JP5374426B2 - Control device for automatic transmission for vehicle - Google Patents

Description

  The present invention relates to a control device for an automatic transmission mounted on a vehicle such as an automobile, and more particularly to a control device for suppressing gear wear in an automatic transmission using a planetary gear mechanism.

  In an automatic transmission using a planetary gear mechanism, there is a shift stage called a “direct connection stage” in which the gears in the planetary gear mechanism do not rotate relative to each other. In the “directly connected stage”, the gears in the planetary gear mechanism remain engaged at the same position. If continuous operation is performed for a long time in this state, a concave surface due to fretting wear occurs on the tooth surface of each gear due to the influence of engine torque fluctuation or the like. When such a concave surface due to fretting wear occurs, the tooth contact of the gear is deteriorated, resulting in a deterioration of merchantability due to gear noise, and the durability is also deteriorated.

  In order to cope with such problems, the surface of the gear is subjected to a wear-resistant surface treatment, the gear material is changed to a wear-resistant one, or the lubricating oil is supplied to the tooth surface. Conventionally, the lubricating oil is optimized by providing a lubricating oil hole in the tooth bottom. However, these processes have a drawback of increasing costs. In view of this point, in Patent Document 1 below, if a gear stage in which the gears in the planetary gear mechanism remain engaged at the same position is selected, if a predetermined condition is satisfied (for example, When this state continues for a predetermined time or torque is reduced, control for temporarily switching to another gear stage is performed.

JP 2003-343708 A

  The technique disclosed in Patent Document 1 has a problem that a hunting phenomenon may occur if the gear stage is temporarily switched repeatedly. In addition, when the torque is reduced by the driver's brake operation or throttle closing operation, the effectiveness of the engine brake will change by switching the gear to the driver's intention to decelerate. Therefore, there is a problem of impairing drivability.

  The present invention has been made in view of the above-described points, so that hunting phenomenon due to frequent switching of gear stages does not occur, and fretting wear of gears can be suppressed without impairing drivability. An object of the present invention is to provide a control device for an automatic transmission for a vehicle.

  The automatic transmission control device according to the present invention includes an automatic transmission control means (11) for setting a shift stage of the automatic transmission to a predetermined shift stage according to a running state of the vehicle, and a shift stage of the automatic transmission. And a manual shift control means (12) for setting the gear to the gear selected by the driver, the current gear of the automatic transmission is the current gear Directly connected gear determining means (13) for determining whether or not the gears constituting the gears are in a directly connected gear that maintains a meshed state without relative rotation, and whether or not the vehicle is in an accelerated state. The vehicle acceleration state determining means (14) for determining whether or not the current shift control mode of the automatic transmission is controlled by the automatic shift mode in which the shift control is performed by the automatic shift control means and the manual shift control means. Manual change A shift mode determination hand throw (15) for determining which mode is in order to set the current shift stage when it is determined that the current shift stage of the automatic transmission is the direct coupling stage Engagement control means (16) which controls to weaken the engagement force while maintaining the engagement state of the frictional engagement element, thereby causing the meshing surfaces of the gears constituting the current gear stage to slip. And when the vehicle acceleration state determination means determines that the vehicle is not in an acceleration state, control is performed to weaken the engagement force of the friction engagement element, and in the automatic shift mode, the direct connection is performed. Control is performed to weaken the engagement force of the friction engagement element after a lapse of a predetermined time since it is determined to be a step, and in the manual shift mode, the friction engagement is not waited for a lapse of a predetermined time after the determination of the direct connection step. Engagement force of joint element And Toku撤 by comprising the said engagement control means (16) for controlling weakening. Note that the reference numbers in parentheses indicate the reference numbers of each element in the embodiment described later corresponding to each component of the present invention for reference only.

  Decreasing the engagement force while maintaining the engagement state of the friction engagement element means reducing the engagement force while maintaining the engagement state of the friction engagement element (clutch). To cause slippage. As a result, a subtle rotational difference is generated between the gears connected to the input / output shafts of the friction engagement elements (clutch) (between the gears engaged in the direct connection state), and the current gear stage is configured. Subtle slippage can be caused on the meshing surfaces of the gears.

  According to the present invention, when it is determined that the current shift stage of the automatic transmission is a direct coupling stage, the engagement state of the friction engagement element for setting the current shift stage is maintained. Since the control is performed so that the meshing surfaces of the gears constituting the current gear stage are caused to slip by weakening the resultant force, it is possible to slightly change the meshing position of the tooth surface that transmits power. Thus, fretting wear can be prevented. At this time, since control is performed to weaken the engagement force of the friction engagement element at least when it is determined that the vehicle is not in the acceleration state, the engagement of the friction engagement element is inadvertently performed in the acceleration state. Control that weakens the resultant force is not performed, and drivability is not impaired. In addition, since the control is performed so as to weaken the engagement force of the friction engagement element by changing the start condition between the automatic shift mode and the manual shift mode, the manual shift mode responds immediately to the shift operation to the direct coupling stage. Thus, control for weakening the engagement force of the friction engagement element can be performed. This is because when the shift operation to the direct connection stage is performed in the manual shift mode, it is predicted that the state of the shift stage (direct connection stage) will be maintained to some extent. On the other hand, in the automatic transmission mode, it is preferable to wait for the elapse of a predetermined time without immediately performing control to weaken the engagement force of the friction engagement element even when there is a shift to the direct coupling stage. This is because the control that weakens the engagement force of the frictional engagement element may cause wear and heat generation due to sliding friction of the frictional engagement element. Therefore, if the fastening to the direct coupling stage is not maintained for a predetermined time or more, fretting wear will be reduced. This is because it is configured to be advantageous for maintenance of the friction engagement element in consideration of no influence. Further, in the present invention, the current shift speed is maintained without being temporarily switched to another shift speed, so that a hunting phenomenon due to frequent switching of the shift speed does not occur, and drivability may be impaired. Absent.

  In one embodiment, the engagement control means (16) further includes, from the vehicle drive source, when the vehicle acceleration state determination means (14) determines that the vehicle is in an acceleration state. Control is performed to weaken the engagement force of the friction engagement element on condition that the driving force input to the automatic transmission is less than a predetermined threshold value. Here, the predetermined threshold is intended to distinguish the degree of acceleration, and if the driving force input to the automatic transmission is greater than or equal to the predetermined threshold, strong acceleration, if less than the threshold, weak acceleration, Can be said. And in this embodiment, if it is a weak acceleration state, control which weakens the engagement force of a friction engagement element is performed like the case where it is not an acceleration state, and a measure for preventing fretting wear is thus taken. . In addition, since it is possible to maintain responsiveness to strong acceleration, drivability can be ensured.

  In a further embodiment, the vehicle further comprises climbing road determination means (17) for determining whether or not the vehicle is traveling on an uphill road, and the engagement control means (16) includes the vehicle acceleration state determination means (14). ), When the vehicle is determined to be in an acceleration state and the uphill road determination means determines that the vehicle is traveling on the uphill road, the predetermined threshold value is switched to a second threshold value smaller than that, Control is performed to weaken the engagement force of the friction engagement element on condition that the drive force input from the drive source of the vehicle to the automatic transmission is less than the second threshold value. In this embodiment, since the threshold value is lowered in the uphill state, control is performed to weaken the engagement force of the friction engagement element only in a region where the driving force input to the automatic transmission is smaller than when traveling on flat ground. Is called. Accordingly, it is possible to appropriately take measures for preventing fretting wear while ensuring drivability during climbing.

The block diagram which shows the outline of the power transmission system and control system of a vehicle provided with the control apparatus which concerns on one Embodiment of this invention. The skeleton figure which shows an example of the power transmission structure of the automatic transmission in the embodiment. The table which lists the gear stage achieved by the combination of engagement and release of each clutch and brake in the power transmission configuration shown in FIG. The flowchart which shows an example of the program which makes a computer perform the control which the control apparatus which concerns on this invention performs.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.
FIG. 1 is a block diagram showing an outline of a power transmission system and a control system of a vehicle provided with a control device according to an embodiment of the present invention. The power transmission system of the vehicle is set by inputting the engine 1 as a power source, the torque converter 2 as a fluid coupling for transmitting the rotational output of the engine 1 to the transmission gear mechanism 3, and the rotational output of the torque converter 2. And a differential gear mechanism 4 that distributes the output rotation of the transmission gear mechanism 3 to left and right wheels (for example, rear wheels) 5. A hydraulic control device 6 is provided with the torque converter 2 and the transmission gear mechanism 3, and the hydraulic control device 6 is a hydraulic control type engagement element (inside the torque converter 2 and the transmission gear mechanism 3). By engaging or releasing a clutch or the like in a predetermined combination, the torque converter 2 is locked up and the input / output speed ratio in the transmission gear mechanism 3 is set to a required gear stage. The automatic transmission of the vehicle includes the torque converter 2, the transmission gear mechanism 3, the hydraulic control device 6, and the like.

  A control system for controlling the automatic transmission of the vehicle includes various sensors 11 provided in each part of the vehicle, an electronic control unit (ECU) 10 to which outputs of the various sensors are input, and the electronic control unit 10. The hydraulic control device 6 is controlled. The shift lever position sensor 12 detects the position of the shift lever operated by the driver. As is well known, shift lever positions include, for example, P (parking), R (reverse travel), N (neutral), D (advance travel in automatic transmission mode), etc. There is a manual shift position for manually specifying a specific shift speed such as speed or 1st speed. As is well known, the manual shift operation means for the manual shift mode is not limited to the type attached to the shift lever, but is provided with a shift up switch and a shift down switch ( Paddle switch) or the like.

  The specific configuration of the vehicle power transmission system and the control system shown in FIG. The automatic transmission control device according to the present invention is included in the electronic control unit 10 and is implemented as one of various control functions that can be realized by the electronic control unit 10. The functions (means) related to the present invention realized by the electronic control unit 10 will be described as follows.

  Automatic shift control means 11: The shift stage of the automatic transmission is set to a predetermined shift stage according to the running state of the vehicle. Since it is publicly known, further detailed explanation is omitted.

  Manual shift control means 12: Sets the shift stage of the automatic transmission to the shift stage selected by the driver. Since it is publicly known, further detailed explanation is omitted.

  Direct coupling stage determining means 13: Whether or not the current gear stage of the automatic transmission is a direct coupling stage having a meshing form in which the gears constituting the current gear stage are kept in mesh with each other without relative rotation. Determine whether. An example will be described later because it is known but important for understanding the present invention.

  Vehicle acceleration state determination means 14: It is determined whether or not the vehicle is in an acceleration state. Based on the change in the vehicle speed sensor output or the accelerator pedal opening degree, it may be determined whether or not the vehicle is in an acceleration state by a known method.

  Shift mode determination hand throw 15: Whether the current shift control mode of the automatic transmission is the automatic shift mode in which the shift control is performed by the automatic shift control means 11 or the manual shift mode in which the shift control is performed by the manual shift control means 12 Determine. According to a known method, the determination may be made based on the position of the shift lever, the operation state of the manual shift operation means, and the like.

  Engagement control means 16: When it is determined that the current gear position of the automatic transmission is the direct gear position, the engagement state of the friction engagement element (clutch) for setting the current gear position is maintained. In this state, the control is performed to weaken the engaging force, thereby causing the meshing surfaces of the gears constituting the current gear to slip. Here, at least when the vehicle is determined not to be in an accelerating state, control is performed to weaken the engagement force of the friction engagement element, and in the automatic shift mode, the direct connection stage is determined and a predetermined time elapses after the determination. Control is performed to weaken the engagement force of the friction engagement element (clutch), but in the manual shift mode, the engagement force of the friction engagement element (clutch) is not waited for a predetermined time after it is determined that the direct connection stage. Control to weaken. The engagement control means 16 is related to the gist of the present invention and will be described in detail later.

  Uphill road judging means 17: It is judged whether or not the vehicle is traveling on the uphill road. It is possible to determine whether the vehicle is traveling on an uphill road according to a known method such as detecting the inclination angle of the vehicle body with respect to the horizontal plane or correlating the amount of depression of the accelerator pedal and the detected vehicle speed acceleration.

  FIG. 2 is a skeleton diagram showing an example of a power transmission configuration of the transmission gear mechanism 3. In the figure, the speed change gear mechanism 3 of the automatic transmission outputs a speed change rotation by inputting the speed increasing planetary mechanism G1 for increasing the output of the input shaft and outputting the speed increasing rotation from the speed increasing planetary mechanism G1. The speed-up planetary mechanism G2 and the speed-up planetary mechanism G1 and the speed-change planetary mechanism G2 constitute an automatic transmission that achieves a forward speed of six forward speeds and a reverse speed of the first speed.

  The speed increasing planetary mechanism G1 has a carrier Cz as an input element coupled to an input shaft, and a plurality of pinion gears Pz are arranged on the carrier Cz, and the pinion gears Pz are the sun gear Sz and the ring gear Rz. The sun gear Sz that is the reaction force element is fixed, and the speed-up rotation is output to the ring gear Rz that is the output element. The ring gear Rz is coupled to the carrier Cr of the speed planetary mechanism G2 via the clutch C2. By the engagement of the clutch C2, the output of the speed increasing planetary mechanism G1 is input to the speed changing planetary mechanism G2.

Shifting planetary mechanism G2 supports two and sun i.e. large sun gear S _L and the small-diameter sun gear Ss having different diameters, the short pinion Ps that meshes with the long pinion P _L and a small diameter sun gear Ss meshed with the large sun gear S _L It is composed of a Ravigneaux type planetary gear mechanism composed of a carrier Cr. Long pinion P _L meshes with large-diameter sun gear S _L and meshes with ring gear Rr, and short pinion Ps meshes with small-diameter sun gear Ss. The carrier Cr is configured such that the rotation of the ring gear Rz of the speed increasing planetary mechanism G1 is transmitted via the clutch C2, and can be locked to the transmission case by the brake B2. F1 is a one-way clutch. A ring gear Rz as an output element for variable speed rotation is connected to the output shaft.

The large-diameter sun gear S _L is installed coaxially with the small-diameter sun gear Ss. The large-diameter sun gear S _L and the small-diameter sun gear Ss function as input elements for non-accelerated rotation (input rotation that does not pass through the acceleration planetary mechanism G1) in the speed-change planetary mechanism G2. The small-diameter sun gear Ss is connected to the clutch C1, and the input from the input shaft is transmitted to the small-diameter sun gear Ss via the clutch C1. Large sun gear S _L is connected to the clutch C3, an input from the input shaft is transmitted to the large diameter sun gear S _L via the clutch C3. Further, the large-diameter sun gear S _L, the brake B1 is adapted to be fixed to the transmission case.

  In the transmission gear mechanism 3 configured as described above, the clutches C1 to C3 and the brakes B1 and B2 are engaged so as to achieve the shift stage instructed by the automatic transmission control means 11 or the manual transmission control means 12 of the electronic control unit 10. And release. FIG. 3 is a table showing each shift speed achieved by a combination of engagement and disengagement of the clutches C1 to C3 and the brakes B1 and B2, where “◯” indicates engagement and “No” indicates disengagement. Since such a transmission gear mechanism 3 is publicly known, the “direct coupling stage” related to the present invention will be described next, and the description of each other transmission stage will be omitted.

The transmission gear mechanism 3 having the configuration shown in FIGS. 2 and 3 corresponds to a “direct coupling stage” having a meshing form in which the gears constituting the gear stage maintain the meshed state without relative rotation. Is the “third speed (3rd)”. The third speed (3rd) is achieved by simultaneous engagement of the clutch C1 and the clutch C3. In this case, the non-increased rotation of the input shaft is inputted to the small sun gear Ss and the large-diameter sun gear S _L at the same time shifting planetary mechanism G2 through the clutch C1 and the clutch C3, change speed planetary mechanism G2 is directly coupled. Therefore, rotation of the ring gear Rr is the input rotation and the rotation of the small sun gear Ss and the large-diameter sun gear S _L is outputted to the output shaft. The rotation of the ring gear Rr is the same as the rotation of the input shaft. Note that at the third speed, the clutch C2 is not engaged, and therefore, there is no input of the speed increasing rotation from the speed increasing planetary mechanism G1 to the speed changing planetary mechanism G2.

  When the automatic transmission control unit 11 or the manual transmission control unit 12 issues an instruction to achieve the “third speed (3rd)” in the transmission gear mechanism 3 in the above-described direct connection stage determination unit 13, It is determined that the gear position corresponding to “directly connected gear” is instructed as the current gear speed.

  FIG. 4 is a schematic flowchart showing an example of a computer program for causing a computer included in the electronic control unit 10 to execute processing and control according to the present invention. This flowchart is to cause the computer included in the electronic control unit 10 to execute the processing and control performed by the above-described means 11 to 17 according to the computer program. However, the control device according to the present invention is not limited to a computer program, and may be configured with dedicated electronic circuit hardware.

  FIG. 4 is executed in the course of an automatic shift control processing routine that is repeatedly executed at a predetermined cycle by a computer included in the electronic control unit 10. In step S1, it is determined whether or not the current gear position of the automatic transmission is the “directly coupled gear” (in this example, the third gear) (corresponding to the determination operation of the directly coupled gear determining means 13). If NO, go to step S2 and reset the count value of the predetermined timer TIME to 0. If YES, the process goes to step S3 to determine whether it is the manual shift mode (corresponding to the determination operation of the shift mode determination means 15).

  If it is the automatic transmission mode, the process goes from NO in step S3 to step S4, and determines whether the count value of the timer TIME is equal to or greater than a predetermined set value TIMEs. If the count value of the timer TIME has not reached the predetermined set value TIMEs, the process goes to step S5 to increment the count value of the timer TIME. On the other hand, when the count value of the timer TIME is equal to or greater than the predetermined set value TIMEs, the process proceeds from YES in step S4 to step S7. The predetermined set value TIMEs is used to set the predetermined time in order to start control for weakening the clutch engagement force after a predetermined time has elapsed since the direct connection stage is determined.

  On the other hand, if it is the manual shift mode, the process proceeds from YES in step S3 to step S6, resets the count value of the timer TIME to 0, and then proceeds to step S7.

In step S7, it is determined whether or not the vehicle is in an acceleration state (corresponding to the determination operation of the vehicle acceleration state determination means 14). If it is not in the acceleration state, control goes to step S8 to weaken the engagement force (slid the clutch) while maintaining the engagement state of the friction engagement element (clutch) for setting the current gear position. Thus, slippage occurs on the meshing surfaces of the gears constituting the current gear stage (corresponding to the control operation of the engagement control means 16). Here, the purpose of weakening the clutch engagement force is to cause slippage on the meshing surfaces of the gears constituting the current gear, so that the purpose can be achieved only at necessary places. What is necessary is just to perform control which weakens a clutch engaging force to a necessary extent. In the case of the example now described, the engagement clutches that set the current shift speed (third speed = directly connected) are C1 and C3, and either one of them is slid (the engagement force is weakened). You can do it. For example, when the clutch C3 is slid, the rotation of the input shaft is transmitted as it is to the small-diameter sun gear Ss, but the rotation transmitted to the large-diameter sun gear S _L is somewhat smaller than the rotation of the input shaft. A slight rotational difference between the sun gear S _L and the small-diameter sun gear Ss will occur. As a result, slippage occurs on the meshing surfaces of the gears of the speed-changing planetary mechanism G2 constituting the current gear stage, so that the meshing location of the tooth surface for transmitting power can be changed slightly. Fretting wear due to the fact that the meshing surface does not change for a long time can be prevented. On the other hand, when the sliding clutch C1, the rotation of the input shaft to the large sun gear S _L is transmitted as it is, the rotation transmitted to the small sun gear Ss becomes somewhat smaller ones than the rotation of the input shaft, the Even in this case, a slight rotational difference between the large-diameter sun gear S _L and the small-diameter sun gear Ss occurs, and fretting wear can be prevented.

  In summary, if the vehicle is determined not to be in an acceleration state by the process of YES through S1, NO in S3, YES in S4, NO in S7, and the route to S8, the automatic transmission mode Then, it is realized to perform control to weaken the engagement force of the clutch after a lapse of a predetermined time after it is determined as the direct coupling stage. Since fretting wear occurs when the meshing surface does not change for a certain period of time, in the automatic transmission mode, when it is determined that the gear is in the direct coupling stage, the control for weakening the clutch engagement force is not immediately started and the system waits for a predetermined time. In this way, the control for sliding the clutch is not carried out unnecessarily.

  In addition, if it is determined that the vehicle is not in the acceleration state by the process of the route from S1 YES, S3 YES, S6, S7 NO to S8 and the vehicle is not in the acceleration state, it is determined to be the direct gear stage Thereafter, it is possible to perform control to weaken the engaging force of the clutch without waiting for the elapse of the predetermined time (in this example, immediately). In manual shift mode, it can be considered that the driver intends to maintain a certain shift stage intended for a certain period of time, so it is not a wasteful control even if the control for sliding the clutch is performed immediately, Fretting wear can be effectively prevented.

  By the way, when it is determined in step S7 that the vehicle is in an acceleration state, the process goes to step S9 to determine whether or not the vehicle is traveling on an uphill road (corresponding to the determination operation of the uphill road determination means 17). If it is not running on an uphill road (running on a flat ground), the process goes from YES in S9 to step S11, and it is determined whether or not the driving force (input torque) Tin input from the engine 1 to the automatic transmission is equal to or greater than a predetermined threshold Ts. Determine (Tin ≧ Ts?). If NO, the process goes to step S8 to control the above-described clutch engagement force weakening (sliding the clutch). Even if the vehicle is in an accelerating state by the processing of the route from YES in S7 to NO in S9 and NO in S11, the input torque Tin of the automatic transmission does not satisfy the predetermined threshold Ts. Since it can be considered that the driver does not want high torque operation, the above-described control for weakening the clutch engagement force (sliding the clutch) is performed to take measures to prevent fretting wear. When the input torque Tin of the automatic transmission is equal to or greater than the predetermined threshold value Ts, the process goes from YES in S11 to the end and does not execute the process in step S8. In this case, it is assumed that the driver desires high-torque operation, and control for weakening the clutch engagement force (sliding the clutch) is not performed, so that drivability is not impaired.

  Further, if it is determined in step S9 that the vehicle is traveling on an uphill road, the process goes to step S10, and the predetermined threshold value Ts is switched to a value (second threshold value) smaller than that for flat ground traveling. In step S11, it is determined whether or not the driving force (input torque) Tin input from the engine 1 to the automatic transmission is equal to or greater than the threshold value Ts after switching (Tin ≧ Ts?). That is, in the uphill traveling, if the value of the predetermined threshold value Ts is lower than that during flat road traveling and the input torque Tin of the automatic transmission is less than the lowered threshold value (second threshold value) Ts, step S11 is performed. From NO in step S8, the above-described control for weakening the clutch engagement force (sliding the clutch) is performed to take measures to prevent fretting wear. In other words, when running on an uphill road, the clutch engagement force is weakened (sliding the clutch) to prevent fretting wear only in a region where the input torque Tin of the automatic transmission is lower than when running on flat ground. In a region higher than that, control for weakening the clutch engagement force (sliding the clutch) is not performed. This is because uphill road traveling requires a larger input torque Tin than when traveling on flat ground, so the control of weakening the clutch engagement force (sliding the clutch) is performed only in the region of lower input torque than when traveling on flat ground. By doing so, proper operation and drivability are ensured.

  In the above-described embodiment, when the gear is shifted to the direct gear in the manual shift mode, control is performed to immediately weaken the clutch engagement force (slid the clutch). However, the present invention is not limited to this. The predetermined time may be set to be smaller than the threshold value TIMEs in the automatic transmission mode. That is, in the manual shift mode, it is only necessary to perform control to weaken the clutch engagement force (slid the clutch) without waiting for the elapse of the predetermined time set by the threshold value TIMEs in the automatic shift mode. In addition, the determination of “running on an uphill road” in step S9 is not limited to during an uphill trip, but may be performed on a downhill.

DESCRIPTION OF SYMBOLS 1 Engine 3 Transmission gear mechanism 10 Electronic control unit 11 Automatic transmission control means 12 Manual transmission control means 13 Direct connection stage determination means 14 Vehicle acceleration state determination means 15 Transmission mode determination manual throw 16 Engagement control means 16
17 Climb judgment means

Claims (3)

Automatic shift control means for setting the shift stage of the automatic transmission to a predetermined shift stage according to the running state of the vehicle;
In a control device for an automatic transmission for a vehicle, comprising a manual shift control means for setting a shift stage of the automatic transmission to a shift stage selected by a driver,
Direct connection for determining whether or not the current gear position of the automatic transmission is a direct gear stage having a meshing form in which the gears constituting the current gear stage are engaged with each other without relative rotation. A step determining means;
Vehicle acceleration state determination means for determining whether or not the vehicle is in an acceleration state;
Shift mode determination for determining whether the current shift control mode of the automatic transmission is an automatic shift mode controlled by the automatic shift control means or a manual shift mode controlled by the manual shift control means Hand throwing,
Control that weakens the engagement force while maintaining the engagement state of the friction engagement element for setting the current shift stage when it is determined that the current shift stage of the automatic transmission is the direct coupling stage Thus, the engagement control means for causing the meshing surfaces of the gears constituting the current gear stage to slip, and at least the vehicle acceleration state determination means determines that the vehicle is not in the acceleration state. Control to weaken the engagement force of the frictional engagement element in the automatic shift mode, and control to weaken the engagement force of the frictional engagement element after a lapse of a predetermined time from the determination of the direct coupling stage. And, in the manual shift mode, the engagement control means for performing control to weaken the engagement force of the friction engagement element without waiting for the elapse of a predetermined time after it is determined as the direct coupling stage. Automatic transmission The control device.   In the case where the vehicle acceleration state determination unit determines that the vehicle is in an acceleration state, the engagement control unit further receives a predetermined driving force from the vehicle drive source to the automatic transmission. 2. The control device for an automatic transmission according to claim 1, wherein control for weakening an engagement force of the friction engagement element is performed on condition that the value is less than a threshold value. Further comprising an uphill judging means for judging whether or not the vehicle is traveling on an uphill,
When the vehicle acceleration state determination unit determines that the vehicle is in an acceleration state and the uphill road determination unit determines that the vehicle is traveling on an uphill road, the engagement control unit is configured to perform the predetermined threshold value. Is switched to a second threshold value smaller than that, and the engagement force of the friction engagement element is weakened on condition that the drive force input to the automatic transmission from the drive source of the vehicle is less than the second threshold value. The control device for an automatic transmission according to claim 2, wherein control is performed.

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