Evaporative fuel treatment system, abnormality detection program for the evaporative fuel treatment system, and abnormality detection method for the evaporative fuel treatment system.

Abstract

To improve frequency of a determination on presence / absence of an abnormality of a purge valve.SOLUTION: An evaporation fuel treatment system includes a canister, a vapor passage, a purge passage, an outside air passage, a purge valve, a pressure sensor and a determination device. The vapor passage causes evaporation fuel generated in a fuel tank to flow to the canister. The purge passage causes the evaporation fuel to flow from the canister to an intake passage of an internal combustion engine. The outside air passage introduces outside air to the canister. The purge valve is located in the purge passage and opens / closes a flow passage of the purge passage. The pressure sensor detects pressure of a flow passage of the outside air passage. The determination device determines presence / absence of an abnormality on the purge valve. The determination device executes first determination control under the requite condition that the internal combustion engine is in operation, and executes second determination control without depending on whether or not the internal combustion engine is in operation (S61-S72).SELECTED DRAWING: Figure 5

Description

Technical Field

[0001] The present invention relates to an evaporative fuel processing system, an abnormality determination program for an evaporative fuel processing system, and an abnormality determination method for an evaporative fuel processing system.

Background Art

[0002] The evaporative fuel processing system of Patent Document 1 includes a canister, a vapor passage, a purge passage, an outside air passage, a purge valve, a pressure sensor, and a determination device. The canister adsorbs evaporative fuel. The vapor passage allows the evaporative fuel generated in the fuel tank to flow to the canister. The purge passage allows the evaporative fuel to flow from the canister to the intake passage of the internal combustion engine. The outside air passage introduces outside air into the canister. The purge valve is located in the middle of the purge passage. The purge valve opens and closes the flow path of the purge passage. The pressure sensor detects the pressure on the canister side with respect to the purge valve in the purge passage.

[0003] The determination device determines whether an abnormality of sticking in the open state has occurred with respect to the purge valve. Specifically, the determination device acquires the detection value of the pressure sensor when the internal combustion engine is not operating and satisfies a predetermined first measurement condition as a reference value. This first measurement condition is established when all various requirements such as the purge valve being controlled in the closed state are satisfied. Thereafter, the determination device acquires the detection value of the pressure sensor when the internal combustion engine is operating and satisfies a predetermined second measurement condition as a determination value. This second measurement condition is established when all various requirements such as the purge valve being controlled in the closed state and being within a predetermined period after the reference value is acquired are satisfied. Then, when the difference between the reference value and the determination value is greater than or equal to a predetermined value, the determination device determines that an abnormality of sticking in the open state has occurred with respect to the purge valve.

Prior Art Documents

Patent Documents

[0004] [Patent Document 1] Japanese Patent Publication No. 2003-113744 [Overview of the Initiative] [Problems that the invention aims to solve]

[0005] In the evaporative fuel treatment system of Patent Document 1, the determination of whether or not there is an abnormality in the purge valve is not performed unless the internal combustion engine changes from a non-operating state to an operating state, and various requirements are not met within a certain period of time after the internal combustion engine starts operating. Therefore, in the evaporative fuel treatment system of Patent Document 1, the frequency of determining whether or not there is an abnormality in the purge valve may decrease depending on the operating status of the internal combustion engine. [Means for solving the problem]

[0006] An evaporative fuel treatment system for solving the above problems comprises: a canister for adsorbing evaporative fuel; a vapor passage for circulating evaporative fuel generated in a fuel tank to the canister; a purge passage for circulating evaporative fuel from the canister to the intake passage of an internal combustion engine; an outside air passage for introducing outside air into the canister; a purge valve located in the purge passage for opening and closing the flow path of the purge passage; a pressure sensor for detecting the pressure in the flow path of the outside air passage; and a determination device for determining whether or not there is an abnormality with respect to the purge valve, wherein the determination device includes a first process of storing a first detection value which is the detection value of the pressure sensor when the purge valve is controlled to a closed state, regardless of whether or not the internal combustion engine is operating, and a previous process The following are performed after the first process: a second process to obtain a second detection value, which is the value detected by the pressure sensor when the internal combustion engine is operating and the purge valve is controlled to be in the open state; a third process to determine whether the second detection value is less than or equal to a predetermined specified value, if the third process determines that the second detection value is higher than the specified value, a fourth process to obtain a third detection value, which is the value detected by the pressure sensor when the purge valve is controlled to be in the closed state, without specifying whether the internal combustion engine is operating; and a fifth process to determine that the purge valve is abnormal, if the absolute value of the difference between the first detection value and the third detection value is less than or equal to a predetermined reference value.

[0007] The abnormality detection program for an evaporative fuel treatment system to solve the above problems is for an evaporative fuel treatment system comprising: a canister for adsorbing evaporative fuel; a vapor passage for circulating evaporative fuel generated in a fuel tank to the canister; a purge passage for circulating evaporative fuel from the canister to the intake passage of an internal combustion engine; an outside air passage for introducing outside air into the canister; a purge valve located in the purge passage for opening and closing the flow path of the purge passage; a pressure sensor for detecting the pressure in the flow path of the outside air passage; and a determination device for determining whether or not there is an abnormality with respect to the purge valve. The determination device stores a first detection value, which is the detection value of the pressure sensor when the purge valve is controlled to be in a closed state, regardless of whether or not the internal combustion engine is operating. The system is configured to perform the following steps: a first step, a second step, which, after the first step, obtains a second detection value, which is the value detected by the pressure sensor when the internal combustion engine is operating and the purge valve is controlled to be in the open state; a third step, which, after the second step, determines whether the second detection value is less than or equal to a predetermined specified value; a fourth step, which, if the third step determines that the second detection value is higher than the specified value, obtains a third detection value, which is the value detected by the pressure sensor when the purge valve is controlled to be in the closed state, regardless of whether the internal combustion engine is operating; and a fifth step, which, after the fourth step, determines that the purge valve is abnormal if the absolute value of the difference between the first detection value and the third detection value is less than or equal to a predetermined reference value.

[0008] The method for determining abnormalities in an evaporative fuel treatment system to solve the above problems is as follows: The evaporative fuel treatment system comprises a canister for adsorbing evaporative fuel, a vapor passage for circulating evaporative fuel generated in a fuel tank to the canister, a purge passage for circulating evaporative fuel from the canister to the intake passage of an internal combustion engine, an outside air passage for introducing outside air into the canister, a purge valve located in the purge passage for opening and closing the flow path of the purge passage, a pressure sensor for detecting the pressure in the flow path of the outside air passage, and a determination device for determining whether or not there is an abnormality with respect to the purge valve. The determination device stores a first detection value, which is the detection value of the pressure sensor when the purge valve is controlled to a closed state, regardless of whether or not the internal combustion engine is operating. The process involves: first, a second process which, after the first process, obtains a second detection value which is the value detected by the pressure sensor when the internal combustion engine is operating and the purge valve is controlled to be in the open state; second, a third process which, after the second process, determines whether the second detection value is less than or equal to a predetermined specified value; third, if the third process determines that the second detection value is higher than the specified value, a fourth process which, without regard to whether the internal combustion engine is operating, obtains a third detection value which is the value detected by the pressure sensor when the purge valve is controlled to be in the closed state; and fifth, after the fourth process, if the absolute value of the difference between the first detection value and the third detection value is less than or equal to a predetermined reference value, a fifth process which determines that the purge valve is abnormal. [Effects of the Invention]

[0009] With the above configuration, for example, even if the internal combustion engine continues to operate or stops operating after the third process, the first to fifth processes are executed. This improves the frequency of checking for abnormalities in the purge valve compared to a configuration that only checks for abnormalities in the purge valve when the internal combustion engine changes from an inactive state to an active state. [Brief explanation of the drawing]

[0010] [Figure 1]Figure 1 is a schematic diagram of the vehicle's configuration. [Figure 2] Figure 2 is a schematic diagram showing the pump module when the switching valve is in the OFF position. [Figure 3] Figure 3 is a schematic diagram showing the pump module when the switching valve is in the ON position. [Figure 4] Figure 4 is a flowchart showing the first decision control. [Figure 5] Figure 5 is a flowchart showing the second decision control. [Modes for carrying out the invention]

[0011] <Outline of the vehicle configuration> One embodiment of the present invention will be described below with reference to Figures 1 to 5. First, the general configuration of the vehicle 100 to which the evaporative fuel treatment system is applied will be described. In the following description, when simply referred to as upstream and downstream, they refer to the upstream and downstream in the flow direction of intake, exhaust, evaporative fuel, and outside air.

[0012] As shown in Figure 1, the vehicle 100 is equipped with an internal combustion engine E. The internal combustion engine E comprises an intake passage 11, a plurality of cylinders 12, and an exhaust passage 13. Each cylinder 12 is a space for burning the mixture of intake air and fuel. In this embodiment, the internal combustion engine E has four cylinders 12. The intake passage 11 introduces intake air from outside the internal combustion engine E into the cylinders 12. The downstream end of the intake passage 11 is connected to each cylinder 12. The intake passage 11 comprises an upstream intake passage 11A, a surge tank 11B, and a downstream intake passage 11C. The upstream intake passage 11A, the surge tank 11B, and the downstream intake passage 11C are arranged in the order described above from upstream. The surge tank 11B has the function of suppressing intake pulsation, etc. The exhaust passage 13 discharges exhaust from the cylinders 12 to the outside of the internal combustion engine E. The upstream end of the exhaust passage 13 is connected to each cylinder 12.

[0013] The internal combustion engine E comprises a throttle valve 21, a plurality of fuel injectors 22, and a fuel tank 31. The throttle valve 21 is located in the upstream intake passage 11A. The throttle valve 21 adjusts the amount of intake air flowing through the upstream intake passage 11A. The fuel injectors 22 are located near the downstream end of the downstream intake passage 11C. The fuel injectors 22 inject fuel supplied from the fuel tank 31 into the downstream intake passage 11C. In this embodiment, the internal combustion engine E has four fuel injectors 22 corresponding to four cylinders 12. The fuel tank 31 stores fuel to be supplied to the fuel injectors 22. The fuel in the fuel tank 31 is supplied to the fuel injectors 22 via fuel piping by being pumped by a feed pump (not shown).

[0014] The internal combustion engine E is equipped with an evaporative fuel treatment device 50. The evaporative fuel treatment device 50 is a device for suppressing the release of evaporated fuel generated in the fuel tank 31 to the outside of the internal combustion engine E.

[0015] The evaporative fuel treatment device 50 includes a vapor passage 51, a canister 52, an outside air passage 53, and a purge passage 55. The evaporative fuel treatment device 50 also includes a check valve 61, a purge valve 65, and a pump module 70.

[0016] The canister 52 adsorbs the evaporated fuel generated in the fuel tank 31. The first end of the vapor passage 51 is connected to the canister 52. The second end of the vapor passage 51 is located inside the fuel tank 31. In other words, the vapor passage 51 allows the evaporated fuel generated in the fuel tank 31 to flow to the canister 52. The check valve 61 is located in the middle of the vapor passage 51. The check valve 61 prevents evaporated fuel from flowing from the portion of the vapor passage 51 on the canister 52 side relative to the check valve 61 to the portion of the vapor passage 51 on the fuel tank 31 side relative to the check valve 61.

[0017] The first end of the purge passage 55 is connected to the canister 52. The second end of the purge passage 55 is connected to the surge tank 11B of the intake passage 11. That is, the purge passage 55 allows the evaporated fuel to flow from the canister 52 to the surge tank 11B of the intake passage 11. The purge valve 65 is located in the middle of the purge passage 55. The purge valve 65 opens and closes the flow path of the purge passage 55. In the present embodiment, the purge valve 65 is a normally closed solenoid valve.

[0018] The first end of the outside air passage 53 is connected to the canister 52. The second end of the outside air passage 53 communicates with the outside of the vehicle 100. That is, the outside air passage 53 introduces outside air, which is the air outside the vehicle 100, into the canister 52.

[0019] The pump module 70 is located in the middle of the outside air passage 53. The pump module 70 is a device for determining the presence or absence of gas leakage in the canister 52. Hereinafter, the portion on the canister 52 side with respect to the pump module 70 in the outside air passage 53 is referred to as the downstream outside air passage 53B, and the portion on the opposite side of the downstream outside air passage 53B with respect to the pump module 70 in the outside air passage 53 is referred to as the upstream outside air passage 53A.

[0020] As shown in FIG. 2, the pump module 70 includes a first passage 71, a second passage 72, an upstream common passage 73, a downstream common passage 74, and a bypass passage 75. The pump module 70 also includes a pump 76, a pressure sensor 77, and a switching valve 79.

[0021] The first end of the upstream common passage 73 is connected to the upstream outside air passage 53A. The second end of the upstream common passage 73 is connected to the first end of the first passage 71. The second end of the first passage 71 is connected to the switching valve 79. The first end of the downstream common passage 74 is connected to the switching valve 79. The second end of the downstream common passage 74 is connected to the downstream outside air passage 53B. The first end of the second passage 72 is connected to the connection part of the first passage 71 and the upstream common passage 73. The second end of the second passage 72 is connected to the switching valve 79. Therefore, the switching valve 79 is located at the connection part of the first passage 71, the second passage 72, and the downstream common passage 74.

[0022] The switching valve 79 is a solenoid valve for switching the communication state of the first passage 71, the second passage 72, and the downstream common passage 74. As shown in FIG. 2, when the switching valve 79 is in the OFF state, the switching valve 79 connects the first passage 71 and the downstream common passage 74. Also, when the switching valve 79 is in the OFF state, the switching valve 79 does not connect the second passage 72 and the downstream common passage 74. On the other hand, as shown in FIG. 3, when the switching valve 79 is in the ON state, the switching valve 79 connects the second passage 72 and the downstream common passage 74. Also, when the switching valve 79 is in the ON state, the switching valve 79 does not connect the first passage 71 and the downstream common passage 74.

[0023] As shown in FIG. 2, the bypass passage 75 bypasses the switching valve 79 and connects the second passage 72 and the downstream common passage 74. The middle part of the bypass passage 75 is an orifice 75A. The flow passage cross-sectional area of the orifice 75A is smaller than the flow passage cross-sectional area of the part of the bypass passage 75 other than the orifice 75A. The orifice 75A is used for determining the presence or absence of gas leakage in the above-described canister 52.

[0024] Pump 76 is located on the upstream common passage 73 side of the connection point between the second passage 72 and the bypass passage 75. When pump 76 is ON, pump 76 draws gas from the portion of the second passage 72 on the side of the switching valve 79 and discharges it to the upstream common passage 73 side of the second passage 72. Pump 76 is used for purposes such as determining whether or not there is a gas leak in the canister 52 mentioned above.

[0025] The pressure sensor 77 is located at the connection point between the second passage 72 and the bypass passage 75. The pressure sensor 77 detects the flow path pressure PR, which is the pressure in the flow path at the connection point between the second passage 72 and the bypass passage 75. As described above, the flow path in the area where the pressure sensor 77 is located is connected to the upstream outside air passage 53A via the pump 76 and the upstream shared passage 73. Furthermore, the flow path in the area where the pressure sensor 77 is located is connected to the downstream outside air passage 53B via the bypass passage 75 and the downstream shared passage 74. Therefore, the pressure sensor 77 can detect the pressure in the flow path of the outside air passage 53. In this embodiment, the pressure sensor 77 is a so-called absolute pressure sensor.

[0026] As shown in Figure 1, the vehicle 100 is equipped with a control device 90. In this embodiment, the control device 90, together with the evaporative fuel treatment device 50, constitutes an evaporative fuel treatment system. The control device 90 acquires signals indicating various values ​​from various sensors, including a pressure sensor 77. The control device 90 includes an execution unit 91 and a storage unit 92. The storage unit 92 includes a ROM that is read-only, a volatile RAM that is read and writeable, and a non-volatile storage that is read and writeable. The storage unit 92 stores information acquired by the control device 90. The storage unit 92 also pre-stores various programs and various data. The storage unit 92 pre-stores a control program 92A as one of the various programs. An example of the execution unit 91 is a CPU. The execution unit 91 realizes various processes described later by reading the control program 92A from the storage unit 92. In other words, the execution unit 91 also realizes various processes related to the abnormality determination method of the evaporative fuel treatment system by reading the control program 92A from the storage unit 92. In other words, in this embodiment, the control device 90 is an example of a determination device. Also, the control program 92A is an example of an abnormality determination program.

[0027] The execution unit 91 of the control device 90 executes a purge process when predetermined purge conditions are met. For example, the execution unit 91 of the control device 90 determines that the purge conditions are met when the internal combustion engine E is operating and the amount of evaporated fuel adsorbed inside the canister 52 is relatively large. In the purge process, the execution unit 91 controls the purge valve 65 to the open state by outputting a control signal to the purge valve 65. The execution unit 91 also controls the switching valve 79 to the OFF state by outputting a control signal to the switching valve 79. Furthermore, the execution unit 91 controls the pump 76 to the OFF state by outputting a control signal to the pump 76. As a result, in the purge process, outside air is introduced into the canister 52 via the outside air passage 53 due to the negative pressure of the surge tank 11B in the intake passage 11. Then, the evaporated fuel adsorbed inside the canister 52 and the outside air are introduced into the surge tank 11B in the intake passage 11 via the purge passage 55.

[0028] The execution unit 91 of the control device 90 stores the flow path pressure PR obtained from the pressure sensor 77 in the storage unit 92 at predetermined control cycles. The execution unit 91 performs the above processing regardless of whether the internal combustion engine E is operating or not. Here, the process of storing the flow path pressure PR in the storage unit 92 when it is before the first determination process described later and when the purge valve 65 is controlled to be in the closed state corresponds to the first process. When the purge valve 65 is controlled to be in the closed state, the negative pressure in the intake passage 11 does not reach the outside air passage 53. Therefore, when the purge valve 65 is controlled to be in the closed state, the flow path pressure PR corresponds to the atmospheric pressure at the location where the vehicle 100 is located.

[0029] <First Decision Control> Next, with reference to Figure 4, the first determination control performed by the control device 90 will be described. The first determination control is the first control related to determining whether or not an abnormality has occurred in which the purge valve 65 is stuck in the closed position. The control device 90 starts the first determination control when predetermined execution conditions are met. In this embodiment, the control device 90 starts the first determination control when the internal combustion engine E is operating, the purge process is being performed, the determination completion flag FA is OFF, and the execution flag FB is OFF. In other words, the control device 90 starts the first determination control with the necessary conditions that the internal combustion engine E is operating and the purge valve 65 is controlled to the open position. The determination completion flag FA indicates whether or not the determination of whether or not there is an abnormality related to the purge valve 65 has been completed. In this embodiment, the determination completion flag FA is OFF when the system of the vehicle 100 is started by operating a start switch (not shown). The execution flag FB is a flag for executing the second determination control, which will be described later. In this embodiment, the execution flag FB is OFF when the system of the vehicle 100 is started by operating a start switch (not shown).

[0030] As shown in Figure 4, when the execution unit 91 of the control device 90 starts the first determination control, it executes the process in step S11. In step S11, the execution unit 91 acquires the flow path pressure PR at the time of the processing in step S11 as the first determination pressure P1. As described above, the flow path pressure PR at this point is the pressure when the internal combustion engine E is operating and the purge valve 65 is controlled to be in the open state. After step S11, the execution unit 91 proceeds to step S12.

[0031] In step S12, the execution unit 91 determines whether the first determination pressure P1 is less than or equal to a predetermined first specified value A1. Here, the first specified value A1 is defined, for example, as follows. First, if the purge valve 65 is functioning normally, the purge valve 65 is controlled to be in the open state, and the switching valve 79 is controlled to be in the OFF state, then outside air is introduced into the upstream outside air passage 53A. Then, most of the outside air from the upstream outside air passage 53A is introduced into the intake passage 11 via the upstream common passage 73, the first passage 71, the switching valve 79, and the downstream common passage 74. At this time, due to the negative pressure in the intake passage 11, the pressure in the flow paths of the upstream common passage 73, the first passage 71, and the downstream common passage 74 becomes relatively low, and the flow path pressure PR detected by the pressure sensor 77 also becomes relatively low. Therefore, the first specified value A1 is set to be a value that is a certain value higher than the flow path pressure PR that should be detected by the pressure sensor 77 when the purge valve 65 is controlled to be in the open state and the switching valve 79 is controlled to be in the OFF state, and lower than standard atmospheric pressure. In this embodiment, when focusing on the processes of steps S11 and S12, the process of step S11 is the second process. The process of step S12 is the third process, which is after the second process. Furthermore, the first determination pressure P1 is the second detected value.

[0032] In step S12, if the execution unit 91 determines that the first judgment pressure P1 is higher than the first specified value A1 (S12: NO), the execution unit 91 proceeds to step S21. In step S21, the execution unit 91 controls the switching valve 79 to the ON state by outputting a control signal to the switching valve 79. After step S21, the execution unit 91 proceeds to step S22.

[0033] In step S22, the execution unit 91 acquires the flow path pressure PR at the time of processing in step S22 as the second determination pressure P2. After step S22, the execution unit 91 proceeds to step S23.

[0034] In step S23, the execution unit 91 determines whether the second determination pressure P2 is less than or equal to a predetermined second specified value A2. Here, the second specified value A2 is defined, for example, as follows. First, if the purge valve 65 is functioning normally, the purge valve 65 is controlled to be in the open state, and the switching valve 79 is controlled to be in the ON state, then outside air is introduced into the upstream outside air passage 53A. Then, most of the outside air from the upstream outside air passage 53A is introduced into the intake passage 11 via the upstream common passage 73, the second passage 72, the switching valve 79, and the downstream common passage 74. At this time, since outside air flows through the pump 76 in the second passage 72, the pressure on the side of the switching valve 79 relative to the pump 76 in the second passage 72, that is, the flow path pressure PR detected by the pressure sensor 77, becomes correspondingly lower. Therefore, the second specified value A2 is set to be a value that is a certain value higher than the flow path pressure PR that should be detected by the pressure sensor 77 when the purge valve 65 is controlled to be in the open state and the switching valve 79 is controlled to be in the ON state, and lower than standard atmospheric pressure. Note that the second specified value A2 is lower than the first specified value A1. In this embodiment, when focusing on the processing of steps S22 and S23, the processing of step S22 is the second processing. The processing of step S23 is the third processing, which is after the second processing. Furthermore, the second judgment pressure P2 is the second detected value.

[0035] In step S23, if the execution unit 91 determines that the second determination pressure P2 is less than or equal to the second specified value A2 (S23: YES), the execution unit 91 proceeds to step S31. Also, in step S12 described above, if the execution unit 91 determines that the first determination pressure P1 is less than or equal to the first specified value A1 (S12: YES), the execution unit 91 proceeds to step S31.

[0036] In step S31, the execution unit 91 determines that the purge valve 65 is functioning correctly. Next, the execution unit 91 sets the determination completion flag FA to ON. Once the determination completion flag FA is set to ON as described above, the determination completion flag FA remains ON until the vehicle 100's system stops and then restarts. After step S31, the execution unit 91 terminates this first determination control.

[0037] On the other hand, if the execution unit 91 determines in step S23 above that the second judgment pressure P2 is higher than the second specified value A2 (S23: NO), the execution unit 91 proceeds to step S41. In other words, the execution unit 91 proceeds to step S41 if the second detection value in the third process is higher than a predetermined specified value.

[0038] In step S41, the execution unit 91 sets the execution flag FB to ON. As described above, the execution flag FB is a flag for executing the second decision control described later. After step S41, the execution unit 91 terminates the current first decision control.

[0039] <Second Decision Control> Next, with reference to Figure 5, the second decision control performed by the control device 90 will be described. The second decision control is the second control related to determining whether or not an abnormality has occurred in which the purge valve 65 is stuck in the closed position. In this embodiment, the control device 90 starts the second decision control when the execution flag FB is ON. That is, the control device 90 performs the second decision control without being conditional on whether or not the internal combustion engine E is operating.

[0040] As shown in Figure 5, when the execution unit 91 of the control device 90 starts the second determination control, it executes the process in step S61. In step S61, the execution unit 91 controls the purge valve 65 to a closed state by outputting a control signal to the purge valve 65. After step S61, the execution unit 91 proceeds to step S62.

[0041] In step S62, the execution unit 91 acquires the flow path pressure PR stored in the storage unit 92 immediately before starting the first determination control, specifically, a predetermined control cycle prior to the start of the first determination control, as the starting pressure PS. In other words, the starting pressure PS is the flow path pressure PR before the second process and when the purge valve 65 is controlled to the closed state. As described above, the flow path pressure PR detected by the pressure sensor 77 when the purge valve 65 is controlled to the closed state corresponds to the atmospheric pressure at the location where the vehicle 100 is located. That is, the starting pressure PS corresponds to the atmospheric pressure at the location where the vehicle 100 is located immediately before the second process. In this embodiment, the starting pressure PS is the first detected value. After step S62, the execution unit 91 proceeds to step S63.

[0042] In step S63, the execution unit 91 acquires the flow path pressure PR at the time of processing in step S63 as the end pressure PF. In other words, the end pressure PF is the flow path pressure PR after the third processing and when the purge valve 65 is controlled to be in the closed state. As described above, the flow path pressure PR detected by the pressure sensor 77 when the purge valve 65 is controlled to be in the closed state corresponds to the atmospheric pressure at the location where the vehicle 100 is located. That is, the end pressure PF corresponds to the atmospheric pressure at the location where the vehicle 100 is located immediately after the third processing. In this embodiment, the processing in step S63 is the fourth processing. Also, the end pressure PF is the third detected value. After step S63, the execution unit 91 proceeds to step S64.

[0043] In step S64, the execution unit 91 determines whether the absolute value of the difference between the starting pressure PS and the ending pressure PF is greater than a predetermined reference value B. In other words, the execution unit 91 determines whether the atmospheric pressure at the location where the vehicle 100 is located has changed between the detection of the flow path pressure PR used as the starting pressure PS and the detection of the flow path pressure PR used as the ending pressure PF. Here, the reference value B is a threshold value used to determine whether the change in atmospheric pressure between the detection of the flow path pressure PR used as the starting pressure PS and the detection of the flow path pressure PR used as the ending pressure PF is within an acceptable range.

[0044] In step S64, if the execution unit 91 determines that the absolute value of the difference between the starting pressure PS and the ending pressure PF is greater than the reference value B (S64: YES), the execution unit 91 proceeds to step S71. In other words, the execution unit 91 proceeds to step S71 if it determines that the change in atmospheric pressure from the detection of the flow path pressure PR used as the starting pressure PS to the detection of the flow path pressure PR used as the ending pressure PF is unacceptably large.

[0045] In step S71, the execution unit 91 postpones the decision regarding the purge valve 65. Subsequently, the execution unit 91 sets the execution flag FB to OFF. After step S71, the execution unit 91 terminates the current second decision control.

[0046] On the other hand, in step S64, if the execution unit 91 determines that the absolute value of the difference between the starting pressure PS and the ending pressure PF is less than or equal to the reference value B (S64: NO), the execution unit 91 proceeds to step S72. In other words, the execution unit 91 proceeds to step S72 if it determines that the change in atmospheric pressure from the detection of the flow path pressure PR used as the starting pressure PS to the detection of the flow path pressure PR used as the ending pressure PF is small enough to be acceptable.

[0047] In step S72, the execution unit 91 determines that the purge valve 65 is abnormal. The execution unit 91 then outputs a control signal to a display (not shown) to notify the driver of the vehicle 100 that the purge valve 65 is abnormal. Subsequently, the execution unit 91 sets the determination completion flag FA to ON. In this embodiment, the processing in steps S64 and S72 constitutes the fifth process. After step S72, the execution unit 91 terminates the second determination control.

[0048] <Operation of this embodiment> Suppose that in vehicle 100, an abnormality occurs in which the purge valve 65 is stuck in the closed position. Then, suppose the control device 90 performs the first determination control. In this case, even if the purge valve 65 is controlled to the open position, the purge valve 65 remains in the closed position. As a result, the flow path pressure PR detected by the pressure sensor 77 increases due to the purge valve 65 being in the closed position, causing the first determination pressure P1 and the second determination pressure P2 to become relatively high. Consequently, the control device 90 makes a negative determination in step S12 and again in step S23. Then, in the second determination control, if the change in atmospheric pressure from the detection of the flow path pressure PR used as the starting pressure PS to the detection of the flow path pressure PR used as the ending pressure PF is small enough to be acceptable, the control device 90 makes a negative determination in step S64. As a result, in step S72, the control device 90 determines that the purge valve 65 is abnormal.

[0049] <Effects of this embodiment> (1) In this embodiment, the control device 90 executes the first determination control on the condition that the internal combustion engine E is operating, while executing the second determination control without the condition that the internal combustion engine E is operating or not. Therefore, for example, even if the operation of the internal combustion engine E continues or if the operation of the internal combustion engine E stops after the first determination control, the first and second determination controls are executed. In other words, for example, even if the operation of the internal combustion engine E continues or if the operation of the internal combustion engine E stops after the third process, the first to fifth processes are executed. This makes it possible to improve the frequency of determining whether there is an abnormality with respect to the purge valve 65 compared to a configuration in which the determination of whether there is an abnormality with respect to the purge valve 65 is made only when the situation changes from a state in which the internal combustion engine E is not operating to a state in which it is operating.

[0050] In this embodiment, if the purge valve 65 is functioning normally, the first and second determination pressures P1 and P2 will be relatively low when the internal combustion engine E is operating and the purge valve 65 is controlled to be in the open state. Here, we assume that the absolute value of the difference between the starting pressure PS and the ending pressure PF is less than or equal to the reference value B. In this situation, it is presumed that the atmospheric pressure at the location where the vehicle 100 is located has not changed significantly from the time the flow path pressure PR used as the starting pressure PS is detected until the flow path pressure PR used as the ending pressure PF is detected. Therefore, it is unlikely that the first and second determination pressures P1 and P2 have changed due to a change in atmospheric pressure. For example, in a situation where the first determination pressure P1 is determined to be higher than the first specified value A1 and the second determination pressure P2 is determined to be higher than the second specified value A2, it can be said that the first and second determination pressures P1 and P2 are relatively high. Therefore, in the above situation, it can be presumed that an abnormality has occurred in which the purge valve 65 is stuck in the closed state.

[0051] <Example of changes> This embodiment can be implemented with the following modifications. This embodiment and the following modifications can be combined with each other to the extent that they do not contradict each other technically.

[0052] • In the above embodiment, the first decision control may be modified. For example, either the processes in steps S11 and S12 or the processes in steps S21 to S23 may be omitted. As a specific example, if the processes in steps S21 to S23 are omitted, and in step S12 the execution unit 91 determines that the first determination pressure P1 is higher than the first specified value A1 (S12: NO), the execution unit 91 may proceed to step S41. Also, if the processes in steps S11 and S12 are omitted, the execution unit 91 may execute the process in step S21 when the first determination control is started.

[0053] • In the above embodiment, the configuration of the vehicle 100 may be changed. For example, the pump module 70 may be omitted. Specifically, if the only requirement is to determine whether or not an abnormality has occurred in which the purge valve 65 is stuck in the closed position, the pump module 70 can be omitted. In this case, only the pressure sensor 77 needs to be located in the outside air passage 53. [Explanation of Symbols]

[0054] E...Internal combustion engine 11...Intake passage 12...Cylinder 13...Exhaust passage 21...Throttle valve 31...Fuel tank 50...Evaporative fuel treatment device 51...Vapor passage 52...Canister 53...Outside air passage 55...Purge passage 61...Check valve 65...Purge valve 70...Pump module 71...First passage 72...Second passage 73...Upstream shared passage 74...Downstream shared passage 75...Bypass passage 76...Pump 77...Pressure sensor 79...Switching valve 90...Control device 91...Execution unit 92...Memory unit 92A...Control program 100...Vehicle

Claims

1. A canister that adsorbs evaporated fuel, A vapor passage for circulating evaporated fuel generated in the fuel tank to the canister, A purge passage for circulating evaporated fuel from the canister to the intake passage of the internal combustion engine, The canister includes an outside air passage for introducing outside air, A purge valve located in the purge passage and opening and closing the flow path of the purge passage, A pressure sensor for detecting the pressure in the flow path of the aforementioned outside air passage, A determination device for determining whether or not there is an abnormality in the purge valve, An evaporative fuel processing system comprising, The determination device is A first process that stores a first detection value, which is the detection value of the pressure sensor when the purge valve is controlled to a closed state, regardless of whether the internal combustion engine is operating or not. A second process, performed after the first process, is to acquire a second detection value, which is the detection value of the pressure sensor when the internal combustion engine is operating and the purge valve is controlled to be in the open state. A third process, performed after the second process, determines whether the second detected value is less than or equal to a predetermined value. If the third process determines that the second detection value is higher than the specified value, a fourth process is performed to obtain a third detection value, which is the detection value of the pressure sensor when the purge valve is controlled to a closed state, without specifying whether or not the internal combustion engine is operating. A fifth process, performed after the fourth process, determines that the purge valve is abnormal if the absolute value of the difference between the first detected value and the third detected value is less than or equal to a predetermined reference value. Execute Evaporative fuel processing system.

2. A canister that adsorbs evaporated fuel, A vapor passage for circulating evaporated fuel generated in the fuel tank to the canister, A purge passage for circulating evaporated fuel from the canister to the intake passage of the internal combustion engine, The canister includes an outside air passage for introducing outside air, A purge valve located in the purge passage and opening and closing the flow path of the purge passage, A pressure sensor for detecting the pressure in the flow path of the aforementioned outside air passage, A determination device for determining whether or not there is an abnormality in the purge valve, This applies to evaporation fuel processing systems equipped with the following features: The determination device, A first process that stores a first detection value, which is the detection value of the pressure sensor when the purge valve is controlled to a closed state, regardless of whether the internal combustion engine is operating or not. A second process, performed after the first process, is to acquire a second detection value, which is the detection value of the pressure sensor when the internal combustion engine is operating and the purge valve is controlled to be in the open state. A third process, performed after the second process, determines whether the second detected value is less than or equal to a predetermined value. If the third process determines that the second detection value is higher than the specified value, a fourth process is performed to obtain a third detection value, which is the detection value of the pressure sensor when the purge valve is controlled to a closed state, without specifying whether or not the internal combustion engine is operating. A fifth process, performed after the fourth process, determines that the purge valve is abnormal if the absolute value of the difference between the first detected value and the third detected value is less than or equal to a predetermined reference value. Make it run An anomaly detection program for the evaporative fuel processing system.

3. A canister that adsorbs evaporated fuel, A vapor passage for circulating evaporated fuel generated in the fuel tank to the canister, A purge passage for circulating evaporated fuel from the canister to the intake passage of the internal combustion engine, The canister includes an outside air passage for introducing outside air, A purge valve located in the purge passage and opening and closing the flow path of the purge passage, A pressure sensor for detecting the pressure in the flow path of the aforementioned outside air passage, A determination device for determining whether or not there is an abnormality in the purge valve, This applies to evaporation fuel processing systems equipped with the following features: The determination device, A first process that stores a first detection value, which is the detection value of the pressure sensor when the purge valve is controlled to a closed state, regardless of whether the internal combustion engine is operating or not. A second process, performed after the first process, is to acquire a second detection value, which is the detection value of the pressure sensor when the internal combustion engine is operating and the purge valve is controlled to be in the open state. A third process, performed after the second process, determines whether the second detected value is less than or equal to a predetermined value. If the third process determines that the second detection value is higher than the specified value, a fourth process is performed to obtain a third detection value, which is the detection value of the pressure sensor when the purge valve is controlled to a closed state, without specifying whether or not the internal combustion engine is operating. A fifth process, performed after the fourth process, determines that the purge valve is abnormal if the absolute value of the difference between the first detected value and the third detected value is less than or equal to a predetermined reference value. Execute A method for detecting abnormalities in an evaporated fuel processing system.

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