JPH10250415A - Speed change control device for automatic transmission - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent generation of a free running feeling and a speed change shock, in the case of a downshift speed change at power off time. SOLUTION: In the case that as in a manual shift down, in a power off condition, a downshift speed change is performed, in the case of an input rotational speed NT lower than a second target value NTR, a release side oil pressure PA is feedback controlled so that the input rotational speed NT comes to be the second target value NTR. In the case of the input rotational speed NT higher than the second target value NTR, engine torque TC is feedback controlled so that the input rotational speed becomes a first target value NTS. Here, the engine torque is always controlled in a range of non-drive condition, in the case of exceeding this range, feedback control is performed so as to be assisted by the release side oil pressure PA.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a shift control device for an automatic transmission mounted on a motor vehicle, and more particularly, to a disengagement-side friction clutch in a so-called power-off state in which power is not transmitted from an engine in a wheel direction. The present invention relates to a shift control device for down-shifting by re-engaging the engagement element and the engagement-side friction engagement element, so-called clutch-to-clutch shift.

[0002]

2. Description of the Related Art In general, a downshift by clutch-to-clutch in a power-off state is performed by operating a manual lever from, for example, a D range to an S or L range, and is used when engine braking is required. .

Conventionally, as shown in FIG. 1, in a state of releasing the accelerator pedal (power off), the release (fast) side frictional engagement element is released by reducing the release (fast) side hydraulic P _A Since the transmission relationship between the engine and the wheels is cut off, the input rotation speed _NT decreases due to the power-off state. From this state, after the engagement (low speed) side hydraulic P _B is servo activation (actuated immediately before the torque capacity stuffed with clearance clutch occurs) rises towards the engagement pressure, the engagement side frictional engagement By increasing the torque capacity of the element, the input rotational speed _NT is increased to synchronize with the low speed stage. At this time, as described above, until the disengagement side frictional engagement element is released and the engagement side frictional engagement element starts to be engaged, the engine becomes neutral and the engine brake does not operate, and the driver performs a manual down. Despite demanding engine braking, I feel a sense of idling.

Further, as described above, reduced input rotational speed N _T is once in the neutral state, the input rotational speed N _T is the low speed stage by engaging the start of the engagement side frictional engagement element from the state in which the reduced Since the gear ratio rises toward the gear ratio, it takes time to shift the gear, and the engine braking force temporarily increases to cause a shift shock.

Regarding the downshifting in the power-off state, the one disclosed in Japanese Patent Application Laid-Open No. Hei 5-310262 (the former) and the one disclosed in Japanese Patent Application Laid-Open No. 5-229368 (the latter) have been proposed.

[0006] When the former detects that the input (turbine) rotational speed has decreased by a predetermined amount from the rotational speed before the shift, feedback control of the release-side hydraulic pressure is performed to suppress a decrease in the input rotational speed, and thus the downshift is performed. The aim is to prevent the feeling of idle running.

[0007] In the power-off downshift, the disengagement (high-speed) frictional engagement element starts slipping after the engagement (low-speed) frictional engagement element is completely engaged. The engine is controlled so that the engine blows up, thereby reducing shift shock and downshifting time during downshifting.

[0008]

However, in the former, since the reduction of the input speed is suppressed only by the feedback control of the release hydraulic pressure, the release-side frictional engagement element has a considerable amount corresponding to the above-described reduction. It is necessary to maintain the torque capacity, and it is extremely difficult to re-engage with the engagement-side frictional engagement element. Depending on the timing, there is a possibility that the input rotation speed may drop or tie-up to cause a shift shock. In addition, there is a possibility that the durability of the friction material of the disengagement side frictional engagement element is further reduced.

In the latter case, regardless of the power-off state, the input rotational speed _NT is high as shown by the dashed line in FIG. It gives a feeling.

Accordingly, an object of the present invention is to provide a shift control device for an automatic transmission which solves the above-mentioned problem by controlling both the release hydraulic pressure and the engine torque.

[0011]

According to a first aspect of the present invention, there is provided a motor vehicle, comprising: an input shaft which is inputted from an engine output shaft, and the input rotation is shifted by switching a transmission path by connecting and disconnecting a plurality of friction engagement elements; An automatic transmission mechanism for outputting the speed-changed rotation to the wheels; and a hydraulic servo (9, 10) for disconnecting and connecting the friction engagement elements, and does not transmit power from the engine output shaft to the wheels. In an automatic transmission, in the power-off state, one of the friction engagement elements is disengaged and the other is engaged to perform a downshift, and the input rotation speed is detected to detect the input rotation speed. Means (5) and a pressure adjusting means (SLU or SL) for adjusting a hydraulic pressure (P _A ) communicating with the hydraulic servo (or 10) for the disengagement side frictional engagement element.
S), an engine operating means (8) for operating an engine torque, and an input rotation speed before the downshift is set to a first value.
The target value (N _TS) and then, the input rotational speed detecting means (5)
An engine control means (1b) for controlling the engine operating means (8) such that an actual input rotation speed ( _NT ) based on the first target value (N _T ) is maintained at the first target value;
_TS ), the input rotation speed lower than the second target value (N _TR ) by a predetermined amount.
And the pressure adjusting means (SLU or SL) so that the actual input rotational speed ( _NT ) does not become lower than the second target value.
S), and a release hydraulic control means (1a) for controlling S).

According to a second aspect of the present invention, in the release hydraulic pressure control means (1a), the actual input rotation speed (N _T ) based on the input rotation speed detection means (5) is set to the second target value (N _T ). N
_TS ), the release-side hydraulic pressure (P _A ) is controlled so that the actual input rotational speed becomes the second target value, and the engine control means (1b) controls the actual input rotational speed (P _A ). N
_{If T} ) is higher than the second target value (N _TR ), controlling the engine torque (T _C ) such that the actual input speed becomes the first target value (N _TS ). The shift control device for an automatic transmission according to claim 1, wherein:

According to a third aspect of the present invention, in the engine control means (1b), the sum of the control value (T _C ) of the engine torque and the engine torque (T _E ) at the time of the downshift is negative. 3. The shift control device for an automatic transmission according to claim 1, wherein the engine torque is controlled within a range.

According to a fourth aspect of the present invention, the second target value (N _TR ) is determined by setting the release hydraulic pressure by the release hydraulic pressure control means (1a) to the first target value (N _TS ). 4. The shift control device for an automatic transmission according to claim 1, wherein the value is set to a value larger than a rotation change amount of the input rotation speed (N _T ) generated by a minimum control amount (dP _A ). It is in.

[Operation] Based on the above configuration, when the input rotation speed (N _T ) is lower than the second target value (N _TR ) at the time of downshifting in the power-off state, for example, in manual downshifting , Release hydraulic pressure (P
_A ) indicates that the input rotational speed ( _NT ) is equal to the second target value ( _NTR ).
Feedback control is performed so that When the input rotation speed (N _T ) is higher than the second target value (N _TR ), the engine torque (T _C ) is feedback-controlled so that the input rotation speed becomes the first target value (N _TS ). Is done. At this time, the engine torque is controlled within a range that is always in a non-driving state (a state in which power is transmitted from the wheels to the engine). If the engine torque exceeds the range, the release hydraulic pressure (P _A ) assists. Feedback control.

The reference numerals in parentheses are for comparison with the drawings, but do not limit the configuration of the present invention.

[0017]

According to the first aspect of the present invention, it is possible to prevent the gear ratio before the shift from becoming less than the gear ratio by the engine torque and the release-side hydraulic pressure, and to set the release-side hydraulic pressure to be low at this time, so that the transmission can be shifted. In the meantime, the disengagement side frictional engagement element is always slid, and the decrease in the rotation is controlled by the engine torque, so that the driver does not feel idle and the amount of tie-up is reduced. Therefore, the shift shock can be prevented, and the durability of the release-side friction material can be prevented from lowering.

According to the present invention, when the actual input rotation speed is higher than the second target value, the engine torque is controlled by the engine control means so as to become the first target value. Hunting does not occur between the hydraulic control and the engine torque control, as in the case where control is performed so as to be the first target value, and the reliability of the control can be improved.

According to the third aspect of the present invention, since the control range of the engine torque is set so that the shift is always performed in the non-drive state, it is possible to prevent the feeling of idle running due to the drive state during the shift. And a good shift feeling can be obtained.

According to the present invention, when the actual input rotational speed is lower than the second target value, the release-side hydraulic pressure control is performed so that the actual value becomes the second target value. When the difference between the first target value and the second target value is smaller than the rotation change amount that can be caused by the minimum hydraulic control amount, the actual value is equal to or more than the first target value by performing the hydraulic control. In other words, the release side hydraulic pressure becomes too high, and depending on the timing of gripping with the engagement side, a drop in rotation or a shift shock due to tie-up occurs, but the rotation change amount that can be generated with the minimum control amount of hydraulic pressure By setting a larger value between the first target value and the second target value than the first target value, it is possible to prevent the hydraulic control from being larger than the first target value,
It is possible to prevent a drop in rotation or a tie-up due to re-gripping with the engagement side.

[0021]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present automatic transmission has a number of frictional engagement elements such as clutches or brakes, and an automatic transmission in which the transmission path of a planetary gear is selected by appropriately connecting and disconnecting these frictional engagement elements. A mechanism (not shown) is provided, and the input shaft of the automatic transmission mechanism is connected to an engine output shaft via a torque converter, and the output shaft is connected to drive wheels.

FIG. 2 is a block diagram showing electric system control. Reference numeral 1 denotes a control unit (ECU) comprising a microcomputer (microcomputer), an engine rotation sensor 2, and a throttle opening for detecting a driver's accelerator pedal depression amount. A degree sensor 3, a sensor 4 for detecting an actual throttle opening in the engine, a sensor 5 for detecting an input shaft rotation speed (= turbine rotation speed) of a transmission (automatic transmission mechanism),
Signals from a vehicle speed (= automatic transmission output shaft rotation speed) sensor 6 and an oil temperature sensor 7 are input, and an electronic throttle system (engine operation means) 8 for controlling an engine throttle and a linear solenoid of a hydraulic circuit Valve S
Output to LS and SLU. The control unit 1 includes a release hydraulic pressure control unit 1a for transmitting a pressure control signal to the linear solenoid valve SLS or SLU and an engine control unit 1b for transmitting a throttle opening command to the electronic throttle system 8. The means 1b sets a first target value _NTS of the input rotation speed before downshifting (at the time of starting the shift control) as an actual input rotation speed _NT based on the input shaft speed sensor 5 as the first target value. to control the engine torque T _C so as to maintain and release the hydraulic control unit 1a, an input rotational speed a predetermined amount lower than the first target value and the second target value, the actual input speed the controlling the disengagement hydraulic pressure P _a so as not to or less than the second target value.

FIG. 3 is a diagram schematically showing a hydraulic circuit.
A plurality of friction engagement elements having the two linear solenoid valves SLS and SLU and switching a transmission path of a planetary gear unit of an automatic transmission mechanism to achieve, for example, a forward fourth speed or a fifth speed and a reverse first speed. A plurality of hydraulic servos 9 for connecting and disconnecting (clutches and brakes)
It has 0. Further, the linear solenoid valve S
Solenoid modulator pressure is supplied to input ports a ₁ and a ₂ of LS and SLU, and control oil pressures from output ports b ₁ and b _{2 of} these linear solenoid valves are applied to control oil chambers of pressure control valves 11 and 12, respectively. 11a and 12a. The pressure control valves 11 and 12 supply line pressures to the input ports 11b and 12b, respectively, and the pressure regulation from the output ports 11c and 12c regulated by the control hydraulic pressure is applied to the shift valves 13 and 15 respectively. It is supplied to the hydraulic servos 9 and 10 as needed.

This hydraulic circuit is for showing the basic concept, and the hydraulic servos 9 and 10 and the shift valves 13 and 15 are shown symbolically.
A number of hydraulic servos are provided corresponding to the automatic transmission mechanism, and a number of shift valves for switching the hydraulic pressure to these hydraulic servos are also provided. Further, as shown in the hydraulic servo 10, the hydraulic servo has a piston 19 which is fitted to the cylinder 16 in an oil-tight manner by an oil seal 17, and the piston 19 is provided with a pressure control valve 12 acting on a hydraulic chamber 20. The outer friction plate 22 and the inner friction material 23 come into contact with each other based on the pressure-adjusted hydraulic pressure from the first and second springs, and move against the return spring 21. Although the friction plate and the friction material are shown by the clutch, it is needless to say that the friction plate and the friction material also correspond to the brake.

[0025] Then, the described shift control apparatus according to the present invention along the FIG. 4, on the basis of FIG. 5 will be described disengagement hydraulic pressure P _A in the time the downshift by the clutch-to-clutch shift during power-off.

When the accelerator pedal is released (throttle opening θ = 0) and the shift lever is downshifted from the D range to the S or L range during high-speed running, after a predetermined delay time from the shift determination, Timing is started (S1). In the said start time (t = 0), the release-side hydraulic pressure P _A outputs a control signal to the engagement pressure P _W to the linear solenoid valve SLS (or SLU), the release-side friction engagement element is engaged It is in a state of having done. Then, the release torque T _A is calculated by a function of the input torque T _t (S2). The input torque _Tt is obtained by calculating an engine torque based on a throttle opening and an engine speed by a map, further calculating a speed ratio from an input / output speed of a torque converter, and obtaining a torque ratio by a map based on the speed ratio. It is determined by multiplying the engine torque by the above torque ratio. At this time, since the throttle opening is 0, the input torque T _t is small, and the torque distribution ratio to the input torque or the like is required the release side torque T _A is involved, the disengagement side torque T _A Is small.

Furthermore, the target pressure P _TA of the release-side based on the release side torque T _A is calculated (S3). That is, the effective radius of the disengagement side frictional engagement element × the piston area × the number of sheets × the friction coefficient is A, and the disengagement side piston stroke pressure (return spring pressure)
Is B, the release side hydraulic pressure P _A is [P _A = (T _A /
A) + B]. And, the release side hydraulic pressure P _A
At the same time as the start of the shift control, the pressure suddenly drops to the target oil pressure _PTA consisting of a low pressure.

Next, feedback control is immediately performed (S4). The feedback control will be described later together with the feedback control of the engine torque based on FIG. In the feedback control, a predetermined time t _SE for performing piston stroke control of the engagement side hydraulic pressure (control of moving the piston until just before the friction material comes into contact and has a torque capacity) described later elapses (S5), and continued until the engagement side hydraulic pressure P _B reaches the target oil pressure P _TB which will be described later (S6). When the feedback control is terminated, the said disengagement hydraulic pressure P _A is swept down at a predetermined gradient δP _FA (S7), the sweep-down is continued until the hydraulic pressure is drained (S8), the disengagement hydraulic pressure Is terminated.

On the other hand, as shown in the flow chart of FIG. 6, the engagement side oil pressure P _B starts to be measured at the same time as the shift control is started (S1), and at the same time, is set to a predetermined pressure P _S1. outputs a signal to the linear solenoid valve SLS (or SLU) (S11), is the predetermined time t _SA held in said predetermined pressure P _S1 (S12). The predetermined pressure P _S1 is a pressure required to fill the hydraulic chamber 20 of the hydraulic servo and move the piston 19 so that the friction members 22 and 23 come into contact with each other.
When the predetermined time t _SA has elapsed, the engagement side hydraulic pressure P _B sweeps down at a predetermined gradient [(P _S1 −P _S2 ) / t _SB ] (S13), and the engagement side hydraulic pressure P _B is reduced to the predetermined low pressure P _S2. Is reached (S14), the sweep-down is stopped and the predetermined low pressure P _S2 is maintained (S15). The predetermined low pressure P _S2 is and a on the piston stroke pressure or is set to pressure which does not cause the rotation change of the input shaft, the predetermined low pressure P _S2 is clocked t
Is maintained until a predetermined time t _{SE has} elapsed (piston stroke control) (S16). Then, the release-side torque share T _B is calculated by a function based on the input torque T _t and the disengagement side pressure P _A (S17). Furthermore, on the basis of the disengagement side torque share T _B, engagement hydraulic pressure P _TB immediately before the rotation change of the input rotational speed N _T begins (just before the start of the inertia phase) is calculated (S18). Then, based on the engagement hydraulic pressure P _TB , a predetermined gradient is calculated for a predetermined time t _TB set in advance [(P _TB −PS ₂ ) / t _TB ], and the engagement side hydraulic pressure is swept up based on the gradient. (S19). As a result of the sweep-up, the engagement torque increases, and the oil pressure rises to the state immediately before the change in the input rotation speed starts, that is, the calculated predetermined target engagement oil pressure _PTB (S20).

The sweep-up is predicted to reach the target engagement oil pressure P _TB , that is, to enter an inertia phase at which the rotation change of the input shaft rotation speed starts, and to change the rotation ΔN until the completion of the downshift. Α ₁ [%], for example, 7
It is continued until 0 [%] (S21). That is, the input shaft speed during the shift start to N _TS, the rotational variation amount of .DELTA.N, g i _{+ 1} the pre-shift gear ratio, when the g _i and post-shifting gear ratio, [(.DELTA.N ×
100) / N _TS (g _{i + 1} −g _i )] becomes α ₁ [%].

Further, when the rotation change exceeds α ₁ [%], a different oil pressure change δP _LB is set by feedback control based on the smooth input shaft rotation speed change ΔN.
The sweep-up is performed by the gradient of δP _L (S2
2). The δP _LB has a gentler gradient than the increase in the oil pressure to the target engagement oil pressure P _TB , and the sweep-up is caused by α ₂ [%] of the change in the number of revolutions up to near the completion of the shift, for example, 90
[%] Is continued (S23).

When the change in the number of revolutions reaches α ₂ [%], the clock time t _F is set (S24), and this state substantially corresponds to the state in which the inertia phase has ended. Further, a relatively steep oil pressure change δP _FB is set, and the oil pressure rapidly sweeps up due to the oil pressure change (S2).
5) Then, after a predetermined time t _FB, which is set to a time sufficient to increase to the engagement pressure from the clock time t _F , has elapsed (S26), the hydraulic control on the engagement side is completed.

Next, the engine torque control will be described with reference to FIG. Although the engine is in an idling state based on the throttle opening being 0, when the shift control is started (t = 0), the engine is set so that the input rotation speed _NT becomes the first target rotation speed _NTS. the feedback control of the torque T _C (S31). Incidentally, the feedback control is carried out with the feedback control of the disengagement side pressure P _A, described below along with FIG. Then, the feedback control is continued for the piston stroke control time t _{SE of} the engagement side oil pressure P _B described above (S32). After the lapse of the predetermined time t _SE , the engine control torque T _C is swept down at a predetermined gradient δT _C until the torque becomes 0 (S33, S34).

Next, referring to FIG.
And the feedback control shown in S31 will be described. First, the actual input revolution speed N _T based on the input shaft rotation sensor 5, the shift control start input speed at the time of N _TS slightly lower set of the disengagement hydraulic pressure than the (second) target rotational speed N _TR And (S41). Actual input speed N _T
If There lower than the second target engine speed N _TR previously set (N _T ≦ N _TR), are controlled so that the release-side hydraulic pressure P _A is increased (S42). That is, as shown in FIG. 9 (a), the variation dP _A the release side hydraulic pressure increases in proportion to the difference between the input rotational speed N _T and the target engine speed N _TR (N _TR -N _T) ,
Thus input rotational speed N _T is such that the target rotational speed N _TR, release side hydraulic pressure P _A is feedback-controlled. As a result, the disengagement-side friction engagement element is not completely disengaged and is maintained in the slip state, is prevented from shifting to the neutral side, and the engine brake based on the gear ratio g _{i + 1} before shifting is operated.

On the other hand, when the input rotation speed is higher than the second target rotation speed (N _T > N _TR ), the actual input rotation speed N _T
Is the input rotation speed at the start of the shift control (first target rotation speed)
It is compared to N _TS (S43). If the input speed is smaller than the speed at the start of shifting (N _T ≦ N _TS ), the engine torque T _C is controlled to increase (S44).
That is, as shown in FIG. 9 (b), the engine control torque change amount dT _C is feedback controlled so as to be proportional to the difference between the shift start time of rotation speed N _TS as the input rotational speed N _T (N _TS -N _T) Is done. At this time, based on the manual downshift, the original engine torque _TE is in a negative torque state (T _E <0), and the control torque T _C is generally in a positive torque state (T _C).
> 0), it is determined whether the combined engine output torque (T _E + T _C ) is positive or negative, and the control of the engine torque is negative, that is, the non-drive state in which power is transmitted from the wheels to the engine side. Is performed only in the range, and the feeling of idle running due to the driving state during shifting can be prevented. Also, when as the engine output torque is positive, i.e., if the torque from the engine to the wheel side is in a driving state is transferred, further disengagement side pressure P _A is the predetermined change amount dP _A
Is feedback-controlled so as to rise (S4
6). That is, when a non-drive state (engine brake state) is caused only by the engine torque control, the feedback control of the release hydraulic pressure is not further applied. Hydraulic pressure control is assisted.

If it is determined in step S43 that the input rotation speed is larger than the input rotation speed at the start of shifting (N _T >
N _TS ), and the feedback control is performed so that the engine torque T _C becomes lower (S47).

Thus, when the actual input rotational speed _NT is higher than the second target rotational speed _NTR , the engine torque control alone is performed such that the input rotational speed _NT becomes the shift start rotational speed _NTS. Alternatively, feedback control is performed by assisting the release hydraulic pressure control. Therefore, the disengagement side frictional engagement element is set to the slip state, the fall of the input rotation speed is controlled by the engine torque control, and the driver is not given a feeling of idle running. By reducing the tie-up amount of the joint element, it is possible to reduce the shift shock and prevent the durability of the disengagement side frictional engagement element from being lowered.

[Brief description of the drawings]

FIG. 1 is a time chart showing a downshift in power-off according to a conventional technique.

FIG. 2 is an electric block diagram according to the present invention.

FIG. 3 is a diagram schematically showing a hydraulic circuit according to the present invention.

FIG. 4 is a time chart according to the embodiment of the present invention.

FIG. 5 is a flowchart showing hydraulic control on the release side.

FIG. 6 is a flowchart showing hydraulic control on the engagement side.

FIG. 7 is a flowchart showing the engine torque control.

FIG. 8 is a flowchart illustrating feedback control of the release hydraulic pressure and the engine torque.

FIG. 9A is a diagram showing a control amount of a release side hydraulic pressure, and FIG.
FIG. 3 is a diagram showing a control amount of engine torque.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Control part 1a Release hydraulic pressure control means 1b Engine control means 5 Input rotation speed detection means (sensor) 8 Engine operation means (electronic throttle system) 9,10 Hydraulic servo _NT Input rotation speed _NTS First target value (before shifting) input rotational speed) N _TR second target value P _a disengagement hydraulic pressure T _C engine torque (control value)

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Masaharu Chiba 10 Takane, Fujiimachi, Anjo City, Aichi Prefecture Inside Aisin AW Co., Ltd. (72) Inventor Takayuki Kubo 10 Takane Fujiimachi, Anjo City, Aichi Prefecture Aisin・ AW Co., Ltd.

Claims (4)

[Claims] 1. An automatic transmission mechanism that receives an input from an engine output shaft, shifts the input rotation by switching a transmission path by connecting and disconnecting a plurality of friction engagement elements, and outputs the shifted rotation to wheels. And a hydraulic servo that disconnects and connects the friction engagement elements. In a power-off state in which power is not transmitted from the engine output shaft to the wheels, one of the friction engagement elements is released. An automatic transmission, wherein the other one is engaged to perform a downshift, wherein an input rotation speed detecting means for detecting the input rotation speed, and a hydraulic pressure communicating with the hydraulic servo for the disengagement side frictional engagement element. Pressure adjusting means for adjusting pressure, engine operating means for operating an engine torque, an input speed before the downshift is set as a first target value, and an actual input speed based on the input speed detecting means is set to the first target value. One An engine control means for controlling the engine operating means so as to maintain a standard value; an input rotational speed lower than the first target value by a predetermined amount as a second target value; A shift control device for an automatic transmission, comprising: a release hydraulic pressure control unit that controls the pressure adjustment unit so that the pressure does not fall below a target value. 2. The release hydraulic pressure control means, when an actual input rotation speed based on the input rotation speed detection means is lower than the second target value, the actual input rotation speed becomes equal to the second target value. The engine control means controls the actual input rotation speed to be equal to the first target value when the actual input rotation speed is higher than the second target value. The shift control device for an automatic transmission according to claim 1, wherein the engine torque is controlled. 3. The engine control means according to claim 1, wherein the engine control means controls the engine torque in a range where the sum of the control value of the engine torque and the engine torque at the time of the downshift is negative. 3. The shift control device for an automatic transmission according to claim 2. 4. The second target value is set to be larger than the first target value by a rotation change amount of the input rotation speed which is generated by a minimum control amount of the release hydraulic pressure by the release hydraulic pressure control means. The shift control device for an automatic transmission according to claim 1, 2 or 3, wherein