Abnormality diagnosis device for evaporated fuel processing device

Abstract

The present invention provides an abnormality diagnosis device for an evaporated fuel processing device capable of performing abnormality diagnosis by a simple method. The abnormality diagnosis device for an evaporated fuel processing device is provided with: a first acquisition unit; an opening / closing control unit that executes an opening / closing process in which an opening / closing operation is repeated a predetermined upper limit number of times; a second acquisition unit; and a diagnosis unit that diagnoses the fuel tank, the canister, the closing valve, and the switching valve as normal if the amount of increase from the pressure in the tank acquired by the first acquisition unit to the pressure in the tank acquired by the second acquisition unit is equal to or greater than a threshold value before the number of repetitions of the opening / closing operation reaches the upper limit number. And diagnoses at least one of the fuel tank, the canister, the closing valve, and the switching valve as an abnormality even if the number of repetitions of the opening / closing operation reaches the upper limit number and the increase amount is less than a threshold value.

Description

Technical Field

[0001] This invention relates to an anomaly diagnosis device for evaporative fuel processing equipment. Background Technology

[0002] There are techniques for diagnosing anomalies in the fuel tank and adsorption tank of an evaporative fuel processing device (see, for example, Patent Document 1).

[0003] [Existing Technical Documents]

[0004] [Patent Literature]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 2024-071149 Summary of the Invention

[0006] [The problem the invention aims to solve]

[0007] In diagnosing anomalies in such evaporative fuel processing devices, it is desirable to be able to perform anomaly diagnosis using simple methods that do not involve pumps or the like.

[0008] Therefore, the object of the present invention is to provide an anomaly diagnosis device for an evaporative fuel processing device that can perform anomaly diagnosis in a simple way.

[0009] [Methods used to solve problems]

[0010] The above objective can be achieved by an anomaly diagnosis device for an evaporative fuel treatment apparatus. This device includes a fuel tank for storing engine fuel, an adsorption tank for adsorbing evaporative fuel generated in the fuel tank, a vapor passage connecting the fuel tank and the adsorption tank, a purge passage connecting the engine intake passage and the adsorption tank, a shut-off valve for opening and closing the vapor passage, a purge valve for opening and closing the purge passage, an external air inlet passage for introducing external air into the adsorption tank, a switching valve for opening and closing the external air inlet passage, and an internal pressure sensor for detecting the pressure inside the fuel tank, i.e., the internal pressure. The anomaly diagnosis device further includes: a first acquisition unit for acquiring the internal pressure in a cut-off state where the purge valve is closed, the switching valve is open, and the shut-off valve is closed; and an opening / closing control unit for executing an opening / closing process that repeatedly performs opening and closing operations according to a predetermined procedure. The upper limit number of times the opening and closing operation is defined as follows: the operation is a switch from the cut-off state to a connected state where the pressure inside the tank is stabilized by opening the closing valve after closing the switching valve, and then returning to the cut-off state by opening the switching valve after closing the closing valve in the connected state; the second acquisition unit acquires the pressure inside the tank when the closing valve is closed from the connected state during the execution of the opening and closing process; and the diagnosis unit diagnoses the fuel tank, the adsorption tank, the closing valve, and the switching valve as normal if the increase in pressure from the pressure inside the tank acquired by the first acquisition unit to the pressure inside the tank acquired by the second acquisition unit is above a threshold before the number of repetitions of the opening and closing operation reaches the upper limit number of times, and diagnoses at least one of the fuel tank, the adsorption tank, the closing valve, and the switching valve as abnormal even if the number of repetitions of the opening and closing operation reaches the upper limit number of times.

[0011] [Invention Effects]

[0012] According to the present invention, an anomaly diagnosis device for an evaporative fuel processing apparatus is provided, which can perform anomaly diagnosis in a simple manner. Attached Figure Description

[0013] Figure 1 This is a schematic diagram of an evaporative fuel treatment device used in vehicles.

[0014] Figure 2 It represents P sys A coordinate graph showing the relationship between [n] and the number of repetitions n.

[0015] Figure 3 This is a flowchart illustrating abnormality diagnosis and control.

[0016] [Explanation of reference numerals in the attached figures]

[0017] 1 vehicle

[0018] 30 fuel tanks

[0019] 31 Adsorption tank

[0020] 50 Box Internal Pressure Sensor

[0021] 60 ECU (Abnormal Diagnostic Device, First Acquisition Unit, On / Off Control Unit, Second Acquisition Unit, Diagnostic Unit) Detailed Implementation

[0022] [Brief Structure of the Evaporative Fuel Processing Unit]

[0023] Figure 1 This is a schematic structural diagram of the evaporative fuel treatment device 3 applied to vehicle 1. Vehicle 1 includes the evaporative fuel treatment device 3, engine 10, and ECU (Electronic Control Unit) 60. Power from engine 10 is transmitted to drive wheels 20. Engine 10 is equipped with a fuel injection valve 12 that injects fuel into combustion chamber 11, and spark plugs 13 that ignite the mixture of injected fuel and intake air. Intake passage 14 and exhaust passage 15 are connected to combustion chamber 11. A pressurized fuel tank 16 is installed in intake passage 14. Throttle valve 17 is installed upstream of pressurized fuel tank 16.

[0024] The evaporative fuel treatment device 3 includes a fuel tank 30 for storing fuel. The fuel in the fuel tank 30 is supplied to the fuel injection valve 12 via a fuel supply path. The evaporative fuel treatment device 3 prevents the release of evaporative fuel generated in the fuel tank 30 into the atmosphere.

[0025] The fuel tank 30 includes a tank body 30a, a fuel inlet pipe 30b, and a check valve 30c. The tank body 30a stores fuel. The fuel inlet pipe 30b guides fuel to the tank body 30a. The check valve 30c allows fuel to be introduced from the fuel inlet pipe 30b to the tank body 30a, but restricts the backflow of fuel from the tank body 30a to the fuel inlet pipe 30b. A tank pressure sensor 50 detects the pressure inside the fuel tank 30. A combustion temperature sensor 52 detects the temperature of the fuel inside the fuel tank 30, i.e., the combustion temperature.

[0026] The evaporative fuel processing device 3 is equipped with an adsorption tank 31 that adsorbs the evaporative fuel generated in the fuel tank 30. The adsorption tank 31 and the fuel tank 30 are connected by a steam passage 32. A shut-off valve 42 is provided in the steam passage 32 to open and close the steam passage 32. By opening the shut-off valve 42, the evaporative fuel in the fuel tank 30 is temporarily captured by the adsorption material in the adsorption tank 31. An adsorption tank internal pressure sensor 51 capable of detecting the internal pressure of the adsorption tank is provided in the adsorption tank 31.

[0027] The adsorption tank 31 and the pressure-stabilizing fuel tank 16 are connected by a purge passage 33. A purge valve 43 is provided in the purge passage 33 to open and close the purge passage 33. An external air inlet passage 36 is connected to the adsorption tank 31 to introduce external air into the adsorption tank 31. An air filter 37 is provided at the open end of the external air inlet passage 36.

[0028] A switching valve 46 is provided in the external air intake passage 36 to open and close the external air intake passage 36. When the engine 10 is running, the switching valve 46 opens the external air intake passage 36.

[0029] When the specified conditions are met, during the operation of engine 10, with switching valve 46 open and closing valve 42 closed, purge valve 43 is opened. This causes the evaporated fuel to separate from adsorption tank 31. The separated evaporated fuel is then introduced into pressure-stabilized fuel tank 16 via purge passage 33 and burned in combustion chamber 11.

[0030] ECU 60 is an electronic control unit that includes arithmetic processing circuits for various calculations related to the driving control of vehicle 1 and a memory storing control programs and data. Various sensors for detecting the operating status of engine 10, such as a tank pressure sensor 50, a fuel tank pressure sensor 51, a fuel temperature sensor 52, and an ignition switch 55, are connected to ECU 60. ECU 60 executes various controls on vehicle 1 and engine 10 based on signals from these sensors and switches. Furthermore, ECU 60, described in detail later, is an example of an abnormality diagnostic device. ECU 60 functionally implements a first acquisition unit, an on / off control unit, a second acquisition unit, and a diagnostic unit.

[0031] [Principles of Abnormal Diagnosis and Control]

[0032] When explaining the principle of the abnormal diagnosis and control in this embodiment, such as Figure 1 As shown, the space within the fuel tank 30's main body 30a (excluding the fuel), the space within the fuel inlet pipe 30b, and the space within the steam passage 32 closest to the fuel tank 30 than the shut-off valve 42 are referred to as tank space t. Similarly, the space within the adsorption tank 31, the space within the steam passage 32 closest to the adsorption tank 31 than the shut-off valve 42, and the space within the purge passage 33 closest to the adsorption tank 31 than the purge valve 43 are referred to as adsorption tank space c. Tank space t is sealed by closing the shut-off valve 42. Adsorption tank space c is sealed by closing the shut-off valve 42, the switching valve 46, and the purge valve 43. The internal pressures of tank space t and adsorption tank space c are respectively referred to as P. t and P c The volumes of the box space t and the adsorption tank space c are respectively called V. t and V c .

[0033] The state where switching valve 46 is open and closing valve 42 and purge valve 43 are closed is called the cut-off state. In this state, the adsorption tank space c is open to the atmosphere through the opening of switching valve 46, and the tank space t is sealed through the closing of closing valve 42. Under steady-state conditions, the temperatures in the tank space t and the adsorption tank space c are the same. Since the adsorption tank space c is open to the atmosphere, P... c Assume it is P atm (Atmospheric pressure). Here, it is assumed that the vapor partial pressure generated when the evaporating fuel separates from the adsorption tank 31 is zero. P t It is P ta (Partial pressure of air) and P tv The total value of (vapor partial pressure). Additionally, assuming P is in the off state... t With P atm If the atmospheric pressures are equal, then P ta =P atm -P tv Established.

[0034] When the shut-off valve 42 is opened after the switching valve 46 has been closed, a sealed system space sys is formed, connecting the adsorption tank space c and the box space t. The internal pressure of the system space sys is set to P. sys P sys It is P sysa (Partial pressure of air) and P sysv The total value of (vapor partial pressure). P under stable conditions of pressure inside the tank and adsorption vessel. sys Calculate it as follows.

[0035] [Formula 1] air partial pressure

[0036] Vapor partial pressure

[0037] Furthermore, the reason why the vapor partial pressure in the connected state is the same as the vapor partial pressure in the box space t in the disconnected state is that the saturated vapor pressure is determined to be a constant value according to temperature.

[0038] Next, starting from the connected state, after the closing valve 42 is closed, the switching valve 46 is opened, returning to the disconnected state. In this case, P... c Becoming P again atm Additionally, P t Keep P sys The increase in internal pressure of the box space t under the initial cut-off state and the second cut-off state is calculated as follows.

[0039] [Equation 2]

[0040] If the opening and closing operations described above are repeated, the internal pressure of the box will be set to P in the nth (an integer greater than 2) cut-off state. sysa [n], then the vapor partial pressure is P tv Therefore, the partial pressure of air can be expressed as P. sysa [n]-P tv The (n+1)th time P sysa [n+1]、P sysv [n+1]、P sys [n+1] is calculated as follows.

[0041] [Formula 3] air partial pressure

[0042] Vapor partial pressure

[0043] Figure 2 It represents P sys A coordinate graph showing the relationship between [n] and the number of repetitions n. Under normal conditions of the evaporative fuel processing unit 3, such as... Figure 2 As shown, P sys [n] increases parabolically with the number of repetitions n, gradually approaching the combined value of atmospheric pressure and fuel vapor pressure. Conversely, under abnormal conditions, even with an increase in the number of repetitions n, P... sys [n] also remains approximately the same value. Therefore, setting an upper limit for the number of repetitions n, if P... sys The increase (P) sys [n]-P sys If [0] is above the threshold, it can be diagnosed as normal; if it is below the threshold, it can be diagnosed as abnormal. Here, P sys [n] and the above-mentioned cutting-off state under the condition of repetition number n. t Same. P t The pressure can be detected by the chamber pressure sensor 50. Therefore, the ECU 60 performs abnormality diagnostic control based on whether the increase in pressure value obtained by the chamber pressure sensor 50 in the cut-off state is above a threshold to diagnose whether an abnormality exists.

[0044] Furthermore, in abnormal diagnostic control, ECU60 calculates and learns P as the fuel vapor pressure based on the following formula after transforming the above equation (2). tv .

[0045] [Formula 4]

[0046] [Details of Abnormal Diagnosis and Control]

[0047] Figure 3 This is a flowchart illustrating the abnormal diagnosis control. ECU 60 sets the repetition count n to zero (step S1) and determines whether the preconditions for performing the abnormal diagnosis are met (step S2). If the condition is not met in step S2, the control ends. If the condition is met in step S2, ECU 60 obtains the internal pressure (P) based on the internal pressure sensor 50. sys [0])(Step S3). Step S3 is an example of the processing performed by the first acquisition unit.

[0048] Next, ECU 60 updates the repetition count n to (n+1) and performs the opening and closing process described above (step S4). Step S4 is an example of the process performed by the opening and closing control unit. At this time, the state where switching valve 46 is open and closing valve 42 and purge valve 43 are closed is set to the cut-off state. ECU 60 closes switching valve 46 (step S5), and then opens closing valve 42 (step S6). This creates a connected state. Next, ECU 60 determines whether the pressure inside the tank and the pressure inside the adsorption tank are stable based on the pressure values ​​detected by the tank pressure sensor 50 and the adsorption tank pressure sensor 51, respectively (step S7). If the result is negative in step S7, step S7 is executed again.

[0049] If the condition is yes in step S7, ECU 60 closes the shut-off valve 42 (step S8). Next, ECU 60 obtains the internal pressure (P) based on the internal pressure sensor 50. sys [n])(Step S9). Step S9 is an example of the processing performed by the second acquisition unit.

[0050] Next, the ECU60 calculates the fuel vapor pressure based on the above equation (3) and learns the average value of the fuel vapor pressure n times (step S10). In addition, the ECU60 obtains the combustion temperature based on the combustion temperature sensor 52 and calculates the average value of the combustion temperature n times (step S11).

[0051] Next, ECU60 opens switching valve 46 (step S12). After a predetermined time, ECU60 determines whether the pressure inside the adsorption tank is stable near atmospheric pressure based on the pressure sensor 51 inside the adsorption tank (step S13). If the result is negative in step S13, ECU60 considers switching valve 46 to be closed and stuck, and diagnoses it as an abnormality (step S14).

[0052] If the condition is yes in step S13, ECU60 determines the increase in pressure inside the tank (P). sys [n]-P sys[0]) Is it above the threshold (step S15)? If yes in step S15, ECU60 diagnoses the fuel tank 30, adsorption canister 31, shut-off valve 42, and switching valve 46 as normal (step S16). Step S16 is an example of the processing performed by the diagnostic unit. Next, ECU60 determines that the learned value in step S10 and the average value in step S11 are normal values ​​(step S17).

[0053] If the result in step S15 is negative, the ECU 60 determines whether the number of repetitions n exceeds the upper limit (step S18). If the result in step S18 is negative, step S4 is restarted. This opening and closing operation is repeated. If the result in step S18 is positive, the ECU 60 diagnoses at least one abnormality in the fuel tank 30, adsorption canister 31, shut-off valve 42, and switching valve 46 (step S19). Specifically, it is considered that any one of the following has occurred: leakage in the fuel tank 30, leakage in the adsorption canister 31, jamming of the shut-off valve 42, jamming of the switching valve 46, or jamming of the switching valve 46. Step S19 is an example of the processing performed by the diagnostic unit.

[0054] As described above, the malfunction diagnosis of the evaporative fuel processing unit 3 is performed by repeatedly opening and closing the shut-off valve 42 and the switching valve 46.

[0055] The embodiments of the present invention have been described in detail above, but the present invention is not limited to these specific embodiments. Various modifications and alterations can be made within the scope of the spirit of the present invention as set forth in the claims.

Claims

1. An abnormality diagnosis device for an evaporative fuel treatment apparatus, comprising a fuel tank for storing engine fuel, an adsorption tank for adsorbing evaporative fuel generated in the fuel tank, a vapor passage connecting the fuel tank and the adsorption tank, a purge passage connecting the engine intake passage and the adsorption tank, a shut-off valve for opening and closing the vapor passage, a purge valve for opening and closing the purge passage, an external air inlet passage for introducing external air into the adsorption tank, a switching valve for opening and closing the external air inlet passage, and an internal pressure sensor for detecting the pressure inside the fuel tank, i.e., the internal pressure of the fuel tank, wherein, The abnormality diagnosis device of the evaporative fuel processing unit includes: The first acquisition unit acquires the internal pressure of the chamber in the cut-off state where the purge valve is closed, the switching valve is open, and the closing valve is closed; The opening and closing control unit executes the opening and closing process, which repeats the opening and closing operation a predetermined maximum number of times. The opening and closing operation is an operation that switches from the cut-off state to a connected state where the pressure inside the tank is stabilized by opening the closing valve after closing the switching valve, and then opens the switching valve again after closing the closing valve in the connected state to return to the cut-off state. The second acquisition unit acquires the internal pressure of the tank when the closing valve is closed from the connected state during the execution of the opening and closing process; as well as The diagnostic unit diagnoses the fuel tank, the adsorption tank, the shut-off valve, and the switching valve as normal if the increase in pressure from the tank obtained by the first acquisition unit to the tank obtained by the second acquisition unit is above a threshold number before the number of repetitions of the opening and closing operation reaches the upper limit number, and diagnoses at least one of the fuel tank, the adsorption tank, the shut-off valve, and the switching valve as abnormal if the number of repetitions of the opening and closing operation reaches the upper limit number and the increase is less than the threshold number.

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