JP2013189913A - Fuel supply device for internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To quickly provide a proper fuel injection amount when properties in fuel in a fuel tank change for example immediately after fuel refilling.SOLUTION: A fuel supply device includes: a fuel separation means for separating a raw fuel using either a normal fuel not containing oxygen-contained fuel or a mixed fuel in which the oxygen-contained fuel and the normal fuel are mixed into a higher octane fuel and a lower octane fuel. Moreover, the fuel supply device includes a control means for controlling a fuel injection amount based on an output value of an air-fuel ratio sensor obtained in the injection of the raw fuel, an output value of the air-fuel ratio sensor obtained in the injection of the lower octane fuel separated from the raw fuel, and an injection ratio between the higher octane fuel and the lower octane fuel.

Description

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

  Conventionally, using a separator, a raw material fuel can be separated into a high octane number fuel with a high content of high octane number components (high RON fuel) and a low octane number fuel with a low content of high octane number components (low RON fuel). Are known. The high RON fuel has a higher content of high octane components than the raw material fuel. The low RON fuel has a lower content of high octane components than the raw material fuel. A fuel supply apparatus is known that supplies fuel by changing the ratio of the separated high RON fuel and low RON fuel in accordance with the operating state of the internal combustion engine. (For example, refer to Patent Document 1). Thereby, the octane number of the fuel supplied to the internal combustion engine can be adjusted according to the operating state of the internal combustion engine. Further, a technique for estimating the oxygen-containing fuel content in the high RON fuel separated by the separation device in accordance with the output of the air-fuel ratio sensor and correcting the fuel injection amount has been proposed (see, for example, Patent Document 2). ).

Japanese translation of PCT publication No. 2004-522039 JP 2011-241803 A

  By the way, a mixed fuel obtained by mixing an alcohol-containing fuel such as ethanol or methanol or an oxygen-containing fuel such as MTBE with a petroleum-based fuel such as gasoline may be used as a raw material fuel. When a mixed fuel is used as a raw material fuel and separated, the fuel properties such as the octane number and the calorific value of the separated fuel are different from those of a normal fuel composed solely of petroleum fuel. This is because the oxygen-containing fuel is easy to permeate the separation membrane like the aroma component due to the polarity of the oxygen-containing fuel, so that the oxygen-containing fuel contained in the mixed fuel is separated into the high RON fuel. For this reason, the produced high RON fuel contains the oxygen-containing fuel after separation, and the fuel properties greatly change. For this reason, this high RON fuel contains a large amount of oxygen-containing fuel, and when the fuel injection amount is the same as that of normal fuel, the exhaust air-fuel ratio shifts to the lean air-fuel ratio side. On the other hand, it is conceivable to adjust the exhaust air-fuel ratio by feedback control with an air-fuel ratio sensor, but the supply ratio of high RON fuel is changed according to the operating state of the internal combustion engine, and the oxygen-containing fuel amount with respect to the total supply amount The ratio of will change sequentially. Therefore, even if the exhaust air-fuel ratio is adjusted by feedback control with the air-fuel ratio sensor, it is a follow-up adjustment, and it is difficult to adjust the exhaust air-fuel ratio to the target air-fuel ratio. In order to adjust the exhaust air-fuel ratio to the target air-fuel ratio, it is necessary to calculate the oxygen-containing fuel content contained in the high RON fuel and correct the fuel injection amount according to the calculated oxygen-containing fuel content . The fuel supply device disclosed in Patent Document 2 corrects the fuel injection amount in accordance with the oxygen-containing fuel content of the high RON fuel. For example, the property of the fuel to be supplied is different for each fuel supply. Can be considered. When the fuel properties differ for each refueling, the fuel property determination based on the output value of the air-fuel ratio sensor immediately after refueling may vary.

  Therefore, an object of the fuel supply device for an internal combustion engine disclosed in the present specification is to immediately realize an appropriate fuel injection amount when the property of the fuel in the fuel tank changes, such as immediately after refueling.

  In order to solve the above problems, the fuel supply device for an internal combustion engine disclosed in this specification uses either a normal fuel that does not contain oxygen-containing fuel, or a mixed fuel that is a mixture of oxygen-containing fuel and normal fuel. The fuel separation means for separating the raw material fuel into the high octane fuel and the low octane fuel, the output value of the air-fuel ratio sensor obtained at the time of the raw fuel injection, and the injection of the low octane fuel separated from the raw fuel Control means for controlling the fuel injection amount based on the obtained output value of the air-fuel ratio sensor and the injection ratio of the high octane fuel and the low octane fuel.

  It has been found that the raw material fuel separated by the fuel separation means is separated into a high octane fuel (high RON fuel) and a low octane fuel (low RON fuel) at a substantially constant rate each time. It is also known that almost all the oxygen-containing fuel is separated to the high RON fuel side. That is, the oxygen-containing fuel is not included on the low RON fuel side after separation. For this reason, by performing a calculation based on the output value of the air-fuel ratio sensor acquired at the time of injection of the low RON fuel that does not contain oxygen-containing fuel, the fuel injection amount that provides an appropriate air-fuel ratio is determined. be able to.

  The control means compares the output value of the air-fuel ratio sensor acquired when the raw fuel is injected with the output value of the air-fuel ratio sensor acquired when the low-octane fuel separated from the raw fuel is injected, and The oxygen-containing fuel content rate in the raw fuel can be calculated, and the increase rate of the raw fuel can be calculated based on the oxygen-containing fuel content rate in the raw fuel and reflected in the fuel injection amount.

  As described above, it is known that the low RON fuel side after separation is in a state in which no oxygen-containing fuel is contained. Therefore, based on the output value of the air-fuel ratio sensor acquired at the time of injection of the low RON fuel not containing oxygen-containing fuel, the output value of the air-fuel ratio sensor acquired at the time of injection of the low RON fuel and the raw fuel By comparing the output value of the air-fuel ratio sensor acquired at the time of injection, the oxygen-containing fuel content in the raw fuel can be calculated. By calculating the increase ratio when only the raw material fuel is injected based on the calculated oxygen-containing fuel content in the raw material fuel, an appropriate air-fuel ratio can be obtained when only the raw material fuel is injected.

  The control means includes an output value of an air-fuel ratio sensor acquired when the high-octane fuel separated from the raw fuel is injected, and an air-fuel ratio sensor acquired when the low-octane fuel separated from the raw fuel is injected. Compare the output value and calculate the increase ratio of the high octane fuel based on the injection ratio of the high octane fuel and the low octane fuel at the time of the injection of the high octane fuel and reflect it in the fuel injection amount Can do.

  As described above, it is known that the low RON fuel side after separation is in a state in which no oxygen-containing fuel is contained. Therefore, based on the output value of the air-fuel ratio sensor acquired at the time of injection of the low RON fuel not containing oxygen-containing fuel, the output value of the air-fuel ratio sensor acquired at the time of injection of the low RON fuel and the low RON The oxygen-containing fuel content in the high RON fuel can be calculated by comparing the output value of the air-fuel ratio sensor acquired during the injection of the high RON fuel whose injection ratio with the fuel is known. Based on the oxygen-containing fuel content ratio in the calculated high RON fuel, if an increase ratio at the time of injecting the high RON fuel is calculated, an appropriate air-fuel ratio can be obtained when the high RON fuel is injected.

  According to the fuel supply device for an internal combustion engine disclosed in this specification, an appropriate fuel injection amount can be immediately realized when the property of the fuel in the fuel tank changes.

FIG. 1 is an explanatory diagram showing a schematic configuration of an internal combustion engine to which a fuel supply device of an embodiment is applied. FIG. 2 is a flowchart showing an example of control of the fuel supply apparatus of the embodiment. 3A to 3C are explanatory views showing the properties of the fuel after passing through the separator.

  DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments for carrying out the present invention will be described in detail with reference to the drawings. However, in the drawings, the dimensions, ratios, and the like of each part may not be shown so as to completely match the actual ones.

  FIG. 1 is an explanatory diagram showing a schematic configuration of an internal combustion engine 100 to which a fuel supply device (hereinafter simply referred to as “fuel supply device”) 1 of an internal combustion engine disclosed in this specification is applied. The internal combustion engine 1 includes a fuel tank 2 that stores fuel for operating the internal combustion engine 1. In the fuel tank 2, raw material fuel is stored. Here, the raw material fuel is, for example, a 90 RON normal fuel such as gasoline (ordinary fuel), an alcohol such as ethanol or methanol, or an oxygen-containing fuel such as MTBE as a petroleum fuel (ordinary fuel) such as gasoline. It may be a mixed fuel mixture. In the present embodiment, it is assumed that only gasoline or a mixed fuel in which gasoline and ethanol are mixed is supplied. However, the content of ethanol supplied is not always constant, and the ethanol content (oxygen-containing fuel content) in the raw fuel varies. In particular, when fuels having different properties are supplied, the ethanol content may change greatly. In the following description, the ethanol content indicating the amount of ethanol relative to the total fuel amount is indicated by En (n is a number indicating the ethanol content as a percentage). For example, when the ethanol content is 10%, it is expressed as E10, and when the ethanol content is 5%, it is expressed as E5.

  In the fuel tank 2, a fuel pump P1 is disposed. The raw material fuel in the fuel tank 2 is sent out to the first fuel pipe 3 by the fuel pump P1. A flow control valve 4 is provided in the middle of the first fuel pipe 3. The flow control valve 4 adjusts the flow rate of the raw fuel flowing through the first fuel pipe 3. The raw material fuel is boosted to a predetermined pressure by the fuel pump P1 and the flow control valve 4. Further, the first fuel pipe 3 branches from the flow control valve 4 to the second fuel pipe 5.

  A heat pipe 6 is provided on the downstream side of the flow rate control valve 4 of the first fuel pipe 3. The heat pipe 6 heats the raw material fuel with a medium that has received the heat of the exhaust gas flowing through the exhaust passage 7 of the internal combustion engine 1. The pressurized raw material fuel is heated to a predetermined temperature by the heat pipe 6.

  A temperature sensor 8 is disposed between the flow control valve 4 and the heat pipe 6 on the first fuel pipe 3. The temperature sensor 8 acquires the temperature of the raw material fuel.

  The first fuel pipe 3 is connected to the separator 9 on the downstream side of the heat pipe 4. The separator 9 separates the heated raw material fuel into a high RON fuel (high octane number fuel) and a low RON fuel (low octane number fuel). The separator 9 divides the container with an aroma separation membrane 10 to form a first compartment 11 and a second compartment 12. The aroma separation membrane 10 has a property of selectively permeating aromatic components in the raw material fuel. The second section 12 becomes negative pressure by the action of the inductor 13. For this reason, part of the high-temperature and high-pressure raw material fuel that has flowed into the separator 9 passes through the aroma separation membrane 10 and moves to the second compartment 12 side. The fuel that has moved to the second section 12 side has a large amount of aromatic components and becomes a high RON fuel. On the other hand, the fuel that does not permeate the aroma separation membrane 10 has a small amount of aromatic components and is a low RON fuel.

  The first section 11 in which the fuel in the separator 9 does not permeate the aroma separation membrane 10 is connected to the third fuel pipe 14. The third fuel pipe 14 merges with the second fuel pipe 5. The second section 12 through which the fuel in the separator 9 permeates the aroma separation membrane 10 is connected to the fourth fuel pipe 15. The separator 9 corresponds to fuel separation means.

  A first fuel cooler 16 is disposed on the downstream side of the junction of the second fuel pipe 5 and the third fuel pipe 14. A second fuel cooler 17 is disposed in the fourth fuel pipe 15. The first fuel cooler 16 and the second fuel cooler 17 respectively cool each fuel by exchanging heat with the outside air. The second fuel pipe 5 is connected to the injector 18 on the downstream side of the first fuel cooler 16. The injector 18 injects fuel within the internal combustion engine 100. The fourth fuel pipe 15 is connected to the inductor 13 downstream of the second fuel cooler 12. The idactor 13 can make the inside of the second section 12 have a negative pressure as described above. A downstream side of the inductor 13 is connected to a high RON fuel tank 19. In the high RON fuel tank 19, a remaining amount sensor 20 for detecting the remaining amount of the stored high RON fuel is disposed. The high RON fuel in the high RON fuel tank 14 is pumped up by the fuel pump P <b> 2 and supplied to the injector 21 in the internal combustion engine 100.

  The internal combustion engine 100 includes an electronic control unit (hereinafter referred to as ECU) 22 for controlling the internal combustion engine 100. The ECU 22 controls the operation state of the internal combustion engine 100 according to the operation conditions of the internal combustion engine 100 and the request of the driver. In addition to the above-described remaining amount sensor 20, the ECU 22 includes an air-fuel ratio sensor 23, a crank position sensor 24, and an accelerator position that are disposed in the exhaust passage 7 of the internal combustion engine 100 and detect the exhaust air-fuel ratio of the exhaust discharged from the internal combustion engine 100. Various sensors such as the sensor 25 are connected via electric wiring. Further, the temperature sensor 8 is electrically connected to the ECU 22. Output signals from these various sensors are input to the ECU 22. On the other hand, the ECU 17 is connected to the flow control valve 4, the inductor 17, and the injectors 18 and 21 through electric wiring, and these devices are controlled by the ECU 22.

  The ECU 22 changes the injection ratio of the high RON fuel and the low RON fuel injected from the injectors 18 and 21 in the internal combustion engine 100 to the intake port according to the operating state. The ECU 22 corresponds to control means. The ECU 22 outputs the output value of the air-fuel ratio sensor 23 acquired at the time of injection of the raw material fuel, the output value of the air-fuel ratio sensor 23 acquired at the time of injection of the low RON fuel separated from the raw material fuel, the high RON fuel and the low RON fuel, The fuel injection amount is controlled based on the injection ratio.

  Next, an example of the control of the fuel supply apparatus 1 will be described with reference to FIG. The fuel supply device 1 is controlled mainly by the ECU 22.

  First, in step S1, it is determined whether or not the air-fuel ratio sensor (A / F sensor) 23 is in an ON state. Here, since the air-fuel ratio sensor 23 does not output unless the exhaust gas temperature becomes equal to or higher than a predetermined value, it is used as a guideline for determining whether or not the internal combustion engine 100 has been warmed up based on whether there is an output from the air-fuel ratio sensor 23 or not. be able to. When the exhaust temperature of the internal combustion engine 100 becomes equal to or higher than a predetermined value, the raw material fuel is heated through the heat pipe 6 and separated into high RON fuel and low RON fuel in the separator 9. The process of step S1 is repeated until a Yes determination is made. When it is determined Yes in step S1, the process proceeds to step S2. In step S2, it is determined whether the temperature Tf of the raw material fuel acquired by the temperature sensor 8 is lower than a predetermined threshold value Tf0. The threshold value Tf0 is a value serving as a reference as to whether or not the flow rate of the raw material fuel to the separator 9 side is set to 0 (FC = 0) by controlling the flow rate control valve 4. If the raw material fuel is excessively heated and FC = 0, there is a risk of fuel coking. Therefore, the threshold value Tf0 is set to a temperature with a margin to avoid fuel coking.

  When it is determined Yes in step S2, the process proceeds to step S3. In step S3, the flow control valve 4 is controlled so that FC = 0. That is, the inflow of the raw material fuel to the separator 9 side is stopped, and the raw material fuel is circulated to the second fuel pipe 5 side. In the subsequent step S4, the fuel in the fuel tank 2, that is, the oxygen-containing fuel content (ethanol content; En) of the raw material fuel is calculated. Specifically, the output value AF-R of the air-fuel ratio sensor 23 acquired at the time of injection of raw material fuel is compared with the output value AF-L of the air-fuel ratio sensor 23 acquired at the time of injection of low RON fuel. The calculation here is performed based on the knowledge that ethanol, which is an oxygen-containing fuel, is not mixed in the low RON fuel. That is, assuming that the low RON fuel is E0, the ethanol content in the raw fuel can be obtained by analyzing the output value AF-R with reference to the output value AF-L at this time.

  When the ethanol content in the raw material fuel is thus calculated, the oxygen-containing fuel content of the high RON fuel, that is, the ethanol content can be calculated in the subsequent step S5. Here, calculation of the ethanol content of the high RON fuel will be described with reference to FIGS. 3A to 3C are explanatory views showing the properties of the fuel after passing through the separator 9.

  It is known that when the separator 9 is operated under predetermined conditions, the raw material fuel separated by the separator 9 is separated into a high RON fuel and a low RON fuel at a substantially constant rate each time. For example, when the raw material fuel is supplied to the separator 9 when the ethanol content of the raw material fuel is 0% as shown in FIG. 3A, 80% of the supplied raw material fuel is discharged as a low RON fuel, The remaining 20% is discharged as high RON fuel. At this time, since the ethanol content of the original raw material fuel is 0%, both the low RON fuel and the high RON fuel have an ethanol content of 0 percent (E0). At this time, if the raw material fuel is 90 RON, for example, the low RON fuel is 88 RON and the high RON fuel is 100 RON.

  When the raw material fuel is supplied to the separator 9 when the ethanol content of the raw material fuel is 5% (E5) as shown in FIG. 3B, 80% of the supplied raw material fuel is discharged as a low RON fuel. The remaining 20% is discharged as high RON fuel. That is, when the same separator 9 is used, the low RON fuel and the high RON fuel are separated at substantially the same ratio regardless of the difference in the ethanol content of the raw material fuel. Further, it has been found that almost all ethanol contained in the raw material fuel is separated to the high RON fuel side. At this time, since the ethanol content of the original raw material fuel is 5%, the ethanol content of the high RON fuel is 25% (E25). On the other hand, since the ethanol content is hardly separated on the low RON fuel side, the ethanol content of the low RON fuel is almost 0% (E0). At this time, if the raw material fuel is 91 RON, for example, the low RON fuel is 88 RON, and the high RON fuel is 102 RON.

  When the raw material fuel is supplied to the separator 9 when the ethanol content of the raw material fuel is 10% (E10) as shown in FIG. 3C, as in the above two cases, 80% is discharged as low RON fuel and the remaining 20% is discharged as high RON fuel. That is, when the same separator 9 is used, the low RON fuel and the high RON fuel are separated at substantially the same ratio regardless of the difference in the ethanol content of the raw material fuel. Further, the ethanol content contained in the raw fuel is almost entirely separated to the high RON fuel side. At this time, since the ethanol content of the original raw material fuel is 10%, the ethanol content of the high RON fuel is 50% (E50). On the other hand, since the ethanol content is hardly separated on the low RON fuel side, the ethanol content of the low RON fuel is almost 0% (E0). At this time, if the raw material fuel is 92 RON, for example, the low RON fuel is 88 RON and the high RON fuel is 104 RON.

  Here, it should be noted that when the raw material fuel is supplied to the separator 9, almost all of the ethanol content in the raw material fuel is separated to the high RON fuel side and not to the low RON fuel side. For this reason, if the ethanol content of the raw fuel can be grasped, the ethanol content of the high RON fuel can be calculated based on the ethanol content of the raw fuel. In the above example, if the raw fuel is E5, the high RON fuel is E25, and if the raw fuel is E10, the high RON fuel is E50.

  After step S4 and step S5, the ethanol content of the raw material fuel and the ethanol content of the high RON fuel are grasped, and then the process proceeds to step S9. The process of step S9 will be described in detail later.

  When it is determined No in step S2, the process proceeds to step S6. In step S6, high RON fuel injection is performed. Whether or not to perform high RON fuel is based on the operating state of the internal combustion engine 100, but high RON fuel injection may be forcibly performed for fuel property determination. In step S7 performed subsequent to step S6, the oxygen-containing fuel content (ethanol content; En) of the high RON fuel is calculated. Specifically, the output value AF-HL of the air-fuel ratio sensor 23 acquired at the time of high RON fuel injection is compared with the output value AF-L of the air-fuel ratio sensor 23 acquired at the time of low RON fuel injection. The calculation here is performed based on the knowledge that ethanol, which is an oxygen-containing fuel, is not mixed in the low RON fuel. That is, assuming that the low RON fuel is E0, the ethanol content in the raw fuel can be acquired by analyzing the output value AF-HL with reference to the output value AF-L at this time. Here, the injection of the high RON fuel is performed together with the injection of the low RON fuel. That is, the case where mixed injection is performed is assumed. The injection ratio between the high RON fuel and the low RON fuel is determined by the ECU 22 according to the operating state of the internal combustion engine. Therefore, at this point, the injection ratio of high RON fuel to low RON fuel is known. Further, as described above, the raw material fuel supplied to the separator 9 is separated into a high RON fuel and a low RON fuel at a certain ratio, and almost the entire amount of ethanol is separated to the high RON fuel side. The From this, the ethanol content of the high RON fuel can be calculated. When the injection ratio of the high RON fuel is 100%, the ethanol value of the high RON fuel is calculated with high accuracy by comparing the output value AF-H at this time with the output value AF-L. Can do.

  In step S8, which is performed subsequent to step S7, the ethanol content of the raw fuel (fuel in the fuel tank) is calculated based on the ethanol content of the high RON fuel. Since the fuel separated by the separator 9 has the above-described relationship, if the ethanol content of the high RON fuel can be grasped, the ethanol content of the raw fuel can be determined based on the ethanol content of the high RON fuel. Can be calculated. In the above example, if the high RON fuel is E25, the raw fuel is E5, and if the high RON fuel is E50, the raw fuel is E10.

  After step S7 and step S8, the ethanol content of the raw material fuel and the ethanol content of the high RON fuel are grasped, and then the process proceeds to step S9.

  In step S9, the raw material fuel increase ratio (increase 1) and the high RON fuel increase ratio (increase 2) are determined. The fuel containing ethanol shifts the air-fuel ratio to the lean side because ethanol is an oxygen-containing fuel. That is, the amount of fuel is insufficient. Therefore, the fuel increase corresponding to the ethanol content is brought close to stoichiometry. When the raw material fuel is E10 and the high RON fuel is E50, the increase amount 1 is set to 3.4% and the increase amount 2 is set to 20%.

  In step S10, it is determined whether or not FC = 0, that is, whether or not fuel is supplied to the separator 9 side by the flow rate control valve 4. When it is determined Yes in step S10, that is, when the raw material fuel is supplied for injection, the process proceeds to step S11, and increase 1 and increase 2 are executed. On the other hand, when it is determined No in step S10, since only the raw material fuel is not injected, the increase 1 is avoided and the increase 2 is executed in step S12. Thus, the calculated increase rate of the raw material fuel and the increase rate of the high RON fuel are reflected in the fuel injection amount. Note that an increase in low RON fuel is not necessary. This is because the low RON fuel does not contain ethanol, which is an oxygen-containing fuel, and it is considered that the air-fuel ratio shift to the lean side due to the injection of the low RON fuel does not occur.

  As described above, according to the fuel supply device 1 of the embodiment, the ethanol content of the raw fuel and the high RON fuel are obtained based on the output value of the air-fuel ratio sensor acquired at the time of low RON fuel injection that can be set to E0. The ethanol content can be grasped. Thereby, when the property of the fuel in the fuel tank changes due to refueling or the like, an appropriate fuel injection amount can be immediately realized.

  The above embodiments are merely examples for carrying out the present invention. Therefore, the present invention is not limited to these, and various modifications and changes can be made within the scope of the gist of the present invention described in the claims.

DESCRIPTION OF SYMBOLS 1 Fuel supply apparatus 2 Fuel tank 3 1st fuel piping 4 Flow control valve 5 2nd fuel piping 6 Heat pipe 7 Exhaust passage 8 Temperature sensor 9 Separator 10 Aroma separation membrane 17 Eductor 22 ECU
23 Air-fuel ratio sensor P1, P2 Fuel pump

Claims (3)

A fuel separation means for separating a raw fuel using one of a normal fuel not containing oxygen-containing fuel and a mixed fuel obtained by mixing oxygen-containing fuel and normal fuel into a high-octane fuel and a low-octane fuel; ,
The output value of the air-fuel ratio sensor acquired at the time of injection of the raw fuel, the output value of the air-fuel ratio sensor acquired at the time of injection of the low-octane fuel separated from the raw fuel, and the high-octane fuel and the low-octane fuel Control means for controlling the fuel injection amount based on the injection ratio;
A fuel supply device for an internal combustion engine.   The control means compares the output value of the air-fuel ratio sensor acquired when the raw fuel is injected with the output value of the air-fuel ratio sensor acquired when the low-octane fuel separated from the raw fuel is injected, and The internal combustion engine according to claim 1, wherein an oxygen-containing fuel content rate in the raw material fuel is calculated, and an increase rate of the raw material fuel is calculated based on the oxygen-containing fuel content rate in the raw material fuel and reflected in the fuel injection amount. Fuel supply system.   The control means includes an output value of an air-fuel ratio sensor acquired when the high-octane fuel separated from the raw fuel is injected, and an air-fuel ratio sensor acquired when the low-octane fuel separated from the raw fuel is injected. The output value is compared, and based on the injection ratio between the high octane fuel and the low octane fuel when the high octane fuel is injected, the increase ratio of the high octane fuel is calculated and reflected in the fuel injection amount Item 3. A fuel supply device for an internal combustion engine according to Item 1 or 2.

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