JP2005307973A - Control device for vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent a vehicle from being pushed forward at a time of down shift in deceleration in a device equipped with a transmission equipped with a clutch element transmitting output of an engine and controlling the clutch element to release in deceleration and controlling engine revolution speed. <P>SOLUTION: When deceleration fuel cut condition is established right after engine revolution speed control accompanying speed change, delay of fuel cut start is prohibited and fuel cut is started immediately if deceleration operation is continued longer than a predetermined period of time just before start of engine revolution speed control. If deceleration operation is continued shorter than the predetermined period of time, start of fuel cut is delayed to avoid overheat of a catalyst. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a vehicle control device that temporarily releases a clutch element at the time of shifting and controls the rotational speed of an engine in the released state of the clutch element.

In Patent Document 1, in a vehicle equipped with a clutch that transmits the output of an engine to a transmission, the clutch is temporarily controlled to be released at the time of shifting, and the engine rotational speed is controlled to an instruction speed when the clutch is released. The structure to perform is disclosed.
Patent Document 2 discloses a configuration in which the start of the deceleration fuel cut is delayed in order to prevent catalyst overheating due to the deceleration fuel cut.
JP 2001-041065 A JP 05-321720 A

  By the way, in the above-described conventional control, the clutch is immediately engaged when the engine speed control in the released state of the clutch is completed. However, since the engine torque is not controlled, for example, the engine speed is increased during a downshift during deceleration. If the control for opening the throttle valve is performed as much as possible, there is a problem that the vehicle is pushed forward by engaging the clutch in a state where the engine torque remains unburned, which makes the driver feel uncomfortable.

Here, even if the deceleration fuel cut condition is satisfied when the clutch is engaged, if the start of the fuel cut for protecting the catalyst is delayed, the engine torque is generated within the delay time, and the vehicle moves forward. It will be pushed out.
The present invention has been made in view of the above problems, and even if engine speed control is performed during downshift during deceleration, the vehicle is pushed forward when the clutch is engaged (at the end of speed control). It is an object of the present invention to provide a vehicle control device that can avoid giving an uncomfortable feeling to the vehicle.

  Therefore, the present invention includes an engine and a transmission including a clutch element that transmits the output of the engine, and temporarily controls the release of the clutch element at the time of shifting, and the engine is in a released state of the clutch element. Is a vehicle control device that delays the start of a deceleration fuel cut in the engine while prohibiting a delay in the start of the deceleration fuel cut immediately after the engine rotation speed control. It was set as the structure to do.

  According to this configuration, if the deceleration fuel cut condition is satisfied at the time when the engine rotation speed control accompanying the shift is completed, the deceleration fuel cut is immediately executed. Even if the cylinder intake air amount is larger than the idle equivalent amount at the end of the engine rotation speed control due to the delay in following the change in the air amount accompanying the engine rotation speed control, the fuel cut is executed immediately. No engine torque is generated and the vehicle is prevented from being pushed forward immediately after the end of the engine speed control.

Embodiments of the present invention will be described below with reference to the drawings.
FIG. 1 shows a power train of a vehicle in an embodiment, and includes an internal combustion engine (gasoline engine) 1 and a transmission 2 capable of automatic transmission.
Here, the output shaft of the internal combustion engine 1 and the input shaft of the transmission 2 are connected via a friction clutch 3.

The friction clutch 3 is driven to be switched between a released state and an engaged state by a clutch actuator 4.
The transmission control unit 5 that controls the shifting operation of the transmission 2 and the engagement / release of the friction clutch 3 includes a microcomputer, and includes a gear selection signal by a shift lever 6, a vehicle speed signal by a vehicle speed sensor 7, an accelerator pedal. An accelerator opening signal or the like by the sensor 8 is input.

The transmission control unit 5 releases the friction clutch 3 by controlling the clutch actuator 4 when a shift request is generated according to the traveling state of the vehicle or the will of the driver. 9 is controlled to shift to a gear position (shift stage) corresponding to the shift request.
Further, in the disengaged state of the friction clutch 3, an engine rotation control command is issued to the engine control unit 10 to be described later in order to make the actual engine rotation speed coincide with the target engine rotation speed, and engine rotation control is performed from the engine control unit 10 side. When a signal indicating the end (coincidence with the target engine rotation speed) is transmitted, the friction actuator 3 is engaged by controlling the clutch actuator 4 to end the speed change operation.

The engine control unit 10 that controls the internal combustion engine 1 includes a microcomputer and is configured to be communicable with the transmission control unit 5.
The engine control unit 10 receives an accelerator opening signal from the accelerator pedal sensor 8, an engine speed signal from the engine rotation sensor 12, an intake air amount signal from the air flow meter 13, and the like.

The engine control unit 10 performs fuel injection by the fuel injection valve 15, ignition timing by the ignition device 16, electric power based on detection signals from the various sensors and an engine rotation control request transmitted from the transmission control unit 5. The throttle opening degree by the control throttle 17 is controlled.
Here, the shift control function of the transmission control unit 5 will be described with reference to the flowchart of FIG.

First, in step S1, it is determined whether or not there is a shift request.
Then, when there is a shift request, that is, when the current shift stage is different from the requested shift stage according to the driving condition or the driver's will, the process proceeds to step S2.
In step S2, the friction clutch 3 is released, and in step S3, an engine speed control request is output to the engine control unit 10.

In step S4, the shift actuator 9 is controlled to shift to the required gear position (shift stage).
In step S5, it is determined whether or not an engine rotation speed control end signal is output from the engine control unit 10 side, and the process proceeds to step S6 after waiting for the output of the end signal.

In step S6, the shift control is completed by engaging the friction clutch 3.
The flowchart of FIG. 3 shows the state of engine rotation speed control by the engine control unit 10 when an engine rotation control request is transmitted from the transmission control unit 5, and the time charts of FIGS. The change of various data in speed control is shown.

In the flowchart of FIG. 3, in step S11, it is determined whether or not an engine rotation control request has been transmitted from the transmission control unit 5, and if an engine rotation control request has been transmitted, the process proceeds to step S12.
In step S12, the target engine speed is calculated based on the gear position after the shift, the vehicle speed at that time, and the like.

In step S13, the throttle opening by the electric throttle 17 is feedback controlled so that the actual engine speed at that time matches the target engine speed.
Here, when the target engine rotational speed is approached by feedback control of the throttle opening, the ignition timing is retarded to prevent overshoot of the engine rotational speed.

Note that the input shaft rotational speed of the transmission 2 can be detected, and the throttle opening of the internal combustion engine 1 can be controlled so that the engine rotational speed matches the input shaft rotational speed.
In step S14, it is determined whether or not the actual engine rotational speed has converged to the target engine rotational speed. When the actual engine rotational speed has converged to the target engine rotational speed, the process proceeds to step S15 to control the engine speed control for the transmission control unit 5. A signal indicating that has been completed is transmitted.

The transmission control unit 5 that has received the engine rotation speed control end signal engages the released friction clutch 3 to complete the shifting operation.
The engine control unit 10 is a so-called deceleration that stops fuel injection by the fuel injection valve 15 in a deceleration operation state (except during the engine rotation speed control) in which the accelerator is fully closed and the engine rotation speed is equal to or higher than a predetermined speed. The fuel cut is performed, and the deceleration fuel cut control is switched depending on whether or not it is immediately after the engine rotation speed control accompanying the shift. Details of the deceleration fuel cut control will be described with reference to the flowchart of FIG. .

In the flowchart of FIG. 4, in step S <b> 21, it is determined whether or not a deceleration fuel cut execution condition is satisfied.
Specifically, when the accelerator is fully closed and the engine speed is a predetermined speed or higher and the engine speed is not being controlled (not being shifted), the deceleration fuel cut execution condition is Judge that it is true.

When it is determined that the deceleration fuel cut execution condition is satisfied, the process proceeds to step S22, and it is determined whether or not it is immediately after the engine speed control.
For example, even in a deceleration operation state where the accelerator is fully closed and the engine speed is equal to or higher than a predetermined speed, a change in the intake air amount by the electric throttle 17 is performed while the engine speed control is being performed (during shifting). In addition, the engine torque is changed by supplying the fuel at the same time, so that the engine rotational speed is controlled to the target. However, the deceleration fuel cut condition is satisfied when the engine rotational speed is finished.

If it is determined in step S22 that it is immediately after the engine speed control, the process proceeds to step S23.
In step S23, it is determined whether or not the duration of the deceleration operation state immediately before the start of the engine rotation speed control is equal to or longer than a predetermined time.
When the duration of the deceleration operation state immediately before the engine speed control is a predetermined time or more, the temperature of the catalyst device 19 interposed in the exhaust pipe 18 of the internal combustion engine 1 is not so high. On the other hand, when the duration is less than the predetermined time, it is determined that the temperature of the catalyst device 19 is relatively high.

  On the other hand, in the engine rotation speed control at the time of downshift, the throttle is opened to increase the engine rotation speed. When the fuel is supplied at this time, the vehicle is pushed forward due to the generation of engine torque despite the deceleration.

That is, when it is immediately after the engine speed control, it is desirable to immediately start the deceleration fuel cut in order to prevent the vehicle from being pushed forward.
If deceleration fuel cut is started immediately after engine speed control (from the end of shifting), even if there is a response delay in the intake air amount, engine torque is not generated and the vehicle is prevented from being pushed forward. Will be.

However, if the duration of the deceleration operation state immediately before the engine speed control is less than the predetermined time and the temperature of the catalyst device 19 is relatively high, the deceleration fuel cut is started immediately, The catalyst device 19 may be overheated.
Therefore, in this embodiment, it is determined in step S22 that it is immediately after the engine rotation speed control, and the process proceeds to step S23, where it is determined that the duration of the deceleration operation state immediately before the engine rotation speed control is less than a predetermined time. If it does, it will progress to step S24 and will delay the start only for predetermined time, and will perform the deceleration fuel cut (refer FIG. 6).

That is, when the process proceeds from step S23 to step S24, the vehicle is allowed to be pushed forward by starting the deceleration fuel cut after a predetermined delay time has elapsed after the end of the engine speed control. Thus, overheating of the catalyst device 19 is prevented.
On the other hand, if it is determined in step S23 that the duration of the deceleration operation state immediately before the engine speed control is equal to or longer than the predetermined time, the catalyst device 19 may be overheated even if the deceleration fuel cut is immediately started. Therefore, the process proceeds to step S25, where the deceleration fuel cut is started immediately without providing a delay time, thereby preventing the vehicle from being pushed forward (see FIG. 5).

Further, if it is determined in step S22 that it is not immediately after the engine speed control, it is not necessary to consider that the vehicle is pushed forward by delaying the start of the deceleration fuel cut, and the process proceeds to step S24. Then, the fuel is decelerated by delaying the start by a predetermined time.
In step S24, it is not always necessary to delay the start of the deceleration fuel cut. For example, the start of the deceleration fuel cut may be delayed only when decelerating from a predetermined or higher high-load operation state. it can.

  By the way, the above-mentioned implementation is also performed in the case where the control is performed so that the actual engine speed matches the target engine speed in the released state of the shift friction element that is selectively engaged to determine the gear position of the automatic transmission. Similar to the embodiment, by prohibiting the delay of the start of the deceleration fuel cut immediately after the rotational speed control, the same effect can be obtained, and a second embodiment having such a configuration will be described below.

FIG. 7 shows a power train of the vehicle in the second embodiment.
In FIG. 7, the same elements as those in FIG. 1 are denoted by the same reference numerals.
In FIG. 7, the output of the internal combustion engine 1 is input to a transmission 2 ′ capable of automatic transmission through a torque converter T / C.
The transmission 2 ′ is a direct acting type that directly controls the hydraulic pressure to be supplied to a speed change friction element 3 ′ such as a hydraulically operated clutch or a hydraulically operated brake that determines a power transmission path (shift stage) of a gear transmission system. This is an automatic transmission.

  That is, a plurality of solenoid valves 20 are provided in the shift control valve 4 ′, and the transmission control unit 5 performs duty control on the solenoid valves 20 respectively, so that the hydraulic pressure supplied to each shift friction element 3 ′ is increased. Each shifting friction element 3 ′ is selectively engaged and operated by being individually controlled, whereby the gear position of the transmission 2 ′ is selected.

The transmission control unit 5 includes a signal from the turbine sensor 21 that detects the input shaft rotational speed Nt of the transmission 2 ′ from the turbine of the torque converter T / C, a vehicle speed signal from the vehicle speed sensor 7, and an accelerator opening by the accelerator pedal sensor 8. A degree signal is input.
Then, the transmission control unit 5 determines the target shift speed from the vehicle speed and the accelerator opening, determines that there is a shift request when the target shift speed is different from the current shift speed, and shifts to the target shift speed. As is performed, switching between release and engagement of the frictional element 3 ′ for shifting is executed.

That is, the above process corresponds to the process of determining that a shift request is present in step S1 of the flowchart of FIG. 2 and proceeding to step S2 and subsequent steps.
In the release / engagement switching control, rotation control is performed, and the friction element 3 'related to the currently selected shift speed is switched to the friction element 3' related to the next target shift speed to be selected.

In the rotation synchronization control at the time of shifting, the synchronous rotational speed between the engine rotational speed and the input shaft rotational speed is calculated from the target gear stage and the like, and the switching operation to the friction element 3 ′ is performed in synchronization with the synchronous rotational speed. It is.
Specifically, when a shift request is generated, the transmission control unit 5 rapidly reduces the hydraulic pressure of the disengagement side friction element 3 ′ and releases it, while calculating the synchronous rotation speed from the target shift speed and the vehicle speed, The synchronous rotational speed is output as a target engine rotational speed to the control unit 10.

The above function corresponds to the processing in step S2 and step S3 in the flowchart of FIG.
The engine control unit 10 controls the throttle opening by the electric throttle 17 so that the actual engine speed matches the target engine speed.
The above function corresponds to the engine speed control in the flowchart of FIG.

The transmission control unit 5 increases the hydraulic pressure of the engagement-side friction element 3 ′ in synchronization with the synchronous rotation speed, and when a signal indicating the end of the rotation synchronization control is output from the engine control unit 10 side, By fully increasing the hydraulic pressure of the friction element 3 ′ to the maximum, the engagement is completed, and the shift control is completed.
The above function corresponds to the processing of steps S4 to S6 in the flowchart of FIG.

  As described above, when the shift is performed by switching the friction element 3 ′ while performing the rotation synchronization control, the start delay control of the deceleration fuel cut control shown in the flowchart of FIG. Even if the rotation synchronization control is performed during the downshift, it can be avoided that the vehicle is pushed forward when the engagement-side friction element 3 ′ is completely engaged (at the end of the shift) and the driver feels uncomfortable.

The system diagram which shows the power train of the vehicle in embodiment. The flowchart which shows the shift control in embodiment. The flowchart which shows the engine speed control at the time of the speed change in embodiment. The flowchart which shows the control of the deceleration fuel cut in embodiment. The time chart which shows the control characteristic in the case of prohibiting the delay of the start of the deceleration fuel cut in embodiment. The time chart which shows the control characteristic in the case of delaying the start of the deceleration fuel cut in embodiment. The system diagram which shows the powertrain of the vehicle in 2nd Embodiment.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Internal combustion engine, 2 ... Transmission, 3 ... Friction clutch, 4 ... Clutch actuator, 5 ... Transmission control unit, 6 ... Shift lever, 7 ... Vehicle speed sensor, 8 ... Accelerator pedal sensor, 9 ... Shifting actuator, 10 ... Engine control Unit: 12 ... Engine rotation sensor, 13 ... Air flow meter, 15 ... Fuel injection valve, 16 ... Ignition device, 17 ... Electric throttle, 20 ... Solenoid valve, 21 ... Turbine sensor

Claims (5)

An engine and a transmission including a clutch element that transmits the output of the engine, and temporarily controls the release of the clutch element during a shift, and sets a target rotational speed of the engine in the released state of the clutch element. While controlling to speed
A vehicle control device for delaying the start of deceleration fuel cut in the engine,
Immediately after the engine speed control, the vehicle control device prohibits a delay in starting the deceleration fuel cut.   2. The vehicle control device according to claim 1, wherein the clutch element is a clutch that transmits and releases output from the engine to a transmission.   2. The vehicle control apparatus according to claim 1, wherein the clutch element is a friction element that is selectively engaged to determine a gear position of the automatic transmission.   4. The method according to claim 1, wherein it is determined whether or not to delay a start of the deceleration fuel cut based on an operating state immediately before the control of the engine rotation speed is started. The vehicle control device described in 1.   5. The delay of the start of the deceleration fuel cut is prohibited on the condition that the duration of the deceleration operation state immediately before the control of the engine speed is started is a predetermined time or more. Vehicle control device.

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