JP2006242175A - Device and method for continuously regenerating pm - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an exhaust emission control device mounted to capture particulate matters (called PM hereafter) in an exhaust gas, in a vehicle loaded with a diesel engine. <P>SOLUTION: This device for continuously regenerating PM has the exhaust emission control device to continuously reproduce PM in the exhaust gas exhausted from the diesel engine in which an intake air throttle valve and an EGR system are mounted, an exhaust brake provided between the diesel engine and the exhaust emission control device, and an exhaust gas throttle valve for adjusting an amount of exhaust gas, which discharges the exhaust gas discharged from the exhaust emission control device to the outside. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a PM continuous regeneration device and a PM continuous regeneration method that are mounted to collect particulate matter (hereinafter referred to as PM) in exhaust gas in a vehicle equipped with a diesel engine (hereinafter referred to as DE).

The emission regulation value of DE that becomes stricter over the years is that after 2005, as in gasoline engines, PM, hydrocarbons (HC) and carbon monoxide (CO) are oxidized by a catalyst to form carbon dioxide (CO ₂ ) and water ( H ₂ O), NO _x must be dissociated to make nitrogen (N ₂ ) and oxygen (O ₂ ) harmless, and then discharged.

  Conventionally, DE for automobiles has tried to reduce harmful substances contained in exhaust gas mainly by improving combustion of the engine itself, but it is considered to be very difficult to conform to exhaust emission regulation values after 2005. ing.

Recently, research and development on a continuously regenerative diesel particulate filter (DPF) composed of a front-stage diesel oxidation catalyst (DOC) and a rear-stage diesel particulate filter (DPF) have been promoted. In the preceding DOC, HC changes to CO ₂ and H ₂ O, and CO changes to CO ₂ . Further, nitrogen monoxide (NO) in NO _x is changed to nitrogen dioxide (NO ₂ ). In the latter stage DPF, the soot component in PM is burned with NO ₂ generated in the former stage and discharged as CO ₂ . This continuous regenerative DPF is known as a CRT invented by Johnson Mathey. Research and development of an integrated DPF (catalyst-supported DPF) in which various oxidation catalysts are supported on a structure DPF having only a filter function is also underway. In the present invention, a DPF having only a filter function is simply a DPF, and a DPF carrying a catalyst is a catalyst-carrying DPF. In the present invention, the continuous regeneration type DPF includes a catalyst-supported DPF, a combination of DOC and DPF, and a combination of DOC and catalyst-supported DPF.

Stage continuous regeneration type DPF in provided Deno _x catalyst, research and development has been advanced with regard selective catalytic reduction method for dissociating also last remaining NO _x (SCR). An apparatus combining this SCR and the above CRT is known as SCRT from Johnson Mathey.

The combustion of PM in the continuous regeneration type DPF is said to be 350 ° C. or more in the catalyst-carrying DPF and 250 to 450 ° C. in the DOC. The exhaust temperature during normal idling of the DE is 70 to 100 ° C. At a traveling speed of 80 km / hr or less of a vehicle driven by the DE, the load of the DE corresponding to the generated traveling resistance is low, and the exhaust temperature is The problem is that PM that does not reach 260 ° C (250 ° C + α) and is collected in the continuously regenerating DPF accumulates in the filter without being regenerated (oxidized), clogs, and eventually becomes impossible to operate. was there.
JP 2002-322909 A JP 2003-293749 A JP 2001-336440 A

  For this reason, in Patent Document 1, in addition to the main catalyst, an auxiliary catalyst having a small heat capacity is installed in the vicinity of the engine, and the main catalyst is used at the time of high output of the engine, and the auxiliary catalyst is used at the time of low output. Avoid cooling by long pipes and avoid lowering the specific output of the engine due to the catalyst being installed close to the engine, and using an auxiliary catalyst with a small heat capacity at the start of the engine will increase the temperature in a short time and activate the catalyst It is possible to do.

  Further, in Patent Document 2, an auxiliary catalyst having a small heat capacity is provided in addition to the main catalyst, and an intake throttle, ESC, reduced cylinder, and exhaust throttle can be performed.

  In the DE low load high exhaust temperature maintenance device described in Patent Documents 1 and 2 and Patent Document 3, if it is a disadvantageous condition such as a low load state for a long time, it accumulates inside the catalyst rather than the PM regeneration capability of the catalyst. There was a problem that the state of exceeding the amount of PM continued and the engine eventually misfired.

  In particular, in a 3.0 liter supercharged engine, the DE high exhaust temperature maintenance device at low load described in Patent Document 3 has succeeded in effective exhaust gas rise and continuous PM regeneration, but has an unfavorable condition. Then PM couldn't be played continuously.

  The present invention has been made for the above-mentioned circumstances, and an object of the present invention is to continuously regenerate (oxidize) PM even if conditions unfavorable for PM regeneration at low engine load such as idling continue for a long time. An object of the present invention is to provide a PM continuous regeneration device and a PM continuous regeneration method.

  The present invention is a PM continuous regeneration device capable of continuously regenerating PM even if conditions unfavorable for PM regeneration continue for a long time. The above object of the present invention is an EGR system having an intake throttle valve and an EGR valve An exhaust purification device for continuously regenerating PM in exhaust gas discharged from a diesel engine equipped with an exhaust brake, an exhaust brake installed between the diesel engine and the exhaust purification device, and an exhaust purification device and an exhaust port. This is effectively achieved by having an exhaust throttle valve that is installed in between and adjusts the amount of exhaust gas exhausted from the exhaust purification device to the exhaust port.

  Further, the above object of the present invention is to open the exhaust throttle valve and the intake throttle valve when the diesel engine has a low rotational speed, the diesel engine has a low load, and the exhaust gas temperature is 200 ° C. or less. By setting the degree to 5 to 50% and the throttle opening of the EGR valve to 10 to 100%, or the diesel engine has a high rotational speed, the diesel engine has a high load, and the exhaust gas temperature is 200. When the temperature exceeds ℃, the throttle opening of the exhaust throttle valve and the intake throttle valve is set to 50% or more, and the throttle opening of the EGR valve is set to 10% or less, or the throttle between the exhaust throttle valve and the exhaust brake The opening degree is more effectively achieved by being controlled in a one-stage system, a multi-stage system, or a non-stage system. Here, regarding the throttle opening, the state when the valve is fully opened is expressed as 100%, and the state when the valve is fully closed is expressed as 0%.

  Further, the above object of the present invention is that the exhaust throttle valve and the exhaust brake have the same structure, or when the exhaust brake is operating, the throttle opening of the exhaust throttle valve is set to 100%. When the exhaust brake is operated, the throttle opening of the intake throttle valve is set to 50% or more, or the exhaust purification device is made of DPF, or the exhaust purification device Is made of DPF carrying a catalyst, or the exhaust purification device is a DPF with a DOC mounted on the exhaust brake side, or the exhaust purification device is made of a metal carrier Or the exhaust purification device is more effectively achieved by being a ceramic carrier.

  The above-described object of the present invention is that the exhaust purification device is composed of a combination of a DOC and a plurality of DPFs, or the DOC and the plurality of DPFs are formed of a metal carrier, and the DOC is disposed on the diesel engine side. The catalyst is supported on the DOC and the catalyst is not supported on the DPF, or the catalyst is supported on both the DOC and the plurality of DPFs. The catalyst is supported on the DOC, and the catalyst is supported on at least one of the plurality of DPFs. Alternatively, the DPF with the catalyst supported immediately after the DOC. It is configured to be arranged, or among three or more DPFs, there is one DPF carrying a catalyst. In this case, an unsupported DPF is arranged immediately after the DOC, a DPF carrying a catalyst is arranged immediately after the unsupported DPF, and a plurality of unsupported DPFs are arranged immediately after the DPF on which the catalyst is supported. If there are two or more DPFs on which a catalyst is supported among three or more DPFs, the DPFs on which two catalysts are supported are arranged immediately after the DOC, By arranging the unsupported DPF immediately after the catalyst-supported DPF, or when two of the four or more DPFs support the catalyst, the catalyst is immediately after the DOC. A supported DPF is disposed, an unsupported DPF is disposed immediately after the DPF on which the catalyst is supported, a DPF with a catalyst supported is disposed immediately after the unsupported DPF, and the catalyst is supported. Unsupported D immediately after DPF When a plurality of Fs are arranged, or among two or more DPFs, two DPFs with a catalyst are supported, an unsupported DPF is disposed immediately after the DOC, and the unsupported DPFs are arranged. A DPF carrying a catalyst is arranged immediately after the DPF, an unsupported DPF is arranged immediately after the DPF on which the catalyst is supported, and a DPF carrying a catalyst is provided immediately after the unsupported DPF. This is achieved more effectively by arranging a plurality of unsupported DPFs immediately after the formed DPF.

  The present invention is provided between an exhaust gas purification device that continuously regenerates PM in exhaust gas discharged from a diesel engine having an intake throttle valve and an EGR system having an EGR valve, and between the diesel engine and the exhaust gas purification device. PM continuous exhaust gas is installed between an exhaust brake and an exhaust purification device and an exhaust port, and has an exhaust throttle valve for adjusting the amount of exhaust gas discharged from the exhaust purification device to the outside. The above-mentioned object of the present invention is a regeneration method, and the exhaust throttle valve and the intake throttle when the diesel engine has a low rotational speed, the diesel engine has a low load, and the exhaust gas temperature is 200 ° C. or less. The throttle opening of the valve is 5 to 50%, the throttle opening of the EGR valve is 10 to 100%, the diesel engine has a high rotation speed, and the diesel engine When the exhaust gas temperature exceeds 200 ° C., the throttle opening of the exhaust throttle valve and the intake throttle valve should be 50% or more, and the throttle opening of the EGR valve should be 10% or less. Effectively achieved by

  According to the PM continuous regeneration device and the PM continuous regeneration method of the present invention, when the DE is at a low load and the exhaust gas temperature is low, the exhaust throttle valve and the intake throttle valve are closed, and the EGR valve is By opening the valve, the amount of exhaust gas passing through the EGR valve increases. As a result, the exhaust gas temperature rises, and the PM contained in the exhaust gas can be continuously regenerated by the exhaust purification device. Therefore, PM can be continuously regenerated even if conditions unfavorable for PM regeneration, such as when the DE is under a low load and when idling, continue for a long time. Further, the throttle opening of the exhaust throttle valve, the intake throttle valve, and the EGR valve can be adjusted according to the purpose, etc., so that the exhaust gas temperature can be appropriately increased according to the driving situation, the DE situation, etc. I can do it now.

  Furthermore, since the PM continuous regeneration apparatus of the present invention does not have other independent pipes or the like, the manufacturing cost can be reduced. Since the PM continuous regeneration device of the present invention does not have any other independent pipes or the like, it can be connected to the DE as a retrofit even for a vehicle type with a short interval between the currently used (commercially available) DE and the exhaust purification device. I can do it now.

  It is said that the exhaust gas temperature needs to be 260 ° C. or higher in order to regenerate (oxidize) PM with the exhaust purification device. When the vehicle driven by the DE is traveling at a low speed at low speed or idling, the load of the DE is low, the exhaust gas temperature does not reach 260 ° C., and the PM collected by the exhaust purification device is regenerated. It accumulates in the filter without any clogging, and the filter becomes clogged, and eventually it becomes impossible to operate. The present invention is characterized in that, for example, when the DE is under a low load, the exhaust throttle valve is closed, the exhaust gas temperature is raised, and the filter in the exhaust purification device is prevented from being clogged. Hereinafter, the present invention will be described in detail with reference to the drawings, but the present invention is not limited thereto.

  FIG. 1 is a configuration diagram showing an example of a PM continuous reproduction apparatus of the present invention.

  The air that has passed through the air cleaner 1 passes through the intake throttle valve 2, is sent into the DE3 cylinder (the cylinder is not shown), and is mixed with the fuel injected in the DE3 cylinder and burned. An DEGR system is connected to DE3 and plays a role of returning exhaust gas into DE3 by opening and closing the EGR valve 4 in the EGR system. The burned exhaust gas passes through the exhaust manifold 5, passes through the exhaust brake 6, and is purified by the exhaust purification device 7. The exhaust gas purified by the exhaust purification device 7 passes through the exhaust throttle valve 8 and is discharged to the discharge port 9. The closing of the intake throttle valve 2, the EGR valve 4, the exhaust brake 6 and the exhaust throttle valve 8 is controlled by the ECU 10.

  When the exhaust brake 6 is closed, it becomes difficult for the exhaust gas to flow, and the pressure during exhaust in the cylinder of the DE 3 increases. Since DE3 tries to exhaust the exhaust gas from the cylinder against this pressure, the force applied to the piston increases. Since the fuel injection is not performed when the exhaust brake 6 is operating, the force applied to the piston appears as a force to stop DE3, that is, a brake.

  It is preferable that the exhaust throttle valve 8 has the same structure as the exhaust brake 6, that is, uses the same thing as the exhaust brake 6. By using the same structure for the exhaust throttle valve 8 and the exhaust brake 6, the exhaust throttle valve 8 is the same as the exhaust brake 6, for example, when the opening degree of the valve is controlled in a single stage (single throttle). It becomes a control method, and only the operation area of DE3 is different. Therefore, by making the structure of the exhaust throttle valve 8 the same as that of the exhaust brake 6, the cost can be suppressed. It should be noted that the throttle opening degree of the exhaust throttle valve 8 and the exhaust brake 6 may be controlled not only by a single step type but also by a multi-step type or a stepless type.

  When the exhaust brake 6 is operating, the opening of the exhaust throttle valve 8 is preferably fully open (the throttle opening is 100%). If the opening of the exhaust throttle valve 8 is not fully opened, the pressure in the cylinder of DE3 further increases and DE3 stops. Further, when the exhaust brake 6 is operating, it is preferable that the throttle opening of the intake throttle valve 2 is 50% or more. By setting the throttle opening of the intake throttle valve 2 in such a range, the exhaust brake 6 can be controlled efficiently. If the throttle opening of the intake throttle valve 2 is less than 50%, the intake air amount decreases due to the intake resistance, and the amount of working exhaust gas in the cylinder decreases, so the braking performance of the DE 3 decreases. Further, at this time, since fuel injection is not performed, it is not necessary to reduce exhaust gas by the EGR system, so the EGR valve 4 is fully closed.

  As the exhaust gas purification device 7, a device comprising a DPF, a catalyst-carrying DPF (a DPF carrying a catalyst), or the like is used. Moreover, you may use DPF with which DOC was mounted | worn by the exhaust brake 6 side. By mounting the DOC on the exhaust brake 6 side, the PM in the exhaust gas sent from the DE 3 can be efficiently regenerated. The material of the DOC carrier is not particularly limited, and for example, a metal carrier, cordierite, silicon carbide, silicon nitride, or a ceramic carrier made of a composite of these is preferable. A combination of a metal carrier and a ceramic carrier may be used.

  In addition, as shown in FIG. 2, the exhaust purification device 7 may be used in combination with DOC and a plurality of DPFs. In particular, when a PM continuous regeneration apparatus is configured only with a metal carrier, the metal DPF is made to have a certain length in terms of manufacture by the manufacturer. In order to secure the collection rate, a plurality of DPFs of this fixed length are used in combination. In addition, since using DPFs of the same type and having a predetermined length leads to cost reduction, a plurality of DPFs having the same type and having a predetermined length may be connected.

In the PM continuous regeneration apparatus of the present invention, first, the catalyst-supported DOC is arranged in the front stage 71 on the DE 3 side, and then a plurality of DPFs are placed in the front middle stage 72, the middle stage 73, the rear middle stage 74, and the rear stage according to the above circumstances. 75 may be arranged. In this case, whether or not the catalyst is supported on the plurality of DPFs arranged in the front middle stage 72, the middle stage 73, the rear middle stage 74, and the rear stage 75 depends on the amount of PM collected in the DPF and the DOC. And the amount of NO ₂ produced by the action of the catalyst and the exhaust gas temperature. When the amount of NO ₂ generated from the DOC arranged in the front stage 71 is sufficient to regenerate the deposited PM, or due to the good thermal conductivity of the metal carrier, PM regeneration occurs locally. When the heat at this time is rapidly conducted to the surroundings and the regeneration of the PM accumulated in the surroundings is activated, it is not necessary to support the catalyst on the DPF.

If only the amount of NO ₂ from the DOC arranged in the front stage 71 is insufficient to regenerate the accumulated PM, the DPF (the front middle stage 72) arranged immediately after the DOC is also used. It is necessary to support the catalyst and ensure the amount of NO ₂ . At this time, the catalyst must be supported on all the plurality of DPFs arranged in the front middle stage 72, the middle stage 73, the rear middle stage 74, and the rear stage 75, and one or two of the plurality of DPFs are supported on the catalyst. In some cases, sufficient PM regeneration can be ensured by just doing. This is determined by the condition of the exhaust gas discharged from DE3.

Further, when only one or two of the plurality of catalysts are supported, the catalyst supporting DPF among the plurality of DPFs arranged in the front middle stage 72, the middle stage 73, the rear middle stage 74, and the rear stage 75 are Effective PM regeneration is determined depending on the arrangement with the unsupported DPF. This is also determined in relation to the exhaust gas conditions discharged from DE3. That is, if the unsatisfactory state to play the PM deposited in the DPF is arranged immediately after DOC only NO ₂ from the catalyst supported DOC (front middle 72), a catalyst loaded with DPF upstream 71 It is effective to arrange immediately after the arranged DOC (the front middle stage 72 when there is one catalyst-carrying DPF, and the front middle stage 72 and middle stage 73 when there are two catalyst-carrying DPFs). is there. Conversely, if only the NO ₂ from the DOC arranged in the preceding stage 71 is sufficient to regenerate PM accumulated in the DPF arranged immediately after the DOC (the preceding middle stage 72), the DOC arranged in the preceding stage 71 immediately after DPF disposed (before middle 72) may in unsupported, since NO ₂ used for regeneration in the DPF that is arranged immediately after the DOC, which is located before 71 (front middle 72) is changed to NO Then, the DPF disposed in the middle front stage 72 is used as a catalyst, and NO is changed again to NO ₂ so that PM deposited after the DPF disposed in the front middle stage 72 is regenerated. When the catalyst is not supported on the total number of DPFs, the unsupported DPF is always arranged as the DPF in the rear stage 75.

  For example, when four DPFs and two of them are catalyst-supported DPFs, the arrangement of the front middle stage 72, the middle stage 73, the rear middle stage 74, and the rear stage 75 after the DOC arranged in the front stage 71 is as follows. There is only an arrangement of catalyst-supported DPF + catalyst-supported DPF + non-supported DPF + non-supported DPF, and catalyst-supported DPF + non-supported DPF + catalyst-supported DPF + non-supported DPF. In this case, in addition to the arrangement of catalyst-supported DPF + catalyst-supported DPF + unsupported DPF + unsupported DPF + unsupported DPF, catalyst-supported DPF + unsupported DPF + catalyst-supported DPF + unsupported DPF + unsupported DPF, unsupported DPF + catalyst-supported DPF + not-supported An arrangement of supported DPF + catalyst-supported DPF + non-supported DPF is also effective. The determination of these arrangements is determined by the conditions of the exhaust gas discharged from the target DE as described above. In FIG. 2, the exhaust purification device 7 is configured by a combination of five DPFs or DOCs. However, the present invention is not limited to this, and the exhaust purification device 7 can be appropriately selected according to the purpose of use. The number can be changed. Note that the catalyst is supported on these materials.

  The material of the exhaust gas purification device 7 is not particularly limited, but is preferably a metal carrier, cordierite, silicon carbide, silicon nitride, a ceramic carrier made of a composite thereof, or the like. A combination of a metal carrier and a ceramic carrier may be used.

  When DE3 has a low rotational speed, DE3 has a low load, and the exhaust gas temperature is 200 ° C. or less, the exhaust throttle valve 8 and the intake throttle valve 2 are controlled to be closed through the ECU 10.

  By controlling the exhaust throttle valve 8 and the intake throttle valve 2 to be closed, the exhaust resistance of the exhaust gas increases and the exhaust pressure increases. Further, by controlling the opening of the EGR valve 4, the amount of exhaust gas passing through the EGR valve 4 increases. By controlling the intake throttle valve 2 to close, the amount of fresh air decreases, and the amount of exhaust gas that passes through the EGR valve 4 and is recirculated into the cylinder can be increased. Since the hot exhaust gas is recirculated into the cylinder, the exhaust gas temperature after the intake stroke in the cylinder is increased. Further, since the amount of fresh air is reduced, the burning out of the combustion is delayed, the temperature of the exhaust gas discharged from the DE 3 rises, and the temperature rise of the exhaust purification device 7 is also accelerated.

  The exhaust throttle valve 8 is preferably not closed completely, but the throttle opening is preferably 5 to 50%. By setting the throttle opening in such a range, the EGR amount increases and the exhaust gas temperature can be raised. If the throttle opening of the exhaust throttle valve 8 is less than 5%, the exhaust gas cannot flow through the exhaust port 9, and a load is applied to the DE 3, resulting in a dangerous state such as engine stop. On the other hand, if the throttle opening exceeds 50%, the exhaust gas exhaust pressure does not increase so much and the exhaust purification device 7 cannot efficiently regenerate PM continuously. Further, the amount of exhaust gas passing through the EGR valve 4 cannot be increased, and the fuel consumption may be deteriorated due to an increase in intake resistance.

  Further, the intake throttle valve 2 is not completely closed, and the throttle opening is preferably 5 to 50%. By setting the throttle opening in such a range, the amount of EGR increases and the exhaust gas temperature can be kept high. If the throttle opening of the intake throttle valve 2 is less than 5%, the amount of intake air is extremely reduced, so that the amount of air given to the combustion becomes insufficient and the combustion deteriorates. Therefore, the fuel consumption is also deteriorated, and in the worst case, the engine is in a dangerous state such as being stopped. On the other hand, when the throttle opening of the intake throttle valve 2 exceeds 50%, the EGR amount does not increase so much and the exhaust gas temperature cannot be increased.

  When DE3 has a low rotational speed, DE3 has a low load, and the exhaust gas temperature is 200 ° C. or less, the throttle opening of the EGR valve 4 is performed in conjunction with the closing control of the intake throttle valve 2 and the exhaust throttle valve 8. The degree is 10 to 100%. By setting the throttle opening of the EGR valve 4 in such a range, the exhaust throttle valve 8 and the intake throttle valve 2 are controlled to be closed. Therefore, when the amount of exhaust gas passing through the EGR valve 4 increases, The exhaust gas can be efficiently sent into the cylinder of DE3. In addition, smoke does not deteriorate. If the throttle opening of the EGR valve 4 is less than 10%, the exhaust gas hardly flows into the EGR system (the amount of EGR decreases), and the exhaust gas temperature cannot be raised.

  When DE3 has a high rotational speed and DE3 has a high load and the exhaust gas temperature exceeds 200 ° C., the exhaust throttle valve 8 and the intake throttle valve 2 are controlled to open through the ECU 10.

By controlling the opening of the exhaust throttle valve 8 and the intake throttle valve 2, the exhaust gas in which PM is continuously regenerated by the exhaust purification device 7 can be efficiently sent to the exhaust port 9 and discharged to the outside. Further, in addition to the valve opening control of the exhaust throttle valve 8 and the intake throttle valve 2, by closing control of the EGR valve 4, it is possible to prevent deterioration and reduced fuel consumption of smoke and NO _x.

  The throttle opening degree of the exhaust throttle valve 8 is preferably 50% or more. By setting the throttle opening of the exhaust throttle valve 8 in such a range, exhaust gas in which PM is continuously regenerated efficiently can be sent to the exhaust port 9. If the throttle opening of the exhaust throttle valve 8 is less than 50%, the exhaust gas temperature further rises due to the exhaust resistance, and the combustion heat generated when the PM accumulated in the exhaust purification device 7 is regenerated is accumulated in the surroundings. The exhaust gas purification device 7 may be damaged by being transmitted to PM and combusting at once.

  The throttle opening of the intake throttle valve 2 is preferably 50% or more. By setting the throttle opening of the intake throttle valve 2 in such a range, the balance between the intake air amount and the fuel injection amount is improved, and smoke can be reduced and fuel consumption can be improved. If the throttle opening of the intake throttle valve 2 is less than 50%, the intake air amount becomes smaller than the fuel injection amount, and smoke increases.

  When DE3 has a high rotational speed, DE3 has a high load, and the exhaust gas temperature exceeds 200 ° C., the throttle opening degree of the EGR valve 4 is combined with the opening control of the exhaust throttle valve 8 and the intake throttle valve 2. Is preferably 10% or less. By setting the throttle opening of the EGR valve 4 in such a range, the exhaust gas is not sent into the cylinder in the DE 3 and an increase in the exhaust gas temperature can be suppressed more than necessary. In addition, by doing so, an increase in smoke can be suppressed.

  The rotational speed and engine load of the DE 3 when the exhaust throttle valve 8, the intake throttle valve 2 and the EGR valve 4 are controlled to open and close vary appropriately depending on the engine type, gear ratio, tire diameter, etc. For example, when the maximum engine speed is 3200 rpm, the exhaust throttle valve 8 and the intake throttle valve 2 are controlled to be closed and the EGR valve 4 is controlled to be opened when the speed is a low speed of idle to 2000 rpm. preferable. Further, it is preferable that the exhaust throttle valve 8 and the intake throttle valve 2 are controlled to be opened and the EGR valve 4 is controlled to be closed when the rotational speed is high at 2800 to 3000 rpm. The exhaust gas temperature when the exhaust throttle valve 8, the intake throttle valve 2 and the EGR valve 4 are controlled to be opened and closed can be appropriately changed to other than 200 ° C.

  EXAMPLES Hereinafter, although an Example demonstrates this invention in detail, this invention is not limited to this.

  FIG. 3 is a diagram showing the relationship between the 13 mode points and the weighting factors. According to the PM continuous regenerating apparatus of the present invention, since the mode point 1 is idling, the DE 3 has a low rotational speed and a low load, so the EGR system is activated and the EGR valve 4 is fully opened. (Throttle opening is set to 100%). Further, the ECU 10 controls the throttle openings of the exhaust throttle valve 8 and the intake throttle valve 2 to be 5 to 20%.

  In mode points 2 and 3, since the rotational speed of DE3 is as low as 40% and the engine load of DE3 is as low as 20 to 40%, the EGR valve 4 is fully opened as in mode point 1, and the exhaust throttle valve 8 And the throttle opening of the intake throttle valve 2 is set to 5 to 30%. Since the mode point 4 is idling like the mode point 1, the EGR valve 4 is fully opened, and the throttle openings of the exhaust throttle valve 8 and the intake throttle valve 2 are 5 to 20%.

  At mode points 5 to 9, the rotational speed of DE3 is 60 to 80%, but the engine load of DE3 is 20 to 60%, which is a medium to low load, so the throttle opening degree of EGR valve 4 is set to 100 to 50%. %, And the throttle openings of the exhaust throttle valve 8 and the intake throttle valve 2 are 5 to 50%.

  In mode points 10 to 12, since the rotational speed of DE3 is 60 to 80% and the engine load of DE3 is as high as 80 to 95%, the throttle opening degree of EGR valve 4 is set to 10% or less, and the exhaust throttle The throttle openings of the valve 8 and the intake throttle valve 2 are set to 50% or more.

  At mode point 13, since the engine load of DE3 is as low as 5%, the throttle openings of the exhaust throttle valve 8 and the intake throttle valve 2 are set to 5 to 10%, and the EGR valve 4 is fully opened.

FIG. 4 is a graph showing the relationship between the EGR rate, exhaust gas temperature, NO _x , smoke and fuel consumption at mode points 1 and 4, and FIG. 5 is the EGR rate, exhaust gas temperature, NO _x , smoke and mode at mode point 3. FIG. 6 and FIG. 6 are graphs showing the relationship between the EGR rate, exhaust gas temperature, NO _x , smoke and fuel consumption at the mode point 9.

At any mode point, as the EGR rate increases, the exhaust gas temperature, smoke and fuel consumption increase, and NO _x decreases linearly. That is, increasing the EGR amount by controlling the opening of the EGR valve 4 leads to an increase in the exhaust gas temperature, and the exhaust gas temperature introduced into the exhaust purification device 7 increases, so that the temperature condition for regenerating PM Can be advantageous. Further, since the exhaust gas is recirculated into the cylinder, the amount of inert gas in DE 3 is increased, and the maximum in-cylinder temperature is decreased, so that NO _x can be reduced.

  In FIG. 4C, during idling with a low load, smoke and fuel consumption are hardly deteriorated even if the EGR rate is 40%. Further, at the mode point 3 where the engine load of DE3 is relatively low at 40% and the throttle opening of the intake throttle valve 2 is 20.9% and the smoke limit is set to 2 BSU, the EGR rate is 35%. It becomes a limit. At this time, the deterioration in fuel consumption is 3%, which is lower than the allowable deterioration of 5%. Therefore, when DE3 has a low rotation speed and a low load, it is necessary to control the opening of the EGR valve 4 so as to keep the exhaust gas temperature high.

  On the other hand, when mode point 9 is high even at medium load (see FIG. 6C), the throttle opening of intake throttle valve 2 is 41.3%, and the EGR rate is 15% from the smoke limit. The fuel efficiency deterioration at this time is 6%, and from the fuel efficiency limit, the EGR rate needs to be about 13% which is smaller than 15%. For this reason, as the DE3 load increases, the limit of the amount of EGR that can be recirculated due to the smoke limit and the fuel consumption deterioration limit decreases. Therefore, at the mode points 10, 11, and 12, it is necessary to control the EGR valve 4 to be closed and to recirculate the exhaust gas into the DE 3 so as to minimize the smoke limit and prevent it from recirculating excessively. is there.

It is a block diagram which shows an example of PM continuous reproduction | regeneration apparatus of this invention. It is a block diagram which shows an example of another embodiment of PM continuous reproduction | regeneration apparatus of this invention. It is a figure showing the relationship between a 13 mode point and a weighting coefficient. It is a figure showing the relationship between the exhaust gas temperature in mode points 1 and 4, and an EGR rate. FIG. 5 is a diagram showing the relationship between NO _x and EGR rate at mode points 1 and 4. It is a figure showing the relationship between smoke at mode points 1 and 4 and the EGR rate. It is a figure showing the relationship between the fuel consumption in mode points 1 and 4 and an EGR rate. FIG. 6 is a graph showing the relationship between the exhaust gas temperature at mode point 3 and the EGR rate. Is a diagram showing the relationship of the NO _x and the EGR rate in mode three points. It is a figure showing the relationship between the smoke at mode point 3 and the EGR rate. It is a figure showing the relationship between the fuel consumption in mode point 3, and an EGR rate. FIG. 6 is a graph showing the relationship between the exhaust gas temperature at mode point 9 and the EGR rate. FIG. 6 is a diagram showing the relationship between NO _x and EGR rate at mode point 9. It is a figure showing the relationship between the smoke at mode point 9 and the EGR rate. It is a figure showing the relationship between the fuel consumption in mode point 9, and an EGR rate.

Explanation of symbols

1 Air cleaner 2 Inlet throttle valve 3 Diesel engine (DE)
4 EGR valve 5 Exhaust manifold 6 Exhaust brake 7 Exhaust purification device 71 Front stage 72 Front middle stage 73 Middle stage 74 Rear middle stage 75 Rear stage 8 Exhaust throttle valve 9 Exhaust port 10 ECU

Claims (23)

  An exhaust purification device that continuously regenerates PM in exhaust gas discharged from a diesel engine having an intake throttle valve and an EGR system having an EGR valve, and is installed between the diesel engine and the exhaust purification device An exhaust brake that is disposed between the exhaust purification device and the exhaust port, and an exhaust throttle valve that adjusts an amount of the exhaust gas that exhausts the exhaust gas discharged from the exhaust purification device to the exhaust port; A PM continuous reproduction apparatus comprising:   When the diesel engine has a low rotational speed, the diesel engine has a low load, and the exhaust gas temperature is 200 ° C. or less, the throttle openings of the exhaust throttle valve and the intake throttle valve are set to 5 to 5. The PM continuous regeneration device according to claim 1, wherein the throttle opening of the EGR valve is 10 to 100%.   When the diesel engine has a high rotational speed, the diesel engine has a high load, and the temperature of the exhaust gas exceeds 200 ° C., the throttle openings of the exhaust throttle valve and the intake throttle valve are set to 50%. The PM continuous regeneration apparatus according to claim 1, wherein the throttle opening of the EGR valve is 10% or less.   4. The PM continuous regeneration device according to claim 1, wherein the throttle opening degree of the exhaust throttle valve and the exhaust brake is controlled by a one-stage system, a multistage system, or a non-stage system.   The PM continuous regeneration device according to any one of claims 1 to 4, wherein the exhaust throttle valve and the exhaust brake have the same structure.   The PM continuous regeneration device according to any one of claims 1 to 5, wherein when the exhaust brake is operated, a throttle opening degree of the exhaust throttle valve is set to 100%.   The PM continuous regeneration device according to any one of claims 1 to 6, wherein when the exhaust brake is operating, a throttle opening degree of the intake throttle valve is set to 50% or more.   The PM continuous regeneration device according to any one of claims 1 to 7, wherein the exhaust purification device is a combination of a DOC and a plurality of DPFs.   The PM continuous regeneration apparatus according to claim 8, wherein the DOC and the plurality of DPFs are formed of a metal carrier, the DOC is disposed on the diesel engine side, and the plurality of DPFs are disposed immediately after the DOC.   The PM continuous regeneration apparatus according to claim 9, wherein a catalyst is supported on the DOC, and no catalyst is supported on the DPF.   The PM continuous regeneration apparatus according to claim 9, wherein the DOC and the plurality of DPFs are both configured to carry a catalyst.   The PM continuous regeneration apparatus according to claim 9, wherein a catalyst is supported on the DOC, and the catalyst is supported on at least one of the plurality of DPFs.   The PM continuous regeneration apparatus according to claim 12, wherein the DPF on which the catalyst is supported is arranged immediately after the DOC.   When there is one DPF carrying the catalyst among the three or more DPFs, the unsupported DPF is arranged immediately after the DOC, and the catalyst is supported immediately after the unsupported DPF. The PM continuous regeneration apparatus according to claim 12, wherein a DPF is disposed, and a plurality of unsupported DPFs are disposed immediately after the DPF on which the catalyst is supported.   Of the three or more DPFs, when the number of DPFs on which the catalyst is supported is two, the DPFs on which two of the catalysts are supported are arranged immediately after the DOC, and the catalyst is supported. The PM continuous regeneration apparatus according to claim 12, wherein the unsupported DPF is arranged immediately after the DPF.   Among the four or more DPFs, when there are two DPFs carrying the catalyst, the DPF carrying the catalyst is disposed immediately after the DOC, and is not carried immediately after the DPF carrying the catalyst. The DPF is arranged, the DPF carrying the catalyst is arranged immediately after the unsupported DPF, and a plurality of unsupported DPFs are arranged immediately after the DPF on which the catalyst is supported. The PM continuous regeneration apparatus according to claim 12.   When two or more DPFs on which the catalyst is supported are two or more of the DPFs, the unsupported DPF is disposed immediately after the DOC, and the catalyst is supported immediately after the unsupported DPF. An unsupported DPF is disposed immediately after the DPF on which the catalyst is supported, and the catalyst-supported DPF is disposed immediately after the unsupported DPF, immediately after the DPF on which the catalyst is supported. The PM continuous regeneration apparatus according to claim 12, wherein a plurality of unsupported DPFs are arranged on a wall.   The PM continuous regeneration device according to claim 1, wherein the exhaust purification device is made of DPF.   The PM continuous regeneration device according to claim 1, wherein the exhaust purification device is made of a DPF carrying a catalyst.   The PM continuous regeneration device according to claim 1, wherein the exhaust purification device is a DPF in which a DOC is mounted on the exhaust brake side.   The PM continuous regeneration device according to any one of claims 1 to 19, wherein the exhaust purification device is formed of a metal carrier.   21. The PM continuous regeneration device according to claim 1, wherein the exhaust purification device is a ceramic carrier.   An exhaust purification device that continuously regenerates PM in exhaust gas discharged from a diesel engine having an intake throttle valve and an EGR system having an EGR valve, and is installed between the diesel engine and the exhaust purification device An exhaust brake that is disposed between the exhaust purification device and the exhaust port, and an exhaust throttle valve that adjusts an amount of the exhaust gas that exhausts the exhaust gas discharged from the exhaust purification device to the exhaust port; The method for continuously regenerating PM, wherein the diesel engine has a low rotational speed, the diesel engine has a low load, and the exhaust gas temperature is 200 ° C. or less, the exhaust throttle valve and the The throttle opening of the intake throttle valve is 5 to 50%, and the throttle opening of the EGR valve is 10 to 100%. And when the diesel engine has a high load and the temperature of the exhaust gas exceeds 200 ° C., the throttle opening of the exhaust throttle valve and the intake throttle valve is set to 50% or more, and the EGR valve The continuous PM regeneration method is characterized in that the throttle opening is 10% or less.

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