Internal combustion engine control system

Abstract

To provide a control system for an internal combustion engine that executes exhaust gas temperature increase control corresponding to a fuel mixing ratio.SOLUTION: A control system is for an internal combustion engine that can use fuel obtained by mixing first fuel and second fuel. The control system for the internal combustion engine includes: a filter for collecting particulate matters in an exhaust gas from the internal combustion engine; an injection valve for injecting fuel to be supplied to an upstream side of the filter; and a control device that executes temperature increase control for increasing exhaust gas temperature upstream of the filter before regeneration of the filter. On the basis of a mixing ratio of the first fuel and the second fuel, the control device preferentially executes either, first temperature increase control for increasing the exhaust gas temperature by controlling an injection amount of the injection valve of the internal combustion engine or second temperature increase control for increasing the exhaust gas temperature by controlling an exhaust gas flow rate of the internal combustion engine.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present disclosure relates to control systems for internal combustion engines. [Background technology]

[0002] Conventionally, a filter that captures particulate matter in the exhaust gas of an internal combustion engine has been known (see, for example, Patent Document 1). Patent Document 1 discloses a method for regenerating a filter in an internal combustion engine using biofuel. Such a filter requires increasing the exhaust gas temperature before regenerating the filter. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2013-19283 A Summary of the Invention [Problem to be solved by the invention]

[0004] Biofuels are less likely to vaporize than petroleum-derived fuels. Therefore, when the exhaust temperature is increased by using biofuels, fuel efficiency is deteriorated. Furthermore, in recent years, biofuels are often used in combination with petroleum-derived fuels. Therefore, it is preferable to perform optimal control according to the mixture ratio of biofuels and petroleum-derived fuels to increase the exhaust temperature.

[0005] An object of the present disclosure is to provide a control system for an internal combustion engine that executes exhaust gas temperature increase control in accordance with the mixture ratio of fuel. [Means for solving the problem]

[0006] A control system for an internal combustion engine capable of using a fuel mixture of a first fuel and a second fuel, the control system comprising: a filter that collects particulate matter in exhaust gas from the internal combustion engine; an injection valve that injects fuel to be supplied upstream of the filter; and a control device that executes temperature rise control to raise the exhaust temperature upstream of the filter before regenerating the filter, the control device executing a first temperature rise control to raise the exhaust temperature by controlling an injection amount by the injection valve of the internal combustion engine based on a mixing ratio of the first fuel and the second fuel; Maintaining the injection amount by the injection valve; The second temperature rise control is performed by controlling the exhaust flow rate and raising the exhaust temperature. The first fuel includes a biofuel, and the second fuel is a fuel different from the biofuel, and the control device prioritizes the second temperature rise control as the mixing ratio of the first fuel is higher. Control system for internal combustion engines.

[0007] According to this internal combustion engine control system, the first temperature rise control or the second temperature rise control is prioritized according to the mixture ratio of the first fuel and the second fuel, so that optimal exhaust temperature rise control according to the mixture ratio can be executed, thereby suppressing fuel consumption. Effect of the Invention

[0008] According to the present disclosure, it is possible to provide a control system for an internal combustion engine that executes exhaust gas temperature increase control according to the mixture ratio of fuel. [Brief description of the drawings]

[0009] [Figure 1] 1 is a system diagram of an internal combustion engine control system according to an embodiment of the present disclosure. [Diagram 2] FIG. 4 is a diagram showing a mixture ratio determined by a control device according to an embodiment of the present disclosure. [Diagram 3] 4 is a flowchart showing a control procedure of a control device according to an embodiment of the present disclosure. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] Hereinafter, an embodiment of the present disclosure will be described with reference to the drawings. In the following description, the upstream side with respect to the flow direction of intake air or exhaust air will be referred to as "upstream" and the downstream side will be referred to as "downstream".

[0011] As shown in FIG. 1, a control system 1 of an internal combustion engine 2 includes a fuel injection valve (an example of an injection valve) 2c, a filter 4, a PM sensor (an example of a detection unit) 6, an exhaust gas recirculation device 8, a fuel tank 10, a fuel filler lid 12, a turbocharger 14, an intercooler 16, a throttle valve 18, and a control device 20. The internal combustion engine 2 of this embodiment is a diesel engine that can use biofuel (an example of a first fuel) and diesel (an example of a second fuel) in the fuel tank 10. The internal combustion engine 2 sends intake air from an intake passage 2a to a cylinder 2b, where the intake air is mixed with fuel injected from a fuel injection valve 2c. The internal combustion engine 2 compresses the mixture with a piston 2d and self-ignites it. The internal combustion engine 2 of this embodiment is mounted on a vehicle (for example, an automobile).

[0012] In this embodiment, in the internal combustion engine 2, exhaust gas discharged from the cylinder 2b rotates a turbine 14a of a turbocharger 14. The turbine 14a rotates a compressor 14b arranged coaxially therewith, and supercharges the intake air. The supercharged intake air is cooled by an intercooler 16. However, the turbocharger 14 is not necessarily required.

[0013] The filter 4 is disposed in an exhaust purification device 3 that purifies exhaust gas. The filter 4 collects particulate matter contained in the exhaust gas. In this embodiment, the filter 4 is a diesel particulate filter that collects particulate matter (PM) from a diesel engine. An oxidation catalyst 4a is disposed upstream of the filter 4. The exhaust purification device 3 may also have a NOx trap, a urea selective reduction catalyst, or the like (not shown) disposed downstream of the filter 4.

[0014] The PM sensor 6 is disposed upstream of the filter 4 and detects the accumulation state of particulate matter. The PM sensor 6 is a sensor whose current value changes when particulate matter accumulates. Specifically, when particulate matter accumulates, the current flows more easily and the current value increases. The PM sensor 6 has a heater 6a. The heater 6a burns and removes particulate matter accumulated on the PM sensor 6. Other configurations of the PM sensor 6 may be similar to those of existing PM sensors, and detailed description will be omitted. In this embodiment, the PM sensor 6 is disposed between the oxidation catalyst 4a and the filter 4. This can prevent the adhesion of fuel residues and the like to the PM sensor 6. However, the PM sensor 6 may be disposed upstream of the oxidation catalyst 4a. The PM sensor 6 is electrically connected to the control device 20 and transmits a current value to the control device 20. In addition, the operation of the heater 6a is controlled by the control device 20.

[0015] The exhaust recirculation device 8 is a device that introduces exhaust recirculation gas into the internal combustion engine 2. More specifically, the exhaust recirculation device 8 is a device that recirculates the exhaust discharged from the cylinder 2b to the intake passage 2a. The exhaust recirculation device 8 has an exhaust recirculation passage 8a and an exhaust recirculation valve 8b. The exhaust recirculation passage 8a connects the exhaust passage 4b ​​and the intake passage 2a. The exhaust recirculation valve 8b is provided on the exhaust recirculation passage 8a, and introduces the exhaust recirculation gas recirculated from the exhaust into the intake passage 2a by opening and closing the exhaust recirculation passage 8a. The exhaust recirculation valve 8b is electrically connected to the control device 20 and is controlled by the control device 20. The control device 20 controls the exhaust recirculation valve 8b to control the amount of exhaust recirculation gas introduced into the intake air. In this embodiment, the control device 20 controls the throttle valve 18 to generate a negative pressure in the intake passage 2a by closing the throttle valve 18. The control device 20 can also control the amount of exhaust recirculation gas introduced by this.

[0016] The fuel tank 10 is a device for storing biofuel and diesel and supplying them to the fuel injection valve 2c. In this embodiment, the fuel tank 10 has a fuel filler lid 12 that opens and closes a fuel filler port 10a, and a fuel level sensor 10b. The fuel filler lid 12 is electrically connected to the control device 20 and transmits the open / closed state of the fuel filler lid 12 to the control device 20. The fuel level sensor 10b is electrically connected to the control device 20 and transmits the remaining amount of fuel in the fuel tank 10 (fuel level) to the control device 20.

[0017] The control device 20 executes a determination control to determine the mixing ratio (mixing rate) of the biofuel and diesel based on a first accumulation amount, which is a preset accumulation amount of particulate matter accumulated by the biofuel, a second accumulation amount, which is a preset accumulation amount of particulate matter accumulated by the diesel, and a third accumulation amount of particulate matter detected by the PM sensor 6.

[0018] More specifically, as shown in Fig. 2, the control device 20 stores the change in a first deposition amount (see the dashed line in Fig. 2), which is the deposition amount of particulate matter during a predetermined time, when only biofuel is used in the internal combustion engine 2. The control device 20 also stores the change in a second deposition amount (see the dashed line in Fig. 2), which is the deposition amount of particulate matter during a predetermined time, when only diesel is used in the internal combustion engine 2. The predetermined time may be the time during which the change in the first deposition amount and the change in the second deposition amount are measured by experiment. The control device 20 compares the first deposition amount, the second deposition amount, and the third deposition amount obtained from the PM sensor 6 (see the solid line in Fig. 2), to determine the mixing ratio of biofuel and diesel.

[0019] In this embodiment, the control device 20 calculates an estimated deposition amount (see the two-dot chain line in FIG. 2) according to the mixture ratio of biofuel and diesel based on the first deposition amount and the second deposition amount. The control device 20 acquires a third deposition amount corresponding to the deposition amount of particulate matter actually flowing in the exhaust gas from the current value of the PM sensor 6. The control device 20 judges whether the actual mixture ratio is higher or lower than the estimated mixture ratio by comparing the acquired third deposition amount with the estimated deposition amount. When the third deposition amount is higher than the estimated mixture ratio, the control device 20 corrects the ratio of diesel to be higher than the estimated ratio. On the other hand, when the third deposition amount is lower than the estimated mixture ratio, the control device 20 corrects the ratio of biofuel to be higher than the estimated ratio. This allows the control device 20 to judge the mixture ratio. The PM sensor 6 has a dead zone for a certain period until the particulate matter is deposited on the sensor element of the PM sensor 6. The control device 20 calculates the estimated deposition amount during this period as well.

[0020] The control device 20 determines the introduction ratio of the exhaust recirculation gas, and controls the opening degree of the exhaust recirculation valve 8b so that the introduction amount of the exhaust recirculation gas becomes the introduction ratio determined with respect to the intake air amount detected by the air flow sensor 22 attached to the air cleaner 32. The control device 20 may determine the introduction ratio of the exhaust recirculation gas based on a map that defines the introduction ratio of the exhaust recirculation gas for each operating range of the internal combustion engine 2.

[0021] Furthermore, the control device 20 executes temperature rise control to raise the exhaust temperature upstream of the filter 4 before regenerating the filter 4. In the temperature rise control, the control device 20 executes, with priority, either a first temperature rise control to raise the exhaust temperature by controlling the injection amount by the fuel injection valve 2c, or a second temperature rise control to raise the exhaust temperature by controlling the exhaust flow rate flowing through the oxidation catalyst 4a.

[0022] In this embodiment, in the first temperature rise control, the control device 20 injects fuel from the fuel injection valve 2c in the latter half of the expansion stroke of the internal combustion engine 2. As a result, the fuel is supplied to the oxidation catalyst 4a arranged upstream of the filter 4. The fuel supplied to the oxidation catalyst 4a diffuses into the oxidation catalyst 4a, is adsorbed therein, and undergoes a combustion reaction. As a result, the temperature of the exhaust gas that has passed through the oxidation catalyst 4a increases. As a result, the exhaust gas flowing into the filter 4 becomes hot. The hot exhaust gas burns the particulate matter trapped in the filter 4, regenerating the filter 4.

[0023] In the second temperature rise control, the control device 20 controls the turbocharger 14 and the throttle valve 18 to execute exhaust flow control for controlling the exhaust flow rate flowing to the oxidation catalyst 4a. More specifically, the control device 20 reduces the intake amount by reducing the boost pressure by the turbocharger 14. On the other hand, the fuel injection amount from the fuel injection valve 2c is maintained, and a mixture with a rich air-fuel ratio is supplied to the oxidation catalyst 4a. As a result, the fuel reacts with the oxidation catalyst 4a through combustion, and the exhaust temperature rises. The reduction in the boost pressure can be achieved by reducing the opening of the wastegate valve 14c. In addition, in the case where the turbine 14a is of a variable vane type, the boost pressure can also be reduced by enlarging the variable vane. In addition, the control device 20 can also reduce the intake amount by reducing the opening of the throttle valve 18. As a result, the exhaust temperature rises, similar to the reduction in the boost pressure.

[0024] In addition, the control device 20 may control each device, such as the fuel injection valve 2c, the exhaust gas recirculation valve 8b, and the supercharging pressure of the supercharger 14, based on values ​​acquired from sensors such as the airflow sensor 22 and the accelerator position sensor 30a, so that the internal combustion engine 2 is in a desired operating state. The control device 20 is actually an ECU (Electronic Control Unit) configured by a microcomputer including a calculation device, a memory, an input / output buffer, and the like. The control device 20 controls each device based on a map and a program stored in the memory so that the internal combustion engine 2 is in a desired operating state. Note that the various controls are not limited to processing by software, and can also be processed by dedicated hardware (electronic circuits).

[0025] Next, the control executed by the control device 20 will be described with reference to the flowchart of Fig. 3. The control device 20 starts a control procedure when an ignition switch (not shown) is turned on.

[0026] In step S1, the control device 20 acquires the blend ratio (blending rate) of biofuel and diesel. After acquiring the blend ratio, the control device 20 advances the process to step S2.

[0027] In step S2, the control device 20 determines whether or not a regeneration condition for the filter 4 is satisfied. In this embodiment, the control device 20 determines whether or not a regeneration condition for the filter 4 is satisfied based on whether or not an amount of particulate matter deposited on the filter 4 is equal to or greater than a predetermined amount. Whether or not a predetermined amount of particulate matter has deposited can be detected, for example, by the pressure difference between before and after the filter. Alternatively, it may be detected by the PM sensor 6.

[0028] Furthermore, in this embodiment, the control device 20 judges whether the regeneration conditions are established according to the operating state of the internal combustion engine 2 and the state of the vehicle, in addition to whether the amount of particulate matter deposited on the filter 4 is equal to or greater than a predetermined amount. The control device 20 may judge whether the regeneration conditions are established according to whether the operating state of the internal combustion engine 2, such as the fuel injection amount of the internal combustion engine 2, the exhaust temperature, and the rotation speed of the internal combustion engine 2, are suitable conditions for regenerating the filter 4. The control device 20 may also judge whether the regeneration conditions are established according to whether the speed of the vehicle is suitable conditions for regenerating the filter 4. When the control device 20 judges that the regeneration conditions of the filter 4 are established (step S2 YES), the control device 20 proceeds to the process of step S3. When the control device 20 judges that the regeneration conditions of the filter 4 are not established (step S2 NO), the control device 20 returns the process to step S1.

[0029] In step S3, the control device 20 judges whether the ratio of biofuel is equal to or greater than a predetermined ratio. The predetermined ratio may be set based on the degree of fuel vaporization required for the fuel to undergo a combustion reaction in the oxidation catalyst 4a. In general, the higher the mixing ratio of biofuel, the worse the fuel vaporization. For this reason, the predetermined ratio may be set to, for example, 30 percent (30% biofuel, 70% diesel). In any case, the predetermined ratio may be determined so that the higher the mixing ratio of biofuel, the higher the priority of the second temperature rise control. If the control device 20 judges that the ratio of biofuel is equal to or greater than the predetermined ratio (YES in step S3), the control device 20 proceeds to step S4. If the control device 20 judges that the ratio of biofuel is not equal to or greater than the predetermined ratio (NO in step S3), the control device 20 proceeds to step S10, which will be described later.

[0030] In step S4, the control device 20 executes the second temperature rise control. After executing the second temperature rise control, the control device 20 proceeds to step S5, where the control device 20 executes the exhaust flow rate control by the turbocharger 14 in priority over the exhaust flow rate control by the throttle valve 18. Reducing the opening of the throttle valve 18 increases pump loss. This tends to deteriorate the fuel efficiency of the internal combustion engine 2. For this reason, the control device 20 suppresses pump loss and inhibits deterioration of fuel efficiency by executing the exhaust flow rate control by the turbocharger 14 in priority over the exhaust flow rate control by the throttle valve 18. After executing the exhaust flow rate control by the turbocharger 14, the control device 20 proceeds to step S6.

[0031] In step S6, the control device 20 judges whether the reduction in the supercharging pressure by the supercharger 14 has reached its limit. When the control device 20 judges that the rotation speed of the turbine 14a or the rotation speed of the compressor 14b has decreased and that it is difficult to maintain the output of the internal combustion engine 2 according to the depression amount of the accelerator pedal 30, the control device 20 may judge that the exhaust flow rate control by the supercharger 14 has reached its limit. When the control device 20 judges that the reduction in the supercharging pressure by the supercharger 14 has reached its limit (YES in step S6), the control device 20 proceeds to the process in step S7.

[0032] In step S7, the control device 20 executes exhaust flow rate control (throttle control) using the throttle valve 18. In this way, the control device 20 suppresses pump loss by prioritizing the exhaust flow rate control by the turbocharger 14 over the exhaust flow rate control by the throttle valve 18. After executing the exhaust flow rate control by the throttle valve 18, the control device 20 advances the process to step S8.

[0033] In step S8, the control device 20 judges whether the exhaust flow rate control is at its limit. The control device 20 may judge that the exhaust flow rate control is at its limit if it judges that it will be difficult to maintain the output of the internal combustion engine 2 according to the depression amount of the accelerator pedal 30 if the opening of the throttle valve 18 is further reduced. If the control device 20 judges that the exhaust flow rate control is not at its limit (NO in step S8), the process proceeds to step S9.

[0034] In step S9, the control device 20 determines whether or not regeneration of the filter 4 has been completed. In this embodiment, the control device 20 determines that regeneration of the filter 4 has been completed when the pressure difference between the front and rear of the filter 4 is within a predetermined range. When the control device 20 determines that regeneration of the filter 4 has been completed (YES in step S9), the process returns to step S1.

[0035] In step S2, when the control device 20 determines that the regeneration condition for the filter 4 is not satisfied (step S2 NO), the control device 20 returns the process to step S1 in order not to execute or to prohibit the regeneration of the filter 4.

[0036] For example, when the internal combustion engine 2 is operated under a predetermined load, the control device 20 determines that the regeneration conditions for the filter 4 are not satisfied and prohibits the temperature increase control. The predetermined load is, for example, when the accelerator pedal 30 is fully depressed. In such a case, the output required for the internal combustion engine 2 is high. For this reason, the control device 20 needs to use the fuel for the output of the internal combustion engine 2 rather than for the regeneration of the filter 4.

[0037] Also, for example, when the internal combustion engine 2 is operated at low revolutions and the vehicle speed is low, if the revolution speed of the internal combustion engine 2 increases due to regeneration of the filter 4, the user of the vehicle feels uncomfortable. In such a state, the control device 20 may determine that the regeneration conditions of the filter 4 are not satisfied. In any case, the control device 20 may determine that the regeneration conditions of the filter 4 are not satisfied depending on the operating state of the internal combustion engine 2 and the traveling state of the vehicle, and may prohibit regeneration of the filter 4.

[0038] In step S3, when the control device 20 determines that the ratio of biofuel is less than the predetermined ratio (NO in step S3), the control device 20 advances the process to step S10. Steps after S10 will be described later.

[0039] In step S6, when the control device 20 determines that the decrease in the supercharging pressure by the supercharger 14 is not at the limit point (NO in step S6), the control device 20 returns the process to step S5 and continues the exhaust flow rate control by the supercharger 14.

[0040] In step S8, if the control device 20 determines that the exhaust flow rate control is at its limit (step S8 YES), the control device 20 advances the process to step S12 and executes the first temperature rise control. In this way, the control device 20 executes the first temperature rise control when the second temperature rise control cannot be executed any more. In other words, the control device 20 executes the second temperature rise control preferentially when the biofuel ratio is equal to or greater than a predetermined ratio. In step S8, if the control device 20 determines that the exhaust flow rate control is not at its limit (step S8 NO), the control device 20 advances the process to step S9. In step S9, the control device 20 determines whether or not the regeneration of the filter 4 has been completed.

[0041] In step S9, if the control device 20 determines that the regeneration of the filter 4 has not been completed (step S9 NO), the control device 20 returns to the process in step S3, and if there is no change in the mixture ratio, the second temperature increase control is continued. If the control device 20 determines that the regeneration of the filter 4 has been completed (step S9 YES), the control device 20 returns to the process in step S1.

[0042] In step S10, the control device 20 determines whether refueling has been performed. In this embodiment, the control device 20 detects the open / closed state of the fuel filler lid 12, and determines that refueling has started when the fuel filler lid 12 is open. Alternatively, the control device 20 may determine that refueling has been performed when it is determined that the fuel level has risen. When the control device 20 determines that refueling has been performed (YES in step S10), the process proceeds to step S11.

[0043] In step S11, the control device 20 executes exhaust flow rate control using the throttle valve 18. If refueling has occurred, the fuel may have been replaced. This may have also changed the mixture ratio. In such a case, by executing exhaust flow rate control using the throttle valve 18 before the first temperature rise control, the temperature of the exhaust gas flowing to the filter 4 can be raised more quickly. This makes it possible to suppress fuel consumption during the first temperature rise control. After executing the exhaust flow rate control using the throttle valve 18, the control device 20 proceeds to step S12. In step S12, the control device 20 executes the first temperature rise control.

[0044] When the control device 20 executes the first temperature rise control in step S12, the process proceeds to step S9. If the mixture ratio has not changed due to refueling, the control device 20 continues the first temperature rise control. The control device 20 repeatedly executes the processes from step S1 to step S12 at predetermined time intervals.

[0045] As described above, according to the control system 1 of the internal combustion engine 2 of the present disclosure, the optimal exhaust temperature control according to the mixture ratio of biofuel and diesel can be executed by prioritizing either the first temperature control or the second temperature control according to the mixture ratio. This makes it possible to suppress fuel consumption.

[0046] Furthermore, according to the control system 1 for the internal combustion engine 2 of the present disclosure, the higher the mixing ratio of biofuel, the higher the execution priority of the second temperature rise control. In other words, when the mixing ratio of biofuel is low and the ratio of diesel fuel that is easily vaporized is high, the first temperature rise control is higher. This makes it easier to suppress the deterioration of fuel consumption due to regeneration of the filter 4 while also suppressing the decrease in output of the internal combustion engine 2.

[0047] <Other embodiments> Although the embodiment of the present disclosure has been described above, the present disclosure is not limited to the above embodiment, and various modifications are possible without departing from the gist of the invention. In particular, the multiple modifications described in this specification can be arbitrarily combined as necessary.

[0048] (a) In the above embodiment, a diesel engine using the filter 4 has been described as an example, but the present disclosure is not limited thereto. The internal combustion engine 2 may be a gasoline engine. In this case, the internal combustion engine 2 may be an internal combustion engine 2 capable of using bioethanol fuel (an example of a first fuel) and gasoline (an example of a second fuel). In addition, in this case, the filter 4 may be a gasoline particulate filter.

[0049] (b) In the above embodiment, the temperature increase control is performed by supplying fuel to the oxidation catalyst 4a from the fuel injection valve 2c and burning the fuel in the oxidation catalyst 4a to increase the exhaust temperature, but the present disclosure is not limited to this. Fuel may be supplied to the oxidation catalyst 4a by an injection valve other than the fuel injection valve 2c provided upstream of the oxidation catalyst 4a, for example, by providing a separate injection valve in the exhaust pipe.

[0050] (c) In the above embodiment, the control system 1 for the internal combustion engine 2 is applied to a vehicle equipped with a diesel engine, but the present disclosure is not limited to this. For example, the control system 1 for the internal combustion engine 2 may be applied to a plug-in hybrid electric vehicle (PHEV) that can be externally charged or externally powered.

[0051] (d) In the above embodiment, the control device 20 executes the determination control to determine the mixture ratio of biofuel and diesel, and obtains the mixture ratio, but the present disclosure is not limited to this. The control device 20 may obtain the mixture ratio by using the output value of a biofuel mixture ratio sensor that is installed in a fuel system such as the fuel tank 10 or a fuel pipe connected to the fuel tank 10 and is capable of detecting the mixture ratio of biofuel and diesel. [Explanation of symbols]

[0052] 1: Control system 2: Internal combustion engine 2c: Fuel injection valve 4: Filter 14: Turbocharger 18: Throttle valve 20: Control device

Claims

1. A control system for an internal combustion engine capable of using a mixture of a first fuel and a second fuel, A filter that collects particulate matter in the exhaust gas of the internal combustion engine; an injection valve for injecting fuel to be supplied upstream of the filter; a control device that executes a temperature increase control to increase an exhaust temperature upstream of the filter before regenerating the filter; Equipped with The control device, based on a mixing ratio of the first fuel and the second fuel, a first temperature rise control for raising the exhaust temperature by controlling an injection amount by the injection valve of the internal combustion engine, and a second temperature rise control for raising the exhaust temperature by maintaining an injection amount by the injection valve of the internal combustion engine and controlling an exhaust flow rate; the first fuel comprises a biofuel and the second fuel is a fuel different from the biofuel; The control device prioritizes the second temperature rise control as the mixing ratio of the first fuel is higher. Control system for internal combustion engines.

2. a throttle valve for adjusting an amount of intake air supplied to the internal combustion engine; a supercharger that recovers exhaust gas from the internal combustion engine and supercharges the intake air of the internal combustion engine; Further equipped with the control device executes exhaust flow rate control to control an exhaust flow rate of the internal combustion engine by the throttle valve and the turbocharger, During the second temperature rise control, the exhaust flow rate control by the turbocharger is prioritized over the exhaust flow rate control by the throttle valve.

2. The control system for an internal combustion engine according to claim 1.

3. executing the exhaust flow rate control by the throttle valve before the first temperature increase control; 3. The control system for an internal combustion engine according to claim 2.

4. When a mixing ratio of the first fuel and the second fuel is switched, the exhaust flow rate control is executed before the first temperature rise control.

4. The control system for an internal combustion engine according to claim 3.

5. When the internal combustion engine is operated at a load equal to or higher than a predetermined load, the temperature increase control is prohibited.

5. A control system for an internal combustion engine according to claim 1.

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