JP2011247204A - Fuel supply control apparatus for internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a technique for accurately calculating a content rate of an oxygen-containing fuel in a fuel supply control apparatus for an internal combustion engine when the oxygen-containing fuel is included in a higher octane fuel.SOLUTION: Based on the fact that a temperature rise rate in a constant flow rate is different in whether a material fuel is a normal one or a mixed one, the technique calculates the difference of the temperature rise rate (S102) by comparing the temperature rise rate of the material fuel when the material fuel is heated in a heat pipe in the constant flow rate, with the predetermined temperature rise rate of the material fuel under the same condition, and calculates the content rate of the oxygen-containing fuel (S103) by obtaining the difference in the determined temperature rise rate and the difference in the temperature rise rate calculated in a map of the relation with the content rate of the oxygen-containing fuel.

Description

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

  Separating raw material fuel into high octane fuel with higher content of high octane component than raw fuel and low octane fuel with lower content of high octane component than raw fuel, depending on the operating condition of the internal combustion engine A technique for supplying fuel by changing the ratio of a high-octane fuel and a low-octane fuel is disclosed (for example, see 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. Therefore, in the high load region, the torque is increased using a high octane fuel, and in the low load region, knocking is suppressed using a low octane fuel.

Japanese translation of PCT publication No. 2004-522039 JP 2009-024551 A JP 2009-04-7008 A

  By the way, the use of a mixed fuel obtained by mixing an alcohol-containing fuel such as ethanol or methanol or an oxygen-containing fuel such as MTBE into a petroleum-based fuel such as gasoline has been studied. When the mixed fuel is used as the raw material fuel, the fuel properties such as the octane number and the calorific value of the separated fuel are different from the case of using the normal fuel only of the petroleum-based fuel. This is because the oxygen-containing fuel is easy to permeate the separation membrane in the same manner as 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-octane fuel. For this reason, the produced | generated high octane fuel contains the oxygen-containing fuel after isolation | separation, and a fuel property will change a lot. Therefore, when this high octane fuel is used, it contains a large amount of oxygen-containing fuel, so even if it is supplied in the same amount as when separated from 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. However, since the supply ratio of the high-octane fuel is changed according to the operating state of the internal combustion engine, the ratio of the oxygen-containing fuel amount to the total supply amount changes 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 rate contained in the high-octane fuel and correct the fuel supply amount according to the calculated oxygen-containing fuel content rate .

  The present invention has been made in view of the above problems, and an object of the present invention is to accurately determine the oxygen-containing fuel content rate in a fuel supply control device for an internal combustion engine when the oxygen-containing fuel is contained in the high-octane fuel. It is to provide a technique for calculating the above.

In the present invention, the following configuration is adopted. That is, the present invention
A raw material fuel that uses either a normal fuel that does not contain oxygenated fuel or a mixed fuel that is a mixture of oxygenated fuel and normal fuel has a higher octane component content than the raw fuel. A fuel separation means for separating into a high octane fuel containing oxygen fuel and a low octane fuel with a low content of high octane components than the raw fuel,
Fuel supply means for supplying fuel by changing the ratio of the high-octane fuel and the low-octane fuel supplied to the internal combustion engine according to the operating state of the internal combustion engine according to the basic map;
A fuel supply control device for an internal combustion engine comprising:
Heating means for heating the raw fuel before separating the raw fuel by the fuel separation means;
Taking advantage of the difference in physical properties between the case where the raw material fuel is a normal fuel and the case where the raw material fuel is a mixed fuel, the change in the raw material fuel when the raw material fuel is heated by the heating means is determined in advance under the same conditions. By calculating the physical quantity related to the difference in physical properties compared to the change in normal fuel, and incorporating the calculated physical quantity into the map of the relationship between the predetermined physical quantity and the oxygen-containing fuel content, A fuel supply control device for an internal combustion engine, comprising content rate calculating means for calculating an oxygen fuel content rate.

  When the raw material fuel is normal fuel and when the raw material fuel is a mixed fuel, the physical properties are different, so when the raw material fuel is heated by the heating means, the difference in physical properties due to the oxygen-containing fuel content in the raw material fuel changes the raw material fuel Appears as Therefore, the physical quantity related to the difference in physical properties is calculated by comparing the change in the raw fuel when the raw fuel is heated by the heating means with the change in the normal fuel determined in advance under the same conditions. The oxygen-containing fuel content is calculated by taking the calculated physical quantity into the map of the relationship between the physical quantity and the oxygen-containing fuel content. According to this, it is possible to accurately calculate the oxygen-containing fuel content of the high-octane fuel. Accordingly, since the fuel supply amount can be corrected according to the oxygen-containing fuel content rate calculated accurately, the supply ratio of the high octane fuel is changed according to the operating state of the internal combustion engine, and the fuel supply amount is included in the total fuel supply amount. Even if the ratio of the amount of oxygen fuel changes sequentially, the exhaust air-fuel ratio can be adjusted to the target air-fuel ratio, and the exhaust air-fuel ratio can be prevented from shifting to the lean air-fuel ratio side.

  The content rate calculating means uses the heating means at a constant flow rate by utilizing the fact that the amount of temperature rise at a constant flow rate differs between when the raw material fuel is normal fuel and when the raw material fuel is a mixed fuel. The temperature rise amount of the raw material fuel when the raw material fuel is heated is compared with the temperature rise amount of the normal fuel determined in advance under the same condition to calculate the difference in the temperature rise amount. It is preferable to calculate the oxygen-containing fuel content rate by taking in the difference in the temperature increase calculated in the map of the relationship between the difference and the oxygen-containing fuel content rate.

  When the raw material fuel is normal fuel and when the raw material fuel is a mixed fuel, the amount of increase in temperature at a constant flow rate is different. Therefore, when the raw material fuel is heated by the heating means, it is constant depending on the oxygen-containing fuel content in the raw material fuel. The difference in the temperature rise amount in the flow rate appears in the temperature rise amount. Therefore, the difference in temperature rise is calculated by comparing the temperature rise of the raw material fuel when the raw fuel is heated with heating means at a constant flow rate with the temperature rise amount of the normal fuel determined in advance under the same conditions. Then, the oxygen-containing fuel content rate is calculated by taking the difference in the calculated temperature increase amount into the map of the relationship between the predetermined temperature increase amount and the oxygen-containing fuel content rate. According to this, it is possible to accurately calculate the oxygen-containing fuel content of the high-octane fuel.

  The content rate calculation means heats the raw material fuel to the target temperature with the heating means by utilizing the fact that the flow rate at a constant temperature differs between the case where the raw material fuel is a normal fuel and the case where the raw material fuel is a mixed fuel. The flow rate of the raw material fuel is compared with the predetermined normal fuel flow rate under the same conditions to calculate the flow rate difference, and the map of the relationship between the predetermined flow rate difference and the oxygen-containing fuel content rate It is preferable to calculate the oxygen-containing fuel content by taking in the difference between the calculated flow rates.

Since the flow rate at a constant temperature is different between the case where the raw material fuel is a normal fuel and the case where the raw material fuel is a mixed fuel, when the raw material fuel is heated by the heating means, the flow rate is constant due to the oxygen-containing fuel content in the raw material fuel. The difference in flow rate appears in the flow rate. Therefore, the flow rate of the raw material fuel when the raw material fuel is heated by the heating means at a constant temperature is calculated in advance by comparing the flow rate of the raw material fuel with the predetermined normal fuel flow rate under the same conditions. The oxygen-containing fuel content is calculated by taking the calculated flow-rate difference into the map of the relationship between the flow rate difference and the oxygen-containing fuel content. According to this, it is possible to accurately calculate the oxygen-containing fuel content of the high-octane fuel.

  The content rate calculating means uses the fact that the heat transfer rate with respect to the heat transfer amount supplied from the heating means to the raw material fuel is different between the case where the raw material fuel is a normal fuel and the case where the raw material fuel is a mixed fuel, The amount of heat transfer calculated by multiplying the temperature rise of the raw material fuel when the raw material fuel is heated by the heating means, the flow rate, and the heat transfer coefficient is approximately the same as the heat transfer amount of normal fuel determined in advance under the same conditions. Therefore, by calculating the heat transfer rate of the raw material fuel and incorporating the heat transfer rate of the raw material fuel into the map of the relationship between the predetermined heat transfer rate and the oxygenated fuel content rate, the oxygen-containing fuel content rate is calculated. It is good to calculate.

  When the raw material fuel is a normal fuel and when the raw material fuel is a mixed fuel, the heat transfer rate for the amount of heat transferred from the heating means to the raw fuel is different. The difference in the heat transfer rate with respect to the heat transfer amount due to the oxygen-containing fuel content rate appears in the heat transfer rate. Therefore, the amount of heat transfer calculated by multiplying the temperature rise of the raw material fuel when the raw material fuel is heated by the heating means, the flow rate, and the heat transfer coefficient, and the heat transfer amount of the normal fuel determined in advance under the same conditions are approximately. Therefore, by calculating the heat transfer rate of the raw material fuel and incorporating the heat transfer rate of the raw material fuel into the predetermined relationship between the heat transfer rate and the oxygenated fuel content rate, Calculate the rate. According to this, it is possible to accurately calculate the oxygen-containing fuel content of the high-octane fuel.

A high-octane fuel tank for storing the high-octane fuel separated by the fuel separation means;
A remaining amount detecting means for detecting the remaining amount of the high octane fuel in the high octane fuel tank;
The oxygen-containing fuel content in the high-octane fuel remaining in the high-octane fuel tank, the residual amount of the high-octane fuel remaining in the high-octane fuel tank detected by the remaining amount detection means, An inflow amount of high octane fuel flowing into the octane fuel tank, an oxygen content fuel content of the high octane fuel flowing into the high octane fuel tank, and the oxygen content content calculated by the content calculator; Fuel increasing means for increasing the amount of fuel supplied to the basic map according to the oxygen-containing fuel content in the high-octane fuel in the high-octane fuel tank calculated based on
May be further provided. According to this, the fuel supply amount can be increased and corrected according to the accurately calculated oxygen-containing fuel content in the high-octane fuel in the high-octane fuel tank, so that the high-octane fuel can be adjusted according to the operating state of the internal combustion engine. Even if the ratio of the oxygen-containing fuel amount to the total supply amount changes sequentially, the exhaust air-fuel ratio can be adjusted to the target air-fuel ratio, and the exhaust air-fuel ratio shifts to the lean air-fuel ratio side. Can be suppressed.

  According to the oxygen-containing fuel content rate calculated by the content rate calculating means, the fuel increasing means has the same ratio as the ratio of the high octane fuel and the low octane fuel of the basic map to the basic map. The supply amount should be increased. According to this, the amount of fuel supplied by the correction is the same as the ratio of the high octane number fuel and the low octane number fuel in the basic map, so the octane number of the fuel supplied after the correction is changed to the operating state of the internal combustion engine. The optimum octane number can be maintained.

  According to the present invention, in the fuel supply control device for an internal combustion engine, when the high-octane fuel contains oxygen-containing fuel, the oxygen-containing fuel content can be accurately calculated.

1 is a diagram illustrating a schematic configuration of an internal combustion engine according to Embodiment 1 of the present invention. It is a figure which shows the relationship between the driving | running state of the internal combustion engine of a basic map which concerns on Example 1, and a request | requirement octane number. It is a figure which shows the relationship between the engine load of the internal combustion engine of the basic map which concerns on Example 1, and fuel injection quantity. It is a figure which shows the relationship between the driving | running state of the internal combustion engine which concerns on Example 1, and the temperature rise amount of a normal fuel. It is a figure which shows the relationship between the difference of the temperature rise which concerns on Example 1, and oxygen-containing fuel content rate. 3 is a flowchart illustrating a fuel supply control routine according to the first embodiment. It is a figure which shows the relationship between the oxygen-containing fuel content rate of the high RON fuel which concerns on Example 1, and the fuel for an increase correction. It is a figure which shows the relationship between the engine load of the internal combustion engine which concerns on Example 1, and the fuel injection quantity by which increase correction was carried out.

  Specific examples of the present invention will be described below.

<Example 1>
FIG. 1 is a diagram illustrating a schematic configuration of an internal combustion engine to which a fuel supply control device for an internal combustion engine according to a first embodiment of the present invention is applied. The internal combustion engine 1 shown in FIG. 1 is provided with a fuel tank 2 that stores fuel for operating the internal combustion engine 1. The fuel tank 2 stores the refueled raw material fuel. Here, the raw material fuel is, for example, a petroleum fuel (ordinary fuel) such as 90 RON normal gasoline or the like, or a mixed fuel obtained by mixing an oxygen-containing fuel such as ethanol or alcohol such as ethanol or methanol or MTBE into a petroleum fuel such as gasoline. It is. The raw material fuel in the fuel tank 2 is sent to the raw material fuel pipe by the fuel pump P in the fuel tank 2. A flow control valve 3 is provided in the middle of the raw material fuel pipe. The flow rate control valve 3 adjusts the flow rate of the raw material fuel flowing through the raw material fuel pipe. The raw material fuel is boosted to a predetermined pressure by the fuel pump P and the flow rate control valve 3. A heat pipe 4 is provided in the raw material fuel pipe downstream of the flow rate control valve 3. The heat pipe 4 heats the raw material fuel with a medium that has received the heat of the exhaust gas flowing through the exhaust passage 5 of the internal combustion engine 1. The pressurized raw material fuel is heated to a predetermined temperature by the heat pipe 4. The heat pipe 4 corresponds to the heating means of the present invention. A temperature sensor 6 is provided in the raw material fuel pipe downstream of the heat pipe 4. The temperature sensor 6 detects the temperature of the raw material fuel heated by the heat pipe 4.

  The raw material fuel pipe is connected to the separator 7 on the downstream side of the temperature sensor 6. The separator 7 divides the heated raw material fuel into a high RON fuel having a high octane number component (for example, 103 RON) higher than that of the raw material fuel, and a low RON fuel having a high octane number component (for example, 88 RON) (low octane number) Fuel). The separator 7 divides the container with an aroma separation membrane 8 to form two compartments 9 and 10. The aroma separation membrane 8 has a property of selectively permeating aromatic components in the raw material fuel. When the high-temperature and high-pressure raw material fuel that has flowed into the separator 7 permeates the aroma separation membrane 8 toward the compartment 10 that has become negative due to the action of the inductor 11, the amount of aromatic components increases and becomes high RON fuel. On the other hand, when it does not permeate the aroma separation membrane 8, the amount of aromatic components is small and the fuel is low RON. The section 9 in which the fuel in the separator 7 does not permeate the aroma separation membrane 8 is connected to a low RON fuel pipe. The section 10 through which the fuel in the separator 7 permeates the aroma separation membrane 8 is connected to a high RON fuel pipe. The separator 7 in this embodiment corresponds to the fuel separation means of the present invention.

In the middle of the low RON fuel pipe and the high RON fuel pipe, fuel coolers 12 and 13 for cooling each fuel are arranged. The fuel coolers 12 and 13 cool each fuel by exchanging heat with the outside air. A low RON fuel pipe downstream of the fuel cooler 12 is connected to an injector 14 in the internal combustion engine 1. The high RON fuel pipe downstream of the fuel cooler 13 is provided with an inductor 11 that generates a negative pressure in the section 10 connected to the high RON fuel pipe. The high RON fuel pipe downstream of the inductor 11 is connected to the high RON fuel tank 15. The high RON fuel tank 15 corresponds to the high octane fuel tank of the present invention. In the high RON fuel tank 15, a remaining amount sensor 16 for detecting the remaining amount of the stored high RON fuel is disposed. The remaining amount sensor 16 corresponds to the remaining amount detecting means of the present invention. The high RON fuel in the high RON fuel tank 15 is pumped up by the fuel pump P and supplied to the injector 17 in the internal combustion engine 1.

The internal combustion engine 1 configured as described above is provided with an electronic control unit (hereinafter referred to as ECU) 18 for controlling the internal combustion engine 1. EC
U18 is a unit that controls the operating state of the internal combustion engine 1 in accordance with the operating conditions of the internal combustion engine 1 and the demands of the driver. In addition to the temperature sensor 6 and the remaining amount sensor 16 described above, various sensors such as a crank position sensor 20 and an accelerator position sensor 21 are connected to the ECU 18 through electric wiring, and output signals of these various sensors are input to the ECU 18. It has become so. On the other hand, the ECU 18 is connected with the flow control valve 3, the inductor 11, and the injectors 14 and 17 through electric wiring, and these devices are controlled by the ECU 18.

  The ECU 18 changes the ratio of the high RON fuel and the low RON fuel injected from the respective injectors 14 and 17 in the internal combustion engine 1 to the intake port according to the operating state. FIG. 2 is a diagram showing the relationship between the operating state of the internal combustion engine 1 and the required octane number of the basic map. A solid line L in FIG. 2 indicates a load line L of the internal combustion engine. When the operating state of the internal combustion engine 1 changes as indicated by the load line L, the required octane number of the internal combustion engine 1 changes. For this reason, the ratio of the injection amount of the high RON fuel and the low RON fuel is determined so that the required octane number is realized. FIG. 3 is a diagram showing the relationship between the engine load of the internal combustion engine 1 and the fuel injection amount in the basic map. As shown in FIG. 3, as the engine load increases, the fuel injection amount increases and the high RON fuel ratio also increases. The relationships shown in FIGS. 2 and 3 are derived in advance through experiments and verifications and stored in the ECU 18 as a basic map. Then, the engine rotation speed detected by the crank position sensor 20 and the engine load detected by the accelerator position sensor 21 are taken into the basic maps of FIGS. 2 and 3, and depending on the operating state of the internal combustion engine 1, high RON fuel and The ratio of the low RON fuel injection amount and the fuel injection amount are determined, and each fuel is injected from each injector 14, 17. The ECU 18 that performs such control corresponds to the fuel supply means of the present invention.

By the way, the high RON fuel and the low RON fuel employed in the above basic map are assumed to use a normal petroleum-based fuel as a raw material fuel. However, in recent years, a mixed fuel may be used as a raw material fuel. When a mixed fuel is used as the raw material fuel, the oxygen-containing fuel contained in the mixed fuel is likely to permeate the aroma separation membrane 8 in the same manner as the aroma component due to its polarity. A large amount of oxygen-containing fuel after separation is contained. Particularly, since the oxygen-containing fuel is contained in the high RON fuel having a smaller amount than the mixed fuel, the oxygen-containing fuel content in the high RON fuel is also increased. When the fuel supply control is performed according to the basic map using the high RON fuel separated from such a mixed fuel, the high RON fuel contains a large amount of oxygen-containing fuel. The exhaust air-fuel ratio detected by the air-fuel ratio sensor disposed in the exhaust passage will shift to the lean air-fuel ratio side. In particular, the exhaust air-fuel ratio shifts to a leaner air-fuel ratio side as it becomes a higher load region where more high RON fuel is used. It is desirable that the exhaust air / fuel ratio be adjusted to a target air / fuel ratio such as stoichiometric for exhaust purification using a three-way catalyst or the like. On the other hand, it is conceivable to adjust the exhaust air-fuel ratio by feedback control using an air-fuel ratio sensor, an O ₂ sensor, or the like. However, as described above, since the supply ratio of the high RON fuel is changed according to the operating state of the internal combustion engine 1, the ratio of the oxygen-containing fuel amount with respect to the total supply amount of the fuel changes sequentially. Therefore, when trying to adjust the exhaust air-fuel ratio by feedback control with the air-fuel ratio sensor, the ratio of the oxygen-containing fuel amount used for feedback is the past, and the current ratio of the oxygen-containing fuel amount is the past May be different from proportion. In this case, even if feedback control is performed by the air-fuel ratio sensor, the adjustment becomes a follow-up adjustment, the exhaust air-fuel ratio deviates from the target air-fuel ratio, 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, the oxygen-containing fuel content rate included in the high RON fuel is calculated in advance, and the fuel supply amount is increased and corrected as the calculated oxygen-containing fuel content rate increases. There is a need.

  Therefore, in the present embodiment, the heat pipe 4 at a constant flow rate is used by utilizing the fact that the temperature rise amount at a constant flow rate is different between when the raw material fuel is a normal fuel and when the raw material fuel is a mixed fuel. The temperature rise amount of the raw material fuel when the raw material fuel is heated is compared with the temperature rise amount of the normal fuel determined in advance under the same condition to calculate the difference in the temperature rise amount. The oxygen-containing fuel content is calculated by incorporating the difference in the temperature rise of the raw material fuel into the map of the relationship between the difference and the oxygen-containing fuel content. The ECU 18 that performs such control corresponds to the content rate calculating means of the present invention.

  When the raw material fuel is a normal fuel and when the raw material fuel is a mixed fuel, the amount of temperature rise at a constant flow rate is different. Therefore, when the raw material fuel is heated by the heat pipe 4, it depends on the oxygen-containing fuel content in the raw material fuel. The difference in temperature rise at a constant flow rate appears in the temperature rise. Therefore, the temperature rise amount of the raw material fuel when the raw material fuel is heated by the heat pipe 4 at a constant flow rate is compared with the temperature rise amount of the normal fuel determined in advance under the same condition as the difference in temperature rise amount. The oxygen-containing fuel content rate is calculated by taking the difference in the calculated temperature rise amount into the map of the relationship between the temperature increase amount and the oxygen-containing fuel content rate that has been calculated in advance. According to this, the oxygen-containing fuel content rate of the high RON fuel can be accurately calculated. Accordingly, since the fuel supply amount can be corrected according to the oxygen-containing fuel content rate calculated accurately, the supply ratio of the high RON fuel is changed according to the operation state of the internal combustion engine 1, and the total fuel supply amount is changed. Even if the ratio of the oxygen-containing fuel amount is sequentially changed, the exhaust air-fuel ratio can be adjusted to the target air-fuel ratio, and the exhaust air-fuel ratio can be prevented from shifting to the lean air-fuel ratio side.

  Specifically, the content rate calculating means sets the flow rate of the raw material fuel to a constant flow rate by the flow rate control valve 3. At that time, the temperature of the raw material fuel heated by the heat pipe 4 is detected by the temperature sensor 6. The temperature of the raw material fuel before heating is determined to be the same as the intake air temperature and may be acquired from the intake air temperature sensor of the internal combustion engine 1. Alternatively, a temperature sensor is installed in the fuel tank 2 and acquired from the temperature sensor. It may be a thing. The amount of temperature increase of the raw material fuel can be calculated from the temperature of the raw material fuel after heating and the temperature of the raw material fuel before heating. FIG. 4 is a diagram showing the relationship between the operating state of the internal combustion engine 1 and the amount of temperature increase of normal fuel. Further, the temperature increase amount of the normal fuel under the same conditions as described above, for example, at the same engine load and the same engine speed, is derived from the map shown in FIG. Then, the difference in temperature increase is calculated by comparing the temperature increase of the raw material fuel with the temperature increase of the normal fuel. FIG. 5 is a graph showing the relationship between the difference in temperature rise and the oxygen-containing fuel content. By calculating this difference in temperature rise in the map of the relationship between the predetermined difference in temperature rise shown in FIG. 5 and the oxygen-containing fuel content, the oxygen-containing fuel content of the high RON fuel is calculated. Can do.

  Here, in this embodiment, the high RON fuel is stored in the high RON fuel tank 15 after being separated by the separator 7. As described above, the oxygen-containing fuel content of the high RON fuel that is currently separated by the separator 7 is found. However, there is a possibility that the high RON fuel tank 15 has a remaining amount of high RON fuel that may not have the same oxygen-containing fuel content that has been previously separated and stored. When the remaining amount of the previous high RON fuel is present in the high RON fuel tank 15 and a new high RON fuel is introduced into the high RON fuel tank 15, the oxygen content is calculated as described above. However, the high RON fuel in the high RON fuel tank 15 may be mixed with the previous remaining amount and the new inflow amount, and the oxygen content may change.

  Therefore, in this embodiment, the oxygen-containing fuel content in the high RON fuel remaining in the high RON fuel tank 15 and the high RON fuel remaining in the high RON fuel tank 15 detected by the remaining amount sensor 16 are detected. The remaining amount, the inflow amount of the high RON fuel flowing into the high RON fuel tank 15, and the oxygen-containing fuel content rate of the high RON fuel flowing into the high RON fuel tank 15 were calculated by the above content rate calculating means. The high RON fuel and the low RON fuel of the basic map with respect to the basic map according to the oxygen content of the high RON fuel in the high RON fuel tank 15 calculated based on the oxygen-containing fuel content Increase the amount of fuel supplied at the same rate. The ECU 18 that performs such control corresponds to the fuel increasing means of the present invention.

  The oxygen-containing fuel content in the high RON fuel in the high RON fuel tank 15 is the high RON fuel detected by the oxygen content in the high RON fuel remaining in the high RON fuel tank 15 and the remaining amount sensor 16. The remaining oxygen-containing fuel amount is calculated by multiplying the remaining amount in the tank 15, and the inflowing oxygen-containing fuel amount is calculated by multiplying the inflow amount of the inflowing high RON fuel by the oxygen-containing fuel content rate calculated by the content rate calculating means. And the sum of the remaining oxygen-containing fuel amount and the inflowing oxygen-containing fuel amount is divided by the sum of the remaining amount of the high RON fuel and the inflow amount.

  According to this, since the fuel supply amount can be increased and corrected according to the accurately calculated oxygen-containing fuel content rate, the supply ratio of the high RON fuel is changed according to the operating state of the internal combustion engine 1, and the total amount of fuel is Even if the ratio of the oxygen-containing fuel amount to the supply amount is sequentially changed, the exhaust air-fuel ratio can be adjusted to the target air-fuel ratio, and the exhaust air-fuel ratio can be prevented from shifting to the lean air-fuel ratio side. it can. Further, since the amount of fuel supplied by the correction is the same as the ratio of the high RON fuel and the low RON fuel in the basic map, the octane number of the fuel supplied after the correction is optimal for the operating state of the internal combustion engine 1. The octane number can be maintained. As the fuel increasing means, not only the above control but also the fuel supply amount is increased with respect to the basic map according to the calculated oxygen-containing fuel content rate, and the exhaust air-fuel ratio is made to follow the target air-fuel ratio. Anything is acceptable. Further, when there is no high RON fuel tank 15 or when the remaining amount can be regarded as 0, the fuel supply amount is increased with respect to the basic map in accordance with the oxygen-containing fuel content rate calculated by the content rate calculating means. The exhaust air-fuel ratio may be made to follow the target air-fuel ratio.

  Next, the flow of fuel supply control according to this embodiment will be described. FIG. 6 is a flowchart showing a fuel supply control routine according to this embodiment. This routine is executed particularly when the internal combustion engine 1 is started, the raw material fuel is heated by the heat pipe 4, and the raw material fuel heated at a constant flow rate reaches the stable heating range.

  When the processing of this routine is started, first, in S101, the temperature rise amount of the raw material fuel at a constant flow rate is calculated. The temperature of the raw material fuel after heating is detected by a temperature sensor 6. The temperature of the raw material fuel before heating is detected by an intake air temperature sensor, a temperature sensor in the fuel tank 2, or the like. Then, the temperature increase amount of the raw material fuel is calculated by subtracting the temperature of the raw material fuel before heating from the temperature of the heated raw material fuel.

In S102, the difference in temperature rise between the raw material fuel and the normal fuel is calculated. The temperature rise amount of the raw material fuel is calculated in S101. The temperature increase amount of the normal fuel can be derived by incorporating the same conditions as when the temperature increase amount of the raw material fuel is calculated in S101, for example, the same engine load and the same engine rotation speed, into the map shown in FIG. Then, the temperature rise amount of the raw material fuel is compared with the temperature rise amount of the normal fuel, and the temperature rise amount of the raw material fuel and the normal fuel is subtracted from the temperature rise amount of the normal fuel. Calculate the difference. Here, when calculating the difference in the temperature rise amount, the temperature rise amount of the raw fuel is subtracted from the temperature rise amount of the normal fuel. This is because the temperature rise of the raw material fuel having the oxygen-containing fuel becomes slower than that of the normal fuel. That is, the amount of temperature increase of the raw material fuel having oxygen-containing fuel is smaller than that of normal fuel. As an example, a raw material fuel containing oxygen-containing fuel, here containing 10% ethanol, has an effect of lowering the boiling point, that is, lowering the liquid phase ratio (increasing the gas phase ratio), so that the heat transfer performance is higher than that of a normal fuel. About 10% lower than the normal fuel due to the effect of latent heat of vaporization, and about 2% of the temperature rise slowed down due to the increase in specific heat. Will slow down. For this reason, the difference in the temperature rise is calculated as a positive value by subtracting the temperature rise in the raw material fuel from the temperature rise in the normal fuel.

  In S103, the oxygen-containing fuel content in the high RON fuel separated by the separator 7 is calculated from the difference in temperature increase calculated in S102. The calculation of the oxygen-containing fuel content in the high RON fuel separated by the separator 7 is performed in S102 on the map of the relationship between the predetermined temperature rise amount and the oxygen-containing fuel content shown in FIG. This is done by taking in the difference in the temperature rise. The greater the difference in temperature rise, the greater the oxygen-containing fuel content. ECU18 which performs S101-S103 respond | corresponds to a content rate calculation means.

  In S104, the oxygen-containing fuel content in the high RON fuel in the high RON fuel tank 15 is calculated. The calculation of the oxygen-containing fuel content in the high RON fuel in the high RON fuel tank 15 is performed by calculating the oxygen-containing fuel content in the high RON fuel remaining in the high RON fuel tank 15 and the high amount sensor 16 detects. The remaining oxygen-containing fuel amount is calculated by multiplying the remaining amount in the RON fuel tank 15, and the inflow amount of the high RON fuel separated and flowing in by the separator 7 is multiplied by the oxygen-containing fuel content rate calculated in S103. The inflowing oxygen-containing fuel amount is calculated, and the sum of the remaining oxygen-containing fuel amount and the inflowing oxygen-containing fuel amount is divided by the sum of the remaining amount of the high RON fuel and the inflowing amount.

  In S105, it is determined whether or not the oxygen-containing fuel content calculated in S104 is equal to the oxygen-containing fuel content (previous value) in the high RON fuel in the high RON fuel tank 15 when this routine was executed last time. To do. If a positive determination is made in S105, the process proceeds to S106. If a negative determination is made in S105, the process proceeds to S107.

  In S106, the fuel supply amount to be corrected for increase is maintained at the same rate as the previous time, and the fuel supply amount is increased and corrected at the same rate as the ratio of high RON fuel and low RON fuel in the basic map with respect to the basic map. . FIG. 7 is a diagram showing the relationship between the oxygen-containing fuel content of the high RON fuel and the fuel for the increase correction. As shown in FIG. 7, when the oxygen-containing fuel content of the high RON fuel increases, there is a linear function relationship in which the fuel for the increase correction increases. For this reason, the fuel for the amount of increase correction is obtained from the oxygen-containing fuel content of the high RON fuel using the relationship map of FIG. FIG. 8 is a diagram showing the relationship between the engine load of the internal combustion engine 1 and the fuel injection amount corrected for increase. Here, as shown in FIG. 8, the fuel for the increase correction is increased at the same rate as the ratio of the high RON fuel and the low RON fuel in the basic map of the engine load at that time. By such fuel increase correction, the exhaust air-fuel ratio can be adjusted to a target air-fuel ratio such as stoichiometry, and a shift to the lean air-fuel ratio side can be suppressed.

  In S107, the fuel supply amount to be corrected for the increase is newly changed and the increase rate is updated, and the fuel supply amount is increased and corrected at the same rate as the ratio of the high RON fuel and the low RON fuel in the basic map with respect to the basic map. To do. By using the map of the relationship in FIG. 7, the fuel for the increase correction is obtained from the oxygen-containing fuel content of the high RON fuel. As shown in FIG. 8, the fuel for the increase correction is increased at the same rate as the ratio of the high RON fuel and the low RON fuel in the basic map of the engine load at that time. By such fuel increase correction, the exhaust air-fuel ratio can be adjusted to a target air-fuel ratio such as stoichiometry, and a shift to the lean air-fuel ratio side can be suppressed.

<Others>
The fuel supply control device for an internal combustion engine according to the present invention is not limited to the above-described embodiments, and various modifications may be made without departing from the scope of the present invention. In the present invention, the content rate calculating means uses the fact that the physical properties differ between the case where the raw material fuel is a normal fuel and the case where the raw material fuel is a mixed fuel. The physical quantity related to the difference in physical properties is calculated by comparing the change in fuel with the change in normal fuel determined in advance under the same conditions, and the relationship between the predetermined physical quantity and the oxygen-containing fuel content is calculated. What is necessary is just to calculate an oxygen-containing fuel content rate by taking in the calculated physical quantity into the map. Such modifications of the present invention will be described below.

<Modification 1>
In the first modification, the description of the same configuration as that in the first embodiment is omitted. In the first modification, when the raw material fuel is heated to the target temperature with the heat pipe 4 by utilizing the fact that the flow rate at a constant temperature is different between the case where the raw material fuel is a normal fuel and the case where the raw material fuel is a mixed fuel. The flow rate of the raw material fuel is compared with the flow rate of the normal fuel determined in advance under the same conditions, and the flow rate difference is calculated, and the map of the relationship between the predetermined flow rate difference and the oxygen-containing fuel content is calculated. The oxygen-containing fuel content is calculated by taking in the difference between the flow rates. The ECU 18 that performs such control corresponds to the content rate calculating means of the present invention.

  Since the flow rate at a constant temperature differs between the case where the raw material fuel is a normal fuel and the case where the raw material fuel is a mixed fuel, if the raw material fuel is heated by the heat pipe 4 to the target temperature, the oxygen-containing fuel content in the raw material fuel The difference in flow rate due to appears in the flow rate. Therefore, the flow rate of the raw material fuel when the raw material fuel is heated to the target temperature with the heat pipe 4 is compared with the predetermined normal fuel flow rate under the same condition to calculate the difference in flow rate, and the predetermined flow rate The oxygen-containing fuel content is calculated by taking the calculated flow rate difference into the map of the relationship between the difference between the two and the oxygen-containing fuel content. According to this, the oxygen-containing fuel content rate of the high RON fuel can be accurately calculated.

  Specifically, the content rate calculating means detects the temperature of the raw material fuel heated by the heat pipe 4 with the temperature sensor 6 and heats it to the target temperature. The temperature of the raw material fuel before heating is determined to be the same as the intake air temperature and may be acquired from the intake air temperature sensor of the internal combustion engine 1. Alternatively, a temperature sensor is installed in the fuel tank 2 and acquired from the temperature sensor. It may be a thing. The flow rate of the raw material fuel at this time is detected by a flow sensor arranged in the raw material fuel pipe, or is estimated from the opening degree of the flow control valve 3. Further, the normal fuel flow rate under the same conditions as described above, for example, at the same engine load and the same engine speed, is derived from a map obtained in advance. Then, the flow rate difference is calculated by comparing the flow rate of the raw material fuel with the flow rate of the normal fuel. By incorporating this difference in flow rate into a map of the relationship between the predetermined flow rate difference and the oxygen-containing fuel content rate, the oxygen-containing fuel content rate of the high RON fuel can be calculated.

<Modification 2>
In the second modification, the description of the same configuration as that in the first embodiment is omitted. In the second modification, the heat pipe 4 is utilized by utilizing the fact that the heat transfer rate with respect to the heat transfer amount supplied from the heat pipe 4 to the raw fuel is different between the case where the raw fuel is the normal fuel and the case where the raw fuel is the mixed fuel. Heat transfer amount Q1 (= ΔT1 × m1 × K1: Q1 is unknown) calculated by multiplying the temperature rise amount ΔT1 of the raw material fuel when the raw material fuel is heated by the flow rate m1 and the heat transfer coefficient K1, and the same conditions Since the heat transfer amount Q2 of normal fuel determined in advance in Q is substantially the same (≈Q1: Q2 is known), the heat transfer coefficient K1 (= ΔT1 × m1 ÷ Q2) of the raw fuel is calculated, The oxygen-containing fuel content is calculated by incorporating the heat transfer coefficient K1 of the raw material fuel into the map of the relationship between the predetermined heat transfer coefficient and the oxygen-containing fuel content. The ECU 18 that performs such control corresponds to the content rate calculating means of the present invention.

When the raw material fuel is a normal fuel and when the raw material fuel is a mixed fuel, the heat transfer rate with respect to the heat transfer amount supplied from the heat pipe 4 to the raw fuel is different. In this case, a difference in heat transfer coefficient depending on the oxygen-containing fuel content in the raw material fuel appears in the heat transfer coefficient. Therefore, for example, the heat transfer amount Q1 (= ΔT1 × m1 × K1 = Q) in the case of a raw material fuel in a case where the heat transfer amount Q is substantially equal after 100 km of steady running is the case of the normal fuel that is determined in advance under the same conditions Since it is substantially the same as the heat transfer amount Q2 (= Q), the heat transfer coefficient K1 (= ΔT1 × m1 ÷ Q2) of the raw material fuel is calculated, and the predetermined heat transfer coefficient and the oxygen-containing fuel content ratio are calculated. By incorporating the heat transfer coefficient K1 of the raw material fuel into the relationship map, the oxygen-containing fuel content is calculated. According to this, the oxygen-containing fuel content rate of the high RON fuel can be accurately calculated.

  Specifically, the content rate calculation means performs, for example, 100 km steady running. At this time, the temperature of the raw material fuel after heating is detected by the temperature sensor 6. The temperature of the raw material fuel before heating is determined to be the same as the intake air temperature and may be acquired from the intake air temperature sensor of the internal combustion engine 1. Alternatively, a temperature sensor is installed in the fuel tank 2 and acquired from the temperature sensor. It may be a thing. Then, the temperature rise amount ΔT1 of the raw material fuel is calculated. Further, the flow rate m1 of the raw material fuel is acquired from the control value of the flow rate control valve 3. At this time, that is, the amount of heat transfer in the case of normal fuel under the same conditions of 100 km steady running is determined in advance as the amount of heat transfer Q2. Therefore, the heat transfer coefficient K1 of the raw material fuel is calculated from the equation K1 = ΔT1 × m1 ÷ Q2. By incorporating this heat transfer coefficient K1 into a predetermined map of the relationship between the heat transfer coefficient and the oxygen-containing fuel content, the oxygen-containing fuel content of the high RON fuel can be calculated.

1: internal combustion engine, 2: fuel tank, 3: flow control valve, 4: heat pipe, 5: exhaust passage, 6: temperature sensor, 7: separator, 8: aroma separation membrane, 9, 10: compartment, 11: Eductor, 12, 13: Fuel cooler, 14, 17: Injector, 15: High RON fuel tank, 16: Remaining amount sensor, 18: ECU, 20: Crank position sensor, 21: Accelerator position sensor

Claims (6)

A raw material fuel that uses either a normal fuel that does not contain oxygenated fuel or a mixed fuel that is a mixture of oxygenated fuel and normal fuel has a higher octane component content than the raw fuel. A fuel separation means for separating into a high octane fuel containing oxygen fuel and a low octane fuel with a low content of high octane components than the raw fuel,
Fuel supply means for supplying fuel by changing the ratio of the high-octane fuel and the low-octane fuel supplied to the internal combustion engine according to the operating state of the internal combustion engine according to the basic map;
A fuel supply control device for an internal combustion engine comprising:
Heating means for heating the raw fuel before separating the raw fuel by the fuel separation means;
Taking advantage of the difference in physical properties between the case where the raw material fuel is a normal fuel and the case where the raw material fuel is a mixed fuel, the change in the raw material fuel when the raw material fuel is heated by the heating means is determined in advance under the same conditions. By calculating the physical quantity related to the difference in physical properties compared to the change in normal fuel, and incorporating the calculated physical quantity into the map of the relationship between the predetermined physical quantity and the oxygen-containing fuel content, A fuel supply control device for an internal combustion engine, comprising content rate calculating means for calculating an oxygen fuel content rate.   The content rate calculating means uses the heating means at a constant flow rate by utilizing the fact that the amount of temperature rise at a constant flow rate differs between when the raw material fuel is normal fuel and when the raw material fuel is a mixed fuel. The temperature rise amount of the raw material fuel when the raw material fuel is heated is compared with the temperature rise amount of the normal fuel determined in advance under the same condition to calculate the difference in the temperature rise amount. 2. The fuel supply control for an internal combustion engine according to claim 1, wherein the oxygen-containing fuel content rate is calculated by taking in a difference in the calculated temperature rise amount in a map of the relationship between the difference and the oxygen-containing fuel content rate. apparatus.   The content rate calculation means heats the raw material fuel to the target temperature with the heating means by utilizing the fact that the flow rate at a constant temperature differs between the case where the raw material fuel is a normal fuel and the case where the raw material fuel is a mixed fuel. The flow rate of the raw material fuel is compared with the predetermined normal fuel flow rate under the same conditions to calculate the flow rate difference, and the map of the relationship between the predetermined flow rate difference and the oxygen-containing fuel content rate The fuel supply control device for an internal combustion engine according to claim 1, wherein the oxygen-containing fuel content rate is calculated by taking in the difference in the calculated flow rate.   The content rate calculating means uses the fact that the heat transfer rate with respect to the heat transfer amount supplied from the heating means to the raw material fuel is different between the case where the raw material fuel is a normal fuel and the case where the raw material fuel is a mixed fuel, The amount of heat transfer calculated by multiplying the temperature rise of the raw material fuel when the raw material fuel is heated by the heating means, the flow rate, and the heat transfer coefficient is approximately the same as the heat transfer amount of normal fuel determined in advance under the same conditions. Therefore, by calculating the heat transfer rate of the raw material fuel and incorporating the heat transfer rate of the raw material fuel into the map of the relationship between the predetermined heat transfer rate and the oxygenated fuel content rate, the oxygen-containing fuel content rate is calculated. The fuel supply control device for an internal combustion engine according to claim 1, wherein the control is performed. A high-octane fuel tank for storing the high-octane fuel separated by the fuel separation means;
A remaining amount detecting means for detecting the remaining amount of the high octane fuel in the high octane fuel tank;
The oxygen-containing fuel content in the high-octane fuel remaining in the high-octane fuel tank, the residual amount of the high-octane fuel remaining in the high-octane fuel tank detected by the remaining amount detection means, An inflow amount of high octane fuel flowing into the octane fuel tank, an oxygen content fuel content of the high octane fuel flowing into the high octane fuel tank, and the oxygen content content calculated by the content calculator; Fuel increasing means for increasing the amount of fuel supplied to the basic map according to the oxygen-containing fuel content in the high-octane fuel in the high-octane fuel tank calculated based on
The fuel supply control device for an internal combustion engine according to any one of claims 1 to 4, further comprising:   According to the oxygen-containing fuel content rate calculated by the content rate calculating means, the fuel increasing means has the same ratio as the ratio of the high octane fuel and the low octane fuel of the basic map to the basic map. 6. The fuel supply control device for an internal combustion engine according to claim 5, wherein the supply amount is increased.

Images