JP2005002802A - Exhaust emission control device for diesel engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an exhaust emission control device for a diesel engine capable of closely controlling a change-over valve and improving durability of an exhaust after treatment filter. <P>SOLUTION: In this exhaust gas purifying device 1, clogging state of particulate PM in DPF 14 is determined by a pressure sensor 31. Since the clogging state of PM is accurately and instantaneously reflected as exhaust pressure flowing into the DPF 14, change-over control of the change-over valves 15, 16 is closely controlled in accordance with the clogging state of PM by monitoring the result of detection by the pressure sensor 31 by a controller 20. Even when exhaust gas reaches such high temperature and high pressure that affects the DPF 14 greatly, speedy determination is made without relying on a conventional unstable temperature sensor to control the change-over valves 15, 16, thereby improving durability of the DPF 14. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an exhaust gas purification device for a diesel engine.
[0002]
[Background]
Conventionally, it is known to provide an exhaust gas purification device in an exhaust passage of a diesel engine in order to collect particulates (particulate matter) in the exhaust gas discharged from the diesel engine.
As such an exhaust gas purification device, an exhaust gas after-treatment filter called a diesel particulate filter (hereinafter referred to as DPF (Diesel Particulate Filter)) has been developed. The DPF is formed, for example, in a columnar shape from a ceramic such as cordierite or silicon carbide, and has a large number of honeycomb-shaped small holes along the axial direction. The exhaust gas flows in from one end face of the DPF, passes through a porous partition wall (boundary wall) separating the small holes, and flows out from the other end face. When passing through the partition, particulates in the exhaust gas are collected on the partition surface.
[0003]
The collected particulates are usually self-combusted by being heated by the exhaust gas at a high temperature, but the exhaust gas temperature does not rise so much as when the idling operation continues. When the engine is running, it is difficult to self-combust the particulates and clogging occurs in the DPF. Therefore, in the exhaust gas purifying apparatus equipped with the DPF, by alternately changing the direction of the exhaust gas passing through the DPF, the particulates flowing in and collected from one end face of the DPF are collected on the other side. There are some which suppress the clogging without removing the particulates in the DPF by the exhaust gas flowing in from the exhaust gas and thus burning the particulates in the DPF (for example, Patent Document 1).
[0004]
Specifically, the DPF, a pair of upstream switching valves provided on the upstream side of the DPF, a pair of downstream switching valves provided on the downstream side of the exhaust aftertreatment filter, the upstream side and the downstream side And a control means for controlling the switching valve on the side, and the control means changes the flow direction of the exhaust gas flowing through the DPF by switching the opening and closing of each switching valve.
Further, by opening all the switching valves, it is possible to bypass the exhaust gas without flowing into the DPF and exhaust the exhaust gas as it is.
[0005]
[Patent Document 1]
JP 2002-13409 (FIG. 4, paragraph numbers 0022 to 0028)
[0006]
[Problems to be solved by the invention]
However, in the exhaust gas purification device described in Patent Document 1, although the temperature of the exhaust gas is detected by the temperature sensor, the switching of the switching valve is basically performed when a preset cumulative use limit time has elapsed. Therefore, if the particulate matter becomes clogged for some reason before reaching the cumulative use limit time, the flow of exhaust gas in the DPF cannot be changed immediately, and the switching valve control is not possible. There is a problem that it cannot be done precisely.
[0007]
Also, if the DPF is used for a long period of time, even if the switching valve is switched to change the flow of exhaust gas, the particulate clogging will not be resolved, and the DPF may be cleaned (washed) or replaced. I need it. In this regard, in Patent Document 1, the exhaust temperature on the downstream side of the DPF is detected by the temperature sensor, and when the detection result here exceeds the limit temperature for a predetermined time, it is determined that such a state has occurred. The switching valve is opened to bypass the exhaust gas, thereby protecting the DPF.
[0008]
This is to determine that the pressure on the upstream side of the DPF has abnormally increased due to clogging of the particulates by the abnormal increase in the exhaust temperature on the downstream side of the DPF (Patent Document 1, Paragraph No. 0026). However, when the exhaust gas flow rate on the downstream side of the DPF is small due to clogging, it takes time for the temperature detected by the temperature sensor to stabilize, and during that time, the upstream side of the DPF is damaged by exhaust gas that has become hot and high pressure. There is a problem that the durability of the DPF is reduced.
[0009]
An object of the present invention is to provide a diesel engine exhaust gas purifying apparatus capable of precisely controlling a switching valve and improving the durability of an exhaust aftertreatment filter.
[0010]
[Means for solving the problems and effects]
An exhaust gas purification apparatus for a diesel engine according to claim 1 of the present invention includes an exhaust aftertreatment filter that allows exhaust gas from a diesel engine to pass through, an upstream side switching valve provided on the upstream side of the exhaust aftertreatment filter, A downstream switching valve provided on the downstream side of the exhaust after-treatment filter and a control means for controlling the upstream and downstream switching valves are provided, and the control means opens and closes the switching valves. In the exhaust gas purifying apparatus for a diesel engine provided so as to be able to change the flow direction of the exhaust gas flowing through the exhaust aftertreatment filter by switching, the upstream side switching valve and / or the downstream side switching valve Furthermore, on the downstream side, the pressure of exhaust gas flowing into and / or out of the exhaust aftertreatment filter is set. Provided pressure detection means for output, said control means, a detection result in the pressure detecting means is equal to or switching the opening and closing of the switching valve when it reaches a switching set pressure.
[0011]
According to the present invention, the degree of particulate clogging is accurately and instantaneously reflected as the pressure of the exhaust gas flowing into or out of the exhaust aftertreatment filter. By detecting and monitoring the detection result by the control means, the switching control of the switching valve is precisely controlled in accordance with the degree of particulate clogging.
Even when the exhaust gas reaches a high temperature and high pressure so as to greatly affect the exhaust aftertreatment filter, it is possible to control the switching valve quickly without relying on the conventional unstable temperature sensor. The durability of the filter is improved.
In the present invention, “when the switching set pressure is reached” means that the upstream pressure detecting means reaches the switching set pressure set to the high pressure side, or the downstream pressure detecting means is set to the low pressure side. In addition to the case where the set switching set pressure is reached, the case where the difference between the pressure values by the upstream and downstream pressure detecting means reaches the preset switching set pressure is included.
[0012]
A diesel engine exhaust gas purifying apparatus according to claim 2 of the present invention is the diesel engine exhaust gas purifying apparatus according to claim 1, further comprising a time measuring means for measuring a usage time of the exhaust aftertreatment filter, and the control The means is used when the detection result of the pressure detecting means reaches the switching set pressure before the time measured by the time measuring means reaches the switching set time, or before the switching set pressure is reached. When reaching, the switching of the switching valve is switched.
According to the present invention, normally, the switching control of the switching valve is performed every time the switching set time is reached. However, when the switching set pressure is reached even before the switching setting time is reached, the switching setting pressure is given priority. Since the switching control is performed, it is possible to reliably cope with sudden pressure increase (particulate clogging). In addition, even if the switching set pressure is not reached, switching is performed at regular intervals at each switching set time, so that switching at a stage where the amount of accumulated particulate matter is relatively small is implemented, and the flow direction of the exhaust gas is changed. Particulate removal at the time of the change is performed reasonably and satisfactorily, and the cumulative use time without replacement of the exhaust aftertreatment filter is extended.
[0013]
A diesel engine exhaust gas purification apparatus according to claim 3 of the present invention is the diesel engine exhaust gas purification apparatus according to claim 1 or 2, wherein the vehicle equipped with the diesel engine is coasting. Operating state detecting means for detecting whether or not, and the control means switches opening and closing of the switching valve when it is determined that the coasting operation is based on the detection result of the operating state detecting means.
According to the present invention as described above, it is detected by the driving state detection means that the vehicle is coasting, and the switching control of the switching valve is performed during this coasting, that is, while the diesel engine is operating at a light load. Therefore, there is no need to switch the flow of the high-temperature and high-pressure exhaust gas, the burden on the switching valve and the exhaust aftertreatment filter is reduced, and the removed particulates are not exhausted at a stretch.
Furthermore, by using such a driving state detection means, especially when the present invention is applied to railway cars, the switching control of the switching valve is not performed in the station premises, etc., so that the particulates are discharged into the station premises. There is no worry to do.
[0014]
A diesel engine exhaust gas purification device according to claim 4 of the present invention is the diesel engine exhaust gas purification device according to any one of claims 1 to 3, wherein the switching valve is provided for the diesel engine. It is used for an exhaust brake.
According to the present invention, since the switching valve is also used as an exhaust brake valve, it is not necessary to provide a dedicated exhaust brake valve, the number of parts is reduced, and the structure is simplified.
[0015]
A diesel engine exhaust gas purifying apparatus according to claim 5 of the present invention is the diesel engine exhaust gas purifying apparatus according to any one of claims 1 to 4, wherein the control means opens all the switching valves. The switching valve is controlled for the exhaust brake of the diesel engine even after it is determined to be kept in a state.
According to the present invention, the exhaust post-processing filter is not clogged, and the exhaust brake can be operated even when the switching valve is kept open. Convenience at is high.
[0016]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
FIG. 1 is a diagram showing a schematic configuration of an exhaust gas purification device 1 according to the present embodiment. 2 and 3 are schematic diagrams showing the flow of exhaust gas in the exhaust gas purification device 1. FIG.
In FIG. 1, an exhaust gas purification device 1 collects particulates in exhaust gas by allowing exhaust gas from a diesel engine (not shown) to pass through. The exhaust gas purification device 1 is mounted on, for example, a railcar driven by a diesel engine. .
[0017]
More specifically, the exhaust gas purification device 1 includes a device main body 10 disposed in the middle of an exhaust pipe of a diesel engine, and a valve controller (control means) 20 having a computer and various interfaces. Exhaust gas containing particulates that has passed through the turbocharger (not necessary in the case of natural air supply) flows in from the inlet 10A shown in the lower side of the apparatus main body 10 in the figure (black arrow), and the party After the curate is collected, it is exhausted to the outside from the outlet 10B shown on the upper side in the figure (open arrow). In the present embodiment, the exhaust muffler is unnecessary because the sound is sufficiently silenced by the apparatus main body 10, but an exhaust muffler may be provided on the downstream side of the outlet portion 10B when further silence is desired.
[0018]
The apparatus main body 10 is provided with an inflow channel 11 having the inlet portion 10 </ b> A. The inflow channel 11 is branched into two systems and communicated with a cylindrical housing 12. The housing 12 communicates with an outflow passage 13 that is substantially the same shape as the inflow passage 11 and is provided on the opposite side, and the outlet portion 10 </ b> B is provided at the junction of the outflow passage 13. In addition, a cylindrical DPF (exhaust gas post-treatment filter) 14 carrying an oxidation catalyst is accommodated in the housing 12. Here, the inflow channel 11 and the outflow channel 13 are configured by a split (merging) pipe, an L-shaped elbow pipe, or the like that can be divided. The inflow direction and the discharge direction of the gas can be arbitrarily changed according to the mounting state of the apparatus main body 10.
[0019]
In addition, for example, butterfly type switching valves 15 and 16 are provided in the branch channels of the inflow channel 11 and the outflow channel 13, and the switching valves 15 and the switching valves 16 are opposed to each other with the DPF 14 interposed therebetween. It is arranged at the corner position. Such switching valves 15 and 16 are opened and closed by a cylinder actuator 17. Each actuator 17 is operated by the air pressure supplied from the electromagnetic valve 18, and the electromagnetic valve 18 is controlled by the valve controller 20. Then, by alternately switching the opening and closing of the switching valves 15 and 16, the direction of the exhaust gas flowing in the DPF 14 is changed, and clogging of the particulates is suppressed.
[0020]
The valve controller 20 outputs detection signals from a pressure sensor (pressure detection means) 31 and a temperature sensor 32 provided in the vicinity of the inlet 10A of the apparatus main body 10, and a fuel injection amount to the diesel engine. Adjusts the notch signal from the notch lever 33 for changing the vehicle speed, the ON / OFF signal for the exhaust brake switch 34 for operating the ON / OFF of the exhaust brake, and the vehicle speed sensor provided in the wheel portion or the mission portion of the vehicle The detection signal from 35 is output. At this time, the switching valves 15 and 16 are used for the exhaust brake, and in this embodiment, a valve (shutter) dedicated to the exhaust brake is not required. In addition, an ON / OFF signal of an air brake for braking the wheel is output to the valve controller 20, but the illustration thereof is omitted in FIG.
[0021]
The switching states of the switching valves 15 and 16 by the valve controller 20 include the states shown in FIGS. 2 (A) and 2 (B) and FIGS. 3 (A) and 3 (B).
FIG. 2A shows a state in which the switching valve 15 of the inflow channel 11 and the outflow channel 13 is opened and the switching valve 16 is closed. In this case, the exhaust gas passes through the inflow side switching valve 15, enters from one end surface 14 </ b> A side of the DPF 14, discharges from the other end surface 14 </ b> B, and is exhausted through the outflow side switching valve 15. That is, in the DPF 14, exhaust gas flows from the left side to the right side in the drawing along the axial direction, and particulates are collected during this time.
[0022]
On the other hand, FIG. 2B shows a state in which the switching valve 15 of the inflow channel 11 and the outflow channel 13 is closed and the switching valve 16 is opened. In this case, the exhaust gas passes through the switching valve 16 on the inflow side, enters from the other end surface 14B side of the DPF 14 and is discharged from the one end surface 14A, and is exhausted through the switching valve 16 on the outflow side. That is, in the DPF 14, the exhaust gas flows from the right side to the left side in the drawing along the axial direction, and particulates are collected during this time. Further, the particulates collected in the state of (A) are removed by the reverse flow of the exhaust gas and discharged into the atmosphere. It is well known that particulates at the stage of removal are harmless dust with a low carbon content.
[0023]
By alternately repeating these states (A) and (B), clogging due to particulates is suppressed in the DPF 14, and the DPF 14 can be used without being replaced for a long period of time. Such switching is normally performed when the valve controller 20 outputs a control signal for switching the valve to the electromagnetic valve 18 when the usage time in the same open / close state reaches a preset switching set time t1. Done.
[0024]
However, even before the switching set time t1 is reached, if the pressure detected by the pressure sensor 31 reaches the preset switching set pressure P2, it is determined that a large amount of particulate has been collected, and the valve controller 20 outputs a valve switching control signal to immediately switch the open / close state of the switching valves 15 and 16. Further, this switching is performed during coasting operation in the case of a diesel vehicle, for example, and is not performed while stopping at the station premises, so that dust is not discharged to the premises.
[0025]
On the other hand, the DPF 14 is not permanently used without replacement, and eventually becomes clogged by particulates deposited in a small amount. In this case, in consideration of the fuel consumption of the diesel engine and protection of the DPF 14, the exhaust gas is bypassed and exhausted without flowing into the DPF 14.
[0026]
FIG. 3A shows such a bypass state, and all the switching valves 15 and 16 are opened. In this case, the exhaust gas flows into the housing 12 from both directions of the inflow channel 11, enters the outflow channel 13 from both directions as it is, joins, and is exhausted from the outlet 10 </ b> B. However, such switching control to fully open is also performed when the exhaust gas pressure (exhaust pressure) or temperature (exhaust temperature) rises abnormally for some reason. The exhaust pressure and exhaust temperature at this time are preset as the limit pressure P1 and the limit temperature T1, and when it is determined that the limit pressure P1 and the limit temperature T1 have been reached by the detection signals from the pressure sensor 31 and the temperature sensor 32, The valve controller 20 outputs a fully open control signal to the electromagnetic valve 18.
[0027]
By the way, in this embodiment in which the switching valves 15 and 16 are used for the exhaust brake, when an ON signal is output from the exhaust brake switch 34 to the valve controller 20, the valve controller 20 is as shown in (B). All the switching valves 15 and 16 are closed, and the exhaust flow is temporarily stopped to apply the exhaust brake. The signal from the exhaust brake switch 34 is always accepted, and not only when the switching valves 15 and 16 are in the state shown in FIGS. 3 (A) and 3 (B) but also in the fully open state shown in FIG. 4 (A). Even if it is in a state, it is accepted and the exhaust brake works.
[0028]
Hereinafter, an example of specific control of the exhaust gas purification apparatus 1 will be described with reference to the flowchart of FIG.
Step 1 (hereinafter, “step” is simply abbreviated as “ST”): When the diesel engine is started, time counting is started by a counter (time measuring means) 21 in the valve controller 20 shown in FIG. In addition, when the timekeeping time at the time of stopping the diesel engine last time is stored in the storage means in the valve controller 20, timekeeping is started following this timekeeping time.
[0029]
ST2: Next, an ON / OFF signal from the exhaust brake switch 34 is monitored to determine whether or not the exhaust brake is in an ON state. If the ON signal is not output, the process proceeds to ST3, and if the ON signal is output, the process proceeds to ST16.
[0030]
ST3: Here, whether or not the exhaust pressure and exhaust temperature at the inlet 10A reach the limit pressure P1 and the limit temperature T1 based on detection signals from the pressure sensor 31 and the temperature sensor 32 when the exhaust brake is not working. Determine whether. If not reached, the process proceeds to ST4 as being in a normal state, and if reached, the process proceeds to ST12 as being in an abnormal state.
[0031]
ST4: In the normal state, first, it is monitored whether or not the exhaust pressure at the inlet 10A has reached the switching set pressure P2. If not, it is determined that the amount of particulates collected by the DPF 14 is small and clogging has not occurred, and the process proceeds to ST5. If it has reached, clogging has started to occur, and it is determined that the flow of exhaust gas in the DPF 14 needs to be changed, and the process proceeds to ST6. Here, in addition to the exhaust pressure, the switching set temperature may be set separately, and the clogged state of the particulates may be determined by the exhaust temperature.
[0032]
ST5: In a state where no clogging occurs, it is determined whether or not the time measured by the counter 21 has reached the switching set time t1. If not, the process returns to ST2 and repeats ST2 to ST5. If it has reached, it is determined that it is time to change the flow of the exhaust gas in the DPF 14 even if the exhaust pressure has not reached the switching set pressure P2, and the process proceeds to ST6.
[0033]
ST6 to ST8: In ST6, the notch signal from the notch lever 33 is monitored to determine whether or not the position of the notch lever 33 is at the idling position. In ST7, signals from the exhaust brake switch 34 and an air brake switch (not shown) are monitored to determine whether or not the vehicle is in a braking state. In ST8, the detection signal from the vehicle speed sensor 35 is monitored to determine whether or not the pneumatic vehicle is in a traveling state.
[0034]
If any of these determination results is NO, it is determined that the diesel car is not in the coasting operation state, and waits until it enters the coasting state. If all the determination results are yes, it is determined that the diesel car is coasting and the process proceeds to ST9. That is, the notch lever 33, the exhaust brake switch 34, the air brake switch, and the vehicle speed sensor 35 are means for determining whether or not the pneumatic vehicle is coasting, and thus the driving state detection means 36 according to the present invention is used as the means. It is composed.
[0035]
Note that the driving state detection means for determining whether or not the pneumatic vehicle is coasting is not limited to this, and may be configured by only the notch lever 33, for example. In such a case, for example, after the notch lever 33 maintains the acceleration position (high load position) for a predetermined time, whether or not the idling position is further maintained for a predetermined time can determine whether the coasting operation is being performed. Further, it is possible to determine that the diesel car is not stopped in the station premises or the like by the driving state detecting means 36 as described above.
[0036]
ST9: When it is determined that the pneumatic vehicle is in coasting operation, the switching valves 15 and 16 are switched to change the flow of exhaust gas in the DPF 14 and the collected particulates are removed. At this time, when switching the valve, the state of (A) in FIG. 2 is not switched to the state of (B), or conversely from the state of (B) to the state of (A). Only (for example, within 1 second), it is once fully opened and switched through this state. As a result, it becomes possible to prevent the exhaust brake from being applied to the state where the engine is almost closed when switching.
[0037]
ST10: Here, the exhaust pressure is detected again. If the exhaust pressure has reached the switching set pressure P2 even though the flow of exhaust gas in the DPF 14 has been changed, it is determined that it is time to prevent clogging in the DPF 14 and the process goes to ST12. move on. If the switching set pressure P2 has not been reached, the process proceeds to ST11. However, when the exhaust pressure is detected in ST10, it is desirable that a predetermined time elapses after the valve switching in ST9.
[0038]
ST11: After the above, the counter 21 is reset (cleared to zero), and the process returns to ST1 to restart the counter 21. ST1 to ST11 are normal flows in which no abnormality has occurred. If the engine is stopped during this flow, the time measured by the counter 21 is stored and held as it is, and the switching valves 15 and 16 are opened and closed. Is maintained as it is.
[0039]
ST12: In ST3, when it is determined that the exhaust pressure and exhaust temperature at the inlet 10A have reached the limit pressure P1 and the limit temperature T1 and the diesel engine or the exhaust gas purification device 1 is in an abnormal state, or in ST10, When it is determined that it is time to eliminate clogging in the DPF 14, all the switching valves 15 and 16 are opened and immediately switched to the state shown in FIG. 3A to protect the DPF 14 and the like.
[0040]
ST13: Subsequently, an arbitrary warning means such as a warning light or a buzzer in an underfloor inspection section or a cab is operated to notify an abnormal state. When this warning is issued, the vehicle is moved to a vehicle place or the like for inspection according to the situation, or the DPF 14 is replaced if it is time to replace the DPF 14. Further, when the DPF 14 is replaced, the counter 21 is automatically reset.
[0041]
ST14, 15: By the way, even if all the switching valves 15, 16 are opened, there are many cases where the operation of the diesel car is continued for a while. Even in such a case, the ON / OFF signal from the exhaust brake switch 34 is received here in order to use the exhaust brake effectively. That is, when the switch is OFF, the valve is fully opened, but when the ON signal is output from the exhaust brake switch 34, all the switching valves 15 and 16 are closed to operate the exhaust brake, and then the process returns to ST14 again. The exhaust brake is applied until the OFF signal is output.
[0042]
ST16: When an ON signal is output from the exhaust brake switch 34 in ST2, that is, when operating in a normal state, when the exhaust brake is to be activated by approaching a downhill road or a stop station, the ON signal is output. In this case, as described above, all the switching valves 15 and 16 are closed and the exhaust brake is operated.
[0043]
ST17: After that, the output of the OFF signal from the exhaust brake switch 34 is monitored (or monitoring until the output of the ON signal stops), and the exhaust brake is operated until the OFF signal is output. Proceed to
[0044]
ST18: Here, the switching valves 15 and 16 are again returned to the original open / closed state before the exhaust brake, and returned to the normal collection state.
[0045]
According to this embodiment, there are the following effects.
(1) That is, according to the exhaust gas purification apparatus 1, the degree of particulate clogging is accurately and instantaneously reflected as the exhaust pressure flowing into the DPF 14, so that such exhaust pressure is detected by the pressure sensor 31, By monitoring this detection result with the valve controller 20, the switching control of the switching valves 15 and 16 can be precisely controlled according to the degree of particulate clogging.
[0046]
(2) Further, even if the exhaust gas reaches a high temperature and a high pressure so that the exhaust gas has a great influence on the DPF 14 by detecting the exhaust pressure with the pressure sensor 31, as described in ST12 in FIG. Therefore, the switching valves 15 and 16 can be controlled quickly without using the temperature sensor, and the durability of the DPF 14 can be improved.
[0047]
(3) Further, in the exhaust gas purification apparatus 1 of the present embodiment, switching control of the switching valves 15 and 16 is normally performed every time the switching setting time t1 is reached, but before the switching setting time t1 is reached, the switching setting pressure P2 Since the switching control is performed with priority given to the switching set pressure P2, when it reaches, the sudden pressure increase (particulate clogging) can be dealt with reliably.
[0048]
(4) Moreover, even if the switching set pressure P2 is not reached, the switching is performed almost periodically at each switching set time t1, so that switching can be performed at a stage where the accumulated amount of clogged particulates is relatively small, and the flow direction of the exhaust gas The removal of particulates can be made reasonably well when changing, and the cumulative use time without replacement of the DPF 14 can be extended.
[0049]
(5) Then, it is determined from the notch positions and output signals of the operation state detection means 36 composed of the notch lever 33, the exhaust brake switch 34, and the vehicle speed sensor 35 that the diesel car is in coasting operation. Since switching control of the switching valves 15 and 16 is performed during this coasting operation which is a light load operation, there is no need to switch the flow of high-temperature and high-pressure exhaust gas during acceleration, and the switching valves 15 and 16 and the DPF 14 are not switched. The burden can be reduced and the removed particulates are not expelled at once.
[0050]
(6) Further, by using such a driving state detecting means 36, it can be determined with certainty that the train is not stopped in the station premises, so that the switching control of the switching valves 15 and 16 is not performed in the station premises. Sorry, there is no worry of discharging particulates inside the station.
[0051]
(7) In the exhaust gas purification device 1, the switching valves 15 and 16 are also used as exhaust brake valves, so there is no need to provide a dedicated exhaust brake valve, the number of parts can be reduced, and the structure is simplified. And cost can be reduced.
[0052]
(8) And, as shown in ST14 and ST15 in FIG. 4, the exhaust brake can be operated even when the switching valves 15 and 16 are held in the open state. Can be increased.
[0053]
In addition, this invention is not limited to the said embodiment, Including other structures etc. which can achieve the objective of this invention, the deformation | transformation etc. which are shown below are also contained in this invention.
For example, in the exhaust gas purification apparatus 1 of the above embodiment, the pressure sensor 31 is provided at the inlet 10A, but it may be provided at the outlet 10B. In such a case, the switching set pressure P2 is set to the low pressure side. When the exhaust pressure becomes equal to or lower than the switching set pressure P2, the opening and closing of the switching valves 15 and 16 may be switched. Moreover, the pressure sensor 31 may be provided in both the inlet portion 10A and the outlet portion 10B, and the clogged state may be determined from the difference between the exhaust pressures.
[0054]
The switching valves 15 and 16 in the above embodiment are provided in a total of four pairs, one for the inflow channel 11 and one for the outflow channel 13, but one switching valve is provided at the branch portion of the inflow channel 11. It is also possible to provide one switching valve at the confluence portion of the flow path 13 to perform switching control, thereby changing the direction of the exhaust gas flowing in the DPF 14. In such a case, the number of switching valves can be made two, which can be made cheaper.
[0055]
According to the embodiment, after the release of the exhaust brake that was activated during the normal operation state, the switching valves 15 and 16 are returned to the original open / closed state as shown in ST18 in FIG. Immediately after the release of the brake, it may be fully opened even momentarily, and then the original open / close state may be restored.
That is, the exhaust gas at the inlet portion 10A during exhaust brake operation is certainly compressed by closing the switching valves 15 and 16, but there is little fuel during braking. Since it is not sprayed or not sprayed at all, it becomes low pressure and low temperature. And when such exhaust gas is unpreferable on the function of DPF14 for some reason, it is desirable to open | release all the switching valves 15 and 16 once, exhaust exhaust gas, and not let DPF14 pass. Further, during the operation of the exhaust brake, particulates are not easily generated because the fuel is not injected so much, so even if such exhaust gas is discharged as it is, there is little influence on the surroundings.
[0056]
On the contrary, when the low pressure and low temperature exhaust gas during the operation of the exhaust brake is advantageous for the function of the DPF 14 for another reason, the switching valves 15 and 16 on the inflow passage 11 side are opened and the outflow passage 13 is opened. The switching valves 15 and 16 on the side may be closed to apply the exhaust brake so that the inside of the housing 12 in which the DPF 14 is accommodated may be in a low pressure and low temperature state.
[0057]
The opening degree of the switching valves 15 and 16 in the above embodiment was either completely closed or fully opened, but the opening degree of these switching valves 15 and 16 can be adjusted steplessly or stepwise. You may comprise. In such a configuration, the temperature of the exhaust gas passing through the DPF 14 is increased by further reducing the opening of the switching valves 15 and 16 on the open side, and the self-combustion of the collected particulate matter becomes high temperature. Induction can be promoted with exhaust gas. In addition to the existing switching valves 15 and 16, another exhaust valve whose opening degree can be adjusted is provided in the vicinity of the inlet portion 10A or the outlet portion 10B, and this exhaust valve is throttled to raise the temperature of the exhaust gas. Good.
[0058]
In the embodiment, the example in which the exhaust gas purifying device 1 is mounted on a railway car has been described. However, the exhaust gas purifying device of the present invention is not limited to this, and any arbitrary diesel engine such as a truck, a bus, or a construction machine is mounted. It may be mounted on a vehicle, and can be applied to, for example, a diesel engine for driving a stationary generator other than the vehicle.
[0059]
In addition, the best configuration, method and the like for carrying out the present invention have been disclosed in the above description, but the present invention is not limited to this. That is, the invention has been illustrated and described primarily with respect to particular embodiments, but may be configured for the above-described embodiments without departing from the scope and spirit of the invention. Various modifications can be made by those skilled in the art in terms of materials, quantity, and other detailed configurations.
Therefore, the description limiting the shape, material, etc. disclosed above is an example for easy understanding of the present invention, and does not limit the present invention. The description by the name of the member which remove | excluded the limitation of one part or all of such restrictions is included in this invention.
[Brief description of the drawings]
FIG. 1 is a diagram showing a schematic configuration of an exhaust gas purification apparatus according to an embodiment of the present invention.
FIG. 2 is a schematic diagram showing a flow of exhaust gas in the exhaust gas purification device.
FIG. 3 is a schematic diagram showing another flow of exhaust gas in the exhaust gas purification device.
FIG. 4 is a flowchart showing a control method of the exhaust gas purification device.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Exhaust gas purification apparatus, 14 ... DPF which is an exhaust after-treatment filter, 15, 16 ... Switching valve, 20 ... Valve controller which is control means, 21 ... Timer which is time measuring means, 31 ... Pressure sensor which is pressure detection means 36, operating state detection means, P2, switching setting pressure, t1, switching setting time.

Claims (5)

An exhaust aftertreatment filter (14) that allows exhaust gas from the diesel engine to pass through, an upstream switching valve (15, 16) provided upstream of the exhaust aftertreatment filter (14), and the exhaust aftertreatment filter ( 14) provided with a downstream switching valve (15, 16) provided on the downstream side, and a control means (20) for controlling these upstream and downstream switching valves (15, 16). Exhaust gas of a diesel engine provided so that the flow direction of the exhaust gas flowing through the exhaust aftertreatment filter (14) can be changed by switching the opening and closing of the switching valves (15, 16) by the control means (20). In the purification device (1),
The upstream switching valve (15, 16) and / or the downstream switching valve (15, 16) further flows into and / or out of the exhaust after-treatment filter (14). Pressure detecting means (31) for detecting the pressure of the exhaust gas is provided;
The control means (20) switches the opening and closing of the switching valve (15, 16) when the detection result of the pressure detection means (21) reaches the switching set pressure (P2). Exhaust gas purification device (1). In the exhaust-gas purification apparatus (1) of the diesel engine of Claim 1,
Provided with time measuring means (21) for measuring the usage time of the exhaust aftertreatment filter (14),
In the control means (20), the detection result in the pressure detection means (31) reaches the switching set pressure (P2) before the time measured in the time measuring means (21) reaches the switching set time (t1). Or when the switching set time (t1) is reached before the switching set pressure (P2) is reached, the opening and closing of the switching valve (15, 16) is switched. Purification device (1). In the exhaust-gas purification apparatus (1) of the diesel engine of Claim 1 or Claim 2,
An operation state detection means (36) for detecting whether or not the vehicle on which the diesel engine is mounted is coasting;
The control means (20) switches the opening and closing of the switching valve (15, 16) when it is determined that the coasting operation is performed based on the detection result of the operation state detection means (36). Exhaust gas purification device (1). The exhaust gas purification device (1) for a diesel engine according to any one of claims 1 to 3,
The diesel engine exhaust gas purification device (1), wherein the switching valve (15, 16) is used for an exhaust brake of the diesel engine. The exhaust gas purification device (1) for a diesel engine according to any one of claims 1 to 4,
The control means (20) controls the switching valve (15, 16) for exhaust braking of the diesel engine even after determining that the switching valve (15, 16) is all kept open. An exhaust gas purification device (1) for a diesel engine.

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