JP2001241543A - Control method for automatic transmission - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method of controlling an automatic transmission which can improve the feeling of a deceleration to shorten the duration of the torque phase as well as reducing a shifting shock and shortening shift time. SOLUTION: In the automatic transmission having a first engagement element and a second engagement element, a controller can shift a gear to a higher speed stage from a lower speed stage by engaging the first engage element and disengaging the second engaging element. Furthermore, the controller provides a process controlling a feedback so that an input revolution will be a higher target value than an input revolution at the low stage step by reducing a hydraulic fluid pressure in the second engagement element, a process to lower the input revolution by increasing the hydraulic fluid pressure in the first engage element maintaining the feedback control, and a process extending the inclination of a depression gradient of the second engagement element than the previous gradient at the point that the input revolution is lowered than the input revolution at the low speed stage.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for controlling an automatic transmission, and more particularly to a method for controlling a shift from a low gear to a high gear.

[0002]

2. Description of the Related Art Conventionally, shifting from a low gear to a high gear (for example, shifting from second gear to third gear, third gear to fourth gear) by engaging one engaging element and releasing another engaging element. There is an automatic transmission that performs the following. In this case, it is difficult to smoothly switch the torque transmission path from the disengagement side engagement element to the engagement side engagement element, and the shift time becomes longer,
There is a problem that a shift shock occurs.

In order to solve such a problem, the hydraulic pressure of the disengagement side engaging element is reduced to perform feedback control so that the input rotation speed becomes higher than the input rotation speed in the low speed stage by a constant value. An automatic transmission has been proposed in which the input rotation speed is reduced by increasing the hydraulic pressure of the engagement element on the engagement side while maintaining the speed, thereby performing a smooth shift (Japanese Patent Publication No. 7-51984). .

FIG. 9 shows an example of a conventional shift control method.
FIG. 9 shows temporal changes in the hydraulic pressure of the engagement element, the input rotation speed (turbine rotation speed), and the output shaft torque during a shift from a low-speed stage to a high-speed stage. As is clear from the figure, first (1)
Input speed hydraulic and vacuum engagement element is feedback controlled to a constant value r ₁ is higher by the target value than the input rotation speed V ₂ in the low speed stage of the release side as shown in the region of. Then, while maintaining the feedback control as in (2), the hydraulic pressure of the engagement element on the engagement side is increased to decrease the input rotation speed. Eventually, as shown in (3), a region called a torque phase in which the vehicle acceleration decreases appears, and the rate of decrease in the input rotation speed becomes slow. Thereafter, since the input rotation speed departs from the initial target rotation speed, the disengagement side engaging element is further depressurized in an attempt to increase the input rotation speed, exits the torque phase, ends the feedback control, and releases the engagement on the disengagement side. The element is completely released. Then, at time t ₁ , the input rotation speed decreases to the input rotation speed V ₃ in the high speed stage, and the shift is completed.

[0005]

The above control has the effect of shortening the shift time and reducing the shift shock as compared with the conventional control. However, since the torque phase period is relatively long, it is unpleasant. There is a problem that a feeling of deceleration remains.

SUMMARY OF THE INVENTION An object of the present invention is to provide an automatic transmission control method capable of shortening a shift time and reducing a shift shock, shortening a period of a torque phase, and improving a feeling of deceleration.

[0007]

In order to achieve the above object, the present invention according to claim 1 has a first and a second engaging element, and engages the first engaging element and the second engaging element. In the automatic transmission configured to shift from the low gear to the high gear by releasing the engaging element, the hydraulic pressure of the second engaging element is reduced to make the input rotational speed constant from the input rotational speed in the low gear. Performing a feedback control so as to attain a target value that is higher by a value, increasing the oil pressure of the first engagement element to reduce the input speed while maintaining the feedback control, and Making the pressure reduction gradient of the second engagement element greater than the pressure reduction gradient before the time point when the input rotation speed falls below the input rotation speed of the automatic transmission.

In shifting from the low gear to the high gear, feedback control is performed such that the hydraulic pressure of the second engagement element is reduced so that the input speed becomes a target value that is higher than the input speed in the low speed by a fixed value. I do. Then, while maintaining the feedback control, the hydraulic pressure of the first engagement element is increased to decrease the input rotation speed. These steps are the same as in the related art. When the input speed falls below the input speed in the low speed stage, a deceleration range called a torque phase occurs,
In the present invention, the pressure reduction gradient of the second engagement element in this torque phase is made larger than the pressure reduction gradient before the torque phase.
Therefore, the period of the torque phase can be shortened, and the feeling of deceleration in the torque phase is improved.

As a method of increasing the pressure reduction gradient of the second engagement element in the torque phase from the pressure reduction gradient before the torque phase, as described in claim 2, after the time when the input rotation speed becomes lower than the input rotation speed in the low speed stage. Is preferably higher than the previous feedback target value. That is, the feedback target value in the torque phase is set higher than the feedback target value before the torque phase. As a method of increasing the pressure reduction gradient of the second engagement element in the torque phase from the pressure reduction gradient before the torque phase, a method of increasing the feedback gain may be considered in addition to the method of increasing the target value. If erroneous determination is made, there is a risk that the input rotation speed may increase due to feedback hunting. On the other hand, if the method is to increase the target value as in claim 2,
Since the hunting is small and does not rise above the target value at least as compared with the method of increasing the feedback gain, it is advantageous for the input rotation rising at the time of erroneous determination. In addition, as a method of increasing the pressure reduction gradient of the second engagement element in the torque phase from the pressure reduction gradient before the torque phase, there are a method of increasing the target value, a method of increasing the feedback gain, and a method of increasing the feedback gain at the start of the torque phase. There is also a method of ending the control.

[0010]

FIG. 1 shows an example of an automatic transmission for a vehicle according to the present invention. This automatic transmission includes a torque converter 1, an input shaft 2, to which engine power is transmitted via the torque converter 1, three clutches C1 to C3, two brakes B1, B2, a one-way clutch F, a Ravigneaux type planetary gear. A mechanism 4, an output gear 5, an output shaft 7, a differential device 8, and the like are provided. In this embodiment, the first engagement element engaged when shifting from the low gear to the high gear in the present invention refers to the C3 clutch, and the disengaged second engagement element refers to the B1 brake.

The forward sun gear 4a of the planetary gear mechanism 4
Is connected to the input shaft 2 via a C1 clutch, and the forward sun gear 4a is connected to the transmission case 6 via a B1 brake. The rear sun gear 4b is C
It is connected to the input shaft 2 via two clutches. The carrier 4c is connected to the input shaft 2 via the intermediate shaft 3 and the C3 clutch.
Is linked to The carrier 4c is connected to the transmission case 6 via a B2 brake and a one-way clutch F that allows only the forward rotation (engine rotation direction) of the carrier 4c. The carrier 4c supports two types of pinion gears 4d and 4e, the forward sun gear 4a meshes with a long pinion 4d having a long shaft length, and the rear sun gear 4b meshes with a long pinion 4d via a short pinion 4e having a short shaft length. . Long pinion 4d
The ring gear 4 f that meshes with only the output gear 5 is connected to the output gear 5. The output gear 5 is connected to a differential 8 via an output shaft 7.

The automatic transmission has clutches C1, C2,
C3, brakes B1, B2 and one-way clutch F
As shown in FIG. 2, four forward speeds and one reverse speed are realized by the operation of. In FIG. 2, ● indicates the operation state of the hydraulic pressure. The B2 brake is engaged at the time of reverse and the first speed, but is engaged at the first speed only in the L range. FIG. 2 also shows operating states of first to fourth solenoid valves (SOL1 to SOL4) 22 to 25 described later. ○ indicates an energized state, X indicates a non-energized state, and △ indicates a temporary energized state. This operation table shows the operation in the steady state.

FIG. 3 shows an example of a hydraulic control device used in the automatic transmission. The hydraulic control device includes an oil pump 10, a regulator valve 11, a manual valve 1
2. Solenoid modulator valve 13, sequence valve 15, fail-safe valve 16, B1 pressure control valve 17, C2 pressure control valve 18, C2 lock valve 1.
9, C3 pressure control valve 20, B2 pressure control valve 21, first to fourth solenoid valves 22 to 25, electronic control unit 3
0 or the like. The electronic control unit 30 receives signals relating to the vehicle operating state such as the throttle opening, the vehicle speed, the rotational speed of the input shaft 2 (turbine rotational speed), and the shift position for detecting the position of the shift lever. The first to fourth solenoid valves 22 to 2
5 is controlled.

The first solenoid valve 22 is for B1 brake control, the second solenoid valve 23 is for C2 clutch control, and the third solenoid valve 24 is for C3 clutch control and B2 brake control. Third
The reason that the solenoid valve 24 serves both for controlling the C3 clutch and for controlling the B2 brake is that the B2 brake does not operate in the D and 2 ranges but is used only for the engine brake control in the L range and the transient control in the R range. This is because they do not interfere with the C3 clutch operated in the D range. The fourth solenoid valve 25 is a valve for switching the sequence valve 15 at the time of switching transition between the L range (first speed) and the R range. As described above, since the first to third solenoid valves 22 to 24 need to perform delicate hydraulic control, a duty solenoid valve or a linear solenoid valve is used, and the fourth solenoid valve 25 is an ON / OFF switching valve. Good.

The regulator valve 11 is an oil pump 1
The discharge pressure of 0 a valve pressure regulated to a predetermined line pressure P _L, the manual valve 12, and supplies the line pressure P _L to the solenoid modulator valve 13, B2 pressure control valve 21. As shown in FIG. 4, the regulator valve 11 includes a spool 11b urged rightward by a spring 11a, and a plug 11c separate from the spool 11b is provided at the left end. The discharge pressure of the oil pump 10 is input to the port 11d, and the port 11e is connected to the suction side of the oil pump 10. The line pressure P _L is fed back to the right end of the port 11f. The C1 clutch pressure _PC1 is input to the left end port 11h only during reverse (R), and the line pressure during reverse is adjusted to be higher than during forward travel.

The manual valve 12 changes the spool 12a to L, 2, D, N,
The range can be switched between R and P. Then, selectively outputs the line pressure P _L input from the input port 12b from the output port 12c, or the output 12d for backward for forward.

The solenoid modulator valve 13 is a valve for supplying a constant original pressure to each of the solenoid valves 22 to 25, and has a spool 13b urged leftward by a spring 13a as shown in FIG. The input port 13c is input line pressure P _L from regulator valve 11, the solenoid modulator pressure Psm each solenoid valve 22-2 from the output port 13d
5 and output to the right end signal port 19c of the C2 lock valve 19. The port 13e is a drain port. The output pressure Psm is fed back to the left end port 13f, whereby the solenoid modulator pressure Ps
m is adjusted to a hydraulic pressure corresponding to the load of the spring 13a.

The B1 pressure control valve 17 is a pressure regulating valve for controlling the B1 brake pressure P _B1 , as shown in FIG.
Spool 1 urged left by spring 17a
7b, and the signal pressure P _s1 is input from the first solenoid valve 22 to the left end port 17c. Port 17d is a drain port. Output port 17e is B
The input port 17f is connected to a port 16i of a fail-safe valve 16 described later. Further, the output pressure P _B1 is fed back to the right end port 17h. Therefore, the output pressure P _B1 becomes the signal pressure P
_The pressure is adjusted to the oil pressure proportional to _s1 .

The fail-safe valve 16 is a valve for preventing multiple meshing (interlock) in which the C2 and C3 clutches and the B1 brake are simultaneously engaged during traveling in the D range. Specifically, the solenoid valve 22
3 engaging elements C2, C3, B due to malfunctions of ~ 25, failure of electronic control circuit, sticks of various valves, etc.
When the hydraulic pressure is simultaneously supplied to the first gear, the third gear state is forcibly set by releasing the hydraulic pressure P _{B1 of the} B1 brake. The fail-safe valve 16 includes a spool 16b urged rightward by a spring 16a as shown in FIG. 5, and the spool 16b is normally in the right position as shown in the upper part of the drawing, Only at the time of switching transition and at the time of interlock, it switches to the left side as shown in the lower part of the drawing. The right end port 16c has a C3 clutch pressure _Pc3 or R
Range pressure P _R is selectively input, the port 16d C
The two-clutch pressure P _C2 is input, the B1 brake pressure P _B1 is input to the port 16e, and the spool 16b is pushed leftward by these oil pressures. The left end of the port 16j accommodating the spring 16a the line pressure P _D at the time of forward movement is constantly input, the line pressure P _D at the time of even advanced port 16h is input through the sequencing valve 15. for that reason,
These oil pressures push the spool 16b rightward.
The port 16i is an input port 17 of the B1 pressure control valve 17.
f. Port 161 is a drain port. The fail-safe valve 16 has a reverse hydraulic pressure, ie, C, as shown in FIG.
A port 16f to which one clutch pressure _PC1 is input, a port 16g connected to the drain port 21d of the B2 pressure control valve 21, a drain port 16k, and the like are provided.

The sequence valve 15 has a function of ensuring the first speed when the operation of the second solenoid valve 23 or the C2 pressure control valve 18 is defective. Further, since the third solenoid valve 24 is also used for controlling the C3 clutch and the B2 brake, the B2 pressure control valve 21 and the C3 pressure control valve 2 are used.
Function of switching the source pressure of 0, function of guiding the R range pressure P _R to the right port 16c of the fail-safe valve 16 at the time of transition for change to the reverse range, B2 source pressure of the B1 brake pressure and the C3 clutch pressure when the action of the brake pressure And the like. As shown in FIG. 6, the valve 15 includes a spool 15b urged leftward by a spring 15a, and is controlled by a signal pressure P _S4 of a fourth solenoid valve 25 input to a signal port 15c at the left end. It switches to the direction. That is, the spool 15b is switched to the right only at the first speed of the L range and at the time of transition to the R range as shown in the lower part of the drawing. The port 15d receives the C2 clutch pressure P from the C2 pressure control valve 18.
_C2 is input, and port 15e is connected to the C2 clutch. Line pressure P _D at the time of forward movement from the manual valve 12 is input to the port 15f. Port 15g is connected to port 16h of fail-safe valve 16,
And it outputs the line pressure P _D at the time of forward. Port 15h is a drain port. The B2 brake pressure P _B2 is input from the B2 pressure control valve 21 to the port 15i,
5j is connected to the B2 brake. The port 15k line pressure P _R at the time of retraction are input is also connected to it C1 clutch. The port 151 is connected to the right end port 16c of the fail-safe valve 16, and the port 1
5m is connected to the C3 clutch.

The B2 pressure control valve 21 is a pressure regulating valve for controlling the B2 brake pressure P _B2 , and has a spool 21b urged leftward by a spring 21a.
From the third solenoid valve 24 to the left end port 21c,
When the signal pressure P _S3 is input at the time of the range, the port 21 d
Is connected to the port 16g of the fail-safe valve 16. The port 21e is connected to the B2 brake via the sequence valve 15, and has a role of supplying the oil pressure P _B2 to the B2 brake at the time of the first shift of the L range and at the time of transition to the R range. The line pressure P _L is input to the port 21f, and the output pressure P _B2 is fed back to the right end port 21g containing the spring 21a.

Since the port 21d is connected to the C1 clutch via the fail-safe valve 16 during forward running, it is drained. Also, left end port 2
1c, the signal pressure P of the third solenoid valve 24
_{Since S3 is} also drained, the spool 21b is at the left end position as shown in the lower part of FIG. Therefore, the hydraulic pressure P _B2 to the B2 brake is also drained.

On the other hand, at the time of transition from the P, N range to the R range, the fourth solenoid valve 25 is temporarily turned on.
Therefore, the sequence valve 15 is temporarily switched to the right side, and the right end port 16
By high receding pressure P _R to c is input, the fail-safe valve 16 also temporarily switched to the left side, the port 21d of the B2 pressure control valve 21 is drained. Also,
Since the signal pressure P _S3 is input from the third solenoid valve 24 to the left end port 21c, the spool 21b is held at the position shown in the upper part of FIG. 6, and the output pressure P _B2 is proportional to the signal pressure P _S3 and the line pressure. The pressure is adjusted to a hydraulic pressure lower than P _L.
As described above, the B2 pressure control valve 21 has a function of gradually increasing the hydraulic pressure P _B2 to the B2 brake during the transition to the R range, that is, reducing the switching shock by delaying the engagement from the C1 clutch. are doing.

The C2 pressure control valve 18 has a C2 clutch pressure P
_This is a valve for controlling _C2 . The spool 18 is biased leftward by a spring 18a as shown in FIG.
b. The line pressure P _D during forward movement is input to the input port 18c, and the C2 clutch pressure P _C2 is output from the output port 18d. Line pressure P _D at the time of the signal pressure P _s2 or advancement of the second solenoid valve 23 via the C2 lock valve 19 at the left port 18e is input. In addition,
18f is a drain port. Output pressure P _C2 is fed back to the right end port 18g spring 18a is accommodated, the output pressure P _C2 is pressure is adjusted to a hydraulic proportional to the signal pressure P _s2.

The C2 lock valve 19 supplies the signal pressure _Ps2 of the second solenoid valve 23 to the left end port 18e of the C2 pressure control valve 18 at the time of starting transition, and is maximum during traveling (first to third speeds). a valve for switching to supply the hydraulic pressure P _D. The lock valve 19 has a spool 19b urged rightward by a spring 19a as shown in FIG. 7, and is pushed leftward by a solenoid modulator pressure Psm input to a signal port 19c at the right end. The input port 19d has a line pressure P _D during forward movement.
Is input, and the output port 19e is connected to the C2 pressure control valve 18.
Is connected to the left end port 18e. Then, the left two ports 19f, the 19g is input the signal pressure P _s2 of the second solenoid valve 23. Starting at the beginning, since the signal pressure P _s2 of the second solenoid valve 23 is lower than the solenoid modulator pressure Psm, the spool 19b is in the left position, the port 19 g, signal at the left end port 18e of the C2 pressure control valve 18 via 19e By supplying the pressure P _s2 , the C2 clutch is controlled to slip, and the vehicle starts gently. on the other hand,
After the transition to complete to the running state of the start, since the P _s2 = Psm, spool 19b is switched to the right position by a spring 19a, the line pressure P _D during forward is supplied to the left port 18e of the C2 pressure control valve 18 To securely engage the C2 clutch. Further, in the fourth speed state, the signal pressure _Ps2 of the second solenoid valve 23 is drained, so that the spool 19b is in the left position and the port 19
The left end port 18e of the C2 pressure control valve 18 is drained via g and 19e, and the C2 clutch is released.

The C3 pressure control valve 20 is a valve for controlling the C3 clutch pressure _PC3 , and as shown in FIG. 7, a spool 20b urged leftward by a spring 20a.
It has. The left end port 20c is connected to the third solenoid valve 24, and receives a signal pressure _Ps3 thereof. Therefore, at the first and second speeds, the spool 20b is at the lower position in FIG. 7, and at the third and fourth speeds, the spool 20b is at the upper position in FIG. Port 20d is a drain port, port 2
0e is the output port connected to the C3 clutch, and the port 20f line pressure P _D at the time of forward movement is input. The output pressure _PC3 is fed back to the right end port 20g in which the spring 20a is disposed.

Next, at the time of shifting from the second speed to the third speed, C
The hydraulic control of the three clutches (first engagement element) and the B1 brake (second engagement element) will be described with reference to FIG. In FIG. 8, the control of the areas (1) and (2) is the same as in FIG. In other words, in the region (1), the hydraulic pressure of the release-side B1 brake is reduced, and the input rotational speed is higher than the input rotational speed V2 at the _second speed by a constant value r ₁ (for example, about 50 rpm) (the initial target value). a feedback control so as to be referred to as R _1). Next, while maintaining the feedback control as in (2), the hydraulic pressure of the C3 clutch on the engagement side is increased to reduce the input rotation speed. Eventually, as shown in (3) ′, a region where the vehicle acceleration decreases, called a torque phase, appears, and the decreasing speed of the input rotation speed becomes slow. The torque phase, as indicated by a broken line, the feedback target value of the torque phase (referred to as a second target value R ₂₎ a set higher than the torque phase previous initial target value R _1. In other words, to increase by a constant value r ₂ than the input rotation speed V ₂ in the second speed. Since the deviation between the input speed and the second target value R ₂ at this time is large, (3) an attempt to increase the input rotational speed as the ', B1 brake release side are reduced pressure at (3) in FIG. 9 The pressure is reduced with a gradient greater than the gradient. As a result, it is possible to escape from the torque phase in a short time, and it is possible to improve the feeling of deceleration. Incidentally, the end of the torque phase, when the input speed is a predetermined value than the input rotation speed V ₂ at the second speed (for example, about 30 rpm) or becomes lower may be determined to be terminated. Upon completion of the torque phase, to exit the feedback control, with the withdrawn oil pressure B1 brake release side, increases the hydraulic pressure of the C3 clutch engaging side, the input rotation speed at time t ₁ is rotated input in third speed It decreased to several V _3, to complete the shift. In FIG. 8, the feedback target value is increased stepwise in order to be higher than the initial target value. However, the feedback target value may be increased gradually by providing a rising gradient, or may be increased in multiple steps in a stepwise manner. .

FIG. 8 illustrates the hydraulic control of the C3 clutch and the B1 brake during the shift from the second speed to the third speed. However, the present invention relates to the control of the C2 clutch and the B1 brake during the shift from the third speed to the fourth speed. It can also be applied to hydraulic control. That is, as is apparent from FIG. 2, when shifting from the third speed to the fourth speed, the C2 clutch is released and the B1 brake is engaged, and in this case, the B1 brake becomes the first engagement element. , C2 clutch is the second engagement element.

In the automatic transmission according to this embodiment, the speed is changed from the first speed to the second speed.
At the time of shifting to the first speed, the function of the one-way clutch F is used, and the engagement and disengagement of the engagement elements are not performed, but the engagement and disengagement of the two engagement elements are performed at the time of shifting from the first speed to the second speed. The present invention can be applied to an automatic transmission.

In the above embodiment, three clutches C1 to C
Although the automatic transmission having three and two brakes B1 and B2 has been described, the present invention is not limited to this, and has at least two engagement elements, and one of the engagement elements when shifting from a low gear to a high gear. And any other automatic transmission that releases the other engagement element. The hydraulic control valves of the B1 brake and the C3 clutch are connected to the spool valve 17,
Although the configuration is made by combining the solenoid valve 20 and the solenoid valves 22 and 24, it may be configured by a single solenoid valve. As the solenoid valve in this case, a known solenoid valve such as a duty solenoid valve or a linear solenoid valve can be used.

[0031]

As is apparent from the above description, according to the present invention, when shifting from a low gear to a high gear,
By reducing the hydraulic pressure of the disengagement side engagement element, feedback control is performed so that the input rotation speed becomes a target value that is higher than the input rotation speed in the low speed stage by a certain value. Since the input rotation speed is reduced by increasing the oil pressure of the combined element, the shift time can be shortened and the shift shock can be reduced.
In addition, since the pressure reduction gradient of the disengagement side engagement element in the torque phase is made larger than the pressure reduction gradient before the torque phase, the effect of reducing the period of the torque phase and improving the feeling of deceleration during shifting can be achieved. .

[Brief description of the drawings]

FIG. 1 is a schematic mechanism diagram of an example of an automatic transmission for a vehicle according to the present invention.

FIG. 2 is an operation table of each engagement element and a solenoid valve of the automatic transmission of FIG. 1;

FIG. 3 is an overall circuit diagram of a hydraulic control device of the automatic transmission shown in FIG.

FIG. 4 is a circuit diagram of a regulator valve, a manual valve, and a solenoid modulator valve in the hydraulic control device of FIG. 3;

FIG. 5 is a circuit diagram of a B1 pressure control valve and a fail-safe valve in the hydraulic control device of FIG.

6 is a circuit diagram of a fail-safe valve, a sequence valve, and a B2 pressure control valve in the hydraulic control device of FIG.

FIG. 7 is a circuit diagram of a C2 pressure control valve, a C2 lock valve, and a C3 pressure control valve in the hydraulic control device of FIG. 3;

FIG. 8 is a time change diagram of the hydraulic pressure, the input rotation speed, and the output shaft torque of the C3 clutch and the B1 brake during the shift from the second speed to the third speed according to the invention.

FIG. 9 is a time change diagram of a hydraulic pressure, an input rotation speed, and an output shaft torque of an engagement element during a shift from a low gear to a high gear according to the related art.

[Explanation of symbols]

 C3 clutch (first engagement element) B1 brake (second engagement element) 17 B1 pressure control valve 20 C3 pressure control valve 22, 24 solenoid valve 30 Electronic control unit

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Joe Hashime 2-1-1 Taoyuan, Ikeda-shi, Osaka Daihatsu Kogyo Co., Ltd. F-term (reference) 3J052 AA01 AA04 CA09 CA33 GC44 HA02

Claims (2)

[Claims] A shift from a low gear to a high gear is provided by having first and second engagement elements, engaging the first engagement element and releasing the second engagement element. Reducing the oil pressure of the second engagement element and performing feedback control so that the input rotation speed becomes a target value that is higher than the input rotation speed in the low speed stage by a fixed value, and maintaining the feedback control. A step of increasing the oil pressure of the first engagement element to reduce the input rotation speed; and a step of reducing the input rotation speed from the input rotation speed in the low-speed stage to the second rotation.
Making the pressure reduction gradient of the engagement element of the second embodiment larger than the previous pressure reduction gradient. 2. The method according to claim 1, wherein the input speed is lower than the input speed in the low speed stage, so that the pressure reduction gradient of the second engagement element after the time when the input speed is lower than the input speed in the low speed stage is larger than the previous pressure reduction gradient. The control method for an automatic transmission according to claim 1, wherein a feedback target value after the time point when the input rotation speed falls below the input rotation speed is set higher than a feedback target value before that time point.