JP2009203814A - Fuel supply control device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fuel supply control device accurately detecting behavior of a fuel pump. <P>SOLUTION: A pressure regulator 17 is provided in a fuel supply pipe 15 of an internal combustion engine 10. The pressure regulator 17 discharges fuel from the fuel supply pipe 15 when the fuel pressure in the fuel supply pipe 15 becomes higher than a prescribed adjustment pressure. ECU 31 controls drive of a fuel pump 14 to keep fuel the pressure in the fuel supply pipe 15 at a target pressure. Especially, the ECU 31 detects the behavior of the fuel pump 14 while controlling the fuel pressure by setting a target value higher than the adjustment pressure. In this case, the behavior can be detected under a condition where the fuel pressure in the fuel supply pipe 15 is stabilized near the adjustment pressure and the behavior of the fuel pump 14 is stabilized. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a fuel supply control device that controls driving of a fuel pump that supplies fuel to an internal combustion engine.

In recent years, an internal combustion engine that can use various fuels (fossil fuels, alcohol fuels, and mixed fuels thereof) has been developed from the viewpoint of effective use of resources (see, for example, Patent Document 1). In such an internal combustion engine, the behavior of the fuel pump changes according to the alcohol concentration of the fuel. That is, alcohol fuel has a higher viscosity than fossil fuel. Therefore, the higher the alcohol concentration of the fuel, the higher the viscosity of the fuel and the greater the load applied to the fuel pump. Thereby, the behavior of the fuel pump changes according to the alcohol concentration of the fuel. Therefore, in an engine system mainly composed of an internal combustion engine capable of using various types of fuel, it is conceivable to control the internal combustion engine based on the behavior of the fuel pump.
Japanese Patent No. 3903943

  By the way, from the viewpoint of improving the detection accuracy of the behavior of the fuel pump, it is desirable to detect the behavior of the fuel pump in a stable state. Furthermore, the change in the fuel pressure in the fuel supply pipe or the delivery pipe in the delivery pipe, which is the destination of the fuel delivered by the fuel pump, affects the behavior of the fuel pump. Therefore, it is desirable to detect the behavior of the fuel pump in a state where the fuel pressure in the fuel supply path is stabilized.

  However, when the fuel pump is operated, the fuel pressure increases accordingly. Therefore, it is not easy to accurately detect the behavior of the fuel pump in a state where both the behavior of the fuel pump and the fuel pressure in the fuel supply path are stabilized.

  The present invention has been made in order to solve the above-described problems, and has as its main object to provide a fuel supply control device that accurately detects the behavior of a fuel pump.

  Hereinafter, means for solving the above-described problems and the effects thereof will be described.

  The present invention is applied to a fuel supply apparatus including an electric fuel pump that sends fuel to a fuel supply path of an internal combustion engine, and a fuel discharge unit that discharges fuel from the fuel supply path and returns the fuel to a fuel tank. It is a fuel supply control apparatus which controls the drive of this. In particular, the invention according to claim 1 detects the behavior of the fuel pump when the fuel discharge portion is in the fuel discharge state.

  In the fuel discharge state of the fuel discharge section, even if the operation of the fuel pump is continued, the fuel in the fuel supply path is discharged and the fuel pressure in the fuel supply path is stabilized. Further, in the fuel discharge state of the fuel discharge portion, the operation of the fuel pump can be stabilized by continuing the operation of the fuel pump. Therefore, according to the first aspect of the present invention, it is possible to accurately detect the behavior of the fuel pump in a state where both the behavior of the fuel pump and the fuel pressure in the fuel supply path are stabilized.

  When fuel pressure control is performed by a fuel pump so that the fuel pressure in the fuel supply path becomes the target pressure, the fuel in the fuel supply path is discharged when the fuel pressure in the fuel supply path is higher than a predetermined adjustment pressure. The pressure regulator to be used can be employed as the fuel discharge section (claim 2). In this case, by performing the fuel pressure control so that the target pressure of the fuel pressure control is higher than the adjustment pressure of the pressure regulator, the fuel discharge portion can be forced into the fuel discharge state.

  As described above, the change in the fuel pressure in the fuel supply path affects the behavior of the fuel pump. Therefore, in the invention according to the third aspect, the behavior of the fuel pump is detected after the fuel discharge portion is brought into the fuel discharge state when the internal combustion engine is stopped. As a result, the behavior of the fuel pump can be detected with higher accuracy in a state where the change in fuel pressure associated with the fuel supply to the internal combustion engine is eliminated.

  In the fourth aspect of the invention, the alcohol concentration of the fuel supplied to the internal combustion engine is estimated based on the behavior of the fuel pump detected by the first aspect of the invention.

  As the alcohol concentration of the fuel changes, the viscosity of the fuel changes. As the fuel viscosity changes, the fuel pump load changes. When the load of the fuel pump changes, the behavior of the pump unit changes. From the above, it can be seen that the behavior of the fuel pump changes as the alcohol concentration of the fuel changes.

  Focusing on this point, the alcohol concentration can be estimated based on the behavior of the fuel pump as described above. As described above, according to any one of the first to third aspects, the behavior of the fuel pump can be detected with high accuracy. Therefore, the alcohol concentration of the fuel can be accurately estimated based on the behavior of the fuel pump detected by the invention according to any one of claims 1 to 3.

  The alcohol concentration of the fuel is changed by supplying a fuel having an alcohol concentration different from that in the fuel tank. Therefore, it is desirable to estimate the alcohol concentration of fuel for each refueling.

  Therefore, in the invention described in claim 5, every time fuel supply to the fuel tank is detected, the behavior of the fuel pump is detected after the fuel discharge portion is set in the fuel discharge state. Thereby, the change in the alcohol concentration of the fuel can be effectively reflected in the control of the internal combustion engine.

  The present embodiment embodies the present invention as an engine system mainly composed of a vehicle-mounted internal combustion engine, and the detailed configuration thereof will be described below.

  First, a schematic configuration of this engine system will be described with reference to FIG. In FIG. 1, the internal combustion engine 10 is a multi-cylinder (for example, four cylinders) internal combustion engine, but one of the cylinders is shown. Further, the internal combustion engine 10 is assumed to be capable of using various fuels (fossil fuel, alcohol fuel, and mixed fuel of these fuels). The present invention can also be applied to a single cylinder internal combustion engine.

  An injector 12 for injecting fuel is provided in the intake passage 11 of each cylinder of the internal combustion engine 10 shown in FIG. The fuel stored in the fuel tank 13 is supplied to the injector 12. Specifically, the fuel in the fuel tank 13 is pumped up by the fuel pump 14 and supplied into the delivery pipe 16 via the fuel supply pipe 15, and the fuel in the delivery pipe 16 is supplied to the injector 12. Yes.

  The fuel supply pipe 15 is provided with a pressure regulator 17 as a fuel discharge portion. The pressure regulator 17 is a mechanical pressure reducing valve, and is opened when the fuel pressure in the fuel supply pipe 15 becomes equal to or higher than the adjustment pressure. Thus, excess fuel is returned from the fuel supply pipe 15 to the fuel tank 13 via the return pipe 18. Alternatively, a pressure regulator 17 may be provided in the delivery pipe 16 so that excess fuel is returned from the delivery pipe 16 to the fuel tank 13.

  The fuel supply pipe 15 is further provided with a fuel filter 19. As a result, the fuel filtered by the fuel filter 19 is supplied into the delivery pipe 16. The fuel tank 13 is provided with a fuel filler opening and closing by a fuel cap (not shown).

  The fuel pump 14 is an electric pump that uses the DC motor 20 as a power source, and includes a pump unit 21 that is driven by the DC motor 20 to pump fuel. The DC motor 20 can be supplied with power from a backup power source such as an in-vehicle battery in addition to a generator such as an alternator driven by the internal combustion engine 10. Thereby, the DC motor 20 can be operated (rotated) even when the internal combustion engine 10 is stopped. In the present embodiment, the DC motor 20 is a direct current brushless motor. The power source (electric motor) of the fuel pump 14 may be an AC motor or a brush motor.

  FIG. 2 is a diagram showing the pump unit 21 of the fuel pump 14. As shown in FIG. 2, in this embodiment, the pump unit 21 is a turbine-type pump unit, and includes a cover 23 having a suction port 22, a casing 25 having a discharge port 24 (see FIG. 2B), It is comprised with the disk-shaped impeller 26 accommodated in the cover 23 and the casing 25 rotatably. On the outer periphery of the impeller 26, many blade grooves 26a penetrating in the plate thickness direction are formed in the rotation direction. A casing groove 23 a and a cover groove 25 a extending in the rotation direction of the impeller 26 are formed at positions facing the blade groove 26 a in the cover 23 and the casing 25, respectively. In this case, when the impeller 26 is rotated by being driven by the DC motor 20, a pressure difference is generated before and after the blade groove 26a due to fluid friction. By repeating this operation in a large number of blade grooves 26a, a vortex is generated and the fuel pressure rises. The fuel thus boosted is sent out (pressure fed) to the delivery pipe 16 side through the discharge port 24. The space in the blade groove 26a corresponds to the “pressure part”.

  In addition, as a pump part, it is not restricted to a turbine type thing, For example, you may employ | adopt a rotor type thing. Further, in the following description, the portion of the fuel passage formed in the fuel pump 14 on the downstream side of the pump portion 21, the fuel passage in the fuel supply pipe 15, and the fuel passage in the delivery pipe 16 are referred to as “fuel supply passage”. "

  As shown in FIG. 1, the DC motor 20 is connected to a pump controller 30, and the pump controller 30 is connected to an ECU 31. The ECU 31 is an electronic control unit mainly composed of a known microcomputer provided with a CPU, a memory and the like. In addition to the pump controller 30 described above, the ECU 31 includes an intake pressure sensor 32 that detects the pressure (intake pressure) in the intake passage 11, a crank angle sensor 33 that detects the rotational angle position of the crankshaft 27 of the internal combustion engine 10, A fuel pressure sensor 34 for detecting the fuel pressure in the fuel supply path, a fuel temperature sensor 35 for detecting the temperature (fuel temperature) of the fuel in the fuel supply path, a fuel inlet opening / closing sensor 36 for detecting the opening / closing of the fuel inlet by the fuel cap, etc. The various sensors are connected.

  The ECU 31, the fuel pressure sensor 34, the fuel temperature sensor 35, and the fuel filler opening / closing sensor 36 are operable even when the internal combustion engine 10 is stopped, as with the DC motor 20. The fuel pressure sensor 34 and the fuel temperature sensor 35 may each detect a fuel pressure and a fuel temperature in a portion of the fuel passage formed in the fuel pump 14 on the downstream side of the pump portion 21, or may be a fuel supply pipe. The fuel pressure and fuel temperature in 15 may be detected, or the fuel pressure and fuel temperature in the delivery pipe 16 may be detected.

  ECU31 controls each part of an engine system by running the program memorized by memory with CPU. For example, the ECU 31 controls fuel injection by the injector 12 based on detection signals from the intake pressure sensor 32 and the crank angle sensor 33. Further, the ECU 31 calculates the fuel pressure (actual fuel pressure) of the fuel supply path based on the detection signal of the fuel pressure sensor 34, and uses the pump controller 30 to generate electric power corresponding to the pressure difference between the calculated actual fuel pressure and the target pressure. The actual fuel pressure is controlled to the target pressure by supplying to 20.

  Next, this actual fuel pressure feedback control (fuel pressure feedback control) will be described in detail with reference to FIG. FIG. 3 is a timing chart showing the fuel pressure feedback control. FIG. 3A is a control signal (pump drive control signal) from the ECU 31 to the pump controller 30, and FIG. 3B is a rotation speed of the DC motor 20 (pump rotation speed). (C) indicates the fuel pressure (actual fuel pressure) in the delivery pipe 16. In FIG. 3, it is assumed that the amount of power supplied to the fuel pump 14 is duty controlled. Further, it is assumed that the target value (target pressure) of the fuel pressure in the delivery pipe 16 is set to Ptrg1 which is less than the adjustment pressure Preg of the pressure regulator 17.

  When power supply to the fuel pump 14 is started under the control of the ECU 31 at the timing t1 shown in FIG. 3, that is, when a pump drive control signal having a predetermined duty ratio is input from the ECU 31 to the pump controller 30, the duty ratio depends on the duty ratio. Electric power is supplied from the pump controller 30 to the fuel pump 14, and the fuel pump 14 is started.

  Thereafter, at timings t1 to t2, the DC motor 20 rotates while receiving a load torque due to the viscosity of the fuel, and the pump rotation speed gradually increases. As a result, the amount of fuel discharged by the fuel pump 14 increases, and the actual fuel pressure increases. At this time, the rate of increase in actual fuel pressure (the rate of increase per unit time) is not constant. That is, at the timings t1 to t2, the pump rotation speed is gradually increased as described above, and therefore the rate of increase in the actual fuel pressure gradually increases.

  At the timing t2 to t3 when the pump rotation speed is stabilized at N1, the rate of increase in the actual fuel pressure is constant. The rotational speed at which the pump rotational speed is stabilized is determined according to the alcohol concentration (fuel viscosity) of the fuel, and is considered to decrease as the alcohol concentration of the fuel increases.

  When the actual fuel pressure reaches the target pressure Ptrg1 at timing t3, the power supply to the fuel pump 14 is stopped, that is, the duty ratio of the pump drive control signal becomes 0 by the control of the ECU 31. As a result, the actual fuel pressure becomes constant at the target pressure Ptrg1.

  By the way, the theoretical air-fuel ratio of alcohol fuel is lower than the theoretical air-fuel ratio of fossil fuel, and the octane number of alcohol fuel is higher than the octane number of gasoline. Therefore, for example, if the fuel injection amount control set for the fossil fuel is applied to the internal combustion engine 10 supplied with the alcohol fuel as it is, there is a concern that drivability and emission are deteriorated.

  Therefore, in this embodiment, the alcohol concentration of the fuel is estimated, and various controls including fuel injection control are performed based on the estimated value. Hereinafter, characteristics of the alcohol concentration estimation process of the present embodiment will be described with reference to FIGS. 3 and 4. FIG. 4 is a timing chart showing fuel pressure feedback control as in FIG.

  As described above, in the fuel pump 14, the fuel is sequentially pumped to the delivery pipe 16 side by the numerous blade grooves 26a. Therefore, when the fuel pump 14 is operated, the actual fuel pressure pulsates due to fuel pumping by the fuel pump 14 as shown in FIG.

  Here, the higher the alcohol concentration of the fuel, the higher the viscosity of the fuel, the higher the fuel viscosity, the lower the pump rotation speed, and the lower the pump rotation speed, the longer the pulsation cycle of the actual fuel pressure. That is, the pulsation cycle of the actual fuel pressure increases as the alcohol concentration increases.

  Focusing on this point, in this embodiment, the fuel pressure (actual fuel pressure) of the fuel supply path is detected, the pulsation cycle of the actual fuel pressure is calculated based on the detection result, and the alcohol concentration is calculated based on the calculated pulsation cycle. I try to estimate.

  In addition, the alcohol concentration estimation process of this embodiment has the following four characteristics.

  First, when the fuel pressure feedback control is performed, the power supply to the fuel pump 14 is stopped when the actual fuel pressure reaches the target pressure (see timing t3 in FIG. 3). Therefore, the period in which the pulsation of the actual fuel pressure can be detected is limited to the period from the start of the fuel pump 14 until the actual fuel pressure reaches the target pressure (see timings t1 to t3 in FIG. 3). Further, the pulsation cycle of the actual fuel pressure is not constant during the period when the pump rotation speed is not stable (see timings t1 to t2 in FIG. 3). Therefore, it is desirable to detect the actual fuel pressure in a state where the pump rotation speed is stable and calculate the pulsation cycle of the actual fuel pressure based on the detection result. In this case, the period in which the pulsation of the actual fuel pressure can be detected is further limited (see timings t2 to t3 in FIG. 3). Further, during the period in which the actual fuel pressure is increasing, the behavior of the fuel pump 14 changes with the increase, and consequently the pulsation cycle of the actual fuel pressure changes (see timings t1 to t3 in FIG. 3). Therefore, it is desirable to detect the actual fuel pressure in a state where the actual fuel pressure is stable, and to calculate the pulsation cycle of the actual fuel pressure based on the detection result. However, during the period in which the actual fuel pressure is stable at the target pressure, the power supply to the fuel pump 14 is stopped, and the pulsation of the actual fuel pressure cannot be detected (see timing t3 and after in FIG. 3).

  Therefore, in this embodiment, the stable period of the pump rotation speed is extended. Specifically, when executing the alcohol concentration estimation process, the target pressure in the feedback control of the actual fuel pressure is set to be higher than the adjustment pressure of the pressure regulator 17.

  This operation will be described with reference to FIG. 4. The actual fuel pressure starts to increase at the timing t11 when the fuel pump 14 is started. When the actual fuel pressure reaches the adjustment pressure Preg (see timing t13), excess fuel in the fuel supply pipe 15 is returned to the fuel tank 13 by the pressure regulator 17 thereafter. As a result, macroscopically, the actual fuel pressure becomes constant near the adjustment pressure Preg of the pressure regulator 17, and microscopically, the actual fuel pressure pulsates near the adjustment pressure Preg. Accordingly, the operation of the fuel pump 14 is continued without the actual fuel pressure reaching the target pressure Ptrg2, and as a result, the stable period of the pump rotation speed is extended (see timing t13 and thereafter in FIG. 4C).

  Thus, the stable period of the pump rotation speed is extended, the actual fuel pressure is detected during the stable period, and the pulsation cycle of the actual fuel pressure is calculated based on the detection result. As a result, an accurate pulsation cycle of the actual fuel pressure can be calculated, and as a result, the alcohol concentration of the fuel can be accurately estimated.

  Second, in the present embodiment, the alcohol concentration estimation process is executed before the internal combustion engine 10 is started for the following reason.

  When the fuel injection by the injector 12 is being performed, the actual fuel pressure changes due to the fuel injection. Therefore, it is desirable to detect the actual fuel pressure in a state where the fuel injection by the injector 12 is not executed (fuel injection stop state) and calculate the pulsation cycle of the actual fuel pressure based on the detection result. As a result, it is possible to calculate a more accurate pulsation cycle of the actual fuel pressure by eliminating the change in the actual fuel pressure due to fuel injection, and to estimate the alcohol concentration of the fuel more accurately.

  It is desirable to estimate the alcohol concentration of the fuel before starting the internal combustion engine 10. Thereby, the estimation result can be reflected in the control of the engine system immediately after the internal combustion engine 10 is started.

  For the above reason, in this embodiment, the alcohol concentration estimation process is executed before the internal combustion engine 10 is started.

  Third, the alcohol concentration of the fuel changes by supplying a fuel having an alcohol concentration different from that of the fuel in the fuel tank 13. Therefore, in this embodiment, the alcohol concentration of the fuel is estimated for each refueling. Thereby, the change in the alcohol concentration of the fuel can be effectively reflected in the control of the engine system.

  Fourth, the viscosity of the fuel changes not only with the alcohol concentration of the fuel but also with the temperature (fuel temperature) of the fuel. Therefore, in this embodiment, in the alcohol concentration estimation process, the alcohol concentration is estimated based on the fuel temperature in addition to the pulsation cycle of the actual fuel pressure. As a result, a more accurate pump rotation speed can be calculated, and the alcohol concentration of the fuel can be estimated with higher accuracy.

  Next, the flow of the alcohol concentration estimation process will be described with reference to FIG. FIG. 5 is a flowchart showing the flow of the alcohol concentration estimation program. This program is executed by the ECU 31. Specifically, when the fuel filler port is closed by the fuel cap, a detection signal indicating the closure of the fuel filler port is output from the fuel filler opening / closing sensor 36. The ECU 31 is activated by this signal, and then the alcohol concentration estimation program is repeatedly executed by the ECU 31 at a predetermined cycle.

  In step S <b> 10 shown in FIG. 5, the ECU 31 sets the target pressure for the fuel pressure feedback control to a pressure higher than the adjustment pressure of the pressure regulator 17. In subsequent step S <b> 11, the ECU 31 starts the fuel pump 14 by the pump controller 30. In subsequent step S12, the ECU 31 calculates the actual fuel pressure Pf (i) based on the detection signal of the fuel pressure sensor.

  In step S13, the ECU 31 determines whether or not the actual fuel pressure is stable. For example, the ECU 31 compares the actual fuel pressure Pf (i) with the adjustment pressure of the pressure regulator 17. Further, the ECU 31 determines whether or not the rate of increase of the actual fuel pressure, that is, the difference between the current value Pf (i) of the actual fuel pressure and the previous value Pf (i-1) is equal to or less than a predetermined value. The ECU 31 determines that the actual fuel pressure is stable when the actual fuel pressure Pf (i) is close to the adjustment pressure and the rate of increase of the actual fuel pressure is equal to or less than a predetermined value. When the ECU 31 determines that the pump rotation speed is stable, the ECU 31 proceeds to step S14. When the ECU 31 determines that the actual fuel pressure is not stable, the ECU 31 ends the execution of the current program.

  In this embodiment, it is assumed that the pump rotation speed is always stable in a state where the actual fuel pressure is stable, and it is not determined whether the pump rotation speed is stable. However, in this step, it is determined whether or not the pump rotation speed is stable. When it is determined that the actual fuel pressure and the pump rotation speed are stable, the process proceeds to step S14, and either the actual fuel pressure or the pump rotation speed is determined. May be terminated when it is determined that the program is not stable.

  In step S14, the ECU 31 stores the actual fuel pressure Pf (i) calculated in step S12 and the power supply amount to the fuel pump 14. For example, the ECU 31 calculates the power supply amount to the fuel pump 14 based on the duty ratio of the pump drive control signal and the drive voltage of the fuel pump 14 by the pump controller 30, and the actual fuel pressure Pf (i) is calculated together with the calculated power supply amount. Remember.

  In subsequent step S15, the ECU 31 determines whether or not the number of data of the actual fuel pressure and the amount of power supply is equal to or greater than the number (predetermined number) N1 sufficient for estimating the alcohol concentration. If the ECU 31 determines that the actual fuel pressure and the amount of power supply are greater than or equal to the predetermined number N1, the ECU 31 proceeds to step S16, and determines that the actual fuel pressure and the amount of power supply is less than the predetermined number N1. The execution of this program is terminated.

  In step S16, the ECU 31 calculates the pulsation cycle of the actual fuel pressure based on the N1 actual fuel pressures stored as the processing result of step S14. For example, the ECU 31 detects a plurality of peaks of the fuel pressure pulsation based on the N1 actual fuel pressures, and calculates an interval between these peaks as a pulsation cycle of the actual fuel pressure. The actual fuel pressure sampling period, that is, the execution period of the alcohol concentration estimation program by the ECU 31 is set to a time sufficiently shorter than the minimum value of the actual fuel pressure pulsation period. The minimum value of the pulsation cycle of the actual fuel pressure may be a value calculated in advance by the maximum value of the pump rotation speed and the number of blade grooves 26a formed in the rotation direction of the impeller 26, or based on the duty ratio of the pump drive control signal. The value calculated each time may be used.

  In subsequent step S17, the ECU 31 calculates the pump rotation speed based on the pulsation cycle of the fuel pressure.

  In subsequent step S18, the ECU 31 calculates the viscosity of the fuel based on the amount of power supplied to the fuel pump 14 and the pump rotation speed. For example, the ECU 31 calculates the representative values (average value, median value, mode value, etc.) based on the N1 power supply amounts stored as the processing result of step S14. Then, the ECU 31 refers to the map using the power supply amount to the fuel pump 14, the pump rotation speed, and the viscosity of the fuel as parameters, and calculates the fuel from the pump rotation speed calculated in step S 16 and the representative value of the calculated power supply amount. Viscosity is calculated.

  In subsequent step S19, the ECU 31 calculates the alcohol concentration of the fuel based on the fuel viscosity and the fuel temperature. For example, the ECU 31 calculates the fuel temperature based on the detection signal of the fuel temperature sensor 35. Then, the ECU 31 refers to the map using the fuel viscosity, fuel temperature, and fuel alcohol concentration as parameters, and calculates the alcohol concentration of the fuel from the fuel viscosity calculated in step S17 and the calculated fuel temperature. Thereafter, the ECU 31 ends the execution of the current program.

  According to the embodiment described in detail above, the following excellent effects can be obtained.

  The alcohol concentration of the fuel was estimated based on the pulsation cycle of the fuel pressure (actual fuel pressure) in the fuel supply path. Since the fuel pressure sensor 34 is generally less expensive than a sensor that detects the refractive index and dielectric constant of fuel, the manufacturing cost of the engine system can be reduced.

  The actual fuel pressure was detected in a state where the actual fuel pressure and the pump rotation speed were stable, and the alcohol concentration of the fuel was calculated based on the detection result. Thereby, the alcohol concentration of the fuel can be accurately estimated.

  Alcohol concentration estimation processing was started at the closing timing of the filler port. There is a high probability that the internal combustion engine 10 is stopped during fuel supply (while the fuel supply port is open) and the fuel injection is stopped for a while after the fuel supply port is closed. Therefore, by starting the alcohol concentration estimation process at the closing timing of the fuel filler opening as described above, the actual fuel pressure is detected in a state where the fuel injection is stopped, that is, the change in the actual fuel pressure accompanying the fuel injection is excluded, and the detection result is Based on this, the alcohol concentration of the fuel can be calculated. Thereby, the alcohol concentration accuracy of the fuel can be estimated with higher accuracy.

  Further, the alcohol concentration estimation process can be executed before the internal combustion engine 10 is started by starting the alcohol concentration estimation process at the closing timing of the fuel filler opening as described above. Thus, the alcohol concentration of the fuel can be estimated before the internal combustion engine 10 is started, and various controls of the internal combustion engine 10 can be performed according to the alcohol concentration of the fuel immediately after the internal combustion engine 10 is started.

  Furthermore, by starting the alcohol concentration estimation process at the closing timing of the fuel filler opening as described above, the alcohol concentration estimation process can be executed for each fuel supply. Thereby, the alcohol concentration can be estimated for each refueling, and the estimation result can be effectively reflected in the control of the engine system.

  In estimating the alcohol concentration of the fuel from the viscosity of the fuel, the alcohol concentration of the fuel was calculated in consideration of the fuel temperature. The viscosity of the fuel varies not only with the alcohol concentration of the fuel but also with the fuel temperature. Therefore, by considering the fuel temperature as described above, the alcohol concentration of the fuel can be estimated with higher accuracy.

(Other embodiments)
The present invention is not limited to the description of the above embodiment, and may be implemented as follows, for example.

  In the above embodiment, the fuel pressure is calculated based on the detection signal of the fuel pressure sensor, and the pump rotation speed is calculated based on the fuel pressure. However, the present invention is not limited to this, and the pump rotation speed may be directly detected. For example, the angular position of the rotor may be detected from the electromotive force waveform of the DC motor 20, and the pump rotation speed may be calculated based on the angular position. Further, a rotation angle sensor that detects the angular position of the rotor of the DC motor 20 may be provided, and the pump rotation speed may be calculated based on the detection signal of the sensor. Even in this case, the same effect as the above-described embodiment can be obtained.

  It is also conceivable that the alcohol concentration of the fuel is not used for engine system control while the pump rotation speed is used for engine system control. For example, it is conceivable to directly calculate a control parameter of the engine system based on the pump rotation speed, or to detect a failure of the fuel pump 14 based on the pump rotation speed. In such a case, the calculation process of the alcohol concentration of the fuel may be omitted.

  When the fuel viscosity is not used for engine system control, the fuel viscosity calculation process may be omitted, and the fuel alcohol concentration may be directly calculated based on the pump rotation speed.

  The alcohol concentration estimation process may be executed during operation of the internal combustion engine 10.

  -It may replace with the pressure regulator 17 and may employ | adopt as a fuel discharge part the pressure regulator which can variably set adjustment pressure. In this case, the fuel pressure in the fuel supply path can be stabilized at a pressure lower than the target pressure of the fuel pressure feedback control by setting the adjustment pressure of the pressure regulator to a pressure lower than the target pressure of the fuel pressure feedback. Thereby, the effect similar to the said embodiment is acquired.

  In particular, when the adjustment pressure of the regulator 40 is set to the actual fuel pressure just before the start of the alcohol concentration estimation process, the actual fuel pressure after the start of the alcohol concentration estimation process pulsates in the vicinity of the actual fuel pressure just before the start of the estimation process. As a result, it is possible to detect the pulsation period after eliminating the effect of the macroscopic change (increase) in the actual fuel pressure on the microscopic pulsation of the actual fuel pressure, so that the estimation accuracy of alcohol concentration is expected to improve. it can.

  Instead of the pressure regulator 17, a pressure regulator capable of controlling the fuel discharge amount may be adopted as the fuel discharge portion. Even in this case, the fuel pressure in the fuel supply path can be stabilized at a pressure lower than the target pressure of the fuel pressure feedback control by controlling the discharge amount. Thereby, the effect similar to the said embodiment is acquired.

  Instead of the pressure regulator 17, a fuel discharge path connected to the fuel supply path, for example, an on-off valve that opens and closes the fuel flow path in the return pipe 18 may be adopted as the fuel discharge section. Even in this case, by controlling the opening and closing of the on-off valve, the fuel pressure in the fuel supply path can be stabilized at a pressure lower than the target pressure of the fuel pressure feedback control. Thereby, the effect similar to the said embodiment is acquired.

  In the above embodiment, the feedback control of the fuel pressure is performed, but the open loop control of the fuel pressure may be performed.

The figure which shows schematic structure of an engine system. The figure which shows the pump part of a fuel pump. The timing chart for demonstrating fuel pressure feedback control. The timing chart for demonstrating alcohol concentration estimation processing. The flowchart which shows the flow of an alcohol concentration estimation process.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 ... Internal combustion engine, 12 ... Injector, 13 ... Fuel tank, 14 ... Fuel pump, 15 ... Fuel supply pipe, 16 ... Delivery pipe, 17 ... Pressure regulator (fuel discharge part), 31 ... ECU (discharge control means, behavior detection) Means, concentration estimation means, oil supply detection means), 36...

Claims (5)

The fuel pump is applied to a fuel supply device that includes an electric fuel pump that sends fuel to a fuel supply path of an internal combustion engine, and a fuel discharge unit that discharges fuel from the fuel supply path and returns the fuel to a fuel tank. In the fuel supply control device for controlling
A discharge control means for forcibly bringing the fuel discharge section into a fuel discharge state;
Behavior detecting means for detecting the behavior of the fuel pump when the fuel discharge portion is in a fuel discharge state by the discharge control means;
A fuel supply control device comprising: A pressure regulator that discharges fuel when the fuel pressure becomes higher than a predetermined adjustment pressure is applied to a fuel supply device provided as the fuel discharge unit, and the fuel pump is used to set the fuel pressure in the fuel supply path as a target pressure. In a fuel supply control device that performs fuel pressure control,
The discharge control means performs the fuel pressure control such that a target pressure of the fuel pressure control is higher than an adjustment pressure of the pressure regulator in order to force the fuel discharge portion into a fuel discharge state. The fuel supply control device according to 1.   3. The fuel supply according to claim 1, wherein, in a stopped state of the internal combustion engine, the behavior of the fuel pump is detected by the behavior detection unit after the fuel discharge unit is brought into a fuel discharge state by the discharge control unit. Control device.   The concentration estimating means for estimating the alcohol concentration of the fuel supplied to the internal combustion engine based on the behavior of the fuel pump detected by the behavior detecting means. Fuel supply control device. Comprising fuel supply detecting means for detecting fuel supply to the fuel tank;
5. The fuel pump according to claim 4, wherein each time fuel supply is detected by the fuel supply detection unit, the behavior of the fuel pump is detected by the behavior detection unit after the fuel discharge unit is made to be in a fuel discharge state by the discharge control unit. The fuel supply control device described.

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