JPH112319A - Control device for automatic transmission - Google Patents

Abstract

PROBLEM TO BE SOLVED: To carry out an up-shift after coast down control in an automatic transmission without deteriorating a shock. SOLUTION: A device comprises a coast down control judging means (step 1), reset detection means (step 2) detecting an output request in a prescribed value or more relating to a power source in a condition judging during coast down control, rotational speed difference detection means (step 3) detecting a difference of preset value or more relating to a synchronous rotational speed after an up-shift according to a prescribed rotational speed of a rotary member of an automatic transmission resetting a down-shift point to a car speed in the case of normal speed change control, and an up-shift permitting means (step 4) permitting an up-shift in the case of detecting the rotational speed of the rotary member different from the value or more relating to the synchronous rotational speed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a control device for executing a so-called coast down control for setting a downshift point to a higher vehicle speed side when an output demand for a power source is reduced.

[0002]

2. Description of the Related Art As is well known, an automatic transmission for a vehicle uses a shift map (shift map) in which an engine load represented by a throttle opening and a vehicle speed are used as parameters. The shift speed to be set is determined based on the vehicle speed, and shift control for achieving the shift speed is executed. The shift diagram is set so that the power performance, efficiency, running feeling, and the like are improved.

In the shift diagram, a shift speed region is determined by an upshift line connecting an upshift point and a downshift line connecting a downshift point, and the upshift line and the downshift line are changed. By doing so, various shift controls can be performed. For example, Japanese Unexamined Patent Publication No.
In the control device of the automatic transmission described in Japanese Patent Publication No. 52, when a braking request at the time of deceleration is detected, such as when a switch for operating the exhaust brake device is turned on, a decrease in throttle opening causes a decrease. By setting the shift line to the high vehicle speed side, the engine brake is easily applied.

The control for setting the downshift point in the coast state on the high vehicle speed side by returning the accelerator pedal or the like may be executed as coast down control in addition to the case where the engine brake is applied. is there. That is, during the running of the vehicle, in the coast state where the output request for the power source such as the engine is zero,
When the vehicle speed is high to some extent, a negative torque state occurs in which torque is input to the automatic transmission from the output shaft side, and thereafter, a positive torque acts as the vehicle speed gradually decreases. On the other hand, in the middle and low speed stages of an automatic transmission, a one-way clutch is often used to set the speed in order to facilitate shifting. , The one-way clutch is released, and the gear transmission mechanism of the automatic transmission is similar to the neutral state.

[0005] Therefore, when downshifting is performed in a middle-low speed coast state, it is preferable to execute the downshift in a state in which the one-way clutch is released, that is, before a positive torque is generated. For this reason, when the coasting state occurs at the middle and low speeds, the downshift point is set to a higher vehicle speed side than usual, and the downshift is encouraged to prevent the occurrence of a shock accompanying the shift.

[0006]

SUMMARY OF THE INVENTION The above-mentioned Japanese Patent Laid-Open Publication No. Hei 2-1
The control described in Japanese Patent No. 34452 and the above-described coast-down control involve control for changing the low-speed side gear position range to a higher vehicle speed side than usual, so that the coast state is determined by depressing an accelerator pedal or the like. If it is out of the range, the shift speed range is returned to the original normal state. In this case, if the vehicle speed has not significantly decreased from the previous state, the running state of the vehicle is in the shift speed region before the downshift, and thus the shift speed region (downshift point).
Is returned to the original state, an upshift determination is made.

In this case, if the output increase request immediately after the coast state is entered, that is, if the accelerator is turned on, the output rotation speed of the automatic transmission becomes a rotation speed substantially equal to the rotation speed immediately before execution of the coast downshift. I have. On the other hand, when the accelerator is turned on, the engine speed, that is, the input speed of the automatic transmission increases at least to the speed immediately before the coast downshift. As a result, the input rotation speed at the time of the accelerator-on is approximated to the synchronous rotation speed after the gear shift when the upshift is performed in response to the termination of the coast-down control. That is, the difference between the input speed and the value obtained by multiplying the speed ratio after the upshift by the output speed becomes small.

[0008] In general, the end of the shift in the automatic transmission is determined based on the fact that the rotational speeds of the rotating elements such as the engine and members connected thereto have reached the synchronous rotational speed after the shift. . Therefore, as described above, if the input rotation speed at the time when the determination of the upshift is established is close to the determined synchronous rotation speed after the upshift, immediately after the determination of the upshift, the end determination of the upshift or The start determination of the end control of the upshift is established. Therefore, the control of the hydraulic pressure during shifting is not performed as expected,
Shift shock may be exacerbated.

This will be described with reference to an automatic transmission disclosed in Japanese Patent Application Laid-Open No. 5-60209. In the automatic transmission described in this publication, an accumulator is connected to a clutch that sets the third forward speed, and when the clutch is engaged to set the third speed, the back pressure of the accumulator is electrically controlled. Is controlled. Specifically, the back pressure of the accumulator during shifting is controlled to be somewhat high in accordance with the progress of shifting, and at the end of shifting, the friction coefficient of the clutch apparently increases. Let it.

Accordingly, the accelerator pedal is returned during traveling in the third speed, the downshift point is set to a higher vehicle speed side by the coast down control, and accordingly, the determination of the downshift from the third speed to the second speed is made. When the condition is satisfied, and then the accelerator pedal is depressed to return the downshift point to the normal shift control state and the coast down control ends, the determination of the upshift from the second speed to the third speed is established. In this case, since the third speed is a so-called direct connection stage and the speed ratio is “1”, there is almost no difference between the input rotation speed and the output rotation speed.
Therefore, immediately after the start of the control of the upshift to the third speed, the end determination of the upshift is established.
In such a case, the back pressure of the accumulator of the third speed clutch is maintained at a high pressure without being controlled to a low pressure because the end determination of the upshift has already been established.

FIG. 8 shows an example of this. When the accelerator pedal is depressed during the coast-down control and the throttle opening θ increases, an upshift from the second speed to the third speed is performed at time t1 immediately thereafter. The judgment is made. Since there is almost no difference between the input rotational speed NC0 and the output rotational speed NO at that time, the end determination of the upshift to the third speed is established. As a result, the duty ratio DSLN of the linear solenoid valve for controlling the back pressure of the accumulator is controlled to zero, and accordingly, the back pressure of the accumulator of the third speed clutch increases, and the engagement pressure of the third speed clutch increases. State controlled. Therefore, the third speed clutch is suddenly engaged, so that the output torque is rapidly increased, and this is felt as a shock.

On the other hand, if the determination of the upshift accompanying the end of the coast-down control is established at the time when the difference between the input speed and the output speed slightly occurs, the control of the upshift to the third speed starts. Immediately thereafter, the shift end control is started, and as a result, the shift shock increases. This is shown in FIG. In other words, if a slight difference in the rotational speed between the input rotational speed NC0 and the output rotational speed NO occurs at the time t11 when the throttle pedal θ starts to increase due to the depression of the accelerator pedal, the upshift is executed. This is the same state as the shift end timing in the case, and as a result, the end shift up control to the third speed is started. As described above, the hydraulic pressure of the clutch for setting the third speed is temporarily reduced at the end of the shift, so in the example shown in FIG.
Immediately after the start of the upshift to the first speed, the duty ratio DSLN of the linear solenoid valve is gradually increased, and the back pressure of the clutch that sets the third speed is reduced. As a result, a so-called end contact occurs in which the hydraulic pressure of the clutch for setting the third speed shifts to a low pressure from the start of the shift and the piston of the accumulator reaches the movement limit before the actual shift ends. At approximately the same time as the end contact, the clutch hydraulic pressure sharply increases, so that the output torque sharply increases, and this is felt as a shock.

The present invention has been made in view of the above circumstances, and has as its object to provide a control device capable of executing an upshift accompanying a return from coast-down control without causing a shock. Things.

[0014]

In order to achieve the above-mentioned object, according to the first aspect of the present invention, a downshift point is set to a normal value by reducing an output demand for a power source to below a predetermined value. The downshift point is set to a higher vehicle speed side than in the case of the shift control to prompt a downshift, and the downshift point is returned to the vehicle speed in the normal shift control by increasing the output request for the power source to the predetermined value or more. A coast down control determining means for determining that control for setting the down shift point to a higher vehicle speed side is being executed, and the coast down control determining means raises the down shift point to a higher vehicle speed. Return detection means for detecting that an output request for the power source has become equal to or greater than the predetermined value in a state where it is determined that the control for setting the vehicle speed is being performed; The rotational speed of the predetermined rotating member of the automatic transmission is different from or greater than a predetermined value with respect to the synchronous rotational speed after the upshift caused by returning the downshift point to the vehicle speed in the case of the normal shift control. Rotation speed difference detecting means for detecting that the rotational speed of the rotating member is different from the synchronous rotation speed by the rotation speed difference or more by the rotation speed difference detecting means. And an upshift permitting means.

Therefore, according to the first aspect of the present invention, when there is a demand for increasing the output of the power source after the start of the so-called coast-down control, the control returns from the coast-down control, and when the upshift is performed accordingly, the rotation speed of the predetermined rotating member is increased. Upshifting is permitted at a point where the synchronous rotation speed after the upshift differs to some extent. Therefore, the end of the upshift is not determined immediately after the start of the upshift, and as a result, the upshift is executed normally and the deterioration of the shock is prevented.

According to a second aspect of the present invention, when the output request for the power source falls below a predetermined value, the downshift point is set to a higher vehicle speed side than in the case of the normal shift control, to promote the downshift, and In a control device for an automatic transmission, the downshift point is returned to a vehicle speed in the case of the normal shift control when an output request for a power source increases to the predetermined value or more, wherein the downshift point is set to a high vehicle speed side. A coast-down control determining means for determining that the control to be executed is being executed, and an upshift point from a lower gear to a higher gear with the downshift point interposed therebetween. In the request area,
Upshift area setting means for setting the vehicle to a higher vehicle speed side than the downshift point set to the higher vehicle speed side is provided.

Therefore, according to the second aspect of the present invention, when there is a request to increase the output of the power source during the so-called coast-down control and the control returns from the coast-down control, the upshift point is set to the entire output request area during the coast-down control. Since the vehicle speed is set higher than the downshift point, the upshift is not immediately determined by the return from the coast down control. And when the vehicle speed increases in response to a request for increasing the output of the power source, the running state changes across the upshift point,
An upshift is performed. Since this is a normal upshift control, the shock does not deteriorate.

[0018]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, the present invention will be specifically described with reference to the drawings. FIG.
FIG. 1 is a diagram showing an overall control system of an example applied to an automatic transmission described in Japanese Patent Application Publication No. 60209, in which an automatic transmission A connected to an engine E as a power source has a lock-up clutch as a transmission mechanism. Converter 20 having a set 20 and a second transmission section 30 having a set of planetary gear mechanisms
And a first transmission section 40 for setting a plurality of forward speeds and reverse speeds by two sets of planetary gear mechanisms.

The second transmission section 30 performs high-low switching between two stages. A carrier 31 of the planetary gear mechanism is connected to the turbine runner 22 of the torque converter 21. A clutch C0 and a one-way clutch F0 are provided in parallel relationship with each other between the sun gear 32 and the sun gear 32.
A brake B0 is provided between the motor and the housing Hu.

The sun gears 41 and 42 of each planetary gear mechanism of the first transmission section 40 are provided on a common sun gear shaft 43. The ring gear 44 in the planetary gear mechanism on the left side (front side) in the drawing of the first transmission portion 40 and the second
A first clutch C1 is provided between the transmission unit 30 and the ring gear 33. A second clutch C2 is provided between the sun gear shaft 43 and the ring gear 33 of the second transmission unit 30. The carrier 45 of the planetary gear mechanism on the left side in the figure and the ring gear 46 of the planetary gear mechanism on the right (rear side) in the first transmission unit 40 are integrally connected, and the output shaft is connected to the carrier 45 and the ring gear 46. 47 are connected.

A first brake B1 as a band brake is provided on the outer peripheral side of the clutch drum of the second clutch C2 so as to stop the rotation of the sun gear shaft 43. A first one-way clutch F1 and a second brake B2 are arranged in series between the sun gear shaft 43 and the housing Hu. Further, a second one-way clutch F2 and a third brake B3 are arranged in parallel between the carrier 48 and the housing Hu in the rear planetary gear mechanism.

A hydraulic circuit 50 is provided for supplying and discharging hydraulic pressure to each of the clutches C0, C1, C2 and each of the brakes B0, B1, B2, B3. This hydraulic circuit 50
Consists of first and second solenoid valves S1 and S2 for executing first to fourth gear shifts, a linear solenoid valve SLN for mainly controlling the back pressure of the accumulator, and mainly lock-up. A linear solenoid valve SLU for controlling the clutch 20 is provided. An electronic control unit (ECU) 51 is provided for controlling ON / OFF of these solenoid valves S1, S2, SLN and SLU. The electronic control unit 51 mainly includes a central processing unit (CPU), a storage unit (RAM, ROM), and an input / output interface, and serves as data for controlling the solenoid valves S1, S2, SLN, and SLU. , A vehicle speed signal, a throttle opening signal (or an accelerator opening signal which is an accelerator pedal depression amount), a shift position signal, a shift pattern select signal, an engine water temperature signal, a brake signal, and the like.

In the automatic transmission A described above, each shift speed is set by engaging each friction engagement device as shown in FIG. In FIG. 5, a mark .largecircle. Indicates ON for the solenoid valve and engagement for the frictional engagement device, and a mark X indicates OFF for the solenoid valve and release for the frictional engagement device.

As shown in FIG. 5, the second clutch C2 is
The engagement is performed when upshifting from the second speed to the third speed, and the engaged state is maintained at the third speed and the fourth speed. An accumulator is connected to the second clutch C2, and by controlling the back pressure thereof, the second clutch C2
Is controlled. FIG. 6 is a partial hydraulic circuit diagram for controlling the hydraulic pressure of the second clutch C2. The first solenoid valve S1 is connected to the control port 61 of the 2-3 shift valve 60. This 2-3 shift valve 60
Is configured such that an input port 62 and an output port 63 communicate with each other when a signal pressure is supplied to the control port 61. The line pressure PL is supplied to the input port 62, and the second clutch C2 is connected to the output port 63.

From the 2-3 shift valve 60 to the second clutch C2
The positive pressure chamber of the accumulator 64 is connected to a branch point in the middle of an oil path that supplies hydraulic pressure to the accumulator 64. The accumulator 64 is the same as a normal one. A spring is arranged on the opposite side of the positive pressure chamber with the piston interposed therebetween, and a hydraulic pressure is supplied to the back pressure chamber to load the opposing hydraulic pressure in the positive pressure chamber. Is configured to be increased.

An accumulator control valve 65 for controlling the back pressure of the accumulator 64 is provided. The accumulator control valve 65 uses the line pressure PL as a source pressure and the throttle pressure Pth
And a valve that outputs a hydraulic pressure adjusted by a signal pressure PSLN of the linear solenoid valve SLN. That is, while the line pressure PL is supplied to the input port 66,
An output port 67 is connected to the foot back port 68 and the back pressure chamber of the accumulator 64. Further, a throttle pressure Pth that increases in accordance with the throttle opening is input to a first signal pressure port 69 opposite to the feedback port 68, and is output from a linear solenoid valve SLN to a second signal pressure port 70. The signal pressure PSLN is input. Note that this linear solenoid valve S
LN is configured such that the modulator pressure PSLM adjusted by a solenoid modulator valve (not shown) is used as a source pressure, and the signal pressure PSLN becomes lower as the duty ratio DSLN increases.

The automatic transmission A is configured to perform coast down control. That is, when the engine load becomes zero by closing the throttle valve during traveling, the downshift point is set to a higher vehicle speed side than the normal control, and control is performed so as to prompt the downshift. This can be performed, for example, by changing the shift diagram or correcting the detected vehicle speed to a low vehicle speed. 7 schematically shows a part of a shift diagram in which the horizontal axis represents the vehicle speed v and the vertical axis represents the throttle opening θ, and point A indicates a normal 3-2 down when the throttle valve is fully closed. Shift point,
Point B is a coast downshift point at which the vehicle speed is increased. The solid line indicates a normal 2-3 upshift line, and the broken line indicates a normal 3-2 downshift line.

Therefore, during the coast down control, the vehicle speed v
When the accelerator pedal is depressed in a state where is slightly lower than the point B, the control returns from the coast down control to the normal shift control, and at the same time, the upshift determination is established.
That is, in FIG. 7, if the throttle opening θ changes from point B to point C by increasing the throttle opening θ, it is determined that the traveling state has changed to the third speed state, and the running state is changed from the second speed to the third speed. An upshift is determined.

In such a case, the control device according to the present invention performs control as described below. FIG. 1 is a flowchart showing an example of the control routine. In step 1, it is determined whether or not the coast down control is being performed. This is determined based on, for example, that the throttle opening θ is zero, that the downshift point is set on the higher vehicle speed side, that the downshift determination is made in accordance with the change of the downshift point, and the like. can do. This step 1 corresponds to the coast down determining means in the present invention.

If a negative determination is made in step 1, the control returns without performing any particular control. If an affirmative determination is made, it is determined whether or not the accelerator pedal is depressed (step 2). This can be determined, for example, by switching the idle switch from on to off. If the accelerator pedal is depressed, the throttle opening θ increases and the engine output increases, so if an affirmative determination is made in step 2, the output increase request has been made. On the other hand, the control for setting the downshift point to the high vehicle speed side is executed when the throttle opening θ is zero, and otherwise, normal shift control is performed. Therefore, if an affirmative determination is made in step 2, the downshift point is returned to the normal state in this way, and step 2 corresponds to the return determination means of the present invention.

If a negative determination is made in step 2, the coast down control is continued, and the routine returns.
On the other hand, if the determination is affirmative, it is determined whether or not the difference between the value obtained by multiplying the output speed N0 by the speed ratio ρ2 after the downshift and the input speed NC0 is equal to or less than a preset reference value α. (Step 3). The reference value α is set to a relatively small value. Therefore, in step 3, the coast downshift is almost completed, and it is determined whether or not the automatic transmission A is in the state of setting the gear position after the downshift. Will be determined.

The purpose of making the determination in step 3 is to prevent the automatic transmission A from executing another shift from an ambiguous state in the middle of the shift, and to erroneously terminate the upshift accompanying the return from the coast down control. This is to avoid judgment. Therefore, when focusing on the latter purpose, it is only necessary that the rotation speed of a predetermined rotation element such as the engine E differs to some extent from the synchronization rotation speed after the upshift. When making such a determination, a difference between a value obtained by multiplying the speed ratio after the upshift by the output rotation speed and the output rotation speed may be compared with a predetermined reference value. In the case of an upshift from the second speed to the third speed after the coast downshift from the third speed to the second speed, the speed ratio of the third speed is “1”. It may be determined whether or not the difference between the input rotation speed and the output rotation speed has become larger than a predetermined reference value. Therefore, this step 3 corresponds to the rotational speed difference detecting means of the present invention.

If a negative determination is made in step 3 above, there is a possibility that an error may occur in the determination of the end of the upshift, or the automatic transmission A may be in an ambiguous state in the middle of a shift. Return without starting any control. That is, without starting the upshift control, a delay is made until the condition of step 3 is satisfied. On the other hand, if an affirmative determination is made in step 3, the coast downshift is almost completed, and the output of the upshift signal is permitted (step 4). Step 4 corresponds to the upshift permission means of the present invention. Thereafter, the coast down control ends (step 5).

FIG. 2 shows a time chart when the above control is executed. When the accelerator pedal is returned, the throttle opening θ becomes zero, and accordingly, coast-down control is started. For example, the accelerator pedal is returned at the time point t21 during traveling in the third speed, and the determination of the second speed downshift is established by the coast down control accompanying the accelerator pedal. Therefore, in order to reduce the hydraulic pressure of the second clutch C2 that sets the third speed, the duty ratio D
SLN is controlled to 100% and back pressure is reduced.

When the accelerator pedal is depressed and the throttle opening θ increases at time t22 during the execution of the coast downshift as described above, the coast state disappears, and the running state becomes 3-2 downshift. By increasing the vehicle speed at the point, the vehicle deviates from the second speed region and enters a third speed region under normal control. This is, for example, a change in the traveling state from point B to point C shown in FIG.
However, since the difference between the input rotation speed NC0 and the output rotation speed N0 at this time is small, upshifting is not permitted.

Thereafter, the input rotation speed NC0 increases due to the increase in the engine output, and the upshift is permitted at time t23 when the difference from the output rotation speed N0 increases. That is, at this point, an upshift from the second speed to the third speed is determined,
It will be executed again. Therefore, the difference between the input rotation speed NC0 and the output rotation speed N0 at the time of starting the upshift control is larger than the rotation speed difference for determining the end of the shift, so that the end of the upshift is erroneously determined. It will not be done.

Therefore, the second clutch C for setting the third speed
2, the back pressure of the accumulator, that is, the duty ratio DSLN of the linear solenoid valve SLN is controlled to be low in accordance with the progress of the shift during the shift, as in the case of the normal upshift from the second speed to the third speed. By judging the shift end time, the duty ratio DSLN is gradually increased, and the engagement pressure of the second clutch C2 is temporarily reduced. That is, at the start of shifting or during shifting, the second
Since the engagement pressure of the clutch C2 does not suddenly increase, deterioration of the shift shock is reliably prevented.

In the control example described above, the upshift is executed after the accelerator pedal is depressed and the input rotation speed NC0 increases to some extent. However, instead of this, the control is performed as follows. Is also good. FIG. 3 is a flowchart for explaining an example of the control.
It is determined whether or not the coast down control is being performed (step 1).
1). If a negative determination is made in step 11, a normal upshift line is set (step 12). Conversely, if a positive determination is made, the upshift line is changed from that of normal shift control. (Step 13).

The upshift line to be changed here is an upshift line between the lower gear position by the coast down control and the next higher gear position. , The upshift line from the second speed to the third speed. The usual upshift line is
This is an upshift line set together with other shift lines based on the power performance of the vehicle and the like, and is shown by a solid line in FIG. 7 described above. On the other hand, the upshift line changed in step 13 is an upshift line set to a higher vehicle speed side than the coast downshift point with respect to all the throttle opening degrees θ (that is, an output increase request), as shown by a chain line in FIG. It is a shift line.

If the upshift line has been changed in step 13, a return determination is made in step 14. This is a control for judging whether or not a condition for returning the upshift line to the state of the normal shift control has been satisfied. For example, in FIG. 7, the running state deviates from a region surrounded by a chain line and a solid line. The return condition is satisfied by this. Therefore, if a positive determination is made in step 14, the changed upshift line is returned to the original normal state, and if a negative determination is made, the process returns. Note that the above step 1
When the control of 2 is performed, the process returns as it is.

Here, step 11 corresponds to the coast down control judging means of claim 2 and step 13
Corresponds to the upshift area setting means of claim 2.

Therefore, if the control shown in FIG. 3 is performed, even if the accelerator pedal is depressed during the coast-down control, the upshift line is increased in speed. It does not change across. If the vehicle speed increases by depressing the accelerator pedal and the running state crosses the upshift line at which the vehicle speed has increased, an upshift is determined at that time. That is, by increasing the speed of the upshift line, the upshift is delayed until the vehicle speed increases. And when the upshift is determined,
Since the input rotation speed is increasing, the end determination of the upshift is not immediately established, and the erroneous determination of the end of the upshift and the deterioration of the shock due to the determination can be prevented.

In the control shown in FIG. 3, the traveling state is changed from a region (a region surrounded by a chain line and a solid line in FIG. 7) in which the upshift line is increased to a higher vehicle speed and changed to a lower speed range region. In the case of deviation, the return control for returning the upshift line to the normal upshift line is performed, so that the upshift determination is not established with the return control. That is, the determination of the upshift is established in accordance with a change in the normal traveling state such as an increase in the vehicle speed or a decrease in the throttle opening,
Further, since the shift is executed, the shift shock does not deteriorate.

In each of the specific examples described above, the coast down control during the third speed and the subsequent upshift from the second speed to the third speed have been described as examples.
The present invention is not limited to the above-described example, and can be applied to the case of coast down control between other shift speeds and control of subsequent up shift. The invention also provides
The present invention can be applied to a control apparatus for an automatic transmission having a gear train or a hydraulic circuit other than the above-described gear train or hydraulic circuit. Further, the present invention can be applied to a control apparatus for an automatic transmission of a vehicle using a motor as a power source or an automatic transmission of a vehicle using a motor and an internal combustion engine as a power source, in addition to the internal combustion engine. Therefore, the output increase request in the present invention is not limited to the depression of the accelerator pedal or the increase of the throttle opening,
In essence, it involves a wide range of general operations for increasing the power source output.

[0045]

As described above, according to the first aspect of the present invention, when the upshift is executed after returning from the coast down control, the input speed is changed to some extent by the operation of increasing the output of the power source. Since the upshift will be executed later, it is possible to avoid erroneously determining the end of the upshift immediately after the execution of the upshift accompanying the so-called return control from the coast-down control. This can prevent the shock from worsening.

According to the second aspect of the present invention, when returning from the coast down control in response to the operation of increasing the output of the power source, the driving state by the operation of increasing the output of the power source is changed to the upshift point where the vehicle speed is increased. Therefore, the vehicle is still in the lower vehicle speed range, and therefore the upshift is not immediately determined by the return control from the coast down control. That is, since the upshift is determined after the vehicle speed has been increased by the operation of increasing the output of the power source, the end of the upshift is not erroneously determined, and naturally the shift shock is reliably prevented from becoming worse.

[Brief description of the drawings]

FIG. 1 is a flowchart for explaining a control example by a control device of the present invention.

FIG. 2 is a time chart when the control shown in FIG. 1 is performed.

FIG. 3 is a flowchart for explaining another control example of the present invention.

FIG. 4 is a block diagram showing an overall control system of the vehicle according to the present invention.

FIG. 5 is a chart showing an engagement operation table of a friction engagement device for setting each shift speed of the automatic transmission.

FIG. 6 is a schematic diagram showing a part of a hydraulic circuit for a second clutch.

FIG. 7 is a schematic diagram showing an upshift line and a downshift line between a second speed and a third speed.

FIG. 8 is a time chart when an upshift is performed after the conventional coast down control.

FIG. 9 is another time chart when an upshift is performed after the conventional coast down control.

[Explanation of symbols]

 A automatic transmission E engine 51 electronic control unit

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Yasuhiko Higashiyama 1 Toyota Town, Toyota City, Aichi Prefecture Inside Toyota Motor Corporation

Claims (2)

[Claims] When the output request for the power source falls below a predetermined value, the downshift point is set to a higher vehicle speed side than in the case of normal shift control to prompt a downshift, and the output request for the power source is reduced. In a control device for an automatic transmission for returning the downshift point to the vehicle speed in the case of the normal shift control by increasing to a predetermined value or more, the control for setting the downshift point to a high vehicle speed side is being executed. A coast-down control determining means for determining that there is an output request to the power source while the coast-down control determining means determines that the control for setting the downshift point to a higher vehicle speed side is being performed; Return detection means for detecting that the predetermined value or more has been reached; and a case where the rotation speed of the predetermined rotating member of the automatic transmission is a downshift point in a normal shift control. A rotational speed difference detecting means for detecting that the synchronous rotational speed after the upshift accompanying the return to the vehicle speed is equal to or more than a preset value; and a rotational speed of the rotating member by the rotational speed difference detecting means. And an upshift permitting means for permitting an upshift when it is detected that the synchronous rotation speed differs from the synchronous speed by more than the value. 2. An output request for a power source falls below a predetermined value, so that a downshift point is set to a higher vehicle speed side than in a case of normal shift control to promote a downshift. In a control device for an automatic transmission for returning the downshift point to the vehicle speed in the case of the normal shift control by increasing to a predetermined value or more, the control for setting the downshift point to a high vehicle speed side is being executed. A coast-down control determining means for determining that there is a high-speed shift stage from a low-speed shift stage to a high-speed shift stage sandwiching the downshift point. A control device for an automatic transmission, comprising: an upshift area setting means for setting a vehicle speed side higher than a downshift point set on the vehicle speed side.