JP2019019793A - SCR system - Google Patents

Abstract

To provide an SCR system capable of improving NOx elimination performance after a rise of an SCR catalyst temperature.SOLUTION: An SCR system 50 includes: an upstream side SCR catalyst 51 and a downstream side SCR catalyst 52; an urea water supply system 54 having an upstream side urea water supply section 55 and a downstream side urea water supply section 56; and a control device 10 having a control section 11 for controlling the urea water supply system. The control section executes engine start time control processing for starting urea water supply from the upstream side urea water supply section and the downstream side urea water supply section and making urea water supply quantity of the downstream side urea water supply section larger than that of the upstream side urea water supply section when a temperature of each of the upstream side SCR catalyst and the downstream side SCR catalyst becomes higher than a preset predetermined temperature at start of an engine.SELECTED DRAWING: Figure 2

Description

  The present invention relates to an SCR system.

Conventionally, an SCR system having an SCR (Selective Catalytic Reduction) catalyst is known (see, for example, Patent Document 1 and Patent Document 2). In such an SCR system, when the temperature of the SCR catalyst rises and the temperature of the SCR catalyst becomes high, NOx in exhaust discharged from the engine using ammonia generated by hydrolysis of urea water. NOx can be purified by reducing. Further, when the temperature of the SCR catalyst is low, such as immediately after starting the engine, ammonium nitrate (NH ₄ NO ₃₎ produced by the reaction of ammonia produced by hydrolysis of urea water and NOx in the exhaust gas. ) Is adsorbed by the SCR catalyst, and the release of NOx into the atmosphere can be suppressed.

International Publication No. 2014/073408 JP 2011-202620 A

  However, in the conventional SCR system, the NOx purification performance after the SCR catalyst temperature rises cannot be said to be sufficiently high.

  The present invention has been made in view of the above, and an object thereof is to provide an SCR system capable of improving the NOx purification performance after the SCR catalyst temperature rises.

  To achieve the above object, an SCR system according to the present invention includes an upstream SCR catalyst disposed in an exhaust passage of an engine, and a downstream SCR catalyst disposed in the exhaust passage downstream of the upstream SCR catalyst. An upstream urea water supply unit that supplies urea water to the exhaust passage upstream of the upstream SCR catalyst, and a downstream side of the upstream SCR catalyst and an upstream side of the downstream SCR catalyst. A urea water supply system having a downstream urea water supply unit for supplying urea water to the exhaust passage, and a control device having a control unit for controlling the urea water supply system, the control unit comprising: When the temperature of the upstream SCR catalyst and the downstream SCR catalyst becomes higher than a predetermined temperature set in advance, the upstream urea water supply unit and the downstream urine are A start-up control process for starting the urea water supply from the water supply unit and increasing the urea water supply amount of the downstream urea water supply unit more than the urea water supply amount of the upstream urea water supply unit is executed. .

NOx in the exhaust gas first flows into the upstream SCR catalyst out of the upstream SCR catalyst and the downstream SCR catalyst, and at least a part thereof reacts with the ammonia remaining in the upstream SCR catalyst to become ammonium nitrate. The amount of NOx flowing into the downstream SCR catalyst is smaller than the amount of NOx flowing into the upstream SCR catalyst. For this reason, the downstream SCR catalyst produces less ammonium nitrate and the ammonium nitrate adsorbs less than the upstream SCR catalyst. Therefore, the downstream SCR catalyst has higher NOx purification performance when the temperature of the upstream SCR catalyst and the downstream SCR catalyst becomes higher than the predetermined temperature after the engine is started. In this regard, according to the present invention, when the temperature of the upstream side SCR catalyst and the downstream side SCR catalyst becomes higher than a predetermined temperature at the time of starting the engine, the engine start time control process is executed, and the downstream urea water The urea water supply amount of the supply unit is set larger than the urea water supply amount of the upstream urea water supply unit. As a result, a large amount of urea water can be supplied to the downstream SCR catalyst having a high NOx purification performance, so that the NOx purification performance after the SCR catalyst temperature rises can be improved.

It is a schematic diagram showing typically the whole composition of the engine system concerning an embodiment. It is a flowchart which shows an example of control of the SCR system at the time of engine starting.

  FIG. 1 is a schematic diagram schematically showing an overall configuration of an engine system 1 according to the present embodiment. The engine system 1 is mounted on a vehicle. Although the specific kind of vehicle is not specifically limited, In this embodiment, commercial vehicles, such as a bus and a truck, are used as an example. The engine system 1 includes an engine 2, an intake passage 3 through which intake air taken into the engine 2 passes, and an exhaust passage 4 through which exhaust exhausted from the engine 2 passes. Although the kind of engine 2 is not specifically limited, In this embodiment, the diesel engine is used as an example.

  The engine system 1 also includes a control device 10, an EGR system (EGR passage 20, EGR valve 21 and EGR cooler 22), an oxidation catalyst 30, a filter 40, and an SCR system 50. The control device 10 according to the present embodiment is a control device that controls the engine system 1 in an integrated manner, and is also a control device of the SCR system 50 (that is, part of the components of the SCR system 50).

  The control device 10 includes a microcomputer having a CPU 11 that executes various control processes and the like, and a storage unit 12 that stores various information, programs, and the like used for the operation of the CPU 11. As the storage unit 12, for example, a ROM, a RAM, or the like can be used. The control device 10 controls the urea water supply system 54 of the SCR system 50, which will be described later, and also integrates the engine system 1 by controlling the fuel injection timing, the fuel injection amount, the operation of the EGR valve 21 and the like of the engine 2. To control.

  The EGR passage 20 is a passage for introducing a part of the exhaust gas from the exhaust passage 4 into the intake passage 3. In the present embodiment, the EGR passage 20 branches from the exhaust manifold portion of the exhaust passage 4 and branches to the intake manifold of the intake passage 3. It joins the part. The exhaust gas passing through the EGR passage 20 is referred to as EGR gas. The EGR valve 21 and the EGR cooler 22 are arranged in the middle of the EGR passage 20. The EGR valve 21 is opened and closed in response to an instruction from the control device 10 to adjust the flow rate of the EGR gas. The EGR cooler 22 is a heat exchanger that cools the EGR gas by exchanging heat with the refrigerant.

The oxidation catalyst 30 is disposed at a predetermined location downstream of the exhaust manifold in the exhaust passage 4. The filter 40 is disposed in the exhaust passage 4 on the downstream side of the oxidation catalyst 30 and collects PM in the exhaust. The oxidation catalyst 30 has a configuration in which a noble metal catalyst such as platinum (Pt) or palladium (Pd) is supported on a filter through which exhaust gas can pass. The oxidation catalyst 30 promotes an oxidation reaction that changes nitrogen monoxide (NO) in the exhaust gas to nitrogen dioxide (NO ₂ ) by the oxidation catalytic action of the noble metal catalyst. When the exhaust temperature becomes a predetermined temperature or higher, the PM collected by the filter 40 can be burned by the nitrogen dioxide generated in the oxidation catalyst 30 and discharged as carbon dioxide (CO ₂ ).

The SCR system 50 includes an upstream SCR catalyst 51, a downstream SCR catalyst 52, an ammonia slip catalyst 53, and a urea water supply system 54. The upstream SCR catalyst 51 is disposed in the exhaust passage 4 on the downstream side of the filter 40. The downstream SCR catalyst 52 is disposed in the exhaust passage 4 on the downstream side of the upstream SCR catalyst 51. The upstream SCR catalyst 51 and the downstream SCR catalyst 52 are catalysts that selectively reduce NOx in the exhaust gas using ammonia (NH ₃ ) generated by hydrolysis of urea water. The specific kind of this catalyst is not specifically limited, For example, well-known SCR catalysts, such as vanadium, molybdenum, tungsten, a zeolite, can be used.

  The ammonia slip catalyst 53 is disposed in the exhaust passage 4 on the downstream side of the downstream SCR catalyst 52. The ammonia slip catalyst 53 is an oxidation catalyst that oxidizes ammonia that has passed through the downstream SCR catalyst 52.

  The urea water supply system 54 is a system that supplies urea water to the exhaust passage 4. Specifically, the urea water supply system 54 includes an upstream urea water supply unit 55 that supplies urea water to the exhaust gas in the exhaust passage 4 upstream from the upstream SCR catalyst 51 and downstream from the filter 40, and an upstream side. A downstream urea water supply unit 56 that supplies urea water to the exhaust gas in the exhaust passage 4 downstream from the SCR catalyst 51 and upstream from the downstream SCR catalyst 52. As an example of the upstream urea water supply unit 55 and the downstream urea water supply unit 56, a urea water injection valve that injects urea water in response to an instruction from the control device 10 is used in the present embodiment.

  In the following description, the upstream SCR catalyst 51 and the downstream SCR catalyst 52 are collectively referred to as “SCR catalyst”, and the upstream urea water supply unit 55 and the downstream urea water supply unit 56 are collectively referred to as “ This is referred to as a “urea water supply unit”.

  When urea water is injected from the urea water supply unit after the SCR catalyst reaches the catalyst activation temperature or higher, urea in the injected urea water is hydrolyzed, and as a result, ammonia is generated. This ammonia reduces NOx under the catalytic action of the SCR catalyst. As a result, nitrogen and water are generated. In this way, the SCR system 50 reduces NOx in the exhaust (that is, purifies NOx). Further, according to the present embodiment, since the ammonia slip catalyst 53 is provided, the ammonia is effectively suppressed from being discharged outside the engine system 1.

  The SCR system 50 may include a member in which the upstream SCR catalyst 51 and the filter 40 are integrated (that is, a filter with an SCR catalyst) instead of the upstream SCR catalyst 51 and the filter 40. In this case, the upstream-side urea water supply unit 55 is connected to the exhaust passage 4 upstream of the filter with SCR catalyst, more specifically, the exhaust gas upstream of the filter with SCR catalyst and downstream of the oxidation catalyst 30. It is only necessary to inject urea water into the passage 4.

  Further, the engine system 1 includes, as sensors for detecting various types of information, a NOx sensor 60 that detects the concentration of NOx in the exhaust, a temperature sensor 61a that detects the temperature of the upstream SCR catalyst 51, and a downstream SCR catalyst. The temperature sensor 61b which detects the temperature of 52 is provided. The detection results of these sensors are transmitted to the control device 10.

Next, details of the control of the control device 10 will be described. First, when the temperature of the upstream SCR catalyst 51 and the downstream SCR catalyst 52 becomes higher than a predetermined temperature set in advance when the engine 2 is started, the control device 10 While the urea water supply from the downstream urea water supply unit 56 is started, the urea water supply amount (mm ³ / min) of the downstream urea water supply unit 56 is changed to the urea water supply amount (mm) of the upstream urea water supply unit 55. ³ / min) is executed. This control process is referred to as “engine start time control process”.

  Further, the control device 10 sets the urea water supply amount of the upstream urea water supply unit 55 to the downstream urea water supply unit 56 after the completion of the engine start time control process (that is, during normal operation of the engine). A control process for increasing the amount of urea water supplied is executed. This control process is referred to as “normal control process”.

  FIG. 2 is a flowchart showing an example of the control of the SCR system 50 when the engine 2 is started. Specifically, it shows an example of a series of control processes including an engine start time control process. Note that each step of FIG. 2 is specifically executed by the CPU 11 of the control device 10. Further, the control device 10 starts execution of the flowchart of FIG. 2 simultaneously with the start of the engine 2.

  In step S10, the control device 10 determines the amount of ammonia adsorbed on the SCR catalyst when the engine 2 is started (in this embodiment, the start switch of the engine 2 is used as an example). An adsorption amount (ammonia adsorption amount (A1)) is acquired.

  As an example of this step S10, the control device 10 according to the present embodiment adsorbs to the upstream SCR catalyst 51 and the downstream SCR catalyst 52 based on the state of the SCR system 50 when the engine 2 was stopped last time. The ammonia adsorption amount is estimated, and the estimated ammonia adsorption amount is acquired as the ammonia adsorption amount (A1) in step S10. Note that the technique for obtaining the ammonia adsorption amount according to step S10 itself can be applied with a known technique (for example, the method for calculating the ammonia adsorption amount described in Patent Document 1, etc.), and thus a more detailed description is omitted. To do.

Next, the control device 10 determines whether or not the temperature of the SCR catalyst (SCR catalyst temperature: T _SCR ) is higher than a predetermined temperature (T1) set in advance (step S20). In the present embodiment, the catalytic activation temperature of the SCR catalyst is used as an example of the predetermined temperature (T1). The predetermined temperature (T1) is stored in advance in the storage unit 12 (that is, set in the control device 10).

  In addition, when acquiring the SCR catalyst temperature in step S20, the control device 10 according to the present embodiment specifically includes the temperature of the upstream SCR catalyst 51 detected by the temperature sensor 61a and the downstream side detected by the temperature sensor 61b. The temperature of the SCR catalyst 52 is acquired. And the control apparatus 10 determines whether the temperature of the upstream SCR catalyst 51 acquired in this way and the temperature of the downstream SCR catalyst 52 are both higher than predetermined temperature (T1).

  Step S20 is repeatedly executed until it is determined as YES. When it determines with YES by step S20, the control apparatus 10 acquires the production amount (ammonium nitrate production amount (A2)) of the ammonium nitrate produced | generated by the SCR catalyst after the start-up of the engine 2 (step S30).

As an example of this step S30, the control device 10 according to the present embodiment calculates the ammonium nitrate production amounts respectively generated in the upstream SCR catalyst 51 and the downstream SCR catalyst 52 based on the engine operating state after the start of the engine 2. The estimated ammonium nitrate production amount is acquired as the ammonium nitrate production amount (A2) in step S30. In addition, since the well-known technique (For example, the estimation method of the ammonium nitrate production amount etc. which are described in patent document 1 etc.) can be applied to the estimation method of the ammonium nitrate production amount which concerns on this step S30, more detailed description is more than this. Is omitted.

  Here, ammonium nitrate has a property of being generated when the SCR catalyst temperature is equal to or lower than the catalyst activation temperature of the SCR catalyst. For this reason, the amount of ammonium nitrate generated after the start of the engine 2 (specifically, the start of the start of the engine 2) is executed by executing step S30 when it is determined YES in step S20 as in the present embodiment. Thereafter, the amount of ammonium nitrate produced until the SCR catalyst temperature becomes higher than the catalyst activation temperature can be obtained with high accuracy.

  After step S30, the control device 10 subtracts the ammonium nitrate production amount (A2) acquired in step S30 from the ammonia adsorption amount (A1) acquired in step S10, so that the upstream side SCR catalyst 51 and the downstream side at the present time are subtracted. The amount of ammonia adsorbed on the SCR catalyst 52 (currently adsorbed ammonia amount (A3)) is acquired (step S40).

Next, the control device 10 starts executing the engine start time control process (step S50). In this engine start time control process, the control device 10 starts supply of urea water from the upstream urea water supply unit 55 and the downstream urea water supply unit 56. In addition, when the control device 10 supplies urea water from the upstream urea water supply unit 55 and the downstream urea water supply unit 56, the control device 10 sets the urea water supply amount (mm ³ / min) of the downstream urea water supply unit 56. More than the urea water supply amount (mm ³ / min) of the upstream urea water supply unit 55 is controlled.

  That is, when the temperature of the SCR catalyst becomes higher than a predetermined temperature set in advance at the time of starting the engine 2 (when YES in step S20), the control device 10 causes the urea in the downstream urea water supply unit 56 to In the urea water supply mode in which the water supply amount (injection amount of urea water) is greater than the urea water supply amount (urea water injection amount) of the upstream urea water supply unit 55, the upstream urea water supply unit 55 and The urea water supply from the downstream urea water supply unit 56 is started.

  Note that the control device 10 uses, for example, a method in which the valve opening time per unit time of the downstream urea water supply unit 56 is made longer than the valve opening time per unit time of the upstream urea water supply unit 55. The urea water supply amount of the side urea water supply unit 56 is made larger than the urea water supply amount of the upstream side urea water supply unit 55.

  As described above, the urea water supply amount of the downstream urea water supply unit 56 is larger than the urea water supply amount of the upstream urea water supply unit 55, so that the ammonia amount actually supplied to the downstream SCR catalyst 52 is upstream. The amount of ammonia actually supplied to the side SCR catalyst 51 becomes larger.

  In step S50, the control device 10 according to the present embodiment acquires the ratio of the urea water supply amount of the downstream urea water supply unit 56 and the urea water supply amount of the upstream urea water supply unit 55 in step S40. It is determined based on the current amount of adsorbed ammonia (A3).

Specifically, the control device 10 increases the urea water supply amount (X ₁ ) of the downstream urea water supply unit 56 as the current amount of adsorbed ammonia (A3) increases (that is, the NOx purification performance by the SCR catalyst increases). Is relatively decreased, and the urea water supply amount (X ₂ ) of the upstream urea water supply unit 55 is relatively increased. As a result, as the total value of the current amount of adsorbed ammonia of the upstream SCR catalyst 51 and the amount of current adsorbed ammonia of the downstream SCR catalyst 52 increases, the upstream side of the urea water supply amount (X ₁ ) of the downstream urea water supply unit 56 increases. The ratio (X ₂ / X ₁ ) of the urea water supply amount (X ₂ ) of the urea water supply unit 55 is large (however, even in this case, the downstream supply amount is larger than the upstream supply amount). Will not change).

  After step S50, the control device 10 determines whether or not ammonium nitrate produced by the SCR catalyst has been decomposed by heat (step S60). Specifically, the control device 10 determines whether or not the ammonium nitrate production amount (A2) obtained in Step S30 has been decomposed by heat.

  More specifically, in the control device 10 according to the present embodiment, when the elapsed time (Tp) from the start of execution of step S50 is longer than the reference time (Td), ammonium nitrate is decomposed (YES). Is determined. The reference time (Td) may be set in advance as an appropriate constant or may be calculated (in this case, Td becomes a variable). An example of a method for calculating the reference time (Td) is as follows.

  First, the control device 10 acquires the temperature of the SCR catalyst and the exhaust flow rate flowing into the SCR catalyst, and calculates the decomposition rate of ammonium nitrate from these values using a predetermined arithmetic expression. And the control apparatus 10 calculates the decomposition time of ammonium nitrate by dividing the ammonium nitrate production amount (A2) by the decomposition rate of this ammonium nitrate. The control device 10 may use the decomposition time calculated in this way as the reference time (Td).

  The control device 10 preferably determines whether or not ammonium nitrate has been decomposed for each of the upstream SCR catalyst 51 and the downstream SCR catalyst 52. In fact, the control device 10 according to the present embodiment does this way. ing. Step S60 is repeatedly executed until it is determined as YES.

  When it determines with YES by step S60, the control apparatus 10 complete | finishes execution of the engine start time control process, and performs the normal time control process mentioned above (step S70). That is, the control device 10 according to the present embodiment continues to execute the engine start-up control process until the ammonium nitrate generated by the upstream SCR catalyst 51 and the downstream SCR catalyst 52 is decomposed. In this normal control process, the control device 10 makes the urea water supply amount of the upstream urea water supply unit 55 larger than the urea water supply amount of the downstream urea water supply unit 56. Next, the control device 10 ends the execution of the flowchart.

  In the present embodiment, the CPU 11 of the control device 10 that executes the engine start time control process and the normal time control process corresponds to a member having a function as a “control unit” according to the present invention. CPU11 of the control apparatus 10 which performs step S10 is corresponded to the member which has a function as an "ammonia adsorption amount acquisition part" which concerns on this invention. CPU11 of the control apparatus 10 which performs step S30 is corresponded to the member which has a function as "ammonium nitrate production amount acquisition part" which concerns on this invention. CPU11 of the control apparatus 10 which performs step S40 is corresponded to the member which has a function as the "currently-adsorbed ammonia amount acquisition part" which concerns on this invention.

  Then, the effect of the SCR system 50 concerning this embodiment is demonstrated. First, NOx in the exhaust first flows into the upstream SCR catalyst 51 out of the upstream SCR catalyst 51 and the downstream SCR catalyst 52, and at least a part thereof reacts with ammonia remaining in the upstream SCR catalyst 51. Therefore, the amount of NOx flowing into the downstream SCR catalyst 52 is smaller than the amount of NOx flowing into the upstream SCR catalyst 51. For this reason, the downstream SCR catalyst 52 produces less ammonium nitrate and the ammonium nitrate adsorbs less than the upstream SCR catalyst 51.

Here, when ammonium nitrate is adsorbed on the surface of the SCR catalyst, the SCR catalyst cannot sufficiently exhibit its catalytic action, and as a result, the NOx purification performance due to the catalytic action decreases. Therefore, the downstream SCR catalyst 52 having a smaller amount of adsorption of ammonium nitrate is more suitable for the upstream SC.
The NOx purification performance at the time when the temperature of the SCR catalyst becomes higher than the predetermined temperature (T1) is higher than that of the R catalyst 51.

  In this regard, according to the present embodiment, when the temperature of the SCR catalyst becomes higher than the predetermined temperature (T1) at the time of engine start (in the case of YES at step S20), the engine start-time control process according to step S50. And the urea water supply amount of the downstream urea water supply unit 56 is made larger than the urea water supply amount of the upstream urea water supply unit 55, so that the downstream SCR catalyst 52 with high NOx purification performance is A lot of urea water can be supplied. Thereby, the NOx purification performance after the SCR catalyst temperature rises can be improved.

  Further, according to the present embodiment, the ratio of the urea water supply amount of the downstream urea water supply unit 56 and the urea water supply amount of the upstream urea water supply unit 55 in the engine start time control process is based on the current adsorbed ammonia amount. Therefore, the NOx purification performance after the SCR catalyst temperature rises can be improved more effectively.

  Further, according to the present embodiment, the normal time control process is executed after the completion of the engine start time control process, and in this normal time control process, the urea water supply amount of the upstream urea water supply unit 55 is set. The amount of urea water supplied from the downstream urea water supply unit 56 is set larger. According to this configuration, it is possible to purify NOx by using the SCR catalyst in which ammonium nitrate is decomposed by the execution of the engine start time control process and the NOx purification performance is restored. Further, since a large amount of urea water is supplied to the upstream SCR catalyst 51 having a large inflow of NOx, the NOx purification performance after the SCR catalyst temperature rises can be effectively improved.

  Although the preferred embodiments of the present invention have been described above, the present invention is not limited to such specific embodiments, and various modifications and changes can be made within the scope of the gist of the present invention described in the claims. Is possible.

DESCRIPTION OF SYMBOLS 1 Engine system 2 Engine 3 Intake passage 4 Exhaust passage 10 Controller 11 CPU
12 Storage Unit 50 SCR System 51 Upstream SCR Catalyst 52 Downstream SCR Catalyst 54 Urea Water Supply System 55 Upstream Urea Water Supply Unit 56 Downstream Urea Water Supply Unit 60 NOx Sensors 61a and 61b Temperature Sensor

Claims (4)

An upstream SCR catalyst disposed in the exhaust passage of the engine, and a downstream SCR catalyst disposed in the exhaust passage downstream of the upstream SCR catalyst;
An upstream urea water supply unit for supplying urea water to the exhaust passage upstream of the upstream SCR catalyst, and the exhaust gas downstream of the upstream SCR catalyst and upstream of the downstream SCR catalyst A urea water supply system having a downstream urea water supply unit for supplying urea water to the passage;
A control device having a control unit for controlling the urea water supply system,
When the temperature of the upstream SCR catalyst and the downstream SCR catalyst becomes higher than a preset predetermined temperature at the time of starting the engine, the controller is configured to supply the upstream urea water supply unit and the downstream side. The engine start-time control process is executed to start the urea water supply from the urea water supply unit, and to make the urea water supply amount of the downstream urea water supply unit larger than the urea water supply amount of the upstream urea water supply unit SCR system. The control device includes:
An ammonia adsorption amount acquisition unit that acquires an adsorption amount of ammonia adsorbed on the upstream SCR catalyst and the downstream SCR catalyst when the engine is started;
An ammonium nitrate production amount obtaining unit for obtaining the production amount of ammonium nitrate produced by the upstream SCR catalyst and the downstream SCR catalyst after the start of the engine;
By subtracting the ammonium nitrate production amount acquired by the ammonium nitrate production amount acquisition unit from the ammonia adsorption amount acquired by the ammonia adsorption amount acquisition unit, the upstream SCR catalyst and the downstream SCR catalyst at the present time The SCR system according to claim 1, further comprising: a presently-adsorbed ammonia amount obtaining unit that obtains a presently-adsorbed ammonia amount that is an amount of ammonia adsorbed on the substrate.   In the engine start-up control process, the control unit determines a ratio between the urea water supply amount of the downstream urea water supply unit and the urea water supply amount of the upstream urea water supply unit based on the current adsorbed ammonia amount. The SCR system according to claim 2, wherein the SCR system is determined.   The control unit performs normal time control in which the urea water supply amount of the upstream urea water supply unit is larger than the urea water supply amount of the downstream urea water supply unit after the execution of the engine start time control process is completed. The SCR system according to claim 3, wherein the process is executed.

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