JP5315139B2 - Fuel supply device for internal combustion engine for alcohol mixed fuel - Google Patents

Description

  The present invention relates to a fuel supply device for an internal combustion engine for alcohol-mixed fuel that can use an alcohol-mixed fuel in which alcohol and gasoline are mixed at an arbitrary ratio.

  Emission regulations for internal combustion engines mounted on vehicles such as automobiles are becoming stricter year by year. Therefore, in order to reduce carbon dioxide emissions in response to these stricter exhaust gas regulations, an alcohol-mixed fuel internal combustion engine that can use an alcohol-mixed fuel in which alcohol such as bioethanol and gasoline are mixed in any proportion An institution is being developed.

  Depending on the country or region, there may be tax incentives for alcohol blended fuel or vehicles equipped with an alcohol blended fuel internal combustion engine. The use of internal combustion engines for alcohol blended fuel is expanding.

  However, alcohol generally has a characteristic that it is less likely to vaporize in a low temperature environment than gasoline. Therefore, in an internal combustion engine for alcohol-mixed fuel, when a fuel with a high alcohol concentration is used, the fuel is less likely to vaporize in a low temperature environment, and the engine cannot be started or the engine operation becomes unstable. There is a concern that

  On the other hand, in the fuel supply device for the alcohol-mixed fuel internal combustion engine described in Patent Document 1, a fuel is provided in the fuel supply passage, and the fuel in the low temperature environment is heated by heating the fuel in the passage with the heater. To promote vaporization.

JP-A-5-19587

  By the way, when the heater is provided in the fuel supply passage and the fuel is heated by the heater as described above, the fuel may be vaporized in the passage. For example, immediately after the energization of the heater is stopped when the engine is stopped, the fuel staying in the passage is gradually warmed by the residual heat of the heater, and there is a risk that fuel vapor is generated in the passage. is there.

  In addition, if fuel vapor is generated in the fuel supply passage, the fuel injection amount for the valve opening period of the fuel injection valve is shifted, so that appropriate fuel injection can be performed at the next engine operation. There is a risk of disappearing.

  The present invention has been made in view of the above circumstances, and an object thereof is to provide a fuel supply device for an alcohol-mixed fuel internal combustion engine capable of promoting the vaporization of fuel without using a heater.

In the following, means for achieving the above object and its effects are described.
The invention according to claim 1 is a fuel supply device for an alcohol-mixed fuel internal combustion engine capable of using a fuel in which alcohol and gasoline are mixed, and an intake passage to which fuel spray injected from a fuel injection valve is exposed Temperature estimation means for estimating the ambient temperature, which is the temperature of the air inside, concentration estimation means for estimating alcohol concentration, which is the concentration of alcohol contained in the fuel supplied to the fuel injection valve, and supply to the fuel injection valve A fuel pressure adjusting means for adjusting the fuel pressure, which is the pressure of the fuel to be generated, such that the fuel pressure increases as the ambient temperature is lower, and the fuel pressure increases as the alcohol concentration is higher. , “P” is the fuel pressure, “E” is the alcohol concentration, “T” is the ambient temperature, and “α”, “β ₁ ”, “β ₂ ”, “γ”, “K” are constants. ,under The fuel pressure adjusting means is controlled based on the fuel pressure “P” calculated using the above formula, and the fuel pressure is repeatedly adjusted during engine operation from start to stop of the internal combustion engine. The gist.

The particle size of the fuel spray droplets injected from the fuel injection valve becomes smaller as the pressure of the fuel supplied to the fuel injection valve is higher. The smaller the particle size of the droplets of the fuel spray, the more easily the droplets evaporate and the fuel vaporization is promoted. In this regard, in the configuration according to claim 1, the fuel pressure adjusting means is controlled on the basis of the atmospheric temperature, which is the temperature of the air in the intake passage to which the fuel spray is exposed, and the alcohol concentration of the fuel , During the engine operation from the start to the stop of the internal combustion engine, the fuel pressure is repeatedly adjusted . The fuel pressure is increased as the ambient temperature is lower and as the alcohol concentration is higher.

  Therefore, according to the above configuration, the fuel pressure is increased when the ambient temperature is low and the fuel is difficult to vaporize, or when the alcohol concentration is high and the fuel is difficult to vaporize. Thereby, the particle size of the droplets of the fuel spray injected from the fuel injection valve is reduced, and the vaporization of the fuel is promoted. That is, according to the structure of the said Claim 1, vaporization of a fuel can be accelerated | stimulated without using a heater by increasing a fuel pressure.

  Note that fuel vaporization can also be promoted by always maintaining the fuel pressure at a high level. However, if the fuel pressure is always kept high, the energy consumption for driving the fuel pump increases. On the other hand, according to the configuration of the first aspect, the fuel pressure is increased based on the low ambient temperature and the high alcohol concentration. For this reason, it is possible to effectively increase the fuel pressure when the fuel is not easily vaporized without unnecessarily increasing the fuel pressure. That is, fuel vaporization can be effectively promoted while suppressing an increase in energy consumption for driving the fuel pump.

The invention described in 請 Motomeko 2, in the fuel supply system for the alcohol-mixed fuel for an internal combustion engine according to claim 1, wherein the fuel pressure, fuel pressure "P" or higher value calculated by using the formula The gist of the present invention is to control the fuel pressure adjusting means.

When the fuel pressure adjusting means is controlled based on the fuel pressure “P” calculated using the above formula and the fuel pressure is adjusted, the fuel pressure “P” calculated using the formula is actually In addition to the method of controlling the fuel pressure adjusting means so as to make the fuel pressures coincide with each other, as described in claim 2 , the fuel pressure is a value equal to or higher than the fuel pressure “P” calculated using an equation. It is also possible to adopt a configuration that controls the fuel pressure adjusting means.

A third aspect of the present invention is the fuel supply apparatus for an internal combustion engine for alcohol-mixed fuel according to the first or second aspect , wherein the temperature estimating means includes means for detecting the temperature of air in the intake passage.

According to a fourth aspect of the present invention, there is provided a water temperature detecting means for detecting the engine cooling water temperature, and the temperature estimating means estimates the ambient temperature based on the engine cooling water temperature detected by the water temperature detecting means. It is a fuel supply apparatus of the internal combustion engine for alcohol mixed fuels as described in any one of 1-3 .

The invention according to claim 5 is provided with oil temperature detecting means for detecting the temperature of the lubricating oil, and the temperature estimating means determines the ambient temperature based on the temperature of the lubricating oil detected by the oil temperature detecting means. It is a fuel supply apparatus of the internal combustion engine for alcohol mixed fuels as described in any one of Claims 1-4 estimated.

As a specific configuration of the temperature estimation means for estimating the atmospheric temperature, a configuration in which means for detecting the temperature of the air in the intake passage (an intake temperature sensor or the like) is provided as described in claim 3. Can do. Further, as described in claim 4 and claim 5 , a water temperature detecting means or an oil temperature detecting means for detecting an engine cooling water temperature or a lubricating oil temperature having a high correlation with the temperature of the internal combustion engine that affects the ambient temperature. It is also possible to employ a configuration in which the ambient temperature is estimated based on the engine coolant temperature detected by these and the temperature of the lubricating oil. In addition, the structure which estimates atmospheric temperature combining these structures can also be employ | adopted.

The invention described in claim 6, as the concentration estimation means, claim 1-5 comprising means for detecting the concentration of alcohol contained fuel to the fuel in the fuel supply passage for supplying to the fuel injection valves A fuel supply device for an internal combustion engine for an alcohol-mixed fuel according to one item.

The invention described in Claim 7, the alcohol-mixed fuel for an internal combustion engine according to any one of claims 1 to 6, wherein the concentration estimation means estimates the alcohol concentration, based on the deviation of the air-fuel ratio control It is a fuel supply device.

As a specific configuration of the concentration estimating means for estimating the alcohol concentration, means for detecting the concentration of alcohol contained in the fuel in the fuel supply passage (alcohol concentration) in the fuel supply passage as described in claim 6. It is possible to employ a configuration in which an alcohol concentration is estimated based on the detected value. Further, as described in the seventh aspect , it is possible to adopt a configuration in which the alcohol concentration is estimated based on the deviation of the air-fuel ratio control accompanying the engine operation. Further, such a configuration may be combined, for example, a configuration in which a value detected by an alcohol concentration sensor is corrected based on a deviation in air-fuel ratio control, and a configuration in which the alcohol concentration is estimated based on the corrected value may be employed.

1 is a schematic diagram showing a schematic configuration of an internal combustion engine including a fuel supply device according to an embodiment of the present invention. The graph which shows the particle size of the droplet of the fuel spray injected from a fuel injection valve, and a fuel pressure. The flowchart which shows the flow of a series of processes of the fuel pressure control in the internal combustion engine concerning the embodiment. The map which shows the relationship between the alcohol concentration of a fuel and engine cooling water temperature, and the fuel pressure which fuel vaporizes favorably. The graph which shows the control aspect of the fuel pressure in the fuel supply apparatus concerning the example of a change of this invention.

  Hereinafter, the fuel supply device for an internal combustion engine for alcohol-mixed fuel according to the present invention is specifically described as a fuel supply device for an internal-combustion engine that can use an alcohol-mixed fuel obtained by mixing bioethanol, which is plant-derived ethanol, and gasoline, so-called flex fuel. A simplified embodiment will be described with reference to FIGS. FIG. 1 is a schematic diagram showing a schematic configuration of an internal combustion engine including a fuel supply device according to the present embodiment.

  As shown in FIG. 1, a piston 12 is accommodated in a cylinder 11 formed in a cylinder block 10 of the internal combustion engine so as to be able to reciprocate. In FIG. 1, for convenience of explanation, only one of a plurality of cylinders 11 is shown.

  A connecting rod 16 is connected to the piston 12, and the piston 12 is connected to a crankshaft (not shown) via the connecting rod 16. The cylinder block 10 is formed with a water jacket 17 through which engine coolant circulates so as to surround each cylinder 11.

  As shown in FIG. 1, a cylinder head 20 is assembled to the upper portion of the cylinder block 10. Thus, the combustion chamber 13 is defined by the inner peripheral surface of the cylinder 11, the upper surface of the piston 12, and the lower surface of the cylinder head 20. The cylinder head 20 is provided with an ignition plug 14 so as to protrude into each combustion chamber 13, and an intake port 21 and an exhaust port 22 communicating with each combustion chamber 13 are formed.

  Each intake port 21 is connected to an intake manifold (not shown) and constitutes a part of the intake passage 30. Each exhaust port 22 is connected to an exhaust manifold (not shown) to form a part of the exhaust passage 40. The intake passage 30 is provided with a throttle valve 33 that adjusts an intake air amount GA that is driven by a motor 33 a and introduced into the combustion chamber 13, and fuel is directed toward the combustion chamber 13. A fuel injection valve 34 for injecting fuel is provided for each cylinder 11.

  A fuel supply passage 52 is connected to each fuel injection valve 34, and the fuel stored in the fuel tank 50 is supplied through the fuel supply passage 52. As shown in the lower right side of FIG. 1, a fuel pump 51 is provided in the fuel tank 50. The fuel pump 51 is an electric pump and discharges fuel at a predetermined pressure during engine operation. A fuel supply passage 52 is connected to the fuel pump 51. The fuel supply passage 52 is connected to the fuel injection valve 34 as described above, and the fuel pressure-fed by the fuel pump 51 is supplied to the fuel injection valve 34 through the fuel supply passage 52.

  As shown in the center of FIG. 1, an alcohol concentration sensor 66 that detects the concentration of ethanol contained in the fuel supplied to the fuel injection valve 34 is provided in the vicinity of the fuel injection valve 34 in the fuel supply passage 52. .

  Further, as shown in the lower right portion of FIG. 1, a fuel pressure adjustment valve 53 and a return passage 54 are provided in the middle of the fuel supply passage 52. The return passage 54 is a passage for returning a part of the fuel pressure-fed by the fuel pump 51 to a portion upstream of the fuel pump 51 in the fuel supply passage 52, and as shown in FIG. It is connected to the fuel supply passage 52 through 53.

  The fuel pressure adjustment valve 53 has a function as a pressure regulator, and opens when the fuel pressure P, which is the pressure of fuel supplied to the fuel injection valve 34 through the fuel supply passage 52, becomes equal to or higher than the set pressure Ps. Part of the fuel pumped by the fuel pump 51 is returned to the upstream side of the fuel pump 51 through the return passage 54.

  The fuel pressure adjustment valve 53 is configured such that the set pressure Ps can be changed based on a command from the electronic control unit 100, and the fuel pressure P that is the pressure of the fuel supplied to the fuel injection valve 34 through the change of the set pressure Ps. It has a function to adjust.

  As shown in FIG. 1, the cylinder head 20 includes an intake valve 31 that communicates and blocks the intake passage 30 and the combustion chamber 13, and an exhaust valve 41 that communicates and blocks the exhaust passage 40 and the combustion chamber 13. Is provided.

  The intake valve 31 and the exhaust valve 41 are opened by the action of the intake camshaft and the exhaust camshaft that are driven as the crankshaft rotates. Specifically, when the intake camshaft and the exhaust camshaft rotate during engine operation, the intake valve 31 is opened by the action of the intake cam provided on the intake camshaft, and the action of the exhaust cam provided on the exhaust camshaft. The exhaust valve 41 is opened.

  The internal combustion engine is provided with various sensors for detecting the engine operating state. For example, an accelerator position sensor 61 provided on the accelerator pedal 60 detects an accelerator operation amount ACCP that is a depression amount of the accelerator pedal 60. The vehicle speed sensor 62 detects the vehicle speed SPD. The air flow meter 63 detects the intake air amount GA introduced into the combustion chamber 13. The crank angle sensor 64 detects an engine rotational speed NE that is the rotational speed of the crankshaft. A water temperature sensor 65 provided in the cylinder block 10 detects an engine cooling water temperature T that is the temperature of the engine cooling water circulating in the water jacket 17. As described above, the alcohol concentration sensor 66 detects the alcohol concentration E, which is the concentration of ethanol contained in the fuel supplied to the fuel injection valve 34.

  These various sensors 61 to 66 are connected to the electronic control device 100 that controls the internal combustion engine in an integrated manner, and the electronic control device 100 reads detection signals from these various sensors 61 to 66 and performs various types of engine control. Execute the control.

  For example, by controlling the motor 33a based on the engine rotational speed NE and the accelerator operation amount ACCP, the throttle valve 33 is driven to regulate the intake air amount GA, and the fuel injection valve 34 is adjusted in accordance with the intake air amount GA. The fuel injection amount is adjusted by controlling the valve opening period.

  Alcohol such as ethanol has a characteristic that it is less likely to vaporize in a low temperature environment than gasoline. Therefore, in an internal combustion engine that uses flex fuel, when using a fuel with a high ethanol concentration, the fuel is less likely to vaporize in a low temperature environment, making it impossible to start the engine or making the engine unstable. It may become.

  As shown in FIG. 2, the particle size D of the droplets of the fuel spray injected from the fuel injection valve 34 becomes smaller as the fuel pressure P, which is the pressure of the fuel supplied to the fuel injection valve 34, is higher. Further, the smaller the particle size D of the droplets of the fuel spray, the easier the fuel is vaporized.

Therefore, in the internal combustion engine according to the present embodiment, the fuel pressure P is adjusted by controlling the fuel pressure adjustment valve 53 in order to promote the vaporization of fuel in a low temperature environment.
Hereinafter, the fuel pressure control in the internal combustion engine according to the present embodiment will be described with reference to FIG. FIG. 3 is a flowchart showing a flow of a series of processes for fuel pressure control in the internal combustion engine according to the present embodiment. This fuel pressure control is repeatedly executed at a predetermined control cycle by the electronic control unit 100 during engine operation.

  As shown in FIG. 3, when the fuel pressure control is started, the electronic control unit 100 first, in step S100, as an alternative value of the atmospheric temperature, which is the temperature of the air to which the fuel injected from the fuel injection valve 34 is exposed, The engine cooling water temperature T detected by the water temperature sensor 65 is read.

Then, the process proceeds to step S200, and the alcohol concentration E detected by the alcohol concentration sensor 66 in step S200 is read.
When the engine cooling water temperature T and the alcohol concentration E are read in this way, the process proceeds to step S300, and the electronic control unit 100 calculates the target fuel pressure P based on the engine cooling water temperature T and the alcohol concentration E.

  Note that in the internal combustion engine of the present embodiment, the fuel pressure P is calculated using, for example, the relationship expressed by the following mathematical formula (1).

The mathematical formula (1) is derived as follows.

The amount Q of fuel vaporized per unit time increases as the particle diameter D of the fuel spray droplets decreases and as the evaporation rate constant C increases.
Therefore, for the amount Q of fuel vaporized per unit time, the relationship shown in the following mathematical formula (2) is established.

Further, as described above, the particle size D of the droplets of the fuel spray decreases as the fuel pressure P increases, and increases as the alcohol concentration E of the fuel increases.

  Therefore, the relationship represented by the following mathematical formula (3) is established for the particle size D of the droplets of the fuel spray.

Further, the evaporation rate constant C is larger as the difference between the engine cooling water temperature T, which is an alternative value of the ambient temperature that is the temperature of the air to which the injected fuel spray is exposed, and the fuel droplet surface temperature Ts (T). As the alcohol concentration E increases, it decreases as the alcohol concentration E increases.

  Therefore, for the fuel evaporation rate constant C, the relationship shown in the following formula (4) is established.

Note that “β ₁ ” in Equation (3) and “β ₂ ” in Equation (4) are coefficients indicating the degree of change in droplet diameter D and evaporation rate constant C with respect to change in alcohol concentration E, It is a positive value. These “β ₁ ” and “β ₂ ” are set empirically based on, for example, results of experiments performed in advance.

  Since the droplet surface temperature Ts (T) in the above equation (4) is a function of the engine cooling water temperature T, the droplet surface temperature Ts (T) is approximated as shown in the following equation (5). To do.

“Α” and “γ” are constants set based on the result of an experiment or the like, and are positive values.

  Thus, by approximating the droplet surface temperature Ts (T) as shown in Equation (5), the relationship shown in Equation (4) can be rewritten as shown in Equation (6) below. .

Then, by using the relationship shown in the equation (3) and the relationship shown in the equation (6), the equation (2) can be rewritten as shown in the following equation (7).

Furthermore, when this is rearranged, the following formula (8) is obtained.

By setting the right side of the formula (8) as a constant K as shown in the following formula (9), the formula (1) is derived based on the formula (9).

The constant K is a positive value.

  As shown by the arrows in FIG. 4, the fuel pressure P calculated using the relationship shown in the mathematical formula (1) is larger as the engine cooling water temperature T is lower and the ambient temperature is lower, and as the alcohol concentration E is higher. Value.

  FIG. 4 is a map showing the relationship between the alcohol concentration E and the engine cooling water temperature T and the fuel pressure P at which the fuel vaporizes satisfactorily. The solid line shown in FIG. 4 indicates that the fuel vaporizes well when the fuel pressure P is “P1”, “P2”, “P3”, “P4” (where P1 <P2 <P3 <P4). The boundary line of the density | concentration E and the engine cooling water temperature T is shown. That is, the lower right region of each solid line indicates that the fuel is vaporized well at the fuel pressure P, and the fuel is vaporized well even in a low temperature environment as the fuel pressure P is increased. It shows that it will become.

  In the internal combustion engine according to the present embodiment, Equation (1) derived as described above is used as a basic model equation, and the value of the constant K is used in a low-temperature environment based on the results of experiments and simulations. Even so, the value is set so that stable engine operation can be realized.

  Specifically, as shown by a point X in FIG. 4, when the engine coolant temperature T is “Tx” and the alcohol concentration E is “Ex”, the fuel pressure P calculated through the equation (1) is calculated. The value of the constant K is set so that the value always includes the point X in the lower right region from the boundary line as "P3" and "P4" in FIG.

As described above, in the fuel pressure control, the fuel pressure P is calculated using Equation (1) in which the constant K is set in this way.
Thus, when the target fuel pressure P is calculated based on the engine coolant temperature T and the alcohol concentration E using the relationship shown in Equation (1) in step S300, the process proceeds to step S400, and the electronic control unit 100 Based on the calculated fuel pressure P, the fuel pressure adjustment valve 53 is driven. That is, the fuel pressure adjustment valve 53 is driven so that the fuel pressure P matches the value of the fuel pressure P calculated through step S300.

When the fuel pressure adjustment valve 53 is driven based on the value of the fuel pressure P calculated using the relationship expressed by the formula (1) in this way, the electronic control unit 100 once ends this process.
Thus, by controlling the fuel pressure regulating valve 53 through the fuel pressure control according to the present embodiment, the fuel pressure P becomes higher as the engine cooling water temperature T is lower and the ambient temperature is lower, and the fuel is higher as the alcohol concentration E is higher. The fuel pressure P is adjusted so that the pressure P increases.

According to the embodiment described above, the following effects can be obtained.
(1) The particle diameter D of the droplets of the fuel spray injected from the fuel injection valve 34 decreases as the fuel pressure P increases. The smaller the particle diameter D of the fuel spray droplets, the easier the droplets evaporate, and the fuel vaporization is promoted. In this regard, in the internal combustion engine of the above embodiment, the target fuel pressure P is calculated based on the engine coolant temperature T and the alcohol concentration E, and the fuel pressure adjustment valve 53 is controlled based on this. ing. The fuel pressure P is increased as the engine coolant temperature T is estimated to be lower and the ambient temperature is lower, and as the alcohol concentration E is higher.

  Therefore, the fuel pressure P is increased when the ambient temperature is low and the fuel is difficult to vaporize, or when the alcohol concentration E is high and the fuel is difficult to vaporize. Thereby, the particle diameter D of the droplets of the fuel spray injected from the fuel injection valve 34 is reduced, and the vaporization of the fuel is promoted. That is, by increasing the fuel pressure P, fuel vaporization can be promoted without using a heater.

  (2) Vaporization can also be promoted by, for example, mounting a large fuel pump to always keep the fuel pressure P at a high level. However, if the fuel pressure P is always kept high, the amount of energy consumed for driving the fuel pump increases. On the other hand, according to the configuration of the above embodiment, the fuel pressure P is increased based on the low engine cooling water temperature T and the low ambient temperature and the high alcohol concentration E. Therefore, the fuel pressure P can be effectively increased when the fuel is not easily vaporized without unnecessarily increasing the fuel pressure P. That is, fuel vaporization can be effectively promoted while suppressing an increase in energy consumption for driving the fuel pump.

In addition, the said embodiment can also be implemented with the following forms which changed this suitably.
In the above embodiment, the target fuel pressure P is calculated for each predetermined control cycle using the relationship expressed by the mathematical formula (1), and the actual fuel pressure P is made to coincide with the calculated fuel pressure P. The configuration for driving the fuel pressure regulating valve 53 is shown in FIG.

  On the other hand, a threshold is set for the engine coolant temperature T and the alcohol concentration E, and the fuel pressure P is set so that it does not fall below the value of the fuel pressure P calculated using the relationship shown by the equation (1). It is also possible to adopt a configuration that switches in stages.

  For example, as shown in FIG. 5, the low-temperature fuel pressure Pc is set so as not to fall below the value of the fuel pressure P calculated using the relationship shown in Formula (1) (the dashed line in FIG. 5). When the engine cooling water temperature T is lower than the reference temperature Tc, a configuration in which the fuel pressure P is increased to the low temperature fuel pressure Pc as shown by an arrow in FIG. 5 may be employed.

  In the above embodiment, the configuration in which the alcohol concentration sensor 66 is provided as the alcohol concentration estimation means for estimating the concentration of ethanol contained in the fuel supplied to the fuel injection valve 34 has been described. Instead of the provided configuration, a configuration in which the alcohol concentration E is estimated based on the magnitude of the deviation of the air-fuel ratio control accompanying the engine operation can be adopted.

  In the above embodiment, the water temperature sensor is a water temperature detecting means for detecting the engine cooling water temperature T as the atmospheric temperature estimating means for estimating the atmospheric temperature by using the engine cooling water temperature T as an alternative value of the atmospheric temperature. A configuration using 65 is shown. On the other hand, as an ambient temperature estimating means, an oil temperature sensor which is an oil temperature detecting means for detecting the temperature of lubricating oil for lubricating each part of the internal combustion engine is provided, and the ambient temperature is estimated based on the temperature of the lubricating oil. Also, it is possible to employ an arrangement in which an intake air temperature sensor, which is means for directly detecting the temperature of the air in the intake port 21, is provided, and the ambient temperature is directly detected.

  In the above-described embodiment, the fuel pressure adjusting valve 53 and the return passage 54 are provided in the fuel supply passage 52 as the fuel pressure adjusting means. However, the pressure of the fuel supplied to the fuel injection valve 34 is changed. As long as it can be configured, the configuration of the fuel pressure adjusting means can be changed as appropriate.

DESCRIPTION OF SYMBOLS 10 ... Cylinder block, 11 ... Cylinder, 12 ... Piston, 13 ... Combustion chamber, 14 ... Spark plug, 16 ... Connecting rod, 17 ... Water jacket, 20 ... Cylinder head, 21 ... Intake port, 22 ... Exhaust port, 30 ... Intake passage, 31 ... Intake valve, 33 ... Throttle valve, 33a ... Motor, 34 ... Fuel injection valve, 40 ... Exhaust passage, 41 ... Exhaust valve, 50 ... Fuel tank, 51 ... Fuel pump, 52 ... Fuel supply passage, 53 DESCRIPTION OF SYMBOLS ... Fuel pressure regulating valve, 54 ... Return passage, 60 ... Accelerator pedal, 61 ... Accelerator position sensor, 62 ... Vehicle speed sensor, 63 ... Air flow meter, 64 ... Crank angle sensor, 65 ... Water temperature sensor, 66 ... Alcohol concentration sensor, 100 ... electronic control unit.

Claims (7)

A fuel supply device for an internal combustion engine for an alcohol-mixed fuel capable of using a fuel in which alcohol and gasoline are mixed,
Temperature estimation means for estimating an ambient temperature, which is a temperature of air in an intake passage to which fuel spray injected from the fuel injection valve is exposed, and alcohol which is a concentration of alcohol contained in the fuel supplied to the fuel injection valve Concentration estimating means for estimating the concentration; and fuel pressure adjusting means for adjusting the fuel pressure, which is the pressure of the fuel supplied to the fuel injection valve,
The fuel pressure is higher as the ambient temperature is lower, and the fuel pressure is higher as the alcohol concentration is higher.
When “P” is the fuel pressure, “E” is the alcohol concentration, “T” is the atmospheric temperature, and “α”, “β ₁ ”, “β ₂ ”, “γ”, “K” are constants,
The fuel pressure adjusting means is controlled based on the fuel pressure “P” calculated using the above formula, and the fuel pressure is repeatedly adjusted during engine operation from start to stop of the internal combustion engine. A fuel supply device for an alcohol-mixed fuel internal combustion engine. The fuel supply device for an internal combustion engine for alcohol-mixed fuel according to claim 1 ,
The fuel supply device for an alcohol-mixed fuel internal combustion engine, wherein the fuel pressure adjusting means is controlled so that the fuel pressure is equal to or higher than a fuel pressure “P” calculated using the mathematical formula. The temperature as an estimation unit, a fuel supply system of an alcohol blended fuel for an internal combustion engine according to claim 1 or 2 comprising means for detecting the temperature of the air in the intake passage. Comprising a water temperature detecting means for detecting an engine coolant temperature, said temperature estimation means according to any one of claims 1 to 3 for estimating the ambient temperature on the basis of the engine cooling water temperature detected by the coolant temperature detecting means A fuel supply device for an internal combustion engine for alcohol-mixed fuel. Comprising an oil temperature detecting means for detecting a temperature of lubricating oil, it claims 1-4, wherein the temperature estimating means for estimating the ambient temperature based on the temperature of lubricating oil detected by the oil temperature detecting means one A fuel supply device for an internal combustion engine for an alcohol-mixed fuel according to item 2. As the density estimating means, for alcohol-mixed fuel as claimed in any one of claims 1 to 5, comprising means for detecting the concentration of alcohol contained fuel to the fuel in the fuel supply passage for supplying to the fuel injection valves A fuel supply device for an internal combustion engine. The fuel supply device for an alcohol-mixed fuel internal combustion engine according to any one of claims 1 to 6 , wherein the concentration estimation means estimates the alcohol concentration based on a deviation in air-fuel ratio control.