A pipeline blockage identification-based oil tank leakage diagnosis false-alarm-preventing method and system

Abstract

The present application relates to a kind of oil tank leakage diagnosis false alarm prevention method and system based on pipeline blockage identification, false alarm prevention method includes: when starting oil tank leakage diagnosis, real-time identification whether the evaporation pipeline of vehicle oil tank is in the state of blockage, when the evaporation pipeline of vehicle oil tank is in the state of blockage, pause oil tank leakage diagnosis.In the present application, by introducing pipeline blockage identification in the vacuum stage of oil tank, oil tank leakage diagnosis can be prohibited when the evaporation pipeline is blocked, so as to avoid false alarm leakage fault caused by rapid vacuum degree of oil tank after the evaporation pipeline is blocked.

Description

Technical Field

[0001] This invention belongs to the field of fuel tank leak diagnosis technology, and relates to a fuel tank leak diagnosis method and system based on pipeline blockage identification to prevent false judgments. Background Technology

[0002] When a vehicle's fuel tank has a high fuel level, it is prone to sloshing. In this situation, fuel may enter the evaporator lines and cause blockage. Similarly, when the vehicle is parked uphill or downhill, the tilted fuel level can also cause blockage in the evaporator lines. When entering leak diagnostics at idle, the blockage creates two separate spaces for the fuel tank and carbon canister. During the vacuum building phase, the space around the carbon canister and lines is smaller than before the blockage, causing the vacuum to build up abnormally quickly, leading to false leak alarms. Summary of the Invention

[0003] To address the shortcomings of the prior art, the technical problem to be solved by the present invention is to provide a method and system for preventing false alarms in fuel tank leakage diagnosis based on pipeline blockage identification.

[0004] To achieve the above objectives, the present invention provides the following technical solution:

[0005] A method for preventing false positives in fuel tank leak diagnosis based on pipeline blockage identification involves the following steps when initiating fuel tank leak diagnosis:

[0006] S100: Real-time identification of whether the evaporator pipe of the vehicle's fuel tank is blocked. When the evaporator pipe of the vehicle's fuel tank is blocked, execute step S200.

[0007] S200, Suspend fuel tank leak diagnosis.

[0008] Furthermore, methods for identifying whether the evaporator line of a vehicle's fuel tank is blocked include the following steps:

[0009] Evacuate the fuel tank and its connecting pipelines;

[0010] Calculate the maximum slope of the pressure change in the oil tank during the vacuuming process of the oil tank and its connecting pipelines;

[0011] When the maximum slope of the change in fuel tank pressure exceeds the preset slope threshold, the evaporator pipe of the vehicle's fuel tank is determined to be blocked.

[0012] Furthermore, methods for identifying whether the evaporator line of a vehicle's fuel tank is blocked include the following steps:

[0013] Evacuate the fuel tank and its connecting pipelines;

[0014] Calculate the maximum rate of change of the pressure slope in the oil tank during the vacuuming process of the oil tank and its connecting pipelines.

[0015] When the maximum rate of change of the fuel tank pressure slope exceeds the preset rate of change threshold, the evaporator pipe of the vehicle's fuel tank is determined to be blocked.

[0016] Furthermore, methods for identifying whether the evaporator line of a vehicle's fuel tank is blocked include the following steps:

[0017] Evacuate the fuel tank and its connecting pipelines;

[0018] When the air pressure in the oil tank is less than the preset air pressure threshold, the vacuuming of the oil tank and its connecting pipelines is stopped, and the desorption flow rate integral during the vacuuming period is calculated.

[0019] When the desorption flow integral is less than the preset flow threshold, the evaporator pipe of the vehicle's fuel tank is determined to be blocked.

[0020] Furthermore, methods for identifying whether the evaporator line of a vehicle's fuel tank is blocked include the following steps:

[0021] S101. Vacuum the fuel tank and its connecting pipelines.

[0022] S102. Calculate the maximum slope of the change in tank pressure; if the maximum slope of the change in tank pressure is greater than the preset slope threshold, proceed to step S107; otherwise, proceed to step S103.

[0023] S103. Calculate the maximum rate of change of the tank pressure slope; if the maximum rate of change of the tank pressure slope is greater than the preset rate of change threshold, proceed to step S107; otherwise, proceed to step S104.

[0024] S104. Determine whether the air pressure in the fuel tank is less than the preset air pressure threshold. If the air pressure in the fuel tank is less than the preset air pressure threshold, proceed to step S105.

[0025] S105. End the vacuuming of the oil tank and its connecting pipelines;

[0026] S106. Calculate the desorption flow rate integral during the vacuuming period. If the desorption flow rate integral is less than the preset flow rate threshold, proceed to step S107; otherwise, return to step S101.

[0027] S107. It is determined that the evaporator pipe of the vehicle's fuel tank is blocked.

[0028] Furthermore, the air pressure threshold is -15 hPa.

[0029] Furthermore, when the carbon canister solenoid valve opens, a vacuum is initiated on the oil tank and its connecting pipelines; when the carbon canister solenoid valve closes, the vacuuming of the oil tank and its connecting pipelines ends; the formula for calculating the desorption flow integral is as follows:

[0030]

[0031] in, Ms Represents the desorption flow integral; t 0 indicates the moment the carbon canister solenoid valve opens; t 1 indicates the moment the carbon canister solenoid valve closes; indicates M dte This indicates the flow rate of the carbon canister solenoid valve.

[0032] Furthermore, when the evaporator line of the vehicle's fuel tank is identified as blocked, the following steps are also performed:

[0033] S300, Start counting. When the count value reaches the preset number of times threshold, execute step S400.

[0034] S400: Identify whether the evaporator pipe of the vehicle's fuel tank is blocked. If it is blocked, return to step S300; otherwise, proceed to step S500.

[0035] S500, recovery of fuel tank leak diagnosis.

[0036] A fuel tank leak diagnosis and false alarm prevention system based on pipeline blockage identification, including

[0037] The vacuum control unit is used to set the pressure threshold, control the start of vacuuming of the oil tank and its connecting pipelines, and stop vacuuming of the oil tank and its connecting pipelines when the pressure in the oil tank is less than the pressure threshold.

[0038] The pipeline blockage detection unit is used to identify in real time whether the evaporator pipeline of the vehicle's fuel tank is blocked;

[0039] The counting unit is used to start counting when the pipeline blockage detection unit identifies that the evaporator pipe of the vehicle's fuel tank is blocked, and to stop counting after the count reaches a preset threshold number of times, and then cause the pipeline blockage detection unit to perform the detection again; and

[0040] The anti-false alarm control unit is used to suspend fuel tank leak diagnosis when the evaporator pipe of the vehicle fuel tank is blocked, and to resume fuel tank leak diagnosis when the evaporator pipe of the vehicle fuel tank changes from a blocked state to a non-blocked state.

[0041] Furthermore, the pipeline blockage identification unit includes

[0042] The pressure slope calculation module is used to calculate the slope of the pressure change in the oil tank during the vacuuming process of the oil tank and its connecting pipelines, and to record the maximum value of the pressure change slope in the oil tank.

[0043] The slope change rate calculation module is used to calculate the rate of change of the oil tank pressure slope during the vacuuming process of the oil tank and its connecting pipelines, and to record the maximum value of the rate of change of the oil tank pressure slope.

[0044] The flow integral module is used to calculate the desorption flow integral during the vacuuming period after the oil tank and its connecting pipelines have been evacuated.

[0045] The threshold storage module is used to store pre-set slope thresholds, rate of change thresholds, and flow thresholds; and

[0046] The blockage detection module is used to determine that the evaporator pipe of the vehicle's fuel tank is blocked when the maximum value of the slope of the fuel tank pressure change is greater than the slope threshold, the maximum value of the rate of change of the fuel tank pressure slope is greater than the rate of change threshold, or the desorption flow integral is less than the flow threshold.

[0047] In this invention, by introducing pipeline blockage identification during the vacuum establishment phase of the fuel tank, fuel tank leak diagnosis can be prevented when the evaporator pipeline is blocked, thereby avoiding false leak alarms caused by the rapid establishment of vacuum in the fuel tank after the evaporator pipeline is blocked. By identifying three parameters—the maximum value of the slope of pressure change over time, the maximum rate of change of the pressure slope, and the integral of the desorption flow rate at the end of vacuuming—pipeline blockage can be identified more accurately to prevent misjudgment. Attached Figure Description

[0048] The accompanying drawings, which are included to provide a further understanding of this application and form part of this application, illustrate exemplary embodiments and are used to explain this application, but do not constitute an undue limitation of this application. In the drawings:

[0049] Figure 1 In a preferred embodiment, the flowchart of a method for preventing false alarms in fuel tank leakage diagnosis based on pipeline blockage identification is provided.

[0050] Figure 2 In a preferred embodiment, a flowchart is provided to identify whether the evaporator pipe of the vehicle's fuel tank is blocked.

[0051] Figure 3 In a preferred embodiment, the present invention provides a structural block diagram of a fuel tank leak diagnosis and false alarm system based on pipeline blockage identification. Detailed Implementation

[0052] The following specific examples illustrate the implementation of the present invention. The illustrations provided in the following embodiments are only schematic representations of the basic concept of the present invention. Unless otherwise specified, the following embodiments and features can be combined with each other.

[0053] like Figure 1As shown, in a preferred embodiment of the fuel tank leak diagnosis and false positive prevention method based on pipeline blockage identification of the present invention, when the leak diagnosis program is run to start fuel tank leak diagnosis, the following steps are performed:

[0054] S100: Real-time identification of whether the vehicle's fuel tank evaporator pipe is blocked. If the fuel tank evaporator pipe is blocked, execute step S200 to pause fuel tank leak diagnosis. Figure 2 As shown, a method for identifying whether the evaporator line of a vehicle's fuel tank is blocked may include the following steps:

[0055] S101, the carbon canister solenoid valve opens, evacuating the oil tank and its connecting pipelines to create a negative pressure environment in the oil tank.

[0056] S102. Calculate the real-time slope of the fuel tank pressure change and find the maximum value of the slope. When the maximum value of the fuel tank pressure change slope is greater than a preset slope threshold, proceed to step S107 to determine that the vehicle's fuel tank evaporator pipe is blocked. When the maximum value of the fuel tank pressure change slope is less than or equal to the preset slope threshold, determine that the vehicle's fuel tank evaporator pipe is not blocked (if the vehicle's fuel tank evaporator pipe is not identified as blocked, it is considered non-blocked), and proceed to step S103. Maximum value of the fuel tank pressure change slope. That is, the oil tank pressure. P The maximum value of the first derivative during the vacuuming process is expressed as follows:

[0057]

[0058] S103. Calculate the real-time rate of change of the fuel tank pressure slope and find the maximum value of the rate of change. When the maximum value of the rate of change of the fuel tank pressure slope is greater than a preset threshold, proceed to step S107 to determine that the evaporator pipe of the vehicle's fuel tank is blocked. When the maximum value of the rate of change of the fuel tank pressure slope is less than or equal to the preset threshold, determine that the evaporator pipe of the vehicle's fuel tank is not blocked, and proceed to step S104. (Maximum value of the rate of change of the fuel tank pressure slope) That is, the oil tank pressure. P The maximum value of the second derivative during the vacuuming process is expressed as follows:

[0059]

[0060] S104. Determine whether the air pressure in the oil tank is less than the preset air pressure threshold. The air pressure threshold is generally set to -15hPa. When the air pressure in the oil tank is less than -15hPa, it means that the negative pressure in the oil tank is already low. Execute step S105 to end the vacuuming process.

[0061] S105, the carbon canister solenoid valve is closed, ending the vacuuming of the oil tank and its connecting pipelines.

[0062] S106. Calculate the desorption flow rate integral during vacuuming. If the desorption flow rate integral is less than a preset flow rate threshold, proceed to step S107 to determine if the vehicle's fuel tank evaporator pipe is blocked. Otherwise, it indicates that the vehicle's fuel tank evaporator pipe is not blocked, and return to step S101. The formula for calculating the desorption flow rate integral is:

[0063]

[0064] in, Ms Represents the desorption flow integral; t 0 indicates the moment when the carbon canister solenoid valve opens, which is the moment when the oil tank and its connecting pipelines begin to be evacuated; t 1 indicates the moment the carbon canister solenoid valve closes, i.e., the moment the oil tank and its connecting pipelines finish evacuating; indicates M dte Indicates the flow rate of the carbon canister solenoid valve; M dte The ratio of intake manifold pressure to ambient pressure and the hardware characteristics and opening degree of the carbon canister solenoid valve are determined by the ratio of intake manifold pressure to ambient pressure. The calculation method is existing technology and will not be elaborated here.

[0065] S107. It is determined that the evaporator pipe of the vehicle's fuel tank is blocked.

[0066] Of course, in other embodiments, when identifying whether the evaporator pipe of the vehicle's fuel tank is blocked, only one or two of the following can be calculated: the maximum slope of the fuel tank pressure change, the maximum rate of change of the fuel tank pressure slope, and the integral of the desorption flow rate. This can be used to determine whether the evaporator pipe of the vehicle's fuel tank is blocked.

[0067] S200. Suspend fuel tank leak diagnosis to prevent false positives during fuel tank leak diagnosis. At this time, the following steps can also be performed:

[0068] S300: The counter starts counting. When the count reaches the preset threshold, the counter is reset to zero, and step S400 is executed. Since a blockage in the pipeline will inevitably last for a period of time, the detection of whether the vehicle's fuel tank evaporator pipeline is blocked is paused during the counting process. This allows for delayed detection through counting, avoiding frequent vacuuming for pipeline blockage detection.

[0069] S400: Reset the counter to zero and check if the vehicle's fuel tank evaporator line is blocked. If blocked, return to step S300 and the counter will start counting again. Otherwise, proceed to step S500 to restore the fuel tank leak diagnosis.

[0070] S500, Resume fuel tank leak diagnosis. At this time, the system will still simultaneously identify whether the vehicle's fuel tank evaporator line is blocked.

[0071] In this embodiment, by introducing pipeline blockage identification during the fuel tank vacuum establishment phase, fuel tank leak diagnosis can be prohibited when the evaporator pipeline is blocked, thereby avoiding false leak alarms caused by the rapid establishment of vacuum in the fuel tank after evaporator pipeline blockage. By identifying three parameters—the maximum value of the slope of pressure change over time, the maximum rate of change of the pressure slope, and the integral of the desorption flow rate at the end of vacuuming—and setting identification conditions for each of these three parameters, fuel tank leak diagnosis is prohibited if any one of these conditions is met during the current driving cycle. If none of the three conditions are met, fuel tank leak diagnosis can proceed normally, thus more accurately identifying pipeline blockages and preventing false alarms.

[0072] like Figure 3 As shown, a preferred embodiment of the fuel tank leak diagnosis and false alarm prevention system based on pipeline blockage identification of the present invention includes a vacuum control unit, a pipeline blockage identification unit, a counting unit, and a false alarm prevention control unit. It should be noted that the device for vacuuming the fuel tank and its connecting pipelines via the carbon canister solenoid valve, and the device for detecting the fuel tank pressure, are all components used in vehicle fuel tank leak diagnosis systems, i.e., existing vehicle components, and therefore are not included in the false alarm prevention system.

[0073] The vacuum control unit is used to set a pressure threshold, control the start of vacuuming of the fuel tank and its connecting pipelines, and stop vacuuming of the fuel tank and its connecting pipelines when the pressure in the fuel tank is lower than the pressure threshold. However, when vacuuming of the fuel tank and its connecting pipelines is required, the vacuum control unit opens the carbon canister solenoid valve to start vacuuming; when a negative pressure is established in the fuel tank and the pressure in the fuel tank is lower than the pressure threshold, the vacuum control unit closes the carbon canister solenoid valve to stop vacuuming of the fuel tank and its connecting pipelines.

[0074] The pipeline blockage identification unit is used to identify in real time whether the evaporator pipeline of the vehicle's fuel tank is blocked. The pipeline blockage identification unit may include a pressure slope calculation module, a slope change rate calculation module, a flow integral module, a threshold storage module, and a blockage determination module. The pressure slope calculation module calculates the slope of the fuel tank pressure change during the vacuuming process of the fuel tank and its connecting pipelines, and records the maximum value of the slope. The slope change rate calculation module calculates the rate of change of the fuel tank pressure slope during the vacuuming process, and records the maximum value of the rate of change of the fuel tank pressure slope. The flow integral module calculates the desorption flow integral during the vacuuming period after the vacuuming of the fuel tank and its connecting pipelines is completed. The threshold storage module stores pre-set slope thresholds, change rate thresholds, and flow thresholds. The blockage determination module determines that the evaporator pipeline of the vehicle's fuel tank is blocked when the maximum value of the fuel tank pressure change slope is greater than the slope threshold, the maximum value of the fuel tank pressure slope change rate is greater than the change rate threshold, or the desorption flow integral is less than the flow threshold. Of course, in the pressure slope calculation module, slope change rate calculation module and flow integration module, the pipeline blockage identification unit may only include one or two of them. Correspondingly, the threshold storage module may only store one or two of the slope threshold, change rate threshold and flow threshold.

[0075] The counting unit starts counting when the pipeline blockage identification unit detects that the evaporator pipe of the vehicle's fuel tank is blocked, and stops counting after the count reaches a preset threshold. Then, the pipeline blockage identification unit re-identifies whether the evaporator pipe of the vehicle's fuel tank is blocked. While the counting unit is in counting mode, the vacuum control unit pauses vacuuming, and the pipeline blockage identification unit also pauses pipeline blockage identification, thus avoiding frequent vacuuming for pipeline blockage identification.

[0076] The anti-false alarm control unit is used to suspend fuel tank leak diagnosis when the evaporator pipe of the vehicle fuel tank is blocked, so as to prevent false alarms during fuel tank leak diagnosis; and to resume fuel tank leak diagnosis when the evaporator pipe of the vehicle fuel tank changes from a blocked state to a non-blocked state.

[0077] In this embodiment, the pipeline blockage identification unit can prevent oil tank leak diagnosis when the evaporator pipeline is blocked, thereby avoiding false leak alarms caused by the rapid establishment of vacuum in the oil tank after the evaporator pipeline is blocked. By identifying three parameters—the maximum value of the slope of pressure change over time, the maximum rate of change of the pressure slope, and the integral of the desorption flow rate at the end of vacuuming—and setting identification conditions for each of the three parameters, pipeline blockage can be identified more accurately to prevent misjudgment.

[0078] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. A method for preventing false alarms in fuel tank leak diagnosis based on pipeline blockage identification, characterized in that: When initiating fuel tank leak diagnosis, perform the following steps: S100: Real-time identification of whether the evaporator pipe of the vehicle's fuel tank is blocked. When the evaporator pipe of the vehicle's fuel tank is blocked, execute step S200. S200, Suspend fuel tank leak diagnosis; The method for identifying whether the evaporator line of a vehicle's fuel tank is blocked includes the following steps: S101. Vacuum the fuel tank and its connecting pipelines. S102. Calculate the maximum slope of the change in tank pressure; if the maximum slope of the change in tank pressure is greater than the preset slope threshold, proceed to step S107; otherwise, proceed to step S103. S103. Calculate the maximum rate of change of the tank pressure slope; if the maximum rate of change of the tank pressure slope is greater than the preset rate of change threshold, proceed to step S107; otherwise, proceed to step S104. S104. Determine whether the air pressure in the fuel tank is less than the preset air pressure threshold. If the air pressure in the fuel tank is less than the preset air pressure threshold, proceed to step S105. S105. End the vacuuming of the oil tank and its connecting pipelines; S106. Calculate the desorption flow rate integral during the vacuuming period. If the desorption flow rate integral is less than the preset flow rate threshold, proceed to step S107; otherwise, return to step S101. S107. It is determined that the evaporator pipe of the vehicle's fuel tank is blocked.

2. The method for preventing false alarms in fuel tank leakage diagnosis based on pipeline blockage identification according to claim 1, characterized in that: The pressure threshold is -15 hPa.

3. The method for preventing false alarms in fuel tank leakage diagnosis based on pipeline blockage identification according to claim 1, characterized in that: When the carbon canister solenoid valve opens, vacuuming of the oil tank and its connecting pipelines begins; when the carbon canister solenoid valve closes, vacuuming of the oil tank and its connecting pipelines ends; the formula for calculating the desorption flow integral is: in, Ms Represents the desorption flow integral; t 0 indicates the moment the carbon canister solenoid valve opens; t 1 indicates the moment the carbon canister solenoid valve closes; indicates M dte This indicates the flow rate of the carbon canister solenoid valve.

4. A method for preventing false alarms in fuel tank leakage diagnosis based on pipeline blockage identification according to any one of claims 1 to 3, characterized in that, When the evaporator line of the vehicle's fuel tank is detected to be blocked, the following steps are also performed: S300, Start counting. When the count value reaches the preset number of times threshold, execute step S400. S400: Identify whether the evaporator pipe of the vehicle's fuel tank is blocked. If it is blocked, return to step S300; otherwise, proceed to step S500. S500, recovery of fuel tank leak diagnosis.

5. A system for preventing false alarms in fuel tank leakage diagnosis based on pipeline blockage identification, characterized in that: The method for preventing false alarms in fuel tank leakage diagnosis based on pipeline blockage identification, as described in any one of claims 1 to 4, is adopted. include The vacuum control unit is used to set the pressure threshold, control the start of vacuuming of the oil tank and its connecting pipelines, and stop vacuuming of the oil tank and its connecting pipelines when the pressure in the oil tank is less than the pressure threshold. The pipeline blockage detection unit is used to identify in real time whether the evaporator pipeline of the vehicle's fuel tank is blocked; The counting unit is used to start counting when the pipeline blockage detection unit identifies that the evaporator pipe of the vehicle's fuel tank is blocked, and to stop counting after the count reaches a preset threshold number of times, and then cause the pipeline blockage detection unit to perform the detection again; and The anti-false alarm control unit is used to suspend fuel tank leak diagnosis when the evaporator pipe of the vehicle fuel tank is blocked, and to resume fuel tank leak diagnosis when the evaporator pipe of the vehicle fuel tank changes from a blocked state to a non-blocked state.

6. The fuel tank leak diagnosis and false alarm system based on pipeline blockage identification according to claim 5, characterized in that: The pipeline blockage identification unit includes The pressure slope calculation module is used to calculate the slope of the pressure change in the oil tank during the vacuuming process of the oil tank and its connecting pipelines, and to record the maximum value of the pressure change slope in the oil tank. The slope change rate calculation module is used to calculate the rate of change of the oil tank pressure slope during the vacuuming process of the oil tank and its connecting pipelines, and to record the maximum value of the rate of change of the oil tank pressure slope. The flow integral module is used to calculate the desorption flow integral during the vacuuming period after the oil tank and its connecting pipelines have been evacuated. The threshold storage module is used to store pre-set slope thresholds, rate of change thresholds, and flow thresholds; and The blockage detection module is used to determine that the evaporator pipe of the vehicle's fuel tank is blocked when the maximum value of the slope of the fuel tank pressure change is greater than the slope threshold, the maximum value of the rate of change of the fuel tank pressure slope is greater than the rate of change threshold, or the desorption flow integral is less than the flow threshold.

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