JP2001234775A - Control device for engine and automatic transmission - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent torque varying by practicing a rich spike from being incongruent to hydraulic pressure of a friction engagement device. SOLUTION: This control device for an engine and an automatic transmission to set hydraulic pressure of a friction engagement device at the time of changing speed on the automatic transmission connected to the engine in accordance with detected engine torque by releasing NOx from a NOx absorbent in an exhaust passage by practicing a rich spike to temporarily reduce an air-fuel ratio at specified time in the meddle of lean-burn driving increasing the air-fuel ratio of mixture to supply to the engine and practicing control to restrain increase of the engine torque by the rich spike, is furnished with a rich spike prohibition means (step 106) to prohibit the rich spike to temporarily decrease the air-fuel ratio in the middle of detecting the engine torque.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an automatic transmission in a vehicle and an apparatus for controlling an engine connected to the automatic transmission, and more particularly to a method for removing NOx from a NOx absorbent during lean burn operation with an increased air-fuel ratio. BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an engine for executing a rich spike for temporarily lowering an air-fuel ratio to release the engine and an apparatus for controlling an automatic transmission connected to the engine.

[0002]

2. Description of the Related Art In recent years, in order to further improve the fuel efficiency of a vehicle, a vehicle has been developed which performs lean burn control for operating an engine at an air-fuel ratio higher than a stoichiometric air-fuel ratio, and has been put to practical use. ing. In the lean burn operation, the amount of emission of unburned hydrocarbons (HC) and carbon monoxide (CO) in the exhaust gas decreases, but the oxygen concentration in the exhaust gas increases, and the exhaust path increases. The absorption of NOx by the NOx absorbent provided therein is promoted. The NOx absorbent adsorbs NOx in the form of nitric acid, but has a limited capacity, and releases the absorbed NOx during lean burn operation.

One example is described in Japanese Patent Application Laid-Open No. HEI 6-108824. In the invention described in this publication, when the cumulative value of the engine speed reaches a predetermined value, the air-fuel ratio is set to 0.5. The control is performed on the rich side for a short time of about seconds. This is a so-called rich spike control. By performing such control, the concentration of oxygen in the inflow gas with respect to the NOx absorbent is reduced, so that the NOx is released from the NOx absorbent and the NOx absorbent can absorb NOx again. become.

If the air-fuel ratio is controlled to the rich side even in the short time of about 0.5 seconds as described above, the fuel supply amount (fuel injection amount) increases, and the engine output temporarily increases. The increase in the engine output naturally appears as an increase in the driving force, which causes a shock. Therefore, in the invention described in the above publication, the ignition timing is retarded together with the rich spike, and the rich spike is used. The increase in the engine torque is offset by the decrease in the engine torque due to the ignition timing retard control to prevent substantial fluctuations in the drive torque.

When the fluctuation of the engine torque appears as the output torque as it is, it causes a shock as described above. However, even if the fluctuation of the engine torque does not appear as it is, a shock may occur. That is, in a vehicle, a transmission is arranged following a drive source such as an engine, and the torque fluctuates with a change in the gear ratio of the transmission. Shifting in an automatic transmission is performed by switching the engagement / disengagement state of a friction engagement device such as a clutch or a brake. If improper, there will be a shift in the timing of the shift, which eventually causes a shock. Therefore, conventionally, the hydraulic pressure of the friction engagement device of the automatic transmission is generally controlled based on the engine torque.

[0006]

In the conventional apparatus described in the above-mentioned publication, in order to suppress the fluctuation of the engine torque, the ignition timing is retarded together with the rich spike during the lean burn operation. are doing. However, the amount of increase in engine torque due to rich spikes and the amount of decrease in engine torque due to ignition timing retard control are:
It may not always be the same depending on factors such as the warm-up state of the engine and individual differences between the engine and the control device. In such a case, the engine torque fluctuates due to rich spikes. Such fluctuations in torque
Since this occurs due to failure to perform appropriate control, the amount of torque fluctuation cannot be accurately known.

Therefore, when the fluctuation of the engine torque due to the above-described rich spike and the shift, for example, in the automatic transmission, overlap with each other in time, the engine torque cannot be accurately known, so that the friction involved in the shift is changed. The hydraulic pressure of the engagement device becomes an inappropriate pressure with respect to the engine torque (more precisely, the input torque to the automatic transmission). As a result, the shift shock becomes worse, There was a disadvantage that the durability was reduced by slipping. In particular, in the case of a clutch-to-clutch shift in which the two friction engagement devices are simultaneously switched and executed, it is necessary to control the oil pressure of at least one of the friction engagement devices according to the input torque and the situation of the shift. If the actual engine torque or the input torque based on it cannot be accurately detected, there is a possibility that the shift shock will increase.

The present invention has been made in view of the above circumstances, and executes a control for executing a rich spike during lean burn operation and suppressing an increase in engine torque due to the rich spike. It is an object of the present invention to provide a control device capable of preventing a shift shock even when there is a change in engine torque due to an increase factor and a decrease factor of the engine torque.

[0009]

In order to achieve the above object, the invention according to the first aspect of the present invention is directed to a predetermined period during lean burn operation in which the air-fuel ratio of the air-fuel mixture supplied to the engine is increased. A rich spike that temporarily reduces the air-fuel ratio is performed to reduce NOx in the exhaust passage.
Performing control to release NOx from the absorbent and to suppress an increase in engine torque due to the rich spike,
A control device for an engine and an automatic transmission for setting the oil pressure of a friction engagement device at the time of shifting in an automatic transmission connected to the engine based on the detected engine torque. A rich spike inhibiting means for inhibiting a rich spike that temporarily reduces the fuel ratio is provided.

Therefore, according to the first aspect of the present invention, there is no or little factor for fluctuating the engine torque detected based on the engine speed, the intake air amount, the intake pipe negative pressure, or the like. Therefore, the hydraulic pressure set based on the detected engine torque, that is, the torque obtained by subtracting the friction loss torque or the torque for driving the auxiliary equipment from the detected engine torque, and the torque corrected in the operation state of the torque converter, etc. The oil pressure determined in consideration of
The torque is adapted to the actual engine torque, and no shift shock or excessive slippage of the friction engagement device occurs.

[0011] The invention of claim 2 is the invention of claim 1, further comprising means for changing a control amount of the rich spike according to whether or not the rich spike is prohibited.

Therefore, according to the second aspect of the present invention, the rich spike is inhibited, so that the NOx
When the amount of absorption is large, the amount of control such as the time of the rich spike and the amount of decrease in the air-fuel ratio is increased, and the amount of NOx release is increased. As a result, the degree of saturation of the NOx absorbent is reduced, and normal NOx absorption and removal can be performed.

Further, according to the third aspect of the present invention, the exhaust gas is executed by executing a rich spike for temporarily reducing the air-fuel ratio at a predetermined time during the lean burn operation in which the air-fuel ratio of the air-fuel mixture supplied to the engine is increased. A control for releasing NOx from the NOx absorbent in the passage and suppressing an increase in engine torque due to the rich spike is executed, and a hydraulic pressure of a friction engagement device at the time of shifting in an automatic transmission connected to the engine is set to: In the control device for the engine and the automatic transmission, which is set based on the detected engine torque, the engine torque value detected for setting the oil pressure is determined according to the amount of fluctuation of the engine torque by executing the rich spike. And a means for performing correction.

According to the third aspect of the present invention, the variation of the engine torque due to the execution of the rich spike is not limited to the variation of the engine torque due to only the rich spike, but also to other control such as the retard control of the rich spike and the ignition timing. It also includes the total amount of engine torque fluctuation due to the engine torque control. Therefore, in the invention of claim 3, the engine torque detected from the throttle opening, the amount of intake air, and the like is calculated based on these engine torque fluctuations. Since the correction is made, the difference between the obtained engine torque value and the actual engine torque becomes small. Therefore, the hydraulic pressure set based on the engine torque obtained in this way is adapted to the torque input to the automatic transmission, and prevents a reduction in durability due to a shift shock or slippage of the friction engagement device. Is done.

According to a fourth aspect of the present invention, in any one of the first to third aspects, the control for suppressing an increase in engine torque due to the rich spike changes an ignition timing such that the engine torque decreases. Control.

According to the fourth aspect of the present invention, the ignition timing change control for reducing the engine torque is executed together with the rich spike, and as a result, the increase and decrease of the engine torque occur simultaneously. The increase or fluctuation of the engine torque due to the above is suppressed.

[0017]

Next, the present invention will be described more specifically with reference to the drawings. The automatic transmission according to the present invention is configured to control the hydraulic pressure (engagement pressure or release pressure) of the friction engagement device according to the input torque, and the engine to which the automatic transmission is connected includes: The engine performs a lean burn operation in which the air-fuel ratio is set to a value larger than the stoichiometric air-fuel ratio, and executes a rich spike that temporarily reduces the air-fuel ratio at a predetermined time during the lean burn operation.
Therefore, first, an example of the automatic transmission will be described with reference to FIG.

In FIG. 1, an automatic transmission 3 is connected to an engine 1 via a torque converter 2. The torque converter 2 has a pump impeller 5 connected to a crankshaft 4 of the engine 1, a turbine runner 7 connected to an input shaft 6 of the automatic transmission 3, and a direct connection between the pump impeller 5 and the turbine runner 7. And a stator 10 whose rotation in one direction is prevented by a one-way clutch 9.

The automatic transmission 3 has a high and a low
The vehicle is provided with a sub-transmission unit 11 for switching gears, and a main transmission unit 12 for switching between a reverse gear position and four forward gear positions. The auxiliary transmission unit 11 includes a sun gear S0, a ring gear R0,
And an HL planetary gear unit 13 comprising a pinion P0 rotatably supported by the carrier K0 and meshed with the sun gear S0 and the ring gear R0, 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.

The main transmission unit 12 includes a first planetary gear unit 14 including a sun gear S1, a ring gear R1, and a pinion P1 rotatably supported by the carrier K1 and meshed with the sun gear S1 and the ring gear R1.
A second planetary gear set 15 comprising a pinion P2 rotatably supported by the sun gear S2, the ring gear R2 and 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 set 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, and the ring gear R1, the carrier K2, and the carrier K3 are integrally connected to each other.
Is connected to the output shaft 17. Also, the 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.

A first brake B1 in the form of a band for stopping rotation of the sun gear S1 and the sun gear S2 is provided on the housing 19 as a braking means. 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 direction opposite 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. Have been. This second
The one-way clutch F2 is configured to be engaged when the ring gear R3 attempts to rotate in the reverse direction. The clutches C0, C1, C2, the brakes B0, B1, B2
, B3, B4 are hydraulic friction engagement devices in which friction materials are engaged by the action of hydraulic pressure.

In the above automatic transmission, five forward speeds and reverse speeds can be set, and the engagement and disengagement states of the respective friction engagement devices for setting these shift speeds are shown in FIG. It is shown in the joint operation table. In FIG. 2, a mark “○” indicates an engaged state, and a mark “X” indicates a released state.

FIG. 3 shows a control system diagram for the engine 1 and the automatic transmission 3.
The electronic control unit 2 for the engine outputs a signal corresponding to the depression amount of the engine.
1 has been entered. An electronic throttle valve 23 driven by a throttle actuator 22 is provided in an intake duct of the engine 1, and an air flow meter 24 for detecting an intake air amount is arranged upstream of the electronic throttle valve 23, that is, on the intake port side. A control signal is output from the control device 21 to the throttle actuator 22 according to the amount of depression of the accelerator pedal 20, and the opening of the electronic throttle valve 23 is controlled according to the amount of control. The air flow meter 24 is configured to input the detected air amount Q, which is a detection signal, to the control device 21.

An engine speed sensor 25 for detecting the rotational speed of the engine 1, an intake air temperature sensor 26 for detecting the temperature of the intake air, a throttle sensor 27 for detecting the opening θ of the electronic throttle valve 23, and an output shaft A vehicle speed sensor 28 for detecting a vehicle speed V from the rotation speed of the engine 17, a cooling water temperature sensor 29 for detecting a cooling water temperature of the engine 1,
An operation position sensor 32 for detecting an operation position of a brake switch 30 and a shift lever 31 for detecting operation of a brake
And so on. From these sensors, the engine speed N, the intake air temperature Tha, the electronic throttle valve 2
3, the signal indicating the opening degree θ, 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 supplied to the engine electronic control device 21 and the shift electronic control device 33. It has become. Further, a drive / non-drive signal of an auxiliary device such as an air conditioner (air conditioner) 34 is input to the engine electronic control device 21.

A signal representing the turbine rotation speed NT is supplied to a shift electronic control unit 33 from a turbine rotation speed sensor 35 for detecting the rotation speed of the turbine runner 7. Further, a kick-down switch 36 for detecting that the accelerator pedal 20 has been operated to the maximum operation position.
A signal representing the kick down operation is supplied to the electronic control unit 33 for shifting.

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 a temporary storage function of the RAM. While processing input signals in accordance with a program stored in the ROM in advance, various engine controls are executed. For example, by controlling the fuel injection valve 37 for controlling the fuel injection amount,
The igniter 38 is controlled for ignition timing control, a bypass valve (not shown) is controlled for idle speed control, and all throttle control including traction control is performed.
The electronic throttle valve 23 is controlled and executed by the throttle actuator 22. When a failure of the air flow meter 24 or the intake air temperature sensor 26 or a failure of a circuit related thereto occurs, a signal for controlling the driving state of the engine 1 such as a basic fuel injection time and an ignition timing is set to a predetermined value. To the engine 1
Are driven under certain driving conditions.

The electronic control unit 33 for shifting is also a microcomputer similar to the electronic control unit 21 for the engine, and the CPU uses a temporary storage function of the RAM to input an input signal according to a program stored in the ROM in advance. In addition to the processing, each solenoid valve or linear solenoid valve of the hydraulic control circuit 39 is driven.
For example, the electronic control unit for shifting 33 is provided with the throttle valve 23.
The linear solenoid valve SLT is used to generate an output pressure PSLT having a magnitude corresponding to the opening degree, the linear solenoid valve SLN is used to control the back pressure of the accumulator, the slip amount of the lock-up clutch 8 is controlled, and The linear solenoid valves SLU are driven in order to control the predetermined clutch or brake engagement pressure during the transition in accordance with the progress of the shift and according to the input torque. Further, the shift electronic control unit 33 determines the basic throttle valve opening θ (the throttle opening obtained by converting the depression amount of the accelerator pedal with a predetermined nonlinear characteristic), the vehicle speed V, and a shift diagram using these as parameters. The gear position of the automatic transmission 3 and the engagement state of the lock-up clutch 8 are determined, and the solenoid valves SOL1, SOL2, and SOL3 are driven so as to obtain the determined gear position and engagement state, and the engine brake is activated. At the time of generation, the solenoid valve SOL4 is driven.

On the other hand, the lock-up clutch 8 is disengaged in the first and second speeds of the automatic transmission 3, but in the third and fourth speeds, based on the basic throttle valve opening θ and the vehicle speed V. Any one of the areas of release, slip, and engagement is determined. If the area is the slip area, the lock-up clutch 8 is slip-controlled, and if the area is the engagement area, the lock-up clutch 8 is engaged. This slip control is for suppressing the rotation loss of the torque converter 2 as much as possible while absorbing the rotation fluctuation of the engine 1.

FIG. 4 shows the operating position of the shift lever 31. In the drawing, 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 operably supported by the shift lever 31 in eight operation positions. 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 shift speed up to the fourth speed, “3” is a “3” range position for setting a shift speed up to the third speed, and “2” is L indicates a "2" range position for setting a shift speed up to the second speed, and L indicates a low range position at which an upshift to the first or higher speed is prohibited.

As shown in FIG. 2, the automatic transmission 3 is
The shift between the second speed and the third speed is a clutch-to-clutch shift that switches both the engagement states of the third brake B3 and the second brake B2. In order to execute this shift smoothly and quickly, a circuit shown in FIG. This is the third brake B
The third embodiment is configured so that the engagement pressure PB3 is electrically controlled directly based on the input torque and the progress of the shift. The configuration will be briefly described below.

In FIG. 5, reference numeral 70 denotes a 1-2 shift valve, reference numeral 71 denotes a 2-3 shift valve, and reference numeral 72 denotes a 3-4 shift valve. The communication state of each port of these shift valves 70, 71, 72 at each shift speed is determined by the respective shift valves 70, 71, 7
2 as shown below. The numbers indicate the respective gears. A third brake B3 is connected via an oil passage 75 to a brake port 74 communicating 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 interposed in this oil passage, and the orifice 76 and the third brake B3
And a damper valve 77 is connected. This damper valve 77 absorbs a small amount of hydraulic pressure when the line pressure is rapidly supplied to the third brake B3 to perform a buffering action.

Reference numeral 78 denotes a B-3 control valve which directly controls the engagement pressure of the third brake B3 by the 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 selectively connected to 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 leading end side of the spool 79. On the other hand, among the ports 85 of the 2-3 shift valve 71, a port 86 for outputting the D range pressure at the third or higher speed is provided through an oil passage 87. Are in communication. A lock-up clutch linear solenoid valve SLU is connected to a control port 88 formed at the end of the plunger 80.

Therefore, the B-3 control valve 78
The pressure adjustment 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. I have.

In FIG. 5, reference numeral 89 denotes a 2-3 timing valve. The 2-3 timing valve 89 includes a spool 90 having a small-diameter land and two large-diameter lands, and a first plunger. A first plunger 93 is disposed on the opposite side of the first plunger 91 with a spring 92 and a spool 90 interposed therebetween. An oil passage 95 is connected to a port 94 at an intermediate portion of the 2-3 timing valve 89.
Is the port 9 of the 2-3 shift valve 71 which is connected to the brake port 74 at the third or higher speed.
6 is connected.

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

The oil passage 87 is for supplying and discharging hydraulic pressure to and 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. The oil passage 103 branched from the oil passage 87 has a large-diameter orifice 10 having a check ball which opens when the pressure is released from the second brake B2.
The 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 speed from the second brake B2. The orifice control valve 105 is provided with a second brake B2 at a port 107 formed at an intermediate portion so as to be opened and closed by its spool 106.
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 figure is a port selectively communicated with a drain port. The port 111 of the B-3 control valve 78 is connected. The port 111 is a port selectively connected to the output port 83 to which the third brake B3 is connected.

A control port 112 formed at the end of the port of the orifice control valve 105 opposite to the spring for pressing the spool 106 is connected to a port 114 of the 3-4 shift valve 72 via an oil passage 113. ing. The port 114 outputs the signal pressure of the third solenoid valve S3 at the third speed or lower and the fourth speed.
This port outputs the signal pressure of the fourth solenoid valve S4 at a speed higher than the 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 a drain port.

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

In FIG. 5, reference numeral 121 denotes an accumulator for the second brake B2, and an accumulator control pressure regulated according to the hydraulic pressure output from the linear solenoid valve SLN is supplied to the back pressure chamber. I have. The accumulator control pressure is configured to increase as the output pressure of the linear solenoid valve SLN decreases. Therefore, the second brake B
The transitional hydraulic pressure for engagement / disengagement 2 is such that the lower the signal pressure of the linear solenoid valve SLN, the higher the transition pressure. By temporarily lowering the signal pressure of the linear solenoid valve SLU, the second brake B2
Can be temporarily increased.

Reference numeral 122 denotes a C-0 exhaust valve, and reference numeral 123 denotes an accumulator for the clutch C0. C-0 exhaust valve 1
Reference numeral 22 designates an operation for engaging 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 pressure regulation level is controlled by a linear solenoid valve. SLU
Can be changed by If the spool 106 of the orifice control valve 105 is located at the position shown in the left half of the figure, the second brake B2 is connected to the oil passage 103 through the orifice control valve 105. Relieving pressure is possible, so that 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 a shift between the second speed and the third speed, which is a clutch-to-clutch shift.
Is controlled on the basis of a shift situation and an input torque. For example, in the case of an upshift from the second speed to the third speed, the input speed is reduced to the synchronous speed of the third speed by controlling so-called overlap with a predetermined torque capacity together with the second brake B2. Promote that. Conversely, during a downshift from the third speed to the second speed, the engagement pressure of the third brake B3 is maintained at a low pressure so as to be controlled in a so-called underlap mode, and the input speed is set to the second speed. Promote the rise to synchronous speed. At the end of the downshift to the second speed, the shock caused by the torsional torque is reduced by temporarily increasing the engagement pressure of the second brake B2 which is finally released to reduce the torque. To prevent.

As described above, the engagement pressure may be controlled in accordance with the situation of gear shifting. In this case, the engagement pressure is controlled by the input torque in order to prevent a decrease in durability due to slippage 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 influenced 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 can perform lean burn operation in which the air-fuel ratio is larger than the stoichiometric air-fuel ratio, and releases NOx from the NOx absorbent during the lean burn operation. Therefore, a rich spike for temporarily setting the air-fuel ratio to the rich side is executed. To explain this engine 1, FIG. 6 schematically shows an intake and exhaust system.
An ignition plug 132 is arranged in a combustion chamber 131 formed on the top side of the piston 130. The combustion chamber 131 has an intake port 134 having an intake valve 133.
And an exhaust port 136 having an exhaust valve 135 are communicated.

The intake port 134 is connected to a surge tank 138 via a corresponding manifold 137,
A fuel injection valve 139 for injecting fuel into the intake port 134 is attached to each of the manifolds 137. The surge tank 138 is provided with an intake duct 140.
And the air cleaner 14 via the air flow meter 24.
1 and the throttle valve 23 in the intake duct 140.
Is arranged.

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

An electronic control unit 2 for controlling the engine 1
Reference numeral 1 denotes a digital computer, a ROM (read only memory) 150 and a RAM (random access memory) interconnected by a bidirectional bus 149.
151, a CPU (microprocessor) 152, an input port 153, and an output port 154. The air flow meter 24 generates an output voltage proportional to the amount of intake air, and the output voltage is input to the input port 153 via the AD converter 155. The input port 153 is connected to a rotation speed sensor 25 that generates an output pulse indicating the engine rotation speed. On the other hand, the output port 154 is connected to the ignition plug 132 and the fuel injection valve 139 via the corresponding drive circuits 156 and 157, respectively.

As described above, the engine 1 has the fuel injection valve 1
The fuel injection time TAU is calculated based on the following equation: TAU = TP × Kt. Here, TP represents a basic fuel injection time, and Kt represents a correction coefficient. The basic fuel injection time TP is a fuel injection time required for setting the air-fuel ratio of the air-fuel mixture supplied to the cylinder of the engine 1 to the stoichiometric air-fuel ratio.

The basic fuel injection time TP is obtained by an experiment in advance, and the engine load and the engine speed N represented by the intake air amount Q / N per revolution (Q is the intake air amount, N is the engine speed). Are stored in the ROM 152 in advance 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 the stoichiometric air-fuel ratio. On the other hand, if 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 operated in lean burn.
Further, when Kt> 1.0, the air-fuel ratio of the air-fuel mixture supplied into the cylinder becomes smaller than the stoichiometric air-fuel ratio, and a so-called rich state is established.

In the engine shown in FIG.
t = 0.7 or 0.6 is maintained, so that the lean burn operation is performed. FIG. 8 shows the combustion chamber 1
3 schematically shows the concentrations of representative components in the exhaust gas discharged from 31. As is known from FIG. 8, the concentrations of unburned HC and CO discharged from the combustion chamber 131 increase as the air-fuel ratio of the air-fuel mixture supplied to the combustion chamber 131 increases, and the concentration of unburned HC and CO discharged from the combustion chamber 131 increases. The concentration of oxygen O2 in the exhaust gas increases as the air-fuel ratio of the air-fuel mixture supplied into the combustion chamber 131 increases.

NO contained in casing 145
x The absorbent 144 is made of, for example, alumina as a carrier, and for example, potassium K, sodium Na, lithium L
i, an alkali metal such as cesium Cs, barium Ba
Alkaline earths, such as calcium Ca, lanthanum La
And at least one selected from rare earths such as yttrium Y and a noble metal such as platinum Pt.

The ratio of the air and fuel supplied into the intake duct and the exhaust pipe upstream of the NOx absorbent 144 is represented by "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 performs an absorption / release operation of the NOx that releases the absorbed NOx when the oxygen concentration in the inflowing exhaust gas becomes lower.

When no fuel or air is 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 mixture supplied to the combustion chamber 131 is lean, and the oxygen concentration in the mixture supplied to the combustion chamber 131 decreases. Then, the absorbed N
Ox will be released.

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

[0058] That is, when the inflowing exhaust gas becomes considerably lean, the oxygen concentration in the inflowing exhaust gas is greatly increased, these oxygen O ₂ as shown in FIG. 9 (A) O ₂ ^-
Alternatively, it adheres to the surface of platinum Pt in the form of O ²⁻ . on the other hand,
NO in the inflowing exhaust gas reacts with O ₂ ⁻ or O ^{2− on} the surface of the platinum Pt to become NO ₂ (2NO + O ₂ →
2NO ₂ ).

Next, a part of the produced 2NO ₂ is absorbed in the absorbent 144 while being oxidized on the platinum Pt and combined with the barium oxide BaO, and as shown in FIG. 9 (A), the nitrate ion NO ₃ ⁻ Is absorbed in the absorbent 144. In this way, NOx is absorbed in the NOx absorbent 144.

As long as the oxygen concentration in the inflowing exhaust gas is high, NO ₂ is formed on the surface of platinum Pt, and as long as the NOx absorption capacity of the absorbent is not saturated, NO ₂ is absorbed in the absorbent and nitrate ions NO ₃ ⁻ are formed. Generated. On the other hand, when the oxygen concentration in the inflowing exhaust gas decreases and the NO ₂ generation amount decreases, the reaction proceeds in the opposite direction (NO ₃ ⁻ → NO ₂ ),
As a result, nitrate ions NO in absorbent ₃ ^- are released from the absorbent in the form of NO _2. That is, when the oxygen concentration in the inflowing exhaust gas decreases, the NOx
Will be released. As shown in FIG. 8, if the oxygen concentration in the inflowing exhaust gas is reduced, and therefore the degree of leanness of the inflowing exhaust gas is reduced, NOx is released from the NOx absorbent 144 even when the inflowing exhaust gas is lean. Will be.

On the other hand, at this time, the air-fuel ratio of the inflowing exhaust gas is reset.
As shown in FIG. 8, the engine 1
Unburned HC and CO are discharged, and these unburned HC,
CO is oxygen O on platinum Pt₂ ⁻Or O^2-React with
Oxidize. Also make the air-fuel ratio of the inflow exhaust gas rich
And the oxygen concentration in the incoming exhaust gas drops extremely
NO from absorbent₂Is released and this NO₂Figure 9
As shown in (B), it reacts with unburned HC and CO to reduce
Is done. In this way, NO on the surface of platinum Pt₂ Exists
NO2 is released from the absorbent when it is no longer present
Is done. Therefore, the air-fuel ratio of the inflow exhaust gas is made rich.
Then, in a short time, NOx is released from the NOx absorbent 144.
Released.

That is, when the air-fuel ratio of the inflowing exhaust gas is made rich, first, the unburned HC and CO immediately react with O ₂ ⁻ or O ²⁻ on the platinum Pt to be oxidized, and then the O ₂ on the platinum Pt is oxidized. ₂ ^- or ^{O 2-} are still unburned HC be consumed, any remaining CO is the unburned HC, C
O reduces NOx released from the absorbent and NOx discharged from the engine. Therefore, in order to reduce all NOx released from the absorbent and all NOx discharged from the engine when the air-fuel ratio of the inflowing exhaust gas is made rich, at least O ₂ ⁻ or O ₂ on the platinum Pt is required.
^The amount of unburned HC and CO required to consume ^2- is NO
x It is necessary to control the degree of air-fuel ratio richness of the inflowing gas so as to flow into the absorbent 144.

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

In this case, simply switching the air-fuel mixture supplied into the cylinder from the lean air-fuel ratio to the rich air-fuel ratio causes the engine output torque to fluctuate, so that such a situation does not occur. Is set. That is, as shown in FIG. 11, the engine output torque decreases when the air-fuel ratio becomes lean from the output air-fuel ratio (11.0 to 12.0),
Even when the air-fuel ratio becomes rich, the engine output torque decreases.

Therefore, as shown in FIG. 11, there are a lean air-fuel ratio (KL) and a rich air-fuel ratio (KK) at which the engine output torques are equal. So combustion chamber 1
When the lean air-fuel mixture is to be burned at 31, the air-fuel ratio at that time is set to a lean air-fuel ratio (KL), and the combustion chamber 13
When the rich air-fuel mixture is to be burned within 1, the air-fuel ratio at that time is set to a 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 determined in advance in this way, when the lean air-fuel ratio is switched from the rich air-fuel ratio to the rich air-fuel ratio, and when the rich air-fuel ratio is switched from the lean air-fuel ratio to the lean air-fuel ratio, fluctuations in engine output torque and shocks may occur. Is suppressed.

In this embodiment, the lean air-fuel ratio (K
L) is set in advance, for example, to Kt = 0.7,
Therefore, the rich air-fuel ratio (KK) is set such 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. The rich air-fuel ratio (KK) is, as shown in FIG. It is stored in the ROM 150 in advance in the form of a function of N.

The rich air-fuel ratio KK 'in FIG. 10 is obtained when the air-fuel ratio of the mixture supplied to the cylinder is switched from the lean air-fuel ratio (Kt = 0.7) to the rich air-fuel ratio (Kt = KK'). O ₂ on the platinum Pt ^- consumed and unburnt components required to reduce all the NOx indicates the air-fuel ratio for generating. In the above-described engine, the rich air-fuel ratio (KK) at the time of the rich spike is set to a richer air-fuel ratio than this rich air-fuel ratio (KK '). Unburned components required to consume O ₂ ⁻ and reduce total NOx will be supplied, and as a result, NOx will be reduced well.

However, in that case, the surplus unburned components are discharged from the NOx absorbent 144, and therefore, it is necessary to oxidize the surplus unburned components.
Therefore, a catalytic converter 147 having a built-in catalyst 148 having a storage function is arranged in an exhaust pipe on the downstream side of the NOx absorbent 144, and the catalyst oxidizes unburned components.

That is, the catalyst 148 comprises, for example, alumina as a carrier, a noble metal and calcium Ca on the carrier.
And cesium Ce are supported. When cesium Ce is carried on the carrier as described above, 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 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, if the catalyst 148 having such an O ₂ storage function is disposed in the exhaust pipe downstream of the NOx absorbent 144, a large amount of oxygen is adsorbed and held on the catalyst 148 while the lean air-fuel mixture is burning. Therefore, even if the air-fuel mixture supplied into the combustion chamber 131 is made rich to release NOx from the NOx absorbent 144 and unburned HC and CO are discharged from the NOx absorbent 144, these unburned H
C and CO are oxidized by removing oxygen adsorbed and held by the catalyst 148, and as a result, unburned HC and CO are prevented from being released into the atmosphere.

The NOx releasing action from the NOx absorbent 144 is such that when a certain amount of NOx is absorbed by the NOx absorbent 144, for example, the NOx is absorbed to about 50% of the absorption capacity of the NOx absorbent 144. When 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 this 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 amount of NOx 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. For simplicity, the amount of NOx absorbed in the NOx absorbent 144 may be estimated from the cumulative value of the engine speed.

Next, the control of the rich spike in the engine will be described. FIG. 13 shows a routine executed by the electronic control unit 21 at regular 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 a stoichiometric air-fuel ratio or a rich air-fuel ratio, the routine exits from this routine without performing any particular control.

On the other hand, when Kt <1.0, that is, when the lean air-fuel mixture is being combusted, step 2
The result of adding ΣNE to the current engine speed NE is set as ΣNE. Therefore, ΣNE indicates the cumulative value of the engine speed NE. Next, in step 3, it is determined whether or not the cumulative rotation speed ΣNE is larger than a fixed value SNE. This constant value SNE is the NOx absorbent 14
FIG. 4 shows the cumulative rotational speed at which it is estimated that the NOx amount of, for example, 50% of the NOx absorbing capacity is absorbed. Σ
If NE ≦ SNE, the routine returns. If ΣNE> SNE, that is, if it is estimated that the NOx absorbent 144 has absorbed 50% of the NOx amount of the NOx absorbing capacity, the routine proceeds to step 4 where the NOx release flag is set. Is 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.

Next, at step 5, the count value C is set to 1
Is only incremented. Then, in step 6, it is determined whether or not the count value C has become larger than the fixed value C0, that is, for example, whether or not 0.5 seconds have elapsed. C ≦
When C> C0, the process returns. When C> C0, the routine proceeds to step 7, where the NOx release 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 controlled to be rich for 0.5 seconds. Next, at step 8, the accumulated rotational 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 intervals (or at constant crankshaft rotation angles). 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 determined whether or not the NOx release flag is set. If the NOx release flag is not set, steps 12 and 13
Then, the correction coefficient Kt is set to, for example, 0.7, and then the routine proceeds to step 14. In step 14, the 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, if it is determined in step 11 that the NOx release flag has been set, then in step 1
Proceeding to 5, the KK is calculated from the relationship shown in FIG. Next, at step 16, the value of the correction coefficient Kt is set to KK,
Proceed to step 14. Therefore, at this time, the mixture supplied to the cylinder is set to the rich air-fuel ratio.

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, it is preferable to install an air-fuel ratio sensor at the exhaust port 136 and correct the control value based on the detected actual air-fuel ratio.

Further, when performing a rich spike for temporarily setting the air-fuel ratio to the rich side during the lean operation, even if the air-fuel ratio of the mixture supplied to the cylinder is reduced, the combustion chamber 13
The air-fuel ratio of the air-fuel mixture within 1 may change with a delay.
This is because during lean operation, the wall surface of the intake port 134 is in a dry state, and when a mixture having a rich air-fuel ratio is supplied thereto, part of the fuel contained in the mixture adheres to the wall surface of the intake port, and 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 with a delay from the start of the rich spike control. Therefore, if the ignition timing is changed at the same time as the start of the rich spike control, the air-fuel ratio and the ignition timing may transiently become incompatible, and the fluctuation of the engine output torque may increase. In order to avoid such a situation beforehand, when changing the air-fuel ratio from lean to rich, or from rich to lean, change the ignition timing later to change the air-fuel ratio, or gradually change the ignition timing. It is preferable to change to. Alternatively, when the air-fuel ratio is changed 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. It is preferable to reduce the fuel injection amount at the start of the control so as to compensate for the shift. The transient control for switching the air-fuel ratio is specifically described in Japanese Patent Application Laid-Open No. Hei 6-193487.

As described above, the temporary increase of the air-fuel ratio for NOx release during the lean burn operation in which the air-fuel ratio of the engine 1 is increased, that is, the rich spike is caused by the engine operation such as the accumulated value of the engine speed. Implemented based on status. On the other hand, the shift in the automatic transmission 3 is performed based on the running state of the vehicle such as the vehicle speed and the throttle opening. Therefore, the rich spike in the engine 1 and the shift in the automatic transmission 3 may be determined at the same time. However, even if the ignition timing is controlled simultaneously during the rich spike, the engine output torque due to the change in the air-fuel ratio may be determined. It is difficult to eliminate the fluctuation, and it is necessary to set the engagement pressure of the friction engagement device at the time of gear shifting in the automatic transmission 3 in accordance with the engine output torque or the input torque based thereon.

Therefore, the control device according to the present invention performs control as described below in order to prevent the engine output torque and the engagement pressure of the friction engagement device from becoming incompatible with each other due to the rich spike. FIG. 15 shows an example of the control routine. After the input signal is processed (step 100), it is determined whether or not the range selected by the shift lever 31 is the drive range (D range). (Step 101). If the D range is not selected, the process exits this routine without performing any particular control. If the D range is selected, it is determined whether or not the lean burn control is being performed (lean burn operation is being performed). (Step 102).

In the lean burn control, the correction coefficient Kt of the basic fuel injection time TP in the engine 1 is set to "1.
This is an operation state in which the air-fuel ratio is set to a value larger than the stoichiometric air-fuel ratio by setting a value smaller than 0 "(for example, about 0.7). In a normal operation state, for example, the accumulated value of the engine speed is a predetermined value. , The above-described rich spike for temporarily lowering the air-fuel ratio is executed (Step 1).
If a negative determination is made in 02, this routine is exited without performing any particular control. If an affirmative determination is made, the routine proceeds to step 103, where a shift is determined.

The determination of the shift is, for example, a determination of an upshift from the second speed to the third speed. In the above-described automatic transmission 3 according to the present invention, the third brake B3 is released and the shift is determined. This is a so-called clutch-to-clutch shift in which the second brake B2 is engaged. In this clutch-to-clutch shift, the hydraulic pressure PB3 of the third brake B3 is directly controlled by the linear solenoid valve SLU according to the engine torque (input torque to the automatic transmission 3) and the engagement pressure of the second brake B2. In addition, the influence on the shift shock due to the fluctuation of the engine torque due to the rich spike increases.

Therefore, if a negative determination is made in step 103, the routine exits this routine without performing any particular control, and if an affirmative determination is made, an upshift from the second speed to the third speed is determined. It is determined whether or not the elapsed time from the point in time, that is, whether the timer TRE has reached a predetermined value TA (step 104). This time TA is a time that defines the point in time when the pressure adjustment of the third brake B3 is started. Therefore, when the determination in step 104 is affirmative, the pressure adjustment of the third brake B3 is started (step 10).
5).

The pressure adjustment of the third brake B3 at this time is as follows:
This is a control in which the hydraulic pressure is gradually reduced to the hydraulic pressure according to the input torque to the automatic transmission 3 and then maintained at the hydraulic pressure according to the input torque. Therefore, the input torque is detected as a premise of the pressure regulation control, and this is performed by conventionally known means. One example is disclosed in
The control described in Japanese Patent Application Publication No. 660 can be adopted. Specifically, the engine output is estimated from the amount of intake air per revolution of the engine 1, that is, the engine load Q / N, and the estimated value is consumed for driving the accessories and the loss due to oil agitation and the like. The torque obtained by subtracting the torque is input torque. The hydraulic pressure PB3 of the third brake B3 is determined according to the input torque obtained in this manner, and the duty ratio of the linear solenoid valve SLU is controlled so that the pressure becomes equal to the pressure PB3.

As described above, the engagement pressure P of the third brake B3
When the control of B3 is started, the rich spike in the engine 1 is prohibited (step 106). This step 10
Reference numeral 6 corresponds to rich spike prohibition means in the present invention.

In the above-described engine 1, the NOx release flag is set when the cumulative value エ ン ジ ン NE of the engine speed during the lean burn operation becomes equal to or greater than the above-mentioned reference value SNE, and the mixture is maintained for about 0.5 seconds. Is set to the rich air-fuel ratio KK, and the ignition timing is retarded at the same time.
After the pressure adjustment of the third brake B3 is started as described above, even if the accumulated value ΣNE of the engine speed exceeds the reference value SNE or the NOx release flag is set accordingly, the rich spike or the Accordingly, the ignition timing change control is not executed. Therefore, the third brake B
Since the engine torque, which is the basis of the pressure control of the engagement pressure PB3, does not fluctuate, it is possible to prevent the hydraulic pressure PB3 of the third brake B3 from becoming incompatible with the input torque, and the shift shock is accordingly caused. Is prevented.

With the increase of the engagement pressure PB2 of the second brake B2, the hydraulic pressure PB3 of the third brake B3 is gradually decreased, and finally the third brake B3 is released, and the pressure adjustment ends. In step 107, the end of the pressure adjustment is determined by timer control or the like, and the prohibition of the rich spike is continued until the pressure adjustment of the third brake B3 ends. And the third
When the pressure adjustment of the brake B3 is completed and the affirmative determination is made in step 107, the rich spike prohibition control is ended, and it is determined whether or not a request for rich spike has been made (step 108).

In the control of step 108, there is a request for a rich spike while the rich spike is prohibited due to the regulation of the hydraulic pressure PB3 of the third brake B3. Is to determine whether or not it is on hold. Therefore, this step 108
If a negative determination is made, the routine returns. If an affirmative determination is made, a rich spike is executed (step 1).
09).

The rich spike is a control for lowering the oxygen concentration in the exhaust gas flowing into the NOx absorbent 144 to release NOx from the NOx absorbent 144.
The release amount varies depending on the oxygen concentration in the inflowing exhaust gas, the duration of the rich spike, and the like. NOx absorbent 1
The degree of saturation of the NOx absorption capacity at 44 becomes higher as the time during which the rich spike is not executed becomes longer. Therefore, when the rich spike is requested while the rich spike is prohibited and the affirmative determination is made in step 108, and the rich spike is executed in step 109,
The control amount is made larger than in the normal case, that is, when the rich spike is not prohibited. Specifically, the execution time (for example, 0.5 seconds) of the normal rich spike is lengthened. Alternatively, the fuel injection time correction coefficient Kt is set to a large value.

By controlling in this way, NOx absorbed more than usual due to prohibition of rich spikes
Is released from the NOx absorbent 144 as necessary
The NOx absorption capacity of the absorbent 144 is restored to the original state. Therefore, this step 109 includes the means for changing the control amount of the rich spike in the present invention.

If a negative determination is made in step 104, that is, if the elapsed time TRE from when the upshift from the second speed to the third speed is determined has not reached the predetermined reference time TA, the rich state is determined. A spike permission control is executed (step 110). That is, when the accumulated value of the engine speed reaches a predetermined reference value and the NOx release flag is set, the state is set to execute the rich spike (normal state).

The example shown in FIG. 15 described above is an example in which only the hydraulic pressure PB3 of the third brake B3, which is one of the frictional engagement devices in the clutch-to-clutch shift, is controlled based on the input torque. , So the third
The prohibition of the rich spike is released when the pressure adjustment of the hydraulic pressure PB3 of the brake B3 is completed. However, in the case of a clutch-to-clutch shift, the hydraulic pressure of both friction engagement devices (in the above example, the second brake B2 and the third brake B3) involved in the shift may be controlled based on the input torque. In such a case, in step 107, the end of the shift is determined in place of the determination of the end of the hydraulic pressure PB3 of the third brake B3. Therefore, the inhibition of the rich spike is postponed until the end of the shift. Will be done. Further, in this case, it is preferable that the control amount when executing the rich spike suspended with the execution of the prohibition control be further larger than that in the above example.

In the above-described example, when the engine torque or the input torque of the automatic transmission 3 is detected in performing the shift, the rich spike is prohibited, so that the oil pressure associated with the shift and the engine torque or the input torque do not match. However, the correction of the mismatch between the oil pressure of the friction engagement device and the engine torque or the input torque of the automatic transmission at the time of shifting is different from the above-described example, and is performed as follows. May go.

The control routine shown in FIG. 16 adds the variation caused by the rich spike as a correction term to the detection or estimation of the engine torque or the input torque of the automatic transmission, thereby obtaining the hydraulic pressure of the friction engagement device involved in the shift. This is configured to correct the incompatibility with the engine torque or the input torque. In FIG.
The control is performed in the same manner as shown in FIG. Then, after the elapsed time TRE from the determination of the upshift from the second speed to the third speed reaches the predetermined reference time TA, the pressure adjustment of the hydraulic pressure PB3 of the third brake B3 is started (step 105). Next, it is determined whether or not there is a request for a rich spike (step 111). Specifically, it is determined whether or not the above-mentioned NOx release flag is set.

Step 1 upon request of rich spike
If a positive determination is made in step 11, the third brake B
Even during the pressure adjustment of the third hydraulic pressure PB3, the rich spike is executed (step 112). That is, the air-fuel ratio is temporarily set to a value smaller than the stoichiometric air-fuel ratio.

At the same time, a correction is made by executing a rich spike to detect the engine torque or the input torque (step 113). This step 113 corresponds to the engine output correcting means in the present invention. Specifically, as described in Japanese Patent Application Laid-Open No. Hei 5-77660, the engine torque is determined by the amount of intake air per revolution, that is, the engine load Q / N, the intake pipe negative pressure PM, or the intake air amount GN. The map value is experimentally obtained based on the engine speed NE, and the map value is stored in the electronic control unit 21. When a rich spike is executed, a correction term corresponding thereto is added. The value of the correction term is experimentally obtained in advance and stored in the electronic control unit 21 in the form of a map value, and the map value is read and used according to the running state of the vehicle at the time of execution of the rich spike and the shift. . Naturally, in this case, the map value takes into account the value when the torque correction is performed by changing the ignition timing due to the rich spike and the value when the torque correction is performed by the transient change in the fuel injection amount. Therefore, at least two types of map values are prepared as map values so as to be adapted when the torque correction is performed.

Next, the engine torque or the input torque to the automatic transmission is calculated (step 114), and the hydraulic pressure PB3 of the third brake B3 is determined based on the calculated value (step 115). It is needless to say that the linear solenoid valve SLU is controlled so as to have the value determined in this manner.

Therefore, if the control shown in FIG. 16 is performed, the rich spike is executed simultaneously with the detection of the engine torque or the input torque to the automatic transmission at the time of shifting, and the correction of the torque based on the rich spike is performed. Therefore, there is almost no difference between the actual torque of the engine torque or the input torque, which is the basis for determining the oil pressure of the friction engagement device, and therefore, the mismatch between the oil pressure and the torque of the friction engagement device is prevented, and as a result, , Shifting shock becomes better.

In the control shown in FIG. 16, when the hydraulic pressures of the two friction engagement devices involved in the shift are simultaneously controlled at the time of the clutch-to-clutch shift, it is determined as described above. Based on the engine torque or the input torque, the oil pressure of both friction engagement devices is determined.

Here, the control shown in FIG.
If the time chart when the control shown in 6 is performed is shown,
As shown in FIG. When the control shown in FIG. 15 is performed, the rich spike during the pressure adjustment of the hydraulic pressure PB3 of the third brake B3 (that is, during the detection of the torque) is prohibited. Instead, the rich spike is executed after the pressure adjustment is completed. Therefore, the air-fuel ratio A / F changes as shown by the solid line in FIG. On the other hand, when the control shown in FIG. 16 is performed,
Since the rich spike is performed even during the adjustment of the hydraulic pressure PB3 of the third brake B3, the air-fuel ratio A / F changes as shown by the broken line in FIG. Of these rich spikes,
In the rich spike shown in FIG. 15, the time Ts1 of the rich spike is set to be longer than the time Ts2 in the case of the control shown in FIG.

The present invention has been described with reference to the specific examples. However, the present invention is not limited to the above examples. The automatic transmission to which the present invention is applied includes the gear train shown in FIG. 1 and the gear train shown in FIG. A gear train or a hydraulic circuit other than the hydraulic circuit may be provided. The shift that temporally overlaps with the rich spike is not limited to the clutch-to-clutch shift between the third speed and the second speed, and is described above when the rich spike overlaps with another general shift. Control may be performed in the same manner as in each example. Further, the means for detecting (estimating) the engine torque and the input torque of the automatic transmission is not limited to those described in the above embodiment, and any appropriate means can be adopted as necessary, and the torque fluctuation accompanying the rich spike can be reduced. What is necessary is just to add or subtract as a correction value.

[0102]

As described above, according to the first aspect of the present invention, when controlling the hydraulic pressure of the friction engagement device involved in shifting based on the engine torque, when the engine torque is detected or estimated, Since the rich spike that temporarily reduces the air-fuel ratio is not performed, the detected value of the engine torque is accurate, and therefore, mismatch between the oil pressure of the friction engagement device and the engine torque or the input torque to the automatic transmission is prevented. As a result, a shift shock is improved, and a decrease in durability due to slippage of the friction engagement device is prevented.

According to the second aspect of the present invention, if the execution of the rich spike is suspended and the NOx absorption continuation time becomes long, the control amount of the next rich spike is changed accordingly. The NOx absorbing ability of the agent can be sufficiently restored in the same manner as when a normal rich spike is executed.

Further, according to the third aspect of the present invention, when a rich spike is executed at the time of detecting an engine torque for determining the oil pressure of the friction engagement device, a variation in torque caused by the rich spike is used as a correction amount. Incorporating into torque detection, the value obtained is equal to the actual torque value, as a result of which the mismatch between the hydraulic pressure of the frictional engagement device and the engine torque on which it is determined is corrected,
Therefore, in the present invention as well, the shift shock can be improved and the durability of the friction engagement device can be improved as in the first aspect of the invention.

According to the fourth aspect of the present invention, the ignition timing change control for reducing the engine torque is executed in conjunction with the rich spike. As a result, an increase factor and a decrease factor of the engine torque occur simultaneously. It is possible to prevent or suppress the increase or fluctuation of the engine torque due to the spike.

[Brief description of the drawings]

FIG. 1 is a skeleton diagram showing an example of a gear train of an automatic transmission according to 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 hydraulic circuit diagram showing a portion of the hydraulic circuit for mainly controlling a second brake and a third brake.

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

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

FIG. 8 is a diagram schematically showing the concentrations of unburned HC, CO, and oxygen in exhaust gas discharged from an engine.

FIG. 9 is a view for explaining the 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 control for releasing NOx from a NOx absorbent.

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

FIG. 15 is a flowchart illustrating an example of rich spike prohibition control during hydraulic pressure adjustment of the friction engagement device.

FIG. 16 is another flowchart illustrating a control example for correcting a torque variation due to a rich spike.

FIG. 17 is a time chart when a rich spike is performed after adjusting the hydraulic pressure of the friction engagement device and when a rich spike is performed during the pressure adjustment.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Engine, 3 ... Automatic transmission, 21 ... Engine electronic control device, 33 ... Shift electronic control device.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification code FI Theme coat ゛ (Reference) F02P 5/15 F16H 61/02 F16H 61/02 59:14 // F16H 59:14 59:74 59:74 F02P 5/15 B

Claims (4)

[Claims] At a predetermined time during a lean burn operation in which the air-fuel ratio of an air-fuel mixture supplied to an engine is increased, a rich spike is executed to temporarily reduce the air-fuel ratio to thereby reduce NOx from NOx absorbent in the exhaust passage. And performs control to suppress an increase in engine torque due to the rich spike. Based on the detected engine torque, the hydraulic pressure of the friction engagement device at the time of shifting in the automatic transmission connected to the engine is controlled. A control device for an engine and an automatic transmission to be set, comprising: a rich spike inhibiting means for inhibiting a rich spike that temporarily reduces the air-fuel ratio while detecting the engine torque. Machine control device. 2. The control device for an engine and an automatic transmission according to claim 1, further comprising means for changing a control amount of the rich spike depending on whether or not the rich spike is prohibited. 3. At a predetermined time during a lean burn operation in which the air-fuel ratio of the air-fuel mixture supplied to the engine is increased, a rich spike is executed to temporarily reduce the air-fuel ratio to thereby reduce NOx from the NOx absorbent in the exhaust passage. And performs control to suppress an increase in engine torque due to the rich spike. Based on the detected engine torque, the hydraulic pressure of the friction engagement device at the time of shifting in the automatic transmission connected to the engine is controlled. In the control device for the engine and the automatic transmission to be set, there is provided means for correcting the engine torque value detected to set the oil pressure according to a variation amount of the engine torque due to the execution of the rich spike. A control device for an engine and an automatic transmission. 4. The control according to claim 1, wherein the control for suppressing an increase in the engine torque due to the rich spike is a control for changing an ignition timing so that the engine torque is reduced. Engine and automatic transmission control device.