Failure determination device, failure determination method and program

Abstract

To expand an engine load range that can determine presence / absence of an abnormality of a purification device.SOLUTION: A failure determination device 60 includes: a specification section 623 that specifies a state of a load of an engine 10; a detection section 622 that detects a differential pressure that is a difference of exhaust gas pressure between an upstream side and a downstream side of a purification device 30 provided in an exhaust passage 13; and a determination section 624 that determines the purification device 30 has an abnormality in the case where a difference between a first differential pressure detected by the detection section 622 when the load of the engine 10 is in a first state or greater and a second differential pressure detected by the detection section 622 when the load of the engine 10 is in a second state smaller than the first state is less than a threshold value.SELECTED DRAWING: Figure 2

Description

Technical Field

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

Background Art

[0002] In the hybrid vehicle described in Patent Document 1, when the differential pressure between the exhaust pressure upstream of the purification device provided in the exhaust passage and the exhaust pressure downstream of the purification device is less than a predetermined differential pressure, it is determined that there is an abnormality in the purification device.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems 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 deterioration of each sensor. Therefore, in a conventional hybrid vehicle, in order to improve the accuracy of detecting an abnormality in the purification device, it is desirable to reduce the ratio of the errors included in the differential pressure. In order to reduce the ratio of the errors included in the differential pressure, it is conceivable to increase the differential pressure by setting the engine load to a large state (so-called high load state). However, there is a problem that the state of the engine load when determining the presence or absence of an abnormality in the purification device is limited.

[0005] Therefore, the present invention has been made in view of these points, and an object thereof is to widen the range of the engine load in which the presence or absence of an abnormality in the purification device can be determined.

Means for Solving the Problems

[0006] The failure determination device according to the first aspect of the present invention includes an identifying unit that identifies the state of the engine load, a detecting unit that detects a differential pressure which is the difference between the exhaust pressures on the upstream side and the downstream side of a purification device provided in an exhaust passage, a first differential pressure detected by the detecting unit when the engine load is at a first state or higher, and a second differential pressure detected by the detecting unit when the engine load is at a second state smaller than the first state. When the difference between them is less than a threshold value, it includes a determining unit that determines that there is an abnormality in the purification device.

[0007] The identifying unit may identify the first state of the engine load when the vehicle equipped with the engine is traveling on a road different from a highway, and the second state of the engine load when the vehicle is in an idling state.

[0008] The identifying unit may identify the engine load based on at least two of the engine speed, torque, exhaust gas flow rate, and fuel injection amount.

[0009] The identifying unit may identify the engine load corresponding to the engine speed and the engine torque or fuel injection amount.

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

[0011] The determining unit may determine whether there is an abnormality in the purification device when the sum of the first differential pressures detected at each time when the engine load is at the first state or higher is equal to or greater than a first total value, and the sum of the second differential pressures detected at each time when the engine load is at the second state is equal to or greater than a second total value smaller than the first total value.

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

[0013] The determination unit may determine whether there is an abnormality in the purification device after a predetermined time has elapsed since the time when the process of burning the particulate matter collected by the purification device has ended.

[0014] The failure determination method according to the second aspect of the present invention includes a specifying step of specifying the state of the engine load, which is executed by a processor, a detecting step of detecting a differential pressure, which is the difference in exhaust pressure between the upstream side and the downstream side of a purification device provided in an exhaust passage, a first differential pressure detected in the detecting step when the engine load is in a first state or more, and a second differential pressure detected in the detecting step when the engine load is in a second state smaller than the first state, and a determining step of determining that there is an abnormality in the purification device when the difference between the first differential pressure and the second differential pressure is less than a threshold value.

[0015] The program according to the third aspect of the present invention causes a processor to execute a step of specifying the state of the engine load, a step of detecting a differential pressure, which is the difference in exhaust pressure between the upstream side and the downstream side of a purification device provided in an exhaust passage, a step of detecting a first differential pressure in the step of detecting the differential pressure when the engine load is in a first state or more, a step of detecting a second differential pressure in the step of detecting the differential pressure when the engine load is in a second state smaller than the first state, and a step of determining that there is an abnormality in the purification device when the difference between the first differential pressure and the second differential pressure is less than a threshold value.

Advantages of the Invention

[0016] According to the present invention, there is an effect of widening the range of the engine load in which it is possible to determine whether there is an abnormality in the purification device.

Brief Description of the Drawings

[0017]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Embodiment for Carrying Out the Invention

[0018] <Overview of Vehicle S> FIG. 1 is a diagram for explaining the overview of the vehicle S according to the present 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 warming device 33, a first exhaust pressure sensor 40, a second exhaust pressure sensor 41, a rotational speed sensor 42, an intake pressure sensor 43, a vehicle control device 50, a notification device 51, and a failure determination device 60. The vehicle S has a function of determining the presence or absence of an abnormality in the purification device 30. The abnormality of the purification device 30 in the present embodiment is, for example, at least one of the states where the filter 32 accommodated in the purification device 30 is in a failed state, a damaged state, or a removed state.

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

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

[0021] The purification device 30 is a device for purifying the exhaust gas of the engine 10, and houses a catalyst 31 and a filter 32. The catalyst 31 is, for example, an oxidation catalyst provided in the exhaust passage 13, and purifies hydrocarbons and carbon monoxide contained in the exhaust gas of the engine 10. Specifically, the catalyst 31 oxidizes hydrocarbons into water and carbon dioxide, and oxidizes carbon monoxide into carbon dioxide. The catalyst 31 may include a reduction catalyst that receives the supply of an aqueous urea solution or ammonia and reduces nitrogen oxides into 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 heated by the temperature raising device 33 and converts it into carbon dioxide. The temperature raising 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 raising device 33 includes an exhaust passage injector (not shown) for injecting fuel into the exhaust passage 13, the exhaust gas is heated by the oxidation heat of the fuel injected by the exhaust passage injector. When the temperature raising device 33 does not include an exhaust passage injector, the temperature raising device 33 may heat the exhaust gas by the oxidation heat of the fuel injected into the injector 11. In this case, the temperature raising device 33 is included in the engine 10. Further, the temperature raising device 33 may heat the exhaust gas by heat-exchanging a heater (not shown) heated by electricity supplied from a battery (not shown) with the exhaust gas flowing through the exhaust passage 13.

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

[0024] The rotational speed sensor 42 is a sensor that detects the rotational speed of the engine 10. As an example, the rotational speed sensor 42 is provided in proximity to the crank pulley 21 and detects the number of changes in magnetic force associated with the rotation of the crank pulley 21 per unit time (for example, 1 second). The rotational speed sensor 42 identifies the rotational speed of the crank pulley 21 based on the detected number of changes in magnetic force and outputs the rotational speed of the crank pulley 21 as the rotational speed of the engine 10. The intake pressure sensor 43 is a sensor that is provided in the intake passage 12 and detects the intake pressure of the intake air (air) flowing into the engine 10.

[0025] The vehicle control device 50 is a device that includes, for example, 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, for example, by determining the fuel injection amount of the injector 11 corresponding to the depression amount of the accelerator operated by the driver of the vehicle S. The vehicle control device 50 controls the combustion of the PM collected by the filter 32 (so-called filter regeneration), for example, by heating the exhaust gas of the engine 10 with the temperature increasing 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 rotational speed of the engine 10 detected by the rotational speed sensor 42, and the intake pressure detected by the intake pressure sensor 43 to the failure determination device 60. Note that 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 the abnormality.

[0027] The failure determination device 60 is a housing including electronic components or a printed circuit board on which the electronic components are mounted, and executes a process of determining the presence or absence of an abnormality in the purification device 30 based on a differential pressure that 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 in a state where there is an abnormality in the purification device 30 is smaller than the differential pressure in a state where there is no abnormality in the purification device 30, the failure determination device 60 can determine the presence or absence of an abnormality in the purification device 30 based on whether the differential pressure is equal to or greater than a predetermined differential pressure. Further, the differential pressure includes an error (so-called variation) generated in the process of manufacturing each of the first exhaust pressure sensor 40 and the second exhaust pressure sensor 41, and an error caused by 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 ratio of the error included 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 a differential pressure larger than an added value obtained by adding a differential pressure caused by various errors to a predetermined differential pressure that can be determined in a state where there is no error can be detected. Since the magnitude of the differential pressure increases as the load of the engine 10 increases, in a state where the load of the engine 10 is large (so-called high load), a differential pressure larger than the added value can be detected. However, in a state where the load of the engine 10 is not a high load, a differential pressure larger than the added value cannot be detected, so 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 the presence or absence of an abnormality in the purification device 30 based on the difference between a first differential pressure in a first state where the load of the engine 10 is less than the high load and a second differential pressure in a second state where the load of the engine 10 is less than the first state. Since the errors caused by the first exhaust pressure sensor 40 and the second exhaust pressure sensor 41 included in the first differential pressure and the second differential pressure are the same value or approximate values, it can be considered that they are not included in the difference between the first differential pressure and the second differential pressure. Therefore, when the failure determination device 60 operates as described above, even when the proportion of the error included in the differential pressure is large, the presence or absence of an abnormality in the purification device 30 can be determined with high accuracy. That is, since the failure determination device 60 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 a high load, 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 may be referred to as "low load", and the third state of the engine 10 may be referred to as "high load". Details of the first state (medium load), the second state (low load), and the third state (high load) will be described later. Hereinafter, the configuration and operation of the failure determination device 60 will be described in detail.

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

[0032] The storage unit 61 has a storage medium such as a ROM (Read Only Memory), a RAM (Random Access Memory), an HDD (Hard Disk Drive), or an SSD (Solid State Drive), for example. The storage unit 61 stores a program executed by the control unit 62. The storage unit 61 stores various types of information for detecting the presence or absence of an abnormality in the purification device 30.

[0033] The control unit 62 is a processor such as a CPU or an ECU, for example. By executing the program stored in the storage unit 61, the control unit 62 functions as an acquisition unit 621, a detection unit 622, a specification unit 623, a determination unit 624, and a notification unit 625. Note that the control unit 62 may be composed of one processor, or may be composed of a combination of a plurality of processors or one or more processors and an electronic circuit. Hereinafter, the configuration of each unit realized by the control unit 62 will be described.

[0034] The acquisition unit 621 acquires the first exhaust pressure of the exhaust gas flowing into the filter 32, the second exhaust pressure of the exhaust gas that has passed through the filter 32, the rotational 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 rotational speed of the engine 10 detected by the rotational 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 above various values at a predetermined period. The predetermined period is, for example, a fixed value less than 1 second. The predetermined period may be different for each of the above various values.

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

[0036] The specifying unit 623 specifies the load state of the engine 10. For example, the specifying unit 623 specifies a first state (medium load) of the load of the engine 10 when the vehicle S equipped with the engine 10 travels on a road different from a highway. For example, the specifying unit 623 specifies a second state (low load) of the load of the engine 10 when the vehicle S is in an idling state. The specifying unit 623 may specify a third state (high load) of the load of the engine 10 when the vehicle S travels on a highway.

[0037] The specifying unit 623 specifies the load of the engine 10 based on at least two of the rotational speed, torque, exhaust gas flow rate, and fuel injection amount of the engine 10. The exhaust gas flow rate is the sum of the fresh air amount of the air (fresh air) flowing into the engine 10 and the recirculation amount of the EGR gas recirculated by EGR (Exhaust Gas Recirculation) (not shown) when the vehicle S has EGR. When the vehicle S does not have EGR, the exhaust gas flow rate is the fresh air amount of the fresh air flowing into the engine 10. The specifying unit 623 specifies 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 specifying unit 623 specifies low load, medium load, or high load based on at least two of the exhaust gas flow rate specified by the specifying unit 623, the rotational speed of the engine 10, the torque of the engine 10, and the fuel injection amount of the injector 11 acquired by the acquisition unit 621.

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

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

[0040] The torque indicated by the boundary line M1 is the torque corresponding to the rotational 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 first differential pressure is a differential pressure corresponding 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. Further, the torque indicated by the boundary line M2 is the torque corresponding to the rotational 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. The second differential pressure is a differential pressure corresponding 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 of the engine 10 when the detection unit 622 detects a differential pressure equal to or higher than the first differential pressure (for example, 1 kPa) and less than the second differential pressure (for example, 2 kPa) in a state where there is no abnormality in the purification device 30. Further, the high load can be said to be the load of the engine 10 when the detection unit 622 detects a differential pressure equal to or higher than the second differential pressure (for example, 2 kPa) in a state where there is no abnormality in the purification device 30.

[0042] As shown in FIG. 3, when the acquisition unit 621 acquires the rotational speed R1 and the torque N1, the specifying unit 623 specifies that the coordinate Z1 corresponding to the rotational speed R1 and the torque N1 is included in the region L2, and specifies that the load on the engine 10 is a low load. Similarly, when the acquisition unit 621 acquires the rotational speed R2 and the torque N2, the specifying unit 623 specifies that the coordinate Z2 corresponding to the rotational speed R2 and the torque N2 is included in the region L1, and specifies that the load on the engine 10 is a medium load.

[0043] When the specifying unit 623 specifies the load state of the engine 10 corresponding to the rotational 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 rotational speed of the engine 10, and the vertical axis indicates the fuel injection amount of the injector 11. And the boundary line MX indicates the maximum value of the fuel injection amount corresponding to the rotational speed of the engine 10. The boundary line M0 indicates the range of the rotational speed of the engine 10 and the fuel injection amount of the injector 11 when the vehicle S is in the idling state. The boundary line M1 indicates the minimum value of the fuel injection amount corresponding to the rotational speed of the engine 10 under a medium load. The boundary line M2 indicates the maximum value of the fuel injection amount corresponding to the rotational speed of the engine 10 under a medium load.

[0044] Furthermore, the fuel injection amount indicated by the boundary line M1 is the fuel injection amount corresponding to the rotational 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 rotational 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. That is, when the vertical axis shown in FIG. 3 is the fuel injection amount, the differential pressure detected by the detection unit 622 at the boundary line M1 and the boundary line M2 is the same as the differential pressure when the vertical axis is the torque. Therefore, the load state (low load, medium load, high load) specified by the specifying unit 623 using the fuel injection amount and the load state specified by the specifying unit 623 using the torque can indicate the same state.

[0045] The determination unit 624 determines whether there is an abnormality in the purification device 30. When the load of the engine 10 is medium load or higher (i.e., medium load or high load), the determination unit 624 acquires the first differential pressure detected by the detection unit 622, and when the load of the engine 10 is a low load smaller than the medium load, the determination unit 624 acquires the second differential pressure detected by the detection unit 622. Then, when the difference between the first differential pressure and the second differential pressure is less than the threshold value, the determination unit 624 determines that there is an abnormality in the purification device 30. 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 the error due to the pressure loss of the catalyst 31 (as an example, 0.5 kPa).

[0046] Figure 4 is a diagram for explaining the operation of determining whether there is an abnormality in the purification device 30. The horizontal axis of Figure 4 indicates time, and the vertical axis of Figure 4 indicates the differential pressure detected by the detection unit 622. In Figure 4, in the time from time T1 to time T2, the specifying unit 623 specifies the load of the engine 10 as a low load, and in the time from time T3 to time T4, the specifying unit 623 specifies the load of the engine 10 as a medium load. 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 in the time from time T3 to time T4 and the second differential pressure D1 detected by the detection unit 622 in the time from time T1 to time T2. When the calculated difference "D2 - D1" is less than the threshold value, the determination unit 624 determines that there is an abnormality in the purification device 30, and when the calculated difference "D2 - D1" is greater than or equal to the threshold value, the determination unit 624 determines that there is no abnormality in the purification device 30.

[0047] By operating in this manner, the determination unit 624 can subtract the error of each exhaust pressure sensor included in the second differential pressure from the error of each exhaust pressure sensor included in the first differential pressure. As a result, even if the ratio 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. Therefore, 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 a high load. Specifically, even in a situation where the specifying unit 623 specifies a medium load (for example, a situation where the vehicle S is traveling in an urban area) instead of a situation where the specifying unit 623 specifies a high load (for example, a situation where 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. Thereby, 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 with high accuracy can be widened.

[0048] The determination unit 624 may calculate the total value of the differential pressures for each load state of the engine 10 based on the plurality of differential pressures detected by the detection unit 622 at a plurality of times, and determine the presence or absence of an abnormality in the purification device 30 based on the total value. For example, the determination unit 624 calculates the sum of the first differential pressures detected at each time when the load of the engine 10 is a medium load or higher, and the sum of the second differential pressures detected at each time when the load of the engine 10 is a low load. Then, the determination unit 624 determines whether there is an abnormality in the purification device 30 when the sum of the first differential pressures is equal to or greater than a first total value and the sum of the second differential pressures is equal to or greater than a second total value that is smaller than the first total value. 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 pressure 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 specifying unit 623 specifies 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 specifying unit 623 specifies the load of the engine 10 as a low load. In FIG. 5, a first total value TH1 and a second total value TH2 are also shown.

[0050] The determination unit 624 specifies, for example, that the total of the second differential pressures is equal to or greater than the second total value TH2 at time TB, and specifies that the total of the first differential pressures is equal to or greater than the first total value TH1 at time TA. Then, the determination unit 624 determines whether there is an abnormality in the purification device 30 at time TA. As an example, the determination unit 624 determines the presence or absence of 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 the presence or absence of an abnormality in the purification device 30 based on the difference between the total of each first differential pressure detected by the detection unit 622 from time T0 to time TA and the total of each second differential pressure 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 specified by the specifying unit 623 is equal to or greater than the medium load and the other loads are less than the medium load among the loads of the engine 10 specified at each predetermined cycle, if the determination unit 624 determines based on one load equal to or greater than the medium load, the accuracy of the determination may decrease. Therefore, by having the determination unit 624 determine the presence or absence of an abnormality in the purification device 30 when the load of the engine 10 is continuously equal to or greater than the medium load for a predetermined time (for example, 10 seconds), the accuracy of the determination can be improved, but the frequency of determination decreases. On the other hand, by the determination unit 624 operating as described above, even if the time during which the load of the engine 10 is equal to or greater than the medium load is short, based on the total value of the differential pressures at the times equal to or greater than the medium load when the total time equal to or greater than the medium load reaches a predetermined time, the presence or absence of an abnormality in the purification device 30 can be determined. As a result, the presence or absence of an abnormality in the purification device 30 can be determined with high accuracy without the load of the engine 10 continuously remaining equal to or greater than the medium load.

[0052] Furthermore, by determining the presence or absence of an abnormality in the purification device 30 based on the differential pressures at a plurality of times, the determination unit 624 can increase the accuracy of the determination while reducing the frequency of the determination as compared to determining the presence or absence of an abnormality in the purification device 30 for each time specified by the specifying unit 623 when the load on the engine 10 is medium load or higher. As a result, the determination unit 624 can reduce the processing amount for determining the presence or absence of an abnormality in the purification device 30.

[0053] Furthermore, the determination unit 624 may determine that there is an abnormality in the purification device 30 when the difference between the statistical amount of the plurality of first differential pressures and the statistical amount of the plurality of second differential pressures is less than the threshold value. The statistical amount is, for example, an average value, a median value, or a maximum value. For example, in FIG. 5, at time TA, the determination unit 624 calculates the statistical amount of the plurality of first differential pressures detected by the detection unit 622 during the time from time T0 to time TA and the statistical amount of the plurality of second differential pressures detected by the detection unit 622 during the time from time T0 to time TB. By operating in this manner, the determination unit 624 can determine the presence or absence of an abnormality in the purification device 30 with high accuracy without continuously maintaining the state where the load on the engine 10 is medium load or higher, and can reduce the amount of data when determining the presence or absence of an abnormality in the purification device 30.

[0054] Incidentally, the vehicle control device 50 executes a process (so-called filter regeneration) of burning the PM collected by the filter 32 by raising the temperature of the exhaust gas of the engine 10 by the temperature raising device 33. Immediately after the filter regeneration is completed, since the first exhaust pressure sensor 40 and the second exhaust pressure sensor 41 themselves and the vicinity thereof are in a heated state, the differential pressure detected by the detection unit 622 increases, so that the determination unit 624 may erroneously determine that there is an abnormality in the purification device 30.

[0055] Therefore, for example, after a predetermined time has elapsed since the time when the process of burning the PM collected by the filter 32 accommodated in the purification device 30 has ended, the determination unit 624 determines whether there is an abnormality in the purification device 30. The predetermined time is the time until the temperature at the inlet of the filter 32 returns to the temperature before filter regeneration, and is, for example, 5 minutes. The determination unit 624 determines the presence or absence of an abnormality in the purification device 30 based on, for example, the differential pressure detected by the detection unit 622 five minutes after the time when the filter regeneration ends. By operating in this way, the determination unit 624 can prevent misjudging the presence or absence of an abnormality in the purification device 30 due to the temperature increase caused by filter regeneration. As a result, the determination unit 624 can determine the presence or absence of an abnormality in the purification device 30 with high accuracy.

[0056] The notification unit 625 causes the notification device 51 to notify the determination result of whether there is an abnormality in the purification device 30 determined by the determination unit 624. For example, the notification unit 625 causes the notification device 51 to notify the determination result by outputting determination information indicating the determination result to the notification device 51. Specifically, for example, the notification unit 625 outputs determination information indicating that there is an abnormality in the purification device 30 to the notification device 51, causing the display included in the notification device 51 to display an image indicating that there is an abnormality in the purification device 30. The notification unit 625 may output determination information indicating that there is an abnormality in the purification device 30 to the notification device 51, causing a sound indicating that there is an abnormality in the purification device 30 to be emitted from the speaker included in the notification device 51.

[0057] <Processing Sequence in the Failure Determination Device 60> FIG. 6 is a diagram showing an example of a processing sequence in the failure determination device 60. The processing sequence shown in FIG. 6 is a processing sequence showing the operation of the failure determination device 60 for determining the presence or absence of an abnormality in the purification device 30.

[0058] The acquisition unit 621 acquires the rotational speed and torque of the engine 10 from the vehicle control device 50 (S11). The specifying unit 623 specifies the load state of the engine 10 corresponding to the rotational 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] When the load of the engine 10 identified by the identifying unit 623 is a low load (YES in S13), the detecting unit 622 detects the 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 determining unit 624 adds the differential pressure P to the total value U2 of the second differential pressure (S15). When the load of the engine 10 identified by the identifying unit 623 is not a low load (NO in S13), the identifying unit 623 determines whether the load of the engine 10 is a medium load or higher (S16).

[0060] When the load of the engine 10 identified by the identifying unit 623 is a medium load or higher (YES in S16), the detecting unit 622 detects the 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 determining unit 624 adds the differential pressure P to the total value U1 of the first differential pressure (S18). When the load of the engine 10 identified by the identifying 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] When the total value U1 is less than the first total value TH1 or the total value U2 is less than the second total value TH2 (NO in S19), the determining unit 624 returns to step S11. When the total value U1 is greater than or equal to the first total value TH1 and the total value U2 is greater than or equal to the second total value TH2 (YES in S19), the determining unit 624 calculates the average value C1 of the plurality of differential pressures P (first differential pressure) included in the total value U1 and the average value C2 of the plurality of differential pressures P (second differential pressure) included in the total value U2 (S20).

[0062] Subsequently, when 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 determining unit 624 determines that there is an abnormality in the purification device 30 (S22). When the subtraction value is greater than or equal to the threshold value TH3 (NO in S21), the determining unit 624 determines that there is no abnormality in the purification device 30 (S23).

[0063] <Effect of the failure determination device 60> As described above, the failure determination device 60 includes a specifying unit 623 that specifies the load state of the engine 10, a detecting unit 622 that detects a differential pressure, which is the difference in exhaust pressure between the upstream side and the downstream side of the purification device 30 provided in the exhaust passage 13, a first differential pressure detected by the detecting unit 622 when the load of the engine 10 is equal to or higher than a first state, and a second differential pressure detected by the detecting unit 622 when the load of the engine 10 is in a second state smaller than the first state. When the difference between the first differential pressure and the second differential pressure is less than a threshold value, the determination unit 624 determines that there is an abnormality in the purification device 30.

[0064] With the failure determination device 60 configured in this way, 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 the errors of the first exhaust pressure sensor 40 and the second exhaust pressure sensor 41 used for detecting the differential pressure. As a result, by increasing the differential pressure and reducing the ratio of the error included in the differential pressure, it becomes unnecessary to increase the load of the engine 10. Therefore, the failure determination device 60 can widen 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. Specifically, even when the vehicle S is traveling on a road different from a highway (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. And when the failure determination device 60 determines the presence or absence of an abnormality in the purification device 30 while the vehicle S is traveling on a road different from a highway, the failure determination device 60 can increase the frequency of determining the presence or absence of an abnormality in the purification device 30.

[0065] As described above, the present invention has been described using embodiments. However, 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. For example, all or part of the device can be configured by being functionally or physically dispersed and integrated in any unit. Also, new embodiments generated by any combination of a plurality of embodiments are included in the embodiments of the present invention. The effects of the new embodiments generated by the combination have the effects of the original embodiments combined.

Explanation of Reference Numerals

[0066] 10 Engine 11 Injector 11a Injector 11b Injector 11c Injector 11d Injector 12 Intake passage 13 Exhaust passage 20 Crankshaft 21 Crank pulley 30 Purification device 31 Catalyst 32 Filter 33 Heating device 40 First exhaust pressure sensor 41 Second exhaust pressure sensor 42 Rotation speed sensor 43 Intake pressure sensor 50 Vehicle control device 51 Notification device 60 Fault determination device 61 Memory unit 62 Control unit 621 Acquisition unit 622 Detection unit 623 Identification unit 624 Judgment unit 625 Notification unit

Claims

1. A specifying unit that specifies the state of the engine load; A detection unit that detects a differential pressure which is the difference in the exhaust pressures on the upstream side and the downstream side of a purification device provided in an exhaust passage; 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 a first state or higher and a second differential pressure detected by the detection unit when the load of the engine is at a second state smaller than the first state is less than a threshold value; A failure determination device having the above.

2. The specifying unit specifies the first state of the engine load when a vehicle equipped with the engine travels on a road different from a highway, and the second state of the engine load when the vehicle is in an idling state, The failure determination device according to Claim 1.

3. The specifying unit specifies the engine load based on at least two of the engine speed, torque, exhaust gas flow rate, and fuel injection amount, The failure determination device according to Claim 1 or 2.

4. The specifying unit specifies the engine load corresponding to the engine speed and the engine torque or fuel injection amount, The failure determination device according to Claim 1 or 2.

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

6. The determination unit determines whether there is an abnormality in the purification device when the sum of the first differential pressures detected at each time when the load of the engine is at the first state or higher is equal to or greater than a first total value, and the sum of the second differential pressures detected at each time when the load of the engine is at the second state is equal to or greater than a second total value smaller than the first total value, The failure determination device according to Claim 1.

7. The determination unit determines that there is an abnormality in the purification device when the difference between the statistical amounts of the plurality of first differential pressures and the statistical amounts of the plurality of second differential pressures is less than the threshold value, The failure determination device according to Claim 6.

8. The determination unit determines whether there is an abnormality in the purification device after a predetermined time has elapsed since the time when the process of burning the particulate matter collected by the purification device has ended, The failure determination device according to Claim 1.

9. Executed by a processor, A specifying step of specifying the state of the engine load; A detection step of detecting a differential pressure, which is a difference in exhaust pressure between the upstream side and the downstream side of a purification device provided in an exhaust passage; A determination step of determining that there is an abnormality in the purification device when a difference between a first differential pressure detected in the detection step when the load of the engine is in a first state or more and a second differential pressure detected in the detection step when the load of the engine is in a second state smaller than the first state is less than a threshold value; A failure determination method having the above.

10. For a processor, A step of specifying a state of an engine load; A step of detecting a differential pressure, which is a difference in exhaust pressure between the upstream side and the downstream side of a purification device provided in an exhaust passage; A step of determining that there is an abnormality in the purification device when a difference between a first differential pressure detected in the step of detecting the differential pressure when the load of the engine is in a first state or more and a second differential pressure detected in the step of detecting the differential pressure when the load of the engine is in a second state smaller than the first state is less than a threshold value; A program for causing the above to be executed.

Images