JP2009191702A - Fuel mixing ratio estimating device for internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fuel mixing ratio estimating device for an internal combustion engine capable of accurately estimating a mixing ratio of fuels without having an exclusive sensor for detecting the mixing ratio of the fuels in mixed fuel. <P>SOLUTION: This device is provided with a high pressure fuel pump 20 for pressure-feeding the mixed fuel wherein gasoline and alcohol are mixed, and a delivery pipe 40 for storing the mixed fuel pressure-fed by the high pressure fuel pump 20. The delivery pipe 40 is connected to a fuel injection valve 50 for supplying the stored mixed fuel to the internal combustion engine. A leakage amount of the mixed fuel passing through a minute passage 27 formed in the high pressure fuel pump 20 is calculated, and the smaller the calculated leakage amount is, the higher the mixing ratio of the fuel having a higher coefficient of viscosity in the mixed fuel, that is, the alcohol, is estimated. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a fuel mixture ratio estimation apparatus for an internal combustion engine that uses a mixed fuel in which two types of fuel such as gasoline and alcohol are mixed.

In recent years, attention has been paid to an internal combustion engine that can use a mixed fuel obtained by mixing alcohol and gasoline fuel in an arbitrary ratio. In such an internal combustion engine, various properties such as the theoretical air-fuel ratio, the calorific value, and the latent heat of vaporization are different between the alcohol and gasoline used. Therefore, it is necessary to perform control according to the mixing ratio. Thus, conventionally, a configuration has been proposed in which a dedicated sensor for detecting the alcohol mixing ratio of the mixed fuel is installed, and control is executed based on the detection value of the sensor (Patent Document 1 and Patent Document 2).
Japanese Patent Laid-Open No. 62-54987 JP-A-5-106498

  By the way, although the dedicated sensor is installed and the alcohol mixing ratio of the mixed fuel is detected to control the internal combustion engine based on the alcohol mixing ratio, the dedicated sensor is installed. There is a risk that the manufacturing cost will increase. In addition, when this dedicated sensor fails, it may be difficult to properly maintain control.

  The present invention has been made in view of such a situation, and an object thereof is to accurately estimate the mixing ratio of each fuel without providing a dedicated sensor for detecting the mixing ratio of each fuel in the mixed fuel. An object of the present invention is to provide a fuel mixture ratio estimation device for an internal combustion engine.

In the following, means for achieving the above object and its effects are described.
The invention according to claim 1 is a fuel mixture ratio estimation device for an internal combustion engine that uses a mixed fuel obtained by mixing two types of fuels having different viscosities, and is a fuel supply system that supplies the mixed fuel to the internal combustion engine. A leak amount calculating means for calculating a leak amount of the mixed fuel through the formed micro passage; and a mixture ratio estimating means for estimating a higher mixture ratio of the higher viscosity fuel in the mixed fuel as the leak amount decreases. The main point is that

  In a mixed fuel composed of two types of fuels having different viscosities, the viscosity changes depending on the mixing ratio of the respective fuels, so that the leak amount of the mixed fuel through the micro passage changes. Therefore, the mixing ratio of each fuel can be estimated based on the amount of leakage through the minute passage.

  According to the above configuration, the leak amount of the mixed fuel through the micro passage formed in the fuel supply system that supplies the mixed fuel to the internal combustion engine is calculated, and the smaller the leak amount, the higher the viscosity of the mixed fuel is mixed Since the ratio is estimated to be high, the mixing ratio of each fuel can be accurately estimated without providing a dedicated sensor for detecting the mixing ratio of each fuel in the mixed fuel.

  According to a second aspect of the present invention, in the fuel mixture ratio estimation apparatus for an internal combustion engine according to the first aspect, the fuel supply system includes a high-pressure fuel pump for pumping the mixed fuel, and a fuel for each cylinder of the internal combustion engine. A delivery pipe that is connected to an injection valve and stores the mixed fuel pumped by the high-pressure fuel pump, and the leak amount calculation means includes a mixed fuel in which each fuel is mixed at a predetermined ratio to the delivery pipe. The gist is to calculate the leak amount based on a difference in supply amount between an estimated fuel supply amount when supplied and an actual fuel supply amount actually supplied to the delivery pipe.

  In the mixed fuel in which two types of fuels having different viscosities are mixed, the total viscosity increases as the mixing ratio of the higher viscosity fuel increases, so that the amount of leakage through the micro passage decreases. For this reason, if there is a difference between the assumed mixing ratio of each fuel and the actual mixing ratio of each fuel, there is a difference between the fuel supply amount estimated in consideration of the leak amount and the actual fuel supply amount. . Therefore, as in the above configuration, the supply amount of the estimated fuel supply amount when the mixed fuel in which each fuel is mixed at a predetermined ratio is supplied to the delivery pipe and the actual fuel supply amount actually supplied to the delivery pipe Based on the difference, the leak amount can be calculated. The relationship between the mixing ratio of each fuel in the mixed fuel and the estimated fuel supply amount may be determined in advance by experiments or the like, or theoretically calculated from the design value of the fuel supply system.

  According to a third aspect of the present invention, in the fuel mixture ratio estimation apparatus for an internal combustion engine according to the first aspect, the fuel supply system includes a high pressure fuel pump for pumping the mixed fuel, and a fuel for each cylinder of the internal combustion engine. A delivery pipe that is connected to an injection valve and stores the mixed fuel pumped by the high-pressure fuel pump; and a fuel pressure detection means that detects an actual fuel pressure in the delivery pipe, and the leak amount calculation means includes: Estimated fuel pressure in the delivery pipe when the mixed fuel mixed at a predetermined ratio is supplied to the delivery pipe, and the delivery when the mixed fuel to be used is actually supplied to the delivery pipe The gist is to calculate the leak amount based on a pressure difference from the actual fuel pressure in the pipe.

  In the mixed fuel in which two types of fuels having different viscosities are mixed, the total viscosity increases as the mixing ratio of the higher viscosity fuel increases, so that the amount of leakage through the micro passage decreases. Therefore, if there is a difference between the assumed mixing ratio of each fuel and the mixing ratio of each fuel used, the fuel pressure in the delivery pipe estimated in consideration of the leak amount and the actual delivery pipe There is a difference in fuel pressure. Therefore, as in the above configuration, when the mixed fuel in which each fuel is mixed at a predetermined ratio is supplied to the delivery pipe, the estimated fuel pressure in the delivery pipe and the mixed fuel to be used are actually supplied to the delivery pipe. The amount of leak can be calculated based on the pressure difference from the actual fuel pressure in the delivery pipe when supplied.

  In addition, the fuel pressure detecting means for detecting the actual fuel pressure in the delivery pipe is provided, and the leak amount is calculated based on the actual fuel pressure detected by the fuel pressure detecting means, so that the existing fuel pressure in the delivery pipe is detected. The fuel mixture ratio can be estimated using a sensor. That is, it is not necessary to provide a dedicated sensor for detecting the mixing ratio of each fuel in the mixed fuel.

The relationship between the mixing ratio of each fuel in the mixed fuel and the estimated fuel pressure may be determined in advance by experiments or the like, or theoretically calculated from the design value of the fuel supply system.
Specifically, as described in claim 4, the high-pressure fuel pump includes a pressurizing chamber that pressurizes the mixed fuel by a plunger inserted in a sliding hole so as to be reciprocally slidable. A fuel supply amount to be supplied from the pressurizing chamber to the delivery pipe through adjustment of the opening / closing timing of the adjusting valve, comprising a fuel passage for supplying fuel to the chamber and an adjusting valve for communicating or closing the pressurizing chamber Can be controlled.

  According to a fifth aspect of the present invention, in the internal combustion engine fuel mixture ratio estimating apparatus according to the fourth aspect, the leak amount calculating means sets the state of the mixed fuel supplied to the delivery pipe to a predetermined state. In addition, the first closing timing of the regulating valve when the mixed fuel in which each fuel is mixed at the predetermined ratio is supplied to the delivery pipe, and the mixed fuel to be used is actually supplied to the delivery pipe. The gist of the present invention is to calculate the amount of leak based on a timing difference from the second valve closing timing of the regulating valve when the operation is performed.

  Here, since the amount of fuel supplied by the high-pressure fuel pump is controlled through adjustment of the opening / closing timing of the regulator valve, the difference between the estimated fuel supply amount and the actual fuel supply amount, or the difference between the estimated fuel pressure and the actual fuel pressure is determined. Accordingly, the opening / closing timing of the adjusting valve changes.

  Therefore, as described above, when the state of the mixed fuel supplied to the delivery pipe is set to a predetermined state, the adjustment valve when the mixed fuel in which each fuel is mixed at a predetermined ratio is supplied to the delivery pipe. The leak amount can be calculated based on the timing difference between the first valve closing timing and the second valve closing timing of the regulating valve when the mixed fuel to be used is actually supplied to the delivery pipe. The predetermined state of the mixed fuel state is, for example, a state in which the fuel supplied to the delivery pipe becomes a predetermined fuel supply amount, or a state in which the pressure in the delivery pipe becomes a predetermined fuel pressure, etc. Can do.

  According to a sixth aspect of the present invention, in the fuel mixing ratio estimation device for an internal combustion engine according to the fourth or fifth aspect, the minute passage is between an inner peripheral surface of the sliding hole and an outer peripheral surface of the plunger. The gist is that the space is formed.

  According to the above configuration, since the micro passage is a space formed between the inner peripheral surface of the sliding hole and the outer peripheral surface of the plunger, the amount of leakage is determined using the space formed in the design of the high-pressure fuel pump. Can be calculated.

  According to a seventh aspect of the present invention, in the fuel mixture ratio estimation apparatus for an internal combustion engine according to the first aspect, the fuel supply system includes a high-pressure fuel pump that pumps the mixed fuel, and a fuel for each cylinder of the internal combustion engine. A delivery pipe that is connected to an injection valve and stores the mixed fuel pumped by the high-pressure fuel pump, and the leak amount calculation means calculates the leak amount of the mixed fuel from the delivery pipe through the micro passage. The gist is to calculate.

  As described above, the fuel supply system includes a high-pressure fuel pump that pumps the mixed fuel, a delivery pipe that is connected to the fuel injection valve of each cylinder of the internal combustion engine and stores the mixed fuel pumped by the high-pressure fuel pump, And the leak amount calculation means calculates the leak amount of the mixed fuel from the delivery pipe through the micro passage.

  The invention according to claim 8 is the fuel mixture ratio estimation apparatus for the internal combustion engine according to claim 7, wherein the fuel supply system further comprises a fuel pressure detecting means for detecting an actual fuel pressure in the delivery pipe, The gist of the leak amount calculation means is to calculate the leak amount based on a change in the actual fuel pressure accompanying the leak of the mixed fuel through the minute passage.

  The actual fuel pressure in the delivery pipe changes according to the amount of fuel leak from the delivery pipe through the micro passage. Therefore, as in the above configuration, the leak amount can be calculated based on the change in the actual fuel pressure in the delivery pipe accompanying the leak of the mixed fuel through the micro passage.

  Note that the relationship between the change in the actual fuel pressure in the delivery pipe due to the leakage of the mixed fuel through the micro passage and the amount of leakage may be determined in advance by experiments or the like, or theoretically based on the design value of the fuel supply system. May be calculated.

Specifically, as described in claim 9, the micro passage can be a passage that leaks the mixed fuel pumped by the high-pressure fuel pump.
A tenth aspect of the present invention is the internal combustion engine fuel mixture ratio estimating apparatus according to the ninth aspect, wherein the high-pressure fuel pump includes a pressurizing chamber for pressurizing the mixed fuel, and the delivery pipe from the pressurizing chamber. A discharge valve that allows the mixed fuel to pass only in the direction of the pressure, and the micro passage is provided in the discharge valve and is capable of passing the mixed fuel from the delivery pipe in the direction of the pressurizing chamber. The gist is that it is a hole.

  Here, the pressure reducing hole through which the mixed fuel can pass from the delivery pipe in the direction of the pressurizing chamber of the high pressure fuel pump means that the pressure in the delivery pipe is reduced after the internal combustion engine is stopped, that is, after the high pressure fuel pump is stopped. Therefore, it is a passage provided in the discharge valve. Thus, after the internal combustion engine is stopped, the delivery pipe is prevented from being maintained in a high pressure state, and fuel leakage from the fuel injection valve is suppressed.

  According to the above configuration, the micro passage is a pressure reducing hole that is provided in the discharge valve and allows the mixed fuel to pass from the delivery pipe to the pressurizing chamber. The amount of leakage can be calculated using a pressure reducing hole provided to suppress fuel leakage.

  The invention according to claim 11 is the fuel mixture ratio estimation device for an internal combustion engine according to any one of claims 1 to 10, wherein the leak amount calculation means passes through the minute passage during idle operation of the internal combustion engine. The gist is to calculate the leak amount of the mixed fuel.

  According to the above configuration, since the leak amount calculation means calculates the leak amount of the mixed fuel through the micro passage during the idling operation of the internal combustion engine, the leak of the mixed fuel is performed in a state where the fuel supply amount required for the internal combustion engine is stable. The amount can be calculated. Accordingly, the amount of fuel supplied from the high-pressure fuel pump to the delivery pipe does not vary greatly with time, and the amount of leakage can be easily calculated.

  The invention according to claim 12 is the fuel mixture ratio estimation device for an internal combustion engine according to any one of claims 1 to 11, wherein the mixed fuel is a fuel in which gasoline and alcohol are mixed, and the mixture The gist of the ratio estimating means is to estimate the alcohol mixing ratio of the mixed fuel.

  As in the above configuration, the mixed fuel is a fuel in which gasoline and alcohol are mixed, and the mixing ratio estimation means can estimate the alcohol mixing ratio of the mixed fuel.

(First embodiment)
Hereinafter, a first embodiment in which a fuel mixture ratio estimation apparatus for an internal combustion engine according to the present invention is embodied will be described with reference to FIGS.

  FIG. 1 shows an internal combustion engine (hereinafter simply referred to as “internal combustion engine”) and a fuel supply system for a flexible fuel vehicle (FFV) to which a fuel mixture ratio estimation apparatus for an internal combustion engine according to the present invention is applied. FFV refers to a vehicle that can use only alcohol (alcohol mixing ratio AC is 100%), gasoline only (alcohol mixing ratio AC is 0%), or mixed fuel in which alcohol and gasoline are mixed. Say. In the following description, the term “fuel” simply indicates a mixed fuel in which alcohol and gasoline are mixed.

  A low pressure fuel pump 11 is disposed in the fuel tank 10, and the low pressure fuel pump 11 is connected to a low pressure fuel passage 12 through a fuel filter 15. The low pressure fuel passage 12 is connected to the high pressure fuel pump 20 and the return passage 14 respectively. The end of the return passage 14 is opened into the fuel tank 10, and a low-pressure pressure regulator 13 that maintains the pressure of the fuel in the low-pressure fuel passage 12 at the set pressure Pl is provided at the end. . The low pressure regulator 13 is a pressure actuated valve that opens when the preset pressure P1 is exceeded, and the fuel is returned to the fuel tank 10 through the return passage 14 when the actuated valve is opened. It is. The set pressure Pl is set based on the discharge capacity of the low-pressure fuel pump 11 and the like.

  A plunger 25 is accommodated in the sliding hole of the cylinder 24 of the high-pressure fuel pump 20 so as to be reciprocally movable, and a pressurizing chamber 26 for pressurizing fuel by the movement of the plunger 25 is formed adjacent to the cylinder 24. Yes. Further, a predetermined space (clearance) is set between the inner peripheral surface of the sliding hole of the cylinder 24 and the outer peripheral surface of the plunger 25, and this space constitutes a minute passage 27. When the fuel is pumped by the high pressure fuel pump 20, the fuel leaks through the minute passage 27. The flow passage cross-sectional area of the minute passage 27 is calculated from design values of the cylinder 24 and the plunger 25.

  An end of the plunger 25 opposite to the pressurizing chamber 26 is connected to a lifter 22a, and the lifter 22a is biased by a coil spring 23 toward a cam 22 attached to the camshaft 21 of the internal combustion engine. Then, as the cam 22 rotates, the plunger 25 reciprocates in the sliding hole of the cylinder 24, and the expansion stroke in which the plunger 25 moves in the direction in which the fuel in the pressurizing chamber 26 expands is added. The compression stroke that moves in the direction of compressing the fuel in the pressure chamber 26 is repeated alternately.

  An electromagnetic spill valve 30 is provided at a connection port 31 between the low-pressure fuel passage 12 and the pressurizing chamber 26. The electromagnetic spill valve 30 is urged in a direction to open the connection port 31 by a coil spring 33 and is driven in a closing direction by applying a voltage to the electromagnetic solenoid 32. When the expansion stroke is reached in a state where the electromagnetic spill valve 30 opens the connection port 31, the fuel from the low pressure fuel pump 11 is sucked into the pressurizing chamber 26 through the low pressure fuel passage 12. On the other hand, when the electromagnetic spill valve 30 enters the compression stroke with the connection port 31 closed, the fuel in the pressurizing chamber 26 is pressurized and discharged into the high-pressure fuel passage 41. That is, fuel is supplied to the delivery pipe 40 during the closing period of the electromagnetic spill valve 30.

  The high-pressure fuel passage 41 connected to the pressurizing chamber 26 is connected to a delivery pipe 40, and a discharge valve 34 is provided in the middle thereof. The discharge valve 34 is a pressure actuated valve that opens when the pressure of the supplied fuel becomes equal to or higher than the set pressure Pm, and only in the direction from the pressurizing chamber 26 to the delivery pipe 40 (only in the direction indicated by the arrow A). Let the fuel pass. The set pressure Pm is set to a relatively low pressure.

  A fuel injection valve 50 that injects fuel into each cylinder of the internal combustion engine is connected to the delivery pipe 40. As a result, the fuel discharged into the high-pressure fuel passage 41 is supplied to the delivery pipe 40 via the discharge valve 34 and stored in the pipe 40, and also supplied into each cylinder of the internal combustion engine by the fuel injection valve 50. Is done.

  The delivery pipe 40 is provided with a relief valve 60 for maintaining the pressure in the pipe 40 at or below a preset pressure Ph set in advance. The relief valve 60 is a pressure operating valve that opens when the pressure in the pipe 40 exceeds the set pressure Ph. When the operating valve is opened, the fuel is returned to the fuel tank 10 through the relief passage 61. It is. The set pressure Ph is set to a pressure that can prevent the fuel pressure in the delivery pipe 40 from becoming excessively high. In addition, a fuel pressure sensor 40 a that detects the fuel pressure in the pipe 40 is attached to the delivery pipe 40 and a signal is output to the electronic control unit 70. This fuel pressure sensor 40a corresponds to a fuel pressure detecting means.

  The internal combustion engine is provided with various sensors, the engine rotation speed sensor 71 detects the engine rotation speed, the cam position sensor 72 detects the rotation position of the cam 22, and the accelerator depression amount sensor 73 depresses the depression amount of the accelerator pedal. The throttle valve opening sensor 74 detects the opening of the throttle valve that adjusts the intake air amount and outputs it to the electronic control unit 70.

  The electronic control unit 70 includes a calculation unit (CPU), a memory for storing and holding various control programs, calculation maps, data calculated when the control is executed, and the like. Based on outputs from various sensors, fuel injection control and ignition timing control by the fuel injection valve 50, intake air amount control by the throttle valve, fuel supply amount control by the high-pressure fuel pump 20, and the like are executed.

  In addition, the electronic control unit 70 executes a leak amount calculation process for calculating the amount of fuel leakage through the micro passage 27 described above, and alcohol that estimates the alcohol mixture ratio AC of the currently used fuel based on the amount of leak. A mixing ratio estimation process is executed. In the present embodiment, the leak amount calculation process executed by the electronic control device 70 corresponds to the process as the leak amount calculation means, and the alcohol mixture ratio estimation process corresponds to the process as the mixture ratio estimation means.

  Next, the leak amount calculation process and the alcohol mixture ratio estimation process performed by the electronic control unit 70 will be described with reference to FIGS. FIG. 2 is a flowchart showing a flow of a series of processing, and the actual processing is repeatedly executed by the electronic control unit 70 with a predetermined cycle.

  As shown in FIG. 2, in this series of processing, it is first determined whether or not the internal combustion engine is in an idling operation (step S100). Specifically, the determination is made based on the operating state of the internal combustion engine detected based on various outputs from the engine speed sensor 71, the accelerator depression amount sensor 73, the throttle valve opening sensor 74, and the like. If it is determined that it is not during idling (step S100: NO), the series of processes is temporarily terminated.

  On the other hand, when it is determined that the engine is idling (step S100: YES), fuel pressure feed is started (step S110). Specifically, the position of the plunger 25 is detected based on the output from the cam position sensor 72, and the electromagnetic solenoid 32 is energized at a predetermined valve closing timing (timing t11 shown in FIG. 3) in the compression stroke of the plunger 25. As a result, the electromagnetic spill valve 30 is closed. Thereby, fuel pressure feed from the pressurizing chamber 26 to the delivery pipe 40 is started, and the fuel pressure in the delivery pipe 40 increases as shown by the solid line in FIG. Note that the solid line in (b) fuel pressure change indicates the actual fuel pressure change due to the fuel currently in use, that is, the fuel whose alcohol mixing ratio AC is estimated.

  Subsequently, it is determined whether or not the pumping period T1 has elapsed (step S120). This pumping period T1 is set in advance as a period suitable for carrying out the main processing related to the leak amount calculation. If it is determined that the pumping period T1 has not elapsed (step S120: NO), the determination process in step S120 is repeatedly executed at regular time intervals until a result indicating that the pumping period T1 has elapsed is obtained. Is done.

  If it is determined through this determination that the pumping period T1 has elapsed (step S120: YES), the fuel pumping is terminated (step S130). Specifically, fuel pumping is terminated by opening the electromagnetic spill valve 30 at timing t12.

  Here, the estimated fuel pressure Pe in the pipe 40 when the fuel whose alcohol mixing ratio AC is 0% (fuel of 100% gasoline) is supplied to the delivery pipe 40 is preset. Specifically, as indicated by a one-dot chain line in FIG. 3, a change in fuel pressure in the delivery pipe 40 when fuel with an alcohol mixing ratio AC of 0% (fuel with 100% gasoline) is supplied is estimated. Yes. The estimated fuel pressure Pe corresponds to a fuel pressure that is increased when 100% gasoline is supplied to the delivery pipe 40 by the estimated fuel supply amount Qe, and a leak amount (estimated leak amount) Qle0 that leaks through the minute passage 27 is calculated. It is set in consideration. Here, the leak amount Qle is calculated based on the following equation (1).

^{Qle = (πdh 3 / 12μl)} ΔP ··· (1)
π: Circumference ratio, d: Diameter of plunger 25 h: Distance between outer peripheral surface of plunger 25 and inner peripheral surface of sliding hole μ: Viscosity, l: Length of minute passage, ΔP: Pressure inside and outside of minute passage Difference The estimated fuel pressure Pe and the estimated fuel supply amount Qe are calculated based on the calculated estimated leak amount Qle0 and the design values of the cylinder 24, plunger 25, delivery pipe 40, etc. of the high-pressure fuel pump 20. The estimated fuel pressure Pe may be obtained in advance by experiments or the like.

  Next, the actual fuel pressure P is detected at timing t12 when the fuel pumping is finished (step S140). The actual fuel pressure P is detected based on the output from the fuel pressure sensor 40a.

  Then, a pressure difference ΔP1 between the detected actual fuel pressure P and the estimated fuel pressure Pe is calculated (step S150), and an actual leak amount Qle when supplied to the delivery pipe 40 based on the calculated pressure difference ΔP1. Is calculated (step S160). This leak amount (actual leak amount) Qle is calculated with reference to the map shown in FIG. 4 so as to decrease as the pressure difference ΔP1 increases.

  Here, when ΔP1 is a positive value, that is, when the actual fuel pressure P is larger than the estimated fuel pressure Pe, the fuel supply amount (actual fuel supply amount) Q actually supplied to the delivery pipe 40 is the estimated fuel supply. It can be determined that the amount was larger than the amount Qe. The fuel supply amount and the leak amount have a relationship represented by the following equation.

Actual fuel supply amount Q + Actual leak amount Qle = Estimated fuel supply amount Qe + Estimated leak amount Qle0
That is, when the actual fuel supply amount Q is larger than the estimated fuel supply amount Qe, it can be determined that the actual leak amount Qle is smaller than the estimated leak amount Qle0. In other words, when the actual fuel pressure P is greater than the estimated fuel pressure Pe, it can be determined that the actual leak amount Qle is less than the estimated leak amount Qle0. Therefore, the pressure difference ΔP1 and the leak amount Qle are in the relationship shown in FIG. 4, and it can be determined that the leak amount Qle decreases as the pressure difference ΔP1 increases. The map shown in FIG. 4 is set based on experiments and the like. The processing from step S110 to step S160 corresponds to the leak amount calculation processing.

  Next, the alcohol mixing ratio AC is estimated based on the calculated leak amount Qle (step S170). The process in this step corresponds to an alcohol mixture ratio estimation process. Specifically, with reference to the map shown in FIG. 6, the alcohol mixing ratio AC is estimated to be higher as the leak amount Qle is smaller. When the alcohol mixing ratio AC is estimated as a result, a series of processing ends.

Hereinafter, the reason why the alcohol mixing ratio AC can be estimated to be higher as the leak amount Qle is smaller as shown in FIG. 6 will be described.
First, the viscosity μ differs between alcohol and gasoline contained in fuel. Specifically, since the viscosity μ of alcohol is higher than the viscosity μ of gasoline, in the mixed fuel of alcohol and gasoline, as shown in FIG. 5A, the viscosity μ increases as the alcohol mixing ratio AC increases. Show the trend. That is, when the viscosity μ of a fuel having an alcohol mixing ratio AC of 0% (gasoline 100%) is μ0 and the viscosity μ of a fuel having an alcohol mixing ratio AC of 100% is μ100, these alcohols and gasoline are mixed. The viscosity μ of the mixed fuel is any value from μ0 to μ100 depending on the alcohol mixing ratio AC.

  Secondly, the leak amount Qle through the minute passage 27 satisfies the relationship of the above formula (1), and therefore decreases as the viscosity μ increases as shown in FIG. 5B. Specifically, the leak amount Qle0 of the fuel whose viscosity μ is μ0 (<μ100) is larger than the leak amount Qle100 of the fuel whose viscosity μ is μ100, and the fuel whose viscosity μ is μ0 and the viscosity μ is μ100. The leak amount Qle of the mixed fuel mixed with the fuel of any one of the values is any value from the leak amount Qle0 to the leak amount Qle100 according to the viscosity μ of the mixed fuel.

  Due to the first and second facts, the alcohol mixing ratio AC can be estimated based on the leak amount Qle through the minute passage 27. As described above, the smaller the leak amount Qle, the higher the alcohol mixing ratio AC is estimated. be able to. Note that the relationship between the leak amount Qle and the alcohol mixing ratio AC, that is, the relationship shown in FIG. 6, is set based on experiments and the like.

According to the first embodiment described above, the following effects can be obtained.
(1) The fuel leak amount Qle through the minute passage 27 is calculated, and the fuel with higher viscosity in the fuel, that is, the alcohol mixing ratio AC is estimated to be higher as the leak amount Qle is smaller (step S170). Thus, the mixing ratio of each fuel can be accurately estimated without providing a dedicated sensor for detecting the mixing ratio of each fuel.

  (2) Since the fuel mixture ratio can be estimated using the existing fuel pressure sensor 40a that detects the fuel pressure in the delivery pipe 40, a dedicated sensor for detecting the mixture ratio of each fuel in the mixed fuel is provided. Without providing it, the alcohol mixing ratio AC can be estimated.

  (3) Since the minute passage 27 is a space between the inner peripheral surface of the sliding hole of the cylinder 24 and the outer peripheral surface of the plunger 25, the amount of leakage is made using the space formed in the design of the high-pressure fuel pump 20. Qle can be calculated.

  (4) Since the leak amount calculation process is executed during the idling operation of the internal combustion engine to calculate the fuel leak amount Qle through the minute passage 27, the fuel leak amount in a state where the fuel supply amount required for the internal combustion engine is stable. Qle can be calculated. Therefore, the amount of fuel supplied from the high-pressure fuel pump 20 to the delivery pipe 40 does not vary greatly with time, and the leak amount Qle can be easily calculated.

(Second Embodiment)
A second embodiment that embodies a fuel mixture ratio estimation apparatus for an internal combustion engine according to the present invention will be described below with reference to FIGS. 1 and 7 to 10. Note that the same components as those in the first embodiment are denoted by the same reference numerals, and detailed description thereof is omitted, and detailed description of the same processing is omitted.

  FIG. 7 is a flowchart showing a flow of a series of processes, and the actual processes are repeatedly executed by the electronic control unit 70 with a predetermined cycle. In this series of processes, first, the electromagnetic spill valve is closed at the first valve closing timing t1, and the first fuel pumping is started (step S200). In this way, by starting fuel pumping at the first valve closing timing t1 (timing t21 shown in FIG. 8), as shown by the solid line in (c) fuel pressure change in FIG. Fuel pressure rises.

  Subsequently, it is determined whether or not the pumping period T2a has elapsed (step S210). This pumping period T2a is set in advance as a period suitable for carrying out this processing for calculating the leak amount. If it is determined that the pumping period T2a has not elapsed (step S210: NO), the determination process in step S210 is repeatedly executed at regular time intervals until a result indicating that the pumping period T2a has elapsed is obtained. Is done.

  If it is determined through this determination that the pumping period T2a has elapsed (step S210: YES), the electromagnetic spill valve is opened and the first fuel pumping is terminated (step S220). The end of the first fuel pumping is executed at timing t22.

  Next, the actual fuel pressure P is detected at the timing t22 when the fuel pumping is finished (step S230), and then the pressure difference ΔP2 between the actual fuel pressure P and the estimated fuel pressure Pe is calculated (step S240). . This estimated fuel pressure Pe is a fuel pressure set in the same manner as in the first embodiment, and is 100% gasoline during the first valve closing timing t1 to the pumping period T2a (between timing t21 and timing t22). This corresponds to the fuel pressure in the delivery pipe 40 that is estimated to be reached when the fuel is supplied.

Then, based on the calculated pressure difference ΔP2, the second valve closing timing t2 is set (step S250). Thereby, the valve closing timing is changed based on the pressure difference ΔP2.
Hereinafter, the second valve closing timing t2 and the relationship between the second valve closing timing t2 and the pressure difference ΔP2 will be described in detail. Note that the electromagnetic spill valve (a) reference pumping timing shown in FIG. 8 indicates the opening / closing timing of the electromagnetic spill valve 30 when fuel with an alcohol mixing ratio AC of 0% (100% gasoline fuel) is supplied. (B) The actual pressure feed timing indicates the opening / closing timing of the electromagnetic spill valve 30 when the fuel to be used, that is, the fuel whose alcohol mixture ratio AC is estimated is supplied. In addition, (c) one-dot chain line of fuel pressure change indicates an estimated change when 100% gasoline fuel is supplied, and a solid line indicates a change when fuel to be used is supplied.

  The second valve closing timing t2 is the closing timing of the electromagnetic spill valve 30 in the second fuel pressure feed stroke, and the actual fuel pressure P and the estimated fuel pressure at the end of the fuel pressure feed in this stroke (timing t27). The valve closing timing for matching Pe.

  Here, when the second fuel pumping is started from the second valve closing timing t2 (timing t26) in the second fuel pumping stroke, the fuel pressure increases as shown by the solid line in FIG. The actual fuel pressure P at the time (timing t27) coincides with the estimated fuel pressure Pe. This estimated fuel pressure Pe is the same pressure as the estimated fuel pressure Pe in the first fuel pumping stroke, and is 100% gasoline from the first valve closing timing t1 (timing t25) in the second fuel pumping stroke. This corresponds to the fuel pressure estimated to be reached at the end of fuel pumping (timing t27) due to the fuel pressure rising. As described above, regarding the fuel pressure in the delivery pipe 40 at the timing t27, matching the actual fuel pressure P with the estimated fuel pressure Pe corresponds to setting the state of the mixed fuel to a predetermined state.

  The second valve closing timing t2 is set so as to be delayed as the pressure difference ΔP2 increases with reference to the map shown in FIG. In the present embodiment, the opening timing of the electromagnetic spill valve 30 in the first and second fuel pumping strokes is set to be the same, so that the pumping period is shortened as the valve closing timing is delayed. That is, as shown in FIG. 8, the pumping period T2b in the second fuel pumping stroke is shorter than the pumping period T2a in the first fuel pumping stroke. This is equivalent to shortening the fuel pumping period required to make the actual fuel pressure P coincide with the estimated fuel pressure Pe.

  Here, when the pressure difference ΔP2 is a positive value, that is, when the actual fuel pressure P is larger than the estimated fuel pressure Pe, the actual fuel supply amount (actual fuel supply amount) Q supplied to the delivery pipe 40 is the estimated fuel. It can be determined that the amount is greater than the supply amount Qe. Further, the amount of fuel supplied by the high-pressure fuel pump 20 can be reduced as the valve closing timing is delayed. Accordingly, by delaying the second valve closing timing t2 from the valve closing timing t1 in the first fuel pressure feed stroke, the actual fuel pressure P at the end of the fuel pressure feed in the second fuel pressure feed stroke (timing t27) is obtained. It approaches the estimated fuel pressure Pe. In other words, as shown in FIG. 9, the second valve closing timing t2 is set to be delayed as the pressure difference ΔP2 increases, so that the actual fuel pressure P and the estimated fuel pressure Pe at the timing t27 coincide with each other. Will be able to. The map shown in FIG. 9 is set in advance based on experiments and the like.

  In this way, when the second valve closing timing t2 is set in step S250, the timing difference ΔT (second valve closing timing t2−first valve closing timing t1) based on the second valve closing timing t2. ) Is calculated (step S260). Thereby, the timing difference ΔT is calculated to be larger as the pressure difference ΔP2 becomes larger.

  Based on the calculated timing difference ΔT, the actual leak amount Qle when supplied to the delivery pipe 40 is calculated (step S270). This leak amount (actual leak amount) Qle is calculated with reference to the map shown in FIG. 10 so as to decrease as the timing difference ΔT increases.

  Here, as described above, the timing difference ΔT increases as the pressure difference ΔP2 in the first fuel pumping stroke increases. Further, the relationship between the pressure difference ΔP2 and the actual leak amount Qle is the same as the relationship between the pressure difference ΔP1 and the actual leak amount Qle in the first embodiment, and the actual leak amount Qle increases as the pressure difference ΔP2 increases. It can be judged that there were few. Therefore, the timing difference ΔT and the leak amount Qle have the relationship shown in FIG. 10, and it can be determined that the leak amount Qle is smaller as the timing difference ΔT increases. Note that the processing from step S200 to step S270 corresponds to the leak amount calculation processing.

  Based on the calculated leak amount Qle, the alcohol mixing ratio AC is estimated (step S280). The process in this step corresponds to an alcohol mixture ratio estimation process. As a result, a series of processing ends.

According to 2nd Embodiment described above, in addition to the effect shown to said (1)-(3), there can exist the effect shown to the following (5).
(5) The closing timing of the electromagnetic spill valve 30 changes according to the difference ΔP2 between the estimated fuel pressure Pe and the actual fuel pressure P. Therefore, when the state of the mixed fuel is set to a predetermined state, that is, when the actual fuel pressure P in the delivery pipe 40 at the end of fuel pumping (timing t27) matches the estimated fuel pressure Pe, the alcohol mixing ratio AC is 0%. The first closing timing t1 of the electromagnetic spill valve 30 when the fuel is supplied to the delivery pipe 40, and the second closing timing t1 of the electromagnetic spill valve 30 when the used fuel is actually supplied to the delivery pipe 40. The leak amount Qle can be calculated based on the timing difference ΔT with the valve closing timing t2.
(Third embodiment)
A third embodiment that embodies a fuel mixture ratio estimation apparatus for an internal combustion engine according to the present invention will be described below with reference to FIGS. 1 and 11 to 13. In addition, about the structure similar to the said 1st, 2nd embodiment, while attaching | subjecting the same code | symbol, detailed description is abbreviate | omitted, and description of a specific aspect is abbreviate | omitted about the same process.

  In the first and second embodiments, alcohol is used based on the leak amount Qle that leaks through the micro passage 27 that is a space formed between the inner peripheral surface of the sliding hole of the cylinder 24 and the outer peripheral surface of the plunger 25. The mixing ratio AC was estimated. In contrast, in the present embodiment, as shown by a broken line in FIG. 1, the discharge valve 34 is provided with a pressure reducing hole 34a, and the alcohol mixing ratio AC is set based on the amount of leakage leaking from the delivery pipe 40 through the pressure reducing hole 34a. presume.

  The decompression hole 34a is a minute passage through which fuel can pass from the delivery pipe 40 in the direction of the pressurizing chamber 26, and after the internal combustion engine is stopped, that is, after the high-pressure fuel pump 20 is stopped, Is provided to reduce the pressure. Thus, after the internal combustion engine is stopped, the delivery pipe 40 is prevented from being maintained in a high pressure state, and fuel leakage from the fuel injection valve 50 is suppressed. In addition, the opening area of the pressure reducing hole 34a can reduce the fuel pressure in the delivery pipe 40 after the internal combustion engine is stopped in this way, and hinder the fuel supply to the pipe 40 by the high pressure fuel pump 20. It is set to a size that is not.

  FIG. 11 is a flowchart showing a flow of a series of processing, and the actual processing is repeatedly executed by the electronic control unit 70 with a predetermined cycle. In this series of processes, first, fuel pressure feed is started (step S300). As described above, the fuel pressure in the delivery pipe 40 is increased by starting the fuel pumping at the timing t31 shown in FIG.

  Subsequently, it is determined whether or not the actual fuel pressure P has reached the target fuel pressure Pt (step S310). Specifically, the determination is made based on the output from the fuel pressure sensor 40a. The target fuel pressure Pt is a fuel pressure required as a fuel pressure in the delivery pipe 40, and is set according to the vehicle operating state detected based on outputs from various sensors.

  If it is determined that the actual fuel pressure P has not reached the target fuel pressure Pt (step S310: NO), the process proceeds to step S310 until a result indicating that the actual fuel pressure P has reached the target fuel pressure Pt is obtained. The determination process is repeatedly executed at regular time intervals.

  If it is determined through this determination that the actual fuel pressure P has reached the target fuel pressure Pt (step S310: YES), fuel pumping is terminated (step S320). Thereafter, as the fuel leaks through the decompression hole 34a, the fuel pressure in the delivery pipe 40 decreases as shown by the solid line in FIG. 12 indicates a change in fuel pressure (estimated fuel pressure) Pe when fuel having an alcohol mixing ratio AC of 0% (fuel of 100% gasoline) leaks through the decompression hole 34a.

  Subsequently, it is determined whether or not a predetermined period T3 has elapsed (step S330). This predetermined period T3 is set to a period suitable for executing this process for calculating the leak amount. When fuel injection by the fuel injection valve 50 is started, the fuel in the delivery pipe 40 is consumed, and the fuel pressure is reduced due to the fuel injection. As a result, a decrease in fuel pressure due to fuel leakage through the pressure reducing hole 34a cannot be detected, and therefore, a predetermined period T3 is set between the time when the fuel pumping ends and the time when the fuel injection by the fuel injection valve 50 starts. The

  When it is determined that the predetermined period T3 has not elapsed (step S330: NO), the determination process of step S330 is repeatedly executed at regular time intervals until it is determined that the predetermined period T3 has elapsed. The

  If it is determined that the predetermined period T3 has passed through this determination (step S330: YES), the actual fuel pressure Pa at the timing t33 when the predetermined period T3 has elapsed is detected (step S340), and the detected actual fuel is detected. A pressure change ΔP3 is calculated based on the pressure Pa (step S350). This pressure change ΔP3 is a value obtained by subtracting the actual fuel pressure P (actual fuel pressure Pa) at the timing t33 from the actual fuel pressure P (target fuel pressure Pt) at the timing t32, and the fuel leak through the decompression hole 34a. This corresponds to a change in the actual fuel pressure P.

  Next, the actual leak amount Qle is calculated based on the calculated pressure change ΔP3 (step S360). This leak amount Qle is calculated with reference to FIG. 13 as the pressure change ΔP3 increases. This leak amount Qle corresponds to the fuel leak amount from the delivery pipe 40 through the decompression hole 34a (micro passage). Further, the relationship between the leak amount Qle and the pressure change ΔP3 shown in FIG. 13 may be determined in advance by experiments or the like, or theoretically calculated from design values of the delivery pipe 40 and the like. Note that the processing from step S320 to step S360 corresponds to the leak amount calculation processing.

  Based on the calculated leak amount Qle, the alcohol mixing ratio AC is estimated (step S370). The process in this step corresponds to an alcohol mixture ratio estimation process. As a result, a series of processing ends.

According to the third embodiment described above, the following effects (6) and (7) can be obtained in addition to the functions and effects equivalent to the above (1) and (2).
(6) The actual fuel pressure P in the pipe 40 changes according to the fuel leak amount Qle from the delivery pipe 40 through the decompression hole 34a. Therefore, the leak amount Qle can be calculated based on the change in the actual fuel pressure P in the delivery pipe 40 accompanying the fuel leak through the decompression hole 34a.

  (7) The leak amount Qle is calculated using a decompression hole 34a that is provided in the discharge valve 34 and allows the fuel to pass from the delivery pipe 40 toward the pressurizing chamber 26 of the high-pressure fuel pump 20. Therefore, the leak amount Qle can be calculated using the pressure reducing hole 34a provided to suppress fuel leakage from the fuel injection valve 50 after the internal combustion engine is stopped.

(Other embodiments)
Note that the fuel mixture ratio estimation device for an internal combustion engine according to the present invention is not limited to the configuration exemplified in the above embodiment, and is implemented as the following embodiment, which is appropriately modified from the embodiment. You can also.

  In the first embodiment, the example in which the leak amount Qle is calculated based on the pressure difference ΔP1 between the actual fuel pressure P and the estimated fuel pressure Pe is shown. However, based on the supply amount difference ΔQ between the estimated fuel supply amount Qe when the mixed fuel in which each fuel is mixed at a predetermined ratio is supplied to the delivery pipe and the actual fuel supply amount Q actually supplied to the delivery pipe. A mode of calculating the leak amount Qle can also be adopted. The actual fuel supply amount Q can be obtained, for example, by detecting the flow rate of fuel passing through a predetermined passage. Even in this case, the effect shown in the above (1) can be achieved.

  In the second embodiment, the example in which the timing difference ΔT is calculated based on the pressure difference ΔP2 between the actual fuel pressure P and the estimated fuel pressure Pe is shown. However, based on the supply amount difference ΔQ between the estimated fuel supply amount Qe when the mixed fuel in which each fuel is mixed at a predetermined ratio is supplied to the delivery pipe and the actual fuel supply amount Q actually supplied to the delivery pipe. It is also possible to adopt a mode in which the timing difference ΔT is calculated, and thereby the leak amount Qle is calculated. In this case, setting the mixed fuel to a predetermined state corresponds to matching the actual fuel supply amount Q at the end of the fuel pumping in the second fuel pumping stroke with the estimated fuel supply amount Qe. Even in this case, the following effects (8) can be obtained in addition to the effects (1).

  (8) The closing timing of the electromagnetic spill valve 30 changes according to the difference ΔQ between the estimated fuel supply amount Qe and the actual fuel supply amount Q. Therefore, when the state of the mixed fuel is a predetermined state, that is, when the actual fuel supply amount Q in the delivery pipe 40 at the end of fuel pumping (timing t27) is matched with the estimated fuel supply amount Qe, the alcohol mixing ratio AC is 0%. The first valve closing timing t1 of the electromagnetic spill valve 30 when a certain fuel is supplied to the delivery pipe 40, and the second closing timing t1 of the electromagnetic spill valve 30 when the used fuel is actually supplied to the delivery pipe 40. The leak amount Qle can be calculated based on the timing difference ΔT with the valve closing timing t2.

  In the second embodiment, the closing timing of the electromagnetic spill valve 30 is changed from the first closing timing t1 to the second closing timing t2 based on the pressure difference ΔP2, and the timing difference between the closing timings An example in which the leak amount Qle is calculated based on ΔT is shown. However, the leak amount Qle is not limited to the calculation of the valve closing timing in this way, but the leak amount Qle is calculated based on the change in the pumping period by the high-pressure fuel pump 20, that is, the change in the valve closing period of the electromagnetic spill valve 30. You can also

  In the first embodiment, an example is shown in which the pumping period T1 is set as a period suitable for the main processing for calculating the leak amount, and the estimated fuel pressure Pe when the pumping period T1 elapses is set in advance. However, the target fuel pressure Pt used in the third embodiment may be set as the estimated fuel pressure Pe. In this case, the pumping period T1 is calculated so as to reach the target fuel pressure Pt required as the fuel pressure in the delivery pipe 40, and the control of the high-pressure fuel pump is executed. Then, the leakage amount may be calculated based on the pressure difference between the actual fuel pressure P and the target fuel pressure Pt after the pumping period T1 has elapsed. Similarly, in the second embodiment, the target fuel pressure Pt may be set as the estimated fuel pressure Pe. In this case, the control may be executed similarly after setting the first valve closing timing t1 to reach the target fuel pressure Pt.

  In the first and second embodiments, the alcohol mixing ratio AC is estimated for the high-pressure fuel system including the high-pressure fuel pump 20 and the delivery pipe 40. However, the alcohol mixing ratio is similarly applied to the low-pressure fuel system. Can be estimated. In this case, the alcohol mixing ratio can be estimated based on the amount of leakage through the micro passage formed in the low-pressure fuel system. Even in this case, the effect shown in the above (1) can be achieved.

  In addition, the formation place of the minute passage is not limited to the minute passage 27 shown in the first and second embodiments and the decompression hole 34a shown in the third embodiment. For example, in the first and second embodiments, the minute passage may be formed at any position between the high-pressure fuel pump 20 and the delivery pipe 40 in the fuel supply system. In the third embodiment, the minute passage may be formed at any position as long as the fuel pumped by the high-pressure fuel pump can leak from the delivery pipe. The minute passage may be a passage formed by design in the fuel supply system or a passage formed for calculating the leak amount. The opening area of the micro passage is preferably set to a size that is suitable for calculating the leak amount and does not hinder the fuel supply by the fuel pump.

  In each of the above embodiments, an example in which the alcohol mixture ratio AC is 0% as a mixed fuel in which alcohol and gasoline are mixed at a predetermined ratio is shown. However, the alcohol mixture ratio AC is limited to 0%. Absent. In short, it is sufficient that the estimated fuel supply amount Qe or the estimated fuel pressure Pe is determined in accordance with the alcohol mixture ratio AC. The relationship between the mixing ratio of each fuel in the mixed fuel and the estimated fuel supply amount or the estimated fuel pressure may be determined in advance by experiments or the like, or theoretically calculated from the design value of the fuel supply system. . When the actual fuel pressure P is smaller than the estimated fuel pressure Pe or the actual fuel supply amount Q is smaller than the estimated fuel supply amount Qe, the alcohol mixture ratio AC in the currently used fuel is compared. It can be determined that the ratio was lower than the predetermined ratio.

In each of the above embodiments, an example in which the amount of leakage is determined by calculation has been described. However, a mode in which the amount of leakage through a minute passage is directly detected may be employed.
In each of the above embodiments, an example in which a dedicated sensor for detecting the mixing ratio of each fuel in the mixed fuel is not provided has been described. However, after providing such a dedicated sensor, a mode in which a leak amount calculation process and an alcohol mixture ratio estimation process are executed when the sensor fails may be employed. In this case, appropriate control according to the mixture ratio can be continued even when the sensor fails.

  In each of the above embodiments, an example is shown in which the leak amount calculation process and the alcohol mixture ratio estimation process are executed as a series of processes. However, the leak amount calculation process and the alcohol mixing ratio may be executed separately. For example, the leak amount calculation process may be executed during idle operation suitable for the execution of the process, and the alcohol mixture ratio estimation process may be executed in another operating state based on the leak amount calculated previously.

  In the above embodiment, an example in which the present invention is applied to an internal combustion engine that uses a mixed fuel of alcohol and gasoline has been shown, but the present invention also applies to an engine that uses a mixed fuel composed of a combination of other fuels. The same applies. In short, if the engine uses two types of fuels having different viscosities, the concentration of each fuel contained in the mixed fuel currently in use can be estimated by applying the estimation device of the present invention.

The schematic block diagram which shows the fuel mixing ratio estimation apparatus of the internal combustion engine concerning 1st Embodiment with a fuel supply system. The flowchart which shows the process sequence about the control concerning the embodiment. The timing chart which shows the execution aspect about the control concerning the embodiment. The correlation diagram which shows the relationship between the pressure difference concerning the same embodiment, and the amount of leaks. It is a correlation diagram which shows the premise fact for demonstrating the embodiment, Comprising: (a) is a correlation diagram which shows the relationship between alcohol mixing ratio and a viscosity, (b) is a correlation diagram which shows the relationship between a viscosity and a leak amount. . The correlation diagram which shows the relationship between the leak amount concerning the same embodiment, and alcohol mixing ratio. The flowchart which shows the process sequence about the control concerning 2nd Embodiment. The timing chart which shows the execution aspect about the control concerning the embodiment. The correlation diagram which shows the relationship between the pressure difference concerning the same embodiment, and valve closing timing. The correlation diagram which shows the relationship between the timing difference concerning the same embodiment, and the amount of leaks. The flowchart which shows the process sequence about the control concerning 3rd Embodiment. The timing chart which shows the execution aspect about the control concerning the embodiment. The correlation diagram which shows the relationship between the pressure change concerning the same embodiment, and the amount of leaks.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 ... Fuel tank, 11 ... Low pressure fuel pump, 12 ... Low pressure fuel passage, 13 ... Low pressure pressure regulator, 14 ... Return passage, 15 ... Fuel filter, 20 ... High pressure fuel pump, 21 ... Cam shaft, 22 ... Cam, 22a ... Lifter, 23, 33 ... Coil spring, 24 ... Cylinder, 25 ... Plunger, 26 ... Pressurizing chamber, 27 ... Micro passage, 30 ... Electromagnetic spill valve (regulating valve), 31 ... Connection port, 32 ... Electromagnetic solenoid, 34 ... Discharge valve, 34a ... decompression hole, 40 ... delivery pipe, 40a ... fuel pressure sensor, 41 ... high pressure fuel passage, 50 ... fuel injection valve, 60 ... relief valve, 61 ... relief passage, 70 ... electronic control unit, 71 ... engine rotation Speed sensor 72 ... Cam position sensor 73 ... Accelerator depression amount sensor 74: Throttle valve opening sensor

Claims (12)

An apparatus for estimating a fuel mixture ratio of an internal combustion engine using a mixed fuel obtained by mixing two types of fuels having different viscosities,
A leak amount calculating means for calculating a leak amount of the mixed fuel through a micro passage formed in a fuel supply system for supplying the mixed fuel to the internal combustion engine;
A fuel mixture ratio estimation device for an internal combustion engine, comprising: a mixture ratio estimation unit that estimates a higher mixture ratio of the fuel having a higher viscosity in the mixed fuel as the leak amount is smaller. In the internal combustion engine fuel mixture ratio estimation apparatus according to claim 1,
The fuel supply system includes a high-pressure fuel pump that pumps the mixed fuel, and a delivery pipe that is connected to a fuel injection valve of each cylinder of the internal combustion engine and stores the mixed fuel pumped by the high-pressure fuel pump. ,
The leak amount calculation means supplies the estimated fuel supply amount when the mixed fuel in which each fuel is mixed at a predetermined ratio is supplied to the delivery pipe and the actual fuel supply amount actually supplied to the delivery pipe. A fuel mixture ratio estimation device for an internal combustion engine, wherein the leak amount is calculated based on a difference in amount. In the internal combustion engine fuel mixture ratio estimation apparatus according to claim 1,
The fuel supply system includes: a high-pressure fuel pump that pumps the mixed fuel; a delivery pipe that is connected to a fuel injection valve of each cylinder of the internal combustion engine and stores the mixed fuel pumped by the high-pressure fuel pump; A fuel pressure detecting means for detecting the actual fuel pressure in the delivery pipe,
The leak amount calculation means includes an estimated fuel pressure in the delivery pipe when a mixed fuel in which each fuel is mixed at a predetermined ratio is supplied to the delivery pipe, and the mixed fuel to be used is actually in the delivery pipe. The fuel mixture ratio estimation device for an internal combustion engine, wherein the leak amount is calculated based on a pressure difference with the actual fuel pressure in the delivery pipe when the fuel is supplied to the internal combustion engine. The fuel mixture ratio estimation apparatus for an internal combustion engine according to claim 2 or 3,
The high-pressure fuel pump includes a pressurizing chamber that pressurizes the mixed fuel by a plunger that is slidably inserted into a sliding hole, a fuel passage that supplies fuel to the pressurizing chamber, and the pressurizing chamber. A fuel mixing ratio of the internal combustion engine, characterized in that a fuel supply amount supplied from the pressurizing chamber to the delivery pipe is controlled through adjustment of an opening / closing timing of the regulating valve. Estimating device. In the internal combustion engine fuel mixture ratio estimation apparatus according to claim 4,
The leak amount calculation means is configured to set a state where the mixed fuel supplied to the delivery pipe is in a predetermined state, and when the mixed fuel in which each fuel is mixed at the predetermined ratio is supplied to the delivery pipe. The amount of leak is calculated based on a timing difference between the first valve closing timing of the regulating valve and the second valve closing timing of the regulating valve when the mixed fuel to be used is actually supplied to the delivery pipe. An apparatus for estimating a fuel mixture ratio of an internal combustion engine. The fuel mixture ratio estimation apparatus for an internal combustion engine according to claim 4 or 5,
The minute passage is a space formed between an inner peripheral surface of the sliding hole and an outer peripheral surface of the plunger. A fuel mixture ratio estimation device for an internal combustion engine, wherein: In the internal combustion engine fuel mixture ratio estimation apparatus according to claim 1,
The fuel supply system includes a high-pressure fuel pump that pumps the mixed fuel, and a delivery pipe that is connected to a fuel injection valve of each cylinder of the internal combustion engine and stores the mixed fuel pumped by the high-pressure fuel pump. ,
The fuel mixture ratio estimation device for an internal combustion engine, wherein the leak amount calculation means calculates a leak amount of the mixed fuel from the delivery pipe through the minute passage. In the internal combustion engine fuel mixture ratio estimation apparatus according to claim 7,
The fuel supply system further includes a fuel pressure detecting means for detecting an actual fuel pressure in the delivery pipe,
The fuel mixture ratio estimation device for an internal combustion engine, wherein the leak amount calculation means calculates the leak amount based on a change in the actual fuel pressure accompanying a leak of the mixed fuel through the minute passage. In the internal combustion engine fuel mixture ratio estimation apparatus according to claim 7 or 8,
The fuel passage ratio estimation device for an internal combustion engine, wherein the micro passage is a passage for leaking the mixed fuel pumped by the high-pressure fuel pump. In the internal combustion engine fuel mixture ratio estimation apparatus according to claim 9,
The high-pressure fuel pump includes a pressurizing chamber that pressurizes the mixed fuel, and a discharge valve that allows the mixed fuel to pass only from the pressurizing chamber toward the delivery pipe.
The micro passage is a pressure reducing hole that is provided in the discharge valve and allows the mixed fuel to pass from the delivery pipe in the direction of the pressurizing chamber. . The fuel mixture ratio estimation apparatus for an internal combustion engine according to any one of claims 1 to 10,
The apparatus for estimating a fuel mixture ratio of an internal combustion engine, wherein the leak amount calculation means calculates a leak amount of the mixed fuel through the minute passage during an idling operation of the internal combustion engine. The fuel mixture ratio estimation device for an internal combustion engine according to any one of claims 1 to 11,
The mixed fuel is a fuel in which gasoline and alcohol are mixed,
The fuel mixture ratio estimation device for an internal combustion engine, wherein the mixture ratio estimation means estimates an alcohol mixture ratio of the fuel mixture.

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