JP2009204322A - Measuring instrument of fuel vapor pressure - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a vapor pressure measuring instrument of fuel, preventing the deterioration of a detection means, and reducing power consumption. <P>SOLUTION: An engine control system 10 is equipped with: a fuel tank 20; a fuel pump 26 for supplying the fuel in the fuel tank 20 to an injector 12; a fuel vapor producing part 40 for vaporizing the fuel; a first fuel passage 22 for connecting the fuel pump 26 and the injector 12; the second fuel passage 23 connected to the fuel pump 26 at its one end and connected to the fuel vapor producing part 40 at its other end; a pressure sensor 46 for detecting the pressure in the fuel vapor producing part 40; and a fuel temperature sensor 48 for detecting the temperature of the fuel supplied to the fuel vapor producing part 40. An ECU 30 calculates lead vapor pressure RVP on the basis of the respective detection values of the pressure sensor 46 and the fuel temperature sensor 48 and stores the RVP, and calculates the vapor pressure VP of the fuel on the basis of the stored lead vapor pressure RVP and the temperature of cooling water or the temperature of the fuel at that time. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a vapor pressure measuring device that measures the vapor pressure of fuel. More specifically, the present invention relates to a vapor pressure measuring device that measures the vapor pressure of fuel supplied to an internal combustion engine.

  Currently, gasoline is mainly used as a fuel for internal combustion engines, but the properties of commercially available fuel (gasoline) are not necessarily constant. For this reason, the fuel vapor pressure varies. In particular, when the destination is different, the fuel properties are often different, and the fuel vapor pressure tends to vary. The change in the vapor pressure of the fuel may affect the flammability of the fuel. For this reason, at present, the internal combustion engine is adapted for each destination.

  However, the vapor pressure of the fuel also changes due to oxidation of the fuel or evaporation of the fuel. For this reason, even if the internal combustion engine is adapted for each destination, it is difficult to optimally control the fuel injection amount, the injection timing, the ignition timing, and the like in all the internal combustion engines. If the fuel injection pressure, injection timing, ignition timing, etc. are not optimally controlled due to variations in the fuel vapor pressure, the startability, emission performance, and drivability of the internal combustion engine are particularly deteriorated. End up.

Thus, in all internal combustion engines, in order to optimally control the fuel injection amount, injection timing, ignition timing, etc., it is necessary to measure the vapor pressure (fuel property) of the fuel. As an apparatus for measuring such fuel properties, for example, there is one described in Patent Document 1. The apparatus described here includes a water flow pump including a chamber and a nozzle that ejects a fluid to be measured, a pressure sensor that measures the pressure in the chamber, and a fuel temperature sensor that detects the fuel temperature in the chamber. And a property calculator for calculating the property of the liquid to be measured in response to information from the pressure sensor and the fuel temperature sensor. Then, the pressure inside the chamber is made negative by ejecting the fluid to be measured from the nozzle and the pressure when the fuel is vaporized is measured to measure the typical vapor pressure of the fuel, that is, the fuel properties. Yes.
JP-A-5-223723

  However, the liquid property measuring apparatus described above has a problem that each sensor (detection means) is deteriorated and power consumption is increased. Such a problem arises because the above-described liquid property measuring apparatus always detects the pressure in the chamber and the fuel temperature to measure the vapor pressure. And if each sensor (detection means) deteriorates, the measurement accuracy of fuel vapor pressure will fall, and if there is much power consumption, the fuel consumption of an internal combustion engine will deteriorate.

  Accordingly, the present invention has been made to solve the above-described problems, and it is an object of the present invention to provide a fuel vapor pressure measuring device capable of preventing deterioration of the detecting means and reducing power consumption. And

  A fuel vapor pressure measuring device according to the present invention, which has been made to solve the above problems, supplies a fuel tank storing fuel to be supplied to an internal combustion engine, and supplies the fuel in the fuel tank to a fuel injection device. A fuel pump, a nozzle, a vaporization chamber, and a venturi, a fuel vapor generation unit that vaporizes fuel in the vaporization chamber by ejecting fuel from the nozzle and passing through the venturi, the fuel pump, and the fuel A first fuel passage connecting the injection device, a second fuel passage having one end connected to the fuel pump or the first fuel passage, and the other end connected to the fuel vapor generation section, and the inside of the fuel vapor generation section Pressure detection means for detecting the pressure of the fuel, fuel temperature detection means for detecting the temperature of the fuel passing through the fuel vapor generating section, detection results of the pressure detection means, and detection results of the fuel temperature detection means Calculating the vapor pressure of the fuel based on the fuel vapor characteristic stored in the characteristic storage means and the fuel temperature detected by the fuel temperature detecting means; Vapor pressure calculating means.

  Here, the fuel vapor characteristic can identify a vapor pressure curve (type of fuel). Specifically, for example, a detection value (vapor pressure) of the pressure detection means and a detection value of the fuel temperature detection means It is a representative value such as a vapor pressure or a reed vapor pressure at a specific temperature converted from the two variables (fuel temperature) or the vapor pressure and the fuel temperature.

  In this fuel vapor pressure measuring device, a first fuel passage for supplying fuel from the fuel pump to the fuel injection device, and a second fuel passage for supplying fuel to the fuel vapor generating section from the fuel pump or the first fuel passage are provided. ing. For this reason, fuel is supplied to the second fuel passage directly from the fuel pump or via the first fuel passage. Then, the fuel that has flowed into the second fuel passage reaches the nozzle. Here, since the nozzle is provided with a throttle, the fuel ejected from the nozzle is supplied to the vaporizing chamber at an increased flow rate, passes through the venturi, and is returned to the fuel tank. At this time, when the fuel injected from the nozzle passes through the throat portion of the venturi, a negative pressure is generated in the vaporization chamber. This is because when the fuel passes through the throat portion of the venturi, the fuel in the vaporization chamber is pulled due to the influence of viscosity, so that a negative pressure is generated in the vaporization chamber.

  Based on this negative pressure generating action, the fuel is vaporized under reduced pressure, and vapor pressure is generated in the vaporization chamber. And the pressure of a vaporization chamber will be in an equilibrium state based on the vapor pressure of a fuel. At this time, the pressure in the vaporization chamber in the equilibrium state is detected by the pressure detection means. In addition, the temperature of the fuel passing through the fuel vapor generation unit is detected. Then, the fuel vapor characteristic obtained from the detection result of the pressure detection means and the detection result of the fuel temperature detection means is stored in the characteristic storage means.

  As described above, according to this vapor pressure measuring device, the fuel injected at an increased flow rate by the nozzle throttling causes the negative pressure in the vaporization chamber to vaporize the fuel under reduced pressure, and in an equilibrium state due to the generated vapor pressure. The pressure in the vaporization chamber is detected by the pressure detection means, and the temperature of the fuel supplied to the fuel vapor generation unit is detected by the fuel temperature detection means at that time, and the fuel vapor characteristics obtained from the detected values are characteristic storage means. Is remembered.

  When the fuel vapor characteristic is stored, the vapor pressure measuring device calculates the vapor pressure of the fuel at that time by the vapor pressure calculating means based on the stored fuel vapor characteristic and the fuel temperature at that time. For this reason, according to this vapor pressure measuring device, there is no need to constantly detect the pressure and fuel temperature of the vaporization chamber, that is, only when the fuel vapor characteristic is obtained and stored in the characteristic storage means, the pressure and fuel temperature of the vaporization chamber. Therefore, it is possible to prevent deterioration of the pressure detection means and the fuel temperature detection means, and it is possible to reduce power consumption. As a result, the fuel vapor pressure can be stably measured with high accuracy, and deterioration of the fuel consumption of the internal combustion engine can be prevented.

Further, another embodiment of the fuel vapor pressure measuring device according to the present invention for solving the above problems includes a fuel tank in which fuel to be supplied to an internal combustion engine is stored, and fuel in the fuel tank as fuel. A fuel pump for supplying to the injection device, a refrigerant temperature detecting means for detecting the temperature of the refrigerant for cooling the internal combustion engine, a nozzle, a vaporizing chamber, and a venturi are provided, and fuel is ejected from the nozzle to pass through the venturi. Thus, a fuel vapor generation unit that vaporizes fuel in the vaporization chamber, a first fuel passage that connects the fuel pump and the fuel injection device, one end is connected to the fuel pump or the first fuel passage, A second fuel passage having the other end connected to the fuel vapor generation unit, a pressure detection unit for detecting a pressure in the fuel vapor generation unit, a detection result of the pressure detection unit, and a refrigerant temperature detection unit The fuel vapor characteristics are stored on the basis of the respective detection results, the fuel vapor characteristics are stored on the basis of the fuel vapor characteristics stored in the characteristic storage means and the refrigerant temperature detected by the refrigerant temperature detection means. And a vapor pressure calculating means for calculating a pressure.
The fuel vapor characteristic can specify the vapor pressure curve (type of fuel) as described above. Specifically, for example, the detection value (vapor pressure) of the pressure detection means and the fuel temperature detection It is a representative value such as a vapor pressure at a specific temperature converted from the vapor pressure and the fuel temperature, a lead vapor pressure, or the like, with two variables of the detection value (fuel temperature) of the means.

  This fuel vapor pressure measuring device also includes a first fuel passage through which fuel is supplied from the fuel pump to the fuel injection device, and a second fuel passage through which fuel is supplied from the fuel pump or the first fuel passage to the fuel vapor generating section. ing. For this reason, fuel is supplied to the second fuel passage directly from the fuel pump or through the first fuel passage. Then, the fuel that has flowed into the second fuel passage reaches the nozzle. Here, since the nozzle is provided with a throttle, the fuel ejected from the nozzle is supplied to the vaporizing chamber at an increased flow rate, passes through the venturi, and is returned to the fuel tank. At this time, when the fuel injected from the nozzle passes through the throat portion of the venturi, a negative pressure is generated in the vaporization chamber.

  Based on this negative pressure generating action, the fuel is vaporized under reduced pressure, and vapor pressure is generated in the vaporization chamber. And the pressure of a vaporization chamber will be in an equilibrium state based on the vapor pressure of a fuel. At this time, the pressure in the vaporization chamber in the equilibrium state is detected by the pressure detection means. In addition, the temperature of the fuel passing through the fuel vapor generation unit is detected. Then, the fuel vapor characteristic obtained from the detection result of the pressure detection means and the detection result of the fuel temperature detection means is stored in the characteristic storage means.

  Then, when the fuel vapor characteristic is stored, the vapor pressure measuring device calculates the vapor pressure of the fuel at that time by the vapor pressure calculating means based on the stored fuel vapor characteristic and the refrigerant temperature at that time. For this reason, according to this vapor pressure measuring device, there is no need to constantly detect the pressure and fuel temperature of the vaporization chamber, that is, only when the fuel vapor characteristic is obtained and stored in the characteristic storage means, the pressure and fuel temperature of the vaporization chamber. Therefore, it is possible to prevent deterioration of the pressure detection means and the fuel temperature detection means, and it is possible to reduce power consumption. As a result, the fuel vapor pressure can be stably measured with high accuracy, and deterioration of the fuel consumption of the internal combustion engine can be prevented.

  Here, the fuel vapor pressure to be considered for the control of the internal combustion engine is a value in the internal combustion engine (combustion chamber). For this reason, in this fuel vapor pressure measuring device, when the fuel vapor pressure is calculated after storing the fuel vapor characteristics, the refrigerant temperature, which is the temperature index value of the internal combustion engine, is referred to instead of the fuel temperature. Thereby, since the value close | similar to the fuel vapor pressure in an internal combustion engine (combustion chamber) can be calculated, the control precision of an internal combustion engine can be improved.

Furthermore, another embodiment of the fuel vapor pressure measuring apparatus according to the present invention for solving the above-described problems includes a fuel tank in which fuel to be supplied to an internal combustion engine is stored, and fuel in the fuel tank as fuel. A fuel pump for supplying to the injection device, a refrigerant temperature detecting means for detecting the temperature of the refrigerant for cooling the internal combustion engine, a nozzle, a vaporizing chamber, and a venturi are provided, and fuel is ejected from the nozzle to pass through the venturi. Thus, a fuel vapor generation unit that vaporizes fuel in the vaporization chamber, a first fuel passage that connects the fuel pump and the fuel injection device, one end is connected to the fuel pump or the first fuel passage, A second fuel passage having the other end connected to the fuel vapor generation unit, a pressure detection unit for detecting a pressure in the fuel vapor generation unit, a detection result of the pressure detection unit, and a refrigerant temperature detection Characteristic storage means for storing fuel vapor characteristics obtained based on each detection result of the stage, fuel vapor characteristics stored in the characteristic storage means, and refrigerant temperature detected by the refrigerant temperature detection means And the vapor pressure calculating means for calculating the vapor pressure.
The fuel vapor characteristic can specify the vapor pressure curve (type of fuel) as described above. Specifically, for example, the detection value (vapor pressure) of the pressure detection means and the fuel temperature detection It is a representative value such as a vapor pressure at a specific temperature converted from the vapor pressure and the fuel temperature, a lead vapor pressure, or the like, with two variables of the detection value (fuel temperature) of the means.

  This fuel vapor pressure measuring device also includes a first fuel passage through which fuel is supplied from the fuel pump to the fuel injection device, and a second fuel passage through which fuel is supplied from the fuel pump or the first fuel passage to the fuel vapor generator. ing. For this reason, fuel is supplied to the second fuel passage directly from the fuel pump or via the first fuel passage. Then, the fuel that has flowed into the second fuel passage reaches the nozzle. Here, since the nozzle is provided with a throttle, the fuel ejected from the nozzle is supplied to the vaporizing chamber at an increased flow rate, passes through the venturi, and is returned to the fuel tank. At this time, when the fuel injected from the nozzle passes through the throat portion of the venturi, a negative pressure is generated in the vaporization chamber.

  Based on this negative pressure generating action, the fuel is vaporized under reduced pressure, and vapor pressure is generated in the vaporization chamber. And the pressure of a vaporization chamber will be in an equilibrium state based on the vapor pressure of a fuel. At this time, the pressure in the vaporization chamber in the equilibrium state is detected by the pressure detection means. The refrigerant temperature of the internal combustion engine is detected by the refrigerant temperature detecting means. Then, the fuel vapor characteristic obtained from the detection result of the pressure detection means and the detection result of the refrigerant temperature detection means is stored in the characteristic storage means.

  And this vapor pressure measuring device memorizes the fuel vapor characteristic, and based on the memorized fuel vapor characteristic and the refrigerant temperature at that time (when calculating the vapor pressure), the vapor pressure calculating means uses the vapor of the fuel at that time. Calculate the pressure. Thereby, since the value close | similar to the fuel vapor pressure in an internal combustion engine (combustion chamber) can be calculated, the control precision of an internal combustion engine can be improved. And according to this vapor pressure measuring device, it is not necessary to always detect the pressure of the vaporization chamber, that is, it is only necessary to detect the pressure of the vaporization chamber when obtaining the fuel vapor characteristic and storing it in the characteristic storage means. The pressure detection means can be prevented from being deteriorated, and the power consumption can be reduced. As a result, the fuel vapor pressure can be stably measured with high accuracy, and deterioration of the fuel consumption of the internal combustion engine can be prevented. In addition, since this vapor pressure measuring device does not require a fuel temperature detecting means, the cost and size of the device can be reduced.

  In the fuel vapor pressure measuring apparatus according to the present invention, it is desirable that the characteristic storage means stores a lead vapor pressure as the fuel vapor characteristic.

  By doing so, arithmetic processing and storage in the vapor pressure measuring device can be facilitated, and the vapor pressure of the fuel can be accurately measured. Note that the measurement accuracy of the fuel vapor pressure does not change even if the two variables of the detection value (vapor pressure) of the pressure detection means and the detection value (fuel temperature) of the fuel temperature detection means are stored. This is disadvantageous in terms of arithmetic processing and memory. If the vapor pressure at a specific temperature is stored instead of the lead vapor pressure, the calculation processing and storage in the vapor pressure measuring device can be facilitated, but the measurement accuracy of the fuel vapor pressure may be reduced.

  In the fuel vapor pressure measuring apparatus according to the present invention, the characteristic storage means updates the fuel vapor characteristic at a constant time period, and the vapor pressure calculation means includes the updated fuel vapor characteristic and the fuel temperature. It is desirable to calculate the vapor pressure of the fuel based on the temperature detected by the detection means or the refrigerant temperature detection means.

  The vapor pressure of the fuel also changes (changes with time) due to oxidation of the fuel or evaporation of the fuel. For this reason, the characteristic storage means periodically updates the fuel vapor characteristics, and the vapor pressure of the fuel is calculated by the vapor pressure calculation means using the updated fuel vapor characteristics, so that it is possible to cope with the change with time of the fuel. it can. In other words, such a configuration can reduce power consumption while preventing deterioration of the pressure detection means and the fuel temperature detection means, and can accurately measure the vapor pressure of the fuel even if the fuel changes with time. it can.

  In the fuel vapor pressure measuring apparatus according to the present invention, the characteristic storage means may update the fuel vapor characteristic every time the internal combustion engine is started.

  In this way, by updating the fuel vapor characteristic every time the fuel engine is started, it is possible to reliably cope with the change with time of the fuel that occurs while the internal combustion engine is stopped.

  In the fuel vapor pressure measuring apparatus according to the present invention, when the fuel is supplied to the fuel tank, the characteristic storage means may update the fuel vapor characteristic.

  In this way, by updating the fuel vapor characteristics when the fuel is replenished to the fuel tank, it is possible to cope with the change in the fuel property due to the refueling.

  In the fuel vapor pressure measuring apparatus according to the present invention, the characteristic storage means preferably stores a fuel vapor characteristic under an operating condition of the internal combustion engine in which an injection amount from the fuel injection device is reduced.

  In order to supply fuel to the fuel vapor generating section by storing the fuel vapor characteristics in the characteristic storage means during the operating conditions of the internal combustion engine in which the injection amount from the fuel injection device is reduced, for example, during idling or deceleration. Therefore, it is not necessary to increase the size of the fuel pump, and the influence on the fuel injection in the fuel injection device can be reduced.

  In the fuel vapor pressure measuring device according to the present invention, the fuel vapor pressure measuring device includes a control valve disposed upstream or downstream of the nozzle, and controls the inflow of fuel to the nozzle, and the control valve stores the characteristic memory. It is desirable that the means be opened when obtaining the fuel vapor characteristics stored.

  With such a configuration, it is possible to supply fuel (inject fuel from the nozzle) to the fuel vapor generating section only when obtaining the fuel vapor characteristics stored in the characteristic storage means. For this reason, the influence on the fuel injection in the fuel injection device can be reduced.

  Then, the fuel injection amount may be corrected using the vapor pressure measured by the fuel vapor pressure measuring device so that the internal combustion engine is in the optimum operating state. Specifically, the fuel vapor pressure measuring device according to any one of the above-described fuel and an operation control means for controlling the operation state of the internal combustion engine are provided, and the operation control means is configured to control the fuel pressure calculated by the vapor pressure calculation means. The fuel injection amount in the fuel injection device may be corrected based on the vapor pressure.

  As a result, the optimum fuel injection amount required by the internal combustion engine can be corrected in accordance with the type and temperature of the fuel. As a result, a stable combustion state is always obtained, and in particular, it is possible to reduce HC, startability, and drivability when the A / F sensor is inactive (during open control) during cold weather. In addition, since it is possible to detect differences in vapor pressure (fuel properties) due to differences in destinations, it is not necessary to adapt the internal combustion engine according to the type of fuel, making it easier to deploy models and greatly reducing development man-hours. Can do.

  Alternatively, the fuel vapor pressure measuring device according to any one of the above-described fuel and an operation control means for controlling an operation state of the internal combustion engine, wherein the operation control means adjusts the fuel vapor pressure calculated by the vapor pressure calculation means. Based on this, the ignition timing of the internal combustion engine may be corrected.

  Thereby, the optimal ignition timing required by the internal combustion engine can be corrected in accordance with the type and temperature of the fuel. As a result, a stable combustion state is always obtained, and in particular, it is possible to reduce HC, startability, and drivability when the A / F sensor is inactive (during open control) during cold weather. In addition, since it is possible to detect differences in vapor pressure (fuel properties) due to differences in destinations, it is not necessary to adapt the internal combustion engine according to the type of fuel, making it easier to deploy models and greatly reducing development man-hours. Can do.

  According to the fuel vapor pressure measuring apparatus of the present invention, as described above, it is possible to prevent the detection means from deteriorating and reduce the power consumption.

  BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, a most preferred embodiment embodying a fuel vapor pressure measuring device and a fuel injection control system of the present invention will be described in detail with reference to the accompanying drawings. In the present embodiment, the present invention is applied to an automotive engine control system.

(First embodiment)
First, the first embodiment will be described. The engine control system according to the first embodiment will be described with reference to FIGS. FIG. 1 is a configuration diagram showing an outline of an engine control system according to the first embodiment. FIG. 2 is a partial cross-sectional view showing a schematic configuration of the fuel vapor generating section. As shown in FIG. 1, the engine control system 10 includes an engine 11, an injector 12, a fuel tank 20, a fuel pump unit 21, a first fuel passage 22, a second fuel passage 23, and an engine control unit. (ECU) 30. Thus, in the engine control system 10, the fuel in the fuel tank 20 is supplied from the fuel pump unit 21 to the injector 12 through the fuel passage 22 based on a command from the ECU 30, and the fuel is injected and supplied from the injector 12 to the engine 11. It has become so.

  Here, the engine 11 is of a reciprocating type having a known structure. The engine 11 ignites a combustible mixture of air sucked through the intake passage 13 and fuel injected from the injector 12 by an ignition plug 35 to explode and burn in the combustion chamber. Is discharged through the exhaust passage 14 to operate the piston 15 to rotate a crankshaft (not shown) to obtain power. The engine 11 is provided with a water temperature sensor 33. The water temperature sensor 33 detects the temperature (cooling water temperature) of the cooling water (refrigerant) flowing inside the engine 11 and outputs an electrical signal corresponding to the detected value. The output signal from the water temperature sensor 33 is input to the ECU 30.

  An air flow meter 31, a throttle valve 16, and a surge tank 17 are provided in the intake passage 13. Here, the air flow meter 31 detects the amount of air (intake amount) taken into the engine 11 through the intake passage 13 and outputs an electrical signal corresponding to the detected value. The throttle valve 16 is opened and closed to adjust the amount of air (intake amount) taken into the engine 11 through the intake passage 13. The valve 16 is operated in accordance with an operation of an accelerator pedal 18 provided at the driver's seat, and more specifically, according to an output signal from an accelerator position sensor 19 provided at the accelerator pedal 18. The surge tank 17 is provided with an intake pressure sensor 32. The intake pressure sensor 32 detects the intake pressure in the intake passage 13 downstream from the throttle valve 16 and outputs an electric signal corresponding to the detected value. Note that output signals from the intake air temperature sensor 31 and the intake pressure sensor 32 are input to the ECU 30.

  The injector 12 injects fuel into the intake port of each cylinder in the engine 11. The fuel pumped from the fuel pump unit 21 is supplied to the injector 12 through the first fuel passage 22. The fuel supplied in this manner is injected into the intake port when the injector 12 is operated based on a command from the ECU 30, forms a combustible air-fuel mixture with air, and is taken into each cylinder. As will be described later, since the fuel injection pressure is controlled to be constant by the pressure regulator 28, the surplus fuel is returned into the fuel tank 20 via a jet pump provided in the fuel pump unit 21.

  The fuel tank 20 stores fuel to be supplied to the engine 11, and a fuel pump unit 21 is provided therein. As shown in FIG. 2, the fuel pump unit 21 has a reserve plate 27 in which a fuel pump 26 and the like are accommodated in a set plate 25 that closes the mounting hole 20 a of the fuel tank 20. The fuel pump unit 21 is attached to the fuel tank 20 by attaching the set plate 25 to the fuel tank 20 so as to close the attachment hole 20 a of the fuel tank 20. From such a fuel pump unit 21, the fuel adjusted to a constant pressure by the pressure regulator 28 is supplied to the first fuel pipe 22 and the second fuel pipe 23. Thereby, since the fuel injection conditions from the nozzle 42 mentioned later can be made constant, a fuel can be vaporized on the same conditions in the vaporization chamber 45 mentioned later. In addition, a float 29 for detecting the remaining amount of fuel in the fuel tank 20 is attached to the fuel pump unit 21. A signal related to the position (height) of the float 29 is input to the ECU 30, and the remaining amount of fuel and the presence or absence of refueling are detected from the signal.

  The spark plug 35 provided in the engine 11 receives the high voltage output from the igniter 36 and performs an ignition operation. The ignition timing of the spark plug 35 is determined by the output timing of the high voltage by the igniter 36 determined by the command of the ECU 30.

  In addition to the above, various signals output from various sensors such as a crank angle sensor are input to the ECU 30 shown in FIG. The ECU 30 detects the operating state of the engine based on these input signals, and executes the fuel supply control, the ignition timing control, and the like according to the operating state of the engine, so that the fuel pump 26, the injector 12, and the igniter 36 are executed. Each is controlled. That is, the ECU 30 corresponds to “operation control means” of the present invention. The fuel supply control controls the discharge amount of the fuel pump 26 (the number of revolutions of the pump motor), the fuel amount injected from the injector 12 (fuel injection amount), and the injection timing according to the operating state of the engine. It is to be. The ignition timing control is to control the ignition timing by the spark plug 35 by controlling the igniter 36 according to the operating state of the engine 11.

  The ECU 30 calculates and stores the lead vapor pressure as the fuel vapor characteristic based on output signals from the pressure sensor 46 and the fuel temperature sensor 48 described later. That is, the ECU 30 corresponds to the “fuel vapor characteristic storage means” of the present invention. Further, the ECU 30 calculates the fuel vapor pressure based on the stored lead vapor pressure and the coolant temperature or fuel temperature detected by the water temperature sensor 33 or the fuel temperature sensor 48. That is, the ECU 30 corresponds to “vapor pressure calculation means” of the present invention.

  Here, the ECU 30 includes a known configuration, that is, a central processing unit (CPU), a read-only memory (ROM), a random access memory (RAM), a backup RAM, an external input circuit, an external output circuit, and the like. The ECU 30 constitutes a logical operation circuit formed by connecting a CPU, a ROM, a RAM, a backup RAM, an external input circuit, an external output circuit, and the like through a bus. The ROM stores in advance a predetermined control program related to control in the engine. The RAM temporarily stores the calculation result of the CPU. The backup RAM stores data stored in advance. The CPU executes various controls according to a predetermined control program based on detection values of various sensors input via an input circuit.

  A fuel vapor generator 40 is disposed on the fuel tank side of the set plate 25, that is, in the fuel tank 20, more specifically, in the reserve cup 27. By providing the fuel vapor generation part 40 in the fuel tank 20 in this way, there is no problem even if the fuel leaks from the fuel vapor generation part 40. Therefore, the structure of the fuel vapor generation part, particularly the seal structure is simplified. be able to. In addition, the fuel vapor generating section 40 can be modularized together with the fuel pump 26 and the like, so that the mounting thereof becomes easy and the mounting member can be simplified. In the present embodiment, the fuel vapor generator 40 is integrated with the set plate 25.

  As shown in FIG. 2, the fuel vapor generation unit 40 includes an electromagnetic valve 41, a nozzle 42, a vaporization chamber 45, and a venturi 47. The inlet of the solenoid valve 41 is connected to the second fuel pipe 23, and the inlet is connected to the nozzle 42. The valve body 43 of the electromagnetic valve 42 is moved by turning ON / OFF the energization of the electromagnetic valve 41, and the fuel injection from the nozzle 42 to the vaporizing chamber 45 is controlled. By providing such an electromagnetic valve 42, it is possible to inject fuel from the nozzle 42 only during the measurement of the fuel vapor pressure and to reliably generate a negative pressure in the vaporizing chamber 45. Thus, the fuel vapor pressure can be measured when the fuel injection amount is small, the fuel vapor pressure can be accurately measured without increasing the flow rate of the fuel pump 26, and the fuel of the injector 12 can be measured. The influence on the injection amount can be reduced. As shown in FIG. 1, the electromagnetic valve 41 is connected to the ECU 30, and energization of the electromagnetic valve 41 is turned on / off based on a command from the ECU 30.

  As shown in FIG. 2, the vaporization chamber 45 is formed around the nozzle 42 and between the nozzle 42 and the venturi 47. In the present embodiment, the nozzle 42 has a diameter of 0.9 mm, the venturi 47 has a throat portion diameter of 1.5 mm, and the distance between the nozzle 42 and the venturi 47 is 3 mm. These numerical values are determined by the performance of the fuel pump, and are not limited to those illustrated.

  A pressure sensor 46 is connected to the vaporizing chamber 45 so that the pressure in the vaporizing chamber 45 can be detected. As a result, the pressure in the vaporizing chamber 45 when the fuel is boiled under reduced pressure and vapor pressure is generated by the negative pressure generated in the vaporizing chamber 45 is detected by the pressure sensor 46. The output signal from the pressure sensor 46 is input to the ECU 30 as shown in FIG.

  Thus, the reason why the fuel is boiled under reduced pressure in the vaporizing chamber 45 is as follows. That is, the fuel ejected from the nozzle 42 is supplied to the vaporizing chamber 45 at an increased flow velocity, passes through the venturi 47 and is returned into the reserve cup 27, but the fuel injected from the nozzle 42 passes through the throat portion of the venturi 47. When passing through, the fuel in the vaporization chamber 45 is pulled outside (Benyuri) side due to the influence of the viscosity of the fuel, so that a negative pressure is generated in the vaporization chamber 45. Then, based on this negative pressure generating action, the fuel in the vaporizing chamber 45 is vaporized under reduced pressure, and a vapor pressure is generated in the vaporizing chamber 45. And the pressure of the vaporization chamber 45 will be in an equilibrium state based on the vapor pressure of the fuel. At this time, the pressure in the vaporizing chamber 45 in the equilibrium state is detected by the pressure sensor 46.

  The pressure sensor 46 is provided outside the fuel tank 20, specifically, on the front side of the set plate 25 (the side opposite to the tank). Thereby, wiring to the pressure sensor 46 and wiring to the pressure sensor 46 are facilitated. Further, since the fuel flowing out from the venturi 47 is returned into the reserve cup 27, even when the fuel pump 26 is inclined, the fuel pump 26 disposed in the reserve cup 27 reliably sucks up the fuel and supplies the fuel. Can be done.

  Furthermore, as shown in FIG. 2, a fuel temperature sensor 48 is provided at the inlet of the fuel vapor generating section 40 (electromagnetic valve 41). Thereby, the temperature of the fuel injected into the nozzle 42 can be accurately detected. An output signal from the fuel temperature sensor 48 is input to the ECU 30 as shown in FIG. The fuel temperature sensor 48 is integrally assembled with the fuel vapor generation unit 40. Thereby, the components of the fuel vapor generation part 40 are integrated (integrated), and the attachment property of the fuel vapor generation part 40 can be further improved.

  Based on the pressure and fuel temperature detected by the fuel vapor generation unit 40 in this way, the lead vapor pressure RPV is calculated as described later. In other words, the fuel vapor generation unit 40 can vaporize the fuel under reduced pressure to calculate the fuel reed vapor pressure RVP, thereby calculating the fuel vapor pressure at the starting temperature. Therefore, the system configuration can be simplified, the size can be reduced, and fuel injection control with higher accuracy can be performed.

  Here, the calculation of the fuel vapor pressure performed in the engine control system 10 and the concept of engine control using the fuel vapor pressure will be briefly described with reference to FIGS. FIG. 3 is a diagram for explaining the concept of the lead vapor pressure calculation process. FIG. 4 is a diagram for explaining the concept of engine control when starting the engine.

  First, as shown in FIG. 3, after the engine is started, the vaporization chamber pressure P (T1) is detected in an idle operation or in a decelerating state, and the fuel temperature is detected to detect the vapor pressure change rate (temperature coefficient) Ct (T1). Is calculated. Then, the reed vapor pressure RVP is calculated based on the conversion formula. Details of the conversion formula for calculating the lead vapor pressure will be described later. Thereafter, the reed vapor pressure RVP is stored in the RAM as a representative value. Thereby, it is only necessary to store one value as an index indicating the fuel property in the fuel tank, and subsequent handling (calculation, storage, etc.) is simplified. As the fuel vapor characteristic, instead of storing the lead vapor pressure, the vaporization chamber pressure and the fuel temperature may be stored as they are, or the vapor pressure at a specific temperature calculated from the vaporization chamber pressure and the fuel temperature is stored. May be. However, when the two variables of the vaporization chamber pressure and the fuel temperature are stored, the measurement accuracy of the fuel vapor pressure does not decrease, but it is disadvantageous in terms of arithmetic processing and storage in the vapor pressure measuring device. . On the other hand, when the vapor pressure at a specific temperature is stored, it is advantageous in terms of arithmetic processing and storage in the vapor pressure measuring device, but the measurement accuracy of the fuel vapor pressure may be reduced.

  Then, at the next engine start, as shown in FIG. 4, the read vapor pressure RVP stored during the previous engine operation is read, and the engine water temperature is detected to determine the vapor pressure change rate (temperature coefficient) Ct (T2). calculate. Next, the vapor pressure VP (T2) at the time of engine start is calculated based on the conversion formula. The details of the conversion formula for calculating the vapor pressure will be described later. Next, correction values for the fuel injection amount and ignition timing are determined based on the calculated vapor pressure, and the engine is started with the corrected fuel injection amount and ignition timing.

  Thus, the engine control system 10 calculates and stores the reed vapor pressure RVP. Thereafter, the fuel vapor pressure VP (T2) is calculated based on the stored reed vapor pressure RVP and the coolant temperature T2 at that time. Therefore, in order to calculate the fuel vapor pressure VP (T2), it is not necessary to constantly detect the pressure and fuel temperature of the vaporization chamber, and the deterioration of the pressure sensor and fuel temperature sensor can be prevented, and the consumption in the system can be prevented. The amount of electric power can also be reduced. Therefore, the fuel vapor pressure VP (T2) can be stably measured with high accuracy, and deterioration of fuel consumption can be prevented. In calculating the fuel vapor pressure VP (T2), the fuel temperature can be used instead of the cooling water temperature. However, the calculation of the fuel vapor pressure VP using the cooling water temperature is more effective for the engine 11. Since the fuel vapor pressure VP corresponding to the temperature state can be calculated, fuel supply control and ignition timing control can be performed more appropriately.

  The control by the engine control system 10 can correct the optimal fuel injection and ignition timing required by the engine in accordance with the type and temperature of the fuel. As a result, a stable combustion state is always obtained, and in particular, it is possible to reduce HC, startability, and drivability when the A / F sensor is inactive (during open control) during cold weather. In addition, since it is possible to detect differences in vapor pressure (fuel properties) due to differences in destinations, it is not necessary to adapt the engine to the type of fuel, which makes it easier to deploy models and greatly reduce development man-hours. it can.

  Next, the operation of the engine control system 10 when the above control concept is applied to the engine control system 10 will be described with reference to FIGS. 5 and 6. FIG. 5 is a flowchart showing the content of fuel supply control at the time of engine start in the engine control system. FIG. 6 is a flowchart showing the content of a lead vapor pressure measurement routine in the engine control system. The fuel supply control in the engine control system 10 is started when the ignition (IG) is turned on.

  When the ignition (IG) is turned on, the ECU 30 reads the current reed vapor pressure RVP stored in the RAM provided in the ECU 30 as shown in FIG. 5 (step 1). The lead vapor pressure RVP is an index indicating the volatility of the fuel. The process of writing (storing) the current read vapor pressure RVP to the RAM is performed during the execution of a read vapor pressure measurement routine (see FIG. 6) described later.

Next, the ECU 30 detects the cooling water temperature of the engine 11 based on a signal from the water temperature sensor 33 (step 2). Then, the ECU 30 calculates a temperature coefficient Ct (T2) based on the cooling water temperature detected in step 2 (step 3). Here, the temperature coefficient Ct (T2) indicates the rate of change in vapor pressure due to fuel temperature when the read vapor pressure RVP (37.8 ° C.) read in step 1 is “1” (FIG. 9). reference). Thereafter, the ECU 30 calculates the current fuel vapor pressure VP from the lead vapor pressure RVP (37.8 ° C.) read out in step 1 and the temperature coefficient Ct (T2) calculated in step 3 by the following equation (step 4). ).
VP = RVP · Ct (T2)

  Here, the reason why the fuel vapor pressure is calculated from the temperature coefficient based on the coolant temperature is to accurately calculate the vapor pressure in a state where the fuel is injected from the injector 12 (in the engine 11). For example, in a cold region, the fuel temperature may be low even when the engine 11 has been warmed up. In such a case, if the fuel vapor pressure is calculated based on the fuel temperature, the fuel is injected from the injector 12. This is because the fuel vapor pressure at this time cannot be calculated accurately. And the control accuracy of the engine 11 can be improved by calculating the fuel vapor pressure in this way. Note that the temperature for calculating the fuel vapor pressure may be determined (switched) between the cooling water temperature and the fuel temperature depending on the operating state of the engine 11.

  Thereafter, the ECU 30 determines correction amounts such as the fuel injection amount and ignition timing at the start based on the calculated fuel vapor pressure (step 5). Thereby, in the engine control system 10, the fuel increase correction and the ignition timing correction based on the fuel vapor pressure at the start are performed. Specifically, the operation of the injector 12 and the igniter 36 is controlled by the ECU 30, the injection amount from the injector 12 is corrected, and the ignition timing of the spark plug 35 is corrected. Then, the ECU 30 performs the fuel injection amount correction and the ignition timing correction to start the engine 11 (step 6).

  In this way, in the engine control system 10, since the ECU 30 performs the fuel injection control and the ignition timing control when starting the engine 11 based on the fuel vapor pressure, even if the fuel property (type) changes, highly accurate fuel injection Control can be performed. As a result, the optimum fuel injection amount required by the engine can be corrected in accordance with the type and temperature of the fuel, so that a stable combustion state is always obtained, especially when the A / F sensor is inactive at the time of cold start (open control) HC reduction, startability, and drivability improvement. In addition, since it is possible to detect differences in fuel properties (vapor pressure) due to differences in destinations, it is not necessary to adapt the internal combustion engine to match the fuel properties, making it easier to deploy models and greatly reducing development man-hours. Can do.

  Then, after the engine 11 is started, the ECU 30 executes a lead vapor pressure measurement routine shown in FIG. When this lead vapor pressure measurement routine is executed, as shown in FIG. 6, after resetting the timer (step S10), the ECU 30 determines whether the pressure measurement condition by the pressure sensor 46 is satisfied (step 11). ~ 14). In the present embodiment, a specified time or more has elapsed since the timer reset (step 11), the output voltage of the accelerator position sensor 19 is below a specified value, that is, the accelerator pedal 18 is not operated (step 12), the battery The measurement condition is that the voltage is equal to or higher than a predetermined value (for example, 6V) (step 13) and that no fuel is supplied (step 14). In the present embodiment, the presence / absence of refueling is determined based on the position signal of the float 29, but can also be determined based on the opening / closing of the refueling port.

  When the measurement conditions described above are satisfied (S11 to S13: YES, S14: NO), that is, at the time of idling or deceleration when the fuel injection amount is small, the pressure of the vaporization chamber 45 is measured by the fuel vapor generation unit 40 (step) 15). Specifically, the ECU 30 turns on the electromagnetic valve 41 and opens the nozzle 42. As a result, fuel is injected from the nozzle 42 toward the venturi 47, the fuel adheres to the throat portion of the venturi 47, a negative pressure is generated in the vaporization chamber 45, and the fuel is vaporized under reduced pressure to enter the vaporization chamber 45. Vapor pressure is generated. At this time, the pressure sensor 46 detects the pressure in the vaporization chamber 45, and the fuel temperature sensor 48 detects the temperature T1 of the fuel supplied to the fuel vapor generator 40 (step 16).

  Here, the pressure detected by the pressure sensor 46 is P (T1) shown in FIG. This pressure P (T1) is vaporized under reduced pressure than the negative pressure Pn (see the alternate long and short dash line) generated in the vaporizing chamber 45 when the fuel is injected from the nozzle 42 (injection flow rate Q (Q is constant)). The negative pressure recovered (decreased) by the vapor pressure generated (see solid line). In addition, FIG. 7 is a figure which shows the relationship (feed pressure of 300 kPa) between the ejection flow rate from a nozzle, and a vaporization chamber pressure.

  On the other hand, if the pressure measurement conditions are not satisfied in steps 11 to 13, the ECU 30 temporarily stops the subsequent processing until each condition is satisfied. And if all the conditions of step 11-13 are satisfy | filled (S11-S13: YES), ECU30 will judge whether it was refueled (step 14). At this time, if fuel is being supplied (S14: YES), the ECU 30 resets the timer and repeats the determination of the pressure measurement conditions (steps 11 to 14).

  Then, the ECU 30 calculates a temperature coefficient Ct (T1) based on the fuel temperature detected in step 16 (step 17). Next, the reed vapor pressure RVP (37.8 ° C.) is calculated based on the following conversion formula using the pressure P (T1) measured in step 15 and the temperature coefficient Ct (T1) calculated in step 17 (step 18). ).

  Here, a conversion formula for calculating the Reed vapor pressure and the vapor pressure (volatility) at an arbitrary temperature will be described with reference to FIGS. 8 and 9. FIG. 8 is a diagram showing the relationship between the Reid vapor pressure (physical property value) and the vaporization chamber pressure. FIG. 9 is a diagram showing a change rate (temperature coefficient Ct) with respect to temperature when the vaporization chamber pressure at 37.8 ° C. obtained from the result of FIG. 8 is used as a reference.

  As is apparent from FIG. 8, the vaporization chamber pressure has a very high correlation with the lead vapor pressure (physical property value) regardless of the type of fuel at each fuel temperature. And with respect to the temperature change when the vaporization chamber pressure at 37.8 ° C. is used as a reference, as shown in FIG. 9, the change rate of the vaporization chamber pressure changes at a certain rate regardless of the type of fuel. Therefore, if the pressure in the vaporization chamber 45 and the fuel temperature can be detected, the lead vapor pressure and the fuel vapor pressure (volatility) at an arbitrary temperature can be easily calculated.

And the conversion formula of Reed vapor pressure RVP obtained from the said result is as showing below.
RVP = 1 / Ct (T1) · A ₀ · P (T1) + B ₀
A ₀ : slope of the reference temperature (37.8 ° C.) B ₀ : intercept of the reference temperature (37.8 ° C.) Further, the conversion formula of the vapor pressure VP at an arbitrary temperature is as shown below.
VP (T2) = RVP · Ct (T2)

  Thereafter, when the ECU 30 calculates the lead vapor pressure RVP (37.8 ° C.) in this way, the ECU 30 overwrites the RAM with the calculated lead vapor pressure RVP (37.8 ° C.) as the current lead vapor pressure RVP. As a result, the previous lead vapor pressure RVP is erased, and the current lead vapor pressure RVP is stored (step 19). Thereafter, when the engine 11 is stopped, this processing routine ends (step 20). The current reed vapor pressure RVP stored in this way is read out at the next engine start (see step 1).

  As described above in detail, in the engine control system 10 according to the present embodiment, the fuel vapor generation unit 40 generates vapor pressure by vaporizing the fuel under reduced pressure, and the pressure in the vaporization chamber 45 at that time is generated. The ECU 30 calculates the lead vapor pressure RVP (37.8 ° C.) from the temperature coefficient Ct (T1) based on the detection signal of the fuel temperature sensor 48 detected by the pressure sensor 46 and stores it. When the engine 11 is started, the current fuel vapor pressure VP is calculated from the stored reed vapor pressure RVP (37.8 ° C.) and the temperature coefficient Ct (T2) calculated based on the detection signal of the water temperature sensor 33. Using the fuel vapor pressure VP, fuel injection control and ignition timing control when the engine 11 is started are performed. For this reason, since the optimum fuel injection amount and ignition timing required by the engine 11 can be corrected according to the type and temperature of the fuel, a stable combustion state can always be obtained, and the A / F sensor is inactive particularly during cold start. HC reduction at the time (during open control), startability, and improvement in drivability can be satisfied. In addition, since it is possible to detect differences in vapor pressure (fuel properties) due to differences in destinations, it is no longer necessary to adapt the engine to the type of fuel, making it easier to deploy models and greatly reducing development man-hours. .

  In the engine control system 10, when the fuel vapor pressure VP is measured, the current fuel vapor pressure VP is calculated based on the stored reed vapor pressure RVP and the detection signal of the water temperature sensor 33. For this reason, since it is not necessary to always detect the pressure and fuel temperature of the vaporization chamber 45, the pressure sensor 46 and the fuel temperature sensor 48 can be prevented from being deteriorated, and the power consumption can be reduced. As a result, the fuel vapor pressure VP can be stably measured with high accuracy, and deterioration of fuel consumption can be prevented.

  Since the lead vapor pressure stored in the RAM of the ECU 30 is updated (periodically) every time the engine 11 is started, the fuel vapor is stably stabilized even when the fuel changes with time. The pressure VP can be measured with high accuracy.

  Here, in order to improve the measurement accuracy of the fuel vapor pressure, it is necessary to accurately detect the fuel temperature without variation. Therefore, instead of attaching the fuel vapor generating part to the set plate 25, as shown in FIG. 10, the fuel vapor generating part 40a is installed at the bottom of the reserve cup 27, and the fuel temperature sensor 48 is attached to the bottom of the reserve cup 27. It may be arranged. With such a configuration, the fuel is stably present at the bottom of the reserve cup 27 and the temperature of the fuel is also stable, so that the fuel temperature sensor 48 can be surely submerged, and the fuel temperature can be accurately varied without variation. Can be detected. As a result, the measurement accuracy of the fuel vapor pressure can be further improved.

(Second Embodiment)
Next, a second embodiment will be described. The basic configuration of the second embodiment is substantially the same as that of the first embodiment, except that an electromagnetic valve and a fuel temperature sensor are not incorporated in the fuel vapor generation unit. For this reason, in the following description, the same reference numerals are given to the same components as those in the first embodiment, and the description thereof will be omitted as appropriate. The engine control system according to the second embodiment will be mainly described with respect to the different components. This will be described with reference to FIGS. 11 and 12. FIG. 11 is a configuration diagram showing an outline of a main part of the engine control system according to the second embodiment. FIG. 12 is a flowchart showing the contents of a reed vapor pressure measurement routine in the engine control system.

  As shown in FIG. 11, the fuel vapor generation unit 40 b in the engine control system 10 a according to the second embodiment includes a nozzle 42, a vaporization chamber 45, a pressure sensor 46, and a venturi 47. That is, the solenoid valve and the fuel temperature sensor are not incorporated in the fuel vapor generation unit 40b. Such a fuel vapor generation part 40b is incorporated in the set plate 25 as in the first embodiment. Specifically, a first fuel passage 22 that supplies fuel from the fuel pump 26 to the injector 12 and a second fuel passage 23 that supplies fuel from the fuel pump 26 to the fuel vapor generation unit 40b are formed. The other end of the second fuel passage 23 is connected to the inlet of the fuel vapor generating unit 40b. When fuel of a constant pressure is supplied from the fuel pump 26 to the fuel vapor generating unit 40b, the fuel is vented from the nozzle 42. It is injected toward 47. At this time, as in the first embodiment, the pressure in the vaporization chamber 45 is detected by the pressure sensor 46 when the fuel is depressurized and boiled by the negative pressure generated in the vaporization chamber 45. It is like that.

  Next, the lead vapor pressure measurement in the engine control system 10a will be described with reference to FIG. Also in the engine control system 10a, when the engine 11 is started, the ECU 30 executes a lead vapor pressure measurement routine. When this lead vapor pressure measurement routine is executed, the ECU 30 determines whether or not the pressure measurement conditions (steps 30 and 31) are satisfied, as shown in FIG. Unlike the first embodiment, this measurement condition is that in this embodiment, refueling has been performed (step 30) and that a specified time has elapsed since the last engine stop (step 31). It is said. In addition, what is necessary is just to set time until fuel temperature and the cooling water temperature of the engine 11 become the same temperature as regulation time in step 31.

  When the above pressure measurement conditions are satisfied, the ECU 30 detects the pressure (P (T)) in the vaporization chamber 45 based on the signal from the pressure sensor 46 (step 32), and the engine 11 based on the signal from the water temperature sensor 33. The cooling water temperature is detected (step 33). Then, the ECU 30 calculates a temperature coefficient Ct (T) based on the coolant temperature detected in step 33 (step 34). Next, the reed vapor pressure RVP (37.8 ° C.) is calculated from the pressure P (T) detected in step 32 and the temperature coefficient Ct (T) calculated in step 34 based on the above conversion equation (step 35). ). Thereafter, the ECU 30 overwrites the RAM with the calculated lead vapor pressure RVP (37.8 ° C.) as the current lead vapor pressure RVP. As a result, the previous lead vapor pressure RVP is deleted and the current lead vapor pressure RVP is stored (step 36). That is, the reed vapor pressure RVP is updated when the fuel is replenished.

  Then, when the engine 11 is started next time, the ECU 30 reads the current reed vapor pressure RVP stored in step 36, and fuel based on the temperature coefficient (Ct (T 2)) calculated from the cooling water temperature of the engine 11 at that time. A vapor pressure VP is calculated. Then, the fuel injection amount is corrected based on the fuel vapor pressure VP, and the engine 11 is started (see FIG. 5).

  Thus, also in the engine control system 10a according to the second embodiment, the fuel injection control and the ignition timing control similar to those in the first embodiment are performed by the ECU 30, and the same effects as those in the first embodiment are achieved. Can be obtained. And in the engine control system 10a, since there is no electromagnetic valve and a fuel temperature sensor, cost reduction and size reduction can be further achieved. Since the lead vapor pressure is updated when the fuel is replenished, the fuel vapor pressure VP can be accurately measured even when the fuel property changes due to the fuel replenishment.

  It should be noted that the above-described embodiment is merely an example and does not limit the present invention in any way, and various improvements and modifications can be made without departing from the scope of the invention. For example, in the above-described embodiment, one end of the second fuel passage 23 is connected to the fuel pump 26, but one end of the second fuel passage 23 is connected to the first fuel passage 22 as shown in FIG. (Branch from the first fuel passage 22) is also possible.

  Further, in the first embodiment described above, the electromagnetic valve 41 that controls the inflow of fuel into the vaporizing chamber 45 is arranged on the upstream side of the vaporizing chamber 45. However, as shown in FIG. It can also arrange | position in the downstream of this.

  Furthermore, in the above-described embodiment, the pressure regulator 28 is disposed in the first fuel passage 22, but the pressure regulator 28 may be disposed in the fuel pump 26 or in the second fuel passage 23.

It is a lineblock diagram showing the outline of the engine control system concerning a 1st embodiment. It is sectional drawing which shows schematic structure of a fuel vapor generation part. It is a figure explaining the concept of a calculation process of reed vapor pressure. It is a figure explaining the concept of engine control at the time of engine starting. It is a flowchart which shows the content of the fuel supply control at the time of engine starting. It is a flowchart which shows the content of a lead vapor pressure measurement routine. It is a figure which shows the relationship between the ejection flow volume from a nozzle, and a vaporization chamber pressure. It is a figure which shows the relationship between a vaporization chamber pressure and a lead vapor pressure. It is a figure which shows the relationship between a fuel temperature and a temperature coefficient. It is a figure which shows the fuel vapor generation part which has arrange | positioned the fuel temperature sensor to the reserve cup bottom part. It is a block diagram which shows the outline of the principal part of the engine control system which concerns on 2nd Embodiment. It is a flowchart which shows the content of a lead vapor pressure measurement routine. It is a figure which shows the principal part of the engine control system which connected the 2nd fuel path to the 1st fuel path. It is a figure which shows the fuel vapor generation part which has arrange | positioned the solenoid valve to the upstream of a vaporization chamber.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Engine control system 11 Engine 12 Injector 19 Accelerator position sensor 20 Fuel tank 20a Mounting hole 21 Fuel pump unit 22 1st fuel passage 23 2nd fuel passage 25 Set plate 26 Fuel pump 27 Reserve cup 28 Pressure regulator 29 Float 30 Engine control unit (ECU)
33 Water temperature sensor 35 Spark plug 36 Igniter 40 Fuel vapor generating part 41 Solenoid valve 42 Nozzle 43 Valve element 45 Vaporization chamber 46 Pressure sensor 47 Venturi 48 Fuel temperature sensor

Claims (11)

A fuel tank in which fuel to be supplied to the internal combustion engine is stored;
A fuel pump for supplying fuel in the fuel tank to a fuel injection device;
A fuel vapor generating section that comprises a nozzle, a vaporization chamber, and a venturi, and vaporizes the fuel in the vaporization chamber by ejecting fuel from the nozzle and passing the venturi;
A first fuel passage connecting the fuel pump and the fuel injection device;
A second fuel passage having one end connected to the fuel pump or the first fuel passage and the other end connected to the fuel vapor generator;
Pressure detecting means for detecting the pressure in the fuel vapor generating section;
Fuel temperature detecting means for detecting the temperature of the fuel passing through the fuel vapor generating section;
Characteristic storage means for storing fuel vapor characteristics obtained based on the detection results of the pressure detection means and the detection results of the fuel temperature detection means;
The vapor pressure calculating means for calculating the vapor pressure of the fuel based on the fuel vapor characteristics stored in the characteristic storage means and the fuel temperature detected by the fuel temperature detecting means;
A fuel vapor pressure measuring device comprising: A fuel tank in which fuel to be supplied to the internal combustion engine is stored;
A fuel pump for supplying fuel in the fuel tank to a fuel injection device;
A fuel vapor generating section that comprises a nozzle, a vaporization chamber, and a venturi, and vaporizes the fuel in the vaporization chamber by ejecting fuel from the nozzle and passing the venturi;
A first fuel passage connecting the fuel pump and the fuel injection device;
A second fuel passage having one end connected to the fuel pump or the first fuel passage and the other end connected to the fuel vapor generator;
Pressure detecting means for detecting the pressure in the fuel vapor generating section;
Fuel temperature detecting means for detecting the temperature of the fuel passing through the fuel vapor generating section;
Refrigerant temperature detecting means for detecting the temperature of the refrigerant for cooling the internal combustion engine;
Characteristic storage means for storing fuel vapor characteristics obtained based on the detection results of the pressure detection means and the detection results of the fuel temperature detection means;
The vapor pressure calculating means for calculating the vapor pressure of the fuel based on the fuel vapor characteristics stored in the characteristic storage means and the refrigerant temperature detected by the refrigerant temperature detecting means;
A fuel vapor pressure measuring device comprising: A fuel tank in which fuel to be supplied to the internal combustion engine is stored;
A fuel pump for supplying fuel in the fuel tank to a fuel injection device;
Refrigerant temperature detecting means for detecting the temperature of the refrigerant for cooling the internal combustion engine;
A fuel vapor generating section that comprises a nozzle, a vaporization chamber, and a venturi, and vaporizes the fuel in the vaporization chamber by ejecting fuel from the nozzle and passing the venturi;
A first fuel passage connecting the fuel pump and the fuel injection device;
A second fuel passage having one end connected to the fuel pump or the first fuel passage and the other end connected to the fuel vapor generator;
Pressure detecting means for detecting the pressure in the fuel vapor generating section;
Characteristic storage means for storing fuel vapor characteristics obtained based on the detection results of the pressure detection means and the detection results of the refrigerant temperature detection means;
The vapor pressure calculating means for calculating the vapor pressure of the fuel based on the fuel vapor characteristics stored in the characteristic storage means and the refrigerant temperature detected by the refrigerant temperature detecting means;
A fuel vapor pressure measuring device comprising: In the vapor pressure measuring device of any one of claims 1 to 3,
The characteristic storage means stores a reed vapor pressure as the fuel vapor characteristic. In the vapor pressure measuring device of any one fuel according to any one of claims 1 to 4,
The characteristic storage means updates the fuel vapor characteristic at a constant time period,
The vapor pressure calculating means calculates the vapor pressure of the fuel based on the updated fuel vapor characteristic and the temperature detected by the fuel temperature detecting means or the refrigerant temperature detecting means. Pressure measuring device. The fuel vapor pressure measuring device according to claim 5,
The fuel vapor pressure measuring device, wherein the characteristic storage means updates the fuel vapor characteristic each time the internal combustion engine is started. The fuel vapor pressure measuring device according to claim 5,
The fuel vapor pressure measuring device, wherein when the fuel is replenished to the fuel tank, the characteristic storage means updates the fuel vapor characteristic. In the vapor pressure measuring device of any one fuel according to any one of claims 1 to 4,
The fuel vapor pressure measuring apparatus according to claim 1, wherein the characteristic storage means stores a fuel vapor characteristic under an operating condition of the internal combustion engine in which an injection amount from the fuel injection device is reduced. In the vapor pressure measuring device of any one fuel according to claim 1 to claim 8,
A control valve that is arranged upstream or downstream of the nozzle and controls the inflow of fuel to the nozzle;
The fuel vapor pressure measuring device according to claim 1, wherein the control valve is opened when the fuel vapor characteristic stored in the characteristic storage means is obtained. A vapor pressure measuring device for any one of the fuels according to claim 1;
An operation control means for controlling the operation state of the internal combustion engine,
The control apparatus for an internal combustion engine, wherein the operation control means corrects a fuel injection amount in the fuel injection device based on a fuel vapor pressure calculated by the vapor pressure calculation means. A vapor pressure measuring device for any one of the fuels according to claim 1;
An operation control means for controlling the operation state of the internal combustion engine,
The control device for an internal combustion engine, wherein the operation control means corrects an ignition timing of the internal combustion engine based on a fuel vapor pressure calculated by the vapor pressure calculation means.

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