

[0009] The leak diagnosis module is configured to switch between reference modes and diagnostic modes of different phases by controlling the on / off position of the multi-phase analysis switching component when the air pump is working, so as to perform quantitative leak analysis on the evaporative emission system and improve the accuracy of leak diagnosis.

[0010] Optionally, the leak diagnosis module for the gasoline vehicle evaporative emission system further includes:

[0011] The control unit, connected to the current sensor, drive motor, and switching motor, is used to determine the reference current I under different phase reference modes acquired by the current sensor. ref And the diagnostic current I in diagnostic mode em c. Calculate the equivalent leakage orifice diameter ΦD of the current evaporative emission system. emc .

[0012] Optionally, the equivalent leakage orifice diameter ΦD of the current evaporative emission system emc In the diagnostic current I emc At the reference current I ref1 and I ref2 When the interval is between, it is obtained from the following formula:

[0013]

[0014] Where ΦD1 is the actual diameter of a reference hole, ΦD2 is the actual diameter of another reference hole with a diameter larger than that of the first reference hole, and K s1 K is the flow coefficient of a reference orifice. s2 T is the flow coefficient of another reference orifice. C K is the temperature compensation coefficient. Pamb This is the air pressure compensation coefficient.

[0015] Optionally, the diameters of the plurality of reference holes are 0 mm, 0.3 mm, and 0.5 mm, respectively.

[0016] Optionally, the multi-phase analysis switching component further includes:

[0017] The screw has one end threadedly connected to the motor rotor of the switching motor, and the other end extends into the switching valve through the second cavity and the first cavity in sequence.

[0018] A positioning bracket is disposed between the second cavity and the switching motor and sleeved on the screw. The contact portion between the positioning bracket and the screw is provided with a limiting groove for converting the circumferential rotation of the screw into axial movement.

[0019] A sealing element, which is fitted onto the screw and located within the first cavity, is used to seal the main hole or between the first cavity and the second cavity to change the gas flow path.

[0020] Optionally, the multi-phase analysis switching component further includes:

[0021] A filter screen is disposed on the sealing element and sleeved on the screw;

[0022] An inner sealing ring is disposed on the screw and located below the filter screen, and is used to cooperate with the sealing element to seal between the first cavity and the second cavity;

[0023] A buffer spring is disposed between the positioning bracket and the seal.

[0024] Optionally, the switching valve has a communication hole that communicates with the outlet of the air pump, and the plurality of reference holes are spaced apart on the inner wall of the communication hole;

[0025] The other end of the screw is provided with a connecting cylinder that extends into the connecting hole, and the side wall of the connecting cylinder is provided with mating holes corresponding to the multiple reference holes.

[0026] According to a second aspect of the present invention, a diagnostic method for a leak diagnostic module of an evaporative emission system for gasoline vehicles is provided, comprising the following steps:

[0027] The multi-phase analysis switching component is controlled to switch between reference modes and diagnostic modes for different phases;

[0028] Obtain the reference current in the reference mode and the diagnostic current in the diagnostic mode under different phases, and calculate the equivalent leakage orifice diameter of the current evaporative emission system.

[0029] The deterioration trend of evaporative emission system sealing is predicted based on changes in diagnostic current and equivalent leakage orifice diameter.

[0030] Optionally, controlling the multi-phase analysis switching component to switch between reference modes and diagnostic modes for different phases includes the following steps:

[0031] The switching motor of the multi-phase analysis switching component is controlled to rotate in the forward direction, which drives the screw of the multi-phase analysis switching component to move axially upward from the initial position to reach multiple phases in sequence to complete a diagnostic cycle;

[0032] The switching motor is controlled to rotate in the opposite direction, driving the screw back to its initial position.

[0033] Optionally, predicting the degradation trend of the equivalent leakage orifice diameter based on changes in diagnostic current and equivalent leakage orifice diameter includes the following steps:

[0034] The service life of the evaporative emission system is inferred based on the predicted degradation trend of the equivalent leakage orifice diameter.

[0035] The beneficial effects of this invention are as follows: When the air pump is working, by controlling the on / off position of the multi-phase analysis switching component with multiple reference holes, the system switches between reference modes and diagnostic modes corresponding to different phases of the multiple reference holes, thereby performing quantitative leak analysis on the evaporative emission system and improving the accuracy of leak diagnosis. Simultaneously, using a switching motor to drive the multi-phase analysis switching component reduces workload and minimizes product weight and size.

[0036] The above description is merely an overview of the technical solution of the present invention. In order to better understand the technical means of the present invention and to implement it in accordance with the contents of the specification, the preferred embodiments of the present invention are described in detail below with reference to the accompanying drawings. Attached Figure Description

[0037] Figure 1 This is a schematic structural diagram of a leak diagnosis module for an evaporative emission system in a gasoline vehicle, according to an embodiment of the present invention.

[0038] Figure 2 This is a schematic structural diagram of the switching valve of a leak diagnosis module for an evaporative emission system in a gasoline vehicle, according to an embodiment of the present invention.

[0039] Figure 3 This is a schematic structural diagram of the screw of a leak diagnosis module for an evaporative emission system in a gasoline vehicle, according to an embodiment of the present invention.

[0040] Figure 4 This is a schematic diagram of the gas flow path in the second reference mode of a leak diagnosis module for an evaporative emission system for gasoline vehicles, as shown in an embodiment of the present invention.

[0041] Figure 5 This is a schematic diagram of the gas flow path of a leak diagnosis module for a gasoline vehicle evaporative emission system in the third reference mode, according to an embodiment of the present invention.

[0042] Figure 6 This is a schematic diagram of the gas flow path in diagnostic mode of a leak diagnosis module for an evaporative emission system for gasoline vehicles, according to an embodiment of the present invention.

[0043] Figure 7This is a schematic diagram illustrating the changes in test current and outlet pressure with detection time under different modes of a leak diagnosis module for an evaporative emission system for gasoline vehicles, according to an embodiment of the present invention.

[0044] Figure 8 This is a schematic diagram illustrating the prediction of the deterioration trend of the sealing performance of an evaporative emission system according to an embodiment of the present invention;

[0045] Figure 9 This is a schematic flowchart illustrating a diagnostic method for a leak diagnosis module of an evaporative emission system for gasoline vehicles, according to an embodiment of the present invention.

[0046] In the diagram: 1-Housing, 11-Main hole, 12-First cavity, 13-Second cavity, 2-Air pump, 3-Multi-phase analysis switching component, 31-Conversion valve, 311-Connecting hole, 312-Precision stamping part, 313-First reference hole, 314-First reference flow channel, 315-Second reference hole, 316-Second reference flow channel, 32-Switching motor, 33-Screw, 331-Screw limiting part, 332-Connecting cylinder, 333-O-ring seal, 334-Vulcanized rubber part, 335-First mating hole, 336-Second mating hole, 34-Positioning bracket, 35-Seal, 351-Limiting fixing groove, 36-Filter screen, 37-Inner sealing ring, 38-Buffer spring. Detailed Implementation

[0047] The technical solution of the present invention will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0048] In the description of this invention, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing the invention and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the invention. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0049] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances. Furthermore, the technical features involved in the different embodiments of this invention described below can be combined with each other as long as they do not conflict with each other.

[0050] Please see Figure 1 This application discloses a preferred embodiment of a leak diagnosis module for an evaporative emission system in a gasoline vehicle. The module includes a housing 1, an air pump 2, and a multi-phase analysis switching assembly 3. The housing 1 contains a first cavity 12 and a second cavity 13 with a main orifice 11. The air pump 2 is housed within the housing 1, with its outlet connected to the main orifice 11. A drive motor and a current sensor are mounted on the air pump 2. The multi-phase analysis switching assembly 3 includes a switching valve 31 with multiple reference orifices located within the first cavity 12 and a switching motor 32 located outside the second cavity 13 for switching in conjunction with the switching valve 31. The leak diagnosis module is configured to switch between reference modes and diagnostic modes of different phases by controlling the on / off position of the multi-phase analysis switching assembly 3 when the air pump 2 is operating, thereby performing quantitative leak analysis on the evaporative emission system to improve the accuracy of leak diagnosis.

[0051] According to the solution of this embodiment, since the single reference hole setting in the reference mode of the traditional leak diagnosis module cannot meet the increasingly stringent requirements of evaporative emissions, this solution uses a switching motor 32 to drive multiple reference holes when the air pump 2 is working. A switching valve 31 with multi-phase analysis switching function precisely controls the on / off position of the multi-phase analysis switching component 3, switching between reference mode and diagnostic mode corresponding to different phases of the multiple reference holes. This allows for quantitative leak analysis of the evaporative emission system, improving the accuracy of leak diagnosis. Simultaneously, using a switching motor 32 to drive the multi-phase analysis switching component 3 reduces workload, shrinks product weight and size, and offers high versatility. Unlike solenoid valves and high-pressure tank isolation valves, it does not require replacement of internal elastic elements such as springs, and can be matched with high-pressure tanks of different pressure ranges.

[0052] The following detailed description uses specific examples:

[0053] Please see Figure 1 and Figure 4The multi-phase analysis switching assembly 3 also includes a screw 33, a positioning bracket 34, a seal 35, a filter 36, an inner sealing ring 37, and a buffer spring 38. One end of the screw 33 is threadedly connected to the rotor of the switching motor 32 located above the second cavity 13, and the other end of the screw 33 passes through the second cavity 13 and the first cavity 12 in sequence and extends into the switching valve 31. The positioning bracket 34 is located between the second cavity 13 and the switching motor 32 and is sleeved on the screw 33. The contact portion between the positioning bracket 34 and the screw 33 is provided with a limiting groove for converting the circumferential rotation of the screw 33 into axial movement. The seal 35 is located above the switching valve 31 inside the first cavity 12 and has a limiting fixing groove 351. It is limited and sleeved on the limiting part 331 of the screw through the limiting fixing groove 351, and is used to seal the main hole 11 or the space between the first cavity 12 and the second cavity 13 to change the gas flow path. In this embodiment, the seal 35 is a vulcanized assembly. The filter screen 36 is disposed on the seal 35 and sleeved on the screw 33. The inner sealing ring 37 is disposed on the screw 33 and located below the filter screen 36, and is used to cooperate with the seal 35 to seal the space between the first cavity 12 and the second cavity 13. The buffer spring 38 is disposed between the positioning bracket 34 and the seal 35.

[0054] Please see Figure 2 and Figure 3 The switching valve 31 has a connecting hole 311 that communicates with the outlet of the air pump 2, and multiple reference holes are spaced apart on the inner wall of the connecting hole 311. In this embodiment, a 0.3mm first reference hole 313 and a first reference flow channel 314 communicating with the first reference hole 313 are formed on the lower side of the connecting hole 311 through a precision stamping part 312, and a 0.5mm second reference hole 315 and a second reference flow channel 316 communicating with the second reference hole 315 are formed on the upper side of the connecting hole 311 through a precision stamping part 312. The other end of the screw 33 is provided with a connecting cylinder 332 that extends into the connecting hole 311. An O-ring 333 is fitted at the end of the connecting cylinder 332, and mating holes corresponding to the multiple reference holes are formed on the side wall of the connecting cylinder 332. A ring of vulcanized rubber 334 is provided around the mating holes for sealing. In this embodiment, the side wall of the connecting cylinder 332 is provided with a first mating hole 335 corresponding to the first reference hole 313 and a second mating hole 336 corresponding to the second reference hole 315.

[0055] In this embodiment, the leak diagnosis module is divided into four phases, which are distributed sequentially upwards from the initial position. The first to third phases correspond to three reference modes (with corresponding reference hole diameters of 0mm, 0.3mm, and 0.5mm, respectively), and the fourth phase corresponds to the diagnostic mode. Phase switching is achieved by controlling the position of the screw 33. When the leak diagnosis module is working, the switching motor 32 (stepper motor or servo motor) drives the screw 33 to rotate. Under the limiting groove of the positioning bracket 34, the screw 33 changes from circumferential rotation to axial movement, thereby changing the phase position. Using the first phase (initial position) as a reference, the power-on time of the switching motor 32 is controlled to change the rotation angle of the switching motor 32, thereby controlling the distance of each axial movement of the screw 33.

[0056] When the screw 33 is in the first phase (i.e., the initial position of the motor), the leakage diagnosis module is in the first reference mode. The first mating hole 335 and the first reference hole 313 are misaligned, the second mating hole 336 and the second reference hole 315 are misaligned, and the evaporation emission system is completely blocked. This is used to simulate a 0mm diameter leak in the evaporation emission system as a reference.

[0057] When screw 33 is in the second phase, the leakage diagnosis module is in the second reference mode. Screw 33 moves upward from its initial position, causing the first mating hole 335 and the first reference hole 313 on the communicating cylinder 332 to connect, while the second mating hole 336 and the second reference hole 315 are misaligned. Please refer to [link / reference]. Figure 4 In this state, the lower part of the seal 35 closes the main hole 11 next to the switching valve 31. The gas flowing out from the outlet of the air pump 2 enters the first reference hole 313 with a diameter of 0.3 mm through the connecting hole 311, and enters the second cavity 13 through the first reference flow channel 314 and the filter screen 36 to achieve reflux circulation, thereby simulating a 0.3 mm diameter leak in the evaporation emission system as a reference.

[0058] When screw 33 is in the third phase, the leakage diagnosis module is in the third reference mode. Screw 33 continues to move upward from the second phase, causing the second mating hole 336 and the second reference hole 315 on the communicating cylinder 332 to connect, while the first mating hole 335 and the first reference hole 313 are misaligned. Please refer to [link / reference]. Figure 5 In this state, since there is a gap between the screw limiting part 331 and the limiting fixing groove 351 on the seal 35, the upward movement of the screw 33 will not cause the seal 35 to move upward. The lower part of the seal 35 still closes the main hole 11 next to the switching valve 31. The gas flowing out from the outlet of the air pump 2 enters the second reference hole 315 with a diameter of 0.5 mm through the connecting hole 311, and enters the second cavity 13 through the second reference flow channel 316 and the filter screen 36 to achieve backflow circulation, thereby simulating a 0.5 mm diameter leak as a reference.

[0059] When screw 33 is in the fourth phase, the leak diagnosis module is in diagnostic mode, and screw 33 continues to move upward from the third phase. See also... Figure 6 When the screw 33 is positioned beyond the reference hole in the axial direction, the screw limiting part 331 will press against the limiting fixing groove 351 on the seal 35, thereby causing the seal 35 to move upward. When the screw 33 reaches the fourth phase, the upper part of the seal 35 can seal the first cavity 12 and the second cavity 13 from the outside. At the same time, the inner sealing ring 37 provided on the screw 33 can seal the filter screen 36, thereby sealing the first cavity 12 and the second cavity 13 from the inside. In this state, the gas flow path from the outlet of the air pump 2 cannot pass through the reference hole, but can only reach the carbon canister through the main hole 11, thus activating the diagnostic mode.

[0060] After the leak diagnosis module completes a diagnosis cycle, the switching motor 32 will automatically rotate in the reverse direction, causing the screw 33 to return to the first phase (initial position). After the reference mode is enabled, the switching motor 32 rotates in the forward direction, causing the screw 33 to move upward to start a new round of diagnosis cycle.

[0061] The leakage diagnosis module also includes a control unit (ECU) connected to the current sensor, drive motor, and switching motor 32, used to analyze the reference current I under different phase reference modes acquired by the current sensor. ref And the diagnostic current I in diagnostic mode emc Calculate the equivalent leakage orifice diameter of the current evaporative emission system.

[0062] ΦD emc Meanwhile, a pressure sensor connected to the ECU is installed at the outlet of the leak diagnostic module and the carbon canister to measure the outlet pressure.

[0063] Please see Figure 7 As can be seen, the larger the diameter of the reference orifice, the smaller the stable value of the reference current measured by the current sensor and the lower the outlet pressure. By setting multiple phase reference modes, a more accurate reference to the actual leakage situation can be provided in diagnostic mode.

[0064] Traditional leak diagnosis modules have only one 0.5mm diameter reference hole, and the obtained reference current is I. ref0.5 The current in diagnostic mode is I. emc When the actual leakage is less than the leakage of a reference hole with a diameter of 0.5 mm (i.e., I... emc >I ref0.5 When the actual leakage exceeds the leakage of the reference orifice with a diameter of 0.5 mm (i.e., I...), only the effectiveness of the evaporative emission system's seal can be determined. emc <I ref0.5In such cases, it can only be determined that the leakage of the evaporative emission system exceeds the standard. The above analysis is only a qualitative analysis and cannot perform quantitative calculations. It cannot determine whether the sealing performance of the evaporative emission system has deteriorated, nor can it provide guidance for preventive maintenance work for potential leakage of evaporative oil and gas caused by expected sealing control failures.

[0065] The leakage diagnosis module in this embodiment can detect the reference current I under different phase reference modes collected by the current sensor. ref And the diagnostic current I in diagnostic mode emc Calculate the equivalent leakage orifice diameter ΦD of the current evaporative emission system. emc This allows for quantitative analysis of leak diagnosis in evaporative emission systems.

[0066] The equivalent leakage orifice diameter ΦD of the current evaporative emission system emc In the diagnosis current I emc At reference current I ref1 and I ref2 When the interval is between, it is obtained from the following formula:

[0067]

[0068] Where ΦD1 is the actual diameter of a reference hole, ΦD2 is the actual diameter of another reference hole with a diameter larger than that of the first reference hole, and K s1 K is the flow coefficient of a reference orifice. s2 T is the flow coefficient of another reference orifice. C K is the temperature compensation coefficient. Pamb This is the air pressure compensation coefficient.

[0069] For example, the diagnostic current in the first reference mode is I. ref0 The diagnostic current in the second reference mode is I. ref0.3 The diagnostic current in the third reference mode is I. ref0.5 .

[0070] When I ref0.5 <I emc <I ref0.3 hour,

[0071]

[0072] The equivalent leakage orifice diameter ΦD is calculated and recorded internally by the ECU using a formula. emc This yields the historical record curve. Then, the ECU internally determines the diagnostic current I based on the currently measured value. emc The calculated equivalent leakage orifice diameter ΦD emc If the calculation is unreliable, proceed with the recalculation. The equivalent leakage orifice diameter ΦD is obtained through ECU analysis. emcBy analyzing changes in the evaporative emission system and combining them with historical data, it can be determined whether the system is deteriorating. If the equivalent leakage orifice diameter ΦD is obtained... emc There is an increasing trend, which will also be used to predict the rate of deterioration of the evaporative emission system's sealing performance and infer the expected time when the evaporative emission system will fail to meet regulatory requirements (i.e., the service limit time of the evaporative emission system, expressed in terms of vehicle mileage, see [link]). Figure 8 This is to remind users to perform preventative maintenance in advance, so as to avoid situations where excessive emissions due to leaks restrict the normal operation of the engine or the entire vehicle.

[0073] Please see Figure 9 This embodiment also provides a diagnostic method for a leak diagnosis module of an evaporative emission system for gasoline vehicles, including the following steps:

[0074] Step S10: Control the multi-phase analysis switching component 3 to switch between reference mode and diagnostic mode for different phases;

[0075] Step S20: Obtain the reference current in the reference mode and the diagnostic current in the diagnostic mode under different phases, and calculate the equivalent leakage orifice diameter of the current evaporative emission system.

[0076] Step S30: Predict the deterioration trend of the evaporative emission system's sealing performance based on changes in diagnostic current and equivalent leakage orifice diameter.

[0077] Step S10 includes the following steps:

[0078] Step S101: Control the switching motor 32 of the multi-phase analysis switching component 3 to rotate in the forward direction, driving the screw 33 of the multi-phase analysis switching component 3 to move axially upward from the initial position to reach multiple phases in sequence to complete a diagnostic cycle;

[0079] Step S102: Control the switching motor 32 to rotate in the opposite direction to drive the screw 33 back to the initial position.

[0080] Step S30 includes the following steps:

[0081] The service life of the evaporative emission system is inferred based on the predicted degradation trend of the equivalent leakage orifice diameter.

[0082] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0083] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the protection scope of the present invention. Therefore, the protection scope of this invention patent should be determined by the appended claims.

Claims

1. A leak diagnosis module for an evaporative emission system in a gasoline vehicle, characterized in that, include: The shell has a first cavity and a second cavity with a main hole inside. An air pump is installed inside the housing and its outlet is connected to the main hole. A drive motor and a current sensor are installed on the drive motor. The multi-phase analysis switching assembly includes a switching valve disposed in the first cavity and having multiple reference holes, and a switching motor disposed outside the second cavity for switching in conjunction with the switching valve. The leak diagnosis module is configured to switch between reference mode and diagnosis mode corresponding to different phases of multiple reference holes by controlling the on / off position of the multi-phase analysis switching component when the air pump is working, so as to perform quantitative leak analysis on the evaporation emission system and improve the accuracy of leak diagnosis. The multi-phase analysis switching component also includes: The screw has one end threadedly connected to the motor rotor of the switching motor, and the other end extends into the switching valve through the second cavity and the first cavity in sequence. A positioning bracket is disposed between the second cavity and the switching motor and sleeved on the screw. The contact portion between the positioning bracket and the screw is provided with a limiting groove for converting the circumferential rotation of the screw into axial movement. A sealing element, which is limited and sleeved on the screw and located in the first cavity, is used to seal the main hole or the space between the first cavity and the second cavity to change the gas flow path; The multi-phase analysis switching component also includes: A filter screen is disposed on the sealing element and sleeved on the screw; An inner sealing ring is disposed on the screw and located below the filter screen, and is used to cooperate with the sealing element to seal between the first cavity and the second cavity; A buffer spring is disposed between the positioning bracket and the seal; The switching valve has a communication hole that communicates with the outlet of the air pump, and the plurality of reference holes are spaced apart on the inner wall of the communication hole; The other end of the screw is provided with a connecting cylinder that extends into the connecting hole, and the side wall of the connecting cylinder is provided with mating holes corresponding to the multiple reference holes.

2. The leak diagnosis module for the evaporative emission system of a gasoline vehicle according to claim 1, characterized in that, Also includes: The control unit, connected to the current sensor, drive motor, and switching motor, is used to determine the reference current I under different phase reference modes acquired by the current sensor. ref And the diagnostic current I in diagnostic mode em c. Calculate the equivalent leakage orifice diameter ΦD of the current evaporative emission system. emc .

3. The leak diagnosis module for the evaporative emission system of a gasoline vehicle according to claim 2, characterized in that, The equivalent leakage orifice diameter ΦD of the current evaporative emission system emc In the diagnostic current I emc At the reference current I ref1 and I ref2 When the interval is between, it is obtained from the following formula: Wherein, ΦD1 is the actual diameter of a reference hole. K is the actual diameter of another reference hole whose diameter is larger than that of a first reference hole. s1 K is the flow coefficient of a reference orifice. s2 T is the flow coefficient of another reference orifice. C K is the temperature compensation coefficient. Pamb This is the air pressure compensation coefficient.

4. The leak diagnosis module for the evaporative emission system of a gasoline vehicle according to claim 1, characterized in that, The diameters of the plurality of reference holes are 0 mm, 0.3 mm, and 0.5 mm, respectively.

5. A diagnostic method for a leak diagnosis module of a gasoline vehicle evaporative emission system as described in any one of claims 1-4, characterized in that, Includes the following steps: The multi-phase analysis switching component is controlled to switch between reference modes and diagnostic modes for different phases; Obtain the reference current in the reference mode and the diagnostic current in the diagnostic mode under different phases, and calculate the equivalent leakage orifice diameter of the current evaporative emission system. The deterioration trend of evaporative emission system sealing is predicted based on changes in diagnostic current and equivalent leakage orifice diameter.

6. The diagnostic method for the leakage diagnosis module of the gasoline vehicle evaporative emission system according to claim 5, characterized in that, The control of the multi-phase analysis switching component to switch between reference modes and diagnostic modes for different phases includes the following steps: The switching motor of the multi-phase analysis switching component is controlled to rotate in the forward direction, which drives the screw of the multi-phase analysis switching component to move axially upward from the initial position to reach multiple phases in sequence to complete a diagnostic cycle; The switching motor is controlled to rotate in the opposite direction, driving the screw back to its initial position.

7. The diagnostic method for the leakage diagnosis module of the gasoline vehicle evaporative emission system according to claim 5, characterized in that, The method of predicting the degradation trend of the equivalent leakage orifice diameter based on changes in diagnostic current and equivalent leakage orifice diameter includes the following steps: The service life of the evaporative emission system is inferred based on the predicted degradation trend of the equivalent leakage orifice diameter.

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