JPH09240322A - Controller for vehicular power train - Google Patents

Abstract

PROBLEM TO BE SOLVED: To maintain a target fuel-air ratio so as to reduce fuel costs and improve exhaust cleaning performance by setting the target fuel-air ratio according to target engine torque and an engine revolving speed and controlling the quantify of air taken in and the quantity of fuel supplied to an engine based on the set ratio. SOLUTION: A target fuel-air ratio calculating part E calculates a target fuel-air ration t1/λ based on target engine torque the and an engine revolution speed Ne and a fuel correction rate calculating part F calculates a fuel correction rate FCrate based on the target fuel-air ration t1/λ and the engine revolution speed Ne. Further, the air intake quantity of an engine is controlled based on a target taken-in air quantity obtained by multiplying of the fuel correction rate FCrate. A target fuel quantity calculating part D calculates a target fuel quantity tQf based on the target engine torque the and the engine revolution speed Ne and controls the fuel supply quantity of the engine. Thus, by maintaining the target fuel-air ratio, fuel costs are reduced and exhaust performance is improved.

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 a vehicle power train including an engine capable of controlling a fuel-air ratio in a wide range and an automatic transmission (including a continuously variable transmission) connected to the engine. , A technology for comprehensively controlling the intake air amount, the fuel supply amount, the fuel-air ratio, and the gear ratio to optimally control the fuel consumption, the exhaust gas, and the drivability in a well-balanced manner.

[0002]

2. Description of the Related Art As a conventional vehicle powertrain control device of this type, there is, for example, one disclosed in Japanese Patent Laid-Open No. 62-110536.

[0003]

However, in such a conventional control device, based on the accelerator operation amount,
The target vehicle driving force, the target gear ratio, and the target engine torque are obtained, and the throttle actuator opening is simply controlled by the throttle actuator so as to obtain the target engine torque.
(In a diesel engine, the fuel injection amount is controlled by the fuel injection pump.) Therefore, the desired torque cannot be obtained in the case of an engine in which the fuel-air ratio is controlled in a wide range.

Further, when the target fuel-air ratio is decided by giving priority to the engine torque, there is a problem that fuel consumption and exhaust gas are deteriorated and the fuel and air amounts cannot be controlled in a good balance as they are. The present invention has been made in view of such conventional problems, and an object thereof is to control the engine torque to a target value while maintaining the fuel-air ratio at the target value.

[0005]

Therefore, the invention according to claim 1 controls a vehicle power train including an engine capable of controlling a fuel-air ratio in a wide range and an automatic transmission connected to the engine. In the apparatus, a target value of the driving force at the outlet of the automatic transmission and a gear ratio, and a target engine torque at which the target value is obtained are set, while a target fuel air amount is set according to the target engine torque and the engine rotation speed. Set the ratio,
The intake air amount and the fuel supply amount to the engine are controlled so that the target engine torque and the target fuel-air ratio can be obtained.

Further, according to the second aspect of the present invention, as shown in FIG. 1, the fuel-air ratio can be controlled in a wide range, and the opening degree of the throttle valve provided in the intake system of the engine is set to a target value. Vehicle power train including an engine having a throttle valve control device for controlling the fuel amount control device for controlling the amount of fuel supplied to the engine to a target value, and an automatic transmission connected to the engine In this control device, an accelerator operation amount detecting means for detecting an accelerator operation amount, a vehicle speed detecting means for detecting a vehicle speed, an engine rotation speed detecting means for detecting an engine rotation speed, and an intake air amount for detecting an intake air amount to the engine. An air amount detecting means, a target driving force / gear ratio calculating means for calculating a target driving force and a target gear ratio at the transmission outlet based on the detected accelerator operation amount and vehicle speed, and the transmission. A target driving force and the target speed ratio of the mouth,
Target engine torque calculating means for calculating a target engine torque based on a ratio between the engine speed and the transmission inlet speed, and a target for calculating a target fuel-air ratio based on the target engine torque and the engine speed. Fuel-air ratio calculation means, target intake air amount calculation means for calculating a target intake air amount of the engine based on the target engine torque, engine rotation speed, and target fuel-air ratio, the target intake air amount and engine rotation speed Fuel supply based on the target throttle valve opening calculation means for calculating the target throttle valve opening based on the above, and the intake air amount, engine rotation speed and target air-fuel ratio detected by the intake air amount detection means. A fuel supply amount calculating means for calculating an amount, and the throttle valve control device is configured to adjust the throttle valve control device to the calculated target throttle valve opening degree. Controls the opening of the throttle valve, the fuel supply amount control apparatus controls the fuel supply amount so that the calculated fuel supply amount, and controlling the engine torque to the target value.

Further, in the invention according to claim 3, the target intake air amount calculation means calculates a target fuel supply amount based on the target engine torque and the engine rotation speed, and the target fuel supply amount is the target fuel supply amount. The target intake air amount is calculated by dividing by the fuel air ratio. Further, the invention according to claim 4 is characterized in that the target intake air amount calculation means obtains the target intake air amount by performing correction according to engine friction and pump loss.

[0008]

According to the first aspect of the present invention, it is possible to obtain the required engine torque and ensure good driving performance while maintaining the target fuel-air ratio and satisfying fuel consumption and exhaust gas purification performance. Further, according to the invention of claim 2, the target fuel-air ratio is obtained based on the target engine torque and the engine rotation speed, and the target intake air amount is adjusted so that the target engine torque and the target fuel-air ratio are satisfied. Is calculated.

By controlling the throttle valve opening to the target throttle valve opening by the throttle valve control device, the intake air amount is controlled so as to approach the target intake air amount. The fuel supply amount corresponding to the target fuel-air ratio can be obtained by multiplying the intake air amount thus determined by the target fuel-air ratio, and the fuel supply control device controls the fuel supply amount to be the fuel supply amount. The target fuel-air ratio can be controlled accurately.

According to the third aspect of the invention, if the target engine torque and the engine rotation speed are determined, the target air-fuel ratio is also determined. Therefore, the target intake air amount is calculated from the target engine torque and the engine rotation speed. It is possible to directly calculate by taking the factor of the sky ratio into consideration. However, if the amount of change in the target air-fuel ratio is large, the amount of data required to calculate the target intake air amount increases.

On the other hand, when the target fuel supply amount is calculated based on the target engine torque and the engine rotation speed, the change margin of the target fuel supply amount due to the engine rotation speed is small.
Therefore, the amount of data required for the calculation can be small.
Once the target fuel supply amount is obtained, the target intake air amount is uniquely determined by simply dividing the target fuel supply amount by the target fuel-air ratio. is there.

According to the fourth aspect of the invention, when the fuel-air ratio is made lean, the throttle loss (pump loss) due to the increase in the throttle valve opening is reduced, and the fuel consumption rate is improved. Further, the engine friction changes depending on the target engine torque and the engine rotation speed. Therefore, the target intake air amount can be set to a more appropriate value by correcting the target intake air amount in consideration of the torque loss due to the engine friction and the pump loss.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 2 shows a system configuration (common to each control embodiment to be described later) of an embodiment of the present invention. The engine 1 is an in-cylinder direct injection gasoline engine having a fuel injection valve 2 in the combustion chamber. By injecting fuel directly into the cylinder and switching the injection timing and injection amount,
It is possible to realize stratification and homogeneous combustion of the engine 1 and control the air-fuel ratio in a wide range.

However, the engine may be a so-called lean burn engine in which a fuel injection valve is attached so as to inject fuel into the intake port and the gas flow of intake air is controlled to control the air-fuel ratio in a wide range. The engine 1 is provided with a spark plug 3 which is mounted in a combustion chamber for ignition, and an intake passage 4 of the engine 1 is provided with a throttle valve 5 for electronically controlling the opening degree of the throttle valve 5. A controllable throttle valve control device 6 is provided.

An automatic transmission 7 is attached to the output shaft of the engine 1.
Are linked. Here, although the automatic transmission 7 includes the torque converter 7a, it may be a continuously variable transmission,
It is sufficient that the gear ratio can be automatically controlled. The accelerator operation amount sensor 8 serving as an accelerator operation amount detecting means indicates the amount of depression of the accelerator pedal depressed by the driver as the engine load (engine torque) desired by the driver.
Detected as An acceleration / deceleration sensor or the like can be used instead of this sensor as long as it detects the driver's intention of acceleration / deceleration.

An air flow meter 9 as an intake air amount detecting means detects an intake air amount into the engine 1 (intake air amount per unit time = intake air flow rate). It should be noted that a negative pressure sensor for detecting the intake negative pressure is used in place of the air flow meter in the engine of the system in which the fuel injection amount is controlled according to the intake negative pressure. The throttle sensor 10 detects the opening degree of the throttle valve 5 driven by the throttle valve control device 6.

A crank angle sensor 11 as an engine speed detecting means generates a position signal for each unit crank angle and a reference signal for each cylinder stroke phase difference, and measures the number of generated position signals per unit time. Due to
Or by measuring the reference signal generation period,
The engine speed can be detected. Besides, on the engine 1 side, a water temperature sensor 1 for detecting the temperature of the cooling water of the engine 1
2. An air-fuel ratio sensor 13 is provided which outputs a signal proportional to the oxygen concentration in the exhaust gas to detect the air-fuel ratio of the air-fuel mixture in a wide range. The air-fuel ratio sensor 13 is necessary for feedback control of the air-fuel ratio, but it detects the ternary point by using a so-called oxygen sensor that distinguishes only rich lean from the theoretical air-fuel ratio, and the air at that time is detected. It is also possible to estimate the lean to rich air-fuel ratio from the amount and the fuel amount.

A vehicle speed sensor 14 for detecting the vehicle speed by detecting the rotation speed of the output shaft of the automatic transmission 7 is provided. A PCM (Powertrain Control Module) 15 is composed of a microcomputer and inputs detection signals from the various sensors to integrally control the engine 1 and the automatic transmission 7. FIG. 3 shows a functional configuration of the PCM.

The output target driving force calculation unit A inputs the accelerator operation amount signal Acc from the accelerator operation amount sensor 8 and the vehicle speed signal Vsp from the vehicle speed sensor 14, and based on these signals, the automatic transmission 7 The output target driving force tTd of is calculated from the map or by an arithmetic expression. The target gear ratio calculation unit B similarly uses the accelerator operation amount signal Acc and the vehicle speed signal Vsp to set the target gear ratio Gr of the automatic transmission 7.
Is obtained by searching the map.

The torque converter torque ratio calculation unit C calculates the engine speed Ne obtained from the crank angle sensor 11, the automatic transmission 7 obtained from the vehicle speed signal Vsp and the target gear ratio Gr.
Of the torque converter 7a based on the inlet rotation speed Nt of
The torque ratio Rtq of is calculated from the table or by an arithmetic expression. By dividing the output target driving force tTd by the target gear ratio Gr and the torque ratio Rtq,
The target engine torque tTe is uniquely obtained. Further, when the continuously variable transmission is used as the automatic transmission and the gear ratio is continuously set, the target engine torque tTe is also uniquely determined.

Next, a method of controlling the engine torque based on the target engine torque tTe will be described. The target fuel amount calculation unit D determines the target engine torque tTe.
The target fuel amount tQf is obtained by a map or an arithmetic expression based on the engine speed Ne and the engine speed Ne. Target fuel-air ratio calculator E
Calculates the target fuel-air ratio t1 / λ by a map or a calculation formula based on the target engine torque tTe and the engine rotation speed Ne.

The fuel consumption correction rate calculation unit F is arranged to
Based on 1 / λ and the engine rotation speed Ne, the fuel consumption correction rate FCrate is obtained by a map or an arithmetic expression. The target fuel amount tQf is divided by the target fuel-air ratio t1 / λ to obtain the first target air amount tQa, and the fuel consumption correction rate FCra is further calculated.
The second target intake air amount t in which engine friction and torque loss corresponding to pump loss are corrected by multiplying by te
Qa2 is obtained.

As described above, in order to determine the target intake air amount tQa2 in consideration of the target fuel-air ratio t1 / λ, engine friction, and pump loss, the torque that is intended by the driver is satisfied under all engine operating conditions. The target engine torque tTe and the output target driving force tTd can be realized. Further, when the torque loss corresponding to the engine friction and the pump loss is relatively small with respect to the torque generated by the engine 1, the correction by the fuel consumption correction rate FCrate can be omitted.

The target throttle opening area calculation unit G obtains the target throttle opening area tAair from the target intake air amount tQa2 and the engine speed Ne by a map or a calculation formula. The target throttle valve opening calculation unit H calculates the target throttle valve opening tTVO from a table or a calculation formula based on the target throttle opening area tAair.

The calculated target throttle valve opening tT
The VO signal is output to the throttle valve control device 6, and the throttle valve control device 6 causes the opening of the throttle valve 5 to match the target throttle valve opening tTVO.
Drive the throttle valve 5. As a result, the intake air amount of the engine can be controlled to the target intake air amount tQa2.

On the other hand, the first basic fuel injection amount T _P obtained based on the intake air amount Q detected by the air flow meter 9 and the target fuel-air ratio t1 / λ are added to the first basic fuel injection amount T _P. The second basic fuel injection amount tT _P 2 corresponding to the target fuel-air ratio t1 / λ is obtained by multiplication, and a signal with various known corrections is output to the fuel injection valve 2 as a fuel injection valve opening signal. To do.

As a result, the target fuel quantity tQf can be obtained as to the fuel quantity. As a result, even in an engine that controls the air-fuel ratio in a wide range to improve fuel economy and exhaust gas purification, the target driving force and target of the vehicle are adjusted according to the accelerator operation amount, that is, the driver's intention and degree of acceleration / deceleration. The gear ratio can be set, and the intake air amount and the fuel amount can be controlled to their respective target values so as to simultaneously satisfy the target engine torque and the target air-fuel ratio required to obtain them, and thus the vehicle It is possible to improve both the driving performance of the engine and the improvement of fuel efficiency and exhaust gas purification of the engine.

Further, in this embodiment, since the correction is performed in consideration of the torque loss amount due to the engine friction and the pump loss, the control accuracy is enhanced, and particularly, the operation is performed in the high speed and high load region where the influence of the torque loss is large. It is possible to improve the property. Next, another embodiment will be described based on FIG. In the present embodiment, the parts shown in FIG. 3 are the same as those in the first embodiment, and therefore the description thereof will be omitted. In FIG. 5, the same parts as those in FIG. 4 will be designated by the same reference numerals, and only different parts will be described. To do.

That is, in the present embodiment, in contrast to the first embodiment, the intake air amount signal from the air flow meter 9 is compared with the air amount first-order delay calculation unit I in consideration of the dynamics of the intake system.
In step 1, the basic fuel injection amount T _P is calculated by using the signal corrected for the first-order delay. Further, the target fuel-air ratio t1 / λ calculated by the target fuel-air ratio calculation unit E is also subjected to first-order delay correction by the fuel-air ratio first-order delay calculation unit J, and the corrected signal is corrected by the fuel-air ratio correction calculation unit K. Then, it is further corrected by the time change amount ΔAcc of the accelerator operation amount Acc.

Then, the second basic fuel injection amount tT is obtained by multiplying the basic fuel injection amount T _P based on the first-order-lag-corrected air amount signal by the two corrected target fuel-air ratios t1 / λ. _{Find P.} In this way, the target fuel-air ratio t1 / λ is delayed so as to correspond to the response delay of the intake air amount when the target fuel-air ratio t1 / λ changes, and the accelerator operation amount time By correcting the change in the target fuel-air ratio t1 / λ due to the change amount as well, it is possible to prevent a torque step difference during a transition and improve the exhaust gas purification performance during a transition.

[Brief description of drawings]

FIG. 1 is a block diagram showing the configuration and functions of the invention according to claim 2;

FIG. 2 is a diagram showing a system configuration of an embodiment of the present invention.

FIG. 3 is a block diagram showing a functional configuration of the first embodiment.

FIG. 4 is a block diagram showing a functional configuration of the first embodiment.

FIG. 5 is a block diagram showing a functional configuration of a second embodiment.

[Explanation of symbols]

 1 engine 2 fuel injection valve 5 throttle valve 6 throttle valve control device 7 automatic transmission 8 accelerator operation amount sensor 9 air flow meter 10 throttle sensor 11 crank angle sensor 13 air-fuel ratio sensor 14 vehicle speed sensor 15 PCM A output target driving force calculation unit B Target gear ratio calculation unit D Target fuel amount calculation unit E Target fuel-air ratio calculation unit F Fuel consumption correction ratio calculation unit G Target throttle opening area calculation unit H Target throttle valve opening calculation unit I Air amount first-order delay calculation unit J Fuel-air ratio First-order delay calculation unit K Fuel-air ratio correction calculation unit

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Masaaki Uchida 2 Takaracho, Kanagawa-ku, Yokohama-shi, Kanagawa Nissan Motor Co., Ltd.

Claims (4)

[Claims] 1. An engine capable of controlling a fuel-air ratio in a wide range,
In a control device for a vehicle powertrain including an automatic transmission connected to the engine, a target value of a driving force and a gear ratio at the automatic transmission outlet, and a target engine torque for obtaining the target value are set. On the other hand, a target fuel-air ratio is set according to the target engine torque and the engine rotation speed, and the intake air amount and the fuel supply amount to the engine are set so that the target engine torque and the target fuel-air ratio are obtained. A control device for a vehicle power train, which controls the vehicle. 2. A throttle valve control device capable of controlling a fuel-air ratio in a wide range and controlling an opening of a throttle valve interposed in an intake system of an engine to a target value, and a fuel amount supplied to the engine. A fuel supply amount control device for controlling the
A vehicle powertrain control device including an engine having an engine and an automatic transmission connected to the engine, comprising: an accelerator operation amount detecting means for detecting an accelerator operation amount; a vehicle speed detecting means for detecting a vehicle speed; An engine rotation speed detecting means for detecting a rotation speed, an intake air amount detecting means for detecting an intake air amount to the engine, a target driving force and a target at a transmission outlet based on the detected accelerator operation amount and vehicle speed. A target driving force / gear ratio calculating means for calculating a gear ratio, a target driving force and a target gear ratio at the transmission outlet, and a target engine torque based on a ratio of an engine rotational speed and a transmission inlet rotational speed. Target engine torque calculating means for calculating; target fuel-air ratio calculating means for calculating a target fuel-air ratio based on the target engine torque and engine rotation speed; Based on the target intake air amount and the engine rotation speed, a target intake air amount calculation means for calculating a target intake air amount of the engine based on the target engine torque, the engine rotation speed and the target fuel-air ratio,
A target throttle valve opening calculation means for calculating the target throttle valve opening, and a fuel supply quantity is calculated based on the intake air quantity, the engine rotation speed, and the target fuel-air ratio detected by the intake air quantity detection means. And a fuel supply amount calculation means, wherein the throttle valve control device controls the opening amount of the throttle valve so as to reach the calculated target throttle valve opening amount, and the fuel supply amount control device includes A control device for a vehicle power train, wherein the fuel supply amount is controlled so as to be the calculated fuel supply amount, and the engine torque is controlled to a target value. 3. The target intake air amount calculation means calculates a target fuel supply amount based on the target engine torque and engine rotation speed, and divides the target fuel supply amount by the target fuel-air ratio. The control device for a vehicle powertrain according to claim 2, wherein a target intake air amount is calculated. . 4. The vehicle powertrain according to claim 2, wherein the target intake air amount calculation means obtains the target intake air amount by performing correction according to engine friction and pump loss. Control device.