JP2010090852A - Control device for exhaust emission control device, control method for exhaust emission control device, and exhaust emission control device for internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a control device for an exhaust emission control device, a control method for the exhaust emission control device and the exhaust emission control device for an internal combustion engine, shortening a waiting time for reducing an amount of ammonia adsorbed in a reduction catalyst in performing the forced regeneration of a particulate filter and preventing the clogging of the particulate filter during the waiting time. <P>SOLUTION: The control device includes a section for determining the performance of the forced regeneration, a section for controlling the performance of the forced regeneration, an ammonia slip estimation section for determining whether or not an ammonia slip can occur with the execution of the forced regeneration, a section for commanding the stop of reducing agent supply, which stops supplying a reducing agent when it is determined that the ammonia slip can occur with the execution of the forced regeneration, a section for commanding waiting of the regeneration, which puts off the execution of the forced regeneration for a predetermined period when it is determined that the ammonia slip can occur with the performance of the forced regeneration, and a section for controlling an increase in a NOx flow rate, which increases the flow rate of NOx flowing in the reduction catalyst within the predetermined period. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

The present invention relates to an exhaust purification device control device, an exhaust purification device control method, and an exhaust purification device for an internal combustion engine. More particularly, the present invention relates to an exhaust purification device control device, an exhaust purification device control method, and an exhaust purification device for an internal combustion engine, each having a particulate filter that collects exhaust particulates and a reduction catalyst that reduces NO _x using a reducing agent. .

An exhaust gas discharged from an internal combustion engine such as a diesel engine contains exhaust particulates and nitrogen oxides (hereinafter referred to as “NO _X ”). A particulate filter that collects fine particles, a reduction catalyst that selectively reduces NO _x using a reducing agent, and the like are provided. In recent years, exhaust gas regulation values have increased, and exhaust purification apparatuses equipped with both a particulate filter and a reduction catalyst have begun to be put into practical use.

  Among these, the particulate filter collects exhaust particulates when the exhaust gas passes through the particulate filter. However, as the amount of exhaust particulates increases, the pressure loss of the exhaust gas gradually increases. There is a risk of malfunction. Therefore, when the particulate filter is provided in the exhaust system of the internal combustion engine, the forced regeneration of the particulate filter that forcibly burns the exhaust particulates accumulated on the particulate filter is performed in a timely manner.

  In this forced regeneration, for example, an oxidation catalyst is provided on the exhaust gas upstream side of the particulate filter, and the unburned fuel (HC) in the exhaust gas is increased by a method such as controlling the operating conditions of the internal combustion engine. This is performed by burning exhaust particulates deposited on the particulate filter using exhaust heat generated when the catalyst is oxidized by the oxidation catalyst. Alternatively, it has also been proposed to perform forced regeneration by directly or indirectly heating the particulate filter using a heating means such as a burner provided upstream of the particulate filter.

As the reduction catalyst, for example, a reduction catalyst that adsorbs ammonia as a reducing agent and selectively reduces NO _{x in} exhaust gas flowing in using the ammonia is used. More specifically, an ammonia-derived liquid reducing agent is injected and supplied upstream of the reduction catalyst, and ammonia generated by decomposition of the reducing agent is adsorbed to the reduction catalyst, so that NO in the exhaust gas is reduced. The denitration reaction between _X and ammonia is promoted by the reduction catalyst, and NO _X is efficiently decomposed into nitrogen, water, or the like.

Here, the reduction catalyst has a property that the NO _x reduction efficiency is improved as the amount of ammonia actually adsorbed (hereinafter referred to as “actual adsorption amount”) is increased. Therefore, in order to realize good NO _x reduction efficiency, it is desirable to adsorb as much ammonia as possible to the reduction catalyst. On the other hand, the amount of adsorbable ammonia (hereinafter referred to as “saturated adsorption amount”) depends on the catalyst temperature, and the reduction catalyst has a property that the saturated adsorption amount decreases as the temperature of the reduction catalyst increases. . Therefore, when the temperature of the reduction catalyst suddenly increases from a relatively low state, the saturated adsorption amount of the reduction catalyst rapidly decreases, and a part of the ammonia that has been adsorbed by the reduction catalyst to the downstream side of the reduction catalyst. There is a risk of releasing so-called ammonia slip.

  In an exhaust emission control device equipped with both a particulate filter and a reduction catalyst, when the forced regeneration of the particulate filter is executed, the reduction catalyst is rapidly heated by the high-temperature exhaust gas, and the saturated adsorption amount of ammonia in the reduction catalyst is reduced. Since it decreases rapidly, ammonia slip is likely to occur.

In view of this, an exhaust emission control device capable of preventing ammonia slip of the reduction catalyst during forced regeneration of the particulate filter has been proposed. More specifically, the particulate filter includes a particulate filter and a reduction catalyst that selectively reduces NO _x in the exhaust gas using ammonia as a reducing agent, and when the ammonia is supplied to the reduction catalyst by the ammonia supply means, the particulates An exhaust purification device is disclosed in which when the forced regeneration of the filter is started, the supply of ammonia is stopped and the forced regeneration is started when the amount of ammonia adsorbed on the reduction catalyst becomes a predetermined value or less. (See Patent Document 1).

JP 2006-342734 A (the whole sentence, all figures)

However, in the exhaust gas purification device described in Patent Document 1, the rate of decrease in ammonia adsorbed on the reduction catalyst depends on the flow rate of NO _x flowing into the reduction catalyst, and therefore ammonia slip even during forced regeneration of the particulate filter. It may take a relatively long time before the actual adsorption amount of ammonia is reduced to such an extent that no occurrence occurs. For example, when the rotational speed of the internal combustion engine is extremely low, the NO _x concentration in the exhaust gas is relatively low, and the NO _x flow rate flowing into the reduction catalyst is relatively small. For this reason, when it is necessary to forcibly regenerate the particulate filter during idling or traffic jam of the internal combustion engine, it may take a long time for the actual adsorption amount of ammonia to decrease to a predetermined value or less. There is a possibility that execution of forced regeneration of the particulate filter may be waited for a long time.

  If the forced regeneration of the particulate filter is made to wait for a long time, exhaust particulate accumulates further on the particulate filter during that period, causing the particulate filter to be completely clogged, causing a malfunction of the internal combustion engine, There is a risk of deterioration.

Therefore, the inventors of the present invention diligently tried to stop the supply of the reducing agent and to wait for a predetermined period of execution of the forced regeneration when there is a risk of ammonia slip accompanying the forced regeneration of the particulate filter, The inventors have found that such a problem can be solved by increasing the flow rate of NO _x flowing into the reduction catalyst during a predetermined period, and have completed the present invention. That is, the present invention reduces the waiting time for reducing the amount of ammonia adsorbed on the reduction catalyst before the forced regeneration of the particulate filter, and prevents the particulate filter from being clogged during the waiting time. It is an object of the present invention to provide a control device for an exhaust purification device, a control method for the exhaust purification device, and an exhaust purification device for an internal combustion engine.

The present invention includes a particulate filter that collects exhaust particulates in exhaust gas discharged from an internal combustion engine, and a reduction catalyst that selectively purifies NO _{x in} exhaust gas using a reducing agent. In the exhaust emission control device for controlling the exhaust emission control device, a forced regeneration execution determination unit that determines whether or not forced regeneration of the particulate filter is necessary, a forced regeneration execution control unit that executes forced regeneration, and forced regeneration An ammonia slip estimator that determines whether or not ammonia slip can occur with the execution of the reductant, and a reducing agent that stops the supply of the reducing agent when it is determined that ammonia slip can occur with the execution of forced regeneration A supply stop instruction unit and a regeneration standby instruction for waiting for a predetermined period of execution of forced regeneration when it is determined that ammonia slip may occur due to execution of forced regeneration. And parts, and controls the operating condition of the internal combustion engine within a predetermined time period, the NO _X flow rate increasing control unit to increase the NO _X flow rate flowing into the reduction catalyst, the controller of the exhaust purification apparatus comprising: a is Provided and can solve the above-mentioned problems.

  Further, when configuring the control device for the exhaust gas purification apparatus according to the present invention, the regeneration standby instruction unit determines when the accumulated amount of exhaust particulates collected by the particulate filter reaches the limit accumulation amount of the particulate filter. It is preferable to set a predetermined period with a limit of.

  In configuring the control device for the exhaust gas purification apparatus of the present invention, it is preferable that the regeneration standby instruction unit sets a predetermined period based on the deposition rate or deposition rate of exhaust particulates deposited on the particulate filter.

Further, when configuring the control device for the exhaust gas purification apparatus of the present invention, the NO _X flow rate increase control unit calculates the target NO _X amount to flow into the reduction catalyst when it is determined that ammonia slip can occur, it is preferable to increase the NO _X flow rate depending on the amount of NO _X.

Further, in configuring the control device for the exhaust gas purification apparatus of the present invention, the NO _X flow rate increase control unit determines that the integrated amount of NO _X flowing into the reduction catalyst has a predetermined period when it is determined that ammonia slip can occur. increasing the NO _X flow rate so as to gradually reach the target amount of NO _X over is preferred.

Another aspect of the present invention provides a particulate filter that collects exhaust particulates in exhaust gas discharged from an internal combustion engine, and a reduction catalyst that selectively purifies NO _{x in} exhaust gas using a reducing agent. And determining whether ammonia slip can occur in accordance with execution of forced regeneration before performing forced regeneration of the particulate filter, and determining that ammonia slip can occur In this case, the supply of the reducing agent is stopped and the execution of forced regeneration is waited for a predetermined period, and the operating condition of the internal combustion engine is controlled to increase the NO _x flow rate flowing into the reduction catalyst, thereby A control method for an exhaust gas purification apparatus, wherein forced regeneration is executed after reducing the actual adsorption amount of ammonia.

Moreover, carrying out the control method of the exhaust gas purifying apparatus of the present invention to increase the NO _X flow rate, after reducing the actual adsorption amount of ammonia in the reduction catalyst, the control for executing forced regeneration, the rotation speed of the internal combustion engine It is preferable to perform when the value is equal to or less than a predetermined value.

Further, another aspect of the present invention provides a particulate filter that collects exhaust particulates in exhaust gas discharged from an internal combustion engine, and an exhaust gas that is provided on the exhaust downstream side of the particulate filter and uses ammonia as a reducing agent. NO which in an exhaust gas purification apparatus for an internal combustion engine and a reduction catalyst for purifying NO _X in the flows forced regeneration means by elevating the temperature of the particulate filter the forced regeneration of the particulate filter, and the reduction catalyst provided with a NO _X flow rate increasing means for increasing the _X rate, the forced regeneration execution judging unit judges necessity of forced regeneration of the particulate filter, and forced regeneration execution control unit for executing the forced regeneration, the forced regeneration An ammonia slip estimator for determining whether or not ammonia slip can occur with execution, and execution of forced regeneration. When it is determined that ammonia slip can occur, a reducing agent supply stop instruction unit that stops supply of the reducing agent, and when it is determined that ammonia slip can occur along with execution of forced regeneration, forced regeneration is performed. A control device that includes a regeneration standby instruction unit that waits for execution for a predetermined period, and a NO _X flow rate increase control unit that controls the operating conditions of the internal combustion engine within a predetermined period to increase the NO _X flow rate flowing into the reduction catalyst. An exhaust emission control device for an internal combustion engine, comprising:

According to the exhaust purification device control device and the exhaust purification device control method of the present invention, when it is determined that ammonia slip may occur due to the forced regeneration of the particulate filter, the supply of the reducing agent is stopped. At the same time, execution of forced regeneration is waited for a predetermined period, and control for increasing the NO _x flow rate flowing into the reduction catalyst is performed within the predetermined period. Therefore, the control device for the exhaust gas purification device and the control method for the exhaust gas purification device according to the present invention increase the decrease rate of ammonia adsorbed on the reduction catalyst, and shorten the waiting time until the forced regeneration of the particulate filter. Can do. Therefore, clogging of the particulate filter during the waiting time until the forced regeneration is prevented, and the deterioration of the filter and the malfunction of the internal combustion engine are prevented.

  Further, in the control device of the exhaust gas purification apparatus of the present invention, the predetermined period for waiting for forced regeneration is set by the time when the amount of exhaust particulate accumulation reaches the limit accumulation amount of the particulate filter, so that the particulate filter The forced regeneration is surely executed before clogging occurs.

  In the control device for the exhaust gas purification apparatus of the present invention, the predetermined period for waiting for forced regeneration is set based on the deposition rate or deposition rate of the exhaust particulates on the particulate filter, so that the amount of exhaust particulates deposited can be reduced. The time when the limit accumulation amount of the particulate filter is reached can be estimated more accurately.

In the control device of the exhaust purification system of the present invention, by NO _X flow rate is increased in accordance with the target amount of NO _X to flow into the reduction catalyst, ammonia slip with the forced regeneration execution is reduced to a degree that does not cause NO _x corresponding to the amount of ammonia to be introduced flows into the reduction catalyst without excess or deficiency. As a result, it is possible to prevent the ammonia adsorbed on the reduction catalyst from being reduced more than necessary or the ammonia from being sufficiently reduced. Therefore, ammonia slip accompanying forced regeneration of the particulate filter is reliably prevented, and the actual adsorption amount of ammonia during forced regeneration is prevented from being significantly reduced.

In the control device of the exhaust purification system of the present invention, by increasing the NO _X flow rate as integrated amount of the NO _X flowing into the reduction catalyst reaches a gradual target amount of NO _X over a predetermined time, NO _X The increase in flow rate does not become excessively large. Therefore, the peak value of noise that can be generated as the NO _x flow rate is increased is suppressed.

  Further, in the control method for the exhaust gas purification apparatus of the present invention, the exhaust particulates discharged from the internal combustion engine when the internal combustion engine is idling or congested by performing the above control when the rotational speed of the internal combustion engine is a predetermined value or less. Even when the particulate filter must be forcibly regenerated in an operating situation where it is relatively easy to increase, the actual amount of ammonia adsorbed on the reduction catalyst quickly decreases before the exhaust particulate accumulation reaches its limit. The forced regeneration of the particulate filter can be executed.

  Further, according to the exhaust gas purification apparatus for an internal combustion engine of the present invention, by providing the control device having the above-described configuration, the actual adsorption amount of ammonia in the reduction catalyst is reduced before the amount of exhaust particulates reaches the limit, There is provided an exhaust emission control apparatus in which forced regeneration of a particulate filter is executed, ammonia is less emitted due to forced regeneration of the particulate filter, and clogging of the particulate filter can be reliably prevented.

  DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments relating to an exhaust purification device control device, an exhaust purification device control method, and an internal combustion engine exhaust purification device according to the present invention will be specifically described below with reference to the drawings as appropriate. However, this embodiment shows one aspect of the present invention and does not limit the present invention, and can be arbitrarily changed within the scope of the present invention. In addition, in each figure, what has attached | subjected the same code | symbol has shown the same member, and description is abbreviate | omitted suitably.

1. FIG. 1 shows the overall configuration of an exhaust emission control device 10 according to the present embodiment. The exhaust purification device 10 includes a particulate filter 20 and a reduction catalyst 21 that are disposed in the exhaust passage 11 of the internal combustion engine 5. An oxidation catalyst 19 is disposed on the upstream side of the particulate filter 20, and a reducing agent injection valve 43 for supplying a urea aqueous solution as a reducing agent into the exhaust passage 11 is included on the upstream side of the reduction catalyst 21. A reducing agent supply device 40 is connected. Further, the exhaust purification device 10 includes a control device 60 for performing forced regeneration of the particulate filter 20 and operation control of the reducing agent supply device 40.

  Of these, the particulate filter 20 is a filter for collecting exhaust particulates in the exhaust gas. As the particulate filter 20, a known filter, for example, a honeycomb structured filter made of a ceramic material is used. In the exhaust purification apparatus 10 of the present embodiment, the particulate filter 20 is disposed on the upstream side of the reduction catalyst 21, and there is no possibility that exhaust particulates adhere to the reduction catalyst 21.

  The oxidation catalyst 19 disposed on the upstream side of the particulate filter 20 removes the unburned fuel supplied into the exhaust passage 11 by post injection or the like in the internal combustion engine 5 when the particulate filter 20 is forcibly regenerated. The exhaust gas passing through the particulate filter 20 is oxidized and used to heat the particulate filter 20 by raising the temperature. As the oxidation catalyst 19, a known catalyst, for example, a catalyst in which platinum is supported on alumina and a predetermined amount of a rare earth element such as cerium is added is used.

The reduction catalyst 21 adsorbs ammonia produced by hydrolysis of the urea aqueous solution injected into the exhaust gas by the reducing agent injection valve 43, and reduces NO _x in the inflowing exhaust gas. As this reduction catalyst 21, for example, a zeolite-based reduction catalyst having an ammonia adsorption function and capable of selectively reducing NO _x is used.
In the reduction catalyst 21 having the ammonia adsorption function, the saturated adsorption amount (adsorbable amount) of ammonia depends on the catalyst temperature. FIG. 2 shows the relationship between the temperature of the reduction catalyst 21 and the saturated adsorption amount of ammonia. The reduction catalyst 21 is saturated with ammonia as the catalyst temperature increases in the temperature range in which NO _x reduction and purification is actually performed. It has the characteristic that the amount decreases.

  Further, temperature sensors 26 and 27 are provided on the upstream side and the downstream side of the reduction catalyst 21, respectively. Sensor values of the temperature sensors 26 and 27 are sent to the control device 60, and the control device 60 detects the exhaust gas temperature at each position. The sensor values of the temperature sensors 26 and 27 are also used for estimating the temperature of the reduction catalyst 21.

  A first pressure sensor 28 is provided between the oxidation catalyst 19 and the particulate filter 20, and a second pressure sensor 29 is provided between the particulate filter 20 and the reduction catalyst 21. The sensor values of the first pressure sensor 28 and the second pressure sensor 29 are also sent to the control device 60, and the pressure in the exhaust passage 11 at each position is detected. The sensor values of the first pressure sensor 28 and the second pressure sensor 29 are used for estimating the amount of exhaust particulates accumulated in the particulate filter 20.

  Further, the reducing agent supply device 40 provided in the exhaust purification device 10 of the present embodiment includes a reducing agent injection valve 43 fixed to the exhaust passage 11 on the upstream side of the reducing catalyst 21, and a urea aqueous solution as a liquid reducing agent. Is stored in the storage tank 41, and a reducing agent pumping means 42 that pumps the urea aqueous solution in the storage tank 41 toward the reducing agent injection valve 43. A first supply passage 44 is connected between the reducing agent pressure feeding means 42 and the storage tank 41, and a second supply passage 45 is connected between the reducing agent pressure feeding means 42 and the reducing agent injection valve 43. Yes. The second supply passage 45 is provided with a reducing agent pressure sensor 30 used for driving control of the reducing agent pressure feeding means 42.

  In the exhaust purification device 10 of the present embodiment, an aqueous urea solution is used as a liquid reducing agent. The aqueous urea solution is mixed with the exhaust gas upstream of the reduction catalyst 21 and decomposes to generate ammonia. This ammonia is adsorbed on the reduction catalyst 21. However, the reducing agent that can be used is not limited to the urea aqueous solution, and any other reducing agent that can supply ammonia to the reduction catalyst 21 may be used.

As the reducing agent injection valve 43 of the reducing agent supply device 40, for example, a reducing agent injection valve whose opening / closing control is performed by energization control is used. The urea aqueous solution pumped from the reducing agent pumping means 42 to the reducing agent injection valve 43 is maintained at a predetermined pressure, and when the reducing agent injection valve 43 is opened by a control signal output from the control device 60, the urea aqueous solution is It is injected into the exhaust passage 11.
The reducing agent pumping means 42 typically uses an electric pump, and pumps the urea aqueous solution in the storage tank 41 and pumps it to the reducing agent injection valve 43. As this pump, for example, an electric diaphragm pump or a gear pump is used, and drive control is performed by the control device 60.

  The configuration of the reducing agent supply device 40 is not limited to the configuration in which the urea aqueous solution is directly injected into the exhaust passage 11 from the reducing agent injection valve 43 as described above. For example, the urea aqueous solution is atomized using high-pressure air. In addition, an air-assist type configuration that supplies air into the exhaust passage 11 may be used.

(2) Forced regeneration means The exhaust purification device 10 includes forced regeneration means for burning the exhaust particulates deposited on the particulate filter 20. In the exhaust purification device 10 of the present embodiment, the particulate filter 20 is forcibly regenerated by performing post injection in the internal combustion engine 5. Specifically, the unburned fuel contained in the exhaust gas is increased by the post injection, and the particulate filter 20 is heated by utilizing the oxidation heat generated when the unburned fuel is oxidized by the oxidation catalyst 19. Then, the exhaust particulate deposited on the particulate filter 20 burns. Therefore, in the exhaust purification device 10 of the present embodiment, the fuel injection valve provided in the internal combustion engine 5 and the control device 60 that controls the fuel injection valve correspond to the forced regeneration means.

  However, the forced regeneration means is not limited to the above example, and is not particularly limited as long as the temperature of the exhaust gas can be raised to about 500 to 600 ° C. For example, the forced regeneration means may be configured using an apparatus that supplies unburned fuel upstream of the oxidation catalyst 19 without relying on post injection. Further, the particulate filter 20 is directly heated by using a heating means such as a burner or a heating wire as the forced regeneration means, or the particulate filter 20 is indirectly heated through the exhaust gas. The exhaust particulate deposited on the filter 20 can also be burned.

(3) NO _X flow rate increasing means The exhaust purification device 10 is provided with NO _X flow rate increasing means for increasing the NO _X flow rate flowing into the reduction catalyst 21. To increase the NO _X flow rate flowing into the reduction catalyst 21, since it is effective to increase the concentration of NO _X in the exhaust gas discharged from the internal combustion engine 5, NO _X flow rate increasing means, typically Is constituted by a device and a control means that can easily cause lean combustion in the internal combustion engine 5.

In the exhaust purification device 10 of the present embodiment, an EGR (Exhaust Gas Recirculation) device is used as the NO _x flow rate increasing means. The EGR device includes an exhaust gas recirculation passage 17 connecting between an intake passage 12 connected to an intake manifold of the internal combustion engine 5 and an exhaust passage 11 connected to an exhaust manifold of the internal combustion engine 5, and the exhaust gas recirculation. The EGR valve 18 is provided in the circulation passage 17 to adjust the flow rate of the exhaust gas flowing through the exhaust gas recirculation passage 17. The EGR valve 18 is controlled to be opened and closed by a control device 60.

In the EGR device, in a state where the EGR valve 18 is closed, the entire amount of exhaust gas discharged from the internal combustion engine 5 flows through the exhaust passage 11 and proceeds downstream, while in a state where the EGR valve 18 is opened, A part of the exhaust gas discharged from the internal combustion engine 5 returns from the exhaust passage 11 to the intake passage 12. By closing the EGR valve 18, the ratio (EGR rate) of the recirculated exhaust gas amount to the intake air amount of the internal combustion engine 5 is reduced. At this time, the combustion state is improved by stopping the recirculation of the inert exhaust gas, and as a result, the NO _x concentration in the exhaust gas increases. That is, the exhaust gas purification apparatus 10 of the present embodiment increases the NO _x flow rate flowing into the reduction catalyst 21 by closing the EGR valve 18.

Various other methods for increasing the flow rate of NO _x flowing into the reduction catalyst 21 are conceivable. For example, NO in the exhaust gas can be increased by increasing the pressure in the common rail provided in the fuel injection device of the internal combustion engine to improve the fuel injection characteristics from the fuel injection valve or by advancing the injection timing. _X rate can be increased. In addition to the method of changing the adaptation of the fuel injection system in the internal combustion engine 5, the drive conditions of the internal combustion engine 5 are changed, or the setting conditions of auxiliary equipment provided in the intake system or the exhaust system of the internal combustion engine 5 are set. by or by varying the, it is possible to increase the concentration of NO _X in the exhaust gas.

Incidentally, as in the exhaust gas purifying apparatus 10 of the present embodiment, increasing the NO _X flow rate for whatever NO _X flow rate increasing means, be synonymous with to the amount of heat possessed by the supplied fuel is sufficiently generated in the internal combustion engine That is, it is possible to obtain the effect of improving the fuel efficiency of the internal combustion engine.

(4) Control Device FIG. 3 shows a configuration example in which the control device 60 provided in the exhaust purification device 10 is represented for each functional block. The control device 60 is configured around a known microcomputer, and includes a reducing agent supply device control unit (indicated as “DeNOX control” in FIG. 3) and an operating condition control unit (in FIG. 3, “DeNOX control”). Engine control ”), forced regeneration control unit (indicated as“ forced regeneration control ”in FIG. 3), ammonia slip prevention control unit (indicated as“ NH ₃ slip prevention control ”in FIG. 3), etc. It has as a main element. Specifically, each part of the control device 60 is realized by executing a program by a microcomputer (not shown).

(4) -1 Reductant Supply Device Control Unit The reductant supply device control unit includes a reductant pumping unit control unit (indicated as “pump control” in FIG. 3) that controls the driving of the reducing agent pumping unit 42, and a reduction. A reducing agent injection valve control unit (indicated as “inj control” in FIG. 3) that performs drive control of the agent injection valve 43, and an actual adsorption amount calculation unit (in FIG. 3) that calculates the actual adsorption amount Nact of ammonia in the reduction catalyst 21. And an injection amount calculation unit (indicated as “Qud calculation” in FIG. 3) for calculating the required injection amount of the urea aqueous solution.

The reducing agent pumping means controller performs feedback control of the reducing agent pumping means 42 based on the pressure Pud in the second supply path 45 detected by using the reducing agent pressure sensor 30, and The pressure is maintained at a predetermined value.
Further, the actual adsorption amount calculation unit integrates, for example, a value obtained by subtracting the amount of ammonia used for the reduction reaction of NO _x contained in the exhaust gas from the amount of ammonia generated by the urea aqueous solution injected last time. Thus, the actual adsorption amount Nact of ammonia in the reduction catalyst 21 is calculated.

The injection amount calculation unit is a temperature Tcat of the reduction catalyst 21 estimated from the flow rate Fnox of NO _x discharged from the internal combustion engine 5 and the sensor values of the temperature sensors 26 and 27 provided upstream and downstream of the reduction catalyst 21. The required injection amount Qud of the aqueous urea solution is calculated by adding the actual adsorption amount Nact of ammonia in the reduction catalyst 21 to the NO _x reduction efficiency η in the reduction catalyst 21.
Further, the reducing agent injection valve control unit performs opening / closing control of the reducing agent injection valve 43 based on the calculated required injection amount Qud of the urea aqueous solution.

(4) -2 Operation condition control unit of internal combustion engine The operation condition control unit of the internal combustion engine includes at least a fuel injection control unit (indicated as “fuel injection control” in FIG. 3) and an EGR control unit (in FIG. 3, “EGR control”). ")"). The fuel injection control unit calculates the required injection amount according to the rotational speed of the internal combustion engine 5, the accelerator operation amount, the pressure of the fuel supplied to the fuel injection valve, the load of the internal combustion engine 5, etc., and uses a predetermined injection pattern. The fuel injection valve is controlled to be opened and closed so that the fuel is injected into the cylinder of the internal combustion engine 5.
The EGR controller controls the operation of the EGR valve 18 and adjusts the flow rate of the exhaust gas recirculated from the exhaust passage 11 of the internal combustion engine 5 to the intake passage 12.

(4) -3 Forced regeneration control unit The forced regeneration control unit is a deposition amount calculation unit (denoted as “Vpm calculation” in FIG. 3) that estimates the accumulation amount SL of the exhaust particulates collected by the particulate filter 20. , A forced regeneration execution determination unit (indicated as “forced regeneration determination” in FIG. 3) for determining whether or not forced regeneration of the particulate filter is necessary, and a forced regeneration execution control unit (in FIG. 3, “forced regeneration determination”). Forcible regeneration execution ”).

Among these, in the control device 60 provided in the exhaust gas purification device 10 of the present embodiment, the accumulation amount calculation unit includes the sensor value of the first pressure sensor 28 provided before and after the particulate filter 20 and the second pressure. Based on the differential pressure obtained from the sensor value of the sensor 29, the accumulation amount Vpm of exhaust particulates is estimated.
However, various other methods can be adopted as the method for estimating the exhaust gas deposition amount Vpm. For example, based on parameters relating to operating conditions such as the rotational speed of the internal combustion engine 5, fuel injection amount, injection timing, etc., parameters relating to exhaust gas such as the flow rate of exhaust gas discharged from the internal combustion engine 5, exhaust pressure, exhaust temperature, etc. The accumulated amount Vpm of exhaust particulates can also be estimated by calculating and integrating the flow rate of exhaust particulates in the exhaust gas.

  The forced regeneration determination unit determines that the forced regeneration of the particulate filter 20 is necessary when the exhaust particulate deposition amount Vpm estimated by the deposition amount calculation unit exceeds a predetermined forced regeneration threshold value Vpm1. The forced regeneration threshold value Vpm1 is an amount of exhaust particulates that can cause a malfunction of the internal combustion engine 5 or the particulate filter 20 due to accumulation of exhaust particulates on the particulate filter 20 and cause a malfunction of the internal combustion engine 5 or the particulate filter 20 (limit accumulation amount). ) It is set to a value smaller than Vpm0. Since the forced regeneration threshold value Vpm1 is smaller than the limit deposition amount Vpm0, forced regeneration is performed before the exhaust particulates collected by the particulate filter 20 reach the limit deposition amount Vpm0.

The forced regeneration execution unit outputs a forced regeneration execution instruction signal when the forced regeneration determination unit determines that forced regeneration of the particulate filter 20 is necessary. In the control device 60 provided in the exhaust purification device 10 of the present embodiment, the forced regeneration execution unit instructs the fuel injection control unit of the operating condition control unit of the internal combustion engine 5 to perform post injection.
In addition, the forced regeneration execution unit outputs an instruction signal for stopping the post-injection triggered by the exhaust particulate accumulation amount Vpm in the particulate filter 20 estimated by the forced regeneration determination unit being reduced to a predetermined amount. With respect to the timing for terminating the forced regeneration, the time from the start of the forced regeneration execution may be measured, and the forced regeneration may be terminated when a predetermined time has elapsed.

(4) -4 Ammonia Slip Prevention Control Unit The ammonia slip prevention control unit is an ammonia slip determination unit (denoted as “slip determination” in FIG. 3) that determines whether ammonia slip can occur with forced regeneration. When it is determined that ammonia slip can occur with forced regeneration, a reducing agent supply stop instruction unit (indicated as “Ud supply stop” in FIG. 3) for stopping the supply of urea aqueous solution, and execution of forced regeneration When it is determined that ammonia slip may occur, a regeneration standby instruction unit (indicated as “regeneration standby instruction” in FIG. 3) that waits for execution of forced regeneration for a predetermined period, and a predetermined period that waits for forced regeneration A NO _x flow rate increase control unit (indicated as “NO _x increase control” in FIG. 3) for increasing the NO _x flow rate flowing into the reduction catalyst 21 is provided.

  The ammonia slip determination unit receives the actual adsorption amount Nact of the ammonia calculated by the actual adsorption amount calculation unit of the reducing agent supply device control unit, and whether the actual adsorption amount Nact of ammonia is equal to or greater than the saturated adsorption amount N1 during forced regeneration Determine whether or not. The saturated adsorption amount N1 during forced regeneration is a saturated adsorption amount corresponding to the temperature of the reduction catalyst 21 when forced regeneration of the particulate filter 20 is performed. As an example, saturation when the temperature of the reduction catalyst 21 is 500 ° C. The adsorption amount is set as the saturated adsorption amount N1 during forced regeneration. However, the saturated adsorption amount N1 during forced regeneration can be set to a variable value in consideration of conditions that affect the amount of heat released from the exhaust pipe or the reduction catalyst 21, such as the outside air temperature and the vehicle speed.

The ammonia slip determination unit detects the rotational speed of the internal combustion engine 5 and determines whether the actual ammonia adsorption amount Nact is equal to or greater than the saturated adsorption amount N1 during forced regeneration only when the rotational speed is equal to or less than a predetermined value. You may make it determine. Since the flow rate of the exhaust particulate discharged from the internal combustion engine 5 is relatively increased when the internal combustion engine 5 is idling at low speed or when there is a traffic jam, the exhaust particulate accumulation amount Vpm in the particulate filter 20 reaches the forced regeneration threshold value Vpm1. However, in other operating conditions, the flow rate of exhaust particulate discharged from the internal combustion engine 5 is relatively small and the exhaust particulate deposition amount Vpm in the particulate filter 20 is forced. It is easy to obtain a time margin from reaching the regeneration threshold Vpm1 to reaching the limit deposition amount Vpm0. Therefore, performs control to increase the NO _X flow rate only when the low rotational speed of the internal combustion engine 5, while so as to shorten the waiting time until the forced regeneration execution, when the rotational speed of the internal combustion engine 5 is larger than a predetermined value By stopping the supply of the urea aqueous solution and waiting for the decrease in the actual adsorption amount Nact of ammonia in the reduction catalyst 21, the number of times that the operating condition of the internal combustion engine 5 can be changed can be reduced.

  The reducing agent supply stop instruction unit is a reducing agent injection valve control unit of the reducing agent supply device control unit when the ammonia slip determination unit determines that the actual adsorption amount Nact of ammonia is equal to or greater than the saturated adsorption amount N1 during forced regeneration. In response to this, an instruction signal for temporarily stopping the injection of the urea aqueous solution is output. As a result, the actual adsorption amount Nact of ammonia in the reduction catalyst 21 does not increase.

Similar to the reducing agent supply stop instruction unit, the forced regeneration standby instruction unit is a forced regeneration execution unit when the ammonia slip determination unit determines that the actual adsorption amount Nact of ammonia is equal to or greater than the saturated adsorption amount N1 during forced regeneration. In response to this, an instruction signal for waiting for execution of forced regeneration of the particulate filter 20 is output. During this waiting period, the NO _X flow rate increase instruction unit to be described later, NO _X flow rate flowing into the reduction catalyst 21 is increased, control is performed to reduce the actual adsorption amount Nact of ammonia in the reduction catalyst 21. That is, in the exhaust purification device 10 of the present embodiment, the particulates depend on whether or not the actual adsorption amount Nact of ammonia calculated by the actual adsorption amount calculation unit of the reducing agent supply device control unit is equal to or greater than the saturated adsorption amount N1 during forced regeneration. The execution time of forced regeneration of the filter 20 is different.

  This forced regeneration standby instruction unit includes a standby time calculation unit (indicated as “twait calculation” in FIG. 3), and the amount Vpm of exhaust particulates accumulated in the particulate filter 20 is limited based on the operating state of the internal combustion engine 5. A waiting time tmax that is a time required to reach the deposition amount Vpm0 is estimated. In other words, the maximum time for which the particulate filter 20 can be kept waiting without executing the forced regeneration of the particulate filter 20 is calculated. Then, the forced regeneration standby instruction unit sets a standby time twait for actually waiting for forced regeneration based on the standby time tmax, measures the time with a timer, and waits for forced regeneration when the standby time twait has elapsed. Outputs a signal to cancel.

If the time for waiting for forced regeneration to be set in advance to prevent ammonia slip from the reduction catalyst 21 is set in advance, the possibility that the accumulated amount Vpm of the exhaust particulates in the particulate filter 20 exceeds the limit deposition amount Vpm0 during the standby is reduced. In addition, deterioration of the particulate filter 20 due to clogging of the particulate filter 20 and problems with the internal combustion engine 5 are prevented.
That is, when the forced regeneration of the particulate filter 20 is made to wait for the waiting time twait, exhaust particulates exceeding the forced regeneration threshold Vpm1 are deposited on the particulate filter 20, but the exhaust particulate accumulation amount Vpm is Since the waiting time twait is set to end before reaching the limit accumulation amount Vpm0, the particulate filter 20 is not clogged.

The forced regeneration standby instructing unit of the control device 60 of the present embodiment is discharged from the internal combustion engine 5 and the ratio Rpm (%: deposition rate) of the current exhaust particulate deposition amount Vpm to the limit deposition amount Vpm0 of the particulate filter 20. Based on the accumulation rate Spm (% / second) of the exhaust particulates on the particulate filter 20 calculated based on the NO _x flow rate, the standby possible period tmax is calculated. The waiting time twait for actually waiting for execution of forced regeneration of the particulate filter 20 is set as long as possible. As the waiting time twait is long, it is possible to suppress the noise can be lowered concentration of NO _X exhaust gas was increased by NO _X flow rate increasing means which will be described later, it occurs due to lean combustion.

The NO _X flow rate increase control unit outputs a signal for increasing the NO _X flow rate flowing into the reduction catalyst 21 when it is determined that forced regeneration of the particulate filter 20 is necessary. The NO _X flow rate increase control unit of the control device 60 of the present embodiment outputs an instruction signal to the EGR control unit of the operating condition control unit of the internal combustion engine 5 so as to reduce the opening degree of the EGR valve 18.

This NO _X flow rate increase control unit includes a target NO _X flow rate calculation unit (indicated as “tgtnox calculation” in FIG. 3), and the target NO _X flow rate calculation unit receives an actual ammonia adsorption amount Nact from the ammonia slip determination unit. And the saturated adsorption amount N1 during forced regeneration are received, and the NO _x amount Mnox necessary for consuming the difference amount of ammonia is calculated. Further, the target NO _X flow rate calculation section, the amount of NO _X Mnox required to consume the ammonia sets divided by latency twait to wait for execution of forced regeneration value as a target NO _X flow rate Tgtnox. Then, the NO _X flow rate increase control unit outputs an instruction signal to the EGR control unit so that the set target NO _X flow rate tgtnox is realized.

That, NO _X flow rate increasing control unit, the forced regeneration standby instruction section, by utilizing the period in which to wait for the execution of the forced regeneration, increasing the NO _X flow rate flowing into the reduction catalyst 21, adsorbed to the reduction catalyst 21 To reduce ammonia. Therefore, even when the temperature of the reduction catalyst 21 rises during the forced regeneration and the saturated adsorption amount N in the reduction catalyst 21 decreases, the downstream of the ammonia adsorbed on the reduction catalyst 21 is prevented. Is done.

Further, the NO _x flow rate increase control unit of the control device 60 of the present embodiment calculates the target NO _x flow rate tgtnox by dividing the NO _x amount Mnox necessary for consuming a predetermined amount of ammonia by the waiting time twait. without NO _X flow discharged from the internal combustion engine 5 increases rapidly, the noise level due to the lean combustion is suppressed.

2. Next, an example of a method for controlling the exhaust purification apparatus 10 performed by the control apparatus 60 of the exhaust purification apparatus 10 of the present embodiment shown in FIGS. 1 and 3 will be described with reference to time charts of FIGS. 4 and 5. This will be described in detail with reference to the flowcharts of FIGS. Among the time chart diagrams of FIGS. 4 and 5, FIG. 4 is a time chart diagram in a case where the ammonia slip determination unit determines that ammonia slip cannot occur with the forced regeneration of the particulate filter 20. Show. FIG. 5 is a time chart when the ammonia slip determination unit determines that ammonia slip can occur with the forced regeneration of the particulate filter 20.

  As shown in the flow of FIG. 6, first, during operation of the internal combustion engine, the sensor value Pu of the pressure sensor 28 provided on the upstream side of the particulate filter 20 in step S11 and the pressure sensor 29 provided on the downstream side. After the sensor value Pl is read, the exhaust particulate accumulation amount Vpm in the particulate filter 20 is calculated in step S12. Next, in step S13, the exhaust particulate deposition amount Vpm calculated in step S12 is compared with the forced regeneration threshold value Vpm1, and it is determined whether or not the exhaust particulate deposition amount Vpm is equal to or greater than the forced regeneration threshold value Vpm1.

  When the exhaust particulate deposition amount Vpm is equal to or greater than the forced regeneration threshold value Vpm1, the process proceeds to step S14. On the other hand, when the exhaust particulate deposition amount Vpm is less than the forced regeneration threshold value Vpm1, the process returns to step S11. The comparison between the exhaust particulate deposition amount Vpm and the forced regeneration threshold value Vpm1 is repeated until the deposition amount Vpm becomes equal to or greater than the forced regeneration threshold value Vpm1 (period from t0 to t1 in FIGS. 4 and 5).

  At the time t1 in FIGS. 4 and 5 when the exhaust particulate accumulation amount Vpm is equal to or greater than the forced regeneration threshold value Vpm1, first, in step S14, the actual ammonia adsorption amount Nact at the current reduction catalyst 21 is calculated. Next, in step S15, the actual adsorption amount Nact of ammonia calculated in step S14 is compared with the saturated adsorption amount N1 during forced regeneration, and whether the actual adsorption amount Nact of ammonia is equal to or greater than the saturated adsorption amount N1 during forced regeneration. It is determined whether or not.

  When the actual adsorption amount Nact of ammonia is equal to or greater than the saturated adsorption amount N1 during forced regeneration, this corresponds to the case of the time chart in FIG. In this case, the process proceeds to step S16, and the actual adsorption amount Nact of ammonia in the reduction catalyst 21 is less than the saturated adsorption amount N1 during forced regeneration within a time during which the forced regeneration of the particulate filter 20 can be kept waiting. Control is performed so as to be (period t1 to t2 in FIG. 5).

FIG. 7 is a flowchart showing details of the control in step S16. First, in step S31, a drive stop signal for the reducing agent injection valve 43 is output, and the reducing agent supply control by the reducing agent supply device 40 is stopped. Next, in step S32, the ratio Rpm (%) of the current exhaust particulate deposition amount Vpm to the exhaust particulate limit deposition amount Vpm0 in the particulate filter 20 is obtained and included in the exhaust gas exhausted from the internal combustion engine 5. NO deposition rate Spm exhaust particulates _X on the basis of the density to the particulate filter 20 (% / sec) is calculated. Further, in step S33, based on the ratio Rpm (%) of the current exhaust particle deposition amount Vpm to the exhaust particulate limit deposition amount Vpm0 and the exhaust particulate deposition rate Spm (% / second), the particulate filter 20 The waiting time tmax for forced regeneration is calculated, and the waiting time twait is set.

Next, in step S34, based on the difference between the actual adsorption amount Nact of ammonia, which is the amount of ammonia to be consumed, and the saturated adsorption amount N1 during forced regeneration, the NO _x amount Mnox required to consume the ammonia amount is calculated. After the calculation, in step S35, the target NO _X flow rate tgtnox discharged from the internal combustion engine 5 is calculated by further dividing the NO _X amount Mnox by the standby time twait set in step S33. Then, the timer is activated in step S36, in step S37, the instruction signal to narrow the EGR valve 18 is output to the EGR control unit, NO _X flow rate increases discharged from the internal combustion engine 5. Steps S31 to S37 so far are performed at time t1 in FIG.

Thereafter, it is determined whether or not the timer has passed the waiting time twait in step S38 until the timer has passed the waiting time twait. Execution of forced regeneration is maintained in a standby state until the timer elapses the standby time twait. During this period (period t1 to t2 in FIG. 5), the urea aqueous solution supply control is stopped and the internal combustion engine is stopped. The NO _x flow rate discharged from the engine 5 is increased.
The criterion for determining that the actual adsorption amount Nact of ammonia in the reduction catalyst 21 has decreased to the saturated adsorption amount N1 during forced regeneration is exhausted from the internal combustion engine 5 in addition to the count of the elapse of the waiting time twait by the timer. It can also be determined by estimating the consumption of ammonia based on the NO _x flow rate.

If it is determined in step S38 that the timer has passed the standby time (time t2 in FIG. 5), the process proceeds to step S39, where an instruction signal is output to the EGR control unit to open the EGR valve 18, and the internal combustion engine 5 The increase control of the NO _x flow rate discharged from the engine ends. When the increase control of the NO _x flow rate is finished, the process proceeds to step S17 in FIG.

  On the other hand, if it is determined in step S15 described above that the actual adsorption amount Nact of ammonia is less than the saturated adsorption amount N1 during forced regeneration, this corresponds to the case of the time chart in FIG. In this case, since there is no fear of ammonia slip accompanying the execution of forced regeneration, the process proceeds to step S17 as it is, and forced regeneration of the particulate filter 20 is promptly performed at time t1 in FIG.

In step S17, an instruction signal for performing post injection is output to the fuel injection control unit, and forced regeneration of the particulate filter 20 is executed. Thus, in the control device 60 of the exhaust purification apparatus 10 of the present embodiment, when the actual adsorption amount Nact of ammonia is determined to be equal to or greater than the saturated adsorption amount N1 during forced regeneration, the ammonia adsorbed on the reduction catalyst 21 is reduced. Part of the particulate filter 20 is immediately consumed after a part of the particulate filter 20 is consumed during the waiting time tmax for forced regeneration, and when the actual adsorption amount Nact of ammonia is determined to be less than the saturated adsorption amount N1 during forced regeneration. Forced regeneration is executed.
When the forced regeneration of the particulate filter 20 is executed in step S17, it is then determined in step S18 whether the urea aqueous solution supply control is stopped. In the case of FIG. 4, since the urea aqueous solution supply control is not stopped, the process proceeds to step S20 as it is. In the case of FIG. 5, since the urea aqueous solution supply control is stopped, in step S19, the reducing agent injection valve control unit On the other hand, a restart permission signal for the urea aqueous solution supply control is output, and after the supply of the urea aqueous solution is restarted, the process proceeds to step S20.

  Thereafter, until the forced regeneration of the particulate filter 20 is completed (the period from t1 to t4 in FIG. 4 and the period from t2 to t3 in FIG. 5), in step S20, the forced regeneration of the particulate filter 20 is performed. It is determined whether or not it has been completed. Completion of the forced regeneration can be determined by elapse of a predetermined time, or can be determined by estimating the amount of exhaust particulate reduction in the particulate filter 20. Then, at the time t4 in FIG. 4 and t3 in FIG. 5 when the forced regeneration is completed, the process proceeds to step S21, the post-injection end instruction signal is output to the fuel injection control unit, and the forced regeneration control is stopped. The routine ends.

Incidentally, only the rotational speed is low idling and congestion or the like of the internal combustion engine 5, to perform control for increasing the NO _X flow rate discharged from the internal combustion engine 5, for example, as shown in FIG. 8, after the step S15 A step S25 for comparing the rotational speed Ne of the internal combustion engine 5 with a predetermined threshold value Ne0 is provided. Rotation speed Ne of the internal combustion engine 5 is at the threshold Ne0 following increasing control of the NO _X flow proceeds to step S16 are performed. On the other hand, when the rotational speed Ne of the internal combustion engine 5 exceeds the threshold value Ne0, the process proceeds to step S26, and after the supply of the urea aqueous solution is stopped, the reduction catalyst based on the NO _x flow rate discharged from the internal combustion engine 5 in step S27. It is determined whether the ammonia consumption amount Nact adsorbed on 21 has decreased to less than the saturated adsorption amount N1 during forced regeneration. When the actual adsorption amount Nact of ammonia becomes less than the saturated adsorption amount N1 during forced regeneration, the process proceeds to step S17, where forced regeneration of the particulate filter 20 is executed.

By implementing the control method of the exhaust purification apparatus of the present embodiment described above, the actual adsorption amount Nact of ammonia in the reduction catalyst 21 is reduced when there is a risk of ammonia slip accompanying the forced regeneration of the particulate filter 20. Therefore, the failure due to the clogging of the particulate filter 20 and the malfunction to the internal combustion engine 5 are prevented. In addition, it is possible to obtain an effect of improving fuel efficiency by performing lean combustion of the internal combustion engine 5 in order to increase the NO _x flow rate.

1 is a diagram illustrating an overall configuration of an exhaust gas purification apparatus for an internal combustion engine according to an embodiment of the present invention. It is a figure for demonstrating the relationship between the saturated adsorption amount of ammonia, and the temperature of a reduction catalyst. It is a block diagram which shows the structural example of the control apparatus of the exhaust gas purification apparatus concerning embodiment of this invention. It is a time chart which shows an example of the control method of the exhaust gas purification device concerning embodiment of this invention. It is a time chart which shows an example of the control method of the exhaust gas purification device concerning embodiment of this invention. It is a flowchart which shows an example of the control method of the exhaust gas purification apparatus concerning embodiment of this invention. It is a flow diagram illustrating an example of increasing control of the NO _X flow rate. It is a flowchart which shows another example of the control method of an exhaust gas purification apparatus.

Explanation of symbols

5: internal combustion engine, 10: exhaust purification device, 11: exhaust passage, 12: intake passage, 17: exhaust gas recirculation passage, 18: EGR valve, 19: oxidation catalyst, 20: particulate filter, 21: reduction catalyst, 26:27: temperature sensor, 28: first pressure sensor, 29: second pressure sensor, 30: reducing agent pressure sensor, 40: reducing agent supply device, 41: storage tank, 42: reducing agent pumping means, 43 : Reducing agent injection valve, 44: first supply passage, 45: second supply passage, 60: control device

Claims (8)

An exhaust emission control device comprising: a particulate filter that collects exhaust particulates in exhaust gas discharged from an internal combustion engine; and a reduction catalyst that selectively purifies NO _x in the exhaust gas using a reducing agent. In the control device of the exhaust gas purification device for controlling,
A forced regeneration execution determination unit that determines whether or not forced regeneration of the particulate filter is necessary;
A forced regeneration execution control unit for performing the forced regeneration;
An ammonia slip estimator that determines whether or not ammonia slip can occur with the execution of the forced regeneration;
A reducing agent supply stop instruction unit for stopping the supply of the reducing agent when it is determined that ammonia slip may occur with the execution of the forced regeneration;
A regeneration standby instruction unit that waits for a predetermined period of execution of the forced regeneration when it is determined that ammonia slip may occur with the execution of the forced regeneration;
A NO _x flow rate increase control unit for controlling the operating conditions of the internal combustion engine within the predetermined period to increase the NO _x flow rate flowing into the reduction catalyst;
A control device for an exhaust gas purification device.   The regeneration standby instruction unit sets the predetermined period up to a time when it is estimated that the accumulated amount of the exhaust particulates collected by the particulate filter reaches the limit accumulation amount of the particulate filter. The exhaust emission control device control apparatus according to claim 1.   The control of the exhaust gas purification apparatus according to claim 1 or 2, wherein the regeneration standby instruction unit sets the predetermined period based on a deposition rate or a deposition rate of the exhaust particulates deposited on the particulate filter. apparatus. The NO _X flow rate increase control unit calculates a target NO _X amount to flow into the reduction catalyst when it is determined that the ammonia slip can occur, and increases the NO _X flow rate according to the target NO _X amount. The control device of the exhaust emission control device according to any one of claims 1 to 3, wherein the control device is an exhaust purification device. When it is determined that the ammonia slip can occur, the NO _x flow rate increase control unit gradually reaches the target NO _x amount over the predetermined period when the integrated amount of the NO _x flowing into the reduction catalyst is determined. The control device of the exhaust emission control device according to claim 4, wherein the NO _x flow rate is increased as described above. An exhaust emission control device comprising: a particulate filter that collects exhaust particulates in exhaust gas discharged from an internal combustion engine; and a reduction catalyst that selectively purifies NO _x in the exhaust gas using a reducing agent. In the control method,
Before performing forced regeneration of the particulate filter, determine whether ammonia slip can occur with the forced regeneration,
When it is determined that the ammonia slip may occur, the supply of the reducing agent is stopped and the forced regeneration is waited for a predetermined period, and the operating condition of the internal combustion engine is controlled to flow into the reduction catalyst. by increasing the NO _X flow rate, after reducing the amount of adsorption of the ammonia in the reduction catalyst, the control method of the exhaust gas purification apparatus characterized by performing the forced regeneration. Increasing the NO _X flow rate, after reducing the amount of adsorption of the ammonia in the reduction catalyst, a control to execute the forced regeneration, the rotational speed of the internal combustion engine and characterized in that when more than a predetermined value A method for controlling an exhaust emission control device according to claim 6. A particulate filter that collects exhaust particulates in the exhaust gas discharged from the internal combustion engine, and a reduction that is provided on the exhaust downstream side of the particulate filter and reduces and purifies NO _x in the exhaust gas using ammonia as a reducing agent In an exhaust gas purification device for an internal combustion engine comprising a catalyst,
A forced regeneration means for forcibly regenerating the particulate filter by raising the temperature of the particulate filter, and a NO _x flow rate increasing means for increasing the NO _x flow rate flowing into the reduction catalyst,
A forced regeneration execution determination unit that determines whether or not forced regeneration of the particulate filter is necessary, a forced regeneration execution control unit that executes the forced regeneration, and whether or not ammonia slip can occur with the execution of the forced regeneration. An ammonia slip estimator for determining, a reducing agent supply stop instruction unit for stopping supply of the reducing agent when it is determined that ammonia slip may occur with the execution of the forced regeneration, and execution of the forced regeneration. When it is determined that ammonia slip may occur, a regeneration standby instruction unit that waits for a predetermined period of time to execute the forced regeneration, and an operating condition of the internal combustion engine within the predetermined period of time to control the reduction catalyst. An exhaust purification apparatus for an internal combustion engine, comprising: a control device including an NO _x flow rate increase control unit that increases an inflow NO _x flow rate.

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