JP2009127763A - Automatic transmission control device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an automatic transmission control device enabling to suppress a variation in the acceleration of a vehicle during down-shift while improving the accelerating performance of the vehicle. <P>SOLUTION: The control device is mounted on the vehicle 1, and applied to an automatic transmission 5 which is provided in a power transmission passage between an internal combustion engine 2 and a driving wheel 9 for changing over a gear ratio into a plurality of ones mutually different in size. It controls the automatic transmission 5 to execute down-shift which changes over the gear ratio to be smaller to greater when sudden accelerating operation is performed on an accelerator pedal 10 to change an throttle opening for the internal combustion engine 1 a predetermined amount or more to a valve opening side. It sets a target acceleration α to be generated by the vehicle 1 at a before-change gear ratio as a gear ratio before the down-shift is executed, when the sudden accelerating operation is performed, and it prohibits the execution of the down-shift when the acceleration of the vehicle 1 in the forward travelling direction after the sudden accelerating operation is performed is the target acceleration α or lower. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a control device for an automatic transmission that is provided in a power transmission path between an internal combustion engine and drive wheels of a vehicle and that can be switched to a plurality of gear ratios having different sizes.

  An automatic transmission that is provided in a power transmission path between an internal combustion engine and a drive wheel and that can be switched to a plurality of gear ratios having different sizes by switching a connection state of a plurality of gears provided inside is known. It has been. As is well known, in such an automatic transmission, the gear ratio is automatically switched based on the traveling state of the vehicle and the request from the driver. In such a control device that automatically switches the gear ratio of the automatic transmission, it is known to perform a downshift that switches the gear ratio from small to large when the driver requests rapid acceleration of the vehicle. (See Patent Document 1). In addition, Patent Documents 2 and 3 exist as prior art documents related to the present invention.

JP-A-5-133461 JP-A-3-172666 Japanese Patent Laid-Open No. 2-107865

  By the way, in such an automatic transmission, when switching the gear ratio, first, the gear connected to the gear ratio before the change is switched from the connected state to the released state in which the meshing of each gear is released, and then from the released state to the changed gear state. Is switched to the gear connected state corresponding to the gear ratio. In this released state, the meshing of the gears of the automatic transmission is released, so that the power of the internal combustion engine is not transmitted to the drive wheels and the vehicle acceleration decreases. When the driver demands rapid acceleration of the vehicle and the downshift of the automatic transmission is executed, first the throttle opening of the internal combustion engine is opened, so that the rotational speed of the internal combustion engine increases and the acceleration of the vehicle increases. The vehicle is accelerated. Thereafter, a downshift is performed. At this time, the temporary automatic transmission is released, and the acceleration of the vehicle decreases. Then, when switching from the released state to the gear connected state corresponding to the changed gear ratio, the power of the internal combustion engine is transmitted to the drive wheels, the acceleration of the vehicle is increased again, and the acceleration of the vehicle is resumed. Further, since the gear ratio is larger after downshifting, the acceleration of the vehicle is more likely to increase. Therefore, if the difference between the acceleration of the vehicle before the downshift is performed and the acceleration of the vehicle after the downshift is large, the variation in the acceleration of the vehicle increases. In this case, vibrations in the front-rear direction of the vehicle may occur, which may cause discomfort to the driver. Further, if the acceleration of the vehicle fluctuates greatly during downshifting, the acceleration of the vehicle may be deteriorated.

  Therefore, an object of the present invention is to provide a control device for an automatic transmission that can suppress fluctuations in the acceleration of the vehicle during downshifting and can improve the acceleration of the vehicle.

  An automatic transmission control device according to the present invention is mounted on a vehicle and is provided in a power transmission path between an internal combustion engine and a drive wheel of the vehicle, and can be automatically switched to a plurality of gear ratios having different sizes. When a sudden acceleration operation is applied to a transmission and the throttle opening of the internal combustion engine is to be changed to a valve opening side by a predetermined amount or more with respect to the accelerator pedal of the vehicle, the gear ratio is changed from a small one to a large one. In the control device including the control unit that controls the automatic transmission so that the downshift to be switched to is performed, the control unit is configured to perform the downshift before the downshift is performed when the sudden acceleration operation is performed. Target acceleration setting means for setting a target acceleration to be generated by the vehicle at a gear ratio before change that is a gear ratio, and acceleration in the forward direction of the vehicle after the sudden acceleration operation is performed In the following cases the target acceleration by and a down-shift inhibiting means for inhibiting the execution of the downshift, to solve the problems described above (Claim 1).

  According to the control device of the present invention, execution of the downshift is prohibited until the acceleration in the forward direction of the vehicle (hereinafter, referred to as forward acceleration) after the sudden acceleration operation becomes larger than the target acceleration. Therefore, by appropriately setting the target acceleration, the forward acceleration can be sufficiently increased in advance before the downshift is executed. Therefore, for example, by sufficiently increasing the forward acceleration in advance and making the forward acceleration close to the acceleration generated by the vehicle after the downshift is executed, the automatic transmission is released during the downshift and the forward acceleration is reduced. Even if it drops temporarily, the fluctuation range of the forward acceleration before and after that can be reduced. Therefore, fluctuations in forward acceleration can be suppressed. Moreover, since the vehicle can be accelerated stably and quickly by reducing the fluctuation range of the forward acceleration during the downshift in this way, the acceleration of the vehicle can be improved.

  In one form of the control device of the present invention, the target acceleration setting means may set the target acceleration based on a maximum value of acceleration that can be generated by the vehicle at the pre-change gear ratio. Item 2). In this case, for example, by suppressing the target acceleration to be equal to or less than the maximum value of acceleration that can be generated by the vehicle at the gear ratio before change, it is possible to prevent an excessive load from being applied to the internal combustion engine and the automatic transmission.

  In one embodiment of the control device of the present invention, the control means, when the sudden acceleration operation is performed, based on the operation amount given to the accelerator pedal in the sudden acceleration operation and the pre-change gear ratio. A gear ratio prediction means for predicting a post-change gear ratio that is a gear ratio to be set after the gear ratio is switched by downshift, and the post-change gear ratio predicted by the gear ratio prediction means and the accelerator pedal Acceleration prediction means for predicting acceleration in the forward direction of the vehicle after the downshift is executed based on the throttle opening after changing to the valve opening side in response to the sudden acceleration operation; The target acceleration setting means may set the target acceleration based on the acceleration predicted by the acceleration prediction means. In this case, for example, by setting the acceleration predicted by the acceleration prediction means as the target acceleration, it is possible to further suppress fluctuations in the forward acceleration during the downshift. Therefore, the acceleration performance of the vehicle can be further improved.

  In one form of the control device of the present invention, the vehicle may further include an acceleration detection means for detecting the longitudinal acceleration of the vehicle. In this case, the forward acceleration can be easily acquired.

  As described above, according to the control device of the present invention, since the forward acceleration can be sufficiently increased in advance before the downshift is executed, the fluctuation range of the forward acceleration before and after the downshift can be reduced. it can. Therefore, fluctuations in forward acceleration can be suppressed. Moreover, since the vehicle can be stably accelerated by reducing the fluctuation range of the forward acceleration in this way, the acceleration of the vehicle can be improved.

  FIG. 1 schematically shows a vehicle equipped with an automatic transmission to which a control device according to an embodiment of the present invention is applied. An internal combustion engine 2 is mounted on the vehicle 1 as a driving power source. The internal combustion engine 2 is a gasoline engine having a plurality of (four in FIG. 1) cylinders, and an automatic transmission 5 is connected to the crankshaft 3 via a torque converter 4. The torque converter 4 is a well-known one having a pump 4a connected to the crankshaft 3 and a turbine 4b connected to the input shaft 6 of the automatic transmission 5 in combination with the pump 4a. The automatic transmission 5 is a well-known automatic transmission that can switch the connection state of a plurality of gears provided therein and switch to a plurality of gear ratios having different sizes. The driving state of the vehicle 1 and the operation of the internal combustion engine 2 are known. It is switched to an appropriate gear ratio according to the state. In general, in the automatic transmission 5, a plurality of speeds (for example, five speeds) are set for forward movement, and a gear ratio of one speed is set for backward movement. The rotation of the output shaft 7 of the automatic transmission 5 is transmitted to the drive wheels 9 via the differential device 8. Thus, the automatic transmission 5 is provided in the power transmission path between the internal combustion engine 2 and the drive wheels 9.

  The internal combustion engine 2 and the automatic transmission 5 are controlled by an engine control unit (ECU) 20 as a control means. The ECU 20 is configured as a computer including a microprocessor and peripheral devices such as ROM and RAM necessary for its operation. As shown in FIG. 1, the ECU 20 outputs an accelerator opening sensor 21 that outputs a signal corresponding to the amount of operation of the accelerator pedal 10 by the driver, that is, an accelerator opening, and a signal corresponding to acceleration in the longitudinal direction of the vehicle. An acceleration sensor 22 serving as an acceleration detecting means, a crank angle sensor 23 for outputting a signal corresponding to the rotational speed (rotational speed) of the crankshaft 3, and the speed of the vehicle 1 (hereinafter sometimes abbreviated as vehicle speed). An output signal from a vehicle speed sensor 24 or the like that outputs a corresponding signal is input. Although the output signals of sensors other than these are also input to the ECU 20, they are not shown.

  For example, when the driver performs a rapid acceleration operation to change the throttle opening of the internal combustion engine 2 to the valve opening side by a predetermined amount or more with respect to the accelerator pedal 10, the ECU 20 sets the throttle opening of the internal combustion engine 2 to the valve opening side. And the automatic transmission 5 is controlled so that a downshift for changing the gear ratio from a small one to a large one is executed. Hereinafter, this speed ratio control may be referred to as kickdown control. The change of the gear ratio in the kick-down control is performed by, for example, storing a map indicating the correspondence between the operation amount of the accelerator pedal 10 and the number of steps to be dropped from the current gear ratio by the kick-down control in the ROM of the ECU 20. You can refer to the map.

  FIG. 2 shows a kickdown control routine that the ECU 20 repeatedly executes at a predetermined cycle during the operation of the internal combustion engine 2 in order to execute the kickdown control of the automatic transmission 5 in this way. In the control routine of FIG. 2, the ECU 20 first acquires the traveling state of the vehicle 1 in step S11. As the traveling state of the vehicle 1, for example, the vehicle speed, the number of rotations of the crankshaft 3, the accelerator opening degree, the acceleration related to the longitudinal direction of the vehicle, and the like are acquired. In the next step S12, the ECU 20 determines whether or not a predetermined kickdown execution condition is satisfied. It is determined that the kick-down execution condition is satisfied, for example, when the driver depresses the accelerator pedal 10 by a predetermined amount or more in order to rapidly accelerate the vehicle 1 as described above. As the predetermined amount, for example, about half of the stroke in which the accelerator pedal 10 is movable is set. If it is determined that the kickdown execution condition is not satisfied, the current control routine is terminated.

  On the other hand, when it is determined that the kick-down execution condition is satisfied, the process proceeds to step S13, and the ECU 20 determines whether a predetermined precondition is satisfied. When it is determined that the kick-down execution condition is satisfied, the ECU 20 changes the throttle opening of the internal combustion engine 2 to the valve opening side as described above. For example, it is determined that the precondition is satisfied when the acceleration sensor 22 operates normally. Further, since the acceleration sensor 22 detects the acceleration in the front-rear direction of the vehicle 1 even when the vehicle 1 is climbing, for example, when the acceleration sensor 22 does not detect the acceleration due to the tilt state of the vehicle 1 in this way. It is determined that the precondition is satisfied. The inclination state of the vehicle 1 may be detected by providing the vehicle 1 with a sensor that detects the inclination of the vehicle 1 or by referring to information such as GPS for grasping the current location of the vehicle 1. The determination may be made based on whether the vehicle is traveling on a slope. If it is determined that the precondition is not satisfied, steps S14 to S17 are skipped and the process proceeds to step S18.

  On the other hand, if it is determined that the precondition is satisfied, the process proceeds to step S14, where the ECU 20 determines whether or not the target acceleration α has already been set. The target acceleration α indicates the forward acceleration of the vehicle 1 that should be reached before kick-down control is performed. If it is determined that the target acceleration α has already been set, the process skips step S15 and proceeds to step S16. On the other hand, if it is determined that the target acceleration α is not set, the process proceeds to step S15, where the ECU 20 sets the target acceleration α. The target acceleration α can be generated by the vehicle 1 at, for example, the current gear ratio of the automatic transmission 5, that is, the gear ratio before executing the kick-down control (hereinafter sometimes referred to as a gear ratio before change). Is set based on the maximum value of the acceleration (hereinafter sometimes referred to as the maximum acceleration). The maximum acceleration can be predicted based on a predicted load factor calculated from a load predicted to be required for the internal combustion engine 2 after the throttle opening is changed, the rotational speed of the internal combustion engine 2, the speed ratio before change, the vehicle speed, and the like. . For example, the predicted load factor is calculated based on the throttle opening after the ECU 20 has changed to the valve opening side when the kick-down execution condition is satisfied, and the throttle opening is multiplied by the number of revolutions of the internal combustion engine 2. The generated torque that is expected to be generated after changing the value is calculated. Then, the maximum acceleration is calculated based on the generated torque, the pre-change gear ratio, and the vehicle speed. This maximum acceleration may be set as the target acceleration α, or a value obtained by multiplying the maximum acceleration by a safety factor of about 0.8 in order to reliably prevent an excessive load on the internal combustion engine 2 is set. May be.

  In subsequent step S <b> 16, the ECU 20 acquires the acceleration in the forward direction of the vehicle 1 (forward acceleration) based on the output signal of the acceleration sensor 22. At this time, the ECU 20 performs an averaging process, a filter process for removing noise, and the like on the output signal of the acceleration sensor 22, and acquires a forward acceleration based on the output signal after performing these processes. May be.

  In the next step S17, the ECU 20 determines whether or not the acquired forward acceleration is larger than the target acceleration α. When it is determined that the forward acceleration is larger than the target acceleration α, the process proceeds to step S18, and the ECU 20 executes kick-down control. Thereafter, the current control routine is terminated. On the other hand, if it is determined that the forward acceleration is equal to or less than the target acceleration α, the process proceeds to step S19, and the ECU 20 prohibits execution of kick-down control. Thereafter, the current control routine is terminated.

  FIG. 3 shows an example of a temporal change in the forward acceleration when the kick down control routine of FIG. 2 is executed and the kick down control is executed after the forward acceleration exceeds the target acceleration α. Note that the line L1 in FIG. 3 shows the time change of the forward acceleration. A line G in FIG. 3 shows a change over time in the gear ratio of the automatic transmission 5. In FIG. 3, the gear ratio is indicated by a transmission gear (stage) corresponding to each gear ratio. As shown in FIG. 3, in this kick down control, the transmission gear of the automatic transmission 5 is switched from the fifth speed to the third speed via the fourth speed. A line S in FIG. 3 shows a time change of the throttle opening. FIG. 3 shows, as a comparative example, a broken line L2 as an example of a temporal change in the forward acceleration when the forward acceleration is not increased to the target acceleration α before the kickdown control is executed. In FIG. 3, the accelerator pedal 10 is operated at time t, and the kick-down execution condition is satisfied. Thereafter, the throttle opening is first opened, and then the transmission gear of the automatic transmission 5 is switched. As is apparent from FIG. 3, the fluctuation range Δ1 of the forward acceleration when the kickdown control is executed after the forward acceleration is made larger than the target acceleration α is the kickdown control without increasing the forward acceleration to the target acceleration α. It is smaller than the fluctuation range Δ2 of the forward acceleration when executed.

  Thus, by prohibiting the execution of kickdown control until the forward acceleration becomes greater than the target acceleration α and sufficiently increasing the forward acceleration, the fluctuation range of the forward acceleration before and after the kickdown control and when the control is executed can be reduced. Can be small. Therefore, fluctuations in forward acceleration in kick down control can be suppressed. Moreover, since the vehicle 1 can be accelerated stably and rapidly by suppressing the fluctuation | variation of a forward acceleration in this way, the acceleration property of the vehicle 1 can be improved. Note that the ECU 20 functions as the downshift prohibiting means of the present invention by executing the processing of steps S17 to S19 in FIG.

  Since the target acceleration α is set based on the maximum acceleration, it is possible to prevent an excessive load from being applied to the internal combustion engine 2.

  The method for setting the target acceleration α is not limited to the method described above. For example, in step S15 of FIG. 2, the ECU 20 first predicts a gear ratio to be set after switching in the kickdown control (hereinafter, may be referred to as a post-change gear ratio), and then predicts this change. The forward acceleration after the kick-down control is executed is predicted based on the rear gear ratio and the throttle opening after the ECU 20 changes to the valve opening side when the kick-down execution condition is satisfied, and then the predicted forward acceleration is calculated. The target acceleration α may be set based on the above. In this case, for example, the predicted forward acceleration is set as the target acceleration α. Further, when it is impossible to increase the acceleration of the vehicle 1 to the predicted forward acceleration at the gear ratio before change, a value obtained by multiplying the predicted forward acceleration by a predetermined coefficient (for example, 0.8) is set as the target acceleration. You may set to (alpha). Thus, by setting the target acceleration α based on the forward acceleration after the kick-down control is executed, fluctuations in the forward acceleration before and after the kick-down control and when this control is executed can be further suppressed. Therefore, the vehicle 1 can be accelerated more stably and quickly. Note that the ECU 20 functions as a speed ratio predicting unit and an acceleration predicting unit of the present invention by predicting the post-change gear ratio or predicting the forward acceleration after the kick-down control is executed in this way.

  The present invention is not limited to the above-described form and can be implemented in various forms. For example, the internal combustion engine connected to the automatic transmission to which the present invention is applied may be a diesel engine. The acceleration of the vehicle may be estimated based on the vehicle speed, the operating state of the internal combustion engine, the inclination of the vehicle, and the like.

The figure which shows the outline of the vehicle carrying the automatic transmission with which the control apparatus which concerns on one form of this invention was applied. The flowchart which shows the kickdown control routine which ECU of FIG. 1 performs. The figure which shows an example of the time change of a forward acceleration when kickdown control is performed after a forward acceleration exceeds target acceleration.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Vehicle 2 Internal combustion engine 5 Automatic transmission 9 Drive wheel 10 Accelerator pedal 20 Engine control unit (a control means, a target acceleration setting means, a downshift prohibition means, a gear ratio prediction means, an acceleration prediction means)
22 Acceleration sensor (acceleration detection means)
α Target acceleration

Claims (4)

An accelerator pedal for a vehicle that is mounted on a vehicle and is provided in a power transmission path between an internal combustion engine and a drive wheel of the vehicle and can be switched to a plurality of gear ratios having different sizes from each other. On the other hand, when a rapid acceleration operation that should change the throttle opening of the internal combustion engine to a valve opening side by a predetermined amount or more is performed, a downshift for switching the gear ratio from small to large is performed. In a control device comprising a control means for controlling an automatic transmission,
The control means, when the sudden acceleration operation is performed, target acceleration setting means for setting a target acceleration to be generated by the vehicle at a gear ratio before change that is a gear ratio before the downshift is performed; An automatic transmission comprising: downshift prohibiting means for prohibiting execution of the downshift when acceleration in the forward direction of the vehicle after the sudden acceleration operation is equal to or less than the target acceleration. Control device.   2. The control apparatus for an automatic transmission according to claim 1, wherein the target acceleration setting means sets the target acceleration based on a maximum value of acceleration that can be generated by the vehicle at the pre-change gear ratio. When the sudden acceleration operation is performed, the control means switches the gear ratio in the downshift based on the operation amount given to the accelerator pedal in the sudden acceleration operation and the gear ratio before change. A gear ratio predicting means for predicting a post-change gear ratio that is a gear ratio to be set later; and the valve opening in response to the post-change gear ratio predicted by the gear ratio predicting means and the rapid acceleration operation on the accelerator pedal Acceleration prediction means for predicting acceleration in the forward direction of the vehicle after the downshift is executed based on the throttle opening after changing to the side,
The control apparatus for an automatic transmission according to claim 1, wherein the target acceleration setting means sets the target acceleration based on the acceleration predicted by the acceleration prediction means.   The control device for an automatic transmission according to any one of claims 1 to 3, further comprising acceleration detection means for detecting acceleration in the longitudinal direction of the vehicle.

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