JP2008120151A - Control device for vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To promptly start a vehicle or generate creep torque from neutral control even when an idle speed during the neural control is set to be low in a vehicle performing the neural control when a vehicle stops. <P>SOLUTION: In this control device for the vehicle having an engine 1 and an automatic transmission 2 connected to the engine 1 mounted thereon, lowering engagement pressure of a forward clutch 223 of the automatic transmission to enter a nearly neutral state when the vehicle stops in a travel range, when brake operation is eliminated during the neutral control, the neutral control is ended, a target engine speed higher than a target idle speed normally set in the travel range is set, and an intake air flow rate of the engine is increased. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a control device for a vehicle that performs neutral control that is set to a substantially neutral state when the vehicle is stopped in a travel range, and particularly relates to control when neutral control is canceled.

An example of a vehicle control device that performs neutral control is disclosed in Patent Document 1. In this device, when the shift range is in the traveling range, all the conditions such as the idle switch being ON, the foot brake being ON, and the engine rotational speed ≧ turbine rotational speed of the torque converter are all satisfied. While neutral control is performed by lowering the clutch engagement pressure, if the above condition is not satisfied because the idle switch is off (ie, the accelerator is ON), the clutch is immediately engaged, otherwise the condition is When the condition is not established, smoothing control (clutch smoothing engagement) is performed.
Japanese Patent Laid-Open No. 5-118434

However, the above conventional techniques have the following problems.
That is, in recent years, as the demand for improving fuel efficiency has increased, the idle rotation speed has been lowered, and the idle rotation speed in the neutral state is set relatively low (for example, about 500 rpm). The oil pressure during idling is also low. For this reason, even if the accelerator is ON during the neutral control, the hydraulic pressure (clutch hydraulic pressure) for engaging the clutch is insufficient in the first place, the clutch cannot be immediately engaged, and the vehicle can be started quickly. It may not be possible. In addition, the time from when the foot brake is turned off to when the creep torque is generated is longer than when the vehicle is normally stopped in the travel range, which may cause the driver to feel uncomfortable.

  The present invention has been made in view of such a conventional problem, and an object of the present invention is neutral control in a vehicle that performs neutral control even when the idle rotation speed during neutral control is set low. The time from the brake OFF to the generation of creep torque is set to a level equivalent to that at the time of normal stop in the travel range.

  Therefore, the present invention is equipped with an engine and an automatic transmission connected to the engine, and when the vehicle is stopped in the travel range, the neutral pressure is reduced by reducing the engagement pressure of the forward clutch of the automatic transmission. In a vehicle control apparatus that performs control, when there is no brake operation during the neutral control, the neutral control is terminated and a target engine speed higher than the target idle speed normally set in the travel range is set. And the amount of intake air of the engine is corrected to be increased.

  Here, the increase correction amount of the intake air amount is gradually decreased according to the elapsed time after the brake operation is stopped, and is in the neutral control (more preferably, immediately before the end of the neutral control). It is preferably set based on the amount of intake air.

  According to the present invention, when there is no brake operation during the neutral control, the automatic transmission shifts from the neutral state to the traveling range, that is, increases the engagement pressure of the forward clutch. Since the target engine speed higher than the idling speed normally set in the travel range is set and the intake air amount is corrected to increase, the engine speed can be quickly raised, and the automatic transmission forward The clutch hydraulic pressure for engaging the clutch can be secured quickly. As a result, even when the idle rotation speed in the neutral state is set low, the generation delay of the creep torque and the start delay of the vehicle after the neutral control is canceled can be prevented.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 shows a schematic configuration of a vehicle according to an embodiment of the present invention. As shown in FIG. 1, the vehicle according to the present embodiment is equipped with an engine 1 and an automatic transmission 2 connected to the engine 1.
The automatic transmission 2 includes a torque converter 21, a forward / reverse switching mechanism 22, and a belt type continuously variable transmission (CVT) 23. The output of the engine 1 is input to the CVT 23 via the torque converter 21 and the forward / reverse switching mechanism 22. The output of the CVT 23 is transmitted to the wheel drive shaft 6 and the drive wheel 7 through the propeller shaft 3, the final gear 4 and the differential gear 5.

The torque converter 21 includes a pump impeller 211 connected to the crankshaft 11 of the engine 1 and a turbine runner 213 that is disposed opposite to the pump impeller 211 and connected to the forward / reverse switching mechanism 22 via the turbine shaft 212. Prepare. Although not shown in the figure, a configuration including a lock-up clutch may be adopted.
The forward / reverse switching mechanism 22 is interposed between an inner clutch (corresponding to a forward clutch) 223 that connects and disconnects the input shaft 221 and the output shaft 222 connected to the turbine shaft 212, and the input shaft 221 and the output shaft 222. And an outer clutch 226 that connects and disconnects the support shaft of the intermediate gear 224a of the planetary gear mechanism 224 and the clutch case (fixed body) 225.

  The inner clutch 223 and the outer clutch 226 are each driven by a piston of a hydraulic cylinder. The engagement state (engagement pressure) of the inner clutch 223 and the outer clutch 226 is changed by controlling the hydraulic pressure (clutch hydraulic pressure) of the hydraulic cylinder. When the inner clutch 223 is engaged (engaged) and the outer clutch 226 is released, the forward / reverse switching mechanism 22 is in the forward engagement state. On the other hand, when the inner clutch 223 is disengaged and the outer clutch 226 is engaged (engaged), the forward / reverse switching mechanism 22 is in the reverse engagement state. Further, when both the inner clutch 223 and the outer clutch 226 are released, the neutral state is obtained.

  The CVT 23 is provided on the input shaft 231 side that is connected to the output shaft 222 of the forward / reverse switching mechanism 22 and has a variable effective diameter, and the secondary pulley 234 that is provided on the output shaft 233 side and has a variable effective diameter. And hydraulic cylinders 235 and 236 for changing the effective diameters of the primary pulley 232 and the secondary pulley 234, and a transmission belt 237 wound around the primary pulley 232 and the secondary pulley 234. The pulley ratio is changed by controlling the hydraulic pressures of the hydraulic cylinders 235 and 236, and the gear ratio changes steplessly according to the change in the pulley ratio.

The operation of the engine 1 is controlled by an engine control unit (ECU) 10, and the operation of the automatic transmission 2 (particularly, the forward / reverse switching mechanism 22 and CVT 23) is controlled by a transmission control unit (TCU) 20. In addition, ECU10 and TCU20 are connected so that communication is mutually possible.
The ECU 10 receives detection signals from various sensors (accelerator opening sensor 101, rotational speed sensor 102, etc.) that detect the operating conditions of the engine 1, and based on these detection signals, performs engine control (fuel injection control, ignition timing control, and so on). Execute intake air amount control).

  Here, the intake air amount control is performed as follows. That is, the basic target intake air amount is obtained according to the accelerator opening and the engine speed, and the idle target correction air amount is added to the basic target intake air amount to obtain the final target intake air amount. The target intake air amount is converted into the opening degree of the throttle valve 8 to obtain the target opening degree, and the throttle motor 9 is controlled so that the opening degree of the throttle valve 8 becomes the target opening degree. The idle correction air amount includes the basic required amount according to the target idle rotation speed, the friction correction amount based on the water temperature, etc., the auxiliary load correction amount by an electric load, an air conditioner, etc., and the engine rotation speed when the feedback control condition is satisfied. A feedback correction amount for feedback control is included in the idling rotational speed, but in this embodiment, an “N → D transition correction amount” is further included. The “correction amount at the time of transition from N to D” is a correction amount that is set when the neutral control is finished (released) and the transition is made from the neutral state to the forward travel range.

On the other hand, the TCU 20 receives signals from the accelerator opening sensor 101, the brake switch 103, the vehicle speed sensor 104, the range switch 105, and the like, and controls the forward / reverse switching mechanism 22 and the CVT 23 (transmission ratio thereof) based on these signals. .
Here, the control of the forward / reverse switching mechanism 22 is performed as follows. That is, when the range selected by an AT shift lever or the like (not shown) is the forward travel range (D range), the inner clutch 223 is engaged (fastened) and the outer clutch 226 is released, while the selected range is the reverse travel range. In the case of (R range), the inner clutch 223 is disengaged and the outer clutch 226 is engaged (fastened). In the forward travel range, when a predetermined condition is satisfied, the engagement pressure of the inner clutch 223 is decreased to enter a neutral state in which the power transmission of the forward / reverse switching mechanism 22 is substantially interrupted (hereinafter, this is referred to as “neutral state”). "Neutral control"). The predetermined conditions, that is, the neutral control execution conditions are as follows: (1) the accelerator pedal is released (accelerator is OFF); (2) the foot brake is depressed (the brake switch is ON). And (3) the vehicle speed is substantially zero.

Here, the neutral control according to the present embodiment and the control at the time of releasing the neutral control will be described based on the flowcharts shown in FIGS.
FIG. 2 shows a flowchart of the neutral control, which is executed every predetermined time when the forward travel range is selected (that is, when the inner clutch 223 in the forward / reverse switching mechanism 22 is in the engaged state). The

In FIG. 2, in S11, it is determined whether or not the accelerator pedal is released. If the accelerator pedal is released, the process proceeds to S12, and if the accelerator pedal is depressed, this flow ends.
In S12, it is determined whether or not the brake pedal is depressed. If the brake pedal is depressed, the process proceeds to S13, and if the brake pedal is released, this flow is terminated.

In S13, it is determined whether or not the vehicle speed is (almost) zero. If the vehicle speed is substantially zero, the process proceeds to S14, and if the vehicle speed is not zero, this flow ends.
In S14, neutral control is executed. That is, the engagement pressure of the inner clutch 223 in the forward / reverse switching mechanism 22 is lowered to a substantially neutral state. In such neutral control, a neutral control flag is set (Fneu = 1), a target idle speed in the neutral state (hereinafter referred to as “neutral target idle speed”) is set, and the engine speed is set to “ The engine control is executed so that the neutral target idle speed (for example, 500 rpm) is obtained.

FIG. 3 shows a flowchart when the neutral control is canceled, and is executed at predetermined time intervals during the neutral control (that is, when Fneu = 1).
In FIG. 3, in S21, it is determined whether or not the brake pedal is released (brake switch ON → OFF). If the brake pedal is released (that is, if the brake operation is no longer performed), the process proceeds to S22.

  In S22, the neutral control is released (terminated) (at the same time, the neutral control flag is also released. Fneu = 0). Thereby, the transition from the neutral state to the forward travel range (D range) is started, and the clutch hydraulic pressure is supplied so as to increase the engagement pressure of the inner clutch 223. On the other hand, if the foot brake is depressed in S21 (if the brake switch is still ON), this flow is terminated and the neutral control is continued as it is. Basically, if it is determined whether or not the brake pedal is released, it is possible to determine whether or not the neutral control execution condition is satisfied. However, other conditions (the above (1), (3 Of course, it may be determined.

  In S23, since the transition from the neutral state to the forward travel range is started, the target engine speed at the time of transition (at the time of transition from N to D) (hereinafter referred to as "target engine speed at the time of transition from N to D") is determined. Set. The “target engine speed at the time of transition from N to D” is not only higher than the neutral target idle speed but also the target idle speed normally set during idle operation in the forward travel range (hereinafter referred to as “D range target idle speed”). It is a value higher than “rotational speed”. For example, when the “neutral target idle rotation speed” is 500 rpm and the “D range target idle rotation speed” is 700 rpm, the “target engine rotation speed during the transition from N to D” is set to 750 to 800 rpm.

  In S24, “N → D transition correction amount” is set. The “correction amount during N → R transition” is set based on the intake air amount during the neutral control, as shown in the figure. Specifically, the smaller the intake air amount during the neutral control, the larger the “N → R transition correction amount” is set. Further, it is desirable that the “correction amount at the time of transition from N → R” is gradually decreased as time elapses (see the hatched portion in FIG. 4).

If the accelerator pedal is depressed after the brake pedal is released, first, the control at the time of transition from N to D as described above is performed, and then engine control (fuel injection control, intake air amount control) is performed according to the depression amount of the accelerator pedal. Etc.) will be implemented.
FIG. 4 is a time chart showing a state when the neutral control is canceled.
When the brake pedal is released during the neutral control (time t1), the neutral control is terminated and the transition from the neutral state to the forward travel range is started. At this time, the target rotational speed of the engine is switched from “neutral target idle rotational speed” to “target engine rotational speed at the time of transition from N to D”, and at the time of transition from “N to D” for correcting the intake air amount to be increased. Correction amount "is set. As described above, “N → R transition target engine rotational speed (for example, 750 to 800 rpm)” is not limited to “neutral target idle rotational speed (for example, 500 rpm)”, but “D range target idle rotational speed (for example, 700 rpm) ”. Further, the “correction amount at the time of transition from N → D” is set during neutral control, that is, based on the immediately preceding intake air amount, and is set to gradually decrease as time passes, as indicated by hatching in the figure. (In other words, a triangular correction of the intake air amount is performed from the end of neutral control). It should be noted that a constant value may be set for the first predetermined time and then gradually decreased (keystone correction).

  At the end of neutral control (start of shifting to the forward travel range), supply of clutch hydraulic pressure is started to engage the inner clutch 223, but the “neutral target idle speed” is set low due to a fuel efficiency improvement request or the like. Then, it takes time until the clutch hydraulic pressure becomes insufficient and the clutch hydraulic pressure is sufficient to engage the inner clutch 223 (time t3). Therefore, the engagement pressure of the inner clutch 223 cannot be sufficiently ensured, and a delay in the generation of creep torque and a delay in starting (see the broken line in the figure).

  On the other hand, in the present embodiment, the brake engine is turned ON → OFF, that is, with the end of the neutral control, the target engine speed (target engine speed at the time of transition from N → D) higher than the “D range target idle speed”. In addition, a correction amount at the time of transition from N to D is set, and an increase correction of the intake air amount is performed. As a result, the engine speed can be quickly converged to the target engine speed at the time of transition from N to D (the engine speed rapidly rises). As a result, the clutch hydraulic pressure is also quickly raised (time t2), and at least a creep torque equivalent to that at the time of brake ON → OFF in the normal forward travel range can be secured, and the occurrence of a delay in starting and an uncomfortable feeling can be suppressed. (See the solid line in the figure).

  As described above, according to the present embodiment, neutral control is performed in which the engagement pressure of the forward clutch (inner clutch 223) of the automatic transmission is reduced to a substantially neutral state when the vehicle is stopped in the travel range. When the brake operation is lost during the neutral control, the neutral control is terminated, and an N → D target engine rotational speed higher than the target idle rotational speed normally set in the travel range (D range target idle rotational speed) is set. In addition, since the intake air amount is increased and corrected by setting the correction amount at the time of transition from N to D, the engine rotation speed can be quickly raised, and even when the idle rotation speed during neutral control is set low. , Creep torque generation delay and start delay due to insufficient clutch hydraulic pressure can be suppressed (ie, Possible to realize the same operability as when the brake ON → OFF in normal forward drive range). Here, the correction amount at the time of transition from N to D is set based on the intake air amount at the neutral control, and is gradually increased according to the elapsed time, so that the intake air amount is increased appropriately and excessively increased. It is possible to prevent the engine from being blown up unnecessarily by increasing the amount.

1 is a diagram illustrating a schematic configuration of a vehicle according to an embodiment of the present invention. It is a flowchart which shows neutral control. It is a flowchart which shows the control at the time of neutral control cancellation | release. It is a time chart which shows the state at the time of cancellation | release of neutral control which concerns on this embodiment.

Explanation of symbols

    DESCRIPTION OF SYMBOLS 1 ... Engine, 2 ... Automatic transmission, 10 ... Engine control unit (ECU), 20 ... Transmission control unit (TCU), 21 ... Torque converter, 22 ... Forward / reverse switching mechanism, 23 ... Continuously variable transmission (CVT), DESCRIPTION OF SYMBOLS 101 ... Accelerator opening sensor, 102 ... Rotational speed sensor, 103 ... Brake switch, 104 ... Vehicle speed sensor, 105 ... Range switch, 223 ... Inner clutch (forward clutch), 224 ... Planetary gear mechanism, 226 ... Outer clutch

Claims (4)

Vehicle control apparatus equipped with an engine and an automatic transmission connected to the engine and performing neutral control to reduce the engagement pressure of the forward clutch of the automatic transmission to a substantially neutral state when the vehicle is stopped in the travel range In
When there is no brake operation during the neutral control, the neutral control is terminated, a target engine speed higher than the target idle speed normally set in the travel range is set, and the intake air amount of the engine A vehicle control device that corrects the amount of increase.   The vehicle control device according to claim 1, wherein an increase correction amount of the intake air amount is gradually decreased according to an elapsed time after the brake operation is stopped.   The vehicle control device according to claim 1 or 2, wherein an increase correction amount of the intake air amount after the neutral control is finished is set based on the intake air amount during the neutral control.   4. The vehicle control device according to claim 3, wherein the smaller the intake air amount during the neutral control, the larger the correction value for increasing the intake air amount after the neutral control is finished.

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