JP3203945B2 - Control device for internal combustion engine with automatic transmission - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION This invention relates to a control apparatus for an internal combustion engine with an automatic transmission, air-fuel ratio of the exhaust gas flowing in detail absorbs NO _X in the exhaust gas when the lean, reduced exhaust oxygen concentration a control device for an internal combustion engine with an automatic transmission having an exhaust gas purification apparatus using the _the NO _X absorbent to release the absorbed NO _X when.

[0002]

2. Description of the Related Art As an exhaust purifying apparatus for an internal combustion engine using this type of the NO _X absorbent, International Publication No. WO93-7
No. 363. In the above exhaust gas purifier, the air-fuel ratio of the exhaust flowing absorbs NO _X in the exhaust gas when the lean, NO _X absorbent oxygen concentration in the inflowing exhaust gas to release the absorbed NO _X when lowered It was disposed in an exhaust passage of an internal combustion engine, usually by operating an internal combustion engine at a lean air-fuel ratio to absorb NO _X in the exhaust gas to the _the NO _X absorbent. Further, followed by a lean air-fuel ratio operation, when absorbed amount of NO _X in _the NO _X absorbent exceeds a predetermined amount, switches the operating air-fuel ratio of the internal combustion engine from the short-time lean air-fuel ratio to the rich or the stoichiometric air-fuel ratio Reduce the oxygen concentration in the exhaust
Together to release the absorbed NO _X from _X absorbent, this released NO _X unburned HC in the exhaust gas, in the (herein that so as to reduce and purify by components such as CO, the _the NO _X absorbent The operation of releasing, reducing, and purifying NO _X from the NOx is referred to as “NO _X absorbent regeneration operation”).

[0003] In the apparatus, absorbed in _the NO _X absorbent N
When O _X amount is somewhat increased, by switching the engine operating air-fuel ratio in a short time a rich air-fuel ratio from the lean air-fuel ratio NO
NO _X in _the NO _X absorbent by reproducing the _X absorbent
Absorption is prevented from saturating, it is always maintain a high exhaust gas purification capability of the NO _X absorbent. However, the exhaust gas purifying device as described in the aforementioned International Publication, when regenerating operation of the NO _X absorbent is performed, with the switching of the air-fuel ratio varies the output torque of the engine, the vehicle drive torque fluctuation Will do. Further, in the above exhaust gas purifying apparatus, reproducing operation of the NO _X absorbent, NO _X amount _the NO _X absorbent is absorbed when it becomes more than a predetermined value is carried out independently of the driver's will. Therefore, NO _X when the driver Unexpected
Regenerating operation of the absorbent is performed, will be variation in the drive torque occurs, since the increase in the actual or the felt torque fluctuation of the driver at the time of the regenerating operation of the NO _X absorbent, drivability (riding so-called vehicle Comfort) is deteriorated.

On the other hand, in an internal combustion engine with an automatic transmission having a fluid torque converter, the engine and the drive system are connected via a torque converter, so that even if the above-mentioned sudden change in engine output torque occurs, Fluctuations in the engine output torque are not directly transmitted to the drive system due to the buffering action of the fluid, and fluctuations in the drive torque are reduced. Thus, by providing the exhaust gas purifying apparatus as described above publication to the internal combustion engine with an automatic transmission, it is possible to prevent deterioration in drivability and reduce the drive torque fluctuation of Ji _the NO _X absorbent regenerating operation.

However, when the above-described exhaust gas purifying device is provided in an internal combustion engine with an automatic transmission having a lock-up clutch, the above-described fluid buffering function cannot be obtained when the lock-up clutch is engaged. when _the NO _X absorbent regenerating operation during up clutch engagement is performed, there is a case where deterioration of drivability caused by the drive torque fluctuation.

That is, the lock-up clutch reduces the slip loss of the torque converter by mechanically directly connecting the input shaft (engine output shaft) and the output shaft (transmission input shaft) of the torque converter during high-speed running or the like. Therefore, when the lock-up clutch is engaged (that is, when the engine output shaft and the transmission input shaft are mechanically directly connected), the fluid buffering does not occur and the engine output torque fluctuation does not occur. Is directly transmitted to the drive system. Therefore, when the switching to the rich air-fuel ratio for _the NO _X absorbent reproduced when the lock-up clutch engagement is performed, it is the deterioration of the drivability at the sudden change of the unexpected drive torque of the driver occurs.

By the way, although not targeted at fluctuations in the engine output torque due to switching to the rich air-fuel ratio for the regenerating operation of the _the NO _X absorbent, JP-A-4-16516
Japanese Patent Application Publication No. JP-A No. 0-205139 discloses a control of a lock-up clutch in an internal combustion engine with an automatic transmission having an engine output torque control means other than a throttle valve, wherein the lock-up clutch is released when the engine output torque suddenly changes due to the operation of the control means. A method is described.

In the method disclosed in the above publication, the lock-up clutch is released when the engine output torque suddenly changes, thereby causing a buffer action by the fluid of the torque converter, thereby preventing deterioration of drivability.

[0009]

However, the above-mentioned NO
_In order to prevent drivability from deteriorating due to switching to the rich air-fuel ratio operation at the time of the _X absorbent regeneration operation, lockup is performed at the time of NO _X absorbent regeneration as in the method of JP-A-4-165160. A problem arises when the clutch is released.

That is, engagement of the lock-up clutch,
At the time of the release operation, the drive torque fluctuates in accordance with the change in the engagement state between the engine output shaft and the transmission input shaft. Normally, the engagement and disengagement operations of the lock-up clutch are performed based on a change in the operating state.Therefore, the driver expects to some extent that a change in the driving torque will occur from the change in the operating state. Even in the case where the above-described drive torque fluctuation occurs due to the engagement and release operations, the drivability does not significantly deteriorate.

[0011] However, the regenerating operation of the NO _X absorbent, NO _X amount absorbed even when the operating state does not change from being automatically carried out if increased. Therefore, when the release of the lock-up clutch for each regenerating operation of the NO _X absorbent, when unexpected by the driver, resulting driving torque variation due to the lockup clutch released, resulting in rather drivability deteriorates problem Occurs.

[0012] The present invention has been made in view of the above problems, the lock-up clutch engagement time can prevent deterioration of drivability due to switching to the rich air-fuel ratio for _the NO _X absorbent reproduction is performed in the automatic transmission It is an object of the present invention to provide a control device for an internal combustion engine with an engine.

[0013]

Means for Solving the Problems] According to the present invention described in claim 1, disposed in an exhaust passage of an internal combustion engine for a vehicle, the air-fuel ratio of the exhaust gas absorbs NO _X in the exhaust gas when the lean ,
And _the NO _X absorbent to the oxygen concentration in the exhaust gas to release NO _X absorbed when lowered, NO _X absorption of the _the NO _X absorbent
When There it reaches the value predetermined by switching the air-fuel ratio of the internal combustion engine from a lean air-fuel ratio to a rich air-fuel ratio, the air-fuel ratio switching means for releasing NO _X absorbed from the _the NO _X absorbent, the With an automatic transmission provided with an automatic transmission connected to the internal combustion engine, and a lock-up clutch provided between the input and output shafts of the torque converter of the automatic transmission and bringing the input and output shaft into a directly connected state when engaged. In the control device for the internal combustion engine, a torque change detecting means for detecting a change in engine output torque intended by the vehicle driver, and a change in engine output intended by the vehicle driver is detected while the lock-up clutch is engaged. Prohibits the execution of the rich air-fuel ratio operation by the air-fuel ratio switching means only when the lock-up clutch is engaged. Means for controlling an internal combustion engine with an automatic transmission.

Further, according to the present invention described in claim 2,
NO arranged in an exhaust passage of an internal combustion engine for a vehicle that absorbs NO _X in the exhaust when the air-fuel ratio of the exhaust is lean and releases the absorbed NO _X when the oxygen concentration in the exhaust decreases.
And _X absorbent, by switching to the rich air-fuel ratio of the internal combustion engine when controlling the air-fuel ratio of the internal combustion engine, a predetermined condition is satisfied from the lean air-fuel ratio, the NO _X
And air-fuel ratio switching means for releasing NO _X absorbed from the absorbent, and an automatic transmission connected to the internal combustion engine, provided between the input and output shafts of the torque converter of the automatic transmission, changing the engagement pressure Thereby, the engagement state is continuously performed between the non-engagement state, the half-clutch state in which the input and output shafts are engaged while allowing the rotation difference therebetween, and the fully engaged state in which the input and output shafts are directly connected. the control apparatus for an internal combustion engine with an automatic transmission having a lockup clutch capable of varying the, when a predetermined condition for the NO _X emission is established, the engagement pressure of the lock-up clutch Rockua
Engagement control means for reducing the clutch to a predetermined value at which the half-clutch is in the half-clutch state, and switching to the rich air-fuel ratio by the air-fuel ratio switching means until the lock-up clutch engagement pressure reducing operation by the engagement control means is completed. And a prohibiting means for prohibiting the internal combustion engine.

Further, according to the present invention as set forth in claim 3,
NO arranged in an exhaust passage of an internal combustion engine for a vehicle that absorbs NO _X in the exhaust when the air-fuel ratio of the exhaust is lean and releases the absorbed NO _X when the oxygen concentration in the exhaust decreases.
And _X absorbent, the NO _X absorbed from the _the NO _X absorbent release
By switching the air-fuel ratio of the internal combustion engine when a predetermined condition for executing the regenerating operation is satisfied from the lean air-fuel ratio to a rich air-fuel ratio to the air-fuel ratio to release the NO _X absorbed from the _the NO _X absorbent A switching unit, an automatic transmission connected to the internal combustion engine, and an input / output shaft of a torque converter of the automatic transmission. A lock-up clutch capable of continuously changing the engagement state between a half-clutch state that engages while allowing a rotation difference between the shafts and a full engagement state that directly connects the input / output shaft. The control device for an internal combustion engine with an automatic transmission according to claim 1, wherein said regeneration is performed according to a change in an engagement state of said lock-up clutch.
Condition setting means for changing the predetermined condition for performing the operation , wherein the condition setting means is configured such that as the engagement state of the lock-up clutch approaches the non-engagement state from the full engagement state. To perform the playback operation.
A control device for an internal combustion engine with an automatic transmission , wherein the predetermined condition is relaxed so that the predetermined condition is easily satisfied .

[0016]

According to the first aspect of the present invention, the torque change detecting means is intended to allow the driver to change the engine output torque based on, for example, a change in the accelerator pedal operation amount of the driver (a change in throttle opening). Detect whether or not.
For example, when the rate of change of the amount of depression of the accelerator pedal (throttle opening) exceeds a predetermined value, the driver intends to change (increase or decrease ) the engine output torque, and the driver intends to change the engine output torque. Is determined to occur.

The inhibiting means, when the lock-up clutch engagement only when it is detected that the intended engine output torque change of the driver occurs, the rich for _the NO _X absorbent regeneration by the air-fuel ratio switching means Switching to the air-fuel ratio is permitted. Therefore, when the lock-up clutch engagement, the rich air-fuel ratio operation for _the NO _X absorbent regeneration will be performed only when the engine output torque change the driver's intended results.

As described above, when the driver does not expect to drive,
Drivability is greatly deteriorated when dynamic torque fluctuations occur
However, if the driver is expecting drive torque fluctuations,
Deterioration of drivability is small even if drive torque fluctuations occur
Absent. Therefore, the driving torque fluctuation expected by the driver is
Occurs at the same time as NO_XLid for absorbent regeneration
Lock-up by executing the switch to the air-fuel ratio
NO during clutch engagement _XWhen the absorbent regeneration operation is performed
However, drivability does not deteriorate due to torque fluctuation.
No.

According to the present invention, the lock-up clutch is continuously engaged between a fully engaged state in which the input / output shaft is directly connected and a non-engaged state in which the input / output shaft is separated. It is possible to change the state, and there is a half-clutch state in which the clutch slippage changes according to the change in the engagement pressure between the fully engaged state and the disengaged state. The engagement control means reduces the clutch engagement pressure to a predetermined value when a condition for releasing NO _X from the NO _X absorbent is established, so that the lock-up clutch is brought into a predetermined half-clutch state. The prohibiting means prohibits the air-fuel ratio switching means from switching to the rich air-fuel ratio until the engagement pressure decreases to the predetermined value. Therefore, switching to the rich air-fuel ratio for releasing NO _X from the NO _X absorbent is performed after the lock-up clutch is in the half-clutch state.

In the half-clutch state, slippage occurs in the clutch, so that fluctuations in engine output torque due to switching to the rich air-fuel ratio are less likely to be transmitted to the drive shaft than in full engagement. In addition, when the clutch engagement pressure is reduced to the half-clutch state as compared with the case where the clutch is completely disengaged, the drive torque fluctuation due to the change in the engagement state of the lock-up clutch is reduced. Therefore, the NO _X release operation from _the NO _X absorbent, the driving torque variation due to the operation of the lock-up clutch is reduced, deterioration in drivability is reduced.

According to the third aspect of the present invention, the lock-up
The clutch is fully engaged similarly to the second aspect of the invention.
Between the engaged state and the disengaged state according to the change in the engagement pressure.
Can take a half-clutch state where the amount of latch slip changes
Noh. Further, the condition setting means may be NO_XAbsorbent
The execution condition of the regeneration operation is determined by the engagement state of the lock-up clutch.
Relaxes from fully engaged to disengaged
And NO _XMeasured to expand the range of conditions for the execution of absorbent regeneration
Change line conditions. On the other hand, engagement of the lock-up clutch
As the condition approaches the disengaged condition, the lock-up
The engine output torque fluctuates because the
It is difficult to transmit to the drive train,
Deterioration of evanability is reduced.

For this reason, by changing the conditions for executing the NO _x absorbent regeneration operation as described above, the opportunity to execute the regeneration operation of the NO _x absorbent is increased in an area where the influence on the drivability is small. together with the playback operation of the NO _X absorbent is sufficiently performed without deterioration of the drivability, in the region high-impact given to drivability decreases the chance that the regenerating operation of the NO _X absorbent is performed, the reproduction operation Deterioration of drivability due to execution is prevented.

[0023]

Embodiments of the present invention will be described below with reference to the accompanying drawings. FIG. 1 is an overall view of an internal combustion engine with an automatic transmission to which the present invention is applied. In FIG. 1, reference numeral 1 denotes an internal combustion engine such as a gasoline engine that performs combustion at a lean air-fuel ratio, and 3 denotes an engine 1.
, 6 indicates an intake port of the engine, and 8 indicates an exhaust port. Each intake port 6 is connected to a surge tank 10 via an intake branch pipe 9, and each branch pipe 9 is provided with a fuel injection valve 11 for injecting fuel into each intake port 6.

The surge tank 10 is connected to an air cleaner 13 through an intake passage 12, and a throttle valve 14 having an opening corresponding to the operation of an accelerator pedal (not shown) by a driver is provided in the intake passage 12. Are located. Also,
The surge tank 10 is provided with an intake pressure sensor 15 that generates an output voltage proportional to the absolute pressure in the surge tank 10.

On the other hand, the exhaust port 8 of the engine 1 is connected to an exhaust passage 17 via an exhaust manifold 16, and a casing 19 containing a NO _X absorbent 18 described later is connected to the exhaust passage 17. Also, what is indicated by 40 in FIG. 1 is an automatic transmission connected to an output shaft (not shown) of the engine 1. The automatic transmission 40 includes a torque converter 41
And a transmission 42. The output shaft of the transmission 42 is connected to driving wheels of the vehicle via a differential gear (not shown).

The transmission 42 is of a known type having a planetary gear train and a friction element, and switches the control oil pressure to switch the engagement state of the friction element (brake, clutch, etc.) to change each of the planetary gear trains. The gear shifting operation is performed by fixing and connecting the elements. The torque converter 41 is of a known type including a pump directly connected to an engine output shaft and a turbine driven by the pump discharge fluid. Directly connected to the input shaft. The torque converter 41 has a known torque amplifying function of amplifying torque input from the engine output shaft and outputting the amplified torque to the converter output shaft. Further, the torque converter 41 is provided with a lock-up clutch that directly connects the engine output shaft (pump impeller) and the converter output shaft (turbine) under predetermined conditions to reduce slip loss of the torque converter. In addition, the automatic transmission 4
0 is a converter output shaft rotation speed sensor 2 that outputs a pulse signal having a frequency corresponding to the rotation speed of the converter output shaft.
2. A transmission output shaft rotation speed sensor 23 that outputs a pulse signal having a frequency corresponding to the rotation speed of the output shaft of the transmission 42 is provided.

In FIG. 1, reference numeral 30 denotes an electronic control circuit of the engine 1. The electronic control circuit 30 includes a ROM (Read Only Memory) 32, a RAM (Random Access Memory) 3
3, CPU (microprocessor) 34, input port 3
5. A digital computer having a known configuration in which the output ports 36 are connected to each other by the bidirectional bus 31,
In addition to performing basic control of the engine such as fuel injection amount control and ignition timing control of the engine 1, shift control of the automatic transmission 40, control of a lock-up clutch, and the like, in the present embodiment, NO _X is described in claim 1. Air-fuel ratio switching means for switching the engine operation air-fuel ratio to the rich air-fuel ratio for regeneration of the absorbent 18, torque change detection means for detecting a change in engine output torque intended by the driver, prohibition means for inhibiting the rich air-fuel ratio operation, also plays a role as the means such condition setting means for changing _the NO _X absorbent regenerating operation condition in accordance with the engagement state of the lock-up clutch.

For the above purpose, a voltage signal corresponding to the intake pressure from the intake pressure sensor 15 and a voltage signal representing the opening of the throttle valve 14 from the throttle opening sensor 20 are provided to the input port 35 of the control circuit 30. Further, voltage signals representing the vehicle running speed are output from the vehicle speed sensor 24 to the AD converters 3 respectively.
7, a pulse signal indicating the engine speed from an engine speed sensor 21 provided in a distributor (not shown) of the engine, and the above-described converter output shaft speed sensor 22 and the transmission. Output shaft speed sensor 2
3 are respectively input.

The output port 36 of the control circuit 30
The fuel injection valve 11 is connected via the corresponding drive circuit 38.
And the ignition plug 4, and controls the fuel injection from the fuel injection valve 11 and the ignition timing of the engine. _The NO _X absorbent 18 built in the casing 19, for example using a carrier such as alumina, alkali metal, such as the carrier on, for example, potassium K, sodium Na, lithium Li, cesium Cs, barium Ba, calcium Ca At least one selected from alkaline earths, rare earths such as lanthanum La and yttrium Y, and a noble metal such as platinum Pt are supported. NO _X when the air-fuel ratio of the _the NO _X absorbent 18 is inflowing exhaust is lean
Absorb NO and release NO _X when the oxygen concentration decreases
_X absorbs and releases.

The above-mentioned exhaust air-fuel ratio is defined as N
O _X absorbent 18 upstream of the exhaust passage and the engine combustion chamber is intended to mean the ratio of the sum of the sum and fuel respectively to the intake passage or the like supplied air quantity. Therefore, NO _X absorbent 1
When no fuel or air is supplied to the upstream exhaust passage 8, the exhaust air-fuel ratio becomes equal to the air-fuel ratio of the engine (air-fuel ratio in combustion in the engine combustion chamber).

In this embodiment, since an engine that performs combustion at a lean air-fuel ratio is used, the exhaust air-fuel ratio during normal operation is lean, and the NO _X absorbent 18 absorbs NO _{X in} the exhaust gas. Further, when the air-fuel ratio of the engine is the oxygen concentration in the exhaust gas is switched from the lean air-fuel ratio to the rich or the stoichiometric air-fuel ratio decreases, NO _X absorbent 18 performs the release of the absorbed NO _X.

The detailed mechanism of the absorption / release action is not clear in some parts. However, it is considered that this absorption / release action is performed by a mechanism as shown in FIG. Next, regarding this mechanism, platinum P
The case where t and barium Ba are supported will be described as an example, but other noble metals, alkali metals, alkaline earths,
The same mechanism is obtained even when rare earth elements are used.

That is, the inflow exhaust gas becomes considerably lean.
And the oxygen concentration in the inflow and exhaust gas greatly increased, as shown in Fig. 2 (A).
These oxygen O_TwoIs O_Two ^-Or O^2-In the form of
It adheres to the surface of platinum Pt. On the other hand, NO in the inflow exhaust gas is
This O on the surface of platinum Pt_Two ^-Or O^2-Reacts with N
O_Two(2NO + O_Two→ 2NO_Two ). Then generated
NO_TwoSome of the oxygen is oxidized on platinum Pt and
FIG. 2 shows that while being absorbed by and combined with barium oxide BaO.
As shown in (A), nitrate ion NO_Three ^-Absorbent in the form of
Spreads in. NO in this way_XIs NO_XAbsorbent 1
8 is absorbed.

Accordingly, as long as the oxygen concentration in the inflowing exhaust gas is high, NO ₂ is generated on the surface of the platinum Pt, and as long as the NO _x absorption capacity of the absorbent is not saturated, NO ₂ is absorbed in the absorbent and nitrate ions NO ₃ ^- is generated. Institution 1
When the air-fuel ratio is switched to rich or stoichiometric,
The oxygen concentration in the inflow exhaust gas decreases, and the amount of generated NO ₂ decreases. As a result, the reaction proceeds in the reverse direction (NO ₃ ⁻ → NO ₂ ), and nitrate ions NO ₃ ⁻ in the absorbent are released from the absorbent in the form of NO ₂ . On the other hand, unburned HC,
When components such as CO are present, these components are oxidized by reacting with oxygen O ₂ ^- or O ^2-on platinum Pt,
Consume the above oxygen. Further, NO ₂ released from the NO _X absorbent 18 is reduced by reacting with HC and CO as shown in FIG. 2 (B). In this way, N on the surface of platinum Pt
When the O ₂ is no longer present, NO _{2 is} successively removed from the absorbent.
Is released.

[0035] That is, HC in the inflowing exhaust gas, CO, first O ₂ on the platinum Pt ^- immediately react with oxidized or O ^2-, and then on the platinum Pt O ₂ ^- or O ^2- is consumed the HC, NO _X flowing into NO _X released from the absorbent by CO, and with the exhaust gas is reduced even yet HC, any remaining CO is. In this embodiment, during normal lean-burn operation using the above together to absorb NO _X in the exhaust gas in the NO _X absorbent, short engine air when the absorbed amount of NO _X in _the NO _X absorbent is increased by switching the ratio to the rich or the stoichiometric air-fuel ratio is performed and reduction purification and release of the NO _X from _the NO _X absorbent. That is,
When the engine air-fuel ratio is switched to the rich or stoichiometric air-fuel ratio, the oxygen concentration in the exhaust gas rapidly decreases, and the amount of unburned HC and CO discharged from the engine increases significantly.
Therefore, by switching the engine air-fuel ratio to a rich or stoichiometric air-fuel ratio, the oxygen concentration in the exhaust gas is reduced, and the amount of unburned HC and CO is increased, so that N
The regeneration of the _OX absorbent 18 will be performed.

Next, the air-fuel ratio control of the engine according to the present embodiment will be described. In the present embodiment, the aforementioned International Publication No. WO
The same air-fuel ratio control as described in No. 93-7363 is performed. Hereinafter, the air-fuel ratio control will be briefly described. In the present embodiment, the fuel injection amount from the fuel injection valve 11
That is, the valve opening time (fuel injection time) TAU of the fuel injection valve 11 at the time of fuel injection is determined by the control circuit 30 by, for example, TA
It is calculated as U = TP × K.

Here, TP indicates a fuel injection time required to make the air-fuel ratio of the air-fuel mixture supplied to the engine combustion chamber a stoichiometric air-fuel ratio, that is, a basic fuel injection time, and is detected by the intake pressure sensor 15. As a function of the measured absolute pressure PM in the surge tank 10 and the engine speed N, it is obtained in advance through experiments or the like, and stored in the ROM 32 of the control circuit 30 in the form of a numerical table as shown in FIG.

K is a correction coefficient for controlling the engine air-fuel ratio. When K = 1.0, the engine air-fuel ratio becomes the stoichiometric air-fuel ratio. If K> 1.0, the engine air-fuel ratio becomes smaller than the stoichiometric air-fuel ratio (ie, rich air-fuel ratio). If K <1.0, the engine air-fuel ratio becomes larger than the stoichiometric air-fuel ratio (ie, lean air-fuel ratio). To the fuel ratio). The value of the correction coefficient K is given as a function of the absolute pressure PM in the surge tank 10 and the engine speed N, for example, as shown in FIG. That is, as shown in FIG. 4, in the present embodiment, the region where the PM is relatively low (engine low-medium load operation region).
, The correction coefficient K is set smaller than 1.0, and the engine is operated at a lean air-fuel ratio. In a region where the PM is relatively high (engine high load operation region), the value of the correction coefficient K is set to 1.0, and the engine is operated at the stoichiometric air-fuel ratio. Also, PM
Is high (engine full load operation range), the value of the correction coefficient K is set to be larger than 1.0, and the engine is operated at a rich air-fuel ratio. In a vehicle engine or the like, the low-medium load operation is usually performed most frequently, so that these engines are operated at a lean air-fuel ratio during most of the operation.

[0039] As described above, NO NO _X absorbent engine absorbs NO _X in the exhaust gas when being operated at a lean air-fuel ratio, the engine is absorbed when being operated at a rich or stoichiometric air-fuel ratio _X Release. Therefore, if the operation of the rich or the stoichiometric air-fuel ratio is appropriately performed, NO _X absorption of the NO _X absorbent is not increased beyond a certain level, it is not necessary to perform special reproduction operation. However, when the engine operating conditions which may operated at a lean air-fuel ratio such that long-lasting, NO _X absorption of the NO _X absorbent increases,
There is a possibility that the NO _x absorption capacity may be saturated.

[0040] Therefore, the electronic control circuit 30 in the present embodiment estimates the amount of NO _{X the} NO _X absorbent 18 is absorbed, when the estimated NO _X absorption amount becomes a predetermined amount or more, though the area of FIG. 4 not, short (e.g., time of about 0.5 to 1 second) driving the forcibly set to the engine a value of the correction coefficient K to 1.0 or rich or stoichiometric air-fuel ratio, of the NO _X absorbent NO _X absorbing capacity of the NO _X absorbent by performing reproduction operation is prevented from saturating.

Next, a description will be given of an embodiment of the estimation method of the NO _X absorption of the _the NO _X absorbent. Electronic control circuit 30 in this embodiment, in accordance with the engine operating state at predetermined time intervals, addition of the absorption amount counter representing the NO _X absorption of _the NO _X absorbent 18, by performing the subtraction, the absorption counter It estimates the NO _X absorption of the NO _X absorbent 18 from the value. That is, _the NO _X absorbent 18 when the engine is operated at a lean air-fuel ratio carried out absorption of the NO _X in the exhaust gas, NO _X absorption of the NO _X absorbent 18 increases. NO to _the NO _X absorbent 18 is absorbed per unit this time period
_X amount is considered to be proportional to the amount of the NO _X discharged per unit time from the engine. On the other hand, the amount of the NO _X discharged per unit time from the engine is determined by the engine load conditions, such as the engine load (the engine intake pressure) is higher, also it increases the higher the engine speed. Therefore, in the present embodiment, the NO _X emission amount of the engine is obtained in advance by actual measurement or the like as a function of the engine load and the number of revolutions, and a value obtained by multiplying the NO _X emission amount by a constant coefficient is determined as the NO _X absorbent as of the NO _X absorption, it is stored in the form of a numerical table of the same format as FIG. 3 in ROM32 of the electronic control circuit 30. When the the engine is operated at a lean air-fuel ratio, an electronic control circuit 30 calculates the NO _X absorption amount per unit time by using the numerical table from every predetermined time, the engine load (the intake air pressure) the engine speed and Then, it is added to the value of the above-mentioned NO _X absorption amount counter.

Further, when the engine is operated in a rich or stoichiometric air-fuel ratio, NO _X absorbent 18 is absorbed N
To release O _X, NO _X absorption of the NO _X absorbent 18 is reduced. Therefore, in this embodiment, the electronic control circuit 30
When the engine is operated in a rich or stoichiometric air-fuel ratio, performs an operation of subtracting the constant value corresponding to the NO _X release amount per unit from the value of the NO _X absorption counter time at predetermined time intervals.

Thus, the above-mentioned NO_XAbsorption counter
Is always NO_XNO of absorbent 18 _XCorresponding to the amount of absorption
Value_XNO from the value of the absorption counter_XSucking
NO for collector 18_XThe amount of absorption can be estimated.
FIG. 5 is executed by the electronic control circuit 30 at regular intervals.
NO above_XShows the flowchart of the absorption amount estimation routine
You.

When the routine starts in FIG.
In step 501, the engine intake pressure PM and the engine speed N are input from the intake pressure sensor 15 and the engine speed sensor 21, respectively. In step 503, the current lean air-fuel ratio operation is performed based on the value of the air-fuel ratio correction coefficient K described above. It is determined whether or not it has been performed. If it is determined in step 503 that the lean air-fuel ratio operation is currently being performed (K <1.0), the process proceeds to step 505, in which the numerical value table stored in the ROM 32 using the intake pressure PM and the engine speed N is used. , The NO _x absorption amount α of the NO _x absorbent per unit time is calculated, and then in step 507, the NO _x absorption amount counter C
Is added to the value of, and the routine ends in step 511.

If it is determined in step 503 that the rich or stoichiometric air-fuel ratio operation is currently being performed (if K ≧ 1.0), the process proceeds to step 509, where the value of the NO _x absorption counter C per unit time is calculated. The constant value β corresponding to the NO _X release amount is subtracted, and the routine ends in step 511. Although this embodiment is NO _X emissions β from _the NO _X absorbent per unit time is a constant value, the engine air-fuel ratio (K), the value of β in accordance with the engine load condition (PM, N) It may be changed.

Next, the shifting operation of the automatic transmission according to the present embodiment will be described. In this embodiment, the shift operation of the automatic transmission 40 is performed based on the vehicle traveling speed and the throttle opening. That is, the electronic control circuit 30 inputs the vehicle running speed and the throttle opening from the vehicle speed sensor 24 and the throttle opening sensor 20, respectively, and performs a shifting operation based on these values. FIG. 6 is a shift characteristic diagram showing an example of the relationship between the vehicle running speed, the throttle opening, and the shift operation.
FIG. 6 shows shift characteristics of an automatic transmission having an overdrive (OD) mechanism and three-stage gears. FIG. 6 shows the throttle opening TA and the horizontal axis shows the vehicle running speed SP, respectively. Indicates the timing of shifting from a low gear to a high gear (shift up), and the dotted line indicates the timing of shifting from a high gear to a low gear (shift down). In FIG. 6, a hatched area indicates an area where the lock-up clutch is engaged and the engine output shaft and the converter output shaft are directly connected to operate. As mentioned above, the torque converter consists of a pump impeller (input shaft) and a turbine (output shaft).
Are connected by fluid action to transmit power, and a torque amplifying action is generated due to a difference (slip) in rotation speed between the pump impeller and the turbine. However, in the torque converter, a power transmission loss (slip loss) occurs due to the slip. For this reason, a lock-up clutch for mechanically connecting the pump impeller and the turbine is provided, and in an operation region where the torque amplifying action of the torque converter is not so much required (for example, during high-speed, medium-load or light-load steady operation). The slip loss is reduced by directly engaging the pump impeller and the turbine by engaging the lock-up clutch.

When the lock-up clutch is disengaged, the input / output shaft of the torque converter is connected via the fluid, so that the fluctuation of the engine output torque is attenuated by the buffer action of the interposed fluid, and The torque fluctuation (driving torque fluctuation) of the output shaft is relatively small, but when the lock-up clutch is engaged, the input / output shaft is mechanically directly connected. To be transmitted. For this reason, when the above-mentioned NO _X absorbent regeneration operation is performed when the lock-up clutch is engaged, a problem arises in that the drivability deteriorates due to the fluctuation of the driving torque.

Next, an embodiment corresponding to claim 1 of the present invention will be described with reference to FIG. In the present embodiment, for example, the electronic control circuit 30 monitors a change in the accelerator pedal depression amount of the driver (a change in the opening of the throttle valve).
When the lock-up clutch is engaged (the input / output shaft is mechanically directly connected), the throttle opening change rate (change speed)
There has been so to allow switching to the rich air-fuel ratio for the regeneration of the NO _X absorbent only when it becomes a predetermined value or more.

When the rate of change of the throttle opening is equal to or more than a predetermined value, that is, when the driver steps on or returns the accelerator at a certain speed or more, the driver accelerates (increases driving torque) or decelerates (driving torque) exceeding a certain speed. Decrease)
Is meant. Therefore, in this state, the driver expects that the driving torque will change next. NO _X when lock-up clutch is engaged
When the engine output torque fluctuates due to the execution of the absorbent regeneration operation, the torque fluctuation is directly transmitted to the drive system, so that the driving torque fluctuates. However, the driver expects the driving torque fluctuation as described above. In this case, even if the driving torque fluctuates, the drivability is hardly deteriorated. In this embodiment, when the lock-up clutch engagement, by executing only _the NO _X absorbent regenerating operation when intended engine output variation of the driver occurs, so as to prevent deterioration in drivability.

FIG. 7 shows a flowchart of a routine for the above control executed by the electronic control circuit 30 at regular intervals. In FIG. 7, when the routine starts, in step 701, the throttle opening TA is read from the throttle opening sensor 20, and in step 703, the throttle opening TA _OLD at the time of the previous execution of the routine and the value of TA read above are compared. , The throttle opening change amount DLTA from the previous execution of the routine is calculated (that is, DLTA = | TA−TA _OLD |), that is, DL
TA is a parameter representing the amount of change in the throttle opening during a certain period of time (change rate of the throttle opening TA).

[0051] At step 705, the value of the NO _X absorption counter C that is calculated by the routine of FIG. 5 whether or not a predetermined value C ₀ or more is determined. If NO _X absorption amount of the NO _X absorbent is small, i.e. C <C ₀ at step 705
Since there is no need of regenerating operation of the NO _X absorbent in the case of,
Proceeding to step 707, the flag F is reset (= 0) and the routine ends. When the flag F is reset,
In a separately executed fuel injection control routine, the value of the correction coefficient K is determined based on the relationship in FIG.

In this embodiment, the value of C ₀ is, for example,
It is set to about 70% of the maximum NO _X amount that the NO _X absorbent 18 can absorb. Further, when NO _X absorption amount is large,
That is, when C ≧ C ₀ , the process proceeds to step 709,
It is determined whether the lock-up clutch is engaged. Here, whether or not the lock-up clutch is engaged may be determined from FIG. 6 based on, for example, the throttle opening TA and the vehicle traveling speed SP, or the engine output detected by the rotation speed sensor 21. The determination may be made based on whether or not the difference between the shaft rotation speed (ie, the torque converter input shaft rotation speed) and the torque converter output shaft rotation speed detected by the rotation speed sensor 22 is equal to or greater than a predetermined value.

At step 709, the lock-up clutch
Is released (for example, torque converter input / output)
If the difference in the number of rotations of the power shaft is equal to or greater than the predetermined value), the routine
Proceeding to step 713, the flag F is set (= 1).
You. Here, when the flag F is set, it is executed separately.
In a fuel injection control routine not shown in FIG.
Regardless of the area, a short time (for example, about 0.5 to 1 second)
Interval) When the value of the air-fuel ratio correction coefficient K is set to K> 1.0,
A rich air-fuel ratio operation of the Seki is performed, whereby NO _Xabsorption
NO from agent_XRelease and reduction purification are performed. Also on
After the recording time has elapsed, NO_XThe value of the absorption counter C is
At the same time, the flag F is reset.

In step 709, the lock-up
If the latch was engaged, then step 7
In step 11, the throttle opening change amount DLTA is set to a predetermined value A.
It is determined whether or not this is the case. Here, when DLTA ≧ A
In some cases, the driver is expecting engine power fluctuations and
NO when the clutch is engaged_XPerform the absorbent regeneration operation
However, since the deterioration of drivability is small, the routine is
Proceeding to step 713, the flag F is set. Also,
If DLTA <A, the driver expects engine output fluctuation
And the lock-up clutch is engaged and NO_XSucking
Drivability may deteriorate when regenerating the absorbent.
Therefore, the process proceeds to step 707, where the flag F is reset.
NO _XThe regeneration operation of the absorbent is not performed.

According to the above-described routine, in this embodiment, when the lock-up clutch is released, NO _X
NO _X absorption amount of the absorbent is regenerated operation of the NO _X absorbent becomes more than a predetermined value is performed, during engagement of the lock-up clutch, when the driver does not expect the engine output fluctuation NO _X absorption of the absorbent is not less than a predetermined value, and the driver so that the reproducing operation only _the NO _X absorbent when you are expecting engine output variation is performed. Therefore, deterioration in drivability can be prevented by the regenerating operation of the NO _X absorbent according to the present embodiment.

In addition, the engagement of the lock-up clutch
Engagement of the release or the like, depending on the running state is intended to be suitable engagement is controlled so as to obtain the engagement state of the lock-up clutch for the regenerating operation of the NO _X absorbent Changing the value may not be preferable in maintaining the optimum running state. However, according to this embodiment, due to the regenerating operation of the NO _X absorbent, since it is not necessary to change the engagement state of the lock-up clutch, without disturbing the lockup clutch control according to the running state N
Performs O regenerating operation of the _X absorbent, yet it is possible to reduce the deterioration of the drivability.

Next, an embodiment of the present invention will be described. In the above-described embodiment, the lock-up clutch is controlled to either the disengaged state or the engaged state that directly connects the input / output shaft, and the control for maintaining the intermediate state therebetween is not performed. However, the lock-up clutch presses the friction material (clutch) connected to the turbine with the hydraulic pressure on the inner surface of the front cover connected to the pump impeller (to be precise, the difference in hydraulic oil acting on both sides of the clutch). In order to perform the engagement operation (by pressing the clutch against the front cover by pressure), by controlling this differential pressure, the engagement pressure of the lock-up clutch is controlled to bring the engagement state into the intermediate state described above. It is possible to maintain. That is, by controlling the differential pressure in accordance with the vehicle running conditions, the lock-up clutch is completely engaged (the input / output shaft is mechanically directly connected and there is no difference in the number of rotations), and the lock-up clutch is not engaged (the on-state is not engaged). (The output shaft is connected only by the action of the fluid) and the lock-up clutch is engaged in a state where the rotation speed of the input / output shaft is different, that is, the clutch is slipped and engaged. The operation can be performed in a so-called half-clutch state.

In the clutch slip state, the power is transmitted by both the clutch and the fluid,
It is possible to obtain a certain amount of torque amplifying action of the torque converter while keeping the slip loss of the torque converter relatively small. (In this specification, the control for engaging the lock-up clutch in a slid state will be described. This is referred to as “slip control of a lock-up clutch.” As a method of the slip control of the lock-up clutch, for example, there is a method described in Japanese Patent Application Laid-Open No. Hei 4-203561. In the device disclosed in the publication, the differential pressure is controlled so that the rotational speed difference (slip amount) of the input / output shaft of the torque converter becomes a target slip amount determined by operating conditions (for example, engine speed and throttle opening). , The slip control of the lock-up clutch is performed.

Also in the present embodiment, the control circuit 30 performs the slip control of the lock-up clutch by the same method as in the above-mentioned Japanese Patent Application Laid-Open No. 4-203561. Hereinafter, this control method will be briefly described. In this embodiment, the engagement pressure of the lock-up clutch, that is, the differential pressure of the working oil acting on both sides of the clutch is adjusted by controlling the opening of a differential pressure control valve provided in the hydraulic circuit. The opening degree DSLU of the differential pressure control valve is DSLU = DFWD + KGD + D, as shown below, as a sum of three terms of a feed forward term DFWD, a learning term KGD, and a feedback term DFB.
Expressed as FB.

Here, DFWD is a parameter determined from the engine speed (torque converter input shaft speed) NI and the throttle opening TA (engine generated torque).
It is stored in the ROM 32 of the control circuit 30 as a numerical table using I and TA. Further, KGD is a learning value for compensating for a steady deviation due to deterioration of hydraulic oil, variation in product characteristics, etc., and DFB is a target slip amount TSLP of the torque converter and an actual slip amount (torque converter input shaft and output shaft). Speed difference from SLP) difference from SLP (TS
This is a feedback amount determined by PID (proportional, integral, differential) control based on LP-SLP. The target slip amount TSLP is set in advance to a value at which optimal drivability and fuel efficiency are obtained, for example, according to the engine speed NI and the throttle opening TA, that is, according to the engine output shaft speed and the generated torque. As with DFWD above, N
It is stored in the ROM 32 as a numerical table using I and TA.

The control circuit 30 reads the feedforward amount DFWD from the engine speed NI and the throttle opening TA using a numerical table stored in the ROM 32,
Similarly, the target slip amount TSLP is determined from NI and TA, and the feedback amount DFB is calculated from the deviation between the target slip amount TSLP and the actual slip amount SLP. Next, DFWD and DFB are added, and a value obtained by adding the learning amount KGD is output as the differential pressure control valve opening DSLU.

The learning amount KGD is increased or decreased so that the value of the feedback amount DFB in the steady state approaches zero. With the above control, the differential pressure control valve opening DSLU in each operation state is controlled to a value determined by the feedforward amount DFWD corrected by the learning amount KGD, and only the change in the DSLU when the operation state changes is the target slip. Based on the deviation between the amount TSLP and the actual slip amount SLP, control is performed by the feedback amount DFB.

[0063] In this embodiment, the control circuit 30, when performing switching to a rich air-fuel ratio for the regeneration of the NO _X absorbent during the lock-up clutch engagement, firstly, reduce the differential pressure of the clutch hydraulic oil ( That reduces the engaging pressure of the clutch) to increase the slip amount to a predetermined value, for switching to the rich air-fuel ratio operation for regeneration of the NO _X absorbent thereafter. Lock When up clutch slip control, since the higher the engine output fluctuation slip amount is large hardly appears as a drive torque fluctuation, deterioration in drivability due to a driving torque fluctuation by increasing the amount of slip during _the NO _X absorbent regeneration Is prevented from occurring.

[0064] Figure 8 is a flowchart showing the control of the lock-up clutch during the changeover to the rich air-fuel ratio for _the NO _X absorbent regeneration. This routine is executed by the control circuit 30 at regular intervals. When the routine starts in FIG. 8, in step 801, the engine speed (torque converter input shaft speed) NI and the throttle opening TA are read from the sensors 21 and 20, respectively. Also, then in step 803, the need for the regenerating operation of the NO _X absorbent from the value similarly NO _X absorption amount counter C and the embodiment of FIG. 7 is determined.

In step 803, the NO _x absorption amount is small,
When it is not necessary to execute the NO _X absorbent regeneration operation, the routine proceeds to step 805, and the flag F is reset. The function of the flag F is the same as in the embodiment of FIG. Next, in step 807, step 8
The target slip amount TSLP of the slip control is determined from the numerical table stored in the ROM 32 using the values of N and TA read in step 01, and the above-described slip control is executed in step 821. That is, when there is no need to perform the regenerating operation of the NO _X absorbent, the slip control of the usual lock-up clutch is performed based on the target slip amount TSLP determined from operating conditions.

[0066] On the other hand, if NO _X absorption amount is large in step 803, that is, if the regenerating operation of the NO _X absorbent is required, at step 811, the limit slip required for _the NO _X absorbent regenerating operation The quantity SLPL is calculated. Here, if the limit slip amount SLPL is carrying out the rich air-fuel ratio switching for _the NO _X absorbent regeneration, slip amount required to change the engine output to alleviate that is transmitted to the drive shaft The value is stored in advance in the ROM 32 of the control circuit 30 as a numerical table using the engine speed NI and the throttle opening TA. The limit slip amount SLPL is determined according to the engine speed NI and the throttle opening TA because, for example, when the engine is operated at a high speed and a high load, the engine is switched to a rich air-fuel ratio. This is because the output torque fluctuation also increases, and the slip amount required to reduce the output torque fluctuation of the drive shaft becomes larger than in the low rotation and low load state.

Next, at step 813, it is determined whether or not the currently set target slip amount TSLP of the slip control is smaller than the limit slip amount SLPL determined at step 811. If a TSLP <SLPL, since being set slip is small, the torque fluctuation of the drive shaft and to perform the reproducing operation of the NO _X absorbent in this state is considered to increase, the flow proceeds to step 815, target slip The amount TSLP is set to be larger by the predetermined amount SL, the flag F is reset (= 0) in step 817, and the slip control in step 821 is executed.

In step 813, TSLP ≧ SL
If was PL is the target slip amount set in step 809 TSLP or target slip amount TSLP that is increased in step 815 is sufficiently large, perform the regenerating operation of the NO _X absorbent in this state However, since the torque fluctuation of the drive shaft is considered to be sufficiently small, the flag F is set (= 1) in step 819, and then the process proceeds to step 821 to execute the slip control.

That is, by executing the above routine, N
O_XIf there is no need to perform absorbent regeneration
Slip control is executed (from step 803 to step
807), NO_XIt is necessary to perform an absorbent regeneration operation.
The lock-up clutch every time the routine is executed.
The slip amount is increased by a predetermined amount SL (that is,
Reduce the engagement pressure of the clutch (step 803)
817), the slip amount (clutch engagement pressure)
NO after reaching a predetermined amount determined from operating conditions _XAbsorbent
(Step 813, Step 81)
9). Thereby, NO_XWhen performing absorbent regeneration operation
Is always driven by a sufficient amount of slip.
Deterioration of drivability due to torque fluctuation is prevented
You. Further, according to the present embodiment, NO_XAbsorbent NO_XSucking
If the yield increases, do not wait for changes in driving conditions.
Perform playback operations at the right time
NO_XKeeping the absorption capacity of the absorbent high
Becomes possible.

[0070] In the present embodiment, the target slip amount TSLP when _the NO _X absorbent regenerating operation so that is gradually changed by a predetermined amount SL is the fluctuation of the driving torque due to sudden change in the engagement state of the clutch This is to prevent drivability from deteriorating. Further, in this embodiment, since the slip amount is increased to a predetermined amount according to the driving conditions, the change in the clutch engagement state is smaller than in the case where the clutch is completely released. Smaller than when releasing the clutch. Therefore, according to the present embodiment, NO
_X absorbent despite changing the engagement state of the clutch to each playback operation execution, deterioration in drivability such as in the case of releasing the lock-up clutch for each regenerating operation of the NO _X absorbent is generated Absent.

Next, an embodiment corresponding to claim 3 of the present invention will be described. Also in this embodiment, the slip control of the lock-up clutch is performed as in the embodiment of FIG. As described above, when the lock-up clutch is released, N
O _X be performed regenerating operation of the absorbent less variation in the drive torque, deterioration in drivability is not necessary to limit the reproducing operation of the NO _X absorbent for less. On the other hand, during the lock-up clutch full engagement, to appear in a driving torque variation directly the engine output variation, limiting the execution of the regeneration operation of the NO _X absorbent because deterioration of drivability due to _the NO _X absorbent regeneration increases There is a need. In addition, during the intermediate state between them, that is, during the slip control, the larger the slip of the lock-up clutch, the less the fluctuation of the engine output torque appears in the fluctuation of the driving torque.

[0072] In this embodiment, when the lock-up clutch fully engaged condition, NO NO by regenerating operation of the _X absorbent is tightened condition to be performed to reduce the regeneration operation execution frequency of the NO _X absorbent _X while reducing the chance of drivability deteriorates due absorbent regeneration operation occurs, by increasing the regeneration operation execution frequency of the NO _X absorbent to relax the above conditions as the lock-up clutch approaches a released state from the state of slip control , thereby preventing a decrease in the absorption capacity of _the NO _X absorbent increases the frequency of execution of _the NO _X absorbent regenerating operation. Thus, the overall deterioration in drivability can be prevented, lowering of the absorption capacity of _the NO _X absorbent is prevented.

FIG. 9 shows an example of a flowchart of the NO _X absorbent regeneration operation control. This routine is also executed by the electronic control circuit 30 at regular intervals. In this embodiment, the slip control of the lock-up clutch is executed by a routine separately executed by the control circuit 30,
_The NO _X absorbent operation of changing the target slip amount for playback operation is not performed, as _the NO _X absorbent regenerating operation conditions, the throttle opening change amount of the embodiment of FIG. 7 in response to the lock-up clutch engagement state Is changed.

In FIG. 9, when the routine starts,
In step 901, it is determined the need for the regenerating operation of the NO _X absorbent from the value similarly NO _X absorption amount counter C and the embodiment of FIG. 7, step when a small absorption amount 903
To reset the flag F and terminate the routine. In addition,
The function of the flag F is the same as in the embodiment of FIG. If NO _X absorption in step 901 it is determined that the large step 9
05, the torque converter input / output shaft rotation speed NI, NO
Are read from the sensors 21 and 22 and the throttle opening TA is read from the sensor 20, respectively. In step 907, the throttle opening change rate DLTA and the rotational speed difference (slip amount) SLP of the input / output shaft are expressed by SLP = NI− NO
Is calculated as

[0075] In step 909 following then divides the value of the slip amount SLP in the four regions, the determination value of the throttle opening change rate DLTA as _the NO _X absorbent regenerating operation conditions in accordance with each region Alternatively, it is determined whether or not the reproduction operation can be performed. That is, in step 909 and below, the value of the slip amount SLP is set as SLP ≧ S ₃ , SLP
_{3> SLP ≧ S 2, S} 2> SLP ≧ S 1, S 1> S
In four regions of the LP, as the slip amount is large, i.e. variation in the engine output more difficult it appears as deterioration in drivability, and set to a small determination value of the throttle opening change rate DLTA NO _X absorbent The area of the condition under which the reproduction operation is executed is expanded.

First, in step 909, the slip SL
P is whether or not a predetermined value S ₃ or more is determined. Here S ₃ is large slip amount sufficient to be determined that the lock-up clutch is in a released state. Therefore, step 90
Since the lock-up clutch in the case of SLP ≧ S ₃ is in the released state at 9, since deterioration also drivability running regenerating operation of the NO _X absorbent fewer steps 911
Sets the flag F (= 1) and ends the routine.

[0077] When the SLP <S ₃ in step 909, the process proceeds to step 913, the slip SLP predetermined value S
_It is determined whether it is ₂ or more. Here S ₂ is S ₃ is smaller than the slip amount. SLP is S ₂ or more, i.e. S ₃
> For SLP ≧ S _2, the lock-up clutch means relatively slip is large state in a semi-engaged state, the process proceeds to step 915, the throttle opening change rate DL
TA is determined whether the predetermined value A ₁ or more, DLTA ≧ A ₁
In the case of, the flag F is set in step 911 and NO
_X Permits the execution of absorbent regeneration operation. Here the predetermined value A ₁ is a predetermined value A ₂ value smaller than the later. Also, DLTA
<In the case of A ₁ does not perform _the NO _X absorbent regenerating operation to reset the flag F in step 925.

[0078] Further, the process proceeds to step 917 in the case of SLP <S ₂ in step 915, the slip SLP whether predetermined values S ₁ or more is determined. Where S ₁ is sufficiently small slip amount is determined that the lockup clutch is completely engaged. SLP is S ₁ or more at step 917,
That is, if S ₂ > SLP ≧ S ₁ , it means that the lock-up clutch is in the half-clutch state and the slip is relatively small, so the process proceeds to step 919, where it is determined whether the throttle opening change rate DLTA is equal to or more than the predetermined value A _2. Judge whether
In the case of LTA ≧ A ₂ permits the _the NO _X absorbent regenerating operation sets the flag F at step 921. Here the predetermined value A ₂ are predetermined values A ₁ greater than the aforementioned. Further, in the case of DLTA <A ₂ do not run _the NO _X absorbent regenerating operation to reset the flag F in step 925.

[0079] When the SLP <S ₁ in step 917, i.e. whether the lock-up clutch is determined to be in full engagement, the process proceeds to step 923, the throttle opening change rate DLTA predetermined value A ₃ or more Judge whether or not
Sets the flag F process proceeds to step 911 only if the DLTA ≧ A ₃ permit _the NO _X absorbent regenerating operation performed.
Here the predetermined value A ₃ is greater than the predetermined value A ₂ described above. Further, DLTA <Step 92 in the case of A ₃
5 do not run _the NO _X absorbent regenerating operation to reset the flag F in.

That is, in this embodiment, the slip amount SL
As P becomes larger as S ₁ → S ₂ → S ₃ , the throttle opening change rate D as the condition for executing the NO _X absorbent regeneration operation D
The LTA determination value is set as small as A ₃ → A ₂ → A ₁ . That is, the regenerating operation conditions of the NO _X absorbent as engagement state of the lock-up clutch approaches the fully engaged in the disengaged (released) state is alleviated, comprising reproducing operation is easily performed.

As described in the embodiment of FIG. 7, the rate of change DLTA of the throttle opening represents the driver's intention to accelerate or decelerate. As the DLTA increases, the driver anticipates a large change in driving torque. You are doing.
By increasing the determination value DLTA closer state to the lock-up clutch is completely engaged state as in the present embodiment therefore, by _the NO _X absorbent regenerating operation as in a state where a large variation appears in the driving torque Thus, the driving torque fluctuation expected by the driver can be increased. For this reason, according to the present embodiment, even when the regeneration operation is performed and the driving torque fluctuation increases, the discomfort actually given to the driver is reduced, and the effect of further reducing the drivability is obtained. Also in this embodiment, similar to the embodiment of FIG. 7, there is no changing the engagement state of the lock-up clutch for the regenerating operation of the NO _X absorbent, the optimum always according to the running state This means that control of the lock-up clutch is maintained.

Next, FIG. 10 shows another embodiment corresponding to claim 3 of the present invention, which is different from FIG. In the embodiment of FIG. 9, by setting smaller the determination value of the throttle opening change rate as _the NO _X absorbent regenerating operation conditions as the slip amount increases, it had relaxed execution condition. In contrast, in this embodiment, by setting a small determination value of the NO _X absorption as _the NO _X absorbent regenerating operation conditions as the slip amount increases, the point that relaxes the regenerating operation conditions Are different.

That is, in the embodiment of FIG. 10, the slip amount is divided into four regions by using the simultaneous predetermined values S ₁ , S ₂ , and S ₃ as shown in FIG. 9 (steps 1009, 1013, 101).
7), as the slip amount increases, the NO _x absorption amount as a condition for executing the regeneration operation becomes C ₄ → C ₃ → C ₂ → C
₁ and is set to be small (step 100
1, 1015, 1019, 1023). In the embodiment of FIG. 10, the values of C ₄ , C ₃ , C ₂ , and C ₁ are, for example, 75% of the maximum NO _X amount that can be absorbed by the NO _X absorbent.
%, 70%, 65%, and 60%.

[0084] Thus, by changing the NO _X absorption amount determination value as the regenerating operation condition in accordance with the slip amount, the engine output variation lockup clutch approaches the fully engaged state is likely to appear in the drive torque fluctuation As the reproduction operation becomes more difficult to execute, the chances of drivability deterioration are reduced, and overall drivability deterioration is reduced. In addition, as the lock-up clutch approaches the disengaged (disengaged) state and the influence on drivability is reduced, the regeneration operation is more easily performed. Therefore, according to this embodiment, optimal with deterioration in drivability can be prevented without reducing the regenerating operation frequency as a whole _the NO _X absorbent, similar to the embodiment of FIG. 9, which always according to the running state Lockup clutch control can be maintained.

The steps in the flowchart in FIG. 10 are the same as those in the flowchart in FIG. In the embodiment of FIGS. 9 and 10, the slip amount SLP is divided into four regions, and the determination value of the reproduction operation execution condition is changed stepwise according to this region. It is also possible to continuously change the judgment value of the execution condition.

[0086]

Effects of the Invention According to the present invention described in claim 1, in the lock-up clutch engagement, it has to perform only _the NO _X absorbent regenerating operation when the drive torque fluctuation driver intended results the performs reproduction operation of the NO _X absorbent without inhibiting the control of the lock-up clutch according to the running state, it is possible to prevent deterioration in drivability simultaneously.

According to the second aspect of the present invention,
The regenerating operation of the NO _X absorbent, to reduce the engagement pressure of the lock-up clutch, in accordance with the NO _X absorption without causing deterioration in drivability by which is adapted to run after securing a sufficient amount of slip it becomes possible to perform the regenerating operation of the NO _X absorbent. Further, according to the present invention described in claim 3, as the engagement state of the lock-up clutch approaches a released state from the completely engaged state, by which is adapted to mitigate the regenerating operation conditions of the NO _X absorbent , even when performing the slip control of the lock-up clutch, perform the regenerating operation of the NO _X absorbent without inhibiting the control of the lock-up clutch according to the running state
In addition, deterioration of drivability can be prevented as a whole.

[Brief description of the drawings]

FIG. 1 is an overall view of an internal combustion engine with an automatic transmission showing an embodiment of the present invention.

FIG. 2 shows NO _X used in the exhaust gas purification apparatus of the embodiment shown in FIG.
It is a figure explaining the absorption and release effect of NO _X of the absorbent.

FIG. 3 is a diagram showing a format of a numerical value table used for determining a basic fuel injection amount.

FIG. 4 is a diagram showing a setting example of a fuel injection amount correction coefficient.

5 is a flowchart showing an example of the NO _X absorption estimation method of the NO _X absorbent.

FIG. 6 is a diagram illustrating an example of a shift diagram of the automatic transmission.

FIG. 7 is a flowchart showing an embodiment according to claim 1 of the present invention.

FIG. 8 is a flowchart showing an embodiment according to claim 2 of the present invention.

FIG. 9 is a flowchart showing an embodiment according to claim 3 of the present invention.

FIG. 10 is a flowchart showing another embodiment according to claim 3 of the present invention.

[Explanation of symbols]

1 ... engine 17 ... exhaust passage 18 ... NO _X absorbent 30 ... electronic control circuit 40 ... automatic transmission

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification code FI B60K 41/02 F01N 3/08 ZABA F01N 3/08 ZAB 3/18 ZABB 3/18 ZAB 3/24 ZABR 3/24 ZAB F02D 29 / 00 H F02D 29/00 43/00 301E 43/00 301 301Z 45/00 364H 45/00 364 F16H 61/14 602Z F16H 61/14 602 B01D 53/34 129Z (56) References JP-A-5-306641 (JP, A) JP-A-4-165160 (JP, A) JP-A-58-152143 (JP, A) JP-A-64-45933 (JP, A) JP-A-4-39131 (JP, A) Kaihei 1-115739 (JP, A) JP-A 63-63546 (JP, U) International Publication 93/7363 (WO, A1) (58) Fields investigated (Int. Cl. ⁷ , DB name) F02D 41 / 00-41/40 F02D 43/00-45/00 F02D 29/00-29/06

Claims (3)

(57) [Claims] 1. A disposed in an exhaust passage of an internal combustion engine for a vehicle, NO air-fuel ratio of the exhaust gas absorbs NO _X in the exhaust gas when the lean, the oxygen concentration in the exhaust gas absorbed when reduced
And _the NO _X absorbent to release the _X, NO _X absorption of the _the NO _X absorbent reaches a predetermined value
Automatically when the, by switching the air-fuel ratio of the internal combustion engine from a lean air-fuel ratio to a rich air-fuel ratio, the air-fuel ratio switching means for releasing NO _X absorbed from the _the NO _X absorbent, which is connected to the internal combustion engine A control device for an internal combustion engine with an automatic transmission, comprising a transmission and a lock-up clutch provided between an input / output shaft of a torque converter of the automatic transmission and bringing the input / output shaft into a directly connected state when engaged. A torque change detecting means for detecting a change in engine output torque intended by the vehicle driver; and the air-fuel ratio only when an engine output change intended by the vehicle driver is detected while the lock-up clutch is engaged. Prohibiting means for permitting execution of the rich air-fuel ratio operation by the switching means and prohibiting execution of the rich air-fuel ratio operation while the other lock-up clutch is engaged. A control device for an internal combustion engine with an automatic transmission. Wherein disposed in an exhaust passage of an internal combustion engine for a vehicle, NO air-fuel ratio of the exhaust gas absorbs NO _X in the exhaust gas when the lean, the oxygen concentration in the exhaust gas absorbed when reduced
And _the NO _X absorbent to release the _X, by switching to control the air-fuel ratio of the internal combustion engine, from a lean air-fuel ratio of the internal combustion engine when a predetermined condition is satisfied rich air-fuel ratio, the NO _X and air-fuel ratio switching means for releasing NO _X absorbed from the absorbent, and an automatic transmission connected to the internal combustion engine, provided between the input and output shafts of the torque converter of the automatic transmission, changing the engagement pressure Thereby, a non-engaged state and a half-clutch state in which the input and output shafts are engaged while allowing a rotational difference therebetween,
The control apparatus for an internal combustion engine with an automatic transmission having continuous and a lock-up clutch capable of changing the engaged state between a fully engaged state to directly connect the input and output shafts, the NO _X release When the predetermined condition for the lock-up clutch is satisfied, the engagement pressure of the lock-up clutch is reduced to the lock-up clutch .
Engagement control means for reducing the latch to a predetermined value at which the latch is in the half-clutch state; and switching to the rich air-fuel ratio by the air-fuel ratio switching means until the lock-up clutch engagement pressure reduction operation by the engagement control means is completed. A control device for an internal combustion engine with an automatic transmission, comprising: a prohibition unit for prohibiting the operation. 3. disposed in an exhaust passage of an internal combustion engine for a vehicle, NO air-fuel ratio of the exhaust gas absorbs NO _X in the exhaust gas when the lean, the oxygen concentration in the exhaust gas absorbed when reduced
And _the NO _X absorbent to release the _X, reproduction Misao to release NO _X absorbed from the _the NO _X absorbent
By switching to the rich air-fuel ratio from the lean air-fuel ratio of the internal combustion engine when a predetermined condition for executing the work is satisfied, NO _X absorbed from the _the NO _X absorbent
And an automatic transmission connected to the internal combustion engine, and provided between the input and output shafts of a torque converter of the automatic transmission, and by changing an engagement pressure, a non-engaged state is provided. And a half-clutch state in which the input and output shafts are engaged while allowing a rotational difference therebetween.
A control device for an internal combustion engine with an automatic transmission, the control device including: a lock-up clutch capable of continuously changing an engagement state between a full engagement state directly connecting the input / output shaft; and the lock-up clutch. Before the change of engagement state
Condition setting means for changing the predetermined condition for performing the recording operation, wherein the condition setting means changes the engagement state of the lock-up clutch from the completely engaged state to the non-engaged state. As approaching, predetermined conditions for executing the reproduction operation are satisfied.
A control device for an internal combustion engine with an automatic transmission , wherein the predetermined condition is relaxed so as to be easy to stand .