JP5677505B2 - Power generation control device and power generation control method - Google Patents

Description

  The present invention relates to a power generation control device and a power generation control method, and more particularly to a power generation control device and a power generation control method for a hybrid vehicle that control an operating point of the internal combustion engine in a vehicle using an internal combustion engine and a generator as power sources.

  2. Description of the Related Art Conventionally, an internal combustion engine for power generation mounted on a hybrid vehicle has been proposed in which an exhaust gas sensor for detecting the oxygen concentration in exhaust gas is installed in an exhaust pipe of the internal combustion engine (see, for example, Patent Document 1). ).

  The exhaust gas sensor failure diagnosis generally uses a method of monitoring the absolute value or responsiveness of the output voltage of the exhaust gas sensor by forcibly changing the oxygen concentration of the gas in the exhaust pipe in which the exhaust gas sensor is disposed. . Because it is necessary to continue the fuel cut state of the internal combustion engine and continue to scavenge the gas in the exhaust pipe from the time when the oxygen concentration of the gas in the exhaust pipe is forcibly changed until the output change of the exhaust gas sensor is sufficiently stable In a hybrid vehicle in which the internal combustion engine is intermittently operated according to the amount of power generation required during traveling, so-called motoring is performed in which the internal combustion engine is forcibly driven from the generator.

Japanese Patent No. 4325700

  As described above, in a hybrid vehicle that intermittently operates an internal combustion engine according to the amount of electric power required during traveling, the internal combustion engine is forcibly driven using a generator in order to diagnose a failure of the exhaust gas sensor. Motoring is being performed. For this reason, there has been a problem that electric energy is consumed in order to perform failure diagnosis of the exhaust gas sensor.

  The present invention has been made to solve such a problem, and provides a power generation control apparatus and a power generation control method capable of suppressing the consumption of electrical energy for performing failure diagnosis of an exhaust gas sensor of an internal combustion engine. It is intended to provide.

The present invention is a power generation control device that is mounted and used in a vehicle including a generator and an internal combustion engine that drives the generator, and includes a power consumption amount of a vehicle driving motor that drives the vehicle, calculates a target power generation amount based on the charging electric energy to the battery for storing electric power, using a function of the target power generation amount, the calculation of the power generation request output to the internal combustion engine showing a power generation amount to be power A target power generation amount calculation unit to be performed, and an exhaust gas sensor that is disposed in an exhaust passage of the internal combustion engine and that performs failure diagnosis of an exhaust gas sensor that detects an air-fuel ratio of exhaust gas discharged from the internal combustion engine or an oxygen concentration in the exhaust gas Exhaust gas diagnosis permission for determining whether or not the exhaust gas sensor diagnosis execution unit is allowed to execute a failure diagnosis of the exhaust gas sensor according to a state of the diagnosis execution unit and the exhaust gas sensor And the exhaust gas sensor diagnosis permission unit do not permit execution of failure diagnosis of the exhaust gas sensor, the target rotational speed of the internal combustion engine is set to a first target rotational speed based on the power generation request output. A target rotational speed changing unit that sets a target rotational speed of the internal combustion engine to a second target rotational speed for failure diagnosis when the exhaust gas sensor diagnostic permitting part permits execution of failure diagnosis of the exhaust gas sensor; It is a power generation control apparatus provided with.

The present invention is a power generation control device that is mounted and used in a vehicle including a generator and an internal combustion engine that drives the generator, and includes a power consumption amount of a vehicle driving motor that drives the vehicle, calculates a target power generation amount based on the charging electric energy to the battery for storing electric power, using a function of the target power generation amount, the calculation of the power generation request output to the internal combustion engine showing a power generation amount to be power A target power generation amount calculation unit to be performed, and an exhaust gas sensor that is disposed in an exhaust passage of the internal combustion engine and that performs failure diagnosis of an exhaust gas sensor that detects an air-fuel ratio of exhaust gas discharged from the internal combustion engine or an oxygen concentration in the exhaust gas Exhaust gas diagnosis permission for determining whether or not the exhaust gas sensor diagnosis execution unit is allowed to execute a failure diagnosis of the exhaust gas sensor according to a state of the diagnosis execution unit and the exhaust gas sensor And the exhaust gas sensor diagnosis permission unit do not permit execution of failure diagnosis of the exhaust gas sensor, the target rotational speed of the internal combustion engine is set to a first target rotational speed based on the power generation request output. A target rotational speed changing unit that sets a target rotational speed of the internal combustion engine to a second target rotational speed for failure diagnosis when the exhaust gas sensor diagnostic permitting part permits execution of failure diagnosis of the exhaust gas sensor; Therefore, when the diagnosis of the exhaust gas sensor is permitted, the target rotational speed of the internal combustion engine is changed from the target rotational speed for the normal power generation control request to the target rotational speed for exhaust gas sensor diagnosis. Since the exhaust gas sensor is diagnosed during subsequent fuel supply stops, motoring by a generator is not required. It is possible to suppress the electric energy consumption for carrying out the diagnosis.

It is a figure which shows schematic structure of the hybrid vehicle concerning Embodiment 1-4 of this invention. It is the figure which showed the structure of the internal combustion engine and power generation control apparatus concerning Embodiment 1-4 of this invention. It is a conceptual block diagram of the electric power generation control apparatus concerning Embodiment 1-4 of this invention. It is the figure which showed the operating point at the time of electric power generation control in the internal combustion engine concerning Embodiment 1 of this invention. 4 is a timing chart showing the rotational speed of the internal combustion engine when traveling at a constant speed in the vicinity of the target charged amount in the hybrid vehicle according to the first embodiment of the present invention. It is explanatory drawing which shows the relationship between the air fuel ratio and sensor output voltage of the air fuel ratio sensor concerning Embodiment 1 of this invention. It is explanatory drawing which shows the relationship between the excess air ratio and sensor output voltage of the oxygen sensor concerning Embodiment 1 of this invention. It is a flowchart which shows the process of the electric power generation control part of the electric power generation control apparatus concerning Embodiment 1 of this invention. It is a flowchart which shows the process of the internal combustion engine control part of the electric power generation control apparatus concerning Embodiment 1-4 of this invention. It is a flowchart which shows the process of the exhaust gas sensor diagnosis permission determination in the exhaust gas sensor diagnostic part of the electric power generation control apparatus concerning Embodiment 1-4 of this invention. It is a flowchart which shows the process of the output control of the electric power generation control apparatus concerning Embodiment 1 of this invention. It is a flowchart which shows the process of the diagnosis of the air fuel ratio sensor concerning Embodiment 1-4 of this invention. It is a flowchart which shows the process of the diagnosis of the oxygen sensor concerning Embodiment 1-4 of this invention. 3 is a timing chart showing the behavior of the rotational speed of the internal combustion engine at the time of diagnosis of the exhaust gas sensor according to Embodiment 1 of the present invention. It is a flowchart which shows the process of the output control concerning Embodiment 2 of this invention. It is a timing chart which shows the behavior of the rotational speed of the internal combustion engine at the time of exhaust gas sensor diagnosis concerning Embodiment 2 of this invention. It is a flowchart which shows the process of the output control concerning Embodiment 3 of this invention. It is a timing chart which shows the behavior of the rotational speed of the internal combustion engine at the time of the exhaust gas sensor diagnosis concerning Embodiment 3 of this invention. It is a flowchart which shows the process of the output control concerning Embodiment 4 of this invention. It is a timing chart which shows the behavior of the rotational speed of the internal combustion engine at the time of the exhaust gas sensor diagnosis concerning Embodiment 4 of this invention.

  Hereinafter, embodiments of a power generation control device and a power generation control method according to the present invention will be described with reference to the drawings. In those embodiments described below, a hybrid electric vehicle having a generator as a power source for driving the vehicle and an internal combustion engine for driving the vehicle is used as a vehicle using the power generation control device and the power generation control method of the present invention. An example will be described. The power generation control device of the present invention controls the generator and the internal combustion engine, and stores the power obtained by the power generation by the power generator or the regenerative power generation of the vehicle drive motor in the battery, and the power from the battery or the power generator. The target power generation amount of the generator is calculated based on the power consumption amount of the vehicle driving motor that drives the vehicle and the amount of electricity stored in the battery, and the generator and the internal combustion engine are controlled based on the target power generation amount It is. Since the vehicle can travel only with electric power from the battery under the control of the power generation control device, the internal combustion engine can be stopped while the vehicle is traveling. In addition, the power generation control device performs failure diagnosis of the exhaust gas sensor and performs control for suppressing consumption of electrical energy for performing the failure diagnosis.

Embodiment 1 FIG.
FIG. 1 is a schematic configuration diagram illustrating an example of a hybrid vehicle on which the power generation control device 9 according to Embodiment 1 of the present invention is mounted. As shown in FIG. 1, the hybrid vehicle includes an internal combustion engine 1 that obtains dynamic energy by burning fuel such as gasoline, and obtains dynamic energy from the internal combustion engine 1 and converts it into electrical energy. A generator 2 that generates power, a battery 3 that stores electric power obtained by power generation by the generator 2 or regenerative power generation of the vehicle drive motor 6, an accelerator pedal 4 that the driver steps on, and a vehicle drive motor 6 Electric power is supplied between the motor control device 5 to be controlled, the vehicle driving motor 6 that drives the vehicle by obtaining electric power from the battery 3 or the generator 2, and the generator 2, the vehicle driving motor 6, and the battery 3. A power converter 7 that converts direct current to alternating current or alternating current to direct current, and a vehicle that obtains electric power from a battery or a generator and transmits the driving force from the vehicle driving motor 6 to the road surface. A drive wheel 8 for running are provided.

  The accelerator pedal 4 receives a request for a traveling state of the vehicle from the driver. That is, the driver's acceleration request can be detected from the depression amount of the driver's accelerator pedal 4.

  The motor control device 5 controls the power supplied to the vehicle driving motor 6 or drives the vehicle based on the acceleration request signal from the accelerator pedal 4, the state of the vehicle, and / or the state of the vehicle driving motor 6. The generated power in the motor 6 is controlled.

  The vehicle driving motor 6 not only generates driving force for running the vehicle based on the electric power from the generator 2 or the battery 3, but can also perform regenerative power generation based on the kinetic energy of the running vehicle. .

  The power generation control device 9 monitors the states of the accelerator pedal 4, the battery 3, the vehicle drive motor 6, the power converter 7, and the like, and controls the internal combustion engine 1 and the generator 2.

  FIG. 2 is a diagram showing the configuration of the internal combustion engine 1 and the power generation control device 9. In FIG. 2, the internal combustion engine 1 includes a catalytic converter 12 that purifies the exhaust gas of the internal combustion engine 1, an air-fuel ratio sensor 13 that detects an air-fuel ratio of the exhaust gas discharged from the internal combustion engine 1, and a downstream of the catalytic converter 12. An oxygen sensor 14 indicating the oxygen concentration of the exhaust gas, a crank angle sensor 15 for detecting the angular position and rotational speed of the crankshaft of the internal combustion engine 1, and an airflow sensor 16 for measuring the amount of air taken in by the internal combustion engine 1. And an injector 17 that supplies fuel into the cylinder of the internal combustion engine 1, an ignition plug 18 that ignites a spark inside the cylinder of the internal combustion engine 1, and a valve mechanism, and the air that the internal combustion engine 1 sucks according to the opening degree thereof And a throttle 19 for adjusting the amount of. The power generation control device 9 detects the operating state of the internal combustion engine 1 from the crank angle sensor 15, the air flow sensor 16, and the like, and controls the amount of fuel injected from the injector 17 and the ignition timing of the spark plug 18. The failure diagnosis of the air-fuel ratio sensor 13 and the oxygen sensor 14 is performed.

  In the present embodiment, the air-fuel ratio sensor 13 and / or the oxygen sensor 14 are disposed in the exhaust passage of the internal combustion engine 1, and the air-fuel ratio of the exhaust gas discharged from the internal combustion engine 1 or the oxygen in the exhaust gas An exhaust gas sensor for detecting the concentration is configured. Hereinafter, the exhaust gas sensors (13, 14) are collectively referred to.

  Next, the configuration of the power generation control device 9 will be described. FIG. 3 is a conceptual configuration diagram of the power generation control device 9. In FIG. 3, reference numeral 10 denotes a group of various sensors provided in the internal combustion engine 1 such as the air flow sensor 16, the crank angle sensor 15, the air-fuel ratio sensor 13, and the oxygen sensor 14 shown in FIG. .

  As shown in FIG. 3, the power generation control device 9 includes a generator control unit 90 and an internal combustion engine control unit 91.

  The generator control unit 90 is based on the input unit 21 to which the power consumption amount of the vehicle driving motor 6 and the power storage amount of the battery 3 are input, and the target power consumption based on the power consumption of the vehicle driving motor 6 and the power storage amount of the battery 3. A target power generation amount calculation unit 22 that calculates a power generation amount and outputs a power generation request output indicating a value of the power generation amount to be generated by the internal combustion engine 1 to the internal combustion engine control unit 91, and corresponds to the target power generation amount A target generator load calculation unit 23 that calculates a target generator load and gives it to the generator 2 is provided.

On the other hand, the internal combustion engine control unit 91 includes a fuel injection control unit 24, an ignition timing control unit 25, an exhaust gas sensor diagnosis unit 26, and an output control unit 27.
The fuel injection control unit 24 calculates an appropriate fuel injection amount for the amount of air taken into the internal combustion engine 1 and controls the fuel injection of the injector 17.
The ignition timing control unit 25 controls the ignition of the ignition plug 18 by calculating the ignition timing by the ignition plug 18 so that the fuel injected from the injector 17 to the internal combustion engine 1 is ignited at an appropriate timing. To do.
The exhaust gas sensor diagnosis unit 26 determines whether or not to permit failure diagnosis of the exhaust gas sensor (13 and 14) based on the state of the exhaust gas sensor (13 and 14) and determines to permit execution of failure diagnosis. In this case, a diagnosis permission signal is output to the output control unit 27 and a failure diagnosis of the exhaust gas sensors (13, 14) is executed.
The output control unit 27 includes a target rotation speed changing unit, sets the target rotation speed of the internal combustion engine 1 and adjusts the throttle opening of the internal combustion engine 1. The output control unit 27 also controls the start / stop of operation of the internal combustion engine 1. When the exhaust gas sensor diagnosis unit 26 does not permit execution of failure diagnosis of the exhaust gas sensor (13, 14), the target rotation speed change unit sets the target rotation speed of the internal combustion engine 1 based on the first power generation request output. When the target rotational speed is set and the exhaust gas sensor diagnosis unit 26 permits execution of failure diagnosis of the exhaust gas sensors (13, 14), the target rotational speed of the internal combustion engine 1 is set as the second target rotational speed for failure diagnosis. Set to.

  The target power generation amount in the hybrid vehicle is set so that the power consumption amount of the vehicle drive motor 6 determined mainly by the accelerator depression amount by the driver's operation of the accelerator pedal 4 and the power storage amount of the battery 3 are the target power storage amount. It is determined by the sum of required charging power. Note that the target power storage amount of the battery 3 is a value determined in advance so as not to hinder the driving of the vehicle with respect to the power consumption amount of the vehicle driving motor 6 that changes momentarily according to the driving state. For example, when a large acceleration request is generated from the driver, the target of the battery 3 is set so that the power supplied to the vehicle drive motor 6 is not short during the response delay until the output of the internal combustion engine 1 reaches the required value. The amount of power storage is set with a sufficient margin.

  Next, a method for setting the target rotational speed of the internal combustion engine 1 for the power generation request output of the generator control unit 90 will be described. In a hybrid vehicle with high fuel efficiency, in order to obtain a target power generation amount from the generator 2, the internal combustion engine 1 is operated only at an operating point with high fuel efficiency. Specifically, a line with good fuel efficiency of the internal combustion engine 1 among the operating points of the internal combustion engine 1 determined by the rotation speed and the charging efficiency corresponding to the power generation request output from the generator control unit 90 (the best fuel efficiency described later). Select and drive to trace the curve.

  FIG. 4 shows the operating point of the internal combustion engine 1 determined by the rotational speed and the charging efficiency with respect to the power generation request output from the generator control unit 90. In FIG. 4, the horizontal axis represents the rotational speed of the internal combustion engine 1, and the vertical axis represents the charging efficiency. As indicated by the equal fuel efficiency line in FIG. 4, the operating point characteristic of the internal combustion engine 1 is a concentric substantially elliptical characteristic determined by a predetermined charging efficiency and a predetermined rotational speed. A curve AB-Emin passing through the points A, B, and Emin in the figure represents the best fuel consumption curve, and the best fuel efficiency at an arbitrary rotational speed is connected. If the internal combustion engine 1 is controlled so as to operate on this fuel efficiency best curve, the fuel consumption can be reduced. For example, when the target power generation amount of the generator 2 changes in a decreasing direction from AkW (point A) to BkW (point B), the operating point of the internal combustion engine 1 represents the best fuel consumption curve indicated by curve AB-Emin. Thus, the point A changes from a point A having high rotation and high filling efficiency to a point B having low rotation and low filling efficiency. The internal combustion engine 1 generally becomes unstable when the rotational speed is low, and a loss of output torque at the time of intake of air, called pumping loss, occurs on the light load side. The operating point with low charging efficiency is not used for power generation. Therefore, when the power generation request output to the internal combustion engine 1 corresponding to the target power generation amount is less than the Emin point in FIG. 4, the generator control unit 90 sets the output request to the internal combustion engine control unit 91 to 0 kW. For example, when the amount of power stored in the battery 3 (hereinafter referred to as SOC) is sufficiently larger than the target amount of stored power and the required power amount of the vehicle drive motor 6 is small or 0 kW (for example, when the vehicle is stopped), generator control is performed. When the target power generation amount calculated by the unit 90 is small and the power generation request output to the internal combustion engine 1 corresponding to the target power generation amount is less than Emin, the power generation request output to the internal combustion engine control unit 91 is 0 kW. . The internal combustion engine control unit 91 stops the internal combustion engine 1 when the power generation request output becomes 0 kW.

  The relationship between the target power generation amount and the operating state of the internal combustion engine 1 will be described using the timing chart of FIG. In FIG. 5, the horizontal axis represents time, and the vertical axis represents SOC [%], electric energy (charging electric energy [kW] to the battery 3 and electric power consumption [kW] of the vehicle driving motor 6) in order from the top. The target power generation amount [kW], the power generation request output [kW] to the internal combustion engine 1, and the rotational speed [r / min] of the internal combustion engine 1. Further, in the SOC chart in the figure, Ts1 is a target charged amount for determining whether or not the battery 3 is fully charged, and the battery 3 is charged when the SOC of the battery 3 becomes equal to or higher than the target charged amount Ts1. Is determined to be complete. In the SOC chart in the figure, Ts2 is a target storage amount for determining whether or not a request for charging the battery 3 is necessary, and when the SOC of the battery 3 becomes equal to or less than the target storage amount Ts2. It is determined that the battery 3 needs to be charged. Note that the target charged amount Ts1 for determining whether or not the battery 3 is fully charged is set to a larger value than the target charged amount Ts2 for determining whether or not a request for charging the battery 3 is required. Therefore, when the SOC of the battery 3 becomes equal to or less than the target power storage amount Ts2, charging to the battery 3 is started. However, the amount of charging power to the battery 3 is not constant, and when the SOC increases due to charging, Along with the increase, the charging power amount to the battery 3 is gradually decreased at a constant ratio, and when the SOC of the battery 3 becomes equal to or higher than the target storage amount Ts1, the charging to the battery 3 is completely terminated. As shown in FIG. 5, the target power generation amount to be achieved by the internal combustion engine 1 is represented by the sum of the amount of power charged to the battery 3 and the power consumption amount of the vehicle drive motor 6. The value of the power generation request output to the internal combustion engine 1 is determined based on the target power generation amount. If the value of the power generation request output to the internal combustion engine 1 corresponding to the target power generation amount falls below Emin, the generator control unit 90 Sets the value of the power generation request output to the internal combustion engine 1 to 0 kW.

  As shown in the example of FIG. 5, for example, when the vehicle travels at a constant speed from a state where the SOC of the battery 3 is slightly higher than the target charged amount Ts1, the vehicle 3 travels using only the power from the battery 3 at first. (Period indicated by BT), the SOC of the battery 3 gradually decreases to Ts2 or less. Then, charging of the battery 3 is started, and since the power generation request output to the internal combustion engine corresponding to the target power generation amount exceeds Emin, the internal combustion engine 1 is started to drive the generator 2 (time: T1), While the battery 3 is being charged, the vehicle is driven by supplying power to the vehicle driving motor 6 (period indicated by EN). Thus, when the SOC of the battery 3 reaches Ts1, the request for charging disappears, the target power generation amount decreases, and the power generation request output to the internal combustion engine 1 falls below Emin. Is set to 0 kW, and the internal combustion engine 1 is stopped (time: T2). Thereafter, the vehicle driving motor 6 travels using only the electric power stored in the battery 3 for a while. If this state continues, the SOC of the battery 3 gradually decreases to Ts2 or less. If it does so, in order to drive the generator 2, the internal combustion engine 1 will be started and a driving | operation will be started (time: T3). Accordingly, when the vehicle 3 travels in the vicinity of Ts1, which is the target charge amount of the battery 3, the internal combustion engine 1 operates intermittently.

  Next, a method for diagnosing the exhaust gas sensors (13, 14) attached to the exhaust pipe of the internal combustion engine 1 will be described. The output characteristics of the exhaust gas sensors (13, 14) are shown in FIGS. FIG. 6 shows the characteristics of the air-fuel ratio sensor 13 that measures the air-fuel ratio in the exhaust gas, among the exhaust gas sensors (13, 14), and the excess air ratio in the exhaust gas is near 1.0 (that is, near the theoretical air-fuel ratio). 7), the characteristics of the oxygen sensor 14 in which the output voltage changes sharply are shown in FIG. In FIG. 6, the horizontal axis represents the air-fuel ratio, and the vertical axis represents the sensor output. In FIG. 7, the horizontal axis represents the excess air ratio, and the vertical axis represents the sensor output.

  The air-fuel ratio sensor 13 is diagnosed by introducing the atmosphere into the space around the air-fuel ratio sensor 13 to cause the air-fuel ratio sensor 13 to measure high concentration oxygen, and when the output is not within a predetermined range, It is determined that the fuel ratio sensor 13 is malfunctioning. Specifically, when air is introduced into the space around the air-fuel ratio sensor 13 and the output of the air-fuel ratio sensor 13 deviates greatly from a predetermined threshold value Vout_a1 (see FIG. 6), it is determined that a failure has occurred.

  The diagnosis of the oxygen sensor 14 is performed by causing the oxygen sensor 14 to measure exhaust gas having an excess air ratio of 1.0 or less while the internal combustion engine 1 is operating, and then suddenly changing the gas measured by the oxygen sensor 14. By replacing the exhaust gas with the atmosphere, the output of the oxygen sensor 14 is changed from the high voltage side to the low voltage side, and a failure diagnosis is performed based on the time required for the change in the output of the oxygen sensor 14. Specifically, if the output voltage of the oxygen sensor 14 corresponding to the excess air ratio = 1.0 is a predetermined value Vout_S, the oxygen sensor 14 is caused to measure exhaust gas having an excess air ratio of 1.0 or less. The output voltage of the oxygen sensor 14 is set to a state equal to or higher than Vout_S, and then the atmosphere is rapidly introduced into the space around the oxygen sensor 14. After the introduction of the atmosphere, the elapsed time is measured, and the output voltage of the oxygen sensor 14 after a predetermined time has elapsed is detected. If the oxygen sensor 14 is normal, the output voltage should converge to Vout_a2 (here, Vout_a2 <Vout_S) when a predetermined time has elapsed after introduction into the atmosphere. Therefore, when the output voltage of the oxygen sensor 14 is not lower than a predetermined threshold value Vout_L2 (here, Vout_a2 <Vout_L2 <Vout_S) greater than Vout_a2, it is determined that the response of the oxygen sensor 14 is abnormally slow, It is determined that the sensor 14 has failed. Here, the threshold value Vout_L2 is set to, for example, the value of the output voltage of the normal oxygen sensor 14 near the lean excess air ratio = 1.0.

  Thus, in any of the failure diagnosis methods of the air-fuel ratio sensor 13 and the oxygen sensor 14, it is necessary to introduce a gas having a high oxygen concentration, that is, the atmosphere, into the space where the sensor measures the gas. In order to introduce the atmosphere to the measurement position of the exhaust gas sensors (13, 14), the supply of fuel to the internal combustion engine 1 is stopped and the crankshaft of the internal combustion engine 1 is rotated, whereby the air that the internal combustion engine 1 takes in Is sent through the combustion chamber of the internal combustion engine 1 to the exhaust pipe in which the exhaust gas sensors (13, 14) are arranged. Here, in order to ensure the reliability of the diagnosis of the exhaust gas sensors (13, 14), the arrangement of the exhaust gas sensors (13, 14) exhausted during operation of the internal combustion engine 1 by introducing a large amount of air. Scavenging the exhaust gas having a low oxygen concentration at the position. A method of introducing a large amount of air is to increase the number of rotations of the crankshaft while the fuel supply is stopped. As an example of this method, a generator mounted on a hybrid vehicle is used as a motor. A method of rotating a crankshaft of an internal combustion engine with the motor is known (for example, see Patent Document 1). However, this method requires large electrical energy to rotate the motor.

  Further, in a general vehicle that travels by transmitting the output of the internal combustion engine to the transmission and drive wheels, the kinetic energy of the traveling vehicle is transmitted via the transmission and drive wheels even when the supply of fuel to the internal combustion engine is stopped. In this state, the exhaust gas sensor can be diagnosed because the crankshaft of the internal combustion engine can be rotated.

  On the other hand, a series hybrid vehicle in which the internal combustion engine 1 is connected only to a generator cannot convert the kinetic energy of the running vehicle into a force that rotates the crankshaft of the internal combustion engine. In the series hybrid vehicle, in the process of stopping the operation of the internal combustion engine for power generation, the rotation speed is gradually reduced, and finally the fuel supply is stopped from the low rotation speed. Even if the exhaust gas sensor is diagnosed at this fuel stoppage, the rotation is stopped before a sufficient number of rotations of the crankshaft is obtained, so the reliability of the diagnosis result of the exhaust gas sensor cannot be ensured.

  Therefore, in the present embodiment, when the exhaust gas sensor diagnosis unit 26 permits the diagnosis of the exhaust gas sensors (13, 14), the target rotation speed of the internal combustion engine 1 is set to the rotation speed used for normal power generation control. The generator connected to the internal combustion engine 1 and the internal combustion engine 1 is changed to a higher rotational speed and the fuel supply to the internal combustion engine 1 is stopped when the internal combustion engine 1 maintains the high rotational speed. The exhaust gas sensor (13, 14) is diagnosed during this period while securing a large number of rotations of the crankshaft until the internal combustion engine 1 stops using the inertial force of No. 2.

  The above control content will be specifically described with reference to a flowchart.

  FIG. 8 is a flowchart showing processing of the generator control unit 90. First, in step S801, it is determined whether or not the SOC of the battery 3 is less than Ts2. If SOC <Ts2, it is determined that the battery 3 needs to be charged, the process proceeds to step S802, and the battery 3 is transferred to in step S802. In order to request charging, the charging request flag C_rq is set to 1. On the other hand, if it is determined in step S801 that SOC ≧ Ts2, the process proceeds to step S803, and it is determined in step S803 whether charging is being requested (C_rq = 1). When C_rq = 1, the process proceeds to step S804, and in step S804, it is determined whether the SOC of the battery 3 is less than Ts1. If SOC <Ts1, it is determined that charging needs to be continued, and the process proceeds to step S805. In step S805, charging power ΔEB is calculated using SOC function TC (SOC), and the process proceeds to step S808. Note that the function TC (SOC) is set in advance. On the other hand, if it is determined in step S804 that SOC ≧ Ts1, it is determined that charging of the battery 3 is completed, and the process proceeds to step S806. In step S806, the charge request flag C_rq is reset (= 0), and then continues. In step S807, the charging power ΔEB is set to 0, and the process proceeds to step S808. In step S808, the power consumption ΔEM consumed by the vehicle driving motor 6 is received from the motor control device 5, and in step S809, the target power generation amount ET is calculated as the sum of the power consumption ΔEM and the charging power ΔEB ( ET = ΔEB + ΔEM). Next, in step S810, the power generation request output E_rq to the internal combustion engine 1 necessary for the generator 2 to generate the target power generation amount ET is calculated by the ET function TENG (ET), and the process proceeds to step S811. In step S811, it is determined whether the power generation request output E_rq is equal to or greater than a limit value Emin at which an output can be efficiently obtained from the internal combustion engine 1. If E_rq ≧ Emin, the process proceeds to step S812, where the generator load on the generator 2, that is, the field current Igen of the generator 2 is calculated by Igen = TGEN (ET), and the process ends. On the other hand, if E_rq <Emin, in steps S813 and S814, processing for making the power generation in the internal combustion engine 1 unnecessary is performed. That is, in step S813, the field current Igen of the generator 2 is set to 0, and in step S814, the power generation request output E_rq to the internal combustion engine 1 is set to 0, and the process ends.

  FIG. 9 is a flowchart showing the processing of the internal combustion engine control unit 91. First, in step S901, an input signal of the sensor group 10 of the internal combustion engine 1, for example, an intake air amount from the air flow sensor 16, a rotation speed of the internal combustion engine 1 from the crank angle sensor 15, and an exhaust gas sensor (13, 14). Information such as the amount of residual oxygen in the exhaust gas is input, an appropriate amount of fuel is injected through the injector 17, and ignition is performed through the spark plug 18 at an appropriate timing. By these processes, the fuel is burned in the internal combustion engine 1 and an output can be obtained. Next, the process proceeds to step S902, where it is determined that the failure diagnosis is permitted or prohibited based on the experience of failure diagnosis and the state of the exhaust gas sensor (13, 14) to be subjected to the failure diagnosis. Next, in step S903, the operating point of the internal combustion engine 1 is adjusted according to the power generation request output from the generator control unit 90 or the diagnosis permission signal of the exhaust gas sensor diagnosis unit 26, and the output of the internal combustion engine 1 is adjusted. obtain. Next, in step S904, it is determined whether or not failure diagnosis of the exhaust gas sensors (13, 14) is permitted. If permitted, failure diagnosis is performed in step S905 and the process is terminated. If it is not permitted, the process is terminated.

  FIG. 10 is a flowchart showing the diagnosis permission determination process of the exhaust gas sensors (13, 14) in the exhaust gas sensor diagnosis unit 26. The determination of permission / prohibition of failure diagnosis of the exhaust gas sensors (13, 14) is permitted when at least one of the following three conditions (a), (b), and (c) is satisfied, and at least one of them: Failure diagnosis is prohibited when one is not established.

(A) The diagnosis of the exhaust gas sensor (13, 14) is incomplete.
(B) The air-fuel ratio sensor 13 is active.
(C) The output of the oxygen sensor 14 is Vout_S or more.

  The determinations from step S1001 to step S1003 in the flowchart of FIG. 10 correspond to these individual conditions (a), (b), and (c), respectively. Accordingly, if all the determinations from step S1001 to step S1003 are Y (YES), the process proceeds to step S1004, and failure diagnosis is permitted in step S1004. Otherwise, the process proceeds to step S1005, and failure diagnosis is performed in step S1005. Is prohibited and the process is terminated.

  FIG. 11 is a flowchart showing the processing of the output control unit 27. First, in step S1101, it is determined whether E_rq> 0 holds for the power generation request output E_rq to the internal combustion engine 1. If E_rq> 0, it is determined that there is a request for output to the internal combustion engine 1, and the process proceeds to step S1103. On the other hand, if E_rq = 0, it is determined that there is no request for output to the internal combustion engine 1, and in step S1102, the supply of fuel to the internal combustion engine 1 is stopped, and the operation of the internal combustion engine 1 is stopped. Exit. In step S1103, it is determined whether the internal combustion engine 1 is in operation. If the internal combustion engine 1 is already in operation, the process proceeds to step S1105. On the other hand, if the internal combustion engine 1 is stopped, the operation of the internal combustion engine 1 is started in step S1104, and the process proceeds to step S1105.

  In step S1105, it is determined whether failure diagnosis of the exhaust gas sensors (13, 14) is permitted. If the failure diagnosis is permitted, the process proceeds to step S1106, the target rotational speed NeT of the internal combustion engine 1 is set to the target rotational speed Ne_diag for failure diagnosis, and the process proceeds to step S1108. On the other hand, if failure diagnosis is not permitted, the process proceeds to step S1107, where the target rotational speed NeT of the internal combustion engine 1 is set to a normal target rotational speed for the power generation request output to the internal combustion engine 1, and the process proceeds to step S1108. Specifically, the normal target rotational speed NeT with respect to the power generation request output to the internal combustion engine 1 is calculated by a function TNeN (E_rq) of the power generation request output E_rq. The function TNeN (E_rq) is set in advance. Further, the target rotational speed Ne_diag for failure diagnosis is set to an arbitrary fixed value such that Ne_diag> TNeN (E_rq) unless the driver makes a rapid acceleration request. This is a setting for ensuring the reliability of the fault diagnosis of the exhaust gas sensors (13, 14) when the fuel supply is stopped from the state where the rotational speed of the internal combustion engine 1 is Ne_diag. Specifically, , Ne_diag is set to a value that can introduce sufficient air into the space near the exhaust gas even if the fuel supply to the internal combustion engine 1 is stopped from the state of the rotational speed value.

  In step S1108, a deviation between the actual rotational speed Ne of the internal combustion engine 1 and the target rotational speed NeT is obtained, and it is determined whether the deviation is within a predetermined error range ε. If | Ne−TeT | ≦ ε, it is determined that the vehicle is operating near the target rotational speed, and the process is terminated. On the other hand, if | Ne−NeT |> ε, the process proceeds to step S1109 to compare the magnitude relationship between the actual rotational speed Ne and the target rotational speed NeT. If Ne <NeT, the process proceeds to step S1110, the throttle opening degree Th is increased by a minute amount ΔTh in order to increase the intake air amount to the internal combustion engine 1 and increase the rotational speed, and the process is terminated. On the other hand, if Ne ≧ NeT, the process proceeds to step S1111 where the throttle opening degree Th is decreased by a minute amount ΔTh in order to reduce the rotation speed, and the process ends.

  FIG. 12 is a flowchart showing a diagnosis process of the air-fuel ratio sensor 13 among the exhaust gas sensors (13, 14) of the internal combustion engine 1. First, in step S1201, it is determined whether or not the fuel supply to the internal combustion engine 1 is stopped. If it is stopped, the process proceeds to step S1202 in order to perform diagnosis. On the other hand, if it is determined in step S1201 that the fuel supply is not stopped, the process is terminated. Next, in step S1202, it is determined whether or not the fuel supply has just stopped. Here, “immediately after” refers to the timing at which the fuel supply is stopped for the first time in the current calculation cycle without stopping the fuel supply one calculation cycle before. If it is immediately after stopping the fuel supply, the process proceeds to step S1203, the fuel supply stop timer TFC indicating the elapsed time after the fuel supply is stopped is reset (= 0), and the process proceeds to step S1205. On the other hand, if not immediately after stopping the fuel supply, in step S1204, the calculation period Δt is added to the timer TFC, and the process proceeds to step S1205. Next, in step S1205, it is determined whether or not a predetermined time TFail1 has elapsed since the stop of fuel supply. If it has elapsed, that is, if the relationship between the fuel supply stop timer TFC and the predetermined time TFail1 is TFC ≧ TFail1 Advances to step S1206, and otherwise the process ends. In step S1206, it is determined whether or not the output Vout1 of the air-fuel ratio sensor in a state where the predetermined time Tfail1 has elapsed after the fuel supply is stopped is larger than the lower limit threshold Vout_a1-α and smaller than the upper limit threshold Vout_a1 + α. Here, Vout_a1 is the saturation output of the air-fuel ratio sensor 13 at the normal time shown in FIG. If the output Vout1 of the air-fuel ratio sensor 13 is larger than the lower limit threshold value Vout_a1-α and smaller than the upper limit threshold value Vout_a1 + α, that is, if not greatly deviating from Vout_a1, the air-fuel ratio sensor 13 is normal in step S1207. Judge that there is. On the other hand, in other cases, that is, when the output Vout1 of the air-fuel ratio sensor 13 is greatly deviated from Vout_a1, it is determined in step S1208 that the air-fuel ratio sensor 13 is out of order. Next, in step S1209, it is determined that the failure diagnosis of the air-fuel ratio sensor 13 has been completed, and the process ends.

  FIG. 13 is a flowchart showing a diagnosis process of the oxygen sensor 14 among the exhaust gas sensors (13, 14) of the internal combustion engine 1. Steps S1301, S1302, S1303, and S1304 shown in FIG. 13 are the same processes as steps S1201, S1202, S1203, and S1204 shown in FIG. In step S1305, it is determined whether or not a predetermined time TFail2 has elapsed since the stop of fuel supply. If it has elapsed, that is, if TFC ≧ TFail2, the process proceeds to step S1306. Otherwise, the process ends. In step S1306, it is determined whether or not the output Vout2 of the oxygen sensor 14 in a state where the predetermined time Tfail2 has elapsed after the fuel supply is stopped is smaller than the threshold value Vout_L2. Here, the threshold value Vout_L2 is an output of the normal oxygen sensor 14 in the vicinity of the lean excess air ratio = 1.0 shown in FIG. If Vout2 <Vout_L2, it is determined in step S1307 that the oxygen sensor 14 is normal, and otherwise, it is determined in step S1308 that the oxygen sensor 14 is malfunctioning. In step S1309, it is determined that the diagnosis is complete, and the process ends.

  Next, the behavior of the rotational speed of the internal combustion engine 1 at the time of diagnosis of the exhaust gas sensors (13, 14) in the above-described power generation control device 9 will be described using the timing chart of FIG. As shown in FIG. 14, in the initial state (time: t0), the vehicle travels only with the electric power of the battery 3. When the SOC of the battery 3 gradually decreases and falls below Ts2, a request for charging the battery 3 is generated, and the internal combustion engine 1 is started (time: t1). Thereafter, the rotational speed of the internal combustion engine 1 changes according to TNeT (E_rq), which is a target rotational speed corresponding to the power generation request output from the generator control unit 90. Thereafter, when failure diagnosis of the exhaust gas sensors (13, 14) is permitted, the target rotational speed of the internal combustion engine 1 is changed from TNeT (E_rq) to the target rotational speed Ne_diag for failure diagnosis (time: t2). When the SOC of the battery 3 reaches Ts1, it is determined that charging is complete, and fuel supply to the internal combustion engine 1 is stopped (time: t3). A failure diagnosis of the exhaust gas sensors (13, 14) is performed from when the fuel supply is stopped until the rotational speed of the internal combustion engine 1 is zero, that is, until the engine stops. The number of rotations of the internal combustion engine 1 during the stop of fuel supply necessary for failure diagnosis of the exhaust gas sensors (13, 14) is ensured at the timing indicated by time t4 in FIG. On the other hand, the rotational speed of the internal combustion engine indicated by the dotted line from time t2 shows the behavior when controlled according to TNeT (E_rq), which is an output required in normal power generation control, and the exhaust gas sensor (13, 14). The rotational speed is 0 by time t4 when the failure diagnosis is completed. Therefore, in this case, it means that the failure diagnosis of the exhaust gas sensors (13, 14) whose reliability is ensured cannot be performed.

  According to the first embodiment, when failure diagnosis of the exhaust gas sensor (13, 14) is permitted, the target rotational speed of the internal combustion engine 1 is determined from the normal target rotational speed TNeT (E_rq) with respect to the power generation request output. Since it is changed to the target rotational speed Ne_diag for the gas sensor failure diagnosis and the failure diagnosis of the exhaust gas sensors (13, 14) is performed during the subsequent fuel supply stop, motoring by the generator 2 is not required. Therefore, it is possible to suppress electric energy consumption for failure diagnosis of the exhaust gas sensors (13, 14). When the failure diagnosis is prohibited after the failure diagnosis of the exhaust gas sensors (13, 14) is permitted, the target rotational speed of the internal combustion engine 1 is determined from the target rotation speed Ne_diag for the exhaust gas sensor failure diagnosis by the normal power generation control. Therefore, when there is no need to diagnose the exhaust gas sensor (13, 14), the internal combustion engine 1 can be operated at an operating point with good fuel efficiency. .

  As described above, in the first embodiment, the power generation control device 9 is mounted and used in a vehicle including the generator 2 and the internal combustion engine 1 that drives the generator 2, and is used for driving the vehicle that drives the vehicle. The target power generation amount is calculated based on the power consumption amount of the motor 6 and the charging power amount to the battery 3 that stores the power from the generator 2, and based on the target power generation amount and the storage amount of the battery 3, A target power generation amount calculation unit 22 that outputs a power generation request output to the internal combustion engine 1 indicating the power generation amount to be generated, and an air-fuel ratio or exhaust gas of exhaust gas that is disposed in the exhaust passage of the internal combustion engine 1 and is discharged from the internal combustion engine 1 Exhaust gas sensors (13, 14) according to the function of exhaust gas sensors (13, 14) for detecting the oxygen concentration in the gas (exhaust gas sensor diagnosis execution unit) and the state of the exhaust gas sensors (13, 14) Because of Exhaust gas sensor diagnosis unit 26 having a function (exhaust gas diagnosis permission unit) for determining whether or not to permit execution of the diagnosis, and exhaust gas sensor diagnosis unit 26 executes the failure diagnosis of exhaust gas sensors (13, 14). If not permitted, the target rotational speed of the internal combustion engine 1 is set to the first target rotational speed based on the power generation request output, and the exhaust gas sensor diagnosis unit 26 executes the fault diagnosis of the exhaust gas sensors (13, 14). An output control unit 27 including a target rotational speed changing unit that sets the target rotational speed of the internal combustion engine 1 to the second target rotational speed for failure diagnosis when permitted. Thus, in the first embodiment, when failure diagnosis of the exhaust gas sensors (13, 14) is permitted, the target rotational speed of the internal combustion engine 1 is set to the normal target rotational speed (first target rotational speed) with respect to the power generation request output. Rotational speed) is changed to a target rotational speed for exhaust gas sensor failure diagnosis (second target rotational speed), and failure diagnosis of the exhaust gas sensors (13, 14) is performed during the subsequent stop of fuel supply. The motoring by the machine 2 is not required, and the effect of suppressing the consumption of electrical energy for the failure diagnosis of the exhaust gas sensors (13, 14) can be obtained.

Embodiment 2. FIG.
In the first embodiment, after the exhaust gas sensor diagnosis unit 26 permits the failure diagnosis of the exhaust gas sensors (13, 14), the required power of the vehicle drive motor 6 may increase due to the driver's acceleration request. . After the failure diagnosis of the exhaust gas sensors (13, 14) is permitted, the target rotation speed of the internal combustion engine 1 is fixed to the target rotation speed Ne_diag for exhaust gas sensor failure diagnosis. It is kept constant. Therefore, when the vehicle is accelerated due to a rapid acceleration request by the driver and a large amount of electric power is consumed by the vehicle driving motor 6, the power supplied from the generator 2 is insufficient, so the insufficient amount is stored in the battery. 3 will be supplied. For this reason, if the acceleration state continues in a state where failure diagnosis of the exhaust gas sensors (13, 14) is permitted, the SOC of the battery 3 may be reduced to 0% and the vehicle may not be able to run.

  Therefore, in the second embodiment, an embodiment for solving this problem will be described. Schematic configuration of hybrid vehicle, configuration of internal combustion engine 1 and power generation control device 9, conceptual configuration of power generation control device 9, processing of generator control unit 90, processing of internal combustion engine control unit 91, exhaust gas sensors (13, 14) The diagnosis permission determination process, the air-fuel ratio sensor 13 diagnosis process, and the oxygen sensor 14 diagnosis process are the same as those in FIGS. 1, 2, 3, 9, 10, 12, and 13, respectively. Therefore, explanation is omitted.

  FIG. 15 is a flowchart showing the processing of the output control unit 27 in the second embodiment. In this flowchart, only the processing in step S1106 is changed to step S1506 with respect to the flowchart in FIG. 11, and thus description other than step S1506 is omitted here.

  In the second embodiment, as shown in FIG. 15, when the failure diagnosis of the exhaust gas sensors (13, 14) is permitted in the determination in step S1105, the process proceeds to step S1506. In step S1506, the target rotational speed NeT of the internal combustion engine 1 is set by selecting the larger one of the target rotational speed Ne_diag for diagnosing the exhaust gas sensor and the normal TNeN (E_rq) based on the power generation request output. To do.

  Next, the behavior of the rotational speed of the internal combustion engine 1 at the time of failure diagnosis of the exhaust gas sensors (13, 14) in the power generation control device 9 according to the second embodiment will be described with reference to the timing chart of FIG. Since it is the same as that of FIG. 14 until time t2, description is abbreviate | omitted here. After the target rotational speed of the internal combustion engine 1 is set to the target rotational speed Ne_diag for diagnosing the exhaust gas sensor at time t2, the power consumption of the vehicle driving motor 6 increases due to the driver's acceleration request. Here, the target rotational speed of the internal combustion engine 1 is set to TNeT (E_rq) corresponding to the sum of the power consumption of the vehicle driving motor 6 and the charging power of the battery 3 by the process of step S1506 (time: t3). . In the SOC graph of FIG. 16, a case where the target rotational speed of the internal combustion engine 1 is not changed from Ne_diag is indicated by a dotted line, and it can be seen that the SOC becomes 0 while the vehicle is traveling. When the driver's acceleration request is completed and the power consumption of the vehicle drive motor 6 is reduced, the TNeT (E_rq) corresponding to this state is lower than the Ne_diag for failure diagnosis, so the target rotational speed of the internal combustion engine 1 is Ne_diag. It is set (time: t4). When the SOC reaches Ts1, the completion of charging is determined and the fuel supply to the internal combustion engine 1 is stopped (time: t5), similarly to time t3 in FIG. A failure diagnosis of the exhaust gas sensors (13, 14) is performed after the fuel supply is stopped and before the internal combustion engine 1 is stopped.

  As described above, according to the second embodiment, the same effects as those of the first embodiment can be obtained. Further, in the second embodiment, failure diagnosis of the exhaust gas sensors (13, 14) can be performed. If permitted, the target rotational speed of the internal combustion engine 1 is set by selecting the larger one of the target rotational speed for failure diagnosis and the normal target rotational speed corresponding to the power generation request output. Even if the power consumption of the vehicle drive motor 6 increases during the diagnosis permission of (13, 14), the SOC of the battery 3 does not decrease, so that it is possible to avoid the inability to run.

Embodiment 3 FIG.
In the first embodiment described above, the rotational speed of the internal combustion engine 1 may suddenly increase at the timing when failure diagnosis of the exhaust gas sensors (13, 14) is permitted. The failure diagnosis of the exhaust gas sensor (13, 14) is permitted when the exhaust gas sensor (13, 14) is activated or the output voltage is in a predetermined state. For example, the timing at time t2 in FIG. In addition, the rotational speed of the internal combustion engine 1 suddenly increases suddenly by permission of the exhaust gas sensor failure diagnosis regardless of the driver's intention to make the vehicle running state constant. It may give a sense of incongruity on hearing. Therefore, in the third embodiment, in order to solve this problem, the target rotational speed of the internal combustion engine 1 is changed between the normal target rotational speed corresponding to the power generation request output and the target rotational speed for failure diagnosis. An embodiment in which the amount of change in the target rotational speed is limited to a predetermined value or less will be described.

  Schematic configuration of hybrid vehicle, configuration of internal combustion engine 1 and power generation control device 9, conceptual configuration of power generation control device 9, processing of generator control unit 90, processing of internal combustion engine control unit 91, exhaust gas sensors (13, 14) The failure diagnosis permission determination process, the air-fuel ratio sensor 13 diagnosis process, and the oxygen sensor 14 diagnosis process are the same as those in FIGS. 1, 2, 3, 9, 10, 12, and 13, respectively. Therefore, the description is omitted.

  FIG. 17 is a flowchart showing the processing of the output control unit 27 in the third embodiment. In this flowchart, the processing in step S1506 is changed to steps S1706, S1707, S1708, S1709, S1710, and S1711 with respect to the flowchart of FIG. Except for these steps, the contents are the same as those in FIG.

  In the third embodiment, when failure diagnosis of the exhaust gas sensor (13, 14) is permitted in step S1105, the target rotational speed Ne_diag for failure diagnosis and the normal power generation request are set in the temporary variable NeT_tmp in step S1706. Is selected and set to the larger one of the target rotational speeds TNEN (E_rq) corresponding to. In step S1707, it is determined whether the absolute value of the difference between the target rotational speed NeT and the temporary variable NeT_tmp is equal to or less than a predetermined value ΔNeT. If | NeT−NeT_tmp | ≦ ΔNeT, NeT_tmp is set in NeT in Step S1708, and the process proceeds to Step 1108. Otherwise, the process proceeds to step S1709, and the magnitude relationship between the target rotational speed NeT and the temporary variable NeT_tmp is compared. If NeT <NeT_tmp, the process proceeds to step S1710, the target rotation speed NeT is added by ΔNeT, and the process proceeds to step S1108. On the other hand, if NeT ≧ Ne_tmp, the target rotational speed NeT is subtracted by ΔNeT in step S1711, and the process proceeds to step S1108. Therefore, the amount of change in the target rotation speed is limited to ΔNeT or less by a series of these processes.

  Next, the behavior of the rotational speed of the internal combustion engine 1 at the time of failure diagnosis of the exhaust gas sensors (13, 14) in the power generation control device 9 according to Embodiment 3 will be described using the timing chart of FIG. Since the process until time t2 is the same as that in FIG. 16, the description thereof is omitted. At time t2, Ne_diag is set to the temporary variable NeT_tmp of the target rotational speed of the internal combustion engine 1, but since the amount of change in the target rotational speed NeT is limited, the rotational speed of the internal combustion engine 1 does not change abruptly. It changes slowly. Further, the increase in power consumption of the vehicle drive motor 6 due to the driver's acceleration request from time t3 and the decrease in power consumption of the vehicle drive motor 6 due to the termination of the acceleration request at time t4 also cause the internal combustion engine 1 to The change in rotation speed becomes gradual.

  According to the third embodiment, the same effects as in the first and second embodiments can be obtained. Further, in the third embodiment, the target rotational speed at the normal time (first 1) and the target rotational speed for failure diagnosis (second target rotational speed), when the target rotational speed of the internal combustion engine 1 is changed, the amount of change in the target rotational speed is a predetermined value or less. Therefore, a rapid change in the rotational speed of the internal combustion engine 1 can be suppressed. For this reason, it is possible to avoid giving the driver an uncomfortable sense of hearing such as noise.

Embodiment 4 FIG.
In the third embodiment, since the rapid change in the rotational speed of the internal combustion engine 1 is suppressed at the timing when the failure diagnosis of the exhaust gas sensors (13, 14) is permitted, the consumption of the vehicle driving motor 6 is reduced. When the electric power suddenly increases, the SOC of the battery 3 decreases until the rotational speed of the internal combustion engine 1 reaches an output corresponding to the target power generation amount. This is the reason why the increase in the SOC is delayed after time t3 in the SOC chart of FIG. For example, if the driver accelerates at the timing of climbing from a flat road, the vehicle drive motor 6 consumes a very large amount of power suddenly, the power supply from the generator 2 cannot catch up, and the SOC of the battery 3 May drop to 0%, making it impossible to run. Therefore, in the fourth embodiment, an embodiment for solving this problem will be described.

  Schematic configuration of hybrid vehicle, configuration of internal combustion engine 1 and power generation control device 9, conceptual configuration of power generation control device 9, processing of generator control unit 90, processing of internal combustion engine control unit 91, exhaust gas sensors (13, 14) The failure diagnosis permission determination process, the air-fuel ratio sensor 13 diagnosis process, and the oxygen sensor 14 diagnosis process are the same as those in FIGS. 1, 2, 3, 9, 10, 12, and 13, respectively. Therefore, the description is omitted.

  FIG. 19 is a flowchart showing processing of the output control unit 27 in the fourth embodiment. In this flowchart, the process of step S1710 is changed to step S1910 with respect to FIG. Except for step S1910, the contents are the same as those in FIG.

  In the fourth embodiment, as shown in FIG. 19, in step S1709, when the magnitude relation between the target rotational speed NeT and the temporary variable NeT_tmp is compared, if NeT <NeT_tmp, the process proceeds to step S1910. In step S1910, NeT_tmp is set as the target rotation speed NeT, and the process proceeds to step S1108. With this processing, when the target rotational speed of the internal combustion engine 1 changes to the larger one when failure diagnosis of the exhaust gas sensors (13, 14) is permitted, the amount of change in the target rotational speed is not limited. On the other hand, the amount of change is limited for the lower target rotation speed.

  Next, the behavior of the rotational speed of the internal combustion engine 1 at the time of failure diagnosis of the exhaust gas sensors (13, 14) in the power generation control device 9 according to the fourth embodiment will be described using the timing chart of FIG. Since there is no restriction on the increase side of the target rotation speed, the process is the same as that in FIG. 16 until time t3. The change in the rotational speed of the internal combustion engine 1 becomes gradual only when the power consumption of the vehicle drive motor 6 decreases due to the termination of the acceleration request at time t4.

  According to the fourth embodiment, the same effects as in the first to third embodiments can be obtained, and furthermore, in the fourth embodiment, failure diagnosis of the exhaust gas sensor (13, 14) is permitted. Then, the amount of change in the target rotation speed of the internal combustion engine 1 is limited only on the decrease side without limiting the increase side of the target rotation speed. That is, only when the target rotational speed is changed to a small value, the change amount of the target rotational speed is limited to a predetermined value or less. For this reason, even if the power consumption of the vehicle driving motor 6 increases while the failure diagnosis of the exhaust gas sensors (13, 14) is permitted, the SOC of the battery 3 does not decrease, thereby avoiding the inability to run. can do. In addition, since a rapid change on the lowering side of the rotational speed of the internal combustion engine 1 is limited, it is possible to avoid giving the driver an uncomfortable sense of hearing such as noise.

  DESCRIPTION OF SYMBOLS 1 Internal combustion engine, 2 Generator, 3 Battery, 4 Accelerator, 5 Motor control apparatus, 6 Vehicle drive motor, 7 Power converter, 8 Drive wheel, 9 Power generation control apparatus, 12 Catalytic converter, 13 Air-fuel ratio sensor, 14 Oxygen Sensor, 15 Crank angle sensor, 16 Air flow sensor, 17 Injector, 18 Spark plug, 19 Throttle.

Claims (6)

A power generation control device used by being mounted on a vehicle including a generator and an internal combustion engine that drives the generator,
A target power generation amount is calculated based on a power consumption amount of a vehicle driving motor that drives the vehicle and a charge power amount to a battery that stores power from the generator, and a function of the target power generation amount is used. A target power generation amount calculation unit for calculating a power generation request output to the internal combustion engine indicating a power generation amount to be generated;
An exhaust gas sensor diagnosis execution unit for diagnosing an exhaust gas sensor disposed in an exhaust passage of the internal combustion engine and detecting an air-fuel ratio of exhaust gas discharged from the internal combustion engine or an oxygen concentration in the exhaust gas;
According to the state of the exhaust gas sensor, an exhaust gas diagnosis permission unit that determines whether or not the exhaust gas sensor diagnosis execution unit permits execution of a failure diagnosis of the exhaust gas sensor;
When the exhaust gas sensor diagnosis permission unit does not permit execution of failure diagnosis of the exhaust gas sensor, the target rotation speed of the internal combustion engine is set to a first target rotation speed based on the power generation request output, and the exhaust gas sensor A target rotational speed changing unit that sets a target rotational speed of the internal combustion engine to a second target rotational speed for failure diagnosis when the gas sensor diagnostic permitting part permits execution of failure diagnosis of the exhaust gas sensor; Power generation control device. When the exhaust gas sensor diagnosis permission unit changes the failure diagnosis of the exhaust gas sensor from the permitted state to the prohibited state, the target rotational speed changing unit changes the target rotational speed of the internal combustion engine from the second target rotational speed to the The power generation control device according to claim 1, wherein the power generation control device is changed to a first target rotation speed. The target rotational speed changing unit is configured to replace the second target rotational speed as the target rotational speed of the internal combustion engine, which is set when the exhaust gas sensor diagnosis permitting unit permits failure diagnosis of the exhaust gas sensor, instead of the second target rotational speed. 3. The power generation control device according to claim 1, wherein a larger one of the target rotation speed of 1 and the second target rotation speed is selected and set. The target rotational speed changing unit sets a change amount of the target rotational speed to a predetermined value when changing the target rotational speed of the internal combustion engine between the first target rotational speed and the second target rotational speed. The power generation control device according to any one of claims 1 to 3, wherein the power generation control device is limited to the following. When the target rotational speed changing unit changes the target rotational speed of the internal combustion engine between the first target rotational speed and the second target rotational speed, the target rotational speed is decreased by the change. In the case, the amount of change in the target rotational speed is limited to a predetermined value or less, and when the target rotational speed increases due to the change, the amount of change in the target rotational speed is not limited. The power generation control device according to any one of claims. A power generation control method used in a vehicle including a generator and an internal combustion engine that drives the generator,
Calculating a target power generation amount based on a power consumption amount of a vehicle driving motor that drives the vehicle and a charging power amount to the battery from the generator;
Using the function of the target power generation amount to calculate a power generation request output to the internal combustion engine indicating the power generation amount to be generated;
A failure diagnosis of the exhaust gas sensor is executed according to the state of the exhaust gas sensor that is disposed in the exhaust passage of the internal combustion engine and detects the air-fuel ratio of the exhaust gas exhausted from the internal combustion engine or the oxygen concentration in the exhaust gas. Determining whether to permit;
When execution of failure diagnosis of the exhaust gas sensor is not permitted, the target rotation speed of the internal combustion engine is set to a first target rotation speed based on the power generation request output, and execution of failure diagnosis of the exhaust gas sensor is performed. If allowed, setting the target rotational speed of the internal combustion engine to a second target rotational speed for fault diagnosis;
And a step of executing failure diagnosis of the exhaust gas sensor when execution of failure diagnosis of the exhaust gas sensor is permitted.

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