JP3487056B2 - Control device for automatic transmission - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a control device for an automatic transmission connected to an engine capable of executing lean burn operation with a large air-fuel ratio, and more particularly to a transient during gear shifting of a friction engagement device. The present invention relates to a control device for an automatic transmission that learns and controls hydraulic pressure.

[0002]

2. Description of the Related Art In an automatic transmission for a vehicle, it is well known that the level of hydraulic pressure of a friction engagement device for performing a gear shift or the state of supply and discharge greatly influences a gear shift shock. The transient hydraulic pressure of the friction engagement device is controlled according to the state of gear shifting. Engagement of two frictional engagement devices such as clutches and brakes
Clutch, which switches the released state at the same time
In the case of clutch gear shifting, the output torque is reduced due to the fact that both of these two friction engagement devices involved in the gear shift have torque capacities above a predetermined level, and the two friction engagement devices involved in the gear shift. The hydraulic pressure of at least one of these friction engagement devices is controlled in accordance with an overshoot state in which both the torque capacity decreases and the engine speed increases. Further, the situation of the tie-up and the overshoot varies depending on the input torque, so that the learning control for sequentially updating the control amount of the hydraulic pressure based on the situation of the shift is performed.

Since the oil pressure of the friction engagement device obtained by the learning control is a pressure suitable for the input torque to the automatic transmission at that time, it is necessary to simultaneously detect the input torque in the learning control of the oil pressure. And the input torque must be stable in a steady state. Since it is practically difficult to directly measure the input torque to detect the input torque, the intake air amount and the intake pipe negative pressure that are in correspondence with the input torque are detected, and the input torque is calculated from the detected value. It is done by the method of estimating.

However, the input torque does not always correspond to these data. For example, even if the intake air amount is the same, if the fuel injection amount is different, the input torque to the automatic transmission changes. . A typical example of this is a lean-burn engine that can be operated with an air-fuel ratio greater than the theoretical air-fuel ratio.During lean-burn operation, the fuel injection amount is reduced and the air-fuel ratio is increased, so the output torque of the engine Becomes smaller for the same throttle opening during operation at the stoichiometric air-fuel ratio or the output air-fuel ratio, and the input torque to the automatic transmission decreases.

In this lean burn state, combustion in the cylinder of the engine becomes unstable, and so on.
The torque estimation data such as the intake air amount and the intake pipe negative pressure do not match the actual output torque as much as at the so-called stoichiometric time set at the theoretical air-fuel ratio and at the so-called rich time set at the output air-fuel ratio. Therefore, for example, in the invention disclosed in Japanese Patent Laid-Open No. 5-209677, in order to prevent erroneous learning of the transient hydraulic pressure during shifting of the friction engagement device, learning of the engagement pressure is prohibited during lean burn, and When learning the engagement pressure, the air-fuel ratio is positively set to the rich or stoichiometric state, and the hydraulic pressure is learned in the state where the torque is stable.

On the other hand, in lean burn control in an engine, for example, the basic fuel injection time for setting the stoichiometric air-fuel ratio is multiplied by a predetermined correction coefficient to inject fuel for a time determined to set the air-fuel ratio to a predetermined value. It is done by doing. For the basic fuel injection time and the correction coefficient, data indicating the engine driving state such as the engine load and the engine speed is prepared as a map as a parameter, and a value corresponding to the operating state is read from the map and adopted. Is normal.

However, since the correction coefficient prepared in advance as described above is obtained under a certain condition, the mapped value is not always appropriate under a condition different from that condition. In some cases, the air-fuel ratio during lean burn operation is learned and controlled based on the operating state of the engine.

[0008]

[Problems to be Solved by the Invention] The lean burn operation is
For example, since it is executed when the vehicle speed or the throttle opening is stable at a predetermined value (range) at the second or higher speed in the drive (D) range, the throttle opening hardly changes. If the vehicle speed changes slowly, the shift is determined. In order to smoothly perform the shift, it is necessary to set the hydraulic pressure supplied to the friction engagement device involved in the shift to an appropriate value according to the input torque to the automatic transmission or the output torque of the engine.

However, the above-mentioned Japanese Patent Laid-Open No. 5-2096
As described in Japanese Patent Publication No. 77, since the learning control of the hydraulic pressure of the friction engagement device during the lean burn operation is not executed in the related art, the hydraulic pressure of the friction engagement device at the time of shifting is preset. There is no choice but to set a fixed value. As a result, the hydraulic pressure of the friction engagement device involved in gear shifting does not always become an appropriate pressure for the torque applied to the friction engagement device, which may cause a shock or the durability of the friction engagement device. There was a possibility that it would lead to a decrease in sex.

The present invention has been made in view of the above circumstances, and optimizes the hydraulic pressure of the friction engagement device involved in the shift during lean burn operation to reduce the shift shock and the durability of the friction engagement device. It is an object of the present invention to provide a control device capable of preventing the above.

The object of the present invention is to learn and control the transient hydraulic pressure of the friction engagement device while the air-fuel ratio is stable even when the air-fuel ratio is set to an appropriate value such as rich or lean. To be achieved.

[0012]

In order to achieve the above-mentioned object, the invention described in claim 1 is an air-fuel system.
Connected to multiple types of engines with different ratios
And learning control of transient hydraulic pressure during shifting of friction engagement device
The automatic transmission control device
A means for detecting the stable state of the fuel ratio, and
When the gear ratio is detected to be stable,
Of the transient hydraulic pressure learning control for each air-fuel ratio
And a means for determining the learned value of the transient hydraulic pressure during the shift.
Each air-fuel ratio is stored separately and stored.
The learning value for the air-fuel ratio is used to
It is characterized by controlling hydraulic pressure .

Therefore, in the invention of claim 1,
When the air-fuel ratio is stable, the friction engagement device is
The transfer hydraulic pressure is learned and controlled, in which case the throttle opening etc.
Engine output torque determined based on the parameters of
Even if the torque varies depending on the air-fuel ratio, the transient hydraulic pressure
Since the learning control is divided into
The shift transient hydraulic pressure of the learning control is based on the output torque of the engine.
And therefore the transient oil of the friction engagement device.
The pressure is optimized to reduce the shock and durability of the friction engagement device.
The bottom is effectively prevented.

The invention of claim 2 is the invention of claim 1.
In the lean-burner with the air-fuel ratio larger than the theoretical air-fuel ratio.
Learning control of the transient hydraulic pressure at the time of gear shifting
The stable state of the air-fuel ratio during the shift
The means to do this is a rich spy that temporarily reduces the air-fuel ratio.
Rich spike execution, including means to detect
If transient is detected, the learning of transient hydraulic pressure during shifting is stopped.
It is characterized in that it is provided with a means for doing.

Therefore, in the invention of claim 2 ,
A lid that temporarily reduces the air-fuel ratio during lean burn operation.
Since the shift transient hydraulic pressure is not learned during the chispike,
When the engine torque increases due to a temporary decrease in air-fuel ratio
Do not take hydraulic pressure as a learning value. Ie lean bar
Erroneous learning during operation is prevented, and as a result, shifting transient hydraulic pressure
Is optimized to improve the durability of gear shift shock and friction engagement device.
It is prevented from falling.

[0016]

[0017]

[0018]

BEST MODE FOR CARRYING OUT THE INVENTION Next, the present invention will be described more specifically with reference to the drawings. First, an example of an automatic transmission targeted by the present invention will be described with reference to FIG. Figure 1
In, the automatic transmission 3 is connected to the engine 1 via the torque converter 2. This torque converter 2
Is a pump impeller 5 connected to the crankshaft 4 of the engine 1, a turbine runner 7 connected to the input shaft 6 of the automatic transmission 3, and a lockup clutch that directly connects the pump impeller 5 and the turbine runner 7. 8
And a stator 10 that is prevented from rotating in one direction by a one-way clutch 9.

The automatic transmission 3 has two types of high and low.
It is provided with a sub-transmission unit 11 that switches the gears, and a main transmission unit 12 that can switch between a reverse gear and four forward gears. The auxiliary transmission unit 11 includes a sun gear S0, a ring gear R0,
And an HL planetary gear unit 13 composed of a pinion P0 rotatably supported by the carrier K0 and meshed with the sun gear S0 and the ring gear R0, and a clutch C0 and a one-way clutch provided between the sun gear S0 and the carrier K0. F0 and a brake B0 provided between the sun gear S0 and the housing 19 are provided.

The main transmission unit 12 includes a sun gear S1, a ring gear R1, and a first planetary gear unit 14 which is rotatably supported by a carrier K1 and comprises a pinion P1 meshed with the sun gear S1 and the ring gear R1.
A second planetary gear unit 15 including a sun gear S2, a ring gear R2, and a pinion P2 rotatably supported by the carrier K2 and meshed with the sun gear S2 and the ring gear R2, a sun gear S3, and a ring gear R3.
, And a third planetary gear unit 16 comprising a pinion P3 rotatably supported by the carrier K3 and meshed with the sun gear S3 and the ring gear R3.

The sun gear S1 and the sun gear S2 are integrally connected to each other, the ring gear R1, the carrier K2 and the carrier K3 are integrally connected to each other, and the carrier K3 thereof is connected.
Is connected to the output shaft 17. In addition, ring gear R2
Are integrally connected to the sun gear S3. A first clutch C1 is provided between the ring gear R2 and the sun gear S3 and the intermediate shaft 18, and a second clutch C2 is provided between the sun gear S1 and the sun gear S2 and the intermediate shaft 18.

As the braking means, the housing 19 is provided with a band-type first brake B1 for stopping the rotation of the sun gear S1 and the sun gear S2. Also, the sun gear S1 and the sun gear S2 and the housing 19
Between the first one-way clutch F1 and the brake B.
2 are provided in series. This first one-way clutch F
1 is configured to be engaged when the sun gear S1 and the sun gear S2 try to reversely rotate in the opposite direction to the input shaft 6.

A third brake B3 is provided between the carrier K1 and the housing 19, and a fourth brake B4 and a second one-way clutch F2 are provided in parallel between the ring gear R3 and the housing 19. Has been. This second
The one-way clutch F2 is configured to be engaged when the ring gear R3 tries to rotate in the reverse direction. The clutches C0, C1, C2, the brakes B0, B1, B2
, B3, B4 are hydraulic friction engagement devices which are engaged with friction material by the action of hydraulic pressure.

In the above automatic transmission, five forward gears and reverse gears can be set, and the engagement / release states of the friction engagement devices for setting these gears are shown in FIG. It is shown in the operation table. In FIG. 2, the mark ◯ indicates the engaged state and the mark x indicates the released state.

FIG. 3 is a control system diagram of the engine 1 and the automatic transmission 3, and shows the accelerator pedal 20.
A signal corresponding to the amount of depression of the engine electronic control unit 2
It is input to 1. The intake duct of the engine 1 is provided with an electronic throttle valve 23 driven by a throttle actuator 22. The electronic throttle valve 23 changes from the control device 21 to the throttle actuator 22 according to the depression amount of the accelerator pedal 20. A control signal is output, and the opening degree is controlled according to the control amount.

Further, an engine rotation speed sensor 24 for detecting the rotation speed of the engine 1, an air flow meter 25 for detecting the amount of intake air, an intake air temperature sensor 26 for detecting the temperature of intake air, and an opening degree of the electronic throttle valve 23. throttle sensor 27 for detecting θ, vehicle speed sensor 28 for detecting vehicle speed V from the rotational speed of output shaft 17, etc., engine 1
A cooling water temperature sensor 29 for detecting the cooling water temperature, a brake switch 30 for detecting the operation of the brake, an operation position sensor 32 for detecting the operation position of the shift lever 31, and the like are provided. Signals representing the engine speed N, the intake air temperature Tha, the opening degree θ of the electronic throttle valve 23, the vehicle speed V, the engine cooling water temperature THw, the brake operating state BK, and the operating position Psh of the shift lever 31 are output from these sensors. It is adapted to be supplied to the engine electronic control unit 21 and the shift electronic control unit 33. It should be noted that the electronic control device 33 for shifting has the electronic throttle valve 2 described above.
Signals of the opening degree θ of 3, the vehicle speed V, the engine cooling water temperature THw, and the brake operating state BK are input.

Further, a signal representing the turbine rotation speed NT is supplied from the turbine rotation speed sensor 34 for detecting the rotation speed of the turbine runner 7 to the electronic shift control device 33. Further, a kick down switch 35 for detecting that the accelerator pedal 20 has been operated to the maximum operation position.
A signal representing a kick down operation is input to the electronic shift control device 33.

The engine electronic control unit 21 is a so-called microcomputer having a central processing unit (CPU), a storage device (RAM, ROM), and an input / output interface. The CPU uses the temporary storage function of the RAM. Meanwhile, the input signal is processed according to a program stored in advance in the ROM, and various engine controls are executed. For example, the fuel injection valve 37 is controlled to control the fuel injection amount,
Controls the igniter 38 for ignition timing control, controls a bypass valve (not shown) for idle speed control, and controls all throttles including traction control.
The throttle actuator 22 controls and executes the electronic throttle valve 23.

The shift electronic control unit 33 is also a microcomputer similar to the engine electronic control unit 21 described above, in which the CPU uses the temporary storage function of the RAM and receives the input signal in accordance with the program stored in the ROM in advance. As well as processing, each solenoid valve or linear solenoid valve of the hydraulic control circuit 38 is driven.
For example, the electronic shift control device 33 includes the throttle valve 23.
The linear solenoid valve SLT for generating the output pressure PSLT having a magnitude corresponding to the opening of the valve, the linear solenoid valve SLN for controlling the accumulator back pressure, and the slip amount of the lockup clutch 8 are controlled, and the speed change is performed. The linear solenoid valves SLU are respectively driven to control the engagement pressure of a predetermined clutch or brake during transition in accordance with the progress of gear shifting and according to the input torque.

Further, the electronic shift control device 33 uses the basic throttle valve opening θ (throttle opening converted by a predetermined nonlinear characteristic with respect to the amount of depression of the accelerator pedal), the vehicle speed V, and a shift line using these as parameters. Based on the drawing, the gear stage of the automatic transmission 3 and the lockup clutch 8
Of the hydraulic pressure control circuit 38 so that the determined gear and engagement state are obtained.
1 to No. 3 solenoid valves SOL1, SOL2, SOL
When driving 3 to generate engine braking,
o. 4 solenoid valve SOL4.

On the other hand, the lockup clutch 8 is released in the first speed and the second speed of the automatic transmission 3, but in the third speed and the fourth speed, it is based on the basic throttle valve opening θ and the vehicle speed V. The lock-up clutch 8 is slip-controlled in the slip region, and engaged in the engagement region. This slip control is intended to suppress the rotational loss of the torque converter 2 as much as possible while absorbing the rotational fluctuation of the engine 1.

FIG. 4 shows the operating position of the shift lever 31. In the figure, a combination of six operation positions in the front-rear direction of the vehicle and two operation positions in the left-right direction of the vehicle allows the shift lever 31 to be operated at eight operation positions by a supporting device (not shown) so that the shift lever 31 can be operated. It is supported. And P is the parking range position, R
Is the reverse range position, N is the neutral range position,
D is a drive range position, "4" is a "4" range position for setting a gear up to the fourth speed, "3" is a "3" range position for setting a gear up to the third speed, and "2" is The "2" range position is used to set the gears up to the second speed, and L is the low range position where the upshift to the first or higher gears is prohibited.

As shown in FIG. 2, the automatic transmission 3 described above is
The shift between the second speed and the third speed is a clutch-to-clutch shift in which both the engagement states of the third brake B3 and the second brake B2 are switched. In order to execute this shift smoothly and quickly, the hydraulic pressure control circuit 38 incorporates the circuit shown in FIG. This is the third brake B
The engagement pressure PB3 of 3 is electrically controlled directly on the basis of the input torque and the progress of the shift. The configuration will be briefly described below.

In FIG. 5, reference numeral 70 indicates a 1-2 shift valve, reference numeral 71 indicates a 2-3 shift valve, and reference numeral 72 indicates a 3-4 shift valve. The communication state of each port of the shift valves 70, 71, 72 at each shift speed is determined by the respective shift valves 70, 71, 7
As shown on the lower side of No. 2. In addition, the number shows each gear stage. A third brake B3 is connected via an oil passage 75 to a brake port 74 that communicates with the input port 73 at the first speed and the second speed among the ports of the 2-3 shift valve 71. An orifice 76 is provided in this oil passage, and the orifice 76 and the third brake B3
A damper valve 77 is connected between and. The damper valve 77 sucks a small amount of hydraulic pressure to perform a buffering action when the line pressure is suddenly supplied to the third brake B3.

Reference numeral 78 is a B-3 control valve, and the engagement pressure of the third brake B3 is directly controlled by this B-3 control valve 78. That is, the B-3 control valve 78 includes a spool 79, a plunger 80, and a spring 81 interposed therebetween, and an oil passage 75 is connected to an input port 82 opened and closed by the spool 79. Output port 8 that is selectively communicated with input port 82
3 is connected to the third brake B3. Further, the output port 83 is connected to a feedback port 84 formed on the tip side of the spool 79. On the other hand, in the port 85 that opens at the location where the spring 81 is arranged, the port 86 that outputs the D range pressure at the third or higher speed of the 2-3 shift valve 71 is connected via the oil passage 87. It is in communication. A lockup clutch linear solenoid valve SLU is connected to a control port 88 formed on the end side of the plunger 80.

Therefore, the B-3 control valve 78
Is configured such that the pressure regulation level is set by the elastic force of the spring 81 and the hydraulic pressure supplied to the port 85, and the elastic force of the spring 81 increases as the signal pressure supplied to the control port 88 increases. There is.

Further, in FIG. 5, reference numeral 89 is a 2-3 timing valve. The 2-3 timing valve 89 comprises a spool 90 having a small diameter land and two large diameter lands and a first plunger. 91, a spring 92 arranged between them, and a second plunger 93 arranged on the opposite side of the first plunger 91 with the spool 90 interposed therebetween. An oil passage 95 is connected to an intermediate port 94 of the 2-3 timing valve 89.
Is the port 9 of the 2-3 shift valve 71 that is communicated with the brake port 74 at the third or higher speed.
Connected to 6.

Further, the oil passage 95 is branched in the middle to open a port 97 between the small diameter land and the large diameter land.
Is connected via an orifice. The port 98, which is selectively communicated with the port 94 at the intermediate portion, is the oil passage 9
It is connected to the solenoid relay valve 100 via 9. The lock-up clutch linear solenoid valve SLU is connected to the port opened at the end of the first plunger 91, and the second brake B2 is passed through the orifice at the port opened at the end of the second plunger 93. Connected.

The oil passage 87 is for supplying / discharging hydraulic pressure to / from the second brake B2, and a small diameter orifice 101 and an orifice 102 with a check ball are interposed in the middle thereof. Further, the oil passage 103 branched from the oil passage 87 has a large diameter orifice 10 provided with a check ball that opens when the pressure is exhausted from the second brake B2.
4 is interposed, and this oil passage 103 is connected to an orifice control valve 105 described below.

The orifice control valve 105 is a valve for controlling the exhaust pressure speed from the second brake B2, and the port 107 formed in the intermediate portion so as to be opened and closed by the spool 106 has the second brake B2.
The oil passage 103 is connected to a port 108 formed below the port 107 in the figure. A port 109 formed above the port 107 to which the second brake B2 is connected in the drawing is a port that is selectively communicated with the drain port, and the port 109 is connected to the port 109 via an oil passage 110. The port 111 of the B-3 control valve 78 is connected. The port 111 is a port that is selectively communicated with the output port 83 to which the third brake B3 is connected.

Of the ports of the orifice control valve 105, the control port 112 formed at the end opposite to the spring for pressing the spool 106 is connected to the port 114 of the 3-4 shift valve 72 via the oil passage 113. ing. This port 114 outputs the signal pressure of the third solenoid valve S3 at the shift speed of the third speed or lower, and the fourth speed.
It is a port for outputting the signal pressure of the fourth solenoid valve S4 at a shift speed higher than the high speed. Further, an oil passage 115 branched from the oil passage 95 is connected to the orifice control valve 105, and the oil passage 115 is selectively connected to the drain port.

The port 11 for outputting the D range pressure at the shift speed of the second speed or lower in the 2-3 shift valve 71.
6 through the oil passage 11 at the port 117 opening at the position where the spring 92 is arranged in the 2-3 timing valve 89.
8 are connected. Also 3-4 shift valve 72
Of these, a port 119, which is communicated with the oil passage 87 at a speed lower than the third speed, is connected to the solenoid relay valve 100 via an oil passage 120.

In FIG. 5, reference numeral 121 denotes an accumulator for the second brake B2, to the back pressure chamber of which the accumulator control pressure adjusted according to the hydraulic pressure output by the linear solenoid valve SLN is supplied. There is. The accumulator control pressure is configured to be higher as the output pressure of the linear solenoid valve SLN is lower. Therefore, the second brake B
The transitional hydraulic pressure of engagement / disengagement 2 is changed to a higher pressure as the signal pressure of the linear solenoid valve SLN is lower. Further, by temporarily lowering the signal pressure of the linear solenoid valve SLU, the second brake B2
The engagement pressure of can be temporarily increased.

Reference numeral 122 indicates a C-0 exhaust valve, and reference numeral 123 indicates an accumulator for the clutch C0. C-0 exhaust valve 1
Numeral 22 operates to engage the clutch C0 to apply the engine brake only in the second speed in the second speed range.

Therefore, according to the hydraulic circuit described above,
If the port 111 of the B-3 control valve 78 communicates with the drain, the engagement pressure of the third brake B3 can be directly regulated by the B-3 control valve 78, and the regulation level can be adjusted by the linear solenoid valve. SLU
Can be changed by If the spool 106 of the orifice control valve 105 is in the position shown in the left half of the figure, the second brake B2 can be communicated with the oil passage 103 through this orifice control valve 105, so that the large diameter orifice 104 is used. Exhaust pressure is possible and therefore the drain speed from the second brake B2 can be controlled.

The engagement pressure of each friction engagement device in the automatic transmission 3 described above is a pressure determined by the line pressure controlled according to the throttle opening θ in the engine 1,
For example, the engagement pressure PB3 of the third brake B3 during the shift between the second speed and the third speed, which is a clutch-to-clutch shift.
Is controlled on the basis of the gear change situation and the input torque. For example, in the case of upshifting from the second speed to the third speed, the input speed is reduced to the synchronous speed of the third speed by controlling the second brake B2 and the so-called overlap with a predetermined torque capacity. Promote things. On the contrary, when downshifting from the third speed to the second speed, the engagement pressure of the third brake B3 is maintained at a low pressure to control so-called underlap, and the input speed is set to the second speed. Promote the increase to the synchronous speed. Also, at the end of the downshift to the second speed, the engagement pressure of the second brake B2 that is finally released is temporarily increased to reduce the torque, so that the shock caused by the torsion torque is reduced. To prevent.

As described above, the engagement pressure may be controlled in accordance with the circumstances of the gear shift. In this case, the engagement pressure is set to the input torque in order to prevent the durability from being deteriorated due to the sliding of the friction engagement device. It is necessary to set the pressure according to. Since the torque input to the automatic transmission 3 is most affected by the output torque of the engine 1, that is, the driving state of the engine 1, it is necessary to detect or control the driving state of the engine 1. An example of the control will be described later.

The engine 1 to which the automatic transmission 3 described above is connected is capable of lean burn operation in which the air-fuel ratio is larger than the theoretical air-fuel ratio, and releases NOx from the NOx absorbent during lean burn operation. Therefore, it is configured to execute the rich spike that temporarily sets the air-fuel ratio to the rich side. Then, explaining the engine 1, FIG. 6 schematically shows an intake and exhaust system,
A spark plug 132 is arranged in a combustion chamber 131 formed on the top side of the piston 130. Further, the combustion chamber 131 has an intake port 134 having an intake valve 133.
And the exhaust port 136 having the exhaust valve 135 are in communication with each other.

The intake port 134 is connected to the surge tank 138 via the corresponding manifold 137,
A fuel injection valve 139 for injecting fuel into the intake port 134 is attached to each of the manifolds 137. Further, the surge tank 138 has an intake duct 140.
And the air cleaner 14 via the air flow meter 25.
1, the throttle valve 23 in the intake duct 140.
Are arranged.

On the other hand, the exhaust port 136 is connected to the NOx absorbent 1 through the exhaust manifold 142 and the exhaust pipe 143.
It is connected to a casing 145 containing 44, and the casing 145 is further connected to a catalytic converter 147 via an exhaust pipe 146. The catalytic converter 147 contains a three-way catalyst 148.

Electronic control unit 2 for controlling this engine 1
1 comprises a digital computer, a bidirectional bus 1
ROM (Read Only Memory) 150, RAM (Random Access Memory) 1 mutually connected by 49
51, a CPU (microprocessor) 152, an input port 153 and an output port 154. The air flow meter 25 generates an output voltage proportional to the intake air amount, and this output voltage is input to the input port 153 via the AD converter 155. Further, the input port 153 is connected to a rotation speed sensor 24 that generates an output pulse representing the engine rotation speed. On the other hand, the output port 154 is connected to the spark plug 132 and the fuel injection valve 139 via the corresponding drive circuits 156 and 157, respectively.

As described above, the engine 1 includes the fuel injection valve 1
The fuel is supplied from 39, and the fuel injection time TAU is calculated based on the formula TAU = TP × Kt. Here, TP represents the basic fuel injection time, and Kt represents the correction coefficient. The basic fuel injection time TP is the fuel injection time required to make the air-fuel ratio of the air-fuel mixture supplied to the cylinder of the engine 1 the stoichiometric air-fuel ratio.

The basic fuel injection time TP is previously obtained by an experiment, and the engine load and the engine speed N are expressed by the intake air amount Q / N (Q is the intake air amount, N is the engine speed) per revolution. Is previously stored in the ROM 152 in the form of a map as shown in FIG.
The correction coefficient Kt is a coefficient for controlling the air-fuel ratio of the air-fuel mixture supplied to the engine 1. If Kt = 1.0, the air-fuel mixture supplied to the cylinder has a stoichiometric air-fuel ratio. On the other hand, when Kt <1.0, the air-fuel ratio of the air-fuel mixture supplied into the cylinder becomes larger than the stoichiometric air-fuel ratio, and the engine 1 is in lean burn operation.
Further, if Kt> 1.0, the air-fuel ratio of the air-fuel mixture supplied into the cylinder becomes smaller than the stoichiometric air-fuel ratio, resulting in a so-called rich state.

In the engine shown in FIG. 6, normally, for example, K
Since t = 0.7 or 0.6 is maintained, lean burn operation is performed. FIG. 8 shows the combustion chamber 1
31 schematically shows the concentrations of typical components in the exhaust gas discharged from 31. As is known from FIG. 8, the concentration of unburned HC and CO discharged from the combustion chamber 131 increases as the air-fuel ratio of the air-fuel mixture supplied to the combustion chamber 131 becomes richer, and is discharged from the combustion chamber 131. The concentration of oxygen O _{2 in} the generated exhaust gas increases as the air-fuel ratio of the air-fuel mixture supplied into the combustion chamber 131 becomes leaner.

NO stored in the casing 145
The x-absorbent 144 uses, for example, alumina as a carrier, and potassium K, sodium Na, lithium L
i, alkali metals such as cesium Cs, barium Ba
, Alkaline earth such as calcium Ca, lanthanum La
, At least one selected from rare earths such as yttrium Y, and a noble metal such as platinum Pt.

The ratio of air and fuel supplied into the exhaust duct upstream of the intake duct and the NOx absorbent 144 is determined to be "NO."
x air-fuel ratio of the exhaust gas flowing into the absorbent 144 ",
The NOx absorbent 144 absorbs NOx when the air-fuel ratio of the inflowing exhaust gas is lean, and when the oxygen concentration in the inflowing exhaust gas is below, performs the absorbing and releasing action of the NOx that releases the absorbed NOx.

When fuel or air is not supplied into the exhaust pipe upstream of the NOx absorbent 144, the air-fuel ratio of the inflowing exhaust gas matches the air-fuel ratio of the air-fuel mixture supplied into the combustion chamber 131. Therefore, in this case, the NOx absorbent 144 absorbs NOx when the air-fuel ratio of the air-fuel mixture supplied to the combustion chamber 131 is lean, and the oxygen concentration in the air-fuel mixture supplied to the combustion chamber 131 decreases. Then, the absorbed N
It will release Ox.

If the above NOx absorbent 144 is arranged in the exhaust pipe, the NOx absorbent 144 actually absorbs and releases NOx, but the detailed mechanism of this absorbing and releasing operation is not clear. is there. However, this absorption and release action is considered to be performed by a mechanism as shown in FIG. Although this mechanism will be described by taking as an example the case where platinum Pt and barium Ba are supported on a carrier, the same mechanism can be obtained by using other noble metals, alkali metals, alkaline earths and rare earths.

That is, when the inflowing exhaust gas becomes considerably lean, the oxygen concentration in the inflowing exhaust gas greatly increases.
As shown in (A), these oxygen O ₂ are O ₂ ⁻ or O ^2−.
Adheres to the surface of platinum Pt. On the other hand, NO in the inflowing exhaust gas reacts with O ₂ ⁻ or O ^{2− on} the surface of platinum Pt to become NO ₂ (2NO + O ₂ → 2NO ₂ ).

Then, a part of 2NO ₂ produced is platinum P
While being oxidized on t, it is absorbed by the absorbent 144 and combined with barium oxide BaO, and is absorbed in the absorbent 144 in the form of nitrate ion NO ₃ ⁻ as shown in FIG. 9 (A). In this way, NOx is absorbed in the NOx absorbent 144.

[0061] NO ₂ is produced on the surface of the platinum Pt so long as the oxygen concentration in the inflowing exhaust gas is high, as long as NO ₂ to NOx absorption ability of the absorbent is not saturated it is absorbed in the absorbent and nitrate ions NO ₃ ^- is Is generated. On the other hand, if the oxygen concentration in the inflowing exhaust gas decreases and the amount of NO ₂ produced decreases,
Proceeds to ^- (→ NO ₂ NO _3), as a result, nitrate ions NO in absorbent ₃ ^- reaction backward is released from the absorbent in the form of NO _2. That is, when the oxygen concentration in the inflowing exhaust gas decreases, NOx is released from the NOx absorbent 144. As shown in FIG. 8, when the oxygen concentration in the inflowing exhaust gas is reduced, and therefore the leanness of the inflowing exhaust gas is lowered, NOx is released from the NOx absorbent 144 even if the inflowing exhaust gas is lean. It will be.

On the other hand, when the air-fuel ratio of the inflowing exhaust gas is made rich at this time, a large amount of unburned HC and CO are discharged from the engine 1 as shown in FIG.
CO reacts with oxygen O ₂ ⁻ or O ²⁻ on platinum Pt to oxidize. Also, if the air-fuel ratio of the inflowing exhaust gas is made rich,
Since the oxygen concentration in the inflowing exhaust gas is extremely reduced, NO ₂ is released from the absorbent, and this NO ₂ is reduced by reacting with unburned HC and CO, as shown in FIG. 9 (B). When NO ₂ is no longer present on the surface of platinum Pt in this way, NO ₂ is released from the absorbent one after another. Therefore, when the air-fuel ratio of the inflowing exhaust gas is made rich, NOx is released from the NOx absorbent 144 within a short time.

That is, when the air-fuel ratio of the inflowing exhaust gas is made rich, first, unburned HC and CO immediately react with O ₂ ⁻ or O ^{2 −} on platinum Pt to be oxidized, and then O on platinum Pt is oxidized. ₂ ^- or O ^2- are still unburned HC be consumed, any remaining CO is the unburned HC, NOx discharged from the released NOx, the engine from the absorbent by CO is reduced. Therefore, in order to reduce the total NOx released from the absorbent and the total NOx emitted from the engine when the air-fuel ratio of the inflowing exhaust gas is made rich, at least O ₂ ⁻ or O ²⁻ on platinum Pt is consumed. It is necessary to control the degree of richness of the air-fuel ratio of the inflow gas so that the amount of unburned HC and CO necessary for the flow into the NOx absorbent 144.

As described above, in the engine shown in FIG.
Normally, the air-fuel mixture supplied to the cylinder is kept lean (for example, Kt = 0.7), and the N generated at this time is generated.
Ox is absorbed by the NOx absorbent 144. However, if the lean air-fuel mixture continues to be burned, the NOx absorbent 144
The NOx absorption capacity due to is saturated and NOx cannot be absorbed by the NOx absorbent 144 after a while. Therefore, when the lean air-fuel mixture is continuously burned, the control device according to the present invention temporarily enriches the air-fuel mixture supplied to the cylinder as shown in FIG.
= KK), whereby the NOx absorbed by the NOx absorbent 144 is released from the NOx absorbent 144. That is, the rich spike is executed.

In this case, if the air-fuel mixture supplied into the cylinder is simply switched from the lean air-fuel ratio to the rich air-fuel ratio, the engine output torque fluctuates. Therefore, in order to prevent such a situation, the lean air-fuel ratio and the rich air-fuel ratio are prevented. And are set. That is, as shown in FIG. 11, the engine output torque decreases when the air-fuel ratio becomes lean with the output air-fuel ratio (11.0 to 12.0) as a boundary.
In addition, the engine output torque decreases even when the air-fuel ratio becomes rich.

Therefore, as shown in FIG. 11, there are the lean air-fuel ratio (KL) and the rich air-fuel ratio (KK) at which the engine output torque becomes equal. So combustion chamber 1
When the lean air-fuel mixture is to be burned in 31, the air-fuel ratio at that time is set to the lean air-fuel ratio (KL), and the combustion chamber 13
When the rich air-fuel mixture is to be burnt within 1, the air-fuel ratio at that time is set to the rich air-fuel ratio (KK) and the ignition timing is switched to a value corresponding to each air-fuel ratio. When the lean air-fuel ratio and the rich air-fuel ratio are predetermined in this way, when the lean air-fuel ratio is switched to the rich air-fuel ratio and when the rich air-fuel ratio is switched to the lean air-fuel ratio, fluctuations in engine output torque and shock Is suppressed.

In this embodiment, the lean air-fuel ratio (K
L) is preset to be equivalent to Kt = 0.7,
Therefore, the rich air-fuel ratio (KK) is set so that an output torque equal to the engine output torque when using this lean air-fuel ratio is obtained. In this case, the rich air-fuel ratio (KK) is a function of the engine load Q / N and the engine speed N, and the rich air-fuel ratio (KK) is the engine load Q / N and the engine speed as shown in FIG. It is stored in the ROM 150 in advance in the form of N functions.

By the way, the rich air-fuel ratio KK 'of FIG. 10 is obtained when the air-fuel ratio of the air-fuel mixture supplied into the cylinder is switched from the lean air-fuel ratio (Kt = 0.7) to the rich air-fuel ratio (Kt = KK'). It shows the air-fuel ratio at which the unburned components necessary for consuming O ₂ ⁻ on platinum Pt and reducing all NOx are generated. In the above engine, the rich air-fuel ratio (KK) at the time of the rich spike is set to an air-fuel ratio on the richer side than the rich air-fuel ratio (KK '), so the NOx absorbent 144 has platinum Pt above The unburned components necessary for consuming O ₂ ⁻ and reducing all NOx are supplied, and as a result, NOx is reduced well.

However, in that case, the surplus unburned component is discharged from the NOx absorbent 144, and thus it is necessary to oxidize this surplus unburned component.
Therefore, a catalytic converter 147 containing a catalyst 148 having a storage function is arranged in the exhaust pipe line on the downstream side of the NOx absorbent 144, and this catalyst oxidizes unburned components.

That is, this catalyst 148 uses, for example, alumina as a carrier and a noble metal and calcium Ca on the carrier.
Alkaline earth like the above and cesium Ce are carried. When cesium Ce is supported on the carrier in this manner, the catalyst 148 adsorbs and holds oxygen contained in the exhaust gas when the air-fuel ratio of the exhaust gas flowing into the catalyst 148 is lean, and the exhaust gas flowing into the catalyst 148 is adsorbed and held. when the air-fuel ratio of the becomes richer, so provided the O ₂ storage function of unburned HC, CO deprives oxygen was adsorbed and held. Therefore, a catalyst 1 having such an O ₂ storage function
When 48 is placed in the exhaust pipe line downstream of the NOx absorbent 144, a large amount of oxygen is adsorbed and held by the catalyst 148 while the lean air-fuel mixture is being burned, so the NOx absorbent 1
Even if the air-fuel mixture supplied to the combustion chamber 131 to release NOx from 44 is made rich and unburned HC and CO are discharged from the NOx absorbent 144, these unburned HC,
CO deprives the oxygen adsorbed and held by the catalyst 148 to be oxidized, and as a result, unburned HC and CO are prevented from being released into the atmosphere.

The action of releasing NOx from the NOx absorbent 144 is such that when a certain amount of NOx is absorbed by the NOx absorbent 144, NOx is absorbed up to about 50% of the absorption capacity of the NOx absorbent 144. Sometimes done. N
The amount of NOx absorbed by the Ox absorbent 144 is proportional to the amount of exhaust gas discharged from the engine and the NOx concentration in the exhaust gas, in which case the amount of exhaust gas is proportional to the amount of intake air,
Since the NOx concentration in the exhaust gas is proportional to the engine load, the NOx amount absorbed by the NOx absorbent 144 can be accurately estimated from the cumulative value of the product of the intake air amount and the engine load, but the control For simplicity, the NOx amount absorbed in the NOx absorbent 144 may be estimated from the cumulative value of the engine speed.

Next, control of the rich spike in the above engine will be described. FIG. 13 shows a routine executed by the electronic control unit 21 at regular time intervals. First, in step 1, the basic fuel injection time T
Whether the correction coefficient Kt for P is smaller than 1.0,
That is, it is determined whether or not the lean burn operation is being performed. When Kt ≧ 1.0, that is, when the air-fuel mixture supplied to the cylinder has the stoichiometric air-fuel ratio or the rich air-fuel ratio, the routine exits without performing any control.

On the other hand, when Kt <1.0, that is, when the lean air-fuel mixture is being combusted, step 2
And the result of adding ΣNE to the current engine speed NE is taken as ΣNE. Therefore, ΣNE indicates the cumulative value of the engine speed NE. Next, at step 3, it is judged if the cumulative rotation speed ΣNE is larger than a constant value SNE. This constant value SNE is NOx absorbent 14
4 shows the cumulative rotational speed at which it is estimated that 50% of the NOx absorption capacity of the NOx is absorbed. Σ
When NE≤SNE, the routine returns, and when ΣNE> SNE, that is, when it is estimated that the NOx absorbent 144 has absorbed 50% of the NOx absorbing capacity of the NOx absorbing capacity, the routine proceeds to step 4, where the NOx releasing flag is set. To be done. When the NOx release flag is set, the air-fuel mixture supplied into the cylinder is switched to rich as described later, and the ignition timing is retarded according to the air-fuel ratio of the air-fuel mixture.

Then, in step 5, the count value C is 1
Is incremented only. Next, at step 6, it is judged if the count value C has become larger than the constant value C0, that is, if 0.5 seconds has elapsed, for example. C ≦
When C0, the routine returns, and when C> C0, the routine proceeds to step 7, where the NOx releasing flag is reset. NO
When the x release flag is reset, the air-fuel mixture supplied into the cylinder is switched from rich to lean as described later. Therefore, the air-fuel mixture supplied into the cylinder is richly controlled for 0.5 second. Next, at step 8, the cumulative rotation speed ΣNE and the count value C are cleared.

FIG. 14 shows a routine for calculating the fuel injection time TAU. This routine is executed by the engine electronic control unit 21 at regular time intervals (or at constant crankshaft rotation angles). In FIG. 14, first, at step 10, the basic fuel injection time TP is calculated from the map shown in FIG. Next, at step 11, it is judged if the NOx releasing flag is set. When the NOx release flag is not set, steps 12 and 13
Then, the correction coefficient Kt is set to 0.7, for example, and then the process proceeds to step 14. In step 14, fuel injection time TA
U (= TP * Kt) is calculated. At this time, the air-fuel mixture supplied into the cylinder is made lean.

On the other hand, when it is determined in step 11 that the NOx releasing flag is set, step 1
In step 5, KK is calculated from the relationship shown in FIG. Then, in step 16, the value of the correction coefficient Kt is set to KK,
Go to step 14. Therefore, at this time, the air-fuel mixture supplied into the cylinder has a rich air-fuel ratio.

By the way, the actual air-fuel ratio may deviate from the controlled air-fuel ratio due to aging of the engine or the like.
In such a case, for example, an air-fuel ratio sensor (not shown)
Is preferably installed in the exhaust port 136, and the control value is corrected based on the detected actual air-fuel ratio.

[0078] Further, when performing rich spike that temporarily set to a rich side air-fuel ratio during lean operation, the combustion chamber even by reducing the air-fuel ratio of the mixed Aiki supplied to the cylinder 1
The air-fuel ratio of the air-fuel mixture in 31 may change with a delay. This is because the wall surface of the intake port 134 is in a dry state during lean operation, and when a rich air-fuel ratio mixture is supplied to this, a part of the fuel contained in the mixture adheres to the wall surface of the intake port, This is because the amount of fuel in the air-fuel mixture in the cylinder decreases.

Therefore, the air-fuel ratio in the combustion chamber 131 becomes smaller after the start of the rich spike control. Therefore, if the ignition timing is changed at the same time when the rich spike control is started, it is conceivable that the air-fuel ratio and the ignition timing become transiently incompatible with each other and the fluctuation of the engine output torque becomes large. In order to avoid such a situation, when changing the air-fuel ratio from lean to rich, or when changing from rich to lean, the ignition timing is changed by delaying the change of the air-fuel ratio, or the ignition timing is gradually changed. It is preferable to change to. Alternatively, when changing the air-fuel ratio from lean to rich, the fuel injection amount is increased at the start of control so as to compensate for the adhesion of fuel to the wall surface, and when changing from rich to lean, rich due to the detachment of fuel from the wall surface. It is preferable to decrease the fuel injection amount at the start of the control so as to compensate for the change. The transient control when switching these air-fuel ratios is specifically described in Japanese Patent Laid-Open No. 6-193487.

In the automatic transmission 3 described above, the hydraulic pressure of the friction engagement device involved in gear shifting is set based on the input torque to the automatic transmission 3 or the output torque of the engine 1, and the parameter thereof is, for example, gear shifting. The type, vehicle speed, throttle opening, etc. are adopted. On the other hand, the engine 1 is operated by changing the air-fuel ratio depending on the condition of the vehicle, and therefore the engine torque may be different even if the vehicle speed and the throttle opening are the same. Then, the shift transient hydraulic pressure of the friction engagement device is learned and controlled as described below.

FIG. 15 is a flow chart showing an example of the control routine, which processes the input signal (step 2).
After performing 0), it is determined whether or not the sensor is normal (step 21). The sensor judged here is, in short,
These are sensors for detecting the operating states of the engine 1 and the automatic transmission 3, and the main ones are air flow meter 25, engine speed sensor 24, throttle opening sensor 27, vehicle speed sensor 28, cooling water temperature sensor. 29 etc. The determination can be made based on the fact that the output signal is inconsistent with the output signal from another sensor or the execution content of the control.

If any of the sensors has an abnormality and a negative determination is made in step 21, it means that the conditions of the engine 1 and the automatic transmission 3 cannot be accurately detected, and therefore the process returns without any particular control. . If each sensor is operating normally and the determination in step 21 is affirmative, it is determined whether the engine water temperature TE is equal to or higher than a preset reference temperature α (step 22). This is because it is necessary that the engine 1 is sufficiently warmed up and the operation of the engine 1 is stable.

Therefore, if the determination in step 22 is negative because the engine water temperature has not reached the reference temperature α, the process returns without performing any particular control, and if the engine water temperature is equal to or higher than the reference temperature α, the automatic shift is performed. It is determined whether the oil temperature TA of the machine 3 is equal to or higher than a predetermined reference temperature β (step 23). This is because it is premised that the oil viscosity of the automatic transmission 3 is lowered and stable hydraulic pressure control can be performed. If a negative determination in step 23 is therefore to return without any control, and when an affirmative determination is made whether the drive range (D range) is set (Step 24 ).

When a range other than the D range is selected, the process returns, and when the D range is selected, it is determined whether or not gear shifting (upshift or downshift) is in progress (step 25). If the gear is not being changed, the routine returns. If the gear is being changed, it is judged whether or not the air-fuel ratio is in the stoichiometric air-fuel ratio (stoichiometric region) (step 26). This can be determined by, for example, whether or not the above-described fuel injection time correction coefficient Kt is set to "1.0".

If a negative decision is made in step 26,
It is determined whether the air-fuel ratio is set in the rich region (step 27). This can be determined by whether or not the correction coefficient Kt is set to a value larger than "1.0". If a negative determination is made in step 27, it is determined whether the air-fuel ratio is set in the lean range (step 28). This can be determined by whether or not the correction coefficient Kt is set to a value smaller than "1.0".

If a negative decision is made in step 28,
Since the air-fuel ratio cannot be determined, the routine returns without any particular control. On the other hand, when the affirmative determination is made in step 28 because the lean burn operation is being executed, it is determined whether the air-fuel ratio (A / F) is stable, that is, the fluctuation range of the air-fuel ratio is within the predetermined range. It is then determined whether or not it is inside, or whether or not the air-fuel ratio is continuously changing (step 29). The air-fuel ratio may be changed due to unstable combustion in the engine 1 or the like, and the air-fuel ratio may be temporarily lowered due to the rich spike described above. The air-fuel ratio may be changed transiently and continuously, and in such a case, the engine torque becomes unstable, which may affect the learning control of the transient hydraulic pressure during shifting of the friction engagement device. There is.

If a negative determination is made in step 29 because the air-fuel ratio is unstable, the learning control of the hydraulic pressure during the shift transition of the friction engagement device is stopped (step 3).
0). Specifically, the detected value of the shift transient hydraulic pressure is not stored in the memory, or the data obtained by learning is not reflected in the hydraulic control of the friction engagement device. On the other hand, when the affirmative determination is made in step 29 because the air-fuel ratio is stable, it is determined whether or not the lean sensor (air-fuel ratio sensor) is stable (step 31). This lean sensor is arranged in the exhaust manifold, and outputs the detected air-fuel ratio as an electric signal. If the operation of the lean sensor, that is, the output signal is not stable, the learning is stopped (step 30), and if it is stable, it is determined whether the learned value of the air-fuel ratio in the lean burn state is stable. A judgment is made (step 32).

The air-fuel ratio during lean burn operation is feedback-controlled (and learning-controlled) so that the deviation between the value obtained by the air-fuel ratio sensor and the target air-fuel ratio becomes small, but the learning coefficient changes greatly with it. If so, the change in the engine torque due to the change in the air-fuel ratio is large, so the determination in step 32 is made. And step 32
If the determination is negative, the engine torque is in an unstable state, so learning of the transient hydraulic pressure is stopped (step 30).

On the other hand, if the affirmative judgment is made in step 32, it is judged whether or not the lean limited feedback control is stable (step 33). This is because when the air-fuel ratio in the lean burn state is feedback-controlled, the limit value thereof is set in advance, so that the air-fuel ratio may reach the limit value as a result of the feedback control. If it is stable in that state, the engine torque is stable, so that state is determined in step 33.

When the lean limited feedback control is in an unstable state, that is, when the air-fuel ratio fluctuates, learning of the transient hydraulic pressure is stopped (step 30). On the contrary, when it is stable, The learning control of the transient hydraulic pressure in the lean burn state is performed (step 34). This is, for example, a tie-up amount during clutch-to-clutch gear shift executed by the hydraulic circuit of FIG. 5 described above, an overshoot amount of the engine 1, and a hydraulic pressure control value by engagement pressure feedback control during gear shift transition. Specifically, it is learned as the duty ratio of the linear solenoid valve for controlling the hydraulic pressure. An example of such control is described in JP-A-63-291738. The hydraulic pressure obtained by the learning control, specifically, the duty ratio D3 is stored as a map for lean burn operation, as shown in FIG. It should be noted that, as an example, the map can be adopted with the vehicle speed and the type of shift as parameters.

On the other hand, if the affirmative judgment is made in step 26, that is, if the air-fuel ratio is in the stoichiometric range, it is judged whether the air-fuel ratio (A / F) is stable or not (step 35). If it is not stable, the hydraulic pressure learning control is stopped (step 36). On the contrary, if it is stable, the hydraulic pressure learning control in the stoichiometric state is executed (step 37). The content of this learning control is the same as during lean burn operation, but its learned value D1 is stored as a map for stoichiometric operation and is used for transient oil pressure control during gear shifting, as shown in FIG. To be done.

Further, when the affirmative judgment is made in step 27, that is, when the air-fuel ratio is in the rich region, it is judged whether or not the air-fuel ratio (A / F) is stable (step 38), and it is stable. If not, the hydraulic pressure learning control is stopped (step 39). On the contrary, if it is stable, the hydraulic pressure learning control in the stoichiometric state is executed (step 40). The content of this learning control is the same as during lean burn operation or stoichiometric operation, but its learning value D2 is stored as a map for rich operation as shown in FIG. 17, and at the rich air-fuel ratio. It is used to control the transient hydraulic pressure during shifting during operation.

Incidentally, steps 29, 33, 38, 35
Corresponds to means for determining the stable state of the engine torque, and steps 34, 37, 40 correspond to means for learning by classifying for each air-fuel ratio. Further, step 29 includes means for executing rich spike, and step 30 is performing learning .
It corresponds to the means to stop .

That is, in the above control device, the friction engagement device is operated in accordance with the air-fuel ratio in each of the lean, rich and stoichiometric regions and when the operating state at each air-fuel ratio is stable. The hydraulic pressure at the time of the gear shift transition is learned separately, and the transient hydraulic pressure is controlled by the obtained control value. Therefore, the gear shift transient hydraulic pressure of the friction engagement device can be set to a pressure that matches the engine torque or the input torque of the automatic transmission 3, and smooth gear shift can be achieved without gear shift shock, and the durability of the friction engagement device can be improved. It is possible to prevent deterioration of sex.

In the above embodiment, the gear shift transient hydraulic pressure of the friction engagement device is divided into three types, rich, stoichiometric and lean, to be learned, but the present invention is limited to the above embodiment. However, the air-fuel ratio may be divided into a plurality of types, and the shift transient hydraulic pressure may be learned and controlled for each divided air-fuel ratio.

The automatic transmission to which the present invention is applied is
It may have a gear train other than the gear train shown in FIG. 1 or a hydraulic circuit other than the hydraulic circuit shown in FIG.

[0097]

As described above, according to the invention described in claim 1 , based on the parameter such as the throttle opening.
Judgment engine output torque is different for each air-fuel ratio
However, the transient hydraulic pressure is learned and controlled by dividing it by the air-fuel ratio.
As a result, the transitional hydraulic pressure of the friction engagement device will eventually
Learning control is performed according to the output torque of the engine.
Therefore, the transient hydraulic pressure of the friction engagement device is optimized and the shock
And deterioration of the durability of the friction engagement device are effectively prevented.
It

Further, in the invention of claim 2 , lean burn
During a rich spike that temporarily reduces the air-fuel ratio during operation
The transient hydraulic pressure for shifting is not learned in the
Learning value of hydraulic pressure when engine torque increases with decreasing ratio
Not taken as. That is, a mistake during lean burn operation
Learning is prevented and, as a result, shift transient oil pressure is optimized.
To prevent shifting shocks and deterioration of the durability of the friction engagement device.
Be stopped.

[0099]

[Brief description of drawings]

FIG. 1 is a skeleton diagram showing an example of a gear train of an automatic transmission targeted by the present invention.

FIG. 2 is a diagram showing an engagement operation table of a friction engagement device for setting each shift speed in the automatic transmission.

FIG. 3 is a control system diagram for the engine and the automatic transmission.

FIG. 4 is a diagram showing an arrangement of each range position in the shift device.

FIG. 5 is a diagram showing a part of a hydraulic circuit for controlling hydraulic pressures of second and third brakes that perform shift between clutch second and clutch third speeds. is there.

FIG. 6 is a diagram schematically showing an intake / exhaust system and an air-fuel ratio control system of an engine which is a target of the present invention.

FIG. 7 is a diagram showing a map of basic fuel injection time.

FIG. 8: Unburned H in exhaust gas discharged from the engine
It is a diagram which shows the concentration of C, CO, and oxygen roughly.

FIG. 9 is a diagram for explaining a NOx releasing action.

FIG. 10 is a diagram for explaining NOx release control.

FIG. 11 is a diagram for explaining the relationship between engine torque and air-fuel ratio.

FIG. 12 is a diagram showing a map of a correction coefficient KK.

FIG. 13 is a flowchart showing an example of NOx release control from the NOx absorbent.

FIG. 14 is a flowchart showing an example of fuel injection amount control.

FIG. 15 is a partial flowchart showing a part of a control routine for permitting / prohibiting the learning control of the shift transient hydraulic pressure.

FIG. 16 is a partial flowchart showing another part of the control routine.

FIG. 17 is a map conceptually showing an example of a shift transient hydraulic pressure control value learned by classifying the air-fuel ratio into stoichiometric, rich, and lean states.

[Explanation of symbols]

1 engine 3 automatic transmission 21 Electronic control unit for engine 33 Electronic shifting control device

─────────────────────────────────────────────────── ─── Continuation of the front page (58) Fields surveyed (Int.Cl. ⁷ , DB name) F16H 59/00-63/48

Claims (2)

(57) [Claims] 1. A control device for an automatic transmission, which is connected to an engine capable of performing a plurality of types of operations with different air-fuel ratios, and which learns and controls transient hydraulic pressure during gear shifting of a friction engagement device. A means for detecting a stable state of the air-fuel ratio during shifting,
If the air-fuel ratio is detected to be stable by
In this case, the learning control of the transient hydraulic pressure at the time of shifting is performed for each air-fuel ratio.
And a means for separately performing the operation, which means
It is also possible to store the learned value of the hydraulic pressure for each air-fuel ratio separately.
For each air-fuel ratio, use the learning value for that air-fuel ratio
A control device for an automatic transmission, characterized in that it controls a transient hydraulic pressure during a shift . 2. A fuel tank having an air-fuel ratio larger than the theoretical air-fuel ratio.
Learning control of the transient hydraulic pressure at the time of gear shift during the air-burn operation
When controlling, make sure that the air-fuel ratio is stable during gear shifting.
The means for detecting is a rich engine that temporarily reduces the air-fuel ratio.
Rich spike spikes, including means to detect pike execution
If execution is detected, learn the transient hydraulic pressure during the shift.
To claim 1 characterized in that it comprises means to abort
Control device for automatic transmission according.