Exhaust system state determination method and exhaust system state determination device

Abstract

A control unit (9) determines whether or not freezing occurs in an inlet-side pressure introduction pipe (10) or an outlet-side pressure introduction pipe (11), which is a path through which pressure is introduced into a differential pressure sensor (8), in the differential pressure sensor (8) that detects pressure loss of a GPF (5). If it is determined that freezing has occurred, the control means (9) sets the count value of the freezing release counter to a predetermined initial value, increases or decreases the count value of the freezing release counter with respect to the initial value on the basis of the operating state of the internal combustion engine (2), and if the count value of the freezing release counter reaches a predetermined freezing determination release threshold value, the control means (9) determines that freezing has occurred. If so, it is determined that the freezing occurring in the differential pressure sensor (8), the inlet-side pressure introduction pipe (10), or the outlet-side pressure introduction pipe (11) has ablated. The count value of the freeze release counter decreases during the temporary stop of the internal combustion engine (2) and increases during the operation of the internal combustion engine (2).

Description

Technical Field

[0001] The present invention relates to a method for determining a state of an exhaust system and a device for determining a state of an exhaust system. Background Art

[0002] For example, Patent Document 1 discloses a differential pressure sensor that detects a pressure loss of a gasoline particulate filter provided in an exhaust pipe that introduces exhaust gas from an internal combustion engine.

[0003] In Patent Document 1, with respect to at least one of the upstream piping that transmits the pressure on the upstream side (inlet side) of the gasoline particulate filter to the upstream piping of the differential pressure sensor and the downstream piping that transmits the pressure on the downstream side (outlet side) of the gasoline particulate filter to the downstream piping of the differential pressure sensor, it is determined whether a freezing state (frozen state) in which water freezes inside and can block the pipe occurs.

[0004] In Patent Document 1, when the outside temperature is lower than a preset first threshold value when the ignition switch is turned on, or when the water temperature is lower than a preset second threshold value when the ignition switch is turned on, it is determined that at least one of the upstream piping and the downstream piping is in a frozen state.

[0005] However, Patent Document 1 does not consider refreezing after the frozen state is resolved during driving of the vehicle.

[0006] Therefore, in Patent Document 1, if the frozen state is temporarily determined, it is difficult to determine the frozen state again when the frozen state is eliminated. That is, Patent Document 1 does not envision the situation where the frozen state becomes frozen again after the frozen state is eliminated, and there is room for further improvement in the aspect of accurately determining the frozen state.

[0007] Patent Document 1: Japanese Patent Application Publication No. 2020-143595 Summary of the invention

[0008] The exhaust system of the present invention determines whether ice has occurred in a differential pressure sensor that detects the pressure loss of an exhaust particulate filter provided in an exhaust passage of the internal combustion engine or in a path that introduces pressure to the differential pressure sensor based on the stopped state of the internal combustion engine mounted on the vehicle, and if it is determined that ice has occurred, the count value of a predetermined release counter is set to a predetermined initial value, and the count value of the release counter is increased or decreased relative to the initial value based on the operating state of the internal combustion engine, and if the count value of the release counter reaches a predetermined threshold value, it is determined that the ice generated in the differential pressure sensor or in the path that introduces pressure to the differential pressure sensor has melted. In addition, during driving of the vehicle determined to have frozen, the direction of increase or decrease of the count value of the release counter is opposite when the internal combustion engine is temporarily stopped and when it is operating.

[0009] According to the present invention, the melting of ice generated in the differential pressure sensor and the path for introducing pressure to the differential pressure sensor can be determined with high accuracy during driving of the vehicle. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Figure 1 It is an explanatory diagram schematically showing the outline of an exhaust system to which the present invention is applied.

[0011] Figure 2 This is a timing chart showing the situation of freezing determination.

[0012] Figure 3 This is a flowchart showing the flow of freezing determination. DETAILED DESCRIPTION

[0013] Hereinafter, one embodiment of the present invention will be described in detail based on the drawings. Figure 1 It is an explanatory diagram schematically showing the outline of an exhaust system 1 to which the present invention is applied.

[0014] The exhaust system 1 is mounted on a vehicle and includes an internal combustion engine 2, an exhaust passage 3, a manifold catalyst 4, a GPF 5 (Gasoline Particulate Filter), an underfloor catalyst 6, a muffler 7, a differential pressure sensor 8 for detecting a pressure loss in the GPF 5, and a control unit 9 capable of performing a freezing diagnosis described later.

[0015] The internal combustion engine 2 is a spark ignition type internal combustion engine that uses gasoline as fuel, and is mounted on a vehicle such as an automobile.

[0016] Here, the vehicle equipped with the internal combustion engine 2 is specifically an idle stop vehicle capable of idling stop based on the idle stop control or a hybrid vehicle capable of EV driving in which the internal combustion engine 2 is stopped. That is, the vehicle equipped with the internal combustion engine 2 is a vehicle capable of temporarily stopping the internal combustion engine 2 during driving of the vehicle.

[0017] The idle stop control, for example, stops fuel supply to automatically stop the internal combustion engine 2 if a predetermined automatic stop condition is satisfied, and restarts fuel supply to restart the internal combustion engine 2 if a predetermined automatic restart condition is satisfied during the automatic stop.

[0018] The predetermined automatic stop condition includes, for example, the vehicle speed being less than or equal to a predetermined value, the accelerator opening being less than or equal to a predetermined value, etc. The predetermined automatic restart condition includes, for example, the accelerator opening being greater than a predetermined value, the brake pedal not being depressed, etc.

[0019] A hybrid vehicle is a structure that can achieve EV driving by using only a driving motor (not shown) as a driving source to drive the drive wheels. It can also be a so-called series hybrid vehicle that does not use an internal combustion engine 2 as the power of the vehicle, or a so-called parallel hybrid vehicle that can use an internal combustion engine 2 as the power of the vehicle.

[0020] The manifold catalyst 4 purifies exhaust gas and is composed of, for example, a three-way catalyst. The manifold catalyst 4 is arranged close to a combustion chamber (not shown) of the internal combustion engine 2, for example, just downstream of a converging portion of an exhaust manifold (not shown).

[0021] The GPF 5 and the underfloor catalyst 6 are disposed under the floor of the vehicle interior space separated from the combustion chamber (not shown) of the internal combustion engine 2. That is, the GPF 5 and the underfloor catalyst 6 are disposed separated from the engine room of the vehicle.

[0022] The GPF 5 corresponds to an exhaust particulate filter and collects PM, which is exhaust particulate matter in the exhaust gas. The GPF 5 is arranged on the downstream side of the manifold catalyst 4 .

[0023] The underfloor catalyst 6 purifies exhaust gas and is composed of, for example, a three-way catalyst. The underfloor catalyst 6 is disposed adjacent to the GPF 5 on the downstream side of the GPF 5 .

[0024] The muffler 7 reduces exhaust noise and is disposed on the downstream side of the underfloor catalyst 6 .

[0025] The differential pressure sensor 8 can detect the pressure difference between the exhaust pressure at the inlet of the GPF 5 and the exhaust pressure at the outlet of the GPF 5. The exhaust pressure at the inlet of the GPF 5 is introduced into the differential pressure sensor 8 via the inlet side pressure introduction pipe 10. The exhaust pressure at the outlet of the GPF 5 is introduced into the differential pressure sensor 8 via the outlet side pressure introduction pipe 11. The inlet side pressure introduction pipe 10 and the outlet side pressure introduction pipe 11 correspond to the path for introducing the pressure into the differential pressure sensor 8.

[0026] The control unit 9 is a well-known electronic computer having a CPU, a ROM, a RAM, and an input / output interface. Detection signals (output signals) of various sensors such as the differential pressure sensor 8, the crank angle sensor 12, and a sensor capable of detecting the air-fuel ratio of the internal combustion engine 2 are input to the control unit 9. The crank angle sensor 12 detects the crank angle of the crankshaft of the internal combustion engine 2 and can detect the engine speed of the internal combustion engine 2.

[0027] The control unit 9 can calculate the accumulation amount of exhaust particulates trapped by the GPF 5. Specifically, the control unit 9 compares the first accumulation amount calculated using the output signal of the differential pressure sensor 8 and the second accumulation amount calculated based on the operating state of the internal combustion engine 2, and sets the larger value as the accumulation amount of exhaust particulates accumulated on the GPF 5. Here, the first accumulation amount is the accumulation amount calculated based on the pressure loss of the GPF 5. The second accumulation amount is, for example, the accumulation amount calculated based on a physical model using the air-fuel ratio of the internal combustion engine 2, the history of the internal combustion engine speed, etc.

[0028] In addition, the control unit 9 can control the internal combustion engine 2 and perform various diagnoses.

[0029] The exhaust gas (combusted gas) flowing in the exhaust passage 3 contains moisture. Therefore, the differential pressure sensor 8, the inlet pressure introduction pipe 10, and the outlet pressure introduction pipe 11 are in an environment where moisture exists. Therefore, in an extremely low temperature state where the outside temperature is below freezing, the differential pressure sensor 8, the inlet pressure introduction pipe 10, and the outlet pressure introduction pipe 11, which are the paths for introducing pressure into the differential pressure sensor 8, may freeze. For example, if any one of the differential pressure sensor 8, the inlet pressure introduction pipe 10, and the outlet pressure introduction pipe 11 freezes, even if the differential pressure sensor 8 does not fail, the output signal from the differential pressure sensor 8 may not become the value indicating the differential pressure at that time, and various controls and various diagnoses using the output signal of the differential pressure sensor 8 may cause malfunctions. That is, if the differential pressure sensor 8 and the path for introducing pressure into the differential pressure sensor 8 freeze, even if the differential pressure sensor 8 does not fail, the output signal from the differential pressure sensor 8 may deviate from the original value (true value) that should be output at that time, and various controls and various diagnoses using the output signal of the differential pressure sensor 8 may cause malfunctions.

[0030] If freezing of the differential pressure sensor 8 and the path for introducing pressure to the differential pressure sensor 8 can be determined with high accuracy, malfunctions and misdiagnosis of various controls and diagnoses using the output signal of the differential pressure sensor 8 can be suppressed.

[0031] As various controls using the output signal of the differential pressure sensor 8, there is, for example, a GPF 5 regeneration control based on the amount of exhaust particulate matter deposited in the GPF 5. The output signal of the GPF 5 becomes a value deviated from the true value due to freezing. For example, if the first accumulation amount is calculated as a value greater than the actual value, the GPF 5 regeneration control may not be properly performed, resulting in the deterioration of the GPF 5.

[0032] As various diagnoses using the output signal of the differential pressure sensor 8, for example, there are diagnoses of faults of the differential pressure sensor 8 itself and diagnoses of whether the GPF 5 is installed in the exhaust passage 3 or removed from the exhaust passage 3. If the output signal of the GPF 5 becomes a value deviating from the true value due to freezing, it is possible that the fault diagnosis mistakenly determines that the GPF 5 is faulty. In addition, if the output signal of the GPF 5 becomes a value deviating from the true value due to freezing, it is possible that the GPF 5 is determined to be removed from the exhaust passage 3 even when the GPF 5 is installed in the exhaust passage 3.

[0033] Therefore, in the present invention, freezing judgment of the differential pressure sensor 8 and the path for introducing pressure into the differential pressure sensor 8 is performed with high precision, so that when the output of the differential pressure sensor 8 is abnormal due to freezing, various controls and diagnoses using the output signal of the differential pressure sensor 8 are stopped, thereby avoiding malfunction and misdiagnosis.

[0034] The freezing determination is performed by the control unit 9 as a determination unit. The control unit 9 determines whether freezing occurs in any one of the pressure difference sensor 8, the inlet-side pressure introduction pipe 10, and the outlet-side pressure introduction pipe 11, for example, based on the stop state of the internal combustion engine 2 mounted on the vehicle. That is, the control unit 9 determines whether freezing occurs in the pressure difference sensor 8 or the path for introducing pressure into the pressure difference sensor 8. Specifically, when the internal combustion engine 2 is temporarily stopped for a time greater than or equal to a specified time, and the outside temperature during this period is less than or equal to a specified temperature, it is determined that any one of the pressure difference sensor 8, the inlet-side pressure introduction pipe 10, and the outlet-side pressure introduction pipe 11 is frozen. The above-mentioned specified temperature is, for example, 0°C.

[0035] The outside air temperature can be estimated based on, for example, a detection signal of an air flow meter (not shown). Alternatively, a temperature sensor for detecting the outside air temperature may be separately provided and the outside air temperature may be obtained from the temperature sensor.

[0036] Furthermore, when the outside temperature is equal to or lower than the predetermined temperature when the vehicle is started by key-on, it is determined that ice has occurred in the differential pressure sensor 8 and the path for introducing pressure to the differential pressure sensor 8 .

[0037] If any one of the differential pressure sensor 8, the inlet pressure introduction pipe 10, and the outlet pressure introduction pipe 11 is frozen, the control unit 9 determines that the output signal of the differential pressure sensor 8 deviates from the true value and stops various controls and various diagnoses using the output signal of the differential pressure sensor 8.

[0038] If it is determined through the freezing determination that freezing has occurred, the control unit 9 sets the count value of the freezing release counter, which is a prescribed release counter, to a prescribed initial value. The freezing release counter is equivalent to an indicator of the total amount of heat conducted from the internal combustion engine 2 to the GPF 5. Moreover, the control unit 9 increases or decreases the count value of the freezing release counter relative to the initial value based on the operating state (operating / temporarily stopped state) of the internal combustion engine 2. If the count value of the freezing release counter reaches a prescribed freezing release threshold, the control unit 9 determines that the freezing generated in the differential pressure sensor 8 or the path for introducing pressure into the differential pressure sensor 8 has melted. That is, if the count value of the freezing release counter reaches a prescribed freezing release threshold, the control unit 9 determines that no freezing has occurred in the differential pressure sensor 8, the inlet side pressure introduction pipe 10, and the outlet side pressure introduction pipe 11.

[0039] Here, the initial value of the count value of the defreezing counter is a value that is smaller than the defreezing threshold value by a predetermined amount. That is, the initial value of the count value of the defreezing counter is set to be a constant difference value relative to the defreezing threshold value. Further, the initial value of the count value of the defreezing counter is set, for example, in a range greater than or equal to 0 (zero) and less than the defreezing threshold value.

[0040] The freezing release threshold is set so as not to become 0 (zero) even if the above-mentioned predetermined amount is subtracted.

[0041] The count value of the ice-removal counter is set so that, during the driving of the vehicle determined to be iced, the count value decreases when the internal combustion engine 2 is temporarily stopped (when the internal combustion engine speed is 0 rpm), and increases when the internal combustion engine 2 is running (when the internal combustion engine speed is not 0 rpm). In other words, the count value of the ice-removal counter is set so that, during the driving of the vehicle determined to be iced, the direction of increase and decrease is opposite when the internal combustion engine 2 is temporarily stopped and when it is running.

[0042] In addition, the count value of the defrost counter will not be less than 0 (zero).

[0043] When it is determined that no freezing has occurred in the differential pressure sensor 8, the inlet side pressure introduction pipe 10 and the outlet side pressure introduction pipe 11, the control unit 9 determines that the output signal of the differential pressure sensor 8 is a true value and restarts various controls and various diagnoses using the output signal of the differential pressure sensor 8.

[0044] With the exhaust system 1 of this embodiment, the melting of ice generated in the differential pressure sensor 8 and the path for introducing pressure to the differential pressure sensor 8 can be determined with high accuracy during driving of the vehicle.

[0045] Figure 2This is a time chart showing an example of a situation of freezing determination when the outside air temperature is constant at a temperature lower than or equal to the above-mentioned predetermined temperature.

[0046] Time t1 is the timing at which the internal combustion engine 2 starts operating in a state where the initial count value of the defrosting counter is 0 (zero).

[0047] The time t2 is the timing at which the count value of the defrosting counter starts to increase (increment) from the initial value. The count value of the defrosting counter starts to increase from the time t2. In the region where the internal combustion engine speed of the internal combustion engine 2 is relatively low, the intake air volume is relatively small, and the exhaust volume is relatively small, so sufficient heat cannot be supplied to the exhaust system 1. Therefore, after the internal combustion engine 2 restarts operation, until the time t2 when the internal combustion engine speed reaches the predetermined speed, the count value of the defrosting counter is not increased or decreased, but is maintained at the initial value (current value).

[0048] Thus, the exhaust system 1 can determine the melting of ice with higher accuracy.

[0049] Time t3 is the timing when the engine speed reaches a predetermined target speed.

[0050] Time t4 is the timing when the count value of the freezing release counter reaches the freezing release threshold value and is the timing when it is determined that freezing has not occurred by the freezing determination.

[0051] Time t5 is a timing when the engine speed of the internal combustion engine 2 is “0” (zero) and the internal combustion engine 2 is stopped while the vehicle is being driven.

[0052] Time t6 is the timing when freezing is determined by freezing determination. Time t6 is the timing when the predetermined time has passed relative to the timing when the internal combustion engine 2 is stopped. The predetermined time is set, for example, according to the outside temperature and can be set to be shorter as the outside temperature is lower.

[0053] Specifically, the control unit 9 has a timer for measuring the time when the internal combustion engine 2 is temporarily stopped, and the count value of the timer starts to increase (increase) from the timing of time t5, and the timing when the count value of the timer reaches the predetermined refreezing threshold value corresponding to the above-mentioned predetermined time is time t6. In addition, the refreezing threshold value is changed according to the outside temperature, and can be set to be smaller as the outside temperature is lower.

[0054] Furthermore, at time t6, the count value of the defrosting counter is set to an initial value.

[0055] Time t7 is the timing when the count value of the defrosting counter decreases to 0 (zero) due to the continuous temporary stop of the internal combustion engine 2. That is, during the period from time t6 to time t7, the internal combustion engine 2 is stopped, so the count value of the defrosting counter decreases (decreases) from the initial value and gradually decreases.

[0056] Time t8 is the timing at which the internal combustion engine 2 starts operating.

[0057] Figure 3 1 is a flowchart showing the flow of freezing determination of the exhaust system 1 according to the above-mentioned embodiment.

[0058] In step S1, it is determined whether or not it is determined that the differential pressure sensor 8 or any one of the paths for introducing pressure into the differential pressure sensor 8 is frozen. That is, in step S1, it is determined whether or not it is determined that the differential pressure sensor 8 or any one of the paths for introducing pressure into the differential pressure sensor 8 is frozen. If it is determined in step S1 that it is frozen, the process proceeds to step S4. If it is not determined in step S1 that it is frozen, the process proceeds to step S2.

[0059] In step S2, it is determined whether freezing has occurred in the differential pressure sensor 8 or in the path for introducing pressure into the differential pressure sensor 8. That is, in step S2, it is determined whether refreezing has occurred in the differential pressure sensor 8 or in the path for introducing pressure into the differential pressure sensor 8. If it is determined in step S2 that refreezing has occurred, the process proceeds to step S3. If it is determined in step S2 that no refreezing has occurred, the process ends.

[0060] In step S3, an initial value is set for the count value of the defrosting counter.

[0061] In step S4, it is determined whether the internal combustion engine 2 is in operation (rotating). If it is determined in step S4 that the internal combustion engine 2 is in operation (rotating), the process proceeds to step S5. If it is determined in step S4 that the internal combustion engine 2 is stopped (the engine speed is zero), the process proceeds to step S8.

[0062] In step S5, the count value of the defrosting counter is incremented.

[0063] In step S6, it is determined whether the count value of the defreezing counter has reached the defreezing threshold value. If it is determined in step S6 that the count value of the defreezing counter has reached the defreezing threshold value, the process proceeds to step S7. If it is determined in step S6 that the count value of the defreezing counter has not reached the defreezing threshold value, the process ends.

[0064] In step S7, it is determined that the differential pressure sensor 8 and the path for introducing pressure to the differential pressure sensor 8 have been freed from ice (melted). That is, in step S7, it is determined that the differential pressure sensor 8 and the path for introducing pressure to the differential pressure sensor 8 have been freed from ice.

[0065] In step S8, the count value of the defrosting counter is decremented to terminate the current flow.

[0066] Although specific embodiments of the present invention have been described above, the present invention is not limited to the above embodiments, and various modifications can be made within the scope of the present invention.

[0067] For example, the internal combustion engine 2 may be a diesel internal combustion engine. In addition, the exhaust particulate filter is not limited to the GPF 5, and may be, for example, a DPF (Diesel Particulate Filter).

[0068] In the above embodiment, the heat supplied to GPF5 is set as a positive value and the heat released from GPF5 is set as a negative value to set the defrost counter, but the heat supplied to GPF5 may be set as a negative value and the heat released from GPF5 may be set as a positive value to set the defrost counter.

[0069] In addition, even if the internal combustion engine 2 is in operation, during the fuel cutoff in which the fuel supply to the internal combustion engine 2 is stopped, and the vehicle speed is greater than or equal to the prescribed speed, the defrosting counter may not increase or decrease the count value, but maintain the current value. For example, if the heat supplied to the GPF 5 is set to a positive value and the defrosting counter is set, even if the internal combustion engine 2 is in operation, during the fuel cutoff in which the fuel supply to the internal combustion engine 2 is stopped, and the vehicle speed is greater than or equal to the prescribed speed, the count value of the defrosting counter may not be increased, but maintained at the current value.

[0070] Thus, the exhaust system 1 can determine the melting of ice with higher accuracy.

[0071] When the target application area of ​​the vehicle equipped with the exhaust system 1 of the present invention is not an extremely cold area, the defrosting counter may not increase or decrease the count value during the temporary stop of the internal combustion engine 2, but may be kept at the current value. For example, if the heat supplied to the GPF 5 is set to a positive value and the defrosting counter is set, when the target application area of ​​the vehicle equipped with the exhaust system 1 of the present invention is not an extremely cold area, the defrosting counter may not decrease the count value during the temporary stop of the internal combustion engine 2, but may be kept at the current value.

[0072] When the target application area is not an extremely cold area, if the freezing is eliminated by starting the internal combustion engine 2, it can be considered that the freezing will not progress even if the internal combustion engine 2 is temporarily stopped thereafter.

[0073] Thus, the exhaust system 1 can determine the melting of ice with higher accuracy.

[0074] The initial value of the count value of the de-icing counter is such that the shorter the temporary stop time of the internal combustion engine 2 during the period when the freezing is determined to occur, the closer it is to the de-icing threshold. For example, if the heat supplied to the GPF 5 is set as a positive value and the de-icing counter is set, the initial value of the count value of the de-icing counter is such that the shorter the temporary stop time of the internal combustion engine 2 during the period when the freezing is determined to occur, the larger the value is.

[0075] Thus, the exhaust system 1 can determine the melting of ice with higher accuracy.

[0076] In addition, if it is determined that the temporary stop time of the internal combustion engine 2 during the period of freezing is longer than the prescribed time, the initial value of the count value of the freezing release counter can be set to a value farthest from the freezing release threshold value (for example, "0"). In other words, if it is determined that the temporary stop time of the internal combustion engine 2 during the period of freezing is longer than the prescribed time, the initial value of the count value of the freezing release counter can be set to a value farthest from the freezing release threshold value.

[0077] When the temporary stop time of the internal combustion engine 2 is long, for example, when the ignition key is turned off at night to stop the internal combustion engine 2 and the ignition key is turned on the next morning to start the internal combustion engine 2, there is no need to correct the initial value of the defreezing counter.

[0078] Thereby, the exhaust system 1 can set the initial value of the defrosting counter to a value suitable for actual use.

[0079] In addition, the freezing release threshold value may be set according to the outside temperature. Specifically, the freezing release threshold value may be set to be smaller as the outside temperature is higher, for example.

[0080] The above-mentioned embodiments relate to a method for determining a state of the exhaust system 1 and a device for determining a state of the exhaust system 1 .

Claims

1. A method for determining the state of an exhaust system, wherein: Based on a stopped state of an internal combustion engine mounted on a vehicle, it is determined whether freezing occurs in a differential pressure sensor that detects a pressure loss of an exhaust particulate filter provided in an exhaust passage of the internal combustion engine or in a path that introduces pressure to the differential pressure sensor, If it is determined that ice has occurred, the count value of a predetermined release counter is set to a predetermined initial value, and the count value of the release counter is increased or decreased relative to the initial value based on the operating state of the internal combustion engine. If the count value of the release counter reaches a predetermined threshold value, it is determined that the ice generated in the differential pressure sensor or in a path for introducing pressure into the differential pressure sensor has melted. During driving of the vehicle determined to have frozen, the count value of the release counter increases and decreases in the opposite directions when the internal combustion engine is temporarily stopped and when it is operating.

2. The exhaust system state determination method according to claim 1, wherein: When the internal combustion engine is temporarily stopped for a time period greater than or equal to a predetermined time during driving of the vehicle and the outside temperature is less than or equal to a predetermined temperature, it is determined that ice has occurred in the differential pressure sensor or a path for introducing pressure to the differential pressure sensor.

3. The exhaust system state determination method according to claim 1 or 2, wherein: Even if the above-mentioned internal combustion engine is in operation, in any of the following situations: the intake air amount is less than or equal to the specified value, the fuel supply to the above-mentioned internal combustion engine has been stopped, or the vehicle speed is greater than or equal to the specified speed, the count value of the above-mentioned release counter does not increase or decrease, but remains at the current value.

4. The exhaust system state determination method according to claim 1 or 2, wherein: If the target application area of ​​the above-mentioned vehicles is not an extremely cold area, During the temporary stop of the internal combustion engine, the count value of the release counter is not increased or decreased but is maintained at the current value.

5. The exhaust system state determination method according to claim 1 or 2, wherein: The initial value of the count value of the release counter is a value that is closer to the predetermined threshold value as the temporary stop time of the internal combustion engine during the period determined to have frozen is shorter.

6. The exhaust system state determination method according to claim 1 or 2, wherein: If the temporary stop time of the internal combustion engine during the period in which it is determined that freezing has occurred is longer than a predetermined time, the initial value of the count value of the release counter is set to a value farthest from the predetermined threshold value.

7. The exhaust system state determination method according to claim 1 or 2, wherein: The temporary stop of the internal combustion engine is referred to as idling stop.

8. The exhaust system state determination method according to claim 1 or 2, wherein: The vehicle is a hybrid vehicle capable of autonomous EV driving with the internal combustion engine stopped. The temporary stop of the internal combustion engine is performed during EV driving.

9. A device for determining the state of an exhaust system, wherein: The exhaust system state determination device comprises: An exhaust particulate filter provided in an exhaust passage of an internal combustion engine mounted on a vehicle; a differential pressure sensor for detecting a pressure loss of the exhaust particulate filter; and a determination unit that determines whether ice has occurred in the differential pressure sensor or in a path for introducing pressure into the differential pressure sensor based on the stopped state of the internal combustion engine, sets a count value of a predetermined release counter to a predetermined initial value if it is determined that ice has occurred, increases or decreases the count value of the release counter relative to the initial value based on the operating state of the internal combustion engine, and determines that ice generated in the differential pressure sensor or in a path for introducing pressure into the differential pressure sensor has melted if the count value of the release counter reaches a predetermined threshold value, During driving of the vehicle determined to have frozen, the count value of the release counter increases and decreases in the opposite directions when the internal combustion engine is temporarily stopped and when it is operating.

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