JP2010156312A - Control device for internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a control device for internal combustion engines which decreases NOx of the internal combustion engines (engine), and can maintain excellent fuel efficiency. <P>SOLUTION: The controller 1 controls the engine 100 in which the emulsion fuel is used. The controller 1 has an EGR device and ECU17 that controls the EGR rate in the EGR device. When the fuel efficiency in the base state of the engine that runs only by the base fuel is set as acceptable fuel efficiency, and when the emulsion fuel is used, the EGR rate is increased within the range where the fuel efficiency is not deteriorated beyond this acceptable fuel efficiency by the ECU17. As a result, NOx of the engine 100 is decreased, and superior fuel efficiency can be maintained. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a control device for an internal combustion engine.

  Conventionally, exhaust gas recirculation devices (EGR devices) or emulsion fuels have been used with the aim of reducing nitrogen carbide (NOx) emitted by internal combustion engines. Emulsion fuels have been used and equipped with EGR devices. An internal combustion engine has also been proposed (see Patent Document 1).

Japanese Patent Laid-Open No. 5-231247

  By the way, when the EGR device is used and the introduction amount of the EGR amount is increased, the NOx amount can be reduced, but the fuel consumption may be deteriorated. On the other hand, improvement of fuel consumption is expected by using emulsion fuel.

  Therefore, an object of the present invention is to provide a control device for an internal combustion engine that can reduce NOx of the internal combustion engine and maintain good fuel efficiency.

  In order to solve this problem, an internal combustion engine control device disclosed in the present specification is a control device for an internal combustion engine using emulsion fuel, and includes an exhaust gas recirculation means and an exhaust gas recirculation means in the exhaust gas recirculation means. A circulation rate control means, and the control means controls the exhaust gas recirculation rate in consideration of fuel consumption when the emulsion fuel is introduced.

Improvement of fuel consumption is expected by introducing emulsion fuel. On the other hand, when the exhaust gas recirculation rate (hereinafter referred to as “EGR rate”) is increased, the amount of NOx generated can be reduced, but fuel efficiency is also deteriorated.
Therefore, if the EGR rate is controlled in consideration of the fuel efficiency that is improved by introducing emulsion fuel, the NOx amount can be reduced while maintaining and improving the fuel efficiency.

  According to the control device for an internal combustion engine disclosed in the present specification, it is possible to reduce NOx of the internal combustion engine and maintain good fuel efficiency.

FIG. 1 is an explanatory diagram illustrating a schematic configuration of an engine having the control device according to the first embodiment. FIG. 2 is a control flow diagram of the first embodiment. FIG. 3 is an example of a map for calculating the mixing ratio α. FIG. 4 is an example of a target EGR rate calculation map selection map. FIG. 5 is a target NOx-BSFC and target EGR rate map. FIG. 6 is an example of the reference target EGR rate map. FIG. 7 is a control flow diagram of the second embodiment. FIG. 8 is a target NOx-BSFC and target EGR rate map. FIG. 9 is an example of an allowable NOx amount map. FIG. 10 is a control flowchart of the third embodiment. FIG. 11 is a target NOx-BSFC and target EGR rate map. FIG. 12 is a PM-BSFC change rate map. FIG. 13 is a control flowchart of the fourth embodiment. FIG. 14 is a target NOx-BSFC and target EGR rate map. FIG. 15 is a NOx-BSFC change rate map.

  Hereinafter, the best mode for carrying out the present invention will be described in detail with reference to the drawings.

  FIG. 1 is an explanatory diagram showing a schematic configuration of an engine 100 having a control device (hereinafter referred to as “control device”) 1 for an internal combustion engine according to a first embodiment. The engine 100 is an example of an internal combustion engine and is a four-cylinder diesel engine.

Engine 100 operates by burning emulsion fuel. The emulsion fuel is produced by using light oil as the first liquid serving as the base fuel and mixing the second liquid with it. As the second liquid, water, ethanol, or other liquid can be used, and a liquid obtained by mixing these can be used. The engine 100 may be a gasoline engine, gasoline may be used as a base fuel, and the second liquid as described above may be mixed with gasoline and used.
However, in the present embodiment, in order to simplify the description, a case where light oil is adopted as the first liquid and water is used as the second liquid will be described.

The engine 100 has an engine body 100a, and an intake manifold 2 and an exhaust manifold 3 are provided on the engine body 100a. A fuel injection valve 4 for injecting fuel into each cylinder and a common rail 5 for supplying high-pressure fuel to these fuel injection valves 4 are provided. The intake manifold 2 is connected to an air cleaner 9 through an intake throttle valve 6, an intercooler 7, and a compressor 8 a of an exhaust turbocharger 8. The exhaust manifold 3 is connected to an oxidation catalyst and NOx through an exhaust turbine 8 b of the exhaust turbocharger 8. It is connected to an exhaust gas purification device 10 composed of an agent or a particulate filter.
The exhaust turbocharger 8 is of a variable nozzle type and includes an actuator 8b1 for changing the opening degree of the variable nozzle (hereinafter referred to as NV opening degree).

  Exhaust gas recirculation means (EGR) is provided between the intake manifold 2 and the exhaust manifold 3. The intake manifold 2 and the exhaust manifold 3 are connected by an EGR passage 11. In the EGR passage 11, an EGR control valve 12, an EGR cooler 13, and a catalyst 14 are arranged.

  The engine 100 includes a first tank 18 that stores light oil that serves as a base fuel, and a second tank 22 that stores water that serves as a second liquid.

  The engine 100 includes a mixing tank 21 for mixing light oil and water, which is a second liquid, to generate emulsion fuel. A first supply pipe 19 extending from the first tank 18 and a second supply pipe 23 extending from the second tank 22 are connected to the mixing tank 21. A first filter 20 is provided in the first supply pipe 19. The second supply pipe 23 is provided with a second filter 24 and an electric pump 25.

  One end of a third supply pipe 26 is connected to the mixing tank 21, and the other end of the third supply pipe 26 is connected to the common rail 5. A high pressure fuel pump 27 is provided in the third supply pipe. The high-pressure fuel pump 27 uses the crankshaft of the engine 100 as a driving source, and pumps the emulsion fuel generated in the mixing tank 21 into the common rail 5. One end of a first return pipe 28 is connected to the high pressure fuel pump 27. In addition, one end of a second return pipe 29 is connected to the common rail 5, and the other end of the second return pipe 29 joins the first return pipe 28. As a result, the return fuel from the common rail 5 is returned to the high-pressure fuel pump 27. Further, one end of a third return pipe 30 is connected to each fuel injection valve 4, and the other end of the third return pipe 30 joins the first return pipe 28. Thereby, the return fuel from the fuel injection valve 4 is returned to the high-pressure fuel pump 27.

  The engine 100 includes an air cleaner 9 through which intake air passes, and an air flow meter 16 for detecting the amount of intake air is attached near the outlet of the air cleaner 9.

  The engine 100 includes an ECU (Electronic control unit) 17 that controls each part. The ECU 17 connects a read-only memory (ROM), a random access memory (RAM), a central processing unit (CPU), an input / output port, a digital analog converter (DA converter), an analog digital converter (AD converter), etc. with a bidirectional bus. It is configured as a microcomputer having a known configuration. The ECU 17 corresponds to the control means in the present invention.

  The ECU 17 is electrically connected to the intake throttle valve 6, the actuator 8 b 1, the electric pump 25, and the air flow meter 16. Further, an accelerator opening sensor 32, a supercharging pressure sensor 33, and an engine speed sensor 34 are electrically connected to the ECU 17.

  An example of exhaust gas recirculation control performed by the control device 1 as described above, that is, an example of EGR rate control, will be described with reference to the control flowchart shown in FIG. The EGR rate control is performed by the ECU 17. The control policy is to increase the EGR rate as much as possible within a range where the fuel consumption can be maintained and to increase the NOx reduction effect. In this control, finally, various EGR control parameters for changing the EGR rate are obtained.

  First, in step S <b> 1, the ECU 17 acquires engine load information of the engine 100. The engine load information is calculated based on values acquired from the accelerator opening sensor 32, the supercharging pressure sensor 33, and the air flow meter 16. In step S2, the ECU 17 acquires the engine speed Ne from the engine speed sensor 34. Note that the process in step S1 and the process in step S2 may be performed simultaneously, or may be performed in a reversed order.

  Following the processing of steps S1 and S2, the ECU 17 calculates and acquires the mixing ratio α in the emulsion fuel from the engine load information and the engine speed Ne in step S3. Here, the mixing rate α is a volume ratio between the light oil mixed in the mixing tank 21 and water. Specifically, it is calculated based on the map shown in FIG. Here, a, b, and c in FIG. 3 have a relationship of a <b <c, and the map is created so that the amount of water increases as the engine speed Ne and the engine load increase. When the mixing ratio α is 0, that is, the state where the diesel fuel as the base fuel is 100% and the engine 100 is operated only by the base fuel is the base state in the present invention.

ECU17 performs the process of step S4 following the process of step S3. In step S4, a map for calculating the target EGR rate from the engine load information and Ne from the engine speed is selected. The ECU 17 has a plurality of maps for calculating the target EGR rate. The plurality of maps are created so as to be adapted to several points according to the frequently used conditions of the engine 100. In this embodiment, the map is adapted to m1 to m9. FIG. 4 is an example of a target EGR rate calculation map selection map. Since the operating state of the engine 100 does not necessarily match m1 to m9 for which the map is matched, if the map does not match, a predetermined correction calculation is performed from the map using a map with similar conditions. This achieves highly accurate control.
As described above, by adapting the map only to the frequently used conditions and performing the correction calculation using the map, it is possible to suppress the adaptation man-hours in the map manufacturing process, and the ECU 17. It is possible to save the use area of the internal ROM.
FIG. 5 shows an example of the map selected in step S4.

In step S5, the ECU 17 uses the map shown in FIG. 5 to calculate a target NOx that becomes a Brake Specific Fuel Consumption (BSFC) equivalent to the allowable fuel in the base state. Here, BSFC is the amount of fuel consumed by engine 100, and is adopted as a parameter for evaluating fuel consumption.
FIG. 5 is a target NOx-BSFC and target EGR rate map. This map has a part (A) in which the horizontal axis represents the target NOx, the vertical axis represents the target EGR rate, and the part (B) in which the horizontal axis represents the target NOx and the vertical axis represents BSFC. ing.
Note that the example shown in FIG. 5 shows a map when the mixing ratio α = b (%). However, when α = c (%), the map is shown by a thin solid line in FIG. A simple curve is drawn. When the value of α is between b (%) and c (%), a map is created by calculation.

  The ECU 17 refers to the map shown in FIG. 5 and calculates the target EGR rate. For this purpose, first, the allowable fuel consumption is obtained. The allowable fuel consumption is a fuel consumption in a base state where only diesel oil is used. In order to obtain the allowable fuel consumption, a reference target EGR rate map shown in FIG. 6 is referred to. This reference target EGR rate map is obtained by mapping the target EGR rate in the base state in relation to the engine speed Ne. Then, the target EGR rate calculated from the reference target EGR rate map is applied to the (A) portion of the map shown in FIG. Thereby, the value of the target NOx at the intersection of the target EGR rate and the curve corresponding to the base state is obtained (point X). The BSFC at the intersection (point x) between the value of the target NOx at point X and the curve corresponding to the base state in part (B) is the allowable fuel consumption.

  If the target NOx is located on a straight line indicating the allowable fuel consumption, fuel consumption equivalent to the allowable fuel consumption is ensured. In part (B), the target NOx at the intersection b1 between the straight line indicating the allowable fuel consumption and the curve indicating α = b (%) is obtained. This is the process in step S5.

  Following step S5, the ECU 17 calculates a target EGR rate in step S6. ECU17 calculates | requires the target EGR rate corresponding to B1 point on the (A) part which implement | achieves target NOx calculated by step S5. Through the above processing, the target EGR can be calculated.

  The target EGR rate obtained in this way can be made larger than the point X in part (A), and the target NOx can be reduced. At this time, the calculated target EGR rate corresponds to the B1 point in the (A) portion, and the B1 point corresponds to the b1 point in the (B) portion. Since the fuel consumption b1 is equivalent to the allowable fuel consumption, the fuel consumption in the base state is maintained.

  In addition, if the target EGR rate is further increased and the point B2 in the part (A) is set, the target NOx can be further decreased. However, the point b2 corresponding to the point B2 has a BSFC larger than the allowable fuel consumption, Fuel consumption will deteriorate.

  ECU17 which finished the process of step S6 calculates an EGR control parameter in step S7. The EGR control parameter is calculated so as to be the target EGR rate calculated up to step S6. Then, a command is issued to the intake throttle valve 6, the actuator 8b1, and the EGR control valve 12 controlled by the EGR control parameter.

  Thus, a series of controls are completed. By performing such control, NOx can be reduced while maintaining good fuel efficiency of engine 100.

Next, Example 2 will be described. Since the hardware configuration of the second embodiment is the same as that of the first embodiment, detailed description thereof will be omitted. Example 2 and Example 1 differ in the following points. That is, in the first embodiment, the target NOx amount is set to a value corresponding to the allowable fuel consumption, whereas in the second embodiment, the target NOx amount is set to the allowable NOx amount.
Even if it is a case where further NOx reduction can be aimed at by performing the control of the first embodiment, if the target EGR rate is kept within a range where the allowable NOx amount can be achieved, it is possible to distribute the fuel efficiency accordingly.

  An example of EGR rate control performed under the above policy will be described with reference to the control flowchart shown in FIG. The EGR rate control is performed by the ECU 17.

  Since the processing from step S11 to step S14 is the same as the processing from step S1 to step S4 in the first embodiment, detailed description thereof is omitted. FIG. 8 shows an example of the map selected in step S14.

  In step S15, the allowable NOx amount is calculated with reference to the map shown in FIG. The allowable NOx amount is calculated from the engine load and the engine speed Ne. Here, in FIG. 9, i, ii, iii, iv, and v have a relationship of i <ii <iii <iv <v, and the map shows the allowable NOx amount as the engine speed Ne and the engine load increase. Has been created to increase. The allowable NOx amount can be a predetermined value without using a map.

  FIG. 8 is a target NOx-BSFC and target EGR rate map. This map has a part (A) in which the horizontal axis represents the target NOx, the vertical axis represents the target EGR rate, and the part (B) in which the horizontal axis represents the target NOx and the vertical axis represents BSFC. ing. In step S15, the ECU 17 sets the allowable NOx amount to the target NOx amount. FIG. 8 shows a case where the allowable NOx amount is iii and this is set as the target NOx amount.

  After step S15, the ECU 17 calculates the target EGR rate in step S16. ECU17 calculates | requires the target EGR rate corresponding to B4 point on the (A) part which implement | achieves target NOx set by step S15. Through the above processing, the target EGR can be calculated.

  By setting the target EGR rate in this way, it is possible to further improve the fuel efficiency while clearing the allowable NOx amount.

  As in the first embodiment, in order to secure the fuel consumption equivalent to the allowable fuel consumption in the base state, the target NOx at the intersection b3 between the straight line indicating the allowable fuel consumption and the curve indicating α = b (%) in the (B) portion is set. Suppose that it is set. Then, the target NOx amount becomes smaller than iii, as indicated by point B3 in part (A). However, the target NOx emission amount only needs to clear iii. Therefore, the target EGR rate is kept at a value corresponding to point B4. Thereby, a fuel consumption improvement can be aimed at. As is clear from part (B), if the target EGR rate is set to the B4 point, the BSFC becomes a point corresponding to the b4 point, and can be lower than the BSFC corresponding to the b3 point. This decrease is an improvement in fuel consumption.

  After completing the process in step S16, the ECU 17 calculates an EGR control parameter in step S17. The EGR control parameter is calculated so as to be the target EGR rate calculated up to step S16. Then, a command is issued to the intake throttle valve 6, the actuator 8b1, and the EGR control valve 12 controlled by the EGR control parameter.

  Thus, a series of controls are completed. By performing such control, the fuel consumption of the engine 100 can be improved while protecting the allowable NOx emission amount.

  Next, Example 3 will be described. Since the hardware configuration of the third embodiment is the same as that of the first embodiment, a detailed description thereof will be omitted. Example 3 and Example 1 differ in the allowable fuel consumption that is set. In the first embodiment, the fuel consumption of the engine 100 in the base state is set to the allowable fuel consumption, but in the third embodiment, the improved fuel consumption ΔFC1 obtained by further reducing the fuel used in the rich spike to the fuel consumption in the base state. Allowable fuel consumption is set in consideration of By shifting from the base state to an emulsion mixed state in which emulsion fuel is mixed, the amount of particulate matter (PM) can be reduced. When the reduction in PM is acquired, the amount of fuel used for the rich spike used for the rich spike performed to regenerate PM clogging in the exhaust filter can be reduced. If the amount of fuel used for rich spikes can be reduced, the fuel efficiency will be improved accordingly. In the third embodiment, the fuel consumption considering the improved fuel consumption ΔFC1 is set as the allowable fuel consumption. Then, the target EGR rate is increased within a range in which the fuel consumption does not deteriorate beyond the allowable fuel consumption set in this way. Thereby, NOx can be further reduced.

  An example of EGR rate control performed under the above policy will be described with reference to the control flowchart shown in FIG. The EGR rate control is performed by the ECU 17.

  Since the processing from step S21 to step S24 is the same as the processing from step S1 to step S4 in the first embodiment, detailed description thereof is omitted. FIG. 11 shows an example of the map selected in step S24.

In step S25, the ECU 17 calculates an improved fuel consumption ΔFC1 using the maps shown in FIGS.
FIG. 11 is a target NOx-BSFC and target EGR rate map. This map has a part (A) in which the horizontal axis represents the target NOx, the vertical axis represents the target EGR rate, and the part (B) in which the horizontal axis represents the target NOx and the vertical axis represents BSFC. ing. The map shown in FIG. 11 has a (C) portion in addition to the (A) portion and the (B) portion in the map in the first embodiment shown in FIG. Part (C) shows the relationship between the target NOx amount and the PM amount.

  The ECU 17 refers to the map shown in FIG. 11 and calculates the target EGR rate. For this purpose, first, the ECU 17 obtains the fuel consumption in the base state where only the diesel oil is operated. In order to obtain this fuel consumption, a reference target EGR rate map shown in FIG. 6 is referred to. This is the same as in the first embodiment. Then, the target EGR rate calculated from the reference target EGR rate map is applied to the (A) portion of the map shown in FIG. Thereby, the value of the target NOx at the intersection of the target EGR rate and the curve corresponding to the base state is obtained (point X). The BSFC at the intersection (point x) between the value of the target NOx at point X and the curve corresponding to the base state in part (B) is calculated.

  And the intersection b1 of the straight line which shows the fuel consumption corresponding to x point, and the curve which shows (alpha) = b (%) is calculated | required. The ECU 17 refers to part (C) and calculates the difference between the PM amount corresponding to the point x and the PM amount corresponding to the point b1. Then, the map shown in FIG. 12 is referred to. FIG. 12 is a PM-BSFC change rate map. If the amount of PM is small, the amount of fuel used for the rich spike can be suppressed, leading to improved fuel efficiency. Therefore, the ECU 17 calculates the improved fuel efficiency ΔFC1 with reference to the map shown in FIG.

  In step S26 performed after step S25, the ECU 17 adds the improved fuel consumption ΔFC1 calculated in step S35 to the BSFC at the point x, and sets this value as the allowable fuel consumption. And target NOx used as BSFC equivalent to this BSFC is calculated. Specifically, in part (B), the target NOx at the intersection b5 between the straight line indicating the allowable fuel consumption and the curve indicating α = b (%) is obtained. This is the process in step S26.

  Following step S26, the ECU 17 calculates a target EGR rate in step S27. ECU17 calculates | requires the target EGR rate corresponding to B5 point on the (A) part which implement | achieves target NOx calculated by step S26. Through the above processing, the target EGR can be calculated.

  The target EGR rate obtained in this way can be made larger than the point b1 in the part (A) and the target NOx can be reduced. That is, compared with the first embodiment, the target NOx can be reduced. At this time, the calculated target EGR rate corresponds to the B5 point in the (A) portion, and the B5 point corresponds to the b5 point in the (B) portion. The b5 point seems to have deteriorated fuel consumption at first glance compared with b1. However, since the amount of fuel used for rich spikes is reduced, the fuel efficiency equivalent to that in the base state is maintained when the engine 100 is viewed as a whole.

  After completing the process in step S27, the ECU 17 calculates an EGR control parameter in step S28. The EGR control parameter is calculated so as to be the target EGR rate calculated up to step S27. Then, a command is issued to the intake throttle valve 6, the actuator 8b1, and the EGR control valve 12 controlled by the EGR control parameter.

  Thus, a series of controls are completed. By performing such control, it is possible to further reduce NOx while maintaining good fuel efficiency of engine 100.

  Next, Example 4 will be described. Since the hardware configuration of the fourth embodiment is the same as that of the first embodiment, a detailed description thereof will be omitted. Example 4 and Example 1 differ in the allowable fuel consumption that is set. In the first embodiment, the fuel consumption of the engine 100 in the base state is set to the allowable fuel consumption. In the fourth embodiment, the improved fuel consumption ΔFC2 obtained by further reducing the fuel used in the rich spike to the fuel consumption in the base state. Allowable fuel consumption is set in consideration of By shifting from the base state to an emulsion mixed state in which emulsion fuel is mixed, NOx can be reduced. When the reduction in NOx is acquired, the amount of fuel used for the rich spike used for the rich spike for the NOx storage reduction catalyst can be reduced. If the amount of fuel used for rich spikes can be reduced, the fuel efficiency will be improved accordingly. In the fourth embodiment, the fuel consumption considering the improved fuel consumption ΔFC2 is set as the allowable fuel consumption. Then, the target EGR rate is increased within a range in which the fuel consumption does not deteriorate beyond the allowable fuel consumption set in this way. Thereby, NOx can be further reduced.

  An example of EGR rate control performed under the above policy will be described with reference to the control flowchart shown in FIG. The EGR rate control is performed by the ECU 17.

  Since the processing from step S31 to step S34 is the same as the processing from step S1 to step S4 in the first embodiment, detailed description thereof is omitted. FIG. 14 shows an example of the map selected in step S34.

In step S35, the ECU 17 calculates an improved fuel efficiency ΔFC2 using the maps shown in FIGS.
FIG. 14 is a target NOx-BSFC and target EGR rate map. This map has a part (A) in which the horizontal axis represents the target NOx, the vertical axis represents the target EGR rate, and the part (B) in which the horizontal axis represents the target NOx and the vertical axis represents BSFC. ing.

  The ECU 17 refers to the map shown in FIG. 14 to calculate the target EGR rate. For this purpose, first, the ECU 17 obtains the fuel consumption in the base state where only the diesel oil is operated. In order to obtain this fuel consumption, a reference target EGR rate map shown in FIG. 6 is referred to. This is the same as in the first embodiment. Then, the target EGR rate calculated from the reference target EGR rate map is applied to the (A) portion of the map shown in FIG. Thereby, the value of the target NOx at the intersection of the target EGR rate and the curve corresponding to the base state is obtained (point X). The BSFC at the intersection (point x) between the value of the target NOx at point X and the curve corresponding to the base state in part (B) is calculated.

  And the intersection b1 of the straight line which shows the fuel consumption corresponding to x point, and the curve which shows (alpha) = b (%) is calculated | required. The ECU 17 refers to the part (A) and calculates the difference between the target NOx corresponding to the x point and the target NOx corresponding to the b1 point. Then, the map shown in FIG. 15 is referred to. FIG. 15 is a NOx-BSFC change rate map. If the amount of NOx is small, the amount of fuel used for the rich spike can be suppressed, which leads to an improvement in fuel consumption. Therefore, the ECU 17 calculates the improved fuel efficiency ΔFC2 with reference to the map shown in FIG.

  In step S36 performed after step S35, the ECU 17 adds the improved fuel consumption ΔFC2 calculated in step S35 to the BSFC at the point x, and sets this value as the allowable fuel consumption. And target NOx used as BSFC equivalent to this BSFC is calculated. Specifically, in part (B), the target NOx at the intersection b6 between the straight line indicating the allowable fuel consumption and the curve indicating α = b (%) is obtained. This is the process in step S36.

  Following step S36, the ECU 17 calculates a target EGR rate in step S37. ECU17 calculates | requires the target EGR rate corresponding to B6 point on the (A) part which implement | achieves target NOx calculated by step S36. Through the above processing, the target EGR can be calculated.

  The target EGR rate obtained in this way can be made larger than the point b1 in the part (A) and the target NOx can be reduced. That is, compared with the first embodiment, the target NOx can be reduced. At this time, the calculated target EGR rate corresponds to the B6 point in the (A) portion, and the B6 point corresponds to the b6 point in the (B) portion. The b6 point seems to have deteriorated fuel consumption at first glance compared with b1. However, since the amount of fuel used for rich spikes is reduced, the fuel efficiency equivalent to that in the base state is maintained when the engine 100 is viewed as a whole.

  After completing the process in step S37, the ECU 17 calculates an EGR control parameter in step S38. The EGR control parameter is calculated so as to be the target EGR rate calculated up to step S37. Then, a command is issued to the intake throttle valve 6, the actuator 8b1, and the EGR control valve 12 controlled by the EGR control parameter.

  Thus, a series of controls are completed. By performing such control, it is possible to further reduce NOx while maintaining good fuel efficiency of engine 100.

  The above-described embodiments are merely examples for carrying out the present invention, and the present invention is not limited thereto. Various modifications of these embodiments are within the scope of the present invention. It is apparent from the above description that various other embodiments are possible within the scope.

DESCRIPTION OF SYMBOLS 1 ... Control apparatus 2 ... Intake manifold 3 ... Exhaust manifold 4 ... Fuel injection valve 5 ... Common rail 6 ... Intake throttle valve 8 ... Exhaust turbocharger 8b1 ... Actuator 11 ... EGR passage 12 ... EGR control valve 13 ... EGR cooler 17 ... ECU
DESCRIPTION OF SYMBOLS 18 ... 1st tank 21 ... Mixing tank 22 ... 2nd tank 25 ... Electric pump 27 ... High pressure fuel pump 100 ... Engine

Claims (5)

A control device for an internal combustion engine in which emulsion fuel is used,
Exhaust gas recirculation means;
Means for controlling the exhaust gas recirculation rate in the exhaust gas recirculation means;
With
The control device for an internal combustion engine, wherein the control means controls the exhaust gas recirculation rate in consideration of fuel consumption when the emulsion fuel is introduced. The control means includes
Setting the fuel efficiency of the internal combustion engine in the base state of the internal combustion engine operated only by the base fuel to an allowable fuel efficiency,
2. The control apparatus for an internal combustion engine according to claim 1, wherein the exhaust gas recirculation rate is increased within a range in which the fuel consumption does not deteriorate than the allowable fuel consumption. The control means includes
2. The control apparatus for an internal combustion engine according to claim 1, wherein the exhaust gas recirculation rate is determined so as to be an allowable NOx amount. The control means includes
Decreased due to a decrease in the amount of particulate matter acquired by transitioning from the base state to the emulsion mixed state in which the emulsion fuel is mixed from the base state to the fuel efficiency of the internal combustion engine operating only with the base fuel Set the fuel consumption considering the improved fuel consumption ΔFC1 based on the amount of fuel available for rich spikes to the allowable fuel consumption,
2. The control apparatus for an internal combustion engine according to claim 1, wherein the exhaust gas recirculation rate is increased within a range in which the fuel consumption does not deteriorate than the allowable fuel consumption. The control means includes
Rich fuel that can be reduced due to the reduction in NOx obtained by shifting from the base state to the emulsion mixed state in which the emulsion fuel is mixed into the fuel efficiency of the internal combustion engine that is operated only by the base fuel. Set the fuel consumption considering the improved fuel consumption ΔFC2 based on the spike fuel consumption amount to the allowable fuel consumption,
2. The control apparatus for an internal combustion engine according to claim 1, wherein the exhaust gas recirculation rate is increased within a range in which the fuel consumption does not deteriorate than the allowable fuel consumption.

Images