JP2010116861A - Vehicle controller - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a vehicle controller capable of estimating the temperature of a catalyst highly precisely even in a vehicle equipped with an internal combustion engine which is intermittently operated. <P>SOLUTION: In this vehicle controller, an engine ECU 22 inhibits calculation of basic temperature of catalyst Tbase based on engine speed NE and engine load factor KL when an engine 11 is intermittently stopped and retracts each temperature reduction corrected value Tai, Tsp decided in accordance with outside air temperature and vehicle speed from the basic temperature of catalyst Tbase inferred at the previous time to estimate simulated temperature of catalyst, tempcat. As a result, the simulated temperature of catalyst, tempcat in a catalyst converter 58 becomes hardly estranged from actual temperature Treal, and temperature of catalyst in the catalyst converter 58 can be estimated with high precision. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a vehicle control apparatus that increases the amount of fuel injected to an internal combustion engine in order to suppress deterioration of a catalyst that purifies exhaust gas discharged from the internal combustion engine. In particular, the control device is suitable for controlling a vehicle equipped with an internal combustion engine that is operated intermittently.

In order to purify the exhaust gas discharged from the internal combustion engine, a catalyst is provided in the exhaust system of the internal combustion engine. When the temperature of the catalyst becomes higher than a predetermined criterion value, the catalyst is exposed to a lean atmosphere at a high temperature and deteriorates. For this reason, various techniques for suppressing the deterioration of the catalyst have been developed. As one of them, for example, the temperature of the catalyst is estimated, and when the estimated catalyst temperature is equal to or higher than the determination reference value, control for increasing the fuel injection amount is performed (Patent Document 1). . In this technique, the catalyst temperature is lowered to a reference value or less by suppressing the fuel injection amount to suppress the deterioration of the catalyst. The catalyst temperature is generally estimated from a basic simulated temperature calculated based on the operating state of the internal combustion engine (for example, a two-dimensional map of the engine speed and the engine load factor (intake air amount)). .
JP 2007-168470 A

  However, in the above-described technique, the internal combustion engine mounted on the vehicle is operated with idle stop control, or the internal combustion engine is mounted with an electric motor for traveling to control the internal combustion engine intermittently. When the engine is stopped intermittently, the fuel injection amount increase control may not be accurately performed. This is because a large difference occurs between the estimated temperature of the catalyst and the actual temperature. Such a deviation from the actual catalyst temperature occurs when the internal combustion engine is intermittently stopped, while the estimated temperature of the catalyst is reset to the initial value, while the actual temperature of the catalyst is constant or gradually decreases, and This is because the initial value is set to a map value that maximizes the intake air amount at the minimum engine speed for catalyst protection. For this reason, when the internal combustion engine is intermittently stopped, the estimated temperature of the catalyst becomes higher than the actual temperature of the catalyst, and the two temperatures greatly deviate from each other.

  Then, due to the temperature divergence as described above, when the internal combustion engine is restarted (automatically started), the estimated catalyst temperature is determined even though the actual catalyst temperature does not exceed the determination reference value. There is a risk of exceeding the reference value. If it does so, the increase of the fuel injection amount which is originally unnecessary will be performed, and there existed a problem that a fuel consumption and emission performance deteriorated. In particular, when the vehicle is accelerated immediately after the internal combustion engine is restarted, fuel consumption and exhaust emission are greatly deteriorated.

  Therefore, the present invention has been made to solve the above-described problems, and is a vehicle control device that can accurately estimate the temperature of a catalyst even in a vehicle equipped with an internal combustion engine that is intermittently operated. It is an issue to provide.

  The present invention, which has been made to solve the above problems, controls a vehicle including an internal combustion engine, internal combustion engine control means for intermittently operating the internal combustion engine, and a catalyst for purifying exhaust gas discharged from the internal combustion engine. The apparatus includes a catalyst temperature estimation unit that estimates the temperature of the catalyst based on an operating state of the internal combustion engine, and an intermittent stop detection unit that detects that the internal combustion engine is intermittently stopped by the internal combustion engine control unit. The catalyst temperature estimating means prohibits the estimation of the catalyst temperature based on the operating state of the internal combustion engine when the intermittent stop detecting means detects the intermittent stop of the internal combustion engine, and uses the previously estimated catalyst temperature as the catalyst. It is characterized by the estimated temperature.

  In this vehicle control device, when the internal combustion engine is intermittently stopped, the estimation of the catalyst temperature based on the operating state of the internal combustion engine is prohibited, and the previously estimated catalyst temperature is maintained as it is (during the intermittent stop). As a result, the estimated temperature of the catalyst is not reset to the initial value, and the catalyst temperature does not change suddenly during the intermittent stop. It is possible to prevent the temperature from greatly deviating. That is, the temperature of the catalyst can be accurately estimated. As a result, when the internal combustion engine is restarted (automatically started), the estimated temperature of the catalyst does not exceed the judgment reference value, so an unnecessary increase in the fuel injection amount is not performed, and fuel consumption and exhaust emission are reduced. Can be improved.

  Another aspect of the present invention made to solve the above problems is an internal combustion engine that performs intermittent operation, internal combustion engine control means that controls intermittent operation of the internal combustion engine, and exhaust gas that is discharged from the internal combustion engine. In a control apparatus for a vehicle comprising a catalyst for purifying gas, a catalyst temperature estimating means for estimating a temperature of the catalyst based on an operating state of the internal combustion engine, and the internal combustion engine is intermittently stopped by the internal combustion engine control means. An intermittent stop detecting means for detecting this, the catalyst temperature estimating means is determined according to the vehicle environment from the previously estimated catalyst temperature when the intermittent stop of the internal combustion engine is detected by the intermittent stop determining means The catalyst temperature is estimated by subtracting the correction value.

  In this vehicle control device, when the internal combustion engine is intermittently stopped, the estimation of the catalyst temperature based on the operating state of the internal combustion engine is prohibited, and a correction value determined according to the vehicle environment from the previously estimated catalyst temperature is set. The catalyst temperature is estimated by subtraction. As a result, the estimated catalyst temperature is not reset to the initial value, and the catalyst estimated by the catalyst temperature estimating means is calculated to take into account that the catalyst temperature gradually decreases during the intermittent stop. It is possible to prevent the temperature from deviating from the actual temperature. That is, the temperature of the catalyst can be estimated with higher accuracy. As a result, when the internal combustion engine is restarted (automatically started), the estimated temperature of the catalyst does not exceed the judgment reference value, so an unnecessary increase in the fuel injection amount is not performed, and fuel consumption and exhaust emission are reduced. This can be further improved.

  In the above-described invention, the vehicle is provided with an electric motor capable of outputting driving power, further includes electric motor control means for controlling driving of the electric motor, and is detected by the intermittent stop detection means. The intermittent stop of the internal combustion engine is preferably an automatic stop of the internal combustion engine in the intermittent operation control executed by the internal combustion engine control means.

  By applying the present invention to the hybrid vehicle in this way, the temperature of the catalyst can be accurately estimated during the travel mode in which only the electric motor is driven or when the vehicle is stopped. For this reason, when the internal combustion engine is automatically started, the estimated temperature of the catalyst does not exceed the judgment reference value, so that unnecessary increase of the fuel injection amount is not performed, and fuel consumption and exhaust emission can be improved. it can.

  Alternatively, in the above-described invention, the intermittent stop of the internal combustion engine detected by the intermittent stop detection means is an automatic stop of the internal combustion engine by idling stop control executed by the internal combustion engine control means while the vehicle is stopped. Also good.

  Thus, by applying the present invention to a vehicle having an idling stop function, the temperature of the catalyst can be accurately estimated at the time of idling stop. For this reason, when the internal combustion engine is automatically started, the estimated temperature of the catalyst does not exceed the judgment reference value, so that unnecessary increase of the fuel injection amount is not performed, and fuel consumption and exhaust emission can be improved. it can.

  According to the vehicle control apparatus of the present invention, as described above, the temperature of the catalyst can be accurately estimated even in a vehicle equipped with an intermittently stopped internal combustion engine. As a result, when the internal combustion engine is restarted after an intermittent stop, the estimated temperature of the catalyst does not exceed the judgment reference value, so that unnecessary increase of the fuel injection amount is not performed, and fuel consumption and exhaust emission are improved. Can do.

  DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, a most preferred embodiment in which a vehicle control device of the invention is embodied will be described in detail with reference to the drawings. In the present embodiment, the case where the present invention is applied to a hybrid vehicle including a drive source and an engine and a motor is illustrated. First, a control system for a hybrid vehicle according to the present embodiment will be described with reference to FIGS. FIG. 1 is a diagram showing a schematic configuration of a hybrid vehicle control system according to the present embodiment. FIG. 2 is a diagram showing a schematic configuration of the engine system.

  As shown in FIG. 1, the hybrid vehicle is equipped with an engine 11 and a motor (motor generator) 12 as power sources. The vehicle is also equipped with a generator (motor generator) 13 that receives the output of the engine 11 to generate power. These engine 11, motor 12 and generator 13 are connected by a power split mechanism 14. The power split mechanism 14 distributes the output of the engine 11 to the generator 13 and the drive wheels 15, transmits the output from the motor 12 to the drive wheels 15, and drives the drive wheels from the drive shaft 17 via the gear mechanism 46. It functions as a transmission related to the driving force transmitted to 15. Each drive of the engine 11 and the motors 12 and 13 is controlled by an engine electronic control device (engine ECU) 22 and a motor electronic control device (motor ECU) 27, and the drive by the engine 11 and the motor 12 and the generator 13 are controlled. The main ECU 28 comprehensively controls the driving by.

  The motor 12 is an AC synchronous motor and is driven by AC power. The inverter 18 converts electric power stored in the battery 19 from direct current to alternating current and supplies it to the motor 12, and converts electric power generated by the generator 13 from alternating current to direct current and stores it in the battery 19. is there. The generator 13 has basically the same configuration as the motor 12 described above, and has a configuration as an AC synchronous motor. In this case, the motor 12 mainly outputs the driving force, whereas the generator 13 mainly receives the output of the engine 11 to generate power.

  The motor 12 mainly generates driving force, but can also generate electric power (regenerative power generation) by using the rotation of the driving wheel 15 and can also function as a generator. At this time, a brake (regenerative brake) acts on the drive wheel 15, and the vehicle can be braked by using this together with the foot brake or the engine brake. On the other hand, the generator 13 mainly receives the output of the engine 11 and generates electric power. However, the generator 13 can function as an electric motor driven by receiving the electric power of the battery 19 via the inverter 18.

As shown in FIG. 2, the engine 11 includes an intake manifold 52, an air duct 53, and an air cleaner 54 in its intake system. The intake manifold 52, the air duct 53, and the air cleaner 54 constitute a series of intake passages 55 through which the engine 11 draws outside air. The engine 11 includes an exhaust manifold 56, an exhaust pipe 57, and a catalytic converter 58 in its exhaust system. The catalyst of the catalytic converter 58 may be composed of an oxidation catalyst such as platinum (Pt) or palladium (Pd), a reduction catalyst such as rhodium (Rh), a promoter such as ceria (CeO ₂ ), or the like. In this case, CO and HC contained in the exhaust gas are purified to water (H ₂ O) and carbon dioxide (CO ₂ ) by the action of the oxidation catalyst, and NOx contained in the exhaust gas is nitrogen (N ₂ ) and Purified to oxygen (O ₂ ). The exhaust manifold 56, the exhaust pipe 57, and the catalytic converter 58 constitute a series of exhaust passages 59 for exhausting exhaust gas from the engine 11.

  The engine 11 is provided with a fuel injection valve (injector) 61 corresponding to each of the plurality of combustion chambers 50. Fuel is supplied to these injectors 61 from a fuel tank (not shown) by a fuel pump (not shown). The fuel supplied to each injector 61 is injected toward the intake port 62 when each injector 61 is operated. Air that has been purified through an air cleaner 54 is introduced into the intake passage 55. The introduced air and the injected fuel form an air-fuel mixture and are sucked into each combustion chamber 50. The sucked air-fuel mixture is ignited and explosively burned in each combustion chamber 50 when the ignition device 63 is operated. The exhaust gas after combustion is discharged to the outside through the exhaust passage 59.

  The intake manifold 52 includes a surge tank 64 for calming the pulsation of intake air, a plurality of branch pipes 65 branching from the tank 64 to each cylinder, and a throttle body 66 positioned on the upstream side of the air flow of the surge tank 64. It has. The throttle body 66 is provided with a throttle valve 67. The throttle valve 67 opens and closes in conjunction with the operation of an accelerator pedal (not shown) by the driver. By opening and closing the throttle valve 67, the amount of air flowing through the intake passage 55 (intake amount) is adjusted. In order to measure the temperature of the air flowing through the intake passage 55 and the amount of air (intake amount), the air duct 53 is provided with an intake air temperature sensor 70 and an air flow meter 71.

  The throttle valve 67 is provided with a throttle sensor 72 for detecting its opening degree (throttle opening degree) TA. The surge tank 64 is provided with an intake pressure sensor 73 for detecting the intake pressure PM. The engine 11 is provided with a rotational speed sensor 74 that detects the angular speed of the crankshaft 20 in order to detect the rotational speed (engine rotational speed) NE. Further, the engine 11 is provided with a water temperature sensor 75 for detecting the temperature (cooling water temperature) THW of the cooling water flowing through the engine 11.

  An engine ECU 22 is provided to control the operation of the engine 11. As is well known, the engine ECU 22 includes a central processing unit (CPU) and a memory. The above-described various sensors 70 to 75 are connected to the engine ECU 22. Similarly, the injector 61 and the ignition device 63 are connected to the engine ECU 22, respectively. The engine ECU 22 executes fuel injection control and ignition timing control by controlling each injector 61 and the ignition device 63 based on detection signals from the various sensors 70 to 75. Further, engine ECU 22 estimates the catalyst temperature of catalytic converter 58. The engine ECU 22 is in communication with the main ECU 28, controls the operation of the engine 11 by a control signal from the main ECU 28, and outputs data related to the operation state of the engine 11 to the main ECU 28 as necessary.

  The power split mechanism 14 is configured by a known planetary gear unit. That is, the power split mechanism (planetary gear unit) 14 is arranged on the outer periphery of the sun gear 41, a plurality of planetary gears 42 arranged around the sun gear 41, a carrier 43 that holds each planetary gear 42, and the planetary gear 42. The ring gear 44 is formed. The crankshaft 20 of the engine 11 is connected to the carrier 43, the motor 12 is connected to the sun gear 41, and the reduction gear 45 is connected to the ring gear 44 via a ring gear shaft 44a.

  In such a power split mechanism 14, when the motor 12 functions as a generator, the power from the engine 11 input from the carrier 43 is distributed to the sun gear 41 side and the ring gear 44 side according to the gear ratio. When functioning as an electric motor, the power from the engine 11 input from the carrier 43 and the power from the motor 12 input from the sun gear 41 are integrated and output to the ring gear 44 side. The power output to the ring gear 44 is transmitted from the ring gear shaft 44a to the drive shafts 17 and 17 via the gear mechanism 46 and the differential gear 16, and finally output to the drive wheels 15 and 15 of the vehicle.

  The motor 12 has a stator 37 and a rotor 38 inside, and the generator 13 has a stator 39 and a rotor 40 inside. The drive shafts 23 and 24 of the motor 12 and the generator 13 are provided with resolvers 25 and 26 for detecting the respective rotation speeds. The resolvers 25 and 26 are connected to the motor ECU 27 and output the detected rotational speeds of the drive shafts 23 and 24 to the motor ECU 27.

  Of the various controls described above, the drive by the engine 11 and the drive by the motor 12 and the generator 13 that are characteristic of a hybrid vehicle are comprehensively controlled by the main ECU 28. That is, the distribution of the output of the engine 11 and the output of the motor 12 and the generator 13 is determined by the main ECU 28 according to the traveling state of the vehicle with respect to the driver's requested output (requested torque). In order to control the machine 13, each control command is output to the engine ECU 22 and the motor ECU 27.

  Further, the engine ECU 22 and the motor ECU 27 also output information on the engine 11, the motor 12, and the generator 13 to the main ECU 28. The main ECU 28 is also connected to a battery ECU 29 that controls the battery 19. The battery ECU 29 monitors the state of charge of the battery 19 and outputs a charge request command to the main ECU 28 when the amount of charge is insufficient. Receiving the charge request, the main ECU 28 controls the generator 13 to generate power so that the battery 19 is charged.

  The hybrid vehicle having such a configuration distributes the output (torque) required for the entire vehicle while the vehicle is running to the engine 11 and the motor 12 (generator 13), so that the operation state of the engine 11 is desired. It is possible to satisfy the output required for the entire vehicle while controlling to the driving state. In this case, the hybrid vehicle calculates the required torque based on the accelerator opening corresponding to the amount of depression of the accelerator pedal by the driver and the vehicle speed (rotation speed of the drive shaft), and the required power corresponding to this required torque is output. Thus, the engine 11, the motor 12, and the generator 13 are controlled to operate.

  In the driving force control of the hybrid vehicle, the operation control of the engine 11, the electric motor 12, and the generator 13 includes a torque conversion operation mode, a charge / discharge operation mode, and a motor operation mode.

  For example, in the torque conversion operation mode, the operation of the engine 11 is controlled so that the power corresponding to the required power is output from the engine 11, and all of the power output from the engine 11 is generated by the power split mechanism 14, the motor 12, and the power generation. This is an operation mode in which the motor 12 and the generator 13 are drive-controlled so that torque is converted by the machine 13 and output to the drive wheels 15.

  In the charge / discharge operation mode, the engine 11 is operated and controlled so that the power corresponding to the sum of the required power and the power required for charging / discharging the battery 19 is output from the engine 11, and the battery 19 is charged / discharged. The motor 12 and the generator 13 are configured such that all or part of the power output from the engine 11 is output to the drive wheels 15 with torque conversion by the power split mechanism 14, the motor 12, and the generator 13. Is an operation mode for controlling the driving of the motor.

  The motor operation mode is an operation mode in which the operation of the engine 11 is stopped and operation control is performed so that power corresponding to the required power from the motor 12 is output to the drive wheels 15. In this motor operation mode, the engine ECU 22 intermittently stops the operation of the engine 11 based on a command from the main ECU 28.

  Here, when the engine 11 is in operation, the fuel injection amount control is performed by the engine ECU 22. In this fuel injection amount control, in order to protect the catalyst in the catalytic converter 58, an OT (Over Temperature) increase is performed when the estimated temperature of the catalyst exceeds the determination reference value.

  However, when the engine 11 is automatically started after being intermittently stopped and the estimated temperature of the catalyst is reset to the initial value when the engine 11 is intermittently stopped, the estimated temperature of the catalyst and the actual temperature are greatly different. Resulting in. Then, when the engine 11 is automatically started, there is a possibility that the estimated temperature of the catalyst becomes equal to or higher than the determination reference value even though the actual catalyst temperature does not exceed the determination reference value. In such a case, an increase in the fuel injection amount which is essentially unnecessary is performed, and there is a possibility that fuel consumption and emission performance are deteriorated.

  For this reason, in the present embodiment, processing for fuel injection amount control, OT increase correction value calculation, and catalyst temperature estimation is performed as described below to solve this problem. First, fuel injection amount control and OT increase control will be described with reference to FIGS. FIG. 3 is a flowchart showing the contents of the fuel injection amount control. FIG. 4 is a flowchart showing the calculation contents of the OT increase correction value. The engine ECU 22 periodically executes the routine shown in FIG. 3 every predetermined time (for example, 100 msec).

  During operation of the engine 11, in step 1, the engine ECU 22 determines that the throttle opening degree TA detected by the throttle sensor 72, the intake air amount QA measured by the air flow meter 71, the engine rotational speed NE detected by the rotational speed sensor 74, The coolant temperature THW detected by the coolant temperature sensor 75 is read.

In step 2, the engine ECU 22 calculates a basic fuel injection amount taub corresponding to the operation state at that time based on the read intake air amount QA and the engine rotational speed NE. The engine ECU 22 calculates the basic fuel injection amount taub according to the following equation (1). In Equation (1), “K” is a predetermined proportional constant, which is determined by the engine specifications. This basic fuel injection amount taub means a basic value for calculating the final fuel injection amount etaub.
taub = K * QA / NE (1)

  In step 3, the engine ECU 22 calculates an OT increase correction value OT for performing OT increase. The OT increase means, for example, a correction term that increases the fuel injection amount taub in order to prevent the catalyst of the catalytic converter 8 from being overheated when the engine 11 is in a high rotation operation state with a high load. The engine ECU 22 calculates the correction value OT according to a subroutine shown in FIG.

  That is, in step 31 of FIG. 4, the engine ECU 22 reads the catalyst simulation (estimated) temperature tempcat. The catalyst simulated temperature tempcat means a catalyst temperature estimated on the basis of the operating state of the engine 11 or the traveling state of the vehicle according to a separate routine (see FIG. 5). The calculation of the catalyst simulation temperature tempcat will be described later. In step 32, the engine ECU 22 determines whether the catalyst simulation temperature tempcat is equal to or higher than a predetermined set value (determination reference value) T1. Here, for example, “950 ° C.” can be applied as the set value T1.

If the catalyst simulated temperature tempcat is equal to or higher than the predetermined set value T1 (S32: YES), in step 33, the engine ECU 22 calculates the OT increase correction value OT. The engine ECU 22 sets the correction value OT based on, for example, the engine rotation speed NE, the intake air amount QA, and the throttle opening degree TA, and the function data (the engine rotation speed NE, the engine load KL, and the correction value OT are set in advance as parameters. It is calculated by referring to the map. Here, the fuel injection amount tau is increased in order to prevent overheating of the catalyst at a timing when the simulated catalyst temperature tempcat becomes equal to or higher than a predetermined set value T1 when the engine 11 is in a high rotation operation state with a high load. In order to perform the OT increase, a predetermined OT increase correction value OT is obtained.
On the other hand, when the catalyst simulated temperature tempcat is lower than the predetermined set value T1 (S32: NO), the engine ECU 22 sets the OT increase correction value OT to “0” in step 34. That is, the OT increase is not performed.

  Here, calculation of the above-described catalyst simulation temperature tempcat will be described with reference to FIG. FIG. 5 is a flowchart showing the contents of the calculation process of the simulated catalyst temperature. First, in step 311, the engine ECU 22 determines whether or not the engine 11 is intermittently stopped. That is, the main ECU 28 determines whether or not the vehicle operation mode is the motor operation mode. If it is determined that the engine 11 is not intermittently stopped (S311: NO), in step 312, the engine ECU 22 sets the simulated catalyst temperature during steady operation based on the operating state of the engine 11 as in the prior art. presume. Specifically, the engine ECU 22 reads the engine rotational speed NE and the engine load KL. The engine load KL is calculated based on the engine speed NE, the intake air amount QA, and the throttle opening TA, and means the load state of the engine 11. Then, the engine ECU 22 calculates a basic catalyst simulation temperature Tbase. The engine ECU 22 calculates the basic catalyst simulation temperature Tbase by referring to a two-dimensional map of the engine rotation speed NE and the engine load KL as shown in FIG. 6, for example. In this two-dimensional map, “965 ° C.” in which NE = 1000 rpm and KL = 100% is set as an initial value. FIG. 6 is a diagram showing the contents of a map for calculating the basic catalyst simulation temperature Tbase.

  Further, the engine ECU 22 calculates an addition value of the catalyst temperature based on the retard of the ignition timing and a subtraction value of the catalyst temperature based on the vehicle speed, and corrects the basic catalyst simulation temperature Tbase by using these addition / subtraction values (correction values). The catalyst simulated temperature is tempcat. The addition value of the catalyst temperature due to the retard of the ignition timing is calculated by referring to function data (map) set in advance using the ignition timing and the temperature addition value as parameters, and the subtraction value of the catalyst temperature due to the vehicle speed is It is calculated by referring to preset function data (map) using the vehicle speed and the temperature subtraction value as parameters. This is the same as the estimation of the simulated catalyst temperature conventionally performed.

On the other hand, when it is determined that the engine 11 is intermittently stopped (S311: YES), in step 313, the engine ECU 22 does not calculate the basic catalyst simulation temperature Tbase as described above (intermittent of the engine 11). The catalyst simulation temperature immediately before the stop) is corrected by the vehicle environment correction value and calculated as the final catalyst simulation temperature tempcat. That is, when the engine 11 is intermittently stopped, the calculation (estimation) of the basic catalyst simulation temperature Tbase using the two-dimensional map shown in FIG. The final catalyst simulation temperature tempcat is calculated by subtracting the temperature decrease correction value Tai based on the outside air temperature (intake air temperature) and the temperature decrease correction value Tsp based on the vehicle speed from the catalyst simulation temperature tempcatb immediately before the intermittent stop.
tempcat = tempcatb-Tai-Tsp (2)

  In the present embodiment, as the vehicle environment correction value, a temperature decrease correction value due to the outside air temperature (intake air temperature) as shown in FIG. 7 and a temperature decrease correction value due to the vehicle speed as shown in FIG. 8 are used. FIG. 7 is a diagram showing the relationship between the intake air temperature and the temperature decrease correction value. FIG. 8 is a diagram illustrating the relationship between the vehicle speed and the temperature decrease correction value.

  As described above, when the engine 11 is intermittently stopped, the estimation of the basic catalyst temperature based on the operating state of the engine 11 is prohibited, and the previous estimated basic catalyst temperature (immediately before the intermittent stop) is used according to the outside air temperature and the vehicle speed. The final catalyst simulation temperature tempcat is calculated (estimated) by subtracting each temperature decrease correction value determined in this manner. For this reason, it is considered that the estimated temperature of the catalyst is not reset to the initial value and that the catalyst temperature gradually decreases during the intermittent stop, so that the estimated catalyst calculated by the engine ECU 22 is taken into consideration. It is possible to reliably prevent the temperature and the actual temperature from greatly deviating from each other. That is, the temperature of the catalyst of the catalytic converter 58 can be accurately estimated.

  Thereafter, in step 314, the engine ECU 22 determines whether or not the catalyst simulation temperature tempcat calculated in step 313 is 500 ° C. or less. If the catalyst simulation temperature tempcat is 500 ° C. or lower (S314: YES), the engine ECU 22 performs the lower limit guard process to set the catalyst simulation temperature tempcat to 500 ° C. in step 315, and the catalyst simulation temperature tempcat. The calculation (estimation) process is terminated. When the catalyst simulation temperature tempcat calculated in step 313 is higher than 500 ° C. (S314: NO), the engine ECU 22 ends the calculation (estimation) process of the catalyst simulation temperature tempcat without performing the lower limit guard process.

  Returning to the main routine of the injection amount control of FIG. 3, in step 4, the engine ECU 22 calculates a cold increase correction value cold for the cold increase. This cold increase amount means a correction term for increasing the fuel injection amount taub in order to promote warm-up of the engine 11 when cold. The engine ECU 22 calculates the correction value cold by referring to function data (map) set in advance using the coolant temperature THW and the cold increase correction value cold as parameters.

Next, in step 5, the engine ECU 22 calculates a total increase correction value ekrich. The engine ECU 22 calculates the total increase correction value ekrich by adding the calculated OT increase correction value OT and the cold increase correction value cold. That is, the engine ECU 22 calculates the total increase correction value ekrich according to the following equation (3).
ekrich = (OT + cold) +1 (3)

In step 6, the engine ECU 22 calculates the final fuel injection amount etau by multiplying the basic fuel injection amount taub by the total increase correction value ekrich. That is, the engine ECU 22 calculates the fuel injection amount etau according to the following equation (4). This fuel injection amount etau means a required value that the injector 61 should inject in one fuel injection.
etau = taub * ekrich (4)

  Thereafter, in step 7, the engine ECU 22 executes fuel injection by controlling the injector 61 based on the calculated fuel injection amount etau. The engine ECU 22 performs one fuel injection by opening the injector 61 at a timing determined according to the operating state of the engine 11.

  As described above, in the present embodiment, the catalyst temperature of the catalytic converter 58 can be accurately estimated even when the engine 11 is automatically started after being intermittently stopped, so that the catalyst simulation temperature tempcat is equal to or higher than the set value T1. Therefore, unnecessary OT increase is not performed. For this reason, fuel consumption and exhaust emission can be improved.

  Here, changes in various indexes indicating the catalyst temperature and the engine state when the above-described control is performed will be described with reference to FIG. FIG. 9 is a timing chart showing changes in various indices indicating the catalyst temperature and the state of the engine when the engine is automatically started after being intermittently stopped and accelerated.

  At time t1, for example, when the motor 11 is in the motor operation mode and the engine 11 is intermittently stopped, “YES” is determined in step 311 of FIG. 5, and therefore, after time t1, the two-dimensional map shown in FIG. Calculation (estimation) of the basic catalyst simulation temperature Tbase is prohibited. Then, the simulated catalyst temperature tempcat subtracts the respective temperature decrease correction values Tai and Tsp determined according to the outside air temperature and the vehicle speed from the previously estimated basic catalyst temperature (immediately before the intermittent stop) according to the above equation (2). Is calculated (estimated). As a result, it can be seen that the catalyst temperature of the catalyst converter 58 is accurately estimated without substantially deviating between the simulated temperature tempcat of the catalyst of the catalyst converter 58 and the actual temperature Treal. On the other hand, in the prior art, the basic catalyst simulation temperature Tbase is reset to the initial value, so that it can be seen that the simulation temperature tempcat and the actual temperature Treal are greatly different.

  At time t2, when the accelerator pedal is depressed during the motor operation mode to start acceleration, the engine 11 is automatically started and switched to the torque conversion operation mode. Here, in the prior art, although the actual temperature Treal of the catalyst does not exceed the set value T1, the simulated temperature tempcat exceeds the set value T1, so the OT increase is performed. The OT increase is performed until time t3 when the catalyst simulation temperature tempcat becomes equal to or lower than the set value T1. For this reason, from time t2 to t3, an unnecessary increase in the fuel injection amount is performed, the A / F (air-fuel ratio) becomes rich, and fuel consumption and emissions deteriorate.

  On the other hand, in the present embodiment, when the engine 11 is automatically started at time t2, “NO” is determined in step 311 of FIG. 5, and therefore, after time t2, 2 shown in FIG. The calculation of the basic catalyst simulation temperature Tbase by the dimension map is resumed, and the simulation temperature tempcat is calculated (estimated) by the same processing as that of the prior art. At this time, since the simulated temperature tempcat at the time of intermittent stop of the engine 11 is calculated without substantially deviating from the actual temperature Treal, the simulated temperature tempcat is calculated without greatly deviating from the actual temperature Treal even after the time t2. The Thereby, since the simulated temperature tempcat does not exceed the set value T1, OT increase is not performed. Accordingly, since an unnecessary increase in the fuel injection amount is not performed between time t2 and t3, the A / F (air-fuel ratio) is stabilized in the stoichiometric state, so that fuel consumption and emission can be improved.

  As described above, according to the vehicle control system of the present embodiment as described in detail, when the engine 11 is intermittently stopped, the engine ECU 22 estimated the catalyst simulated temperature tempcat last time (immediately before the intermittent stop). It is calculated (estimated) by subtracting each temperature decrease correction value Tai, Tsp determined according to the outside air temperature and the vehicle speed from the basic catalyst temperature. As a result, the temperature of the catalyst of the catalytic converter 58 can be accurately estimated without any substantial difference between the simulated temperature tempcat of the catalyst of the catalytic converter 58 and the actual temperature Treal. As a result, since the simulated temperature tempcat does not exceed the set value T1 when the engine 11 is restarted (automatically started), unnecessary fuel injection amount increase (OT increase) is not performed, resulting in fuel consumption and exhaust emission. Can be improved.

  It should be noted that the above-described embodiment is merely an example and does not limit the present invention in any way, and various improvements and modifications can be made without departing from the scope of the invention. For example, in the above-described embodiment, the present invention is applied to a hybrid vehicle. However, the present invention is also applied to a vehicle on which an ordinary engine not equipped with a traveling motor is mounted and idling stop control is performed. can do.

It is a figure which shows schematic structure of the control system of the hybrid vehicle which concerns on this Embodiment. It is a figure which shows schematic structure of an engine system. It is a flowchart which shows the content of fuel injection amount control. It is a flowchart which shows the calculation content of the OT increase correction value. It is a flowchart which shows the calculation processing content of catalyst simulated temperature. It is a figure which shows the content of the map for calculating basic catalyst simulation temperature. It is a figure which shows the relationship between intake temperature and a temperature fall correction value. It is a figure which shows the relationship between a vehicle speed and a temperature fall correction value. It is a timing chart which shows the change of the various parameter | index showing the catalyst temperature and the state of an engine in the case of starting automatically and accelerating after an engine stops intermittently.

Explanation of symbols

11 Engine 12 Motor 22 Engine ECU
27 Motor ECU
28 Main ECU
58 catalytic converter 61 injector 63 ignition device 67 throttle valve 70 intake air temperature sensor 71 air flow meter 72 throttle sensor 73 intake air pressure sensor 74 rotation speed sensor 75 water temperature sensor

Claims (4)

In a control apparatus for a vehicle, comprising: an internal combustion engine; an internal combustion engine control unit that intermittently operates the internal combustion engine; and a catalyst that purifies exhaust gas discharged from the internal combustion engine.
Catalyst temperature estimating means for estimating the temperature of the catalyst based on the operating state of the internal combustion engine;
Intermittent stop detection means for detecting that the internal combustion engine is intermittently stopped by the internal combustion engine control means,
The catalyst temperature estimation means prohibits the estimation of the catalyst temperature based on the operating state of the internal combustion engine when the intermittent stop detection means detects the intermittent stop of the internal combustion engine, and estimates the catalyst temperature estimated last time as the catalyst A control apparatus for a vehicle, characterized in that the temperature is set. In a control apparatus for a vehicle, comprising: an internal combustion engine that performs intermittent operation; an internal combustion engine control unit that controls intermittent operation of the internal combustion engine; and a catalyst that purifies exhaust gas discharged from the internal combustion engine.
Catalyst temperature estimating means for estimating the temperature of the catalyst based on the operating state of the internal combustion engine;
Intermittent stop detection means for detecting that the internal combustion engine is intermittently stopped by the internal combustion engine control means,
The catalyst temperature estimation means estimates the catalyst temperature by subtracting a correction value determined according to the vehicle environment from the previously estimated catalyst temperature when the intermittent stop determination means detects the intermittent stop of the internal combustion engine. A control apparatus for a vehicle. In the vehicle control device according to claim 1 or 2,
The vehicle is equipped with an electric motor capable of outputting driving power,
Electric motor control means for controlling the driving of the electric motor;
The vehicle control device according to claim 1, wherein the intermittent stop of the internal combustion engine detected by the intermittent stop detection means is an automatic stop of the internal combustion engine in the intermittent operation control executed by the internal combustion engine control means. In the vehicle control device according to claim 1 or 2,
The intermittent control of the internal combustion engine detected by the intermittent stop detection means is an automatic stop of the internal combustion engine by idling stop control executed by the internal combustion engine control means while the vehicle is stopped. .

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