JP2011021567A - Atmosphere learning system for oxygen concentration sensor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To properly perform the atmosphere learning of an oxygen concentration sensor and improve the detection accuracy of an oxygen concentration. <P>SOLUTION: An engine ECU 40 implements the atmosphere learning of an output value of an oxygen concentration sensor 18, based on an output value outputted by the oxygen concentration sensor 18 when inside of an exhaust passage 17 is in an atmospheric state, in a vehicle having: an engine 10 which has an oxygen concentration sensor 18 for detecting an oxygen concentration in exhaust gas of an exhaust passage 17; and a motor 22 as a power source other than the engine 10. In the engine ECU 40, it is determined whether or not an implementation condition of atmosphere learning is established. When it is determined that the implementation condition is established, the operation of the engine 10 is stopped and an engine output shaft 19 is made to rotate by driving the motor 22. After the engine output shaft 19 is rotated, the atmosphere learning is implemented. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an atmospheric learning device for an oxygen concentration sensor, and more particularly to an atmospheric learning device for performing atmospheric learning of an output value of an oxygen concentration sensor that detects an oxygen concentration in exhaust gas of an internal combustion engine.

  2. Description of the Related Art Conventionally, an oxygen concentration sensor (so-called A / F sensor) that detects an oxygen concentration (air-fuel ratio) in an exhaust gas discharged from an internal combustion engine is known. This oxygen concentration sensor is configured such that the element current flowing through the sensor element changes according to the oxygen concentration in the exhaust gas. In the internal combustion engine, air-fuel ratio control is performed based on the measurement result of the element current flowing through the sensor element.

  In the oxygen concentration sensor, an output error may occur due to manufacturing variation, secular change, and the like. Therefore, conventionally, it is determined that the exhaust pipe of the internal combustion engine is in an atmospheric state during a fuel cut period such as when the vehicle is decelerated, and the measurement value measured by the oxygen concentration sensor during the same period is regarded as a value corresponding to the oxygen concentration in the atmosphere. It has been proposed to perform atmospheric learning of the oxygen concentration sensor for calibrating the relationship between the output value of the oxygen concentration sensor and the oxygen concentration (see, for example, Patent Document 1).

JP 2003-3903 A

  However, it is not always possible to ensure a sufficient fuel cut period for atmospheric learning during driving of the vehicle by the internal combustion engine. That is, since it takes time until the inside of the exhaust pipe becomes atmospheric after execution of fuel cut is started, the fuel cut period may end before air learning is completed. In this case, the relationship between the sensor output value and the oxygen concentration cannot be calibrated, and as a result, there is a concern that the detection accuracy of the oxygen concentration is lowered.

  The present invention has been made to solve the above-described problems, and provides a control device for an internal combustion engine that can appropriately perform atmospheric learning of an oxygen concentration sensor and, in turn, improve the accuracy of oxygen concentration detection. The main purpose is to provide.

  The present invention employs the following means in order to solve the above problems.

  The present invention is applied to a vehicle including an internal combustion engine having an oxygen concentration sensor that detects an oxygen concentration in exhaust gas in an exhaust passage and a power device other than the internal combustion engine as a power source, and the inside of the exhaust passage is in an atmospheric state. The present invention relates to an atmosphere learning device of an oxygen concentration sensor that performs atmosphere learning of the sensor output value based on an output value of the oxygen concentration sensor at a certain time. The invention according to claim 1 determines that the execution condition for the atmospheric learning is satisfied, and when the determination means determines that the execution condition is satisfied, Control means for stopping the operation of the internal combustion engine and rotating the engine output shaft by driving the power unit, and learning for performing the atmosphere learning after rotating the engine output shaft by the control means Execution means.

  In general, the learning of the atmosphere of the oxygen concentration sensor is performed while the internal combustion engine is in operation, waiting for the operating state to be in a state in which an atmospheric state can be formed in the exhaust passage (for example, combustion stop state). Further, in order to bring the exhaust passage into an atmospheric state, the above operating state needs to be continued for a predetermined time. However, since the operating state of the internal combustion engine changes from time to time, it is considered that the above operating state is not continued for a sufficiently long time, and as a result, atmospheric learning cannot be performed.

  In view of that, in the present invention, in a vehicle including an internal combustion engine and a power device other than the internal combustion engine (another power device) as a power source, if the execution condition of the air learning is satisfied, the internal combustion engine may be in an operating state. If the operation is stopped, the operation stop state is maintained. Then, the engine output shaft is rotated by driving another power unit. Thereby, scavenging in the exhaust passage is performed, and an atmospheric state is formed around the oxygen concentration sensor. That is, instead of waiting for the operating state of the internal combustion engine to be in a state where the exhaust passage can be brought into the atmospheric state, the state is positively created by controlling the internal combustion engine and other power units. Therefore, according to the present invention, it is possible to properly carry out air learning, and consequently improve the accuracy of oxygen concentration detection.

  When the engine output shaft is rotated by driving another power unit, the load on the other power unit increases with the rotation. For this reason, torque loss occurs in the other power unit, and as a result, it is conceivable that torque sufficient for the torque to be output from the other power unit cannot be transmitted to the output shaft of the vehicle. Therefore, when scavenging in the exhaust passage is performed while the internal combustion engine operation is stopped and the air learning execution condition is satisfied, the operation state of the internal combustion engine is stopped as in the invention according to claim 2. The driving of the power unit may be controlled on the basis of a load torque required to rotate the engine output shaft.

  On the other hand, when scavenging in the exhaust passage is performed during the operation of the internal combustion engine as the execution condition of the air learning is satisfied, as in the invention according to claim 3, after the operation of the internal combustion engine is stopped, The driving of the power unit is controlled based on the engine torque before stopping the operation of the internal combustion engine and the load torque required to rotate the engine output shaft. In addition to the torque (load torque) required to turn the engine output shaft into a rotating state, by controlling the other power unit so as to output the torque (engine torque) before stopping the operation of the internal combustion engine from the other power unit, The vehicle running performance can be maintained after the operation of the internal combustion engine is stopped.

  According to a fourth aspect of the present invention, the on-off valve that adjusts the amount of intake air flowing into the internal combustion engine is fully opened while the engine output shaft is rotated by the power unit. When the engine output shaft is rotated by another power unit, the rotation becomes a load of the other power unit, and loss torque is generated in the other power unit. In that respect, by adopting the above configuration, the pumping loss of the internal combustion engine can be reduced, and as a result, the load of the other power unit can be reduced as much as possible. Also, by opening the on-off valve, the flow rate of fresh air to the internal combustion engine can be increased, and the formation of atmospheric conditions around the oxygen concentration sensor can be promoted. Thereby, the time required for forming the atmospheric state, that is, the scavenging period required for scavenging in the exhaust passage can be shortened. Therefore, it is suitable for reducing the load of other power units.

  According to a fifth aspect of the present invention, a rotational speed detecting means for detecting the rotational speed of the internal combustion engine or the power unit that is operating when the execution condition is satisfied, and the rotational speed detecting means detect the rotational speed. Setting means for setting a required period from the start of rotation of the engine output shaft by the power unit to the execution of the air learning based on the rotational speed of the internal combustion engine or the power unit.

  During air learning, the scavenging period required to scavenge the exhaust passage before air learning is performed, i.e., from the start of rotation of the engine output shaft by the power unit to the reading of the air output value of the oxygen concentration sensor. It is desirable to shorten the time as much as possible. Further, it is considered that the time required for scavenging varies depending on the vehicle operating state, and becomes shorter as the rotational speed of the internal combustion engine or power unit that is operating at the time when the atmospheric learning condition is satisfied increases. In this regard, according to the above configuration, an appropriate scavenging period can be set according to the rotational speed of the internal combustion engine or the power unit that is operating at the time when the atmospheric learning condition is satisfied. Thereby, air | atmosphere learning can be implemented, aiming at optimization of vehicle driving | running | working. It should be noted that the shorter the scavenging period is set, the higher the rotational speed of the internal combustion engine or power unit that is operating at the time the atmospheric learning condition is satisfied.

1 is an overall schematic configuration diagram of a vehicle control system. The flowchart which shows the process sequence of an air | atmosphere learning process. The time chart for demonstrating the specific aspect of the air | atmosphere learning process at the time of engine driving | running | working. The time chart for demonstrating the specific aspect of the air | atmosphere learning process at the time of motor driving | running | working. The time chart for demonstrating the specific aspect of the air | atmosphere learning process at the time of engine / motor driving | running | working.

  DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, embodiments of the invention will be described with reference to the drawings. This embodiment is embodied in a control device of a vehicle control system in a hybrid vehicle that uses an engine and a motor as power sources. In the control system, an engine electronic control unit (hereinafter referred to as engine ECU) and a hybrid electronic control unit (hereinafter referred to as hybrid ECU) are provided. Then, control of the fuel injection amount and ignition timing in the engine is performed with the engine ECU as the center, and the entire system of the vehicle is controlled with the hybrid ECU as the center. FIG. 1 is a block diagram showing the overall outline of the control system.

  In FIG. 1, an engine 10 is, for example, a multi-cylinder gasoline engine, and includes an injector 11 and an ignition device (eg, an igniter) 12. Further, a throttle valve 15 whose opening degree is adjusted by a throttle actuator 14 such as a DC motor is provided in the intake passage 13 of the engine 10. The opening (throttle opening) of the throttle valve 15 is detected by a throttle opening sensor 16 built in the throttle actuator 14. Air (fresh air) that has passed through the throttle valve 15 is mixed with fuel, and the mixture is used for combustion in the combustion chamber of the engine 10. Thereby, the piston (not shown) of the engine reciprocates and the output shaft (crank shaft) 19 of the engine 10 is rotated.

  The exhaust passage 17 of the engine 10 is provided with an oxygen concentration sensor 18 for detecting the air-fuel ratio (oxygen concentration) of the air-fuel mixture with exhaust gas as a detection target. Specifically, the oxygen concentration sensor 18 is a wide-area detection type A / F sensor that outputs a wide-range air-fuel ratio signal proportional to the oxygen concentration in the exhaust gas by applying a voltage to the sensor element.

  A power distribution device 20 using a planetary gear is connected to the output shaft 19 of the engine 10. A motor 22 that can be driven as an electric motor and a generator is connected to the power distribution device 20 via a gear shaft 21 a, and wheels (drive wheels) 25 are connected via a gear shaft 21 b, a differential gear 23, and a drive shaft 24. Is connected. That is, the engine 10 and the motor 22 can output power to the same drive shaft 24.

  The power distribution device 20 is provided with a clutch mechanism 26 that transmits and blocks power between the engine 10 and the motor 22. The clutch mechanism 26 is controlled to be intermittent based on a control signal from the hybrid ECU 50. That is, power transmission from the motor 22 to the engine 10 is interrupted when the clutch mechanism 26 is disconnected, and power is transmitted from the motor 22 to the engine 10 when the clutch mechanism 26 is connected. Therefore, if the motor 22 is driven and the clutch mechanism 26 is in the connected state when the engine 10 is stopped, the power is transmitted from the motor 22 to the engine 10, that is, the rotation of the motor 22 causes the engine 10 to rotate. Will be.

  A high voltage battery 28 is connected to the motor 22 via an inverter 27. When the motor 22 is driven as a generator, the electric power generated by the motor 22 is converted from alternating current to direct current by the inverter 27 and then stored in the high voltage battery 28. On the other hand, when the motor 22 is driven as an electric motor, power from the high voltage battery 28 is supplied to the motor 22 via the inverter 27.

  In addition, in this system, a low voltage battery 29 is provided in addition to the high voltage battery 28. By supplying power from the low-voltage battery 29, the system is activated, or an electric load such as the injector 11, the ignition device 12, the throttle actuator 14, or the like is driven. The low voltage battery 29 is charged by an alternator (not shown) that induces an alternating voltage as the crankshaft 19 rotates.

  As is well known, the engine ECU 40 and the hybrid ECU 50 are configured mainly by a microcomputer (hereinafter referred to as a microcomputer) including a CPU, a ROM, a RAM, and the like, and by executing various control programs stored in the ROM, Implement various controls related to vehicle drive.

  Specifically, the engine ECU 40 charges the crank angle sensor 31 that outputs a rectangular crank angle signal for each predetermined crank angle of the engine 10, the cooling water temperature sensor 32 that detects the temperature of engine cooling water, and the low-voltage battery 29. Detection signals from various sensors that detect the operating state of the engine 10, such as a battery sensor 37 that detects the state (voltage), the throttle opening sensor 16, and the like are input, and based on these various signals, the fuel injection amount and ignition The timing and the like are calculated and the drive of the injector 11 and the ignition device 12 is controlled. The engine ECU 40 is electrically connected to the hybrid ECU 50 and controls the engine 10 based on a control signal from the hybrid ECU 50.

  The hybrid ECU 50 includes an ignition switch 33, an accelerator sensor 34 that detects the accelerator operation amount, a brake sensor 35 that detects the brake operation amount, a vehicle speed sensor 36 that detects the vehicle speed, and a current sensor 38 that detects the charge / discharge current of the high-voltage battery 28. A detection signal is input from a motor rotation speed sensor 39 or the like that detects the rotation speed of the motor 22, and the drive of the motor 22, clutch mechanism 26, inverter 27, etc. is controlled based on these various signals. Further, the hybrid ECU 50 calculates the remaining capacity (SOC) of the high voltage battery 28 based on the detection value of the current sensor 38. The hybrid ECU 50 exchanges various control signals and data with the engine ECU 40, and controls the engine 10 and the motor 22 in a vehicle travel mode that takes into account the fuel efficiency of the engine 10.

  Specifically, for example, in a region where the fuel efficiency of the engine 10 is poor, such as when starting or running under a low load, the engine 10 is stopped and the wheels 25 are driven only by the power of the motor 22 (motor running mode). When the engine 10 is started during the motor running mode, the electric power stored in the high voltage battery 28 is supplied to the motor 22 via the inverter 27, and the output of the engine 10 is output by the power of the motor 22 output thereby. The shaft 19 is rotated (cranking is performed). In this cranking state, the clutch mechanism 26 is in a connected state.

  During normal travel, the wheels 25 are driven by the power of the engine 10 (engine travel mode). On the other hand, when the vehicle is accelerating or traveling at a high load, the power of the engine 10 is used to drive the wheels 25, and the electric power stored in the high voltage battery 28 is supplied to the motor 22 via the inverter 27. The wheel 25 is driven by the power of the motor 22 output by the above. That is, the wheels 25 are driven by the power of the engine 10 and the motor 22 (engine / motor travel mode).

In the above system, atmospheric learning is performed by the engine ECU 40 as processing for calibrating the relationship between the output value of the sensor 18 and the oxygen concentration for the oxygen concentration sensor 18. For details on atmospheric learning, in the period in which the fuel supply to the engine 10 is stopped while the vehicle is operating (for example, the fuel cut period during vehicle deceleration), the oxygen concentration sensor 18 has an oxygen concentration similar to that of the atmosphere. Based on the output value of the oxygen concentration sensor 18 at that time, the relationship between the sensor output value and the oxygen concentration is calibrated. More specifically, for example, the output value Vatm of the sensor 18 is read during the period in which the fuel cut is performed, and the read output value Vatm and the reference output value Vstd in the atmospheric state stored in advance in the ROM are calculated. The learning value Flea (= Vstd / Vatm) is calculated from the ratio and stored in a backup memory such as an EEPROM or a backup RAM. Then, the actual output value Vaf of the oxygen concentration sensor 18 is set to a value Vlea that does not include an output error due to manufacturing variation, deterioration with time, or the like by the following equation (1), using the learning value Flae obtained by air learning. .
Vlea = Vaf × Flea (1)
However, during operation of the vehicle, the operating state of the engine 10 changes from time to time, so that a sufficiently long fuel cut period cannot be secured, and the atmosphere is not changed between when the ignition switch 33 is turned on and when it is turned off. It is possible that learning cannot be conducted. That is, since the air-fuel mixture remains in the exhaust passage 17 immediately after the start of the fuel cut, a sufficient time is required from the start of the fuel cut until the inside of the exhaust passage 17 becomes an atmospheric state. Therefore, even if the fuel cut is started, the fuel cut period may end before the air learning is completed. In this case, the relationship between the sensor output value and the oxygen concentration cannot be calibrated, and as a result, the detection accuracy of the oxygen concentration by the oxygen concentration sensor 18 decreases.

  In view of the above, it is conceivable to perform atmospheric learning while the operation of the engine 10 is stopped. For example, immediately after the ignition switch 33 is turned on, it is presumed that the atmosphere around the oxygen concentration sensor 18 is in an atmospheric state by introducing the atmosphere into the exhaust passage 17 while the vehicle is stopped. Therefore, it is considered that the atmospheric learning can be performed with high accuracy by performing the atmospheric learning immediately after the ignition is turned on. However, in the engine operation stop period accompanying the vehicle stop, the fuel is leaked from the injector 11 or the fuel stored in the oil pan is vaporized, so that the inside of the exhaust passage 17 is not always in the atmospheric state. I can not say. Therefore, there is a possibility that atmospheric learning cannot be properly performed. Considering this point, the air learning is performed while the vehicle is traveling as much as possible, and more specifically, after the scavenging in the exhaust passage 17 is properly performed in a state where the output shaft 19 of the engine 10 can be rotated. Is desirable.

  Therefore, in the present embodiment, when it is determined that the execution condition of the air learning is satisfied for the hybrid vehicle using the engine 10 and the motor 22 as a power device other than the engine 10 as a power source, The operation is stopped and the engine output shaft 19 is rotated by driving the motor 22. Then, after the engine output shaft 19 is rotated, atmospheric learning is performed.

  More specifically, when the travel mode at the time when the atmospheric learning execution condition is satisfied is the motor travel mode, the engine 10 is kept stopped, and when the travel mode is the engine travel mode or the engine / motor travel mode, the engine 10 is stopped. Stop driving. In either case, the wheel 25 is driven by the power of the motor 22 and the engine 10 is rotated by the rotation of the motor 22 by setting the clutch mechanism 26 in the connected state. Thereby, scavenging in the exhaust passage 17 is performed appropriately. In the present embodiment, when the travel mode at the time when the atmospheric learning execution condition is satisfied is the engine travel mode or the engine / motor travel mode, the torque ( The driving of the motor 22 is controlled so that the engine torque is output from the motor 22. Thereby, it is avoided that the vehicle running performance is lowered by putting the engine 10 in the operation stop state.

  FIG. 2 is a flowchart showing the processing procedure of the atmospheric learning process. This process is executed by the engine ECU 40 at predetermined intervals.

  In FIG. 2, first, in step S101, it is determined whether or not a value 0 is set in the scavenging start flag FT. The scavenging start flag FT is a flag indicating that forced scavenging of the exhaust passage 17 has started, and is set to a value of 1 when forced scavenging has started.

  If forced scavenging of the exhaust passage 17 has not yet been started, an affirmative determination is made in step S101 and the process proceeds to step S102 to determine whether or not atmospheric learning has been performed from ignition on to the present time. In the present embodiment, when atmospheric learning is performed after the ignition is turned on, the value of the atmospheric learning completion flag FA is set from the value 0 to the value 1, and the above determination is performed based on the atmospheric learning completion flag FA. The value 1 is set in the air learning completion flag FA after the air learning is performed during the fuel cut period or after the air learning is performed by executing this routine between the ignition ON and the present time. In step S102, an affirmative determination is made, and the present process is terminated as it is. On the other hand, if atmospheric learning has not been performed from the time the ignition is turned on to the present time, the process proceeds to step S103, and it is determined whether or not the learning execution condition is satisfied.

In this embodiment, the learning execution condition is set as a condition relating to a vehicle operating state in which the inside of the exhaust passage 17 can be scavenged appropriately (in a short time). That is, from the viewpoint of running the vehicle in a running mode suitable for the driving state of the vehicle, it is desirable to shorten the scavenging period for atmospheric learning as much as possible. In addition, the time required for scavenging varies depending on the vehicle operating state. In the case where scavenging is performed by rotating the engine with the rotation of the motor 22, the shorter the rotation speed of the motor 22, the shorter. In view of this, in the present embodiment, the learning execution condition is set as a vehicle operating state in which the rotation speed of the motor 22 during the scavenging period can be set to a predetermined value or more. In particular,
(1) The vehicle speed calculated based on the output value of the vehicle speed sensor 36 is equal to or higher than a predetermined speed. (2) When the engine is operating, the engine speed calculated based on the output value of the crank angle sensor 31 is determined. (3) When the engine is in an operating state, the engine load is equal to or greater than a determination value. Specifically, the throttle opening calculated based on the output value of the throttle opening sensor 16 is equal to or greater than the determination value. (4) In the motor drive state, the motor rotation speed calculated based on the output value of the motor rotation speed sensor 39 includes at least one of a determination value and higher. Note that the above (3) is set as an engine load region in which motor travel is possible when the engine torque output from the engine 10 to the gear shaft 21b is replaced with motor torque.

Furthermore, in addition to the above (1) to (4), as conditions regarding the battery,
(5) The SOC of the high voltage battery 28 calculated based on the output value of the current sensor 38 is not less than a predetermined value. (6) The voltage of the low voltage battery 29 calculated based on the output value of the battery sensor 37 is not less than the predetermined value. It may also include at least one of certain things. This is because when the SOC of the high-voltage battery 28 is too low, the motor travel cannot be continued for a long time, and the engine 10 needs to be in an operating state during the scavenging of the exhaust passage 17. Further, if the driving of the engine 10 is stopped when the charging state of the low voltage battery 29 is deteriorated, the low voltage battery 29 cannot be charged by the alternator, and the electric load such as the injector 11 is driven after learning the atmosphere. This is because there is a risk that it will not be possible.

  When the learning execution condition is satisfied, the process proceeds to step S104, and a request signal is output to the hybrid ECU 50 to switch the clutch mechanism 26 from the disconnected state to the connected state. Thereby, the connection of the clutch mechanism 26 is started.

  In subsequent steps S105 to S107, the engine 10 and the motor 22 are controlled according to the vehicle travel mode at the time when the learning execution condition is satisfied. In other words, if the vehicle travel mode at the time when the learning execution condition is satisfied is the motor travel mode, the motor travel is continued as it is. To do.

  Specifically, in step S105, it is determined whether or not the vehicle travel mode at the time when the learning execution condition is satisfied is the motor travel mode. If it is determined that the motor travel mode is selected, the process proceeds to step S106, where the hybrid ECU 50 controls the drive of the motor 22 based on the load torque required to rotate the engine output shaft 19 when the operation of the engine 10 is stopped. Outputs a request signal.

  That is, when the engine 10 is rotated by the rotation of the motor 22 in order to scavenge the exhaust passage 17, the engine 10 becomes a motor rotation load (motor output shaft load), and torque loss occurs in the motor 22. In this case, the actual torque transmitted from the motor 22 to the gear shaft 21b is smaller than the torque commensurate with the driver's request for driving the vehicle. Therefore, when the motor for scavenging the exhaust passage 17 travels, in addition to the torque set based on the drive request from the driver, the load torque required to rotate the engine output shaft 19 when the engine is stopped, that is, the engine The target torque is set so that the load torque required for the rotation of 10 is output from the motor 22 to the gear shaft 21a. This prevents the actual torque transmitted to the drive shaft 24 from changing before and after the operation of the engine 10 is stopped.

  Specifically, for example, the relationship between the elapsed time from the connection request of the clutch mechanism 26 and the target torque is set so that the target torque of the motor 22 is set according to the connection state of the clutch mechanism 26. A map is stored in advance in the ROM, and a target torque corresponding to the current elapsed time is set based on the map. In the present embodiment, as the clutch mechanism 26 changes from the disconnected state to the connected state (for example, as the elapsed time from the connection request of the clutch mechanism 26 increases), the target torque increases and the clutch mechanism 26 enters the connected state. Thereafter, the relationship between the connection state of the clutch mechanism 26 and the target torque is defined so that the target torque becomes constant.

  On the other hand, if the vehicle travel mode when the learning execution condition is satisfied is the engine travel mode or the engine / motor travel mode, the process proceeds to step S107, where the fuel injection by the injector 11 and the ignition by the ignition device 12 are stopped. Stop burning. Simultaneously with the combustion stop of the engine 10, a request signal is sent to the hybrid ECU 50 to control the driving of the motor 22 based on the engine torque before the engine 10 is stopped and the load torque required to rotate the engine output shaft 19. Output. In other words, in addition to the torque set based on the drive request from the driver, the target torque is set so that the load torque due to the rotation of the engine 10 is output from the motor 22 to the gear shaft 21a.

  More specifically, regarding the target torque, when the engine 10 that is operating when the learning execution condition is satisfied is stopped, in addition to the motor output torque at the same point (value 0 in the engine running mode) The target torque is set so that the engine torque before the operation of the engine 10 is stopped and the load torque required to rotate the engine output shaft 19 are output from the motor 22 after the operation of the engine 10 is stopped. As for the setting of the load torque, the target torque increases as the clutch mechanism 26 changes from the disconnected state to the connected state, and the target torque becomes constant after the clutch mechanism 26 enters the connected state. .

  In step S108, the throttle actuator 14 is driven to drive the throttle valve 15 in the opening direction, so that the throttle valve 15 is fully opened. Thereafter, in step S109, a value 1 is set to the scavenging start flag FT.

  In a succeeding step S110, it is determined whether or not the inside of the exhaust passage 17 is in an atmospheric state. Here, the fact that the inside of the exhaust passage 17 is in the atmospheric state means that the elapsed time since the throttle is fully opened is equal to or greater than the determination value, or the integrated value of the intake air amount after the throttle is fully opened. Is determined based on, for example, that the value exceeds the determination value. And when it determines with the inside of the exhaust passage 17 having been in an atmospheric condition, it progresses to step S111 and performs air | atmosphere learning. That is, the learning value Flea is calculated from the ratio between the output value Vatm of the oxygen concentration sensor 18 after the vicinity of the oxygen concentration sensor 18 is forced to be in the atmospheric state and the reference output value Vstd, and this is stored in the backup memory. . Thereafter, the air learning completion flag FA is set to a value of 1 and the scavenging start flag FT is reset to a value of 0. Note that the atmospheric learning completion flag FA is reset to 0 when the ignition is turned off.

  When the atmosphere learning completion flag FA is set to the value 1, the output value Vatm of the oxygen concentration sensor 18 after the vicinity of the oxygen concentration sensor 18 is forcibly brought into the atmospheric state is compared with the reference output value Vstd. The atmospheric learning completion flag FA may be set to a value 1 when the difference is within a predetermined value. That is, when the difference between the output value Vatm and the reference output value Vstd is larger than a predetermined value, the air learning is performed again. Then, when the atmosphere learning is performed a predetermined number of times or more, for example, it is diagnosed that the oxygen concentration sensor 18 is abnormal.

  Next, specific modes of atmospheric learning according to the present embodiment will be described using the time charts of FIGS. 3 shows a case where the vehicle travel mode is the engine travel mode when the learning execution condition is satisfied, FIG. 4 shows a case of the motor travel mode, and FIG. 5 shows a case of the engine / motor travel mode. ing.

  First, a mode in which the learning execution condition is satisfied and the air learning is performed when the vehicle is traveling in the engine traveling mode will be described with reference to FIG. If the learning execution condition is satisfied while the vehicle is running and atmospheric learning has not yet been performed from ignition on until the current time (atmospheric learning completion flag FA = 0), the operation of the engine 10 is stopped at the establishment timing t11. At the same time, the driving of the motor 22 is started. Further, the connection operation of the clutch mechanism 26 is started, and the throttle valve 15 is driven to the open side. Thereafter, when the clutch mechanism 26 is fully connected at timing t12 and the throttle valve 15 is fully opened at timing t13, measurement of the elapsed time from the timing t13 is started.

  Here, with respect to the output torque of the motor 22 (transfer torque from the motor 22 to the gear shaft 21a), first, at timing t11, the engine torque Tr1 before the engine operation is stopped is replaced with the motor torque, so that the motor torque is changed to Tr1. To rise. In the subsequent timing t11 to t12, the output torque of the motor 22 gradually increases as the clutch mechanism 26 shifts to the connected state. Further, after timing t12, the motor 22 outputs the sum of the torque (Tr1) set based on the drive request from the driver and the load torque Tr2 due to the accompanying rotation of the engine 10 in the clutch fully connected state. Therefore, the transmission torque (final torque) to the drive shaft 24 does not fluctuate depending on the operation stop of the engine 10 or the clutch connection.

  During the period after t13, the clutch mechanism 26 is in the connected state, so the engine 10 is rotated by the rotation of the motor 22, and fresh air is introduced into the intake passage 13 by the rotation. Further, when the introduced fresh air is replaced with the remaining gas, the vicinity of the oxygen concentration sensor 18 is brought into an atmospheric state. At this time, since the throttle valve 15 is fully opened, the pumping loss of the engine 10 is reduced, and the motor load due to the accompanying rotation of the engine 10 is reduced as much as possible. In addition, the introduction of fresh air into the engine 10 is promoted by fully opening the throttle, and the vicinity of the oxygen concentration sensor 18 is quickly brought into the atmospheric state. Further, during this period, since the torque based on the drive request from the driver is output from the motor 22, the operation stop state of the engine 10 is continued for a time sufficient to bring the exhaust passage into the atmospheric state. At time t14, when the elapsed time since the throttle is fully opened exceeds the determination value TH, atmospheric learning is performed.

  In this embodiment, as shown in FIG. 3, the throttle opening during the atmospheric learning is left fully open from the viewpoint of reducing the motor load due to the accompanying rotation of the engine 10.

  When the atmospheric learning is completed, a value 1 is set to the atmospheric learning completion flag FA at the completion timing t15. After the air learning is completed, the driving of the engine 10, the motor 22, and the like is controlled in the vehicle travel mode according to the input results of the detection signals from various sensors.

  Next, a mode in which the learning execution condition is satisfied and the air learning is performed when the vehicle travels in the motor travel mode will be described with reference to FIG. When the learning execution condition is satisfied when the atmospheric learning completion flag FA is 0, the connection operation of the clutch mechanism 26 is started at the satisfaction timing t21, and the throttle valve 15 is driven to the open side. Since the motor traveling mode is assumed in this figure, the engine 10 has already been stopped at the timing t21, and the motor 22 is being driven. Thereafter, when the clutch mechanism 26 is fully connected at timing t22 and the throttle valve 15 is fully opened at timing t23, measurement of the elapsed time from t23 is started. At time t24, when the elapsed time since the throttle is fully opened exceeds the determination value TH, atmospheric learning is performed.

  As for the output torque of the motor 22, the torque Tr3 set based on the drive request from the driver is output before the timing t21. The output torque of the motor 22 gradually increases as the clutch mechanism 26 shifts to the connected state in the period from the timing t21 to t22, and the load due to the accompanying rotation of the engine 10 in the clutch fully connected state after the timing t22. The sum of the torque Tr4 and the torque Tr3 is output from the motor 22.

  Further, the case where the learning execution condition is satisfied and the air learning is performed when the vehicle is traveling in the engine / motor traveling mode is basically the same as that in the engine traveling mode (FIG. 3). In other words, in FIG. 5, when the learning execution condition is satisfied when the atmospheric learning completion flag FA is 0, the operation of the engine 10 is stopped and the driving of the motor 22 is started at the satisfaction timing t31. Further, the connection operation of the clutch mechanism 26 is started, and the throttle valve 15 is driven to the open side. Thereafter, when the clutch mechanism 26 is fully connected at timing t32 and the throttle valve 15 is fully opened at timing t33, measurement of the elapsed time from that t33 is started. At time t34, when the elapsed time since the throttle is fully opened exceeds the determination value TH, atmospheric learning is performed.

  Regarding the output torque of the motor 22, first, at time t31, the engine torque Tr6 before stopping the engine operation is replaced with the motor torque, so that the motor torque at t31 increases by Tr6 from the motor torque Tr5 before stopping the engine drive. . In the subsequent timing t31 to t32, the output torque of the motor 22 gradually increases as the clutch mechanism 26 shifts to the connected state. Further, after timing t32, the motor 22 outputs the sum of the torque (Tr5 + Tr6) set based on the drive request from the driver and the load torque Tr7 caused by the accompanying rotation of the engine 10 in the clutch fully connected state.

  As mentioned above, according to this embodiment explained in full detail, the following outstanding effects are acquired.

  In a hybrid vehicle including the engine 10 and the motor 22 as a power source, when it is determined that the air learning execution condition is satisfied, the engine output shaft 19 is stopped by driving the motor 10 and driving the motor 22. Since it is in a state where it is rotating and thereafter it is configured to perform air learning, for example, it is possible to sufficiently perform scavenging in the exhaust passage 17 without waiting for a fuel cut period during vehicle deceleration, and as a result, The surroundings of the oxygen concentration sensor 18 can be brought into an atmospheric state. Therefore, it is possible to appropriately perform air learning, and consequently improve the accuracy of detecting the oxygen concentration.

  When scavenging in the exhaust passage 17 is performed when the air learning execution condition is satisfied while the engine is stopped, based on the load torque required to rotate the engine output shaft 19 when the engine 10 is stopped. Therefore, the driving torque of the motor 22 is controlled so that the transmission torque from the motor 22 to the gear shaft 21b due to the accompanying rotation of the engine 10 can be suppressed. As a result, vehicle running performance can be maintained. In addition, it is possible to secure a sufficient time for the surroundings of the oxygen concentration sensor 18 to be in an atmospheric state while maintaining the vehicle traveling performance.

  When scavenging in the exhaust passage 17 is performed when the air learning execution condition is satisfied during engine operation, the engine torque before the engine 10 is stopped and the load torque required to rotate the engine output shaft 19 Therefore, in addition to the torque (load torque) required to turn the engine output shaft 19 into the rotating state, the torque before the engine 10 is stopped can be output from the motor 22. it can. As a result, the vehicle travelability can be maintained after the engine 10 is stopped. In addition, it is possible to secure a sufficient time for the surroundings of the oxygen concentration sensor 18 to be in an atmospheric state while maintaining the vehicle traveling performance.

  When the engine output shaft 19 is rotated by the rotation of the motor 22 after the learning execution condition is satisfied, the throttle valve 15 is fully opened, so that the flow rate of fresh air to the engine 10 can be increased. Formation of atmospheric conditions around the concentration sensor 18 can be promoted. Thereby, the time required to form the atmospheric state can be shortened, and the motor load can be reduced. Further, when the clutch mechanism 26 is brought into the power transmission state, the engine 10 is rotated by the rotational force of the motor 22, and a load torque is generated in the motor 22 due to the pumping loss of the engine 10 due to the rotation. By making 15 fully open, the pumping loss of the engine 10 can be minimized. As a result, the motor load can be reduced.

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

  When the air-fuel ratio feedback control is performed based on the output value of the oxygen concentration sensor 18, the air-learning process shown in FIG. 2 is performed on condition that the air-fuel ratio learning value calculated based on the feedback correction value is larger than the determination value. It is set as the structure which implements. Here, in the air-fuel ratio feedback control, an air-fuel ratio learning value is calculated according to a change with time of the engine 10 or a manufacturing error, and this air-fuel ratio learning value is reflected in the air-fuel ratio feedback control. However, when the air-fuel ratio learning value is too large, there is a possibility that some abnormality occurs in the oxygen concentration sensor 18. Therefore, when the air-fuel ratio learning value is larger than the determination value, it is preferable to calibrate the relationship between the sensor output value and the oxygen concentration by performing the air learning process. Specifically, when at least one of the above (1) to (4) is established and it is determined that the air-fuel ratio learning value is larger than the determination value, the air learning process of FIG. 2 is performed.

  Requirement from the start of rotation of the engine output shaft 19 by the motor 22 to the start of air learning based on the rotation speed detected when the learning execution condition is satisfied A period, that is, a scavenging period during which scavenging in the exhaust passage 17 is performed during atmospheric learning is set. Specifically, the scavenging period is set to be shorter as the rotational speed of the engine 10 or the motor 22 that is operating at the time when the atmospheric learning condition is satisfied. Then, air learning is performed after the set scavenging period has elapsed from the rotation start timing of the engine output shaft 19 by the motor 22. That is, when learning the atmosphere, it is desirable to shorten the scavenging period before the atmosphere learning is performed as much as possible. Further, the time required for scavenging varies depending on the vehicle operating state, and is considered to be shorter as the rotational speed of the engine 10 or the motor 22 that is operating at the time when the atmospheric learning condition is satisfied is larger. Therefore, by setting it as the said structure, a suitable scavenging period can be set according to the rotational speed of the engine 10 or the motor 22 which is operating at the time of the atmospheric learning condition establishment. Thereby, air | atmosphere learning can be implemented, aiming at optimization of vehicle driving | running | working.

  In the above embodiment, when the learning execution condition is satisfied, the engine 10 and the motor 22 are controlled so that the engine 10 is in the operation stop state and the motor 22 is in the drive state at the time when the learning execution condition is satisfied. The operation stop timing 10 and the motor 22 drive start timing are not limited to the timing at which the learning execution condition is satisfied. For example, when the learning execution condition is satisfied while the vehicle is traveling in the engine travel mode, the motor 22 first starts idling at the time when the learning execution condition is satisfied (t11 in FIG. 3), and then the clutch mechanism 26 is in a fully connected state. At the same timing (t12 in FIG. 3), the operation of the engine 10 is stopped and power is output from the motor 22.

  Although the connection start of the clutch mechanism 26 is performed at the time when the learning execution condition is satisfied, the present invention is not limited to this, and the connection of the clutch mechanism 26 may be started after the time when the learning execution condition is satisfied. Further, the timing at which the throttle valve 15 is fully opened is not particularly limited, and the throttle mechanism may be fully opened before the clutch mechanism 26 is fully connected or at the same time as the clutch mechanism 26 is fully connected.

  The output torque of the motor 22 after the engine 10 is brought into the drive stop state in accordance with the establishment of the learning execution condition is variably set according to the temperature of the engine 10 (for example, the engine coolant temperature). Here, as the engine temperature is lower, the friction of the engine 10 becomes larger. As a result, the motor torque loss when the clutch mechanism 26 is in the engaged state when the engine is stopped, that is, the load torque of the motor 22 caused by the accompanying rotation of the engine 10 Becomes larger. Therefore, with the above configuration, a torque corresponding to the load torque of the motor 22 caused by the accompanying rotation of the engine 10 can be output from the motor 22. Thereby, it can suppress suitably that the driveability of a vehicle falls.

  In the above embodiment, the clutch mechanism 26 is set in the power cut-off state when the scavenging in the exhaust passage 17 is completed, and then the atmosphere learning is executed. More specifically, when the learning execution condition is satisfied (for example, t11 in FIG. 3), the clutch mechanism 26 is set in the power transmission state, and then it is determined that the inside of the exhaust passage 17 is in the atmospheric state (for example, FIG. 3). At t14), the clutch mechanism 26 is brought into a power cut-off state. According to this configuration, the clutch mechanism 26 is in the power transmission state only during the scavenging period in the exhaust passage 17. For this reason, the load torque required to rotate the engine output shaft 19 for the motor 22 can be minimized.

  In the above-described embodiment, the atmosphere learning is performed with the throttle valve 15 fully opened, but when the scavenging in the exhaust passage 17 is completed, the throttle valve 15 is driven from the fully opened state to the closed side (for example, fully closed), Atmospheric learning may be performed in this state. When the throttle valve 15 is closed from the fully opened state during the air learning, the exhaust flow velocity in the exhaust passage can be reduced. Thereby, the gas atmosphere around the oxygen concentration sensor 18 can be stabilized at the time of reading the atmospheric output value of the oxygen concentration sensor 18, which is suitable for stabilizing the sensor output.

  In the above embodiment, the engine ECU 40 is configured to perform the air learning process, but the hybrid ECU 50 may be configured to perform the air learning process.

  In the above embodiment, the vehicle including the engine 10 and the motor 22 as the power source has been described. However, the vehicle can be driven only by the power device other than the engine 10 including the engine 10 and the power device other than the engine 10. If it is a simple vehicle, it is not limited to the hybrid vehicle of the said structure. The engine 10 is not limited to a gasoline engine, and the present invention may be applied to a diesel engine.

  DESCRIPTION OF SYMBOLS 10 ... Engine, 15 ... Throttle valve (open / close valve), 17 ... Exhaust passage, 18 ... Oxygen concentration sensor, 19 ... Crankshaft, 20 ... Power distribution device, 22 ... Motor (power device), 26 ... Clutch mechanism (clutch means) ), 40... Engine ECU (control means, learning execution means, clutch means), 50... Hybrid ECU.

Claims (5)

Applied to a vehicle having an internal combustion engine having an oxygen concentration sensor for detecting an oxygen concentration in exhaust gas in an exhaust passage, and a power device other than the internal combustion engine as a power source;
An atmosphere learning device for an oxygen concentration sensor that performs atmosphere learning of an output value of the oxygen concentration sensor based on an output value of the oxygen concentration sensor when the exhaust passage is in an atmospheric state,
Determination means for determining that the execution condition of the atmospheric learning is satisfied;
Control means for stopping the operation of the internal combustion engine and rotating the engine output shaft by driving the power unit when the execution means determines that the execution condition is satisfied;
Learning execution means for performing the air learning after rotating the engine output shaft by the control means;
An atmosphere learning device for an oxygen concentration sensor, comprising:   When the internal combustion engine is stopped at the time when the execution condition is satisfied, the control means is configured to control the power based on a load torque required to rotate the engine output shaft when the internal combustion engine is stopped. The oxygen learning sensor atmosphere learning device according to claim 1, wherein the device driving is controlled.   When the internal combustion engine is in operation at the time when the execution condition is satisfied, the control means rotates the engine torque and the engine output shaft before the internal combustion engine is stopped after the internal combustion engine is stopped. The atmosphere learning device for an oxygen concentration sensor according to claim 1 or 2, wherein the driving of the power unit is controlled based on a load torque required for the oxygen concentration sensor.   The oxygen concentration sensor according to any one of claims 1 to 3, further comprising means for fully opening an on-off valve that adjusts an intake air amount flowing into the internal combustion engine while the engine output shaft is rotated by the power unit. Atmosphere learning device. A rotational speed detecting means for detecting the rotational speed of the internal combustion engine or the power unit that is operating when the execution condition is satisfied;
Setting means for setting a required period from the start of rotation of the engine output shaft by the power unit to execution of the atmospheric learning based on the rotation speed of the internal combustion engine or the power unit detected by the rotation speed detection unit; ,
An atmosphere learning device for an oxygen concentration sensor according to any one of claims 1 to 4.

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