JP2000104588A - Air-fuel ratio controller for engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To efficiently reduce NOx from the beginning of a restarting by correcting an air-fuel ratio in the restarting to be temporarily richer than a target value in compliance with an integrated value of an intake air amount or a stopping time from a stop of fuel supply to an engine till the restart. SOLUTION: When it is determined that it is not in a fuel-cut condition while the number of idle revolutions is a reference value or more and a feedback control condition is established, it is determined whether operating conditions till the previous time is in a fuel-cut condition or not (S1-S4). If it is determined that fuel injection is restarted for the first time, a correction value PLCLP for a proportional part P of an air-fuel ratio feedback control constant found from an integrated value SQa of an intake air amount integrated during a stop of an engine is corrected with a correction coefficient KPLVTC based on a cam actuation angle, and a feedback control constant α is set so that an air-fuel ratio is shifted greatly to the rich side (S5-S8, S14). Including the feedback control constant α, a fuel injection amount is computed (S16), and then, control for enriching the air-fuel ratio is carried out.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an air-fuel ratio control device for an engine, and more particularly, to an air-fuel ratio control device for an engine of a hybrid vehicle.

[0002]

2. Description of the Related Art There has been known a hybrid vehicle having both an engine (internal combustion engine) and an electric motor as a prime mover and running with one or both driving forces (for example, a railway). "Automotive Engineering" VOL.46 No.7, June 1997, published by Nihonsha, pp. 39-52).

[0003] Such a so-called parallel type hybrid vehicle basically runs only on the electric motor in an operation range where the load is relatively small. When the load increases, the engine is started to secure a required driving force, and Accordingly, the maximum driving force can be exhibited by using an electric motor and an engine together. The engine is also driven when the charged amount of the battery becomes equal to or less than the set value, and charges the battery.

[0004] In order to purify exhaust gas discharged from the engine, a three-way catalyst is provided in the engine exhaust passage to oxidize HC and CO and reduce NOx.

[0005] As described above, in a hybrid vehicle, the engine is not always driven during running, and the operation is frequently stopped when it is not necessary. For this reason, when the engine is started when necessary, if the three-way catalyst does not function immediately after the start, the exhaust gas purification efficiency deteriorates during that time.

However, while the engine is stopped,
The three-way catalyst is placed in an oxygen atmosphere because it becomes the same state as the fuel cut at the time of deceleration or the exhaust passage is filled with air. Even if the primary catalyst is in an active state, there is a problem that the NOx reduction efficiency tends to decrease.

The present invention has been proposed to solve such a problem, and it is an object of the present invention to improve exhaust characteristics at the time of restarting an engine, particularly, NOx purification efficiency.

[0008]

A first invention comprises an engine and a motor for starting the engine, automatically stops the engine at least when the vehicle is temporarily stopped, and automatically starts the engine when the vehicle starts. A three-way catalyst provided in an exhaust passage of the engine, a sensor for detecting an exhaust gas component, an air-fuel ratio control means for feedback-controlling an air-fuel ratio to a target value in accordance with the output of the sensor, Air-fuel ratio correction means for temporarily correcting the air-fuel ratio at the time of restart to be higher than the target value in accordance with the integrated value of the intake air amount or the stop time from when the supply of fuel to the fuel is stopped to when the fuel is restarted. .

According to a second aspect of the present invention, there is provided an engine, a clutch interposed in a path for transmitting rotation of the engine to driving wheels, a first motor for rotating the driving wheels, and power generation by starting or driving the engine. A second motor,
In a hybrid vehicle including a battery that stores generated power and supplies electric power to a second motor, and a controller that controls the engine, clutch, and first and second motors, a hybrid vehicle provided in an exhaust passage of the engine. A source catalyst, a sensor for detecting an exhaust gas component, an air-fuel ratio control means for feedback-controlling an air-fuel ratio to a target value according to the output of the sensor, and an intake from stopping supply of fuel to the engine until restarting. Air-fuel ratio correction means for temporarily correcting the air-fuel ratio at the time of restart to be higher than the target value in accordance with the integrated value of the air amount or the stop time.

In a third aspect based on the first or second aspect, the air-fuel ratio correction means determines the proportion of the air-fuel ratio feedback control constant on the rich side when the engine is restarted to the intake air amount integrated value or the stop. Increase according to time.

In a fourth aspect based on the third aspect, the engine includes a variable valve operating device, and a proportional component of the air-fuel ratio feedback control constant is determined according to a cam operating angle of the variable valve operating device when the engine is restarted. Correct the size of.

In a fifth aspect based on the first to fourth aspects, the sensor includes a heater, and heats the sensor so that the sensor temperature does not fall below the activation temperature even when the engine is stopped.

According to a sixth aspect, in the second aspect, a restart torque absorbing means is provided for driving the second motor when the engine is restarted, and absorbing the engine torque by the drive motor torque.

In a seventh aspect based on the sixth aspect, the restart torque absorbing means sets the motor drive torque according to the integrated value or the stop time of the intake air amount or the correction value of the air-fuel ratio.

According to an eighth aspect of the present invention, in the second aspect, a restart torque absorbing means for absorbing engine torque by correcting the ignition timing by retarding the ignition timing from the normal control value when the engine is restarted is provided.

[0016]

According to the first or second aspect of the present invention, when the fuel supply to the engine is stopped, a restart is performed in accordance with the integrated value of the intake air amount or the stop time until the next fuel supply is restarted. Temporarily increases the air-fuel ratio, so that even if oxygen is deposited on the three-way catalyst at the time of restart, HC,
By increasing the CO concentration, a reducing atmosphere can be formed, and NOx can be efficiently reduced from the initial stage of the restart. In this case, the degree to which the air-fuel ratio is made richer than the target value is
Estimate the amount of oxygen deposited on the three-way catalyst while the engine is stopped,
Since the setting is made in accordance with this, it is possible to enrich the air-fuel ratio without excess or deficiency for the reduction of NOx, and it is possible to minimize deterioration of fuel efficiency.

In the third aspect, since the proportional component of the feedback control constant is corrected, the air-fuel ratio can be increased with good response at the time of restart, and NOx can be reliably reduced from the initial stage of restart.

In the fourth invention, the basic fuel injection amount changes in accordance with the cam operation angle at the time of restarting. Thus, the air-fuel ratio can be appropriately concentrated.

In the fifth aspect of the present invention, the sensor activation state is maintained while the engine rotation is stopped, so that a lean judgment can be made at all times when the engine is restarted. Based on this, the air-fuel ratio can be shifted to the rich side, and at the time of restart, The air-fuel ratio can be reliably enriched.

In the sixth to eighth aspects, the increase in torque caused by enriching the air-fuel ratio when the engine is restarted can be appropriately absorbed by correcting the drive torque of the motor or the retardation of the ignition timing. It is possible to reduce the torque shock at the time of restart.

[0021]

Embodiments of the present invention will be described below with reference to the drawings. First, FIGS. 1 to 4 show a configuration example of a hybrid vehicle to which the present invention can be applied. Each of these is a parallel type hybrid vehicle that travels by using the power of one or both of an engine (internal combustion engine) and a motor (electric motor) according to traveling conditions.

In FIG. 1, a thick solid line indicates a transmission path of mechanical force, and a thick broken line indicates a power line. A thin solid line indicates a control line, and a double line indicates a hydraulic system.

The power train of this vehicle is a motor 1,
It comprises an engine 2, a clutch 3, a motor 4, a continuously variable transmission 5, a reduction gear 6, a differential gear 7, and driving wheels 8.
The output shaft of the motor 1, the output shaft of the engine 2, and the input shaft of the clutch 3 are connected to each other.
, The output shaft of the motor 4 and the input shaft of the continuously variable transmission (or automatic transmission) 5 are connected to each other.

When the clutch 3 is engaged, the engine 2 and the motor 4
Is the propulsion source of the vehicle, and when the clutch 3 is released, only the motor 4 is the propulsion source of the vehicle. The driving force of the engine 2 or the motor 4 is controlled by a continuously variable transmission 5, a reduction gear 6, and a differential gear 7.
Is transmitted to the drive wheels 8 via the The continuously variable transmission 5 is supplied with pressure oil required for shifting from a hydraulic device 9. Hydraulic device 9
The oil pump (not shown) is driven by the motor 10.

The motor 1 is mainly used for starting the engine and generating electricity, and the motor 4 is mainly used for propulsion (power running) and braking (regeneration of deceleration energy) of the vehicle. Motor 1
0 is for driving the oil pump of the hydraulic device 9. Further, when the clutch 3 is engaged, the motor 1 can be used for propulsion and braking of the vehicle, and the motor 4 can be used for starting the engine and generating power. Clutch 3 is a powder clutch,
The transmission torque can be adjusted. The continuously variable transmission 5 is a continuously variable transmission of a belt type, a toroidal type, or the like, and can continuously adjust the speed ratio.

The motors 1, 4, and 10 are driven by inverters 11, 12, and 13, respectively. When a DC electric motor is used for the motors 1, 4, and 10, a DC / DC converter is used instead of the inverter. The inverters 11 to 13 are connected to a main battery 15 via a common DC link 14,
Converts the DC charging power to AC power and
0, and converts the AC power generated by the motors 1 and 4 into DC power to charge the main battery 15. Since the inverters 11 to 13 are connected to each other via the DC link 14, the power generated by the motor during the regenerative operation can be supplied directly to the motor during the power running operation without passing through the main battery 15. it can. As the main battery 15, various batteries such as a lithium-ion battery, a nickel-metal hydride battery, and a lead battery, and an electric double layer capacitor, a so-called power capacitor, are applied.

The controller 16 includes a microcomputer and its peripheral parts, various actuators, and the like. The transmission torque of the clutch 3, the rotation speed and output torque of the motors 1, 4, and 10, the gear ratio of the continuously variable transmission 5, Controls fuel injection amount, injection timing, ignition timing, etc.

As shown in FIG. 2, the controller 16 includes a key switch 20, a select lever switch 21,
Accelerator pedal sensor 22, brake switch 23, vehicle speed sensor 24, battery temperature sensor 25, battery SO
The C detection device 26, the engine speed sensor 27, and the throttle opening sensor 28 are connected. The key switch 20 is
When the key of the vehicle is set to the 0N position or the START position, the vehicle is closed (hereinafter, the switch is turned on or the switch is turned on or off).
N, open circuit is called off or OFF). The select lever switch 21 switches P, Neutral N, Reverse R, and Drive D according to the set position of a select lever (not shown) for switching to any one of the ranges.
One of N, R, and D switches is turned on.

The accelerator pedal sensor 22 detects the amount of depression of the accelerator pedal, and the brake switch 23 detects the state of depression of the brake pedal (at this time, switch on). The vehicle speed sensor 24 detects the running speed of the vehicle,
Battery temperature sensor 25 detects the temperature of main battery 15. The battery SOC detection device 26 detects an SOC (battery charge amount) that is a representative value of the actual capacity of the main battery 15. Further, the engine speed sensor 27 detects the speed of the engine 2, and the throttle opening sensor 28 detects the throttle valve opening of the engine 2.

The controller 16 is also connected to a fuel injection device 30, an ignition device 31, and a variable valve device 32 of the engine 2. The controller 16 controls the fuel injection device 3
0 to control the supply and stop of the fuel to the engine 2 and the fuel injection amount / injection timing.
To control the ignition timing of the engine 2. Further, the controller 16 controls the variable valve operating device 32 to adjust the operation state of the intake and exhaust valves of the engine 2. The controller 16 is supplied with power from a low-voltage auxiliary battery 33.

FIG. 3 shows the engine 2, in which an exhaust passage 35 is provided with a three-way catalyst 36, and the HC in the exhaust gas,
CO is oxidized and NOx is reduced. An oxygen sensor 37 is provided upstream of the three-way catalyst 36, and is supplied from the fuel supply device 30 by the controller 16 so that the air-fuel ratio supplied to the engine 2 matches a predetermined air-fuel ratio (stoichiometric air-fuel ratio). The fuel amount is feedback-controlled. In addition,
Although not shown, the oxygen sensor 37 is provided with a sensor heater, and when the temperature of the oxygen sensor drops even when the engine 2 is stopped while the vehicle is running, the oxygen sensor 37 is provided.
Is heated to maintain the activated state.

However, the feedback control of the fuel supply amount is stopped when the engine is cold or the like, and in such a case, the air-fuel ratio is controlled to be open.

By the way, as described above, the engine 2
It is operated (driven) as needed, but when the vehicle is running at a low speed, decelerating, or temporarily stopped, the supply of fuel is shut off and the operation is stopped. When the engine 2 is restarted after the operation is stopped, the NOx of the catalyst depends on the amount of oxygen accumulated on the three-way catalyst 36 while the engine is stopped.
Since the purification efficiency is reduced, in order to prevent this, in the present invention, control is performed during the restart to temporarily increase the air-fuel ratio corresponding to the accumulated oxygen amount.

The details of this control will be described with reference to the flowcharts of FIGS.

These controls are repeatedly executed at regular intervals.

First, in FIG. 4, it is determined in step S1 whether or not the fuel supply amount is cut. If the fuel is cut, that is, if the engine 2 is stopped, the process proceeds from step S11 to step S13.

In step S11, the output VO2 of the oxygen sensor 37 is set to 0, a lean state is recognized, and in step S12, the intake air amount Qa while the engine is stopped is integrated, and the integrated value SQa is obtained as follows. . That is,
As SQa = SQa + Qa, the intake air amount measured this time is added to the previous value.

The amount of intake air when the engine is stopped is obtained by integrating the output of the intake air sensor. Therefore, when the rotation of the engine is completely stopped, the amount of intake air is zero. When the fuel is cut during deceleration or the like, since the engine is rotating, the intake air amount at that time is integrated. The intake air amount is also integrated when the engine is restarted (until fuel injection is started at the time of cranking). In this way, the amount of oxygen accumulated on the three-way catalyst 36 while the engine is stopped is estimated.

In step S13, the feedback control constant α of the air-fuel ratio feedback control is clamped to a predetermined lean value ALPL #.

If it is determined in step S1 that the vehicle is not in the fuel cut state, the engine speed Ne is reduced to a predetermined idle speed reference value NELMD # in step S2.
If it is equal to or less than the reference value, the process proceeds to step S10 to stop the feedback control of the air-fuel ratio,
The feedback control constant α is set to 1 to perform open loop control.

In step S3, the operating conditions at that time are as follows:
It is determined whether the air-fuel ratio is under the feedback control condition. For example, when the engine cooling water temperature is lower than a predetermined value, the feedback control of the air-fuel ratio is stopped in order to promote warm-up. When the feedback control is stopped, the process proceeds to step S10 as described above.

When the feedback control condition is satisfied, the process proceeds to step S4, and it is determined whether or not the previous operating condition was the fuel cut. If not, the process proceeds to step S9, and the feedback control constant α is calculated based on the oxygen sensor output at that time. This calculation routine is shown in FIG.

In order to calculate the air-fuel ratio feedback control constant based on the output of the oxygen sensor, first, in step S21, the output of the oxygen sensor is read, and further based on the fuel injection pulse width Tp and the engine speed Ne at that time.
Proportion P of feedback control constant set in map
And the integral I are read.

In step S22, it is determined whether the currently read oxygen sensor output is rich or lean. If rich, the process proceeds to step S23 to determine whether the previous oxygen sensor output is rich or lean. If the previous time is rich, the feedback control constant α is set to α = α−I in step S25, and the control constant is set to change the air-fuel ratio toward the lean side.

If it is determined in step S23 that the last time is lean, the process proceeds to step S26, where the feedback control constant α is set to α = α−P, and the control constant is also changed toward the lean side.

On the other hand, if the oxygen sensor output value read this time is lean in step S22,
The process proceeds to 24 to determine whether the previous value is rich or lean.
If the air-fuel ratio is rich, the feedback control constant α is set to α = α + P in step S27, and the control constant is changed so as to direct the air-fuel ratio to the rich side.

If the previous value is lean in step S24, the feedback control constant α is determined in step S28.
Is set to α = α + I, and the control constant is similarly changed toward the rich side.

As described above, when the normal feedback control condition is satisfied, the feedback control constant α is calculated based on the oxygen sensor output at that time.

Next, returning to FIG. 4, in step S4,
When it is determined that the fuel injection has been restarted for the first time this time, the process proceeds to step S5, and corresponds to the proportional amount P of the air-fuel ratio feedback control constant based on the integrated value SQa of the intake air amount integrated while the engine is stopped. A correction value PLCLP is calculated. This is obtained by looking up a table as shown in FIG. 7, and this PLCLP becomes larger as the integrated value of the intake air amount becomes larger.

In step S6, the variable valve device (CVT)
C) The cam operation angle at that time of step 32 is read, and based on this, the correction coefficient KPLVTC is calculated by looking up a table as shown in FIG. When the cam operation angle is at an angle where the intake charging efficiency is small, the basic fuel injection amount is also small, so the degree of enrichment of the air-fuel ratio is relatively small. Therefore, in such a case, the three-way catalyst 36
Assuming that the amount of oxygen storage at
It is necessary to increase the CLP. Therefore, a correction coefficient is obtained in order to perform the correction according to the cam operation angle.

In step S8, the correction value PLCLP proportional to the feedback control constant is corrected as follows.

PLCLP = PLCLP × KPLVTC After setting the feedback control constant in this way,
In step S14, the air-fuel ratio feedback control constant α
Is set as α = α + PLCLP, and a control constant is set such that the air-fuel ratio greatly changes to the rich side.

In step S15, the integrated value SQa of the intake air amount integrated while the engine is stopped is reset to 0, and the flow advances to step S16.

In step S16, the fuel injection amount (pulse width) Ti including the feedback control constant α is calculated as follows.

Ti = Tp × α + Ts where Tp is the basic fuel injection pulse width calculated based on the intake air amount, and Ts is the invalid pulse width of the fuel injection valve.

As described above, the fuel injection pulse Ti corrected at the time of restarting the fuel injection is output, and the control for increasing the air-fuel ratio is performed.

When the fuel injection is restarted, the output of the oxygen sensor 37 immediately before the fuel injection is clamped to the lean value, so that the proportional component of the feedback control constant α rises to the rich side. A value larger than the normal shift value to the rich side is set by the correction value. Therefore, the feedback control constant α greatly swings to the rich side, and the air-fuel ratio becomes deeper than the stoichiometric air-fuel ratio. Thereafter, since the feedback control constant is gradually corrected based on this, the state in which the air-fuel ratio is high continues for a while, and the NOx reduction efficiency in the three-way catalyst 36 during this period can be maintained satisfactorily.

FIG. 6 shows a control for causing the motor 1 driven by the engine 2 to generate electric power so as to absorb the torque in order to reduce the torque shock caused by increasing the air-fuel ratio when the fuel injection of the engine 2 is restarted. Is shown.

In step S31, it is determined whether the correction value PLCLP for the proportionality of the feedback control constant α is set, and if it is set, in step S32, the integrated intake air amount SQa while the engine is stopped is determined. Based on this, a table such as that shown in FIG. 9 is looked up to calculate a torque correction amount initial value Tmothi. Then, in step S33, the motor torque value is set as Tmoth = Tmothi, and this initial value is set, thereby determining the motor torque. The power generation amount increases as the motor torque increases.

In step S31, the correction value PLCL
If it is determined that it is not immediately after the setting of P, the process proceeds to step S34, and the motor torque is gradually reduced. That is, the motor torque Tmoth = Tmoth × K # / Ne
, The motor torque is gradually reduced. Note that K # is a constant,
Ne is the engine speed.

Although the motor 1 is made to generate electric power to absorb the engine torque, it is also possible to reduce the engine torque by retarding the ignition timing to reduce the torque shock.

FIG. 10 shows the relationship between the correction value PLCLP of the feedback control constant and the ignition timing retard amount. As shown in the figure, the larger the correction value, that is, the larger the generated torque at the time of resuming the fuel injection, the larger the retard amount is, and the less the torque shock is.

Next, the overall operation will be described with reference to FIG.

Now, an example will be described in which the vehicle shifts from a constant running speed to a decelerating state, stops as it is, starts running again after a certain stop time has elapsed, and the vehicle speed increases.

When the vehicle shifts to a deceleration state and the supply of fuel is cut off, the engine speed decreases and the clutch is eventually disengaged. In this state, engine rotation is completely stopped. When fuel is supplied and the air-fuel ratio is feedback-controlled, the oxygen sensor output is rich and lean at the stoichiometric air-fuel ratio and the average air-fuel ratio is controlled to the stoichiometric air-fuel ratio. With the stop, the oxygen sensor output outputs a lean value, and the air-fuel ratio feedback control constant α is lean-clamped.

In order to prevent the oxygen sensor 37 from becoming inactive while the engine is stopped, when the temperature drops, the oxygen sensor heater is energized and maintained at the activation temperature or higher.

On the other hand, with the fuel cut of the engine, the integrated value S of the intake air amount from that time to the start of the next start is calculated.
Qa is calculated. The integration of the intake air amount is performed only when the engine is running, and the integrated value remains constant during the stop.

When the vehicle is again started to run by the motor 4 after stopping, the engine 2 is started when a predetermined vehicle speed is reached, and the engine output is added to the driving force. When the fuel injection of the engine 2 is restarted, oxygen is deposited on the three-way catalyst 36 due to the oxygen atmosphere based on the deceleration fuel cut, etc., so that NOx is not sufficiently reduced.

When the fuel injection is restarted, the proportional amount of the control constant α of the air-fuel ratio feedback control is corrected based on the integrated intake air amount while the engine is stopped, and the correction amount is larger than the normal proportional amount P. The value PLCLP is output.

Therefore, the feedback control constant α
The fuel injection amount controlled on the basis of is controlled so that the air-fuel ratio becomes richer than usual, and the air-fuel ratio thereafter is affected by this greatly shifted proportion, and the rich state is maintained for a while. Is done.

As described above, when the fuel injection is restarted, the air-fuel ratio temporarily increases.
The reduction efficiency of x is better maintained than at the beginning of the restart. Also H
With respect to C and CO, favorable oxidation treatment is performed by the presence of excess oxygen in the three-way catalyst 36.

The amount of oxygen that accumulates on the three-way catalyst 36 when the engine is stopped depends on the amount of air that has passed through the three-way catalyst 36 (air that is not combusted instead of exhaust gas). By enriching the air-fuel ratio based on the accumulated air amount, NOx can be appropriately reduced, and fuel is not excessively supplied, so that fuel consumption is not unnecessarily deteriorated.

Further, in this case, since the air-fuel ratio is enriched by correcting the proportional portion of the feedback control constant, the response of the enrichment of the air-fuel ratio is good, and the fuel amount required for NOx reduction reliably when the injection is restarted. Can be supplied.

Further, when the air-fuel ratio is increased when the fuel injection is restarted, the engine torque becomes momentarily excessive.
In this regard, by causing the motor 1 directly connected to the engine 2 to function as a generator and absorbing the torque, the occurrence of torque shock can be avoided amicably. It should be noted that the torque shock can be alleviated by correcting the ignition timing by retarding the ignition timing. This may be performed simultaneously with the driving of the motor 1.

In the above-described embodiment, the integrated value of the intake air amount during the stop of the engine rotation is obtained for the correction value of the air-fuel ratio at the time of re-injection. By using this, the correction value to the rich side can be increased as the stop time becomes longer.

The present invention is not limited to a hybrid vehicle, and can be similarly applied to a vehicle of a type in which the engine is automatically stopped when the vehicle is temporarily stopped and the engine is automatically restarted when the vehicle starts.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram showing a configuration example of a hybrid vehicle to which the present invention can be applied.

FIG. 2 is a block diagram of a controller.

FIG. 3 is a schematic configuration diagram of an engine.

FIG. 4 is a flowchart of a control operation executed by a controller.

FIG. 5 is also a flowchart.

FIG. 6 is also a flowchart.

FIG. 7 is a characteristic diagram showing a relationship between an integrated value of an intake air amount and a proportional correction value of a feedback control constant.

FIG. 8 is a characteristic diagram showing a relationship between a cam operation angle and a correction coefficient.

FIG. 9 is a characteristic diagram showing a relationship between an integrated value of an intake air amount and a motor torque correction amount.

FIG. 10 is a characteristic diagram showing a relationship between a proportional correction value of a feedback control constant and an ignition timing retard amount.

FIG. 11 is an operation explanatory diagram showing a relationship between a fuel injection characteristic at the time of engine stop and restart, and the like.

[Explanation of symbols]

 1, 4 Electric motor 2 Engine 3 Clutch 5 Continuously variable transmission 9 Hydraulic device 10 Motor for generating oil pressure 15 Battery 16 Controller (controller) 20 Key switch 21 Select lever switch 22 Accelerator pedal sensor 23 Brake switch 24 Vehicle speed sensor 25 Battery temperature sensor 26 Battery SOC detection device (capacity detection device) 27 Engine speed sensor 28 Accelerator opening sensor 36 Three-way catalyst 37 Oxygen sensor

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) F02D 13/02 F02D 13/02 G 3G301 17/00 17/00 Q 5H115 29/06 29/06 G 41 / 06 305 41/06 305 41/14 310 41/14 310B 43/00 301 43/00 301E 301Z 301B F02N 11/04 F02N 11/04 D 15/00 15/00 E F02P 5/15 F02P 5/15 E ( 72) Inventor Kintaka Exit 2 Takara-cho, Kanagawa-ku, Yokohama-shi, Kanagawa F-term in Nissan Motor Co., Ltd. FA33 FA36 3G091 AA09 AA14 AA17 AA28 AB03 BA14 CB02 CB05 DA01 DA02 DA03 DB04 DB10 DC01 EA01 EA05 EA16 EA30 FA01 FA06 FA19 FB02 FB10 HA36 3G092 AA01 AA05 AA11 A C02 BA05 BA09 BB10 CB05 DC11 DE01S DG08 EA01 EA02 EA04 EA05 EA06 EA17 EA21 EB02 EC09 FA04 FA17 GA01 GA10 GB02 GB10 HA01Z HA13Z HD05X HD05Z HE01X HE01Z HE08Z 3G093 AA06 AA07 BA01 DA02 BA01 DA02 BA00 EA00 EA04 EA05 EA13 EC02 FA05 FA10 FA11 FB01 FB02 FB05 3G301 HA00 HA01 HA19 JA04 JA25 KA04 KA07 KA16 KB04 LA00 LB02 LC03 MA01 MA12 MA24 NA03 NA08 NC04 ND05 ND13 ND15 NE02 NE12 NE13 NE14 NE23 PE01ZPZPZZ05Z PI16 PI22 PI29 PO17 PU02 PU08 PU22 PU24 PU25 PV02 PV09 QH04 QI04 QN02 RB08 RE04 SE04 SE05 SE08 TB01 TE02 TE03 TE04 TI01 TI10 TO21 TO23

Claims (8)

[Claims] 1. A vehicle comprising an engine and a motor for starting the engine, wherein the engine is automatically stopped at least when the vehicle is temporarily stopped, and the engine is automatically restarted when the vehicle starts moving. A three-way catalyst provided in the passage, a sensor for detecting an exhaust gas component, an air-fuel ratio control means for feedback-controlling an air-fuel ratio to a target value in accordance with the output of the sensor, and stopping and stopping supply of fuel to the engine. Air-fuel ratio control means for temporarily correcting the air-fuel ratio at the time of restart to be higher than a target value in accordance with an integrated value of an intake air amount or a stop time until the engine is started. apparatus. 2. An engine, a clutch interposed in a path for transmitting rotation of the engine to driving wheels, a first motor for rotating the driving wheels, and a second motor for starting up or being driven by the engine to generate power. In a hybrid vehicle including a motor, a battery that stores generated power and supplies power to a second motor, and a controller that controls the engine, the clutch, and the first and second motors,
A three-way catalyst provided in an exhaust passage of the engine, a sensor for detecting an exhaust gas component, air-fuel ratio control means for feedback-controlling an air-fuel ratio to a target value according to the output of the sensor, and stopping supply of fuel to the engine. Air-fuel ratio correction means for temporarily correcting the air-fuel ratio at the time of restart to be higher than the target value in accordance with the integrated value of the intake air amount or the stop time from the start to the restart. Air-fuel ratio control device. 3. The air-fuel ratio correction means according to claim 1 or 2, wherein the proportion of the air-fuel ratio feedback control constant on the rich side at the time of restart is increased according to the intake air amount integrated value or the stop time. Engine air-fuel ratio control device. 4. The engine according to claim 3, wherein said engine has a variable valve operating device and corrects a proportional proportion of said air-fuel ratio feedback control constant in accordance with a cam operating angle of said variable valve operating device when said engine is restarted. An air-fuel ratio control device for an engine as described in the above. 5. The air-fuel ratio control device for an engine according to claim 1, wherein the sensor includes a heater, and heats the sensor so that the sensor temperature does not fall below the activation temperature even when the engine is stopped. 6. The air-fuel ratio control device for an engine according to claim 2, further comprising a restart torque absorbing means for driving the second motor when the engine is restarted and absorbing the engine torque by the drive motor torque. 7. The air-fuel ratio control of an engine according to claim 6, wherein said restart torque absorbing means sets a motor driving torque in accordance with an integrated value or a stop time of said intake air amount or a correction value of an air-fuel ratio. apparatus. 8. An air-fuel ratio control device for an engine according to claim 2, further comprising a restart torque absorbing means for absorbing an engine torque by delaying the ignition timing from a normal control value when the engine is restarted.