Engine control device of hybrid automobile

Description: TECHNICAL FIELD [Detailed description of the invention]

【0001】

[Technical field to which the invention belongs]

The present invention relates to an engine control device for a hybrid vehicle including an engine having a purging means for purging evaporated fuel from a canister and supplying it to a combustion chamber and a motor for driving wheels.

【0002】

[Conventional technology]

Generally, an automobile engine has a canister that stores the evaporated fuel generated in the fuel tank and a purging means that purges the evaporated fuel from the canister and supplies it to the combustion chamber, and is stored in the canister during engine operation. Evaporative fuel is purged at any time and burned in the engine. However, in a hybrid vehicle equipped with an engine and a motor in which the engine is intermittently operated while the vehicle is in operation, the engine is often in a dormant state even while the vehicle is running, and the canister is used during this engine outage period. Since the stored vaporized fuel cannot be purged and the time when the purge can be performed is significantly limited, there is a problem that the amount of vaporized fuel stored in the canister tends to increase excessively.

【0003】

As a countermeasure against such a problem, for example, as shown in Japanese Patent Application Laid-Open No. 6-233410, a canister is used in an electric vehicle in which a vehicle is driven by a motor and a generator for power supply is driven by an engine. Evaporated fuel storage is detected based on the detection of the weight of the engine, the engine is driven when the evaporated fuel storage increases, and the engine is stopped when the evaporated fuel storage decreases after the engine is driven. There is something. In addition, as shown in Japanese Patent Application Laid-Open No. 8-308019, in an electric vehicle in which the vehicle is driven by a motor and the generator for power supply is driven by an engine, when the amount of electricity stored in the battery is reduced, etc. In addition to driving the engine for charging, there is also one that drives the engine with a smaller load than the driving for charging when the amount of evaporated fuel stored in the canister becomes large.

【0004】

In each of the above publications, the engine is used to drive the generator, but as a hybrid vehicle, in addition to this type, the engine is used to assist the running drive, for example. It is also known that the engine is stopped in a low load traveling region while the vehicle is driven by a motor, and the engine is driven to assist the output when an increase in output is required. Even in this type of hybrid vehicle, the engine is operated intermittently, and the amount of evaporated fuel stored in the canister tends to increase, and countermeasures are required.

【0005】

[Problems to be Solved by the Invention]

In the device shown in Japanese Patent Application Laid-Open No. 6-233410, the engine is switched to the driving state and purged when the amount of evaporated fuel stored in the canister increases while the engine is stopped while the vehicle is running. However, in this way, for example, even in a constant running state, the engine that was stopped when the amount of evaporated fuel stored in the canister increases suddenly becomes driven. Therefore, there is a problem that the driver who cannot predict the increase in the amount of evaporated fuel stored will be given a great sense of discomfort due to the unexpected driving of the engine, and the driving feeling will be deteriorated.

【0006】

In addition, the device shown in Japanese Patent Application Laid-Open No. 8-308019 also starts from the stopped state when the amount of evaporated fuel stored in the canister becomes large while the battery has a large amount of electricity stored and the engine is stopped. Since the vehicle is driven suddenly, there is a problem similar to that of JP-A-6-233410 in that the driver feels uncomfortable and the driving feeling is deteriorated.

【0007】

In view of these circumstances, the present invention is a hybrid vehicle capable of effectively eliminating an increase in the amount of evaporated fuel stored in a canister while making it possible to maintain a good driving feeling without giving a great discomfort to the driver. It is intended to provide an engine control device.

【0008】

[Means for solving problems]

The present invention comprises a canister for storing evaporated fuel generated in a fuel tank, an engine having a purging means for purging the evaporated fuel from the canister and supplying it to a combustion chamber, and a motor for driving wheels, and running under a low load. In the area, in a hybrid vehicle in which the engine is stopped and the vehicle is driven by a motor, the storage amount estimation means for estimating the amount of fuel vapor stored in the canister and the engine stop state are changed to drive by the motor only. Based on the drive change determination means that determines this when the power should be reached, the estimation by the storage amount estimation means, and the determination by the drive change determination means, if the fuel storage amount of the evaporated fuel is larger than a predetermined value, the motor The purging means is controlled so that the time when the engine is stopped is delayed with respect to the time when it is determined that the drive should be changed to only driving, and the evaporated fuel is supplied to the combustion chamber during the engine stop delay period. It is provided with a control means for the engine.

【0009】

According to this device, even when the engine is stopped from the engine drive state and it should be changed to drive only by the motor, if the canister has a large amount of evaporated fuel stored, the engine stop is delayed and the engine drive state is changed. It is maintained, during which it is purged from the canister. Therefore, the engine is in a driving region for a relatively short period of time and cannot be sufficiently purged while the engine is being driven in the driving region, or the engine is likely to increase the amount of fuel evaporated. Evaporated fuel is sufficiently purged from the canister during the engine stop delay period when the engine is in a state where it should be stopped. Moreover, since the stop of the engine from the state where the engine is running is delayed while driving, it is possible to give the driver a sense of discomfort when the engine is suddenly driven from the state where the engine is stopped. Absent.

【0010】

In the control device of the present invention, the storage amount estimation means is an air-fuel ratio detecting means so that the air-fuel ratio of the air-fuel mixture in the combustion chamber becomes the stoichiometric air-fuel ratio in a state where the evaporated fuel is supplied by the purging means. It suffices to estimate the amount of fuel vapor stored based on the learning value obtained when the feedback control of the air-fuel ratio is performed based on the output of. In this way, the amount of evaporated fuel stored can be estimated easily and accurately without the need for a special sensor or the like for estimating the amount of stored fuel.

【0011】

Further, the storage amount estimation means may estimate the vaporized fuel storage amount based on the learned value while the engine is being driven normally. In this case, when the engine should be stopped. , The amount of fuel vapor stored estimated during normal engine operation before that is used to determine whether this is high or low.

【0012】

Alternatively, the storage amount estimation means estimates the evaporated fuel storage amount based on the learning value when it is determined that the drive should be changed to the motor only, and the control means estimates the storage amount. After estimating the evaporated fuel storage amount by means, it may be possible to select whether to stop the engine or delay the engine stop according to the estimated evaporated fuel storage amount.

【0013】

In this way, it is possible to more accurately estimate the amount of fuel vapor stored at the time when the drive should be changed to the motor only.

【0014】

The control means may stop the engine when the evaporated fuel storage amount decreases below a predetermined value based on the estimation by the storage amount estimation means during the engine stop delay period. In this way, the delay period for stopping the engine is properly adjusted.

【0015】

The control means is based on the output of the air-fuel ratio detecting means so that the air-fuel ratio of the air-fuel mixture in the combustion chamber including the evaporated fuel supplied by the purge means becomes the stoichiometric air-fuel ratio during the engine stop delay period. Feedback control of the air-fuel ratio may be performed. In this case, the supply of the evaporated fuel by the purging means and the fuel supply by the fuel injection valve may be used in combination during the engine stop delay period.

【0016】

In this way, the fluctuation of the air-fuel ratio due to the variation in the amount of evaporated fuel purged during the engine stop period is suppressed.

【0017】

Further, the control means includes a generator driven by the engine, and when the vaporized fuel storage amount is equal to or higher than a predetermined value, the intake air amount of the engine and the purge provided in the purge means are provided during the engine stop delay period. The control amount of the amount adjusting means may be controlled to a predetermined value, and the power generation amount of the generator may be controlled so as to keep the engine speed at the predetermined value.

【0018】

In this way, even if all or most of the fuel supplied to the combustion chamber of the engine during the engine stop delay period is used as evaporated fuel by purging, the torque fluctuation due to the variation in the amount of evaporated fuel is controlled by the amount of power generated by the generator. It is possible to absorb the engine speed and keep the engine speed at a predetermined speed.

【0019】

When performing such control, the engine may be stopped when the amount of power generated by the generator becomes lower than a predetermined lower limit value. In this way, the engine is stopped when the engine driving force is reduced due to the decrease in the amount of evaporated fuel stored in the canister and the amount of power generation is reduced.

【0020】

In addition, the motor is driven during the engine stop delay period. Alternatively, the drive start of the motor may be delayed corresponding to the engine stop delay period.

【0021】

For example, in the case of a hybrid vehicle having a drive control system in which the motor is driven in substantially the entire operating range and the engine is driven in a specific operating range, the motor may be driven only during the engine stop delay period. In the case of a hybrid vehicle having a drive control system in which the drive of the motor is stopped in the operating region where the engine is driven, the start of driving of the motor may be delayed until the engine is stopped.

【0022】

Further, when the engine is restarted after the engine is stopped, it is preferable to stop the supply of evaporated fuel by the purging means. In this way, it is possible to prevent the combustion from becoming unstable due to the variation in the fuel supply amount.

【0023】

Further, when the vehicle is decelerated, it is preferable to stop the supply of the evaporated fuel to the combustion chamber even if the amount of evaporated fuel stored is equal to or more than a predetermined value, and preferentially perform the regenerative charging of the motor. In this way, wasteful fuel consumption can be avoided during deceleration of the vehicle, which does not require torque for traveling the vehicle and is in a state where the battery can be charged by regeneration of the motor.

【0024】

BEST MODE FOR CARRYING OUT THE INVENTION

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

【0025】

Figure 1 schematically shows the structure of the engine. In this figure, the engine body 1 has a plurality of cylinders, for example, four cylinders 2a to 2d (see FIG. 2), and each cylinder has a combustion chamber above the piston 4 inserted into the cylinder bore. 5 is formed. An intake port 7 and an exhaust port 8 are opened in the combustion chamber 5, and these ports 7 and 8 are opened and closed by an intake valve 9 and an exhaust valve 10, respectively.

【0026】

A spark plug 15 is arranged at the center of the combustion chamber 5, and the tip of the plug faces the inside of the combustion chamber 5. The spark plug 15 is connected to the ignition coil 16.

【0027】

Further, an injector (fuel injection valve) for injecting fuel into the intake port or the combustion chamber is provided. In the illustrated example, the tip of the injector 20 faces the combustion chamber 5 from the side, and the injector 20 faces the combustion chamber. Fuel is injected directly into 5. The injector 20 of each cylinder is connected to the fuel supply passage 22 and the return passage 23 via the delivery pipe 21, and these passages 22 and 23 are connected to the fuel tank 24 via a fuel pump, pressure regulator, etc. (not shown). ing. In addition, 25 is a fuel pump in a tank, and 26 is a filter.

【0028】

A canister 30 is connected to the fuel tank 24 via a passage 31 having a check valve 32, and the evaporated fuel generated in the fuel tank 24 is guided to the canister 30 via the check valve 31. Further, a purging means for purging the evaporated fuel from the canister 30 and supplying it to the combustion chamber is provided. This purging means includes a purge passage 35 connected between the canister 30 and the intake passage 40 and a purge valve 36 interposed in the purge passage 35, and intake is taken from the canister 30 when the purge valve 36 is opened. Purge gas (evaporated fuel) is introduced into the passage 40.

【0029】

Further, the intake passage 40 and the exhaust passage 41 are connected to the engine body 1. The intake passage 40 is provided with an air cleaner 43, an air flow sensor 44, a throttle valve 45 driven by a motor 46, and a surge tank 47 in this order from the upstream side. A throttle opening sensor 48 for detecting the opening of the throttle valve 45 is provided.

【0030】

On the other hand, in the exhaust passage 41, the air-fuel ratio is detected by detecting the oxygen concentration in the exhaust gas.₂A sensor (air-fuel ratio detecting means) 51 is provided, and a catalyst 52 for purifying exhaust gas is provided downstream thereof.

【0031】

60 is a control unit (ECU) for engine control. The ECU 60 includes the above airflow sensor 44, throttle opening sensor 48 and O.₂The detection signals a, b, and c from the sensor 51 are input, and the crank angle signal d and the cylinder discrimination signal e for detecting the engine speed are input from the distributor 53, and the accelerator opening (accelerator pedal depression) is further input. Detection signals f, g, h from the accelerator opening sensor 54 for detecting the amount), the intake air temperature sensor 55 for detecting the temperature of the intake air, the water temperature sensor 56 for detecting the temperature of the engine cooling water, and the like are also input.

【0032】

Further, from the ECU 60, a signal j for controlling fuel injection is output to the injector 20, a signal k for controlling ignition timing is output to the ignition coil 16, and a signal k for controlling the ignition timing is output to the motor 46 for driving the throttle valve. On the other hand, a signal l for controlling the throttle opening is output, and a signal m and the like for controlling the purge valve 36 are also output.

【0033】

FIG. 2 schematically shows the configuration of a hybrid vehicle in which the engine and the motor are used in combination.

【0034】

In this figure, the torque converter 71 on the input side of the continuously variable transmission 70 is connected to the output shaft of the engine body 1, while the axle 73 is connected to the output side of the continuously variable transmission 70 via the final speed reducer 72. At the same time, a motor 74 that also serves as a generator is connected. Further, an alternator (generator) 76 is connected to the front end side of the output shaft of the engine body 1 via a belt 75 or the like. The motor 74 and the alternator 76 are connected to the battery 79 via inverters 77 and 78.

【0035】

Then, the engine and the motor 74 are properly used to drive the vehicle according to the driving state of the vehicle by the controller for hybrid system control (ECU60 in FIG. 1 or another controller (not shown in the figure)). The engine is driven intermittently during operation.

【0036】

For example, as shown in FIG. 3, the drive of the engine and the motor 74 is controlled. That is, according to the example shown in this figure, when the vehicle is in the low load traveling region during steady driving, the engine is stopped and the motor is in a "power running" state (driving by the power supplied from the battery). The state in which the vehicle is running). When the vehicle is in the medium load driving range during steady driving, the engine operates with high efficiency (driving with good fuel efficiency), and the driving force is used to drive the vehicle, while the motor uses the driving force from the wheels. It is in a non-output state where it receives and runs idle. When the vehicle is in a high load traveling region during steady driving, the engine is put into a high output state and the motor 74 is put into a "power running" state, and the vehicle is driven by the driving force of both the engine and the motor 74.

【0037】

In addition, as a control at the time of starting, the engine is stopped and the motor is put into the "power running" state at the time of slow start, and the motor is put into the "power running" state after the engine is started at the time of sudden start. To. At the time of sudden acceleration, the engine is operated at high output and the motor is put into a "power running" state. Further, during deceleration, the engine is stopped and the motor 74 is driven by receiving a driving force from the wheel side to be in a "regenerative" state in which power is generated.

【0038】

FIG. 4 shows the functional configuration of the ECU 60. As shown in this figure, the ECU 60 has a storage amount estimation means 61 that estimates the amount of evaporated fuel stored in the canister 30 and a state in which the engine should be stopped and changed to driving only by the motor. It has a drive change determination means 62 for determination, a control means 63 for receiving estimation and determination results by these means 61 and 62, and further, a purge control unit 64, an injector control unit 65, an ignition control unit 66, and a motor control. It has part 67.

【0039】

The storage amount estimation means 61 is O, for example, as described later, so that the air-fuel ratio of the air-fuel mixture in the combustion chamber 5 becomes the stoichiometric air-fuel ratio in a state where the evaporated fuel is supplied by the purging means.₂The amount of evaporated fuel stored is estimated based on the learning value obtained when the feedback control of the air-fuel ratio is performed based on the output of the sensor 51.

【0040】

The drive change determining means 62 determines this when the operating state changes from a traveling region such as a high load to a low speed traveling region where the engine should be stopped while the engine is in the driving state.

【0041】

Further, the control means 63 is in a state where the drive change determination means 62 should be changed to drive only by the motor when the amount of evaporated fuel stored estimated by the storage amount estimation means 61 is larger than a predetermined value. The purge valve 36 is controlled via the purge control unit 64 so that the time when the engine is stopped is delayed with respect to the time when is determined, and the evaporated fuel is supplied to the combustion chamber 5 during the engine stop delay period. Then, when the amount of evaporated fuel stored decreases below a predetermined value during the engine stop delay period, or when the predetermined time set by the timer elapses, the engine is stopped and the control state is shifted to driving only the motor. It has become.

【0042】

FIG. 5 shows a specific example of the control performed by the ECU 60 in a flowchart.

【0043】

When the process shown in this flowchart starts, first in step S1, the engine speed, accelerator opening, water temperature, vehicle speed, O₂A sensor signal or the like is input, and then in step S2, the running state at that time is collated with the control characteristics as shown in FIG. 3, and it is determined whether or not the engine driving condition is satisfied.

【0044】

If the engine drive condition is satisfied, it is further determined in step S3 whether or not the F / B condition is satisfied based on the detection of the water temperature and the operating state. Here, when the F / B condition is satisfied, the air-fuel mixture in the combustion chamber (when purging is performed, the air-fuel mixture including the evaporated fuel supplied from the canister 30) is performed by a feedback control routine (not shown). ) So that the air-fuel ratio becomes the theoretical air-fuel ratio, O₂The fuel injection amount from the injector 20 is controlled based on the output of the sensor 51.

【0045】

When the above F / B condition is satisfied, it is determined in step S4 whether or not the purge valve 36 is in the purge-on state, and when the determination in step S4 is NO, the learning value L1 at the time of purge-off is calculated. (Step S5) When the determination in step S4 is YES, the learning value L2 at the time of purge-on is calculated (step S6). Then, from these learned values L1 and L2, the purge concentration (concentration of the evaporated fuel supplied from the canister 30) corresponding to the amount of evaporated fuel stored in the canister 30 is calculated (step S7).

【0046】

That is, O during F / B control₂The learning value is obtained based on the average value of the feedback correction coefficient that changes according to the output of the sensor 51. In this case, the learning value L2 at the time of purge-on is the amount of the evaporated fuel supplied from the canister 30 at the time of purge-off. The fuel injection amount deviates from the learning value L1 of. Therefore, the purge concentration is calculated from the deviations of both the above learning values L1 and L2.

【0047】

In this way, when the F / B control condition is satisfied, the engine is driven while performing feedback control and calculating the purge concentration based on the learning value (step S8). When the F / B control condition is not satisfied, the engine is driven by open control.

【0048】

If it is determined in step S2 above that the engine drive condition is not satisfied, that is, if the engine is in a low-load driving area where the engine should be stopped, whether or not the engine was driven last time in step S9 is determined. It is judged.

【0049】

When the determination in step S9 is YES, that is, when the engine is in a state where the engine should be stopped, the purge concentration calculated during the normal engine operation immediately before that in step S10 is larger than a predetermined value. Whether or not it is determined.

【0050】

When it is determined in step S10 that the purge concentration is high, the flag F is turned on (F 1) (step S11), the engine stop is delayed, and both the engine and the motor 74 are driven (step S11). Along with step S12), the purge valve 36 is opened and controlled to the purge-on state in which the evaporative fuel is supplied from the canister 30 (step S13). In addition, during the engine stop delay, fuel injection from the injector 20 is performed together with purging, and O so that the air-fuel ratio becomes the stoichiometric air-fuel ratio (λ = 1).₂While F / B control is performed to control the fuel injection amount from the injector 20 based on the output of the sensor 51, the learning value L2 at the time of purge-on is calculated (step S14), and this and the previously obtained learning at the time of purge-off are performed. The purge concentration is calculated from the value L1 (step S15).

【0051】

On the other hand, when the purge concentration decreases below the predetermined value (when the determination in step S10 becomes NO), the flag F is turned off (F 0) (step S16), the engine stops in step S18. Then, only the motor is driven. When it is determined in step S9 that the engine was not driven last time (the engine has already been stopped), it is determined whether or not the flag F is in the off state (F = 0) (step S17), and the flag F is determined. When is off (when the determination in step S17 is YES), the process proceeds to step S18 in the same manner.

【0052】

When the determination in step S17 is NO, that is, when the flag is on (F = 1), the process returns to step S10 to determine whether the purge concentration is high or not, and the purge concentration is equal to or higher than the predetermined value. During that time, the processes of steps S10 to S15 are repeated.

【0053】

According to the control device of the present embodiment as described above, the engine (and the motor 74) is driven when the engine drive condition is satisfied by operating in the medium or high load traveling region, and this state. For example, when shifting to the low load traveling region, the drive change determination means 62 determines that the engine drive condition is not satisfied, that is, it is determined that the engine should be stopped and the drive should be changed to drive only by the motor. Whether or not the concentration (the amount of fuel evaporated from the canister 30) is greater than the predetermined value is examined.

【0054】

Then, for example, the engine should be stopped in a situation where the period in which the engine is in the driving state is relatively short and the engine cannot be sufficiently purged while the engine is being driven in the operating region, or the amount of fuel vapor generated increases. If the purge concentration is high at the time when the engine drive condition is not satisfied by shifting to, the engine stop is delayed and the engine drive state is maintained, and the canister 30 purges during that time. , The amount of fuel vapor stored in the canister 30 will be sufficiently reduced.

【0055】

Moreover, even if the control for reducing the amount of evaporated fuel stored is performed in this way, the time when the engine is stopped from the engine driving state at the time of transition to the low load traveling region is only slightly delayed. There is almost no discomfort to the driver, and the driving feeling is maintained well.

【0056】

Further, during the above engine stop delay period, the combustion stability of the engine is ensured by performing feedback control of the air-fuel ratio while purging the evaporated fuel and injecting fuel from the injector 20. In other words, the amount of evaporated fuel purged from the canister 30 is liable to fluctuate and it is difficult to control it with high accuracy, but it is fed back to the theoretical air-fuel ratio by controlling the fuel injection amount from the injector 20 based on the air-fuel ratio detection. By being controlled, combustion stability is ensured.

【0057】

Further, the learning value L2 is calculated and the purge concentration is calculated based on the learning value L2 during the feedback control during the engine stop delay period, and the engine is stopped promptly when the purge concentration becomes low due to the decrease in the evaporated fuel storage amount.

【0058】

FIG. 6 is a flowchart showing another example of the control performed by the ECU 60.

【0059】

In this flowchart, steps S1 to S8 are the same as the flowchart of FIG.

【0060】

If it is determined in step S2 that the engine drive condition is not satisfied, it is in step S21 whether or not the engine drive condition was satisfied last time, that is, when the engine is switched to the state in which the engine should be stopped. Whether or not it is determined. If the determination in step S21 is YES, it is determined in step S22 whether or not the purge concentration is higher than the predetermined value, and if the purge concentration is large, the timer is set to the predetermined time in step S23 and then step S24. Move to. If the determination in step S21 is NO, steps S22 and S23 are skipped and the process proceeds to step S24.

【0061】

In step S24, the motor 74 is driven. Then, in step S25, it is determined whether or not the timer is 0. If it is determined that the timer is not 0, it means that the engine stop is delayed within a predetermined time from the time when the purge concentration is determined to be high and the timer is set. In this case, the purge valve 36 is opened and the canister 30 is opened. The engine is driven in an idle operation state (step S27) while being controlled to a purge-on state in which evaporative fuel is supplied from the engine (step S26). Then, after the timer is decremented (step S28), it is returned.

【0062】

If it is determined in step S25 that the timer is 0, the timer was not set because the purge concentration was low in the determination in step S22 before that, or the predetermined time has passed since the timer was set. Either after the lapse has passed, in this case, the process proceeds to step S30 and the engine is stopped. Also, when it is determined in step S22 that the purge concentration is low, the motor is driven and the engine is stopped (steps S29 and S30).

【0063】

In this example as well, if it is determined that the purge concentration is greater than the predetermined value when the engine drive condition is not satisfied (the engine should be stopped and changed to drive only by the motor), the engine stop is delayed. In the meantime, the canister 30 is purged, so that the amount of evaporated fuel stored in the canister 30 is sufficiently reduced, which is the same as the control example shown in FIG.

【0064】

Then, in this control example, the engine stop delay is performed only for a predetermined time set by the timer, and the engine is stopped after the lapse of the predetermined time.

【0065】

In the control shown in FIG. 6 above, as the processing during the engine stop delay period in which the timer is determined to be non-zero in step S25, the processing of steps S41 to S50 of FIG. 7 is performed instead of step S26. May be good.

【0066】

The process shown in FIG. 7 is performed by driving the engine with the evaporated fuel supplied from the canister 30 and controlling the amount of power generated by the alternator (generator) 76 driven by the engine during the engine stop delay period. The number of rotations is controlled to be constant.

【0067】

Specifically, in the above engine stop delay period, first, the target intake amount Qaobj in a predetermined engine operating state (for example, idle operating state) is calculated in step S41, and the throttle opening corresponding to the target intake amount Qaobj in step S42. Calculate TVO1. Subsequently, in step S43, the duty value DT1 of the purge duty, which is the control amount for controlling the duty of the purge valve 36, is calculated from the target intake amount Qaobj, the target air-fuel ratio A / Fobj, and the predetermined coefficient K.

【0068】

Then, the actual throttle opening tvo is controlled to the opening TVO1 calculated in step S42 (step S44), and the duty to control the purge valve 36 is set to the duty value DT1 (step S45). Further, a preset charging capacity is given as the basic control state of the alternator 76 (step S46).

【0069】

Subsequently, in step S47, it is determined whether or not the engine speed ne is higher than the set rotation speed N1, and if the judgment is YES, the alternator 76 is controlled to increase the battery charging capacity (step S48). The engine speed is reduced by increasing the generator load, and it is determined whether or not the amount of power generation is larger than the reference value W1 (step S49). If the determination in step S47 is NO, the alternator 76 is controlled to reduce the battery charging capacity (step S50), and the engine speed is increased by reducing the generator load.

【0070】

If the process of step S48 is performed and it is determined in step S49 that the amount of power generation is larger than the reference value W1, or if the process of step S50 is performed, the process proceeds to step S27 and subsequent steps in FIG. If the determination in step S49 is NO, that is, if the amount of power generation does not exceed the reference value W1 even if the alternator 76 is controlled to increase the charging capacity, the engine is moved to step S30 in FIG. Stop.

【0071】

In this way, during the engine stop delay period, the engine is driven by the evaporated fuel purged from the canister 30, which is effectively used for power generation, and all or most of the fuel supplied to the combustion chamber of the engine is used. Even when the fuel is evaporated by purging, the engine speed can be kept at a predetermined speed.

【0072】

That is, during the engine stop delay period in which the engine does not originally need to be driven, the injector 20 does not supply fuel or the fuel injection amount is reduced, and the engine is operated with the purged evaporated fuel. It is preferable to drive the engine, but the amount of fuel evaporated by purging tends to vary, and torque fluctuations due to this tend to occur. On the other hand, in this control example, the charging capacity is controlled according to the fluctuation of the engine speed, so that the torque fluctuation is absorbed and the engine speed is maintained at a predetermined speed.

【0073】

Then, when the engine driving force decreases due to the decrease in the amount of evaporated fuel stored in the canister 30, and the amount of power generated by the alternator 78 decreases, the engine is stopped.

【0074】

The specific configuration of the apparatus of the present invention is not limited to the above-described embodiment, and may be changed as listed below, for example.

【0075】

In the control example shown in each flowchart of FIGS. 5 to 7 above, when the engine drive condition is not satisfied, the purge concentration obtained based on the learning values L1 and L2 is read out during the normal engine drive before that. We are investigating whether this is large or not, but after switching to the failure of the engine drive condition, the learning value calculation and the purge concentration (evaporated fuel storage amount) may be calculated based on the feedback control. By doing so, it is possible to more accurately estimate the amount of evaporated fuel stored at the time when the engine drive condition is not satisfied. However, if the purge concentration is checked during normal engine drive as in the control example shown in the figure, the magnitude of the purge concentration can be determined immediately when the engine drive condition is not satisfied.

【0076】

In the control example shown in FIG. 3 above, the motor 74 is driven in substantially the entire operating region, and both the engine and the motor 74 are driven in a high load region or the like. However, the motor 74 is driven in the operating region in which the engine is driven. It may be stopped. In such a case, when the engine stop is delayed due to a large purge concentration after the engine drive condition is not satisfied, the motor drive start corresponding to the engine stop delay period. May be delayed.

【0077】

Although not shown in the control examples of FIGS. 5 to 7 above, when the vehicle is decelerating, in order to avoid wasteful fuel consumption, the engine is immediately stopped regardless of the amount of fuel evaporated and the motor 74 is regeneratively charged. It may be prioritized. That is, when the vehicle is decelerating, torque for running the vehicle is not required, and the motor 74 is in a state of being "regenerated" (see FIG. 3) to charge the battery, and the evaporated fuel Even if the engine is driven by the supply, it does not contribute to vehicle running or charging, so the engine may be stopped.

【0078】

Although not shown in the control examples of FIGS. 5 to 7, when restarting after the engine is stopped, the supply of evaporated fuel by purging should be stopped in order to prevent combustion instability due to variations in the fuel supply amount. Is desirable.

【0079】

[Effect of the invention]

As described above, in the hybrid vehicle, when the engine is stopped from the engine driving state and the driving state should be changed to the motor-only driving, the engine is operated when the amount of fuel vapor stored in the canister is larger than a predetermined value. Since the time to stop the engine is delayed and the evaporated fuel is supplied to the combustion chamber during the engine stop delay period, the engine stop delay postponement period may occur if the engine cannot be sufficiently purged while the engine is running. By purging the canister, the amount of fuel vapor stored in the canister can be sufficiently reduced. Moreover, since the stop of the engine from the state where the engine is running is delayed while driving, it is possible to give the driver a sense of discomfort when the engine is suddenly driven from the state where the engine is stopped. It is possible to maintain a good driving feeling.

[Simple explanation of drawings]

[Figure 1]

It is the schematic which shows an example of the engine provided with the control device of this invention.

[Figure 2]

It is the schematic of the drive system of the hybrid vehicle to which this invention is applied.

[Fig. 3]

It is a chart which shows the control characteristic of the engine and the motor of a hybrid vehicle.

[Fig. 4]

It is a block diagram which shows the mechanical structure of the ECU.

[Fig. 5]

It is a flowchart which shows an example of control.

[Fig. 6]

It is a flowchart which shows another example of control.

[Fig. 7]

It is a flowchart which shows the modification example about a part in the flowchart shown in FIG.

[Explanation of symbols]

1 Engine body 20 injector 24 fuel tank 30 canister 36 Purge valve 60 ECU 61 Occlusion estimation method 62 Drive change judgment means 63 Control means