JP4747629B2 - Vehicle control device - Google Patents

Description

  The present invention relates to a control device for a vehicle equipped with an internal combustion engine and an automatic transmission, and more particularly, to a control device that reduces a shock that occurs when returning from a fuel cut.

  Control to stop the fuel supply to the engine during so-called decelerating (engine idling state) to improve the fuel efficiency of the internal combustion engine (engine) mounted on the vehicle, so-called fuel cut control, improves driving performance and ride comfort. This is a control that improves fuel efficiency by reducing the supply of fuel to the engine as much as possible within a range that is not impaired. In general, during deceleration of the engine in an idling state, the fuel supply is stopped because the vehicle speed and the engine speed are predetermined conditions.

  Specifically, the fuel supply is stopped when the throttle valve is closed during traveling and the vehicle speed and engine speed are equal to or greater than a predetermined value. Further, when the vehicle speed and the engine speed decrease and reach the return speed that defines the lower limit, the fuel supply is resumed. The return condition from the fuel cut is set so as not to cause an engine stall and to maintain a stable rotation of the engine. From the viewpoint of improving fuel efficiency, it is desirable that the return rotational speed from the fuel cut is set low and the fuel cut is performed for as long as possible.

  Furthermore, an automatic transmission for a vehicle includes a fluid coupling connected to the output shaft of the engine and a gear-type stepped transmission mechanism or a belt-type or traction-type continuously variable transmission mechanism connected to the output shaft. There is much to be done. As the fluid coupling, there is a torque converter, and many of the torque converters include a lock-up clutch. The lock-up clutch mechanically directly connects a drive-side member (engine-side pump impeller) and a driven-side member (transmission mechanism-side turbine liner) of the torque converter. Therefore, both improvement in fuel consumption and riding comfort can be achieved. A lockup region in which such a lockup clutch is engaged is set based on, for example, the vehicle speed and the throttle opening.

  Japanese Patent Laying-Open No. 2004-136770 (Patent Document 1) discloses a deceleration control device for a vehicle that performs lock-up control during deceleration by fully closing an accelerator opening and cuts fuel. This vehicle deceleration control device includes an engine speed detecting means for detecting the engine speed, an accelerator opening detecting means for detecting the accelerator opening, and an actual lockup state from the time when the lockup release command signal is output. When the elapsed time until release is defined as the lock-up release delay, the lock-up release engine speed initial value that presets the lock-up release engine speed initial value based on the state where the lock-up release delay is large Setting means, lock-up release delay time measuring means for measuring the lock-up release delay time when the lock-up is released, and the set lock-up release engine speed based on the measured lock-up release delay time at a low speed The lockup release engine speed changing means to change to the number side, the accelerator opening is fully closed, the engine A lockup release control means for outputting a lockup release command signal when the rotation speed detection value falls below the set lockup release engine speed, and an actual detection for detecting that the lockup state has actually been released. It has a lockup release detection means and a fuel cut recovery control means for recovering the fuel cut after the lockup state is actually released.

According to this deceleration control device for a vehicle, in lock-up release control, the lock-up release engine speed is changed to a lower speed side as the lock-up release delay is smaller, based on a state where the lock-up release delay is large. In order to expand the lockup range when the accelerator is fully closed and to make the fuel cut recovery condition to release the actual lockup state in the fuel cut recovery control, the fuel consumption improvement fee is not affected regardless of variations in the lockup release delay. In addition, it is possible to achieve both avoidance of engine stall and avoidance of recovery shock.
JP 2004-136770 A

  Generally, ISC (Idle Speed Control) control is performed in an engine. This ISC control is control for maintaining the idling speed of the engine at a constant speed. Specifically, an air passage that bypasses the throttle valve of the engine is provided, and the idling speed is controlled by driving the throttle amount of the passage by an actuator and adjusting the air (mixture) flow rate. In this ISC control device, feedback control is performed in order to bring the rotational speed at idling closer to the target value. Thereby, the rotation speed can be kept substantially constant.

  In feedback control, the air flow rate required to maintain the engine idling speed at a constant speed changes depending on factors such as individual differences and changes over time. So-called learning control is performed to reflect and store feedback results. It is. Usually, the initial value of the learning value of the idling air flow rate is set to a larger value in order to avoid engine stall. When learning is not completed, ISC control is performed with this initial value. In other words, until this learning is completed, control using the initial value is performed, and the engine idling speed is set to a higher setting.

  In the vehicle deceleration control device disclosed in Patent Document 1, the fuel cut is recovered after the lockup is released by the fuel cut recovering means. However, Patent Document 1 does not consider whether learning in ISC control is completed or not. For this reason, the following problems occur. When learning is not completed in the ISC control, the idling speed is set higher. When the fuel cut is restored in this state and the lock-up clutch is released, the engine speed increases to a higher idling speed, causing the driver to feel a shock and drivability to deteriorate. Have the problem of Such a problem at the time of return from fuel cut when ISC learning control is not completed is not mentioned in Patent Document 1.

  The present invention has been made to solve the above-described problem, and the object thereof is to suppress a shock that occurs at the time of return from the fuel cut even when the ISC learning control is incomplete. It is to provide a control device for a vehicle.

  A vehicle control apparatus according to a first invention includes an internal combustion engine, a fluid coupling connected to an output shaft of the internal combustion engine, and an automatic transmission including a mechanical element that mechanically connects an input / output shaft of the fluid coupling. Control the vehicle. The control device includes a learning control means for learning and controlling the idling speed of the internal combustion engine by adjusting the air flow rate, a judging means for judging whether or not learning by the learning control means is completed, When the running condition satisfies a predetermined start condition, the fuel supply to the internal combustion engine is stopped and the mechanical connection of the input / output shaft of the fluid coupling by the mechanical element is started, so that the running condition of the vehicle is predetermined. When the return condition is satisfied, the fuel supply to the internal combustion engine is restarted, and the fuel cut execution means for releasing the mechanical connection of the input / output shaft of the fluid coupling by the machine element, and for changing the predetermined condition Change means. The changing means includes means for changing the return condition to a condition that makes it easy to return from the fuel cut when the determining means determines that learning has not been completed.

  According to the first aspect of the present invention, when the fuel cut execution means satisfies the start condition (the vehicle speed or the internal combustion engine speed is equal to or higher than the fuel cut start threshold value) when the running state of the vehicle satisfies a predetermined start condition, At the same time, the mechanical connection of the input / output shaft of the fluid coupling (torque converter) by the mechanical element (lock-up clutch) is started and the running state of the vehicle is set to a predetermined return condition (vehicle speed and internal combustion engine speed When the fuel cut return threshold value is satisfied, the fuel supply to the internal combustion engine is resumed and the mechanical connection of the input / output shaft of the torque converter by the lock-up clutch is released. When the ISC learning control is not completed, the return condition from the fuel cut is changed to a condition that makes it easy to return. For example, even when the vehicle speed or the internal combustion engine speed is high, the return from the fuel cut is performed. In this way, when the ISC learning control is not completed, it is easy to return from the fuel cut (increase the return vehicle speed and the return rotation speed), so that it is possible to return from the fuel cut before the engine speed decreases significantly. As a result, since the ISC learning control is not completed, it is possible to prevent the engine speed from being greatly increased even if the engine idling speed is high. As a result, it is possible to provide a vehicle control device that can suppress a shock that occurs at the time of return from a fuel cut even if ISC learning control is incomplete.

  In the vehicle control apparatus according to the second invention, in addition to the configuration of the first invention, the return condition is a condition that the vehicle speed of the vehicle is lower than a predetermined vehicle speed. The changing means includes means for changing the return condition by correcting the predetermined vehicle speed so as to increase when it is determined that the learning is not completed by the determining means.

  According to the second aspect of the invention, when the ISC learning control is not completed, the vehicle speed, which is a return condition from the fuel cut, is increased so that the vehicle speed (proportional to the engine speed) does not decrease greatly. It can be made to return from. As a result, since the ISC learning control is not completed, it is possible to prevent the engine speed from being greatly increased even if the engine idling speed is high.

  In the vehicle control apparatus according to the third aspect of the invention, in addition to the configuration of the first aspect of the invention, the return condition is a condition that the rotational speed of the internal combustion engine is below a predetermined rotational speed. The changing means includes means for changing the return condition by correcting so as to increase a predetermined number of revolutions when the determining means determines that learning is not completed.

  According to the third aspect of the invention, when the ISC learning control is not completed, the engine speed, which is the return condition from the fuel cut, is increased so that the engine speed can be reduced before the engine speed decreases significantly. It can be made to return. As a result, since the ISC learning control is not completed, it is possible to prevent the engine speed from being greatly increased even if the engine idling speed is high.

  In the vehicle control apparatus according to the fourth invention, in addition to the configuration of any one of the first to third inventions, the fluid coupling is a torque converter, the machine element is a lock-up clutch, and depends on the machine element. The mechanical connection of the input / output shaft of the fluid coupling is a connection according to at least one of the engagement state and the slip state of the lockup clutch.

  According to the fourth aspect, even when the ISC learning control is not completed, when the vehicle is returned from the fuel cut under the same conditions as when the ISC learning control is completed, the lockup clutch is at least in the engaged state and the slip state. Freed from either state. At this time, when the ISC learning control is not completed, the idling speed of the internal combustion engine is a high speed with an initial value. Therefore, when the lockup clutch is released, the rotational speed of the internal combustion engine increases and a shock is generated. For this reason, when the ISC learning control is not completed in this way, it is easy to return from the fuel cut (so that the internal combustion engine returns at a high speed), and even if the idling speed is high, the internal combustion engine The engine speed can be prevented from rising.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following description, the same parts are denoted by the same reference numerals. Their names and functions are also the same. Therefore, detailed description thereof will not be repeated.

  FIG. 1 shows a control block diagram of this engine system. This engine system controls the engine 100 to prevent the occurrence of a shock by avoiding the increase in engine speed when returning from a fuel cut when the ISC learning control is not completed.

  In engine 100, an ignition plug 110 is controlled by an ignition device 110 controlled by engine ECU 400, and an air-fuel mixture in a combustion chamber is ignited in each cylinder at a desired ignition timing. Torque generated from engine 100 is transmitted to drive wheels via torque converter 200 and automatic transmission 300. The torque converter 200 includes a lockup clutch. The lock-up clutch is a mechanical clutch provided between the pump impeller (engine 100 side) and the turbine liner (automatic transmission 300 side) of the torque converter 200, and the lock-up clutch is brought into an engaged state. By doing so, the transmission efficiency of the automatic transmission can be increased and the fuel consumption can be improved. The engagement state of the lock-up clutch of torque converter 200 is controlled by ECT (Electronic Control Transmission) _ECU different from engine ECU 400. The ECT_ECU controls the automatic transmission 300.

  Engine ECU 400 includes an ISC control unit 410 that controls the amount of air during idling, a fuel cut control unit 420 that performs fuel cut control, and a lockup clutch state detection unit 430 that detects the state of the lockup clutch of torque converter 200. including.

  The ISC control unit 410 adjusts the amount of air flowing through the bypass passage of the throttle valve with the idle speed control valve to control the idling rotational speed to a desired rotational speed. As described above, in this ISC control unit 410, feedback control is performed in order to bring the rotational speed of the engine 100 during idling closer to the target engine rotational speed. The idling air flow rate in this feedback control is controlled so as to learn by reflecting the feedback result. In this learning control, the initial value of the idling air flow rate is set to a larger value in order to avoid engine stall. Therefore, when the learning control is not completed, the ISC control with the initial value is executed. Since the control with the initial value is performed until the learning control is completed, the idling speed of the engine 100 is set to a higher value ( The intake air amount sucked into the engine 100 is larger).

  The fuel cut control unit 420 stops the fuel supply to the engine 100 when the vehicle is in a predetermined operation state, and performs fuel cut control for returning from the fuel cut state when a predetermined condition is satisfied. Execute. That is, in order to improve fuel consumption, the supply of fuel to engine 100 is stopped during the deceleration operation (engine and ring state). In general, the fuel cut is executed in a state where the engine speed is higher than a predetermined fuel cut return speed (the minimum speed at which the engine does not stall even if the fuel supply is stopped), and fuel is as much as possible. The fuel consumption can be improved by reducing the supply amount.

  The lockup clutch state detection unit 430 that detects the state of the lockup clutch of the torque converter 200 may be input directly from the torque converter 200 to the engine ECU 400 as shown in FIG. It may be input to engine ECU 400 via ECT_ECU.

  A control structure of a program executed by engine ECU 400 of FIG. 1 will be described using a flowchart with reference to FIG.

  In step (hereinafter step is abbreviated as S) 100, engine ECU 400 sets lockup clutch release vehicle speed (= fuel cut return vehicle speed) SPDLUOFF to normal lockup release vehicle speed (low speed) SPDREF.

  In S200, engine ECU 400 determines whether or not the engine is idling and fuel cut. If in the idling state and the fuel cut state (YES in S200), the process proceeds to S300. Otherwise (NO in S200), this process ends.

  In S300, engine ECU 400 executes ISC learning control. In S400, engine ECU 400 determines whether or not ISC learning control is completed. In this determination, for example, it is possible to determine whether or not the ISC learning control is completed by determining whether or not the learning value of the idle air flow rate has been updated. That is, if the learning value is not updated for a predetermined time or more, it can be determined that the ISC learning control is completed. When ISC learning control is completed (YES in S400), this process ends. If not (NO in S400), the process proceeds to S500.

  In S500, engine ECU 400 sets lockup clutch release vehicle speed (= fuel cut return vehicle speed) SPDLUOFF to {normal lockup release vehicle speed (low speed) SPDREF + α (α ≧ 0)}.

  The operation of engine 100 controlled by engine ECU 400 that is the control device according to the present embodiment based on the above-described structure and flowchart will be described.

  The automatic transmission 300 and the engine 100 are connected via a torque converter 200 having a lockup clutch. While the vehicle is traveling, the lockup clutch release vehicle speed (= fuel cut return vehicle speed) SPDLUOFF is set to the normal lockup release vehicle speed (low speed) SPDREF. The ISC learning control is executed (S300), and until the ISC learning control is completed (NO in S400), the lockup clutch release vehicle speed (= fuel cut return vehicle speed) SPDLUOFF is set to {normal lockup release vehicle speed (low speed) SPDREF + α (Α ≧ 0)}. On the other hand, when the ISC learning control is completed (YES in S400), the lockup clutch release vehicle speed (= fuel cut return vehicle speed) SPDLUOFF remains the normal lockup release vehicle speed (low speed) SPDREF.

  FIG. 3 shows temporal changes in various state quantities of the engine 100 at this time. FIG. 3A shows the throttle opening corresponding to the accelerator opening (High indicates throttle open state, Low indicates throttle closed state), and FIG. 3B shows the fuel cut flag (High performs fuel cut). The fuel supply is stopped (Low indicates fuel cut is stopped), FIG. 3 (C) shows the fuel supply state (High indicates fuel supply is stopped, Low indicates fuel supply is stopped), and FIG. 3 (D) is locked. Fig. 3 (E) shows the engine speed NE and the turbine speed NT when the ISC learning is not completed. FIG. 3 (F) shows the engine speed NE and the turbine speed NT when ISC learning is completed. In FIGS. 3E and 3F, since the lockup clutch is engaged (or slipped) during the fuel cut, the engine speed NE is equal to the turbine speed NT. The vehicle speed V is proportional to the turbine speed NT. For this reason, in the above-described flowchart, the vehicle speed is described as a reference, but in FIGS. 3E and 3F, the rotation speed is used as a reference.

  As shown in FIG. 3F, when the ISC learning is completed, the idling speed of engine 100 is as low as NE (ID1). This NE (ID1) is lower than the idling speed NE (ID2) of the engine 100 when the ISC learning is not completed. For this reason, as shown in FIG. 3F, even when the lockup clutch release vehicle speed (= fuel cut return vehicle speed) SPDLUOFF remains at the normal lockup release vehicle speed (low speed) SPDREF, The engine speed NE does not blow up greatly and no shock occurs.

  On the other hand, as shown in FIG. 3E, if the ISC learning is not completed, the idling speed of engine 100 is as high as NE (ID2). This NE (ID2) is higher than the idling speed NE (ID1) of the engine 100 when the ISC learning is completed. As shown in the prior art in FIG. 3E, when the idling speed is high as described above, the lockup clutch release vehicle speed (= fuel cut return vehicle speed) SPDLUOFF is changed to the normal lockup release vehicle speed (low speed) SPDREF. If the engine is returned from the fuel cut, the engine speed NE is greatly increased and a shock is generated (black arrow). In such a case, set the lockup clutch release vehicle speed (= fuel cut return vehicle speed) SPDLUOFF to {normal lockup release vehicle speed (low speed) SPDREF + α (α ≥ 0)} to make it easier to return from the fuel cut. Even if the idling speed is high because the ISC learning control is not completed and the idling speed is high, the engine speed NE is reduced when the engine speed NE returns from the fuel cut. It doesn't blow up so much that it doesn't cause a shock.

  As described above, according to the control device of the present embodiment, when the ISC learning control is not completed, it is easy to return from the fuel cut (by increasing the return vehicle speed and the return rotation speed), and the engine speed is increased. It was made to return from the fuel cut before it fell greatly. As a result, since the ISC learning control is not completed, it is possible to prevent the engine speed from being greatly increased even if the engine idling speed is high.

  The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

1 is a control block diagram of an engine control system according to an embodiment of the present invention. It is a flowchart which shows the control structure of the program performed by engine ECU of FIG. It is a timing chart which shows the time change of the state quantity of vehicles carrying the engine control system concerning an embodiment of the invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 100 Engine, 110 Ignition device, 200 Torque converter, 300 Automatic transmission, 400 Engine ECU, 410 ISC control part, 420 Fuel cut control part, 430 Lockup clutch state detection part.

Claims (4)

A vehicle control device equipped with an internal combustion engine and an automatic transmission including a fluid coupling connected to an output shaft of the internal combustion engine and a mechanical element mechanically connecting an input / output shaft of the fluid coupling,
Feedback control is performed to adjust the air flow rate during idle of the internal combustion engine so that the rotational speed of the internal combustion engine approaches the target rotational speed when the internal combustion engine is idle, and the result of the feedback control is reflected to reflect the result of the feedback control. Learning control means for learning the air flow rate of
The initial value of the air flow rate at the idle time before the learning is completed is preset so as to be larger than the air flow rate at the idle time after the learning is completed,
The control device further includes:
A judging means for judging whether or not the learning is completed;
When the running state of the vehicle satisfies a predetermined start condition, the fuel supply to the internal combustion engine is stopped and the mechanical connection of the input / output shafts of the fluid coupling by the mechanical element is started. Fuel cut execution means for resuming fuel supply to the internal combustion engine when a predetermined return condition is satisfied and releasing mechanical connection of the input / output shaft of the fluid coupling by the mechanical element;
Changing means for changing the predetermined return condition,
The changing unit, when it is determined that the learning is not completed by the determining means, the rotation of the internal combustion engine at the time of resumption of the fuel supply by changing the return is likely to occur to the return condition from off Yuerukatto A control device for a vehicle, including means for bringing a number close to a rotational speed corresponding to the initial value . The return condition is a condition that the vehicle speed of the vehicle is lower than a predetermined vehicle speed,
The changing unit, when it is determined that the learning is not completed by the determining means, the resumption of the fuel supply by changing the pre-Symbol return condition is corrected so as to increase the predetermined vehicle speed The vehicle control device according to claim 1, comprising means for bringing the rotational speed of the internal combustion engine at the time closer to the rotational speed corresponding to the initial value . The return condition is a condition that the rotational speed of the internal combustion engine is lower than a predetermined rotational speed,
The changing unit, when it is determined that the learning is not completed by the determining means, the fuel supply by changing the pre-Symbol return condition is corrected so as to increase the rotational speed of the predetermined 2. The vehicle control device according to claim 1, further comprising means for bringing the rotational speed of the internal combustion engine at the time of restart of the engine closer to the rotational speed corresponding to the initial value . The fluid coupling is a torque converter,
The mechanical element is a lock-up clutch;
The mechanical connection of the input / output shaft of the fluid coupling by the mechanical element is a connection according to at least one of an engagement state and a slip state of the lockup clutch. Vehicle control device.

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