Abnormality diagnosis device for evaporated fuel processing device

Abstract

To provide an abnormality diagnosis device for an evaporated fuel treatment device capable of performing abnormality diagnosis by a simple method.SOLUTION: Acquiring a tank internal pressure in a shut-off state; switching from the shut-off state to a communication state in which the tank internal pressure is stabilized by opening a sealing valve after closing a switching valve; A second acquisition unit configured to acquire the tank internal pressure in a state where the sealing valve is closed from the communication state, and a diagnosis unit configured to diagnose that the sealing valve is normal when an increase amount from the tank internal pressure acquired by the first acquisition unit to the tank internal pressure acquired by the second acquisition unit becomes equal to or greater than a threshold value, A diagnosis unit configured to diagnose that there is an abnormality when the amount of increase is less than the threshold value even if the number of repetitions of the opening-closing operation reaches the upper limit number of times.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to an abnormality diagnosis device for an evaporated fuel treatment device. [Background technology]

[0002] There is a technique for diagnosing abnormalities in a fuel tank or a canister of an evaporated fuel treatment device (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent Publication No. 2024-071149 Summary of the Invention [Problem to be solved by the invention]

[0004] In diagnosing such an evaporated fuel treatment device, it is desirable to be able to diagnose the abnormality by a simple method that does not require the use of a pump or the like.

[0005] SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide an abnormality diagnosis device for an evaporated fuel treatment device that can perform abnormality diagnosis using a simple method. [Means for solving the problem]

[0006] The object of the present invention is to provide an abnormality diagnosis device for an evaporated fuel treatment device having a fuel tank for storing fuel for an engine, a canister for adsorbing evaporated fuel generated in the fuel tank, a vapor passage connecting the fuel tank and the canister, a purge passage connecting an intake passage of the engine and the canister, a shut-off valve for opening and closing the vapor passage, a purge valve for opening and closing the purge passage, an outside air introduction passage for introducing outside air into the canister, a switching valve for opening and closing the outside air introduction passage, and an internal tank pressure sensor for detecting internal tank pressure, which is the pressure inside the fuel tank, the abnormality diagnosis device including: a first acquisition unit for acquiring the internal tank pressure in a blocked state in which the purge valve is closed, the switching valve is opened, and the shut-off valve is closed; This can be achieved by an abnormality diagnosis device for an evaporated fuel treatment device, which includes an opening / closing control unit that executes an opening / closing process that repeats an opening / closing operation of closing the shut-off valve, opening the switching valve, and returning it to the shut-off state a predetermined maximum number of times; a second acquisition unit that acquires the tank internal pressure from the connected state to a state where the shut-off valve is closed while the opening / closing process is being executed; and a diagnosis unit that diagnoses the fuel tank, the canister, the shut-off valve, and the switching valve as normal if the amount of increase from the tank internal pressure acquired by the first acquisition unit to the tank internal pressure acquired by the second acquisition unit becomes equal to or greater than a threshold value before the number of repeated opening / closing operations reaches the maximum number of times, and diagnoses at least one of the fuel tank, the canister, the shut-off valve, and the switching valve as abnormal if the amount of increase is less than the threshold value even after the number of repeated opening / closing operations reaches the maximum number of times. [Effects of the Invention]

[0007] According to the present invention, it is possible to provide an abnormality diagnosis device for an evaporated fuel treatment device that can perform abnormality diagnosis using a simple method. [Brief explanation of the drawings]

[0008] [Figure 1] 1 is a schematic diagram of an evaporated fuel treatment device applied to a vehicle; [Figure 2]10 is a graph showing the relationship between Psys[n] and the number of iterations n. [Figure 3] 10 is a flowchart illustrating an example of abnormality diagnosis control. DETAILED DESCRIPTION OF THE INVENTION

[0009] [Outline of the fuel vapor treatment device] FIG. 1 is a schematic diagram of an evaporated fuel processing device 3 applied to a vehicle 1. The vehicle 1 includes the evaporated fuel processing device 3, an engine 10, and an ECU (Electronic Control Unit) 60. Power from the engine 10 is transmitted to drive wheels 20. The engine 10 is provided with a fuel injection valve 12 that injects fuel into a combustion chamber 11, and an ignition plug 13 that ignites an air-fuel mixture that is a mixture of the injected fuel and intake air. An intake passage 14 and an exhaust passage 15 are connected to the combustion chamber 11. A surge fuel tank 16 is provided in the intake passage 14. A throttle valve 17 is provided upstream of the surge fuel tank 16.

[0010] The evaporated fuel processing device 3 includes a fuel tank 30 that stores fuel. The fuel in the fuel tank 30 is supplied to the fuel injection valve 12 via a fuel supply path. The evaporated fuel processing device 3 prevents evaporated fuel generated in the fuel tank 30 from being released into the atmosphere.

[0011] The fuel tank 30 includes a tank main body 30a, a fuel inlet pipe 30b, and a check valve 30c. The tank main body 30a stores fuel. The fuel inlet pipe 30b guides the fuel to the tank main body 30a. The check valve 30c allows fuel to be introduced from the fuel inlet pipe 30b to the tank main body 30a but prevents fuel from flowing back from the tank main body 30a to the fuel inlet pipe 30b. The tank internal pressure sensor 50 detects the pressure inside the fuel tank 30. The fuel temperature sensor 52 detects the fuel temperature inside the fuel tank 30.

[0012] The evaporated fuel treatment device 3 is provided with a canister 31 that adsorbs evaporated fuel generated in a fuel tank 30. The canister 31 and the fuel tank 30 are connected via a vapor passage 32. The vapor passage 32 is provided with a shut-off valve 42 that opens and closes the vapor passage 32. By opening the shut-off valve 42, the evaporated fuel in the fuel tank 30 is temporarily collected in the adsorbent of the canister 31. The canister 31 is provided with a canister internal pressure sensor 51 that can detect the internal pressure of the canister.

[0013] The canister 31 and the surge fuel tank 16 are connected to each other via a purge passage 33. A purge valve 43 that opens and closes the purge passage 33 is provided in the purge passage 33. An outside air introduction passage 36 that introduces outside air into the canister 31 is connected to the canister 31. An air filter 37 is provided at the open end of the outside air introduction passage 36.

[0014] The outside air introduction passage 36 is provided with a selector valve 46 that opens and closes the outside air introduction passage 36. When the engine 10 is running, the selector valve 46 opens the outside air introduction passage 36.

[0015] When a predetermined condition is met, the purge valve 43 is opened while the engine 10 is running, with the switching valve 46 open and the stop valve 42 closed. This causes the evaporated fuel to desorb from the canister 31. The desorbed evaporated fuel is introduced into the surge fuel tank 16 via the purge passage 33 and combusted in the combustion chamber 11.

[0016] The ECU 60 is an electronic control unit including a processing circuit that performs various types of arithmetic processing related to the driving control of the vehicle 1, and a memory that stores control programs and data. The ECU 60 is connected to various sensors that detect the operating state of the engine 10, a tank pressure sensor 50, a canister pressure sensor 51, a fuel temperature sensor 52, an ignition switch 55, and the like. The ECU 60 executes various controls of the vehicle 1 and the engine 10 based on signals from these sensors and switches. The ECU 60 is an example of an abnormality diagnosis device, which will be described in detail later. The ECU 60 functionally realizes a first acquisition unit, an opening / closing control unit, a second acquisition unit, and a diagnosis unit.

[0017] [Principles of abnormality diagnosis control] In explaining the principle of the abnormality diagnosis control of this embodiment, as shown in Fig. 1, the space other than the fuel in the tank main body 30a of the fuel tank 30, the space in the fuel introduction pipe 30b, and the space in the vapor passage 32 on the fuel tank 30 side of the shut-off valve 42 will be referred to as tank space t. Also, the space in the canister 31, the space in the vapor passage 32 on the canister 31 side of the shut-off valve 42, and the space in the purge passage 33 on the canister 31 side of the purge valve 43 will be referred to as canister space c. The tank space t is sealed when the shut-off valve 42 is closed. Also, the canister space c is sealed when the shut-off valve 42, the switching valve 46, and the purge valve 43 are closed. The internal pressures of the tank space t and the canister space c are defined as P t and P c The volumes of the tank space t and the canister space c are called V t and V c It is called.

[0018] The state in which the switching valve 46 is open and the isolation valve 42 and purge valve 43 are closed is called the shut-off state. In this state, the canister space c is opened to the atmosphere by the opening of the switching valve 46, and the tank space t is sealed by the closing of the isolation valve 42. In the steady state, the temperatures in the tank space t and the canister space c are the same. Since the canister space c is open to the atmosphere, P c HA P atmIt is assumed that the partial pressure of vapor due to desorption of evaporated fuel from the canister 31 is zero. t is P ta (air partial pressure) and P tv In the shutoff state, P t HA P atm (atmospheric pressure), P ta =P atm -P tv holds true.

[0019] When the switching valve 46 is closed from the shutoff state and then the stop valve 42 is opened, the canister space c and the tank space t are in communication with each other, forming a sealed system space sys. sys Let's say. P sys is P sysa (air partial pressure) and P sysv The total value of the vapor partial pressure and the vapor partial pressure is the P when the tank internal pressure and the canister internal pressure are stable. sys is calculated as follows:

[0020]

number

[0021] Next, after the block valve 42 is closed, the switching valve 46 is opened to return the state from the communication state to the shutoff state again. c P again atm Also, P t HA P sys The increase in the internal pressure of the tank space t between the first and second shutoff states is calculated as follows:

[0022]

number

[0023] Repeat the above opening and closing operation and check the tank internal pressure at the nth (integer of 2 or more) shutoff time. sysa [n], the vapor partial pressure is P tv Therefore, the partial pressure of the air is P sysa [n]-P tv It can be expressed as follows. sysa [n+1], P sysv [n+1], P sys [n+1] is calculated as follows:

[0024]

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[0025] Figure 2 shows the P sys 2 is a graph showing the relationship between [n] and the number of repetitions n. When the evaporated fuel treatment device 3 is normal, as shown in FIG. sys [n] increases parabolically as the number of repetitions n increases, and approaches the sum of the atmospheric pressure and the fuel vapor pressure. sys [n] is maintained at approximately the same value even if the number of repetitions n increases. Therefore, an upper limit is set for the number of repetitions n, and P sys Increase in (P sys [n]-P sys If P [0] is greater than or equal to the threshold, it is diagnosed as normal, and if it is less than the threshold, it is diagnosed as abnormal. sys [n] is the P in the above-mentioned cutoff state when the number of repetitions is n. t It is the same as P t can be detected by the tank internal pressure sensor 50. Therefore, the ECU 60 executes abnormality diagnosis control to diagnose whether or not there is an abnormality based on whether or not the increase in the pressure value acquired by the tank internal pressure sensor 50 in the shut-off state is equal to or greater than a threshold value.

[0026] In the abnormality diagnosis control, the ECU 60 calculates the fuel vapor pressure P based on the following equation, which is a modified version of the above-mentioned equation (2): tv Calculate and learn.

number

[0027] [Details of abnormality diagnosis control] FIG. 3 is a flowchart illustrating the abnormality diagnosis control. The ECU 60 sets the number of repetitions n to zero (step S1), and determines whether or not the preconditions for executing the abnormality diagnosis are met (step S2). If the answer is No in step S2, the control ends. If the answer is Yes in step S2, the ECU 60 detects the tank internal pressure (P sys [0]) is acquired (step S3). Step S3 is an example of a process executed by the first acquisition unit.

[0028] Next, the ECU 60 updates the number of repetitions n to (n+1) and executes the above-described opening / closing process (step S4). Step S4 is an example of a process executed by the opening / closing control unit. At this point, the state in which the switching valve 46 is open and the isolation valve 42 and the purge valve 43 are closed is a blocked state. The ECU 60 closes the switching valve 46 (step S5) and then opens the isolation valve 42 (step S6). This establishes a communication state. Next, the ECU 60 determines whether the tank internal pressure and the canister internal pressure have stabilized based on the pressure values ​​detected by the tank internal pressure sensor 50 and the canister internal pressure sensor 51, respectively (step S7). If the answer is No in step S7, step S7 is executed again.

[0029] If the answer to step S7 is YES, the ECU 60 closes the shutoff valve 42 (step S8). Next, the ECU 60 detects the tank internal pressure (P sys [n]) is acquired (step S9). Step S9 is an example of a process executed by the second acquisition unit.

[0030] Next, the ECU 60 calculates the fuel vapor pressure based on the above-mentioned equation (3) and learns the average value of the fuel vapor pressure for n times (step S10). The ECU 60 also acquires the fuel temperature based on the fuel temperature sensor 52 and calculates the average value of the fuel temperature for n times (step S11).

[0031] Next, the ECU 60 opens the switching valve 46 (step S12). After a predetermined time has elapsed, the ECU 60 determines whether the canister pressure has stabilized near atmospheric pressure based on the canister pressure sensor 51 (step S13). If the answer is No in step S13, the ECU 60 determines that the switching valve 46 is stuck closed and diagnoses an abnormality (step S14).

[0032] If the answer to step S13 is Yes, the ECU 60 calculates the increase in the tank internal pressure (P sys [n]-P sys [0]) is greater than or equal to a threshold value (step S15). If the answer is Yes in step S15, the ECU 60 diagnoses that the fuel tank 30, the canister 31, the shut-off valve 42, and the switching valve 46 are normal (step S16). Step S16 is an example of processing executed by the diagnosis unit. Next, the ECU 60 determines that the learned value in step S10 and the average value in step S11 are normal values ​​(step S17).

[0033] If the answer is No in step S15, the ECU 60 determines whether the number of repetitions n is equal to or greater than the upper limit number (step S18). If the answer is No in step S18, step S4 is started again. The opening and closing operation is repeated in this manner. If the answer is Yes in step S18, the ECU 60 diagnoses that at least one of the fuel tank 30, the canister 31, the shutoff valve 42, and the switching valve 46 is abnormal (step S19). Specifically, it is determined that one of the following has occurred: a leak from the fuel tank 30, a leak from the canister 31, the shutoff valve 42 stuck open, the switching valve 46 stuck open, or the switching valve 46 stuck closed. Step S19 is an example of processing executed by the diagnosing unit.

[0034] As described above, the diagnosis of abnormality in the evaporated fuel treatment device 3 is carried out by the simple method of repeatedly opening and closing the shutoff valve 42 and the switching valve 46.

[0035] Although the embodiments of the present invention have been described in detail above, the present invention is not limited to such specific embodiments, and various modifications and variations are possible within the scope of the gist of the present invention as defined in the claims. [Explanation of symbols]

[0036] 1 vehicle 30 Fuel Tank 31 canister 50 Tank pressure sensor 60 ECU (abnormality diagnosis device, first acquisition unit, opening / closing control unit, second acquisition unit, diagnosis unit)

Claims

[Claim 1] an internal tank pressure sensor for detecting internal tank pressure, the internal tank pressure sensor detecting internal tank pressure, the internal tank pressure sensor detecting internal tank pressure, the internal tank pressure sensor detecting internal tank pressure, the internal tank pressure sensor detecting internal tank pressure, the internal tank pressure sensor detecting internal tank pressure, the internal tank pressure sensor detecting internal tank pressure, the internal tank pressure sensor detecting internal tank pressure, the internal tank pressure sensor detecting internal tank pressure, the internal tank pressure sensor detecting internal tank pressure, the internal tank pressure sensor detecting internal air intake passage of the engine, the internal air intake passage of the engine, the internal air intake passage of the engine, the external air intake passage of the engine, the external air intake passage of the engine, the external air intake passage of the engine, the external air intake passage of the engine, the external air intake passage of the engine, the external air intake passage of the engine, the internal tank pressure sensor detecting internal tank pressure ... a first acquisition unit that acquires the tank internal pressure in a shut-off state in which the purge valve is closed, the switching valve is open, and the isolation valve is closed; an opening / closing control unit that executes an opening / closing process that switches from the shut-off state to a communication state in which the tank internal pressure is stable by closing the switching valve and then opening the block valve, and then switches from the communication state to the shut-off state by closing the block valve and then opening the switching valve a predetermined upper limit number of times; a second acquisition unit that acquires the tank internal pressure in a state in which the block valve is closed from the communication state during the opening and closing process; an abnormality diagnosis device for an evaporated fuel treatment device, comprising: a diagnostic unit that diagnoses the fuel tank, the canister, the shut-off valve, and the switching valve as normal if the amount of increase from the tank internal pressure acquired by the first acquisition unit to the tank internal pressure acquired by the second acquisition unit becomes equal to or greater than a threshold value before the number of repeated opening and closing operations reaches the upper limit number; and diagnoses at least one of the fuel tank, the canister, the shut-off valve, and the switching valve as abnormal if the amount of increase is less than the threshold value even after the number of repeated opening and closing operations reaches the upper limit number.

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