Exhaust purification equipment

Abstract

To provide an exhaust emission control device capable of obtaining a more accurate ash accumulation amount in a filter without depending on an assumption of a PM accumulation amount.SOLUTION: An exhaust emission control device 30 includes: a DPF device 41 for collecting particulate matters included in exhaust gas of an internal combustion engine; a counting section 51 acquiring a count accumulation amount by counting an ash accumulation amount in the DPF device 41 on the basis of an operating time of the internal combustion engine; pressure sensors 43, 44 for acquiring differential pressure of exhaust gas before and after the DPF device 41; a calculation section 53 for acquiring a calculated accumulation amount by calculating a current ash accumulation amount from an ash accumulation amount corresponding to cleaning reference differential pressure on the basis of a comparison between current treated differential pressure and the cleaning reference differential pressure through communication with a data center A; and a correction section 54 for correcting the count accumulation amount to the calculated accumulation amount.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present disclosure relates to an exhaust purification device. [Background technology]

[0002] Patent Document 1 describes an ash accumulation amount estimation device. This device is configured to store data on the differential pressure between the exhaust inlet and exhaust outlet of the DPF, detected by a DPF differential pressure sensor, and the exhaust flow rate calculated by an exhaust flow rate calculation device in a storage device, and estimate the ash accumulation amount after the end of the DPF regeneration process based on the differential pressure and exhaust flow rate data stored in the storage device during a period immediately before the end of regeneration, up to a predetermined time retroactively from the end of the DPF regeneration process. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2020-002824 A Summary of the Invention [Problem to be solved by the invention]

[0004] In the device described in Patent Document 1 above, in the period immediately prior to the completion of DPF regeneration, the exhaust temperature is maintained within a predetermined range, so fluctuations in differential pressure and exhaust flow rate are small, and PM that would interfere with estimation of ash accumulation amount is also sufficiently incinerated, making it possible to accurately estimate the ash accumulation amount.

[0005] However, this method requires that the exhaust gas flow rate and PM accumulation amount conditions are consistent, and is premised on complete combustion of the PM on the DPF. Therefore, when the DPF regeneration method is mainly performed in a continuous regeneration mode, which leaves a certain amount of PM accumulation in the DPF, the accuracy of the estimation of the ash accumulation amount may decrease.

[0006] Therefore, an object of the present disclosure is to provide an exhaust gas purification device that can obtain a more accurate amount of ash accumulation in a filter, regardless of the premise of the amount of PM accumulation. [Means for solving the problem]

[0007] The exhaust purification device of the present disclosure comprises a filter provided in an exhaust passage of an internal combustion engine for capturing particulate matter contained in exhaust gas of the internal combustion engine, a counting unit for counting the amount of ash accumulation in the filter based on the operating time of the internal combustion engine to obtain the counted accumulation amount, a pressure sensor for obtaining the differential pressure of the exhaust gas before and after the filter in the exhaust passage, a calculation unit for calculating a current ash accumulation amount from the ash accumulation amount equivalent to the cleaning standard differential pressure based on a comparison between the current processed differential pressure and the cleaning standard differential pressure by communicating with a data center to make an ash cleaning request for the filter when a processed differential pressure obtained by long-term averaging and smoothing processing of the differential pressure obtained by the pressure sensor reaches a cleaning standard differential pressure, and a correction unit for correcting the counted accumulation amount to the calculated accumulation amount.

[0008] In this device, the counting unit counts the amount of ash deposited on the filter based on the operating time of the internal combustion engine to obtain the counted amount of ash deposited on the filter. This allows the amount of ash deposited on the filter to be obtained at all times. Meanwhile, in this device, the calculation unit communicates with a data center to request ash cleaning of the filter when the processed differential pressure obtained by the long-term averaging and smoothing of the differential pressure of the exhaust gas before and after the filter reaches the cleaning reference differential pressure, thereby calculating the current ash deposition amount from the ash deposition amount corresponding to the cleaning reference differential pressure based on a comparison between the current differential pressure, which is the current differential pressure, and the cleaning reference differential pressure to obtain the calculated deposition amount. Then, in this device, the correction unit corrects the counted deposition amount to the calculated deposition amount. Therefore, the ash deposition amount is corrected to a more accurate value at least at the time interval at which the long-term average of the differential pressure is obtained. Therefore, according to this device, a more accurate ash deposition amount can be obtained regardless of the assumption of the amount of PM deposited on the filter.

[0009] In the exhaust gas purification device according to the present disclosure, the correction unit may correct a parameter indicating a relationship between the operation time of the internal combustion engine when the counting unit counts the counted accumulation amount and the ash accumulation amount, based on the counted accumulation amount and the calculated accumulation amount. In this case, after the correction by the correction unit, the ash accumulation amount obtained by the counting unit based on the operation time of the internal combustion engine becomes more accurate.

[0010] In the exhaust gas purification device according to the present disclosure, the correction unit may correct the differential pressure threshold for performing particulate matter combustion regeneration of the filter based on the counted accumulation amount or the calculated accumulation amount. In this case, more regeneration requests than necessary due to ash accumulation in the filter are suppressed. Effect of the Invention

[0011] According to the present disclosure, it is possible to provide an exhaust gas purification device that is capable of obtaining a more accurate amount of ash accumulation in a filter, regardless of the premise of the amount of PM accumulation. [Brief description of the drawings]

[0012] [Figure 1] FIG. 1 is a schematic diagram showing an exhaust gas purification device according to one embodiment. [Diagram 2] FIG. 2 is a diagram showing a functional configuration of the ECU shown in FIG. [Diagram 3] FIG. 3 is a graph showing the treated differential pressure and the count accumulation amount. [Figure 4] FIG. 4 is a graph showing the threshold differential pressure for filter regeneration. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] Hereinafter, an exhaust gas purification device according to an embodiment will be described with reference to the drawings. In each drawing, the same or corresponding elements are denoted by the same reference numerals, and duplicated explanations will be omitted.

[0014] FIG. 1 is a schematic diagram showing an exhaust purification device according to one embodiment. The exhaust purification device 30 shown in FIG. 1 is mounted on large vehicles such as buses and trucks, and industrial vehicles, and is intended to purify exhaust gas generated by an engine (internal combustion engine) 10. The vehicle on which the exhaust purification device 30 is mounted may be, for example, a so-called series type hybrid vehicle that uses the engine 10 as a power source for generating electricity. Here, carbon monoxide (NO) and carbon dioxide (NO 2 ) are collectively referred to as nitrogen oxides (NOx).

[0015] The engine 10 is an internal combustion engine such as a diesel engine, and is driven when the remaining capacity of the battery is low (for example, in the case of a hybrid vehicle). The engine 10 has a plurality of cylinders 10a. An intake manifold 12 that supplies air to the cylinders 10a and an exhaust manifold 13 that discharges exhaust gas from the cylinders 10a are connected to the plurality of cylinders 10a.

[0016] An intake passage 14 is connected to the intake manifold 12. A compressor 15 and an intercooler 16 are provided in this order from the upstream side of the intake air in the intake passage 14. An introduction pipe 17 into which the intake air flows is connected to the compressor 15. An air cleaner 18 is provided in the introduction pipe 17.

[0017] An exhaust passage 20 is connected to the exhaust manifold 13 via a turbine 19. The turbine 19 is connected to the compressor 15 via a connecting shaft. The turbine 19 is rotated by the flow of exhaust gas discharged from the exhaust manifold 13 of the engine 10. The compressor 15 rotates with the rotation of the turbine 19, takes in air (intake air) from an intake pipe 17, and sends the compressed air to the intake passage 14. In other words, the compressor 15 and the turbine 19 constitute a turbocharger. The air introduced into the intake passage 14 is introduced into the multiple cylinders 10a through the intake manifold 12. The air introduced into the multiple cylinders 10a is compressed in each cylinder 10a.

[0018] Additionally, a plurality of injectors 24 are provided in proximity to the plurality of cylinders 10a of the engine 10. A fuel supply passage 23 is connected to the plurality of injectors 24. A fuel pump is connected to the fuel supply passage 23. The fuel pump pumps fuel, such as diesel, stored in a fuel tank through the fuel supply passage to the plurality of injectors. The plurality of injectors 24 inject the fuel supplied from the fuel tank into each of the plurality of cylinders 10a.

[0019] Fuel from the injector 24 is injected into the compressed air and combusted in each cylinder 10a, causing a piston disposed in each cylinder 10a to reciprocate within the cylinder 10a. The reciprocating motion of the piston drives the engine 10.

[0020] The exhaust purification device 30 includes a purification unit 40 provided in the exhaust passage 20. The purification unit 40 has a DPF (Diesel Particulate Filter) device (filter) 41 arranged in the exhaust passage 20. The DPF device 41 is, for example, a ceramic filter having a large number of air holes formed therein, and is intended to collect particulate matter (PM: Particulate Matter) contained in the exhaust gas.

[0021] The purification unit 40 also has a DOC (Diesel Oxidation Catalyst) device 42 arranged upstream of the exhaust gas from the DPF device 41. The DOC device 42 includes, for example, a ceramic carrier and an oxidation catalyst supported on the carrier, and oxidizes and purifies hydrocarbons (HC), carbon monoxide (CO), and the like contained in the exhaust gas. Examples of the oxidation catalyst included in the DOC device 42 include precious metal catalysts such as platinum, rhodium, and palladium.

[0022] Furthermore, the purification unit 40 has a pressure sensor 43 and a pressure sensor 44 arranged in this order from the upstream side to the downstream side of the exhaust gas. The pressure sensor 43 is provided between the DOC device 42 and the DPF device 41 and / or on the upstream side of the DOC device 42, and detects the pressure of the exhaust gas. The pressure sensor 44 is provided downstream of the DPF device 41, and detects the pressure of the exhaust gas. In this way, the pressure sensors 43, 44 detect the pressure of the exhaust gas before and after (upstream and downstream) the DPF device 41, and thereby can obtain the differential pressure of the exhaust gas before and after the DPF device 41 in the exhaust passage 20 (hereinafter sometimes simply referred to as the "differential pressure of the DPF device 41").

[0023] Here, the exhaust purification device 30 includes an ECU (Electronic Control Unit) 50. The operation of the ECU 50 will be described in detail later. The ECU 50 is an electronic control unit having a CPU (Central Processing Unit), a ROM (Read Only Memory), a RAM (Random Access Memory), a CAN (Controller Area Network) communication circuit, and the like. The ECU 50 loads a program stored in the ROM into the RAM, and executes the program loaded into the RAM by the CPU, thereby realizing the functions of each part, which will be described later. The ECU 50 may be composed of multiple electronic control units.

[0024] The ECU 50 is configured to be able to acquire information from the pressure sensors 43, 44. This allows the ECU 50 to acquire the differential pressure of the DPF device 41 acquired by the pressure sensors 43, 44. The ECU 50 is also configured to be able to communicate with a data center A installed outside the vehicle, and is able to send and receive information to and from the data center A.

[0025] The data center A periodically acquires the differential pressure of the DPF device 41 via the ECU 50, for example, and periodically calculates the processed differential pressure by long-term averaging and smoothing of the differential pressure acquired by the pressure sensors 43, 44. The data center A then transmits the calculated processed differential pressure to the ECU 50, and transmits a signal to the ECU 50 to request ash cleaning of the DPF device 41 when the processed differential pressure reaches the cleaning reference differential pressure. Ash is, for example, derived from oil contained in exhaust gas, and is ash content including, for example, zinc compounds, calcium compounds, etc.

[0026] Fig. 2 is a diagram showing a functional configuration of the ECU shown in Fig. 1. As shown in Fig. 2, the ECU 50 has a counting unit 51, a communication unit 52, a calculation unit 53, and a correction unit 54. The counting unit 51 counts the amount of ash accumulated in the DPF device 41 based on the operating time of the vehicle or the engine 10, and acquires the counted amount of ash. The graph in Fig. 3 (counted amount of ash accumulated C1 to C3) is an example of the counted amount of ash accumulated.

[0027] The communication unit 52 communicates with the pressure sensors 43, 44 and the data center A. The communication unit 52 receives information indicating the differential pressure of the DPF device 41 from the pressure sensors 43, 44, and transmits information indicating the acquired differential pressure to the data center A. As described above, the communication unit 52 receives information indicating the processed differential pressure from the data center A, and receives a signal related to an ash cleaning request from the data center A. When the ECU 50 receives the signal related to the ash cleaning request, it can notify a vehicle occupant or operator that ash cleaning of the DPF device 41 will be performed.

[0028] The calculation unit 53 calculates the current ash accumulation amount from the ash accumulation amount corresponding to the cleaning standard differential pressure based on a comparison between the current differential pressure, which is the current pressure difference obtained from the pressure sensors 43, 44 via the communication unit 52, and the cleaning standard differential pressure, to obtain the calculated accumulation amount. Then, the correction unit 54 corrects the counted accumulation amount obtained by the counting unit 51 to the calculated accumulation amount obtained by the calculation unit 53. The counting unit 51 continues counting the ash accumulation amount from the corrected value. Next, the operations of the data center A, the calculation unit 53, and the correction unit 54 will be described in more detail.

[0029] 3 is a graph showing the processed differential pressure and the count accumulation amount. In FIG. 3, the processed differential pressure D is plotted, which is generated by performing long-term averaging and smoothing processing in the data center A based on the differential pressure of the DPF device 41 acquired from the pressure sensors 43, 44 via the ECU 50. It can be understood that the processed differential pressure D gradually increases based on the accumulation of ash in the DPF device 41 as the operating time (horizontal axis) of the vehicle / engine 10 increases. When the processed differential pressure D reaches (or is predicted to reach) the cleaning reference differential pressure (cleaning threshold value in the graph), the data center A transmits a signal indicating a request for ash cleaning of the DPF device 41 to the ECU 50.

[0030] Meanwhile, the data center A transmits information related to the generated treated differential pressure D to the ECU 50. As described above, in the ECU 50, the counting unit 51 counts the amount of ash accumulation in the DPF device 41 based on the operating time of the vehicle or engine 10, and acquires the counted accumulation amounts C1, C2, and C3. The calculation unit 53 holds in advance an accumulation amount threshold, which is the amount of ash accumulation in the DPF device 41 that corresponds to the cleaning reference differential pressure of the treated differential pressure D (when the treated differential pressure D reaches the cleaning threshold), and calculates the current ash accumulation amount from the current treated differential pressure D received from the data center A based on this accumulation amount threshold, and acquires the calculated accumulation amount.

[0031] That is, the calculation unit 53 communicates with the data center A via the communication unit 52, and calculates the current ash accumulation amount from the ash accumulation amount corresponding to the cleaning standard differential pressure based on a comparison between the current differential pressure, which is the current treated differential pressure D, and the cleaning standard differential pressure, to obtain the calculated accumulation amount.

[0032] The calculated deposition amount thus obtained may deviate from the current counted deposition amount obtained by counting by the counting unit 51. For this reason, the correction unit 54 corrects the counted deposition amount to the calculated deposition amount in order to suppress the deviation between the calculated deposition amount and the counted deposition amount, for example, during regular maintenance of the vehicle. To explain this using the image in Figure 3, when the counted deposition amount at a certain point in time deviates from the calculated deposition amount calculated based on the processed differential pressure R1 at the same point in time, the counted deposition amount is corrected (corrected) to the calculated deposition amount P1 based on the processed differential pressure R1.

[0033] Furthermore, when the counted accumulation amount at a later time point deviates from the calculated accumulation amount calculated based on the processed differential pressure R2 at the same time, the correction unit 54 corrects (amends) the counted accumulation amount to the calculated accumulation amount P2 based on the processed differential pressure R2. When the counted accumulation amount at a later time point deviates from the calculated accumulation amount calculated based on the processed differential pressure R3 at the same time, the correction unit 54 corrects (amends) the counted accumulation amount to the calculated accumulation amount P3 based on the processed differential pressure R3.

[0034] In this manner, the ECU 50 repeatedly corrects the count at appropriate intervals, such as at regular maintenance intervals. This enables the ECU 50 to continue to hold an accurate ash accumulation amount even if PM remains in the DPF device 41.

[0035] On the other hand, the counting unit 51 acquires the counted accumulation amount of the DPF device 41 by applying an appropriate parameter to the operating time of the vehicle engine 10. As an example, the counting unit 51 acquires the counted accumulation amount by multiplying the operating time by an appropriate proportional constant. Therefore, when the calculated accumulation amount calculated based on the processed differential pressure D and the counted accumulation amount are deviated from each other at a certain point in time, the proportional constant (parameter) may not be appropriate. For this reason, the correction unit 54 further corrects a parameter (proportional constant in the above example) indicating the relationship between the operating time and the ash accumulation amount when the counting unit 51 counts the counted accumulation amount based on the counted accumulation amount and the calculated accumulation amount (for example, by comparison) during, for example, regular maintenance. As a result, the counted accumulation amount acquired by the counting unit 51 thereafter becomes more accurate.

[0036] Incidentally, the exhaust gas purification device 30 may perform filter regeneration, in which PM accumulated in the DPF device 41 is burned to regenerate the filter. More specifically, in the exhaust gas purification device 30, as shown in Fig. 4, a threshold value S1 of the differential pressure with respect to the flow rate is set in the initial state, and filter regeneration is performed when the differential pressure of the DPF device 41 at a certain flow rate reaches this threshold value S1. This threshold value S1 is a threshold value when the amount of ash accumulated in the DPF device 41 is 0. Therefore, when ash accumulates in the DPF device 41 and a differential pressure caused by the ash begins to occur, the differential pressure of the DPF device 41 (differential pressure due to PM accumulation + differential pressure due to ash accumulation) frequently reaches the threshold value S1, which may cause frequent filter regeneration and result in deterioration of fuel efficiency.

[0037] Therefore, the correcting unit 54 corrects the threshold value of the differential pressure that triggers filter regeneration from the initial threshold value S1 to another threshold value S2 or threshold value S3 based on the counted accumulation amount or the calculated accumulation amount. That is, the correcting unit 54 corrects the threshold value of the differential pressure that performs particulate matter combustion regeneration of the DPF device 41 based on the counted accumulation amount or the calculated accumulation amount. This suppresses frequent occurrence of filter regeneration, and suppresses the resulting deterioration of fuel efficiency. Note that the correcting unit 54 can also correct the threshold value from the threshold value S2 or threshold value S3 to the initial threshold value S1 after, for example, ash cleaning of the DPF device 41.

[0038] As described above, the exhaust purification device 30 and the counting unit 51 count the amount of ash accumulated in the DPF device 41 based on the operating time of the engine 10 to obtain the counted amount of accumulated ash. This allows the amount of ash accumulated in the DPF device 41 to be obtained at all times. Meanwhile, in the exhaust purification device 30, the calculation unit 53 communicates with the data center A to request ash cleaning of the DPF device 41 when the processed differential pressure D obtained by the long-term averaging and smoothing processes of the differential pressure of the exhaust gas before and after the DPF device 41 reaches the cleaning reference differential pressure, thereby calculating the current ash accumulation amount from the ash accumulation amount corresponding to the cleaning reference differential pressure based on a comparison between the current differential pressure, which is the current differential pressure, and the cleaning reference differential pressure, to obtain the calculated accumulation amount.

[0039] In the exhaust gas purification device 30, the correction unit 54 corrects the counted accumulation amount to the calculated accumulation amount. Therefore, the ash accumulation amount is corrected to a more accurate value at least at the time interval where the long-term average of the differential pressure is obtained. Therefore, according to the exhaust gas purification device 30, a more accurate ash accumulation amount can be obtained regardless of the premise of the PM accumulation amount in the DPF device 41.

[0040] Furthermore, in the exhaust purification device 30, the correction unit 54 corrects a parameter indicating the relationship between the operation time of the engine 10 when the counting unit 51 counts the counted accumulation amount and the ash accumulation amount, based on the counted accumulation amount and the calculated accumulation amount. Therefore, after the correction by the correction unit 54, the ash accumulation amount obtained by the counting unit 51 based on the operation time of the engine 10 becomes more accurate.

[0041] Furthermore, in the exhaust purification device 30, the correction unit 54 corrects the differential pressure threshold values ​​S1 to S3 for performing PM combustion regeneration of the DPF device 41, based on the counted accumulation amount or the calculated accumulation amount. This suppresses unnecessary requests for PM combustion regeneration caused by ash accumulation in the DPF device 41.

[0042] The above embodiment describes one aspect of the present disclosure. Therefore, the present disclosure is not limited to the above embodiment and may be modified as desired. [Explanation of symbols]

[0043] 10...engine (internal combustion engine), 20...exhaust passage, 30...exhaust purification device, 41...DPF device (filter), 43, 44...pressure sensor, 50...ECU, 51...counting unit, 53...calculation unit, 54...correction unit, A...data center.

Claims

1. a filter provided in an exhaust passage of an internal combustion engine for collecting particulate matter contained in exhaust gas from the internal combustion engine; A counting unit for counting an amount of ash accumulated in the filter based on an operating time of the internal combustion engine to obtain a counted amount of ash accumulated in the filter; a pressure sensor for acquiring a differential pressure of the exhaust gas before and after the filter in the exhaust passage; a calculation unit that calculates a current ash deposition amount from the ash deposition amount corresponding to the cleaning standard differential pressure based on a comparison between the current processed differential pressure and the cleaning standard differential pressure by communicating with a data center to request ash cleaning of the filter when a processed differential pressure obtained by long-term averaging and smoothing of the differential pressure acquired by the pressure sensor reaches the cleaning standard differential pressure, and acquires a calculated deposition amount; a correction unit that corrects the counted accumulation amount to the calculated accumulation amount during regular maintenance of the vehicle having the internal combustion engine; An exhaust purification device comprising:

2. The correction unit corrects a parameter indicating a relationship between the operation time of the internal combustion engine and the ash accumulation amount when the counting unit counts the count accumulation amount based on the count accumulation amount and the calculated accumulation amount. The exhaust gas purification device according to claim 1 .

3. The correction unit corrects a differential pressure threshold for performing particulate matter combustion regeneration of the filter based on the counted accumulation amount or the calculated accumulation amount.

3. An exhaust gas purification device according to claim 1 or 2.

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