JP2014069771A - Control device for automatic stop and restart of engine in vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a control device that can suppress delay of automatic stop and restart of an engine and can prevent uncomfortable feeling such as shock.SOLUTION: A control device comprises: reduction instruction means (Step S109) for reducing transmission torque capacity of a start clutch when a condition for automatically stopping an engine is achieved; stop means for stopping independent rotation of the engine, after output torque of the engine is reduced by delaying ignition timing in a control process of reducing the transmission torque capacity of the start clutch; rapid opening instruction means for increasing reduction speed of the transmission torque capacity so that the start clutch becomes an open state, when a condition for restarting the engine is achieved before opening of the start clutch; and start delay means for executing control for delaying starting of a starter that is rotated to restart the engine, prior to the increase in the reduction speed of the transmission torque capacity of the start clutch by the rapid opening instruction means.

Description

  The present invention relates to a device that includes a start clutch that cuts off torque transmission between an engine and drive wheels, and that controls automatic engine stop and release of the start clutch in association with each other.

  There are various operating conditions required for the driving force source when the vehicle is traveling, and the driving force source needs to output a large torque when starting or accelerating. The braking force needs to be increased. Furthermore, when traveling while maintaining speed, it may not be necessary to generate either driving force or braking force. As described above, since the driving force source does not always need to output the driving force, in a vehicle equipped with the internal combustion engine as a driving force source, even if the main switch is on, Control that automatically stops and improves fuel consumption has been performed.

  Such control is sometimes referred to as stop-and-start (S & S) control or eco-run control. When the vehicle stops according to a stop signal, the control to stop the internal combustion engine or the accelerator pedal is returned. Control that stops the internal combustion engine when decelerating and control that stops the internal combustion engine when the accelerator pedal is returned while the vehicle is traveling at a vehicle speed of a certain level or higher are included. The stoppage of the internal combustion engine by such S & S control is temporary, and the internal combustion engine is restarted by an acceleration request or the like. If the vehicle is decelerating or running, the vehicle running state and the internal combustion engine Since the operating state is different, when the internal combustion engine is stopped, the transmission of torque between the internal combustion engine and the drive wheels is interrupted. Specifically, the clutch on the input side of the transmission connected to the internal combustion engine is released to block torque transmission between the internal combustion engine and the transmission. When a torque converter with a lockup clutch is provided, the lockup clutch may be released.

  Since the internal combustion engine generates driving torque and braking torque as described above, the torque in the power transmission system and the driving wheels varies depending on the engagement and disengagement state of the clutch. For this reason, various controls have been proposed in order to suppress a situation such as a shock caused by a change in torque and to prevent the change in torque from causing an acceleration delay or a braking delay. For example, Patent Document 1 discloses a vehicle in which a torque converter with a lock-up clutch, a clutch, and a transmission are connected in series on the output side of an internal combustion engine. A control device is described that is configured to switch the lockup clutch to an open state, then open the clutch, and stop the operation of the internal combustion engine in that state. According to the description in Patent Document 1, it is said that by controlling in such a manner, it is possible to suppress a shock and prevent the driver from feeling uncomfortable. Further, in Patent Document 2, when a condition for stopping the engine is satisfied, a clutch provided on the output side of the engine is released, and the release control calculates a target hydraulic pressure of the clutch and sets the clutch hydraulic pressure to the target hydraulic pressure. An apparatus is described that is configured to perform by controlling based on values. Further, Patent Document 3 discloses an apparatus for suppressing a shock caused by automatically stopping the engine, and before the engine is automatically stopped, the hydraulic pressure of the friction engagement device is reduced to reduce the engine. A device is described that is configured to reduce the torque transmitted from to the drive wheels.

  On the other hand, it is known that the torque fluctuation is large immediately after the internal combustion engine is started or restarted. Therefore, the apparatus described in Patent Document 4 has a ride comfort due to the torque fluctuation when the engine is started. In order to prevent the deterioration, the ignition timing is retarded when the clutch is released to stop the engine, and the ignition timing is gradually advanced when the clutch is engaged when the engine is restarted. It is configured. Patent Document 5 is configured to reduce the engine torque by retarding the ignition timing after the engine stop condition is satisfied in order to stop the piston at an appropriate position in preparation for engine restart. An apparatus is described.

JP 2006-182148 A JP 2012-91592 A JP 2000-170894 A Japanese Patent Laid-Open No. 11-270376 JP 2004-293474 A

  When the internal combustion engine, which is a driving force source, is stopped and restarted by the control referred to as S & S control, idling stop control, or eco-run control as described above, the behavior of the internal combustion engine or the behavior of the vehicle is not intended by the driver. In order to prevent this change, the internal combustion engine is stopped in a state where the transmission torque capacity of the clutch is lowered, and the transmission torque capacity is gradually increased after the internal combustion engine is restarted. However, in that case, if it takes a long time to open the clutch prior to stopping the internal combustion engine, the time for which the internal combustion engine is stopped is shortened, and there is a high possibility that the effect of improving fuel efficiency is impaired. For example, as described in Patent Document 1 described above, if the lockup clutch and the clutch are sequentially released and the engine is stopped after waiting for the clutch to be released, a delay occurs in stopping the engine. . This situation also applies to the devices described in Patent Document 2 and Patent Document 3, and if the hydraulic pressure of the clutch is gradually lowered toward the target value and then the engine is stopped, There is a delay in stopping.

  In addition, in an internal combustion engine such as a gasoline engine in which an air-fuel mixture of fuel and air is ignited by a spark plug and burned, the ignition timing is delayed as described in Patent Document 4 and Patent Document 5. If the angle is made, the engine torque decreases. Therefore, if the ignition timing retarding control is used together when the engine is stopped by S & S control or the like, the engine torque can be smoothly changed. However, if the engine stop control with the retard control is executed after the clutch is released, a plurality of controls will be continued after the clutch and lockup clutch release control. Similarly to the devices described in each of items 3 to 3, there is a high possibility that a delay occurs in stopping the engine.

  Since the control for temporarily automatically stopping the internal combustion engine is performed based on the operation state of the vehicle, such as whether there is an acceleration request or a drive request, the stop condition may be depending on the situation in which the vehicle is traveling or the road condition. After being established, a condition for restarting the internal combustion engine before the internal combustion engine stops may be satisfied. In such a case, if the clutch control and the engine control are simply executed in order as described in each of Patent Documents 1 to 5, a delay occurs in the increase in the output of the internal combustion engine. End up.

  The present invention has been made paying attention to the above technical problem, and provides a control device that can execute automatic stop and restart control of an engine without causing a delay or a sense of incongruity. It is the purpose.

  In order to achieve the above object, according to the first aspect of the present invention, the engine torque is changed according to the transmission torque capacity between the engine and the drive wheel, the torque of which decreases by retarding the ignition timing. In an automatic engine stop and restart control device for a vehicle provided with a start clutch that can be operated, when the condition for automatically stopping the engine is satisfied without depending on the stop operation of the driver, the start clutch A lowering instruction means for lowering the transmission torque capacity of the engine, and after reducing the output torque of the engine by retarding the ignition timing in the process of reducing the transmission torque capacity of the starting clutch, And a condition for restarting the engine before the determination that the starting clutch is released is established. If the conditions for restarting the engine and the sudden release instruction means for increasing the rate of decrease in the transmission torque capacity of the start clutch are satisfied so that the start clutch is released, the engine is restarted. And a start delay means for executing a control for delaying the start of the starter to be rotated for starting prior to increasing the rate of decrease in the transmission torque capacity of the starting clutch by the quick release instruction means. It is what.

  According to a second aspect of the present invention, in the first aspect of the invention, the starting clutch includes a friction clutch that is engaged by a hydraulic pressure and has a transmission torque capacity corresponding to the hydraulic pressure, and the lowering instruction means is a hydraulic pressure of the friction clutch. Means for lowering the pressure, and the absolute value of the difference between the rotational speed on the input side and the rotational speed on the output side of the friction clutch is greater than or equal to a predetermined reference rotational speed, and the hydraulic pressure instruction value is predetermined. A control device for automatic engine stop and restart in a vehicle, further comprising permission means for permitting the stop means to stop the self-rotation of the engine when the value is equal to or less than a predetermined value.

  According to a third aspect of the present invention, in the first or second aspect of the present invention, the retard control of the ignition timing is configured to start when the vehicle speed of the vehicle decreases to a predetermined vehicle speed. This is a control device for automatic stop and restart of the engine in the vehicle.

  According to a fourth aspect of the present invention, in any one of the first to third aspects, a torque converter having a lock-up clutch is arranged in series with the starting clutch, and the lowering instruction means is a transmission torque of the lock-up clutch. A control device for automatic engine stop and restart in a vehicle, characterized in that it includes means for reducing the capacity, and the quick release means includes means for increasing the rate of decrease in the transmission torque capacity of the lockup clutch. .

  According to the present invention, when the engine is automatically stopped, the retard control of the ignition timing of the engine is performed in the middle of the control for reducing the transmission torque capacity of the starting clutch, and the self-sustaining rotation of the engine is stopped after the retard control. Thus, after the automatic engine stop condition is satisfied, the engine can be quickly stopped, and the fuel efficiency of the vehicle can be improved accordingly. In addition, since the engine stop control is executed during the so-called release control of the start clutch, the condition for restarting the engine may be satisfied during the start clutch release control. The transmission torque capacity of the engine is rapidly reduced and the control for rotating the engine for restarting is delayed, so that torque caused by restarting the engine appears on the drive wheels or a shock occurs. It can be avoided or suppressed.

It is a flowchart for demonstrating an example of the control performed with the control apparatus which concerns on this invention. It is a flowchart for demonstrating an example of the retard angle control performed with the control apparatus which concerns on this invention. It is a flowchart for demonstrating an example of the engine stop control performed with the control apparatus which concerns on this invention. 7 is a flowchart for explaining an example of control executed by the control device according to the present invention when there is a request for engine restart during clutch release control. It is a time chart which shows typically change of each number of rotations, instruction pressure, etc. at the time of performing deceleration S & S control with the control device concerning this invention. It is a time chart which shows typically change of each number of rotations, instruction pressure, etc. at the time of performing conventional deceleration S & S control. It is a block diagram which shows typically the power train of the vehicle made into object by this invention.

  The vehicle targeted by the present invention includes an engine (E / G) 1, a torque converter 2, and a starting clutch (C 1 clutch) 3. This is schematically shown in FIG. 7. In the example shown here, a transmission (T / M)) 4 is further provided, and left and right drive wheels 6 are connected from the transmission 4 via the final reduction gear 5. It is comprised so that a torque may be transmitted to. The engine 1 is basically an internal combustion engine that burns fuel and outputs power. In particular, the engine 1 is ignited with a spark to a mixture of fuel and air, and output is achieved by delaying (retarding) the ignition timing with respect to the crank angle. It is an engine with reduced torque and is therefore generally a gasoline engine. The engine 1 is also provided with a starter motor 1S, as in the case of conventionally known engines. After the fuel supply and ignition are temporarily stopped and the self-rotation is automatically stopped, motoring is performed by the starter motor 1S. By doing so, the engine 1 can be restarted.

  The torque converter 2 has a configuration similar to that conventionally known, and includes a pump impeller 7 rotated by the engine 1 and a turbine 8 that rotates by receiving a spiral flow of oil generated by the pump impeller 7. And a stator 9 disposed between the pump impeller 7 and the turbine 8 by being attached to a predetermined fixing portion (not shown) via a one-way clutch. Therefore, a torque amplification action occurs in the converter region, so that the input torque to the starting clutch 3 changes according to the speed ratio or torque ratio in the torque converter 2.

  Furthermore, the torque converter 2 includes a lockup clutch (direct coupling clutch) 10 that mechanically directly connects the input side member and the output side member. The lock-up clutch 10 has a configuration similar to that conventionally known, and is configured by a friction clutch that operates by hydraulic pressure and whose transmission torque capacity continuously changes in accordance with the hydraulic pressure.

  The starting clutch 3 is an engagement mechanism that transmits torque between the engine 1 and the transmission 4 and interrupts transmission of the torque, and is configured to continuously change the transmission torque capacity. An example of this is a friction clutch, which is generally a multi-plate clutch whose transmission torque capacity is controlled by hydraulic pressure. Further, the transmission 4 is a stepped automatic transmission in which the gear ratio changes stepwise or a continuously variable transmission in which the gear ratio changes continuously. The start clutch 3 is incorporated in the transmission 4. It may be.

  The vehicle targeted by the present invention includes the power train described above, and temporarily stops the engine 1 when a predetermined execution condition is satisfied, and restarts the engine 1 when a predetermined return condition is satisfied. It is configured to perform eco-run control or stop-and-start control (S & S control). For eco-run control or S & S control (hereinafter collectively referred to as S & S control), stop S & S control that stops the engine 1 when the vehicle is stopped, and stop by returning the accelerator pedal and depressing the brake pedal. A deceleration S & S control that automatically stops the engine 1 when the vehicle is decelerating toward the vehicle, and a free-run S & S control that automatically stops the engine 1 when the accelerator pedal is returned when the vehicle is traveling at a vehicle speed higher than a certain level. is there. The execution condition and the return condition will be explained. The stop S & S control is executed when the vehicle speed is “0” and the brake pedal is depressed and the brake pedal is depressed. It is started. The deceleration S & S control is executed when the accelerator pedal is released and the brake is turned on when the vehicle is traveling at a vehicle speed below a predetermined vehicle speed, and the brake is turned off or the accelerator pedal is depressed. And the engine 1 is started. The free-run S & S control is executed with the accelerator off in a state where the vehicle is traveling at a vehicle speed equal to or higher than a predetermined vehicle speed, and the engine 1 is started by returning with the accelerator on.

  An electronic control unit (ECU) 11 for controlling the engine 1, the starter motor 1S, the lockup clutch 10, the starting clutch 3, the transmission 4, and the like is provided. The electronic control device 11 described here is shown as a device integrating an electronic control device for an engine, an electronic control device for a torque converter, an electronic control device for a transmission, and the like. It is configured to perform an operation according to existing data, a control program, etc., and output the operation result as a control command signal. A specific control operation is executed by a control circuit, a hydraulic actuator, or the like. Examples of the control include retard control and advance control of the ignition timing of the engine 1, start and stop of the starter motor 1S, fuel supply control in the engine 1, engagement and release of the lockup clutch 10, and the like. These include torque capacity control, transmission torque capacity control such as engagement and disengagement of the start clutch 3, and gear ratio control of the transmission 4. Examples of input data include engine speed NE, turbine speed in torque converter 2 (input side speed of start clutch 3) NT, input speed of transmission 4 (output of start clutch 3). Side rotation speed) NIN, accelerator opening degree ACC, vehicle speed V, shift position of transmission 4, brake signal, and the like.

  The control device according to the present invention for the vehicle described above opens the start clutch 3 in connection with the control for stopping the engine 1 when the engine 1 is automatically stopped by the S & S control without the operation of the driver. Thus, torque transmission between the engine 1 and the transmission 4 or between the engine 1 and the drive wheels 6 is interrupted. Further, the lockup clutch 10 is released in accordance with the release of the starting clutch 3. An example of control of these clutches 3 and 10 will be described below.

  FIG. 1 is a flowchart for explaining an example of the control executed by the control device according to the present invention, and the clutch release executed in connection with the so-called deceleration S & S control for stopping the engine 1 when the vehicle is decelerated. It is an example of control. The routine shown in FIG. 1 is repeatedly executed every predetermined short time. In the control example shown in FIG. 1, first, it is determined whether or not the shift range or shift pattern is in a state permitting deceleration S & S control (step S101). When the transmission 4 is an automatic transmission, the shift range or the shift pattern is used to set a shift stage or a gear ratio region or pattern that is set based on a vehicle running state such as a vehicle speed or an accelerator opening degree. Therefore, it is selected by the operation of the driver. The shift range or shift pattern includes, in addition to driving for driving the vehicle forward, parking for setting the vehicle in a stopped state, reverse for reverse driving, neutral for blocking transmission of torque to the drive wheels 6, and the like. Yes. If a range or pattern other than the range or pattern for traveling forward is selected, the deceleration S & S control is not executed. Therefore, in step S101, the shift range or shift pattern is first determined. is there. Therefore, if a negative determination is made in step S101, the control shown in FIG. 1 is temporarily terminated without performing any particular control.

  On the other hand, if a positive determination is made in step S101 by setting a shift range or shift pattern for forward traveling, conditions other than the vehicle speed V become conditions under which deceleration S & S control can be executed. It is determined whether or not there is (step S102). This determination is, in essence, for determining whether or not there is an abnormality in various devices for executing the deceleration S & S control such as the engine 1, the auxiliary equipment, or the battery. The control shown in FIG. 1 is once terminated. If there is no abnormality, an affirmative determination is made in step S102. In this case, whether or not the mode for maintaining the lockup clutch 10 in the engaged state (L / U mode) is turned off, that is, lockup is performed. It is determined whether or not the clutch 10 is in the released state, or whether or not the control for smoothly releasing the lockup clutch 10 is in progress (step S103). This determination can be made according to the content of the control signal for the lockup clutch 10. Since the so-called failure determination in step S102 is executed by various types of control in the vehicle, the determination result in other control may be used without being particularly performed in the routine shown in FIG.

  When a negative determination is made in step S103, that is, when the L / U mode for engaging the lockup clutch 10 is turned on or control for engaging the lockup clutch 10 is being executed. The control shown in FIG. 1 is once terminated without performing any particular control. When the engine speed is low and the vehicle speed is low, the lock-up clutch 10 also transmits vibrations caused by torque fluctuations of the engine 1, so that the lock-up clutch 10 is engaged. A so-called lockup region to be controlled and a slip (half lockup) region to be controlled to a slip state are determined based on the vehicle speed and the accelerator opening (or the throttle opening). Therefore, if the condition for executing the S & S control is not satisfied, such as when the accelerator pedal is depressed or the vehicle is traveling at a high vehicle speed, a negative determination is made in step S103. On the other hand, when the accelerator pedal is returned and the engine speed or the vehicle speed is decreasing, the lockup clutch 10 is controlled to be in the released state, so that an affirmative determination is made in step S103. It is determined whether or not the vehicle speed V is equal to or lower than a predetermined reference vehicle speed V1 (step S104). The determination in step S104 is for determining whether or not the vehicle is in a driven state (a state where creep torque is not applied). The reference vehicle speed V1 is determined by the accelerator opening or the transmission 4. It can be determined in advance according to the set gear ratio.

  If a negative determination is made in step S104, the vehicle is in a so-called power running state driven by the output torque of the engine 1, so that the condition for automatically stopping the engine 1 is not satisfied. Therefore, in this case, the control shown in FIG. 1 is temporarily terminated without performing any particular control. On the contrary, if the vehicle speed V is lower than the reference vehicle speed V1 and a positive determination is made in step S104, whether or not a predetermined time has elapsed since the throttle opening became the idle opening. Is determined (step S105). Since the command signal for closing the throttle valve is output when the accelerator pedal is returned, it can be determined that the idle opening has been reached based on the output of the command signal. On the other hand, the intake air amount of the engine 1 does not change immediately due to pulsation caused by compression and expansion of air. Therefore, the predetermined time is a predetermined time in consideration of such a change in the intake air amount, and even when the accelerator opening is suddenly reduced, the driven state is surely set. Therefore, the determination in step S105 is performed to perform clutch release control.

  Therefore, if a negative determination is made in step S105, the control shown in FIG. 1 is temporarily terminated without performing any particular control. On the contrary, if a positive determination is made, it is determined whether or not the starting clutch (C1 clutch) 3 is controlled in connection with the automatic stop of the engine 1 by the S & S control (step S106). ). When step S106 is reached for the first time after the execution condition of the S & S control is satisfied, such as when the accelerator pedal is returned from the state where the engine 1 is running, the determination result is negative. In this case, a determination to start the clutch release control is established in relation to the S & S control or to execute the S & S control (step S107), and the clutch control mode is set to the release control mode (step S108). ). In the disengagement control mode, the procedure for disengaging the start clutch 3 (decreasing the transmission torque capacity) or the transient command pressure and the duration thereof are predetermined, and the clutch control mode is switched to the disengagement control mode. Thus, the starting clutch 3 is controlled according to the predetermined content. That is, in step S109, control of the release hydraulic pressure of the start clutch 3 is started in accordance with the release control mode. An example of the control is a control in which the command pressure is decreased stepwise to a predetermined value, and then the command pressure is decreased at a predetermined gradient, or the differential rotation speed between the rotation speed on the input side and the rotation speed on the output side This is a feedback control in which a target value is set to and the command pressure is set so that the actual differential rotational speed follows the target value. Thereafter, the routine shown in FIG. 1 is once ended.

  After the determination to start the clutch release control is established in step S107 described above, an affirmative determination is made in step S106, and in this case, it is determined whether or not the start clutch 3 release control is being performed ( Step S110). If the control of the starting clutch 3 is other than the release control, that is, if it is determined negative in step S110 because the release control is not being performed, the control shown in FIG. 1 is temporarily terminated without performing any particular control. On the other hand, if the release control has been started and an affirmative determination is made in step S110, the absolute value of the front-rear rotational speed difference of the starting clutch 3 is greater than or equal to a predetermined reference rotational speed N1, and the starting clutch It is determined whether or not the indicated pressure 3 is equal to or less than a predetermined value (step S111). Here, the front-rear rotational speed difference is a difference between the turbine rotational speed NT and the input rotational speed NIN. The reference rotational speed N1 is used to determine that the start clutch 3 is being disengaged, and the rotational speed or torque change on the front side (engine 1 side) does not cause a sense of discomfort such as a shock. It is the number of rotations determined by experiment etc. as a number. Further, the predetermined value for determining the starting clutch 3 command pressure is used for determining that the opening control of the starting clutch 3 has progressed or that the transmission torque capacity has sufficiently decreased, Similar to the reason for the number difference, the engagement pressure is determined by experiments or the like so that a change in the rotational speed or torque on the front side (engine 1 side) does not cause a sense of incongruity such as a shock.

  If a negative determination is made in step S111, the start clutch 3 has not yet been fully released and its transmission torque capacity is large, so the control shown in FIG. 1 is temporarily terminated without any particular control. To do. On the other hand, if the determination in step S111 is affirmative, the disengagement control of the starting clutch 3 proceeds and the transmission torque capacity is reduced, so that the engine 1 is allowed to stop (step). S112). The stop control of the engine 1 based on this permission will be described later. Then, when a predetermined condition is satisfied, the control mode of the starting clutch 3 is switched to the steady control mode which is normal control (step S113), and the routine of FIG.

  The control device according to the present invention reduces the output torque of the engine 1 in the process of performing the release control of the start clutch 3 described above, that is, without waiting for the determination that the start clutch 3 is completely released. Execute retard angle control. The control routine is shown in FIG. 2, and in the example shown here, it is first determined whether or not there is an engine stop request by S & S control (step S201). This can be performed, for example, by determining whether or not the engine stop permission in step S112 described above has been established. If a negative determination is made in step S201 because there is no engine stop request, the routine of FIG. 2 is temporarily terminated without performing any particular control. On the other hand, if an affirmative determination is made in step S201 due to an engine stop request, retard angle control for delaying the ignition timing of the engine 1 is executed (step S202). This control is a control for gradually retarding the ignition timing to the misfire limit, and the change rate (change gradient) of the ignition timing does not cause a sense of incongruity such as a shock due to the stop of the engine 1 and the accompanying torque change. Can be set in advance. Further, the misfire limit is determined by the number of cylinders of the engine 1 and the displacement.

  Further, a specific stop control of the engine 1 when the engine stop permission is established in step S112 described above will be described. FIG. 3 is a flowchart for explaining an example of the control. Since the automatic stop of the engine 1 is executed as S & S control, it is first determined whether or not there is an engine stop request by the S & S control (step S301), and if there is no engine stop request, negative in step S301. If it is determined, the routine of FIG. 3 is once terminated. On the other hand, if it is determined affirmatively, it is determined whether or not the starting clutch 3 has been released (step S302). The determination in step S302 is executed after permission to stop the engine 1 is established in step S112 described above. Since the control device according to the present invention executes the retard control for stopping the engine in the middle of the opening control of the starting clutch 3, the determination result becomes negative when the determination in step S302 is performed first, In that case, it is determined whether or not the retardation control described above has been completed (step S303). Here, the end of the retard control means that the ignition timing has been retarded to the misfire limit, and therefore the determination in step S303 can be made based on the control command for the ignition timing of the engine 1.

  If a negative determination is made in step S303 because the retard control has not ended, the routine of FIG. 3 is once ended and the control from step S301 is performed again. On the other hand, if it is determined affirmative in step S303 that the retard angle control has ended, the engine 1 is automatically stopped (step S304). Specifically, this is control for stopping the self-sustaining rotation of the engine 1 such as stopping the supply of fuel to the engine 1 and stopping energization of the spark plug. On the other hand, if it is determined in step S302 that release of the starting clutch 3 has been completed, that is, if a positive determination is made in step S302, the routine immediately proceeds to step S304, where the engine 1 is automatically stopped, and FIG. This routine is temporarily terminated.

  Therefore, when the engine 1 is automatically stopped by the S & S control, the control device according to the present invention performs the retard control of the engine 1 to stop the engine torque in the process of releasing the start clutch 3. Decrease. In other words, since the engine 1 is automatically stopped or the stop control is started without waiting for the start clutch 3 to be completely released, the delay of the automatic stop of the engine 1 can be shortened more than before, and accordingly, the vehicle The fuel efficiency improvement effect can be increased.

  According to the control device of the present invention, the engine 1 may be automatically stopped in the middle of the opening control of the starting clutch 3, and therefore a request for restarting the engine 1 is generated in the middle of the opening control of the starting clutch 3. There is. Such a situation is a situation that does not occur in the conventional device that executes the engine stop control after the clutch release is completed. In view of this, the control device according to the present invention eliminates inconveniences such as a shock accompanying restart of the engine 1 and excessive slip of the start clutch 3 when there is a restart request of the engine 1 during the release control of the start clutch 3. In order to avoid this, delay control of cranking (motoring) of the engine 1 and sudden release control of the starting clutch 3 are performed.

  FIG. 4 is a flowchart for explaining the control example, which is repeatedly executed every predetermined short time during the S & S control. In the example shown here, first, it is determined whether or not there is a request for restart of the engine 1 by S & S control (step S401). If it is determined negative in step S401 because there is no request for restart, the routine of FIG. 4 is temporarily terminated without performing any particular control. On the other hand, if it is determined affirmative in step S402 due to the request for restart, it is determined whether or not the starting clutch (C1 clutch) 3 has been released (step S402). This determination may be made, for example, by determining whether the same conditions as in step S111 described above are satisfied. At the beginning of the routine of FIG. 4, a negative determination is made in step S402. In this case, the process proceeds to step S403, and it is determined whether or not a starter activation delay is in progress. This starter activation delay is a control for delaying the starter motor 10 until a predetermined condition is satisfied without starting the starter motor 10 even when the engine 1 is requested to be restarted.

  At the beginning of the control shown in FIG. 4, since the starter activation delay has not yet been implemented, a negative determination is made in step S403, and the flow proceeds to step S404 to start a starter activation delay request. This is a control for prohibiting energization or activation of the starter motor 1S for a predetermined time. Note that if the starter activation delay has already been started and the determination in step S403 is affirmative, the routine shown in FIG. 4 is temporarily terminated in order to maintain the previous control state.

  Then, in conjunction with the start of the starter activation delay request, a command for rapidly releasing the starting clutch 3 and the lockup clutch 10 is started (step S405), and the routine of FIG. 4 is once ended. The rapid opening command is specifically an instruction to decrease the respective hydraulic pressure. The command pressure is “0” for the lock-up clutch 10 and the hydraulic pressure in the steady control mode for the starting clutch 3. The steady control mode is a control mode in which the command pressure is set according to the required driving force amount (output required amount) such as the accelerator opening. Thus, before the engine 1 is rotated by the starter motor 1S, the transmission torque capacity of each of the clutches 3 and 10 is sufficiently reduced.

  When the release of the start clutch 3 is completed and an affirmative determination is made in step S402, the starter activation delay request is terminated (step S406), and the quick release command for the start clutch 3 and the lockup clutch 10 is issued. Is canceled (step S407), and the routine of FIG. 4 is once terminated. Therefore, by performing the control as shown in FIG. 4, even if a restart request of the engine 1 is generated during the opening control of the start clutch 3, the drive torque changes suddenly or excessive slip occurs in the start clutch 3. The inconvenience such as can be avoided or suppressed. Further, not only the cranking or motoring of the engine 1 is delayed, but also the transmission torque capacity of the starting clutch 3 during the release control is rapidly reduced, so that the restart delay of the engine 1 is made as short as possible. This can prevent or suppress the driver from feeling uncomfortable.

  FIG. 5 is a time chart showing changes in the clutch control mode, the ignition timing, the indicated pressure of the starting clutch 3 and the like when the S & S control is executed by the control device according to the present invention described above. The example shown here is an example of the deceleration S & S control in which the engine 1 is stopped while the accelerator pedal is returned and decelerated. In the state where the brake is not operated, the engine speed is the fuel cut (FC) speed. In order to maintain the above, the gear ratio is increased as the vehicle speed decreases, and the command pressures (C1 command pressure and LU command pressure) are set to keep the start clutch 3 and the lockup clutch 10 engaged. It is maintained at a high pressure. When the brake is operated in this state (at time t1), the vehicle is expected to stop, so that the control of the start clutch 3 related thereto is started. That is, the clutch control mode is set to the release control mode. Therefore, the command pressure (C1 command pressure) of the starting clutch 3 and the command pressure (LU command pressure) of the lockup clutch 10 are lowered stepwise, and then gradually lowered at a predetermined gradient.

  As the transmission torque capacity of the lock-up clutch 10 decreases, the slip rotation speed of the lock-up clutch 10 increases, so the engine speed NE starts to decrease. Accordingly, the negative torque (braking torque) of the drive shaft (D / S) slightly decreases, and fuel cut (idle-on FC) control is stopped (returned) in order to avoid engine stall. If the vehicle speed V decreases to the engine stop vehicle speed in the deceleration S & S control in the process of controlling in this way (at time t2), the clutches 3 and 10 are not completely disengaged and the disengagement control is in progress. Then, the retard control of the ignition timing is started. When the ignition timing reaches the misfire limit (at time t3), the fuel supply to the engine 1 is stopped, so that the engine speed NE decreases rapidly, the braking torque by the engine 1 decreases, and the drive shaft torque decreases. Increase (negative torque decreases).

  At this time, the command pressures of the clutches 3 and 10 are in a transient state in which they are lowered toward the open state. Therefore, the starting clutch 3 still has a somewhat high transmission torque capacity and the turbine rotational speed NT and the input rotational speed. The number NIN is almost equal. As the transmission torque capacity of the starting clutch 3 decreases, the negative torque due to the rotation of the torque converter 2 decreases, so that the drive shaft torque gradually increases (negative torque gradually decreases), and A difference occurs in the front and rear rotational speed of the starting clutch 3. That is, the turbine rotational speed NT starts to decrease with respect to the input rotational speed NIN. The example shown in FIG. 5 is an example in which the brake is returned in the process of reducing the transmission torque capacity and a restart request for the engine 1 is generated. When a restart request is generated in this way (at time t4). The starter start delay is started. That is, even if there is a restart request, the engine 1 is not cranked (motored), so its rotational speed NE is "0". At the same time, the pressures of the clutches 3 and 10 are lowered stepwise (rapidly). In other words, the quick opening control is executed. As a result, the transmission torque capacity of the starting clutch 3 is rapidly reduced. This appears as a reduction of the turbine speed NT with respect to the input speed NIN.

  Thereafter, while the starter activation delay is being executed, the control mode of the starting clutch 3 is switched to the steady control mode (at time t5). At this time, since the accelerator is off, the command pressure of the starting clutch 3 is maintained at the same low pressure as that immediately before. Thus, when the absolute value of the difference between the front and rear rotational speeds of the starting clutch 3 becomes equal to or greater than the reference rotational speed N1 (time t6), the starter start delay request is terminated and cranking (motoring) of the engine 1 by the starter motor 1S is permitted. Is done. Therefore, the engine speed NE increases as a result of cranking (motoring). At the same time, the control mode of the starting clutch 3 is switched to the constant pressure (low pressure) standby control mode when the engine is restarted. Therefore, switching to the restart constant pressure (low pressure) standby control mode is delayed in the same manner as the starter activation delay. As a result, the engine rotational speed NE and the turbine rotational speed NT are maintained in a state having a constant differential rotational speed. When the restart of the engine 1 is completed and the drive shaft torque increases to a positive torque, that is, when the vehicle is in a driving state (powering state), the control mode of the start clutch 3 is switched to the engagement control mode (t7). Time).

  For comparison, FIG. 6 is a time chart showing changes in each rotation speed, command pressure, and the like when the clutch 3 and 10 release control and engine stop control are performed by conventional deceleration S & S control. The example shown here is an example in which the brake is operated and the vehicle is decelerating in the accelerator-off state, and idle on fuel cut (FC) control is executed. In this state, when the vehicle speed decreases and reaches the lower limit rotational speed at which the lockup clutch 10 should be gradually released (at time t11), the command pressures of the clutches 3 and 10 decrease stepwise, and then decrease with a predetermined gradient. It is done.

  When the transmission torque capacity of each clutch 3 and 10 decreases, the engine speed NE decreases with respect to the turbine speed NT, and when the vehicle speed V decreases to the idling-on-fuel cut return speed, the fuel cut control is stopped. Then, the fuel supply to the engine 1 is resumed (at time t12). As a result, the drive shaft torque increases (negative torque decreases), and the engine speed NE decreases to the idle speed.

  When the vehicle speed V decreases to the engine stop vehicle speed by the deceleration S & S control (at time t13), the ignition timing retardation control is started. When the ignition timing is retarded to the misfire limit, the eco-run fuel cut (FC) control is started and the fuel supply to the engine 1 is stopped, so that the engine speed NE and the turbine speed NT are rapidly decreased. It reaches “0”.

  Comparing the example shown in FIG. 5 by the control device of the present invention described above with the example shown in FIG. 6 by the conventional control, the stop timing of the engine 1 can be greatly advanced by the control according to the present invention. it can. Further, according to the control device of the present invention, a restart request for the engine 1 may be generated during the release control of the start clutch 3 as the stop of the engine 1 is put forward. Since the starter activation delay control and the sudden release control of the starting clutch 3 are executed, the delay in restarting the engine 1 can be shortened as much as possible, and a sense of incongruity such as a shock accompanying the restart of the engine 1 can be avoided. Can do.

  Here, the relationship between the above specific example and the present invention will be briefly described. The functional means for executing the control in step S109 described above corresponds to the lowering instruction means in the present invention, and the control in step S304 described above. The functional means for executing is equivalent to the stopping means in the present invention, and the functional means for executing the control in step S405 is equivalent to the quick opening instruction means in the present invention, and further in step S404 above. The functional means for executing the control corresponds to the activation delay means in the present invention, and the functional means for executing the control in step S102 corresponds to the permission means in the present invention.

  The present invention is not limited to the specific examples described above, and the starting clutch may be a clutch whose transmission torque capacity is electrically controlled, in addition to a clutch whose transmission torque capacity is changed by hydraulic pressure. In this case, the current or the transmission torque capacity is the object of control instead of the hydraulic pressure. The vehicle targeted by the present invention may be a vehicle that does not include a lock-up clutch or a torque converter. In this case, the start clutch 3 to be controlled is only the start clutch.

  DESCRIPTION OF SYMBOLS 1 ... Engine, 1S ... Starter motor, 2 ... Torque converter, 3 ... Starting clutch, 7 ... Pump impeller, 8 ... Turbine, 10 ... Lock-up clutch, 11 ... Electronic control apparatus.

Claims (4)

The engine is automatically stopped in a vehicle provided with a starting clutch capable of changing the torque of the engine in accordance with the transmission torque capacity between the engine and the drive wheel, the torque of which decreases by retarding the ignition timing. In the restart control device,
A lowering instruction means for lowering the transmission torque capacity of the starting clutch when a condition for automatically stopping the engine is satisfied without depending on a driver's stopping operation;
Stop means for stopping the engine self-rotation after retarding the ignition timing and lowering the output torque of the engine in the process of reducing the transmission torque capacity of the starting clutch;
When the condition for restarting the engine is satisfied before the determination that the start clutch is released is satisfied, the rate of decrease in the transmission torque capacity of the start clutch is increased so that the start clutch is released. A quick opening instruction means;
When the condition for restarting the engine is satisfied, the control for delaying the start of the starter for rotating the engine to restart the engine is used to increase the rate of decrease in the transmission torque capacity of the starting clutch by the sudden release instruction means. A control device for automatic stop and restart of an engine in a vehicle, characterized by comprising start delay means that is executed in advance. The starting clutch includes a friction clutch that is engaged by hydraulic pressure and has a transmission torque capacity corresponding to the hydraulic pressure,
The lowering instruction means includes means for giving an instruction to lower the hydraulic pressure of the friction clutch,
When the absolute value of the difference between the rotational speed on the input side and the rotational speed on the output side of the friction clutch is equal to or higher than a predetermined reference rotational speed and the indicated value of the hydraulic pressure is equal to or lower than a predetermined value, the stop means The control device for automatic engine stop and restart in a vehicle according to claim 1, further comprising permission means for permitting the self-rotation of the engine to stop.   3. The automatic engine stop in the vehicle according to claim 1, wherein the retard timing control of the ignition timing is configured to start when the vehicle speed of the vehicle decreases to a predetermined vehicle speed. 4. And restart control unit. A torque converter having a lock-up clutch is arranged in series with the starting clutch;
The lowering instruction means includes means for lowering the transmission torque capacity of the lockup clutch,
4. The engine automatic stop and restart control in a vehicle according to claim 1, wherein the sudden opening means includes means for increasing a rate of decrease in the transmission torque capacity of the lockup clutch. apparatus.

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