Filter status detection device

Abstract

The present invention provides a filter state detection device for detecting the state of a filter with high precision. The filter state detection device includes: a differential pressure sensor that detects the filter differential pressure between the upstream side and the downstream side of the filter, which is disposed in the exhaust pipe to capture particulate matter contained in the exhaust gas of a vehicle; a calculation unit that calculates a pressure ratio between a reference differential pressure on the upstream side and the downstream side of the filter preset in a manner corresponding to the flow rate of the exhaust gas and the filter differential pressure detected by the differential pressure sensor; and a determination unit that infers the accumulation amount of particulate matter in the filter based on the pressure ratio calculated by the calculation unit.

Description

Technical Field

[0001] The present invention relates to a filter state detection device. Background Art

[0002] Conventionally, in vehicles such as commercial vehicles, for example, a filter that captures particulate matter contained in exhaust gas is disposed in an exhaust pipe, and a filter state detection device that detects the state of the filter has been put into practical use. As an example of a filter state detection device, a technique is known in which the amount of particulate matter accumulated in a filter is calculated based on the filter pressure difference between the upstream side and the downstream side of the filter.

[0003] For example, if it is used immediately after the regeneration treatment of the filter, the filter state detection device can calculate the amount of ash accumulated in the particulate matter based on the filter pressure difference. This ash is a non-combustible substance caused by metal oxides, sulfates, etc. contained in engine oil, fuel additives, etc., and it is difficult to remove by the regeneration treatment of the filter that burns the particulate matter by using high temperature. Therefore, by calculating the amount of ash accumulated, for example, it is possible to determine the timing of maintenance such as cleaning and replacement of the filter. Here, it is necessary to accurately determine the maintenance timing of the filter.

[0004] Therefore, as a technique for accurately determining the maintenance timing of a filter, for example, a regeneration treatment control method of a DPF (Diesel Particulate Filter) is disclosed in Patent Document 1, and this regeneration treatment control method improves the determination accuracy of whether there is a DPF failure. This regeneration treatment control method changes the threshold value for determining excessive accumulation of particulate matter based on the amount of ash accumulated, and therefore can accurately determine the maintenance timing of the filter in consideration of the amount of ash accumulated.

[0005] Prior Art Documents

[0006] Patent Documents

[0007] Patent Document 1: Japanese Patent Laid-Open No. 2007-270695 Summary of the Invention

[0008] Problems to be Solved by the Invention

[0009] However, the regeneration treatment control method of Patent Document 1 determines the amount of particulate matter accumulated in the filter only based on the filter pressure difference between the upstream side and the downstream side of the filter. Since the filter pressure difference varies greatly corresponding to the exhaust gas flow rate, etc., it is difficult to detect the state of the filter such as the amount of particulate matter accumulated with high accuracy.

[0010] An object of the present invention is to provide a filter state detection device that detects the state of a filter with high accuracy.

[0011] Solution to the problem

[0012] The filter state detection device of the present invention includes: a differential pressure sensor that detects the filter differential pressure between the upstream side and the downstream side of the filter, which is disposed in the exhaust pipe to capture particulate matter contained in the exhaust gas of the vehicle; a calculation unit that calculates the pressure ratio between the reference differential pressure between the upstream side and the downstream side of the filter preset corresponding to the flow rate of the exhaust gas and the filter differential pressure detected by the differential pressure sensor; and a determination unit that infers the accumulation amount of particulate matter in the filter based on the pressure ratio calculated by the calculation unit.

[0013] Advantages of the invention

[0014] According to the present invention, the state of the filter can be detected with high precision. Description of the drawings

[0015] Figure 1 It is a diagram showing the structure of a vehicle equipped with the filter state detection device of Embodiment 1 of the present invention.

[0016] Figure 2 It is a graph showing the change in the filter differential pressure detected by the differential pressure sensor.

[0017] Figure 3 It is a graph showing the pressure ratio between the reference differential pressure and the filter differential pressure.

[0018] Figure 4 It is a graph showing the change in the pressure ratio calculated each time the regeneration process of the filter is performed.

[0019] Figure 5 It is a diagram showing the structure of the main part of the filter state detection device of Embodiment 2. Detailed implementation manners

[0020] Hereinafter, embodiments of the present invention will be described based on the drawings.

[0021] (Embodiment 1)

[0022] Figure 1 It shows the structure of a vehicle equipped with the filter state detection device of Embodiment 1 of the present invention. The vehicle has: an internal combustion engine 1, an intake pipe 2, an exhaust pipe 3, an internal combustion engine control unit 4, and a purification device 5. It should be noted that, as the vehicle, for example, a commercial vehicle such as a truck can be cited.

[0023] The internal combustion engine 1 is used to drive the vehicle and is composed of, for example, a so-called four-stroke engine that repeatedly performs four strokes: an intake stroke, a compression stroke, an expansion stroke, and an exhaust stroke. As the internal combustion engine 1, for example, a diesel engine can be cited.

[0024] The intake pipe 2 is a flow path that connects its front end to the intake port of the internal combustion engine 1 and supplies the air inhaled from the outside to the internal combustion engine 1.

[0025] The exhaust pipe 3 is a flow path that is configured to extend from the exhaust port of the internal combustion engine 1 to the outside and discharges the exhaust gas discharged from the internal combustion engine 1 to the outside.

[0026] The internal combustion engine control unit 4 controls the internal combustion engine 1 and is respectively connected to the internal combustion engine 1 and the regeneration processing control part of the purification device 5. The internal combustion engine control unit 4 controls, for example, the flow rates of the air and exhaust gas flowing through the intake pipe 2 and the exhaust pipe 3, the engine speed, and the fuel injection.

[0027] The purification device 5 includes: an oxidation catalyst 6, a filter 7, temperature sensors 8a and 8b, a valve 9, an injector 10, a regeneration processing control unit 11, and a filter state detection device 12.

[0028] The oxidation catalyst 6 is disposed in the exhaust pipe 3 and purifies unburned fuel such as hydrocarbons and carbon monoxide contained in the exhaust gas by oxidizing it. In addition, the oxidation catalyst 6 heats the exhaust gas to a high temperature by using the reaction heat generated by oxidizing the fuel injected from the injector 10. The oxidation catalyst 6 can be composed of, for example, platinum and cerium oxide.

[0029] The filter 7 is disposed downstream of the oxidation catalyst 6 in the exhaust pipe 3 and captures particulate matters such as soot components and ash. The filter 7 can be of a so-called wall flow type, which is formed by arranging units made of porous ceramics such as cordierite and silicon carbide in an alternatingly closed manner at the inlets and outlets.

[0030] The temperature sensors 8a and 8b detect the temperature of the exhaust gas flowing in the exhaust pipe 3 and are disposed in the exhaust pipe 3 with the oxidation catalyst 6 sandwiched therebetween.

[0031] The valve 9 is a so-called exhaust throttle valve that is connected to the regeneration processing control unit 11 and adjusts the opening degree of the exhaust pipe 3 under the control of the regeneration processing control unit 11. The valve 9 can be configured to adjust the opening degree of the exhaust pipe 3 by rotating around a rotation axis orthogonal to the exhaust pipe 3. In addition, the valve 9 can be disposed near the internal combustion engine 1 between the internal combustion engine 1 and the temperature sensor 8a, and specifically, can be disposed downstream of a turbocharger (not shown).

[0032] The injector 10 is connected to the regeneration processing control unit 11 and injects fuel into the exhaust pipe 3 under the control of the regeneration processing control unit 11. The injector 10 is disposed downstream of the valve 9 in the exhaust pipe 3.

[0033] The regeneration process control unit 11 is connected to the internal combustion engine control unit 4, the temperature sensor 8a, the temperature sensor 8b, and the differential pressure sensor 13 of the filter state detection device 12. The regeneration process control unit 11 determines the timing to start the regeneration process of the filter 7 based on the differential pressure of the filter between the upstream side and the downstream side of the filter 7 input from the differential pressure sensor 13 of the filter state detection device 12. When it is determined to start the regeneration process, the regeneration process control unit 11 controls the injector 10 to inject fuel into the exhaust pipe 3 and causes the oxidation catalyst 6 to react to heat the exhaust gas. In addition, the regeneration process control unit 11 controls the valve 9 to close the exhaust pipe 3, thereby increasing the load of the internal combustion engine 1 and raising the temperature of the exhaust gas. At this time, the regeneration process control unit 11 controls the regeneration process of the filter 7 based on the temperature information input from the temperature sensors 8a and 8b.

[0034] In addition, in order to control the regeneration process of the filter 7, a reference differential pressure between the upstream side and the downstream side of the filter 7 corresponding to the flow rate of the exhaust gas is preset in the regeneration process control unit 11. In addition, the flow rate of the exhaust gas is sequentially input from the internal combustion engine control unit 4 to the regeneration process control unit 11. The regeneration process control unit 11 sequentially calculates the reference differential pressure of the filter 7 based on the flow rate of the exhaust gas input from the internal combustion engine control unit 4.

[0035] It should be noted that, for example, a map showing the change in the differential pressure of the filter 7 with respect to the flow rate of the exhaust gas can be created through simulation or the like to set the reference differential pressure of the filter 7.

[0036] The filter state detection device 12 includes: a differential pressure sensor 13, a calculation unit 14, a determination unit 15, a notification unit 16, a communication unit 17, and an information providing unit 18. The differential pressure sensor 13 is connected to the determination unit 15 via the calculation unit 14. The calculation unit 14 is also connected to the regeneration process control unit 11. Moreover, the determination unit 15 is respectively connected to the notification unit 16 and the communication unit 17, and the communication unit 17 is connected to the information providing unit 18 through wireless communication.

[0037] The differential pressure sensor 13 is disposed in the exhaust pipe 3 and detects the differential pressure of the filter between the upstream side and the downstream side of the filter 7.

[0038] The calculation unit 14 calculates the pressure ratio between the reference differential pressure of the filter 7 calculated by the regeneration process control unit 11 and the differential pressure of the filter 7 detected by the differential pressure sensor 13.

[0039] The determination unit 15 estimates the accumulation amount of ash in the filter 7 based on the pressure ratio calculated by the calculation unit 14. Then, the determination unit 15 determines the maintenance period of the filter 7 based on the estimated accumulation amount of ash.

[0040] The notification unit 16 notifies the user of the vehicle of the determination result determined by the determination unit 15. The notification unit 16 can be constituted by, for example, a display unit and a speaker, etc.

[0041] The communication unit 17 wirelessly transmits the determination result determined by the determination unit 15 to the information providing unit 18.

[0042] Based on the determination result transmitted from the communication unit 17, the information providing unit 18 provides the maintenance period of the filter to the user of the vehicle. The information providing unit 18 can be set in, for example, a vehicle management company, a vehicle repair shop, and a dealer, etc.

[0043] It should be noted that the functions of the internal combustion engine control unit 4, the regeneration process control unit 11, the calculation unit 14, and the determination unit 15 can also be realized by a computer program. For example, a reading device of a computer reads the program from a recording medium recording a program for realizing the functions of the internal combustion engine control unit 4, the regeneration process control unit 11, the calculation unit 14, and the determination unit 15, and stores it in a storage device. Then, the CPU copies the program stored in the storage device to the RAM, sequentially reads and executes the commands included in the program from the RAM, thereby being able to realize the functions of the internal combustion engine control unit 4, the regeneration process control unit 11, the calculation unit 14, and the determination unit 15.

[0044] Next, the operation of this embodiment will be described.

[0045] First, as Figure 1 shown, after the internal combustion engine control unit 4 controls the internal combustion engine 1 to make the vehicle run, the exhaust gas generated by the internal combustion engine 1 flows through the exhaust pipe 3 and is discharged to the outside. At this time, the exhaust gas passes through the filter 7, so that particulate matters such as oil fume components and ashes contained in the exhaust gas are captured by the filter 7.

[0046] In this way, particulate matters accumulate on the filter 7, and as the accumulation amount increases, the filter pressure difference between the upstream side and the downstream side of the filter 7 rises. Therefore, the differential pressure sensor 13 sequentially detects the filter pressure difference of the filter 7. Then, the regeneration process control unit 11 determines the start timing of the regeneration process for burning and removing the particulate matters accumulated on the filter 7 based on the filter pressure difference detected by the differential pressure sensor 13.

[0047] For example, the regeneration process control unit 11 can determine that the regeneration process of the filter 7 starts when the filter pressure difference detected by the differential pressure sensor 13 exceeds a specified threshold for a fixed period.

[0048] After it is determined that the regeneration process of the filter 7 starts, the regeneration process control unit 11 controls the injector 10 based on the temperatures detected by the temperature sensors 8a and 8b, and causes the injector 10 to inject fuel, such as light oil, into the exhaust pipe 3. Thereby, the oxidation catalyst 6 oxidizes the fuel injected from the injector 10, and heats the exhaust gas to a high temperature using the reaction heat. In addition, the regeneration process control unit 11 controls the valve 9 to close the exhaust pipe 3, so as to raise the temperature of the exhaust gas.

[0049] In this way, the exhaust gas heated to a high temperature passes through the filter 7, so that the soot component of the particulate matter accumulated on the filter 7 burns, and the filter 7 undergoes a regeneration process. Then, if the regeneration process of the filter 7 ends, the regeneration process control unit 11 controls the valve 9 to stop the injector 10 and open the exhaust pipe 3.

[0050] Through the regeneration process of the filter 7, the particulate matter accumulated on the filter 7 is removed, and the particulate matter contained in the exhaust gas is captured by the filter 7 again. Here, not only the combustible soot component in the particulate matter accumulates on the filter 7, but also the incombustible ash accumulates. Therefore, through the regeneration process of the filter 7, the soot component is removed, while the ash still accumulates on the filter 7.

[0051] Therefore, in order to infer the accumulation amount of the ash accumulated on the filter 7, the calculation unit 14 acquires the filter differential pressure of the filter 7 detected by the differential pressure sensor 13 immediately after the regeneration process of the filter 7 is performed. For example, as Figure 2 shown, the calculation unit 14 sequentially acquires the filter differential pressure detected by the differential pressure sensor 13 at fixed intervals within a specified time from the time S1 when the regeneration process of the filter 7 is completed to the time S2.

[0052] In addition, the calculation unit 14 acquires the reference differential pressure of the filter 7 calculated by the regeneration process control unit 11. Here, a map representing the change in the differential pressure of the filter 7 with respect to the flow rate of the exhaust gas is preset in the regeneration process control unit 11. In addition, the regeneration process control unit 11 sequentially acquires the flow rate of the exhaust gas that changes as the internal combustion engine 1 is driven from the internal combustion engine control unit 4. The regeneration process control unit 11 sequentially calculates the reference differential pressures on the upstream side and the downstream side of the filter 7 corresponding to the flow rate of the exhaust gas acquired from the internal combustion engine control unit 4 based on the preset map.

[0053] In this way, by setting the change in the differential pressure of the filter 7 with respect to the flow rate of the exhaust gas as a map, the regeneration process control unit 11 can easily calculate the reference differential pressure of the filter 7. The regeneration process control unit 11 outputs the calculated reference differential pressure of the filter 7 to the calculation unit 14.

[0054] In this way, the calculation unit 14 sequentially inputs the filter differential pressure of the filter 7 detected by the differential pressure sensor 13 and the reference differential pressure of the filter 7 calculated by the regeneration process control unit 11. Moreover, the calculation unit 14 calculates the pressure ratio between the filter differential pressure of the filter 7 detected by the differential pressure sensor 13 and the reference differential pressure of the filter 7 corresponding to the exhaust gas flow rate at the time when the filter differential pressure is detected.

[0055] For example, as Figure 3 shown, the calculation unit 14 calculates the pressure ratio between the filter differential pressure detected by the differential pressure sensor 13 and the reference differential pressure corresponding to the filter differential pressure within a specified time. Moreover, the calculation unit 14 can calculate the pressure ratio immediately after the regeneration process of the filter 7 by approximating the calculated multiple pressure ratios with the approximate formula E. The calculation unit 14 outputs the calculated pressure ratio to the determination unit 15.

[0056] It should be noted that the calculation unit 14 is not limited to approximating multiple pressure ratios with the approximate formula E. For example, the pressure ratio immediately after the regeneration process of the filter 7 can also be calculated by taking the average value of multiple pressure ratios.

[0057] Next, the determination unit 15 infers the amount of ash accumulation in the filter 7 based on the pressure ratio calculated by the calculation unit 14. For example, the map stored in the regeneration process control unit 11 is preset based on a filter 7 in which a specified amount of particulate matter is accumulated, for example, a filter 7 that is entirely filled with particulate matter. In this case, the closer the pressure ratio is to 1, the more the determination unit 15 infers that the amount of ash accumulation is, and the closer the pressure ratio is to 0, the less the determination unit 15 infers that the amount of ash accumulation is.

[0058] Here, as Figure 2 shown, the filter differential pressure detected by the differential pressure sensor 13 varies greatly due to the detection time corresponding to the exhaust gas flow rate and the like. Specifically, as calculated based on Bernoulli's theorem, the filter differential pressure is proportional to the square of the exhaust gas flow rate. For example, if the exhaust gas flow rate becomes 1.2 times, the filter differential pressure becomes 1.44 times.

[0059] In the past, the amount of ash accumulation in the filter 7 was directly calculated based on the filter differential pressure detected by the differential pressure sensor 13. Therefore, the calculated value varies greatly corresponding to the exhaust gas flow rate, and it may not be possible to accurately infer the amount of ash accumulation. In order to suppress the variation of this calculated value, for example, the filter differential pressure of the filter 7 is detected in a state where the vehicle is stopped and the operation amount of the accelerator is maintained constant, and a lot of effort is required to infer the amount of ash accumulation.

[0060] Therefore, in the present invention, the determination unit 15 calculates the accumulation amount of ash in the filter 7 based on the pressure ratio between the reference pressure difference of the filter 7 set in advance and the filter pressure difference detected by the differential pressure sensor 13. In this method, for example, when the flow rate of the exhaust gas becomes 1.2 times, both the filter pressure difference and the reference pressure difference become 1.44 times. Therefore, the pressure ratio remains constant regardless of the flow rate of the exhaust gas. Thereby, it is possible to suppress the calculated accumulation amount of ash from varying corresponding to the flow rate of the exhaust gas and to detect the state of the filter 7 with high accuracy.

[0061] In addition, since the pressure ratio is constant regardless of the flow rate of the exhaust gas, the determination unit 15 can calculate the accumulation amount of ash while the vehicle is running. Therefore, for example, it is possible to simply calculate the accumulation amount of ash without performing operations such as maintaining the operation amount of the accelerator constant.

[0062] In addition, the calculation unit 14 calculates the pressure ratio based on a plurality of filter pressure differences sequentially detected by the differential pressure sensor 13 within a specified time. Therefore, the determination unit 15 can accurately infer the accumulation amount of ash in the filter 7 based on the pressure ratio calculated by the calculation unit 14.

[0063] At this time, preferably, the calculation unit 14 sequentially acquires the filter pressure differences within about 1 hour after the end of the regeneration process of the filter 7.

[0064] It should be noted that preferably, the calculation unit 14 calculates the pressure ratio based on the filter pressure difference when the internal combustion engine 1 is operating near the rated state among the plurality of filter pressure differences sequentially detected by the differential pressure sensor 13 within a specified time. The calculation unit 14, for example, acquires the operation information of the internal combustion engine 1 from the internal combustion engine control unit 4 and obtains the time period during which the internal combustion engine 1 is operating near the rated state based on this operation information. Then, the calculation unit 14 calculates the pressure ratio according to the filter pressure difference detected by the differential pressure sensor 13 within this time period. Thereby, the calculation unit 14 can accurately calculate the pressure ratio.

[0065] In addition, the calculation unit 14 calculates the pressure ratio based on the reference pressure difference preset for the filter 7 in which particulate matter is entirely accumulated and the filter pressure difference detected by the differential pressure sensor 13 immediately after the regeneration process of the filter 7, that is, the filter pressure difference of the filter 7 in a state where the oil fume component is basically removed and only ash is accumulated. Therefore, the determination unit 15 can accurately infer the accumulation amount of ash in the filter 7 based on this pressure ratio.

[0066] In this way, as Figure 4As shown, each time the regeneration process of the filter 7 is performed, the calculation unit 14 calculates the pressure ratio between the reference pressure difference of the filter 7 set in advance and the pressure difference of the filter detected by the differential pressure sensor 13. Next, the determination unit 15 infers the accumulation amount of ash in the filter 7 based on the pressure ratio calculated by the calculation unit 14. Moreover, the determination unit 15 determines the maintenance period of the filter 7 based on the inferred accumulation amount of ash.

[0067] For example, a threshold value T of the pressure ratio for which maintenance of the filter 7 is required is set in advance in the determination unit 15. The closer the pressure ratio is to the threshold value T, the more the determination unit 15 infers that the accumulation amount of ash in the filter 7 is. Moreover, when the pressure ratio exceeds the threshold value T, the determination unit 15 infers that a prescribed amount of ash has accumulated on the filter 7 and determines that maintenance of the filter 7 is required.

[0068] The determination unit 15 outputs the determination result to the notification unit 16 and outputs it to the information providing unit 18 via the communication unit 17. Moreover, based on the determination result of the determination unit 15, the notification unit 16 notifies the user of the vehicle by displaying the maintenance period of the filter 7 or the like. In addition, based on the determination result of the determination unit 15, the information providing unit 18 provides it to the user of the vehicle in association with the maintenance period of the filter 7 or the like.

[0069] In this way, by providing the maintenance period of the filter 7, the user of the vehicle can effectively perform maintenance such as cleaning and replacement of the filter 7.

[0070] Furthermore, when the pressure ratio calculated by the calculation unit 14 exceeds 1.0, the determination unit 15 can determine a malfunction of a device other than the filter 7. The determination unit 15 can determine that, for example, due to malfunctions of devices such as the internal combustion engine 1, the oxidation catalyst 6, the valve 9, and the injector 10, the exhaust gas is not heated to a high temperature.

[0071] According to the present embodiment, the determination unit 15 infers the accumulation amount of ash in the filter 7 based on the pressure ratio between the reference pressure difference of the filter 7 set in a manner corresponding to the flow rate of the exhaust gas and the pressure difference of the filter detected by the differential pressure sensor 13, and thus can detect the state of the filter 7 with high accuracy.

[0072] (Embodiment 2)

[0073] Hereinafter, Embodiment 2 of the present invention will be described. Here, the description will be centered on the differences from the above-described Embodiment 1, and for the same points as those of the above-described Embodiment 1, the same reference numerals will be used and their detailed description will be omitted.

[0074] In the above-described Embodiment 1, the determination unit 15 infers the accumulation amount of ash in the filter 7, but it is not limited thereto, and as long as the accumulation amount of particulate matter in the filter 7 can be inferred.

[0075] For example, as Figure 5 shown, the determination unit 21 can be arranged to replace the determination unit 15 of Embodiment 1, and the regeneration processing control unit 22 can be arranged to replace the regeneration processing control unit 11. The determination unit 21 is connected to the regeneration processing control unit 22.

[0076] Based on the pressure ratio calculated by the calculation unit 14, the determination unit 21 infers the accumulation amount of particulate matter containing oil fume components and ash accumulated on the filter 7.

[0077] Based on the accumulation amount of particulate matter inferred by the determination unit 21, the regeneration processing control unit 22 determines the timing to start the regeneration processing of the filter 7.

[0078] With such a structure, the calculation unit 14 obtains the filter differential pressure detected by the differential pressure sensor 13 when the internal combustion engine 1 is driven, and sequentially calculates the pressure ratio of the reference differential pressure of the filter 7 preset corresponding to the flow rate of the exhaust gas to the filter differential pressure detected by the differential pressure sensor 13. The calculation unit 14 outputs the calculated pressure ratio to the determination unit 21.

[0079] Next, based on the pressure ratio calculated by the calculation unit 14, the determination unit 21 infers the accumulation amount of particulate matter accumulated on the filter 7. Here, similarly to Embodiment 1, the mapping stored in the regeneration processing control unit 22 is preset based on the filter 7 that is entirely filled with particulate matter. In this case, the closer the pressure ratio is to 1, the more the determination unit 21 infers the accumulation amount of particulate matter, and the closer the pressure ratio is to 0, the less the determination unit 21 infers the accumulation amount of particulate matter.

[0080] A threshold value of the pressure ratio for implementing the regeneration processing of the filter 7 is preset in the determination unit 21. When the pressure ratio exceeds the threshold value, it is inferred that a specified amount of particulate matter has accumulated on the filter 7. The determination unit 21 outputs the accumulation amount of particulate matter to the regeneration processing control unit 22.

[0081] Moreover, when the determination unit 21 infers that a specified amount of particulate matter has accumulated on the filter 7, the regeneration processing control unit 22 determines to start the regeneration processing of the filter 7.

[0082] In the past, the regeneration processing control unit 22 determined the timing to start the regeneration processing of the filter 7 based on the filter differential pressure detected by the differential pressure sensor 13. Therefore, the timing to start the regeneration processing of the filter 7 varies corresponding to the flow rate of the exhaust gas, and it is difficult to start the regeneration processing of the filter when a fixed accumulation amount of particulate matter has accumulated on the filter 7.

[0083] Therefore, in the present invention, the determination unit 21 infers the accumulation amount of particulate matter in the filter 7 based on the pressure ratio between the reference differential pressure of the filter 7 preset in a manner corresponding to the flow rate of the exhaust gas and the differential pressure of the filter detected by the differential pressure sensor 13. Moreover, the regeneration processing control unit 22 determines the timing to start the regeneration processing of the filter 7 based on the accumulation amount of particulate matter in the filter 7 inferred by the determination unit 21. Therefore, the regeneration processing of the filter 7 can be performed when a fixed accumulation amount of particulate matter has accumulated on the filter 7, and the regeneration processing of the filter 7 can be implemented at an appropriate timing.

[0084] In this way, if it is determined to start the regeneration processing of the filter 7, the regeneration processing control unit 22 controls the ejector 10 and the valve 9 to heat the exhaust gas to a high temperature. Thereby, the oil fume component of the particulate matter accumulated on the filter 7 burns, and the filter 7 is subjected to regeneration processing.

[0085] According to the present embodiment, the determination unit 21 infers the accumulation amount of particulate matter in the filter 7 based on the pressure ratio between the reference differential pressure of the filter 7 preset in a manner corresponding to the flow rate of the exhaust gas and the differential pressure of the filter detected by the differential pressure sensor 13. Therefore, the regeneration processing control unit 22 can appropriately determine the timing to start the regeneration processing of the filter 7 based on the accumulation amount of particulate matter in the filter 7 inferred by the determination unit 21.

[0086] It should be noted that in the above-described Embodiments 1 and 2, the calculation unit 14 calculates the pressure ratio based on a plurality of differential pressures of the filter detected by the differential pressure sensor 13 within a predetermined time, but the pressure ratio may also be calculated based on a single differential pressure of the filter.

[0087] In addition, in the above-described Embodiments 1 and 2, the calculation unit 14 preset the reference differential pressure based on the filter 7 that is entirely filled with particulate matter, but it is not limited thereto, as long as the reference differential pressure can be set corresponding to the flow rate of the exhaust gas. For example, the calculation unit 14 may also set the reference differential pressure based on the filter 7 without accumulated particulate matter.

[0088] In addition, in the above-described Embodiments 1 and 2, the calculation unit 14 and the determination unit 15 are arranged on the vehicle, but they may also be arranged externally and communicate with each other through a communication line.

[0089] In addition, in the above-described Embodiments 1 and 2, the regeneration processing control unit controls the ejector 10 to heat the exhaust gas to a high temperature, but it is not limited to the ejector 10, as long as the exhaust gas can be heated to a high temperature by using the reaction heat of the oxidation catalyst 6.

[0090] For example, the regeneration processing control unit may control the multi-stage injection of the internal combustion engine 1 to cause the oxidation catalyst 6 to react.

[0091] It should be noted that the above embodiments only represent an example of the implementation of the present invention, and the technical scope of the present invention should not be limited by these embodiments. That is, the present invention can be implemented in various forms without departing from its gist or its main features. For example, the disclosure of the shape, number, etc. of each part described in the above embodiments is only an example, and appropriate changes can be made before implementation.

[0092] This application is based on Japanese Patent Application (Japanese Patent Application No. 2020-094321) filed on May 29, 2020, the content of which is incorporated herein by reference.

[0093] Industrial Applicability

[0094] The filter state detection device of the present invention can be used for a device in which a filter for capturing particulate matter contained in exhaust gas is disposed in an exhaust pipe.

[0095] Explanation of Reference Numerals

[0096] 1 Internal combustion engine

[0097] 2 Intake pipe

[0098] 3 Exhaust pipe

[0099] 4 Internal combustion engine control unit

[0100] 5 Purification device

[0101] 6 Oxidation catalyst

[0102] 7 Filter

[0103] 8a, 8b Temperature sensors

[0104] 9 Valve

[0105] 10 Injector

[0106] 11, 22 Regeneration processing control unit

[0107] 12 Filter state detection device

[0108] 13 Differential pressure sensor

[0109] 14 Calculation unit

[0110] 15, 21 Judgment unit

[0111] 16 Notification unit

[0112] 17 Communication unit

[0113] 18 Information providing unit

[0114] S1, S2 Time

[0115] E Approximation formula

[0116] T threshold

Claims

1. A filter state detection device, comprising: A differential pressure sensor that detects the filter differential pressure between the upstream side and the downstream side of the filter, the filter being disposed in the exhaust pipe to capture particulate matter contained in the exhaust gas of the vehicle; A calculation unit that calculates the pressure ratio between the reference differential pressure between the upstream side and the downstream side of the filter preset in a manner corresponding to the flow rate of the exhaust gas and the filter differential pressure detected by the differential pressure sensor; And A determination unit that infers the accumulation amount of the particulate matter in the filter based on the pressure ratio calculated by the calculation unit, The calculation unit calculates the pressure ratio based on a plurality of filter differential pressures detected by the differential pressure sensor within a specified time and a plurality of reference differential pressures respectively calculated according to the flow rate of the exhaust gas that changes within the specified time.

2. The filter state detection device according to claim 1, Wherein, The calculation unit calculates the pressure ratio by approximating or averaging a plurality of pressure ratios calculated based on the plurality of filter differential pressures and the plurality of reference differential pressures.

3. The filter state detection device according to claim 1, Wherein, The calculation unit calculates the pressure ratio between the reference differential pressure preset based on the filter in which a specified amount of the particulate matter has accumulated and the filter differential pressure detected by the differential pressure sensor immediately after the regeneration process of burning the particulate matter accumulated on the filter.

4. The filter state detection device according to claim 3, Wherein, The calculation unit calculates the pressure ratio each time the regeneration process is performed.

5. The filter state detection device according to claim 1, Wherein, The determination unit infers the accumulation amount of the ash in the particulate matter.

6. The filter state detection device according to claim 5, Wherein, The determination unit determines the maintenance period of the filter based on the inferred accumulation amount of the ash.

7. The filter state detection device according to claim 6, Wherein, It further has: A communication unit that wirelessly transmits the determination result determined by the determination unit; And An information providing unit that provides the maintenance period of the filter to the user of the vehicle based on the determination result transmitted from the communication unit.

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