JP4238925B2 - Fuel property determination device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fuel nature determination apparatus capable of preventing a determination error of a fuel nature. <P>SOLUTION: In the fuel nature determination apparatus for an internal combustion engine, a torque limit control for limiting an output torque can be performed, after a start-up of the internal combustion engine is completed. The fuel nature determination apparatus determines a fuel nature of the internal combustion engine, based on a parameter corresponding to an output torque after the start-up of the internal combustion engine. The fuel nature determination apparatus changes a threshold for determining the fuel nature, if a torque limit control is not performed. <P>COPYRIGHT: (C)2008,JPO&amp;INPIT

Description

The present invention relates to a fuel property determining apparatus, particularly to determine the fuel property determination device property of the fuel supplied to the internal combustion engine.

2. Description of the Related Art Conventionally, a device that corrects a fuel injection amount in accordance with the properties of fuel supplied to an internal combustion engine is known (see, for example, Non-Patent Document 1). The fuel supplied to the internal combustion engine includes a fuel containing a large amount of low volatility components (hereinafter referred to as heavy fuel) and a fuel containing a large amount of high volatility components (hereinafter referred to as light fuel). ) When the fuel to the internal combustion engine is a heavy fuel, it is difficult to vaporize the fuel as compared with the case of a light fuel, and there is a possibility that a stable operation of the internal combustion engine cannot be obtained. In the above conventional apparatus, after the start of the internal combustion engine is started, a start time until the start is completed is detected, and it is determined whether or not the fuel property is heavy based on the start time. Then, the fuel injection amount to the internal combustion engine is corrected according to the determined fuel property. Therefore, according to the conventional apparatus, it is possible to ensure a stable operation in the internal combustion engine regardless of the fuel properties.
Toyota Technical Disclosure-Issue Number 4139 (Issue Date March 29, 1991)

  As described above, in the above-described conventional apparatus, the fuel property is determined based on the start time until the start is completed after the start of the internal combustion engine. That is, the fuel property is not determined unless the start of the internal combustion engine is completed. Therefore, in the above-described conventional device, when the start control similar to the normal time is performed in order to start the internal combustion engine in a situation where the fuel property is heavy, the start of the internal combustion engine will continue for a long time, There is a possibility that excellent startability cannot be ensured in an internal combustion engine.

  The present invention has been made in view of the above points, and has as its first object to provide a start control device for an internal combustion engine that can ensure excellent startability regardless of fuel properties. It is a second object of the present invention to provide a fuel property determination device capable of appropriately determining the fuel property in the device.

The first object is provided with a first start control which corresponds to the light quality fuel, the second start control means may perform the starting control corresponding to the heavy fuel, the internal combustion according to the first start control This is achieved by an internal combustion engine start control device that switches from the first start control to the second start control when the start is not completed within a predetermined time after the start of the engine.

  In the present invention, when the start of the internal combustion engine is not completed within a predetermined time after the start of the internal combustion engine is started by the first start control corresponding to the light fuel, the internal combustion engine is caused by the heavy fuel property. It can be determined that the start of the engine is not completed promptly. In this case, the start control is switched from the first start control to the second start control corresponding to the heavy fuel. Therefore, according to the present invention, the internal combustion engine can be reliably started even when the fuel property is heavy.

In the above-described start control device for the internal combustion engine, the start control means executes the first or second start control according to the fuel property at the previous start of the internal combustion engine, and uses the internal combustion engine as a power source. A generator for generating power, and a fuel property determining means for determining a fuel property based on a power generation amount of the generator after the start is completed when the start of the internal combustion engine is started by the second start control; The start control device for an internal combustion engine having the above is effective in determining the fuel property when the start is started by the second start control corresponding to the heavy fuel.

  In the present invention, when the internal combustion engine is started, the first start control or the second start control is executed according to the fuel properties at the previous start. When the start of the internal combustion engine is started by the second start control, the start of the internal combustion engine is completed in a short time even if the current fuel property is heavy. For this reason, when the start of the internal combustion engine is started by the second start control, it is not appropriate to determine the fuel property based on whether the start is completed within a predetermined time thereafter. In contrast, in the present invention, in the above case, the fuel property is determined based on the power generation amount of the generator that generates power using the internal combustion engine as a power source after the start of the internal combustion engine is completed. When the fuel property is heavy, the number of revolutions after the start of the internal combustion engine is reduced, and the power generation amount of the generator is reduced. Therefore, according to the present invention, when the start is started by the second start control corresponding to the heavy fuel, the amount of power generated by the generator that generates power using the internal combustion engine as a power source is detected. The property can be determined.

In the internal combustion engine start control device, the internal combustion engine can execute the torque limit control for limiting the output torque after the start is completed, and when the torque limit control is executed, the fuel property determination means An internal combustion engine start control device comprising threshold value changing means for changing the threshold value for determining the fuel property by means of a case where the torque limit control is not executed is provided by the generator This is effective in preventing misjudgment of fuel properties when the amount of power generation varies.

  In the present invention, in the internal combustion engine, torque limit control in which the output torque is limited after the start is completed can be executed. When torque limit control is performed, the output torque of the internal combustion engine is limited. Therefore, the fuel property that is determined based on the power generation amount of the generator that generates power using the internal combustion engine as a power source may be erroneously determined. is there. In the present invention, when the torque limit control is executed, the threshold value for the power generation amount of the generator for determining the fuel property is changed with respect to the case where the torque limit control is not executed. Therefore, according to the present invention, when the power generation amount of the generator fluctuates due to torque limit control, erroneous determination of fuel properties is prevented.

In the above-described internal combustion engine start control device, in the internal combustion engine, after the start is completed, the torque limit control for limiting the output torque can be executed, and when the torque limit control is being executed, the fuel property determination An internal combustion engine start control device including a property determination prohibiting unit that prohibits determination of fuel property by means for preventing erroneous determination of fuel property when the power generation amount of the generator fluctuates due to torque limit control. It is valid.

  In the present invention, determination of fuel properties is prohibited when torque limit control is being executed. For this reason, according to the present invention, erroneous determination of the fuel property is prevented when the power generation amount of the generator fluctuates due to torque limit control.

In the above-described internal combustion engine start control device, the air-fuel ratio control means for feedback control the air-fuel ratio toward the target value, and after the start of the internal combustion engine is completed by executing the second start control, the feedback An internal combustion engine start control device comprising start control end means for ending the second start control before the control is started has a problem caused by the second start control being executed for a long period of time. It is effective in suppressing.

  In the present invention, the air-fuel ratio is feedback controlled toward the target value. After the start of the internal combustion engine is completed due to the execution of the second start control, the second start control is ended before the feedback control is started. For this reason, according to the present invention, the second start control is not performed over a long period of time, and a reduction in fuel consumption due to fuel rich caused by the second start control is prevented, and exhaust emission is deteriorated. Is prevented.

By the way, when a plurality of second start controls are executed, if these second start controls are completed at the same time, the air-fuel ratio of the internal combustion engine becomes remarkably lean, and a misfire may occur in the internal combustion engine. Therefore, the start control apparatus for an internal combustion engine, the starting control ending means, said when the second start control has been executed multiple types simultaneously, shifting the timing of the second starting control the plurality of types each other By ending, it is possible to prevent the air-fuel ratio from becoming extremely lean after the end of the second start control, and to reliably avoid misfire of the internal combustion engine.

Further, the first object, in the start control device for an internal combustion engine fuel injection amount corresponding to the inhalation air amount is performed, after start up of the internal combustion engine, until the above start moving is completed, the intake air amount increases This is achieved by a start control device for an internal combustion engine provided with a throttle opening increasing means for changing the throttle opening.

  When the fuel injection amount is increased as the start control corresponding to the heavy fuel, the exhaust emission is deteriorated. In the present invention, after the start of the internal combustion engine is started, the intake air amount is increased until the start is completed, and proper fuel injection is performed for the intake air amount. According to such a method, when the fuel property is heavy, the vaporization of the fuel is promoted, and the internal combustion engine is started quickly. At this time, the fuel injection amount is always maintained at an appropriate amount with respect to the intake air amount. Therefore, according to the present invention, even when the fuel property is heavy, it is possible to reliably start the internal combustion engine without deteriorating exhaust emission.

The second object, after the starting of the internal combustion engine is completed, the fuel property determining apparatus for an internal combustion engine torque limit control can be performed where the output torque is limited, the fuel property of the internal combustion engine after completion of startup When the torque limit control is executed, the threshold value for determining the fuel property is changed with respect to the case where the torque limit control is not executed. This is achieved by a fuel property determination device including a threshold value changing means.

  In the present invention, in the internal combustion engine, torque limit control in which the output torque is limited after the start is completed can be executed, and the fuel property is determined based on a parameter corresponding to the output torque after the start of the internal combustion engine is completed. When the torque limit control is performed, the output torque is limited. Therefore, the fuel property determined based on the parameter corresponding to the output torque may be erroneously determined. In the present invention, when the torque limit control is executed, the threshold value for determining the fuel property is changed with respect to the case where the torque limit control is executed. As described above, if the threshold value for determining the fuel property is changed as the output torque is limited, the fuel property is erroneously determined under a situation where the parameter varies due to the torque limit control. Can be prevented.

Further, the second object, after the starting of the internal combustion engine is completed, the fuel property determining apparatus for an internal combustion engine torque limit control can be performed where the output torque is limited, the fuel property of the internal combustion engine, the starting The determination is made based on a parameter corresponding to the output torque after completion, and is achieved by a fuel property determination device including property determination prohibiting means for prohibiting determination of fuel property when the torque limit control is being executed.

  In the present invention, determination of fuel property is prohibited when torque limit control is being performed. For this reason, according to the present invention, it is possible to prevent erroneous determination of the fuel property when the parameter for determining the fuel property varies due to the torque limit control.

According to the present invention, erroneous determination of fuel properties can be prevented in a situation where parameters for determining fuel properties vary due to torque limit control.

  Hereinafter, specific embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 schematically shows a drive mechanism of a vehicle on which an internal combustion engine 10 according to a first embodiment of the present invention is mounted. FIG. 2 shows a configuration diagram of the internal combustion engine 10. The system of the present embodiment includes an electronic control unit (hereinafter referred to as ECU) 12 and is controlled by the ECU 12.

  The ECU 12 is connected to an ignition switch (hereinafter referred to as IG switch) 13 for switching between starting and stopping of the vehicle. The IG switch 13 includes an accessory switch, an on switch, and a starter switch. The ECU 12 determines whether or not the starter switch is on based on the output signal of the IG switch 13.

  The ECU 12 is also connected to a shift position sensor 14 that outputs a signal corresponding to the shift position of the transmission, and a brake switch 15 that outputs an ON signal when the brake pedal is operated. The ECU 12 determines whether or not the shift position is in the parking range (P range) based on the output signal of the shift position sensor 14 and determines whether or not the brake pedal is operated based on the output signal of the brake switch 15. Is determined.

  In the present embodiment, the vehicle enters the starting state when the starter switch is turned on under the condition that the shift position is in the P range and the brake pedal is operated. After the start is started, the internal combustion engine 10 is in an operating state until the warm-up is completed, and is stopped when the warm-up is completed.

  As shown in FIG. 1, the left wheel FL and the right wheel FR of the vehicle are connected via an axle 16. A reduction gear 18 is attached to the axle 16. A planetary gear mechanism 20 is engaged with the reduction gear 18 via a gear 19. In the vehicle, a generator 22 and an auxiliary motor 24 are mounted as a drive source together with the internal combustion engine 10. The planetary gear mechanism 20 includes a planetary carrier connected to the output shaft of the internal combustion engine 10, a sun gear connected to the output shaft of the generator 22, and a ring gear connected to the output shaft of the auxiliary motor 24. Generator 22 and auxiliary motor 24 are electrically connected to battery 28 via inverter 26. A main relay 29 is provided between the inverter 26 and the battery 28. The main relay 29 has a function of conducting or cutting off the power circuit from the battery 28 to the inverter 26 by being driven by the ECU 12.

  Inverter 26 converts a direct current and a three-phase alternating current between battery 28 and generator 22 and between battery 28 and auxiliary motor 24 by a three-phase bridge circuit composed of a plurality of power transistors, respectively. It has a function. The generator 22 and the auxiliary motor 24 are each controlled to have a rotational speed corresponding to the frequency of the alternating current by appropriately driving the power transistor in the inverter 26 by the ECU 12, and according to the magnitude of the current. Generate torque.

  The generator 22 has a function as a starter motor that starts the internal combustion engine 10 when electric power is supplied from the battery 28 via the inverter 26 when the start of the internal combustion engine 10 is not completed. It has a function as a generator that supplies electric power to the battery 28 or the auxiliary motor 24 via the inverter 26 by the output of the internal combustion engine 10 after the start is completed. Further, the auxiliary motor 24 has a function as an electric motor that applies torque to the axle 16 to assist the output of the internal combustion engine 10 by appropriately supplying electric power during normal traveling, and at the time of vehicle braking. It has a function as a generator that supplies electric power to the battery 28 via the inverter 26 by the rotation of 16.

  According to the above configuration, part of the kinetic energy of the internal combustion engine 10 is converted into electric power generated by the generator 22, and part of the kinetic energy during deceleration is converted into electric power generated by the auxiliary motor 24. Thus, the battery 28 can be recovered, whereby the battery 28 can be charged without providing a separate charger outside the battery 28.

  The inverter 26 incorporates a current detection circuit for detecting a current value supplied to the generator 22 and a voltage detection circuit for detecting a voltage value applied to the generator 22, and a current to the auxiliary motor 24. A current detection circuit for detecting a value and a voltage detection circuit for detecting a voltage value to the auxiliary motor 24 are incorporated. Both output signals of these current values and voltage values are supplied to the ECU 12. The ECU 12 detects a current value and a voltage value to the generator 22 and the auxiliary motor 24 based on those output signals, and detects an output torque of the generator 22 and the auxiliary motor 24 based on these values. Hereinafter, the direction of the output torque STG when the generator 22 functions as an electric motor is a positive direction, and the direction of the output torque STG when it functions as a generator is a negative value. The output torque STG of the generator 22 is converted into the amount of power generated by reversing the positive and negative.

  Thus, in the present embodiment, the vehicle constitutes a hybrid vehicle that travels by appropriately combining two power sources of the internal combustion engine 10 and the auxiliary motor 24. In other words, in the present embodiment, the ECU 10 maintains the internal combustion engine 10 in a stopped state under a situation where the engine efficiency is low, such as when starting or running at a low speed, and from the battery 28 to the auxiliary motor 24 via the inverter 26. By supplying electric power, the auxiliary motor 24 generates torque for running the vehicle. Further, the ECU 12 calculates a required driving force required for the vehicle based on the accelerator operation amount and the vehicle speed, and operates the internal combustion engine 10 in an efficient operating region with respect to the driving force, and the internal combustion engine 10 and the auxiliary motor 24. The torque ratio with respect to the axle 16 is controlled.

  Next, the structure of the internal combustion engine 10 of the present embodiment will be described.

  As shown in FIG. 2, the internal combustion engine 10 includes a cylinder block 30. A water jacket 32 is formed in the wall of the cylinder block 30. The cylinder block 30 is provided with a water temperature sensor 34 so that the tip end portion is exposed in the water jacket 32. The water temperature sensor 34 outputs a signal corresponding to the temperature of the cooling water flowing through the water jacket 32 to the ECU 12. The ECU 12 detects the coolant temperature THW of the coolant of the internal combustion engine 10 based on the output signal of the coolant temperature sensor 34.

  Inside the cylinder block 30 are accommodated pistons 36 provided in the same number as the number of cylinders. A crankshaft 40 is connected to the piston 36 via a connecting rod 38. A crank angle sensor 26 is disposed inside the cylinder block 30 such that the tip portion faces the surface of the crankshaft 40. The crank angle sensor 42 generates a reference signal every time the rotation angle of the crankshaft 40 reaches the reference rotation angle, and outputs a pulse signal every time the crankshaft 40 rotates by a predetermined rotation angle (for example, 30 ° CA). The ECU 12 detects the engine speed NE and the crank angle CA of the internal combustion engine 10 based on the output signal of the crank angle sensor 42.

  A cylinder head 44 is fixed to the upper end of the cylinder block 30. A combustion chamber 46 is formed in a portion surrounded by the cylinder block 30, the cylinder head 44, and the piston 36. The cylinder head 44 is formed with an intake port 48 and an exhaust port 50 that communicate with the combustion chamber 46. Further, the cylinder head 44 includes an intake valve 52 for connecting or blocking the intake port 48 and the combustion chamber 46, an exhaust valve 54 for connecting or blocking the exhaust port 50 and the combustion chamber 46, and a tip portion of the cylinder head 44 for the combustion chamber 46. A spark plug 56 exposed to the inside is incorporated. The intake valve 52, the exhaust valve 54, and the spark plug 56 are provided corresponding to each cylinder of the internal combustion engine 10, respectively. The intake valve 52 and the exhaust valve 54 are each configured to be opened and closed at a predetermined timing in synchronization with the rotation of the crankshaft 40 by a cam mechanism (not shown). In the present embodiment, the cam mechanism on the intake valve 52 side is configured such that the phase thereof can be changed to the advance side and the retard side by a predetermined angle.

  An intake manifold 58 communicates with the intake port 48. An injector 60 is disposed in the intake manifold 58. A fuel pump is connected to the injector 60 via a fuel pipe (not shown). The ECU 60 is electrically connected to the injector 60. The ECU 12 supplies a drive signal to the injector 60 so that fuel injection according to the operating state of the internal combustion engine 10 is performed. The injector 60 injects an appropriate amount of fuel into the intake manifold 58 at an appropriate timing in accordance with a drive signal from the ECU 12.

  An intake passage 64 communicates with the intake manifold 58 via a surge tank 62. A throttle valve 66 that opens and closes in conjunction with an accelerator pedal (not shown) is disposed inside the intake passage 64. The throttle valve 66 opens and closes using a throttle motor 67 electrically connected to the ECU 12 as a power source. The throttle motor 67 has a function of opening and closing the throttle valve 66 in accordance with a drive signal from the ECU 12.

  A throttle position sensor 68 is disposed in the vicinity of the throttle valve 66. The throttle position sensor 68 outputs a signal corresponding to the opening degree of the throttle valve 66 to the ECU 12. The ECU 12 detects the throttle opening θ based on the output signal of the throttle position sensor 68.

  An air flow meter 70 and an intake air temperature sensor 72 are also disposed in the intake passage 64. The air flow meter 70 outputs a signal corresponding to the intake air amount of the air flowing through the intake passage 64 to the ECU 12. The intake air temperature sensor 72 outputs a signal corresponding to the temperature of the air flowing through the intake passage 64 to the ECU 12. The ECU 12 detects the intake air amount VA and the intake air temperature THA of the air flowing into the internal combustion engine 10 based on the output signal of the air flow meter 70 and the output signal of the intake air temperature sensor 72.

  An exhaust manifold 74 communicates with the exhaust port 50 of the internal combustion engine 10. An O2 sensor 76 is disposed on the exhaust manifold 74. The O2 sensor 76 outputs a signal corresponding to the oxygen concentration in the exhaust gas. The oxygen concentration in the exhaust gas becomes leaner as the air-fuel ratio A / F of the air-fuel mixture supplied to the internal combustion engine 10 becomes richer in fuel, and becomes richer as the air-fuel ratio A / F of the air-fuel mixture becomes fuel lean. Become. The O2 sensor 76 is 0.9 V when the air-fuel ratio A / F of the air-fuel mixture supplied to the internal combustion engine 10 is rich in fuel as compared with a target air-fuel ratio that is determined that a catalytic converter described later functions effectively. On the other hand, when the air-fuel ratio A / F is leaner than the target air-fuel ratio, a low signal of about 0.1 V is output to the ECU 12.

  The ECU 12 determines whether the air-fuel ratio A / F of the air-fuel mixture supplied to the internal combustion engine 10 is fuel rich or fuel lean based on the output signal of the O2 sensor 76. The exhaust manifold 74 communicates with a catalytic converter 78 that purifies exhaust gas using a three-way catalyst. The exhaust gas discharged from the internal combustion engine 10 is purified by flowing into the catalytic converter 78 and then released into the atmosphere.

  The internal combustion engine 10 includes an igniter 80 and an ignition coil 82 for each cylinder. Each of the igniters 80 is electrically connected to the ECU 12. When an ignition signal is supplied from the ECU 12 at a timing when ignition is to be performed in its own cylinder, the igniter 80 is primary to the ignition coil 82 in synchronization with the ignition signal. Supply current. When the primary current is supplied to the ignition coil 82, a high-pressure ignition signal is generated on the secondary side of the ignition coil 82. The ignition plug 56 is connected to the secondary side of the ignition coil 82. The spark plug 56 generates a spark inside the combustion chamber 46 when a high-pressure ignition signal is supplied from the ignition coil 82.

  In the system of the present embodiment, the internal combustion engine 10 is started when the starter switch is turned on. When the start of the internal combustion engine 10 is started, the generator 22 is energized to start cranking the internal combustion engine 10, inject a predetermined amount of fuel into the internal combustion engine 10 at a predetermined timing, and At this timing, a spark is generated from the spark plug 56. After the start of the internal combustion engine 10 is completed, the fuel injection amount calculated based on the operating state of the internal combustion engine 10 is corrected so that the air-fuel ratio becomes the target air-fuel ratio, and according to the corrected fuel injection amount. Perform fuel injection. Hereinafter, control for correcting the fuel injection amount so that the air-fuel ratio becomes the target air-fuel ratio is referred to as air-fuel ratio feedback control (air-fuel ratio F / B control).

  By the way, the fuel supplied to the internal combustion engine 10 includes fuels having various properties from heavy fuel that is hard to vaporize to light fuel that is easy to vaporize. If fuel injection is performed on the internal combustion engine 10 without considering the fuel properties when the fuel properties are heavy, there is a possibility that stable operation of the internal combustion engine cannot be obtained. In particular, when the start control similar to the case where the fuel property is light at the time of starting the internal combustion engine 10 is executed, the fuel is not sufficiently vaporized and the start of the internal combustion engine 10 may not be completed quickly. Accordingly, in order to quickly start the internal combustion engine 10, it is appropriate to accurately detect the fuel property at the time of start and change the initial start control to an appropriate start control corresponding to the fuel property. .

  As a method for detecting the fuel property, it is conceivable to detect the fuel property based on the starting time after the start of the internal combustion engine 10 until the start is completed. However, in this method, since the fuel property is not detected unless the start of the internal combustion engine 10 is completed, the start control corresponding to the heavy fuel is not performed even though the fuel property is heavy. If the start-up is not completed, a situation in which the fuel property cannot be detected may occur. For this reason, in the above method, it is not possible to execute appropriate start control corresponding to the fuel properties, and there is a possibility that the internal combustion engine 10 cannot be started.

  On the other hand, in the system of the present embodiment, the property of the fuel supplied to the internal combustion engine 10 is determined based on whether the start is completed within a predetermined time after the start of the internal combustion engine 10 is started. Whether or not is heavy. If it is determined that the internal combustion engine 10 has not been started within the predetermined time and the fuel property is heavy, (1) compared to normal times, the internal combustion engine 10 should be started quickly. Processing for increasing the valve overlap between the intake valve 52 and the exhaust valve 54 by setting the opening / closing timing of the intake valve 52 to the most advanced angle (hereinafter referred to as valve opening timing advance control), (2) Intake of fuel injection Processing (hereinafter referred to as intake synchronous injection control) performed when the valve 52 is opened, and (3) processing (hereinafter referred to as injection amount increase control) for increasing the fuel injection amount as compared with the normal time are executed. . Hereinafter, the processes (1) to (3) are collectively referred to as heavy fuel start control, and the control when the processes (1) to (3) are not performed is referred to as normal start control.

  According to the above system, the fuel property can be reliably detected every time the internal combustion engine 10 is started, and the heavy fuel start control is performed instead of the normal start control when the fuel property is heavy. Can be executed. When the heavy fuel start control is executed, the internal combustion engine 10 starts quickly because the fuel is more easily vaporized than during the normal start control.

  By the way, if the fuel property at the time of the previous start of the internal combustion engine 10 is heavy, the fuel property is maintained heavy unless a new fuel supply is performed to the vehicle thereafter. Therefore, in the system of the present embodiment, in order to quickly complete the start of the internal combustion engine 10, the fuel properties at the previous start of the internal combustion engine 10 are stored, and when the fuel properties are heavy, the internal combustion engine 10 The heavy fuel start control is executed immediately after the start is started.

  Even when the heavy fuel start control is performed immediately after the start of the internal combustion engine 10, it is necessary to accurately detect the fuel property at the start. However, when the heavy fuel start control is performed immediately after the start of the internal combustion engine 10, the start of the internal combustion engine 10 is completed quickly regardless of the fuel properties, and thus the fuel properties are heavy. It is not appropriate to determine whether or not the engine has been started within a predetermined time after the start of the internal combustion engine 10 as described above.

  The rotation of the internal combustion engine 10 tends to become unstable as the fuel property becomes heavier. As described above, in this embodiment, the generator 22 that generates electric power by the output of the internal combustion engine 10 is provided. Therefore, in this embodiment, when the fuel property is heavy, the power generation amount of the generator 22 after the start of the internal combustion engine 10 is small, and when the fuel property is light, the power generation amount of the generator 22 is large. .

  Therefore, in the system of the present embodiment, when heavy fuel start control is performed immediately after the start of the internal combustion engine 10, the fuel property is detected and the internal combustion engine 10 is started within a predetermined time after the start of the start. The determination is made based on the power generation amount of the generator 22 instead of the completion. If the fuel property is detected based on the power generation amount of the generator 22 even when the normal start control is performed, the internal combustion engine 10 is started when the actual fuel property is heavy. Is not completed, that is, the generator 22 may not generate power. Therefore, in the system of the present embodiment, when normal start control is performed, the fuel property is not detected based on the power generation amount of the generator 22. As described above, the fuel property is detected based on whether the start of the internal combustion engine 10 is completed within a predetermined time after the start of the start.

  Hereafter, the characteristic part of a present Example is demonstrated with reference to FIG. 3 thru | or FIG.

  FIG. 3 schematically shows a fuel property detection method used in this embodiment. 3A shows the case where the fuel property at the previous start of the internal combustion engine 10 is light, and FIG. 3B shows the case where the fuel property at the previous start is heavy. Show.

  As shown in FIG. 3A, when the fuel property at the previous start is light, the start of the internal combustion engine 10 is started by the normal start control (TST = 0). If the start of the internal combustion engine 10 is completed within a predetermined time (TST = T1), it is determined that the current fuel property is light. On the other hand, if the start of the internal combustion engine 10 is not completed within a predetermined time, it is determined that the current fuel property is heavy, and instead of the normal start control, the start of the internal combustion engine 10 is completed quickly. Heavy fuel start-up control is executed.

  As shown in FIG. 3B, when the fuel property at the previous start is heavy, the internal combustion engine 10 is started by heavy fuel start control (TST = 0). As described above, the power generation amount of the generator 22 is obtained by reversing the positive / negative of the output torque STG. If the output torque STG of the generator 22 when the start of the internal combustion engine 10 is completed is smaller than the predetermined value A, it is determined that the current fuel property is light. On the other hand, when the output torque STG of the generator 22 when the start of the internal combustion engine 10 is completed is equal to or greater than the predetermined value A, it is determined that the current fuel property is heavy.

  FIG. 4 shows a flowchart of an example of a control routine executed by the ECU 12 in this embodiment to start the internal combustion engine 10. The routine shown in FIG. 4 is a routine that is repeatedly activated every time the process is completed. When the routine shown in FIG. 4 is started, first, the process of step 100 is executed.

  In step 100, whether or not the conditions for starting the internal combustion engine 10 are satisfied, specifically, in the state where the shift lever is in the P range and the brake pedal is depressed, the IG switch 13 is built in. It is determined whether or not the starter switch to be turned on is ON. The process of step 100 is repeatedly started until it is determined that the above condition is satisfied. As a result, if it is determined that the above condition is satisfied, the process of step 102 is executed next.

  In step 102, a process for resetting the start completion flag XST for the internal combustion engine 10 is executed. The start completion flag XST is a flag for displaying whether or not the internal combustion engine 10 has been started. When the process of step 102 is completed, the process of step 104 is executed next.

  In step 104, it is determined whether or not the heavy flag XHD regarding the property of the fuel supplied to the internal combustion engine 10 is set. The heavy flag XHD is a flag for displaying whether or not the fuel property is heavy. As a result of the above processing, when it is determined that the heavy flag XHD is not set, the processing of step 106 is executed next.

  In step 106, it is determined whether or not the generator 22 has started power generation based on the output signals of the current detection circuit and the voltage detection circuit for the generator 22 built in the inverter 26. Specifically, the state in which the generator 22 is energized by the battery 28 as a starter motor is switched to a state in which power is generated as a generator when the start of the internal combustion engine 10 is completed, that is, the output torque STG of the generator 22 is positive. The value is changed to a negative value, and it is determined whether or not the state continues for a predetermined time (for example, 0.4 seconds). As a result, if it is determined that the generator 22 is not generating power, the process of step 108 is executed next.

  In step 108, it is determined whether or not the time TST after the start start condition of the internal combustion engine 10 in step 100 has reached a predetermined time T1. The predetermined time T1 is the maximum value of the time until the start is completed after the start start condition of the internal combustion engine 10 is satisfied, which can be determined that the fuel property is light. If TST> T1 does not hold as a result of the above processing, it is not necessary to execute heavy fuel start control for the internal combustion engine 10. Therefore, if such a determination is made, the process of step 110 is executed next.

  In step 110, a process of starting normal start control for the internal combustion engine 10 is executed. After the processing of step 110 is performed, the processing of step 106 is repeatedly executed.

  On the other hand, if TST> T1 is satisfied in step 108, it can be determined that the nature of the fuel supplied to the internal combustion engine is heavy, and the start of the internal combustion engine 10 is completed only by executing the normal start control. It can be judged that it cannot be made. In such a case, it is appropriate to execute the heavy fuel start control for the internal combustion engine 10. Therefore, if it is determined in step 108 that TST> T1 is satisfied, the process of step 112 is then executed.

  In step 112, processing for setting the heavy flag XHD is executed. When the process of step 112 is completed, the process of step 114 is executed next.

  In step 114, it is determined whether or not the time TST after the start start condition of the internal combustion engine 10 is satisfied in step 100 has reached a predetermined time T2. The predetermined time T2 is the minimum value of the time until the start is completed after the start condition for starting the internal combustion engine 10 is established, which can be determined that the power of the battery 28 is excessively consumed. If TST> T2 does not hold as a result of the above processing, it is appropriate to execute heavy fuel start control for the internal combustion engine 10. Therefore, if such a determination is made, the process of step 116 is executed next. On the other hand, if TST> T2 is established, it can be determined that some trouble has occurred in the internal combustion engine 10. In this case, it is appropriate to quickly stop the internal combustion engine 10 from starting. Therefore, if it is determined that TST> T2 is satisfied, the process of step 118 is executed next.

  In step 116, processing for starting heavy fuel start control for the internal combustion engine 10 is executed. Specifically, compared with the case where the normal start control in step 110 is executed, (1) the valve overlap between the intake valve 52 and the exhaust valve 54 is made by setting the opening / closing timing of the intake valve 52 to the most advanced angle. (2) The fuel injection is performed when the intake valve 52 is opened, and (3) the fuel injection amount is increased. When the process of step 116 is completed, the process of step 106 is repeatedly executed.

  In step 118, processing for stopping the start control of the internal combustion engine 10 is executed. When this step 118 is finished, the current routine is finished.

  If the generator 22 is generating power in step 106, it can be determined that the generator 22 is rotating with the operation of the internal combustion engine 10 without being energized from the battery 28. In this case, it can be determined that the internal combustion engine 10 has been started. Therefore, if such a determination is made in step 106, the process of step 120 is executed next.

  In step 120, processing for setting a start completion flag XST for the internal combustion engine 10 is executed. When the process of step 120 is finished, the current routine is finished.

  If it is determined in step 104 that the heavy flag XHD is set, the process of step 122 is executed next.

  In step 122, similar to step 116, processing for starting heavy fuel start control for the internal combustion engine 10 is executed. When the process of step 122 is executed, the process of step 124 is executed next.

  In step 124, as in step 106, it is determined whether or not the generator 22 has started power generation. As a result, when it is determined that the generator 22 is not generating power, the process of step 126 is performed next. On the other hand, if it is determined that the generator 22 is generating power, the process of step 128 is performed next.

  In step 126, as in step 114, it is determined whether or not the time TST after the start start condition of the internal combustion engine 10 has reached a predetermined time T2. As a result, if it is determined that TST> T2 is not established, the heavy fuel start control is continued in step 122. On the other hand, if it is determined that TST> T2 holds, the routine is terminated after the start control of the internal combustion engine 10 is stopped in step 118.

  In step 128, processing for setting a start completion flag XST for the internal combustion engine 10 is executed. When the process of step 128 is completed, the process of step 130 is executed next.

  In step 130, it is determined whether or not the output torque STG of the generator 22 is smaller than the predetermined value A. The predetermined value A is the minimum value of the output torque STG (maximum value of the power generation amount) that can be determined that the fuel property is heavy when the heavy fuel start control is executed, and is set to a negative value in advance. Is set. As a result of the above processing, if it is determined that STG <A is not satisfied, that is, STG ≧ A is satisfied, the processing of step 132 is executed next.

  In step 132, it is determined whether or not the time t after the start completion flag XST is set in step 128 has passed a predetermined time t0. As a result, when it is determined that t ≧ t0 is not established, the process of step 130 is repeatedly executed. On the other hand, if t ≧ t0 holds, it can be determined that the amount of power generated by the generator 22 does not increase within the predetermined time t0, and the fuel property is heavy. Therefore, when such a determination is made, the current routine is terminated.

  When STG <A is established in step 130, it can be determined that the power generation amount of the generator 22 is large and the fuel property is light. Therefore, if such a determination is made, the process of step 134 is executed next.

  In step 134, processing for resetting the heavy flag XHD is executed. When the processing of step 134 is completed, the current routine is terminated.

  According to the above processing, when the internal combustion engine 10 is started, the start control corresponding to the fuel property at the previous start of the internal combustion engine 10 can be executed. That is, when the fuel property is light, the internal combustion engine 10 is started by the normal start control. On the other hand, when the fuel property is heavy, the internal combustion engine 10 is started by the heavy fuel start control. Is started. For this reason, according to the present embodiment, when the fuel property at the time of the previous start of the internal combustion engine 10 is heavy, the heavy fuel start control is executed immediately after the start of the start of the internal combustion engine 10. It becomes possible to complete start-up promptly.

  Further, according to the above processing, when the start of the internal combustion engine 10 is started by the normal start control, the fuel properties are overlapped based on whether the start of the internal combustion engine 10 is completed within a predetermined time T1 thereafter. When the start of the internal combustion engine 10 is not completed within the predetermined time T1, while the normal start control is continued until the predetermined time T1 elapses after the start of the engine. The heavy fuel start control can be executed instead of the normal start control on the assumption that the fuel property is heavy. That is, according to the present embodiment, the actual fuel property is heavy under the situation where the start of the internal combustion engine 10 is started by the normal start control on the assumption that the fuel property at the previous start of the internal combustion engine 10 is light. In some cases, the start control can be changed to an appropriate start control corresponding to the fuel property. Therefore, according to the system of the present embodiment, even when the fuel property is heavy, it is possible to complete the start-up of the internal combustion engine 10 reliably and promptly, and the internal combustion engine 10 is excellent regardless of the fuel property. It is possible to ensure startability.

  Further, according to the above processing, when the internal combustion engine 10 is started by the heavy fuel start control, the fuel property is heavy based on the output torque of the generator 22 at the completion of the start, that is, the amount of power generation. It can be determined whether or not. Therefore, according to the present embodiment, when the internal combustion engine 10 is started by the heavy fuel start control, it is avoided that the current fuel property becomes undetectable, and the fuel property is accurately detected. be able to. Therefore, according to the system of the present embodiment, it is possible to execute appropriate start control corresponding to the fuel property even when the internal combustion engine 10 is started next time.

  In this embodiment, after the start of the internal combustion engine 10 is started by the normal start control or the heavy fuel start control, when the start is not completed within the predetermined time T2, the start of the internal combustion engine 10 is considered as a malfunction. Control is to be stopped. For this reason, according to the present embodiment, it is possible to prevent excessive power consumption of the battery 28 due to malfunction of the internal combustion engine 10.

  FIG. 5 shows a flowchart of an example of a control routine executed by the ECU 12 in this embodiment in order to switch from the start control of the internal combustion engine 10 to the air-fuel ratio F / B control. The routine shown in FIG. 5 is a routine that is repeatedly activated every time the process is completed. When the routine shown in FIG. 5 is started, the process of step 140 is first executed.

  In step 140, it is determined whether or not the start completion flag XST for the internal combustion engine 10 is set as a result of processing the routine shown in FIG. The process of step 140 is repeatedly executed until it is determined that the start completion flag XST is set. As a result, when it is determined that the start completion flag XST is set, the process of step 142 is executed next.

  In step 142, it is determined whether or not an air-fuel ratio F / B control start condition is satisfied. Specifically, after the start of the internal combustion engine 10 is completed, the water temperature THW of the cooling water flowing through the internal combustion engine 10 is equal to or higher than a predetermined temperature, and the air-fuel ratio of the internal combustion engine 10 is compared with the target air-fuel ratio. It is then determined whether the fuel is rich or lean. The process of step 142 is repeatedly executed until the start condition of the air-fuel ratio F / B control is satisfied. As a result, if it is determined that the above condition is satisfied, the process of step 144 is executed next.

  In step 144, it is determined whether or not the property of the fuel supplied to the internal combustion engine 10 is heavy as a result of processing the routine shown in FIG. As a result, when it is determined that the fuel property is not heavy, the process of step 146 is executed next. On the other hand, if it is determined that the fuel property is heavy, the process of step 148 is performed next.

  In step 146, processing for ending the normal start control is executed.

  In step 148, processing for ending the heavy fuel start control is executed.

  In step 150, a process for starting air-fuel ratio F / B control is executed. After the processing of step 150 is executed, the fuel injection is controlled in the internal combustion engine 10 so that the air-fuel ratio becomes the target air-fuel ratio. When the processing of step 150 is finished, the current routine is finished.

  According to the above processing, when the start condition of the air-fuel ratio F / B control is satisfied after the start of the internal combustion engine 10 is completed, the start control of the internal combustion engine 10 is ended, and thereafter the air-fuel ratio F / B Control can begin. For this reason, according to the present embodiment, the heavy fuel start control is prevented from being executed for a long period of time. Therefore, according to the system of the present embodiment, it is possible to prevent a decrease in fuel consumption of the internal combustion engine 10 by suppressing the air-fuel ratio from becoming rich due to the execution of the heavy fuel start control. In addition, the exhaust emission can be prevented from deteriorating.

  Next, a second embodiment of the present invention will be described with reference to FIGS. The system of the present embodiment is realized by the ECU 12 executing the routine shown in FIG. 8 in the internal combustion engine 10 shown in FIGS.

  FIG. 6A shows a case where (1) valve opening timing advance control, (2) intake-synchronized injection control, and (3) injection amount increase control are all ended simultaneously at the end of heavy fuel start control. An example of the time change of the advance angle evt of the intake valve 52, the end timing angle einjend of the fuel injection, and the fuel injection amount increase rate efmwst is shown. 6B shows the time of the air-fuel ratio A / F of the internal combustion engine 10 obtained when the advance angle evt, the end timing angle einjend, and the increase rate efmwst are changed as shown in FIG. 6A. Showing change.

  As shown in FIG. 6A, after the start of the internal combustion engine 10 is started at time t = 0, if the start condition for the heavy fuel start control is satisfied in the vicinity of time t = 8, the intake valve 52 The advance angle evt is increased, the fuel injection end timing angle einjend is retarded, and the fuel injection amount increase rate efmwst is increased. In this case, the valve overlap between the intake valve 52 and the exhaust valve 54 increases, fuel injection is performed when the intake valve 52 is opened, and the fuel injection amount is increased, so that the internal combustion engine 10 is started. It will be completed promptly. After that, when the condition for ending the heavy fuel start control is satisfied, the processes (1) to (3) are simultaneously ended, and the start control of the internal combustion engine 10 is changed from the heavy fuel start control to the normal start control. Switch.

  By the way, when the processes (1) to (3) performed in the heavy fuel start control are completed, that is, the process for reducing the increased valve overlap, the fuel being performed when the intake valve 52 is opened. When the process of performing the injection when the intake valve 52 is closed as usual, or the process of reducing the increased fuel injection amount, the air-fuel ratio in the internal combustion engine 10 shifts to the fuel lean side. For this reason, as shown in FIG. 6 (A), when the processes (1) to (3) are simultaneously ended (near t = 18) in order to end the heavy fuel start control, immediately after that, FIG. As shown in (B), the air-fuel ratio A / F becomes extremely lean in the internal combustion engine 10, and the air-fuel mixture supplied to the internal combustion engine 10 may not burn, that is, misfire may occur.

  Therefore, in order to prevent the occurrence of misfire in the internal combustion engine 10 under the situation where the heavy fuel start control is terminated, it is not appropriate to terminate the processes (1) to (3) at the same time. Therefore, in this embodiment, when the heavy fuel start control is terminated and returned to the normal start control, the above processes (1) to (3) are terminated at different times.

  FIG. 7 (A) shows the advance angle evt of the intake valve 52 and the end of fuel injection when the processes (1) to (3) are ended at different times at the end of the heavy fuel start control. An example of the temporal change of the timing angle einjend and the fuel injection amount increase rate efmwst will be shown. 7B is obtained when the advance angle evt of the intake valve 52, the fuel injection end timing angle einjend, and the fuel injection amount increase rate efmwst are changed as shown in FIG. 7A. The time change of the air fuel ratio A / F of the air-fuel mixture supplied to the internal combustion engine 10 is shown.

  As shown in FIG. 7A, when the processes (1) to (3) are terminated at different times in order to terminate the heavy fuel start control, the processes (1) to (3) are performed. The degree to which the air-fuel ratio A / F becomes fuel-lean due to the end of the process is small in each of the processes (1) to (3) alone, so that the situation where the air-fuel ratio A / F becomes fuel-lean significantly does not occur. . Therefore, according to the above method, it is possible to prevent misfire in the internal combustion engine 10 at the end of the heavy fuel start control.

  FIG. 8 shows a flowchart of an example of a control routine executed by the ECU 12 when the heavy fuel start control is terminated in the present embodiment in order to realize the above function. The routine shown in FIG. 8 is a routine that is repeatedly started every time the process is completed. When the routine shown in FIG. 8 is started, first, the process of step 160 is executed.

  In step 160, it is determined whether or not the condition for ending the heavy fuel start control is satisfied, specifically, whether or not the process of step 148 in the routine shown in FIG. 7 is executed. The process of step 160 is repeatedly executed until it is determined that the above condition is satisfied. If it is determined that the condition for ending the heavy fuel start control is satisfied, the process of step 162 is executed next.

  In step 162, it is determined whether or not the amount of change ΔNE per unit time of the engine speed NE is equal to or smaller than a predetermined value ΔNE0. The processing of step 162 is repeatedly executed until it is determined that ΔNE ≦ ΔNE0 is satisfied. When ΔNE ≦ ΔNE0 is satisfied, it can be determined that the operation state of the internal combustion engine 10 is stable after the start of the internal combustion engine 10 is completed. Even if the above processes (1) to (3) of the heavy fuel start control are terminated under such circumstances, the influence resulting from the termination of such processes can be kept small.

  Further, when the processing (1) to (3) of the heavy fuel start control is completed, the air-fuel ratio A / F of the air-fuel mixture supplied to the internal combustion engine 10 becomes fuel lean. The amount of change ΔNE of NE temporarily increases. Therefore, even if the threshold value ΔNE0 for ending the processes (1) to (3) of the heavy fuel start control is set to one, the change amount ΔNE of the engine speed NE is reduced. By counting the number of integrations that are less than or equal to the threshold value ΔNE0, it is possible to end each process of the heavy fuel start control with a time lag.

  In this embodiment, after the heavy fuel start control end condition is satisfied, the number of integrations where the amount of change ΔNE of the engine speed NE is less than or equal to a predetermined value ΔNE0 is counted, and every time the number of integrations is counted. Each process of the heavy fuel start control is ended in order.

  Therefore, if it is determined in step 162 that ΔNE ≦ ΔNE0 is satisfied, the process of step 164 is executed next.

  In step 164, it is determined whether or not the count value of the integration counter CNT is “0”. The integration counter CNT is a counter for counting the number of integrations determined that the condition of step 162 is satisfied after the end condition of the heavy fuel start control is satisfied. When CNT = 0 is satisfied, it can be determined that none of the processes (1) to (3) has been completed after the end condition of the heavy fuel start control is satisfied. Accordingly, when it is determined that CNT = 0 is established, the process of step 166 is then executed to end (1) valve opening timing advance control. On the other hand, if it is determined that CNT = 0 is not established, the process of step 170 is executed next.

  In step 166, a process of incrementing the integration counter CNT is executed. When the process of step 166 is executed, the count value of the integration counter CNT becomes “1” thereafter. When the process of step 166 is completed, the process of step 168 is executed next.

  In step 168, processing for returning the opening / closing timing of the intake valve 52 that has been shifted to the advance side to the normal timing is executed. In this case, the increased valve overlap between the intake valve 52 and the exhaust valve 54 decreases. When the processing of step 168 is completed, the current routine is terminated.

  In step 170, it is determined whether or not the count value of the integration counter CNT is “1”. When CNT = 1 is satisfied, it can be determined that (1) only the valve opening timing advance control is completed after the end condition of the heavy fuel start control is satisfied. Therefore, if such a determination is made, then the process of step 172 is executed to end (2) intake synchronous injection control.

  In step 172, a process of incrementing the integration counter CNT is executed. When the processing of this step 172 is executed, the count value of the integration counter CNT becomes “2” thereafter. When the process of step 172 is completed, the process of step 174 is executed next.

  In step 174, processing for returning the fuel injection performed when the intake valve 52 is opened to the normal timing is executed. When the processing of step 174 is completed, the current routine is terminated.

  On the other hand, if CNT = 1 is not satisfied in step 170, it can be determined that CNT = 2 is satisfied, and after the end condition of the heavy fuel start control is satisfied, (1) valve opening timing advance control, And (2) It can be determined that the intake synchronous injection control has ended. Therefore, if such a determination is made, the process of step 176 is then executed to end the (3) injection amount increase control.

  In step 176, a process for returning the increased fuel injection amount to the normal amount is executed. When the process of step 176 is executed, the processes (1) to (3) are all finished, and the start control of the internal combustion engine 10 is switched from the heavy fuel start control to the normal start control. When the process of step 176 is completed, the process of step 178 is executed next.

  In step 178, processing for resetting the integration counter CNT to “0” is executed. When the processing of step 178 is completed, the current routine is terminated.

  According to the above processing, (1) valve opening of the heavy fuel start control is performed each time the change amount ΔNE of the engine speed NE falls below a predetermined value after the end condition of the heavy fuel start control is satisfied. The timing advance control, (2) intake synchronous injection control, and (3) injection amount increase control can be terminated in that order. Therefore, according to this embodiment, at the end of the heavy fuel start control, (1) valve opening timing advance control, (2) intake synchronous injection control, and (3) injection amount increase control are simultaneously ended. Therefore, the air-fuel ratio A / F of the air-fuel mixture supplied to the internal combustion engine 10 is prevented from becoming extremely lean. Therefore, according to the system of the present embodiment, it is possible to reliably avoid the occurrence of misfire in the internal combustion engine 10 due to the end of the heavy fuel start control.

  By the way, in the second embodiment, the heavy fuel start control (1) to (3) is performed depending on whether or not the amount of change ΔNE per unit time of the engine speed NE is equal to or less than a predetermined value ΔNE0. However, the present invention is not limited to this, and the air-fuel ratio in the exhaust gas is detected, and each heavy fuel start-up control is performed according to the detected air-fuel ratio. The processing may be terminated, or each processing of the heavy fuel start control may be terminated in accordance with the accumulated intake air amount, the accumulated fuel consumption amount, or the torque change amount of the internal combustion engine 10.

  In the second embodiment described above, every time the change amount ΔNE per unit time of the engine speed NE becomes equal to or less than the predetermined value ΔNE0 after the end condition of the heavy fuel start control is satisfied, However, the threshold value for ending each process is not limited to one, and three threshold values are provided, Each process may be terminated step by step.

  Furthermore, in the second embodiment, when the heavy fuel start control ends, the processes (1) to (3) of the heavy fuel start control are ended in that order. The order in which the processes (1) to (3) are ended is not limited to this, and may be ended in another order.

  Next, a third embodiment of the present invention will be described with reference to FIGS. In the internal combustion engine 10 shown in FIGS. 1 and 2, the system of this embodiment is realized by the ECU 12 executing the routine shown in FIG. 10 instead of the routine shown in FIG.

  When it is determined that the fuel property is heavy as in the first and second embodiments, if the injection amount increase control is executed as the heavy fuel start control corresponding to the heavy fuel, the fuel injection amount As the fuel consumption increases, the fuel consumption is remarkably lowered and the exhaust gas emission may be deteriorated. Therefore, in order to avoid such an inconvenience, it is not appropriate to increase the fuel injection amount when it is determined that the fuel property is heavy.

  In the internal combustion engine 10, when the fuel injection is performed so as to ensure an appropriate fuel injection amount corresponding to the intake air amount, when the intake air amount is increased, that is, the opening degree of the throttle valve 66 is increased. When increased, the fuel injection amount increases accordingly. In a situation where light fuel is used in the internal combustion engine 10, even if the opening of the throttle valve 66 is relatively small, that is, even if both the intake air amount and the fuel injection amount are small, the internal combustion engine 10 Start-up is completed promptly. Further, in a situation where the fuel property is heavy, if both the intake air amount and the fuel injection amount are small, it is difficult to complete the start-up of the internal combustion engine 10, while the intake air amount and the fuel injection amount are both large. It becomes easier to complete the start-up.

  Therefore, in the present embodiment, after the start of the internal combustion engine 10 is started, the opening of the throttle valve 66 is increased from the minimum angle at which the internal combustion engine 10 can be started quickly when light fuel is used until the start is completed. As a result, the intake air amount to the internal combustion engine 10 is increased, and the fuel injection amount is appropriately increased in accordance with the intake air amount. According to such a method, the fuel injection amount is increased as the intake air amount increases, so that the internal combustion engine 10 can be reliably maintained while maintaining good exhaust gas emission even when the fuel property is heavy. It is possible to start.

  FIG. 9 shows a time chart for explaining the operation of the throttle valve 66 after the start of the internal combustion engine 10 realized in the present embodiment. In FIG. 9, the throttle opening θ realized under the condition where the fuel property is heavy is indicated by a thick line, and the throttle opening θ realized under the condition where the fuel property is light is indicated by a thin line. In addition, the threshold value for determining the fuel property in the present embodiment is indicated by a broken line.

  In this embodiment, the throttle valve 66 normally opens and closes in conjunction with the accelerator pedal as described above, and after the start of the internal combustion engine 10 is started, the throttle valve 66 is throttled at a predetermined ratio as shown in FIG. 9 until completion. It operates so that the opening degree θ increases. Further, the injector 60 performs an appropriate amount of fuel injection according to the opening of the throttle valve 66. In such a configuration, when the throttle opening θ is relatively small when the start of the internal combustion engine 10 is completed, it can be determined that the fuel property is light. On the other hand, when the throttle opening θ is relatively large at the completion of the start, it can be determined that the fuel property is heavy.

  FIG. 10 shows a flowchart of an example of a control routine executed by the ECU 12 in this embodiment in order to realize the above function. The routine shown in FIG. 10 is a routine that is repeatedly activated every time the process is completed. When the routine shown in FIG. 10 is started, the process of step 200 is first executed.

  In step 200, as in step 100 described above, it is determined whether a condition for starting the internal combustion engine 10 is satisfied. As a result, if it is determined that the condition for starting the internal combustion engine 10 is satisfied, the process of step 202 is then executed.

  In step 202, the opening θ of the throttle valve 66 is obtained by adding a function f (t) that changes according to time t after the start start condition of the internal combustion engine 10 is established in step 200 to the initial value θ0. Processing to set the value is executed. The initial value θ0 is set to the minimum value of the throttle opening θ that is expected to start the internal combustion engine 10 quickly when the fuel property is light, and the function f (t) is the internal combustion engine. 10 is a function that increases as time t after the start start condition is satisfied increases. When the process of step 202 is executed, the opening of the throttle valve 66 increases as time passes, and the amount of air VA taken into the internal combustion engine 10 increases.

  In step 203, the fuel injection amount Q supplied to the internal combustion engine 10 is calculated based on the intake air amount VA and the engine speed NE. In the present embodiment, the fuel injection amount supplied to the internal combustion engine 10 is set to an appropriate value according to the intake air amount. Then, a drive signal is supplied to the injector 60 so that the calculated fuel injection amount Q is ensured. When the process of step 203 is executed, the fuel injection amount increases with the increase of the intake air amount.

  In step 204, it is determined whether or not the generator 22 has started power generation. Specifically, it is determined whether or not the output torque STG of the generator 22 changes from a positive value to a negative value and the state continues for a predetermined time (for example, 0.4 seconds). As a result, when it is determined that the generator 22 has not started power generation, the process of step 202 is executed. On the other hand, when power generation is started in the generator 22, the generator 22 generates power using the internal combustion engine 10 as a power source, so it can be determined that the start of the internal combustion engine 10 has been completed. If such determination is made in step 204, the process of step 206 is executed next.

  In step 206, it is determined whether or not the throttle opening θ is equal to or greater than a threshold value θSH. The threshold value θSH is the minimum value of the throttle opening at which the fuel property is judged to be heavy. As a result, if θ ≧ θSH is not established, it can be determined that the start-up has been completed even under a condition where the intake air amount and the fuel injection amount are relatively small in the internal combustion engine 10, and it can be determined that the fuel property is light. Therefore, if such a determination is made, the process of step 210 is executed next. On the other hand, if θ ≧ θSH is satisfied, it can be determined that a relatively large amount of intake air and fuel injection are required to complete the start of the internal combustion engine 10, and it can be determined that the fuel property is heavy. . Therefore, if such a determination is made, the process of step 208 is executed next.

  In step 208, processing for setting the heavy flag XHD is executed. When the processing of step 208 is completed, the current routine is terminated.

  In step 210, processing for resetting the heavy flag XHD is executed. When the processing of step 210 is finished, the current routine is finished.

  According to the above processing, after the start start condition of the internal combustion engine 10 is satisfied, the throttle opening θ can be increased according to the time required for the start to be completed, and the fuel injection amount Q is set to the intake air amount. An appropriate value can be set based on VA. In this case, the amount of intake air taken into the internal combustion engine 10 increases, and the fuel injection amount increases according to the intake air amount, so that even if the fuel property is heavy, the internal combustion engine 10 It is possible to complete the start-up. Further, in this embodiment, the fuel injection amount is set to an appropriate value according to the intake air amount, so that the exhaust gas emission is always kept good. Therefore, according to the system of the present embodiment, even when the fuel property is heavy, it is possible to reliably start the internal combustion engine 10 while maintaining good exhaust gas emission.

  In the present embodiment, both the intake air amount and the fuel injection amount increase with the passage of time after starting. For this reason, according to the present embodiment, when the fuel property is heavy, as compared with the case where the heavy fuel start control is started after a predetermined time has elapsed after the start of the start as in the first embodiment. Thus, the internal combustion engine 10 can be started quickly. Therefore, according to the system of the present embodiment, it is possible to shorten the time until the start is completed after the start of the internal combustion engine 10 is started.

  Further, in the present embodiment, as described above, the fuel property is determined by comparing the throttle opening when the internal combustion engine 10 is completely started with a predetermined threshold value. That is, when the throttle opening at the completion of the start is smaller than the predetermined threshold, it is determined that the fuel property is light, while the throttle opening at the completion of the start is compared with the predetermined threshold. If it is large, the fuel property is judged to be heavy. However, when it is determined that the fuel property is heavy by the above method, the air-fuel ratio of the air-fuel mixture supplied to the internal combustion engine 10 becomes lean after the start is completed because the throttle opening is large. There is a risk. Therefore, if the ignition timing, the fuel injection amount, etc. are corrected according to the fuel properties determined as described above after the start of the internal combustion engine 10, it is possible to avoid the air-fuel ratio from becoming lean, It is possible to prevent misfire in the engine 10.

  In the above embodiment, after the start of the internal combustion engine 10, the throttle opening θ is linearly increased with time as shown in FIG. It may be increased.

  Next, a fourth embodiment of the present invention will be described with reference to FIGS. The system of the present embodiment is realized by the ECU 12 executing the routine shown in FIG. 12 in the internal combustion engine 10 shown in FIGS.

  In the internal combustion engine 10, after completion of starting, the timing for generating a spark from the spark plug 56 (hereinafter referred to as ignition timing (IT)) is retarded in order to reduce emissions and improve warm-up of the catalyst. Control (hereinafter referred to as ignition retard control) may be performed. When such ignition retardation control is executed, the output torque of the internal combustion engine 10 decreases, and the temperature of the exhaust gas increases, thereby reducing the warming-up emission and raising the temperature of the catalyst.

  When the generator 22 that generates power using the internal combustion engine 10 as a power source is provided in the vehicle, the output torque of the internal combustion engine 10 is reduced when the ignition timing of the spark plug 56 is retarded by the ignition retard control described above. Therefore, the power generation amount of the generator 22 is suppressed to a small value regardless of the fuel property. That is, the power generation amount of the generator 22 decreases as the ignition timing is retarded. Therefore, as in the first embodiment, the fuel property is determined based on the power generation amount of the generator 22 at the completion of the start, and the threshold value used for the fuel property determination is maintained at a predetermined value. In this case, when the ignition retard control is executed, the power generation amount of the generator 22 does not exceed the threshold value and the fuel property is heavy even though the fuel property is actually light. There is a risk that it will be misjudged.

  Therefore, in order to accurately determine the fuel property even when the ignition delay control is executed under the situation where the determination of the fuel property is performed based on the power generation amount of the generator 22 at the completion of the start-up, the fuel property It is not appropriate to maintain the threshold value for determination at a constant value. Therefore, in this embodiment, when the ignition retard control is executed, the threshold value for determining the fuel property is suppressed to a value corresponding to the retard amount of the ignition timing.

  FIG. 11 (A) shows the time change of the advance / retard amount of the ignition timing when the ignition retard control is executed after the start-up of the internal combustion engine 10 is completed. FIG. 11B shows the change over time in the amount of power generated by the generator 22 under the situation where the ignition timing is changed as shown in FIG. In FIG. 11B, the power generation amount of the generator 22 when the fuel property is heavy is indicated by a thick solid line, and the power generation amount of the generator 22 when the fuel property is light is indicated by a thin solid line. In addition, the threshold value for determining the fuel property in the present embodiment is indicated by a broken line.

  As shown in FIG. 11A, after the start start condition of the internal combustion engine 10 is satisfied (t = 0), when the start is completed in the vicinity of t = 3, the emission is reduced and the catalyst is warmed up. Therefore, the ignition retard control is executed. When the ignition retard control is executed, the output torque of the internal combustion engine 10 decreases, and the temperature of the exhaust gas increases, thereby reducing the warming-up emission and increasing the temperature of the catalyst.

  The power generation amount of the generator 22 that generates power using the internal combustion engine 10 as a power source decreases as the output torque of the internal combustion engine 10 decreases. Therefore, the output torque of the internal combustion engine 10 decreases as the ignition timing is retarded by the ignition delay control, and is supplied to the internal combustion engine 10 after t = 5.0 as shown in FIG. 11B. Regardless of the nature of the fuel being used, the amount of power generated by the generator 22 is reduced.

  In this embodiment, as indicated by a broken line in FIG. 11B, after the ignition retard control is started, the delay time that the power generation amount of the generator 22 is expected to fluctuate due to the ignition retard control is estimated. After the elapse of time, the threshold value for determining the fuel property is changed to a value corresponding to the retard amount of the ignition timing.

  FIG. 12 shows a flowchart of an example of a control routine executed by the ECU 12 in this embodiment in order to realize the above function. The routine shown in FIG. 12 is a routine that is repeatedly activated every time the process is completed. When the routine shown in FIG. 12 is started, first, the process of step 220 is executed.

  In step 220, it is determined whether or not the generator 22 has started power generation. Specifically, it is determined whether or not the output torque STG of the generator 22 changes from a positive value to a negative value and the state continues for a predetermined time (for example, 0.4 seconds). The process of step 220 is repeatedly executed until it is determined that the generator 22 has generated power. As a result, when power generation is started in the generator 22, it can be determined that the start of the internal combustion engine 10 is completed. If such a determination is made in step 220, then the process of step 222 is executed.

  In step 222, based on the output signals of the various sensors of the internal combustion engine 10, it is determined whether or not an execution condition for ignition retard control is satisfied. As a result, if it is determined that the execution condition is satisfied, the process of step 224 is executed next.

  In step 224, ignition retard control is performed to retard the ignition timing so that sparks from the spark plug occur on the retard side of the internal combustion engine 10.

  In step 226, it is determined whether or not the time t after the ignition retard control is performed exceeds a predetermined time t10. Note that the power generation amount of the generator 22 actually decreases due to the retard of the ignition timing after the ignition timing starts to be retarded by the ignition retard control, during the predetermined time t10, that is, the output of the generator 22 This is the minimum time during which it can be determined that the torque STG increases. The processing in step 226 is repeatedly executed until it is determined that t ≧ t10 is satisfied. As a result, when it is determined that t ≧ t10 is established, it can be determined that the power generation amount (output torque STG) of the generator 22 is changed due to the ignition retard control. In this case, next, step 228 is performed. The process is executed.

  In step 228, the threshold value A for the output torque STG of the generator 22 for determining the fuel property is set to a value obtained by adding a value f (IT) corresponding to the retard amount of the ignition timing IT to the initial value A0. Is executed. The initial value A0 is a threshold value for determining the fuel property when the ignition retard control is not executed, and the function f (IT) increases as the retard amount of the ignition timing IT increases. It is such a function. When the processing of step 228 is executed, the threshold value for determining the fuel property is changed from the initial value. When the process of step 228 is completed, the process of step 232 is executed next.

  On the other hand, if the execution condition of the ignition retard control is not satisfied after the start of the internal combustion engine 10 in step 222, it can be determined that it is not necessary to execute such control. In this case, it is not necessary to change the threshold value for determining the fuel property. Therefore, if it is determined in step 222 that the ignition delay control execution condition is not satisfied, the process of step 230 is executed next.

  In step 230, a process for setting the threshold value A for determining the fuel property to the initial value A0 is executed. When the process of step 230 is completed, the process of step 232 is executed next.

  In step 232, it is determined whether or not the current time is the fuel property determination time. Specifically, it is determined whether or not a certain time has elapsed after the start of the internal combustion engine 10 is completed. The process of step 232 is repeatedly executed until it is determined that the above condition is satisfied. As a result, if it is determined that the fuel property determination time has been reached, the process of step 234 is then performed.

  In step 234, the output torque STG of the generator 22 is detected based on the output signals of the current detection circuit and the voltage detection circuit built in the inverter 26.

  In step 236, it is determined whether or not the output torque STG of the generator 22 detected in step 234 is smaller than the threshold value A set in step 228 or 230. As a result, if it is determined that STG <A is not established, the process of step 238 is executed next. On the other hand, if it is determined that STG <A is established, the process of step 240 is executed next. .

  In step 238, processing for setting the heavy flag XHD is executed. When the processing of step 238 is completed, the current routine is terminated.

  In step 240, processing for resetting the heavy flag XHD is executed. When the processing of step 240 is finished, the current routine is finished.

  According to the above processing, when the ignition retard control is not executed after the start of the internal combustion engine 10, the threshold for determining the fuel property is maintained at a constant value, while the ignition retard is controlled. When the control is executed, the threshold value can be changed to a value corresponding to the retard amount of the ignition timing. For this reason, according to the present embodiment, even when the power generation amount of the generator 22 after starting is changed due to the ignition timing being retarded by the ignition retardation control, it is supplied to the internal combustion engine 10. The property of the fuel can be accurately determined based on the power generation amount of the generator 22. Therefore, according to the present embodiment, it is possible to execute an appropriate correction even when a correction is made to the fuel injection amount, the ignition timing, or the like according to the fuel property after the determination of the fuel property.

  In general, the internal combustion engine 10 is in an unstable operating state immediately after the start is completed. For this reason, in the configuration in which the fuel property is determined based on the power generation amount of the generator 22 that generates power using the internal combustion engine 10 as a power source, it is not appropriate to determine the fuel property immediately after the start of the internal combustion engine 10 is completed. When the ignition delay control is executed, as described above, after the delay time has elapsed after the start of the control, the power generation amount of the generator 22 varies due to the ignition timing being retarded. For this reason, in the configuration in which the fuel property is determined based on the power generation amount of the generator 22 after the start of the start and the threshold value for determining the fuel property is maintained at a constant value, the ignition retard control is started. It is not appropriate to determine the fuel property after the post-delay time has elapsed. Therefore, in such a configuration, the time during which the fuel property can be accurately determined becomes a short period.

  On the other hand, in the present embodiment, after a certain time has elapsed after the start of the ignition retard control, the threshold value for determining the fuel property is changed in accordance with the retard amount of the ignition timing. It is said. In this case, even if the power generation amount of the generator 22 after starting is changed due to the ignition timing being retarded by the ignition retardation control, the fuel property can be accurately determined. Therefore, according to the present embodiment, the fuel property can be accurately determined for a long time after the start of the internal combustion engine 10 is completed, and it is possible to improve the accuracy when determining the fuel property.

  In the fourth embodiment, the output torque STG of the generator 22 is set to “Parameter” described in the claims, and the ignition delay control is set to “Torque limit control” described in the claims. , And the ECU 12 executes the processing of step 228 to realize the “threshold value changing means” described in the claims.

  By the way, in said 4th Example, by changing the threshold value used in order to determine a fuel property, when ignition timing retardation control is performed in order to aim at the improvement of warming-up of a catalyst, Although it is intended to prevent misjudgment of fuel properties, the method of preventing misjudgment of fuel properties is not limited to this, and prohibition of fuel property judgment is prohibited when ignition timing retardation control is executed It is good also as realizing by doing. In this case, the ECU 12 prohibits the determination of the fuel property when the torque limit control is being executed, thereby realizing the “property determination prohibiting unit” recited in the claims.

  In the fourth embodiment, the threshold value for determining the fuel property is changed when the ignition retard control is executed in which the output torque of the internal combustion engine 10 is limited to be small. As long as the output torque of the internal combustion engine 10 is controlled to be small, the threshold value may be changed by a control other than the ignition retard control.

  In the first to fourth embodiments, it is determined whether or not the start of the internal combustion engine 10 is completed based on whether or not the power generation of the generator 22 is started. It may be determined whether or not the start is completed based on the output of the internal combustion engine 10.

1 is a diagram schematically showing a drive mechanism of a vehicle on which an internal combustion engine that is a first embodiment of the present invention is mounted. FIG. It is a block diagram of the internal combustion engine used in a present Example. It is the figure which represented typically the detection method which detects the property of the fuel supplied to an internal combustion engine. In this embodiment, it is a flowchart of an example of a control routine executed to start the internal combustion engine. 5 is a flowchart of an example of a control routine that is executed to switch from start control of the internal combustion engine to air-fuel ratio feedback control in the present embodiment. (A) shows the intake valve advance angle evt, fuel injection end timing angle einjend, and fuel injection amount increase rate efmwst when all the processes performed at the end of the heavy fuel start control are ended simultaneously. FIG. 5B is a diagram showing an example of time changes, and FIG. 5B is an internal combustion engine air-fuel ratio obtained when the advance angle evt, end timing angle einjend, and increase rate efmwst are changed as shown in FIG. It is a figure which shows the time change of A / F. (A) is an increase in the intake valve advance angle evt, fuel injection end timing angle einjend, and fuel injection amount when the processes performed at the end of the heavy fuel start control are ended at different times. FIG. 5B is a diagram showing an example of a time change of the rate efmwst, and FIG. 6B is an internal combustion engine obtained when the advance angle evt, the end timing angle einjend, and the increase rate efmwst are changed as shown in FIG. It is a figure which shows the time change of the air fuel ratio A / F. In 2nd Example of this invention, it is a flowchart of an example of the control routine performed when complete | finishing the 2nd start-up control corresponding to heavy fuel. It is a figure which shows the time change of the throttle opening after the start of an internal combustion engine implement | achieved in 3rd Example of this invention. 4 is a flowchart of an example of a control routine that is executed to determine fuel properties in the present embodiment. (A) is a figure which shows the time change of the advance / retard amount of the ignition timing when the ignition delay control is executed after the start is completed in the internal combustion engine, and (B) is as shown in (A). It is a figure which shows the time change of the electric power generation amount of a generator in the condition which changes ignition timing. In the fourth embodiment of the present invention, it is a flowchart of an example of a control routine executed to determine the fuel properties.

Explanation of symbols

10 Internal combustion engine 12 Electronic control unit (ECU)
22 Generator 60 Injector 66 Throttle valve

Claims (2)

In the internal combustion engine fuel property determination device in which the torque limit control in which the output torque is limited can be executed after the start of the internal combustion engine is completed.
The fuel property of the internal combustion engine is determined based on a parameter corresponding to the output torque after completion of starting,
A fuel property characterized by comprising a threshold value changing means for changing a threshold value for determining the fuel property when the torque limit control is executed as compared with a case where the torque limit control is not executed. Judgment device . In the internal combustion engine fuel property determination device in which the torque limit control in which the output torque is limited can be executed after the start of the internal combustion engine is completed.
The fuel property of the internal combustion engine is determined based on a parameter corresponding to the output torque after completion of starting,
A fuel property determination apparatus comprising: a property determination prohibiting unit that prohibits determination of fuel property when the torque limit control is being executed .