CN111305979A

CN111305979A - System and method for detecting evaporative leakage in a fuel system in a vehicle

Info

Publication number: CN111305979A
Application number: CN201811516921.8A
Authority: CN
Inventors: 宋立廷; 李博; 马智勇; 丁伟文; 胡结兵
Original assignee: SAIC General Motors Corp Ltd; Pan Asia Technical Automotive Center Co Ltd
Current assignee: SAIC General Motors Corp Ltd; Pan Asia Technical Automotive Center Co Ltd
Priority date: 2018-12-12
Filing date: 2018-12-12
Publication date: 2020-06-19
Anticipated expiration: 2038-12-12
Also published as: CN111305979B

Abstract

The invention discloses a system and a method for detecting evaporative leakage of a fuel system in a vehicle. The system comprises: a canister disposed between a fuel tank and an engine of a vehicle; a shutoff valve provided in a first pipeline connected to the canister; a leak detection unit including a leak detection assembly and a first sensor for detecting an internal pressure of the fuel tank, the leak detection assembly being connected to the shutoff valve and the canister via a first pipeline, the leak detection assembly including: the vacuum pump comprises a box body with a cavity, a switch valve, a vacuum pump and a second sensor for detecting the internal pressure of the cavity, wherein the cavity is provided with a reference hole communicated with the outside, and the aperture of the reference hole changes along with the change of the pressure borne by the cavity; and the control unit is connected with the first sensor, the second sensor, the stop valve and the vacuum pump and used for controlling the operation of the first sensor, the second sensor, the stop valve and the vacuum pump, and the control unit stores the corresponding relation between the aperture of the reference hole and the pressure borne by the reference hole.

Description

System and method for detecting evaporative leakage in a fuel system in a vehicle

Technical Field

The present invention relates to the field of vehicle technology, and more particularly to a system and method for detecting evaporative leakage in a fuel system of a vehicle.

Background

In modern society, various vehicles have been widely used, and at the same time, problems such as safety, environmental protection, etc. are caused. As emissions regulations escalate from national five to national six standards, evaporative leak detection for the fuel system of a vehicle has increased. The current market uses evaporation leakage detection methods such as natural vacuum leakage detection, engine stop natural vacuum detection and the like. However, these existing evaporative leakage detection methods all require that after the engine is shut down for a period of time, the fuel system of the vehicle is judged to have a leakage problem according to the pressure and temperature change in the evaporative space of the fuel tank. For some vehicles such as hybrid vehicles, the engine of the vehicle does not run for a long time, so that effective temperature difference and pressure difference cannot be formed, the existing evaporative leakage detection method cannot be adopted for effective evaporative system leakage detection, and the detection frequency required by the regulations cannot be met.

Disclosure of Invention

Accordingly, the present invention is directed to a system and method for detecting evaporative leakage in a fuel system of a vehicle that substantially obviates or mitigates one or more of the above problems and other problems with the prior art.

According to a first aspect of the present invention, there is provided a system for detecting evaporative leakage in a fuel system of a vehicle, the system comprising:

a canister disposed between a fuel tank and an engine of the vehicle;

a shutoff valve provided in a first pipeline connected to the canister;

a leak detection unit including a leak detection assembly and a first sensor for detecting an internal pressure of the fuel tank, the leak detection assembly being connected to the shutoff valve and the canister via the first pipeline, the leak detection assembly including: the device comprises a box body with a cavity, a switch valve used for connecting or disconnecting the box body and the first pipeline, a vacuum pump used for sucking air in the cavity, and a second sensor used for detecting the internal pressure of the cavity, wherein the cavity is provided with a reference hole communicated with the outside, and the aperture of the reference hole is changed along with the change of the pressure borne by the cavity; and

and the control unit is connected with the first sensor, the second sensor, the stop valve and the vacuum pump and used for controlling the operation of the first sensor, the second sensor, the stop valve and the vacuum pump, and the control unit stores the corresponding relation between the aperture of the reference hole and the pressure borne by the reference hole.

In the system for detecting evaporative leakage of a fuel system in a vehicle according to the present invention, optionally, the leakage detecting unit further includes:

a filter connected to the vacuum pump for preventing intrusion of foreign materials in air sucked from the outside; and/or

A desorption control valve connected to the control unit and disposed in a second line for connecting the canister and the engine.

In the system for detecting evaporative leakage of a fuel system in a vehicle according to the present invention, optionally, the control unit is an engine control unit (ECM) of the vehicle.

In the system for detecting evaporative leakage of a fuel system in a vehicle according to the present invention, optionally, the tank body is provided with a metal plate mounted thereon in an interference fit manner, and the reference hole is provided on the metal plate; and/or the reference hole has a diameter of 0.5 mm.

In the system for detecting evaporative leakage of a fuel system in a vehicle according to the present invention, optionally, the first sensor and the second sensor are welded to the fuel tank and the tank, respectively, and/or the desorption control valve is a solenoid valve, and/or the vehicle comprises a hybrid vehicle.

Secondly, according to a second aspect of the present invention, there is provided a method for detecting evaporative leakage in a fuel system of a vehicle, said method comprising the steps of:

providing a system for detecting evaporative leakage in a fuel system in a vehicle as described in any one of the above;

immersing an oil tank of the vehicle with fuel oil for a preset time;

closing both the vacuum pump and the shut-off valve;

the first sensor is used to detect the tank internal pressure P1 and determine whether it is not less than the outside atmospheric pressure: if yes, opening the stop valve; and

the first sensor is used to detect the internal pressure P2 of the oil tank at this time, the second sensor is used to detect the internal pressure P3 of the cavity of the tank body, and then whether P2 and P3 are consistent or not is compared: if so, determining that no leakage exists, otherwise, determining that the leakage detection fails.

In the method for detecting evaporative leakage of a fuel system in a vehicle according to the present invention, optionally, if the detected tank internal pressure P1 is less than the outside atmospheric pressure, the following steps are performed:

A. starting the vacuum pump and closing the stop valve, operating the switch valve to communicate the tank body with the first pipeline, and then recording the aperture of the reference hole and obtaining the bearing pressure P4 corresponding to the aperture; and

B. operating the switch valve to disconnect the tank from the first pipeline, then recording the aperture of the reference hole at the moment and obtaining the bearing pressure P5 corresponding to the aperture, and judging whether P4 is smaller than P5: if so, the leak test is determined to be failed.

In the method for detecting evaporative leakage of a fuel system in a vehicle according to the present invention, optionally, the following step is further included after the step B:

C. opening the shutoff valve and then detecting the tank internal pressure P6 at that time using the first sensor; and

D. closing the stop valve, operating the switch valve to communicate between the tank and the first pipeline, then recording the aperture of the reference hole at the moment and obtaining the bearing pressure P7 corresponding to the aperture, and judging whether the difference between P7 and P4 exceeds a preset threshold value: if so, the leak test is determined to be failed.

In the method for detecting evaporative leakage of a fuel system in a vehicle according to the present invention, optionally, the following steps are further included after the step D:

E. turning off the vacuum pump, detecting the internal pressure P8 of the oil tank at the moment by using the first sensor, and judging whether P8 is greater than P7: if so, determining that a leak exists; otherwise, it is determined that no leakage exists.

In the method for detecting evaporative leakage of a fuel system in a vehicle according to the present invention, optionally, the following steps are further included before the step a:

detecting and judging whether the vacuum pump, the first sensor and the second sensor are in a normal working state or not; and/or

And detecting and judging whether the stop valve is blocked or not.

The features, characteristics, advantages, etc. of the various aspects according to the present invention will become apparent from the following detailed description, which is to be read in connection with the accompanying drawings. For example, by adopting the technical scheme of the invention, the evaporation leakage detection of the fuel system can be realized conveniently and reliably aiming at a hybrid vehicle and the like without running an engine, the detection precision can be ensured, the detection period can be reduced, and the hybrid vehicle and the like can meet the corresponding detection requirements of regulations.

Drawings

The present invention will be described in further detail below with reference to the drawings and examples, but it should be understood that the drawings are designed solely for purposes of illustration and are not necessarily drawn to scale, but rather are intended to conceptually illustrate the structural configurations described herein.

FIG. 1 is a schematic block diagram of an exemplary embodiment of a system for detecting evaporative leakage in a fuel system of a vehicle according to the present invention.

FIG. 2 is a schematic diagram of the components of an example leak detection assembly in the embodiment shown in FIG. 1.

FIG. 3 is a flow chart of an embodiment of a method for detecting evaporative leakage in a fuel system of a vehicle according to the present invention.

Detailed Description

First, it should be noted that the structural components, steps, features, advantages and the like of the system and method for detecting evaporative leakage of a fuel system in a vehicle of the present invention will be specifically described below by way of example, however, all the descriptions are for illustrative purposes only and should not be construed as forming any limitation on the present invention.

Furthermore, any single feature described or implicit in an embodiment or any single feature shown or implicit in the drawings or shown or implicit in the drawings may still allow any combination or permutation to continue between the features (or their equivalents) to achieve still further embodiments of the invention that may not be directly mentioned herein.

The composition and connection arrangement of an embodiment of a system for detecting evaporative leakage in a fuel system of a vehicle according to the present invention is schematically illustrated in fig. 1, and the basic composition of the leakage detection assembly thereof is further illustrated in a schematic manner in fig. 2, by which embodiment the present invention will be described in detail below.

In the given embodiment, the system may include a first sensor 5, a desorption control valve 6, a canister 7, a shut-off valve 8, a leak detection assembly 9, a control unit 10, and a filter 11. The first sensor 5 is a pressure sensor, and may be attached to the fuel tank 3 of the vehicle by welding or the like, for example, to detect the internal pressure of the fuel tank 3. As shown in fig. 1, the fuel tank 3 may be made of a material such as a high-pressure resistant plastic, and it may be provided with a filler pipe 2 for supplying fuel thereto, and a filler cap 1 may be further provided for the filler pipe 2. Further, an oil pump 4 may be provided for the oil tank 3 to pump fuel toward an engine or the like of a vehicle (e.g., a hybrid vehicle or the like).

The canister 7 is disposed between the fuel tank 3 and the engine M to adsorb fuel vapor so as to prevent the fuel vapor from escaping into the atmosphere after the engine stops operating. In an alternative case, the desorption control valve 6 may be arranged in a line 13 for connecting the canister 7 and the engine M and connected to the control unit 10 in order to control the flow of fuel vapour in the line 13 according to the application requirements. By way of illustration, the desorption control valve 6 may be implemented using any suitable valve of the type of a solenoid valve or the like.

A shut-off valve 8 is provided in a line 12 connecting the canister 7 and the leak detection assembly 9, which can be connected to a control unit 10 for controlling the flow of fuel vapour in the line 12 as required by the application, as will be described in more detail hereinafter.

For the leak detection assembly 9, it may comprise a plurality of components and be connected to the shut-off valve 8 and the canister 7 via a line 12. By way of example, as shown in fig. 2, the leak detection assembly 9 may include a tank 90, a vacuum pump 91, a second sensor 92, and an on-off valve 94. The box 90 is provided with a cavity, and the cavity may have a reference hole 93 which is communicated with the outside, the aperture of the reference hole 93 may be changed along with the change of the pressure borne by the reference hole 93, that is, the corresponding relation between the aperture of the reference hole 93 and the borne pressure may be calibrated, so that when the current aperture size of the reference hole 93 is measured, the pressure value borne by the reference hole 93 at that time may be obtained accordingly.

In the alternative, the reference hole 93 may be configured to have a diameter dimension of 0.5mm, although it is also permissible to configure it to have any other suitable dimension. In addition, the metal sheet with the reference hole 93 may be mounted on the box 90 by an interference fit, so that the cavity of the box 90 has the reference hole 93 in fluid communication with the outside.

The on-off valve 94 of the leak detection assembly 9 is provided to maintain a communication state or a disconnection state between the tank 90 and the pipeline 12, and may be implemented by a solenoid valve or the like. In addition, a vacuum pump 91 is provided for pumping air within the cavity of the tank 90 so as to create a vacuum. The second sensor 92 is used for detecting the pressure inside the chamber of the box 90, and can be attached to the box 90 by welding or the like.

Alternatively, as shown in fig. 1, a filter 11 may be provided in the leak detection module 9, and the filter 11 may be connected to a vacuum pump 91 to prevent the undesirable intrusion of foreign substances in the sucked air a into the system.

The control unit 10 is a control part of the system and may be connected to the first sensor 5, the second sensor 92, the shut-off valve 8, the vacuum pump 91 and other possible components or units in order to control their operation according to the application needs. As described above, the corresponding relationship between the aperture of the reference hole 93 and the pressure applied thereto may be stored in the control unit 10, so that the pressure value applied to the reference hole 93 at this time may be obtained according to the measured current aperture size of the reference hole 93 very conveniently and quickly.

In an alternative scenario, the control unit 10 may directly employ an engine control unit (ECM) on the vehicle. Of course, other existing controllers, control modules or control units on the vehicle may be employed as the control unit 10 in some embodiments without departing from the spirit of the invention; alternatively, in some embodiments, the control unit 10 may also be implemented using a separate controller, control module or control unit. By adopting a plurality of modes, various possible practical application requirements can be better met.

By providing a system according to the present invention such as that exemplified above, it can be used to detect a fuel system evaporative leak condition in a vehicle without the need to start an engine on the vehicle, such as a hybrid vehicle, to run. According to the technical scheme, the invention further provides a method for detecting the evaporation leakage of the fuel system in the vehicle. By way of illustration, the embodiments of fig. 1 and 2 may be combined, and the method may include the following steps:

first, a system designed according to the present invention for detecting evaporative leakage in a fuel system in a vehicle is provided.

Then, the fuel tank 3 of the vehicle (such as a hybrid vehicle or the like) is submerged with fuel for a preset period of time. With regard to the above-mentioned preset time period, this can be flexibly set according to the specific situation of the fuel tank 3, the fuel performance, etc., and it can be set to 5 hours, etc., for example. In practical applications, the determination may be made by detecting whether the tank 3 already has the pressure or vacuum necessary for detection, for example, by the first sensor 5 or the like.

In the detection process, the vacuum pump 91 and the stop valve 8 in the system are closed.

Next, the internal pressure P1 of the tank 3 can be detected by the first sensor 5, and then P1 is compared with the external atmospheric pressure P: if P1 is not less than P, it may indicate that a sufficient vacuum has been established inside the tank 3 at this time, and there may be no evaporative leakage problem.

However, in order to prevent false detections from occurring due to the possible failure of the first sensor 5 to function properly, the shut-off valve 8 may be opened to allow fuel vapour to remain in fluid communication from the tank 8 to the tank 90, while still placing the vacuum pump 91 in a closed condition; then, the internal pressure P2 of the tank 3 at that time is detected again using the first sensor 5, and the cavity internal pressure P3 of the tank 90 is detected using the second sensor 92, and then it is compared whether both P2 and P3 coincide: if the pressure of the first sensor and the pressure of the second sensor are consistent, the problem of evaporative leakage can be judged to be absent, and meanwhile, the first sensor 5 can work normally, so that the leakage detection result is effective; if the pressures of P2 and P3 are not consistent, it is determined that the leak test is failed, that is, the first sensor 5 may have a fault or abnormality, and the leak test belongs to a failure situation, and a fault code may be formed and reported to a component or unit, such as the control unit 10, for analysis and judgment.

Through the above steps, a quick and reliable leak test can be completed, which is also shown in the left-hand flow of the exemplary method shown in fig. 3. Further, various optional processing steps are shown in the right-hand flow of FIG. 3, as will be described in more detail below.

For example, as shown in fig. 3, the following steps may be implemented, either individually or in combination:

first, a physical environment detection operation and/or a ventilation performance detection operation may be performed. For the physical environment detection operation, it is detected and judged whether, for example, the vacuum pump 91, the first sensor 5, and the second sensor 92 are all in the normal operation state, which can be detected and judged by the respective operation performance characteristics of these components. As for the operation of the check of the ventilation performance, it is detected and judged whether or not there is a jam of the shut valve 8, which can be judged by, for example, turning off the vacuum pump 91, opening the shut valve 8, and keeping the tank 90 in communication with the pipe 12 (i.e., in a ventilation state) by operating the on-off valve 94, and then in this working case, judging whether or not there is a jam of the shut valve 8.

Further, in an alternative case, when it is found that the internal pressure P1 of the oil tank 3 detected by the first sensor 5 is lower than the external atmospheric pressure P, the vacuum pump 91 may be turned on and the shut-off valve 8 may be closed, then the on-off valve 94 may be operated to keep the tank 90 in communication with the pipeline 12, the vacuum pump 91 may be operated to perform vacuum pumping, which may change the internal pressure of the cavity of the tank 90, and may further change the aperture of the reference hole 93 accordingly, and then the aperture of the reference hole 93 at that time may be recorded, and the corresponding received pressure P4 may be obtained, for example, by the control unit 10, according to the correspondence between the aperture of the reference hole 93 stored therein and the received pressure thereof, that is, P4 is the pressure value obtained when the first reference aperture detection is performed.

The on-off valve 94 is then operated to disconnect (i.e., pump) the tank 90 from the line 12, and the diameter of the reference hole 93 at that time is then recorded, and the corresponding bearing pressure P5 can be obtained in the same manner as described above. Then, the obtained P4 and P5 are both compared, and if P4 is smaller than P5, it is determined that the leak test is failed; otherwise, the system can be considered to be in a normal state, and the steam leakage problem does not exist.

In addition, as shown in fig. 3, in an optional case, the following steps may also be continuously performed after the above steps:

the shutoff valve 8 is opened and is kept in the pumping state by operating the on-off valve 94, and then the first sensor 5 is used to detect that the internal pressure P6 of the fuel tank 3 at this time is obtained.

Next, the shut valve 8 is closed again, and the on-off valve 94 is operated to communicate between the tank 90 and the pipe 12, thereby switching to the air-vent state, and then the hole diameter of the reference hole 93 at that time is recorded and the corresponding pressure P7 is obtained, that is, P7 is the pressure value obtained when the second reference hole diameter detection is performed.

Subsequently, the obtained P7 can be compared with the above detected P4, and if the difference between them exceeds a preset threshold (which can be flexibly set according to specific application conditions), it can be determined that the leakage detection is failed; otherwise, the system can be considered to be in a normal state, and the steam leakage problem does not exist.

Referring to fig. 3, the following optional steps may be further performed, that is:

the vacuum pump 91 may be turned off and still maintained in the pumping state by operating the switching valve 94, and then the pressure P8 inside the oil tank 3 at that time is detected using the first sensor 5, and then P8 is compared with the above detected P7. If P8 is greater than P7, this means that there is a greater amount of leakage than the diameter of the reference hole 93, and it can be determined that the system has leaked; otherwise, the system can be considered to be in a normal state, and the steam leakage problem does not exist.

As described above, the system and method for detecting evaporative leakage of a fuel system in a vehicle according to the present invention can achieve technical advantages over the prior art, overcome the disadvantages and shortcomings of the prior art including those described above, and particularly, can achieve evaporative leakage detection of a fuel system for a vehicle such as a hybrid vehicle without starting a vehicle engine, and can ensure detection accuracy and reduce detection period, which will help to promote various new energy vehicles to meet corresponding detection requirements stipulated by regulations.

The system and method for detecting evaporative leakage in a fuel system of a vehicle according to the present invention has been described in detail by way of example only, and these examples are provided merely for the purpose of illustrating the principles of the invention and its embodiments, rather than for the purpose of limiting the invention, and it is contemplated that modifications and improvements will readily occur to those skilled in the art without departing from the spirit and scope of the invention. Accordingly, all equivalents are intended to be included within the scope of this invention and defined in the claims which follow.

Claims

1. A system for detecting evaporative leakage in a fuel system of a vehicle, the system comprising:

a canister disposed between a fuel tank and an engine of the vehicle;

a shutoff valve provided in a first pipeline connected to the canister;

2. The system for detecting evaporative leakage of a fuel system in a vehicle of claim 1, wherein the leakage detection unit further comprises:

3. The system for detecting evaporative leakage of a fuel system in a vehicle of claim 1, wherein the control unit is an engine control unit (ECM) of the vehicle.

4. The system for detecting evaporative leakage of a fuel system in a vehicle of claim 1, wherein the tank is provided with a metal plate mounted thereon in an interference fit, the reference hole being provided on the metal plate; and/or the reference hole has a diameter of 0.5 mm.

5. The system for detecting fuel system evaporative leakage in a vehicle according to any of claims 1-4, wherein the first and second sensors are welded to the fuel tank and the tank, respectively, and/or the desorption control valve is a solenoid valve, and/or the vehicle comprises a hybrid vehicle.

6. A method for detecting evaporative leakage in a fuel system of a vehicle, the method comprising the steps of:

providing a system for detecting evaporative leakage in a fuel system in a vehicle as claimed in any one of claims 1 to 5;

immersing an oil tank of the vehicle with fuel oil for a preset time;

closing both the vacuum pump and the shut-off valve;

7. The method for detecting evaporative leakage of a fuel system in a vehicle according to claim 6, wherein if the detected tank internal pressure P1 is less than the outside atmospheric pressure, the following steps are performed:

8. The method for detecting a fuel system evaporative leak in a vehicle as set forth in claim 7, further comprising, after said step B, the steps of:

9. The method for detecting a fuel system evaporative leak in a vehicle as set forth in claim 8, further comprising, after said step D, the steps of:

10. The method for detecting a fuel system evaporative leak in a vehicle according to any one of claims 6 to 9, further comprising, before said step a, the steps of:

And detecting and judging whether the stop valve is blocked or not.