JP4292923B2 - Exhaust gas purification method and exhaust gas purification system for internal combustion engine - Google Patents

Description

  The present invention relates to an exhaust gas purification method and an exhaust gas purification system for an internal combustion engine that includes a continuous regeneration type diesel particulate filter (DPF) in a diesel engine with a glow plug and purifies the exhaust gas of the engine.

  The amount of particulate matter discharged from diesel engines (PM: particulate matter: hereinafter referred to as PM) is being regulated year by year along with NOx, CO and HC. Improvement alone has made it impossible to respond. Therefore, a technology has been developed that collects PM discharged from the engine with a filter called a diesel particulate filter (DPF) and reduces the amount of PM discharged to the outside. Yes.

  The DPF that directly collects PM includes ceramic monolith honeycomb wall flow type filters and fiber type filters made of ceramic or metal fibers. Exhaust gas purification using these DPFs Similar to other exhaust gas purification systems, the system is installed in the middle of the exhaust passage of the engine to purify and discharge exhaust gas generated in the engine.

  When the filter collects PM, the exhaust pressure rises in proportion to the amount of collected DPF. Therefore, it is necessary to regenerate the DPF by removing the collected PM by burning or the like. Various methods have been proposed, such as an electric heater heating type, a burner heating type, and a backwash type.

  However, when these regeneration methods are used, PM is burned by receiving energy supply from the outside, which leads to deterioration of fuel consumption, and control during regeneration is difficult, and PM collection, PM combustion (DPF) There is a problem that the system becomes large and complicated, such as requiring a two-system DPF system that alternately performs (regeneration).

  In order to solve this problem, a technique has been proposed in which the oxidation temperature of PM is lowered using an oxidation catalyst, and PM is oxidized by exhaust heat from the engine to regenerate DPF without receiving energy from the outside. In this case, since DPF regeneration is basically continuous, it is called a continuous regeneration type DPF system. However, these systems become a simpler one-system DPF system, and regeneration control is also simplified. There is an advantage that

An NO ₂ regeneration type DPF system 1X shown as an example in FIG. 5 is a system that oxidizes PM with NO ₂ (nitrogen dioxide) to regenerate DPF, and an oxidation catalyst 3Aa is disposed upstream of a normal wall flow filter 3Ab. Then, NO (nitrogen monoxide) in the exhaust gas is oxidized. Therefore, NOx in the exhaust gas of the oxidation catalyst 3Aa slipstream almost becomes NO _2. With this NO ₂ , the PM collected by the downstream filter 3Ab is oxidized to CO ₂ (carbon dioxide) to remove the PM. Since NO ₂ has a smaller energy barrier than O ₂ , the PM oxidation temperature (DPF regeneration temperature) is lowered, and PM combustion occurs continuously with the thermal energy in the exhaust gas without supplying energy from the outside.

  In FIG. 5, E is a diesel engine, 2 is an exhaust passage, 4 is a fuel pump system, 5 is an electronic control box, 7 is a battery, 8 is a silencer, and 9 is a fuel tank.

FIG. 6 shows an improved system 1Y of the NO ₂ regeneration type DPF system shown in FIG. In this improved system 1Y, the porous catalyst coat layer 31 of the oxidation catalyst 32A is applied to the porous wall surface 30 of the wall flow filter 3B, and oxidation of NO and oxidation of PM by NO ₂ generated thereby are performed, and the wall flow filter 3B. The system is simplified to be configured to do on the wall surface.

  And in FIG. 7, the porous catalyst coat layer 31 of the oxidation catalyst 32A and the PM oxidation catalyst 32B such as an oxide is applied to the porous wall surface 30 of the wall flow filter 3C, and the PM accumulated in the filter 3C is reduced at a low temperature. 1 shows a system 1Z that burns and continuously regenerates.

These catalyst-attached DPF systems are systems that realize continuous regeneration of PM by lowering the PM oxidation start exhaust temperature (PM forced combustion temperature) than the normal filter by the oxidation reaction of PM by the catalyst and NO ₂ .

  However, even if the PM oxidation start exhaust temperature is lowered, an exhaust gas temperature of about 350 ° C. is still necessary. Under idle and low load engine operating conditions, the exhaust gas temperature is insufficient, and PM oxidation and DPF regeneration are performed. Does not occur.

  Therefore, if such idle or low-load engine operating conditions are continued, the PM oxidation state does not occur even if PM accumulates, so that the exhaust pressure increases, fuel consumption deteriorates, and troubles such as engine stop occur. There is a fear.

  Therefore, in these continuous regeneration type DPF systems, it is necessary to regenerate the DPF by calculating the PM accumulation amount in the filter from the engine operating conditions or estimating the PM accumulation amount from the filter pressure loss corresponding to the PM accumulation amount. Conditions are set and DPF regeneration control is performed to forcibly burn and remove the accumulated PM when this DPF regeneration requirement is satisfied.

  This DPF regeneration control is a multi-stage injection (split injection) in an electronically controlled fuel injection system such as a common rail, and combines early injection and delayed injection to increase negative work in the piston cycle by early injection. Fuel that increases NOx in exhaust gas required to oxidize PM without changing the amount of torque generated in the engine even under low load conditions, and raises the temperature of exhaust gas above the PM forced combustion temperature by delayed injection An injection control method and a regeneration control method for a continuous regeneration type DPF have been proposed, and the effect has been confirmed depending on operating conditions (for example, see Patent Document 1).

  The increase in NOx in the exhaust gas, the temperature rise of the exhaust gas, and the occurrence of negative work by this fuel injection control method are the same as the injection of the first fuel injection injected extremely early in the multi-stage injection. This is realized by igniting and causing the cylinder (inside the cylinder) to become high pressure and high temperature before top dead center.

  However, when it is cold or under extremely low load conditions, if the early injection is performed with an extremely early injection timing, the in-cylinder temperature does not reach the ignition temperature of the injected fuel, so the fuel is injected with early injection. There is a problem that the fuel does not ignite, the inside of the cylinder does not become high pressure and high temperature before top dead center, and sufficient effects cannot be obtained for NOx increase, exhaust gas temperature rise, and negative work generation.

On the other hand, diesel engines equipped with these continuously regenerating DPFs are often equipped with glow plugs (preheating plugs, heating plugs) that become hot when energized. Diesel engines are spontaneously ignited by highly compressing the air-fuel mixture, but when the outside air temperature is low, such as in winter, the air-fuel mixture becomes cold, making it difficult to spontaneously ignite, making it difficult to start the engine. Only at the start, the glow plug preheats the inside of the cylinder, particularly the combustion chamber, so that the fuel at the start of the engine is easily ignited. When the engine is started and warmed up, the preheating by the glow plug is finished.
JP 2002-276443 A

  The present invention has been made to solve the above-mentioned problems by using a glow plug already provided or newly providing a glow plug, and its purpose is to control regeneration at a low temperature of exhaust gas. In continuous regeneration type DPF that performs multi-stage injection composed of early injection and delayed injection, output torque is increased by using glow assist heating that is turned on at the time of execution of at least early injection of multi-stage injection to heat the inside of the cylinder The present invention provides an exhaust gas purification method and an exhaust gas purification system that can efficiently perform DPF regeneration by increasing NOx in exhaust gas and significantly increasing exhaust gas temperature while preventing fluctuations in the exhaust gas. is there.

An exhaust gas purification system for achieving the above object comprises a continuous regeneration type DPF in an exhaust passage of an internal combustion engine, and when the regeneration control operation of the continuous regeneration type DPF is required, the continuous regeneration type When the exhaust temperature at the inlet of the mold DPF is lower than the PM forced combustion temperature at which the PM collected in the continuous regeneration DPF starts combustion, fuel injection is performed earlier than the proper fuel injection timing of fuel injection in normal operation In an exhaust gas purification system for an internal combustion engine that performs regeneration control operation with multi-stage injection that performs early injection and delay injection that injects fuel at a later time, when the regeneration control operation of the continuous regeneration type DPF is requested, wherein when the exhaust gas temperature at the inlet of the continuous regeneration type DPF is lower than the PM forced combustion temperature, in addition to the multi-stage injection, which is turned on glow plug provided in the engine Performing a first control for heating the cylinder in the state, the control of the first, the continuous regeneration inlet of the exhaust gas temperature of the DPF becomes more the PM forced combustion temperature, and the playback control operation request is state have rows until no, when the reproduction control operation of the continuous regeneration type DPF is requested, the exhaust gas temperature at the inlet of the continuous regeneration type DPF is when more than the PM forced combustion temperature, which is off the glow plug Thus, it is configured as a method of performing the second control in which the temperature control suitable for the PM oxidation removal is performed until the request for the regeneration control operation disappears .

The exhaust gas purification system includes a continuous regeneration type DPF in the exhaust passage of the internal combustion engine, and when the regeneration control operation of the continuous regeneration type DPF is required, the exhaust temperature at the inlet of the continuous regeneration type DPF is When the PM collected in the continuous regeneration type DPF is lower than the PM forced combustion temperature at which combustion starts, the fuel is injected at an early timing and at a later timing than the proper fuel injection timing of fuel injection in normal operation. In an exhaust gas purification system for an internal combustion engine having a regeneration control device with multi-stage injection for performing delayed injection to be injected, when the regeneration control operation of the continuously regenerating DPF is requested, the inlet of the continuously regenerating DPF when exhaust gas temperature is lower than the PM forced combustion temperature, in addition to the multiple injection to heat the in-cylinder in the state of being turned on a glow plug provided in the engine Performs first control, the control of the first, the exhaust temperature at the inlet of the continuous regeneration type DPF becomes higher the PM forced combustion temperature, and have rows until the request is eliminated in the playback control operation, the continuous regeneration type When the regeneration control operation of the DPF is required, if the exhaust temperature at the inlet of the continuous regeneration DPF is equal to or higher than the PM forced combustion temperature, the glow plug is turned off and suitable for the oxidation removal of PM. The second control is performed so that the temperature control is performed until the regeneration control operation is no longer required .

  According to the above configuration, in the regeneration control operation, the in-cylinder and the in-cylinder in the early injection are injected by performing glow assist heating in the cylinder while being turned on at the time of execution of at least the early injection of the multistage injection (split injection). Due to the heating of the fuel spray, negative work is generated and at the same time the amount of NOx generated increases. And since negative work occurs in early injection, the amount of delayed injection can be increased and the temperature of exhaust gas can be significantly increased without increasing the output output.

  Therefore, even under the operating conditions of the internal combustion engine in an idling or low load range, it is possible to efficiently raise the temperature of the exhaust gas and increase the amount of exhausted NOx to perform DPF regeneration. In addition, since DPF regeneration can be performed at any time, an increase in exhaust pressure due to excessive accumulation of PM can be suppressed, and engine stall due to this high exhaust pressure can be avoided. Further, the temperature of the exhaust gas can be increased efficiently, so that fuel efficiency can be improved.

  And, since the exhaust gas is low temperature, DPF regeneration cannot be performed and the phenomenon of excessive accumulation of PM can be avoided. Therefore, an accident in which PM runs away during PM ignition after this excessive accumulation of PM and the filter is damaged. Can be prevented.

  In the exhaust gas purification system for an internal combustion engine, the continuous regeneration type DPF includes a continuous regeneration type DPF in which an oxidation catalyst is supported on a filter that collects PM, and an upstream side of the filter that collects PM. A continuous regeneration type DPF provided with a catalyst, a continuous regeneration type DPF in which an oxidation catalyst is carried on a filter that collects PM, and an oxidation catalyst is provided on the upstream side of the filter can be employed.

  According to the exhaust gas purification method and exhaust gas purification system of an internal combustion engine of the present invention, in a continuous regeneration type DPF having an oxidation catalyst and a DPF with a catalyst, the exhaust gas temperature is insufficient in the conventional technology, and DPFPM forced regeneration combustion can be performed. DPF regeneration can be performed by efficiently raising the temperature of the exhaust gas and increasing the amount of exhausted NOx even under the operating conditions of the engine in the idle, low load region, etc. that did not exist. Moreover, since exhaust gas can be raised efficiently, fuel consumption can be improved.

  And because DPF regeneration can be performed at any time even in the idling or low-load engine operating range, it becomes possible to perform DPF regeneration at any time, which suppresses an increase in exhaust pressure due to excessive accumulation of PM, resulting from this high exhaust pressure To avoid engine stall. In addition, since the phenomenon of excessive PM accumulation due to the inability to regenerate the DPF can be avoided, it is possible to prevent accidents in which the PM runs away and burns out when the PM is ignited after this excessive PM accumulation.

  Hereinafter, regarding an exhaust gas purification method and an exhaust gas purification system according to an embodiment of the present invention, a continuous regeneration type DPF (diesel particulate filter) composed of a combination of an upstream oxidation catalyst and a downstream filter with a catalyst is provided. An example will be described with reference to the drawings.

  1 and 2 show the configuration of the exhaust gas purification system 1 of this embodiment. In this exhaust gas purification system 1, a continuous regeneration type DPF 3 configured by having an oxidation catalyst 3 </ b> Aa on the upstream side and a filter with a catalyst 3 </ b> Ab on the downstream side is provided in the exhaust passage 2 connected to the exhaust manifold 11 of the diesel engine E. It has been.

  This oxidation catalyst 3Aa is formed by carrying an oxidation catalyst such as platinum (Pt) on a carrier such as a porous ceramic honeycomb structure, and the filter with catalyst 3Ab is formed at the inlet of the channel of the porous ceramic honeycomb. And a monolith honeycomb wall flow type filter in which the outlets are alternately sealed. A catalyst such as platinum or cerium oxide is supported on the filter. In this filter with catalyst 3Ab, PM (particulate matter) in the exhaust gas G is collected (trapped) by a porous ceramic wall.

  In order to estimate the amount of PM deposited on the catalyst-attached filter 3Ab, a differential pressure sensor 21 is provided on the conducting pipe connected before and after the continuous regeneration type DPF device 3. An exhaust temperature sensor 22 is provided in the vicinity of the inlet of the continuous regeneration type DPF device 3 for regeneration control of the filter with catalyst 3Ab.

  The output values of these sensors are input to a control device (electronic control box: ECU: engine control unit) 5 that performs overall control of the operation of the engine E and also performs regeneration control of the filter 3Ab with catalyst. The control signal output from the device 5 controls the fuel injection valve 15 of the engine E, the intake valve 11 provided in the intake passage 6 and adjusting the intake amount to the intake manifold.

  The fuel injection valve 15 is connected to a common rail (not shown) that temporarily stores high-pressure fuel that has been boosted by a fuel pump (not shown). Information such as ON / OFF of the switch, ON / OFF of the neutral switch, vehicle speed, cooling water temperature, engine speed, accelerator opening, etc. is also input.

  Then, the intake air A passes through the compressor 17 a of the turbocharger 17 and the intercooler 12 in the intake passage 6, adjusts the intake amount by the intake valve 11, and then enters the combustion chamber 14 in the cylinder 13. The combustion chamber 14 is provided with a fuel injection valve 15 and a glow plug 16. By fuel injection from the fuel injection valve 15, the fuel and the intake air A are mixed, and by compression of the piston 18, it spontaneously ignites and burns to generate exhaust gas G. The exhaust gas G enters the continuous regeneration type DPF 3 via the turbine 17 b of the turbocharger 17 in the exhaust passage 2, becomes purified exhaust gas Gc, and is released into the atmosphere via the silencer 8. The

  In this exhaust gas purification system 1, the differential pressure of the differential pressure sensor 21 increases, and the PM accumulation amount of the filter 3Ab with catalyst of the continuous regeneration type DPF device 3 exceeds the set amount that needs to be regenerated. When the exhaust temperature required for PM oxidation and DPF regeneration is not reached due to idling or low load, exhaust gas temperature rise control is performed to regenerate the continuous regeneration type DPF device 3.

  In the regeneration control in the exhaust gas purification system 1, detection values ΔP and T1 of the differential pressure sensor 21 and the exhaust temperature sensor 22 are input to the control device 5 to control the fuel injection valve 15, the glow plug 16, the intake valve 11, and the like. And do it.

  In the present invention, in the regeneration control of the continuous regeneration type DPF device 3, the differential pressure ΔP of the differential pressure sensor 21 is increased and the regeneration start control is required, but the engine operating conditions are idle, a low load region, etc. When the temperature of the exhaust gas does not reach the temperature required for DPF regeneration in the operating state, or when the amount of NOx in the exhaust gas does not reach the amount required for DPF regeneration, the regeneration control operation combined with glow assist heating To raise the temperature of the exhaust gas and increase the amount of NOx in the exhaust gas to perform DPF regeneration.

  This regeneration control operation combined with glow assist heating is a regeneration control operation in which the glow plug 16 is also turned on when multistage injection (early injection + delayed injection) is executed. FIG. 3 shows an operating acupressure diagram in this multi-stage injection (split injection). In FIG. 3, two-stage multi-stage injection is used, but more stages are more preferable.

  In the multi-stage injection combined with the glow assist heating, as shown in FIG. 3, the injection timing t1 of the first stage of fuel injection is extremely earlier than the proper fuel injection timing tn of fuel injection in normal operation. At the same time, glow assist heating is performed with at least the glow plug 16 turned on at the early injection timing (A), thereby heating the cylinder (inside the cylinder) and the injected fuel spray, and negative work (Wm). At the same time as generating NOx. At this time, the temperature of the working gas in the cylinder also increases (B).

  The glow plug 16 may be kept on during the multi-stage injection, but it suffices if the early injection fuel can be ignited at the same time as the injection, and the on period is also around the early injection timing in consideration of the response speed of the glow plug 16. Only it is good.

  Next, fuel injection of the second-stage delayed injection is performed. In this injection, an amount of fuel that can overcome the negative work (Wm) of the first stage and extract positive work (Wp) is injected. At this time, in order to raise the temperature of the exhaust gas, the second stage injection timing t2 is delayed from the proper fuel injection timing tn of the fuel injection in the normal operation, that is, the retard side.

  In these injection controls, the timing t1 of the first-stage fuel injection can be extremely advanced by glow assist heating, so that the amount of exhausted NOx can be increased. Further, since the in-cylinder temperature is very high in the first stage fuel injection, the retard amount at the second stage injection timing can be increased, and the temperature of the exhaust gas can be greatly increased. Moreover, since negative work (Wm) is performed by the first-stage fuel injection, the second-stage injection amount can be increased without increasing the output output (Wo = Wp-Wm). The exhaust gas temperature can be raised significantly even in the operation state of the region.

  Therefore, the exhaust gas temperature and the NOx amount necessary for DPF regeneration can be ensured when DPF regeneration is required even under idling or low load operating conditions. In addition, since the output output (generated output) can be controlled by controlling the ratio of the first stage injection amount and the second stage injection amount, the normal operation and the regeneration control operation are controlled by this ratio control. The fluctuation of output torque at the time of switching to can be prevented.

  Next, an exhaust gas purification method for performing this glow assist heating combined regeneration control operation will be described. This exhaust gas purification method is performed according to the control flow illustrated in FIG.

  The control flow in FIG. 4 is a control throw illustrated as a regeneration control flow incorporated in the main control flow for controlling the entire vehicle including the engine E, and is repeatedly called from the main control flow that starts when the start switch of the engine E is turned on. And repeat execution.

  When the control flow of FIG. 4 is called from the main control flow and starts, in step S10, the normal injection control operation is performed for a predetermined time (time related to the time interval for determining whether or not to start regeneration). In this normal injection control operation, regardless of the regeneration of the DPF, normal fuel injection is performed with respect to the engine speed and load required for the engine, and the glow plug 16 is also other than preheating such as when warming up in the cold period. Then it is driven off.

  In the next step S11, whether or not the PM collection state of the catalyst-attached DPF 3Ab is in a regeneration start state requiring regeneration control, the differential pressure ΔP detected by the differential pressure sensor 21 is a predetermined regeneration start differential pressure. The determination is made based on whether or not the determination value ΔP0 is reached.

  This regeneration start is determined by calculating the PM accumulation amount of the DPF 3 Ab with catalyst while referring to the PM accumulation amount map data input in advance from the engine operating state, and the PM accumulation which is the sum of the PM accumulation amounts. The amount may be calculated, and the regeneration may be started when the PM accumulation amount becomes larger than a predetermined limit accumulation amount.

  As long as the differential pressure ΔP is smaller than the regeneration start differential pressure determination value ΔP0 in this regeneration start determination, it is determined that the regeneration is not started, and the routine returns to step S10 to repeat the normal injection control operation. In this regeneration start determination, the differential pressure ΔP becomes equal to or greater than the regeneration start differential pressure determination value ΔP0, and if the regeneration is started, the process goes to step S12.

In step S12, it is determined whether or not the exhaust temperature (DPF inlet exhaust temperature) T1 detected by the exhaust temperature sensor 22 is smaller than the PM forced combustion temperature Tpm. The PM forced combustion temperature Tpm is a temperature at which PM trapped in the DPF 3Ab with catalyst is forcibly burned and removed by NOx or O ₂ in the exhaust gas if the exhaust temperature T1 is equal to or higher than the temperature Tpm. , PM oxidation start exhaust gas temperature is the same.

  In this determination, when the exhaust gas temperature T1 is equal to or higher than the PM forced combustion temperature Tpm, the glow plug-off normal PM regeneration control operation in step S16 is related to a predetermined time (determining whether or not the regeneration of the DPF is completed). To determine whether or not the regeneration of the DPF has ended in step S17, and determines whether or not the differential pressure ΔP before and after the DPF has become smaller than the regeneration end differential pressure determination value ΔP10.

  If the front-rear differential pressure ΔP of the DPF is not smaller than the regeneration end differential pressure determination value ΔP1, the process returns to step S16, and the normal PM regeneration control operation is repeated, and the PM accumulated in the DPF 3Ab with catalyst is burned and removed. If the differential pressure ΔP before and after the DPF becomes smaller than the regeneration end differential pressure determination value ΔP1 in the determination in step S17, the process returns to the end of the regeneration.

  In this normal PM regeneration control operation, the timing of the main injection (main injection) of the fuel injection of the engine E is delayed (retarded), post-injection (post-injection), intake throttling, etc. The temperature of the gas is raised so that the temperature and environment are suitable for the oxidation removal of PM, and the PM collected by the continuous regeneration type DPF 3 is oxidized and removed.

  For example, with an air system such as an intake throttle, EGR, VNT, etc., the NOx concentration in the exhaust gas is increased and post injection is performed, so that the target temperature is set to about 500 ° C. and the state is maintained for a set time, Thereafter, while performing similar control, the target temperature is set to about 600 ° C. and the state is maintained for a set time, whereby PM is burned and regeneration is performed.

  If it is determined in step S12 that the exhaust gas temperature T1 is lower than the PM forced combustion temperature Tpm, the glow-assisted heating combined regeneration control operation in step S13 is performed for a predetermined time (a time interval for checking the exhaust gas temperature T1) until it becomes higher. The exhaust temperature is checked again in step S14. If the exhaust gas temperature T1 becomes higher than the PM forced combustion temperature Tpm in the exhaust gas temperature check, the process goes to step S15, and if it is smaller, the process returns to step S13.

  In the glow assist heating combined regeneration control operation of step S13, as described above, multistage injection (early injection) that uses glow assist heating that heats the inside of the cylinder with the glow plug 16 turned on at the time of execution of early injection as described above. + Delayed injection) regeneration control operation, and by glow assist heating, in-cylinder and the injected fuel spray are heated at the time of early injection execution to generate negative work (Wm) and at the same time reduce the amount of NOx generated Increase the exhaust gas temperature at the next delayed injection. At this time, since negative work (Wm) is generated by early injection, the second stage injection amount can be increased without increasing the output output (Wo = Wp-Wm), so the exhaust gas temperature is significantly increased. it can.

  By the glow assist heating combined regeneration control operation in step S13, the temperature of the exhaust gas flowing into the continuous regeneration type DPF 3 is raised above the PM forced combustion temperature Tpm, and the NOx amount is increased to an amount necessary for DPF regeneration. DPF regeneration is performed.

  Next, in step S15, it is determined whether or not the regeneration of the DPF has ended by whether or not the differential pressure ΔP before and after the DPF has become smaller than the regeneration end differential pressure determination value ΔP1. If the front-rear differential pressure ΔP of the DPF is not smaller than the regeneration end differential pressure determination value ΔP1, the process returns to step S13, and the glow-assisted heating combined regeneration control operation of step S13 is repeated until it becomes smaller and accumulated in the DPF 3Ab with catalyst. If the PM is burned and removed, and if the differential pressure ΔP before and after the DPF becomes smaller than the regeneration end differential pressure determination value ΔP1 in the determination in step S15, it is determined that the regeneration is completed and the process returns.

  Then, the regeneration control flow of the DPF in FIG. 4 is completed, the process returns to the main control flow, is called again, and is repeated until the engine is stopped. Although not particularly illustrated, when the engine key is turned off, an interrupt occurs even during the execution of the control flow, and the process returns to the main control flow.

  According to the exhaust gas purification system 1 configured as described above, in the regeneration control of the DPF, when the DPF inlet exhaust temperature T1 detected by the exhaust temperature sensor 22 is equal to or lower than the PM forced combustion Tpm, the glow plug 16 is at least executed at the early injection time. Glow-assist heating combined regeneration control operation that heats the inside of the cylinder and performs multi-stage injection in the on state can efficiently raise the temperature of the exhaust gas even in the idling or low load range, and exhaust NOx Can increase the amount.

  In the above description, the continuous regeneration type DPF is exemplified as a continuous regeneration type DPF in which an oxidation catalyst is supported on a filter that collects PM and an oxidation catalyst is provided on the upstream side of the filter. However, the present invention can be applied to a continuous regeneration type DPF in which an oxidation catalyst is supported on a filter that collects PM, and a continuous regeneration type DPF in which an oxidation catalyst is provided on the upstream side of a filter that collects PM.

1 is a system configuration diagram of an exhaust gas purification system according to an embodiment of the present invention. It is a figure which shows the structure of the engine part of the exhaust-gas purification system which concerns on this invention. It is a figure which shows the operation shiatsu diagram in the glow-assist-heat combined regeneration control operation which concerns on this invention. It is a figure which shows an example of the control flow of the reproduction | regeneration control which concerns on this invention. It is a system block diagram which shows an example of the exhaust gas purification system of a prior art. It is a system block diagram which shows another example of the exhaust-gas purification system of a prior art. It is a system block diagram which shows another example of the exhaust-gas purification system of a prior art.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Exhaust gas purification system 2 Exhaust passage 3 Continuous regeneration type particulate filter 3Aa Oxidation catalyst 3Ab Catalyzed filter 13 Cylinder 15 Fuel injection valve 16 Glow plug E Diesel engine G Exhaust gas T1 Filter inlet exhaust temperature Tpm PM forced combustion temperature

Claims (3)

A continuous regeneration type DPF is provided in the exhaust passage of the internal combustion engine, and when the regeneration control operation of the continuous regeneration type DPF is required, the exhaust temperature at the inlet of the continuous regeneration type DPF is captured by the continuous regeneration type DPF. When the collected PM is lower than the PM forced combustion temperature at which combustion starts, an early injection for injecting fuel at an earlier time than an appropriate fuel injection timing for fuel injection in normal operation and a delayed injection for injecting fuel at a later time are executed. In an exhaust gas purification system for an internal combustion engine that performs regeneration control operation involving multi-stage injection,
When the regeneration control operation of the continuous regeneration type DPF is requested, when the exhaust temperature at the inlet of the continuous regeneration type DPF is lower than the PM forced combustion temperature, a glow plug provided in the engine is added to the multistage injection. Turn on state performs first control for heating the cylinder, the control of the first exhaust temperature at the inlet of the continuous regeneration type DPF becomes higher the PM forced combustion temperature, and the playback control operation There line until the request is no longer of,
When the regeneration control operation of the continuous regeneration type DPF is requested, if the exhaust temperature at the inlet of the continuous regeneration type DPF is equal to or higher than the PM forced combustion temperature, the glow plug is turned off to oxidize the PM. An exhaust gas purification method for an internal combustion engine, characterized in that second control is performed in which temperature control suitable for removal is performed until the demand for the regeneration control operation disappears . A continuous regeneration type DPF is provided in the exhaust passage of the internal combustion engine, and when the regeneration control operation of the continuous regeneration type DPF is required, the exhaust temperature at the inlet of the continuous regeneration type DPF is captured by the continuous regeneration type DPF. When the collected PM is lower than the PM forced combustion temperature at which combustion starts, an early injection for injecting fuel at an earlier time than an appropriate fuel injection timing for fuel injection in normal operation and a delayed injection for injecting fuel at a later time are executed. In an exhaust gas purification system for an internal combustion engine equipped with a regeneration control device with multi-stage injection,
When the regeneration control operation of the continuous regeneration type DPF is requested, when the exhaust temperature at the inlet of the continuous regeneration type DPF is lower than the PM forced combustion temperature, a glow plug provided in the engine is added to the multistage injection. Turn on state performs first control for heating the cylinder, the control of the first exhaust temperature at the inlet of the continuous regeneration type DPF becomes higher the PM forced combustion temperature, and the playback control operation There line until the request is no longer of,
When the regeneration control operation of the continuous regeneration type DPF is requested, if the exhaust temperature at the inlet of the continuous regeneration type DPF is equal to or higher than the PM forced combustion temperature, the glow plug is turned off to oxidize the PM. The temperature control suitable for the removal is performed until the request for the regeneration control operation is eliminated.
2. An exhaust gas purification system for an internal combustion engine , wherein control for performing control 2 is performed .   The continuous regeneration type DPF collects a continuous regeneration type DPF in which an oxidation catalyst is supported on a filter that collects PM, and a continuous regeneration type DPF in which an oxidation catalyst is provided upstream of the filter that collects PM, PM. 3. The exhaust gas purification system for an internal combustion engine according to claim 2, wherein the filter is one of a continuous regeneration type DPF in which an oxidation catalyst is supported on a filter and an oxidation catalyst is provided upstream of the filter.

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