JP4637775B2 - Control device for engine with selective reduction type NOx catalyst - Google Patents

Description

  The present invention relates to an engine equipped with a selective reduction type NOx catalyst, and more particularly to an engine control device that purifies NOx in exhaust gas by controlling both the engine side and the catalyst side.

Fuel for an automobile engine, particularly a diesel engine, is injected into compressed air taken into a cylinder. Since this fuel burns by self-ignition, there is a concern about the generation of NOx (nitrogen oxide). Thus, a technique for depriving O ₂ (oxygen) from this NOx and reducing it to N ₂ (nitrogen) is known.
One example of this type of technology is to use a selective reduction type NOx catalyst (SCR catalyst) that selectively reduces NOx in exhaust gas with urea. Specifically, when urea water (urea water) is added to the exhaust gas, urea changes to NH ₃ (ammonia). In the SCR catalyst, NH ₃ and NOx in the exhaust gas are combined and decomposed into water and N ₂ to purify NOx (see, for example, Patent Document 1).
JP-T-2002-512336

By the way, the NOx generation amount discharged from the engine depends on the fuel injection amount and the like, and the above-mentioned urea water addition amount is adjusted according to this NOx generation amount. These urea water addition amount and fuel injection The amount is set so that the total operating cost of each unit price of urea water and fuel is optimal.
However, it must be noted that the unit prices of these urea water and fuel are assumed prices. That is, each unit price of urea water and fuel is a fixed value input at the time of engine development or engine manufacture, and when each actual unit price after the engine is mounted varies from the above estimated unit price. This is because, even if NOx purification can be achieved, it is no longer difficult to achieve optimal operating costs.

  The present invention has been made in view of such a problem, and an object of the present invention is to provide a control device for an engine with a selective reduction type NOx catalyst capable of achieving both NOx purification and optimizing operating costs.

  In order to achieve the above object, the control device for an engine with a selective reduction type NOx catalyst according to claim 1 is provided in an exhaust system of the engine and purifies NOx in exhaust gas by adding a reducing agent. And a controller that performs fuel injection timing control and reducing agent addition amount control on the engine, and the controller is configured to be able to input each unit price of the fuel and the reducing agent at any time, and is executed according to the input unit price. Control on the catalyst side or fuel injection to change the amount of reducing agent added so that the operating cost based on the actual value is lower than the operating cost based on the set value. Determine the share of the control on either side of the engine-side control that changes the timing and promote the NOx purification to complement the control of the other It is characterized by determining the.

In the invention according to claim 2, the controller performs control on the catalyst side to reduce the amount of addition of the reducing agent when the unit price of the reducing agent of the execution value exceeds the unit price of the reducing agent of the set value. While determining the sharing, it is characterized in that the execution of the control on the engine side that retards the fuel injection timing by the decrease in the NOx purification amount due to the decrease in the addition amount of the reducing agent is characterized.
According to the third aspect of the present invention, the controller performs the sharing of the control on the engine side to advance the fuel injection timing when the unit price of the fuel of the execution value exceeds the unit price of the fuel of the set value. On the other hand, it is characterized in that the share of the control on the catalyst side in which the amount of addition of the reducing agent is increased by the amount of increase in the amount of NOx produced by advancing the fuel injection timing is characterized.

  Furthermore, in the invention described in claim 4, the set value is set to a control amount that satisfies the minimum value of the operating cost at a predetermined price of the reducing agent and fuel, and the controller executes the execution value based on the unit price of the reducing agent that is input as needed. The main share of the reducing agent that determines the sharing of the engine-side control and the catalyst-side control based on the comparison results of the reducing agent-side unit price comparing means for comparing the set value and the reducing agent-side unit price comparing means. The engine-side control and the catalyst-side control are determined based on the result of comparison by the determination means, the fuel-side unit price comparison means for comparing the execution value according to the unit price of the fuel input as needed and the set value, and the fuel-side unit price comparison means. It is characterized by comprising an assignment determination means mainly using fuel for determining the execution share.

  In the invention according to claim 5, the controller adds the respective execution shares by the sharing determination means mainly including the reducing agent and the sharing determination means mainly including the fuel, and controls the engine side control and the catalyst side control. It is characterized by having a final assignment determination means for determining the final execution assignment.

  Therefore, according to the control device for the engine with the selective reduction type NOx catalyst according to the first aspect of the present invention, the controller can execute the fuel unit price and the execution value based on the unit price of the reducing agent, and the preset unit price of the fuel. And a setting value based on the unit price of the reducing agent, and the execution sharing of the control on the engine side for changing the fuel injection timing and the control on the catalyst side for changing the addition amount of the reducing agent is determined. Specifically, in accordance with the input unit price fluctuation, one of the controls is performed so that the operation cost based on the execution value is lower than the operation cost based on the set value, and at the same time, the other one is related to NOx purification. The other control is performed to complement the control. As a result, it is possible to achieve both purification of NOx and optimization of the overall operation cost composed of the fuel and the reducing agent.

According to the second aspect of the present invention, when the unit price of the reducing agent as the effective value is high, the amount of the reducing agent added is decreased, and an increase in operating cost due to the use of this reducing agent is surely prevented. On the other hand, at this time, the fuel injection timing is retarded to compensate for the reduction of the reducing agent, so that NOx purification is reliably maintained.
Furthermore, according to the third aspect of the present invention, when the unit price of the fuel of the execution value is high, the fuel injection timing is advanced, and an increase in operating cost due to maintaining the injection timing is reliably prevented. On the other hand, at this time, the addition amount of the reducing agent is increased, and the increase in the NOx generation amount due to the advance of the injection timing is complemented, so that NOx purification is reliably maintained.

Furthermore, according to the invention described in claim 4, any of the sharing determination means on the reducing agent side and the fuel side is controlled on the engine side so as to reduce the operating cost based on the execution value rather than the minimum operating cost based on the set value. Since the control on the catalyst side is shared and implemented, the overall operation cost can be optimized.
According to the fifth aspect of the present invention, the final assignment determination means includes engine-side control and catalyst-side control assignment by the reducing agent-side assignment determination means, and engine-side assignment by the fuel-side assignment determination means. Since the final execution share is determined by adding the control share and the control share on the catalyst side, it is possible to cope with any fluctuations in the unit price of the reducing agent and fuel.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 shows an engine control apparatus according to an embodiment, and the engine 2 is a common rail type diesel engine. The engine 2 is provided with fuel injectors 4, 4... For each cylinder, and each injector 4 is connected to a common rail 8 through a fuel passage 6.

  The engine 2 has an engine intake system including an intake pipe 12 connected to the intake manifold and an engine exhaust system including an exhaust pipe 14 connected to the exhaust manifold. A compressor 17 of the supercharger 16, an intercooler 20, and an intake throttle valve 22 are sequentially disposed at appropriate positions of the intake pipe 12. The opening degree of the intake throttle valve 22 is variably adjusted by an actuator 24 that operates under the control of an ECU (controller) 10 installed in the passenger compartment.

On the other hand, a turbine 18 of the supercharger 16, an exhaust brake valve 26, an exhaust gas aftertreatment device 30, and a muffler (not shown) are sequentially disposed at appropriate positions of the exhaust pipe 14. The opening degree of the exhaust brake valve 26 is variably adjusted by an actuator 28 that operates under the control of the ECU 10.
The compressor 17 and the turbine 18 of the supercharger 16 are coupled to each other by a coupling shaft (not shown) so as to be able to rotate synchronously, and the rotational force of the turbine 18 is generated by the flow of exhaust gas discharged from each cylinder of the engine 2. The compressor 17 is rotated by the rotational force 18 to pressurize the intake air, and the intake air is supplied to the engine 2. Further, the pressurized intake air is cooled by the intercooler 20, and the density of the intake air is increased to improve the charging efficiency, and the engine output is increased.

  Further, the engine intake system and the engine exhaust system are connected by an EGR passage 32, and a part of the exhaust gas is supplied to the engine 2 as a recirculation gas through the EGR passage 32. At an appropriate position of the EGR passage 32, there is provided an EGR cooler 34 that cools the recirculation gas to increase the gas filling density in each cylinder, and an EGR valve 36 that shuts off the supply and supply of the recirculation gas into each cylinder. It has been. The opening degree of the EGR valve 36 is variably adjusted by an actuator 38 that operates under the control of the ECU 10.

Here, the exhaust gas aftertreatment device 30 purifies NOx contained in the exhaust gas. Specifically, the exhaust gas aftertreatment device 30 of the present embodiment includes a pre-stage oxidation catalyst 40 and a selective reduction type NOx catalyst (hereinafter referred to as an SCR catalyst) 42 arranged on the downstream side thereof. The SCR catalyst 42 selectively reduces NOx in the exhaust gas using urea. More specifically, urea water (urea water) as an example of a reducing agent is stored in a urea water tank 46, and is supplied from this tank 46 to the urea water addition device 44. In this urea water addition device 44, urea water and air from the air tank 48 are mixed and supplied to the urea water injector 50 in accordance with a command from the ECU 10. The injector 50 has an opening on the upstream side of the SCR catalyst 42, and urea water is appropriately added to the exhaust gas. As a result, the urea changes to NH ₃ , and the NH ₃ and NOx in the exhaust gas are combined in the SCR catalyst 42 to be decomposed into water and N ₂ to purify NOx.

The temperature of the SCR catalyst 42 is detected by the temperature sensor 52, and the amount of urea water added can be adjusted according to this temperature. Further, an oxidation catalyst may be disposed on the downstream side of the SCR catalyst 42 to decompose excess NH _{3 due} to excessive addition of urea water.
The ECU 10 includes an input / output device (not shown), a storage device (ROM, RAM, BURAM, etc.) used for storing control programs and control maps, a central processing unit (CPU), a timer counter, and the like. . Various sensors that detect the states of the engine 2 and the SCR catalyst 42 are electrically connected to the input side of the ECU 10. On the other hand, various actuators such as the above-described fuel injector 4 and urea water addition device 44 are electrically connected to the output side of the ECU 10.

  The ECU 10 of the present embodiment is configured so that the unit prices of fuel (light oil) and urea water can be input as needed, and the fuel injection timing control for the engine 2 according to the input of each unit price of fuel and urea water. And the amount of urea water added to the SCR catalyst 42 are controlled. More specifically, the unit price of urea water and fuel is input to the ECU 10 not only when the engine 2 is developed or manufactured but also after the engine 2 is mounted on the vehicle. For example, a maintenance company of a sales company, a driver at the time of replenishing urea water or fuel, and the like can adjust the above-mentioned unit prices by adjusting a panel such as a passenger compartment.

Then, as shown in FIG. 2, the ECU 10 includes a unit price comparison unit 54 and a sharing determination unit 56 mainly using urea water, a unit price comparison unit 57 and a sharing determination unit 59 mainly using fuel, and a final sharing determination unit 60. And an engine-side control unit 62 and a catalyst-side control unit 64.
In the unit price comparison unit 54, the execution value based on the unit price of urea water newly input as described above is compared with the set value based on the unit price set in advance. This set value is a reference control amount that satisfies the minimum value of the total operating cost based on the predetermined price of the urea water at the time of development or manufacture of the engine 2 and the predetermined price of the initial fuel, and more specifically. For example, the fuel injection timing is the standard injection timing where the retard amount and advance amount are zero, and the urea water addition amount is about 2-5% of the fuel. The amount is applicable. These reference injection timing and reference addition amount are both stored in the storage device. Then, the unit price comparison unit 54 outputs the comparison result between the execution value and the set value to the sharing determination unit 56.

In the assignment determination unit 56, control for the engine 2 and control for the SCR catalyst 42 are performed in accordance with the comparison result in order to achieve both NOx purification mainly using urea water and optimization of the total operation cost combining urea water and fuel. The execution sharing seen from the urea water side with the control is determined, and the determination result is output to the final sharing determination unit 60.
On the other hand, the unit price comparison unit 57 compares the execution value based on the current unit price of fuel newly input as described above with the set value. Then, the unit price comparison unit 57 outputs the comparison result between the execution value and the set value to the sharing determination unit 59. In addition, the assignment determination unit 59 controls the engine 2 and the SCR catalyst 42 according to the comparison result in order to achieve both NOx purification mainly using fuel and optimization of the total operation cost combining urea water and fuel. The execution share seen from the fuel side with respect to the control with respect to is determined, and the decision result is output to the final share decision unit 60.

  Then, the final assignment determination unit 60 adds the respective execution assignments. More specifically, the execution sharing seen from the urea water side determined by the sharing determination unit 56 and the execution sharing seen from the fuel side determined by the sharing determination unit 59 are added together to control the engine 2 and to the SCR catalyst 42. The final execution sharing with the control is determined and output to the engine side control unit 62 and the catalyst side control unit 64, respectively.

  Next, the engine-side control unit 62 selects a map of the fuel injection timing stored in the storage device, controls the valve opening timing of the injector 4, and sets the fuel injection timing from the limit value of the retard amount to the advance amount. Adjust within the limits of. At the same time, the catalyst side control unit 64 selects a map of the addition amount stored in the storage device, and controls the valve opening timing of the injector 50 via the urea water addition device 44 to adjust the addition amount of urea water. To do.

Next, a specific operation of the ECU 10 will be described.
First, when the unit price of urea water is newly input by the maintenance company or driver of the sales company, the unit price comparison unit 54 compares the unit price of this urea water with the original unit price of urea water.
Here, for example, when the unit price of this urea water is higher than the original unit price, in order to always make it cheaper than the operating cost by the set value (indicated by a dotted line in FIG. 3), It is necessary to reduce the amount of urea water added. Therefore, the sharing determination unit 56 determines a decrease amount (execution value) of the urea water addition amount. More specifically, in the sharing determination unit 56 in this case, the addition amount on the reduction side with respect to the reference addition amount is read from the map, and as shown in FIG. 3B, the urea water addition amount (solid line in the figure). ) Is less than the hypothetical addition amount (indicated by the alternate long and short dash line in the figure) when the unit price after the change is executed. As a result, the amount of NOx purification by the SCR catalyst 42 is reduced due to the decrease in the reaction amount as shown in FIG.

  On the other hand, in this state, it is difficult to purify NOx, and there is a concern that the amount of NOx on the downstream side of the SCR catalyst 42 increases. Therefore, the sharing determination unit 56 determines an increase (execution value) of the retard amount of the fuel injection timing. This execution value is set to a value that complements the decrease in the NOx purification amount by the SCR catalyst 42 accompanying the decrease in the amount of urea water added. In other words, as shown in FIG. 6A, in the sharing determination unit 56 in this case, the retarded fuel injection timing (indicated by the solid line in the figure) corresponding to the increase in unit price of urea water is obtained from the map. It is read out, and this injection timing is made later than the virtual injection timing (indicated by the alternate long and short dash line in the figure) when it is executed with the changed unit price. Then, the combustion temperature in the cylinder decreases, and the amount of NOx generated from the cylinder of the engine 2 as shown in FIG. 5A, in other words, the amount of NOx generated upstream of the SCR catalyst 42 is small. Become. As a result, the control of the fuel injection timing and the control of the addition amount are combined, and the NOx amount on the downstream side of the SCR catalyst 42 is maintained without increasing as shown by the solid line in FIG. The

  In this way, when the unit price of this urea water is higher than the initial unit, the amount of urea water is reduced from the hypothetical amount of addition, so as shown in FIG. The cost required for this is significantly lower than in the case of the hypothetical addition amount (indicated by the alternate long and short dash line in the figure). On the other hand, in this case, since the fuel injection timing is made later than the virtual injection timing, as shown in FIG. 5A, when the fuel consumption increases and the cost required for the fuel is the virtual injection timing (FIG. It is slightly higher than (indicated by a one-dot chain line). However, since the cost required for urea water is low, the total operating cost of fuel and urea water is assumed to be the case when it is executed with the unit price after fluctuation as shown by the solid line in FIG. It can be seen that it can be kept lower than the virtual total cost (indicated by the alternate long and short dash line in the figure).

  In addition, when the unit price of this urea water becomes cheaper than the initial unit, the sharing determination unit 56 makes the fuel injection timing earlier than the virtual injection timing as shown in FIG. As shown in the figure (b), the increase amount (running value) of the urea water addition amount is determined. This execution value is set to a value that complements the increase in the NOx generation amount existing on the upstream side of the SCR catalyst 42 with the increase in the advance amount of the fuel injection timing and the decrease in the output of the engine 2. As a result of the increase in the amount of NOx purification by the SCR catalyst 42, the NOx amount on the downstream side of the SCR catalyst 42 is maintained without increasing as shown by the solid line in FIG. In addition, the total operating cost of fuel and urea water is lower than the virtual total cost (indicated by the alternate long and short dash line in the figure) due to the sum of the small fuel consumption and the increased but inexpensive amount of urea water. It can be kept low.

On the other hand, when the unit price of fuel is newly input by the maintenance company or driver of the sales company, the unit price comparison unit 57 compares the unit price of the current fuel with the unit price of the initial fuel.
Here, for example, in the case where the unit price of the current fuel is higher than the initial unit, in order to always reduce the operation cost according to the set value (indicated by a dotted line in FIG. 4), In order to achieve this, the fuel injection timing is advanced so as to improve fuel efficiency. Therefore, the share determination unit 59 determines the advance angle (execution value) of the fuel injection timing. More specifically, the sharing determination unit 59 in this case reads the injection timing that is more advanced than the reference injection timing from the map, and as shown in FIG. 4A, the fuel injection timing (solid line in the figure). ) Is made earlier than the virtual injection timing (shown by the alternate long and short dash line in the figure) when the unit price after the change is executed. As a result, the fuel consumption is reduced as shown in FIG.

  On the other hand, in this state, NOx is likely to be generated, and there is a concern that the amount of NOx on the downstream side of the SCR catalyst 42 increases. Therefore, the sharing determination unit 59 determines an increase (execution value) of the urea water addition amount. This execution value is set to a value that complements the increase in the NOx generation amount accompanying the increase in the advance amount of the injection timing. That is, as shown in FIG. 5B, the sharing determination unit 59 in this case reads the urea water addition amount (indicated by the solid line in the figure) corresponding to the increase in the unit price of the fuel from the map. This addition amount is set to be larger than the hypothetical addition amount (indicated by the alternate long and short dash line in the figure) when it is executed with the unit price after fluctuation. Then, the reaction amount increases, and the NOx purification amount by the SCR catalyst 42 increases as shown in FIG. As a result, the control of the fuel injection timing and the control of the addition amount are combined, and the NOx amount on the downstream side of the SCR catalyst 42 is maintained without increasing as shown by the solid line in FIG. The

  As described above, when the unit price of the fuel becomes higher than the initial cost, the fuel injection timing is made earlier than the virtual injection timing. Therefore, as shown in FIG. Is significantly lower than in the case of the virtual injection timing (indicated by the alternate long and short dash line in the figure). On the other hand, in this case, since the amount of urea water added is made larger than the hypothetical added amount, the cost required for urea water is the hypothetical added amount as shown in FIG. It is slightly higher than However, since the cost required for the fuel is low, the total operating cost of the fuel and urea water is hypothetical when it is executed at the unit price after the fluctuation as shown by the solid line in FIG. It can be seen that the total cost (indicated by the alternate long and short dash line in the figure) can be kept low.

  In addition, when the unit price of the fuel this time is lower than the initial unit, the sharing determination unit 59 reduces the amount of urea water added to the hypothetical amount added as shown in FIG. As shown in FIG. 5A, an increase amount (execution value) of the retard amount of the injection timing is determined. This execution value is set to a value that complements the decrease in the NOx purification amount by the SCR catalyst 42 accompanying the decrease in the amount of urea water added. As a result of the reduction in the amount of NOx generated on the upstream side of the SCR catalyst 42, the NOx amount on the downstream side of the SCR catalyst 42 is maintained without increasing as shown by the solid line in FIG. . In addition, the total operating cost of fuel and urea water increases compared to the virtual total cost (indicated by the alternate long and short dash line in the figure) due to the sum of the fuel consumption that is high but low and the amount of urea water that is low. It can be kept low.

Subsequently, in the final assignment determination unit 60, the execution assignment seen from the urea water side determined by the assignment determination part 56 and the execution assignment seen from the fuel side determined by the assignment determination part 59 are added together to control the engine 2 And the final execution sharing of the control for the SCR catalyst 42 are determined and output to the engine side control unit 62 and the catalyst side control unit 64.
As described above, the present invention mainly focuses on the point that each unit price of urea water and fuel can be input as appropriate, and focuses on reducing expensive urea water or fuel in each unit price.

  And according to the engine control apparatus of this embodiment mentioned above, in ECU10, the unit price comparison parts 54 and 57 input the unit price of the urea water and the execution value by the unit price of the fuel inputted at any time, and the unit price of urea water set beforehand. And the set values according to the unit price of the fuel, respectively, and the sharing determination units 56 and 59 share the execution of the control on the engine side that changes the fuel injection timing and the control on the catalyst side that changes the amount of urea water added. Each is decided.

In this regard, according to the prior art, even when the price of urea water or fuel fluctuates, each of the execution shares between the engine-side control and the catalyst-side control are determined with the above set values. It will end up.
On the other hand, according to the change in unit price of urea water and fuel input this time, the sharing determination units 56 and 59 of this embodiment firstly, the operation cost based on the execution value is lower than the operation cost based on the set value. Thus, the control amount of any one of the catalyst side control unit 64 and the engine side control unit 62 is determined. Next, the control amount related to the promotion of NOx purification of the other control is determined so as to complement one control performed for suppressing the operation cost. Therefore, it is possible to achieve both NOx purification and optimization of the overall operation cost made of fuel and urea water.

Further, since the sharing determination unit 56 decreases the amount of urea water added when the unit price of urea water input this time is high, an increase in operating cost due to the use of urea water is reliably prevented. On the other hand, at this time, the retard amount of the fuel injection timing is increased to compensate for the decrease in urea water, so that NOx purification is reliably maintained.
Furthermore, since the sharing determination unit 56 increases the advance amount of the fuel injection timing when the unit price of urea water input this time is reduced, an increase in operating cost due to the use of this fuel is prevented. On the other hand, since the amount of urea water added is increased at this time to compensate for the increase in the advance amount of the injection timing, NOx purification is reliably maintained also in this case.

Furthermore, since the assignment determination unit 59 increases the advance amount of the fuel injection timing when the unit price of the fuel input this time is higher, the operating cost associated with maintaining the injection timing is surely increased. To be prevented. On the other hand, at this time, the amount of urea water added is increased to compensate for the increase in the advance amount of the injection timing, so that NOx purification is reliably maintained.
Moreover, since the sharing determination unit 59 decreases the amount of urea water added when the unit price of the fuel input this time is reduced, an increase in operating cost due to the use of this urea water is prevented. On the other hand, at this time, the retard amount of the fuel injection timing is increased to compensate for this decrease in urea water, so that NOx purification is reliably maintained in this case as well.

Further, since the assignment determination units 56 and 59 share and execute the engine side control and the catalyst side control so as to always reduce the operation cost based on the execution value rather than the minimum operation cost based on the set value, the total operation cost is determined. Can be optimized.
Furthermore, the final assignment determination unit 60 performs the assignment of the engine side control and the catalyst side control determined by the assignment determination unit 56 and the execution assignment of the engine side control and the catalyst side control determined by the assignment determination unit 59. In addition, the final implementation share is determined. Therefore, it is possible to cope with any fluctuations in unit prices of urea water and fuel. More specifically, when the unit price of both urea water and fuel fluctuates, and when the unit price of urea water fluctuates but the unit price of fuel does not fluctuate, the unit price of urea water does not fluctuate but the unit price of fuel Can be accommodated for various combinations of price fluctuations, such as when the unit price of both urea water and fuel has not changed.

The description of one embodiment of the present invention is finished above, but the present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the spirit of the present invention.
For example, when the unit price of urea water input this time is given as an example, first, the amount of retarded fuel injection timing is increased to reduce the amount of NOx produced, and then the amount of urea water added is reduced. It may be possible to prevent the operating cost from being increased by using urea water by reducing it. Also in this case, as described above, there is an effect that it is possible to achieve both purification of NOx and optimization of operation costs.

Further, the unit price comparison units 54 and 57 may compare an execution value and a set value based on a ratio of unit prices of urea water and fuel. Further, the set value described above is not limited to the initial unit price at the time of engine development or manufacturing, but also applies to a unit price before the current time (for example, the previous unit price) input after the engine is installed. .
Furthermore, the controller of the present invention may be divided into an engine ECU that controls the engine side that can determine the execution share and a catalyst ECU that controls the catalyst side that can determine the execution share. Furthermore, the present invention may omit a supercharger, an exhaust brake valve, and the like.

It is the schematic which shows the control apparatus of the engine with a selective reduction type NOx catalyst by one Embodiment of this invention. It is a block diagram of NOx purification control which ECU of FIG. 1 implements. It is a figure regarding NOx purification control and operation cost optimization control which mainly used urea water by ECU of FIG. 1, and is a figure explaining the effect | action of this invention. It is a figure regarding NOx purification control and operation cost optimization control mainly using light oil by the ECU of FIG. 1, and is a diagram for explaining the operation of the present invention.

Explanation of symbols

2 Engine 10 ECU (controller)
42 SCR catalyst (selective reduction NOx catalyst)
54 Unit price comparison unit (unit price comparison means on the reducing agent side)
56 sharing determination part (sharing determination means mainly using reducing agent)
57 Unit price comparison unit (unit price comparison means on the fuel side)
59 Sharing determination section (sharing determination means mainly using fuel)
60 Final assignment determination section (Final assignment determination means)
62 Engine side control unit 64 Catalyst side control unit

Claims (5)

A selective reduction type NOx catalyst that is provided in an exhaust system of an engine and purifies NOx in exhaust gas by adding a reducing agent;
A controller for performing fuel injection timing control for the engine and addition amount control of the reducing agent;
The controller is configured such that each unit price of the fuel and the reducing agent can be input at any time, and compares an execution value based on the input unit price with a set value based on a preset unit price, and calculates an operating cost based on the execution value. Implementation sharing of either control of the catalyst side for changing the amount of addition of the reducing agent or control of the engine side for changing the fuel injection timing in order to reduce the operation cost according to the set value. A control device for an engine with a selective reduction type NOx catalyst, wherein the control share of the other control is determined in order to determine and promote NOx purification to complement the one control.   When the unit price of the reducing agent of the effective value exceeds the unit price of the reducing agent of the set value, the controller determines an execution share of the control on the catalyst side that reduces the amount of addition of the reducing agent, 2. The selective reduction type NOx catalyst according to claim 1, wherein execution of control on the engine side that retards the fuel injection timing by an amount corresponding to a decrease in the NOx purification amount due to a decrease in the amount of addition of the reducing agent is determined. Engine control unit.   When the unit price of the fuel of the effective value exceeds the unit price of the fuel of the set value, the controller determines an execution share of control on the engine side that advances the fuel injection timing, 2. The selective reduction according to claim 1, wherein an execution share of the control on the catalyst side in which the amount of addition of the reducing agent is increased by the amount of increase in the amount of NOx produced by advancing the injection timing of the catalyst is determined. Type NOx catalyst control device. The set value is set to a control amount that satisfies the minimum value of the operating cost at a predetermined price of the reducing agent and the fuel,
The controller is
The reducing agent side unit price comparing means for comparing the execution value according to the unit price of the reducing agent inputted as needed and the set value, and the engine side control and the catalyst side based on the comparison result by the reducing agent side unit price comparing means. A sharing determination means mainly comprising a reducing agent that determines the execution sharing with the control of
The fuel-side unit price comparison means for comparing the execution value according to the unit price of the fuel input as needed and the set value, and the engine-side control and the catalyst-side control based on the comparison result by the fuel-side unit price comparison means The control apparatus for an engine with a selective reduction type NOx catalyst according to claim 1, further comprising: an assignment determination unit mainly including a fuel for determining an execution share of the engine.   The controller adds the respective execution shares by the sharing determination means mainly using the reducing agent and the sharing determination means mainly using the fuel, and determines the final execution sharing between the control on the engine side and the control on the catalyst side. The control apparatus for an engine with a selective reduction type NOx catalyst according to claim 4, further comprising a final assignment determination unit that performs the determination.

Images