JP3577950B2 - Automatic transmission shift control device and automatic transmission kickdown estimation method - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a shift control device for an automatic transmission and a kickdown estimating method for the automatic transmission.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, as a vehicle automatic transmission, a mechanical automatic transmission that performs automatic transmission using a gear mechanism similar to a manual transmission has been put to practical use. Such a mechanical automatic transmission is provided with a clutch actuator for automatically connecting and disconnecting a clutch, and a gear shift actuator for changing a meshing state (ie, a gear position) of the gears. By controlling the state, automatic shifting is performed.
[0003]
These actuators operate using a fluid pressure such as an air pressure or a hydraulic pressure as a drive source, and are configured to control the operation by changing a supply state of the fluid pressure.
Further, such a mechanical automatic transmission also has a manual shift mode in which a desired gear can be switched by a driver's operation in addition to an automatic shift mode in which a normal automatic shift is performed.
[0004]
By the way, in the above-mentioned mechanical automatic transmission, regardless of the manual shift mode or the automatic shift mode, when a shift operation is performed during acceleration (or during deceleration), engine torque (hereinafter, the same as engine output) is obtained. Is reduced, the clutch actuator is operated to disengage the clutch, and then switching to the target shift speed is performed. Then, after switching to the target shift speed, the clutch is connected to restore the engine torque.
[0005]
As described above, the reason why the engine torque is temporarily reduced before switching to the target gear is that if a large torque is applied to the gear mechanism of the transmission at the time of switching to the target gear, the current meshing is performed. This is because it is difficult to disengage the gear, and the gear is easily disengaged by reducing the engine torque before switching to the target shift speed.
[0006]
[Problems to be solved by the invention]
However, such a conventional technique has the following problems.
For example, when the accelerator pedal is suddenly depressed during traveling in the automatic transmission mode to shift from a steady traveling state to a full-open acceleration state (i.e., when kickdown is performed), first, the engine is operated in accordance with a change in the accelerator opening degree. When the torque increases and a shift-down instruction is output based on the shift map, the engine torque decreases, the clutch is disengaged, and the shift-down is executed.
[0007]
That is, the ECU (electronic governor ECU) provided on the engine side performs an increase control of the fuel injection amount in order to increase the engine speed when the accelerator pedal is depressed and the accelerator opening is increased. Rises. On the other hand, the ECU of the automatic transmission sets the target shift speed from the shift map based on the accelerator opening information and the vehicle speed information, so that the accelerator pedal opening sharply increases, thereby causing the shift map to shift down. If you cross the line, you will be instructed to shift down (kick down). Then, when such a downshift instruction is output, the fuel injection amount is reduced in order to facilitate gear removal, and the engine torque is reduced.
[0008]
As a result, at the time of kick down, the engine torque temporarily increases and then starts to decrease, and then shift down is performed. Therefore, there is a problem that the shift time becomes longer and drivability is not good.
Japanese Patent Publication No. 4-71730 discloses a technique related to a transmission having a gear type manual transmission and an automatic clutch. In this technique, when a shift operation is detected during acceleration, the engine speed is temporarily reduced to reduce the engine output. However, the timing for determining whether to reduce the engine output is based on a shift instruction by the shift operation. Therefore, even if this technique is applied to the above-described mechanical automatic transmission, kick down is not executed until a shift is instructed beyond the downshift line of the shift map, and the shift time cannot be reduced.
[0009]
In order to solve such a problem, if a kickdown can be predicted in advance before crossing the downshift line of the shift map, the shift time can be reduced.
SUMMARY OF THE INVENTION The present invention has been made in view of such a problem, and provides a shift control device for an automatic transmission that shortens a shift time at the time of kick down to improve drivability. It is an object of the present invention to provide a method of estimating kickdown of an automatic transmission, which is capable of predicting kickdown of a transmission.
[0010]
[Means for Solving the Problems]
In the shift control device for an automatic transmission according to the first aspect of the present invention, the target shift speed is set by the shift speed setting means in accordance with the driving state of the vehicle based on a preset shift map. When the target gear position is set by the gear position setting means, the engine output is suppressed by the output suppressing means, and the engine output decreases. Then, the shift control means shifts to the target shift speed.
[0011]
On the other hand, based on the information from the accelerator opening detecting means, the shift down determining means changes the accelerator opening. (increase) If it is determined that the amount is larger than the predetermined value, the shift-down determination means By step setting means Execution of downshifting is instructed to the output control unit and the shift control unit prior to the shift control. Therefore, in such a case, the downshift is executed more quickly than the normal downshift.
[0012]
Also , Out By the force suppressing means, the engine output is suppressed at a larger reduction rate during downshifting by the downshift determining means than during downshifting by the shift speed setting means. Therefore, at the time of downshift by the downshift determination means, the output of the engine is quickly suppressed, and the shift time can be reduced.
[0014]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, a shift control device for an automatic transmission according to an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a schematic block diagram showing a main part configuration, and FIG. 2 is a diagram for explaining the operation. (A) is a time chart showing characteristics of a rack designated position, (b) is a time chart showing changes in accelerator opening, FIG. 3 is a diagram showing an example of a shift map, and FIG. FIG. 5 is a flowchart for explaining the operation, and is a flowchart for mainly explaining a kickdown estimating method of the automatic transmission.
[0015]
Now, as shown in FIG. 1, in a vehicle to which the present invention is applied, an automatic transmission 10 capable of automatically changing the gear position according to the driving state of the vehicle, and controlling the operation of the automatic transmission 10 A control device (AT ECU or AT controller) 100 for controlling the automatic transmission 10 is provided in the AT controller 100. The AT controller 100 outputs an operation control signal to the automatic transmission 10 and a target based on the shift map 60a. A shift speed setting means 60 for setting a shift speed is provided.
[0016]
The automatic transmission 10 is a mechanical automatic transmission that performs automatic transmission using the same gear mechanism as a manual transmission, as described in the related art, and automatically connects and disconnects a clutch. A clutch actuator (not shown) and a gear shift actuator (not shown) for changing the meshing state (i.e., gear position) of the gears are provided, and the automatic shifting is performed by controlling the operating states of these actuators. It is supposed to be.
[0017]
Further, the gear shift actuator is provided with a plurality of solenoid valves for controlling a supply state of a fluid pressure serving as a drive source of the actuator. A gear shift unit (GSU) 20 that switches between the two is configured. The operation of the GSU 20 is controlled based on a control signal from the shift control means 30.
[0018]
On the other hand, as shown in FIG. 1, the vehicle is provided with a vehicle speed sensor 40 for detecting a vehicle speed and an accelerator opening sensor (accelerator opening detecting means) 50 for detecting an accelerator opening. The target shift speed is set by the shift map 60a using the detected vehicle speed information and the accelerator opening information detected by the accelerator opening sensor 50 as parameters.
[0019]
When the target shift speed is set by the shift map 60a, the target shift speed information is output from the shift speed setting means 60 to the shift control means 30 and an output suppressing means 70 described later, and the gear of the automatic transmission 10 is changed. The control signal is output from the shift control means 30 so that the GSU 20 switches the gear so that the target gear is set to the target gear.
[0020]
Further, at the time of such gear switching, similarly to the related art, the engine torque (or engine output) is reduced, then the clutch actuator is operated to disconnect the clutch, and thereafter, switching to the target shift speed is performed. After switching to the target shift speed, the clutch is connected and the engine torque is restored.
[0021]
That is, an engine (here, a diesel engine) not shown is provided with an ECU (electronic governor ECU) 90 for controlling the rack position of the electronic governor, separately from the above-described AT ECU (AT controller) 100. The fuel injection amount is controlled by the electronic governor ECU 90.
As shown in FIG. 1, the electronic governor ECU 90 is provided with an output suppressing means 70 for reducing the engine output at the time of gear shifting control based on information from the gear setting means 60. When the operating state obtained from the above crosses the shift characteristic line of the shift map 60a, the shift operation is executed after the engine torque is suppressed by the output suppressing means 70.
[0022]
Next, the main part of the present invention will be described. The AT controller 100 is provided with a shift-down determining means 80 for predicting a kick-down of the transmission 10 in advance. The shift-down determining means 80 predicts whether a kick-down will be performed by a method described later, and if it predicts that a kick-down will be performed, the shift-down determining means 80 gives priority to the output from the gear position setting means 60. It instructs the control means 30 and the output suppression means 70 to execute downshifting.
[0023]
That is, when a kick-down is predicted by the shift-down determining means 80, the shift-down is started before a shift-down (kick-down) instruction based on information from the shift map 60a. By estimating the kickdown in advance, the shift control time is shortened.
[0024]
Here, a method for estimating kickdown in the present embodiment will be described with reference to FIG.
First, a general kick-down will be described. It is assumed that the driver suddenly depresses the accelerator pedal during the steady running at the point A shown in FIG. 3 and the driving state reaches the position shown at the point C. At this time, first, when the driver depresses the accelerator pedal from point A, only the accelerator opening sharply increases before the vehicle speed increases according to the depression amount of the accelerator pedal.
[0025]
However, even if the driving state is at the position of point B in the drawing, a new target gear (sixth gear) is not set until the vehicle crosses the downshift line from the 7th gear to the 6th gear. No shift down shift instruction is issued to the output suppressing means 70. Only when the shift down line is crossed, the target shift speed is set to the sixth speed, and a shift instruction is output to the shift control means 30 and the output suppressing means 70.
[0026]
On the other hand, in the kick-down estimating method of the present embodiment, first, the accelerator opening information is taken into the shift-down determining means 80 from the accelerator opening sensor 50. Then, the shift-down determining means 80 calculates the accelerator opening change rate Δθ from the detected accelerator opening information, and determines whether the accelerator opening change rate Δθ is larger than a predetermined value (threshold). The accelerator opening change rate Δθ is calculated by subtracting the accelerator opening detected in the previous control cycle from the accelerator opening detected in the current control cycle. Further, if the control cycle is fixed, it can be said that Δθ is the rate of change of the accelerator opening per unit time.
[0027]
The following method will be described as one of the kickdown estimation methods. As shown in FIG. 3, the normal shift map 60a is set so that the kick-down is performed when the accelerator opening is equal to or more than a certain value (for example, 70%). For this reason, in a certain control cycle, the accelerator opening is, for example, θ ₁ (30%), and in the next control cycle, θ ₂ (60%) is detected, the accelerator opening change rate Δθ = θ ₂ −θ ₁ And the current accelerator opening θ ₂ From the formula, Δθ + θ ₂ When ≧ accelerator opening 70%, it is estimated that kickdown is performed in the next control cycle.
[0028]
In addition, kickdown may be estimated by the following method. That is, when it is determined that the accelerator opening change rate Δθ is larger than a predetermined value (for example, 30%) (that is, when the accelerator pedal is suddenly depressed and moves from point A to point B in the drawing), for example. Is the current accelerator opening θ ₂ Is located on the shift map. At this time, the accelerator opening θ ₂ Is, for example, 60% or more (point B in the figure), it is determined that the accelerator opening (for example, point C in the figure) exceeds the downshift line in the next control cycle. That is, the accelerator opening change rate Δθ and the current accelerator opening θ ₂ Based on the above, it is determined on the shift map whether the vehicle crosses the downshift line in the next control cycle.
[0029]
That is, in both methods, although there is a difference depending on the presence or absence of reference to the shift map, it is predicted from the accelerator opening and the accelerator opening change rate whether or not a kick down is reliably performed over the downshift line in the future. It is like that.
When the kick-down is predicted in this manner, the shift-down determining means 80 gives priority to the shift control based on the shift map 60a of the gear position setting means 60 and shifts to the shift control means 30 and the output suppressing means 70. An instruction is given to execute downshifting, whereby downshifting (kickdown) is executed more quickly than usual.
[0030]
As described above, the output suppressing means 70 can start the engine output reduction at an early stage while suppressing the engine output increase due to the depression of the accelerator pedal as much as possible based on the downshift instruction at an early stage, and reduce the engine output reduction time as compared with the normal case. it can.
Further, the output suppressing means 70 causes the engine output reduction rate at the time of downshifting by the shift instruction from the downshift determination means 80 to be larger than the engine output reduction rate at the time of downshifting based on the shift map 60a. Is set to
[0031]
That is, when a kick-down is estimated by the shift-down determining means 80, the engine output is reduced more rapidly than during a normal shift-down, so that the shift control time is shortened.
In the present embodiment, since a diesel engine is used as the engine, the output suppressing means 70 suppresses the engine output by decreasing the rack indication position of the fuel injection pump attached to the engine. However, when the present invention is applied to a gasoline engine, the output suppressing means 70 may be configured to reduce, for example, the throttle opening.
[0032]
Since the shift control device for an automatic transmission according to one embodiment of the present invention is configured as described above, the kick control is performed with characteristics shown in time charts as shown in FIGS. 2 (a) and 2 (b). Down is performed. FIG. 2A shows a change in the rack designated position, and FIG. 2B shows a change in the accelerator opening. Further, in FIG. 2A, the solid line shows the characteristics when the present invention is applied, and the broken line shows the characteristics according to the conventional technology.
[0033]
Now, as shown in FIG. ₁ Up to t ₁ To t ₂ It is assumed that the accelerator pedal is suddenly depressed toward. Note that time t ₂ Is an accelerator opening exceeding the downshift line on the shift map, for example, the accelerator opening corresponding to the point C shown in FIG. Also, the time t ₁ From time t ₂ The time until is actually very small.
[0034]
When the accelerator pedal is depressed in this way, as indicated by the solid line in FIG. 2A, the rack position increases according to the change in the accelerator opening, and the fuel injection amount increases. This is the same in the conventional technology. Then, t = t ₂ Before the shift, the shift-down determining means 80 estimates whether or not a kick-down is performed, that is, whether or not a kick-down is exceeded on the shift map 60. At this time, the shift down determination means 80 estimates execution of kick down with reference to the accelerator opening change rate Δθ and the current accelerator opening. Note that the accelerator opening change rate Δθ corresponds to the angle α in FIG. 2B, and it can be said that the greater the angle α, the larger the accelerator opening change.
[0035]
When the execution of the kick down is predicted by the shift down determination means 80, a downshift instruction (t = t) based on the shift map 60a is performed. ₂ A downshift (kickdown) instruction is output from the downshift determination means 80 before. As a result, in the output suppressing means 70, a control signal is output to reduce the rack pointing position. ₂ Engine output from the rack indicated position r ₁ , The engine output can be reduced, and the suppression of the engine output is started early.
[0036]
Furthermore, since the suppression of the engine output is started earlier than before, the small rack indication position r ₁ The engine output can be reduced from the ₁ To r ₂ Not only the rise time until ₂ To r ₁ The time to decrease can be shortened.
At this time, the output suppressing means 70 reduces the engine output at a larger reduction rate than at the time of downshifting based on the shift map 60a. That is, when the kick-down is estimated by the shift-down determining means 80, the engine output decrease rate at the time of the normal shift-down (or the conventional kick-down) [the angle β in FIG. ₂ (See angle β in FIG. 2A). ₁ See] to reduce the engine output.
[0037]
Therefore, due to the synergistic effect of shortening the time obtained by predicting the kickdown in advance and reducing the engine output more rapidly than usual, control for suppressing the engine output at the time of the kickdown is promptly executed. It is done.
And time t ₃ To t ₄ , A clutch actuator and a gear shift actuator (not shown) are operated to perform gear switching, and after the gear switching is completed, time t ₄ To t ₅ , The rack instruction position is changed to a position corresponding to the accelerator opening, the engine output is restored, and the shift control is completed.
[0038]
Note that t ₃ ~ T ₄ Time required between and t ₄ ~ T ₅ The required time between the two is the required time (t ₃ '~ T ₄ 'And t ₄ '~ T ₅ ').
Then, by performing the shift control as described above, the accelerator pedal is depressed (t = t ₁ ) To the completion of kickdown (t = t ₅ ) Is ΔT (= t) longer than the conventional shift control time T ′. ₅ '-T ₅ Or t ₃ '-T ₃ ), Which greatly improves drivability.
[0039]
Next, the operation of the present apparatus will be described with reference to the flowchart shown in FIG. 0 In, it is determined whether the shift mode of the automatic transmission is the automatic shift mode or the manual shift mode. This is because the transmission applied in the present embodiment is a mechanical automatic transmission having an automatic transmission mode and a manual transmission mode, and in the case of an automatic transmission not having the manual transmission mode, The processing in step S10 is omitted. If it is determined in step S10 that the automatic shift mode is set, the process proceeds to step S20, and otherwise returns.
[0040]
In step S20, it is estimated based on accelerator opening information and the like obtained by accelerator opening sensor 50 whether or not kick down is performed. Thereafter, if a kickdown is predicted based on the estimation result of step S20, the process proceeds from step S30 to step S35, otherwise, the process proceeds to step S40.
When the process proceeds from step S30 to step S40, normal shift control is executed. That is, in step S40, it is determined whether or not to perform a gear shift based on information from the gear position setting means 60, and when the target gear position is set by the gear position setting means 60, the process proceeds to step S50 or lower to perform the gear shift. . If the target gear is not set by the gear setting means 60, the routine returns.
[0041]
In step S50, it is determined whether the shift is a downshift or an upshift. When performing a downshift, the process proceeds to step S60 and below, and when performing an upshift, the process proceeds to step S120 and thereafter.
Then, in steps S60 and S120, engine torque suppression control during normal gear shifting is executed. Thereafter, the process proceeds to steps S70 and S130, and the clutch is disengaged. In steps S80 and S140, the rotational speeds of the engine and the clutch are adjusted. This is to suppress torque fluctuations at the time of clutch engagement after shifting.
[0042]
Further, after the rotational speed is adjusted in steps S80 and S140, the process proceeds to steps S90 and S150, where a downshift and an upshift are performed, respectively. That is, in steps S90 and S150, the actual meshing state of the gears is switched. Then, the clutch is engaged in steps S100 and S160, and the engine torque is restored in steps S110 and S170, and the process returns.
[0043]
On the other hand, when the process proceeds from step S30 to step S35, the engine torque is suppressed regardless of the information from the shift map 60a, and kick down control is started. Here, in this step S35, the engine torque is suppressed at a reduction rate larger than the reduction rate of the engine torque in step S60, and the engine torque is promptly suppressed. Then, the process proceeds to step S70 and thereafter, where the clutch connection / disconnection control and the gear switching control are executed.
[0044]
Therefore, if a kick down is predicted in advance, the engine torque suppression control can be started earlier than at the time of the normal downshift, and the reduction rate of the engine torque at this time is reduced to the normal downshift. Therefore, the engine torque suppression control ends immediately.
Next, a method for estimating kickdown of the automatic transmission will be described with reference to the flowchart of FIG. This kickdown estimating method specifically describes the estimation of kickdown in step S20 of FIG. 4, and the flowchart shown in FIG. 5 is a subroutine of step S20 in FIG.
[0045]
First, in step A10, accelerator opening information is fetched from the accelerator opening sensor 50. Next, in step A20, the accelerator opening change rate Δθ is calculated from the present accelerator opening and the previous accelerator opening.
Next, proceeding to step A30, it is determined whether or not the accelerator opening change rate Δθ calculated in step A20 is larger than a predetermined value (for example, 30%). The case where Δθ is larger than the predetermined value is a case where the accelerator pedal is suddenly depressed. If it is determined that Δθ is larger than the predetermined value, the process proceeds to step A40, and it is determined whether the current accelerator opening degree + Δθ is larger than a threshold value (for example, 70%).
[0046]
If the current accelerator pedal opening degree + Δθ is larger than the threshold value, the process proceeds to step A50, and it is predicted that kick down will be performed. That is, if the accelerator pedal opening degree + Δθ is larger than the threshold value and the accelerator opening degree change rate Δθ is larger than a predetermined value, it is estimated that the downshift line is surely crossed and a downshift instruction is output by the shift speed setting means 60. You do it.
[0047]
As a kick-down estimating method other than the above, if YES in step A40, the accelerator opening change rate Δθ + the current accelerator opening is calculated, and it is determined whether or not the shift-down line of the shift map 60a is exceeded. It may be. In this case, the difference is that if it is determined that the vehicle crosses the downshift line, the process proceeds to step A50, and if it is not, the process returns.
[0048]
Thus, by estimating the kickdown, the shiftdown control can be started prior to the instruction from the shift map 60a, which greatly contributes to shortening the shift time.
As described above in detail, according to the shift control device for an automatic transmission of the present invention, the shift-down determination means 80 determines whether the change in the accelerator opening is (increase) If it is determined that the amount is larger than the predetermined value, the downshift determining unit 80 instructs the output suppressing unit 70 and the shift control unit 30 to perform downshifting, prior to the shift control based on the shift map 60a. Therefore, there is an advantage that downshifting (kickdown) is executed more quickly than normal downshifting, and the shift control time is shortened. Further, there is an advantage that drivability is improved by shortening the shift control time at the time of kick down.
[0049]
In addition, since the engine output is suppressed at a larger reduction rate during downshifting by the downshift determining unit 80 than during downshifting by the shift speed setting unit 60, when the downshift determining unit 80 determines that kickdown is performed. Thus, the output of the engine is quickly suppressed, and the shift control time at the time of kick down is also reduced.
Further, the shift-down determination means 80 estimates the kickdown by referring to the current accelerator opening when the rate of change of the accelerator opening is greater than a predetermined value based on information from the accelerator opening sensor 50. There is an advantage that whether or not kick down is performed can be easily and reliably estimated in advance. Further, since no special sensors are required, there is an advantage that the cost does not increase.
[0050]
In addition, since kickdown is started by suppressing engine output rise as much as possible, occurrence of torsional vibration due to large engine output can be prevented beforehand, and driver's feeling can be improved.
Note that the present embodiment is not limited to the above-described embodiment, and various modifications can be made without departing from the spirit of the present invention. For example, in the present embodiment, the case where the present invention is applied to a diesel engine has been described, but the present invention may be applied to a gasoline engine. In this case, the output suppressing means may function as a means for suppressing, for example, the intake air amount of the engine.
[0051]
【The invention's effect】
As described above in detail, according to the shift control device for an automatic transmission according to the first aspect of the present invention, the change in the accelerator opening degree is determined by the downshift determination means. (increase) If it is determined that the amount is larger than the predetermined value, the shift-down determination means By step setting means Since the execution of the downshift is instructed to the output suppressing unit and the shift control unit prior to the shift control, the downshift (kickdown) is executed more quickly than the normal downshift, and the shift control time is shortened. There is. Further, there is an advantage that drivability is greatly improved by shortening the shift control time at the time of kick down.
[0052]
Also , Strange The engine output is suppressed at a larger reduction rate during downshifting by the downshift determining unit than during downshifting by the speed setting unit. Therefore, when kickdown is determined by the downshift determining unit, the engine output is quickly reduced. Is suppressed, the shift control time at the time of kick down can be shortened.
[Brief description of the drawings]
FIG. 1 is a schematic block diagram showing a main configuration of a shift control device for an automatic transmission according to an embodiment of the present invention.
FIGS. 2A and 2B are diagrams for explaining an operation of the shift control device of the automatic transmission according to the embodiment of the present invention, wherein FIG. 2A is a time chart showing characteristics of a rack designated position, and FIG. It is a time chart which shows an opening degree change.
FIG. 3 is a diagram showing an example of a shift map in a shift control device for an automatic transmission as one embodiment of the present invention.
FIG. 4 is a flowchart illustrating an operation of a shift control device for an automatic transmission according to an embodiment of the present invention.
FIG. 5 is a flowchart illustrating an operation of the automatic transmission shift control device as one embodiment of the present invention, and is a flowchart mainly illustrating a kickdown estimation method of the automatic transmission.
[Explanation of symbols]
10 Automatic transmission
30 Shift control means
40 Vehicle speed sensor
50 Accelerator opening sensor (accelerator opening detecting means)
60 speed setting means
60a shift map
70 Output suppression means
80 Downshift determination means
100 Shift control device

Claims (1)

In a shift control device of an automatic transmission, which can automatically change a shift speed according to a driving state of a vehicle,
Speed-gear setting means for setting a target gear in accordance with the driving state of the vehicle based on a previously set shift map;
Output suppressing means for reducing the engine output based on the output from the gear position setting means,
Shift control means for shifting to the target shift speed after the engine output suppression control is started based on the output from the shift speed setting means,
Accelerator opening detecting means for detecting the accelerator opening of the vehicle,
When it is determined based on information from the accelerator opening detecting means that the increase amount of the accelerator opening is larger than a predetermined value, the output suppressing means and the output suppressing means have priority over the shift control by the gear position setting means. Shift down determining means for instructing the shift control means to perform a shift down, and
The output suppressing means includes:
The reduction rate of the engine output at the time of downshifting by the downshift determination means is set to be larger than the reduction rate of the engine output at the time of downshifting by the shift speed setting means. Transmission control device for an automatic transmission.

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