A method for monitoring leakage of a fuel evaporation system of a hybrid vehicle

Abstract

The application discloses a kind of hybrid vehicle fuel evaporation system leakage monitoring method, comprising: judging whether to meet diagnostic condition;If meet, then close carbon canister solenoid valve, open fuel tank isolation valve, and whether there is fuel tank pressure rationality fault according to fuel tank pressure;If not, then pump up, and monitor the signal voltage of pump, to judge whether there is pump drive circuit fault according to the signal voltage of pump;If not, then according to the duration that fuel tank pressure exceeds corresponding preset calibration threshold, judge whether fuel evaporation system exists leakage.The hybrid vehicle fuel evaporation system leakage monitoring method of the application uses conventional electric pump, diagnoses when pump works, simultaneously monitors fuel tank pressure change, judges whether there is leakage according to calibration threshold, without DMTL component reference pump current measurement, solenoid valve switching and the like control, simplifies ECU control model, and also saves design cost on hardware.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of automobile fuel equipment control, and particularly relates to a leakage monitoring method for a fuel evaporation system of a hybrid vehicle. BACKGROUND

[0002] Plug-in hybrid vehicles still carry engines and need to meet the fuel evaporation leakage monitoring requirements in the national sixth emission regulations. Since the engine operating conditions of hybrid power have great uncertainty, the evaporation leakage diagnosis generally adopts positive pressure diagnosis, which can be completed during the running stage after the vehicle is stopped.

[0003] At present, the general response scheme of the industry for the leakage monitoring requirements of plug-in hybrid vehicles is the positive pressure diagnosis scheme of the fuel evaporation leakage diagnosis module (DMTL): after the vehicle is stopped, the pressure relief valve is opened for pressure relief, and then the DMTL air pump is used to actively pump air into the fuel tank, and whether there is leakage is judged according to the pump current change. The disadvantage of this scheme is that the DMTL component is powerful, which can not only serve as an actuator to perform the air pumping function, but also can serve as a sensor to monitor the pump current, but it is developed based on the traditional fuel tank without a pressure sensor. Under the background of the use of high-pressure fuel tanks in hybrid vehicles, there is a problem of waste in cost that the pressure sensor monitoring function in the high-pressure fuel tank cannot be fully utilized.

[0004] Therefore, there is an urgent need for a leakage monitoring method for a fuel evaporation system of a hybrid vehicle. SUMMARY

[0005] The purpose of the present application is to provide a leakage monitoring method for a fuel evaporation system of a hybrid vehicle to solve the problems in the prior art, which can monitor the tank pressure signal, reduce the component structure of the air pump, simplify the control model of the ECU, and reduce the product cost.

[0006] The present application provides a leakage monitoring method for a fuel evaporation system of a hybrid vehicle, which comprises the following steps:

[0007] determining whether the fuel leakage diagnosis condition is met;

[0008] if the condition is met, closing the carbon canister electromagnetic valve, opening the fuel tank isolation valve, and determining whether there is a fuel tank pressure rationality fault according to the fuel tank pressure;

[0009] if not, the air pump works, and the signal voltage of the air pump is monitored to determine whether there is a fault in the air pump driving circuit according to the signal voltage of the air pump;

[0010] if not, determining whether the fuel evaporation system has leakage according to the duration that the fuel tank pressure exceeds the corresponding preset threshold value.

[0011] The method for monitoring fuel evaporation system leakage of a hybrid vehicle as described above, preferably, the judging whether the fuel leakage diagnosis condition is satisfied specifically comprises:

[0012] judging whether the starting water temperature is within a corresponding calibrated threshold range;

[0013] judging whether the ambient temperature is within a corresponding calibrated threshold range;

[0014] judging whether the difference between the starting water temperature and the ambient temperature is less than a corresponding calibrated threshold value;

[0015] judging whether the engine running time is greater than a corresponding calibrated threshold value;

[0016] judging whether the vehicle is in a post-power-off running state;

[0017] if all the conditions are satisfied, the fuel leakage diagnosis condition is satisfied.

[0018] The method for monitoring fuel evaporation system leakage of a hybrid vehicle as described above, preferably, in the case where the fuel leakage diagnosis condition is satisfied, the charcoal canister electromagnetic valve is closed, the tank isolation valve is opened, and whether there is a tank pressure rationality fault is judged according to the tank pressure, specifically comprising:

[0019] closing the charcoal canister electromagnetic valve and opening the tank isolation valve;

[0020] after waiting for the pressure relief to be completed, obtaining the tank pressure signal through the tank pressure sensor;

[0021] monitoring the deviation between the tank pressure obtained according to the tank pressure signal fed back by the tank pressure sensor and the ambient pressure obtained through the ambient pressure signal obtained by the ambient pressure sensor built in the electronic control unit;

[0022] if the deviation exceeds a corresponding preset calibrated threshold range, a tank pressure rationality fault is reported, and the diagnosis is exited;

[0023] if the deviation is within a corresponding preset calibrated threshold range, the next step is entered.

[0024] The method for monitoring fuel evaporation system leakage of a hybrid vehicle as described above, preferably, in the case where there is no tank pressure rationality fault, the air pump is operated, and the signal voltage of the air pump is monitored to judge whether there is an air pump driving circuit fault according to the signal voltage of the air pump, specifically comprising:

[0025] the electronic control unit controls the air pump to operate;

[0026] during the operation of the air pump, the signal voltage of the air pump is monitored by the electronic control unit;

[0027] The electrical control unit judges whether the air pump driving circuit is faulty according to the voltage signal fed back by the air pump.

[0028] If the air pump driving circuit is faulty, the air pump driving circuit fault is reported, and the diagnosis is exited.

[0029] If the air pump driving circuit is not faulty, the next step is entered.

[0030] The method for monitoring the leakage of the fuel evaporation system of the hybrid vehicle type as described above, wherein preferably, the signal voltage of the air pump comprises at least one of voltage, flow and pressure.

[0031] The method for monitoring the leakage of the fuel evaporation system of the hybrid vehicle type as described above, wherein preferably, in the case where the air pump driving circuit is not faulty, the judgment of whether the fuel evaporation system is leaked according to the duration that the tank pressure exceeds the corresponding preset calibration threshold value comprises:

[0032] The pressure signal is collected by the tank pressure sensor.

[0033] The tank pressure information fed back by the tank pressure sensor is acquired to judge whether the fuel evaporation system is leaked.

[0034] If the tank pressure exceeds the corresponding preset calibration threshold value, and the duration that the tank pressure exceeds the corresponding preset calibration threshold value exceeds the corresponding time threshold value T1, it is judged that the fuel evaporation system is not leaked.

[0035] If the tank pressure is less than the corresponding preset calibration threshold value within the diagnosis time T2, it is judged that the fuel evaporation system is leaked, wherein the diagnosis time T2 is greater than the time threshold value T1.

[0036] The present application provides a method for monitoring the leakage of the fuel evaporation system of the hybrid vehicle type, which uses a conventional electric air pump as an actuator only, controls the air pump to work during diagnosis, monitors the change of the tank pressure at the same time, judges whether there is leakage according to the calibration threshold value after the tank pressure is stabilized, fully utilizes the characteristics of the tank pressure sensor, simplifies the structure of the air pump for positive pressure diagnosis of the hybrid vehicle type, reduces the component structure of the air pump, cancels the reference pump current measurement, electromagnetic valve switching and other controls of the DMTL component, simplifies the ECU control model, saves the design cost on hardware, and increases the speed and reliability of system diagnosis through a simpler diagnosis model. BRIEF DESCRIPTION OF DRAWINGS

[0037] In order to make the purpose, technical scheme and advantages of the present application more clear, the present application will be further described below with reference to the drawings, wherein:

[0038] Figure 1A fuel evaporation system structure diagram of the hybrid vehicle fuel evaporation system leakage monitoring method embodiment provided by the present application;

[0039] Figure 2 A flowchart of the hybrid vehicle fuel evaporation system leakage monitoring method embodiment provided by the present application;

[0040] Figure 3 A logic diagram of the hybrid vehicle fuel evaporation system leakage monitoring method embodiment provided by the present application. DETAILED DESCRIPTION

[0041] Various exemplary embodiments of the present disclosure will now be described in detail with reference to the accompanying drawings. The description of the exemplary embodiments is merely illustrative in nature and is in no way intended to limit the disclosure, its application or uses. The present disclosure can be implemented in numerous different forms, not limited to the embodiments described herein. These embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the present disclosure to those skilled in the art. It should be noted that the relative arrangement of the components and steps set forth in these embodiments, the components of the materials, numerical expressions, and numerical values are to be interpreted as merely exemplary, rather than as a limitation unless otherwise specifically stated.

[0042] The "first", "second", and similar words used in the present disclosure do not represent any order, number or importance, but are only used to distinguish different parts. "Include" or "contain" and similar words mean that the elements before the word cover the elements listed after the word, and do not exclude the possibility of also covering other elements. "Up", "down" and the like are only used to represent the relative positional relationship, and when the absolute position of the described object changes, the relative positional relationship may also change accordingly.

[0043] In the present disclosure, when it is described that a specific component is located between a first component and a second component, there can be an intervening component between the specific component and the first component or the second component, or there can be no intervening component. When it is described that a specific component is connected to other components, the specific component can be directly connected to the other components without an intervening component, or it can not be directly connected to the other components with an intervening component.

[0044] All terms used in the present disclosure, including technical terms or scientific terms, have the same meaning as understood by a person of ordinary skill in the art to which the present disclosure belongs, unless otherwise specifically defined. It should also be understood that terms defined in a general dictionary should be interpreted in a manner consistent with their meanings in the context of the relevant technology, and should not be interpreted in an idealized or excessively formalized sense, unless specifically defined herein.

[0045] Techniques, methods, and apparatus known to those of ordinary skill in the relevant art(s) can not be discussed in any detail since they can be readily understood from the disclosure and are considered part of the present description.

[0046] The fuel evaporation system structure of the present application is shown in Figure 1 Compared with the fuel evaporation diagnosis system of a general plug-in hybrid vehicle, the system structure of the present application has little change, mainly in the different diagnosis process control.

[0047] As shown in Figure 2 and Figure 3 The fuel evaporation system leakage monitoring method for a hybrid vehicle provided by the present embodiment specifically includes the following steps in actual execution process:

[0048] Step S1, judge whether the fuel leakage diagnosis condition is met.

[0049] In an embodiment of the fuel evaporation system leakage monitoring method for a hybrid vehicle of the present application, the step S1 specifically can include:

[0050] Step S11, judge whether the starting water temperature is within the corresponding calibrated threshold range.

[0051] Step S12, judge whether the ambient temperature is within the corresponding calibrated threshold range.

[0052] Step S13, judge whether the difference between the starting water temperature and the ambient temperature is less than the corresponding calibrated threshold.

[0053] Step S14, judge whether the engine running time is greater than the corresponding calibrated threshold.

[0054] Step S15, judge whether the vehicle is in the post-power-off running state.

[0055] Step S16, if all the conditions are met, the fuel leakage diagnosis condition is met.

[0056] It should be noted that the calibrated thresholds corresponding to the starting water temperature, the ambient temperature, the difference between the starting water temperature and the ambient temperature, and the engine running time are not specifically limited.

[0057] Step S2, if met, close the carbon canister electromagnetic valve, open the tank isolation valve, and judge whether there is a tank pressure rationality fault according to the tank pressure.

[0058] In an embodiment of the fuel evaporation system leakage monitoring method for a hybrid vehicle of the present application, the step S2 specifically can include:

[0059] Step S21, close the carbon canister electromagnetic valve and open the tank isolation valve.

[0060] Step S22: After the pressure relief is completed, obtain the oil tank pressure signal through the oil tank pressure sensor.

[0061] Step S23: Monitor the deviation between the fuel tank pressure and the ambient pressure obtained by the ambient pressure signal obtained by the ambient pressure sensor built into the electronic control unit, based on the fuel tank pressure signal fed back by the fuel tank pressure sensor.

[0062] Step S24: If the deviation exceeds the corresponding preset calibration threshold range, report a tank pressure reasonableness fault and exit the diagnostic process.

[0063] Step S25: If the deviation is within the corresponding preset calibration threshold range, proceed to the next step (i.e., proceed to step S3).

[0064] Step S3: If not, the air pump will operate and the signal voltage of the air pump will be monitored to determine whether there is a fault in the air pump drive circuit.

[0065] In one embodiment of the hybrid vehicle fuel evaporation system leakage monitoring method of the present invention, step S3 may specifically include:

[0066] Step S31: The electronic control unit (ECU) controls the air pump to work.

[0067] Step S32: During the operation of the air pump, the signal voltage of the air pump is monitored by the electronic control unit.

[0068] The signal voltage of the air pump includes at least one of voltage, flow rate, and pressure. It should be noted that this invention does not specifically limit the type and value of the signal voltage of the air pump. In specific implementations, the specific ranges of voltage, flow rate, and pressure need to be adapted according to the size of the fuel tank; this invention does not specifically limit this.

[0069] Step S33: The electrical control unit determines whether there is a fault in the air pump drive circuit based on the voltage signal fed back by the air pump.

[0070] Step S34: If there is a fault in the air pump drive circuit, report the air pump drive circuit fault and exit the diagnostic process.

[0071] Step S35: If there is no fault in the air pump drive circuit, proceed to the next step (i.e., proceed to step S4).

[0072] Step S4: If not, determine whether there is a leak in the fuel evaporation system based on the duration for which the fuel tank pressure exceeds the corresponding preset calibration threshold.

[0073] In one embodiment of the hybrid vehicle fuel evaporation system leakage monitoring method of the present invention, step S4 may specifically include:

[0074] Step S41, collect the pressure signal through the oil tank pressure sensor.

[0075] Step S42, obtain the oil tank pressure information fed back by the oil tank pressure sensor, and determine whether the fuel evaporation system has a leakage.

[0076] Step S43, if the oil tank pressure exceeds the corresponding preset calibration threshold, and the duration of exceeding the corresponding preset calibration threshold exceeds the corresponding time threshold T1, it is determined that the fuel evaporation system has no leakage.

[0077] Step S44, if the oil tank pressure is less than the corresponding preset calibration threshold within the diagnosis time T2, it is determined that the fuel evaporation system has a leakage, wherein the diagnosis time T2 is greater than the time threshold T1.

[0078] Specifically, for a 1mm leakage fault, the diagnosis is ended.

[0079] The hybrid vehicle fuel evaporation system leakage monitoring method provided by the embodiment of the application uses a conventional electric air pump as an actuator only, controls the air pump to work during diagnosis, monitors the change of the oil tank pressure at the same time, judges whether there is a leakage according to the calibration threshold after the oil tank pressure is stabilized, fully utilizes the characteristics of the oil tank pressure sensor, simplifies the positive pressure diagnosis air pump structure of the hybrid vehicle, reduces the component structure of the air pump, cancels the reference pump current measurement, electromagnetic valve switching and other controls of the DMTL component, simplifies the ECU control model, saves the design cost on the hardware, and increases the speed and reliability of system diagnosis through a simpler diagnosis model.

[0080] So far, the embodiments of the present disclosure have been described in detail. In order to avoid obscuring the concept of the present disclosure, some details known in the art are not described. Those skilled in the art can fully understand how to implement the technical solutions disclosed herein according to the above description.

[0081] Although some specific embodiments of the present disclosure have been described in detail through examples, those skilled in the art should understand that the above examples are only for illustration, and are not intended to limit the scope of the present disclosure. Those skilled in the art should understand that the above embodiments can be modified or some technical features can be replaced equivalently without departing from the scope and spirit of the present disclosure. The scope of the present disclosure is defined by the appended claims.

Claims

1. A method for monitoring leakage in the fuel evaporation system of a hybrid vehicle, characterized in that, include: Determine whether the diagnostic criteria for a fuel leak are met; If the conditions are met, close the charcoal canister solenoid valve, open the fuel tank isolation valve, and determine whether there is a fuel tank pressure malfunction based on the fuel tank pressure. If not, the air pump will operate and monitor the signal voltage of the air pump to determine whether there is a fault in the air pump drive circuit. If no leak is found, the presence of a leak in the fuel evaporation system is determined based on the duration for which the fuel tank pressure exceeds the corresponding preset calibration threshold. In the absence of any fuel tank pressure malfunction, the air pump operates and its signal voltage is monitored to determine whether there is a fault in the air pump drive circuit. Specifically, this includes: The electronic control unit controls the operation of the air pump; During the operation of the air pump, the signal voltage of the air pump is monitored by the electronic control unit; The electrical control unit determines whether there is a fault in the air pump drive circuit based on the voltage signal fed back by the air pump. If a fault is found in the air pump drive circuit, an air pump drive circuit fault will be reported, and the diagnostic process will exit. If there is no fault in the air pump drive circuit, proceed to the next step.

2. The method for monitoring fuel evaporation system leakage in hybrid vehicles according to claim 1, characterized in that, The determination of whether the fuel leak diagnosis conditions are met specifically includes: Determine whether the starting water temperature is within the corresponding calibrated threshold range; Determine whether the ambient temperature is within the corresponding calibration threshold range; Determine whether the difference between the starting water temperature and the ambient temperature is less than the corresponding calibration threshold; Determine whether the engine running time exceeds the corresponding calibration threshold; Determine if the vehicle is running after being powered off; If all conditions are met, then the criteria for diagnosing a fuel leak are met.

3. The method for monitoring fuel evaporation system leakage in hybrid vehicles according to claim 1, characterized in that, Under the condition of meeting the fuel leak diagnosis criteria, the steps of closing the charcoal canister solenoid valve, opening the fuel tank isolation valve, and determining whether there is a fuel tank pressure malfunction based on the fuel tank pressure specifically include: Close the charcoal canister solenoid valve and open the fuel tank isolation valve; After the pressure relief is complete, the oil tank pressure signal is obtained through the oil tank pressure sensor; The deviation between the fuel tank pressure and the ambient pressure obtained by the ambient pressure sensor built into the electronic control unit is monitored based on the fuel tank pressure signal fed back by the fuel tank pressure sensor. If the deviation exceeds the corresponding preset calibration threshold range, an oil tank pressure reasonableness fault will be reported, and the diagnostic process will be exited. If the deviation is within the corresponding preset calibration threshold range, proceed to the next step.

4. The method for monitoring fuel evaporation system leakage in hybrid vehicles according to claim 1, characterized in that, The signal voltage of the air pump includes at least one of voltage, flow rate, and pressure.

5. The method for monitoring fuel evaporation system leakage in hybrid vehicles according to claim 1, characterized in that, In the absence of a fault in the air pump drive circuit, the step of determining whether there is a leak in the fuel evaporation system based on the duration for which the fuel tank pressure exceeds a corresponding preset calibration threshold specifically includes: Pressure signals are acquired via a fuel tank pressure sensor; Obtain the fuel tank pressure information fed back by the fuel tank pressure sensor to determine whether there is a leak in the fuel evaporation system; If the fuel tank pressure exceeds the corresponding preset calibration threshold, and the duration of exceeding the corresponding preset calibration threshold exceeds the corresponding time threshold T1, then it is determined that there is no leakage in the fuel evaporation system. If the fuel tank pressure remains below the corresponding preset calibration threshold for a period of time T2, it is determined that there is a leak in the fuel evaporation system, where the diagnosis time T2 is greater than the time threshold T1.

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