Fault determination device, fault determination method, and program

Abstract

To widen the range of engine loads in which the presence or absence of an abnormality in a purification device can be determined. [Solution] The failure determination device 60 has an identification unit 623 that identifies the load state of the engine 10, a detection unit 622 that detects a differential pressure, which is the difference in exhaust pressure upstream and downstream of a purification device 30 provided in the exhaust path 13, and a determination unit 624 that determines that there is an abnormality in the purification device 30 when the difference between a first differential pressure detected by the detection unit 622 when the load of the engine 10 is in a first state or higher and a second differential pressure detected by the detection unit 622 when the load of the engine 10 is in a second state lower than the first state is less than a threshold value.

Description

[Technical field]

[0001] The present invention relates to a failure determination device, a failure determination method, and a program. [Background technology]

[0002] The hybrid vehicle described in Patent Document 1 determines that there is an abnormality in a purification device provided in an exhaust passage when the differential pressure between the exhaust pressure upstream of the purification device and the exhaust pressure downstream of the purification device is less than a predetermined differential pressure. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2017-105354 A Summary of the Invention [Problem to be solved by the invention]

[0004] The differential pressure between the exhaust pressures upstream and downstream of the purification device includes errors (so-called variations) for each sensor that detects the exhaust pressure and errors caused by the deterioration of each sensor. Therefore, in conventional hybrid vehicles, it is desirable to reduce the proportion of errors contained in the differential pressure in order to improve the accuracy of detecting an abnormality in the purification device. In order to reduce the proportion of errors contained in the differential pressure, it is possible to increase the load on the engine (so-called high load state) to increase the differential pressure, but this creates a problem in that the engine load state is limited when determining whether or not there is an abnormality in the purification device.

[0005] The present invention has been made in consideration of these points, and has an object to widen the range of engine loads in which the presence or absence of an abnormality in a purification device can be determined. [Means for solving the problem]

[0006] A failure determination device according to a first aspect of the present invention includes an identification unit that identifies the load state of an engine, a detection unit that detects a differential pressure, which is the difference between the exhaust pressures upstream and downstream of a purification device provided in an exhaust flow path, and a determination unit that determines that there is an abnormality in the purification device when the difference between a first differential pressure detected by the detection unit when the load of the engine is at or above a first state and a second differential pressure detected by the detection unit when the load of the engine is at a second state lower than the first state, is less than a threshold value.

[0007] The identification unit may identify the first state of the load on the engine when a vehicle equipped with the engine is traveling on a road other than an expressway, and the second state of the load on the engine when the vehicle is idling.

[0008] The determination unit may determine a load of the engine based on at least two of a rotation speed, a torque, an exhaust gas flow rate, and a fuel injection amount of the engine.

[0009] The specifying unit may specify a load of the engine corresponding to a rotation speed of the engine and a torque or a fuel injection amount of the engine.

[0010] The detection unit may detect a differential pressure between a first exhaust pressure detected by a first sensor provided upstream of the purification device and a second exhaust pressure detected by a second sensor provided downstream of the purification device.

[0011] The determination unit may determine whether or not there is an abnormality in the purification device when a sum of the first differential pressures detected at each time when the engine load is equal to or greater than the first state is equal to or greater than a first sum value, and a sum of the second differential pressures detected at each time when the engine load is in the second state is equal to or greater than a second sum value that is smaller than the first sum value.

[0012] The determination unit may determine that an abnormality exists in the purification device when a difference between a statistical amount of the plurality of first differential pressures and a statistical amount of the plurality of second differential pressures is less than the threshold value.

[0013] The determination unit may determine whether or not there is an abnormality in the purification device after a predetermined time has elapsed from the time when the process of burning the particulate matter trapped by the purification device is completed.

[0014] A failure determination method according to a second aspect of the present invention includes an identification step executed by a processor to identify the load state of an engine; a detection step to detect a differential pressure, which is the difference between the exhaust pressures upstream and downstream of a purification device provided in an exhaust flow path; and a determination step to determine that there is an abnormality in the purification device if the difference between a first differential pressure detected in the detection step when the load of the engine is equal to or higher than a first state and a second differential pressure detected in the detection step when the load of the engine is in a second state lower than the first state is less than a threshold value.

[0015] A program according to a third aspect of the present invention causes a processor to execute the steps of identifying an engine load state; detecting a differential pressure, which is the difference between the exhaust pressures upstream and downstream of a purification device provided in an exhaust flow path; and determining that there is an abnormality in the purification device if the difference between a first differential pressure detected in the step of detecting the differential pressure when the engine load is in a first state or higher and a second differential pressure detected in the step of detecting the differential pressure when the engine load is in a second state lower than the first state, is less than a threshold value. Effect of the Invention

[0016] The present invention has the effect of widening the range of engine loads in which it is possible to determine whether or not there is an abnormality in the purification device. [Brief description of the drawings]

[0017] [Figure 1] FIG. 2 is a diagram for explaining an overview of a vehicle S according to the present embodiment. [Diagram 2] FIG. 2 is a diagram showing the configuration of a failure determination device 60. [Diagram 3] FIG. 13 is a diagram showing a load state map stored in a storage unit 61. [Figure 4] 5 is a diagram for explaining an operation for determining whether or not there is an abnormality in the purification device 30. FIG. [Diagram 5] FIG. 11 is a diagram illustrating an operation of calculating a total value of differential pressures. [Figure 6] 4 is a diagram showing an example of a processing sequence in a failure determination device 60. FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0018] <Overview of Vehicle S> FIG. 1 is a diagram for explaining an overview of a vehicle S according to this embodiment. The vehicle S shown in FIG. 1 includes an engine 10, a plurality of injectors 11 (11a, 11b, 11c, and 11d), an intake passage 12, an exhaust passage 13, a crankshaft 20, a crank pulley 21, a purification device 30, a catalyst 31, a filter 32, a temperature raising device 33, a first exhaust pressure sensor 40, a second exhaust pressure sensor 41, a rotation speed sensor 42, an intake pressure sensor 43, a vehicle control device 50, an alarm device 51, and a malfunction determination device 60. The vehicle S has a function of determining whether or not there is an abnormality in the purification device 30. The abnormality in the purification device 30 in this embodiment is, for example, at least one of a state in which the filter 32 housed in the purification device 30 is broken, broken, or removed.

[0019] The engine 10 is an internal combustion engine that generates power by burning and expanding a mixture of fuel and intake air. A plurality of injectors 11 are components for injecting fuel in a fuel tank (not shown) into a combustion chamber in the engine 10. The intake passage 12 is a passage through which air (intake air) supplied to the engine 10 flows. The exhaust passage 13 is a passage provided downstream of the engine 10 and through which the exhaust gas from the engine 10 flows.

[0020] The crankshaft 20 is a shaft for converting the reciprocating motion of pistons (not shown) in the engine 10 into rotational motion. The crank pulley 21 is a pulley attached to the tip of the crankshaft 20. The crank pulley 21 transmits the rotational motion of the crankshaft 20 to an auxiliary device such as an alternator by rotating a belt that is wound around the crank pulley 21 and another pulley (not shown) attached to the auxiliary device.

[0021] The purification device 30 is a device for purifying the exhaust gas of the engine 10, and contains a catalyst 31 and a filter 32. The catalyst 31 is, for example, an oxidation catalyst provided in the exhaust passage 13, and purifies the hydrocarbons and carbon monoxide contained in the exhaust gas of the engine 10. Specifically, the catalyst 31 oxidizes the hydrocarbons to water and carbon dioxide, and oxidizes the carbon monoxide to carbon dioxide. The catalyst 31 may include a reduction catalyst that receives a supply of a urea aqueous solution or ammonia and reduces nitrogen oxides to nitrogen and water.

[0022] The filter 32 is provided downstream of the catalyst 31 in the exhaust passage 13, and is a filter for collecting PM (Particulate Matter) contained in the exhaust gas of the engine 10. The filter 32 burns the PM collected by the filter 32 with the exhaust gas flowing through the exhaust passage 13, the temperature of which has been increased by the temperature increase device 33, and converts the PM into carbon dioxide. The temperature increase device 33 is provided upstream of the catalyst 31 in the exhaust passage 13, and is a device for heating the exhaust gas flowing into the purification device 30. For example, when the temperature increase device 33 includes an exhaust passage injector (not shown) for injecting fuel into the exhaust passage 13, the temperature increase device 33 heats the exhaust gas by the oxidation heat of the fuel injected by the exhaust passage injector. When the temperature increase device 33 does not include the exhaust passage injector, the temperature increase device 33 may heat the exhaust gas by the oxidation heat of the fuel injected by the injector 11. In this case, the temperature increase device 33 is included in the engine 10. In addition, the temperature raising device 33 may heat the exhaust gas by exchanging heat between a heater (not shown) heated by electricity supplied from a battery (not shown) and the exhaust gas flowing through the exhaust path 13.

[0023] The first exhaust pressure sensor 40 is provided in the exhaust path 13 downstream of the catalyst 31 and upstream of the filter 32, and is a sensor that detects the exhaust pressure of the exhaust gas flowing into the filter 32. The first exhaust pressure sensor 40 may be provided in the exhaust path 13 upstream of the catalyst 31 and downstream of the temperature raising device 33. The second exhaust pressure sensor 41 is provided in the exhaust path 13 downstream of the filter 32, and is a sensor that detects the exhaust pressure of the exhaust gas that has passed through the filter 32. The second exhaust pressure sensor 41 may be provided in the exhaust path 13 downstream of the purification device 30.

[0024] The rotation speed sensor 42 is a sensor that detects the rotation speed of the engine 10. As an example, the rotation speed sensor 42 is provided near the crank pulley 21, and detects the number of changes in magnetic force accompanying the rotation of the crank pulley 21 per unit time (e.g., one second). The rotation speed sensor 42 specifies the rotation speed of the clamp pulley 21 based on the detected number of changes in magnetic force, and outputs the rotation speed of the crank pulley 21 as the rotation speed of the engine 10. The intake pressure sensor 43 is provided in the intake passage 12, and is a sensor that detects the intake pressure of the intake air (air) flowing into the engine 10.

[0025] The vehicle control device 50 is a device including one or more processors such as a CPU (Central Processing Unit) or an ECU (Electronic Control Unit). The vehicle control device 50 controls the speed of the vehicle S by, for example, determining the fuel injection amount of the injector 11 corresponding to the accelerator depression amount operated by the driver of the vehicle S. The vehicle control device 50 controls the combustion of PM collected by the filter 32 (so-called filter regeneration) by, for example, raising the temperature of the exhaust gas of the engine 10 by the temperature raising device 33. The vehicle control device 50 outputs the exhaust pressures detected by the first exhaust pressure sensor 40 and the second exhaust pressure sensor 41, the rotation speed of the engine 10 detected by the rotation speed sensor 42, and the intake pressure detected by the intake pressure sensor 43 to the failure determination device 60. The vehicle control device 50 may be included in the failure determination device 60.

[0026] The notification device 51 is a device for notifying the driver of the vehicle S of the state of the vehicle S. The state of the vehicle S is, for example, the presence or absence of an abnormality in the purification device 30. The notification device 51 has, for example, a display, and causes the display to display an image indicating that there is an abnormality in the purification device 30. The notification device 51 has, for example, a speaker, and causes the speaker to emit a sound indicating that there is an abnormality.

[0027] The failure determination device 60 is a housing including electronic components or a printed circuit board on which electronic components are mounted, and executes a process of determining whether or not there is an abnormality in the purifier 30 based on a differential pressure, which is the difference between the exhaust pressure detected by the first exhaust pressure sensor 40 and the exhaust pressure detected by the second exhaust pressure sensor 41. For example, since the differential pressure when the purifier 30 has an abnormality is smaller than the differential pressure when the purifier 30 has no abnormality, the failure determination device 60 can determine whether or not there is an abnormality in the purifier 30 based on whether or not the differential pressure is equal to or greater than a predetermined differential pressure. The differential pressure includes an error (so-called variation) that occurs during the manufacturing process of each of the first exhaust pressure sensor 40 and the second exhaust pressure sensor 41, and an error due to the deterioration of each of the first exhaust pressure sensor 40 and the second exhaust pressure sensor 41.

[0028] Incidentally, the failure determination device 60 can improve the accuracy of detecting an abnormality in the purification device 30 by reducing the proportion of errors contained in the differential pressure. Specifically, the failure determination device 60 can improve the accuracy of determining the presence or absence of an abnormality in the purification device 30 in a state where it can detect a differential pressure larger than a sum value obtained by adding a differential pressure caused by various errors to a predetermined differential pressure that can be determined in an error-free state. Since the magnitude of the differential pressure is larger as the load of the engine 10 is larger, a differential pressure larger than the sum value can be detected in a state where the load of the engine 10 is large (so-called high load). However, in a state where the load of the engine 10 is not high, a differential pressure larger than the sum value cannot be detected, and therefore the accuracy of determining the presence or absence of an abnormality in the purification device 30 decreases.

[0029] Therefore, the failure determination device 60 determines whether or not there is an abnormality in the purification device 30 based on the difference between the first differential pressure when the load of the engine 10 is in a first state or higher, which is lower than a high load, and the second differential pressure when the load of the engine 10 is in a second state, which is lower than the first state. The errors contained in the first differential pressure and the second differential pressure, which are caused by the first exhaust pressure sensor 40 and the second exhaust pressure sensor 41, respectively, are the same value or approximate value, and therefore can be considered not to be included in the difference between the first differential pressure and the second differential pressure. Therefore, by operating as described above, the failure determination device 60 can determine whether or not there is an abnormality in the purification device 30 with high accuracy even when the rate of error contained in the differential pressure is large. In other words, the failure determination device 60 can determine whether or not there is an abnormality in the purification device 30 with high accuracy even when the load of the engine 10 is not a high load, and therefore the range of the load of the engine 10 in which the presence or absence of an abnormality in the purification device 30 can be determined can be widened.

[0030] In the following description, the first state of the engine 10 may be referred to as "medium load", the second state of the engine 10 as "low load", and the third state of the engine 10 as "high load". The first state (medium load), the second state (low load), and the third state (high load) will be described in detail later. The configuration and operation of the failure determination device 60 will be described in detail below.

[0031] <Configuration of the failure determination device 60> 2 is a diagram showing a configuration of the failure determination device 60. The failure determination device 60 has a storage unit 61 and a control unit 62. The control unit 62 has an acquisition unit 621, a detection unit 622, an identification unit 623, a determination unit 624, and a notification unit 625.

[0032] The storage unit 61 has a storage medium such as a read only memory (ROM), a random access memory (RAM), a hard disk drive (HDD), or a solid state drive (SSD). The storage unit 61 stores a program executed by the control unit 62. The storage unit 61 stores various information for detecting the presence or absence of an abnormality in the purification device 30.

[0033] The control unit 62 is, for example, a processor such as a CPU or an ECU. The control unit 62 executes a program stored in the storage unit 61 to function as an acquisition unit 621, a detection unit 622, an identification unit 623, a determination unit 624, and a notification unit 625. The control unit 62 may be configured with one processor, or may be configured with multiple processors or a combination of one or more processors and an electronic circuit. The configuration of each unit realized by the control unit 62 will be described below.

[0034] The acquisition unit 621 acquires a first exhaust pressure of the exhaust flowing into the filter 32, a second exhaust pressure of the exhaust passing through the filter 32, the rotation speed of the engine 10, and the intake pressure of the intake air (air) flowing into the engine 10. The acquisition unit 621 acquires, for example, the first exhaust pressure detected by the first exhaust pressure sensor 40, the second exhaust pressure detected by the second exhaust pressure sensor 41, the rotation speed of the engine 10 detected by the rotation speed sensor 42, and the intake pressure detected by the intake pressure sensor 43 from the vehicle control device 50. The acquisition unit 621 may acquire the torque of the engine 10 and the fuel injection amount of the injector 11 from the vehicle control device 50. The acquisition unit 621 acquires the various values ​​described above at a predetermined period. The predetermined period is, for example, a fixed value of less than one second. The predetermined period may be different for each of the various values ​​described above.

[0035] The detection unit 622 detects a differential pressure, which is a difference between the exhaust pressures upstream and downstream of the purification device 30 provided in the exhaust passage 13. The detection unit 622 detects, for example, a differential pressure between a first exhaust pressure detected by a first exhaust pressure sensor 40 provided on the upstream side of the filter 32 and a second exhaust pressure detected by a second exhaust pressure sensor 41 provided on the downstream side of the filter 32, which is acquired by the acquisition unit 621. The detection unit 622 may detect a differential pressure between the first exhaust pressure detected by the first exhaust pressure sensor 40 provided on the upstream side of the purification device 30 and the second exhaust pressure detected by the second exhaust pressure sensor 41 provided on the downstream side of the purification device 30.

[0036] The identification unit 623 identifies the load state of the engine 10. For example, the identification unit 623 identifies a first load state (medium load) of the engine 10 when the vehicle S equipped with the engine 10 travels on a road other than an expressway. For example, the identification unit 623 identifies a second load state (low load) of the engine 10 when the vehicle S is in an idling state. The identification unit 623 may also identify a third load state (high load) of the engine 10 when the vehicle S travels on an expressway.

[0037] The determination unit 623 determines the load of the engine 10 based on at least two of the engine speed, torque, exhaust gas flow rate, and fuel injection amount of the engine 10. When the vehicle S has an EGR (Exhaust Gas Recirculation) (not shown), the exhaust gas flow rate is the sum of the amount of fresh air (fresh air) flowing into the engine 10 and the amount of EGR gas returned by the EGR. When the vehicle S does not have an EGR, the exhaust gas flow rate is the amount of fresh air flowing into the engine 10. The determination unit 623 determines the exhaust gas flow rate of the engine 10 based on, for example, the intake pressure of the intake air flowing into the engine 10 acquired by the acquisition unit 621. The determination unit 623 determines the low load, medium load, or high load based on at least two of the exhaust gas flow rate determined by the determination unit 623 and the engine speed, torque of the engine 10, and fuel injection amount of the injector 11 acquired by the acquisition unit 621.

[0038] As an example, the identification unit 623 identifies the load of the engine 10 corresponding to the rotation speed of the engine 10 and the torque of the engine 10 or the fuel injection amount of the injector 11. The identification unit 623 identifies the load state of the engine 10 corresponding to the rotation speed of the engine 10 and the torque of the engine 10 or the fuel injection amount of the injector 11 by referring to a load state map stored in the storage unit 61, for example.

[0039] FIG. 3 is a diagram showing a load state map stored in the storage unit 61. FIG. 3 shows, as an example, the state of the load of the engine 10 corresponding to the rotation speed and torque of the engine 10. The horizontal axis of FIG. 3 shows the rotation speed of the engine 10, and the vertical axis of FIG. 3 shows the torque of the engine 10. In FIG. 3, the region L1 shows the medium load region, the region L2 shows the low load region, and the region L3 shows the high load region. The boundary line MX shows the maximum value of the torque corresponding to the rotation speed of the engine 10. The boundary line M0 shows the range of the rotation speed and torque of the engine 10 when the vehicle S is in an idling state. The boundary line M1 shows the minimum value of the torque corresponding to the rotation speed of the engine 10 at the medium load. The boundary line M2 shows the maximum value of the torque corresponding to the rotation speed of the engine 10 at the medium load.

[0040] The torque indicated by the boundary line M1 is the torque corresponding to the rotation speed of the engine 10 when the detection unit 622 detects a differential pressure within a predetermined range from the first differential pressure when there is no abnormality in the purification device 30. The first differential pressure is a differential pressure according to the exhaust gas flow rate of the vehicle S, and is, for example, 1 kPa. The predetermined range is, for example, ±0.1 kPa. Furthermore, the torque indicated by the boundary line M2 is the torque corresponding to the rotation speed of the engine 10 when the detection unit 622 detects a differential pressure within a predetermined range from the second differential pressure when there is no abnormality in the purification device 30. The second differential pressure is a differential pressure according to the exhaust gas flow rate of the vehicle S, and is, for example, 2 kPa.

[0041] Therefore, the medium load can be said to be the load on the engine 10 when the detection unit 622 detects a differential pressure that is equal to or greater than the first differential pressure (e.g., 1 kPa) and less than the second differential pressure (e.g., 2 kPa) in a state where there is no abnormality in the purification device 30. Furthermore, the high load can be said to be the load on the engine 10 when the detection unit 622 detects a differential pressure that is equal to or greater than the second differential pressure (e.g., 2 kPa) in a state where there is no abnormality in the purification device 30.

[0042] 3, when the acquisition unit 621 acquires the rotation speed R1 and the torque N1, the determination unit 623 determines that the coordinate Z1 corresponding to the rotation speed R1 and the torque N1 is included in the region L2, and determines the load of the engine 10 to be a low load. Similarly, when the acquisition unit 621 acquires the rotation speed R2 and the torque N2, the determination unit 623 determines that the coordinate Z2 corresponding to the rotation speed R2 and the torque N2 is included in the region L1, and determines the load of the engine 10 to be a medium load.

[0043] When the identifying unit 623 identifies the load state of the engine 10 corresponding to the rotation speed of the engine 10 and the fuel injection amount of the injector 11, in the load state map shown in Fig. 3, the horizontal axis indicates the rotation speed of the engine 10, and the vertical axis indicates the fuel injection amount of the injector 11. Then, a boundary line MX indicates the maximum value of the fuel injection amount corresponding to the rotation speed of the engine 10. A boundary line M0 indicates the range of the rotation speed of the engine 10 and the fuel injection amount of the injector 11 when the vehicle S is in an idling state. A boundary line M1 indicates the minimum value of the fuel injection amount corresponding to the rotation speed of the engine 10 at a medium load. A boundary line M2 indicates the maximum value of the fuel injection amount corresponding to the rotation speed of the engine 10 at a medium load.

[0044] Furthermore, the fuel injection amount indicated by the boundary line M1 is the fuel injection amount corresponding to the rotation speed of the engine 10 when the detection unit 622 detects a differential pressure within a predetermined range from the first differential pressure in a state where there is no abnormality in the purification device 30. The fuel injection amount indicated by the boundary line M2 is the fuel injection amount corresponding to the rotation speed of the engine 10 when the detection unit 622 detects a differential pressure within a predetermined range from the second differential pressure in a state where there is no abnormality in the purification device 30. In other words, the differential pressure detected by the detection unit 622 at the boundary line M1 and the boundary line M2 when the vertical axis shown in FIG. 3 is the fuel injection amount is the same as the differential pressure when the vertical axis is the torque. Therefore, the load state (low load, medium load, high load) identified by the identification unit 623 using the fuel injection amount and the load state identified by the identification unit 623 using the torque can indicate the same state.

[0045] The determination unit 624 determines whether or not there is an abnormality in the purification device 30. The determination unit 624 acquires a first differential pressure detected by the detection unit 622 when the load of the engine 10 is medium or higher (i.e., medium or high load) and a second differential pressure detected by the detection unit 622 when the load of the engine 10 is lower than the medium load. Then, the determination unit 624 determines that there is an abnormality in the purification device 30 when the difference between the first differential pressure and the second differential pressure is less than a threshold value. The threshold value is a value including other errors different from the errors caused by the first exhaust pressure sensor 40 and the second exhaust pressure sensor 41, and is, for example, a fixed value larger than an error due to a pressure loss of the catalyst 31 (0.5 kPa, for example).

[0046] FIG. 4 is a diagram for explaining the operation of determining whether or not the purification device 30 has an abnormality. The horizontal axis of FIG. 4 indicates time, and the vertical axis of FIG. 4 indicates the differential pressure detected by the detection unit 622. In FIG. 4, the identification unit 623 identifies the load of the engine 10 as low load during the time from time T1 to time T2, and identifies the load of the engine 10 as medium load during the time from time T3 to time T4. Then, the determination unit 624 calculates, for example, "D2-D1", which is the difference between the first differential pressure D2 detected by the detection unit 622 during the time from time T3 to time T4 and the second differential pressure D1 detected by the detection unit 622 during the time from time T1 to time T2. If the calculated difference "D2-D1" is less than a threshold, the determination unit 624 determines that the purification device 30 has an abnormality, and if the calculated difference "D2-D1" is equal to or greater than the threshold, the determination unit 624 determines that the purification device 30 does not have an abnormality.

[0047] By operating the determination unit 624 in this manner, the error of each exhaust pressure sensor included in the second differential pressure can be subtracted from the error of each exhaust pressure sensor included in the first differential pressure. As a result, even if the rate of the error of the exhaust pressure sensor included in the differential pressure is large, the determination can be made based on a value that does not include the error of the exhaust pressure sensor, so the determination unit 624 can determine the presence or absence of an abnormality in the purification device 30 with high accuracy even when the load of the engine 10 is not in a high load state. Specifically, even when the determination unit 623 determines the load to be a medium load (for example, the vehicle S is traveling in an urban area) rather than in a high load state (for example, the vehicle S is traveling on a highway), the determination unit 624 can determine the presence or absence of an abnormality in the purification device 30 with high accuracy. This makes it possible to widen the range of loads of the engine 10 in which the presence or absence of an abnormality in the purification device 30 can be determined with high accuracy.

[0048] The determination unit 624 may calculate a total value of the differential pressures for each load state of the engine 10 based on the multiple differential pressures detected by the detection unit 622 at multiple times, and determine whether or not there is an abnormality in the purification device 30 based on the total value. The determination unit 624 calculates, for example, a total of first differential pressures detected at each time when the load of the engine 10 is medium or higher, and a total of second differential pressures detected at each time when the load of the engine 10 is low. Then, when the total of the first differential pressures is equal to or greater than the first total value and the total of the second differential pressures is equal to or greater than a second total value that is smaller than the first total value, the determination unit 624 determines whether or not there is an abnormality in the purification device 30. The first total value and the second total value are values ​​determined by experiments or simulations, and are stored in the storage unit 61.

[0049] Fig. 5 is a diagram showing an operation of calculating the total value of the differential pressures. The horizontal axis of Fig. 5 indicates time, and the vertical axis of Fig. 5 indicates the differential pressures detected by the detection unit 622, the sum of the first differential pressures, and the sum of the second differential pressures. Times A1, A2, A3, and A4 shown in Fig. 5 are times when the identification unit 623 identifies the load of the engine 10 as a medium load or a high load, and times B1, B2, B3, and B4 are times when the identification unit 623 identifies the load of the engine 10 as a low load. In Fig. 5, the first total value TH1 and the second total value TH2 are also shown.

[0050] For example, the determination unit 624 determines that the sum of the second differential pressures is equal to or greater than the second sum TH2 at time TB, and determines that the sum of the first differential pressures is equal to or greater than the first sum TH1 at time TA. Then, the determination unit 624 determines whether or not there is an abnormality in the purification device 30 at time TA. As an example, the determination unit 624 determines whether or not there is an abnormality in the purification device 30 based on the difference between the first differential pressure detected by the detection unit 622 at time TA and the second differential pressure detected by the detection unit 622 at time TB or time TC. As another example, the determination unit 624 determines whether or not there is an abnormality in the purification device 30 based on the difference between the sum of the first differential pressures detected by the detection unit 622 from time T0 to time TA and the sum of the second differential pressures detected by the detection unit 622 from time T0 to time TB or from time TB to time TC.

[0051] For example, when one of the loads of the engine 10 identified by the identification unit 623 at each predetermined period is a medium load or more and the other loads are less than a medium load, the accuracy of the judgment may be reduced if the judgment unit 624 makes a judgment based on one of the medium loads or more. Therefore, the accuracy of the judgment can be improved by having the judgment unit 624 judge the presence or absence of an abnormality in the purification device 30 when the load of the engine 10 is medium load or more continuously for a predetermined time (for example, 10 seconds), but the frequency of judgment is reduced. In contrast, by operating the judgment unit 624 as described above, even if the time during which the load of the engine 10 is maintained at a medium load or more is short, the presence or absence of an abnormality in the purification device 30 can be determined based on the total value of the differential pressure at the time when the load is medium load or more when the total time during which the load is medium load or more reaches a predetermined time. As a result, the presence or absence of an abnormality in the purification device 30 can be determined with high accuracy even if the load of the engine 10 is not continuously maintained at a medium load or more.

[0052] Furthermore, by determining whether or not there is an abnormality in the purification device 30 based on the pressure differences at multiple times, the determination unit 624 can increase the accuracy of the determination while reducing the frequency of the determination compared to determining whether or not there is an abnormality in the purification device 30 for each time the determination unit 623 identifies a state in which the load of the engine 10 is medium or higher. As a result, the determination unit 624 can reduce the amount of processing for determining whether or not there is an abnormality in the purification device 30.

[0053] Furthermore, the determination unit 624 may determine that the purification device 30 has an abnormality when the difference between the statistics of the plurality of first differential pressures and the statistics of the plurality of second differential pressures is less than a threshold value. The statistics is, for example, an average value, a median value, or a maximum value. For example, in FIG. 5, the determination unit 624 calculates, at time TA, the statistics of the plurality of first differential pressures detected by the detection unit 622 during the period from time T0 to time TA, and the statistics of the plurality of second differential pressures detected by the detection unit 622 during the period from time T0 to time TB. By operating the determination unit 624 in this manner, the determination unit 624 can determine the presence or absence of an abnormality in the purification device 30 with high accuracy and can reduce the amount of data when determining the presence or absence of an abnormality in the purification device 30, even if the load of the engine 10 does not continue to be maintained at a medium load or higher.

[0054] Meanwhile, the vehicle control device 50 executes a process (so-called filter regeneration) of burning the PM trapped by the filter 32 by causing the temperature raising device 33 to raise the temperature of the exhaust gas from the engine 10. Immediately after the filter regeneration is completed, the first exhaust pressure sensor 40 and the second exhaust pressure sensor 41 themselves and their vicinity are in a raised state, which causes the pressure difference detected by the detection unit 622 to increase, and therefore the determination unit 624 may erroneously determine that there is an abnormality in the purification device 30.

[0055] Therefore, the determination unit 624 determines whether or not there is an abnormality in the purification device 30 after a predetermined time has elapsed from the time when the process of burning the PM captured by the filter 32 housed in the purification device 30 is completed. The predetermined time is the time until the temperature of the inlet of the filter 32 returns to the temperature before the filter regeneration, and is, for example, 5 minutes. The determination unit 624 determines whether or not there is an abnormality in the purification device 30 based on the differential pressure detected by the detection unit 622 5 minutes after the time when the filter regeneration is completed, for example. By operating in this manner, the determination unit 624 can prevent the determination unit 624 from erroneously determining whether or not there is an abnormality in the purification device 30 due to a temperature rise caused by the filter regeneration. As a result, the determination unit 624 can determine whether or not there is an abnormality in the purification device 30 with high accuracy.

[0056] The notification unit 625 notifies the notification device 51 of the determination result of the determination unit 624 as to whether or not there is an abnormality in the purifier 30. The notification unit 625, for example, outputs determination information indicating the determination result to the notification device 51, thereby causing the notification device 51 to notify the determination result. Specifically, the notification unit 625, for example, outputs determination information indicating that there is an abnormality in the purifier 30 to the notification device 51, thereby causing the display of the notification device 51 to display an image indicating that there is an abnormality in the purifier 30. The notification unit 625 may output the determination information indicating that there is an abnormality in the purifier 30 to the notification device 51, thereby causing a speaker of the notification device 51 to emit a sound indicating that there is an abnormality in the purifier 30.

[0057] <Processing sequence in the failure determination device 60> 6 is a diagram showing an example of a processing sequence in the failure determination device 60. The processing sequence shown in FIG.

[0058] The acquisition unit 621 acquires the rotation speed and torque of the engine 10 from the vehicle control device 50 (S11). The identification unit 623 identifies the load state of the engine 10 corresponding to the rotation speed and torque of the engine 10 acquired by the acquisition unit 621 by referring to the load information map stored in the storage unit 61 (S12).

[0059] If the load of the engine 10 identified by the identification unit 623 is a low load (YES in S13), the detection unit 622 detects a differential pressure P between the exhaust pressure detected by the first exhaust pressure sensor 40 and the exhaust pressure detected by the second exhaust pressure sensor 41 (S14). Then, the determination unit 624 adds the differential pressure P to the total value U2 of the second differential pressures (S15). If the load of the engine 10 identified by the identification unit 623 is not a low load (NO in S13), the identification unit 623 determines whether the load of the engine 10 is a medium load or more (S16).

[0060] When the load of the engine 10 identified by the identification unit 623 is equal to or greater than a medium load (YES in S16), the detection unit 622 detects a differential pressure P between the exhaust pressure detected by the first exhaust pressure sensor 40 and the exhaust pressure detected by the second exhaust pressure sensor 41 (S17). Then, the determination unit 624 adds the differential pressure P to the total value U1 of the first differential pressures (S18). When the load of the engine 10 identified by the identification unit 623 is not a low load and is less than a medium load (NO in S16), the failure determination device 60 returns to step S11.

[0061] If the sum U1 is less than the first sum TH1 or the sum U2 is less than the second sum TH2 (NO in S19), the determination unit 624 returns to step S11. If the sum U1 is equal to or greater than the first sum TH1 and the sum U2 is equal to or greater than the second sum TH2 (YES in S19), the determination unit 624 calculates an average value C1 of the multiple differential pressures P (first differential pressures) included in the sum U1 and an average value C2 of the multiple differential pressures P (second differential pressures) included in the sum U2 (S20).

[0062] Next, if the subtraction value obtained by subtracting the average value C2 of the second differential pressure from the average value C1 of the first differential pressure is less than the threshold value TH3 (YES in S21), the determination unit 624 determines that there is an abnormality in the purification device 30 (S22). If the subtraction value is equal to or greater than the threshold value TH3 (NO in S21), the determination unit 624 determines that there is no abnormality in the purification device 30 (S23).

[0063] <Effects of the failure determination device 60> As described above, the failure determination device 60 has an identification unit 623 that identifies the load state of the engine 10, a detection unit 622 that detects a differential pressure, which is the difference in exhaust pressure upstream and downstream of the purification device 30 provided in the exhaust passage 13, and a determination unit 624 that determines that there is an abnormality in the purification device 30 when the difference between a first differential pressure detected by the detection unit 622 when the load of the engine 10 is in a first state or higher and a second differential pressure detected by the detection unit 622 when the load of the engine 10 is in a second state lower than the first state is less than a threshold value.

[0064] By configuring the failure determination device 60 in this manner, the failure determination device 60 can determine the presence or absence of a failure in the purification device 30 based on the "difference between the first differential pressure and the second differential pressure" that is not affected by errors of the first exhaust pressure sensor 40 and the second exhaust pressure sensor 41 used to detect the differential pressure. As a result, by increasing the differential pressure and reducing the proportion of errors contained in the differential pressure, it becomes unnecessary to put a high load on the engine 10, and therefore the failure determination device 60 can widen the range of loads of the engine 10 at which the presence or absence of an abnormality in the purification device 30 can be determined. Specifically, even when the vehicle S is traveling on a road other than an expressway (for example, a road laid in an urban area), the presence or absence of an abnormality in the purification device 30 can be determined with high accuracy. Furthermore, by the failure determination device 60 determining the presence or absence of an abnormality in the purification device 30 while the vehicle S is traveling on a road other than an expressway, the failure determination device 60 can increase the frequency at which the failure determination device 60 determines the presence or absence of an abnormality in the purification device 30.

[0065] Although the present invention has been described above using the embodiments, the technical scope of the present invention is not limited to the scope described in the above embodiments, and various modifications and changes are possible within the scope of the gist of the present invention. For example, all or part of the device can be configured by distributing or integrating functionally or physically in any unit. In addition, new embodiments resulting from any combination of multiple embodiments are also included in the embodiments of the present invention. The effect of the new embodiment resulting from the combination combines the effect of the original embodiment. [Explanation of symbols]

[0066] 10 Engine 11 Injector 11a Injector 11b Injector 11c injector 11d Injector 12 Intake passage 13 Exhaust duct 20 Crankshaft 21 Crank pulley 30 Purification Equipment 31 Catalyst 32 Filters 33 Heating device 40 No. 1 exhaust pressure sensor 41 Second exhaust pressure sensor 42 Rotational speed sensor 43 Intake pressure sensor 50 Vehicle control device 51 Notification device 60 Failure determination device 61 Storage section 62 Control section 621 Acquisition Department 622 Detection unit 623 Specific part 624 Judgment section 625 Information Department

Claims

1. An identification unit that identifies a load state of the engine; a detection unit that detects a differential pressure, which is a difference between exhaust pressures on the upstream side and downstream side of a purification device provided in an exhaust flow path; a determination unit that determines that an abnormality exists in the purification device when a difference between a first differential pressure detected by the detection unit when a load on the engine is equal to or greater than a first state and a second differential pressure detected by the detection unit when a load on the engine is in a second state lower than the first state is less than a threshold value; having the identification unit identifies the first state of the load of the engine when the vehicle including the engine is traveling on a road other than an expressway, and the second state of the load of the engine when the vehicle is in an idling state. Failure determination device.

2. The determination unit determines a load of the engine based on at least two of a rotation speed, a torque, an exhaust gas flow rate, and a fuel injection amount of the engine. The failure determination device according to claim 1 .

3. The identification unit identifies a load of the engine corresponding to a rotation speed of the engine and a torque or a fuel injection amount of the engine. The failure determination device according to claim 1 .

4. The detection unit detects a differential pressure between a first exhaust pressure detected by a first sensor provided upstream of the purification device and a second exhaust pressure detected by a second sensor provided downstream of the purification device. The failure determination device according to claim 1 .

5. the determination unit determines whether or not there is an abnormality in the purification device when a sum of the first differential pressures detected at each time when the load of the engine is equal to or greater than the first state is equal to or greater than a first sum value and a sum of the second differential pressures detected at each time when the load of the engine is in the second state is equal to or greater than a second sum value that is smaller than the first sum value. The failure determination device according to claim 1 .

6. The determination unit determines that an abnormality exists in the purification device when a difference between a plurality of statistics of the first differential pressures and a plurality of statistics of the second differential pressures is less than the threshold value. The failure determination device according to claim 5 .

7. the determination unit determines whether or not there is an abnormality in the purification device after a predetermined time has elapsed from the time when the process of burning the particulate matter collected by the purification device is completed. The failure determination device according to claim 1 .

8. The processor executes A determination step of determining a load state of the engine; a detection step of detecting a differential pressure, which is a difference between exhaust pressures on the upstream side and downstream side of a purification device provided in an exhaust flow path; a determination step of determining that an abnormality exists in the purification device when a difference between a first differential pressure detected in the detection step when a load on the engine is equal to or greater than a first state and a second differential pressure detected in the detection step when a load on the engine is in a second state lower than the first state is less than a threshold value; having In the identifying step, the first state of the load of the engine when the vehicle including the engine is traveling on a road other than an expressway and the second state of the load of the engine when the vehicle is in an idling state are identified. Failure determination method.

9. The processor: Identifying an engine load condition; Detecting a differential pressure between exhaust pressures on the upstream side and downstream side of a purification device provided in an exhaust flow path; determining that an abnormality exists in the purification device when a difference between a first differential pressure detected in a step of detecting the differential pressure when the load of the engine is equal to or greater than a first state and a second differential pressure detected in a step of detecting the differential pressure when the load of the engine is in a second state lower than the first state is less than a threshold value; Run the command, In the step of specifying, the first state of the load of the engine when the vehicle including the engine is traveling on a road other than an expressway, and the second state of the load of the engine when the vehicle is in an idling state are specified. program.

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