JPH0571631A - Shift controller of automatic transmission - Google Patents

Abstract

PURPOSE:To keep off any shift shock attributable to what a frictional element moves for clamping inadvertently at a time when a driver has operated an accelerator pedal in the midway of gearshifting. CONSTITUTION:A servomechanism 35 of a 2-4 brake is provided with a clamping chamber 35b and a releasing chamber 35c. An accumulator 37 is connected to an oil passage 34 being interconnected to the clamping chamber 35b, and line pressure to be increased according to an increment of throttle valve opening acts on it as back pressure. At the time of gearshifting from a shift step, where hydraulic pressure is fed to both these clamping and releasing chambers 35b, 35c of the servomechanism 35, to another shift step where each hydraulic pressure in both these chambers is discharged, any increment in engine load is detected, and at time of this detection, discharge of the hydraulic pressure from the releasing chamber 35c is delayed to sane extent by means of closing control over a 3-2 timing valve 59. With this constitution, at time of the engine load increasing, even if the accumulator 37 is operated by the increment of back pressure and thereby the hydraulic pressure acts on the clamping chamber 35b, any possible operation at the clamping side of the servomechanism 35 is thus preventable.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to improvement of a shift control device for an automatic transmission, and more particularly to measures for reducing shift shock.

[0002]

2. Description of the Related Art Conventionally, as a shift control device for an automatic transmission, as disclosed in, for example, Japanese Patent Application Laid-Open No. 2-76968, a servo mechanism having both a fastening chamber and a release chamber as a friction element is used. In addition to providing an operating area difference between the two chambers, a spring is compressed in the release chamber to supply hydraulic pressure only to the fastening chamber when fastening the friction element, and to release both chambers when releasing. It is known that hydraulic pressure is supplied to or discharged from. Further, the above-mentioned publication includes a timing valve for adjusting the supply of hydraulic pressure to the engagement chamber of the servo mechanism or the discharge of hydraulic pressure from the disengagement chamber at the time of gear shifting, so that the engagement or disengagement operation of the friction element can be performed by other friction. It discloses that various gear shifting operations are preferably performed with less gear shifting shock in association with the operation of elements.

[0003]

By the way, in the friction element having the servo mechanism as described above, an accumulator is arranged in a hydraulic fluid passage to the fastening chamber of the servo mechanism, and a hydraulic pressure acting on the fastening chamber by the accumulator ( The tightening pressure) is adjusted to be moderate. The accumulator generally acts as a back pressure, which is a line pressure that increases as the throttle valve opening increases.

However, in the friction element provided with the servo mechanism in which the accumulator communicates with the engagement chamber as described above, the friction element is temporarily engaged when the driver depresses the accelerator pedal in order to accelerate during the gear shift. However, a shift shock may occur.

Therefore, the inventors of the present invention, as a result of diligent efforts to find out the cause thereof, became aware of the following contents. That is,
In the case of gear shifting, when the gear shifting is from a gear stage in which hydraulic pressure is supplied to both the engagement chamber and the release chamber of the servo mechanism to a gear stage in which the hydraulic pressure in both chambers is discharged, the gears from both chambers are released. Although the hydraulic pressure is gradually discharged through the throttle, etc., if the accelerator pedal is depressed during the discharge, the line pressure increases with an increase in the throttle valve opening and the back pressure of the accumulator increases. Therefore, the piston of the accumulator operates and the hydraulic pressure of the hydraulic oil passage to the engagement chamber of the servo mechanism rises, this hydraulic pressure acts on the engagement chamber, the friction element is temporarily engaged, and a shift shock occurs. I understood.

The present invention has been made in view of the above circumstances, and an object thereof is to open the throttle valve opening during a shift in which hydraulic pressure is discharged from both the engagement chamber and the release chamber of the servo mechanism of the friction element as described above. Even when the torque is increased, the temporary engagement of the friction element is prevented so that the gear shift can be favorably performed with less shift shock.

[0007]

In order to achieve the above object, according to the present invention, when a hydraulic pressure is applied to a fastening chamber of a servo mechanism due to an increase in line pressure, the releasing chamber is also opposed to the hydraulic pressure. A hydraulic pressure is applied to prevent the friction element from being fastened.

That is, the concrete solution means of the invention according to claim 1 is, as shown in FIG. 1, a release chamber 35c and a fastening chamber 3
5b and is arranged in the hydraulic oil passage 34 to the fastening chamber 35b of the friction element 18,
It is premised on a shift control device for an automatic transmission that includes an accumulator 37 in which a hydraulic pressure corresponding to an engine load acts as back pressure. Then, the release chamber 35c and the fastening chamber 35b
Shift detecting means 70 for detecting a shift time from a shift stage to which hydraulic pressure is supplied to another release stage in which the hydraulic pressure in the release chamber 35c and the fastening chamber 35b is discharged, and a load increase for detecting an increase in engine load. Detecting means 71 and the above-mentioned shift detecting means 7
When the engine load detected by the load increase detection means 71 increases during the shift detected by 0, the delay means 72 for delaying the discharge of the hydraulic pressure of the release chamber 35c of the friction element 18 is provided.

According to the second aspect of the invention, the load increase detection means 71 is specified to detect an increase in the engine load from the fully closed state of the throttle valve opening.

Further, in the invention described in claim 3, in the working oil passage of the friction element 18 to the release chamber 35c, an adjusting valve for adjusting the discharge of the oil in the working oil passage is arranged, and the above-mentioned claim 1 is also provided. The delay means 72 of the invention of 1) is configured to control the closing of the adjusting valve.

[0011]

With the above construction, in the invention of claim 1,
During a shift detected by the shift detecting means 70, the hydraulic pressure in the engagement chamber 35b and the disengagement chamber 35c of the friction element 18 is discharged to form a shift stage after the shift.

When the driver depresses the accelerator pedal to accelerate and the increase of the engine load is detected by the load increasing means 71 during the shift, the line pressure or the like is increased as the throttle valve opening increases. Hydraulic pressure increases,
Back pressure in the accumulator 37 (hydraulic pressure such as the above line pressure)
Is increased to increase the hydraulic pressure in the hydraulic oil passage 34 of the engagement chamber 35b of the friction element 18. Therefore, the hydraulic pressure acts on the engagement chamber 35b of the friction element 18 to try to engage the friction element 18, but at this time, the delay means 72 delays the discharge of the hydraulic pressure from the release chamber 35c of the friction element 18. As a result, the decrease in the hydraulic pressure in the release chamber 35c becomes gentle, and the increase in the hydraulic pressure acting on the fastening chamber 35b is opposed. As a result, the friction element 18 is not engaged and is maintained in the released state, so that the shift shock resulting from the engagement of the friction element 18 is effectively reduced.

In particular, according to the second aspect of the present invention, at the time of gear shifting in which the driver completely releases the accelerator pedal and the throttle valve opening is fully closed, the engine load of the engine load when the driver depresses the accelerator pedal again. At the time of increase, the back pressure of the accumulator 37 suddenly increases and the hydraulic pressure of the engagement chamber 35b of the friction element 18 rapidly increases, so that the friction element 18 tries to engage, but only at this time, the delay means 72 operates to cause friction. Since the discharge of the hydraulic pressure from the release chamber 35c of the element 18 is delayed, the temporary engagement of the friction element 18 is reliably prevented, and the gear shift shock that largely occurs is effectively reduced.

Further, according to the third aspect of the invention, since the discharge of the hydraulic pressure in the release chamber 35c is delayed by the closing operation of the adjusting valve arranged in the hydraulic oil passage of the release chamber 35c, the shift can be performed with a simple structure. Shock can be effectively reduced.

[0015]

As described above, according to the shift control device for an automatic transmission of the first aspect of the present invention, the friction element is temporarily operated due to an increase in the line pressure and the like due to the acceleration operation during the shift. It is possible to effectively reduce the shift shock due to the engagement of the friction element, since the engagement of the friction element is prevented.

In particular, according to the second aspect of the present invention, when the engine load increases during a gear shift with the throttle valve opening fully closed, a large hydraulic pressure acts on the engagement chamber of the friction element, Although the friction element is temporarily strongly engaged to cause a large gear shift shock, the friction element is effectively prevented from being engaged only in a situation where there is a strong demand for prevention of the gear shift shock. It can be effectively reduced.

Further, according to the third aspect of the invention, the delay of the decrease in the discharge of the hydraulic pressure of the release chamber corresponding to the increase of the hydraulic pressure of the engagement chamber of the friction element is arranged in the working oil passage of the release chamber. Since it is performed by the closing operation of No. 3, the shift shock can be effectively reduced with a simple configuration.

[0018]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 2 shows an automatic transmission having four forward gears and one reverse gear, where 1 is an engine output shaft and 2 is the engine output shaft 1.
A torque converter including a pump 2a, a stator 2b, and a turbine 2c connected to the stator 2
The b is fixed to the case 4 via a one-way clutch 3 for preventing the stator 2b from rotating in the opposite direction to the turbine 2c. Further, 5 is a converter output shaft 2d connected to the turbine 2c of the torque converter 2.
And a speed change gear device as a speed change mechanism connected to the.

The speed change gear device 5 includes a Ravigneaux type planetary gear mechanism 7 therein, and the planetary gear mechanism 7 has a small-diameter sun gear 8 and a large-diameter sun gear 9 arranged in front and rear, and a short-circuit meshing with the small-diameter sun gear 8. It comprises a pinion gear 10, a long pinion gear 11 that meshes with the large-diameter sun gear 9 and the short pinion gear 10, and a ring gear 12 that meshes with the long pinion gear 11. The small-diameter sun gear 8 has a forward clutch 1 arranged behind it.
5 and the first one-way clutch 16 connected in series to the clutch 15 to prevent reverse driving of the converter output shaft 2d, and the coast clutch 17 connected in parallel to these, the output shaft 2d of the torque converter 2
Is linked to. The large-diameter sun gear 9 is connected to the output shaft 2d of the torque converter 2 via a 2-4 brake 18 arranged obliquely rearward thereof and a reverse clutch 19 arranged rearward of the 2-4 brake 18. . Further, the long pinion gear 11 is provided with a low & reverse brake 21 for fixing the long pinion gear 11 via a rear carrier 20, and a second one-way permitting rotation of the long pinion gear 11 in the same direction as the engine output shaft 1. The clutch 22 is connected in parallel, and the front side carrier 23 of the clutch 22 is connected to the 3-4 clutch 2
It is connected to the output shaft 2d of the torque converter 2 via the shaft 4. Further, the ring gear 12 is connected to an output gear 25 arranged in front of it. In the figure, 27 is a lock-up clutch that directly connects the engine output shaft 1 and the converter output shaft 2d, and 28 is an oil pump driven by the engine output shaft 1 via an intermediate shaft 29. Further, a turbine rotation speed sensor 26 for detecting the rotation speed of the output shaft 2d is provided outside the output shaft 2d of the torque converter 2 and the engine output shaft 1
An engine rotation speed sensor 6 for detecting the rotation speed of the engine output shaft 1 is disposed outside the engine.

The following table shows the operating states of the clutches and brakes at each shift speed in the above configuration.

[0022]

[Table 1]

Next, the above friction elements 15, 18 and 21
FIG. 3 shows a hydraulic control circuit for controlling engagement / disengagement of the. In the figure, 30 is a pressure regulating valve that regulates the hydraulic pressure from the oil pump 28 to generate a line pressure proportional to the opening of the throttle valve, and 31 is a line pressure of the line pressure generated by the pressure regulating valve 30. It is a manual valve connected to the oil passage 30a. When the manual valve 31 is positioned at the "D" and "S" range positions, the input port a connected to the line pressure oil passage 30a communicates with the output port b and the output port d as shown in the drawing. When positioned in the "L" range position, the input port a is connected to the output port d.
And another output port c, and a low reducing valve 47 is communicatively connected to the output port c.

Further, 32 is a 1-2 shift valve, and the valve 32 has a 1-2 solenoid SOL1.
-When the solenoid SOL1 is turned on, the spool 32a is positioned at the upper position in the drawing, the oil passage 33 communicating with the output port d of the manual valve 31 is communicated with the oil passage 34 having the throttle portion 34a, and the low & reverse operation is performed. Brake 2
1 is turned on so as to drain the oil passage 50 communicating with 1, and the line pressure is introduced into the engagement chamber 35b of the servo mechanism 35 for controlling the 2-4 brake 18 via the oil passage 34, and the low & reverse brake 21 is released. On the other hand, when the 1-2 solenoid SOL1 is turned off, the spool 32a is positioned at the lower position in the figure, the oil passage 34 communicating with the fastening chamber 35b of the servo mechanism 35 is drained, and the spool 32a is communicated with the low reducing valve 47. OFF to connect the oil passage 51 to the oil passage 50 communicating with the low & reverse brake 21.
It operates so as to discharge the fastening pressure in the fastening chamber 35b of the servo mechanism 35 of the 2-4 brake 18 and to fasten the low & reverse brake 21.

Next, the internal structure of the servo mechanism 35 will be described. The servo mechanism 35 shown in FIG.
A piston 35a connected to the rod 35a via a rod 18a,
The piston 35a includes a hydraulic engagement chamber 35b and a release chamber 35c that are divided into upper and lower parts in the figure, and a spring 35d that is compressed in the release chamber 35c and biases the piston 35a toward the engagement chamber 35b. Then, the piston 35a
Is formed such that its pressure receiving area is larger in the release chamber 35c and smaller in the fastening chamber 35b. Due to the difference in the pressure receiving area, the action and inaction of the fastening pressure (line pressure) in the fastening chamber 35b is suppressed. Regardless, if the release pressure (line pressure) acts on the release chamber 35b, the piston 35a is released by the release pressure.
Is moved downward in the figure to operate the 2-4 brake 13 to the release side. When the 2-4 brake 18 is requested to be fastened, the piston 35c is moved upward in the drawing by introducing the fastening pressure into the fastening chamber 35b and discharging the release pressure from the release chamber 35c, so that the 2-4 brake 1
8 is configured to be fastened.

Servo mechanism 35 of the 2-4 brake 18
The action and non-action of the hydraulic pressure on the engagement chamber 35b and the release chamber 35c at each shift speed are as shown in the above table (in the table, ◯ indicates the action of the hydraulic pressure, and × indicates the non-action of the hydraulic pressure).

Therefore, as can be seen from the above table, during the downshift from the third speed to the first speed, the hydraulic pressure is supplied to both the engagement chamber 35b and the release chamber 35c of the servo mechanism 35 from the both chambers 35b. , 35c are discharged.

Further, in FIG. 3, the servo mechanism 35 is used.
A piston-type accumulator 37 that suppresses a sudden increase in the hydraulic pressure value of the fastening pressure to the fastening chamber 35b is arranged in the hydraulic fluid passage 34 that communicates with the fastening chamber 35b. The accumulator 37 includes a piston 37a, an oil chamber 37b for moving oil in the oil passage 34 to move the piston 37a leftward in the drawing,
A back pressure chamber 37c facing the oil chamber 37b is provided with a spring 37d that is compressed, and a back pressure (line pressure) acts on the back pressure chamber 37c through an oil passage 38.

Further, in the figure, reference numeral 45 is a 3-4 shift valve for controlling the action of hydraulic pressure on the release chamber 35c of the servo mechanism 35, and the valve 45 is a 3-4 solenoid.
An oil passage 48 which has SOL3 and communicates with the output port b of the manual valve 31 when the 3-4 solenoid SOL3 is OFF.
2-4 Release chamber 35c of servo mechanism 35 of brake 18
The line pressure (release pressure) is introduced to the release chamber 35c of the servo mechanism 35 of the 2-4 brake 24 via the oil passage 49 by being turned on so as to communicate with the oil passage 49 communicating with the.

Further, the forward clutch 15 is connected to the oil passage 5
5 through the oil passage 33 and the manual valve 31,
The line pressure (fastening pressure) is always introduced at each of the D, S, and L forward travel range positions.

Then, the inflow of oil from the oil passage 49 is introduced into the hydraulic oil passage 49 communicating with the release chamber 35c of the servo mechanism 35 of the 2-4 brake 18 (friction element) from the 3-4 shift valve 45. A throttle valve 49a for limiting and a throttle valve 49b for limiting the discharge are provided, and both throttle valves 4
An oil discharge oil passage 57 is connected to the release chamber 35c side of 9a and 49b, and a throttle valve 57a having a larger opening than the discharge side throttle valve 49b is interposed in the discharge oil passage 57. And the drain oil passage 57 is opened and closed.
A 3-2 timing valve 59 as an adjusting valve for adjusting the discharge of oil is interposed. The timing valve 59
Has a spool 59a, and a spring 59b is compressed at the left end of the spool 59a in the drawing, while a pilot chamber 59c is formed at the right end of the spool 59a in the drawing. A pilot oil passage 60 communicates with the pilot chamber 59c, and the oil passage 60 has a 3-2 down solenoid.
SOL4 is located. Also, the timing valve 59
Is provided with a drain port 59d, and is connected with a bypass oil passage 64 that bypasses the hydraulic oil passage 34 to the fastening chamber 35b of the servo mechanism 35. When the solenoid SOL4 is turned on, the pilot oil passage 60 is communicated with the tank 61, the spool 59b is positioned at the upper position in the drawing to communicate the discharge oil passage 57 with the drain port 59d, and the bypass oil passage 64 is connected. Connect upstream and downstream. on the other hand,
When the solenoid SOL4 is turned off, the pilot oil passage 6
0 is closed and the spool 59b is positioned at the lower position in the figure to close the discharge oil passage 57 and the bypass oil passage 64. Therefore, the release chamber 35c of the servo mechanism 35 of the 2-4 brake 18 during the 3 → 1 downshift
Release pressure goes through the throttle portion 49b and the 3-4 shift valve 45
3-2 Down solenoid SOL4 O when discharged from
By discharging the release pressure from the 3-2 timing valve 59 through the discharge oil passage 57 by N control, the discharge of the release pressure from the release chamber 35c is adjusted.

Next, the 3-2 down solenoid SOL4 is turned on.
FIG. 4 shows the ON / OFF control, that is, the release control of the release pressure of the servo mechanism 35 of the 2-4 brake 18 during the 3 → 1 downshift.
The control flow will be described.

After the start, in step S1, the opening time of the 3-2 timing valve 59, that is, the ON time TIME of the 3-2 down solenoid SOL4 is initialized to TIME = 0, and then in step S2, on the shift diagram. Whether or not gear shifting is necessary is determined based on the current driving state.

Then, in step S3, it is determined from the above determination result whether or not the 3 → 1 downshift is being performed. If not, the shift control for a shift other than the 3 → 1 shift is performed in step S9. And returns to step S2. On the other hand, 3 →
If the 1-down shift is being performed, it is determined in step S4 whether or not the 3 → 1 down shift is started. If the shift is started, the 3-2 down solenoid SOL4 is turned off in step S5.
Set N time TIME to a sufficiently long time T (TIME =
T)

After that, in step S6, the ON time T
The value of IME is determined, and since TIME> 0 at the beginning,
The 3-2 down solenoid SOL4 is ON-controlled in step S7, and the ON time TIME is subtracted by "1" in step S8. Then, in step S9, another control for the 3 → 1 downshift is performed.

From the next time onward, the determination in step S4 is not the start of the 3 → 1 downshift, so step S10
Then, the throttle valve opening value THVOL (i-1) between the previous time and this time
, THVOL (i) is compared with the set value TVO near the fully closed state, and THVOL (i-1) <TVO and THVOL (i)>
If it is not TVO, that is, the throttle valve opening is the set value T
If it is not during the acceleration operation that increases more than VO, the process directly proceeds to step S6 to continue ON control of the 3-2 down solenoid SOL4, and when TIME = 0, the process proceeds from step S6 to S12. 3-2 Terminate the ON control of the down solenoid SOL4 and control it to OFF.

On the other hand, in step S10, THV
OL (i-1) <TVO and THVOL (i)> During the acceleration operation of TVO, even if the ON time TIME has not elapsed, the value of the ON time TIME is forcibly set to TIME = 0 in step S11. After setting, the process proceeds to steps S6 and S12 to control the 3-2 down solenoid SOL3 to OFF.

Therefore, in the control flow of FIG.
In step S3, the release chamber 35c and the engagement chamber 3 are moved from the third forward speed to which the hydraulic pressure is supplied to the release chamber 35c and the engagement chamber 35b of the servo mechanism 35 of the 2-4 brake 18.
The shift detecting means 70 is configured to detect a 3 → 1 down shift to the first shift stage in which the hydraulic pressure of 5b is discharged. Further, in step S10 of the control flow, the load increase detection means 71 is configured to detect the increase in the engine load based on the increase change in the throttle valve opening from the fully closed state of the throttle valve opening. Furthermore,
At step S11, when the engine load increases due to the increase in the throttle valve opening detected by the load increase detecting means 71 during the 3 → 1 downshift detected by the shift detecting means 70, the 3-2 timing valve 59 Is forcibly controlled to be closed to discharge the hydraulic pressure of the release chamber 35c of the servo mechanism 35 of the 2-4 brake 18 only from the throttle portion 49b of the hydraulic oil passage 49, and delay the discharge of the hydraulic pressure. The delay means 72 is configured.

Therefore, in the above-described embodiment, at the third forward speed, the engagement chamber 35b of the servo mechanism 35 of the 2-4 brake 18 receives oil from the 1-2 shift valve 32 due to the ON state of the 1-2 solenoid SOL1. The fastening pressure acts through the passage 34, and the release chamber 35c of the servo mechanism 35
3-4 depending on the OFF state of 3-4 solenoid SOL3
The release pressure is applied from the shift valve 45 through the oil passage 49. Therefore, the piston 35a of the servo mechanism 35 moves downward in FIG.
The brake 18 is in the released state.

Now, when the 3 → 1 downshift is performed,
By switching the 1-2 solenoid SOL1 to the OFF operation, the hydraulic oil passage 34 to the fastening chamber 35b of the servo mechanism 35 is set to 1.
-2 through the lower position of the shift valve 32 to communicate with the drain port. At the same time, 3-4 solenoid
When the SOL3 is switched to the ON operation, the hydraulic oil passage 49 to the release chamber 35c of the servo mechanism 35 communicates with the drain port via the upper position of the 3-4 shift valve 45. Further, as shown in FIG. 5, since the 3-2 down solenoid SOL4 is turned on and the 3-2 timing valve 59 is switched to the upper position, the discharge oil passage 57 communicates with the drain port 59a of the valve 59, and The upstream and downstream of the bypass oil passage 64 communicate with each other. As a result, the hydraulic pressure in the engagement chamber 35b of the servo mechanism 35 of the 2-4 brake 18 is 1-from the bypass oil passage 64.
The hydraulic pressure in the release chamber 35c of the servo mechanism 35 is discharged from the discharge oil passage 57 while being discharged through the 2 shift valve 32.
-Exhausted through the timing valve 59.

At this time, during acceleration when the driver depresses the accelerator pedal to perform acceleration operation, the line pressure rises, and this line pressure is the fastening chamber 35b of the servo mechanism 35.
The piston 37 of the accumulator 37 acts as back pressure on the accumulator 37 communicating with the oil passage 34 to the
3a moves to the right in FIG. 3 to increase the hydraulic pressure of the oil passage 34 to the fastening chamber 35b, and this hydraulic pressure acts on the fastening chamber 35b of the servo mechanism 35, and the fastening pressure is indicated by a broken line in FIG. Temporarily rise to.

However, at that time, as shown in the same figure, when the throttle valve opening exceeds the set value TVO, 3-2
Solenoid SOL4 is controlled to OFF from ON operation, and 3-
The 2 timing valve 59 is closed and the discharge passage 57 is closed. At this time, the bypass passage 64 is also closed at the same time, and the hydraulic pressure to the fastening chamber 35b of the servo mechanism 35 also rises as shown by the solid line in FIG. Since the oil is gradually discharged through only the throttle valve 49b, the decrease in the oil pressure in the release chamber 35c is delayed and the increase in the oil pressure in the engagement chamber 35b is opposed to the servo mechanism 35. No, 2
The temporary engagement operation of the -4 brake 18 is effectively prevented. Therefore, the shift shock caused by the temporary engagement operation of the 2-4 brake 18 can be effectively reduced.

Although the above embodiment is applied to the 3 → 1 downshift, it goes without saying that the present invention is not limited to this shift.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of an invention according to claim 1.

FIG. 2 is a skeleton diagram of an automatic transmission.

FIG. 3 is a diagram showing a main part of a hydraulic control circuit of an automatic transmission.

FIG. 4 is a flowchart showing an open control of a 3-2 timing valve at the time of 3 → 1 shift.

FIG. 5 is an operation explanatory view.

[Explanation of symbols]

 18 2-4 Brake (friction element) 34, 39 Hydraulic oil path 35 Servo mechanism 35b Fastening chamber 35c Release chamber 37 Accumulator 57 Discharge oil path 59 3-2 Timing valve (regulating valve) 70 Shift detecting means 71 Load increase detecting means 72 delay means

Claims (3)

[Claims] 1. A friction element having a release chamber and a fastening chamber, and an accumulator arranged in a hydraulic oil passage to the fastening chamber of the friction element and acting as a back pressure by a hydraulic pressure corresponding to an engine load. A shift control device for an automatic transmission, which detects a shift time from a shift stage where hydraulic pressure is supplied to the release chamber and the engagement chamber to another shift stage where hydraulic pressure in the release chamber and the engagement chamber is discharged. Means, load increase detection means for detecting an increase in engine load, and when the engine load detected by the load increase detection means increases during a shift detected by the shift detecting means, the friction element release chamber A shift control device for an automatic transmission, comprising: a delay unit that delays discharge of hydraulic pressure. 2. The shift control device for an automatic transmission according to claim 1, wherein the load increase detection means detects an increase in engine load from the fully closed state of the throttle valve opening. 3. A hydraulic fluid passage to the release chamber of the friction element is provided with a regulating valve for regulating discharge of oil from the hydraulic fluid passage,
The shift control device for an automatic transmission according to claim 1 or 2, wherein the delay means controls to close the adjusting valve.